Clinical efficacy of resin-based direct posterior restorations and glass-ionomer restorations – An updated meta-analysis of clinical outcome parameters

Evaluation of a quadwave curing light compared to a dual-peak LED curing light

OBJECTIVE

To determine if the PinkWave (PW) light-curing unit (LCU) that emits red and infrared (IR) light as well as violet and blue light improves the depth of cure and degree of conversion (DC) of resin-based composites (RBCs).

METHODS

The DC of RBCs at various distances was calculated from data collected at a rate of 13 Hz using attenuated total reflectance Fourier-transform infrared spectroscopy. To assess the contributions of the different wavelengths of light, optical filters were used to block the red and IR light from the PW. The depth of cure was also evaluated by photocuring RBC samples in both metal and plastic molds for 20 s at a 0 mm distance. The length of resin remaining was then measured and divided by 2. Starting from a baseline of 32 °C, the temperature rise during photocuring was measured in the plastic and metal rings reproducing the conditions used to measure the depth of cure and the DC respectively.

RESULTS

In general, the PW produced greater depth of cure, however the use of metal molds greatly reduced this effect because the temperature increase was reduced. Increasing the distance by up to 4 mm from the light tip produced a significant increase in the DC for the RBCs photocured with the PW, but not for the G4. The wavelength of the blue peak (peaking at 473 nm) from the PW was longer compared to the control LCU (peaking at 448 nm). This 25 nm difference negatively affected the photocuring efficiency of some resins.

SIGNIFICANCE

The internal optics and the additional red and IR wavelengths from the PW significantly increased the temperature in the RBCs and increased both depth of cure and the DC.

Degradation of experimental composites containing calcium orthophosphate particles in different immersion media

The aim of the present study was to evaluate the effect of prolonged immersion in different media on the mechanical properties of composites containing dicalcium phosphate dihydrate particles (DCPD, CaHPO4.2H2O). Three formulations with the same resin phase (BisGMA/TEGMA, 1:1 in moles) were prepared. The total inorganic content was 50 vol%, consisting of barium glass (BG) or a mixture of BG and DCPD (15:35 or 35:15 vol%). The degree of conversion (DC) of the composites was determined using FTIR spectroscopy (n = 3). Biaxial flexural strength (BFS) and flexural modulus (FM) were determined using the "piston-on-three-spheres" method (n = 13) after 24 h and 6 months in deionized water (DW), citric acid (CA, pH 5) or 75 % ethanol solution (EtOH). Knoop microhardness (KHN, n = 6) was determined in fragments of the flexural test specimens. Data were analysed using ANOVA/Tukey's test (alpha: 5 %). DC was statistically higher for the 35 % DCPD composite (p < 0.001). Overall, mechanical properties were inversely related to DCPD fraction in all three media and both storage times. The 15 % DCPD composite had BFS statistically similar to the control in most of the tested conditions, and similar FM after 24h in all media. However, CA had a severe negative effect on the KHN of composites containing DCPD both after 24h and 6 months, while EtOH caused the highest reduction in KHN for the control, in comparison to DW. Based on these results, it is concluded that composites containing DCPD presented higher surface degradation than the control, which may limit their use as bulk restoratives.

Physicomechanical properties of resin-based composites photo-polymerized using laser, polywave and quadwave curing lights

OBJECTIVES

This study evaluated the fracture toughness (KIC), energy absorption E and Vickers hardness (VH) of resin-based composites (RBC) photo-polymerized with new light curing unit (LCU) technologies: one laser diode (Monet Laser - AMD Lasers), one polywave™ LED (PowerCure - Ivoclar) and one quadwave LED (PinkWave - Apex).

METHODS

Two conventional: Evo, Tetric EvoCeram (Ivoclar) and FS, Filtek Supreme (Solventum); and two bulk-fill: PF, PowerFill (Ivoclar) and AF, Admira Fusion x-tra (VOCO) were tested. The RBC specimens were photo-polymerized for 1 second with the Monet, 3 seconds with the PinkWave in the 3-second-high output mode, and the 10-second standard mode using the PowerCure light. The power (mW), irradiance (mW/cm2), radiant exposure (J/cm2), and emission spectrum (mW/cm2/nm) were measured using a fiberoptic spectrometer attached to an integrating sphere. KIC (KIC, MPa·m1/2) was obtained using an 8.2 mm diameter and 2.0 mm thick metal mold. After 24-hour storage at 37 °C, the KIC was measured in a universal testing machine at a rate of 0.5 mm/min. The energy absorption (E, N/mm) up to failure was calculated. The Vickers hardness (VH, Kg/mm2) was measured at the bottom of the KIC specimen. Data were analyzed using a two-way analysis of variance followed by the Tukey multiple comparison test (α = 0.05).

RESULTS

Both the KIC and VH were significantly influenced by the light-curing unit/exposure time and by the RBC used (p < .001). The Monet emitted the highest power (1501.4 mW) but delivered the lowest radiant exposure (3.0 J/cm2). In general, the KIC values did not differ when RBCs were photo-polymerized with PowerCure in the standard 10 s or 3 s modes, except for the Admira Fusion x-tra. The KIC, VH and energy absorption to failure values were higher for all RBCs when photo-polymerized with PowerCure in the Standard mode for 10 s and lowest with the Monet used for 1 s. Filtek Supreme had the highest VH values regardless of the curing light unit/exposure time. The VH was better at detecting differences between the LCUs/exposure time and the RBC.

SIGNIFICANCE

Short 1-3 s exposure times produce inferior physicomechanical properties in some RBCs compared to a 10 s exposure at a lower irradiance. Clinicians should understand how much energy the manufacturers of the RBCs are recommending should be delivered to their RBC.

Effect of beam divergence on the irradiance from dental light curing units

OBJECTIVE

This study measured the beam divergence angle and light output from dental light curing units (LCUs). Twenty LCUs were assessed using a laboratory-grade wide beam imager to determine the relationship between the beam divergence on the irradiance as a function of distance from the light tip.

METHODS

The irradiance (mW/cm2) and beam divergence angles (°) at 5, and 10 mm from the tips of 18 Light-Emitting Diode (LEDs), 1 Quartz-Tungsten-Halogen (QTH), and 1 Laser diode LCU.

RESULTS

There were significant differences in the power, irradiance, and emission spectra from the 20 LCUs. At 10 mm from the LCU tip, the irradiance delivered by one LCU decreased by approximately 85.7 %, whereas this decrease was as low as 5.6 % for a different LCU. There was a positive correlation between the divergence angle reported by the wide beam imager and the reduction in irradiance. The laser diode LCU had the least beam divergence and the smallest decrease in irradiance as the distance increased. In contrast, the QTH LCU with the turbo light guide had the greatest beam divergence and the greatest reduction in irradiance as the distance increased. 50 % of the LCUs tested would require exposure times longer than 20 s to deliver 10 J/cm2 at the 10 mm distance.

SIGNIFICANCE

The wide beam imager is a useful tool for measuring the beam divergence from LCUs and predicting the effect of distance on their irradiance. At 10 mm, some LCUs may require a fivefold increase in the exposure time to deliver the same energy they deliver at 0 mm from the tip of the LCU.

Three-Year Practice-Based Clinical Trial on the Performance of a Self-Adhesive Resin-Based Bulk-Fill Restorative

OBJECTIVE

The prospective clinical study followed up on self-adhesive resin-based bulk-fill restorations.

MATERIALS AND METHODS

Seven general dental practitioners from a practice-based research network filled 60 cavities (20 Class I, 19 Class II, 21 Class V) in permanent vital teeth of 41 subjects with a self-adhesive, dual-curing composite hybrid (Surefil one). Modified USPHS criteria were evaluated at baseline and annually. Replacement or repair of the restoration was defined as failure. Data were analyzed using the Kaplan-Meier method and non-parametrically (p < 0.05).

RESULTS

After 3 years (1118 ± 39 days), all 29 recalled teeth were rated as vital with no hypersensitivity. One tooth showed signs of cracking. One Class I and one Class II restoration failed due to a combined marginal gap and chipping. Two restorations showed a color mismatch. The remaining restorations were found to be in clinically acceptable condition and all Class II restorations in proximal contact maintained proper contact. With one restoration failure reported after 1 year, the total of three failures resulted in an annual failure rate of 3.94%.

CONCLUSIONS

The self-adhesive composite hybrid placed during daily routine showed acceptable results out to 3 years in load-bearing Classes I and II as well as non-retentive Class V cavities.

CLINICAL SIGNIFICANCE

Three-year data confirmed the suitability of the novel self-adhesive restorative material for stress-bearing posterior restorations.

Evolution of Dental Resin Adhesives-A Comprehensive Review

This comprehensive review of dental resin adhesives explores their historical development, key components, recent innovations, and potential future directions, highlighting a dynamic and continually advancing field. From Buonocore's breakthrough acid-etching technique and Bowen's pioneering dental resin invention, successive generations of clinicians and scientists have pushed forward the technological and materials development for secure bonding, while preserving dental tissues. The review discusses the substantial advances in improving adhesive reliability, enabling more conservative treatment approaches. It also delves into enhancing fundamental adhesive components and their synergistic combinations. Recent innovations, including biostable and functional resins, nanotechnology, and bioactive components, address persistent challenges such as durability, antimicrobial efficacy, and therapeutic functionality. Emerging technologies, such as digital dentistry, artificial intelligence, and bioinspired adhesives, portend an exciting and promising future for dental adhesives. This review underscores the critical role of ongoing research in developing biocompatible, multifunctional, and durable adhesives. It aims to support dental professionals and researchers by providing a comprehensive understanding of the dynamic progression of dental adhesives, inspiring continued innovation and excellence in restorative dentistry.

Ion-releasing resin composites prevent demineralization around restorations in an in-vitro biofilm model

OBJECTIVE

This study aimed to evaluate the effectiveness of two ion-releasing, resin-based composites (RBCs), ACTIVA BioACTIVE-Restorative (BIO1) and ACTIVA Presto (BIO2), in preventing demineralization around restorations.

METHODS

Class I and II cavities were prepared on bovine (n = 4) and human teeth (n = 8) and restored with BIO1, BIO2, a conventional composite (RBC, Filtek Supreme XTE), and a resin-modified glass ionomer cement (RMGIC, Ionolux). Following restorations (class I, n= 16/material; class II, n= 8/material), the specimens were exposed to Streptococcus mutans biofilm in a continuous-flow bioreactor over two weeks. Micro-computed tomography (micro-CT) assessed demineralization depths at restoration margins, and supernatant pH changes were measured after a 24-h acidic challenge. Statistical analyses included one and two-way ANOVA and Tukey's test (p < 0.05).

RESULTS

On enamel surfaces, RMGIC showed no demineralization, followed by BIO1 (≈50 μm), BIO2 (≈125 μm), and RBC (≈150 μm). No difference between human or bovine enamel was observed. In dentin, RMGIC showed the least demineralization (≈190 μm), followed by BIO1 (≈230 μm), BIO2 (≈280 μm), and RBC (≈400 μm). pH buffering was highest in RMGIC (+ 0.24 pH), while BIO1, BIO2, and RBC showed similar buffering capacities (∼ +0.1 pH). Gaps were found at several interfaces for BIO1 and RMGIC.

CONCLUSIONS

Ion-releasing RBCs varied in effectiveness for reducing demineralization of surrounding tissues, with limited pH buffering capacity. RMGIC exhibited better performance. Gaps between cavity walls and BIO1/RMGIC raised concerns about long-term adhesion.

CLINICAL SIGNIFICANCE

ACTIVA BioACTIVE Restorative (BIO1) and ACTIVA Presto (BIO2) resin-based composites promoted slight inhibition of demineralization in an in-vitro biofilm model, suggesting that further modifications in their chemical composition are necessary.

Proposal of a Modular Classification System for Direct Dental Resin Composites Based on Clinical Applications

The adhesive-resin composite pair has been the cornerstone of direct restorations in dentistry for many years. Resin composites are traditionally classified in three ways based on their inorganic structure, their organic composition and their viscosity. While these classifications have long been associated with the optical, mechanical, and clinical properties of resin composites, recent studies indicate that this classification is not always valid. In recent years, a significant expansion of the range of clinical resin composite families has occurred, each with varying degrees of validation through in vitro and clinical studies. As a result, new resin composites with distinct structures, viscosities, and clinical indications have emerged. Despite this progress, a formal classification of the clinical features of all resin composites is still lacking, leading to terminological inconsistencies in research and potential confusion among clinicians. This brief review, supported by an exhaustive search of the dental literature, proposes a new clinical classification system for resin composites based on their key clinical features to help clinicians and researchers easily identify the key clinical characteristics of formulations. This modular classification, encompassing eight main families and 14 characteristics, is particularly suited to future developments, as current trends aim to simplify procedures by integrating multiple formulations into single products.

Six-year clinical evaluation of a copper-containing universal adhesive in non-carious cervical lesions: A split-mouth double-blind randomized clinical trial

OBJECTIVES

To evaluate the clinical performance of a universal adhesive system containing 0.1 % copper nanoparticles (CuNp) in non-carious cervical lesions (NCCLs) after 6 years.

MATERIAL AND METHODS

Two hundred and sixteen restorations (n = 54) were randomly placed in 36 participants with at least four NCCLs. Groups included: ER-Cu (adhesive in etch-and-rinse strategy with CuNp), ER-Ct (etch-and-rinse without CuNp), SE-Cu (self-etch with CuNp), and SE-Ct (self-etch without CuNp). Restorations were evaluated at baseline and after 1, 3, 4, and 6 years using the FDI and USPHS criteria.

PRIMARY OUTCOME

fracture of material and retention. Examiners and patients were blinded to group assignment.

RESULTS

After 6 years, 104 restorations were analyzed (ER-Cu 24, ER-Ct 29, SE-Cu 27, SE-Ct 24). Fourteen restorations loss retention (ER-Cu 6, ER-Ct 1, SE-Cu 2, SE-Ct 7). Retention rates (95 % confidence interval) were 79.3 % (61.6 - 90.1) for ER-Cu; 97.0 % (83.3 - 99.4) for ER-Ct; 93.1 % (78.1 - 98.1) for SE-Cu; and 76.7 % (59.1 - 88.2) for SE-Ct, with statistical differences between SE-Cu vs. ER-Ct, and SE-Ct vs. ER-Ct (p < 0.05). Thirty-one restorations (ER-Cu 6, ER-Ct 5, SE-Cu 9, SE-Ct 11) showed minor marginal staining, and forty-one restorations (ER-Cu 8, ER-Ct 10, SE-Cu 11, SE-Ct 12) presented minimal marginal adaptation defects (p > 0.05). No significant differences were found for other secondary parameters (p > 0.05).

CONCLUSION

This is the first 6-year clinical trial showing the long-term behavior of a universal adhesive system in NCCLs. The addition of CuNp does not affect the clinical performance of the universal adhesive.

Clinical performance of different composite materials in class II cavities bonded with universal adhesives

OBJECTIVE

To assess the clinical performance of two composite materials with two universal adhesives and a two-step self-etch adhesive on class II restorations for 18 months.

MATERIALS AND METHODS

Two hundred and fifty-two class II cavities were bonded with G-Premio Bond, Single Bond Universal, and Clearfil SE Bond 2. A nanohybrid composite (Filtek Z550 Universal) or a microhybrid composite (G-aenial Posterior) was used to fill the bonded cavities. World Dental Federation criteria were used to evaluate the restorations at 1 week, 6, and 18 months. Statistical analysis was performed using Friedman and Fisher's exact tests (α = 0.05).

RESULTS

Retention loss and fracture were not observed in any restorations during the 18 months. The adhesives used showed no significant differences for all criteria examined (p > 0.05) regardless of composite material. After an 18-month follow-up, seven G-aenial Posterior and three Filtek Z550 Universal restorations presented slight marginal discrepancies, with no significant differences (p = 0.246). At 1 week, Filtek Z550 Universal (9.5%) led to significantly higher postoperative sensitivity compared with G-aenial Posterior (0.8%) (p = 0.001).

CONCLUSIONS

Universal adhesives showed similar clinical performance to Clearfil SE Bond 2. The restorations with Filtek Z550 Universal had a relatively higher risk of postoperative sensitivity.

CLINICAL SIGNIFICANCE

Universal adhesives were clinically successful for 18 months. At 1 week, the type of composite material used significantly affected the occurrence of postoperative sensitivity.

Influence of preheating and water storage on the color, whiteness, and translucency of modern resin-based composites

OBJECTIVES

To evaluate the influence of preheating and water storage on color, whiteness, and translucency of one-shaded, group-shaded, and multi-shaded resin-based composites.

MATERIALS AND METHODS

A total of 270 samples were fabricated from one-shaded (Omnichroma), group-shaded (Optishade MD), and multi-shaded (Enamel Plus HRI) resin-based composites and divided into six groups: no heating (control) and 1-5 heatings (test) (n = 15). The CIE L*, a*, b*, C*, and h° color coordinates were registered over white, black, and gray backgrounds with a spectrophotometer before and after 24, 72, 144 h water storage. Kruskal-Wallis test was used to evaluate differences in the color coordinates, whiteness index, and translucency parameter (α = 0.05). The Mann-Whitney U test was performed with a Bonferroni correction (p < 0.001) for pairwise comparisons. CIEDE2000 color, whiteness, and translucency differences between groups and subgroups were evaluated using their respective 50%:50% perceptibility and acceptability thresholds.

RESULTS

Preheating influenced color coordinates, whiteness index, and relative translucency parameters (p < 0.001). Although color differences were below the acceptability threshold for all materials, translucency differences were above the acceptability threshold for Omnichroma. Water storage significantly influenced the whiteness index of Optishade MD (p < 0.001).

CONCLUSIONS

Preheating had a more considerable effect on the color, whiteness, and translucency of one-shaded resin-based composite, while water storage influenced group-shaded resin-based composite more importantly.

CLINICAL SIGNIFICANCE

Preheating influences the color, whiteness level, and translucency of the resin-based composites, but the variations remain generally clinically acceptable; however, practitioners should be aware that the modifications in translucency for one-shaded resin-based composites could be more important than for group-shaded and multi-shaded resin-based composites.

Esthetic rehabilitation of labial tooth defects caused by caries of the anterior teeth using a composite resin injection technique with veneer-shaped 3D printing indices

PATIENTS

An 18-year-old woman sought treatment for caries of the anterior teeth after completing orthodontic treatment. Direct composite resin restoration was chosen because the patient preferred a minimally invasive and cost-effective treatment whenever possible. Based on diagnostic wax-up, veneer-shaped indices for composite resin injection were designed to replicate and restore tooth defects rapidly and accurately. The overall esthetic result was excellent after a 1-year of follow-up.

DISCUSSION

Direct freehand composite resin restorations are clinically challenging. The recently proposed 3D printing index for the composite resin injection technique is helpful for direct restoration but is challenging to remove. The veneer-shaped indices avoid the formation of an undercut in the direction of removing the index, making them easy to remove after finishing the restorations.

CONCLUSIONS

Using veneer-shaped indices for composite resin injection enables rapid esthetic rehabilitation of labial tooth defects caused by caries. This approach reduces chairside time and operational difficulty while allowing for easy index removal after completing the restorations.

The clinical performance of high-viscosity glass ionomer-based and bulk-fill resin-based restorations in permanent teeth with occlusal or proximal cavities: a systematic review and meta-analysis

OBJECTIVES

To summarize and analyze existing evidence regarding the clinical performance of high-viscosity glass-ionomer-based materials (HVGIs) and bulk-fill resin-based composites (BFs) in patients with occlusal or proximal cavities in permanent teeth.

MATERIALS AND METHODS

A literature search was conducted using PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Embase, Scopus, and Web of Science (WOS) (last update: April 19th, 2024). Randomized control trials (RCTs), retrospective and prospective comparative cohorts were included. Manual searching was performed for twelve relevant dental journals. The primary outcome was the retention of the restoration. The evaluation of included studies, data extraction, and study selection were completed by two independent reviewers. The Cochrane risk-of-bias tool (RoB 2) and the Newcastle-Ottawa scale were used to assess the quality of included studies. A quantitative meta-analysis was conducted, and the overall quality of the evidence was evaluated.

RESULTS

Five RCTs and one retrospective study were included, of which one had a high risk of bias and the others had an unclear risk of bias. In meta-analyses, HVGIs were associated with a less favorable outcome on retention both at one (p = 0.013) and two-year follow-ups (p < 0.0001) compared with BFs. The quality of the evidence was very low.

CONCLUSIONS

Very low certainty evidence suggested that BFs presented favorable clinical performance on retention and marginal adaptation in Class I and II restorations in permanent teeth comparing HVGIs. Nevertheless, HVGIs with a resin-based coating showed acceptable clinical behavior.

CLINICAL RELEVANCE

For patients with a high caries risk, HVGIs serve as a direct restorative alternative for the posterior permanent teeth; however, they should be carefully considered as bulk-fill composite resin alternatives for long-term restoration.

REGISTRATION

PROSPERO (CRD42024535999).

Long-term clinical comparison of a resin-based composite and resin modified glass ionomer in the treatment of cervical caries lesions

This 72-month study compared the clinical effectiveness of a resin-based composite (RBC) (Spectrum TPH3, Dentsply Sirona) with a resin-modified glass ionomer cement (RMGIC) (Riva Light Cure, SDI) in restoring cervical caries lesions (CCLs). Thirty-three patients, each with at least two CCLs, were enrolled. After caries removal, the dimensions of the cavities were recorded. In a split-mouth study design, a total of 110 restorations were randomly placed. Fifty-five restorations were placed with RBC using an etch-and-rinse adhesive system (Prime&Bond NT, Dentsply Sirona), while the remaining 55 were restored with RMGIC. The restorations were assessed at baseline, 6, 12, 18, 24, 36, 60, and 72 months according to modified USPHS criteria. Statistical analysis included Pearson Chi-square, Friedman tests, Kaplan Meier, and Logistic Regression analysis (p < 0.05). After 72 months, 47 restorations in 19 patients were evaluated (55% follow-up rate). Seventy-five percent of the RBC (n = 26) and 74% (n = 21) of the RMGIC restorations were fully retained. There were no significant differences between materials regarding retention and marginal adaptation (p > 0.05). Cavity dimensions, caries activity, and retention exhibited no correlation (p > 0.05). The increase in marginal staining in both groups over time was significant (p < 0.001). RMGIC restorations exhibited higher discoloration than RBC restorations (p = 0.014). At 72 months, three secondary caries lesions were detected in both restoration groups: two RMGIC and one RBC. There were no reports of sensitivity. After 72 months, both RBC and RMGIC restorations were clinically successful, with similar retention and marginal adaptation scores. However, it is noteworthy that RMGIC restorations tend to discoloration over time compared to RBC. The trial is registered in the database of "Clinical Trials". The registration number is NCT0372-2758, October 29, 2018.

Proteomic Analysis of Fibroblasts Exposed to Resin Composite Release

OBJECTIVE

To investigate the potential effects of products released by a resin composite on the proteome of human gingival fibroblasts.

METHODS

Fifteen resin composite cylinders of a Bis-GMA-based resin composite (Tetric EvoCeram, Ivoclar) were made and placed in a culture medium for 24 h. Then, 30 mL of this medium was placed for 72 h in contact with human gingival fibroblasts and a second control group consisted of cells placed in culture medium only. Afterward, cells were collected, washed, and their proteins extracted. Three two-dimensional electrophoresis were performed per condition. Image analysis of the gels was carried out to highlight the differential protein spots. These spots were then analyzed by an ESI/qTOF mass spectrometer. Finally, specific databases provided protein identification, their interactions, and the pathways where they are implicated.

RESULTS

Delta2D software allowed the detection of 21 spots of different proteins. The MASCOT identified 28 proteins. Five proteins from four spots were upregulated, 23 proteins from 17 spots were downregulated. The UniProt database showed that all these proteins were involved in cellular architecture, structural modifications and quality control of proteins, cellular homeostasis, and metabolic pathways. The STRING database revealed the interactions between the regulated proteins. The GO enrichment analysis showed that 19 pathways were affected.

SIGNIFICANCE

The products released from the resin composite tested led to changes in the fibroblast proteome. Under the conditions of this study, resin composite released products can cause early adverse effects on cells, but without complete inhibition of their cellular functions.

Evaluation of the Effect of Chitosan-Based Irrigation Solutions on the Bond Strength of Mineral Trioxide Aggregate to Bulk-Fill Composite

(1) Background: Bond strength between repair and restorative materials is crucial for endodontic success. This study assessed the effects of the following final irrigation solutions on the bond strength of mineral trioxide aggregate (MTA) to a bulk-fill composite: (1) 17% Ethylenediamine tetraacetic acid (EDTA); (2) 2% Chlorhexidine (CHX); (3) 0.2% chitosan; (4) 0.2% chitosan with 2% CHX; 5) 0.2% chitosan with AgNPs. (2) Methods: Sixty MTA samples were divided into six groups (n = 10) based on the final irrigation solution: 1. EDTA, 2. CHX, 3. Chitosan, 4. Chitosan-CHX, 5. Chitosan-AgNP, and 6. distilled water (control). After a 5-min solution exposure, each sample was restored with the bulk-fill composite, and the shear bond strength (SBS) was measured. Structural changes in MTA were analyzed using SEM and EDS, and failure modes were classified as adhesive, cohesive, or mixed. Data were analyzed by one-way ANOVA with Tamhane's T2 and Tukey's tests (α = 0.05). (3) Results: EDTA exhibited the lowest SBS (p < 0.001), while Chitosan-CHX showed the highest. SEM showed a spongy, void-rich surface in EDTA-treated MTA, with significant Ca depletion per EDS. Chitosan-CHX showed no structural change. Cohesive fractures within MTA were predominant. (4) Conclusions: EDTA significantly reduces SBS, while chitosan with CHX enhances bond strength.

Influence of different viscosity and chemical composition of flowable composite resins: A 48-month split-mouth double-blind randomized clinical trial

OBJECTIVES

To evaluate the clinical performance of two flowable composites based on methacrylate and one based on ormocer in treating non-carious cervical lesions (NCCLs) after 48-month evaluation in a split-mouth double-blind clinical study design.

METHODS

A total of 183 restorations were performed on NCCLs using a universal adhesive system (Futurabond U, Voco GmbH) with selective enamel etching on 27 participants: two participants received twelve restorations each, three received nine restorations each, and 22 participants received six restorations each. Three different flowable composites were employed (n = 61): a low-viscosity methacrylate-based composite (GrandioSO Flow, LVM), a high-viscosity methacrylate-based composite (GrandioSO Heavy Flow, HVM), and an ormocer-based flowable composite (Admira Fusion Flow, ORM). All restorations were evaluated using FDI and USPHS criteria after 48 months. Statistical analysis was conducted using Kaplan-Meier Survival analysis and Kruskal-Wallis analysis of variance rank (α = 0.05).

RESULTS

After 48 months, 17 restorations were lost: LVM 6, HVM 9, ORM 2. The retention rates (95 % confidence interval) were 89.4 % for LVM, 80.4 % for HVM, and 95.6 % for ORM, with a significant difference between HVM vs. LVM and HVM vs. ORM (p < 0.05). Minor defects were observed in 30 restorations for marginal staining criteria (LVM 12, HVM 10, ORM 8) and in 71 restorations for marginal adaptation criteria (LVM 24, HVM 20, ORM 27) without significant difference between groups (p > 0.05). No restorations showed postoperative sensitivity or recurrence of caries.

SIGNIFICANCE

The increased viscosity of flowable composites could reduce the clinical longevity in NCCLs after 48 months. Ormocer-based and low-viscosity methacrylate-based flowable composites showed a successful clinical performance in NCCLs after 48 months.

Enhancing Wear Resistance in Glass Ionomer Cement through Green-mediated Chitosan-, Titanium-, Zirconium-, and Hydroxyapatite-based Nanocomposites: An Analysis before and after Chewing Simulator Endurance

Aim and background

Glass ionomer cement (GIC) serves as a widely used restorative dental material, known for its direct bonding to tooth structures and fluoride-releasing properties. This study aims to investigate the enhancement of GIC through the incorporation of a green-mediated nanocomposite comprising chitosan, titanium, zirconium, and hydroxyapatite, with a focus on evaluating the wear resistance of the modified GIC.

Materials and methods

A one-pot synthesis technique was utilized to prepare a green-mediated nanocomposite incorporating chitosan, titanium, zirconium, and hydroxyapatite nanoparticles. Forty extracted teeth fulfilling the inclusion criteria were chosen for the study. Each tooth received a class I cavity preparation, and then they were divided into groups. Each group, comprising 10 teeth, received a restoration using green-mediated nanocomposite-modified GIC in varying concentrations: 3% for group I, 5% for group II, and 10% for group III. Additionally, there was a control group (group IV) consisting of conventional GIC without any modifications. To assess the wear resistance of the samples, they underwent a testing protocol, followed by placement in a chewing simulator for 30,000 cycles. Surface scans before and after chewing simulation were conducted, and deviations were superimposed using Geomagic software. The interim of root mean square (RMS), maximum deviation, and average deviation were analyzed to quantify the wear levels. Then the data obtained were subjected to statistical analysis, one-way analysis of variance (ANOVA), followed by Tukey's post hoc analysis to identify any significant differences among the groups.

Results

The least deviation of RMS (0.292 ± 0.063), maximum deviation (0.664 ± 0.076), and average deviation (0.263 ± 0.049) were observed in the 5% nanocomposite-based GIC group, followed by the 10 and 3% groups. The nanocomposite-modified GIC groups exhibited superior wear resistance compared to the conventional group. This outcome addressed the limitations of traditional GIC, signifying a substantial advancement in dental restorative solutions.

Conclusion

The incorporation of green-mediated chitosan, titanium, zirconium, and hydroxyapatite nanocomposite into GIC demonstrated a remarkable improvement in wear resistance. This study paves the way for future advancements in dental materials, representing a significant stride toward the creation of environmentally conscious and efficacious dental restorations.

How to cite this article

Sitaram SS, Paulraj J, Maiti S, et al. Enhancing Wear Resistance in Glass Ionomer Cement through Green-mediated Chitosan-, Titanium-, Zirconium-, and Hydroxyapatite-based Nanocomposites: An Analysis before and after Chewing Simulator Endurance. Int J Clin Pediatr Dent 2024;17(11):1229-1235.

Buonocore Memorial Lecture 2023: Longevity of Dental Restorations or Longevity of Teeth: What Matters?

This paper aims to raise a discussion from the perspective of maintaining long-term oral health, posing a critical question: What holds greater significance for maintaining oral health, the longevity of restorations or teeth? This question explores the aspects that truly matter in ensuring sustained oral health throughout an individual's life. Restoration longevity is well-researched, and evidence shows several risk factors influencing longevity. The dentist's decision-making factor may be of utmost importance, and further studies are needed to investigate its relevance. The critical risk factors for restoration longevity are active pathology (high caries risk), less prominent parafunction, and extensive defects such as endodontic treatment. However, tooth longevity and the main risk factors for tooth loss are not well-researched. The evidence shows dental caries, and its sequelae, are the principal reasons for tooth loss. Patient-related risk factors, especially those associated with lifestyle and health choices, play a major role in the longevity of restorations and, more importantly, tooth longevity. To provide personalized dental care with maximum patient benefit, clinicians should identify and record potential risk factors, promoting a healthy lifestyle to ensure tooth and dentition longevity. Moreover, the evidence suggests that decision-making frameworks based on minimal intervention principles offer the best standard for clinical practice, promoting a longstanding healthy oral environment.

Clinical evaluation of posterior flowable short fiber-reinforced composite restorations without proximal surface coverage

The purpose of this clinical trail was to assess the clinical behavior of posterior composite restorations supported by a substantial foundation of flowable short fiber-reinforced composite SFRC (everX Flow, GC, Japan) used without proximal surface coverage with particulate filler resin composite (PFC). Seventy patients (20 males, 50 females; mean age: 30 ± 10 years) were randomly enrolled in this trial. Patients received direct restorations of either SFRC covered only on the occlusal surface (1-2 mm) by conventional PFC composite (G-ænial Posterior, GC), or plain conventional PFC composite without fiber-reinforcement, in Class II cavities in premolar and molar vital teeth. One operator made all restorations using one-step, self-etch bonding agent (G-ænial Bond, GC) according to manufacturers' recommendations. Two blinded trained operators evaluated the restorations at baseline, at 6, 12 and 18 months using modified USPHS criteria. Results indicated that, in both groups and at different follow-up intervals, according to evaluated criteria, restorations were rated mostly with best score (Alpha) (p > 0.05). For the marginal integrity after 6 months, a single case in the intervention [increased to 3 (8.8%) after 18 months] and 3 (9.7%) cases of the control group [increased to 4 (12.9%) after 18 months] had Bravo score but with no significant difference (p > 0.05). For color match measured after 6 and 18 months, three (8.8%) cases had Bravo score in the intervention group. The use of flowable SFRC composite without any PFC surface coverage proximally in Class II restorations demonstrated satisfactory clinical outcome throughout the 18-month follow-up.

A Critical Review on the Factors Affecting the Bond Strength of Direct Restorative Material Alternatives to Amalgam

This article comprehensively reviews the performance of simplified direct restorative materials that have the potential to be an alternative to amalgam. Following an understanding of the material structures and clinical performances, this review provides an analysis of the bonding mechanisms and influential factors on the bond strength. These factors include substrate-related variations, involving primary vs. permanent dentin, sound- vs. caries-affected/demineralized dentin comparisons and surface-related factors and pretreatments. Special attention is given to the factors changing the substrate surface, such as different contaminants, remedy methods after contamination and different conditioning methods related to the materials. Variations in sample preparation and bond strength test parameters are also evaluated for the analysis of the outcomes. This review aims to provide an overview of the factors involved in the application procedure of direct restorations together with in vitro testing variations to guide the selection of suitable materials by understanding strengths and shortcomings.

Opalescence and Fluorescence of 46 Resin-Based Composites Exposed to Ultraviolet Light

Identifying the boundary between the tooth and the resin-based composite (RBC) is difficult when replacing restorations. Ultraviolet (UV) light has been reported to assist the viewer by causing the RBC to fluoresce. Using a laboratory-grade fiberoptic spectrometer, 46 RBCs were exposed to UV light from the Woodpecker O-Star curing light. The opalescence and fluorescence were measured relative to a human tooth that contained just dentin and a tooth that contained both enamel and dentin. After these quantitative measurements, 10 RBCs with large differences in light emittance were compared qualitatively to assess their brightness when exposed to UV light compared to the dentin specimen and the specimen containing both enamel and dentin. It was found that, when exposed to UV light, some of the RBCs were less bright compared to the two samples of teeth used for comparison, but most were brighter; some were up to six times brighter. The filler appears to affect the opalescence peaks, while the resin appears to affect the fluorescence peaks. It was concluded that because RBCs emit very different levels of opalescence and fluorescence, UV light from the Woodpecker O-Star cannot be relied upon to detect all brands of RBC on the tooth. The opalescence and fluorescence can also be used to detect changes in the formulation of the RBC.

Comparison of Bulk Polymeric Resin Composite and Hybrid Glass Ionomer Cement in Adhesive Class I Dental Restorations: A 3D Finite Element Analysis

This study aimed to investigate the mechanical behavior of resin composites and hybrid glass ionomer cement in class I adhesive dental restorations under loading and shrinkage conditions. Three CAD models of a mandibular first molar with class I cavities were created and restored with different techniques: a bi-layer of Equia Forte HT with Filtek One Bulk Fill Restorative composite (model A), a single layer of adhesive and Filtek One Bulk Fill Restorative (model B), and a single layer of Equia forte HT (model C). Each model was exported to computer-aided engineering software, and 3D finite element models were created. Models A and B exhibited a similar pattern of stress distribution along the enamel-restoration interface, with stress peaks of 12.5 MPa and 14 MPa observed in the enamel tissue. The sound tooth, B, and C models showed a similar trend along the interface between dentine and restoration. A stress peak of about 0.5 MPa was detected in the enamel of both the sound tooth and B models. Model C showed a reduced stress peak of about 1.2 MPa. A significant stress reduction in 4 mm deep class I cavities in lower molars was observed in models where non-shrinking dental filling materials, like the hybrid glass ionomer cement used in model C, were applied. Stress reduction was also achieved in model A, which employed a bi-layer technique with a shrinking polymeric filling material (bulk resin composite). Model C's performance closely resembled that of a sound tooth.

Flexural Properties, Wear Resistance, and Microstructural Analysis of Highly Filled Flowable Resin Composites

OBJECTIVE

This study aimed to evaluate the flexural properties and two-body wear resistance of nine highly filled flowable resin composites relative to those of viscous and conventional low-filled flowable composites. In addition, scanning electron microscopy (SEM) analysis of the microstructures was performed.

METHODS AND MATERIALS

For each resin composite group (n=12), 12 specimen bars (25 mm × 2 mm × 2 mm) were fabricated using a silicon mold for performing flexural strength (FS), flexural modulus (E), flexural toughness (FT), Weibull modulus (m) tests, and SEM microstructural analysis. For each group, ten bars were tested using a three-point flexural test on a universal testing machine, while the other two were embedded in acrylic resin before being observed by SEM for structural analysis. During the two-body wear test with a chewing simulator, 8 specimens (12 groups, n=8) of each resin composite group were manufactured in a specific mold and subjected to 120,000 cycles of wear against a steatite ball, and the depth loss was measured. Three one-way ANOVA tests followed by Tukey's post hoc tests were conducted to compare the flexural and wear properties among the different groups.

RESULTS

The majority of highly filled composites tested in this study exhibited similar flexural strengths (between 105.68 MPa and 135.49 MPa) and superior wear resistance to those of viscous composites. The flexural moduli (between 5.12 GPa and 9.62 GPa) of these composites were in between those of the viscous and low-filled composites tested in this study.

CONCLUSIONS

The highly filled flowable composites tested in this study exhibited different in vitro properties but were often superior to those of viscous resin composite suggesting their possible use for posterior restorations.

Biomechanics, Bioactive and Biomimetic philosophy in restorative dentistry ̶ Quo vadis?

INTRODUCTION

In recent years, restorative dentistry has embraced various techniques, including direct, semi-direct, and indirect restorations, to address the replacement of lost tooth tissue. The focus has been on integrating the principles of Biomechanics, Bioactivity, and Biomimicry (3-Bio) as key drivers behind these innovations.

METHODS

The aim of this article is to provide a concise overview of three important aspects of restorative dental materials: biomechanics, bioactivity and biomimetics. Further, the aim is to provide readers with relevant information on the 3-Bio concept, offering insights in to the innovative approaches shaping modern restorative dentistry.

RESULTS

Developing restorative materials with interactive properties aligned with the 3-Bio concept poses a significant challenge. Currently, dentistry lacks a comprehensive system in this regard. The development of dental materials based on the 3-Bio concept could potentially elicit positive mechanical and biological responses in targeted tooth tissues.

CONCLUSION

Assessing several parameters through a battery of in vitro and in silico assays could help in tailoring the different aspects of the 3-Bio concept, spanning from bioactivity to biomimetics via biomechanics. This approach could allow the prediction and translation of the clinical performance of the assessed restorative materials.

CLINICAL SIGNIFICANCE

The findings of this opinion article highlight that the development of restorative materials aligned with the 3-Bio concept could enhance the management of dental defects and extend the longevity of bonded restorations, thereby improving patient care through tissue preservation. More collective efforts between clinicians, researchers, and even industrial partners are required to fully understand the correlation between bioactive behavior, biomechanical limitations, and biomimetics to provide suitable restorative materials for specific clinical applications.

Developing an optimised method for accurate wear testing of dental materials using the 'Rub&Roll' device

Dental materials are challenged by wear processes in the oral environment and should be evaluated in laboratory tests prior to clinical use. Many laboratory wear-testing devices are high-cost investments and not available for cross-centre comparisons. The 'Rub&Roll' wear machine enables controlled application of force, chemical and mechanical loading, but the initial design was not able to test against rigid antagonist materials. The current study aimed to probe the sensitivity of a new 'Rub&Roll' set-up by evaluating the effect of force and test solution parameters (deionized water; water + abrasive medium; acid + abrasive medium) on the wear behaviour of direct and indirect dental resin-based composites (RBCs) compared with human molars against 3D-printed rod antagonists. Molars exhibited greater height loss than RBCs in all test groups, with the largest differences recorded with acidic solutions. Direct RBCs showed significantly greater wear than indirect RBCs in the groups containing abrasive media. The acidic + abrasive medium did not result in increased wear of RBC materials. The developed method using the 'Rub&Roll' wear machine in the current investigation has provided a sensitive wear test method to allow initial screening of resin-based composite materials compared with extracted human molars under the influence of different mechanical and erosive challenges.

Clinical performance of posterior restorations using a universal adhesive over moist and dry dentin: A 36-month double-blind split-mouth randomized clinical trial

OBJECTIVES

To evaluate the influence of dentin moisture on the clinical behavior of a universal adhesive on posterior teeth after 36 months of follow-up.

METHODS

Forty-five patients participated in this study. Following a split-mouth design, three operators placed 90 Class I/Class II restorations over moist dentin (MD) or dry (DD) (n = 45) with resin composite (Filtek Bulk Fill) and a universal adhesive used in the etch-and-rinse mode (Single Bond Universal). Each restoration was evaluated according to the FDI and USPHS criteria (postoperative sensitivity, fracture and retention, marginal staining, marginal adaptation, and recurrence of caries) at baseline and after 6-, 12-, and 36 months. For statistical analysis, Kruskal Wallis analysis of variance rank (α = 0.05) and Kaplan-Meier survival analysis were used.

RESULTS

No significant difference between groups was observed in each FDI criterion after 36 months of clinical evaluation (p > 0.05). The retention rates (confidence interval 95 %) were 97.37 % (86.5 - 99.5) for both MD and DD without significant difference between them (p > 0.05). Eight restorations (MD = 4; DD = 4) showed minimal marginal staining defects (p > 0.05). Two restorations were lost (MD = 1; DD = 1). Fifteen restorations (MD = 8; DD = 7) presented minor marginal discrepancies according to the FDI criteria (p > 0.05).

CONCLUSION

The clinical performance of the universal adhesive when applied in etch-and-rinse mode was not influenced by dentin moisture in posterior bulk-fill composite restorations.

CLINICAL SIGNIFICANCE

The level of dentin moisture appears not to influence the clinical efficacy of a universal adhesive when applied using the etch-and-rinse technique in posterior composite resin restorations.

Alternative Direct Restorative Materials for Dental Amalgam: A Concise Review Based on an FDI Policy Statement

Dental restorative procedures remain a cornerstone of dental practice, and for many decades, dental amalgam was the most frequently employed material. However, its use is declining, mainly driven by its poor aesthetics and by the development of tooth-coloured adhesive materials. Furthermore, the Minamata Convention agreed on a phase-down on the use of dental amalgam. This concise review is based on a FDI Policy Statement which provides guidance on the selection of direct restorative materials as alternatives to amalgam. The Policy Statement was informed by current literature, identified mainly from PubMed and the internet. Ultimately, dental, oral, and patient factors should be considered when choosing the best material for each individual case. Dental factors include the dentition, tooth type, and cavity class and extension; oral aspects comprise caries risk profiles and related risk factors; and patient-related aspects include systemic risks/medical conditions such as allergies towards certain materials as well as compliance. Special protective measures (eg, a no-touch technique, blue light protection) are required when handling resin-based materials, and copious water spray is recommended when adjusting or removing restorative materials. Cost and reimbursement policies may need to be considered when amalgam alternatives are used, and the material recommendation requires the informed consent of the patient. There is no single material which can replace amalgam in all applications; different materials are needed for different situations. The policy statement recommends using a patient-centred rather than purely a material-centred approach. Further research is needed to improve overall material properties, the clinical performance, the impact on the environment, and cost-effectiveness of all alternative materials.

Clinical comparison of high-viscosity glass-hybrid systems with a sculptable bulk-fill composite resin in different cavity types

OBJECTIVE

This randomized, double-blind clinical investigation assessed the performance of two high-viscosity glass-ionomer systems and a bulk-fill composite in different cavity types.

MATERIALS AND METHODS

In 146 participants, 360 (class I, II, and V) cavities were restored using three different materials (Equia Forte HT, Chemfill Rock, and SonicFill 2) with equal allocation. Using modified World Dental Federation criteria, restorations were assessed after 1 week, 6 months, and 18 months by an experienced examiner. Statistical analysis was conducted using Fisher's exact and Wilcoxon signed rank tests (α = 0.05).

RESULTS

After 18 months, 267 restorations were assessed in 116 participants. After 18 months, 5 Equia Forte HT restorations failed due to debonding and fracture. Only one loss was observed in the Chemfill Rock restorations. Equia Forte HT exhibited significantly lower retention than SonicFill 2 after 18 months (p = 0.019), irrespective of cavity type. At 1 week, 3 Class I restorations with SF showed postoperative sensitivity. The type of cavity did not affect the performance of the restorative materials used (p > 0.05).

CONCLUSION

Equia Forte HT and Chemfill Rock presented similar clinical performance regardless of color match. Equia Forte HT showed a lower performance compared to SonicFill 2.

CLINICAL SIGNIFICANCE

Glass-hybrid materials presented a lower performance in terms of color match or retention when compared to a sculptable bulk-fill composite resin.

Efficacy of digital guide-assisted implant restoration in anterior teeth aesthetics and its impact on labial bone mass

OBJECTIVE

To analyze the efficacy of digital guide-assisted implant restoration technique in enhancing the anterior teeth aesthetics and its impact on labial bone mass.

METHODS

We retrospectively analyzed clinical data from 90 patients who underwent maxillary anterior teeth implant restoration at The First People's Hospital of Fuyang, Hangzhou, from January 2021 to September 2023. The patients were divided into two groups: a conventional group (n=45, 45 implants, standard implant restoration) and a digital group (n=45, 45 implants, digital guide-assisted implant). We compared implant positional deviations, changes in dental plaque index (PLI), aesthetic effect scores, labial bone mass differences, and the occurrence of adverse reactions post-treatment between the two groups.

RESULTS

The digital group exhibited significantly less deviation in root position in the buccolingual and vertical directions, less neck deviation in the buccolingual and vertical directions, and less apical deviation than the conventional group (P=0.021, P=0.005, P=0.016, P=0.008, P=0.026, respectively). Three months postoperatively, the digital group demonstrated a significantly lower mean PLI (P<0.001), higher white and pink aesthetic scores (P=0.021, P=0.005), and increased alveolar ridge height and coronal and middle labial bone mass (P=0.006, P=0.015, P=0.008). Additionally, this group experienced lower incidence of adverse reactions (4.44% vs. 17.78%) compared with the conventional group (P=0.044).

CONCLUSION

The digital guide-assisted implant restoration significantly enhances implant accuracy, reduces bone resorption, improves aesthetic outcomes, and ensures higher safety.

Effect of a 3-second Off-label Exposure on the Depth of Cure of Eight Resin-based Composites

OBJECTIVES

This study evaluated the depth of cure (DoC) of eight resin-based composites (RBCs) photocured using one multipeak light-curing unit (LCU) on the standard output setting for the manufacturer's RBC recommended exposure time and at a higher irradiance for 3 seconds.

METHODS

Three conventional RBCs: Tetric EvoCeram (Evo), Tetric N-Ceram (Cer), Tetric Prime (Pri); and five bulk-fill: Tetric N-Ceram Bulk Fill (CerBF), Opus Bulk Fill APS (OpusBF), Opus Bulk Fill Flow APS (OpusF), Tetric PowerFill (PFill) and Tetric PowerFlow (PFlow) were examined. Only PFill and PFlow are formulated to be photocured in 3 seconds. The RBCs were packed into a metal mold and photocured using a Bluephase PowerCure LCU for the RBC manufacturer's recommended exposure time on the standard mode and using the 3-second high irradiance mode. After photocuring, the specimens were immersed in a solvent for 1 hour. The length of the remaining RBC was measured and divided by 2. Data were analyzed using two-way analysis of variance (ANOVA) followed by the Tukey post hoc multiple comparison test (α=0.05).

RESULTS

There was no significant difference in the DoC values for PFill and PFlow when photocured using the 3-second high irradiance protocol compared to the lower irradiance standard mode protocol. All other RBCs had significantly lower DoC values (p<0.001) when photocured off-label using the 3-second high irradiance mode.

CONCLUSION

Of the eight RBCs tested, only PFill and PFlow achieved the same DoC when the high irradiance 3-second curing method was used compared to when their longer lower irradiance protocol was used.

5.5-year-survival of CAD/CAM resin-based composite restorations in severe tooth wear patients

OBJECTIVES

Aim of this prospective study was to assess full mouth rehabilitation of severe tooth wear patients using minimally invasive CAD/CAM resin-based composite (RBC) restorations and direct veneers by evaluating restoration survival up to 5.5-years.

METHODS

Twenty-two patients with generalized severe tooth wear with functional and/or esthetic problems were included. Following minimally invasive preparation, CAD/CAM RBC restorations (LAVA Ultimate,3M) were adhesively luted, direct RBC veneers (Filtek Supreme XTE, 3M) were applied in the aesthetic region. Patients were recalled after 1m,1y,3y,5y and seen in between recalls by their general dentists or at the clinical study center if complaints occurred. Failures were categorized as F1 (severe deficiencies requiring replacement/extraction), F2 (localized deficiencies requiring re-cementation/repair) and F3 (small chippings requiring refurbishment/monitoring). Survival of indirect restorations was evaluated using lifetables and Kaplan-Meier-graphs, distinguishing between failure categories and tooth type (front teeth=FT, premolars=PM, molars=M). F1 + F2 and F1 + F2 + F3 failures were analyzed using Cox regression on the variables tooth type/ location, age, gender and VDO increase (p < 0.05).

RESULTS

568 indirect restorations and 200 direct veneers in 21 patients evaluated for up to 5.5-years. For indirect restorations, 96 failures were recorded (F1:6;F2:41;F3:49) and annual failure rates were 0.29%(FT), 1.56%(PM), 2.93%(M) for F1 +F2 and 0.53%(FT), 2.42%(PM), 6.11%(M) for F1 + F2 + F3. Reasons for failure were chipping fracture (48), adhesive fracture (32), complete debonding (7), caries (4), endodontic treatment (1) and reasons unknown (documentation general dentists, 4). Molar tooth type had a statistically significantly increased probability of failure compared with front teeth and premolars for F1 + F2 + F3 (p < 0.006). Direct veneer restorations showed 18 failures (F1:2;F2:9;F3:7).

SIGNIFICANCE

Minimally invasive CAD/CAM RBC restorations combined with direct RBC veneers showed an acceptable clinical mid-term survival for restorative rehabilitation of severely worn dentitions.

Longevity of composite restorations in posterior teeth placed by dental students: a 12-year retrospective study

OBJECTIVES

To evaluate the longevity of resin composite restorations placed in posterior teeth by dental students, using data from electronic records from 2008 to 2019.

MATERIALS AND METHODS

Demographic (gender and age) and clinical variables (dental group, position in dental arch, and the number of restored surfaces) were evaluated. The 5-year follow-up was assessed according to the day the restoration was placed. Kaplan-Meier curves were generated to calculate the annual failure rate. Data were analyzed by Chi-Square, Kruskal-Wallis, and Mann-Whitney tests (α = 0.05).

RESULTS

In total, 3.883 records relative to return periodicity were analyzed. The final sample consisted of 900 restorations from 479 patients. The majority were females, aged between 31 and 60. In total, 256 failures were reported (success rate = 78%), showing an annual failure rate of 2.05%. The main reasons for failures were restoration replacement (55.5%), endodontics (21.9%), prosthetics (14.5%) and extraction (8.2%). There was a higher risk of failure in restorations involving three or more surfaces (p = 0.000) and in patients over 60 years (p < 0.001). In females (p = 0.030), molars (p = 0.044), and maxillary teeth (p = 0.038) failed in a shorter time.

CONCLUSIONS

Resin composite restorations placed in permanent posterior teeth by dental students had high survival rates. The main reason for failure was the replacement of restorations. The age group and the number of restored surfaces significantly affected the success of the restorations.

CLINICAL RELEVANCE

The electronic health records over 12 years showed that 78% of the resin restorations in posterior teeth placed by dental students were successful for a minimum of five years.

Clinical evaluation of posterior restorations over wet and dry dentin using an etch-and-rinse adhesive: A 36-month randomized clinical trial

OBJECTIVES

To evaluate the clinical performance of posterior restorations over wet and dry dentin with an etch-and-rinse adhesive after 36 months of clinical service.

METHODS

Forty-five participants were recruited, each one had at least two posterior teeth that needed restoration. Ninety restorations were placed on Class I or Class II cavities. For the restoration protocol, a simplified etch-and-rinse adhesive (Adper Single Bond 2) was applied over wet (WD) or dry dentin (DD) and later restored with a bulk-fill composite (Filtek Bulk Fill) under rubber dam isolation. Each restoration was evaluated using the World Dental Federation (FDI) criteria after 6, 12, and 36 months of clinical service, regarding the following principal restoration characteristics: postoperative sensitivity, marginal discoloration, marginal adaptation, fracture of material and retention, and recurrence of caries. Kruskal Wallis analysis of variance rank (α = 0.05) and Kaplan-Meier survival analysis were used for statistical analysis.

RESULTS

After 36 months of clinical evaluation, no significant difference between groups was observed in each FDI criterion (p > 0.05). Twenty restorations (WD=10, DD=10) showed minor marginal staining, and twenty-two restorations (WD=11, DD=11) presented small marginal adaptation defects (p > 0.05). Four restorations were lost (WD = 2, DD = 2) and the fracture rates (95% confidence interval) were 94.9% for each one, without significant difference between wet and dry dentin (p > 0.05).

SIGNIFICANCE

The degree of dentin moisture does not seem to affect the clinical performance of a simplified etch-and-rinse adhesive in posterior restorations when the adhesive is applied vigorously over the dentine surface.

Promoting bond durability by a novel fabricated bioactive dentin adhesive

OBJECTIVE

To prepare a bioactive dentin adhesive and investigate its effect on promoting bonding durability of dentin.

METHODS

The mineralization of the bioactive glass with high phosphorus (10.8 mol% P2O5-54.2 mol% SiO2-35 mol% CaO, named PSC) and its ability to induce type I collagen mineralization were observed by SEM and TEM. The Control-Bond and the bioactive dentin adhesive containing 20 wt% PSC particles (PSC-Bond) were prepared, and their degree of conversion (DC), microtensile bond strength (μTBS), film thickness and mineralization performance were evaluated. To evaluate the bonding durability, dentin bonding samples were prepared by Control-Bond and PSC-Bond, and mineralizated in simulated body fluid for 24 h, 3 months, and 6 months. Then, the long-term bond strength and microleakage at the adhesive interface of dentin bonding samples were evaluated by microtensile testing and semiquantitative ELIASA respectively.

RESULTS

The PSC showed superior mineralization at 24 h and induced type I collagen mineralization to some extent under weakly alkaline conditions. For PSC-Bond, DC was 62.65 ± 1.20%, μTBS was 39.25 ± 4.24 MPa and film thickness was 17.00 ± 2.61 μm. PSC-Bond also formed hydroxyapatite and maintained good mineralization at the bonding interface. At 24 h, no significant differences in μTBS and interface microleakage were observed between the Control-Bond and PSC-Bond groups. After 6 months of aging, the μTBS was significantly higher and the interface microleakage was significantly lower of PSC-Bond group than those of Control-Bond group.

SIGNIFICANCE

PSC-Bond maintained bond strength stability and reduced interface microleakage to some extent, possibly reducing the occurrence of secondary caries, while maintaining long-term effectiveness of adhesive restorations.

In vitro remineralization by various ion-releasing materials of artificially demineralized dentin: A micro-CT study

OBJECTIVE

The aim of this study was to evaluate the remineralizing properties of ion-releasing restorative materials on pH cycling-induced carious dentin.

METHODS

Fifty sound molars were freshly extracted. The occlusal surfaces were abraded using water-cooled sandpaper (800 grit). The residual crowns were embedded in self-cured acrylic resin with the flat dentin surface exposed. A mesio-distal trench was created using a calibrated 0.5 mm deep occlusal reduction burr, and artificial dentin caries were generated by pH cycling. Then, teeth were randomly assigned to five groups according to the ion-releasing material used. For each sample, micro-CT acquisitions were performed at various intervals. Remineralization was assessed by mean gray value (MGV) measurements after registration and segmentation of the region of interest with 3D Slicer software. One-way repeated-measures ANOVA followed by Tukey's post hoc test was used to investigate the difference in MGVs among the various groups.

RESULTS

Only Cention Forte showed significantly increased MGVs after 4 weeks compared to demineralized dentin. MGVs were higher, but not significantly, after placement of the restorative materials, including in the resin composite control group. These results can be explained by the radiopacity of the materials.

SIGNIFICANCE

Cention Forte, the material with the highest radiopacity, showed a significant increase in the MGVs of artificially carious dentin after 4 weeks. However, the study of dentin remineralization by micro-CT could be impacted by the radiopacity of the restorative materials used. The relevance of this examination for the study of dentinal remineralization should be investigated.

Influence of surface sealants on the quality of posterior restorations with bulk-fill composites: A 4-year randomized clinical trial

OBJECTIVES

The aim of this study was to evaluate the clinical performance of surface sealants associated with a bulk-fill composite in posterior restorations after 4 years.

METHODS

A total of 174 posterior restorations were performed on 57 participants using a self-etch adhesive system and a bulk-fill composite. The groups were then divided into the following categories: 1) without surface sealant (NoS), 2) with surface sealant Biscover (Bisco, SBi), and 3) with surface sealant Permaseal (Ultradent, SPe). Restorations were evaluated using FDI criteria at baseline and after 1 and 4 years. Statistical analysis was conducted using Kaplan-Meier survival analysis and the Chi-square test (α = 0.05).

RESULTS

After 4 years, only one restoration was lost (1 in the NoS group). The fracture/retention rate (with 95% confidence interval) was 98% for NoS and 100% for both SBi and SPe (p = 0.76). The majority of secondary outcomes showed minor defects, with no significant differences among the groups (p > 0.05). However, significant differences were observed among the groups in terms of marginal staining and marginal adaptation (p = 0.03). In both items, twelve restorations (nine in NoS, one in SBi, and two in SPe) showed minor marginal discrepancies favoring the sealant groups (SBi and SPe).

SIGNIFICANCE

Regardless of the use of surface sealants, the bulk-fill composite restorations showed excellent clinical performance after 4 years. However, the groups that received sealants showed better marginal adaptation and less marginal discoloration compared to those that did not receive sealants.

Mechanical Properties and Ion Release from Fibre-Reinforced Glass Ionomer Cement

The aim of this study was to compare the mechanical properties and ion release from a commercially available resin-modified glass ionomer cement to a formulation reinforced by the addition of short glass fibres at various percentages. Methods: Three experimental groups were prepared by adding a mass ratio of 10%, 15% and 20% of short glass fibres to the powder portion of the cement from a capsule (GC Fuji II LC), while the control group contained no fibres. Microhardness (n = 12), fracture toughness, and flexural, compressive and diametral tensile strength (n = 8) were evaluated. To study ion release, readings were obtained utilising fluoro-selective and calcium-selective electrodes after 24 h, 7 days and 30 days (n = 12). The spatial distribution of fibres within the material was evaluated through scanning electron microscopy. The data were analysed using one-way ANOVA with a Bonferroni adjustment. Results: The findings suggest that elevating fibre weight ratios to 20 wt% results in improved mechanical properties (p < 0.05) in microhardness, flexural strength, diametral tensile strength and fracture toughness. In terms of ion release, a statistically significant difference (p < 0.001) was observed between the groups at the conclusion of 24 h and 7 days, when the fluoride release was much higher in the control group. However, after 30 days, no significant distinction among the groups was identified (p > 0.05). Regarding calcium release, no statistically significant differences were observed among the groups at any of the evaluated time points (p > 0.05). SEM showed the fibres were homogeneously incorporated into the cement in all experimental groups. Conclusions: Resin-modified glass ionomer enhanced with short glass fibres at a weight loading of 20% showcased the most favourable mechanical properties while concurrently maintaining the ability to release fluoride and calcium after a 30-day period.

Evaluating Glass Ionomer Cement Longevity in the Primary and Permanent Teeth-An Umbrella Review

The aim of this umbrella review was to evaluate the longevity of glass ionomer cement (GIC) as a restorative material for primary and permanent teeth. Research in the literature was conducted in three databases (MedLine/PubMed, Web of Science, and Scopus). The inclusion criteria were: (1) to be a systematic review of clinical trials that (2) evaluated the clinical longevity of GICs as a restorative material in primary and/or permanent teeth; the exclusion criteria were: (1) not being a systematic review of clinical trials; (2) not evaluating longevity/clinical performance of GICs as a restorative material; and (3) studies of dental restorative materials in teeth with enamel alterations, root caries, and non-carious cervical lesions. Twenty-four eligible articles were identified, and 13 were included. The follow-up periods ranged from 6 months to 6 years. Different types of GICs were evaluated in the included studies: resin-modified glass ionomer cement (RMGIC), compomers, and low- and high-viscosity glass ionomer cement. Some studies compared amalgam and composite resins to GICs regarding longevity/clinical performance. Analyzing the AMSTAR-2 results, none of the articles had positive criteria in all the evaluated requisites, and none of the articles had an a priori design. The criteria considered for the analysis of the risk of bias of the included studies were evaluated through the ROBIS tool, and the results of this analysis showed that seven studies had a low risk of bias; three studies had positive results in all criteria except for one criterion of unclear risk; and two studies showed a high risk of bias. GRADE tool was used to determine the quality of evidence; for the degree of recommendations, all studies were classified as Class II, meaning there was still conflicting evidence on the clinical performance/longevity of GICs and their recommendations compared to other materials. The level of evidence was classified as Level B, meaning that the data were obtained from less robust meta-analyses and single randomized clinical trials. To the best of our knowledge, this is the first umbrella review approaching GIC in permanent teeth. GICs are a good choice in both dentitions, but primary dentition presents more evidence, especially regarding the atraumatic restorative treatment (ART) technique. Within the limitation of this study, it is still questionable if GIC is a good restorative material in the medium/long term for permanent and primary dentition. Many of the included studies presented a high risk of bias and low quality. The techniques, type of GIC, type of cavity, and operator experience highly influence clinical performance. Thus, clinical decision-making should be based on the dental practitioner's ability, each case analysis, and the patient's wishes. More evidence is needed to determine which is the best material for definitive restorations in permanent and primary dentition.

Profiling Elastoplastic and Chemical Parameters to Assess Polymerization Quality in Flowable Bulk-Fill Composites

In the chronology of polymer-based composite materials, flowable bulk-fill composites represent the most recent development. They enable a significant reduction in treatment time by being applied in larger increments of 4 to 5 mm. The aim of the investigation was to assess the polymerization quality and mechanical performance of a new formulation that has just entered the market and was still in experimental formulation at the time of the investigation, and to compare these results in the context of clinically established materials of the same category. Adequate curing in increments of up to 4 mm could be confirmed both by profiling the elastoplastic material behavior of large increments in 100 µm steps and by real-time assessment of the degree of conversion and the associated polymerization kinetic. A slightly lower amount of filler in the experimental material was associated with slightly lower hardness and elastic modulus parameters, but the creep was similar and the elastic and total indentation work was higher. The kinetic parameters were assigned to the specific characteristics of each tested material. The mechanical macroscopic strength, evaluated in a three-point bending test and supplemented by a reliability analysis, met or exceeded the standards and values measured in clinically established materials, which for all materials is related to the higher flexibility of the beams during testing, while the modulus of elasticity was low. The low elastic modulus of all flowable bulk-fill materials must be taken into account when deciding the clinical indication of this material category.

Comparative study of two bioactive dental materials

OBJECTIVES

New bioactive materials were introduced to not only restore the lost dental hard tissue but also to release fluoride that inhibits demineralization and occurrence of secondary caries. The current study thus aims to assess Fluoride release as well as the mechanical and physical properties of two new commercially available bioactive restorative materials.

METHODS

Two materials, Cention® Forte (CF) (Ivoclar Vivadent), Surefil one™ (SO) (Denstply Sirona), were evaluated in terms of fracture toughness (FT), flexural strength (FS), flexural modulus (FM) (ISO 4049), compressive strength (CS), and Vickers hardness (VH). In addition, thermogravimetric analysis (TGA) was performed, as well as pH measurements and quantification of Fluoride release after immersion in distilled water at times of 0, 7, 14 and 21 days. The sealing ability was evaluated using silver nitrate dye penetration on natural teeth. Finally, Energy-Dispersive X-Ray Spectroscopy (EDX) was used to investigate the surface composition of the two studied material surfaces. The data were statistically analyzed using Independent T-Tests; the chosen significance level was α = 0.05.

RESULTS

CF had significantly higher FT values compared to SO (p = 0.001). Also the FS results showed that CF had significantly higher values (90.11 MPa), followed by SO (22.15 MPa). The CS values showed the same order with significantly higher values for CF (231.79 MPa). While the FM and VH showed the reverse order with SO having significantly higher values than CF. pH measurements showed that CF evolved towards significantly higher pH values after 3 weeks in distilled water, while thermal properties showed more stability and higher resistance to degradation for CF compared to SO. The silver nitrate penetration results showed significantly better sealing ability for CF compared to the self-adhesive SO. Finally, EDX surface analysis results were consistent with the release profiles and confirmed the composition of the two tested materials.

SIGNIFICANCE

Both materials, demonstrated enhanced Fluoride release ability, and hence good remineralisation potential in vitro that could prevent recurrent carious lesions in vivo. The composition based on acrylic polymerization showed better mechanical resistance to bending and fracture, and higher sealing ability than those based on acid base reaction.

5-year clinical performance of posterior bulk-filled resin composite restorations: A double-blind randomized controlled trial

OBJECTIVES

The aim of this double-blind, and randomized controlled clinical trial was to evaluate the 5-year clinical performance of posterior resin composite restorations placed with the incremental filling technique [IF] or the bulk-fill technique [BF]. Two different adhesive systems were used: etch-&-rinse (ER) or self-etch (SE).

METHODS

Posterior dental teeth of 72 participants (n = 236), with a cavity depth of at least 3 mm, were randomly divided into four groups. Restorations were applied with either Tetric N-Bond or Tetric N-Bond SE. The composite resin Tetric N-Ceram Bulk-Fill was placed either with IF or BF. Restorations were evaluated using FDI criteria at baseline and after 1, 2, 3, 4, and 5 years. Statistical analysis was performed using the Wilcoxon Signed rank test (a=0.05).

RESULTS

Two hundred and four restorations were evaluated after 5 years. Eleven restorations were considered 'failed', ten due to fracture (4 IF and 6 BF) and one due to secondary caries (IF). The annual failure rate was 1.2% for BF and 1% for IF (p = 0.35). When comparing BF and IF, no significant differences were found for any of the parameters evaluated (p > 0.05). Regarding the adhesive systems, 44 and 51 restorations showed minor problems in terms of marginal adaptation and staining, with significantly more marginal discoloration when the self-etch adhesive was used (p = 0.002).

SIGNIFICANCE

The bulk-fill restorative technique showed good clinical behavior compared to the incremental filling technique, especially when using an etch-&-rinse adhesive, after 5 years of clinical evaluation.

Compomers for the restorative treatment of dental caries in primary teeth: An umbrella review

OBJECTIVES

This umbrella review comprehensively appraised the evidence on the use of compomers in comparison to other dental filling materials for restorative treatment of decayed primary teeth.

DATA

The literature search was conducted based on the question: "Is the use of compomers as a dental filling material more successful in the restorative treatment of decayed primary teeth than other dental filling materials?" No language restriction was applied and systematic reviews published up to May 2023 were included. The ROBIS tool was used to assess the methodological quality of the included systematic reviews. Data were extracted for narrative synthesis, considering the restoration failure/success outcomes.

SEARCH

Online search was conducted in three databases (PubMed/Medline, Embase and Cochrane library).

STUDY SELECTION

The electronic search yielded a total of 779 publications. Finally, 18 systematic reviews were included in this umbrella review. Four systematic reviews presented a low risk of bias, 11 presented an unclear risk of bias and three presented a high risk of bias. Most systematic reviews presenting low risk of bias reported no difference in the success rates of compomers compared to other dental filling materials used for restoration of decayed primary teeth. Studies that found a significant difference or that made clear recommendations towards the use of compomers were commonly rated with a high risk of bias.

CONCLUSION

Compomers are similar to other dental filling materials for the placement of direct restorations in primary teeth.

CLINICAL SIGNIFICANCE

The results of this umbrella review indicate a similar clinical performance of compomers compared to other materials containing a resin component for direct restoration in primary teeth. Therefore, the choice of restorative material will depend on multiple factors, such as clinician's skills/preferences, patients' wishes, costs, and cavity type/location.

Concept of a Novel Glass Ionomer Restorative Material with Improved Mechanical Properties

The objective of this study was to transfer the concept of ductile particle reinforcement to restorative dentistry and to introduce an innovative glass ionomer material that is based on the dispersion of PEG-PU micelles. It was hypothesized that reinforcing a conventional glass ionomer in this way increases the flexural strength and fracture toughness of the material. Flexural strength and fracture toughness tests were performed with the novel reinforced and a control glass ionomer material (DMG, Hamburg, Germany) to investigate the influence of the dispersed micelles on the mechanical performance. Transmission electron microscopy was used to identify the dispersed micelles. Fracture toughness and flexural strength were measured in a 3-point-bending setup using a universal testing machine. Before performing both tests, the specimens were stored in water at 37 °C for 23 h. The fracture toughness (MPa∙m0.5) of the novel glass ionomer material (median: 0.92, IQR: 0.89-0.94) was significantly higher than that of the control material (0.77, 0.75-0.86, p = 0.0078). Significant differences were also found in the flexural strength (MPa) between the reinforced (49.7, 45.2-57.8) and control material (41.8, 40.6-43.5, p = 0.0011). Reinforcing a conventional glass ionomer with PEG-PU micelles improved the mechanical properties and may expand clinical applicability of this material class in restorative dentistry.

Food Insecurity and Dental Caries in Rural Mexican Populations

Objective

Food insecurity (FI) is a priority for government and health organizations. Over 95% of the world's population has a carious lesion or will develop one before death. This study evaluated the association between FI and oral health in two rural communities in Chiapas, Mexico.

Methods

The study was conducted with patients attending an oral health campaign for dental checkups. Data were collected between April and August 2017 using the Latin-American and Caribbean Scale of Food Security (ELCSA) and the International Caries Detection and Assessment System (ICDAS). We included 209 participants from Siltepec and Huehuetan, Mexico; 67% were women.

Results

The results of the ELCSA were mild FI in 43% (n = 91), moderate FI in 22% (n = 45), and severe FI (n = 6) in 3%; 32% had food security. The ICDAS results were initial decay with a mean of 6.22, moderate decay with a mean of 1.81, and extensive decay with a mean of 1.77.

Conclusions

FI is associated with dental caries, and food-insecure individuals have a higher probability of severe dental caries. In this study, the FI level was lower than in other rural populations in Mexico. Identifying these individuals and addressing the factors related to FI can be useful in the rural communities.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2022 dental literature to briefly touch on several topics of interest to modern restorative dentistry. Each committee member brings discipline-specific expertise in their subject areas that include (in order of the appearance in this report): prosthodontics; periodontics, alveolar bone, and peri-implant tissues; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence the daily dental treatment decisions of the reader with an emphasis on innovations, new materials and processes, and future trends in dentistry. With the tremendous volume of literature published daily in dentistry and related disciplines, this review cannot be comprehensive. Instead, its purpose is to update interested readers and provide valuable resource material for those willing to subsequently pursue greater detail on their own. Our intent remains to assist colleagues in navigating the tremendous volume of newly minted information produced annually. Finally, we hope that readers find this work helpful in managing patients.

High-viscosity glass-ionomer cement or composite resin for restorations in posterior permanent teeth? A systematic review and meta-analyses

OBJECTIVES

Answer the PICO question: Do class I and II posterior restorations in permanent teeth placed with high-viscosity glass-ionomer cement (HV-GIC) fail more than composite resin (CR) restorations?

DATA

The study was registered in the PROSPERO database (CRD42020138290). Randomized and controlled clinical trials, comparing the performance of HV-GIC and CR in load bearing cavities of posterior permanent teeth were included. Cochrane risk of bias tool and GRADE were used to assess the quality and certainty of the evidence. Meta-analyses were performed for clinical outcomes on USPHS and FDI criteria for 12-, 24- and 36-months follow-ups.

SOURCES

PubMed, Scopus and Web of Science were last searched on April 2, 2022, without language or date restrictions. Reference lists of primary studies and their related article link in PubMed were manually searched.

STUDY SELECTION

Ten studies were included, while data from 8 were used for the meta-analyses. A total of 849 HV-GIC and 800 CR restorations were followed. The primary outcome was the fracture/retention of the restoration, with a comparable performance for both materials on all follow-ups. The 36 months follow-up for class I restorations (longest) showed risk difference of -0,00 (95%CI -0,03 to 0,03; p = 0,98) and no heterogeneity (p = 0,98, I2=0%). The certainty of the evidence is moderate, as all included studies were at an uncertain risk of bias.

CONCLUSIONS

HV-GIC and CR presented comparable clinical performance in posterior permanent teeth up to 36 months. HV-GIV wear in class I restorations followed by 24 months was the only poorer result compared to CR.

CLINICAL SIGNIFICANCE

Conservative load bearing cavities in permanent posterior teeth can be restored with HV-GIC with comparable clinical performance to CR expected at least up to 3 years. HV-GIC is a valuable direct restorative option for posterior teeth in high caries risk patients, in which CR is frequently associated with failure.

Marginal Adaptation of In Vitro Class II Restorations Made Out of Bulk or Conventional Composite Using Single- or Multi-Layered Techniques

Objective: Testing the influence of various restorative materials (conventional or bulkfill composites) and filling techniques (single- or multi-layered techniques) on the in vitro marginal adaptation of large class II direct composites with supra and sub-gingival margins subjected to thermomechanical loading (TML). Methods: A total of 40 prepared teeth were attributed randomly to five experimental groups. In Group 1, restorations were made of multi-layered high-viscosity conventional composite (Tetric EvoCeram); in Groups 2 and 3, restorations were made of a high viscosity bulkfill composite (Tetric EvoCeram Bulk Fill) applied in one (Group 2) or three layers (Group 3); in Groups 4 and 5, restorations were made of a flowable bulkfill composite (SDR flow) applied in one (Group 4) or two layers (Group 5), covered with a layer of high-viscosity conventional composite (Ceram-X Universal). A single adhesive (OptiBond FL) was used in all groups. All specimens were submitted to a staged TML comprising three phases (2 × 500,000 and 1,000,000 cycles) at 50 N with 3350 thermal cycles (5 to 55 °C) every 500,000 cycles. The tooth-restoration interfaces on proximal surfaces were evaluated quantitatively by scanning electron microscopy, before and after each TML phase, hence at three timepoints (T0, T1, T2 and T3). The following segments were considered for evaluation: proximal, vertical enamel margins (assessed individually on both restoration sides), cervical enamel (restoration side above CEJ) and cervical dentin margin (restoration side below the CEJ). Results: TML induced a significant reduction in continuous adaptation at both enamel and dentin margins in all groups, with percentages of continuous margins ranging from 75.2 to 91.8% at T0, and decreasing to values ranging from 21.3 to 73.9% at T3. Both composite systems and layering protocols had a significant influence on marginal adaptation of the restorations, with statistical associations depending on the restoration group and the timepoint considered. Defective margins in enamel were all of a cohesive nature with micro-fractures, while in dentin, interfacial gaps were the main defect observed. Conclusions/Clinical significance: The present results highlighted significant degradation of marginal adaption after long-term in vitro fatigue test using materials even with high-viscosity conventional resin composites, applied with a proper layering approach in medium-large sub-gingival cavities. While no significant differences were observed at the dentin cervical margins, there was a tendency for better adaptation at the enamel margin when using a higher modulus material with a multi-layered technique.

Retrospective Clinical Evaluation of RMGIC/GIC Class V Restorations

The aim of this retrospective study was to evaluate the clinical performance of glass-ionomer cement (GIC) and resin-modified glass-ionomer cement (RMGIC) materials in Class V carious cervical lesions restored by dental students. Ninety-six (96) restorations performed with either GIC (Fuji IX) (n = 39) or RMGIC (Fuji II LC) (n = 57) were evaluated using the modified USPHS criteria by two independent investigators at two follow-up evaluations (two years apart). The Fisher statistical test was used to compare USPHS criteria and examine significant differences, with a significance level set at p < 0.05. The Kaplan-Meier algorithm was used to calculate the survival probability. The overall success rate of Class V restorations was 72.9% at the second follow-up evaluation, with restorations ranging in age from 2.5 to 3.5 years. The RMGIC (Fuji II LC) restorations exhibited a significantly higher overall success rate compared to the GIC (Fuji IX) restorations (p = 0.0104). Significant differences were observed in retention (p = 0.0034) and color match (p = 0.0023).

The effect of varying monocalcium phosphate and polylysine levels on dental composite properties

OBJECTIVES

The aim was to quantify effects of polylysine (PLS, 2 or 5 wt%) and monocalcium phosphate (MCP, 4 or 8 wt%) on properties of dental composites.

METHODS

Light-activated, lower surface polymerisation kinetics versus sample depth (1-4 mm) of 4 formulations were quantified using ATR-FTIR. Water sorption and solubility (at 1 week) were assessed following ISO/4049. PLS release (over 1 month) and biaxial flexural strength (over 6 months) of fully-cured, water-immersed, 1 mm thick discs were determined. Surface mineral precipitation, following immersion in simulated body fluid (SBF), was assessed by SEM. Z250 was used as a conventional composite comparator.

RESULTS

With 40s light exposure, increasing depth (from 1 to 4 mm) led to enhanced delay before polymerisation (from 3 to 17s) and decreased final conversion (72-66%) irrespective of PLS and MCP level. Increasing PLS and MCP raised solubility (4-13 μg/mm3). Water sorption (between 32 and 55 μg/mm3) and final PLS release (8-13% of disc content) were raised primarily by increasing PLS. Higher PLS also reduced strength. Strength reached minimum values (69-94 MPa) at 3 months. Surface mineral deposition was enhanced by increased MCP. For Z250, polymerisation delays (3-6s) and final conversions (55-54%) at 1-4 mm depth, solubility (0 μg/mm3), water sorption (16 μg/mm3) and strength (180 MPa) were all significantly different.

CONCLUSION

Delay time increased whilst final conversion decreased with thicker samples. Higher PLS enhances its percentage release, but lower level is required to keep water sorption, solubility and mechanical properties within ISO 4049 recommendations. Doubling MCP raises solubility and enhances minerals reprecipitation with minimal mechanical property compromise.