An overview of reasons for the placement and replacement of restorations

Evaluation of adhesive properties and enzymatic activity at the hybrid layer of a simplified adhesive loaded with 0.2% Cu and 5% ZnO nanoparticles: a Randomized Clinical Trial and ex vivo analysis

OBJECTIVE

The aim of this study was to evaluate the effect of an adhesive loaded with 0.2% cooper (Cu) and 5% zinc oxide (ZnO) nanoparticles (Nps) on its adhesive properties and enzymatic activity at the hybrid layer ex vivo in a randomized clinical model.

METHODS

Fifteen patients participated in this study, and a total of 30 third molars were used. Occlusal cavities (4 × 4 × 2 mm) were made in each tooth, and randomly divided into 2 groups: (i) Experimental group: commercial adhesive loaded with 0.2wt% CuNps and 5wt% ZnONps; and (ii) Control Group: non-loaded commercial adhesive. Teeth were restored with resin composite. Thirty days later, extractions were performed. Extracted teeth were longitudinally sectioned. Nps in powder were characterized by field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray (EDX) analysis. Microtensile bond strength (μTBS), degree of conversion (DC), and nanoleakeage (NL) tests were executed. In situ zymography (Zym) was performed to evaluate the gelatinolytic activity at the hybrid layer. Student's t-test (α = 0.05) was applied for all tests.

RESULTS

μTBS and DC did not show significant differences (p > 0.05) between both groups. However, NL and gelatinolytic activity at the hybrid layer showed significant values (p < 0.05) for experimental group in comparison with control group.

CONCLUSION

The addition of 0.2% CuNps and 5% ZnONps to a universal adhesive decreases NL and gelatinolytic activity at the hybrid layer, without jeopardizing its adhesive properties.

SIGNIFICANCE

This randomized clinical trial with ex vivo analysis demonstrate that a commercial adhesive modified with 0.2wt% Cu and 5wt% ZnO Nps that does not affect its adhesive properties, reducing gelatinolytic activity and nanoleakage at the hybrid layer, which should contribute to an improvement of long term bonding-dentine clinical performance.

Comparing modified USPHS and FDI criteria for the assessment of glass ionomer restorations in primary molars utilising clinical and photographic evaluation

PURPOSE

To compare the applicability of modified US Public Health Service (USPHS) and FDI criteria for evaluating glass ionomer cement (GIC) restorations in primary posterior teeth through digital image analysis.

METHODS

This comparative analytic study was conducted at the Children's Dental Clinic RSKGM FKG UI, involving 40 GIC restorations on lower first primary molars in children aged 4-9 years. After cleaning, the restorations were assessed clinically using modified USPHS and FDI criteria before taking digital images, then the collected images were re-evaluated using both sets of criteria, and the clinical assessment results were compared to the digital image assessment results.

RESULTS

Statistical analysis revealed significant differences between the clinical evaluation of GIC restorations in primary teeth and their corresponding digital photographs when using the modified USPHS criteria, and although the use of FDI criteria yielded different results, these differences were not statistically significant.

CONCLUSION

The assessment of GIC restorations through digital images aligns more closely with clinical assessments using the FDI criteria compared to the modified USPHS criteria.

Attitudes regarding a warranty and the expected longevity of dental treatment amongst New Zealand dentists, dental students, and patients: a mixed methods survey

OBJECTIVES

To investigate and compare estimates of the longevity of dental treatment, expectations for free remedial treatment, and attitudes about formal dental warranties among dentists, students, and patients.

MATERIALS AND METHODS

This is a mixed-method cross-sectional questionnaire survey with convenience sampling from dentists, dental students, and patients in New Zealand. A questionnaire was distributed to New Zealand dentists (n = 28) and final-year dental students (n = 27). A separate questionnaire was provided to patients in a university dental clinic (n = 43). Mann-Whitney U, Chi-square and Pearson Correlation, and Binary logistic regression tests were used to test for differences between groups and correlations amongst variables. Qualitative data were analysed thematically.

RESULTS

Dentists believed that their posterior composite resin restorations would last longer (p = 0.014), would remediate failed crowns for longer (p = 0.002) and would provide longer crown warranties (p = 0.003) compared to students. Patients had higher expectations for restoration longevity and free remediation for failed treatment. Students were generally more willing to provide warranties. Crowns were perceived to be the most warrantable, while endodontic treatment was the least warrantable. Recall attendance, mechanical failure, and adequate oral hygiene were commonly proposed as warranty conditions for restorations and crowns. There was little consensus about complete dentures and endodontic treatment.

CONCLUSIONS

There are significant disparities between the expectations of patients and clinicians regarding treatment longevity and free remediation times. Clinicians, in general, are willing to provide free remediation within a specified time frame, except for endodontic treatment, but are hesitant to provide formal dental warranties.

Do bioactive materials show greater retention rates in restoring permanent teeth than non-bioactive materials? A systematic review and network meta-analysis of randomized controlled trials

OBJECTIVES

To answer the following research question: does the clinical evaluation of restorations on permanent teeth with bioactive materials show greater retention rates than those with non-bioactive materials?

MATERIALS AND METHODS

A search strategy was used in the following databases: MEDLINE via PubMed, Scopus, Web of Science, LILACS, BBO, Embase, The Cochrane Library, and OpenGrey. Randomized controlled trials (RCTs), with a minimum of 2-year follow-up and evaluating at least one bioactive material in permanent teeth were included. Risk of bias was detected according to the Cochrane Collaboration tool for assessing the risk of bias (RoB 2.0), and network meta-analysis was performed using a random-effects Bayesian-mixed treatment comparison model.

RESULTS

Twenty-seven studies were included. The success of the restorations was assessed using modified USPHS system in 24 studies and the FDI criteria in 3 studies. Network meta-analysis revealed three networks based on restoration preparations. Resin composites were ranked with higher SUCRA values, indicating a greater likelihood of being the preferred treatment for class I, II, and III restorations. In class V, resin-modified glass ionomer cement was ranked with the highest value.

CONCLUSION

Bioactive restorative materials showed similar good clinical performance in terms of retention similarly to conventional resin composites.

CLINICAL SIGNIFICANCE

The findings must be interpreted with caution because many RCT on restorative materials aim to verify the equivalence of new materials over the gold standard material rather than their superiority. The present systematic review also suggests that new RCT with longer follow-up periods are necessary.

Enhancing dentin bonding quality through Acetone wet-bonding technique: a promising approach

Objective: This paper aimed to assess the impact of the acetone wet-bonding (AWB) technique on dentin bonding and to investigate its potential underlying mechanisms. Materials and Methods: Caries-free third molars were sliced, ground, etched, water-rinsed. Then the specimens were randomly allocated to four groups according to the following pretreatments: 1. water wet-bonding (WWB); 2. ethanol wet-bonding (EWB); 3. 50% (v/v) acetone aqueous solution (50%AWB); 4. 100% acetone solution (AWB). Singlebond universal adhesive was then applied and composite buildups were constructed. The microtensile bond strength (MTBS), failure modes and interface nanoleakage were respectively evaluated after 24 h of water storage, 10,000 times of thermocycling or 1-month collagenase ageing. In situ zymography and contact angle were also investigated. Results: Acetone pretreatment preserved MTBS after thermocycling or collagenase ageing (p < 0.05) without affecting the immediate MTBS (p > 0.05). Furthermore, AWB group manifested fewer nanoleakage than WWB group. More importantly, the contact angle of the dentin surfaces decreased significantly and collagenolytic activities within the hybrid layer were suppressed in AWB group. Conclusion: This study suggested that the AWB technique was effective in enhancing the dentin bond durability by increasing the wettability of dentin surface to dental adhesives, removing residual water in the hybrid layer, improving the penetration of adhesive monomer, and inhibiting the collagenolytic activities. Clinical significance: The lifespan of adhesive restorations would be increased by utilization of acetone wet-bonding technique.

Retrospective clinical study on the performance and aesthetic outcome of pressed lithium disilicate restorations in posterior teeth up to 8.3 years

OBJECTIVES

Evaluation of cumulative survival and complication rate of monolithic lithium disilicate inlays and partial crowns performed by supervised undergraduate students up to 8.3 years of clinical service.

MATERIALS AND METHODS

In this retrospective clinical study 143 lithium disilicate posterior restorations (IPS e.max Press) were examined according to the FDI criteria. A standardised questionnaire was used to determine patient satisfaction. The aesthetic outcome was evaluated by dentists and dental technicians using intraoral photographs. Data were descriptively analysed. Cumulative survival and success rates were calculated using Kaplan-Meier estimation.

RESULTS

The cumulative survival rate of lithium disilicate restorations was 97.5% after a mean service time of 5.9 years and 95.0% after 8.3 years. The cumulative success rate decreased from 94.4% after 5.9 years to 30.7% after 8.3 years. Repairs were required for 7 restorations (4.9%), and 5 (3.5%) were classified as failures. The results of the questionnaire indicate a high level of patient satisfaction. The subjective aesthetics were assessed more critically by dental technicians compared to dentists.

CONCLUSION

Lithium disilicate posterior restorations survived successfully up to 8.3 years when carried out by undergraduate students.

CLINICAL RELEVANCE

Pressed lithium disilicate glass ceramic inlays and partial crowns are reliable treatment options in posterior teeth.

Release Kinetics of Monomers from Dental Composites Containing Fluoride-Doped Calcium Phosphates

This study analyse the type of release kinetic of specific monomers from dental resin composites containing various fluoride-doped calcium phosphates. The release behavior of urethane dimethacrylate (UDMA), ethoxylated bisphenol-A dimethacrylate (bis-EMA) and 1.6-hexanediol ethoxylate diacrylate (HEDA) was evaluated over a period of 35 days. Two tailored calcium phosphates doped with different concentrations of fluoride salts (VS10% and VS20%) were prepared and incorporated in the dimethacrylate matrix at various concentrations to generate a range of experimental composites. The release kinetics were characterized using mathematical models such as zero-order, first-order, Peppas and Higuchi models. The results showed that the first-order model best described the release kinetics. UDMA and HEDA exhibited significant differences in release compared to bis-EMA from day 1, while no significant differences were observed between UDMA and HEDA, except on day 35, when UDMA exhibited a higher release rate than HEDA. When comparing the release of each monomer, VS20-R20% had the highest total release percentage, with 3.10 ± 0.25%, whereas the composite VS10-R5% showed the lowest release percentage, with a total of 1.66 ± 0.08%. The release kinetics were influenced by the composition of the resin composites and the presence of calcium fluoride and sodium fluoride in the calcium phosphate played a role in the maximum amounts of monomer released. In conclusion, the release of monomers from the tested resin composites followed a first-order kinetic behaviour, with an initial rapid release that decreased over time. The composition of the resin monomers and the presence of fluoride salts influenced the release kinetics. The VS10-R5% and VS10-R10% resin composites exhibited the lowest total monomer release, suggesting its potential favourable composition with reduced monomer elution. These findings contribute to understanding the release behavior of dental resin composites and provide insights for the development of resin-based bioactive dental materials.

Fatigue and wear of human tooth enamel: A review

Human tooth enamel must withstand the cyclic contact forces, wear, and corrosion processes involved with typical oral functions. Furthermore, unlike other human tissues, dental enamel does not have a significant capacity for healing or self-repair and thus the longevity of natural teeth in the oral environment depends to a large degree on the fatigue and wear properties of enamel. The purpose of this review is to provide an overview of our understanding of the fatigue and wear mechanisms of human enamel and how they relate to in vivo observations of tooth damage in the complex oral environment. A key finding of this review is that fatigue and wear processes are closely related. For example, the presence of abrasive wear particles significantly lowers the forces needed to initiate contact fatigue cracking while subsurface fatigue crack propagation drives key delamination wear mechanisms during attrition or attrition-corrosion of enamel. Furthermore, this review seeks to bring a materials science and mechanical engineering perspective to fatigue and wear phenomena. In this regard, we see developing a mechanistic description of fatigue and wear, and understanding the interconnectivity of the processes, as essential for successfully modelling enamel fatigue and wear damage and developing strategies and treatments to improve the longevity of our natural teeth. Furthermore, we anticipate that this review will stimulate ideas for extending the lifetime of the natural tooth structure and will help highlight where our understanding is too limited and where additional research into fatigue and wear of human tooth enamel is warranted.

Bioactive Restorative Dental Materials-The New Frontier

Bioactive materials for dental resin restorations are a rising field of investigation exploring treatment strategies for reducing the recurrence of carious lesions. The current effort has been directed toward developing dental materials that can inhibit biofilms and prevent tooth mineral loss. Bioactive resin materials have shown the potential to interfere with polymicrobial consortia in vivo and help maintain the lifespan of restorations.

Incorporation of chlorhexidine in self-adhesive resin cements

The aim of this study was to evaluate the maximum amount of chlorhexidine (CHX) that could be incorporated to self-adhesive resin cements to add antibacterial effect without affecting the physical properties. The CHX was incorporated into a commercial self-adhesive resin cement at mass fractions of 0.5-15 wt%, and the CHX-release profile, antibacterial effect, flexural and bond strengths of experimental cements were evaluated. Increasing the CHX content from 5 to 15 wt% resulted in a higher released concentration of CHX. In agar diffusion tests, experimental cements containing 5, 10, and 15 wt% CHX produced inhibition zones against oral bacteria. In flexural strength and shear bond strength to dentin, no significant reduction was observed with the incorporation of 5 wt% CHX. This in vitro study suggests that the addition of 5 wt% CHX yielded an antibacterial self-adhesive cement and had no adverse effect on the flexural and shear bond strengths.

Applications of scanning electron microscopy and focused ion beam milling in dental research

The abilities of scanning electron microscopy (SEM) and focused ion beam (FIB) milling for obtaining high-resolution images from top surfaces, cross-sectional surfaces, and even in three dimensions, are becoming increasingly important for imaging and analyzing tooth structures such as enamel and dentin. FIB was originally developed for material research in the semiconductor industry. However, use of SEM/FIB has been growing recently in dental research due to the versatility of dual platform instruments that can be used as a milling device to obtain low-artifact cross-sections of samples combined with high-resolution images. The advent of the SEM/FIB system and accessories may offer access to previously inaccessible length scales for characterizing tooth structures for dental research, opening exciting opportunities to address many central questions in dental research. New discoveries and fundamental breakthroughs in understanding are likely to follow. This review covers the applications, key findings, and future direction of SEM/FIB in dental research in morphology imaging, specimen preparation for transmission electron microscopy (TEM) analysis, and three-dimensional volume imaging using SEM/FIB tomography.

Comparison of two clinical approaches based on visual criteria for secondary caries assessments and treatment decisions in permanent posterior teeth

Background

This cross-sectional study aimed to compare two clinical approaches based on visual criteria for secondary caries assessments and treatment decisions in permanent posterior teeth.

Methods

The two clinical visual criteria tested for the assessments of restored teeth were: FDI criteria—based on the caries presence, marginal adaptation and staining criteria, adapted from the FDI (International Dental Federation) criteria and CARS criteria—"Caries Associated with Restorations or Sealants" (CARS) criteria described by the International Caries Classification and Management System. Adults were randomized according to the criteria. One calibrated examiner assessed the restorations and assigned the treatment according to the criteria. The primary outcome was replacement indication.

Results

A total of 185 patients were included, totalling 718 restorations. The strongest correlation founded between the methods was for the presence of caries lesions (Rho = 0.829). A moderate correlation (Rho = 0.420) was founded between the treatment decisions proposed by the CARS and by the FDI criteria. The multilevel regression analysis showed that the FDI criteria indicated five times more replacements when compared to the CARS (< 0.001). Also, using the FDI criteria restorations were 2.7 times more related to caries around restorations (p < 0.001) compared to the other criterion.

Conclusions

The visual criteria used on the restoration's assessment directly influences the treatment decision to intervene or not on the restoration. The use of a minimally invasive based approach for assessing secondary caries may prevent overtreatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02112-6.

Effects of Plant Extracts on Dentin Bonding Strength: A Systematic Review and Meta-Analysis

Objective: To systematically review in vitro studies that evaluated the effects of plant extracts on dentin bonding strength.

Materials and Methods: Six electronic databases (PubMed, Embase, VIP, CNKI, Wanfang and The Cochrane Library) were searched from inception to September 2021 in accordance with the Preferred Reporting Items for Systematic Reviews (PRISMA). In vitro studies that compared the performance of dental adhesives with and without the plant extracts participation were included. The reference lists of the included studies were manually searched. Two researchers carried out study screening, data extraction and risk of bias assessment, independently and in duplicate. Meta-analysis was conducted using Review Manager 5.3.

Results: A total of 62 studies were selected for full-text analysis. 25 articles used the plant extracts as primers, while five added the plant extracts into adhesives. The meta-analysis included 14 articles of in vitro studies investigating the effects of different plant extract primers on dentin bonding strength of etch-and-rinse and self-etch adhesives, respectively. The global analysis showed statistically significant difference between dental adhesives with and without plant extract primers. It showed that the immediate bond strength of dental adhesives was improved with the application of plant extract primers.

Conclusion: The application of proanthocyanidin (PA) primers have positive effect on the in vitro immediate bonding strength of dental adhesives irrespective of etch-and-rinse or self-etch modes.

Effect of Accelerated Aging on Some Mechanical Properties and Wear of Different Commercial Dental Resin Composites

The aim of current in vitro research was to determine the effect of hydrothermal accelerated aging on the mechanical properties and wear of different commercial dental resin composites (RCs). In addition, the effect of expiration date of the composite prior its use was also evaluated. Five commercially available RCs were studied: Conventional RCs (Filtek Supreme XTE, G-aenial Posterior, Denfil, and >3y expired Supreme XTE), bulk-fill RC (Filtek Bulk Fill), and short fiber-reinforced RC (everX Posterior). Three-point flexural test was used for determination of ultimate flexural strength (n = 8). A vickers indenter was used for testing surface microhardness. A wear test was conducted with 15,000 chewing cycles using a dual-axis chewing simulator. Wear pattern was analyzed by a three-dimensional (3D) noncontact optical profilometer. Degree of C=C bond conversion of monomers was determined by FTIR-spectrometry. The specimens were either dry stored for 48 h (37 °C) or boiled (100 °C) for 16 h before testing. Scanning electron microscopy (SEM) was used to evaluate the microstructure of each material. Data were analyzed using ANOVA (p = 0.05). Hydrothermal aging had no significant effects on the surface wear and microhardness of tested RCs (p > 0.05). While flexural strength significantly decreased after aging (p < 0.05), except for G-aenial Posterior, which showed no differences. The lowest average wear depth was found for Filtek Bulk Fill (29 µm) (p < 0.05), while everX Posterior and Denfil showed the highest wear depth values (40, 39 µm) in both conditions. Passing the expiration date for 40 months did not affect the flexural strength and wear of tested RC. SEM demonstrated a significant number of small pits on Denfil’s surface after aging. It was concluded that the effect of accelerated aging may have caused certain weakening of the RC of some brands, whereas no effect was found with one brand of RC. Thus, the accelerated aging appeared to be more dependent on material and tested material property.

Effects of different surface treatments and adhesive self-etch functional monomers on the repair of bulk fill composites: A randomised controlled study

OBJECTIVE

To evaluate the effect of different adhesive protocols on the microtensile bond strength (μTBS) and integrity of the repaired bulk fill composite interface.

METHODS

Two hundred and seventy composite blocks made of bulk fill composites of different viscosity were randomly assigned to 18 surface conditioning groups (n = 15/group). The universal adhesive systems used were Heliobond™, Tokuyama bond force II™ and Scotchbond Universal™. A nanohybrid resin composite was applied as the repair material. Negative and positive control groups were included. Stick shape specimens of each group were subjected to μTBS testing. Representative samples from all test groups were subjected to microscopic, profilometric and SEM examination to determine their mode of failure. The data were analysed statistically using two-way ANOVA test, Tukey's test and the independent t-test (α = 0.05).

RESULTS

The mean μTBS of all test groups ranged between 28.5 and 46.8 MPa and varied with the type of adhesive system employed. Significantly highest μTBS values were obtained when Tokuyama bond force II™ and Scotchbond Universal™ adhesives were used (p < 0.01) which were comparable to the coherent strength of the bulk fill resin composite in the positive control groups (p > 0.05). The viscosity of the bulk fill composite did not significantly influence repair bond strength. The microscopy and SEM examination of the failed interfaces revealed a mixture of adhesive and cohesive failures.

CONCLUSIONS

Under the tested conditions, significantly greater μTBS of repaired bulk fill composite was achieved when the substrate surface was treated with adhesive systems containing a functional monomer.

CLINICAL SIGNIFICANCE

Eff ;ecting a repair of a bulk fill resin composite restoration with the application of a functional monomer containing adhesive system, such as Tokuyama Bond Force II™ or Scotchbond Universal™, would seem to enhance the interfacial bond strength and integrity of the repaired resin composite interface.

Development and characterization of self-etching adhesives doped with 45S5 and niobophosphate bioactive glasses: Physicochemical, mechanical, bioactivity and interface properties

OBJECTIVE

The aim of study was to develop and characterize experimental bioactive glasses (45S5 and niobophosphate bioactive glass (NbG)) and evaluate the effects of their addition in self-etching adhesive systems on physicochemical, mechanical, and bioactive properties, microtensile bond strength (μTBS), and nanoleakage (NL).

METHODS

Two-step self-etching adhesive systems containing 5, 10, and 20 wt.% of 45S5 and NbG bioactive glasses were developed. An experimental adhesive without microparticles and a commercial adhesive (Clearfil SE Bond) were used as control groups. The materials were evaluated for their degree of conversion (DC%), ultimate tensile strength (UTS), softening in solvent, radiopacity, sorption and solubility, alkalizing activity (pH), ionic release, and bioactivity. μTBS and NL were evaluated after 24 h and 1 year of storage. The data were subjected to analysis of variance and post-Holm-Sidak tests (α = 0.05).

RESULTS

The addition of the two bioactive glasses did not change the values of the degree of conversion, ultimate tensile strength, and softening in solvent. The adhesive system containing 20% NbG showed the highest radiopacity. The incorporation of 45S5 increased water sorption and solubility, raised the pH, and allowed the release of large amounts of calcium. After 28 days of immersion in simulated body fluid, the 45S5 adhesive precipitated hydroxyapatite and calcium carbonate (SEM/EDX, ATR/FTIR, and XDR). The addition of 45S5 and NbG to the adhesives improved the stability of the resin-dentin interface after 1 year.

SIGNIFICANCE

The incorporation of microparticles from 45S5 bioactive glass in self-etching adhesive systems is considered an excellent alternative for the development of a bioactive adhesive that improves the integrity of the hybrid layer on sound dentin.

Surface roughness, plaque accumulation, and cytotoxicity of provisional restorative materials fabricated by different methods

Fabricating method may affect the surface properties and biological characteristics of provisional restorations. This study aimed to evaluate the surface roughness, plaque accumulation, and cytotoxicity of provisional restorative materials fabricated by the conventional, digital subtractive and additive methods. Sixty-six bar-shaped specimens (2×4×10 mm) were fabricated by using provisional restorative materials through the conventional, digital subtractive and additive methods (n = 22 per group). Ten specimens of each group were used for surface roughness and plaque accumulation tests, 10 specimens for cytotoxicity assay, and 2 specimens of each group were used for qualitative assessment by scanning electron microscopy. The Ra (roughness average) and Rz (roughness height) values (μm) were measured via profilometer, and visual inspection was performed through scanning electron microscopy. Plaque accumulation of Streptococcus mutans and cytotoxicity on human gingival fibroblast-like cells were evaluated. The data were analyzed with one-way ANOVA and Tukey's post hoc test (α = 0.05). Surface roughness, biofilm accumulation and cytotoxicity were significantly different among the groups (P<0.05). Surface roughness was significantly higher in the conventional group (P<0.05); however, the two other groups were not significantly different (P>0.05). Significantly higher bacterial attachment was observed in the additive group than the subtractive (P<0.001) and conventional group (P = 0.025); while, the conventional and subtractive groups were statistically similar (P = 0.111). Regarding the cytotoxicity, the additive group had significantly higher cell viability than the subtractive group (P = 0.006); yet, the conventional group was not significantly different from the additive (P = 0.354) and subtractive group (P = 0.101). Surface roughness was the highest in conventionally cured group; but, the additive group had the most plaque accumulation and lowest cytotoxicity.

Novel CaF2 Nanocomposites with Antibacterial Function and Fluoride and Calcium Ion Release to Inhibit Oral Biofilm and Protect Teeth

(1) Background: The objective of this study was to develop a novel dental nanocomposite containing dimethylaminohexadecyl methacrylate (DMAHDM), 2-methacryloyloxyethyl phosphorylcholine (MPC), and nanoparticles of calcium fluoride (nCaF₂) for preventing recurrent caries via antibacterial, protein repellent and fluoride releasing capabilities. (2) Methods: Composites were made by adding 3% MPC, 3% DMAHDM and 15% nCaF₂ into bisphenol A glycidyl dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) (denoted BT). Calcium and fluoride ion releases were evaluated. Biofilms of human saliva were assessed. (3) Results: nCaF₂+DMAHDM+MPC composite had the lowest biofilm colony forming units (CFU) and the greatest ion release; however, its mechanical properties were lower than commercial control composite (p < 0.05). nCaF₂+DMAHDM composite had similarly potent biofilm reduction, with mechanical properties matching commercial control composite (p > 0.05). Fluoride and calcium ion releases from nCaF₂+DMAHDM were much more than commercial composite. Biofilm CFU on composite was reduced by 4 logs (n = 9, p < 0.05). Biofilm metabolic activity and lactic acid were also substantially reduced by nCaF₂+DMAHDM, compared to commercial control composite (p < 0.05). (4) Conclusions: The novel nanocomposite nCaF₂+DMAHDM achieved strong antibacterial and ion release capabilities, without compromising the mechanical properties. This bioactive nanocomposite is promising to reduce biofilm acid production, inhibit recurrent caries, and increase restoration longevity.

Novel antibacterial calcium phosphate nanocomposite with long-term ion recharge and re-release to inhibit caries

Short-term studies on calcium-phosphate (CaP) ion-rechargeable composites were reported. The long-term rechargeability is important but unknown. The objectives of this study were to investigate nanocomposite with strong antibacterial and ion-recharge capabilities containing dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and evaluate long-term ion-recharge by testing for 12 cycles (taking 6 months to complete) for the first time. Three groups were tested: (1) Heliomolar control; (2) Resin+20%NACP+50%glass; (3) Resin+3%DMAHDM+20%NACP+50%glass. Biofilm acid and colony-forming units (CFU) were measured. Ion-recharge was tested for 12 cycles. NACP-DMAHDM composite reduced biofilm acid, and reduced CFU by 4 logs. High levels of ion releases were maintained throughout 12 cycles of recharge, maintaining steady-state releases without reduction in 6 months (p>0.1), representing long-term remineralization potential. Bioactive nanocomposite demonstrated long-term ion-rechargeability for the first time, showed remineralization and potent anti-biofilm functions, with promise for tooth restorations to combat caries.

Synthesis of antibacterial dimethacrylate derived from niacin and its application in preparing antibacterial dental resin system

In this research, a bio-based monomer 1,3-bis(methacryloyloxy)propyl-carbonyl- hexylpyridinium bromide (QANMA) that derived from niacin was synthesized and incorporated into Bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (50 wt/50 wt) with a series of mass fraction as antibacterial agent. The double bond conversion (DC), volumetric shrinkage (VS), mechanical properties, water sorption (WS) and solubility (SL) were investigated among groups with different QANMA concentrations. Antibacterial activity against S. mutans were conducted by bacteria colony counting and bacteria LIVE/DEAD staining. The results showed that QANMA had no influence on DC of dental resin (p > 0.05), but would lead to lower volumetric shrinkage (p < 0.05). Only dental resin with 10 wt% and 20 wt% of QANMA showed obviously antibacterial activity. Mechanical properties, WS and SL of dental resin could be impaired by incorporation QANMA, flexural strength and modulus were decreased with the increasing of QANMA concentration (p < 0.05), while WS and SL were increased with the increasing of QANMA concentration (p < 0.05). Dental resin with 10 wt% of QANMA seemed to be the optimal resin system in this research, for it showed significant antibacterial activity and its flexural strength was still met the requirement of ISO standard. This work suggested that bio-based monomer QANMA could be used as antibacterial agent in dental materials, but further optimization experiment and biocompatibility evaluation should be taken in future.

Fluorescence-aided selective removal of resin-based composite restorative materials: An in vitro comparative study

AIM

During removal of resin-based composite (RBC) restorations, removal of adjacent sound tooth structure can easily occur. The aim of the study was to compare the fluorescence-aided identification of restorations (FAIR) method with the conventional method (CM) using white light illumination for the selective removal of tooth-colored RBC restorations.

MATERIALS AND METHODS

Sixty extracted teeth were used to prepare 15 sets of models, each with four teeth. Cavities were prepared in each tooth and a digital three-dimensional scan of each model was taken in STL format. The teeth were then restored with either Admira Fusion, GRADIA DIRECT X, or TPH Spectra LV (20 teeth for each). Five dentists removed the restorations from sets of 12 teeth (six each using FAIR, and six using CM). From a postoperative scan, changes in intercuspal cavity width were measured using the 3D tool CAD software.

RESULTS

Using FAIR, changes in cavity width were not significant (P = .17), and there was no significant interoperator variance (P = .3). In contrast, when using CM, there was a significant increase in cavity width (P = .0025), and considerable interoperator variance (P = .03). FAIR allowed faster completion of the task of restoration removal (average time 100.23 seconds, vs 165.13 seconds from CM).

CONCLUSION

The FAIR method facilitates the selective removal of tooth-colored RBC restorations, with reduced time and less inadvertent removal of sound tooth structure.

CLINICAL SIGNIFICANCE

By enhancing the differentiation between the restorative material and adjacent tooth structure, the FAIR method facilitates removal of tooth-colored restorations, while concurrently prevents unnecessary removal of healthy tooth structure. The same approach may have applications for removal of resin-based materials such as resin cements under restorations, resin fissure sealants, and orthodontic brackets bonding resins.

Adhesive Systems Used in Indirect Restorations Cementation: Review of the Literature

New technologies are changing the therapeutical options to do indirect restorations and new adhesive systems are continuously introduced to be used by clinicians. Different interactions between restorations, adhesive systems components, enamel and dentin require having criteria based on the selection of the adhesive system, ensuring the longevity of the restorations and the preservation of the biological remnant. The adhesion force to the dental tissue is one of the indicatives of the behavior of the adhesive systems and influences the behavior of the treatments with direct and indirect restorations. The objective of this search was to find the adhesive systems with the best results in terms of the adhesion strength of indirect restorations on the dental tissues. The search was conducted in two MEDLINE digital databases (PubMed), and the Cochrane Library with a search strategy based on the combination of MeSH (Medical Subject Headings) keywords. This systematic review used the PRISMA guide (Preferred Reporting Items for Systematic Reviews and Meta-Analysis). According to this review, the 3-step adhesive systems were the best performing and still are the gold standard for the cementing of indirect restorations. In addition, it can be concluded that self-etched adhesive systems reduce the time spent in clinical practice, however at the interface level they behave as permeable membranes more susceptible to degradation.

An improved dental composite with potent antibacterial function

A new BisGMA-based antibacterial dental composite has been formulated and evaluated. Compressive strength and bacterial viability were utilized to evaluate the formed composites. It was found that the new composite exhibited a significantly enhanced antibacterial function along with improved mechanical and physical properties. The bromine-containing derivative-modified composite was more potent in antibacterial activity than the chlorine-containing composite. The modified composites also exhibited an increase of 30-53% in compressive yield strength, 15-30% in compressive modulus, 15-33% in diametral tensile strength and 6-20% in flexural strength, and a decrease of 57-76% in bacterial viability, 23-37% in water sorption, 8-15% in shrinkage, 8-13% in compressive strength, and similar degree of conversion, than unmodified composite. It appears that this experimental composite may possibly be introduced to dental clinics as an attractive dental restorative due to its improved properties as well as enhanced antibacterial function.

A randomised controlled study on the effects of different surface treatments and adhesive self-etch functional monomers on the immediate repair bond strength and integrity of the repaired resin composite interface

OBJECTIVES

To evaluate the effects of different surface conditioning methods on the immediate repair bond strength and integrity of the repaired composite interface.

METHODS

One hundred and five resin composite blocks made of a nanohybrid resin composite were randomly assigned to one of the following surface conditioning groups (n = 15/group): Group 1: Gluma Self Etch™ adhesive system, Group 2: Tokuyama Bond Force II™ adhesive system, Group 3: non-roughened and non-conditioned surfaces, Group 4: sandblasting and Gluma Self Etch™, Group 5: sandblasting and Tokuyama Bond Force II™, Group 6: sandblasting only. A positive control group was also used. Resin composite identical to the substrate was applied and the repaired specimens were subjected to shear bond strength (SBS) testing. Representative samples from all groups were subjected to scanning electron microscopy and surface profilometry to determine their mode of failure. The data were analysed statistically using Analysis of Variance (ANOVA) and two independent sample t-test (α = 0.05).

RESULTS

The mean SBS of all test groups ranged between 1.92 and 5.40 MPa and varied with the degree of composite surface roughness and the type of adhesive system employed. Significantly highest SBS values (5.40 ± 0.36 MPa) were obtained in Group 5 (p = 0.017) which were comparable to the coherent strength of the resin composite in the positive control group (p > 0.05).

CONCLUSIONS

Under the tested conditions, significantly greater SBS of repaired resin composite was achieved when the substrate surface was conditioned by sandblasting followed by the application of the Tokuyama Bond Force II™ adhesive system.

CLINICAL SIGNIFICANCE

Effecting a repair of a nanohybrid composite restoration with sandblasting and the application of TBF II would seem to enhance the interfacial bond strength and integrity of the repaired resin composite interface. Clinical trials are necessary to determine the usefulness of this technique.

Restoration Repair as a Contemporary Approach to Tooth Preservation: Criteria for Decision Making and Clinical Recommendations

Despite the growing body of evidence-based knowledge, evidence-based restoration repair is not always applied in the clinical setting. This article is intended to give an evidence-based insight into the indications, importance, benefits and long-term success of resin composite restoration repair, together with details of relevant operative techniques aimed at conserving as much sound tooth structure as possible.

Dental remineralization via poly(amido amine) and restorative materials containing calcium phosphate nanoparticles

Tooth decay is prevalent, and secondary caries causes restoration failures, both of which are related to demineralization. There is an urgent need to develop new therapeutic materials with remineralization functions. This article represents the first review on the cutting edge research of poly(amido amine) (PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP). PAMAM was excellent nucleation template, and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization. NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities. PAMAM+NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates, superior acid-neutralization, and ions release. Therefore, the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone. PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions. Besides, the long-term remineralization capability of PAMAM+NACP was established. After prolonged fluid challenge, the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration. Furthermore, the hardness of pre-demineralized dentin was increased back to that of healthy dentin, indicating a complete remineralization. Therefore, the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization, hardness increase, and caries-inhibition capabilities.

Hydrophobic and antimicrobial dentin: A peptide-based 2-tier protective system for dental resin composite restorations

Dental caries, i.e., tooth decay mediated by bacterial activity, is the most widespread chronic disease worldwide. Carious lesions are commonly treated using dental resin composite restorations. However, resin composite restorations are prone to recurrent caries, i.e., reinfection of the surrounding dental hard tissues. Recurrent caries is mainly a consequence of waterborne and/or biofilm-mediated degradation of the tooth-restoration interface through hydrolytic, acidic and/or enzymatic challenges. Here we use amphipathic antimicrobial peptides to directly coat dentin to provide resin composite restorations with a 2-tier protective system, simultaneously exploiting the physicochemical and biological properties of these peptides. Our peptide coatings modulate dentin's hydrophobicity, impermeabilize it, and are active against multispecies biofilms derived from caries-active individuals. Therefore, the coatings hinder water penetration along the otherwise vulnerable dentin/restoration interface, even after in vitro aging, and increase its resistance against degradation by water, acids, and saliva. Moreover, they do not weaken the resin composite restorations mechanically. The peptide-coated highly-hydrophobic dentin is expected to notably improve the service life of resin composite restorations and to enable the development of entirely hydrophobic restorative systems. The peptide coatings were also antimicrobial and thus, they provide a second tier of protection preventing re-infection of tissues in contact with restorations. STATEMENT OF SIGNIFICANCE: We present a technology using designer peptides to treat the most prevalent chronic disease worldwide; dental caries. Specifically, we used antimicrobial amphipathic peptides to coat dentin with the goal of increasing the service life of the restorative materials used to treat dental caries, which is nowadays 5 years on average. Water and waterborne agents (enzymes, acids) degrade restorative materials and enable re-infection at the dentin/restoration interface. Our peptide coatings will hinder degradation of the restoration as they produced highly hydrophobic and antimicrobial dentin/material interfaces. We anticipate a high technological and economic impact of our technology as it can notably reduce the lifelong dental bill of patients worldwide. Our findings can enable the development of restorations with all-hydrophobic and so, more protective components.

In Vitro Caries Models for the Assessment of Novel Restorative Materials

Due to the high failure rates of traditional dental restorations, there is an ongoing effort to develop modified and new restorative biomaterials in dentistry. Being the most commonly used restorative material, most of these efforts primarily aim to improve dental composite. Generally, the main objective of such modifications is to enhance the restorative physical and antimicrobial properties in order to limit micro-leakage and inhibit bacterial biofilm cultivation. Herein, we describe the process of designing a simple in vitro model to assess the physical and antimicrobial properties of novel restorative materials in addition to evaluating their effect on the fragile balance between enamel de- and remineralization.

Chlorhexidine-encapsulated mesoporous silica-modified dentin adhesive

OBJECTIVES

This work aims to explore the feasibility of chlorhexidine-encapsulated mesoporous silica (CHX@pMSN) as a modifier of a commercial dental adhesive via the evaluation of physicochemical properties and antibacterial capabilities of adhesive-dentin interface.

METHODS

Therapeutic adhesives were developed in the present study by incorporating CHX@pMSN into a commercial adhesive at four mass fractions (0, 1, 5 and 10 wt.%). The antibacterial capability on Streptococcus mutans (S. mutans) biofilm, conversion degree, adhesive morphology, microtensile bond strength (MTBS) and nanoleakage expression were evaluated comprehensively.

RESULTS

MTT and CLSM evaluation showed that CHX@pMSN-doped adhesive inhibits S. mutans biofilm growth, while CHX is released from the modified adhesive continuously. The incorporation of CHX@pMSN did not affect immediate bond strength at the concentration of 1% and 5% (P >  0.05). Moreover, these bonds were mainly preserved in 5% CHX@pMSN group after one month of collagenase ageing. Meanwhile, CHX@pMSN-doped adhesive groups exhibited similar nanoleakage distribution compared with the control.

CONCLUSION

This study showed that the 5% CHX@pMSN-modified adhesive achieved balance amongst unaffected immediate bonding strength, well-preserved bonds against collagenase ageing and effective inhibition of S. mutans biofilm growth.

CLINICAL SIGNIFICANCE

CHX@pMSN-modified dentin adhesive can potentially extend the service life of adhesive restoration in clinic.

Recent advances in understanding the fatigue and wear behavior of dental composites and ceramics

Dental composite and ceramic restorative materials are designed to closely mimic the aesthetics and function of natural tooth tissue, and their longevity in the oral environment depends to a large degree on their fatigue and wear properties. The purpose of this review is to highlight some recent advances in our understanding of fatigue and wear mechanisms, and how they contribute to restoration failures in the complex oral environment. Overall, fatigue and wear processes are found to be closely related, with wear of dental ceramic occlusal surfaces providing initiation sites for fatigue failures, and subsurface fatigue crack propagation driving key wear mechanisms for composites, ceramics, and enamel. Furthermore, both fatigue and wear of composite restorations may be important in enabling secondary caries formation, which is the leading cause of composite restoration failures. Overall, developing a mechanistic description of fatigue, wear, and secondary caries formation, along with understanding the interconnectivity of all three processes, are together seen as essential keys to successfully using in vitro studies to predict in vivo outcomes and develop improved dental restorative materials.

Bioactive Dental Composites and Bonding Agents Having Remineralizing and Antibacterial Characteristics

Current dental restorative materials are typically inert and replace missing tooth structures. This article reviews efforts in the development of a new generation of bioactive materials designed to not only replace the missing tooth volume but also possess therapeutic functions. Composites and bonding agents with remineralizing and antibacterial characteristics have shown promise in replacing lost minerals, inhibiting recurrent caries, neutralizing acids, repelling proteins, and suppressing biofilms and acid production. Furthermore, they have demonstrated a low cytotoxicity similar to current resins, with additional benefits to protect the dental pulp and promote tertiary dentin formation. This new class of bioactive materials shows promise in reversing lesions and inhibiting caries.

Microtensile bond strength of resin cement primer containing nanoparticles of silver (NAg) and amorphous calcium phosphate (NACP) to human dentin

PURPOSE

The purpose of the current study was to evaluate the effect of incorporating nanoparticles of silver (NAg) and amorphous calcium phosphate (NACP) into a self-etching primer of a resin cement on the microtensile bond strength of dentin, regarding the proven antibacterial feature of NAg and remineralizing effect of NACP.

MATERIALS AND METHODS

Flat, mid-coronal dentin from 20 intact extracted human third molars were prepared for cementation using Panavia F2.0 cement. The teeth were randomly divided into the four test groups (n=5) according to the experimental cement primer composition: cement primer without change (control group), primer with 1% (wt) of NACP, primer with 1% (wt) of physical mixture of NACP+Nag, and primer with 1% (wt) of chemical mixture of NACP+Nag. The resin cement was used according to the manufacturer's instructions. After storage in distilled water at 37℃ for 24 h, the bonded samples were sectioned longitudinally to produce 1.0 × 1.0 mm beams for micro-tensile bond strength testing in a universal testing machine. Failure modes at the dentin-resin interface were observed using a stereomicroscope. The data were analyzed by one-way ANOVA and Tukey's post-hoc tests and the level of significance was set at 0.05.

RESULTS

The lowest mean microtensile bond strength was obtained for the NACP group. Tukey's test showed that the bond strength of the control group was significantly higher than those of the other experimental groups, except for group 4 (chemical mixture of NACP and NAg; P=.67).

CONCLUSION

Novel chemical incorporation of NAg-NACP into the self-etching primer of resin cement does not compromise the dentin bond strength.

Nanostructured Polymeric Materials with Protein-Repellent and Anti-Caries Properties for Dental Applications

Dental caries is prevalent worldwide. Tooth cavity restorations cost more than $46 billion annually in the United States alone. The current generation of esthetic polymeric restorations have unsatisfactory failure rates. Replacing the failed restorations accounts for 50–70% of all the restorations. This article reviewed developments in producing a new generation of bioactive and therapeutic restorations. This includes: Protein-repellent and anti-caries polymeric dental composites, especially the use of 2-methacryloyloxyethyl phosphorylcholine (MPC) and dimethylaminododecyl methacrylate (DMAHDM); protein-repellent adhesives to greatly reduce biofilm acids; bioactive cements to inhibit tooth lesions; combining protein-repellency with antibacterial nanoparticles of silver; tooth surface coatings containing calcium phosphate nanoparticles for remineralization; therapeutic restorations to suppress periodontal pathogens; and long-term durability of bioactive and therapeutic dental polymers. MPC was chosen due to its strong ability to repel proteins. DMAHDM was selected because it had the most potent antibacterial activity when compared to a series of antibacterial monomers. The new generation of materials possessed potent antibacterial functions against cariogenic and periodontal pathogens, and reduced biofilm colony-forming units by up to 4 logs, provided calcium phosphate ions for remineralization and strengthening of tooth structures, and raised biofilm pH from a cariogenic pH 4.5 to a safe pH 6.5. The new materials achieved a long-term durability that was significantly beyond current commercial control materials. This new generation of bioactive and nanostructured polymers is promising for wide applications to provide therapeutic healing effects and greater longevity for dental restorations.

Improving the durability of resin-dentin bonds with an antibacterial monomer MDPB

The 12-methacryloxydodecylpyridium bromide (MDPB) has been reported to act as a matrix metalloprotease (MMP) inhibitor. In this study, the effects of application of MDPB on resin-dentin bonds were evaluated. The resin-dentin bonded specimens were prepared with a commercial MDPB-containing self-etching primer or a self-etching primer without MDPB, and stored 24 h or 1 year. Surfaces were pretreated with chlorhexidine or MDPB-containing cavity disinfectant. Additionally, we compared the degradation patterns between the two self-etching adhesives and etch and rinse system. Water tree formations were observed as the typical morphological phase of the two tested self-etching adhesives for both 24 h and 1 year groups. The degradation phase of collagen network depletion was observed in the adhesive interface of the etch-and-rinse system in the 1 year group. Pretreatment with chlorhexidine did not prevent bond strength reduction after 1 year. The cavity disinfectant improved the bond durability for the self-etching adhesive.

Antibacterial quaternary ammonium compounds in dental materials: A systematic review

OBJECTIVE

Quaternary ammonium compounds (QACs) represent one of the most effective classes of disinfectant agents in dental materials and resin nanocomposites. This reviews aims to give a wide overview on the research in the field of antibacterial QACs in dental materials and nanocomposites.

METHOD

An introduction to dental materials components as well as the microorganisms and methods of evaluation for the antimicrobial assays are presented. Then, the properties and synthesis route of QACs, as monomer and filler, are shown. Finally, antimicrobial monomers and fillers, specifically those contain quaternary ammonium salts (QASs), in dental materials are reviewed.

RESULTS

QACs have been used as monomer and micro/nanofiller in restorative dentistry. They possess one or more methacrylate functional groups to participate in polymerization reactions. QACs with multiple methacrylate groups can also be used as crosslinking agents. Furthermore, QACs with chain length from ∼12 to 16 have higher antimicrobial activity in cured dental resins. In general, increasing the chain length leads to a threshold value (critical point) and then it causes decrease in the antimicrobial activity.

SIGNIFICANCE

The current state of the art of dental materials and resin nanocomposites includes a wide variety of antimicrobial materials. Among them, QACs presents low cytotoxicity and excellent long-term antimicrobial activity without leaching out over time.

Esthetic restorative materials and glass ionomer cements: Influence of acidic drink exposure on bacterial adhesion

OBJECTIVE

The purpose of this research was to evaluate and compare bacterial adhesion on five esthetic restorative materials, three glass ionomer cements (GIC), and two GIC with coat. All the materials were considered after acidic drink exposure.

MATERIALS AND METHODS

Thirty cylindrical sample of each of the 10 materials were prepared and then divided into three groups: group 1 (baseline), Group 2 (1 day in acidic soft drink), and Group 3 (7 days in acidic soft drink). Bacterial suspension of Streptococcus mutans was cultured and deposited onto each material, and the adhesion was evaluated through the colony-forming units determination. One-way ANOVA and Bonferroni's post hoc tests were applied to estimate significant differences between the esthetic materials.

RESULTS

The highest amount of S. mutans was recorded in Group 3 and the lowest in Group 1 (baseline). In general, the GIC showed bacterial adhesion values higher than the ones related to composites both in Group 2 than in Group 3. Acidic soft drinks lead a time-dependent degradation of restorative materials causing an increase of the surface rugosity. In fact, a general increase in S. mutans cells adhesion to treated samples was observed.

CONCLUSIONS

The use of acidic soft drink resulted in a degradation of the surface layer of the restorative material with consequent increase of bacterial adhesion. The GIC can be considered a more friendly environment for bacterial adhesion. This is true in particular if acid substances have already deteriorated the surface.

Novel rechargeable calcium phosphate nanocomposite with antibacterial activity to suppress biofilm acids and dental caries

OBJECTIVE

Rechargeable calcium phosphate (CaP) composites were developed recently. However, none of the rechargeable CaP composites was antibacterial. The objectives of this study were to develop the first rechargeable CaP composite that was antibacterial, and to investigate the effects of adding dimethylaminohexadecyl methacrylate (DMAHDM) into rechargeable CaP composite on ion rechargeability and re-release as well as biofilm properties.

METHODS

DMAHDM was synthesized via a Menschutkin reaction. Nanoparticles of amorphous calcium phosphate (NACP) were synthesized using a spray-drying technique. The resin contained ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). Two composites were fabricated: rechargeable NACP composite, and rechargeable NACP-DMAHDM composite. Mechanical properties and ion release and recharge were measured. A dental plaque microcosm biofilm model using saliva was tested.

RESULTS

Flexural strength and elastic modulus of rechargeable NACP and NACP-DMAHDM composites matched commercial control composite (p > 0.1). NACP-DMAHDM inhibited biofilm metabolic activity and lactic acid, and reduced biofilm colony-forming units (CFU) by 3-4 log. NACP and NACP-DMAHDM showed similar Ca and P ion recharge and re-release (p > 0.1). Therefore, adding DMAHDM did not compromise the ion rechargeability. One recharge yielded continuous release for 42 d. The release was maintained at the same level with increasing number of recharge cycles, indicating long-term ion release and remineralization capability.

CONCLUSIONS

The first CaP rechargeable and antibacterial composite was developed. Adding DMAHDM into the rechargeable NACP composite did not adversely affect the Ca and P ion release and recharge, and the composite had much less biofilm growth and lactic acid production, with CFU reduction by 3-4 log.

CLINICAL SIGNIFICANCE

This novel CaP rechargeable composite with long-term remineralization and antibacterial properties is promising for tooth restorations to inhibit caries.

Can clusters based on caries experience and medical status explain the distribution of overhanging dental restorations and recurrent caries? A cross-sectional study in Madinah - Saudi Arabia

BACKGROUND

Overhanging dental restorations (ODRs) and secondary caries lesions (SCLs) are of high prevalence and jeopardize the fate of the restoration.

OBJECTIVES

To assess the relationship between ODRs, SCLs and certain caries contributory factors.

METHODS

A total of 502 radiographic records of dental patients with proximal fillings (mean age 38 ± 13 years, 50% females) were screened for ODRs and SCLs. Descriptive and inferential statistics were used. In addition, two-step cluster analysis was performed in an attempt to explain trends in ODR and SCL distribution. A p value of ≤ 0.05 was considered statistically significant.

RESULTS

More than 30% of the individuals had ODRs and SCLs. No differences between genders were observed (p > 0.05). Individuals with medical conditions had more ODRs than those without (49% vs. 34%, p ≤ 0.05), while those with high caries experience had more SCLs (49%, p ≤ 0.05). The cluster analysis grouped the participants in five clusters, with the cluster involving individuals with no medical conditions and low caries experience demonstrating the lowest prevalence of ODRs and SCLs.

CONCLUSIONS

Within the study limits, more than one third of the sample of dental patients had ODRs and SCLs. The medical condition was associated with ODRs, while the past caries experience was associated with SCLs.

Clinical and Radiographic Assessment of Reasons for Replacement of Metal- Ceramic Fixed Dental Prostheses in Patients Referring to Dental School

Background

The expected length of service and reasons for fixed dental prostheses (FDPs) replacement are a frequent inquiry by patients while the answers were mainly based on studies reports that was conducted outside the middle east region. This clinical and radiographic survey was constructed to assess and survey clinically and radiographically the reasons of replacement of metal-ceramic fixed dental prostheses, amongst patients reporting at dental school in Taibah University.

Material and Methods

Between January and May 2016, 151 patients were recruited for this study. Interview (include questions pertained to the length of service of the prosthesis, the nature of complaint as told by patient in her own words), clinical examination, intra-oral photographs, and periapical radiographs, were done by the researchers. The parameters assessed were secondary caries, open margins, loss of retention, failure of endodontic treatment of the abutment and periodontal diseases.

Results

A total number of 249 failed fixed dental prostheses were evaluated. Of which 180 (39.7%) were single crowns, 159 (35.0%) were retainers and 117 (25.8%) were pontics in 69 fixed partial denture. The most common reason for replacement of fixed restorations was periodontal diseases affecting 92.8% of all types’ restorations, followed by defective margin in 90.4% of examined restoration, poor aesthetic in 88% of restorations, while periapical involvement was found in 85.5% of fixed dental prosthesis. The survival rates of fixed prostheses were not predictable, and no association was found between number of years in service and the number of restorations.

Conclusions

The most common reasons for replacing single unit fixed dental prostheses are periodontal diseases and periapical involvement, while defective margins and poor aesthetic mainly associated with multi-unit fixed dental prostheses.

Key words:Failure, Fixed dental prosthesis, Survival, Replacement.

Ca-Doped mesoporous SiO2/dental resin composites with enhanced mechanical properties, bioactivity and antibacterial properties

MCS containing resin composites possess enhanced mechanical properties and antibacterial activity, and can smartly induce the deposition of apatite minerals.