Restoration of noncarious tooth defects by dentists in The Dental Practice-Based Research Network

Evaluating fatigue resistance in occlusal veneers: a comparative study of processing techniques and material thickness of lithium disilicate (IPS e.max Press vs. IPS e.max CAD)

BACKGROUND

Lithium disilicate occlusal veneers are popular for minimally invasive posterior teeth restoration. The aim of this study was to compare the fatigue resistance and crack pattern of lithium disilicate occlusal veneers fabricated using pressing and milling techniques with varying thicknesses.

METHODS

Sixty lithium disilicate discs, representing occlusal veneers, were divided into four groups (n = 15) based on processing technique (IPS e.max Press or IPS e.max CAD) and thickness (0.5 or 0.8 mm). A step-stress fatigue test was applied with axial loading, consisting of 10,000 cycles/step with a step size of 50 N until failure. Fractographic analysis was performed using SEM. Statistical analysis was performed using the Kaplan-Meier test, Mantel-Cox test, and Weibull analysis.

RESULTS

Both processing techniques resulted in similar fatigue resistances at 0.5 mm and 0.8 mm thicknesses. However, the 0.8 mm lithium disilicate restorations showed a significantly higher survival rate than the 0.5 mm lithium disilicate restorations (log-rank tests, χ2 = 58.6; df = 3; P < 0.001). Fractographic analysis revealed radial cracks originating from defects on the ceramic surface at the cementing interface, extending towards the occlusal surface.

CONCLUSIONS

At 0.5 mm or 0.8 mm material thickness, the processing technique did not affect the fatigue resistance or crack patterns of the lithium disilicate occlusal veneers. However, the lithium disilicate with a thickness of 0.8 mm exhibited a superior survival probability compared to that with a thickness of 0.5 mm.

Effect of preparation design on fracture resistance of molars restored with occlusal veneers of different CAD-CAM materials: an in vitro study

BACKGROUND

Occlusal veneer had been evaluated for mechanical properties using lithium disillicate. However, studies evaluating the mechanical properties of occlusal veneer with different preparation designs and ceramic materials are lacking. So, this in vitro study aimed to evaluate the fracture resistance of occlusal veneers with two designs fabricated from two different ceramic materials.

MATERIAL AND METHODS

Fourty mandibular third molars were distributed to 2 groups (n = 20) according to preparation design: group (O) anatomical occlusal reduction and group (OA) anatomical occlusal and 1 mm axial reduction. Each group was additionally subdivided into two subgroups (n = 10) according to ceramic materials; in subgroup X, lithium disilicate (e.max CAD, Ivoclar AG, Schaan, Liechtenstein) was used, and in subgroup S, zirconia-reinforced lithium silicate (ZLS) (Vita Suprinity, VitaZahnfabrik, Bad Säckingen, Germany) was used. All specimens were cemented with a light-cure resin cement (Choice 2, Bisco, Schaumburg, USA). 5000 thermocycles were applied to all specimens with both temperatures of 5 °C and 55 °C in two water baths; the dwell time was 30s at each bath, and the transfer time was 10s. Then all specimens were subjected to a fatigue simulation under dynamic loading of 200 N for 250,000 cycles. A universal testing machine (5500R/1123, Instron, Norwood, USA) was used to evaluate the fracture strength with a crosshead speed of 1 mm/min. All data were analyzed statistically by using a two-way ANOVA, and for some violations of assumptions, these results were compared with those obtained by the nonparametric test (Scheirer Ray Hare) (α = 0.05).

RESULTS

A statistically significantly higher fracture resistance in the 'OA' (3389 N) compared to the 'O' (2787 N) group regardless of the ceramic material (P < .001) and a statistically significantly higher fracture resistance in the 'X' (3295 N) compared to the 'S' (2881 N) regardless of the preparation design (P = .015).

CONCLUSIONS

For occlusal veneers, all preparation designs and materials (such as Vita Suprinity and e.max CAD) had clinically acceptable fracture resistance values that were greater than the maximal biting forces. On the other hand, the e.max CAD with occlusal veneer, including axial reduction design, demonstrated the maximum fracture resistance value. Finally, no relationship between fracture strength and mode of failure was found.

Marginal adaptation and fracture resistance of virgilite-based occlusal veneers with varying thickness

STATEMENT OF PROBLEM

CAD/CAM occlusal veneers have been developed for minimally invasive prosthetic restoration of eroded teeth. Marginal adaptation and fracture resistance are crucial for the long-term survivability and clinical success of such restorations. Virgilite-based lithium disilicate glass-ceramic is a newly introduced material with claims of high strength. However, constructing occlusal veneers from this material of varying thickness has not been investigated.

PURPOSE

The current study aimed to assess the impact of CAD/CAM occlusal veneer thickness and materials on marginal adaptation and fracture resistance.

MATERIALS AND METHODS

Thirty-two occlusal veneers were constructed and divided into two groups (n = 16) based on the CAD/CAM material into Brilliant Crios and CEREC Tessera. Each group was further subdivided into two subgroups (n = 8) according to the thickness: 0.6 and 0.9 mm. Occlusal veneers were bonded to epoxy resin dies. The marginal gap was evaluated before and after thermodynamic aging. Fracture resistance and failure mode were evaluated for the same samples after aging. Marginal adaptation was analyzed using the Mann-Whitney U test. Fracture resistance was analyzed using Weibull analysis (α = 0.05).

RESULTS

The marginal gap was significantly increased following thermodynamic aging for tested groups (P < 0.001). CEREC Tessera showed a significantly higher marginal gap than Brilliant Crios before and after aging for both thicknesses (P < 0.05). CEREC Tessera recorded lower significant fracture load values compared to Brilliant Crios (P < 0.05).

CONCLUSIONS

Both CEREC Tessera and Brilliant Crios demonstrated clinically accepted marginal gap values. All groups showed fracture resistance values higher than the average masticatory forces in the premolar region except for 0.6 mm CEREC Tessera.

CLINICAL IMPLICATIONS

Reinforced composite occlusal veneers demonstrated more favorable outcomes in terms of marginal gap and fracture resistance at both tested thicknesses compared to virgilite-based lithium disilicate glass-ceramic. Additionally, caution should be exercised during the construction of occlusal veneers from virgilite-based lithium disilicate glass-ceramic with reduced thickness.

Effect of preparation design on marginal adaptation and fracture strength of ceramic occlusal veneers: A systematic review

OBJECTIVES

This systematic review aims to investigate the effect of different preparation designs on the marginal fit and fracture strength of ceramic occlusal veneers.

MATERIALS AND METHODS

Based on the PICO question and the search terms, an electronic search was performed in Google Scholar, PubMed (MEDLINE), Scopus, Cochrane Library, Web of Science, Science Direct, Wiley, Ovid, and SAGE for articles published up to July 2022. After including English in vitro studies that evaluated posterior ceramic occlusal overlays at the posterior with ceramic restorations by following the PRISMA statement, the extracted data was tabulated. The methodological quality of the included studies was evaluated. Risk of bias assessment was done independently by two authors using the modified MINORS scale.

RESULTS

About 3138 search results were screened, of which 22 were selected due to their titles. Twenty-one full-text articles were assessed for eligibility. Seventeen in-vitro studies were finalized for the extraction of quantitative data. All 17 articles had a low risk of bias and were retained. The influencing items for evaluating the research were different in most studies; therefore, qualitative synthesis of the results was feasible. They generally included preparation design, material thickness, depth of preparation in the tooth, internal divergence angle, and finish line. Meta-analysis was not done due to heterogeneity of preparation types and evaluation methods. Results revealed that fracture resistance of occlusal veneers is higher than normal mastication force, and it is sufficient to prepare the occlusal surface, use a self-etching primer for bonding, and an acceptable minimum ceramic thickness. The marginal discrepancy of occlusal veneers is clinically acceptable. However, this systematic review faces some limitations due to the lack of in vivo studies, different preparation designs in included studies, different follow-ups, and lack of comprehensive explanations in articles.

CONCLUSIONS

The preparation design of occlusal veneers influences both marginal adaptation and fracture resistance. Various preparation designs are proven to have clinically acceptable fracture strength and marginal adaptation.

Progression of non-carious cervical lesions: 3D morphological analysis

OBJECTIVES

This longitudinal study aimed to investigate morphologically and quantitatively the progression of non-carious cervical lesions (NCCLs) using a confocal laser scanning microscope (CLSM) and replica models.

MATERIALS AND METHODS

The samples examined comprised sets of replicas annually obtained from 83 lesions in 16 participants over 3 to 5 years. All lesions were visually categorized as wedge-shaped, saucer-shaped, or mixed-shaped lesions. CLSM images of the replicas were analyzed in terms of axial depth, occlusogingival width (height) in the buccolingual cross-section, and estimated volume using a custom code of the image analysis software to estimate the progression of the NCCLs over time. The morphological characteristics of the NCCLs were also objectively divided into three groups according to the depth to height ratio (D/H ratio). Fisher's exact test and the Cochran-Armitage trend test were used for statistical analysis.

RESULTS

Saucer-shaped lesions progressed mainly in height, whereas wedge-shaped lesions increased both in height and depth. Annual progression in depth and volume significantly increased as the D/H ratio increased. More than half of the NCCLs with a small D/H ratio progressed 50 μm or more in height, whereas none of them progressed more than 50 μm in depth. Annual progression in depth significantly increased as the lesion depth at baseline increased.

CONCLUSIONS

Progression patterns significantly differed between NCCLs of different shapes. Most NCCLs progressed slowly in depth regardless of their shape. Moreover, NCCLs may progress through active and inactive stages.

Calcium Silicate-Based Biocompatible Light-Curable Dental Material for Dental Pulpal Complex

Dental caries causes tooth defects and clinical treatment is essential. To prevent further damage and protect healthy teeth, appropriate dental material is a need. However, the biocompatibility of dental material is needed to secure the oral environment. For this purpose, biocompatible materials were investigated for incorporated with dental capping material. Among them, nanomaterials are applied to dental materials to enhance their chemical, mechanical, and biological properties. This research aimed to study the physicochemical and mechanical properties and biocompatibility of a recently introduced light-curable mineral trioxide aggregate (MTA)-like material without bisphenol A-glycidyl methacrylate (Bis-GMA). To overcome the compromised mechanical properties in the absence of Bis-GMA, silica nanoparticles were synthesized and blended with a dental polymer for the formation of a nano-network. This material was compared with a conventional light-curable MTA-like material that contains Bis-GMA. Investigation of the physiochemical properties followed ISO 4049. Hydroxyl and calcium ion release from the materials was measured over 21 days. The Vickers hardness test and three-point flexural strength test were used to assess the mechanical properties. Specimens were immersed in solutions that mimicked human body plasma for seven days, and surface characteristics were analyzed. Biological properties were assessed by cytotoxicity and biomineralization tests. There was no significant difference between the tested materials with respect to overall physicochemical properties and released calcium ions. The newly produced material released more calcium ions on the third day, but 14 days later, the other material containing Bis-GMA released higher levels of calcium ions. The microhardness was reduced in a low pH environment, and differences between the specimens were observed. The flexural strength of the newly developed material was significantly higher, and different surface morphologies were detected. The recently produced extract showed higher cell viability at an extract concentration of 100%, while mineralization was clear at the conventional concentration of 25%. No significant changes in the physical properties between Bis-GMA incorporate material and nanoparticle incorporate materials.

Diagnosis, risk assessment, and treatment decisions for tooth wear in daily practice: a case presentation survey among Belgian dentists

This survey assessed the use of current concepts for tooth wear diagnosis, risk assessment, and treatment decisions in daily practice, and identified factors of significance for treatment decisions. A total of 104 dentists were presented with 10 cases representing varying degrees of tooth wear. The dentists were asked to answer six questions pertaining to the diagnosis, risk assessment, and treatment of each case. A benchmark was established by three experts and the agreement between dentists and the benchmark was calculated. At dentition level, the agreement was moderate for diagnosis (κ = 0.55) and risk assessment (κ = 0.54). At tooth/surface level, the agreement for clinical and radiographic severity of wear was moderate (κ = 0.57) and substantial (κ = 0.65), respectively. The agreement for treatment decision was fair (κ = 0.35). Multivariate logistic regression analysis showed that treatment decisions for operative treatment were associated with moderate to high case risk (OR = 10.1; 95% CI: 5.4-18.9). Belgian dentists performed reasonably well in applying current concepts and strategies for tooth wear diagnosis and risk assessments at dentition level, as well as for assessment of wear severity at tooth/surface level. Improvement is warranted concerning treatment decisions. This survey could be a useful tool for disseminating and improving current knowledge of tooth wear, and for training dentists in daily practice.

Association of Non-Carious Cervical Lesions with Oral Hygiene Habits and Dynamic Occlusal Parameters

Dentists routinely encounter non-carious cervical lesions (NCCLs) in daily clinical practices. The dental literature is contradictory regarding the occlusal etiology of NCCLs. NCCL is defined as the loss of dental structure at the cemento-enamel junction, with no association of bacteria. The aim of this study was to evaluate the association of dynamic occlusal factors and dental hygiene practices with NCCLs. In total, 100 participants were selected by the random stratified sampling method, 50 each for control and NCCL groups. Information regarding oral hygiene practices, including frequency, duration, force, and technique of brushing, was recorded. Dynamic occlusal parameters like initial contact, occlusion time (OT), disocclusion time (DT), and center of force were recorded with T-scan analysis. The obtained data were analyzed with Pearson's correlation and binary logistic regression. We found that 68% of participants in the NCCL group and 31% in the control group utilized the horizontal brushing technique; 46% of NCCL group participants used hard brush against 7% of participants in the control group. The mean OT was 0.727 and 0.516 s for NCCL and control groups, respectively. The OT and left and right lateral DT were strongly related to NCCL, with r-values of 0.661, 0.642, and 0.534, respectively, with p ≤ 0.001. Using a hard toothbrush was found to be associated with NCCL. The NCCL group had extended mean occlusion time and disocclusion time in all eccentric mandibular movements.

Composite vs. ionomer vs. mixed restoration of wedge-shaped dental cervical lesions: Marginal quality relative to eccentric occlusal loading

Dental cervical restorations may be impacted by resultants of occlusal loads that may have already contributed to the development of the lesion and should rely on materials' favorable properties to bear the stresses. The marginal quality of cervical restorations made with materials of different moduli of elasticity in essence, isolated, or in combination, was evaluated relative to eccentric occlusal loading. Cervical wedge-shaped cavities, prepared in extracted premolars, were restored with a composite resin (CR), a restorative ionomer (GIC), or the composite in combination with a lining ionomer (Mixed restoration: M). Half of the teeth in each group were subjected to eccentric occlusal loading (eol; 150 N / 10⁶ cycles / 2.5 Hz; CReol / GICeol / Meol, n = 10), and the others were stored in 37 °C distilled water (Control: c; CRc / GICc / Mc, n = 10). A fluorescein-modified adhesive favored delimitation of formed gaps, which were evaluated by confocal laser scanning microscopy regarding their presence, location related to the cavity walls, and width and depth (µm), at a 5% significance level. From a comprehensive perspective, neither the loading nor the materials were significantly associated with the qualitative response variables or exerted any influence over the quantitative variables. More specifically, the use of the different materials was significantly associated with the frequency of gaps exclusively when loading was applied (Chi-square test, p = 0.029, CR > M > GIC). Though the marginal quality of cervical restorations may not be influenced by eccentric occlusal loading or the use of different materials, even in association in general, the unfavorable aspects of the use of the composite may be relevant, particularly in face of the existence of eccentric occlusal loads.

Complications and survival rates of inlays and onlays vs complete coverage restorations: A systematic review and analysis of studies

OBJECTIVE

The aim of this study was to identify if different types of indirect restorations used for single teeth had different biological and technical complications, as well as survival rates.

METHOD

An electronic search was performed in various electronic databases to identify articles, published between 1980 and 2017. The search terms were categorised into 4 groups: inlay, onlay, inlay/onlay and crown. Manual searches of published full-text articles and related reviews were also performed.

RESULTS

A total number of 2849 papers were retrieved initially. After a detailed assessment for eligibility, 9 studies were selected for inclusion. The heterogeneity of the studies did allow neither a meta-analysis nor any meaningful comparison between types of restorations or materials. Only some pooling was performed for representative reasons. The mean survival rate of inlays was 90.89%, while for onlays and crowns it was 93.50% and 95.38%, respectively. For the fourth study group, consisting of both inlays and onlays, the survival rate was found to be 99.43%. Statistical analysis demonstrated caries to be the main biological complication for all types of restorations, followed by a root and/or tooth fracture incidence (11.34%) and endodontic incidence. Ceramic fractures represented the most common technical complication, followed by loss of retention and porcelain chipping.

CONCLUSION

The 5-year survival rate for crowns and inlays/onlays is very high, exceeding 90%. An association between the kind of complications and different types of restorations could not be established. Nevertheless, a relatively high failure rate due to caries and ceramic fractures was noted.

Etiological Aspects of Noncarious Dental Lesions

PURPOSE

The aim of the present study was to correlate etiological factors with noncarious cervical lesions in a group of patients from Craiova.

MATERIAL AND METHODS

The study was conducted between November 2015 and May 2016 on 50 patients, aged 18-56 years, who addressed to the Oral Rehabilitation Clinic, from the University of Medicine and Pharmacy of Craiova. Patients were divided into two groups: the study group consists of patients who had noncarious cervical dental lesions (NCCLs) and the control group with patients who did not have noncarious cervical lesions. Each patient underwent a clinical examination and completed a questionnaire, referring to eating habits, oral hygiene, vicious habits and personal impressions about the appearance and functionality of his teeth, highlighting the factors involved in the noncarious dental lesions etiology.

RESULTS

The study group consisted of 64% women and 36% men. Noncarious cervical lesions were higher in men (72.22%) compared to women (56.25%). Regarding on the tooth brushing method, it has been noted that 34% of patients used a vertical tooth brushing method, 52% were using a circular brushing method, while 14% were practicing a horizontal tooth brushing method. Cervical sensitivity has been detected in 48% of the patients, against 52% who showed no sensitivity. 62% of the participants did not have bruxism, while nighttime/daytime bruxism was found in 38% of the patients.

CONCLUSIONS

There are several etiological factors correlated with noncarious cervical lesions, among which are: tooth brushing method, bruxism, eating behaviors.

Abfraction lesions: etiology, diagnosis, and treatment options

Abfraction is a type of noncarious cervical lesion (NCCL) characterized by loss of tooth tissues with different clinical appearances. Evidence supports that abfraction lesions, as any NCCLs, have a multifactorial etiology. Particularly, the cervical wear of abfraction can occur as a result of normal and abnormal tooth function and may also be accompanied by pathological wear, such as abrasion and erosion. The interaction between chemical, biological, and behavioral factors is critical and helps to explain why some individuals exhibit more than one type of cervical wear mechanism than others. In an era of personalized dentistry, patient risk factors for NCCLs must be identified and addressed before any treatment is performed. Marked variations exist in dental practice concerning the diagnosis and management of these lesions. The lack of understanding about the prognosis of these lesions with or without intervention may be a major contributor to variations in dentists’ management decisions. This review focuses on the current knowledge and available treatment strategies for abfraction lesions. By recognizing that progressive changes in the cervical area of the tooth are part of a physiologically dynamic process that occurs with aging, premature and unnecessary intervention can be avoided. In cases of asymptomatic teeth, where tooth vitality and function are not compromised, abfraction lesions should be monitored for at least 6 months before any invasive procedure is planned. In cases of abfraction associated with gingival recession, a combined restorative-surgical approach may be performed. Restorative intervention and occlusal adjustment are not indicated as treatment options to prevent further tooth loss or progression of abfraction. The clinical decision to restore abfraction lesions may be based on the need to replace form and function or to relieve hypersensitivity of severely compromised teeth or for esthetic reasons.

Opinions on Dental Erosive Lesions, Knowledge of Diagnosis, and Treatment Strategies among Norwegian Dentists: A Questionnaire Survey

This study aimed to investigate dentists' general experience, knowledge about diagnosis, and treatment of dental erosive wear in young adults. A questionnaire was sent to 1262 Norwegian public dental health-employed dentists. The response rate was 60%. Results indicated that most dentists recorded erosive wear, half of them used a specific scoring system, and half registered lesions at the tooth surface level. Lesions were reported most often on palatal surfaces of upper anterior teeth (79% of dentists), on occlusal surfaces of lower 1st molars (74%), and on upper 1st molars (32%). Half the dentists used clinical photographs for documentation and 60% made study models. While 40% reported more erosive lesions in males, 36% reported no gender differences. High intake of carbonated beverages and acidic juices were reported as the most common cause by 97% and 72% of the dentists, respectively. Only 21% of dentists recorded the patient's dietary history, and 73% never measured saliva secretion. The majority (78%) of the dentists treated patients with erosive wear themselves. In general, the survey suggests that the dentists are relatively up to date regarding the clinical recording, diagnosis, and treatment of dental erosive wear. However, dietary and salivary analyses were not given priority, and early, preventive treatment was lacking.