Restorative material and loading type influence on the biomechanical behavior of wedge shaped cervical lesions.

OBJECTIVES: To evaluate the influence of restorative materials used on the rehabilitation of MOD cavities and loading type, on biomechanical behavior of wedge-shaped (WS) lesions in endodontically treated maxillary premolars. The investigation was conducted by 3D finite element analysis (FEA) and strain gauge test. MATERIALS AND METHODS: Six models were generated, with MOD cavities and endodontic treatment: A (MOD amalgam restoration), R (MOD composite restoration), AL (A + cervical lesion (L)), RL, ALR (A + cervical lesion restored with composite (LR)), and RLR. Each model underwent two compressive loading (100N): axial and oblique-45° angle to the long axis on the buccal cusp. The models were analyzed by von Mises criteria. For strain gauge test, 14 standardized maxillary premolars were treated according to the groups described for FEA. Two strain gauges were bonded on each sample submitted to compressive loading in a mechanical testing machine. RESULTS: A presented higher stress concentration and strain values than R. Oblique loading promoted highest stress concentration and strain rates for all groups. ALR and RLR presented similar stress-strain distribution pattern when compared to A and R. CONCLUSION: The interaction between MOD cavity restored with amalgam and oblique loading propitiated the highest stress concentration and strain values on cervical region and WS lesion. CLINICAL RELEVANCE: The MOD cavity restored with composite resin is a better option than amalgam to improve the biomechanical behavior of wedge-shaped lesion, avoiding dental failure. In addition, the occlusal interferences must be removed, allowing homogeneous contact distribution and preventing WS lesion progression.

Morphological characteristics of non-carious cervical lesions. A systematic review.

OBJECTIVES: This systematic review assessed the morphological characteristics of non-carious cervical lesions (NCCL), among clinical and ex-vivo studies assessed by observational and imaging methods. DESIGN: The search strategy was conducted on four online databases (MEDLINE, Embase, Scopus and Web of Science) and grey literature (Google Scholar and OpenGrey). The study selection was performed by three reviewers from March to September (2023). The eligibility criteria were established according to the PICO strategy and included NCCL, morphological characteristics and clinical and ex-vivo study designs. The data extraction considered general data that identifies the study, evaluation method, parameter to assess the outcome and the main results for each study. The risk of bias was evaluated using Joanna Briggs Institute critical appraisal tool, and a personalized tool. RESULTS: The search resulted in 252 studies. A total of 14 studies were included. Prevalence of NCCLs ranged from 3.5 %to 77.78 % with a higher presence in premolars. Common characteristics were wear facets, occluded tubules or cracks, occlusal stress, scratch marks, dimples and craters, structure loss, and dentin sclerosis, which appear more often on buccal surface and were generally classified as wedge-shaped, saucer-shaped. Etiological hypothesis was mainly related to multifactorial factors. In most of the studies, the risk of bias was classified as high. CONCLUSIONS: The morphological characteristics of NCCL showed a wide range of descriptions regarding appearance, prevalence, lesion-related measures, and macro and microscopic descriptions.

The Design, Development, and Calibration of Cervical Abrasion Index of Treatment Needs Probe for Measurement of Cervical Abrasion.

Context: Although a common dental problem, there are no simple instruments or reliable methods to measure cervical abrasion. Aim: To study the design, development, calibration, efficacy, and compliance of usage of a novel Cervical Abrasion Index of Treatment Need (CAITN) probe to measure cervical abrasion. Settings and Design: The ex-vivo study was conducted as a part of comprehensive study for the development of standardized CAITN probe and index with a standard methodology for recording the abrasion. Materials and Methods: The compliance and usage of the probe were assessed by a standardized set of questionnaires to the interns followed by an ex-vivo study in 100 subjects. Gold standard comparisons with Vernier caliper, inter-examiner, and intra-examiner reliability were analyzed using SPSS. Results: Data from the questionnaire indicate that 100% of examiners had no difficulty in handling the instrument or measuring and reading the values. Comparison between the CAITN probe and the gold standard was statistically significant indicating a correlation for cervical abrasion measurement between the two methods (p < 0.001). The mean difference between the two measurements using the CAITN probe and gold standard method was calculated with paired t-test and was insignificant (p > 0.05). High statistical significant correlation was also found for intra-examiner and inter-examiner reliability measurement of CAITN probe (p < 0.001). Conclusion: The design and structure of the CAITN probe are standardized with a fair gold standard comparison and that the novel probe can be used as an effective tool to measure the depth of cervical abrasion and its treatment needs.

Scanning electron microscope characterization of noncarious cervical lesions in human teeth.

AIMS: Abfraction is a theoretical process whereby occlusal forces create microfractures in enamel and dentin along the cervical area and predispose it to erosion and abrasion, forming noncarious cervical lesions. However, the theory is not yet proven. The aim of this study was to elucidate the role of abfraction as an etiology of these lesions. MATERIALS AND METHODS: Ten human premolars with these lesions from 10 patients requiring tooth extraction, one tooth from each patient, were used in this study. After extractions, all teeth were stored in 10% formalin until required, then prepared routinely for scanning electron microscopy. RESULTS: In all 10 teeth, at low magnification, noncarious cervical lesions appeared as crescent-shaped lesions. The upper edges of the lesions were on the enamel surfaces and their lower edges were on the cemental surfaces. In four teeth, the lesions showed evidence of microfractures characterized by the presence of fracture lines and fracture surfaces. In addition, in the first tooth of these teeth, the surface was also covered by a network of poorly fixed collagen fibers. In the third tooth, linear scratches, the openings of the dentinal tubules, a dentin matrix which consisted of a network of poorly fixed collagen fibers, and numerous dentinal tubules were also observed. In the remaining six teeth, they showed linear scratches, and the presence of the dentinal tubules or the exposed collagen fibers. CONCLUSIONS: It appears that abrasion and erosion are associated etiologic factors in forming noncarious cervical lesions and an ultrastructural finding that supports the abfraction theory of these lesions is observed.

Is There Evidence that Three-step Etch-and-Rinse Adhesives Have Better Retention Rates than One-step Self-etch Adhesives in Noncarious Cervical Lesions? A Systematic Review and Meta-Analysis.

PURPOSE: A systematic review and meta-analysis was conducted to compare the retention rates of 3-step etch-and-rinse (3ER) adhesives with 1-step self-etch (1SE) adhesives in noncarious cervical lesions (NCCLs). The secondary outcomes were marginal integrity and marginal discoloration. MATERIALS AND METHODS: Only randomized clinical trials (RCTs) that compared 1SE with 3ER in NCCLs were included. Controlled vocabulary and keywords were combined in the search strategy for PubMed/Medline, LILACS, BBO, Web of Science, Cochrane Library, grey literature, and IADR abstracts (1990-2018). The Cochrane Risk of Bias tool (RoB) was applied to eligible studies. Meta-analyses were conducted for retention rate and secondary outcomes at different follow-up times, using the random effects model. Heterogeneity was assessed with the Cochran Q test and I2 statistics. The GRADE approach was used to assess the quality of the evidence. RESULTS: After the removal of duplicates, title and abstract screening, 18 studies remained. Of these, 15 studies were used for meta-analysis. Fourteen out of these 15 were judged at "unclear" risk and 1 at "low" risk of bias. No significant differences between groups were observed in the different follow-up periods for retention rates 12 to 24 months (p = 0.66), 24 to 36 months (p = 0.21) and 60 months (p = 0.96). A significant difference in marginal integrity was found at 12 to 24 months (p = 0.04) and in marginal discoloration at 12 to 24 months (p = 0.003). CONCLUSION: There is no evidence that 3-step ER adhesives have better retention rates than 1-step SE adhesives in NCCLs.

Fracture Behavior and Integrity of Different Direct Restorative Materials to Restore Noncarious Cervical Lesions.

The purpose of this study was to analyze the fracture resistance and marginal leakage of noncarious cervical lesion (NCCL) restorations made of different restorative materials. Eighty upper premolars were randomly divided into four groups (n = 20/group). Standardized NCCL cavity preparations were performed on the buccal surface of the teeth and then restored with four different materials. Group 1: Packable resin composite (PC); Group 2: Highly flowable resin composite (HF); Group 3: Low flowable resin composite (LF); Group 4: Resin modified glass ionomer cement (RMGIC). After restorations were completed, cyclic and static fracture behavior was evaluated using a loading testing machine. Extra restored teeth were sectioned and then stained (n = 5/group). The specimens were viewed under a stereo microscope and the percentage of microgaps at the tooth-restoration interface was calculated. All restored teeth survived after fatigue loading. There was no statistically significant (p > 0.05) difference between the tested restorations after the static loading test. NCCLs restored with highly filled flowable composite showed the least microleakage among the tested groups (p < 0.05). The investigated restorative materials are acceptable for NCCL restorations in terms of fracture resistance and microleakage.

Treatments for hypersensitive noncarious cervical lesions: a Practitioners Engaged in Applied Research and Learning (PEARL) Network randomized clinical effectiveness study.

BACKGROUND: The Practitioners Engaged in Applied Research and Learning (PEARL) Network conducted a three-armed randomized clinical study to determine the comparative effectiveness of three treatments for hypersensitive noncarious cervical lesions (NCCLs): use of a potassium nitrate dentifrice for treatment of hypersensitivity, placement of a resin-based composite restoration and placement of a sealant. METHODS: Seventeen trained practitioner-investigators (P-Is) in the PEARL Network enrolled participants (N = 304) with hypersensitive posterior NCCLs who met enrollment criteria. Participants were assigned to treatments randomly. Evaluations were conducted at baseline and at one, three and six months thereafter. Primary outcomes were the reduction or elimination of hypersensitivity as measured clinically and by means of patient-reported outcomes. RESULTS: Lesion depth and pretreatment sensitivity (mean, 5.3 on a 0- to 10-point scale) were balanced across treatments, as was sleep bruxism (present in 42.2 percent of participants). The six-month participant recall rate was 99 percent. Treatments significantly reduced mean sensitivity (P < .01), with the sealant and restoration groups displaying a significantly higher reduction (P < .01) than did the dentifrice group. The dentifrice group's mean (standard deviation) sensitivity at six months was 2.1 (2.1); those of the sealant and restoration groups were 1.0 (1.6) and 0.8 (1.4), respectively. Patient-reported sensitivity (to cold being most pronounced) paralleled clinical measurements at each evaluation. CONCLUSIONS: Sealing and restoration treatments were effective overall in reducing NCCL hypersensitivity. The potassium nitrate dentifrice reduced sensitivity with increasing effectiveness through six months but not to the degree offered by the other treatments. Practical Implications. Sealant or restoration placement is an effective method of immediately reducing NCCL sensitivity. Although a potassium nitrate dentifrice did reduce sensitivity slowly across six months, at no time was the reduction commensurate with that of sealants or restorations.