Abfraction Lesions Research Articles

Dentists' education, knowledge, and professional behavior concerning the diagnosis and treatment of dentin hypersensitivity: An exploration.

Dentin hypersensitivity (DH) affects patients' oral health-related quality of life, but is not always optimally treated in dental offices. The objectives were to assess dentists' DH-related education, knowledge, and professional behavior and explore relationships between education, knowledge, and behavior. Survey data were collected from 220 ADA members in the United States. Descriptive and correlational analyses were performed. About half of the respondents agreed/strongly agreed that their dental school had educated them well about diagnosing DH in classroom-based (53.6%) and clinical settings (48.9%). Lower percentages agreed being well educated about treating DH (40.9%/37.3%). The majority self-educated themselves about DH after dental school by attending continuing education courses in person or online (60.6%/36.8%), reading articles (64.1%), or consulting with colleagues (59.6%). The majority knew that patients with DH describe their pain as stimulated (91.4%) and that recessed gingiva (89.6%), abrasion lesions (72.3%), tooth whitening (63.1%), erosion lesions (58.6%), and abfraction lesions (51.4%) are risk factors for DH. The majority diagnosed DH with patient self-reporting, confirmed by exams (81.8%), applying air blasts (53.7%), or cold-water (52.3%). They treated patients with DH often/very often with over-the-counter desensitizing agents (90%), and prescribing fluoride formulations toothpaste (82.8%) and/or potassium nitrate toothpastes (60.9%). In their offices, the majority (73.2%) educated their patients often/very often about DH and used fluoride dental varnish for treating DH (71.8%). The more recently respondents had graduated from dental school, the more positively they described their dental school education (r=0.14; p<0.05), the more ways to diagnose DH they used (r=0.16; p<0.05) and the more often they used fluoride dental varnish in their offices (r=0.23; p<0.001). The more dentists had educated themselves, the more methods for diagnosing DH they used (r=0.23; p<0.001) and the more often they used potassium oxalate products (r=0.19; p<0.01), Arginine/calcium products (r=0.19; p<0.01) and dentin bonding (r=0.22; p<0.001). More recently graduating from dental school correlates with more positive evaluations of DH-related dental school education. The finding that most dentists engage in self-education about DH after dental school should motivate dental educators to increase education about this topic not only in dental school, but also in continuing education courses.

Evaluation of Abfraction Lesions Restored with Three Dental Materials: A Comparative Study.

Abfraction lesions are manifested as damage to hard tissues in the cervical area of dental crowns. The study aimed to assess the direct restoration of abfraction lesions according to the modified United States Public Health Service (USPHS) criteria for 24 months. The restorations were accomplished with Fuji Bulk-GC, Omnichroma Flow-Tokuyama, and Beautifil® II-Shofu dental materials, and the therapy was or was not associated with wearing thermoformed mouthguards. From the 53 selected and analyzed patients (n = 53), 28 patients (with restorations of abfraction lesions) belonged to the 1st group and 25 patients (with 105 restorations, who also wore mouthguards) belonged to the 2nd group. Blind determination assessments were effectuated at baseline and after 2, 6, 12, 18, and 24 months. Results showed that, regardless of the rating score, there are no significant statistical differences in the evaluation criteria between the two groups of patients Conclusions: For each material, the scores of USPHS criterion presented good clinical performances after 24 months, with no significant statistical differences between the fillings and the applied therapy in the two groups of patients.

Abfractive lesions of teeth in dogs

Introduction . The study of patterns and features of the structural state of the dentoalveolar apparatus in representatives of the Canidae family is one of the urgent problems of veterinary dentistry. Understanding the etiological factors of pathologies of the dentoalveolar system allows the veterinarian and pet owners to preserve the function of the tooth as an organ, as well as its functionality by preserving the dentition. It has long been known and confirmed that the pathology of the dentition leads to the development of chronic diseases of the gastrointestinal tract, musculoskeletal system, cardiovascular system and respiratory organs. To systematize the clinical signs of defects and lesions of hard tissues of the teeth, a brief description of these lesions, their classification and clinical signs are given, which are taken from specialized sources and the practical experience of the authors. The purpose of the study was to systematize the clinical signs of defects and lesions of hard dental tissues in dogs of dwarf, small and medium breeds. Objects and methods . A sufficient analysis of significant specialized literature data and a clinical examination of the oral cavity organs were carried out using additional research methods, adopted in dentistry, on dogs (n = 70, dwarf, small and medium breeds). Results . To eliminate the gap in information about abfractional lesions of the teeth, a brief description of these lesions, their classification and clinical signs are given. Based on the study, the following specifications of clinical signs of dental lesions should be distinguished: the presence of microcracks, slight damage to tooth enamel, the formation of a mesh pattern of enamel and the predominance of horizontal lines over vertical ones, and the absence of gum recession. Our studies allow us to identify some features of the systematization of dental lesions in dogs, which is only the initial stage in the study of this complex process. Further research will improve the treatment and prevention measures and methods for the differential diagnosis of abfraction lesions of the teeth in dogs of small and dwarf breeds.

A One-Year Comparative Evaluation of Clinical Performance of Activa™ Bioactive composites with Microhybrid Composite In Abfraction Lesions: A Randomized Control Study

Aim This double-blind randomized controlled study aimed to compare and evaluate the clinical performance of Activatrade bioactive composites with microhybrid composites in abfraction lesions. Methodology Thirty-four teeth having abfraction were randomly divided into two groups n17 per group depending on the restorative material used. Group Andash Microhybrid composite and Group B ndash Activa composite. Initially occlusal contacts were evaluated for the patients and required occlusal adjustments were carried out. Restorations were done according to the manufacturerrsquos guidelines. Evaluation of the restorations was done at baseline 1 month 6 months and 1-year time interval by two blinded examiners as per the modified United States Public Health Service USPHS criteria. The statistical analysis was carried out and the results were tabulated.Results The clinical performance of microhybrid and Activa showed no statistically significant difference at post-op 1 month 6 months and 1 year pgt0.05. In intragroup assessment between baseline and 6 months both groups yielded similar clinical behavior whereas at 1 year a statistically significant difference p0.046 was noted with marginal adaptation in microhybrid group.Conclusion Acceptable clinical performance was shown by both groups by the end of 1 year. However discrepancies were noted in the marginal adaptation criteria for microhybrid. Active composites can be considered as the material of choice for restoring abfraction.

Abfraction lesion in central incisor tooth: displacement and stress evaluation by laser speckle and finite element analysis

The aim of this study was to evaluate the displacement and stress distribution in the cervical region of a mandibular central incisor tooth (MCIT) within wedge-shaped lesion simulating abfraction lesion by means of Laser Speckle (LS) and 3D Finite Element Analysis (FEA) and then compared. One experimental setup was assembled with a MCIT attached in resin and submitted to the LS. An increasing static load from 12.1 to 42.1N was applied in incisal buccal slope at 15º in relation to the tooth's long axis. A 3D numerical model with linear tetrahedral elements and homogeneous, linear and isotropic behavior was built with the same boundary conditions of the experimental setup. The LS present higher displacement in the wedge-shaped lesion than the FEA, but both had an excellent agreement in the displacement direction. The LS show a nonlinear behavior from 32.1N. The FEA has presented higher tensile stresses at the root dentin. In the FEA cementoenamel junction area, tensile stress isn't exceeding the enamel's tensile strength, under simulated conditions. It was concluded that LS is a faster tool and acceptable when studying the quantitative displacement of the biomechanical behavior in MCIT, and FEA is appropriate for the quantitative stress analysis, and both bring important results of the stress and displacement that are fundamental in planning preventive and restorative approach in non-carious cervical lesions.

Epigallocatechin-3-gallate prior to composite resin in abfraction lesions: a split-mouth randomized clinical trial.

Natural extracts have been investigated as a biomimetic strategy to mechanically strengthen the collagen network and control the biodegradation of extracellular matrix. This study evaluated the effect of epigallocatechin-3-gallate (EGCG) on abfraction lesions prior to the composite resin. The sample consisted of 30 patients (aged between 28 and 60 years) with abfraction lesions located in 2 homologous premolars. The teeth were randomly assigned according to dentin treatment: 0.02% EGCG solution or distilled water (control). After enamel acid etching, the solutions were applied immediately for 1 minute. The teeth were restored with Universal Adhesive (3M) and Filtek Z350 XT (3M). Analyzes were done by 2 independent examiners using modified USPHS (retention, secondary caries, marginal adaptation, and postoperative sensitivity) and photographic (color, marginal pigmentation, and anatomical form) criteria at baseline (7 days) and final (18 months). The data analysis used Friedman and Wilcoxon signed-rank tests (α = 0.05). At baseline, all restorations were evaluated as alpha for all criteria. After 18 months, restorations were evaluated as alpha for secondary caries, color, and marginal pigmentation. There was significant difference between baseline and 18 months (p = 0.009) for marginal adaptation and postoperative sensitivity (p = 0.029), but no significant difference were verified between treatments (p = 0.433). The EGCG group had a restoration retention rate of 93.3%, while the control group had 96.7%. The application of EGCG solution on abfraction lesions did not significantly influence the survival of the restorations based on clinical and photographic criteria.

The Influence of Different Occlusal Loading on Six Restorative Materials for Restoration of Abfraction Lesions—Finite Element Analysis

The aim of the study was to analyze the occurrence of stress on teeth with abfraction lesions restored with six different restorative materials, and by introducing the tensile strength parameters to calculate the safety factor of the material under the load (ratio between the strength of the material and the maximum stress). Three-dimensional models of the mandibular premolar are created from a microcomputed tomography images. An abfraction lesion is modeled on the tooth. The stress of the dental tissues and six restorative materials under functional and nonfunctional occlusal loading of 200 (N) are analyzed by finite element method. CTAn program 1.10 and ANSYS Workbench (version 14.0) were used for analysis. Results are presented in von Mises stress. Oblique loads caused ≈ four times higher stress in restorative materials than the axial ones. It is noticeable that high values of von Mises stress are measured at the bottom of the sharp lesion, even up to 240 MPa, that are significantly reduced after the restoration. The highest stresses at the restorative material are present at the lower (gingival) margin of the restoration. The highest stresses under both types of loads are measured in nanohybrid composite (Tetric EvoCeram, Ivoclar Vivadent). The lowest values of the stress are measured in the flowable composite (Tetric Flow, Ivoclar Vivadent), but at the same time, the highest value of the stress is measured in the surrounding dental tissues on the tooth restored with the flowable composite. The microhybrid composite (Herculite XR, Kerr), with the highest safety factor, is the material that best withstands the stresses it is exposed to. The obtained safety factor did not exceed the critical limit, except for the glass ionomer cement, with the safety factor lower than 1. The type of tooth loading has the greatest influence on the intensity of stress. The value of the obtained stresses in the restorative material and dental tissues differ due to the different mechanical properties of the materials. Restoration of noncarious lesions significantly reduces extremely high stress values at their bottom.

Penatalaksanaan Perawatan Saluran Akar pada Gigi dengan Lesi Abfraksi : Laporan Kasus

Background: Pulp and periapical disease may also result from the presence of a cervical cavity reaching the pulp chamber as an abfraction lesion. Abfraction causes the dentinal tubules to be exposed so that it becomes a pathway for microorganisms to enter the pulp. Root canal treatment in cases with abfraction lesions requires special management, so that contamination does not occur during treatment due to the exposed cervical part. Objective: Discusses the management of root canal treatment in teeth with abfractional lesions that penetrate the pulp chamber. Case Management: A 53-year-old male patient came RSGM Unand because he wanted to be treated for a cavity in his right lower posterior tooth and had a sudden throbbing pain. Based on the results of subjective, objective and preoperative radiographs, tooth 45 was diagnosed with pulp necrosis with chronic apical abscess. Pulp and periapical disease of tooth 45 was probably caused by the entry of microorganisms through the abfraction lesion that reached the pulp chamber. Temporary coronal seal of the abfraction cavity and access occlusal cavity is necessary to prevent the entry of microorganisms during root canal treatment procedures. The final restoration is a direct composite resin using a fiber-reinforced composite (FRC). Conclusion: The management of root canal treatment in this case of abfraction lesion showed success as indicated by the absence of subjective complaints, objective examination showed negative results, and periapical lesions showed healing seen on periapical radiographs.&#x0D;

Modified Technique of Porcelain Laminate Veneer in Premolars with Abfraction Lesions: Three-Dimensional Finite Element Analysis (FEA)

The incidence of non-carious cervical lesions (NCCLs) has increased as populations are aging, and teeth are increasingly retained for life. Several materials are available to treat these lesions. This study aimed to evaluate the stress distribution of maxillary premolars with NCCLs using three-dimensional (3D) finite element analysis (FEA) according to different restorative techniques. A 3D FEA mathematical model simulating a sound premolar was initially modeled and replicated in 6 more models simulating a tooth with abfraction: G.1 tooth with abfraction; G.2 tooth with abfraction + composite resin restoration; G.3 tooth with abfraction + glass-ionomer cement restoration; G.4 tooth with abfraction + resin composite restoration + porcelain laminate veneers; G.5 tooth with abfraction + glass-ionomer cement + porcelain laminate veneers; and G.6 modified porcelain laminate veneers filling the lesion. All materials and structures were considered linear, elastic, homogeneous and isotropic and the results were expressed as maximum principal stress. Lower stress concentration in dentin was calculated when the tooth was restored with composite resin and glass-ionomer cement. Regarding the veneer techniques, no difference was found to dentin stress among the groups, but the modified veneer concentrated less stress in the restoration than other the techniques. The control group had the highest concentration of stress in the lesion. All techniques decreased the stress concentration inside the NCCLs and the indirect veneer filling the lesion presented better biomechanical behavior than the veneer cemented above direct restorations. Keywords: Finite Element Analysis. Dental Veneers. Ceramics. Bicuspid. Resumo A incidência de lesões cervicais não-cariosas (LCNC) tem aumentado, uma vez que a população tem envelhecido com uma menor perda de elementos dentários. Diferentes materiais estão disponíveis para tratar dessas lesões. Este estudo objetivou avaliar a distribuição de tensão de pré-molares superiores com LCNC por meio da análise tridimensional (3D) de elementos finitos (FEA) de acordo com diferentes técnicas restauradoras. Um modelo matemático 3D FEA simulando um pré-molar íntegro foi modelado e replicado em mais 6 modelos simulando um dente com abfração: G.1 dente com abfração; G.2 dente com abfração + resina composta; G.3 dente com abfração + cimento de ionômero de vidro; G.4 dente com abfração + resina composta + faceta; G.5 dente com abfração + cimento de ionômero de vidro + faceta cerâmica e G.6 com faceta cerâmica modificada, preenchendo a lesão. Todos os materiais e estruturas foram considerados lineares, elásticos, homogêneos e isotrópicos e os resultados foram expressos como máxima tensão principal. Menor concentração de tensão na dentina foi calculada quando o dente foi restaurado com resina composta ou cimento de ionômero de vidro. Dentre os grupos com laminados, não houve diferença para a dentina, entretanto a faceta modificada apresentou menor concentração de tensão na restauração. O grupo controle apresentou a maior concentração de tensão na lesão. Todas as técnicas restauradoras diminuíram a concentração de tensão no interior das LCNCs e dentre as técnicas com laminados a faceta modificada apresentou o melhor comportamento biomecânico. Palavras-chave: Análise de Elementos Finitos. Facetas Dentárias. Cerâmica. Dente Pré-Molar.

Retrospective Analysis of the Association of Non-Carious Cervical Lesions with Bruxism

Recently, bruxism became the center of attention for the etiological research of non-carious cervical lesions (NCCLs). The present study aims to investigate the presence and types of NCCLs associated with bruxism. Retrospective keywords search of the clinical notes of all patient charts in axiUmTM was performed using the terms “bruxism”, “attrition”, “abrasion”, “erosion”, and “abfraction”. All bruxer patients 18 years and older who presented to the UNLV School of Dental Medicine (01/01/2014 to 09/30/2018) with the complete record were included. To determine the statistical analysis implications, the chi-square test was used. Commonest types of NCCL associated with bruxism were attrition and abfraction. Five hundred seventeen cases had multifactorial lesions. Anterior maxillary teeth followed by mandibular anterior were the most affected teeth. Abfraction lesions were mainly sighted in maxillary premolars, followed by maxillary canines. Within the limitation of the present investigation, it was concluded that attrition and abfraction were highly associated with bruxism.

Abfraction: Etiopathogenesis, clinical aspect, and diagnostic-treatment modalities: A review

Abfraction is a loss of tooth structure along the gingival margin and manifests with different clinical appearances. It has multifactorial etiology and may occur due to normal and abnormal tooth function and may also be accompanied by pathological wear, such as abrasion and erosion. The theory behind the abfraction is that the tooth flexure in the cervical area is caused due to occlusal compressive forces and tensile stresses. This results in the fractures in the hydroxyapatite (HA) crystals. It is also caused by the low packing density of the Hunter-Schreger band (HSB) at the cervical area. Unfortunately, there is a lack of evidence regarding the outcome of abfraction with or without intervention. The aim of this review is to collect clinical information from the literature and discuss the etiology, pathogenesis, clinical representation, and management. Also, search databases for clinical studies that describe the role of sclerotic dentine in non-carious cervical lesions (NCCLs) are becoming a clinical challenge. The literature was searched that described the etiology, pathogenesis, clinical representation, and management of the abfraction lesions. Also, a specific question regarding the formation of sclerotic dentin in the NCCL lesion was described and searched for evidence that challenges etching, bonding, and successfully restoring NCCLs. The databases PUBMED, SCOPUS, MEDLINE, WEB of SCIENCE, and EMBASE were searched using the key terms. The inclusion criteria were the randomized controlled clinical trial, cohort studies, and cross-sectional studies that aimed at determining the role of sclerotic dentine in NCCLs and its effect on etching, bonding. One clinical study was retrieved according to the PRISMA flowchart and PICO format. The longer etching time, total-etch adhesive system, and EDTA pre-treatment of the sclerotic dentin of cervical wedge-shaped defects could improve the bonding strength in lesions like NCCL's. In conclusion, clinical challenges that occur due to NCCLs are better managed by a proper understanding of factors like etiopathogenesis, ultra-structure of enamel, and dentine and their effect on the bonding of restorations of the tooth.

Occlusal Stress Distribution on the Mandibular First Premolar - FEM Analysis.

The aim of this paper was to analyze the distribution of stress and deformation on the mandibular first premolar under two types of loading (axial and para-axial load of 200 N) using the FEM computer method. For this research a µCT scan of the first mandibular premolar was used, and the method used in this research was FEM analysis under two types of loading. The values of the von Mises stress measured in the cervical part of an intact tooth under axial load were up to 12 MPa, and under paraaxial load over 50 MPa. The values of the stress measured on the bottom of the noncarious lesion are very high ≈ 240 Mpa. Stress values in the cervical part of the intact tooth are higher in the zone of the sub-surface enamel. The deformation values of the tooth under para-axial loading were ≈ 10 times higher than the value of the deformation under axial load. The greatest deformations were seen in the area of the tooth crown. Occlusal loading leads to significant stress in the cervical part of teeth. The values of the measured stress are greater under the action of paraxial load. The values of stress in abfraction lesions measured under a paraxial load are extremely high. Exposing the lesion to further stress will lead to its deepening. The total deformation of the entire tooth under paraxial load was ≈ 10 times higher compared to the deformation value of the tooth under axial load.

Non-carious cervical lesions - can terminology influence our clinical assessment?

Introduction Abfraction is a theoretical term used that has been classified as a type of non-carious cervical lesion (NCCL) and characterised by the microstructural loss of hard dental tissue in areas of high stress concentration. There is a lack of consensus among researchers and clinicians as to whether occlusal loading, particularly interferences or eccentric loading, generates sufficient tensile stress to be an aetiological factor in the loss of hard dental tissue at the cemento-enamel junction (CEJ).Aim This narrative review article assesses the evidence behind the theory of abfraction.Results It is difficult to control all influencing factors in a clinical trial making it challenging to generate sufficient evidence to conclusively support the theory of abfraction. There is limited evidence occlusal forces are an aetiological agent in non-carious cervical lesion development. However, if occlusal forces do play a role, the term non-carious cervical lesion is more reflective of the limited role it may play and a multifactorial aetiology.Conclusion The term 'abfraction lesion' remains misleading and could be removed from our diagnostic vocabulary.

Compressive Strength of Direct Tooth Colored Restorative Materials

New materials are being introduced to address the need for restoring both carious and non carious (caused by a combination of abrasion, erosion and abfraction) lesions. In an era when more and more patients are retaining their natural dentition, the need for this restoration is increasing. The ideal materials should be adhesive, tooth colored and abrasion-resistant&#x0D; Materials and Methods: Seven disc samples of Compomer, Giomer &amp; Composite restorative materials were prepared for measurement of compressive strength.&#x0D; Results: The value of Compressive strength of Giomer becomes high in comparison to Compomer but not significant in comparison to Composite.&#x0D; Update Dent. Coll. j: 2019; 9 (2): 36-39

Treatment of non-carious lesions: Diagnosis, restorative materials and techniques

Management of non-carious cervical lesions (NCCLs) still is a challenge in clinical practice. The diagnosis is the key to treat these lesions successfully. Aim/Case report: Therefore, the aim of this case report is to describe the diagnosis and treatment of generalized abfraction lesions associated to abrasion lesions of a 43 years old patient and to discuss considerations about the technique and materials to be used appropriately. After the diagnosis, a treatment plan with preventive and restorative approach was elaborated. The occlusal adjustment was performed to distribute the contact points and the patient was instructed in relation to tooth brushing habits. It was also recommended that the patient use a dentifrice with potassium nitrate for the control of sensitivity. For lesions over 1mm deep, the restorative treatment was performed using the self-etching adhesive system and nanohybrid composite by the stratification technique. Unsatisfactory restorations have been replaced. Occlusal splint was done and the patient was instructed to use the device every day overnight. One year after treatment, follow-up was performed. The appearance of new NCCLs was not observed. There was no progression of lesions smaller than 1 mm. There was no loss of restorations. All restorations were fully satisfactory and the patient reported absence of dentin hypersensitivity. Conclusion: The treatment performed besides being aesthetically satisfactory after 1 year resulted in the control of the disease, preventing the appearance of new lesions and guaranteeing a better quality of life to the patient.

Effect of finish line level of all ceramic crown on stress distribution within dentin of maxillary central incisor with an abfraction lesion

Purpose: to evaluate by means of three dimensional finite element analysis, the effect of finish line location on stress distribution on dentin of maxillary central incisor affected by abfraction lesion and covered with IPS e. max (Lithium di silicate) crown. Statement of the problem: In some cases of abfraction, the tooth need to be covered with full coverage crown, but, location of finish line may affect dentin integrity. Materials and Methods: 3D finite element model of unprepared maxillary central incisor was made. By deleting method, IPS e.max crown was designed and geometric dimensions of prepared tooth were introduced as the following guidelines, 2 mm incisal reduction, 1.5 mm reduction of labial surface and 1 mm circumferential shoulder finish line. The position of labial finish line was designed in three different levels apical to the upper margin of the abfraction lesion (0.5. 1.0 and 1.5 mm) forming three models to be tested (A, B and C) respectively in addition to unprepared control model. Results: For all tested four models, the calculated stresses with 125° applied load were higher than that with 60° with statistical significant differences. The calculated stresses at the control model in both directions of applied load were lower than that in other tested models (A, B and C) with statistical significant differences. For control model at 125° applied load, Von Mises equivalent stress value was (40.27 MPa), whereas, in case of 60° applied load, was (26.33 MPa). For model (A) where the finish line of IPS e.max crown is established 0.5 mm apical to the upper edge of the abfraction lesion, Von Mises equivalent stress values were (22.14 & 39.68 MPa) respectively. Conclusion: In all tested models, maximum stresses increased with increasing the angle of applied load, and model (B and C) provided more favorable stress distribution than that in model (A).

Influence of the occlusal contacts in formation of Abfraction Lesions in the upper premolar

Objective: The aim of this study was to observe the influence of different occlusal contacts in a superior pre-molar structure using Finite Element Analysis. Material and Methods: A three-dimensional model of a superior pre-molar was designed to simulate three occlusion situations, namely central occlusion and two types of lateral occlusion contacts. The model presents enamel, dentin, a periodontal ligament and a fixation cylinder separately. All materials were considered isotropic, linear and homogeneous, and the contacts of each structure were perfectly bonded. On analysis software, a load was applied to an occlusal surface at 40° to the long axis on lateral contacts, and directed to the long axis on central occlusion contact. Results: The results were obtained in stress maps and the maximum values were then plotted in table for quantitative comparison, with the enamel concentrating more stress than dentin and the occlusal contact presenting the worst biomechanical behavior. Conclusion: Within the limitations of this study, it is possible conclude that: eccentric contacts have higher potential to develop abfraction lesions on the cervical region of teeth, thus increasing the magnitude of tensile and shear stresses.KeywordsFinite Elements Analysis, Abfraction; Stress distribution; Occlusion, Premolar.

Are the bite force and electromyographic activity altered in muscle TMD patients with abfraction lesions?

Objective: To verify if the maximal molar bite force (BF) and the electromyographic activity (EMG) are altered in TMD patients with abfraction lesions (AL) when compared to those without AL.Methods: The sample was composed of 45 patients (18–60 years old), 30 diagnosed with TMD (RDC/TMD) (15 with AL and 15 without AL) and 15 controls. The BF and the EMG of the masticatory muscles (maximal voluntary contraction (MVC) and chewing gum) were measured.Results: TMD patients showed decreased BF (p < 0.001), without differences between patients with and without AL. The electromyographic activity during MVC was similar among all groups (p > 0.05), although there was a greater trend of muscular balance for the control group (percentage overlapping coefficient and electromyographic indexes). The TMD group without AL showed a lower number of cycles and masticatory frequency.Discussion: TMD patients with and without AL exhibited similar results in the analysis of the BF and EMG, without differences.

Etiology, diagnosis, and treatment of abfraction lesions

Etiology, diagnosis, and treatment of abfraction lesions

The Influence of Cervical Cavity Shape on the Restoration Material Retention. A finite element method study

Present study examines, by means of finite element method, the influence of cervical cavity shape on tensions distribution caused by occlusal overload of the teeth with abfraction lesion. Same force values are applied to four 3-D lower premolar finite element models, representing four different cavity shapes. An extracted lower premolar which presented an abfraction lesion has been used. The restoration was achieved by using ER adhesive systems and Giomers. The premolar was scanned and the resulting sections were processed and converted into a 3D digital format. Thus, a model of finite elements which presented a restored wedge-shaped cavity in the cervical dental area was obtained. Then, by modifying the shape and dimensions, there were created another 3 modified-shape cavities. Forces of different magnitudes (45-150N), exerted at a 45 degree angle on buccal cusp, have been applied. A wedge-shaped cavity with a short occlusal side does not show tension in the cervical region, nor in the distal angle of the restoration up to a force of 100N. So, in order to increase the retention of the abfraction restoration, changing the shape of the cavity could be the treatment of choice. Clinical relevance In order to avoid costly and unethical research, by means of FEM, different shapes of cervical cavities were easily created and conditions that influence retention of abfraction restoration were tested.