Prevalence of noncarious cervical lesions and their relation to occlusal aspects: a clinical study

Sixty-month comperative evaluation of a glass hybrid restorative and a composite resin in non-carious cervical lesions of bruxist individuals

OBJECTIVE

To compare the clinical performance of a glass hybrid (GH) restorative and a nano-ceramic composite resin (CR) in the restoration of non-carious cervical lesions (NCCLs) of bruxist individuals in a 60-month randomized clinical trial.

MATERIALS AND METHODS

Twenty-five bruxist candidates having NCCLs were recruited in this clinical study. The depth, height (cervico-incisal), width (mesio-distal), internal angles of the NCCLs, degree of tooth wear (TWI) and gingival index (GI) were measured. One hundred-and-forty-eight NCCLs were restored either with a GH restorative (Equia Forte Fil) or a CR (Ceram.X One Universal). Modified USPHS criteria was used to evaluate restorations after 1 week and 12, 24, 36 and 60 months. Pearson's Chi-Square, Fisher's Exact and Cochran Q tests were run for analysis. Survival rates of the restorations were compared with Kaplan-Meier analysis (p < 0.05).

RESULTS

After 60 months, 97 restorations in 15 patients were examined. The recall rate was 60.0%. Retention rates were 73.5% for CR and 66.7% for GH. A total of 29 restorations were lost (13CR (26.5%), 16GH (33.3%)). There was not a significant difference between tested restoratives in retention (p = 0.464), marginal adaptation (p = 0.856) and marginal discoloration (p = 0.273). There was no relationship between internal angle, depth, height or width and retention of the GH or CR restorations (p > 0.05). The increase in retention loss and marginal discoloration of both restorations over time were significant (p < 0.001). Sensitivity or secondary caries were not detected after 60 months.

CONCLUSION

GH and nano-ceramic CR showed similar clinical performances in NCCLs after 60 months in patients with bruxism.

CLINICAL SIGNIFICANCE

After 60 months, CR and GH materials showed clinically acceptable performances in restoration of NCCLs in patients with bruxism.

Noncarious cervical lesions: Response from a 25-year clinical follow-up study

STATEMENT OF PROBLEM

The etiology and diagnosis of noncarious cervical lesions (NCCLs) remain poorly understood.

PURPOSE

The purpose of this clinical study was to examine NCCL progression in an existing group of participants, establish the incidence of new NCCLs in a 25-year follow-up study, and relate them to possible risk factors, including occlusal factors.

MATERIAL AND METHODS

Thirty-three participants who had completed a questionnaire about their habits, diet, and personal information were evaluated in this observational retrospective study. Impressions were made, and casts from 3 time periods (Phase I in 1996, Phase II in 1999, and Phase III in 2021) were scanned to obtain digital casts. The casts were then evaluated in a 3-dimensional analysis software program (Geomagic Control; 3D Systems) to establish digital comparisons between NCCLs and occlusal wear. Furthermore, data from an occlusal analysis device (T-Scan; Tekscan) collected in Phase I was used to analyze occlusal interferences relating to the progression of NCCLs. The statistical analysis applied nonparametric tests, followed by the assessment of the association between NCCLs and risk factors, including occlusal wear, through binary logistic regression (α=.05).

RESULTS

At the end of Phase III, 7 new individuals with NCCLs were detected compared with Phase II. The median percentage progression of NCCLs per participant was 0.0% in Phase I, 7.1% in Phase II, and 35.7% in Phase III (P<.005). Occlusal wear in Phase I was associated with 5.02 times the occurrence of NCCLs in Phase III; occlusal wear in Phase II was associated with 4.73 times the occurrence of NCCLs in Phase III; and occlusal wear in Phase III was associated with 1.94 times the occurrence of NCCLs in Phase III (P<.001). Occlusal interference in border movements of the mandible was associated with a 3.55 times greater chance of presenting NCCLs in Phase III (P<.001). Additionally, statistically significant risk factors for the presence of NCCLs in Phase III were an acidic diet (P=.043) and alcohol consumption (P=.021).

CONCLUSIONS

The 25-year data showed an association between NCCLs and specific risk factors, including occlusal wear and occlusal interferences.

Numerical Modeling of a New Type of Prosthetic Restoration for Non-Carious Cervical Lesions

The paper considers a new technology for the treatment of non-carious cervical lesions (NCCLs). The three parameterized numerical models of teeth are constructed: without defect, with a V-shaped defect, and after treatment. A new treatment for NCCL has been proposed. Tooth tissues near the NCCLs are subject to degradation. The main idea of the technology is to increase the cavity for the restoration of NCCLs with removal of the affected tissues. The new treatment method also allows the creation of a playground for attaching the gingival margin. The impact of three biomaterials as restorations is studied: CEREC Blocs; Herculite XRV; and Charisma. The models are deformed by a vertical load from the antagonist tooth from 100 to 1000 N. The tooth-inlay system is considered, taking into account the contact interaction. Qualitative patterns of tooth deformation before and after restoration were established for three variants of the inlay material.

Modifications of the Dental Hard Tissues in the Cervical Area of Occlusally Overloaded Teeth Identified Using Optical Coherence Tomography

Background and objectives: Occlusal overloads produce a series of manifestations in teeth, especially attrition and non-carious cervical lesions (NCCL). Optical Coherence Tomography (OCT) can highlight and evaluate tooth lesions. The aim of this study was to examine the changes of dental hard tissues in the cervical area because of occlusal overload by macroscopic examination and using in vitro Swept Source OCT examination. Materials and Methods: The study was performed on 21 extracted teeth with occlusal trauma. After macroscopic and OCT examination, the 2D OCT images were transformed into 3D images using ImageJ software. Statistical analysis of macroscopic and OCT images was performed with Statistical Package for Social Sciences. Results: On 21 teeth, 88 cervical lesions (cracks) were identified. Upper premolars with an occlusal Smith and Knight tooth wear score of 2 had the most NCCL. Statistical analysis revealed significant differences in the median widths of cervical lesions between teeth with score 1 and score 3. Additionally, we obtained statistically significant differences in median widths between the buccal and oral surfaces. Conclusions: These cracks can be considered precursors of NCCL. NCCL can be located on dental surfaces in the cervical area other than the buccal one. A 3D reconstruction of OCT images emphasized that cracks are located especially at enamel level, evolving towards the enamel-dentin junction, with multiple ramifications.

Prevalence of non-carious cervical lesions and orthodontic treatment: a retrospective study

Background

This study aimed to assess the distribution of non-carious cervical lesions (NCCLs) by tooth type, investigate the prevalence of NCCLs in patients undergoing orthodontic treatment, and identify the possible associated factors.

Material and methods

A total of 160 patients were enrolled in this retrospective study. Data on the following variables were collected from pre-and post-orthodontic treatment records: age, sex, Angle’s malocclusion, facial pattern, number of activation sessions, compensatory treatment, and retreatment. Frontal, right and left lateral intraoral photographs of each patient were evaluated to identify the presence or absence of NCCLs in each tooth and assess the distribution of NCCLs in the 3840 teeth from the enrolled patients. Furthermore, patients were classified as NCCLs present, irrespective of the number of NCCLs on the teeth or NCCL absent. Bivariate and multivariate Poisson regression analyses with robust variance were used to assess the association between the NCCLs and each independent variable. Prevalence ratio and 95% confidence intervals were calculated and p < 0.05 was considered statistically significant.

Results

The prevalence of NCCLs before and after orthodontic treatment was 22.71% and 30.91%, respectively. Premolars were the most affected teeth, followed by the first molars, canines, and incisors. After statistical analysis, age was found to be the variable factor that influenced the prevalence ratio, with NCCL being the most prevalent when orthodontic treatment was performed in adulthood.

Conclusions

Premolars were most commonly affected by NCCLs. Furthermore, age seemed to contribute to the increased prevalence of NCCLs in adults undergoing orthodontic treatment.

The prevalence of non-carious cervical lesions (NCCLs) with or without erosive etiological factors among adults of different ages in Tokyo

OBJECTIVES

To evaluate the prevalence of non-carious cervical lesions (NCCLs) on teeth with or without erosive etiological factors across a broad range of ages of Japanese adults.

MATERIALS AND METHODS

The study sample consisted of a total of 1108 subjects aged 15 to 89 years in Tokyo, Japan. Two examiners evaluated NCCLs and dental erosion (DE) during a full-mouth examination. Subjects were asked to complete a self-administered daily diet, habits, and health condition questionnaire. Subjects who had frequent acid consumption or gastric reflux and at least one tooth with initial enamel wear were placed in the erosion present (EP) group, and the remainder of subjects were placed in the erosion not present (EN) group. Logistic regression analyses were carried out to identify etiological factors of NCCLs associated with DE.

RESULTS

Overall prevalence of NCCLs was 60.2%; the prevalence increased with age. There were no statistical differences in the prevalence of NCCLs between the EP and EN groups, except for the 60-69 years group. Multiple logistic regression analysis showed the frequency of consumption of carbonated soft drinks, citrus juice, and acidic fruits such as oranges; tooth brushing pressure; and bruxism were associated with the presence of NCCLs.

CONCLUSION

There were no statistical differences in the prevalence of NCCLs with or without erosive etiological factors except for the 60-69 years group.

CLINICAL RELEVANCE

NCCL distribution increased with age, and erosive risk factors caused by change in dietary habits might affect the incidence of NCCLs for elders.

TRIAL REGISTRATION

UMIN000041982.

Prevalence of non-carious cervical lesions among the general population of the Republic of Srpska, Bosnia and Herzegovina

INTRODUCTION

As non-carious cervical lesions (NCCLs) may compromise aesthetics and function, knowledge of their aetiological covariables enhances management of clinical complaints and success of restorative treatments.

AIMS

The primary aim of this study was to assess the presence of NCCLs among the general population of the Republic of Srpska, Bosnia and Herzegovina and the potential association with patient-related risk factors.

METHODS

A prevalence study of NCCLs included 738 respondents from eight towns/municipalities. Two dental practitioners examined all respondents. NCCLs were diagnosed according to the Smith and Knight tooth wear index, measured using a Williams periodontal probe. Data regarding risk factors were obtained through a structured questionnaire. Multivariate logistic regression was used to analyse the association of risk factors and the occurrence of NCCLs.

RESULTS

Non-carious cervical lesions were diagnosed in 384 (52%) respondents. Multivariate regression analysis showed that several variables were independently associated with the risk of developing NCCLs, including frequent consumption of acid food (P = 0.001), frequent consumption of acid drinks (P = 0.001), retaining drink in the mouth (P = 0.001), alcohol consumption (P = 0.030), bruxism (P = 0.018) and gastro-oesophageal reflux (P = 0.023). First mandibular premolars were the most affected teeth (left: 46.0%; right: 44.0%), followed by the second right maxillary premolars (37.3%), second left maxillary premolars (33.6%) and finally by the first right maxillary premolars (34.0%).

CONCLUSION

The results of the current study suggest that NCCLs occur frequently and have a multifactorial aetiology. The lowest prevalence was recorded among individuals younger than 20 years of age. As the majority of risk factors are modifiable, regular dental care could lead to the early detection of NCCLs.

The Role of Occlusal Factors in the Presence of Noncarious Cervical Lesions in Young People: A Case-Control Study

Objective:

The aim of this retrospective case-control study was to evaluate the influence of different occlusal characteristics and self-referred bruxism in the presence of noncarious cervical lesions (NCCLs).

Methods and Materials:

The participants were 280 students (140 cases and 140 controls), with an average age of 24.5 years, from six schools of dentistry in Spain. Clinical examination was carried out to record the NCCLs and the static and dynamic occlusal characteristics. The side of mastication and bruxism was collected by questionnaire. Data variables were analyzed by means of univariate and multivariate logistic regression. Odds ratios and the respective 95% confidence intervals were calculated (p&lt;0.05).

Results:

The presence of NCCLs was significantly more likely in subjects with protrusive interferences (odds ratio [OR]=1.82); with lateral interferences, especially on the nonworking side (OR= 1.77); or who were self-reported bruxists (OR=1.72). In the multivariate analysis, protrusive interferences, bruxism, age, and the presence of attrition were risk factors for the development of NCCLs. These factors resulted in a model with an area under the receiver-operating characteristic curve of 0.667 and a positive predictive value of 61.43%.

Conclusions:

There was no significant relationship between most occlusal factors and the presence of NCCLs. Only bruxism, protrusive interferences, age, and occlusal wear were risk factors. The predictive model was not sufficiently explanatory. Occlusal factors alone do not appear to be sufficient to explain the presence of NCCLs.

Predictors of long-term outcomes in patients undergoing periodontal maintenance

AIM

This retrospective study aimed to characterize the baseline status of patients following periodontal maintenance, analysing the association between the long-term outcome of these patients, smoking, bruxism, and the main clinical and radiographic variables.

MATERIAL AND METHODS

A sample of 174 patients with moderate to severe periodontitis was refined into homogeneous subsamples according to smoking and bruxism and the rate of tooth loss due to periodontal disease (TLPD): 0, 1-2, and >2 teeth. The association and the distribution (χ² test) of the variables within the subsamples were analysed.

RESULTS

Smoking and bruxism were significantly associated with higher TLPD rates. Vertical and circumferential bone defects (p < .0001), and abfractions (p < .0001) were associated with bruxism and particularly with bruxism and TLPD >2. Furcation defects (p = .0002), fewer radio-opaque subgingival calculus (χ² p < .0001), a lower mean Gingival index (χ² p = .027), and increased mean recessions >1.5 mm (χ² p = .0026) were associated with smoking and higher TLPD rates. The mean baseline mobility, abfractions, and recessions characterized two basic types of TLPD.

CONCLUSIONS

Smoking, bruxism, and routine clinical and radiological parameters can be used to characterize the baseline status of patients with worse outcomes.

Abrasion: A Common Dental Problem Revisited

Dental abrasion is most commonly seen at the cervical necks of teeth, but can occur in any area, even inter-dentally from vigorous and incorrect use of dental floss. Acid erosion has been implicated in the initiation and progress of the cervical lesion, while tooth-brush abrasion has long been held as the prime cause of cervical abrasion. Identification of the risk factors is clearly important in order to modify any habits and provide appropriate advice.

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.

Congenitally missing maxillary lateral incisors: update on the functional and esthetic parameters of patients treated with implants or space closure and teeth recontouring

Maxillary lateral incisor agenesis (MLIA) is a condition that affects both dental esthetics and function in young patients, and represents an important challenge for clinicians. Although several treatment options are available, the mesial repositioning of the canines followed by teeth recontouring into lateral incisors; or space opening/maintenance followed by implant placement have recently emerged as two important treatment approaches. In this article, the current and latest literature has been reviewed in order to summarize the functional and esthetic outcomes obtained with these two forms of treatment of MLIA patients in recent years. Indications, clinical limitations and the most important parameters to achieve the best possible results with each treatment modality are also discussed. Within the limitations of this review, it is not possible to assert at this point in time that one treatment approach is more advantageous than the other. Long-term followup studies comparing the existing treatment options are still lacking in the literature, and they are necessary to shed some light on the issue. It is possible, however, to state that adequate multidisciplinary diagnosis and planning are imperative to define the treatment option that will provide the best individual results for patients with MLIA.

Dental wear: a scanning electron microscope study

Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction) studied by scanning electron microscopy (SEM). The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp), to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders). It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction.

Clinical evaluation of the association between noncarious cervical lesions and occlusal forces

STATEMENT OF PROBLEM

Noncarious cervical lesions (NCCLs) are a frequent challenge in clinical dental practice, given the variety of opinions regarding their etiology, diagnosis, and treatment.

PURPOSE

The purpose of this study was to assess the potential relationship between occlusal forces and the occurrence of NCCLs.

MATERIAL AND METHODS

The participant population consisted of 111 volunteers (30 male and 81 female, mean age 23.6 years). General personal information was recorded, after which participants were examined for the presence and location of NCCLs, gingival recession, fracture lines, dental and restoration fractures, presence and location of tooth wear, type of occlusal guidance scheme for lateral mandibular movements, and existence of occlusal interference or premature contacts. The participants were divided according to the presence or absence of NCCLs, and data were statistically analyzed with the Independent t test, the Chi-square test, and the Fisher exact test (α=.05).

RESULTS

A significant association was found between the presence of NCCLs and age (P=.008), gingival recession (P<.001), occlusal trauma (P<.001), presence (P<.001) and location of tooth wear, and group function as occlusal guidance scheme in lateral excursive movements (P<.001).

CONCLUSIONS

A strong relationship between the presence of NCCLs and occlusal overload was found.

Congenitally missing maxillary lateral incisors: functional and periodontal aspects in patients treated with implants or space closure and tooth re-contouring

To evaluate functional and periodontal aspects in patients with unilateral or bilateral congenitally missing maxillary lateral incisors, treated with either implants or space closure and tooth re-contouring. The sample consisted of 68 volunteers, divided into 3 groups: SCR - space closure and tooth re-contouring with composite resin (n = 26); SOI – implants placed in the area of agenesis (n = 20); and CG - control group (n = 22). A modified Helkimo questionnaire and the Research Diagnostic Criteria for Temporomandibular Disorders were used by a single, previously calibrated evaluator to assess signs and symptoms of temporomandibular joint disorder. The periodontal assessment involved the following aspects: plaque index, bleeding upon probing, pocket depth greater than 3 mm, gingival recession, abfraction, periodontal biotype and papilla index. The data were analyzed using Fisher's exact test and the nonparametric Mann-Whitney and Kruskal-Wallis tests (α=.05). No differences in periodontal status were found between treatments. None of the groups were associated with signs and symptoms of temporomandibular joint disorder. Both treatment alternatives for patients with congenitally missing maxillary lateral incisors were satisfactory and achieved functional and periodontal results similar to those of the control group.

Influence of periodontal ligament simulation and splints on strains developing at the cervical area of a tooth crown

Many in vitro tooth models do not incorporate periodontal ligament (PDL) simulation. This study presents the influence of physiologically loaded occlusal splints on cervical strains in a model incorporating roots and PDL. Four sets (N = 10) of occlusal splints differing in material (hard/soft) and location (upper/lower) were prepared for first maxillary and mandibular anatomic molars. Two strain gauges were bonded to the buccal and lingual aspects of the lower molar. Teeth were embedded in acrylic resin with/without a PDL-simulating material. Force vs. strain data were acquired during loading and the maximal strains at 500 N were analyzed. When PDL was incorporated into the model without splints, buccal compressive strains were significantly decreased. Usage of a soft splint resulted in compressive strains on both tooth aspects. Usage of a hard splint on the lower tooth resulted in higher compressive strains on the lingual side compared with the buccal side, whereas usage of this splint on the upper tooth resulted in tensile strains on the lingual side. Bending towards the buccal side occurred when the splints were located on the upper tooth. Soft splints reduce buccal bending, but do not reduce cervical strains. Periodontal ligament stimulation materials should therefore be incorporated in models involving teeth.

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

BACKGROUND

The authors conducted a study to quantify the reasons for restoring noncarious tooth defects (NCTDs) by dentists in The Dental Practice-Based Research Network (DPBRN) and to assess the tooth, patient and dentist characteristics associated with those reasons.

METHODS

Data were collected by 178 DPBRN dentists regarding the placement of 1,301 consecutive restorations owing to NCTDs. Information gathered included the main clinical reason, other than dental caries, for restoration of previously unrestored permanent tooth surfaces; characteristics of patients who received treatment; dentists' and dental practices' characteristics; teeth and surfaces restored; and restorative materials used.

RESULTS

Dentists most often placed restorations to treat lesions caused by abrasion, abfraction or erosion (AAE) (46 percent) and tooth fracture (31 percent). Patients 41 years or older received restorations mainly because of AAE (P < .001). Premolars and anterior teeth were restored mostly owing to AAE; molars were restored mostly owing to tooth fracture (P < .001). Dentists used directly placed resin-based composite (RBC) largely to restore AAE lesions and fractured teeth (P < .001).

CONCLUSIONS

Among DPBRN practices, AAE and tooth fracture were the main reasons for restoring noncarious tooth surfaces. Pre-molars and anterior teeth of patients 41 years and older are most likely to receive restorations owing to AAE; molars are most likely to receive restorations owing to tooth fracture. Dentists restored both types of NCTDs most often with RBC.

Non-carious cervical lesions and occlusion: a systematic review of clinical studies

Non-carious cervical lesions (NCCLs) are a group of lesions that affect the cervical area of the teeth. Different aetiological factors have been reported, among them tooth brushing force, erosive agents and occlusal forces. The aim of this study was to ascertain, by means of a systematic review, the association between NCCLs and occlusion. A search was performed in the MEDLINE database, retrieving a total of 286 articles. After title and abstract screening, the clinical investigations were read in full to select those that evaluated the occlusal aspects of NCCL aetiology. This systematic review describes the results of three prospective and 25 cross-sectional studies. As there is an extreme heterogeneity in design, diagnostic criteria, forms of analysis and associated factors, a meta-analysis was not possible. The wide variety of classification and diagnostic criteria reflects a high range of reported prevalence. An extensive heterogeneity of independent variables was noted, even in occlusal analysis, which helps to mask any conclusion about the role of occlusion in NCCL aetiology. The literature reveals that studies on this topic are subject to a substantial amount of bias, such as evaluation (use of non-blinded examiners) and confounding bias (no control of others aetiological factors). Up to now, it has been impossible to associate NCCLs with any specific causal agent, and the role of occlusion in the pathogenesis of non-carious cervical lesions seems as yet undetermined. Therefore, additional studies, properly designed to diminish bias, are warranted.

Noncarious Cervical Lesions and Their Association With Toothbrushing Practices: In Vivo Evaluation

Knowledge of the characteristics and etiologies of noncarious cervical lesions assists dentists in selecting an appropriate treatment and improving the prognosis.

Incidence of noncarious cervical lesions and their relation to the presence of wear facets

PROBLEM

Noncarious cervical lesions are characterized by loss of tooth structure in the cervical area, compromising its integrity and resulting in esthetic problems for the patient.

PURPOSE

The purpose of this study was to assess noncarious cervical lesions in young patients in an attempt to establish a possible relationship to the presence of wear facets.

MATERIALS AND METHODS

First-year dental students of Bauru Dental School were studied to verify the prevalence of noncarious cervical lesions and their relationship to the presence of wear facets. After 3 years, the students were examined again to verify the incidence of new lesions, trying to establish a correlation to the previous existence of wear facets.

RESULTS

Of the 1,131 teeth analyzed, 129 had noncarious cervical lesions. Twenty-nine of the 40 students had at least one tooth with one lesion. After 3 years, the incidence of new lesions was 57. Mandibular first molars (22.3%), mandibular first premolars (13.2%), mandibular second premolars (13.2%), and maxillary first molars (12.4%) showed the highest prevalence of lesions. On final analysis, 86.8% of all teeth presenting lesions showed wear facets. The identification of new lesions associated with the presence of wear facets identified during the first exam 3 years earlier was statistically significant (p < 0.01).

CONCLUSIONS

The patterns of wear facets found in the study population examined were associated with an increased occurrence of noncarious cervical lesions.

CLINICAL SIGNIFICANCE

Occlusal factors, especially the presence of wear facets, should be considered in the management of noncarious cervical lesions.

In vivo evaluation of noncarious cervical lesions in sleep bruxism subjects

STATEMENT OF PROBLEM

Occlusal load has frequently been suggested to be involved in the development of a noncarious cervical lesion (NCL). However, there is a lack of clinical studies evaluating NCLs and occlusal parameters in sleep bruxism (SB) subjects.

PURPOSE

The purpose of this clinical study was to assess the frequency of NCLs and determine potential occlusal differences between SB subjects and healthy control subjects.

MATERIAL AND METHODS

A total of 91 volunteers, 58 women and 33 men, with a mean (SD) age of 28.37 (4.89) years (range of 20 to 39 years), participated in this investigation. The clinical assessment of SB was based on the criteria of the American Academy of Sleep Medicine. The participants were divided into 2 groups; 58 subjects were assigned to the SB group and 33 subjects to the control group, following a thorough dental examination that was performed by a single trained dentist. Additionally, the following parameters were recorded: mean number of teeth present, existence/absence of NCLs, frequency of NCLs relating to the type of tooth, type of occlusal guidance scheme, existence of a slide from centric occlusion (CO) to maximum intercuspation (MI), length of the slide, and report of tooth hypersensitivity. Group differences were statistically analyzed using chi-square tests for the qualitative variables and Mann-Whitney U tests for the quantitative variables (alpha=.05).

RESULTS

NCLs were significantly more prevalent in SB subjects (39.7%) than in the control subjects (12.1%) (P=.006). In SB subjects, the first premolars were the teeth most affected, and in control subjects, the first molars were most affected. Tooth hypersensitivity was reported in 62.1% of the SB subjects and in 36.4% of the control subjects (P=.018). The evaluation of occlusal guidance schemes revealed no significant difference between the groups. In SB subjects (70.7%), a slide from CO to MI was significantly more prevalent than in control subjects (42.4%) (P=.008). Moreover, SB subjects demonstrated a significantly longer mean (SD) slide of 0.77 (0.69) mm compared to that of control subjects of 0.4 (0.57) mm (P=.008).

CONCLUSIONS

Within the limitations of this study, SB subjects demonstrated significantly more NCLs than the control group; whereas, the type of occlusal guidance scheme seems to be of minor importance in the development of NCLs.

Noncarious cervical lesions in adults: prevalence and occlusal aspects

BACKGROUND

The factors that induce the formation of noncarious lesions are not understood fully, particularly those that are related to occlusal aspects. The authors conducted a study to evaluate the prevalence of noncarious cervical lesions in adults and their association with occlusal aspects.

METHODS

The authors examined 70 people (35 men and 35 women) aged 25 to 45 years to determine the presence and type of noncarious cervical lesions, wear facets, tooth contacts in maximal intercuspal position, and lateral and protrusive movements. The assessment involved a questionnaire and clinical examination.

RESULTS

Among the teeth the authors evaluated, 17.23 percent had cervical lesions, 80.28 percent of which had wear facets (P < .01). The authors found a significant difference between the prevalence of noncarious lesions and the presence of wear facets (P = .0484).

CONCLUSIONS

The authors found that cervical lesions were related significantly to wear facets. These findings strengthen evidence for the role of occlusal forces as an etiologic factor for noncarious lesions.

CLINICAL IMPLICATIONS

The presence of wear facets should be considered in the treatment of noncarious cervical lesions.

Predictors of Non-carious Loss of Cervical Tooth Tissues

In this sample of subjects, age, premolars and the presence of corrosive factors were found to be significantly associated with NLCTT. The long-term success of treating such a lesion is dependent on properly identifying and eliminating the etiologic factors.

Finite element analysis of mechanism of cervical lesion formation in simulated molars during mastication and parafunction

STATEMENT OF PROBLEM

The mechanical theory of cervical lesion formation is popular; however, the mechanism of formation of these lesions is not fully explained.

PURPOSE

The aim of this study was calculation of the stresses and Tsai-Wu strength ratio in the cervical area of the mandibular molar during grinding, clenching, and mastication, as well as theoretical investigation of the mechanism of cervical lesion formation in teeth.

MATERIAL AND METHODS

A 2-dimensional finite element model of the mandibular first molar and crown of the opposing maxillary molar in the frontal section was developed. Computational simulation of mastication of a bolus with high elastic modulus, including grinding and clenching, was performed. Pairs of contact elements were used between the bolus and occlusal surfaces of the teeth. The analysis was nonlinear. During these simulations, the pressure exerted on the occlusal surface and the state of stresses in the mandibular molar were calculated. To evaluate the strength of anisotropic tooth tissues, the Tsai-Wu failure criterion was applied. This criterion considers the difference in strength of materials due to tensile, compressive, and shear stresses.

RESULTS

Significant pressures were exerted on lingual cusps of the mandibular molar model during computer simulations of physiological and pathological load. In enamel elements close to the buccal cemento-enamel junction (CEJ) of the studied tooth, tensile stresses were observed which exceeded the strength of the enamel. In this area, the Tsai-Wu strength ratio reached values higher than 1. According to the Tsai-Wu criterion, these elements were damaged and, thus, were removed from the computer tooth model. During subsequent modeling of the tooth with the initiated cervical lesion, the Tsai-Wu ratio exceeded 1 along the dentino-enamel junction (DEJ), creating an overhang of enamel in the cervical area. Application of minimal horizontal force caused a fracture of this fragile, unsupported enamel fragment.

CONCLUSIONS

Overloading of theoretical teeth by computer simulation resulted in enamel damage at the CEJ and led to initiation of a cervical lesion. Subsequent overloading resulted in enamel destruction along the DEJ. The overhanging enamel fragment may easily be chipped. This process was repeated during subsequent tooth overloading and caused enlarging of the lesion.

In vivo correlation of noncarious cervical lesions and occlusal wear

STATEMENT OF PROBLEM

The etiology of noncarious cervical lesions is not well understood. An understanding of the etiology helps the clinician determine appropriate treatment and management strategies. Purpose This study evaluated the relationship between noncarious cervical lesions and occlusal (or incisal) wear.

MATERIAL AND METHODS

Casts (n = 299) made from dental students were articulated in a semi-adjustable articulator and evaluated. Data included the presence and contour of noncarious cervical lesions (NCLs) and the presence, location, and severity of any occlusal/incisal wear facets. Also included were Angle's classification, occlusal guidance patterns, midline, presence of tori, tooth restoration, reverse articulation (crossbite), open occlusal relationship, and posterior excursive contacts where present. Following a calibration procedure, 2 evaluators made independent observations on the casts. The first evaluator recorded for each tooth in each subject: presence and severity of NCLs, presence and extent of occlusal/proximal restorations, and presence of reverse articulation and open occlusal relationship. Following the first evaluation red rope wax was placed at the cervical margins of each tooth for the purpose of blinding the second evaluator from NCL observations. The second evaluator recorded severity and location of occlusal/incisal wear, presence or absence of posterior excursive contacts, Angle's classification, occlusal guidance pattern, any midline discrepancy, and presence or absence of tori. The Spearman correlation coefficient and chi 2 tests were used to analyze the data (alpha=.05).

RESULTS

There was no relationship between noncarious cervical lesions and occlusal/incisal wear. There was also no correlation between NCLs and other parameters examined.

CONCLUSIONS

Under the conditions of this study, noncarious cervical lesions are not related to occlusal wear.

Abfraction Lesions: Myth or Reality?

Loss of tooth substance in the cervical region is usually attributed to toothbrush abrasion, erosion, or a combination of both factors. Recently the role of occlusal loading has become increasingly prominent. It is suggested that high occlusal loads cause large cervical stress concentrations, resulting in a disruption of the bonds between the hydroxyapatite crystals and the eventual loss of cervical enamel. This process has been called noncarious cervical tooth loss or abfraction. This article reviews the available evidence to support the thesis that occlusal loading can contribute to the process of abfraction. It also reviews the potential interactions between occlusal loading and erosion that may contribute to abfraction lesion formation.

CLINICAL SIGNIFICANCE

It is important to recognize the potential role of occlusal loading in the loss of cervical tooth tissue so that management of the occlusion can be incorporated into a treatment plan for a patient with abfraction lesions.