Epidemiological evaluation of the multifactorial aetiology of abfractions

Is the quality of occlusal contacts comparable after aligner and fixed orthodontic therapy? A non-randomized cohort comparison using computerized occlusal analysis during 6 months of retention

OBJECTIVE

Less than ideal contacts have been reported following aligner therapy, but it is considered a transitory problem, spontaneously resolving with the phenomenon of settling. Methods: Thirty-nine orthodontic patients (14 treated with aligners; 25 with fixed appliances) were evaluated with a digital occlusal analysis system (T-scan™10), assessing Maximum Intercuspation contact simultaneity, symmetry, and relative force distribution at treatment completion and after 3 and 6 months.

RESULTS

No significant differences in occlusal contact quality were found between groups at treatment completion or follow-up. The center of force moved posteriorly and remained stable after 3 months but was located more anteriorly in females (p = 0.01). One-third of patients (both groups combined) had marked contact force asymmetry even after 6 months' retention. Conclusion: Occlusal contacts were comparable at completion of treatment with aligners or brackets and after 3-6 months of retention. Settling did not improve marked asymmetry in all patients.

Effects of occlusal wear on 16-year progression of non-carious cervical lesions-Results of the study of health in Pomerania (SHIP-START)

BACKGROUND

It is still discussed whether occlusal wear (OW) affects the formation of non-carious cervical lesions (NCCLs).

OBJECTIVE

To estimate effects of OW on the presence and development of NCCLs, using 16-year follow-up data from a cohort study.

METHODS

Occlusal and cervical defects were measured in 728 cast models (one from the upper jaw and one from the lower jaw) of 364 participants. Adjusted mixed-effects ordinal logistic models analysing estimated cross-sectional (N = 1308 teeth/291 subjects) and longitudinal (N = 718 teeth/226 subjects) associations of OW with NCCLs using tooth level data.

RESULTS

OW size was cross-sectionally (OR = 1.74; 95% CI: 1.27-2.38 for OW size; OR = 0.97; 95% CI: 0.94-0.99 for squared OW size), but not longitudinally (OR = 1.14; 95% CI: 0.99-1.30) associated with odds of higher NCCL sizes. For cross-sectional analyses, predicted probabilities of an NCCL size of 0 decreased from about 0.996 to 0.010 for OW sizes of 0 to 25.

CONCLUSION

Results suggest an association between OW and NCCL size. However, as longitudinal results were non-significant, while consistent in direction, large-scaled cohort studies are demanded to more precisely estimate effect strength.

A qualitative analysis of dentists' understanding and management of non-carious cervical lesions (NCCL)

INTRODUCTION

Non-carious cervical lesions (NCCLs) are considered to have a multi-factorial aetiology and their management is affected by a range of variables perhaps most importantly clinical judgement. The aim of this study was to elicit information from practicing dentists, using interviews, to explore their understanding of NCCL aetiology, the decision-making criteria of when to restore, and the restorative techniques used to restore NCCLs. This may help identify gaps or anomalies in our understanding to inform future research and clinical practice for the management of NCCLs.

METHODS

An interview guide was developed from a literature search which formed 2 domains framed around understanding and management of NCCLs based on: understanding of diagnosis and aetiology, and factors affecting decision making for management. Practicing dentists with more than 10 years of experience were purposively recruited to conduct in-depth, semi-structured interviews. Fifteen interviews were audio recorded and transcribed verbatim. A thematic content analysis was conducted and the results analysed.

RESULTS

From the thematic analysis, 2 domains were identified. In the domain of "diagnosis and aetiology", while participants have similar understanding and methods of diagnosing NCCL, most stated NCCLs in a patient were caused by a "main aetiology" such as "abrasion", "abfraction" while few described the inter-relationship of these aetiological factors. In the domain of "factors affecting decision making". "Patient reported symptoms" and "lesion dimension" were the main factors that affected participants' decision to provide restorative or non-restorative management. However, a "restorative threshold" was not able to be identified.

CONCLUSION

There was notable variety in participants' understanding of the aetiology, management, and treatment of NCCLs, particularly the restorative threshold of when to treat.

CLINICAL SIGNIFICANCE

The variability demonstrates the need to have a clearer understanding of the key elements that affect the management of NCCLs and better information to support the decision of when to treat.

Stereomicroscopic Aspects of Non-Carious Cervical Lesions

Non-carious cervical lesions (NCCLs) represent a form of tooth wear, characterized by the irreversible loss of dental hard tissues at the enamel-cement junction, without the involvement of caries and dental trauma. The aim of this study was to highlight the morphological elements of NCCLs via their stereomicroscopic examination and to confirm the role of this examination in the diagnosis of early lesions. In addition, the association between the morphological aspects identified during the stereomicroscopic examination of NCCLs and their etiological factors was determined. For this study, extracted teeth with NCCLs were examined with a stereomicroscope. The morphological aspects of NCCLs were evaluated at magnifications up to 75×. In wedge-shaped NCCLs, the stereomicroscopic examination allowed the identification and measurement of scratches, furrows and cracks. In saucer-shaped NCCLs, the stereomicroscopic examination highlighted the smooth appearance of the walls. The presented study highlighted the role of stereomicroscopic examination in the assessment of NCCL morphology and in their early diagnosis. The study confirmed, in particular, the role of occlusal overloads and tooth brushing in determining the morphology of NCCLs.

Conservative Treatment of Dental Non-Carious Cervical Lesions: A Scoping Review

This scoping review aims to evaluate methods of conservative reconstruction of dental enamel lesions resulting from abrasions and evaluate the effect of diode laser in reducing the symptoms of tooth sensitivity. The cementoenamel junction is more prone to substance loss because the enamel thickness is substantially decreased, resulting in a much weaker enamel-dentin bond.

METHODS

Dental abrasion was examined in the mechanical cause alone. Pubmed, Scopus, and Web of Science were used to discover publications that matched our topic from 1 January 2018 to 20 March 2023. A comparison of various non-carious cervical lesion (NCCL) restoration treatments was generated mostly by mechanical considerations.

RESULTS

A final number of 11 clinical trials and randomized controlled trials were included in the review for qualitative analysis. Composite resins performed well in clinical trials for the restoration of NCCLs.

CONCLUSIONS

Composite, in its different forms of filling and consistency, preceded by the use of adhesives, is an efficient and effective material for the treatment of NCCLs. Diode laser use prior to NCCL restoration of teeth does not diminish restoration retention rate, may lessen hypersensitivity, and may affect restoration success.

Fatigue and wear of human tooth enamel: A review

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

Noncarious cervical lesions: Morphology and progression, prevalence, etiology, pathophysiology, and clinical guidelines for restoration

PURPOSE

To synthesize the literature regarding noncarious cervical lesions (NCCLs) and propose clinical guidelines when lesion restoration is indicated.

MATERIAL AND METHODS

A PubMed search was performed related to NCCL morphology, progression, prevalence, etiology, pathophysiology, and restoration.

RESULTS

NCCLs form as either rounded (saucerlike) depressions with smooth, featureless surfaces that progress mainly in height or as V-shaped indentations that increase in both height and depth. Prevalence ranges from less than 10% to over 90% and increases with age. Common locations are the facial surfaces of maxillary premolars. They have a multifactorial etiology due to personal habits such as excessive horizontal toothbrushing and consumption of acidic foods and drinks. Occlusal factors have been identified as contributing to the prevalence of NCCLs in some studies, whereas other studies indicate there is no relationship. The concept of abfraction has been proposed whereby mechanical stress from occlusal loading plays a role in the development and progression of NCCLs with publications supporting the concept and others indicating it lacks the required clinical documentation. Regardless of the development mechanism, demineralization occurs and they are one of the most common demineralization diseases in the body. Treatment should be managed conservatively through preventive intervention with restorative treatment delayed until it becomes necessary due to factors such as lesion progression, impact on patient's quality of life, sensitivity, poor esthetics, and food collection may necessitate restoration. Composite resins are commonly used to restore NCCLs although other materials such as glass ionomer and resin-modified glass ionomer are also used. Sclerotic dentin does not etch like normal dentin and therefore it has been recommended to texture the dentin surface with a fine rotary diamond instrument to improve restoration retention. Some clinicians use mechanical retention to increase retention. Beveling of enamel is used to increase the bonding area and retention as well as enhance the esthetic result by gradually creating a color change between the restoration and tooth. Both multistep and single-step adhesives have been used. Dentin etching should be increased to 30 seconds due to the sclerotic dentin with the adhesive agent applied using a light scrubbing motion for 20 seconds but without excessive force that induces substantial bending of a disposable applicator. Both flowable and sculptable composite resins have been successfully used with some clinicians applying and polymerizing a layer of flowable composite resin and then adding an external layer of sculptable composite resin to provide enhanced resistance to wear. When caries is present, silver diamine fluoride has been used to arrest the caries rather than restore the lesion.

CONCLUSIONS

Noncarious cervical lesions (NCCLs) form as smooth saucerlike depressions or as V-shaped notches. Prevalence values as high as 90% and as low as 10% have been reported due to habits such as excessive toothbrushing and an acidic diet. Occlusal factors have been proposed as contributing to their presence but it remains controversial. Publications have both supported and challenged the concept of abfraction. They are one of the most common demineralization diseases in the body. Conservative treatment through prevention is recommended with restorative treatment delayed as long as possible. When treatment is needed, composite resins are commonly used with proposed restorative guidelines including texturing the sclerotic dentin, beveling the enamel, potential use of mechanical retention, 30 seconds of acid etching, and use of either multistep or single-step adhesives in conjunction with a light scrubbing motion for 20 seconds without excessive force placed on disposable applicators.

Effects of Mandibular Canine Intrusion Obtained Using Cantilever Versus Bone Anchorage: A Comparative Finite Element Study

Background This study was conducted to assess and compare the effects of mandibular canine intrusion obtained using a cantilever having different toe-in bends and with mini-implants using the three-dimensional (3D) finite element method (FEM). Methodology 3D models of the mandibular right quadrant were created using FEM. Brackets and molar tubes were also modeled. In the first model, the mandibular canine intrusion was produced using a cantilever loop with compensatory toe-in bends (0°, 4°, 6°, and 8°). In another model, the intrusion was done using two mini-implants. Force was applied using an elastic chain. The amount of intrusion and the associated labial tipping of canine that occurred in both the models was assessed and compared using FEM analysis. Results The pure intrusion of the canine was produced by the 6° toe-in bend of the cantilever. The labial tipping of the canine was also reduced. The highest amount of periodontal ligament stress was observed around the canine root with a 0° toe-in bend. In the posterior segment, the molar displayed a slight tendency for extrusion and distal crown tipping. Conclusions The intrusion mechanics using a cantilever simulated in this study may achieve pure mandibular canine intrusion with minimal labial tipping when a compensatory toe-in of 6° is incorporated into the cantilever.

The Retention Effect of Resin-Based Desensitizing Agents on Hypersensitivity-A Randomized Controlled Trial

Recently, the development of dental materials has increased the availability of various hyperesthesia desensitizers. However, there are no studies on the duration of retreatment in terms of adherence rates. Thus, the adhesion rates of resin-based desensitizers were investigated. We used a conventional desensitizer and a recently developed desensitizer containing calcium salt of 4-methacryloxyethyl trimellitic acid (C-MET) and 10-methacryloyloxydecyl dihydrogen calcium phosphate (MDCP). These colored agents were applied to the surfaces of premolars and molars, and the area was measured from weekly oral photographs. Areas were statistically analyzed and mean values were calculated using 95% confidence intervals. A p-value of <0.05 was considered statistically significant. These rates were significantly higher on the buccal side of the maxilla and lower on the lingual side of the maxilla. In addition, the desensitizer containing C-MET and MDCP displayed significantly higher adhesion rates. It is suggested that this will require monthly follow-ups and reevaluation because both agents cause less than 10% adherence and there is almost no sealing effect after 4 weeks. In addition, the significantly higher adhesion rate of the desensitizer containing C-MET and MDCP indicated that the novel monomer contributed to the improvement in the adhesion ability.

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.

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.

Prevalence and severity of non-carious cervical lesions and dentin hypersensitivity: association with oral-health related quality of life among Brazilian adults

Objectives

To assess the association between dentin hypersensitivity (DH) (with or without non-carious cervical lesions (NCCL)) and physical and psychosocial oral health impact.

Methods

A cross-sectional population-based study with one-stage random sample of adults living in a Brazilian municipally was conducted between 2018 and 2019. Interviews and oral examinations were performed by calibrated examiners (Kappa ≥0.7). The participant was considered as having physical and psychosocial impact if at least one item of the Oral Health Impact Profile (OHIP-14) was experienced fairly often or very often. NCCL was assessed by the Tooth Wear Index (codes 2 to 4) and DH was evaluated by a tactile test with a probe in the cervical area of teeth. The combination of these clinical variables resulted in categories of the independent variable: without DH or NCCL, NCCL without DH, DH without NCCL, and both DH with NCCL. The covariables were sociodemographic and economic factors, health habits, and oral conditions. Associations were investigated by Poisson Regression models using Direct Acyclic Graph (Stata 17).

Results

Of 197 adults, 59.3% had oral health impact and 31.3% had DH with NCCL. Higher frequency of oral health impact was observed in adults with DH alone. A higher impact on the physical pain dimension of the OHIP-14 was observed in adults with DH and NCCL (PR: 2.46; 95% CI: 1.21–5.00) and with DH alone (PR: 2.03; 95% CI: 1.21–3.41).

Conclusion

NCCL and DH are common conditions in adults and the presence of DH is associated with higher oral health impact. Regardless the presence of NCCL, DH is associated with the physical pain dimension of OHRQoL.

Estimation of stress distribution and risk of failure for maxillary premolar restored by occlusal veneer with different CAD/CAM materials and preparation designs

OBJECTIVES

To compare stress distribution and failure probability in maxillary premolars restored by simple occlusal veneer (SOV) and buccal-occlusal veneer (BOV) with 3 different CAD/CAM materials.

MATERIALS AND METHODS

A maxillary premolar was digitized by a micro-CT scanner. Three-dimensional dynamic scan data were transformed, and finite element models of 2 different models (SOV and BOV restored teeth) were designed. Three different CAD/CAM materials, including lithium disilicate glass ceramic (LD) IPS e.max CAD, polymer-infiltrated ceramic-network (PICN) Vita Enamic, and resin nano-ceramic (RNC) Lava Ultimate, were designated to both veneers. Maximum principle stresses were determined by applying a 300-N axial load to the occlusal surface. Weibull analyses were performed to calculate the failure probability of the models.

RESULTS

LD-restored teeth showed the highest stress in the veneer, lowest stress in substrate teeth, and lowest failure probability for the overall system; RNC-restored teeth showed the lowest stress in the veneer, highest stress in substrate teeth, and highest failure probability. No significant differences were found in the cement layer among the different models. No significant differences of stress and failure probability existed between SOV and BOV preparations.

CONCLUSIONS

CAD/CAM composite resin occlusal veneers bear lower maximum stress than ceramic veneers. Teeth restored by composite veneers are more prone to failure than those restored by ceramic veneers. Additional reduction of the buccal surface did not increase the stress on the occlusal veneer under axial load.

CLINICAL RELEVANCE

Both occlusal veneers could be used under physiological masticatory force. CAD/CAM glass ceramic was safer than composite resins.

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.

Factores de riesgo de la atrición dental severa: un estudio de casos y controles

Objetivo: identificar los factores de riesgo de la atrición dental severa en pacientes que acudieron a instituciones de atención odontológica, públicas y privadas, de la ciudad de Cuenca, Ecuador. Materiales y métodos: fueron analizados 237 pacientes adultos, 79 casos con atrición dental grados 2, 3 y 4, según el índice de Smith y Knight, y 158 controles con atrición grados 0 y 1. Se realizó un examen clínico y fotográfico para determinar la relación entre la atrición dental y factores como edad, sexo, procedencia, número de dientes residuales, pH salival y bruxismo. Resultados: los pacientes mayores de 25 años (OR= 2,47 IC= 1,41 – 4,35 X2= 10,21 p= 0,001), con menos de 20 dientes en boca (OR= 4,95 IC= 1,47 – 16,62 X2= 7,97 p= 0,004) y con bruxismo (OR= 2,64 IC= 1,45 – 4,81 X2= 10,49 p= 0,001) tienen más probabilidades de presentar atrición dental severa. Luego de una regresión logística binaria se confirmó dicha relación: pacientes mayores de 25 años (OR= 2,03 IC= 1,08 – 3,818) con menos de 20 dientes en boca (OR= 3,90 IC= 1,07 – 14,19) y con bruxismo (OR= 3,22 IC= 1,70 – 6,10); sin embargo, se observó una capacidad predictora muy baja de la variables ajustadas según el R–cuadrado de Cox y Snell (0,123) y el R–cuadrado de Nagelkerke (0,172). Conclusiones: edad avanzada, menor cantidad de dientes en boca y bruxismo aumentaron la posibilidad de presentar atrición dental severa en los pacientes analizados. Mientras que el sexo masculino, la procedencia rural y el pH salival crítico (menor a 6) no se comportaron como factores de riesgo

Non-carious cervical lesions and risk factors: A case-control study

OBJECTIVES

To evaluate whether the presence of non-carious cervical lesions (NCCLs) was related to the considered risk factors and to show the corresponding odds ratio in a predictive model.

METHODS

The sample was 280 dentistry students. In an initial clinical examination, 140 cases were selected that presented one or more teeth with non-carious cervical wear. For each case, a similar sex and age control without any tooth with non-carious cervical lesions was selected. An occlusal examination and periodontal probing were performed in all cases and controls by skilled dentists. All the subjects answered a questionnaire referring to factors of brushing, bruxism, preferred chewing side, consumption of extrinsic acids and the presence of intrinsic acids. Data were analysed by means of univariate and multivariate logistic regression.

RESULTS

Of all the study variables, only the protrusion interferences, interferences on the non-working side, the brushing force, CPITN value and the consumption of salads increase the risk of NCCLs in the univariate regression. The best predictive model was formed by the combination of CPITN variables >1, the consumption of acidic salads, self-reported bruxism, brushing force and attrition. However, it only correctly classifies 68.75% of subjects.

CONCLUSIONS

This study supports the multifactorial aetiology of NCCLs, the combination of several factors being necessary to explain their presence. The risk factors that make up the predictive model are not sufficient to explain the appearance of NCCLs. Dentists should take into account all these risk factors in prevention, diagnosis and treatment.

Epidemiological investigation of non-carious cervical lesions and possible etiological factors

Background

Epidemiological studies of non-carious cervical lesions (NCCLs) are being conducted in all geographical regions, which is completely justified, considering the high frequency of these lesions and possible consequences. Data obtained from such studies are of great importance because, beside describing the extent and degree of lesions, they can also point to specific etiological factors. The purpose of this study was to analyze the frequency and distribution of NCCLs among the patients of Faculty of Dentistry in Pancevo, Serbia, and to investigate the impact of certain etiological factors on the frequency of NCCLs.

Material and Methods

The study included 394 patients, who were clinically examined for the presence of NCCLs and interviewed about potential etiological factors using specially designed questionnaire. Saliva samples were analyzed for 30 patients with multiple NCCLs (≥3) and 30 patients without signs of cervical lesions and restorations. Subject – level logistic regression was used to analyze the association of potential etiological factors and presence of NCCLs and Wilcoxon test for the quantity and quality of saliva.

Results

NCCLs were diagnosed at 68.5% from total number of respondents, 15% from all present teeth were affected. The highest prevalence was recorded on premolars. Presence of lesions significantly increased with age. Frequent consumption of citrus fruit was associated with the presence of NCCLs. Significantly lower frequency of NCCLs was recorded among subjects who frequently chew gums. Significantly lower pH values of unstimulated and stimulated saliva were recorded in the group of patients with multiple NCCLs compared to control group.

Conclusions

This study showed high frequency of NCCLs among subjects of different age. Premolars were the most frequently affected. Age, frequent consumption of citrus fruit and lower salivary pH value were associated with an increased occurrence of NCCLs. Chewing gums habit was associated with an decreased occurrence of NCCLs.

Key words:NCCL, abrasion, erosion, abfraction, saliva.

Lesões cervicais não-cariosas de abfração: prevalência e relação com bruxismo do sono

As lesões cervicais não cariosas (LCNCs) são caracterizadas pela perda da estrutura dentária localizada na região próxima a junção cemento-esmalte. O bruxismo do sono é uma parafunção caracterizada pelo contato não-funcional dos dentes durante o sono, manifestada pelo apertar ou ranger dos mesmos. Considerando que uma das possíveis etiologias das LCNCs é a sobrecarga oclusal, torna-se importante a compreensão da relação entre a prevalência destas lesões e os fatores de sobrecarga presentes no meio oral. Objetivo: Avaliar a prevalência de LCNCs do tipo abfração e sua relação com o diagnóstico positivo de bruxismo do sono em uma amostra de pacientes da IMED e CEOM. Metodologia: Este foi um estudo clínico do tipo transversal, onde foi realizada avaliação observacional em uma amostra de 25 pacientes de ambos os sexos, com idade entre 20 e 62 anos. O diagnóstico de bruxismo do sono foi realizado através de um questionário e exame clínico intra-oral. O diagnóstico de abfração foi realizado por meio de exame clínico intra-bucal com auxílio de sonda exploradora e milimetrada. Foram utilizados o teste exato de Fisher e Mann-Whitney para analise estatística (α=0,05). Resultados: a prevalência de lesões de abração na amostra total de dentes foi de 5,64%, sendo significativamente maior em pacientes bruxômas (8,83%) do que em pacientes sem bruxismo (1,38%) (p=0,017). A presença de bruxismo foi associada à presença de abfrações (p=0,012). Conclusão: o diagnóstico positivo do bruxismo do sono é um fator de risco, aumentando consideravelmente a chance de o paciente apresentar LCNCs do tipo abfração.

Effects of non-carious cervical lesion size, occlusal loading and restoration on biomechanical behaviour of premolar teeth

BACKGROUND

Information on fracture biomechanics has implications in materials research and clinical practice. The aim of this study was to analyse the influence of non-carious cervical lesion (NCCL) size, restorative status and direction of occlusal loading on the biomechanical behaviour of mandibular premolars, using finite element analysis (FEA), strain gauge tests and fracture resistance tests.

METHODS

Ten buccal cusps were loaded on the outer and inner slopes to calculate the strain generated cervically. Data were collected for healthy teeth at baseline and progressively at three lesion depths (0.5 mm, 1.0 mm and 1.5 mm), followed by restoration with resin composite. The magnitude and distribution of von Mises stress and maximum principal stress were simulated at all stages using FEA, and fracture strength was also determined (n = 7 per group).

RESULTS

There were significant effects of the lesion size and loading directions on stress, strain and fracture resistance (p < 0.05). Fracture resistance values decreased with increase in lesion size, but returned to baseline with restorations.

CONCLUSIONS

Combined assessment of computer-based and experimental techniques provide an holistic approach to characterize the biomechanical behaviour of teeth with both unrestored and restored NCCLs.

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.

A pilot study to assess the morphology and progression of non-carious cervical lesions

OBJECTIVE

This longitudinal pilot study aimed to morphologically and quantitatively investigate the progress of non-carious cervical lesions (NCCLs) by using swept-source optical coherence tomography (SS-OCT).

METHODS

The samples examined comprised sets of NCCL epoxy resin replicas obtained from 10 lesions in 6 patients who attended annual dental visits over 4 or 5 years. SS-OCT images of the replicas were analyzed in terms of the maximum depth (D_max) and corresponding vertical width (VW) - using an image analyzer to estimate progression of the NCCLs over time.

RESULTS

It was found that differences between wedge- and saucer-shaped lesions were morphologically distinguished well by the OCT images. There were significant differences in dimensions among D_max, VW and horizontal width (HW). HW was the largest and D_max was the smallest. Although no significant differences in absolute values of annual progression rates were found among D_max, VW and HW, the percentage increase in D_max was significantly greater compared to VW and HW. The ratios of D_max to corresponding VW ranged from 0.49 to 1.01 for the wedge-shaped lesions and from 0.13 to 0.44 for saucer-shaped lesions, respectively.

CONCLUSIONS

The dimensional analysis demonstrated notable progression with large variations. The wedge-shaped lesions appeared to show greater D_max values compared to the saucer-shaped lesions.

CLINICAL SIGNIFICANCE

With respect to the depth, the wedge-shaped lesions may progress at a greater rate compared to the saucer-shaped lesions.

Non-carious cervical lesions (NCCLs) in a random sampling community population and the association of NCCLs with occlusive wear

This study investigated the prevalence, risk factors and association of occlusive wear with non-carious cervical lesions (NCCLs) in the general Chinese population. A total of 1320 subjects were recruited, and multistage and random sampling methods of survey spots were performed. All age groups comprised similar numbers of participants and equal numbers of males and females. Each subject completed a structured interview, and all teeth of each subject were examined by a practitioner to determine NCCLs and occlusive wear. Binary logistic regression was conducted by analysing the association of risk factors with the occurrence of NCCLs. Bivariate correlation analysis was performed by determining the association of NCCLs dimension or depth with the range of occlusive wear facets. Clinical assessment showed that the overall prevalence of subjects diagnosed with NCCLs was 63%. The proportion of subjects or teeth with NCCLs significantly increased with age. Pre-molars were the most commonly affected teeth. Single variables and interactive effects of variables associated with the occurrence of NCCLs include the following: age group, intensity of toothbrushing, frequency of fresh fruit consumption and interactive effect between intensity of toothbrushing and frequency of fresh fruit consumption. A weak positive correlation of the grading index was found between NCCLs dimension, size or depth and range of occlusive wear facets. This study reported the higher prevalence of NCCLs in the general Chinese population. Implementation of a combined strategy to reduce risk factors of NCCLs could be more effective than individual techniques; meanwhile, the occurrence of NCCL could be related to the wear degree of occlusive defects in the population studied.

Dentine sensitivity risk factors: A case-control study

Objective:

To identify the clinical and psychological risk factors associated with dentine hypersensitivity (DH) in order to provide an early diagnosis and preventive therapy.

Materials and Methods:

A nested case–control study was design between 2011 and 2012. A total of 61 DH cases and 122 controls participated in this investigation. Cases and controls were matched for sex, group of age and socioeconomic status in a ratio of 1:2. DH to different stimuli such as cold, heat, acid, and sweet was asked in patient interviews, and dental examinations were used to detect DH. Clinical and psychological risk factors such as dental hygiene, periodontal disease, acid diet, alcohol consumption, psychological stress, and psychopathological symptoms were inquired. Psychological stress was measured through the PSS-10 and psychopathological symptoms were evaluated by SCL-90-R in Spanish. Descriptive and univariate binary logistic regression analysis were performed to estimate the association between clinical and psychological risk factors and the presence of DH.

Results:

Toothpaste abrasivity (odds ratio [OR] 1.881, 95% confidence interval [CI] 1.010–3.502, P = 0.045), gingival recession (OR 2.196, 95% CI 1.020–4.728, P = 0.041), and periodontal therapy (OR 5.357, 95% CI 2.051–13.993, P < 0.001) were associated with DH. Subjects with perceived stress (OR 1.211, 95%, CI 0.518–2.833, P = 0.658), obsessive-compulsive (OR 1.266, 95%, CI 0.494–3.240, P = 0.623) and hostility (OR 1.235, 95%, CI 0.507–3.007, P = 0.642) symptoms had a clinical greater odd of DH.

Conclusion:

Oral hygiene products and periodontal conditions are important risk factors for DH. Individuals with perceived stress, obsessive-compulsive, and hostility symptoms may increase a clinical risk for this entity. Targeting to dental counseling focused on oral hygiene products, periodontal therapy and a psychological evaluation may be promising in DH prevention.

Factors influencing the progression of noncarious cervical lesions: A 5-year prospective clinical evaluation

STATEMENT OF PROBLEM

The etiology (chemical, friction, abfraction) of noncarious cervical lesion (NCCL) progression is poorly understood.

PURPOSE

The purpose of this 5-year prospective clinical trial was to measure the relationship between NCCLs and various etiologic factors.

MATERIAL AND METHODS

After review board approval, 29 participants with NCCLs were enrolled. Polyvinyl siloxane impressions were made of each NCCL, and casts were poured at baseline, 1, 2, and 5 years. The casts were scanned with a noncontact profilometer, and 1-, 2-, and 5-year scans were superimposed over baseline scans to measure volumetric change in NCCLs. T-scan and Fujifilm Prescale films were used to record relative and absolute occlusal forces on teeth with NCCLs at the 5-year recall. Participant diet, medical condition, toothbrushing, and adverse oral habit questionnaires were given at the 5-year recall. Occlusal analysis was completed on mounted casts to determine the presence of wear facets and group function. Volumetric lesion progression from 1 to 5 years was correlated to absolute and relative occlusal force using mixed model analysis. The Kruskall-Wallis and Mann-Whitney analyses compared lesion progression with diet, medical condition, toothbrushing, adverse oral habits, wear facets, and group function.

RESULTS

The NCCL progression rate over 5 years was 1.50 ±0.92 mm(3)/yr. The rate of progression of NCCLs was related to mean occlusal stress (P=.011) and relative occlusal force (P=.032) in maximum intercuspation position. No difference was seen in NCCL progression between participants with any other factors.

CONCLUSION

Heavy occlusal forces play a significant role in the progression of NCCLs.

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.

Mandibular canine intrusion with the segmented arch technique: A finite element method study

INTRODUCTION

Mandibular canines are anatomically extruded in approximately half of the patients with a deepbite. Although simultaneous orthodontic intrusion of the 6 mandibular anterior teeth is not recommended, a few studies have evaluated individual canine intrusion. Our objectives were to use the finite element method to simulate the segmented intrusion of mandibular canines with a cantilever and to evaluate the effects of different compensatory buccolingual activations.

METHODS

A finite element study of the right quadrant of the mandibular dental arch together with periodontal structures was modeled using SolidWorks software (Dassault Systèmes Americas, Waltham, Mass). After all bony, dental, and periodontal ligament structures from the second molar to the canine were graphically represented, brackets and molar tubes were modeled. Subsequently, a 0.021 × 0.025-in base wire was modeled with stainless steel properties and inserted into the brackets and tubes of the 4 posterior teeth to simulate an anchorage unit. Finally, a 0.017 × 0.025-in cantilever was modeled with titanium-molybdenum alloy properties and inserted into the first molar auxiliary tube. Discretization and boundary conditions of all anatomic structures tested were determined with HyperMesh software (Altair Engineering, Milwaukee, Wis), and compensatory toe-ins of 0°, 4°, 6°, and 8° were simulated with Abaqus software (Dassault Systèmes Americas).

RESULTS

The 6° toe-in produced pure intrusion of the canine. The highest amounts of periodontal ligament stress in the anchor segment were observed around the first molar roots. This tooth showed a slight tendency for extrusion and distal crown tipping. Moreover, the different compensatory toe-ins tested did not significantly affect the other posterior teeth.

CONCLUSIONS

The segmented mechanics simulated in this study may achieve pure mandibular canine intrusion when an adequate amount of compensatory toe-in (6°) is incorporated into the cantilever to prevent buccal and lingual crown tipping. The effects on the posterior anchorage segment were small and initially concentrated on the first molar.

Bond strength tests of dental adhesive systems and their correlation with clinical results - A meta-analysis

OBJECTIVE

To evaluate the variability of bond strength test results of adhesive systems (AS) and to correlate the results with clinical parameters of clinical studies investigating cervical restorations.

MATERIALS AND METHODS

Regarding the clinical studies, the internal database which had previously been used for a meta-analysis on cervical restorations was updated with clinical studies published between 2008 and 2012 by searching the PubMed and SCOPUS databases. PubMed and the International Association for Dental Research abstracts online were searched for laboratory studies on microtensile, macrotensile and macroshear bond strength tests. The inclusion criteria were (1) dentin, (2) testing of at least four adhesive systems, (3) same diameter of composite and (4) 24h of water storage prior to testing. The clinical outcome variables were retention loss, marginal discoloration, detectable margins, and a clinical index comprising the three parameters by weighing them. Linear mixed models which included a random study effect were calculated for both, the laboratory and the clinical studies. The variability was assessed by calculating a ratio of variances, dividing the variance among the estimated bonding effects obtained in the linear mixed models by the sum of all variance components estimated in these models.

RESULTS

Thirty-two laboratory studies fulfilled the inclusion criteria comprising 183 experiments. Of those, 86 used the microtensile test evaluating 22 adhesive systems (AS). Twenty-seven used the macrotensile test with 17 AS, and 70 used the macroshear test with 24 AS. For 28 AS the results from clinical studies were available. Microtensile and macrotensile (Spearman rho=0.66, p=0.007) were moderately correlated and also microtensile and macroshear (Spearman rho=0.51, p=0.03) but not macroshear and macrotensile (Spearman rho=0.34, p=0.22). The effect of the adhesive system was significant for microtensile and macroshear (p < 0.001) but not for macrotensile. The effect of the adhesive system could explain 36% of the variability of the microtensile test, 27% of the macrotensile and 33% of the macroshear test. For the clinical trials, about 49% of the variability of retained restorations could be explained by the adhesive system. With respect to the correlation between bond strength tests and clinical parameters, only a moderate correlation between micro- and macrotensile test results and marginal discoloration was demonstrated. However, no correlation between these tests and a retention loss or marginal integrity was shown. The correlation improved when more studies were included compared to assessing only one study.

SIGNIFICANCE

The high variability of bond strength test results highlights the need to establish individual acceptance levels for a given test institute. The weak correlation of bond-strength test results with clinical parameters leads to the conclusion that one should not rely solely on bond strength tests to predict the clinical performance of an adhesive system but one should conduct other laboratory tests like tests on the marginal adaptation of fillings in extracted teeth and the retention loss of restorations in non-retentive cavities after artificial aging.

Avaliação de hábitos de higiene bucal, hábitos alimentares e pH salivar em pacientes com ausência e presença de lesões cervicais não cariosas

OBJETIVO: Avaliar hábitos de higiene bucal, hábitos alimentares e pH salivar em pacientes com ausência e presença de lesões cervicais não cariosas. MÉTODO: Por meio de um estudo transversal, foram avaliados 88 pacientes, de ambos os sexos, feminino (63,6%) e masculino (36,4%), entre 18 e 71 anos, nos Serviços de Oclusão das cidades de João Pessoa e Campina Grande. Realizaram-se avaliações clínicas, por um único examinador calibrado, para diagnosticar a presença das lesões, a face, os grupos dentários, os hábitos de abrasão e erosão, e o pH Salivar. Utilizaram-se análises descritivas e não paramétricas (Qui-Quadrado, coeficiente ρ de Spearman e teste U de Mann-Whitney), com 5% de nível de significância e 95% de intervalo de confiança. RESULTADO: Verificou-se a prevalência de 65,90% dos pacientes com lesões e o grupo dos pré-molares foi o mais atingido pelas lesões, que estiveram frequentes na face vestibular e na maxila. O gênero não apresentou associação com a presença das lesões, enquanto que a idade foi estatisticamente significante (p<0,001) para a presença destas. O número e a direção de escovação (Fator Abrasivo) e pH Salivar não demonstraram associação com a presença das lesões, enquanto que a frequência do consumo de refrigerantes, de 1 a 7× semanais, apresentou associação positiva. CONCLUSÃO: Os pacientes com alterações oclusais apresentam um elevado número de lesões cervicais não cariosas e a frequência do consumo de refrigerantes representou associação estatística com a presença de lesões.

A Retrospective Clinical Study of Cervical Restorations: Longevity and Failure-Prognostic Variables

The aim of this retrospective clinical study was to compare the longevity of cervical restorations between resin composite (RC) and glass ionomer (GI) and to investigate variables predictive of their outcome. The clinical performance of the two restorative materials in function was compared using the ratings of the modified United States Public Health Service (USPHS) criteria. A total of 479 cervical restorations were included in the study. Ninety-one already-replaced restorations were reviewed from dental records. The other 388 restorations still in function were evaluated according to the modified USPHS criteria by two investigators. Longevity and prognostic variables were analyzed with the Kaplan-Meier survival analysis and multivariate Cox proportional hazard model. The clinical performances of the two materials were evaluated according to the ratings of the USPHS criteria and compared using the Pearson chi-square test and Fisher exact test. The longevity was not significantly different between RC and GI (median survival time, 10.4 ± 0.7 and 11.5 ± 1.1 years, respectively). The main reasons for failure were loss of retention (82.2%) and secondary caries (17.8%). The longevity of cervical restoration was significantly influenced by tooth group and operator group (Wald test, p&lt;0.05), while material, gender, presence or absence of systemic diseases, arch, and reason for treatment did not affect the longevity. Contrary to the longevity, the clinical performance of RC was superior to GI in the criteria of retention, marginal discoloration, and marginal adaptation, but similar in secondary caries, wear, and postoperative sensitivity.

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.

Epidemiology of dentin hypersensitivity

OBJECTIVE

In contrast to the well-established caries epidemiology, data on dentin hypersensitivity seem to be scarce and contradictory. This review evaluates the available literature on dentin hypersensitivity and assesses its prevalence, distribution, and potential changes.

MATERIALS AND METHODS

The systematic search was performed to identify and select relevant publications with several key words in electronic databases. In addition, the articles' bibliographies were consulted.

RESULTS

Prevalence rates range from 3 to 98 %. This vast range can be explained partly by the differences in the selection criteria for the study sample and also the variety in diagnostic approaches or time frames. Women are slightly more affected than men and an age peak of 30-40 years has been reported. Still, the prevalence of erosions with dentin exposure seems to increase in younger adults, often resulting in hypersensitivity. In older patients, root surfaces are frequently exposed due to periodontal disease which is associated with a high rate of dentin hypersensitivity, especially after periodontal treatment and intensified brushing activity. On the other hand, the number of affected seniors with tooth loss or even edentulism is reduced. About 25-30 % of the adult population report dentin hypersensitivity. Most dentists also consider it to be a relevant problem in their practice, but they request more information on this topic. Maxillary teeth are affected to a higher extent, but the different teeth show very similar rates. Buccal surfaces clearly show the highest prevalence rates.

CONCLUSION

In spite of the advances regarding management of dentin hypersensitivity, it still remains an epidemiologically understudied field.

CLINICAL RELEVANCE

Although great variations have been observed in the prevalence of dentin hypersensitivity, this issue is often observed by dentists and related by patients. However, further studies are necessary to find the cause of this condition and refine its management.

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.

Dental erosion and its growing importance in clinical practice: from past to present

Since the mid-1990s, the focus of studies on tooth wear has steadily shifted from the general condition towards the more specific area of dental erosion; equally, a shift has occurred from studies in adults to those in children and adolescents. During this time, understanding of the condition has increased greatly. This paper attempts to provide a critical overview of the development of this body of knowledge, from earlier perceptions to the present. It is accepted that dental erosion has a multifactorial background, in which individual and lifestyle factors have great significance. Notwithstanding methodological differences across studies, data from many countries confirm that dental erosion is common in children and young people, and that, when present, it progresses rapidly. That the condition, and its ramifications, warrants serious consideration in clinical dentistry, is clear. It is important for the oral healthcare team to be able to recognize its early signs and symptoms and to understand its pathogenesis. Preventive strategies are essential ingredients in the management of patients with dental erosion. When necessary, treatment aimed at correcting or improving its effects might best be of a minimally invasive nature. Still, there remains a need for further research to forge better understanding of the subject.

Cervical wear and occlusal wear from a periodontal perspective

The aim of this study was to investigate whether cervical wear was associated with occlusal wear and clinical periodontal parameters in relatively older adults. A total of 30 patients, with multiple non-carious cervical lesions (NCCLs) and without a disease or condition that could cause heavy tooth wear, were included in the study. The periodontal parameters including plaque index, probing pocket depth, gingival recession (GR) and tooth mobility were obtained from 641 teeth of which 475 (74·1%) displayed NCCLs. The levels of cervical wear and occlusal wear were determined according to a tooth wear index. Premolars were more likely to develop cervical wear than canines, molars and incisors. Cervical wear was significantly associated with less plaque accumulation and the presence of shallow pockets. The teeth with advanced GR and without increased mobility were 2·583 and 1·715 times more likely to develop deeper cervical lesions, respectively. Age and the level of occlusal wear were not linked to the bucco-lingual depth of cervical wear. In conclusion, the significant association of advanced cervical wear with the relatively healthy periodontal status suggested the role of abrasion and its possible combined action with erosion in the aetiology of NCCLs. The rate of GR and the lack of tooth mobility could constitute predisposing factors for the progression of cervical wear because the exposed root surfaces could be more susceptible to abrasion and/or erosion, and the non-mobile teeth resisting strongly against frictional forces, thus abrasive effects, could possibly develop cervical wear.

Characteristics of non-carious cervical lesions--an ex vivo study using micro computed tomography

The aetiology of non-carious cervical lesions (NCCLs) is not well understood and still controversial. The aim of this ex-vivo study was to examine the morphological characteristics of NCCLs for clinical evidence of enamel loss above the cemento-enamel junction (CEJ) as suggested by the abfraction theory. Fifty extracted human teeth with various types of NCCLs were collected and scanned by micro computed tomography. The reconstructed three-dimensional models were evaluated from multiple aspects, including longitudinal cross-section series. The location of internal line angle and proximal exits of the lesions were evaluated in relation to the level of CEJ. The coronal margins of the lesions were inspected for evidence of enamel loss above the CEJ using the bucco-lingual longitudinal sectional images. Coronal margins of the lesions were located along and/or under the CEJ for all of the 50 samples. In most of the lesions, regardless of lesion type, the proximal exits and internal line angles were located below the CEJ. This study did not detect clinical evidence of enamel loss above the occlusal margin of NCCLs as would have been expected according to the general abfraction mechanism.

Rehabilitation of the worn dentition

The purpose of this review was to evaluate the literature on the rehabilitation of tooth wear, with some pertinent historical, epidemiological and aetiological aspects of tooth wear provided as background information. In historical skull material, extensive tooth wear, assumed to be the result of coarser diets, was found even in relatively young individuals. Such wear is seldom seen in current populations. Although many of the factors associated with extensive tooth wear in historical material are no longer present or prevalent, new risk factors have emerged. In the young individual, the literature points to a global rise in soft drink consumption as the most significant factor in the development of tooth wear through dental erosion. Among older individuals, lifestyle changes and chronic diseases that are controlled with medications that may, in turn, result in regurgitation and/or dry mouth, are possible reasons amongst others for the widespread clinical impression of an increasing prevalence of tooth wear. The aetiology of tooth wear is multifactorial and the role of bruxism is not known. Clinical controlled trials of restorative and prosthodontic approaches for the range of clinical conditions that wear can give rise to, are limited in number and quality. Equally, the striking lack of evidence regarding the long-term outcomes of treatment methods and materials calls for caution in clinical decision-making. Notwithstanding these observations, clinicians have provided and continue to provide rehabilitative strategies for managing their patients' worn dentitions that range traditionally from extensive prosthodontics to an increasing reliance on adhesive techniques.

Tooth brushing habits in uninstructed adults--frequency, technique, duration and force

Professional recommendations for individual oral hygiene mostly include tooth brushing at least twice daily for 2-3 min with gentle force using the Bass technique or modifications of it. This study evaluated whether habitual tooth brushing actually meets these standards. Uninstructed adults (n = 103; mean age 31 +/- 6 years; 61 female, 42 male) with habitual manual tooth brushing were given a self-administered questionnaire about the frequency of brushing and a computer system recorded their brushing technique, duration and force. The majority (79.6%) of participants brushed twice daily. The mean brushing duration was 96.6 +/- 36.0 s, the mean brushing force was 2.3 +/- 0.7 N (max. 4.1 N), and no significant differences were found for quadrants. Most subjects (73.8%) brushed with circling, 8.7% with horizontal/scrubbing, 13.6% with horizontal/circling and 3.9% with vertical/sweeping movements. Modified Bass technique was not observed. When appropriate brushing habits were defined as brushing at least twice daily for 120 s with a brushing force of less than 3 N and with circling or vertical sweeping movements, only 25.2% of the participants fulfilled all criteria, emphasising the ongoing need for oral hygiene education.

The prevalence and severity of non-carious cervical lesions in a group of patients attending a university hospital in Trinidad

Non-carious cervical lesions (NCCLs) are often encountered in clinical practice and their aetiology attributed to toothbrush abrasion, erosion and tooth flexure. This paper aims to determine the prevalence and severity of NCCLs in a sample of patients attending a university clinic in Trinidad and to investigate the relationship with medical and dental histories, oral hygiene practices, dietary habits and occlusion. Data were collected via a questionnaire and clinical examination. Odds ratios were used to determine the association of the presence of lesions and the factors examined. One hundred and fifty-six patients with a mean age of 40.6 years were examined of whom 62.2% had one or more NCCLs. Forty five per cent of the lesions were sensitive to compressed air. Younger age groups had a significantly lower correlation with the presence of NCCLs than older age groups. Other significant factors included patients who reported heartburn, gastric reflux, headaches, bruxism, sensitive teeth and swimming or had a history of broken restorations in the last year. There was also significant correlation of NCCLs in patients who brushed more than once a day or used a medium or hard toothbrush. Patients with vegetarian diets and those who reported consuming citrus fruits, soft drinks, alcohol, yoghurt and vitamin C drinks were associated with the presence of lesions. Significant associations were also found in patients with group function, faceting, clicking joints or those who wore occlusal splints.

A qualitative assessment of non-carious cervical lesions in extracted human teeth

BACKGROUND

Opinions vary about the causes of non-carious cervical lesions (NCCLs). They have been attributed to toothbrush abrasion, acid corrosion (commonly termed dental erosion), and abfraction. The purpose of this study was to examine the microwear details of NCCLs in a collection of extracted human teeth using scanning election microscopy (SEM).

METHODS

Negative replicas of large NCCLs in 24 extracted human teeth were obtained in polyvinylsiloxane impression material (Light Body Imprint II, 3M ESPE) and viewed under SEM.

RESULTS

All NCCLs extended from the cemento-enamel junction to the root surface and they displayed a variety of wedge-shaped appearances. There was evidence of both abrasion and corrosion in 18 of the 24 teeth (75.0 per cent), abrasion only in one tooth (4.2 per cent) and corrosion only in five teeth (20.8 per cent). Horizontal furrows with smooth edges and minor scratch marks, characteristic of abrasion and corrosion, were noted in 13 teeth (54.2 per cent).

CONCLUSIONS

Based on microscopic assessment of a sample of extracted teeth, it appears that abrasion and corrosion are common associated aetiological factors in the formation of NCCLs.