Development Of Non-carious Cervical Lesions Research Articles

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

It is still discussed whether occlusal wear (OW) affects the formation of non-carious cervical lesions (NCCLs). To estimate effects of OW on the presence and development of NCCLs, using 16-year follow-up data from a cohort study. 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. 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. 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.

The early wear susceptibility of cementum, enamel and dentine in vitro

ObjectivesTo assess the differential early wear susceptibility of cementum, enamel and dentine at a micron level. MethodsWhole human molar buccal surfaces incorporating natural enamel and cementum (n = 20) confirmed by imaging (digital microscopy: Keyence, VHX-7000 Milton Keynes, UK), were mounted, scanned (profilometry: XYRIS 4000, Taicaan, Southampton, UK), and allocated to receive erosion (citric acid, pH 2.7, 30 min (n = 10)) or erosion/abrasion challenges (3 cycles of (citric acid, pH 2.7, 10 min, 60 300 g linear abrasion strokes), n=10). Samples were polished and the experiment repeated on polished enamel, and polished coronal and radicular dentine within the same tooth. Profilometric wear data were obtained using superimposition: GeoMagic (3Dsystems, Darmstadt, Germany) and subtraction: MountainsMap (DigitalSurf, Besancon, France). Data were normal. A general linear model was used to assess differences between groups and substrates. ResultsThe mean step height (SD) for natural enamel was 8.82 μm (2.53) for erosion and 11.48 μm (2.95) for erosion/abrasion. For natural cementum, the mean step height was 6.00 μm (2.29) for erosion and 4.67 μm (1.58) for erosion/abrasion. Dentine step heights ranged from 7.20 μm (1.53) for erosion and 9.79 μm (1.01) for erosion/abrasion with no statistical differences in dentine wear. Natural cementum surfaces had the lowest wear (p<0.001). Dentine had significantly less wear than natural enamel (p<0.02). ConclusionsCementum surfaces demonstrated the most wear resistance, followed by dentine under erosion dominant conditions in this in vitro study. Further in-vivo investigations are needed to confirm the intraoral stability of cementum. Clinical SignificanceCementum may be the least susceptible of dental substrates to wear and dentine does not wear at a faster rate than enamel under erosive conditions. This adds to our knowledge on the development of non-carious cervical lesions and questions whether wear rates will accelerate once dentine is exposed.

Effect of dentifrice slurry abrasivity and erosive challenge on simulated non-carious cervical lesions development in vitro.

To investigate the effect of slurry abrasive levels and acidic challenges on the development of non-carious cervical lesions. Ninety-six extracted upper premolars were affixed in pairs to acrylic blocks and had their root surfaces covered by acrylic resin except for 2 mm from the cemento-enamel junction. The specimens were distributed into six groups (n = 8 pairs) based on two experimental factors: (1) slurry abrasivity level [low/medium/high] and (2) citric acid challenge [yes/no]. Specimens were brushed for 5,000, 15,000, 35,000, and 65,000 strokes. Volume loss (VL) was determined based on optical profilometry scans of specimens impressions at the baseline and at subsequent brushing levels. Data were analyzed using repeated measures analysis of variance and Bonferroni pairwise comparison (α = 0.05). Higher VL values were associated with high-abrasivity slurries relative to low- and medium-abrasivity slurries (P < 0.001). Increasing the slurry abrasivity level increased the VL regardless of the acidic challenge, which did not have a significant effect (P = 0.184). After 65,000 strokes, significant VL was recorded in all groups relative to preceding brushing levels (P < 0.001). Higher values of time-dependent surface loss were associated with increased dentifrice slurry abrasivity, regardless of the citric acid challenge.

Toothbrush bristle configuration and brushing load: Effect on the development of simulated non-carious cervical lesions

ObjectivesThis study investigated the effect of toothbrush bristle configuration and brushing load on the development of non-carious cervical lesions (NCCLs). MethodsHuman premolars were mounted on acrylic blocks and had their root surfaces partially covered with acrylic resin to simulate gingiva, leaving a 2-mm length area apical to the cemento-enamel junction exposed for brushing. The teeth were brushed under 1- or 3 N load with one of the following toothbrushes (n = 16): a) ordinary/flat-trimmed (Oral-B Indicator); b) rippled (Oral-B Contour); c) cross-angled/multileveled/rubber bristles (Oral-B Pro-Health All-in-One); d) cross-angled/multileveled/flex head (Oral-B Pro-Flex); e) feathered (Oral-B Compact Clean). Brushing was performed using toothpaste slurry (Crest Cavity Protection) for 55,000 double-strokes in back-and-forth motion, to simulate 10 years of brushing. Impressions were taken at baseline and after brushing and scanned by a 3D optical profilometer. The lesions formed were evaluated for volume loss, angle, and shape. ResultsThe ordinary/flat-trimmed toothbrush caused significantly higher volume loss (3.81 mm3) in comparison to the other toothbrushes (2.56-2.92 mm3). The toothbrush having rubber bristles was associated with NCCLs showing the smallest angle and, along with the rippled toothbrush (53.1%), provoked higher proportion of wedge-shaped lesions (43.8%), whereas teeth brushed with the feathered toothbrush exhibited the lowest prevalence of wedge-shaped lesions (3.1%). The 1- and 3 N load applied during brushing affected neither volume loss nor lesion angle. ConclusionsAt the brushing loads tested, the development of NCCLs was dependent on toothbrush bristle configuration, with the ordinary/flat-trimmed version causing the highest abrasion and the feathered toothbrush the least proportion of wedge-shaped lesions. Clinical significanceToothbrush bristle arrangement plays a role in NCCL development, with the ordinary/flat-trimmed version being more abrasive and the feathered toothbrush causing less wedge-shaped lesions.

Interplay between toothbrush stiffness and dentifrice abrasivity on the development of non-carious cervical lesions.

This study investigated the effect of toothbrush stiffness and dentifrice slurry abrasivity on the development and progression of simulated non-carious cervical lesions (NCCLs). Human maxillary premolars were allocated to 12 groups generated by the association between toothbrushes, soft, medium, and hard stiffness, and simulated dentifrice slurries, lower, medium, and higher; deionized water (DI) served as negative control. Teeth were mounted on acrylic blocks, and their root surfaces partially covered with acrylic resin to simulate gingiva, leaving a 2-mm area apical to the cemento-enamel junction exposed to toothbrushing. Specimens were brushed with the test slurries for 35,000 and 65,000 double strokes. Impressions taken at baseline and after both brushing periods were scanned by a 3D optical profilometer. Dentin volume loss (mm3) was calculated by image subtraction. Data were analyzed using three-way ANOVA and Fisher's PLSD tests. All toothbrushes caused higher volume loss when associated to higher abrasive slurry, compared to medium- and lower-abrasive slurries. Medium caused more volume loss than lower-abrasive slurry, which led to more volume loss than DI. Hard and medium toothbrushes were not different when used with medium- or higher-abrasive slurries. There were no differences among toothbrushes when used with DI and lower-abrasive slurry. Overall, 35,000 brushing strokes resulted in significantly less volume loss than 65,000. Toothbrush stiffness was an important factor on NCCL development, especially when brushing with medium- and higher-abrasive slurries. Medium and hard toothbrushes associated with medium- and high-abrasive toothpastes can yield more severe NCCLs.

Prevalence and risk factors for non-carious cervical lesions in children attending special needs schools in India.

We assessed the prevalence and risk factors for development of non-carious cervical lesions (NCCLs) in children attending special needs schools in India. The participants were 395 children aged 12-15 years with disabilities in learning, communication, physical function, and/or development. A questionnaire was designed in order to collect information on sociodemographic characteristics, oral hygiene practices, dietary habits, and risk factors for NCCLs. The chi-square test, bivariate analysis, and logistic regression analysis were used to analyze the data. Presence of NCCLs was associated with use of toothpowder or other materials for teeth cleaning, use of harder toothbrushes, use of a horizontal scrub technique for toothbrushing, consumption of a vegetarian diet, and greater consumption of lemon. The overall prevalence of NCCLs was 22.7%. Most lesions involved minimal loss of contour or defects <1 mm in depth. The prevalence of non-carious cervical lesions was slightly higher than the global average. Effective policies should be developed for oral health care among children attending special needs schools.

Stress Analysis of Occlusal Forces in Canine Teeth and Their Role in the Development of Non-Carious Cervical Lesions: Abfraction

Non-carious cervical tooth lesions for many decades were attributed to the effects of abrasion and erosion mainly through toothbrush trauma, abrasive toothpaste, and erosive acids. However, though the above may be involved, more recently a biomechanical theory for the formation of these lesions has arisen, and the term abfraction was coined. The aim of this study was to investigate the biomechanics of abfraction lesions in upper canine teeth under axial and lateral loading conditions using a three-dimensional finite element analysis. An extracted human upper canine tooth was scanned by μCT machine (Skyscan, Belgium). These μCT scans were segmented, reconstructed, and meshed using ScanIP (Simpleware, Exeter, UK) to create a three-dimensional finite element model. A 100 N load was applied axially at the incisal edge and laterally at 45° midpalatally to the long axis of the canine tooth. Separately, 200 N axial and non-axial loads were applied simultaneously to the tooth. It was found that stresses were concentrated at the CEJ in all scenarios. Lateral loading produced maximum stresses greater than axial loading, and pulp tissues, however, experienced minimum levels of stresses. This study has contributed towards the understanding of the aetiology of non-carious cervical lesions which is a key in their clinical management.

In vitro demineralisation of the cervical region of human teeth

ObjectiveThe aim of this study was to investigate a possible role for demineralisation of the cervical region of human teeth in the development of non-carious cervical lesions (NCCLs). Materials and methodsFreshly extracted human premolars were demineralised and prepared for nanoindentation and scanning electron microscope (SEM) observation. After 1 day or 2 days demineralisation in a solution of pH 4.5, specimens were embedded, cut and polished to 1μm diamond paste. Nanoindentation was done at the cementum–enamel junction (CEJ) region with an interval of 30μm, to develop mechanical properties maps. After the indentation, SEM with back-scatter detector was employed to observe the degree of demineralisation at the CEJ. ResultsAfter 1 day and 2 days demineralisation, the mechanical properties of enamel and dentine at the CEJ decreased by ∼50% and ∼90%, respectively. SEM images illustrate that artificial demineralisation generated typical demineralised zones in enamel near the CEJ. Moreover, 2 days demineralisation penetrated the sound enamel at the CEJ, and the dentine beneath was undermined. Conclusion and significanceOne day and 2 days demineralisation reduced the mechanical properties of teeth at the CEJ significantly. Demineralised enamel and dentine with low mechanical properties are prone to wear and abrasion. The findings of the investigation indicate that acid typical of that produced by dental plaque may compromise the mechanical properties of enamel and dentine at the CEJ to the extent that they would be susceptible to tooth brush abrasion, producing NCCLs.

The biomechanics of abfraction

The role of occlusal loading in the development of non-carious cervical lesions is becoming increasingly prominent. It is suggested that high occlusal loads result in large stress concentrations in the cervical region of the teeth. These stresses may be high enough to cause disruption of the bonds between the hydroxyapatite crystals, eventually resulting in the loss of cervical enamel. This article reviews the evidence to support the thesis that occlusal loading can contribute to the process of non-carious cervical tooth loss or abfraction. It also reviews the potential interactions between occlusal loading and erosion that may contribute to non-carious cervical tooth loss.