A Brief History of Tooth Wear.

Historical publications that have significantly improved the understanding of tooth wear mechanisms are reviewed with a focus on descriptions of the lesions, the evolution of their classification systems, and considerations addressing the main risk factors. Surprisingly, most important advances are often the oldest. Likewise, they are currently only marginally known, which requires a major dissemination effort.

An improved method for measuring molar wear.

OBJECTIVES: Standard methods of recording occlusal dental wear are problematic in that they either do not allow for individual variation of wear or are not designed to allow for comparisons of wear patterns. In this article, we (a) present a novel method for recording and analyzing molar wear, and (b) evaluate this method in light of existing methods. MATERIALS AND METHODS: Eighty-two lower mandibular first molars from two regions (medieval Denmark, prehistoric Ohio Valley) were used to assess the method for replicability (intra and inter observer error) and accuracy (comparison to established methods of recording wear). Wear scores were recorded using the MolWear Android App (Beta) by both authors, and established methods of Smith and Scott by the first author. Intraobserver and interobserver error and comparison of the three methods were compared using Spearman's correlation coefficients. RESULTS: The MolWear method presented high intraobserver (r = 0.985, p < 0.01) and interobserver (r = 0.978, p < 0.01) repeatability. Compared to other methods, the method was strongly correlated with Smith (r = 0.962, p < 0.01) and Smith (r = 0.891, p < 0.01). DISCUSSION: The new MolWear method provides an improved way of measuring occlusal molar wear. This method bridges the gaps between established methods, performing comparatively while capturing more information about the distribution of wear in addition to the extent of wear. This method should be used for research comparing interpopulation or intrapopulation quantity of dental wear. While designed for a bioarchaeological population, this method could extend to any Y5 molar including nonhuman primates and hominins.

Oral pathological conditions of an Early Epipaleolithic human from Southwest Asia: Ohalo II H2 as a probable case of intentional dental ablation.

OBJECTIVE: To describe the oral pathological conditions of Ohalo II H2, an Early Epipaleolithic human from southwest Asia. MATERIALS: The dentognathic skeleton of Ohalo II H2 and relevant comparative data from similar chronological and/or geographic contexts. METHODS: Gross and x-ray observations of oral pathological conditions and occlusal wear were made following published protocols. A differential diagnosis of antemortem tooth loss is provided. RESULTS: Ohalo 2 has two carious lesions on the right M3, pulpal exposure of left M1, and mild to moderate anterior alveolar bone loss. The right I1 was lost antemortem, and there is probably agenesis of the left M3. CONCLUSIONS: The pathological conditions noted are not exceptional for a Late Upper Paleolithic forager. However, the antemortem missing right I1 is most parsimoniously explained by intentional dental ablation. SIGNIFICANCE: Ohalo 2 could represent the oldest example of dental ablation from the Late Pleistocene circum-Mediterranean world - predating the earliest examples from both North Africa and southwest Asia by several thousand years. The similarity of the Ohalo 2 ablation pattern with later Natufians provides further evidence of potential long-term behavioral trends related to the embodiment of social identities through international body modification within the Epipaleolithic of southwest Asia. LIMITATIONS: The pre-Natufian (∼23,000-14,500 cal BP) human fossil record is relatively sparse, making comparisons with the Natufian (∼14,500-11,500 cal BP) phases of the Epipaleolithic difficult. SUGGESTIONS FOR FURTHER RESEARCH: Documentation of oral pathological conditions for other pre-Natufian fossils would provide greater resolution of the temporospatial patterning of oral health and embodied social identities during the Epipaleolithic of southwest Asia.

Complementary approaches to tooth wear analysis in Tritylodontidae (Synapsida, Mammaliamorpha) reveal a generalist diet.

Stereoscopic microwear and 3D surface texture analyses on the cheek teeth of ten Upper Triassic to Lower Cretaceous tritylodontid (Mammaliamorpha) taxa of small/medium to large body size suggest that all were generalist feeders and none was a dietary specialist adapted to herbivory. There was no correspondence between body size and food choice. Stereomicroscopic microwear analysis revealed predominantly fine wear features with numerous small pits and less abundant fine scratches as principal components. Almost all analyzed facets bear some coarser microwear features, such as coarse scratches, large pits, puncture pits and gouges pointing to episodic feeding on harder food items or exogenous effects (contamination of food with soil grit and/or dust), or both. 3D surface texture analysis indicates predominantly fine features with large void volume, low peak densities, and various stages of roundness of the peaks. We interpret these features to indicate consumption of food items with low to moderate intrinsic abrasiveness and can exclude regular rooting, digging or caching behavior. Possible food items include plant vegetative parts, plant reproductive structures (seeds and seed-bearing organs), and invertebrates (i.e., insects). Although the tritylodontid tooth morphology and auto-occlusion suggest plants as the primary food resource, our results imply a wider dietary range including animal matter.

Evaluation of tooth wear by estimating enamel thickness with quantitative light-induced fluorescence technology.

BACKGROUND: Various techniques have been suggested to quantitatively assess tooth wear; most have limited clinical application. The first aim of this in vitro study was to estimate the residual enamel thickness of teeth with various degrees of occlusal wear using quantitative light-induced fluorescence (QLF). The second aim was to identify relationships between the fluorescence parameters of QLF and the conventional tooth wear index (TWI) system. METHODS: Sixty-nine extracted permanent premolars and molars with initial stages of tooth wear (TWI score 1a-2: enamel wear to dentin exposure) were used. Two blinded and trained examiners participated in evaluation procedures. Occlusal QLF-digital (QLF-D) images were acquired for selecting area of interest (AOI) and calculating fluorescence for occlusal tooth wear (ΔFwear) of the AOI by the first examiner. Each specimen was cross-sectioned in the buccal-lingual direction. Enamel thickness from images obtained by stereomicroscopy and TWI of each sample was determined by the second examiner. Spearman correlation was used to determine the relationship of ΔFwear with enamel thickness and TWI. ΔFwear values were compared between histological scores with the Mann-Whitney U test. RESULTS: Seventy-six AOIs were analyzed. As enamel thickness decreased, ΔFwear values significantly increased and strongly correlated with enamel thickness (Spearman rho = -0.825, P < 0.001). There were significant differences in ΔFwear values among TWI scores (P < 0.001); ΔFwear strongly correlated with TWI (Spearman rho = 0.753, P < 0.001). CONCLUSIONS: ΔFwear values, which denote fluorescence difference by using QLF, showed a strong correlation with residual enamel thickness and tooth wear severity.

Oral findings in children and adolescents with Prader-Willi syndrome.

OBJECTIVE: To assess the significance of changes in the saliva in the etiology of gingivitis and tooth wear in children and adolescents with Prader-Willi syndrome (PWS). MATERIALS AND METHODS: The study included 80 (2.8-18 years old; 39 girls and 41 boys): 40 in PWS group (mean age 8.0 ± 4.24 years) and 40 in control group (mean age 7.9 ± 4.12 years). General condition, oral para-functional habits, tooth wear (modified TWI), oral hygiene and gingival status (Plaque Index (PLI) and Gingival Index (GI)), localization of gingivitis, and salivary characteristics were assessed. The chi-square test, the Mann-Whitney U test, Spearman's rank correlation, and odds ratio based on logistic regression in a statistical analysis were applied. RESULTS: Chances of gingivitis were increased by low PLI (odds ratio (OR) = 32.53), low resting salivary flow (OR = 3.96), increased viscosity of saliva (OR = 3.54), and mouth breathing (OR = 8.17). For gingivitis in anterior regions, low PLI (OR = 107.67), low resting (OR = 5.73) and stimulated (OR = 1.86) salivary flow, increased viscosity of saliva (OR = 5.87), mouth breathing (OR = 10.00), and low stimulated salivary flow (OR = 3.18) were observed. Tooth wear rates were increased by teeth grinding (OR = 16.20), mouth breathing (OR = 4.33), increased viscosity of saliva (OR = 11.67) and low resting (OR = 6.07), and stimulated (OR = 4.22) salivary flow. CONCLUSIONS: In PWS, reduced salivary secretion, increased viscosity, of saliva and mouth breathing increase the risk of plaque-induced gingivitis and tooth wear. CLINICAL RELEVANCE: The prevention and treatment of tooth wear and gingivitis in PWS patients is necessary not only to treat bruxism and mouth breathing but also to limit the influence of negative changes of saliva.

Diagnoses and Treatment of Dental Disorders in a Research Colony of Macaca fascicularis: A Case Series.

During daily routine oral examinations in a research colony of nonhuman primates (NHPs, Macaca fascicularis), a variety of oral-dental lesions were identified. A dental care program was established based on these findings. Based on the presence of dental clinical signs and their severity, 31 animals were triaged to be examined and treated by a veterinarian. Clinical examination consisted of visual inspection using a periodontal probe/explorer and full or partial mouth dental radiographs. Treatment was performed during the same procedure. Some animals had a follow-up examination including radiographs months later. Four common dental diseases were diagnosed: periodontal disease, caries, tooth fracture, and tooth attrition. Less frequent were dental abscess, enamel hypomineralization, gingival hyperplasia, hypercementosis, tooth luxation, tooth dysplasia, root resorption, abrasion. Less severe periodontal disease was treated conservatively. If severely affected, teeth were extracted. Well-circumscribed caries without endodontic involvement were treated by composite restoration. Teeth with extensive caries and pulp involvement were extracted. Teeth with exposed pulp were treated via extraction or orthograde root canal treatment. In this case series, 27 (87%) of 31 NHPs exhibited at least 1 moderate to severe dental lesion that required treatment. The presumable improvement in welfare and weight of oral/dental lesions for the overall health status in research NHPs encourages us to continue this program prospectively.

Non-carious cervical lesions imaged by focus variation microscopy.

OBJECTIVE: The aim of this study is to characterize the morphological and histological features of NCCLs in a group of extracted teeth using a focus variation optical microscopic technique that is capable of detecting minute variation in surface topography. METHODS: Twenty three extracted teeth containing NCCLs were collected. Histological features of the surface and longitudinal cross sections were examined using a focus variation microscope (FVM). RESULTS: The sample included 8 teeth with wedge-shaped lesions; the remaining 15 contained saucer-shaped lesions. Wedge-shaped lesions showed obliterated dentinal tubules, parallel furrows and micro-fractures in the surface; longitudinal cross sections revealed subsurface micro-fractures extending toward the pulp chamber. The surfaces of typical saucer-shaped lesions were smooth and relatively featureless. CONCLUSIONS: FVM imaging shows microstructures that are consistent with simultaneous erosion and toothbrush abrasion. Saucer shaped lesions have a smooth featureless surface as well as craters and dimples that could be attributed to uneven acid attack. In wedge-shaped lesions, the presence of scratches and furrows could be attributed to mechanical forces such as tooth brush abrasion. The furrows and in-surface micro-factures of wedge shaped lesions suggest a possible role of tensile stresses but require further investigation. CLINICAL SIGNIFICANCE: NCCLs present in two morphologies, either saucer-shaped or wedge-shaped. Erosion and toothbrush abrasion are important in both types of lesions. Tensile stresses due to occlusal loading may be important in some wedge-shaped lesions. Knowing the etiology of cervical lesions is the key for their prevention.

Surface-Sensitive Microwear Texture Analysis of Attrition and Erosion.

Scale-sensitive fractal analysis of high-resolution 3-dimensional surface reconstructions of wear patterns has advanced our knowledge in evolutionary biology, and has opened up opportunities for translatory applications in clinical practice. To elucidate the microwear characteristics of attrition and erosion in worn natural teeth, we scanned 50 extracted human teeth using a confocal profiler at a high optical resolution (X-Y, 0.17 µm; Z < 3 nm). Our hypothesis was that microwear complexity would be greater in erosion and that anisotropy would be greater in attrition. The teeth were divided into 4 groups, including 2 wear types (attrition and erosion) and 2 locations (anterior and posterior teeth; n = 12 for each anterior group, n = 13 for each posterior group) for 2 tissue types (enamel and dentine). The raw 3-dimensional data cloud was subjected to a newly developed rigorous standardization technique to reduce interscanner variability as well as to filter anomalous scanning data. Linear mixed effects (regression) analyses conducted separately for the dependent variables, complexity and anisotropy, showed the following effects of the independent variables: significant interactions between wear type and tissue type ( P = 0.0157 and P = 0.0003, respectively) and significant effects of location ( P < 0.0001 and P = 0.0035, respectively). There were significant associations between complexity and anisotropy when the dependent variable was either complexity ( P = 0.0003) or anisotropy ( P = 0.0014). Our findings of greater complexity in erosion and greater anisotropy in attrition confirm our hypothesis. The greatest geometric means were noted in dentine erosion for complexity and dentine attrition for anisotropy. Dentine also exhibited microwear characteristics that were more consistent with wear types than enamel. Overall, our findings could complement macrowear assessment in dental clinical practice and research and could assist in the early detection and management of pathologic tooth wear.

A Proposed Methodology to Assess the Accuracy of 3D Scanners and Casts and Monitor Tooth Wear Progression in Patients.

PURPOSE: The aim of this study was to detail and assess the capability of a novel methodology to 3D-quantify tooth wear progression in a patient over a period of 12 months. MATERIALS AND METHODS: A calibrated stainless steel model was used to identify the accuracy of the scanning system by assessing the accuracy and precision of the contact scanner and the dimensional accuracy and stability of casts fabricated from three different types of impression materials. Thereafter, the overall accuracy of the 3D scanning system (scanner and casts) was ascertained. Clinically, polyether impressions were made of the patient's dentition at the initial examination and at the 12-month review, then poured in type IV dental stone to assess the tooth wear. The anterior teeth on the resultant casts were scanned, and images were analyzed using 3D matching software to detect dimensional variations between the patient's impressions. RESULTS: The accuracy of the 3D scanning system was established to be 33 µm. 3D clinical analysis demonstrated localized wear on the incisal and palatal surfaces of the patient's maxillary central incisors. The identified wear extended to a depth of 500 µm with a distribution of 4% to 7% of affected tooth surfaces. CONCLUSION: The newly developed 3D scanning methodology was found to be capable of assessing and accounting for the various factors affecting tooth wear scanning. Initial clinical evaluation of the methodology demonstrates successful monitoring of tooth wear progression. However, further clinical assessment is needed.

Assessment of the amount of tooth wear on dental casts and intra-oral photographs.

Tooth wear is a multifactorial condition, leading to the loss of dental hard tissues. Many grading scales are available to assess the amount of tooth wear, one of which is the tooth wear evaluation system (TWES). A grading scale can be used chairside, on casts and on photographs. The aim was to test whether the grading scales of the TWES, used on casts and on photographs, resulted in comparable scores. In addition, it was tested whether these scales can be used to assess tooth wear reliably on photographs. Of 75 tooth wear patients, sets of casts and series of photographs were obtained and graded. Comparison of the grading on casts and on photographs revealed equal median values and percentiles for both occlusal/incisal grading and non-occlusal/non-incisal grading. The grading on casts and on photographs showed a high correlation for the occlusal/incisal grading and a low correlation for the non-occlusal/non-incisal grading (Spearman's rho = 0·74 and rho = 0·47; P < 0·001). Concerning the grading on photographs, the interexaminer reliability was fair-to-good (ICC = 0·41 to ICC = 0·55) while the intra-examiner reliability was fair-to-good to excellent (ICC = 0·68 to ICC = 0·86) for the occlusal/incisal grading. For the non-occlusal/non-incisal grading, the interexaminer reliability was poor to fair-to-good (ICC = 0·22 to ICC = 0·59), while the intra-examiner reliability was fair-to-good to excellent (ICC = 0·64 to ICC = 0·82). It was concluded that the scores obtained with the grading scales of the TWES on casts and on photographs are comparable. The grading scales can be used in a reliable way on photographs, which is especially the case for occlusal/incisal grading.

The tooth wear evaluation system: a modular clinical guideline for the diagnosis and management planning of worn dentitions.

Tooth wear is a multifactorial condition, leading to the loss of dental hard tissues, viz. enamel and dentine. Tooth wear can be divided into the subtypes mechanical wear (attrition and abrasion) and chemical wear (erosion). Because of its multifactorial aetiology, tooth wear can manifest itself in many different representations, and therefore, it can be difficult to diagnose and manage the condition. A systematic approach is a sine qua non. In the below-described tooth wear evaluation system (TWES), all necessary tools for a clinical guideline are present in different modules. This allows the dental clinician, in a general practitioner setting as well as in a referral practice setting, to perform a state-of-the-art diagnostic process. To avoid the risk of a too cumbersome usage, the dental clinician can select only those modules that are appropriate for a given setting. The modules match with each other, which is indispensable and essential when different modules of the TWES are compared. With the TWES, it is possible to recognise the problem (qualifying), to grade its severity (quantifying), to diagnose the likely causes and to monitor (the progress of) the condition. In addition, a proposal for the classification of tooth wear is made. Further, it is possible to determine when to start a treatment, to make the decision which kind of treatment to apply and to estimate the level of difficulty of a restorative treatment.

Sleep bruxism in individuals with and without attrition-type tooth wear: An exploratory matched case-control electromyographic study.

OBJECTIVES: To examine if there is a difference in possible sleep bruxism activity (SB) in subjects with or without attrition-type tooth wear. METHODS: Sixteen individuals with pronounced attritional-type tooth wear were compared with sex and aged matched controls without tooth wear by means of measurement of electromyographic (EMG) activity during a minimum of four consecutive nights of sleep. Mean age and range for the study- and control- group was 23.7 years (range 19.9-28.5) and 23.6 years (range 20.3-27.9), respectively. There were 11 females and five males in each of the two groups. The attrition group presented incisal/occlusal attrition wear into dentin and matching wear facets between opposing anterior teeth. The controls had negligible signs of incisal/occlusal wear and a minimal number of matching wear facets. RESULTS: The prevalence of both self-reported and partner-reported SB was significantly more common in the attrition group compared to the controls (P=0.04 and P=0.007, respectively). Self-reported morning facial pain was similarly more common in the attrition group (P=0.014). Maximum opening capacity, number of muscles painful to palpation, salivary flow rate and buffering capacity were not significantly different between the groups. Interestingly, none of the measures of jaw muscle EMG activity during sleep, as recorded by the portable EMG equipment, differed significantly between the attrition group and the matched controls (P>0.05). CONCLUSIONS: The results from this exploratory study suggest that there is no difference in EMG activity between subjects with and without attrition-type tooth wear. Further research is needed in order to substantiate these preliminary findings.

Wear Fast, Die Young: More Worn Teeth and Shorter Lives in Iberian Compared to Scottish Red Deer.

Teeth in Cervidae are permanent structures that are not replaceable or repairable; consequently their rate of wear, due to the grinding effect of food and dental attrition, affects their duration and can determine an animal's lifespan. Tooth wear is also a useful indicator of accumulative life energy investment in intake and mastication and their interactions with diet. Little is known regarding how natural and sexual selection operate on dental structures within a species in contrasting environments and how these relate to life history traits to explain differences in population rates of tooth wear and longevity. We hypothesised that populations under harsh environmental conditions should be selected for more hypsodont teeth while sexual selection may maintain similar sex differences within different populations. We investigated the patterns of tooth wear in males and females of Iberian red deer (Cervus elaphus hispanicus) in Southern Spain and Scottish red deer (C. e. scoticus) across Scotland, that occur in very different environments, using 10343 samples from legal hunting activities. We found higher rates of both incisor and molar wear in the Spanish compared to Scottish populations. However, Scottish red deer had larger incisors at emergence than Iberian red deer, whilst molars emerged at a similar size in both populations and sexes. Iberian and Scottish males had earlier tooth depletion than females, in support of a similar sexual selection process in both populations. However, whilst average lifespan for Iberian males was 4 years shorter than that for Iberian females and Scottish males, Scottish males only showed a reduction of 1 year in average lifespan with respect to Scottish females. More worn molars were associated with larger mandibles in both populations, suggesting that higher intake and/or greater investment in food comminution may have favoured increased body growth, before later loss of tooth efficiency due to severe wear. These results illustrate how independent selection in both subspecies, that diverged 11,700 years BP, has resulted in the evolution of different longevity, although sexual selection has maintained a similar pattern of relative sex differences in tooth depletion. This study opens interesting questions on optimal allocation in life history trade-offs and the independent evolution of allopatric populations.

Rate and pattern of interproximal dental attrition.

Although occlusal and interproximal attrition occur because of diverse etiology and present dissimilar features, both progress with age. The objectives of this study were to reveal the rate and pattern of development of interproximal attrition facets (PAF) with age and to compare those with occlusal attrition (OA) changes. Five-hundred and ninety-four teeth were collected from 198 skulls (of adults, 20-71 yr of age). Three mandibular teeth [first premolar (P1), second premolar (P2), and first molar (M1)] were examined for PAF size and OA rate. Interproximal attrition and OA followed similar patterns of development until subjects reached 40-45 yr of age, after which they took different paths: PAF did not increase in size and were not as large as in younger groups, regardless of facet location, whereas OA continued to progress. The PAF changes with age differed between premolars and molars, unlike OA, which presented a similar rate for all teeth studied. Although OA scores presented significantly moderate correlations with age, PAF area size demonstrated low correlations with age. Low, but significant, correlations were found between the rate of OA and that of PAF. However, PAF and OA exhibited different patterns of development with age. Premolars and molars presented dissimilar development of PAF, which is probably caused by a unique attrition pattern in the molar teeth, different morphology, and force vectors.

Dental wear patterns in early modern humans from Skhul and Qafzeh: A response to Sarig and Tillier.

The use of teeth as tools for manipulating objects and simple food-processing methods was common among prehistoric and modern hunter-gatherer human populations. Paramasticatory uses of teeth frequently produce enamel chipping and distinctive types of dental wear that can readily be related to specific tool functions. In particular, the presence of unusual occlusal wear areas (named para-facets) on maxillary teeth of prehistoric, historic and modern hunter-gatherers has been associated with cultural habits involving extensive use of teeth (Fiorenza et al., 2011; Fiorenza and Kullmer, 2013). However, Sarig and Tillier (2014) believe that this wear had been caused by pathological occlusal relationships rather than by the use of teeth as tools. In this contribution, we show how occlusal contacts are created and how it is possible to distinguish between masticatory and non-masticatory wear facets by using an innovative digital approach called Occlusal Fingerprint Analysis. Statistical results from the analysis of comparative modern samples clearly demonstrate that described para-facets in Skhul and Qafzeh could not have been produced by dental occlusal anomalies such as malocclusions and crossbites. Moreover, dental pathologies in prehistoric humans were extremely rare. Only with the adoption of the modern lifestyle between 18th and 19th centuries, did the emergence of malocclusions become significantly more common. Because more than 50% of the Skhul and Qafzeh individuals analysed in our study are characterised by this distinctive type of wear, it is highly unlikely that their para-facets occurred as a result of dental pathologies.

Occlusal wear and occlusal condition in a convenience sample of young adults.

OBJECTIVE: To study progression of tooth wear quantitatively in a convenient sample of young adults and to assess possible correlations with occlusal conditions. METHODS: Twenty-eight dental students participated in a three-year follow up study on tooth wear. Visible wear facets on full arch gypsum casts were assessed using a flatbed scanner and measuring software. Regression analyses were used to assess possible associations between the registered occlusal conditions 'occlusal guidance scheme', 'vertical overbite', 'horizontal overbite', 'depth of sagittal curve', 'canine Angle class relation', 'history of orthodontic treatment', and 'self-reported grinding/clenching' (independent variables) and increase of wear facets (dependent variable). RESULTS: Mean increase in facet surface areas ranged from 1.2 mm2 (premolars, incisors) to 3.4 mm2 (molars); the relative increase ranged from 15% to 23%. Backward regression analysis showed no significant relation for 'group function', 'vertical overbite', 'depth of sagittal curve', 'history of orthodontic treatment' nor 'self-reported clenching. The final multiple linear regression model showed significant associations amongst 'anterior protected articulation' and 'horizontal overbite' and increase of facet surface areas. For all teeth combined, only 'anterior protected articulation' had a significant effect. 'Self reported grinding' did not have a significant effect (p>0.07). CONCLUSIONS: In this study 'anterior protected articulation' and 'horizontal overbite', were significantly associated with the progression of tooth wear. Self reported grinding was not significantly associated with progression of tooth wear. CLINICAL SIGNIFICANCE: Occlusal conditions such as anterior protected articulation and horizontal overbite seem to have an effect on the progression of occlusal tooth wear in this convenient sample of young adults.

Estimated prevalence of erosive tooth wear in permanent teeth of children and adolescents: an epidemiological systematic review and meta-regression analysis.

OBJECTIVES: The main purpose of this systematic review was to estimate the prevalence of dental erosion in permanent teeth of children and adolescents. METHODS: An electronic search was performed up to and including March 2014. Eligibility criteria included population-based studies in permanent teeth of children and adolescents aged 8-19-year-old reporting the prevalence or data that allowed the calculation of prevalence rates of tooth erosion. Data collection assessed information regarding geographic location, type of index used for clinical examination, sample size, year of publication, age, examined teeth and tissue exposure. The estimated prevalence of erosive wear was determined, followed by a meta-regression analysis. RESULTS: Twenty-two papers were included in the systematic review. The overall estimated prevalence of tooth erosion was 30.4% (95%IC 23.8-37.0). In the multivariate meta-regression model use of the Tooth Wear Index for clinical examination, studies with sample smaller than 1000 subjects and those conducted in the Middle East and Africa remained associated with higher dental erosion prevalence rates. CONCLUSIONS: Our results demonstrated that the estimated prevalence of erosive wear in permanent teeth of children and adolescents is 30.4% with high heterogeneity between studies. Additionally, the correct choice of a clinical index for dental erosion detection and the geographic location play an important role for the large variability of erosive tooth wear in permanent teeth of children and adolescents. CLINICAL SIGNIFICANCE: The prevalence of tooth erosion observed in permanent teeth of children and adolescents was considerable high. Our results demonstrated that prevalence rate of erosive wear was influenced by methodological and diagnosis factors. When tooth erosion is assessed, the clinical index should be considered.

The interactions between attrition, abrasion and erosion in tooth wear.

Tooth wear is the result of three processes: abrasion (wear produced by interaction between teeth and other materials), attrition (wear through tooth-tooth contact) and erosion (dissolution of hard tissue by acidic substances). A further process (abfraction) might potentiate wear by abrasion and/or erosion. Knowledge of these tooth wear processes and their interactions is reviewed. Both clinical and experimental observations show that individual wear mechanisms rarely act alone but interact with each other. The most important interaction is the potentiation of abrasion by erosive damage to the dental hard tissues. This interaction seems to be the major factor in occlusal and cervical wear. The available evidence is insufficient to establish whether abfraction is an important contributor to tooth wear in vivo. Saliva can modulate erosive/abrasive tooth wear, especially through formation of pellicle, but cannot prevent it.

Proximal attrition facets: morphometric, demographic, and aging characteristics.

Although interproximal attrition is considered to be limited in modern populations, it has important clinical implications. However, in contrast to occlusal attrition, proximal attrition receives limited scientific attention. The main purpose of the current study was to fill this void. Seven-hundred and sixty-five teeth were collected from 255 skulls of subjects 18-75 yr of age. For each individual, three mandibular teeth (the first and second premolars and the first molar) were examined for proximal attrition facets (PAFs). The results provide detailed information on the size, shape, and location of the facets according to age cohort, gender, and ethnicity. The validity of the method used to measure the facets was also examined. The major findings were as follows: PAFs are usually located on the upper half of the crown proximal aspect; in each tooth, the mesial facet is more lingually positioned and the distal facet is more buccally positioned; the majority of the facets are subrectangular in shape; the size of the facets tends to increase in an anteroposterior direction (from premolars to molars); and facet size and location are age- and sex-dependent and ethnicity-independent. It is our recommendation that dentists bear in mind that interproximal attrition is a dynamic, long-term process and needs to be considered in many clinical scenarios.