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 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.

Tooth wear and dentoalveolar remodeling are key factors of morphological variation in the Dmanisi mandibles.

The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, is unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo. Cranial and dentoalveolar morphologies exhibit a high degree of diversity, but the causes of variation are still relatively unexplored. Here we show that wear-related dentoalveolar remodeling is one of the principal mechanisms causing mandibular shape variation in fossil Homo and in modern human hunter-gatherer populations. We identify a consistent pattern of mandibular morphological alteration, suggesting that dental wear and compensatory remodeling mechanisms remained fairly constant throughout the evolution of the genus Homo. With increasing occlusal and interproximal tooth wear, the teeth continue to erupt, the posterior dentition tends to drift in a mesial direction, and the front teeth become more upright. The resulting changes in dentognathic size and shape are substantial and need to be taken into account in comparative taxonomic analyses of isolated hominin mandibles. Our data further show that excessive tooth wear eventually leads to a breakdown of the normal remodeling mechanisms, resulting in dentognathic pathologies, tooth loss, and loss of masticatory function. Complete breakdown of dentognathic homeostasis, however, is unlikely to have limited the life span of early Homo because this effect was likely mediated by the preparation of soft foods.

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.

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.

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.

Analysis and comparison of tooth wear in late antiquity and early middle age in populations that lived in continental and coastal Croatia using digitized VistaMetrix method.

BACKGROUND: Tooth wear is a non-pathological loss of hard tissues on the incisal and occlusal tooth surface. In archaeology, the loss of dental tissue through attrition is associated with living opportunities and habits, availability, characteristics and methods of food preparation. In forensics, tooth wear is used to estimate the dental age on cadavers. MATERIAL AND METHODS: For this study, we used an archaeological sample from two sample collections. In this study, tooth wear was compared in archaeological samples of well-preserved maxilla and mandible specimens (n=392) from Croatian coastal and continental populations from Late Antiquity (LA) and the Early Middle Ages (EMA). The computer system VistaMetrix 1.38 was used to analyse the abrasion and attrition of hard dental tissues. The Shapiro-Wilk and chi-square tests were performed for categorical data to test the difference between two historical periods and two geographical locations, while the Kruskal-Wallis test was performed for continuous data. RESULTS: There was a statistically significant difference in the proportion of tooth wear in total teeth area (P < 0.001) when comparing continental and coastal Croatia in LA and coastal Croatia between LA and EMA (P = 0.006 and P < 0.001, respectively). Samples from coastal Croatia from the LA period had the lowest percentage of tooth wear with a median of 8.35%, while samples from coastal Croatia from the EMA had the highest percentage of tooth wear with a median of 18.26%. Our results generally show greater tooth wear in the EMA period in male subjects. CONCLUSION: The results of the tooth wear research obtained with the Vista Metrix software can contribute to the study of life circumstances and changes that the analysed population has experienced in its historical development.

Individual tooth macrowear pattern guides the reconstruction of Sts 52 (Australopithecus africanus) dental arches.

The functional restoration of the occlusal relationship between maxillary and mandibular tooth rows is a major challenge in modern dentistry and maxillofacial surgery. Similar technical challenges are present in paleoanthropology when considering fragmented and deformed mandibular and maxillary fossils. Sts 52, an Australopithecus africanus specimen from Sterkfontein Member 4, represents a typical case where the original shape of the dental arches is no longer preserved. It includes a partial lower face (Sts 52a) and a fragmented mandible (Sts 52b), both incomplete and damaged to such an extent to thwart attempts at matching upper and lower dentitions. We show how the preserved macro wear pattern of the tooth crowns can be used to functionally reconstruct Sts 52's dental arches. High-resolution dental stone casts of Sts 52 maxillary and mandibular dentition were mounted and repositioned in a dental articulator. The occlusal relationship between antagonists was restored based on the analysis of the occlusal wear pattern of each preserved tooth, considering all dental contact movements represented in the occlusal compass. The reconstructed dental arches were three-dimensional surface scanned and their occlusal kinematics tested in a simulation. The outcome of this contribution is the first functional restoration of A. africanus dental arches providing new morphometric data for specimen Sts 52. It is noteworthy that the method described in this case study might be applied to several other fossil specimens.

Age estimation from physiological changes of teeth by Gustafson's method.

Age determination is crucial in medicolegal cases. Various factors are considered for determination of age, out of which teeth are the most durable structures in human body which are better preserved even in the acidic soil. In many archaeological sites and forensic cases, teeth are the only available human remains for the identification and age determination purpose. We conducted this study to know the changes in teeth with advancement of age. In our study, 80 cases in the age group of 26-70 years were studied, out of which 58 were men and 22 women. The six physiological changes in teeth, viz. attrition, periodontosis, secondary dentin deposition, root translucency, cementum apposition and root resorption, were studied with each parameter having score ranging from 0 to 3. Total score was calculated by adding the scores of all the six physiological factors. The regression analysis was done by plotting the total score allotted against the actual age of the person. This regression line was used to derive the regression formula which came out as y = 3.71x + 16.03 and from this, age of the person was calculated. The average age difference between known and estimated age in this study was found to be ±4.43 years.

Estimating age from adult occlusal wear: a modification of the miles method.

The Miles method of age estimation relies on molar wear to estimate age and is widely used in bioarcheological contexts. However, because the method requires physical seriation and a sample of subadults to estimate wear rates it cannot be applied to many samples. Here, we modify the Miles method by scoring occlusal wear and estimating molar wear rates from adult wear gradients in 311 hunter-gatherers and provide formulae to estimate the error associated with each age estimate. A check of the modified method in a subsample (n = 22) shows that interval estimates overlap in all but one case with age categories estimated from traditional methods; this suggests that the modifications have not hampered the ability of the Miles method to estimate age even in heterogeneous samples. As expected, the error increases with age and in populations with smaller sample sizes. These modifications allow the Miles method to be applied to skeletal samples of adult crania that were previously only amenable to cranial suture age estimation, and importantly, provide a measure of uncertainty for each age estimate.

Predormancy omnivory in European cave bears evidenced by a dental microwear analysis of Ursus spelaeus from Goyet, Belgium.

Previous morphological and isotopic studies indicate that Late Pleistocene cave bear (Ursus spelaeus) diet ranged from mostly vegetarian to omnivory or even carnivory. However, such analyses do not provide information on seasonal diets, and only provide an average record of diet. A dental microwear analysis of 43 young and adult individuals demonstrate that, during the predormancy period, cave bears from Goyet (Late Pleistocene, Belgium) were not strictly herbivorous, but had a mixed diet composed of hard items (e.g., possibly bone), invertebrates (e.g., insects), meat (ungulates, small vertebrates), and/or plant matter (hard mast, seeds, herbaceous vegetations, and fruits). Therefore, our results indicate that cave bears at Goyet were generalist omnivores during the predormancy period, which is consistent with current data on the dietary ecology of extant bears during this season. These data also raise questions about the ecological role and causes of the extinction of cave bears.

Impact of measuring multiple or single occlusal lesions on estimates of diagnostic accuracy using fluorescence methods.

Carious lesions can occur at different sites on the occlusal surfaces of teeth and may differ in appearance and severity. This study aimed to evaluate how scoring several lesions on occlusal surfaces, as opposed to only one representative lesion, affects estimates of reproducibility and accuracy of fluorescence-based devices. Thirty-six permanent teeth with 2-3 investigation sites (n = 82) were examined by two examiners using the laser fluorescence device DIAGNOdent pen (LF) and the fluorescence camera VistaProof (FC). Lesion depth was then assessed histologically in serial sections of the teeth. Intra-class-correlation coefficients (ICC) and areas under the ROC-curves were calculated for all investigation sites and for one randomly selected site per tooth. Comparing the reproducibility and the performance for the whole sample and the independent sites showed only a small effect or no effect. Measuring multiple sites on teeth with fluorescence devices only moderately influences performance compared to one site being investigated.

Comparison of the anatomic crown width/length ratios of unworn and worn maxillary teeth in Asian and white subjects.

STATEMENT OF PROBLEM: Various aspects of anatomic tooth dimensions have been examined in a number of studies where data are primarily based on the measurements obtained from white subjects. Additional factors such as ethnicity should be considered to produce a more comprehensive analysis. PURPOSE: The purpose of this study is to compare the anatomic crown dimensions of extracted maxillary teeth in Asian and white populations. MATERIAL AND METHODS: The width/length ratio (%) was calculated with standardized digital images of extracted maxillary anterior teeth from 157 Asian and 142 white subjects. Statistical analysis was performed to compare the 4 tooth groups (central incisiors, lateral incisiors, canines, and premolars) of the 2 ethnicities. The distribution of the outcome variables were examined for normality with the Kolmigorov-Smirnov test. Independent sample t tests were used to examine differences in outcomes in Asian and white subjects. RESULTS: There was a significant difference (P<.05) in the width/length ratios of all maxillary anterior teeth in Asian and white subjects. In addition, there was a significant difference in the width of unworn central incisors and the length of worn lateral incisors and canines. CONCLUSIONS: Ethnicity influences width/length ratios for all 4 anterior maxillary teeth. Anterior maxillary teeth in Asian subjects appear to be more slender when compared with those in white subjects.

Nature of occlusion during eccentric mandibular movements in young adults.

AIM: The aim of this study was to find out the nature of occlusion and tooth contact during various eccentric mandibular movements in young adults with class I occlusion. MATERIALS AND METHODS: The sample consisted of 100 young adults with class I occlusion with full complement of teeth. Anterior disclusion in centric occlusion was demonstrated using a shim stock interposed between the upper and lower anteriors. Disclusion of posteriors was ascertained during 1.5 mm straight protusion and in edge-to-edge protrusion, visually as well as using a silk floss method. Posterior disclusion was also verified during lateroprotrusion and crossover. Besides these occlusal wear of teeth also were observed. RESULTS: The results of this study showed that the anterior disclusion is seen only in one-fourth of the subjects compared to almost three-fourth showing posterior disclusion. Mutually protected occlusion was also seen only in one-fourth of the subjects. Canine protective mechanism is seen in a relatively large number of subjects, but it was not overwhelmingly predominant. No correlation could be established between cuspid wear and the type of occlusion. A relatively high percentage of subjects showed wear on posterior teeth when there was no posterior disclusion. CONCLUSION: From the above study it is seen that posterior disclusion is acknowledged as a common factor except when a bilateral balance is present. Since bilateral balance is harmful, the ideal occlusal relationship in eccentric movements is in favor of posterior disclusion. Posterior disclusion is easily obtainable when restorations are planned. CLINICAL SIGNIFICANCE: From the findings and results it has been possible to make some contributions on the nature of tooth contacts and disclusion during various eccentric movements and compare it with the requirements of ideal occlusion.

Changes in orientation of attritional wear facets with implications for jaw motion in a mixed longitudinal sample of Propithecus edwardsi from Ranomafana National Park, Madagascar.

In many mammalian species, the progressive wearing down of the teeth that occurs over an individual's lifetime has the potential to change dental function, jaw movements, or even feeding habits. The orientation of phase-I wear facets on molars reveals the direction of jaw movement during the power stroke of mastication. We investigated if and how molar wear facets change with increasing wear and/or age by examining a mixed longitudinal dataset of mandibular tooth molds from wild Propithecus edwardsi (N = 32 individuals, 86 samples). Measurements of the verticality of wear facets were obtained from three-dimensional digital models generated from µCT scans. Results show that verticality decreases over the lifetime of P. edwardsi, a change that implies an increasingly lateral translation of the jaw as the teeth move into occlusion. A more transverse phase-I power stroke supports the hypothesis that these animals chew to maximize longevity and functionality of their teeth, minimizing the "waste" of enamel, while maintaining sharp shearing crests. Results of this study indicate that wear facet verticality is more closely correlated with age than overall amount of tooth wear, measured as area of exposed dentin, suggesting that age-related changes in cranial morphology may be more responsible for adjustments in jaw motion over the lifetimes of Propithecus than wear-related changes inthe shape of occluding teeth. Finally, the rate of decrease in wear facet verticality with age is greater in males than in females suggesting differences in development and/or access to resources between the sexes in this species.

Diagnosis and management of dental wear.

Dental wear is loss of tooth structure resulting from erosion, attrition, abrasion, and, possibly, abfraction. Clinical/experimental data suggest no single damaging mechanism but rather simultaneous interaction of these destructive processes. The most important interaction is abrasion/attrition potentiated by dental erosion. Awareness of this pathosis is not well-appreciated by the public and dental professionals because the signs may be subtle. This article focuses on the recognition, diagnosis, and management of dental wear.

[Tooth wear, a proposal for an evaluation system]. / Een beoordelingssysteem voor gebitsslijtage.

The present-day terminology and definitions of tooth wear are not unambiguous. For diagnosing tooth wear, however, it is essential that they are unambiguous. In this article a proposal is presented for a tooth wear evaluation system with simplified definitions. This system consists ofa number of modules and can be used for various aspects of the diagnostic procedure. It can be used for the quantification of tooth wear, both for periodic screening and for the monitoring of tooth wear in individual patients. The scoring of occlusal/incisal tooth wear as well as of non-occlusal/non-incisal tooth wear is possible. The evaluative system is also suitable for determining which type of tooth wear, such as attrition, abrasion and erosion, is most likely to have caused any observed loss of hard tooth tissue.