The study evaluated if men and women with severe tooth wear were at increased risk of general bone loss. Enamel biopsies obtained from 50 subjects aged 47.5 ± 5 years showed decreased copper content, which was associated with reduced spine bone mineral density, suggesting deficits of this trace element contributing to bone demineralization, enamel attrition, and deteriorated quality of mineralized tissues.
The objective of this cross-sectional study was to assess associations between enamel trace minerals and bone mineral density (BMD) in severe tooth wear. We hypothesized that similar factors contributed to both the excessive abrasion of dental enamel and reduced BMD in subjects with tooth wear.
Fifty patients aged 47.5 ± 5 years with severe tooth wear and 20 age-, sex-, and body mass index (BMI)-matched healthy volunteers with normal dental status were studied regarding dietary intakes of trace elements, serum and salivary copper (Cu), zinc (Zn), and calcium (Ca) concentrations, and serum PTH, osteocalcin, and hydroxyvitamin D levels. Tooth wear was determined using clinical examination based on standard protocol according to Smith and Knight. In all subjects, acid biopsies of the maxillary central incisors were carried out to assess mineral composition of the enamel. Atomic absorption spectroscopy with an air/acetylene flame was used to measure Ca and Zn, and graphite furnace atomic absorption spectroscopy was used to analyze Cu content. BMD was examined using dual energy X-ray absorptiometry.
Tooth wear patients had reduced lumbar spine, but not femoral, BMD relative to controls (p < 0.001). No differences were found in enamel Ca concentration and Zn content was slightly higher in tooth wear patients than in controls whereas Cu content was significantly decreased in the patients: 19.59 ± 16.4 vs 36.86 ± 26.1 μg/l (p = 0.01) despite similar levels of Cu in serum and saliva. The differences were independent of serum 25-OH-D, osteocalcin concentrations or PTH either.
Severe tooth wear is associated with reduced spinal BMD. Enamel in adult individuals with severe tooth wear is low in copper content. Therefore, further work is needed to determine whether copper plays a role in bone pathophysiology in these patients.
Bone mineral density; Copper deficit; Dental status; Enamel attrition; Enamel composition; Microelements
Tooth wear is a common finding in oral examinations. Pathological tooth wear (PTW) is the amount of wear that exceeds the normal phenomena of ageing or the normal threshold value of wear. The objective of this study was to determine the associated factors of PTW among 16-year-old secondary school children.
This case-control study involved 576 participants randomly selected from eight government secondary schools. The Smith and Knight Tooth Wear Index and WHO criteria were used for charting of tooth wear and dental caries respectively. Data were analyzed using a simplified Microsoft Excel program developed based on the index, to quantify PTW. Controls were subjects with no PTW indicated by zero scores on all tooth surfaces. Cases were subjects with PTW having at least one surface scoring 1 for tooth wear. Consequently, responses were obtained from self-administered questionnaire containing socio-demographic profile of the family, general questions, oral hygiene and food and drinks practices and other associated variables for tooth wear, which was previously developed based on expert opinions.
About 40% and 57% were males were in controls and cases respectively. On performing multivariable analysis, sex, monthly household income, carbonated drinks, duration of intake of orange juices, caries experience and swimming were significantly associated with PTW.
In conclusion the factors associated with PTW were no different from those encountered in Western societies. Realizing that some significant variables were modifiable, oral health promotion should emphasize on this information. The erosive potential of some foods and drinks require further investigation.
Prader-Willi syndrome (PWS) is a rare complex multsystemic genetic disorder characterized by severe neonatal hypotonia, endocrine disturbances, hyperphagia and obesity, mild mental retardation, learning disabilities, facial dysmorphology and oral abnormalities. The purpose of the present study was to explore the prevalence of tooth wear and possible risk factors in individuals with Prader-Willi syndrome.
Forty-nine individuals (6-40 years) with PWS and an age- and sex-matched control group were included. Tooth wear was evaluated from dental casts and intraoral photographs and rated by four examiners using the Visual Erosion Dental Examination (VEDE) scoring system and the individual tooth wear index IA. In accordance with the VEDE scoring system, tooth wear was also evaluated clinically. Whole saliva was collected.
Mean VEDE score was 1.70 ± 1.44 in the PWS group and 0.46 ± 0.36 in the control group (p < 0.001). Median IA was 7.50 (2.60-30.70) in the PWS group and 2.60 (0.90-4.70) among controls (p < 0.001). In the PWS group tooth wear correlated significantly with age (VEDE; r = 0.79, p < 0.001, IA; r = 0.82, p < 0.001) and saliva secretion (VEDE; r = 0.46, p = 0.001, IA; r = 0.43, p = 0.002). Tooth grinding was also associated with tooth wear in the PWS group, as indicated by the mean VEDE 2.67 ± 1.62 in grinders and 1.14 ± 0.97 in non-grinders (p = 0.001) and median IA values 25.70 (5.48-68.55) in grinders and 5.70 (1.60-9.10) in non-grinders (p = 0.003). Multivariate linear regression analysis was performed with tooth wear as the dependent variable and PWS (yes/no), age, tooth grinding and saliva secretion as independent variables. PWS (yes/no), age and tooth grinding retained a significant association with tooth wear, VEDE (p < 0.001) and log IA (p < 0.001). The only factor significantly associated with tooth wear in the control group was age.
Our study provides evidence that tooth wear, in terms of both erosion and attrition, is a severe problem in Prader-Willi syndrome. There is therefore considerable need for prosthodontic rehabilitation in young adults with PWS.
Prader-Willi syndrome; Tooth wear; Tooth grinding; Saliva secretion; Rehabilitation
Association between some socio-demographic attributes and tooth wear among adult male population in a rural community of Igbo-ora, Southwestern Nigeria was investigated in this cross-sectional study.
Cross-sectional study among 200 consenting adult males in Igbo-ora was carried out using a 10-item semi-structured questionnaire to obtain data on socio-demographics. Oral examination to establish the presence of tooth wear lesions was carried out by two examiners. Frequencies and percentages of relevant variables were generated. Multivariate analysis was used to test associations between categorical variables at P<0.05.
The mean age of participants was 35.6±11.7 years. One hundred and six (53.0%) subjects had one form of tooth wear lesion. Sixty eight (34.0%) of the subjects had attrition only and 96 (48.0%) had multiple tooth wear lesions. There was an association between age group, marital status, level of education and tooth wear (p<0.05). However, the association between occupation and tooth wear was not statistically significant (p>0.05). After adjusting for marital status, occupation and level of education, the association between age group and tooth wear was still significant. Though marital status was found to be associated with tooth wear, this association was not significant after adjusting for age, occupation and level of education. The association between some of the socio-demographic factors studied and the types of tooth wear was statistically significant (p<0.05).
Age group was the only independent predictor of tooth wear.
Socio-demographic; Rural Community; Tooth Wear; Nigerian
To estimate the prevalence of tooth wear and to investigate factors associated with tooth wear in patients from general practices in the Northwest United States.
Data on the diagnosis and treatment of oral diseases during the previous year were collected in a survey with a systematic random sample of patients (n = 1530) visiting general dentists from the Northwest Practice-based REsearch Collaborative in Evidence-based DENTistry (PRECEDENT) (n = 80). Prevalence ratios (PRs) of moderate to severe occlusal and incisal tooth wear by patient characteristics were estimated using cluster-adjusted multiple binomial regression for adults (18+ years) and children/adolescents (3–17 years).
For adults, the mean number of teeth with wear facets was 5.4 [95% confidence interval (CI) = 4.6–6.2] and 51% of the adults had four or more teeth with wear. Participants 45–64 and 65+ years old were 1.3 (95% CI = 1.1–1.6) and 1.4 (95% CI = 1.1–1.8) times as likely to have 4+ teeth with moderate to severe wear facets as participants 18–44 years old. Adult males had a 20% (PR = 1.2; 95% CI = 1.1–1.4) higher prevalence of wear than adult females. Adults who were using, or had ever used occlusal splints had higher prevalence of tooth wear compared to those who never used such appliances (PR = 1.3; 95% CI = 1.0–1.5). Adults with any periodontal bone loss also had a 20% higher prevalence of wear than adults without periodontal disease (PR = 1.2; 95% CI = 1.0–1.4). For children/adolescents, the mean number of teeth with moderate to severe wear facets was 1.6 (95% CI = 0.9–2.6) and 31% of the children had one or more teeth with wear facets. The adjusted prevalence ratio of tooth wear (1+ teeth with wear facets) for boys was 1.6 times as high (95% CI = 1.1–2.4) as compared with girls. The prevalence of wear for children 12+ years old was 50% (PR = 0.5; 95% CI = 0.3–0.8) lower than that of children <12 years old. Angle’s class II was associated with higher tooth wear prevalence (PR = 1.8; 95% CI = 1.3–2.6) than class I. Children with posterior or anterior open bite had lower prevalence of wear than their counterparts (PR = 0.6; 95% CI = 0.3–1.0). No associations were observed between tooth wear and orthodontic treatment, missing teeth, and race/ethnicity.
Tooth wear is a prevalent condition in this population. Among adults, higher prevalences of tooth wear were observed among those who were older, males, had used occlusal splints and had periodontal disease. Among children, higher prevalences were associated with younger age, male gender, class II malocclusion and the absence of open bite. Submitted on behalf of the Northwest PRECEDENT network, with support from NIDCR grants DE016750 and DE016752.
dental practice-based research; malocclusion; Northwest PRECEDENT; tooth attrition
This conventional literature review discusses whether pathological tooth wear is age dependant. It briefly reviews the components of tooth wear and the prevalence of tooth wear in children, adolescents and adults. The emphasis on terminology relating to tooth wear varies. In some countries, the role of erosion is considered the most important, whereas others consider the process to be a combination of erosion, attrition and abrasion often with one being more dominant. The importance of tooth wear or erosion indices in the assessment and the evidence for progression within subject and within lesions is described. The data from the few studies reporting pathological levels of wear reported in children and adults are discussed, in particular its relationship with age. There is little evidence to support the concept that pathological levels of erosion or wear are age dependant. There is, however, some evidence to suggest that normal levels of erosion or wear are age dependant.
Erosion; Tooth wear; Tooth wear index; Attrition; Abrasion
The purpose of this study was to evaluate the prevalence, distribution and associated factors of dental wear among patients with eating disorders (EDs).
Materials and Methods:
An epidemiological cross-sectional survey was conducted by trained, calibrated examiners, using the dental wear index. The sample was composed of 30 patients with EDs (experimental group – G1) and 30 control patients without current or previous history of EDs (G2). A questionnaire was used to assess the etiological factors of dental wear. The univariate analyses using the Chi-square (χ2) test were used to compare the tooth wear prevalence between groups according to the surface and tooth (P > 0.05).
The dental wear was similar for both group; however, the G1 presented more moderate wear in molars when compared with G2 (P = 0.048). The majority of EDs patients related have one or more oral habits (n = 26; 86.6%) and only 13.4% (n = 4) affirmed did not have oral habits. The etiological factors of tooth wear related with dental wear were biting objects (P = 0.04) and pain in temporomandibular disorders (P = 0.03).
The highest prevalence of dental wear was observed in the molars teeth. Differences in the extent and pattern of dental wear were found in an individual, emphasized the relevance of clinical parameter.
Anorexic; bulimic; eating disorders; oral health; tooth wear
In indigenous populations, age can be estimated based on family structure and physical examination. However, the accuracy of such methods is questionable. The aim of this cross-sectional study was to evaluate occlusal tooth wear related to estimated age in the remote indigenous populations of the Xingu River, Amazon. Two hundred and twenty three semi-isolated indigenous subjects with permanent dentition from the Arara (n = 117), Xicrin-Kayapó (n = 60) and Assurini (n = 46) villages were examined. The control group consisted of 40 non-indigenous individuals living in an urban area in the Amazon basin (Belem). A modified tooth wear index was applied and then associated with chronological age by linear regression analysis. A strong association was found between tooth wear and chronological age in the indigenous populations (p <0.001). Tooth wear measurements were able to explain 86% of the variation in the ages of the Arara sample, 70% of the Xicrin-Kaiapó sample and 65% of the Assurini sample. In the urban control sample, only 12% of ages could be determined by tooth wear. These findings suggest that tooth wear is a poor estimator of chronological age in the urban population; however, it has a strong association with age for the more remote indigenous populations. Consequently, these findings suggest that a simple tooth wear evaluation method, as described and applied in this study, can be used to provide a straightforward and efficient means to assist in age determination of newly contacted indigenous groups.
Extant rhinos are the largest extant herbivores exhibiting dietary specialisations for both browse and grass. However, the adaptive value of the wear-induced tooth morphology in rhinos has not been widely studied, and data on individual cusp and tooth positions have rarely been published. We evaluated upper cheek dentition of browsing Diceros bicornis and Rhinoceros sondaicus, mixed-feeding R. unicornis and grazing Ceratotherium simum using an extended mesowear method adapted for rhinos. We included single cusp scoring (EM(R)-S) to investigate inter-cusp and inter-tooth wear patterns. In accordance with previous reports, general mesowear patterns in D. bicornis and R. sondaicus were attrition-dominated and C. simum abrasion-dominated, reflecting their respective diets. Mesowear patterns for R. unicornis were more attrition-dominated than anticipated by the grass-dominated diet, which may indicate a low intake of environmental abrasives. EM(R)-S increased differentiation power compared to classical mesowear, with significant inter-cusp and inter-tooth differences detected. In D. bicornis, the anterior cusp was consistently more abrasion-dominated than the posterior. Wear differences in cusp position may relate to morphological adaptations to dietary regimes. Heterogeneous occlusal surfaces may facilitate the comminution of heterogeneous browse, whereas uniform, broad grinding surfaces may enhance the comminution of physically more homogeneous grass. A negative tooth wear gradient was found in D. bicornis, R. sondaicus and R. unicornis, with wear patterns becoming less abrasion-dominated from premolars to molars. No such gradients were evident in C. simum which displayed a uniform wear pattern. In browsers, premolars may be exposed to higher relative grit loads, which may result in the development of wear gradients. The second premolar may also have a role in food cropping. In grazers, high absolute amounts of ingested abrasives may override other signals, leading to a uniform wear pattern and dental function along the tooth row, which could relate to the observed evolution towards homodonty.
The association between periodontal status, oral hygiene status and severity of tooth wear lesion varies from community to community and also from occupation to occupation.
To determine the association between periodontal status, oral hygiene status and tooth wear among the adult male population in Benin City, Nigeria.
Subjects and Methods:
This study was conducted among 65 male drivers, aged 25-64 years, with a mean age of 48.6 (9.1) years in an organized private motor park in Benin City between November 2011 and January 2012. The data collected through interview and clinical oral examination were age, educational status, driving experience, oral hygiene status, periodontal status and severity of tooth wear.
In this study, 13.8% (9/65) and 1.5% (1/65) of the participants had 4-5 mm and ≥6 mm periodontal pockets, respectively. A total of 15.4% (10/65) of the participants had poor oral hygiene status and 58.5% (38/65) of the participants had tooth wear lesion, with 15.8% (9/65) being severe tooth wear lesions (score 3). Participants with poorer oral hygiene and more severe tooth wear lesions significantly exhibited poorer periodontal status. There also existed a significant association between oral hygiene status and the severity of tooth wear lesion among the participants in this study.
Data from this study revealed a statistically significant association between periodontal status, oral hygiene status and severity of tooth wear lesion among the participants.
Africa; Asia; Male population; Oral hygiene
Anthropologists have for many years considered human tooth wear a normal physiological phenomenon where teeth, although worn, remain functional throughout life. Wear was considered pathological only if pulpal exposure or premature tooth loss occurred. In addition, adaptive changes to the stomatognathic system in response to wear have been reported including continual eruption, the widening of the masticatory cycle, remodelling of the temporomandibular joint and the shortening of the dental arches from tooth migration. Comparative studies of many different species have also documented these physiological processes supporting the idea of perpetual change over time. In particular, differential wear between enamel and dentine was considered a physiological process relating to the evolution of the form and function of teeth. Although evidence of attrition and abrasion has been known to exist among hunter-gatherer populations for many thousands of years, the prevalence of erosion in such early populations seems insignificant. In particular, non-carious cervical lesions to date have not been observed within these populations and therefore should be viewed as ‘modern-day’ pathology. Extrapolating this anthropological perspective to the clinical setting has merits, particularly in the prevention of pre-mature unnecessary treatment.
Tooth wear; Attrition; Abrasion; Erosion; Adaptation
Tooth erosion is a growing dental problem; however, the role of diet in the aetiology of tooth erosion is unclear. A cross-sectional study was conducted to determine the association between tooth erosion occurrence and the consumption of acidic foods and drinks among undergraduate university students.
A total of 150 undergraduate students (33 males and 117 females) aged 19 to 24 years at Universiti Kebangsaan Malaysia participated in this study. The Basic Erosive Wear Examination was used to assess the occurrence of tooth erosion. Information regarding dental hygiene practices, usual dietary habits, and consumption of acidic foods and drinks was obtained through a structured questionnaire.
In all, 68% of subjects had tooth erosion. Subjects who reported having received information about healthy eating were less likely to have tooth erosion (χ2 [1, N = 150] = 7.328, P = 0.007). The frequencies of milk (OR = 0.29, 95% CI = 0.13–0.67) and tea/coffee (adjusted OR = 0.42, 95% CI = 0.19–0.95) consumption were negatively associated with tooth erosion. Dental hygiene practice, the frequency and amount of acidic food and drink intake, and body mass index classification were not significantly associated with the risk of tooth erosion (P > 0.05).
A high prevalence of tooth erosion was observed among this group of students. Preventive measures, such as dietary advice and increased consumption of milk at a younger age, may reduce the occurrence of tooth erosion among this age group.
beverages; cross-sectional study; food habits; public health; tooth erosion; young adult
Some studies have shown that casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and acidulated phosphate fluoride (APF) gel can protect teeth against erosion. The aim of this study was to assess whether CPP-ACP and fluoride could reduce enamel wear rates under erosive conditions simulating abrasion and acidic diet regimen.
Materials and Methods:
Enamel specimens consisted of 3 experimental groups (receiving CPP-ACP, APF or both) and a control group. Specimens were subjected to 5,000 wear cycles at a load of 30 N and a pH of 3 in a tooth wear machine. The amount of wear was determined by stereomicroscope. Data were analyzed using one-way analysis of variance and Tukey post hoc tests (α = 0.05).
Mean wear rate (mean±SD) was 194.6±49.2 micrometers in CPP-ACP group, 197.6±39.5 in APF group, 134.6±44.7 in combination group and 266.2± 22.7 in the control group. Statistical analysis indicated significantly higher wear rate in the control group than the experimental groups and also in the CPP-ACP and APF group than the combination group (P<0.05).
We concluded that although either CPP-ACP or APF can protect enamel against wear, their combination provides significant enamel wear reduction. These findings would lead to new strategies for the clinical management of tooth wear.
Casein phosphopeptide-amorphous calcium phosphate; enamel; fluoride; wear
Although modularity affords various options to the orthopedic surgeon, these benefits come at a price. The unintended bearing surface between the back surface of the tibial insert and the metallic tray results in micromotion leading to polyethylene wear debris. The objective of this study was to examine the backside wear of tibial inserts from three modern total knee designs with very different locking mechanisms: Insall-Burstein II® (IB II®), Optetrak®, and Advance®. A random sample of 71 inserts were obtained from our institution’s retrieval collection and examined to assess the extent of wear, depth of wear, and wear damage modes. Patient records were also obtained to determine patient age, body mass index, length of implantation, and reason for revision. Modes of wear damage (abrasion, burnishing, scratching, delamination, third body debris, surface deformation, and pitting) were then scored in each zone from 0 to 3 (0 = 0%, 1 = 0–10%, 2 = 10–50%, and 3 = >50%). The depth of wear was subjectively identified as removal of manufacturing identification markings stamped onto the inferior surface of the polyethylene. Both Advance® and IB II® polyethylene inserts showed significantly higher scores for backside wear than the Optetrak® inserts. All IB II® and Advance® implants showed evidence of backside wear, whereas 17% (5 out of 30) of the retrieved Optetrak® implants had no observable wear. There were no significant differences when comparing the depth of wear score between designs. The locking mechanism greatly affects the propensity for wear and should be considered when choosing a knee implant system.
polyethylene; wear; knee; backside; back surface; locking mechanism
The aim of this study was to estimate the prevalence of tooth wear in the aging population of northwest China and to investigate the factors associated with such tooth wear.
Cross-sectional analytic clinical and questionnaire study was performed in 704 participants who had a mean age of 46.5 ± 0.2 SD and of which 367(52.13%) were males and 337(47.87%) female. These participants were invited when they attended the hospital which located in northwest China for routine oral examination.
In the maxilla of the examined patients, the rate of tooth wear varied from 85.51% for molar group, 89.77% for premolar group, 100.0% for canine group to 87.22% for incisor group. In the mandible, the rates were 86.36%, 88.92%, 100.0% and 91.19% for the four groups respectively. Moreover, both the incisor and canine groups of these patients showed median scores of 3, the premolar group showed a median score of 1, and the molar group had a median score of 2. Additionally, multiple factors were considered to contribute to these patterns of tooth wear, especially the habitual consumption of a hard or sour diet (P < 0.05,odds ratio 1.21, 95% confidence intervals 1.04-1.49).
Tooth wear is a common disease in which the anterior teeth exhibit greater wear than posterior teeth. The data support an association between tooth wear and dietary patterns.
Tooth wear; Attrition; Erosion; Abrasion; Abfraction
Wear simulations may provide an indication of the clinical performance of pit-and-fissure sealants when associated with primary teeth as counterbody, restricting the involved variables. The aim of this study was to evaluate wear of dental materials used as pit-and-fissure sealants in contact with primary teeth.
Materials and Methods:
A resinous sealant (Fluroshield®) and a resin-modified glass ionomer cement (Vitremer®) were selected in a post-plate design, using as counterbody primary tooth pins (4 × 4 × 2 mm) at 3 and 10 N vertical load, 1 Hz frequency, 900 wear cycles in artificial saliva (n = 15). Attrition coefficient values were obtained and the material and primary tooth volumes were analyzed. Data were analyzed statistically by ANOVA and Duncan's test (P < 0.05).
Fluroshield® presented the highest attrition coefficient values for the 3 N but these values decreased significantly for the 10 N load. The means for volume loss (3 mm) of the different samples after the wear test were not statistically different for the materials. The volume loss values for the primary teeth were statistically different and there was an increase in volume loss with the increase of the load applied in the wear tests.
Differences were also observed with regard to the surface deformation characteristics. The wear rates of primary tooth enamel vary according to the type of material and the load applied during mastication.
Pit and fissure sealant; preventive material; primary teeth; two-body wear
Attrition, erosion, and abrasion result in alterations to the tooth and manifest as tooth wear. Each classification corresponds to a different process with specific clinical features. Classifications made so far have no accurate prevalence data because the indexes do not necessarily measure a specific etiology, or because the study populations can be diverse in age and characteristics.
Tooth wears (attrition, erosion and abrasion) is perceived internationally as a growing problem. However, the interpretation and comparison of clinical and epidemiological studies, it is increasingly difficult because of differences in terminology and the large number of indicators/indices that have been developed for the diagnosis, classification and monitoring of the loss of dental hard tissue. These indices have been designed to identify increasing severity and are usually numerical, none have universal acceptance, complicating the evaluation of the true increase in prevalence reported. This article considers the ideal requirements for an erosion index. A literature review is conducted with the aim of analyzing the evolution of the indices used today and discuss whether they meet the clinical needs and research in dentistry.
Key words:Tooth wear, tooth wear indices, attrition, erosion, abrasion, abfraction.
Complementary clinical and laboratory studies were performed to identify variables associated with polyethylene wear following total hip replacement, and to elucidate the mechanisms responsible for accelerated wear in the total hip arthroplasty construct.
Observational cohort studies were performed using a prospective clinical database of more than 4000 consecutive primary total hip arthroplasties performed by a single surgeon, to identify wear-related variables. These variables included head size, acetabular/femoral component impingement, and third body debris. Novel digital edge detection techniques were developed and employed to accurately measure wear, and to determine the relationships of head size and third body debris to acceleration of wear. A novel slidingdistance-coupled finite element model was formulated and employed to examine the mechanisms responsible for wear. The long-term cohort studies demonstrated smaller head sizes to be associated with less wear. Third body debris generated from cable fretting was associated with an increase in wear, osteolysis, and acetabular loosening, especially with larger head sizes. The sliding-distance-coupled finite element model replicated the wear rates occurring in vitro and in vivo, demonstrating the importance of sliding distance on polyethylene wear following total hip arthroplasty. It also demonstrated substantial increases in wear associated with femoral head scratching from third body debris. Further extension of the finite element formulation demonstrated the potential for acetabular component rim damage from impingement wear, and the enhanced potential for third body ingress to the bearing surface with larger head sizes. Edge detection wear measurement techniques demonstrated that early wear rates were predictive of long-term wear rates.
These complementary clinical and laboratory investigations have provided insight into 1) the significance of sliding distance and physiologic loci of motion as contributing factors in minimizing wear, 2) the deleterious effects of third body particulates in accelerating wear, 3) the potential for, and factors related to, impingement wear, and 4) the potential advantages and compromises related to the use of larger head sizes in the bearing surface construct.
Assessment of tooth morphology is an important part of the diagnosis and management of hypodontia patients. Several techniques have been used to analyze tooth form in hypodontia patients and these have shown smaller tooth dimensions and anomalous tooth shapes in patients with hypodontia when compared with controls. However, previous studies have mainly used 2D images and provided limited information. In the present study, 3D surface-imaging and statistical shape analysis were used to evaluate tooth form differences between hypodontia and control patients. Eighteen anatomical landmarks were recorded on the clinical crown of the lower left first permanent molar of 3D scanned study models of hypodontia and control subjects. The study sample group comprised of 120 hypodontia patients (40 mild, 40 moderate, and 40 severe hypodontia patients) and 40 age- and sex-matched controls. Procrustes coordinates were utilized to scale and superimpose the landmark coordinate data and then were subjected to principal component analysis (PCA). Subsequently, differences in shape as well as size were tested statistically using allometric analysis and MANOVA. Significant interaction was found between the two factor variables “group” and “sex” (p < 0.002). Overall expected accuracies were 66 and 56% for females and males, respectively, in the cross-validated discriminant-analysis using the first 20 PCs. Hypodontia groups showed significant shape differences compared with the control subjects (p < 0.0001). Significant differences in tooth crown shape were also found between sexes (p < 0.0001) within groups. Furthermore, the degree of variation in tooth form was proportional to the degree of the severity of the hypodontia. Thus, quantitative measurement of tooth shape in hypodontia patients may enhance the multidisciplinary management of those patients.
hypodontia; Procrustes analysis; shape analysis; teeth
Studies examining human and nonhuman primates have supported the hypothesis that the recent increase in the occurrence of misalignment of teeth and/or incorrect relation of dental arches, named dental malocclusion, is mainly attributed to the availability of a more processed diet and the reduced need for powerful masticatory action. For the first time on live human populations, genetic and tooth wear influences on occlusal variation were examined in a split indigenous population. The Arara-Iriri people are descendants of a single couple expelled from a larger village. In the resultant village, expansion occurred through the mating of close relatives, resulting in marked genetic cohesion with substantial genetic differences.
Dental malocclusion, tooth wear and inbreeding coefficient were evaluated. The sample examined was composed of 176 individuals from both villages. Prevalence Ratio and descriptive differences in the outcomes frequency for each developmental stage of the dentition were considered. Statistical differences between the villages were examined using the chi-square test or Fisher's exact statistic. Tooth wear and the inbreeding coefficient (F) between the villages was tested with Mann-Whitney statistics. All the statistics were performed using two-tailed distribution at p≤0.05. The coefficient inbreeding (F) confirmed the frequent incestuous unions among the Arara-Iriri indigenous group. Despite the tooth wear similarities, we found a striking difference in occlusal patterns between the two Arara villages. In the original village, dental malocclusion was present in about one third of the population; whilst in the resultant village, the occurrence was almost doubled. Furthermore, the morphological characteristics of malocclusion were strongly different between the groups.
Our findings downplay the widespread influence of tooth wear, a direct evidence of what an individual ate in the past, on occlusal variation of living human populations. They also suggest that genetics plays the most important role on dental malocclusion etiology.
Age is one of the prime factors employed to establish the identity of an individual and the use of teeth for this purpose has been considered reliable. Tooth wear is widely accepted as a physiological consequence of aging and evaluation of tooth wear can be a simple and convenient tool to estimate age in adults.
The present study was conducted to record the degree of tooth wear among Indian adults and to estimate their ages from the degree of tooth wear based on Kim's scoring system.
Materials and Methods:
Dental stone casts of 120 participants were used to assess the degree of occlusal tooth wear based on the criteria given by Kim et al.
Statistical Analysis Used:
The age of all subjects was estimated based on these scores using multiple regression analysis function.
The degree of tooth wear showed a significant positive correlation with age in each and every examined tooth of both males and females. The predicted age was within ± 5 years of actual age in 70% of males and 68.3% females, and within ± 3 years of actual age in 50% of males and 50.1% of females.
Kim's scoring system has proven to be a useful tool in estimation of age using occlusal wear in an Indian population with a high level of accuracy in adults.
Age estimation; forensic odontology; Kim's scoring system; occlusal tooth wear
We aimed to assess the oral health status and risk factors for dental caries and periodontal disease among Sudanese adults resident in Khartoum State. To date, this information was not available to health policy planners in Sudan.
A descriptive population-based survey of Sudanese adults aged ≥ 16 years was conducted. After stratified sampling, 1,888 adult patients from public dental hospitals and dental health centres scattered across Khartoum State, including different ethnic groups present in Sudan, were examined in 2009-10. Data were collected using patient interviews and clinical examinations. Dental status was recorded using the DMFT index, community periodontal index (CPI), and a validated tooth wear index.
Caries prevalence was high, with 87.7% of teeth examined having untreated decay. Periodontal disease increased in extent and severity with age. For 25.8% of adults, tooth wear was mild; 8.7% had moderate and 1% severe toothwear. Multivariate analysis revealed that decay was less prevalent in older age groups but more prevalent in southern tribes and frequent problem based attenders; western tribes and people with dry mouths who presented with less than18 sound, untreated natural teeth (SUNT). Older age groups were more likely to present with tooth wear; increasing age and gender were associated with having periodontal pocketing ≥ 4 mm.
The prevalence of untreated caries and periodontal disease was high in this population. There appear to be some barriers to restorative dental care, with frequent use of dental extractions to treat caries and limited use of restorative dentistry. Implementation of population-based strategies tailored to the circumstances of Sudanese population is important to improve oral health status in Sudan.
The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis; finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted.
all-ceramic; crowns; tooth wear
Dental ceramics are the most used esthetic fixed Prosthodontic restorative material today. However, dentists remain suspicious about their potential abrasivity. Lower-fusing ceramic materials developed, are claimed to be wear friendly. This study was conducted to compare the wear of enamel of extracted teeth against one conventionally used ceramic VMK-95 (fusing temperature 930 °C) and two new lower-fusing ceramics-Omega 900 and Finesse with fusing temperatures 900 and 760 °C respectively, used for metal–ceramic restorations. Metal disks were prepared from ceramic alloy and divided into three groups of 10 disks each on which VMK-95, Omega 900 and Finesse ceramics were applied respectively. Ceramic disks and tooth specimen were mounted on custom-made wear simulator and subjected to predefined masticatory test. Each tooth specimen was profiled by laser triangulation sensor before and after masticatory test. Difference in height was calculated. The results showed that mean loss of height of tooth was least against Finesse (0.3431 + 0.0177 mm) followed by Omega 900 (0.4076 + 0.0135 mm) and VMK-95 (0.6177 + 0.014 mm). Statistical analysis revealed statistically significant difference between VMK-95 & Omega 900 and VMK-95 & Finesse. The difference in loss of height of tooth against Finesse & Omega 900 is statistically insignificant (P < 0.001). The results of this study indicate that lower-fusing dental ceramics cause less wear of opposing enamel.
Wear; Fusion temperature; Wear simulator; Profilometry; Laser triangulation sensor
Polyethylene wear is an important factor for longevity of total knee arthroplasty. Proven and suspicious factors causing wear can be grouped as material, patient and surgery related. There are more studies correlating design and/or biomaterial factors to in vivo wear than those to patient and surgery related factors. Many retrieval studies just include revision implants and therefore may not be representative. This study is aimed to correlate patient- and surgery- related factors to visual wear score by minimizing design influence and include both autopsy and revision implants. Comparison between the groups was expected to unmask patient and surgery-related factors responsible for wear.
The amount of joint side wear on polyethylene retrievals was measured using a modification of an established visual wear score. Fatigue type wear was defined as summation of the most severe wear modes of delamination, pitting and cracks. Analysis of patient and surgery related variables suspicious to cause wear included prospectively sampled patient activity which was measured by self reported walking capacity. Statistical analysis was done by univariate analysis of variance. Activity level and implantation time were merged to an index of use and correlated to the wear score.
Wear score after comparable implantation time was significantly less in the autopsy group. Even so, fatigue type wear accounted for 84 and 93 % of total wear score on autopsy and revision implants respectively. A highly significant influence on wear score was found in time of implantation (p = 0.002), level of activity (p = 0.025) and inserts belonging to revision group (p = 0.006). No influence was found for the kind of patella replacement (p = 0.483). Body mass index and accuracy of component alignment had no significant influence on visual wear score. Fatigue-type wear in the medial compartment was closely correlated to the index of use in the autopsy (R2 = 0.383) and the revision group (R2 = 0.813).
The present study's finding of substantial fatigue type wear in both autopsy and revision retrievals supports the theory that polyethylene fatigue strength is generally exceeded in this type of prosthesis. Furthermore, this study correlated fatigue-type polyethylene wear to an index of use as calculated by activity over time. Future retrieval studies may use activity over time as an important patient related factor correlated to the visual wear score. When evaluating total knee arthroplasty routine follow up, the surgeon must think of substantial wear present even without major clinical signs.