Tooth wear in aging people: an investigation of the prevalence and the influential factors of incisal/occlusal tooth wear in northwest China
© Liu et al.; licensee BioMed Central Ltd. 2014
Received: 7 December 2013
Accepted: 27 May 2014
Published: 5 June 2014
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.
KeywordsTooth wear Attrition Erosion Abrasion Abfraction
The incidence of natural tooth retention is increasing, and consequently, a greater prevalence of tooth wear is observed in the aging population . The term ‘tooth wear’ is used to describe the loss of hard tooth tissue caused by friction between the occlusal surfaces of opposing teeth or between a tooth’s occlusal surface and food during masticatory and non-masticatory movements, with no occurrence of dental caries or trauma. There are three main mechanisms of tooth wear, namely, erosion, attrition, and abrasion . Attrition is the physiological wearing of dental hard tissues through tooth-to-tooth contact, without the intervention of foreign substances . Abrasion is the pathological wear of dental hard tissue through abnormal mechanical processes that involve foreign objects or substances that are repeatedly introduced to the mouth and contact the teeth. Erosion is the loss of dental hard tissues by the chemical dissolution of enamel or dentin through the action of nonbacterial acid from dietary or gastric sources.
A review of the literature reveals that many different tooth wear indices have been developed for clinical and laboratory use all over the world. The literature abounds with many different methods, which can be broadly divided into categories that are quantitative and qualitative in nature . Quantitative methods tend to rely on objective physical measurements, such as depth of grooves, area of facets, and height of crowns . Qualitative methods, which rely on clinical descriptions, can be more subjective and incline to descriptive assessment measures, such as mild, moderate or severe . In this paper, the Tooth Wear Index (TWI), introduced by Smith and Knight was used .
Currently, tooth wear is perceived internationally as an ever-increasing problem, especially in the elderly, as it is more common in this age group . Furthermore, dietary habits, the presence of acid reflux and socio-economic status have all been shown to affect the prevalence of tooth wear. However, there are not many studies in China that clearly establish the prevalence and etiology of tooth wear. This study first proposed the types and the distribution of tooth position and tooth wear in Chinese people, especially among the northwestern region of China. The objective of this study was to investigate the prevalence of tooth wear and to assess the possible influential factors associated with such wear among the aging population. This information will enable professionals and public health personnel to establish methods and develop preventive strategies for the passive management of tooth wear in this age group.
Seven hundred and fifty patients attending the stomatological hospital of the Fourth Military Medical University(FMMU, Shaanxi Xi’an) for routine oral examination between April 2012 and June 2013 were invited to take part in the study. Forty six patients declined participation in the investigation. Therefore, seven hundred and four patients (52.13% males and 47.87% female) with tooth wear, aged 40–50 years (mean 46.5 ± 0.2 SD), were included in this study. In each patient, less than two teeth were missing in either the maxilla or the mandible, and the occlusion of the remaining tooth was normal. Clinical oral examination of the patients was performed in an outpatient dental clinic using a disposable dental mirror, disposable explorer and gauzes (to remove food debris, if necessary), under standard illumination from a dental operating light. All patients were examined intraorally by the same practitioner. In our study, the examiner was trained and calibrated both on clinical intra-oral photograhs and on a group of patients. The intra-examined variations were evaluated according to the World Health Organization (WHO) recommendation giving a Kappa agreement at the end of the training phase of 0.75 as described by Bartlett DW et al. . The authors declare that the protocols were approved by the Human Experimental Ethical Inspection of FMMU (No. IRB-REV-2011015), and that the study was performed in accordance with the Declaration of Helsinki (2008) for humans.
Smith and Knight tooth wear index: B = buccal; L = lingual; O = occlusal; I: incisal
No loss of enamel surface characteristics
Loss of enamel surface characteristics
Loss of enamel, exposing dentin on less than one-third of surface
Loss of enamel, just exposing dentin
Loss of enamel, exposing dentin on more than one third of surface
Loss of enamel and substantial loss of dentin
Complete enamel loss, pulp exposure, secondary dentin exposure
Pulp exposure or exposure of secondary dentin
Questionnaire responses among 704 patients (%)
Q1: Do you often make tooth grinding sounds during sleep (confirmed by room mate or family member)?
Q2: Do you favor the consumption of hard or acidic foods?
Q3: Does your work environment involves dust or acid gas?
Q4: Do you have parafunctional activity, such as clenching or grinding your teeth?
Q5: Do you suffer from clicking of the temporomandibular joint?
Q6: Do you suffer from stiffness or fatigue of the masticatory muscles?
Q7: Do you suffer from acid reflux?
The analysis of data was carried out using the Statistical Package for the Social Sciences (SPSS, Inc. Chicago, IL, USA version 10). The relationship between tooth wear and questionnaire items was evaluated in a multiple logistic regression model,estimating an odds ratio per unit increase of the mean tooth wear score when the mean tooth wear was a linear variable in the statistical model. The odds ratio represented the odds of suspected items for an individual with level y mean tooth wear score + 1 unit mean tooth wear score versus the odds of the items for an individual with level y mean tooth wear score. Thereby, the criterion for the independent variables to enter the model was set at 0.2 and the criterion to stay at 0.25. Statistically significant levels were set at p <0.05.
The prevalence rates of tooth wear in dental patients were calculated. In the maxilla, the rate 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. However, no significant difference was observed among these groups in either maxilla or mandible.
The scoring of tooth wear
2.08 ± 0.73
1.55 ± 0.81
2.44 ± 0.65
2.37 ± 0.76
2.24 ± 0.63
1.61 ± 0.75
2.47 ± 0.72
2.55 ± 0.83
All participants completed the questionnaire. Table 2 demonstrates that for the etiological factors that are specifically associated with tooth wear. Notably, Consuming of hard or acidic foods (52.3%), bruxism during sleep (40.9%), and clicking of the temporomandibular joint (36.4%) turn to be the top 3 factors which may be responsible for tooth wear.
The result of multiple logistic regression analysis shows that the preference for hard or acidic foods was significantly associated with tooth wear (p = 0.024 < 0.05). The odds ratio is 1.21, which means that consuming of hard or acidic foods increased the chance of tooth wear by 121% (95% confidence intervals 104-149%).
There is a well-recognized trend for increased longevity amongst the population of China, resulting in an increased proportion of aging and elderly people in the community. Concomitant with the observed increase in the proportion of elderly people, there has been a decrease in the rate of tooth loss with increasing age. These two factors have combined to produce a substantial increase in the numbers of aging and elderly patients with some retained teeth. Tooth surface loss is a macroscopically irreversible process that accumulates with age. Lambrechts estimated the normal vertical loss of enamel from physiological wear to be approximately 20–38 μm per annum . When the process of tooth wear is excessive, it leads to tooth shortening, exposed dentin, tooth hypersensitivity, or, more seriously, exposure of the canal, pulpitis, pulp necrosis, and an unsightly appearance [9, 10].
In a recent systematic review of the results of tooth wear by all causes, Van’t Spijker concluded that the percentage of adult patients presenting with severe tooth wear increased from 3% at the age of 20 years to 17% at the age of 70 years, with a tendency to develop more wear with age . Similar results were reported in a large epidemiological study with German dental patients, in which the extent of tooth wear was scored on a scale from 0 to 3; in this study, the mean wear scores increased from 0.6 among 20- to 29-year-olds to 1.4 in 70- to 79-year-olds . The incisal surfaces of canines and incisors, together with the occlusal surfaces of molars and premolars, are the functional surfaces of the dentition. This classification indicates their role in mastication and in providing guidance in excursive movements of the mandible. In this study, incisors and canines showed greater wear than molars, and molars showed greater wear than premolars in both the maxillary or mandibular dentition. The canine and incisor teeth displayed a stronger increase in the severity of wear than did the molar and premolar teeth, with mean wear scores that indicated a loss of enamel and a substantial loss of dentin on the incisal surfaces of these teeth. This result was consistent with the findings of other scholars . The reasons for this higher degree of wear observed in the incisors and canines may include the following: i the enamel of incisors is thinner, and incisors are smaller; ii the active role of incisors and canines in both masticatory and excursive jaw movements during function and parafunction, which may place greater demands upon these teeth than that endured by the larger posterior teeth; iii incisors and canines are, on average, the most frequently retained teeth among older people, which may influence the level of wear to which they are subjected. Between the two arches, the incisal surfaces of the mandibular anterior teeth displayed higher mean wear scores than that of the maxillary anterior teeth, and this result may be attributed to the role of the lower incisal edges during incision and throughout the process of protrusive guidance.
The prevalence of tooth wear varies around the globe, and the etiology of tooth wear is multifactorial [14, 15]. In developed countries, the prevalence of tooth wear is on the rise, which could be due to changes in dietary patterns [16, 17]. Oral habits are repetitive behaviors in the oral cavity that result in loss of tooth structure, including dietary habits, brushing techniques, bruxism, parafunctional habits and regurgitation. Their effect is dependent on the nature, onset and duration of the habits. The role of acidic foods and drinks is likely important to the progression of tooth wear. There is a considerable body of evidence from laboratory studies that indicates that low pH acidic foods and drinks cause erosion of enamel and dentin [18–20]. The coarseness or grit of the diet during function is a main causative factor in occlusal wear. Bruxism is thought to affect 5-20% of the normal population, and it is associated with tooth wear . Pavone noted that abnormal clenching and grinding habits produced unusual wear patterns of occlusal surfaces, and Christensen showed that people who displayed bruxism could experience up to four times more tooth wear than those without this habit [22, 23]. Individuals with stronger and/or more frequent bite forces should exhibit more tooth wear. In this study, the survey results found that eating habits, bruxism and joint disease constitute the majority of the total respondents, followed by parafunctional activity, the presence of reflux disease and working conditions. Analyzing the relevant factors that affect tooth wear by multiple logistic regression analysis, it was found that the preference for hard or acidic food had the greatest effect on tooth wear. The constituents of the diet, the consistent chewing of abrasive diets, the presence of unglazed enamel and environmental factors, such as constant exposure to dust and grit in farming activities, were related to abrasion . Eisenburger found that simultaneous erosion and abrasion resulted in approximately 50% more wear than alternating erosion and abrasion . Among these seven hundred and four patients, one male subject had retained twenty-six teeth, and he had twenty-one teeth with wear scores of 3 to 4. His questionnaire revealed that the frequently consumed Daguokui (known to be dry, hard, and chewy) and Shaanxi sour soup noodles and that his working environment involved dust (miner). This finding may indicate that softened enamel is highly unstable and that it can be easily removed by short and relatively gentle physical action. Therefore, the chewing of acidic foods with a stronger bite force might cause enhanced tooth wear.
In conclusion, this study has provided data on the proportions of the various types of tooth wear lesions among aging people in northwest China. Though the observed patterns of wear displayed no differences from those encountered in Western cultures, the preference for hard or acidic food turn to be the major cause in northwest China. Knowledge of the etiology of such lesions is important for the prevention of further lesions and the termination of the progression of already-present lesions. According to the epidemiological analysis of tooth wear performed in this study, people of various regions need to take appropriate preventive measurements. This study suggests that it is important to protect and prevent the wear of incisors and canines among people who favor the consumption of hard or acidic foods in the northwestern region of China. In addition, further investigation is required to identify the specific risk factors of tooth wear.
Tooth wear index.
We thank the Prosthodontic Department of College of Stomatology of the Fourth Military Medical University for valuable technical support.
- Haugen LK: Biological and physiological changes in the ageing individual. Int Dent J. 1992, 42 (5): 339-348. discussion 349–52PubMedGoogle Scholar
- Bishop K, Kelleher M, Briggs P, Joshi R: Wear now? An update on the etiology of tooth wear. Quintessence Int. 1997, 28 (5): 305-313.PubMedGoogle Scholar
- Molnar S, McKee JK, Molnar IM, Przybeck TR: Tooth wear rates among contemporary Australian Aborigines. J Dent Res. 1983, 62 (5): 562-565. 10.1177/00220345830620051101.View ArticlePubMedGoogle Scholar
- Lopez-Frias FJ, Castellanos-Cosano L, Martin-Gonzalez J, Llamas-Carreras JM, Segura-Egea JJ: Clinical measurement of tooth wear: tooth wear indices. J Clin Exp Dent. 2012, 4 (1): e48-e53.View ArticlePubMedPubMed CentralGoogle Scholar
- Smith BG, Knight JK: An index for measuring the wear of teeth. Br Dent J. 1984, 156 (12): 435-438. 10.1038/sj.bdj.4805394.View ArticlePubMedGoogle Scholar
- Jaeggi T, Gruninger A, Lussi A: Restorative therapy of erosion. Monogr Oral Sci. 2006, 20: 200-214.View ArticlePubMedGoogle Scholar
- Bartlett DW, Lussi A, West NX, Bouchard P, Sanz M, Bourgeois D: Prevalence of tooth wear on buccal and lingual surfaces and possible risk factors in young European adults. J Dent. 2013, 41 (11): 1007-1013. 10.1016/j.jdent.2013.08.018.View ArticlePubMedGoogle Scholar
- Lambrechts P, Braem M, Vuylsteke-Wauters M, Vanherle G: Quantitative in vivo wear of human enamel. J Dent Res. 1989, 68 (12): 1752-1754. 10.1177/00220345890680120601.View ArticlePubMedGoogle Scholar
- Donachie MA, Walls AW: The tooth wear index: a flawed epidemiological tool in an ageing population group. Community Dent Oral Epidemiol. 1996, 24 (2): 152-158. 10.1111/j.1600-0528.1996.tb00833.x.View ArticlePubMedGoogle Scholar
- Mehta SB, Banerji S, Millar BJ, Suarez-Feito JM: Current concepts on the management of tooth wear: part 1. Assessment, treatment planning and strategies for the prevention and the passive management of tooth wear. Br Dent J. 2012, 212 (1): 17-27. 10.1038/sj.bdj.2011.1099.View ArticlePubMedGoogle Scholar
- Van't Spijker A, Rodriguez JM, Kreulen CM, Bronkhorst EM, Bartlett DW, Creugers NH: Prevalence of tooth wear in adults. Int J Prosthodont. 2009, 22 (1): 35-42.PubMedGoogle Scholar
- Bernhardt O, Gesch D, Splieth C, Schwahn C, Mack F, Kocher T, Meyer G, John U, Kordass B: Risk factors for high occlusal wear scores in a population-based sample: results of the Study of Health in Pomerania (SHIP). Int J Prosthodont. 2004, 17 (3): 333-339.PubMedGoogle Scholar
- Donachie MA, Walls AW: Assessment of tooth wear in an ageing population. J Dent. 1995, 23 (3): 157-164. 10.1016/0300-5712(95)93573-K.View ArticlePubMedGoogle Scholar
- Seligman DA, Pullinger AG, Solberg WK: The prevalence of dental attrition and its association with factors of age, gender, occlusion, and TMJ symptomatology. J Dent Res. 1988, 67 (10): 1323-1333. 10.1177/00220345880670101601.View ArticlePubMedGoogle Scholar
- Fareed K, Johansson A, Omar R: Prevalence and severity of occlusal tooth wear in a young Saudi population. Acta Odontol Scand. 1990, 48 (4): 279-285. 10.3109/00016359009005886.View ArticlePubMedGoogle Scholar
- Kelleher M, Bishop K: Tooth surface loss: an overview. Br Dent J. 1999, 186 (2): 61-66.PubMedGoogle Scholar
- Shaw L, Smith AJ: Dental erosion–the problem and some practical solutions. Br Dent J. 1999, 186 (3): 115-118.PubMedGoogle Scholar
- Attin T, Weiss K, Becker K, Buchalla W, Wiegand A: Impact of modified acidic soft drinks on enamel erosion. Oral Dis. 2005, 11 (1): 7-12. 10.1111/j.1601-0825.2004.01056.x.View ArticlePubMedGoogle Scholar
- Bartlett DW, Fares J, Shirodaria S, Chiu K, Ahmad N, Sherriff M: The association of tooth wear, diet and dietary habits in adults aged 18–30 years old. J Dent. 2011, 39 (12): 811-816. 10.1016/j.jdent.2011.08.014.View ArticlePubMedGoogle Scholar
- Moazzez R, Smith BG, Bartlett DW: Oral pH and drinking habit during ingestion of a carbonated drink in a group of adolescents with dental erosion. J Dent. 2000, 28 (6): 395-397. 10.1016/S0300-5712(00)00020-8.View ArticlePubMedGoogle Scholar
- Lobbezoo F, Van Der Zaag J, Naeije M: Bruxism: its multiple causes and its effects on dental implants - an updated review. J Oral Rehabil. 2006, 33 (4): 293-300. 10.1111/j.1365-2842.2006.01609.x.View ArticlePubMedGoogle Scholar
- Pavone BW: Bruxism and its effect on the natural teeth. J Prosthet Dent. 1985, 53 (5): 692-696. 10.1016/0022-3913(85)90026-5.View ArticlePubMedGoogle Scholar
- Christensen GJ: Treating bruxism and clenching. J Am Dent Assoc. 2000, 131 (2): 233-235. 10.14219/jada.archive.2000.0152.View ArticlePubMedGoogle Scholar
- Ibiyemi O, Oketade IO, Taiwo JO, Oke GA: Oral habits and tooth wear lesions among rural adult males in Nigeria. Arch Orofac Sci. 2010, 5 (2): 31-35.Google Scholar
- Eisenburger M, Shellis RP, Addy M: Comparative study of wear of enamel induced by alternating and simultaneous combinations of abrasion and erosion in vitro. Caries Res. 2003, 37 (6): 450-455. 10.1159/000073399.View ArticlePubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6831/14/65/prepub
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.