More than half of the university students aged 19–24 years who participated in this study had dental erosion. Unfortunately, limited data are available on the prevalence of tooth erosion among young adults in Malaysia. Although it is difficult to accurately compare the results of this study with other prevalence studies due to the differences in the indices used, the study criteria, the diagnostic criteria, and the tooth surfaces examined, it appears that the prevalence of tooth erosion in this study is greater than that reported by an aforementioned local study among adults in Kelantan (21
), among university students in the United States of America (36.5%) (19
) and among adults aged 26–30 years in Switzerland (29.9%) (20
). Tooth erosion was reportedly higher (77%) among Saudi military men similar in age to the participants in our study (19–25 years old) (30
). In the present study, there was no significant difference in the proportion of tooth erosion between genders, ethnic groups, or parental education levels. A study among adolescents aged 13–14 years in Brazil (18
) also reported that gender and socio-economic class were not significantly associated with the risk of tooth erosion.
Our study found that there were no relationships between tooth erosion and the frequency and amount of acidic foods and drinks consumed. Tooth erosion is more frequently reported to be associated with acidic drinks among children (31
), adolescents (5
) and adults (15
) when the consumption was high, and the association is not reported in children (3
) when the consumption was low. In our study, the proportion of subjects who reported frequently consuming acidic drinks was too small to show a significant association with tooth erosion occurrence.
Another potential explaination for why dietery habits were not found to have any significant association with tooth erosion is that the study was cross-sectional, and therefore only assessed dietary patterns 1–2 months prior to the study. Dietary patterns during data collection may not have been the same as the dietary patterns when tooth erosion occurred. Moreover, tooth erosion is a progressive disease resulting from frequent and prolonged exposure to acidic food items. Finally, the risk of tooth erosion is multi-factorial in nature and is influenced by the tooth composition and structure and the saliva composition (31
), which we did not examine in this study due to financial and time constraints.
The present study found that the amount of acidic fruits consumed was not associated with the occurrence of tooth erosion. This finding is consistent with previous studies (34
). Associations between fruit consumption and tooth erosion were reported only in studies when consumption was excessive. In case-control studies, a considerable risk of erosion has been reported when citrus foods were eaten more than twice per day (10
). Less than half of the subjects in the present study consumed fruits 4 to 5 times per day, with a median intake of 56 g among subjects with erosion and 46 g among subjects without tooth erosion. Fruit juices are more likely to initiate tooth erosion compared with fruits themselves (37
). However, we did not find a significant association between fruit juices and tooth erosion in this study (P
= 0.268), which may be because the majority of subjects reported low fruit juice and acidic food intake.
In the present study, we found that the occurrence of tooth erosion was lower among subjects who reported greater milk consumption. One study (31
) indicated that children and adults with erosion drank milk significantly less than children with no erosion. Laboratory studies have demonstrated that milk is protective against tooth erosion due to its high concentration of calcium. The calcium and phosphate in foods may have a protective effect against erosion on tooth enamel. Calcium is crucial for dental health because it helps to maintain the teeth’s mineral composition in the process of demineralisation and remineralisation, which depends on dietary factors, pH, and the oral environment (2
). Cow’s milk has been demonstrated to strengthen tooth enamel by re-hardening it after exposure to acidic drinks (4
). Milk consumption among all subjects in this study was low, with a median daily consumption of 4 mL/day among subjects with tooth erosion and 46 mL/day among subjects without tooth erosion. Low consumption of milk by the subjects in this study is in agreement with data from the national survey among adults in Malaysia in 2006; the survey reports that the average milk consumption among adults was 0.14 servings per day, compared with the recommendation of 1 to 2 servings per day (39
). Only 17.1% of adults in this population consumed milk 1.4 times daily (39
). According to the Recommended Nutrient Intake Malaysia, adults aged 19 to 65 years should consume 800 mg of calcium per day, and the Malaysian Dietary Guidelines recommend 1–3 glasses of milk as part of a balanced diet (40
). The association between the risk of having tooth erosion and milk consumption was not significant when other confounding factors were taken into account. This may be because milk consumption was low among our participants.
The present study found that tea and coffee consumption greater than 150 mL/day was associated with a reduction in the risk of tooth erosion to 42% after other confounding factors were taken into consideration. We asked the subjects in this study to recall the frequency and amount of tea and coffee consumption, but we did not specifically ask them to recall these beverages separately. We also did not ask the participants to specify whether they added milk, sugar, or both to their coffee/tea. It is possible that some subjects in this study added milk to their coffee or tea, which may have provided a protective effect. In addition, it has been reported that tea has a complex composition, and its consumption has been recognised as having some beneficial dental effects because of its appreciable fluoride content (41
). Although tea is acidic, with a pH of 4.9, it only reduces 1 pH unit on the tooth surface, and resting pH levels are restored within approximately 2 minutes after drinking (44
). Despite the possible advantages of tea, excessive consumption may lead to problems of staining of the dentition. In addition, among groups at risk of iron deficiency, such as young infants and the elderly, excessive consumption of tea should be avoided to prevent possible effects on intestinal mineral absorption. We could not find any evidence to indicate any potential protective effects of drinking coffee on tooth erosion. Further studies are highly recommended to test and clarify this finding.
The present study found that the frequency of yogurt consumption was not associated with tooth erosion. Yogurt reportedly contains high amounts of calcium and phosphate, but it is also an acidic food (16
). A laboratory study (45
) indicated that yogurt has no erosive potential on enamel, although it can induce the deposition of hydroxyapatite and fluorapatite, components of tooth enamel.
Subjects who reported that they had not received dietary information about healthy eating were significantly more likely to have tooth erosion compared with their counterparts. More than two-thirds of subjects reported that their most recent dental check-up was more than 6 months before the study was conducted, which indicates that dental healthcare awareness should be promoted. In this study, subjects reported that parents, relatives/friends, and television/magazines were the primary sources of dietary advice related to dental health. This indicates that dental health promotion should be channelled through parents and media to reach out to this age group. Dentists, nutritionists, and dieticians should play an important role in promoting healthy eating to maintain dental health.
Our study did not specify whether acidic foods and drinks were consumed as a meal or as a snack. Acidic foods and drinks are recommended to be consumed with meals to reduce the risk of tooth erosion, as saliva flow is high during meal time (38
). In addition, the consumption of acidic drinks with swishing, holding, sipping, or using a straw was not specifically addressed in the questionnaire, which may have been very useful to study (46
). This study was conducted at one of the universities in Malaysia; thus, the results of this study may not be representative of the tooth erosion occurrence and dietary patterns of the general population, due to educational status, individual preferences, and lifestyle differences. This study should be replicated using a larger sample size including subjects from a wider age range and across multiple ethnic groups. Despite these limitations, outcomes from this study have highlighted several points. First, a high occurrence of tooth erosion among young adults at the university should be addressed through oral health promotion. Second, the study supports the importance of the dietary aspect in managing tooth erosion; thus, feasible means of integrating dietary education into the dental setting and mainstream media warrants further investigation. Finally, our study demonstrates the complexity of the interaction between diet and tooth erosion in humans, as well as the need for further epidemiological studies with large, random populations.