The prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Southern China

Dental erosion is defined as the loss of hard dental tissue due to the chemical influence of extrinsic and intrinsic acids without bacterial involvement [1]. It is becoming an increasingly important factor when considering the long-term health of the dentition. If dental erosion is not controlled and stabilized, the child may suffer from severe tooth surface loss, tooth sensitivity, over closure, poor aesthetics, or even dental abscesses in the affected teeth [2]. Erosive lesions frequently require preventive and restorative treatments, which will add the family and government's public health burden. The etiology of dental erosion is multi-factorial and not fully understood. Currently, the increased consumption of acidic foods and carbonated beverages is becoming an important factor in the development of dental erosion [3]. The acidic attack leads to an irreversible loss of dental hard tissue, which is accompanied by a progressive softening of the surface [3].

The sample age in studies of the prevalence of dental erosion was 3-50 years old [4]. Many studies have focused on 12-year-old children (Table 1) because the permanent incisors and first molars of children at this age have been exposed to potential etiologic factors in the mouth for a considerable duration compared to other teeth. Furthermore, the differentiation of erosion from attrition or abrasion is easier at this age compared to adults.

The objective of the present study was to evaluate the dental erosion status among 12-13-year-old school children in Guangzhou, Southern China, including the prevalence, distribution, and severity of dental erosion in the permanent dentition at the tooth and surface level. This investigation also aimed to explore the associated socioeconomic and behavioral risk factors influencing the prevalence of dental erosion.

The prevalence of dental erosion of 27.3% in the current study was similar to the results of Caglar et al. [10] and Correr et al. [11], which indicated that 28% of 11-year-old children and 26% of 12-year-old children had permanent teeth affected by erosion, respectively. However, the prevalence ranging from 11.6%-100% was determined during recent surveys on the permanent dentition of children in different countries (Table 1). The variation in prevalence among these studies may be partially explained by differences in the diagnostic criteria and indices. Furthermore, socio-economic, cultural, and geographic factors could influence the outcome of prevalence data.

The central incisors in the upper and lower jaws were affected predominantly, followed by the lateral incisors. The first molars in the upper and lower jaws were less affected by erosion. The upper central incisors of children were usually reported to be frequently affected by erosion [12–14]. In our study, the lower central incisors were affected predominantly as well. Both the upper and lower incisors are located in the front of the oral cavity, which predisposes these teeth to erosion by extrinsic acids, such as acidic beverages. Moreover, the lower central incisors are the first erupting teeth, which are exposed to erosive challenges for a longer period of time. These may be the possible reasons for this finding.

The most frequently affected surface was the incisal or occlusal only (43.2%) for all teeth, followed by the labial and incisal/occlusal surfaces. Al-Majed et al. [8] also determined that 91% of dental erosion occurred on the incisal/occlusal surfaces of 12-14-year-old Saudi boys. The results of other surveys varied. For example, Auad et al. [12] and Mangueira et al. [15] reported that the palatal surfaces were the most affected. The consumption of erosive drinks and food was also shown to be strongly associated with erosion on the facial and occlusal surfaces, while severe palatal erosion occurred infrequently and were highly associated with chronic vomiting [16]. The predominant affected surfaces of erosion on the incisal/occlusal might result from these tooth surfaces being predisposed to physical impacts from mastication, which promotes the effect of erosion. Although distinguishing erosion from abrasion/attrition in the incisal/occlusal surfaces at the late stages of primary and permanent dentition is difficult, the dentition of 12-13-year-old children is during the early stages and the appearance of the incisal/occlusal surfaces as grooving/cupping is mainly due to erosion [17]. According to the differential diagnosis of dental erosion proposed by Gandara et al. [18], incisal surface contour appearing flat and shiny was defined as abrasion or attrition and was not included in the records in our study.

The severity of erosive lesions in our study demonstrated that the loss of enamel contour occurred most frequently (54.6%), and only a small proportion of tooth surfaces were affected with dentine exposure (1.4%). Several surveys found that all affected children of their study samples exhibited erosion with no exposed dentin. Peres et al. [19] reported that enamel loss was the most prevalent type of dental erosion for 12-year-old school children in Brazil. However, Al-Majed et al. [8] examined 862 Saudi Arabian boys 12-14 years of age, and 26% of these children exhibited pronounced dental erosion (erosion into the dentin or pulp). The frequent ingestion of carbonated soft drinks at nighttime could contribute to the high percentage of pronounced dental erosion in these Saudi boys.

Associations between dental erosion and the variables under study were investigated through processes of bivariate and multivariate analyses. A logistic regression analysis contributed to eliminate confounding factors that may mask an actual association or falsely demonstrate an apparent association between the study variables. The results of logistic regression analysis demonstrated that the gender of the children, frequency of consumption of carbonated drinks, and the level of education of the mothers were independent risk factors for dental erosion in school children of Southern China.

A significantly higher prevalence of dental erosion was found in girls (29.9%) than in boys (25.7%), which is in agreement with the results of previous investigation of 12-year-old Cuban children by Künzel et al. [20]. However, several surveys had found a significantly higher prevalence in boys than in girls [21, 22], while Correr et al. [11] and Peres et al. [19] found no difference between the genders. In the present study, there was no significant difference in the frequency of consumption of carbonated drinks between the genders. Girls ate more succade and fruit, and were more likely to suck drinks than boys, but these variables had no significant difference between children with and without dental erosion. These results indicate that the reason of gender difference in the occurrence of dental erosion was not clear and further studies are necessary on this issue.

In the literature, the influence of socio-economic status is somewhat conflicting [9, 23]. Children whose mothers had higher levels of education exhibited fewer lesions, which is in agreement with the study by Harding et al. [23]. Some studies reported no relationship between erosion and social class based on the occupation of the father and education of the mother [9]. In this study, the relationship between the level of education of the mother and the presence of erosion in the children may be due to the influence of the level of education on the lifestyle of the family. Mothers who had higher levels of education may have more knowledge of oral hygiene and better oral health habits.

The frequency of consumption of carbonated drinks was significantly related to dental erosion in the present study, which supported the results of previous surveys [24–26]. Daily fluid consumption is high due to the hotter climate in Guangzhou, particularly the consumption of carbonated soft drinks, which are becoming increasingly available at a reasonable cost and are popular due to their taste. Outputs of carbonated drinks in the Guangdong province increased to approximately 2 billion litres (22.7% of the total output in China) from January - October 2007, and ranked first of all 31 provinces/municipalities [27]. A recent study performed in seven cities of China, including Guangzhou, reported that carbonated drinks were still the predominant beverage preferred by school children. The frequency of consumption of carbonated drinks has increased greatly compared to 8 years ago [28]. There is a need for intervention programs aimed at the increasing consumption of soft drinks among school children in China, such as a media campaign, classroom workshops, school meal modification, and parental support.

The present study had limitations because of recall bias, the cross-sectional study design, and the relatively small sample size of suburban residents. Standardization of the indices and the teeth examined would facilitate the comparisons of different studies. More research should be done to determine the differences in tooth erosion and the main risk factors between urban and rural children. The prospective epidemiologic design will be of benefit for elucidation of the risk factors of the disease.

Our study provides evidence that dental erosion is becoming a significant problem in Chinese school children. Dental erosion should receive more attention that promotes awareness in dentists to make an early diagnosis and to evaluate the different etiologic factors that identify children at risk in China. Children who were female, consumed carbonated drinks once a week or more, and had mothers that were educated to the primary level tended to have more dental erosion. A strategy of offering preventive care, including more campaigns promoting a healthier lifestyle for those at risk of dental erosion, should be conducted for school children and their parents in China in order to reduce the medical burden of the government and families.