The meta-analysis by Kisely et al. «Kisely S, Baghaie H, Lalloo R, ym. Association bet...»1 included 10 case-control studies. Four studies were from Nordic countries, two from England, and one study each from Australia, Israel, Germany, and the USA. Data for meta-analyses were available for 556 patients with eating disorder and 556 controls. Gender data were available for 868 participants, of whom 852 (98%) were female. The most common diagnosis was bulimia nervosa, followed by anorexia nervosa and eating disorders not otherwise specified. Age of the participants ranged from 10 to 50 years.
Included studies assessed the oral health of people with eating disorders and included a control group of people without eating disorders, ideally matched by age, gender, socioeconomic status and education level. Psychiatric status could be determined by clinical diagnosis or diagnostic criteria. Studies of people with severe mental illness, primary alcohol or substance use disorders, intellectual disability and other psychological disorders were excluded, as were studies of other dental outcomes than dental erosion, decay and salivary gland function.
Six studies defined psychiatric caseness using diagnostic criteria such as the DSM or ICD by clinical assessment. One further study assessed the presence of morbidity using the Eating Disorders Inventory and Examination, as well as the Eating Attitudes Test. Controls were as follows; three recruited dental patients, and the remainder used staff or university students. In one study the source of controls was not stated. One study excluded the presence of eating disorders in the control group through the use of a standardised questionnaire, whereas another asked about past psychiatric history. In terms of group comparability, all the studies either used age- and gender-matched controls or checked that there was no significant difference between the two groups at baseline. Two studies checked that participants in the eating disorder cases and control groups were of similar socioeconomic status, and a third that they were similar in terms of ethnicity and medical history.
The primary outcome of this study was dental erosion. The area worst affected in the mouth determined the overall score of dental erosion. Secondary outcomes were dental decay and salivary gland function. The total number of teeth (T) and surfaces (S) that were decayed (D), missing because of pathology (M) or filled (F) were measured to as the DMFT and DMFS respectively. Salivary gland function was assessed where possible by measurement of unstimulated salivary flow, otherwise by report of dry mouth by the patient.
Participants with an eating disorder had five times the odds of dental erosion (OR 5.00, 95% CI 3.31–7.58) compared with controls. Patients with self-induced vomiting had the highest likelihood (OR 7.32) whereas those without vomiting had the lowest (OR 3.10), although this still remained significantly greater than for controls (95% CI 1.67–5.77). Limiting the analyses to include only studies that used diagnostic criteria to define the psychiatric cases did not change the results (OR = 4.95, 95% CI 3.13–7.84). Likewise, limiting the analyses to studies that were clearly restricted to outpatients made no difference to the results (OR = 3.75, 95% CI 2.11–6.70).
Patients with an eating disorder had non-significantly more decayed, missing and filled surfaces than controls (OR 4.10, 95% CI 0.93-7.27). The study that used the DMFT reported no difference (OR 3.07, 95% CI 0.66-5.48); it was confined to non-vomiting patients. Five studies assessed salivary gland function in terms of dry mouth or reduced salivary flow and there was a significant association with eating disorders (OR 2.24, 95% CI 1.44, 3.51)
Ascertainment of oral status in all the studies was by trained dental examiners. In the case of erosion, this was a clinical assessment sometimes guided by an established classification. Five studies supplemented the clinical examination with dental impressions, radiographs and/or intraoral photographs. In the case of caries, all the studies used some or all of the Decayed, Missing and Filled classification. In two studies, radiographs and/or intraoral photographs were also taken. Five studies assessed salivary gland function, and saliva flow was measured in all cases.