Malocclusion and its relationship with oral health-related quality of life in patients with eating disorders

ABSTRACT Objective: To evaluate the prevalence and severity of malocclusion and its impact on oral health-related quality of life (OHRQoL) and self-reported satisfaction of patients with anorexia and bulimia nervosa. Methods: The sample consisted of sixty women who attended a specialized mental health clinic of a Brazilian medical school. Participants were distributed into two groups: patients with anorexia and bulimia nervosa (ABN; n=30) and control patients without eating disorders (CN; n=30). The dental occlusion was evaluated by the Dental Aesthetic Index; the OHRQoL was assessed using the OHIP-14 questionnaire; and the self-reported satisfaction with the appearance of teeth, speech ability and chewing was obtained by interviews. Results: Severe and very severe malocclusion were observed in 26.67% and 46.67% of patients in the ABN group, respectively, while the CN group showed 80.00% of patients without abnormality/mild malocclusion. ABN group showed a higher proportion of patients (p < 0.05) with tooth loss, spacing in the region of incisors, maxillary misalignment, and mandibular misalignment in relation to CN group. ABN group presented lower (p< 0.05) OHRQoL and self-reported satisfaction with the appearance of teeth, speech ability and chewing, compared to the CN group. There was a significant positive correlation (p< 0.05) between the Dental Aesthetic Index and OHIP-14 scores in the ABN group. Conclusions: The prevalence of severe malocclusion in ABN group was high, with a negative impact on OHRQoL and self-reported satisfaction with the chewing ability, speech ability and appearance of teeth.


INTRODUCTION
Anorexia and bulimia nervosa are eating disorders characterized by fear of gaining weight, extreme eating behaviors aimed at reducing weight and marked distortion of body self-image. 1 These conditions may be associated with alterations in mental, systemic and oral health, and the understanding of its effects, as well as the control and treatment of these complications are of fundamental importance, since they may present relevant repercussions on the quality of life and in the treatment of eating disorders. 2 Eating disorders are characterized by changes in eating behavior that may be associated with damage to dental tissues and impairment in oral health. 3 The most commonly observed oral changes are dental erosion, tooth sensitivity, dental caries, decreased salivary flow and gingival bleeding. [4][5][6][7] These changes may be related to an imbalance in dental occlusion, and may contribute to the development of malocclusion and impairment of dental aesthetics, functional performance, as well as systemic health. 8 Orthodontic treatment aims to reestablish oral function and health as a final objective, however, the psychological and social effects of orthodontic interventions represent important reasons for seeking treatment. 9 Chiba FY, Chiba EK, Moimaz SAS, Matsushita DH, Garbin AJI, Garbin CAS -Malocclusion and its relationship with oral health-related quality of life in patients with eating disorders 5 In this context, it is important to consider the impact of malocclusions on quality of life, since these conditions may be related to impairment of speech and chewing functions, impair the psychological and social condition of individuals and influence the degree of satisfaction with oral condition. 10 In addition, it is known that individuals with anorexia and bulimia nervosa present poorer quality of life, compared to individuals without eating disorders. 11 Considering that oral health is an important component that interferes with quality of life and the scarcity of studies about malocclusions in individuals with eating disorders, this study aimed to evaluate the prevalence and severity of malocclusion and its impact in the oral health-related quality of life (OHRQoL) and the self-reported satisfaction of patients with anorexia and bulimia nervosa.

MATERIAL AND METHODS
This quantitative cross-sectional study was performed on patients attended in a specialized mental health clinic of a Brazilian medical school, in 2018. The sample consisted of sixty women distributed into two groups: control patients without eating disorders (CN group; n=30) and patients with medical history of anorexia and bulimia nervosa diagnosed by psychiatrists of a specialized mental health clinic (ABN group; n=30). Chiba FY, Chiba EK, Moimaz SAS, Matsushita DH, Garbin AJI, Garbin CAS -Malocclusion and its relationship with oral health-related quality of life in patients with eating disorders 6 The ABN group included individuals who met the following eligibility criteria: patients with current diagnosis of eating disorders and patients who did not abandon the psychiatric treatment. Exclusion criteria were applied to both groups as follows: patients with a history of accidents that resulted in tooth loss and patients who were currently undergoing orthodontic treatment.
The sample size was determined based on data from a pilot study, considering the estimated proportion of malocclusion as the primary outcome. It was used a Z-test applied for two proportions, with a reliability of 95%, a margin of error of 5%, and a test power of 80%, resulting in a minimum sample size of 27 participants per group. All patients with eating disorders undergoing treatment at the Specialized Mental Health Clinic were invited to participate in the research, totaling 30 patients in each group. Participants in the CN group were selected from the companions of patients in the ABN group following a psychiatric consultation. This was done to maintain sample homogeneity and avoid bias, due to significant differences in socioeconomic characteristics between groups. The patients who agreed to participate in the study were submitted to oral clinical examination, evaluation of the oral health-related quality of life and assessment of self-reported satisfaction with the appearance of teeth, speech ability and chewing.

ORAL CLINICAL EXAMINATION
The Dental Aesthetic Index (DAI) was used to evaluate the prevalence of malocclusions, its severity and the need for treatment. 12 The examinations were carried out in the specialized mental health clinic of the medical school, in isolated rooms with good lighting conditions, using a chair, a mouth mirror and a WHO periodontal probe. The data were collected by a blind previously calibrated single dental surgeon. The calibration process consisted of a theoretical study involving the study of the DAI index and the performance of clinical examinations. The Kappa test for occlusal condition assessment was performed to verify intra-examiner agreement, and a value of 0.90 was obtained.

EVALUATION OF ORAL HEALTH-RELATED QUALITY OF LIFE (OHRQOL)
OHRQoL was evaluated by the OHIP-14 questionnaire. 13 The questionnaire contains 14 questions and evaluates seven dimensions of the impact of oral conditions on individual's quality of life, including functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and handicap. The response format follow a Likert-type frequency scale, as described: never = 0, hardly ever = 1, occasionally = 2, fairly often = 3, and very often = 4.
The additive method was used to calculate the score of each dimension. Thus, the OHIP-14 score for each of the seven dimensions ranged from 0 to 8, with higher scores indicating a poorer OHRQoL.

ASSESSMENT OF SELF-REPORTED SATISFACTION
A structured questionnaire was used to assess patients' satisfaction with the appearance of teeth, speech ability and chewing. Answers were classified into two categories: satisfied (satisfied and very satisfied) and dissatisfied (dissatisfied and very dissatisfied).

STATISTICAL ANALYSES
The data about the occlusal condition, orthodontic treatment need, OHIP-14 score, and self-reported satisfaction were described by using descriptive statistics. The values of age, Dental Aesthetic Index score and OHIP-14 score for each dimension were analyzed for normality using the Shapiro-Wilk test, and the Mann-Whitney test was used to compare the groups. The correlation between Dental Aesthetic Index score and total OHIP-14 score was analyzed by the Spearman correlation test. Two-proportion test was used to compare the proportion of patients with very severe or disabling malocclusion, and patients with occlusal alterations according to the Dental Aesthetic Index criteria. The chi-square test was performed to evaluate the association between eating disorder and the degree of satisfaction with speech ability, chewing ability and aesthetic appearance of teeth. The results were expressed as the mean ± standard deviation, and differences between groups were considered significant at p < 0.05. Data analysis was performed using GraphPad Prism 7.0 software.

RESULTS
There was no difference in the age between groups (CN group = 28.93 ± 9.77; ABN group = 31.13 ± 12.72). Table 1  It was observed that the ABN group showed a significantly higher (p<0.05) Dental Aesthetic Index score and total OHIP-14 score compared to the CN group (Table 3). There was a significant positive correlation (r=0.8461; p<0.0001) between the DAI score and the OHIP-14 score in the ABN group.   The ABN group presented significantly higher scores (p<0.05) in the dimensions of functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and handicap, compared to the CN group (Table 4).
It was observed that the degree of satisfaction with the oral condition was worse in the ABN group when compared to the CN group. There was a significant association between the presence of eating disorders and dissatisfaction with speech ability (p<0.0001), chewing ability (p<0.0001) and aesthetic appearance of teeth (p<0.0001) ( Table 5).

DISCUSSION
In this research, it was observed that the ABN group presented a worse occlusal condition evaluated using the Dental Aesthetic Index, and poorer oral health-related quality of life, as assessed using the OHIP-14 questionnaire. These changes were accompanied by decreased self-reported satisfaction with speech ability, chewing ability and aesthetic appearance of teeth.
It was observed that data related to age were similar between the two groups. Thus, it is possible to suggest that the differences in the occlusal condition, oral health-related quality of life, and self-reported satisfaction observed in the present study were not caused by this variable.
Eating disorders can negatively affect the oral condition of patients and are associated with the development of dental caries, dental erosion, hyposalivation, and gingivitis. 3,14 Excessive consumption of carbonated drinks as appetite suppressants, gastric reflux, frequent self-induced vomiting and nutritional deficiency may contribute to the development of these changes. 15  presence of orthodontic abnormality was not associated with reports of self-induced vomiting, which suggested that digital pressure was not the causal factor.
The progression of dental caries and periodontal disease can lead to tooth loss and is associated with malocclusion. 17,18 Indeed, in the present study, it was observed that a great pro- The present results are in agreement with studies that verified that malocclusion is associated with reduced speech capacity and lower efficiency of chewing ability, highlighting that orthodontic deviations should be considered in oral health planning, to identify risk groups and to improve health services. 26,27 The relationship between malocclusion and the lower degree of satisfaction with the aesthetic appearance of teeth has been reported in previous studies, considering that orthodontic treatment may improve body image and, especially, facial image. 26,28 Restoration of weight and nutritional status are key elements in the treatment of eating disorders. 29 In this context, the data about self-reported satisfaction with chewing ability, functional limitation, physical pain and physical disability revealed a worrying situation. It was observed that patients of the ABN group presented unsatisfactory diet, need to interrupt meals, chewing discomfort and worsening in sense of taste due to oral problems. Systematic review has shown that malocclusions cause a decrease in masticatory performance, especially in relation to the reduction of occlusal contact area. 30 Thus, it is possible to suggest that the occlusal condition may have an important negative impact on the nutritional rehabilitation of patients with anorexia and bulimia nervosa.
In this research, all patients in the ABN group who agreed to participate in the study were female. Thus, to maintain the homogeneity of the sample, men were also not included in the CN group. However, even though the sample is composed only of women, this research presents significant results because the literature demonstrates that eating disorders have greater prevalence in women than in men 2,4 . In a cross-sectional study, the outcome and the exposure factor are evaluated simultaneously, so that it is not possible to evaluate possible local etiological effects acting over a period of time, which can be considered a limitation of the present study.