AN and BN affect hard and soft tissues in various ways. A common dental issues in BN is dental erosion or Perimylolysis ⁸, characterized by ''loss of enamel texture, a silky glossy appearance, and sometimes a dulling of the surface gloss." ⁹ This erosion is associated with excessive consumption of acidic foods such as soft drinks or citrus fruits, but also in concordance with gastroesophageal reflux disease or psychosomatic diseases (anorexia nervosa or bulimia nervosa) ¹⁰.

BN is characterized by self-induced vomiting, where gastric juice with a PH close to 1 reaches the oral cavity, producing an irreversible loss of dentin and enamel in greater proportion. Dentine lesions are frequently found in the lower first molars, while upper central incisors show enamel lesions ¹¹. Even though dental erosion is a usual sign, it has a delayed manifestation, as a long time of regurgitation of the gastric contents is needed to induce these kinds of lesions ¹². The literature is unclear, failing to distinguish between enamel and dentin lesions, making it difficult to assess the severity of erosions and complicating the ability of examiners to monitor the progression of lesions ¹¹.

In a clinical study that evaluated the occurrence, distribution, and severity of dental erosions in patients who experienced bulimia, the results showed dental erosions in 69.7 % of the individuals, with women being the most prevalent. Nineteen of them presented only enamel lesions, and 27 had both enamel and dentine lesions ¹¹. Due to erosion, the destruction of the hard tissue of the tooth is greater, which can lead to other dental injuries such as abrasion or abfraction ¹³.

Oral symptoms related to bulimia nervosa that have been described in case reports, descriptive studies, and case-control studies include enamel erosion, dental caries, dental pain, orthodontic abnormalities, xerostomia, reduced saliva secretion, parotid enlargement, and dysphagia, among others ¹⁴. To properly diagnose and treat these conditions, it is crucial to classify the severity of dental erosion. The scoring system established to identify both early and advanced stages of erosion is Visual Erosion Dental Examination (VEDE) system: Score 0: No erosion; score 1: Initial loss of enamel, no dentine exposed; Score 2: Pronounced loss of enamel, no dentine exposed; score 3: Exposure of dentine, < 1/3 of the surface involved; score 4: 1/32/3 of the dentine exposed; score 5: > 2/3 of dentine exposed¹¹.

This section presents pictures of a 27-year-old patient who had gastric sleeve surgery 9 months ago. Her reason for consultation was severe pain in an ulcerative lesion found on the left side of her hard palate. She reported experiencing six episodes of vomiting daily. The presumptive clinical diagnosis was Necrotizing Sialometaplasia. The patient was informed about the self-limited nature of the lesion. Figure 1; a. Clinical photograph showing a red ulcerative lesion on the left posterior hard palate. No biopsy was performed, and there was an agreement with the patient to return for follow-up appointments. b. Photograph taken with a 10-day interval, c. one-month since the first picture, showing a self-limited type of lesion that resolved completely in two months.

Figure 1 Source: Authors.

Other oral manifestations of eating disorders, either directly or due to nutritional deficiency, include dental caries, qualitative and quantitative salivary changes (xerostomia, altered buffering capacity and salivary pH), gingival and periodontal diseases, and oral mucosal lesions (erythema and palatal ulcers). However, the consequences are not only oral, as these eating disorders can be accompanied by comorbidities such as cardiovascular diseases and dysfunction of the endocrine system, gastrointestinal, pulmonary and musculoskeletal ailments ¹⁷.

Patients with AN and BN can present marginal gingivitis due to a lack of vitamin C, and periodontitis because of poor oral hygiene and micro-nutrient deficiency. In some cases, patients present erythematous lesions and trauma-induced ulcerations in the palate, caused by physical and acidic trauma ¹⁷. Another common sign in these patients is the exfoliation of the mucous membrane of the lips, caused by dehydration, low saliva secretion, and a lack of vitamins A and B ¹³. On the other hand, vitamin D could be included in the treatment of these or other injuries since it is considered a necessary micronutrient to prevent some diseases due to its role in cell proliferation, immunomodulation, resistance to viral infections, and prevention of severe infection symptoms. For example, in COVID-19 or opportunistic infections with the potential to colonize lesions¹⁸, such as lip bites and buccal mucosa biting due to stress tension, as occurs in bulimia¹³.

Dental caries, mainly cervical, and dentinal lesions with large areas of undermined enamel are frequently observed in patients with BN and AN. Patients with ED usually take antidepressants that cause xerostomy as a side effect. Hence salivary viscosity increases and buffering capacity decreases. The low salivary pH promotes the survival of acidogenic and cariogenic microbes (S. mutans and Candida). These factors magnify the risk of demineralization and breakdown of the dental structure. In addition, xerostomia can lead to taste alterations (hypogeusia) and candidal infections, producing angular cheilitis.

Patients with BN can also present Sialadenosis, which may the first noticeable clinical sign. Studies describe the enlargement of parotid glands in bulimic patients, where chronic vomiting is associated with bilateral parotid enlargement ¹⁹. Some patients with BN show slightly elevated levels of serum amylase, probably reflecting an increase in the salivary isoenzyme as a marker along with the particularly marked enlargement of the parotid glands. This last symptom should also alert the dentist during an extraoral examination as an indicator of a probable bulimia patient ²⁰.

Clinical manifestations on teeth include reduced thickness of enamel, increased translucency of the cutting, edges and exposure of the dentin due to the total loss of enamel, causing dentine hypersensitivity ¹⁶. People with eating disorders who suffer from gastrointestinal reflux disease can also suffer from sleep bruxism, causing attrition of occlusal surfaces, and consequently leading to temporomandibular disorders. The TMJ disorders are caused by the lack of stability of the interact contacts and loss of vertical dimension. Patients present a high sensitivity to muscle palpation, prevalence of intensive gum chewing, and high levels of craniofacial pain; all these symptoms are related to the somatization of their anxiety ¹⁷.

Given that oral health is an indicator of the systemic state of illness, it is essential to guarantee the general well-being of patients. In many cases, the oral cavity may be the main site of manifestations of eating disorders, hence the importance of the dentist in the early diagnosis of this underlying systemic pathology through a careful and thorough examination of the oral cavity. This helps to detect the disease early and also saves patients from the consequences of the disease ¹⁷.

Dental treatment for people with disorders such as AN and BN involves discouraging obsessive-compulsive tooth brushing to hide their embarrassment after vomiting episodes or even to induce vomiting. Therefore, tooth brushing should be recommended and limited to a maximum of three times a day ¹⁷. Once the eating disorder has been diagnosed and a subsequent treatment plan has been prepared to recover the damaged dentition (with medical, psychotherapeutic, nutritional advice and dental management) it is necessary to establish treatment plans according to severity. For example, in mild but painful cases due to the loss of exposed enamel and dentin (hypersensitivity), desensitizing agents and direct restorations with composites and glass ionomer cement are applied conservatively. In a more advanced state, removable pros-theses are not the recommended treatment for these patients. The need for computer-assisted restorations arises for the elaboration of porcelain veneers and crowns to restore the vertical dimension in patients with the loss of dental substance in posterior teeth, which implies full dental arch reconstruction. The cost of treatment is another important aspect, as people with eating disorders may face social and economic hardship. Mainly because studies have reported a high proportion of unemployment in people with eating disorders due to psychiatric problems ¹⁷.

A study of the German health system carried out a cost compensation analysis for the treatment of eating disorders, based on evidence, and using data from the results of a psychotherapy trial involving cognitive behavioral therapy and focal psychodynamic therapy. Since AN and BN are associated with a very high level of suffering for afffected patients, the need to establish an adequate and early treatment based on evidence is necessary and needs to be included in public health services to generate a reduction in costs and a better quality of life for patients, since the greater use of medical care services by these patients results in longer hospital stays²¹.

Eating disorders represent a serious public health problem, raising direct and indirect costs. Direct costs related to the prevention, diagnosis, and treatment of a mental health disorder, and indirect costs the payment of sickness benefits or loss of productivity. To evaluate all of this, a formula is generated which includes the consequences of the lack of treatment and therapy for AN and BN. In addition, the improvement in the quality of life and the reduction in the risk of mortality derived from the treatment are taken into account, leading to the conclusion that treating with evidence generates several types of savings, for example, the reduction of the loss of gross value, savings due to cost of individual therapy sessions per patient, savings due to improvement in quality of life, savings due to reduction in days of hospitalization, and savings due to reduction in mortality²¹.

Currently, over the last 10 years, a stable incidence of AN is reported; however, in the younger population group (<15 years), it has increased. This implies the need to investigate risk factors and highlights the need for prevention programs. When we talk about the incidence of BN, we know that it has decreased in the general population over time. In addition, recent studies suggest that not only for AN the mortality risk is five or more times elevated, but also for BN. In terms of incidence, it is not known whether it has actually increased or if the changes in case detection systems, diagnostic criteria, increased availability of treatment facilities, or heightened awareness have lead to early detection and referral. Without forgetting the changes that can occur in the incidence due to variations in the study methods or differences in the stage of detection. When we talk about mortality, it is suggested that men are at greater risk, highlighting the importance of detection and treatment of anorexia nervosa and bulimia nervosa in men ²².

A study carried out in 2019 evaluated self-perception and oral health in a population of anorexic and/or bulimic patients in which 46 individuals participated. Prior to teaching dental health, a knowledge survey showed that, although most patients were aware that dental erosion was a consequence of their health situation, only 30 % knew the exact location of the erosion. However, after the teaching process, which lasted 6 weeks, 73 % of the patients were able to correctly identify the erosion site, demonstrating an improvement in their knowledge and the teaching being fruitful. Additionally, an increase in patients who went to the dentist was reported. This positively influenced the patient's self-perception and self-esteem ²³.