Background

Eating disorders are serious psychiatric illnesses with substantial morbidity and mortality, causing significant disturbances in somatic health and psychosocial functioning [1,2,3]. Research on the somatic effects of eating disorders indicates that they impact all body systems and include conditions ranging in severity from vitamin deficiencies to potentially fatal electrolyte imbalances and hypoglycemia [4]. Internationally, the findings from medical research have been translated into screening and treatment guidelines for providers by professional organizations in eating disorders, psychiatry, other medical specialties, and government bodies [5,6,7,8,9,10]. While screening and treatment guidance for many sequalae include specifics such as laboratory testing, observable physical signs, and treatment interventions, the guidance related to oral health is notably sparse or absent from many of the guidelines. Often, the only mention of oral health is the recognition that self-induced vomiting may cause dental erosion and the recommendation for eating disorder professionals (e.g., therapists, nutrition professionals, nurses, physicians who treat individuals with eating disorders) to refer someone who is vomiting to an oral health provider (OHP) such as a dentist or dental hygienist. Notably absent is guidance about when to refer patients to OHPs. This omission is particularly problematic given that eating disorder professionals report dissatisfaction with their level of oral health education, and thus tend to wait until a patient reports complications [11]. Guidance for OHPs on the recognition and clinical care of someone with an eating disorder is even more sparse.

Across health conditions, it is widely understood that early identification and intervention leads to better health outcomes. The same is true for people with eating disorders. The paucity of guidance regarding the link between oral health and eating disorders means that health conditions are not addressed until the impact is severe. A significant benefit of early intervention is that it decreases the time of untreated illness [12], which is associated with positive outcomes such as shorter time to remission [13]. Despite this opportunity, medical education regarding eating disorders is limited. In a study of 637 U.S. medical education residency programs in internal medicine, pediatrics, family medicine, psychiatry, and child and adolescent psychiatry, 514 did not offer any rotations for eating disorders. In the 123 programs with rotations, only 42 had a formal, scheduled rotation [14]. A study of Canadian medical residents found that participants had, at most, 5 h of training on eating disorders; those who had such training reported comfort with screening for and assessing eating disorders, but a lack of comfort with medical management. An evaluation of the residents’ knowledge of assessment and treatment of eating disorders supported that they had sufficient knowledge of assessment practices but were not well-versed in management and treatment [15]. Medical education in the United Kingdom is similarly lacking in education about eating disorders. A 2018 study noted that most physicians receiving < 2 h of instruction across 10–16 years of training. Additionally, eating disorders are absent from the curricula of 20% of medical schools, and < 1% of students have access to specialty clinical experiences [16].

Given the particular effects of eating disorders on oral health, and the opportunity for oral health providers to play an instrumental role in early detection of eating disorders, the purpose of this study was to assess the status of research on clinical implications and provider education about eating disorders for oral health providers. Additionally, as the reported rates of eating disorders education and training are generally low, the question remains whether such training is provided for OHPs given the high rates of oral health symptoms that individuals with eating disorders experience. Presently, there is limited research on oral health and eating disorders, with existing systematic reviews focusing on clinical presentation. The primary aim of this study is to examine the literature on eating disorders and oral health broadly to capture clinical research (e.g., effects of eating disordered behaviors on oral health and treatment strategies) and topics such as dental education and training.

Methods

A scoping review was conducted to identify key concepts, sources of evidence and research gaps at the intersection of eating disorders and oral health. Scoping reviews are appropriate in cases where there is uncertainty about the breadth of the literature on a topic. Accordingly, the study was conducted with the methodology and guidance in Peters et al. and from PRISMA [17, 18]. A search was conducted in Pubmed, Embase, Google Scholar, the Journal of the American Dental Association and Science Direct. Search terms included “Eating Disorder”; “Eating Disorders”; “Disordered Eating”; “ED”; “EDs”; “ED's”; “Anorexia”; “AN”; “Bulimia”; “BN”; “EDNOS”; “Binge Eating Disorder”; “Restrictive Food Intake Disorder”; “ARFID”; “Rumination Disorder”; “Other Specified Feeding or Eating Disorder”; “OSFED”; “Unspecified Feeding or Eating Disorder”; and “UFED”. These terms were combined with the additional terms “Dentist”; “Dentists”; “Dental”; “Dentistry”; “Oral Hygiene”; “Hygienist”; “Hygienists”; “Oral Health”; “Caries”; “Cavity”; “Cavities; Teeth”. MeSH and Emtree terms included “Feeding and Eating Disorders”[Mesh]) AND “Oral Health”[Mesh] Emtree terms: ‘dentistry’/exp/mj AND ‘eating disorder’/exp/mj. Articles were eligible for inclusion if they were written in or translated into English, published in peer-reviewed journals, and had a publication date after the year 2000. The year 2000 was selected for three reasons. First, to capture research from the current century. Second, knowledge of eating disorders had spread beyond the mental health fields such that it would be feasible to capture research in a broader range of disciplines. Finally, the expansion in internet use at the turn of the century and growth technology would ensure that we were identifying current trends in education and training. Full inclusion and exclusion criteria are provided in Table 1. Two members of the study team reviewed all studies independently and any disagreements were discussed to reach consensus. For each article meeting inclusion criteria, data were extracted for: (1) country in which data were collected, (2) primary study aim, (3) study design, (4) included eating disorder diagnoses, and (5) findings.

Table 1 Inclusion and Exclusion Criteria
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Results

An initial 178 articles were identified from the search terms (Fig. 1). After removal of duplicates, 147 titles and abstracts were screened for inclusion. A total of 93 articles were sought for retrieval, with 21 not retrieved due to a lack of full-text availability. Of the remaining 72 articles, 20 were excluded as not original research, 4 lacked an English language version, and 3 were excluded because they were not relevant to oral health and eating disorders. Forty-four studies were retained for inclusion (Table 2). Of these 44 studies, seventeen related specifically to oral health professionals [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35], twenty addressed the impact of eating disorders on oral health [36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55], and seven focused on patient experiences and perspectives [56,57,58,59,60,61,62].

Fig. 1
figure 1

From: Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. https://doi.org/10.1136/bmj.n71

PRISMA flow diagram of study selection.

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Table 2 Articles included in the scoping review
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Oral health professional education and training

The 17 articles about oral health professionals fell into three overarching categories: knowledge, education, and practices.

Seven of the articles assessed OHPs’ knowledge of the oral health signs of eating disorders, symptoms of eating disorders, how to raise concerns with a patient, and where to refer a patient for treatment if necessary. Of these seven articles three studies included dentists and dental hygienists [19, 27], three included dentists only [26, 28], one included hygienists only [22], and one included a random sample of dental practices. All studies were conducted in the United States except one which was conducted in Norway [33]. All seven studies indicated that OHPs lacked sufficient knowledge of eating disorders and limited clinical experience. Of those who were aware of oral health signs and symptoms, many reported not knowing how to address their observations with patients. Most OHPs did not refer patients for evaluation and treatment of their eating disorder, and when they did it was usually to primary care physicians rather than mental health providers.

Additional studies addressed education provided to oral health students about eating disorders and interventions to improve student and provider knowledge. The study populations included deans of dental schools and directors of dental hygiene programs [25], dentists, hygienists and students in dental and dental hygiene programs [23], and dental and dental hygiene students [20, 21, 24, 30]. The primary findings from these studies indicated that dental and dental hygiene students receive minimal instruction (between 17 and 35 min) in eating disorders [20, 25] and that interventions to provide education about eating disorders and their related effects on oral health can improve OHPs knowledge and capacity to intervene in patient care. DeBate et al. [20] study leveraged intervention mapping to design and test an online intervention to improve OHP student’s awareness of the impact of eating disordered behaviors on oral health and treatment options available to people with eating disorders [20]. The study demonstrated positive benefit, high student satisfaction with the program, and student interest in retaining access to the educational materials provided in the intervention.

The final category of articles relates to specific practices of OHPs when working with patients who have eating disorders. Of the four articles in this category, three are case studies providing insight into procedures OHPs used to address specific effects of eating disorders on oral health. In a 2014 paper, Lee et al. present two cases of adolescents who restricted food intake as a result of wearing braces that led to hospitalization for eating disorders [34]. The two other case studies describe procedures for treating oral health conditions in patients with longstanding bulimia nervosa [31, 35]. In both cases the eating disorder had significant effects on the patient’s teeth, including placement of implants or removable prosthesis, addressing both functional and aesthetic concerns. A final study examined the integration of tele-dentistry consultations into eating disorder day treatment to screen for oral health conditions and prevent dental erosion [32]. The article findings suggest that the use of tele-dentistry in an established eating disorder treatment program may provide advantages such as targeted evaluation of the oral health of individuals with eating disorders and an opportunity to establish oral health care for patients who may otherwise not have access to or not seek care.

Effects of eating disorders on oral health

The largest numbers of articles generated by the scoping review focused on the oral health effects of eating disorder behaviors. One study examined the prevalence of erosive lesions in a cross-section of Polish 18-year-olds and found that lesions were significantly associated with eating disorders [55]. Eleven of the studies used case–control designs to compare oral health findings between people with/at risk for eating disorders and healthy controls/those not at risk. An additional six studies described oral health effects and risk behaviors in patients with diagnosed eating disorders [41, 44, 47, 51, 53, 54]. Findings from these studies indicate negative effects of eating disorders on oral health including tooth erosion, increased size of salivary glands, and gingival recessions at higher rates than control groups. One study evaluated dental conditions and oral health behaviors (e.g., frequency of brushing) and noted differences in the presentation of both between people with anorexia nervosa and bulimia nervosa [48]. Additional findings in these studies showed increased self-reported oral health problems in individuals with eating disorders compared to those without [43], and a higher presentation of general muscle sensitivity potentially suggesting higher susceptibility to myofascial pain than healthy subjects [40].

Two articles described the impact of eating disorder behaviors in individual cases. One study described a patient who’s self-induced vomiting led to necrotizing sialometaplasia (a benign ulcerative lesion due to tissue death of the salivary glands) and significant dental erosion [42]. The other case study described dental evaluation and treatment of a patient over a 6-year period, noting worsening oral health symptoms and denial of an eating disorder [38]. At the appointment 6 years from the original appointment, she shared her longstanding eating disorder with her OHP and her initial reluctance to confirm their concerns.

A final study designed and tested a questionnaire to identify oral health risk factors and symptoms in individuals with anorexia nervosa. A 26-item questionnaire was assessed and found have moderate reliability when administered as a self-report form. The ten most reliable items from the original questionnaire were recommended as a risk assessment in patients with anorexia nervosa [51].

Patient practices and experience of oral health care

The remaining seven articles evaluated dental fear and anxiety, oral hygiene knowledge and attitudes, and oral health behaviors in individuals with or at-risk-for eating disorders. Three articles identified elevated dental fear and anxiety among individuals with or at risk for eating disorders compared to those without [60,61,62]. These study samples were Finnish university students, Norwegian women with diagnosed eating disorders recruited from a self-help organization, and Turkish individuals with and without eating disorders about to undergo oral surgery. The methods used to identify patients with or at risk for an eating disorder varied across studies, as did their assessments to measure dental fear and anxiety.

Two papers evaluated oral health concerns, sources of information about oral health effects of eating disorders, and willingness to see OHPs in people with eating disorders [56, 57]. Both articles found that participants were concerned (with high proportions expressing significant concern) about the impact of their eating disorder on their oral health. For sources of information, Conviser et al. found that, of participants who sought information about how to minimize damage from purging, 84% found the internet to be one of the most helpful sources of information, whereas only 29% included OHPs as one of the most helpful. In Dynesen et al. research, 70% obtained information about oral health complications from media sources (e.g., internet, television) compared to 24% from a dentist.

Conviser et al. and Dynesen et al. also evaluated oral care behaviors following self-induced vomiting. Conviser et al. asked whether participants rinsed the mouth with water or a mouth rinse (84%) or brushed their teeth immediately after (33%) purging. Dyneson et al. study summarized the findings of participants’ oral health behaviors following SIV as neutralizing acid in the mouth (34%) and avoiding toothbrushing (29%). Both studies, along with Wilumsen et al. [62], and Johanssen et al. [58] found that most participants had not told an OHP about their eating disorder. Johanssen et al. reported that only 6% of participants disclosed their eating disorder, with 29%, 32%, and 39% disclosing in Conviser, Dynesen, and Willumsen respectively.

Additionally, Dynesen, Willumsen, and Johanssen asked participants about frequency of visits to an OHP. Dynesen et al. framed the question in terms of frequency, with 33% reporting visiting the dentist more than twice per year [57]. Willumsen et al. asked about the date of participants’ last dental treatment—with 87% having seen a dentist in the last 2 years [62]. Johanssen et al. found that 71% attended “regular dental visits” but did not specify a time frame. However, the average time between visits for people attending any dental appointments in the study was 14 months [58].

The last study examined differences in behaviors in individuals with eating disorders at different clinical presentations in their eating disorders. They compared participant responses when symptoms were relatively absent (defined as ED-good) and when they were more “active” or highly symptomatic (defined as ED-bad) [59]. They found that behaviors associated with different states of an individual’s eating disorder posed differential risks to oral health. Compared to health controls, ED-good was predicted by the variables: higher intake of caffeinated beverages, and lower intake of regular (non-diet) soft drinks. Predictive variables of ED-bad were: lower frequency of lunch, and lower intake of sweet biscuits. A key takeaway from the study is that between ED-good and ED-bad states, an individual’s behaviors pose different risks to oral health.

Discussion

This scoping review investigated the state of evidence about oral health and eating disorders. In addition to literature on the oral health sequalae of eating disorders, included articles addressed (1) eating disorder knowledge and education of OHPs, (2) interventions OHPs use to treat effects of eating disorders, and (3) patient attitudes and behaviors related to oral health care. Across the different categories of studies, a consistent finding was that OHPs do not receive sufficient education and training to address eating disorders in practice—inhibiting early identification, treatment, and referral.

OHPs’ insufficient knowledge of eating disorders is evidenced by an absence of or minimal educational content on eating disorders and lack of clinical exposure to patients with eating disorders in training programs. The insufficient training received in OHP training programs is similar to medical training programs [14,15,16, 63]. The factors that impacted OHP’s ability to identify and comfort with treating patient with eating disorders was associated with their exposure to clinical cases during training and working with a clinician who had a particular interest in eating disorders, factors also associated with physicians’ ability to identify and treat patients with eating disorders [63].

Research examining methods to educate OHPs about eating disorders found promising results. Knowledge about eating disorders and their presentation was increased, and the interventions were considered acceptable to participants. While both a static e-learning training and an interactive training improved participants’ knowledge of eating disorders, the interactive training was superior at reducing OHPs’ perceived barriers to secondary prevention, increasing perceived benefits of secondary prevention, and increasing perceived self-efficacy to perform secondary prevention behaviors [24]. The small body of research on educational programs warrants further study to examine the transferability of these interventions into non-U.S. oral health training programs. Additionally, uptake of these educational programs by dental and dental hygiene programs will be an important are for additional research.

One major area of note across the included studies was the assertion that OHPs need to be connected to eating disorder professionals. No studies were identified that examined mechanisms for connecting OHPs and eating disorder professionals. The eating disorders field has an opportunity to build relationships with local and national oral health provider organizations and with local providers to increase awareness of referral resources and offer support to OHPs who may be among the first providers to observe an eating disorder. Increasing OHPs awareness of resources for eating disorder treatment and eating disorder treatment providers’ knowledge of oral health risks and referral resources presents an opportunity for research into methods to incorporate OHPs in eating disorder treatment teams. The clearly stated need for these relationships and the noted lack of research indicates an important area of study for researchers across the globe.

A small portion of the research in this review examined eating disorder patients’ oral hygiene behaviors and feelings about oral health procedures. The findings in these studies indicate that many individuals do not disclose their eating disorder to OHPs and may engage with oral health care less frequently than clinically recommended. Future research should evaluate whether and how eating disorder treatment professionals can contribute to patient engagement with oral health care. In addition to the potential for engagement between eating disorder professionals and OHPs, there is an opportunity for eating disorder professionals to encourage patients to disclose to OHPs and to address fear and anxiety about oral health procedures. There is also an opportunity to examine the ways that OHPs can be formally included in the American Psychiatric Association practice guidelines for the treatment of eating disorders as members of the multi-disciplinary research team—and whether doing so increases engagement with OHPs.

A final note on the findings of this scoping review is that the majority of work on oral health and eating disorders is on the oral health sequalae of eating disordered behaviors. This body of literature has been the subject of previous systematic reviews [64,65,66,67]. One key issue raised in many of the studies is that the oral health effects of eating disorders are not unique to eating disordered behaviors. Most of the associated conditions (e.g., tooth erosion, susceptibility to caries, changes in salivary flow, periodontal disease) can be indicative of many other conditions. This finding, paired with the research indicating OHPs’ lack of confidence in their ability to communicate about eating disorders, suggests a need for additional research. Research on interventions to increase OHP confidence in their ability to raise concerns about disordered eating behaviors will be vital to promoting secondary prevention efforts. Additionally, research is needed on whether increasing OHPs’ communication capacity impacts patients’ willingness and comfort with disclosure of eating disordered behaviors with their providers.

This research has a number of limitations. First, articles were only included if they were available in English. Several studies returned in the search were excluded based on language that may address some of the topics that were less well represented in this study. Additionally, we did not evaluate the quality of the research. The quality of evidence for oral health sequalae of eating disorders has been previously reviewed. Future research should consider the quality of studies evaluating provider education and training and patient experiences.

Conclusion

This scoping review sought to assess the state of research on eating disorders and oral health. While there has been significant research on the impact of eating disorders on oral health, there is a need for research in all other aspects of the intersection between eating disorders and oral health. In addition, there is a clear need to establish relationships between oral health professionals and eating disorder treatment professionals. These relationships would improve patients’ referral to specialty care when symptoms are observed in an oral health setting and increase the potential for improved oral hygiene and clinical outcomes for individuals with eating disorders.