Celiac Disease is an underdiagnosed pathology, partially due to the wide variety and non-specificity of clinical signs and symptoms (Pastore et al. 2008a, b; Lindfors et al. 2019). Oral manifestations can be important for the diagnosis of CD, especially in atypical clinical cases (Jajam et al. 2017). In these atypical cases, oral manifestations may be the only signs and symptoms present, and the oral health professional may be important in the diagnosis, control, and counselling of these patients. When there is suspicion of CD, the dentist or dental hygienist should advise the patient to seek a gastroenterologist, to screen for this autoimmune disease (Costacurta et al. 2010; Macho et al.2017). Additionally, in patients already diagnosed, the oral health professional should be aware of the components of the products they use in their clinical practice to ensure that they do not contain gluten. Also, more specific recommendations must be made to these patients, to indicate safe oral hygiene products and to make frequent control appointments to reduce possible oral manifestations and their consequences. The oral health professional must reinforce the importance of a gluten-free diet, which is to date, the only effective form of control for this disease.

Oral health behaviours were generally well-implemented in celiac children, with the majority performing twice a day toothbrushing, having low frequency of cariogenic foods and drinks intake, and frequent appointments to the oral health professional. Shteyer et al. (2013) determined that 66.7% of celiac children brushed their teeth twice a day, compared to 60% of the healthy children. Toothbrushing with a fluoride paste is an important recommendation for all patients but is especially important for celiac patients who have frequently enamel defects, which increase the risk of developing dental caries.

The assessment of OHRQoL to measure the impact of oral pathologies reflects a more focused and patient-centered follow-up and treatment. Although ECOHIS values in the present study can be considered low, revealing a good OHRQoL of the celiac children, almost all the reported oral manifestations showed a relationship with a worse OHRQoL. The relationship between OHRQoL and CD was suggested by van Gils et al. (2017) who verified a clear impact of CD on Health-Related Quality of Life, when compared to a group of healthy individuals.

In the present study, several oral manifestations were reported, and the oral health professional should be aware of those manifestations. Oral health manifestations are described in a high percentage of celiac patients (Campisi et al. 2008; Nieri et al. 2017; Villemur Moreau et al. 2021). Recurrent aphthous stomatitis is one of the oral manifestations most frequently described in CD, and its etiology is thought to be related to anemia and hematinic deficiencies (Jajam et al. 2017). According to the literature, there is a decrease or even total regression of recurrent aphthous stomatitis with the introduction of a gluten-free diet (Bucci et al. 2006; Campisi et al. 2008; Pastore et al. 2008a, b), as reported by the parents of celiac children in the present study.

Dental manifestations were also among the most reported oral manifestations in the studied population. The prevalence of these manifestations in the literature ranges between 10 and 96% (Pastore et al. 2008a, b; Rashid et al. 2011; Ferraz et al. 2012; Macho et al. 2017). A meta-analysis (Nieri et al. 2017) described that a study with 1490 celiac children and 2318 healthy children, demonstrated that 46% of children with CD were found to have at least one affected tooth with enamel defects, compared to 14% of children in the control group. The etiology of dental enamel defects in celiac patients is not yet clarified (Bramanti et al. 2014). These dental alterations may be associated with several systemic diseases and not just CD, but the defects present in celiac patients are highly specific, being characterized by dotted surfaces, furrows, and sometimes complete loss of enamel (Macho et al. 2017). de Carvalho et al. (2015). De Carvalho et al. (2015) analyzed the chemical composition of the enamel of primary teeth in patients with CD and found that the calcium/phosphorus ratio is significantly lower in these individuals. These defects can result from hypocalcemia, genetic susceptibility, or an autoimmune reaction in the enamel organ during tooth formation, before the 7th year of age (Macho et al. 2017; Cruz et al. 2018).

The association between dental caries and CD is still controversial, with some studies showing a higher caries experience in celiac patients (Costacurta et al. 2010) and others the opposite (de Carvalho et al. 2015). Some authors refer that dental caries are less prevalent in these patients due to strict diet control. Other authors justify the association of CD with dental caries due to the fragility of the hypoplastic enamel and changes in saliva composition or reduced salivary flow (Macho et al. 2017). Despite contradictory data and authors opinions, oral health professionals should consider incorporating preventive oral health measures in these patients, which may include topical fluoride and sealants, as well as early treatment of caries lesions and fractures of the hypoplastic enamel (Macho et al. 2017).

The impact of oral manifestations on the OHRQoL of celiac children/adolescents was lower than the one reported by Mansoori et al. (2019) in Indian children aged 0 to 6 years (ECOHIS score = 7.0), but higher than the value obtained by Chaffee et al. (2017) in Brazilian children aged 2 and 3 years (ECOHIS score = 2.0).

The negative impact of oral manifestations of CD on OHRQoL can be explained in several ways. Recurrent aphthous stomatitis can affect diet, speech, as well as toothbrushing and, in addition, it can cause emotional instability due to pain and discomfort (Macho et al. 2017). Patients with atrophic glossitis also report difficulty in chewing, swallowing, and talking (Bucci et al. 2006; Macho et al. 2017). On the other hand, enamel defects cause discomfort to patients and put them at risk for oral pathologies such as dental caries (Cervino et al. 2018). Children with caries lesions are more likely to have pain and chewing difficulties, which can lead to greater concern with oral health (Piovesan et al. 2011). In this study, as in the studies of Piovesan et al. (2011), Chaffee et al. (2017), and Freire et al. (2022) caries experience was associated with a worse OHRQoL.

The associations found between the reported oral manifestations and the OHRQoL of CD patients highlight the importance of a correct diagnosis of the pathology and, consequently, of its control with a gluten-free diet.

This cross-sectional study included a non-probabilistic sample and analyzed the perceived oral health of celiac children by their parents. The DC is described as an under diagnosed disease with a prevalence of about 1% of the general population. Considering the Portuguese population under 18 years-old (1,800,000) (PORDATA 2021) and a prevalence of DC 0.7% in the Portuguese population (Antunes et al. 2006) the present study included about 0.8% of the celiac population in Portugal (PORDATA 2021). Additionally, the data were collected by an online questionnaire and this methodology have some advantages, but also several caveats. The latter ones are related to the sample that can include the possibility of self-selection, non-response, unknown participation rates, and under-coverage of the target population, determined, amongst others, by access to the internet (Nayak and Narayan 2019). Despite its limitations, this study may provide a valuable insight of the OHRQoL in celiac children and of oral manifestations associated with CD, particularly in the Portuguese population, where these studies are scarce. It also highlights the importance of the oral health professionals to be aware of the heterogenous presentation of the disease, and their role in early diagnosis, leading to a reduction of complications and a consequent improvement in the OHRQoL of CD patients.