Association of achalasia and dental erosion

Dental erosion is the dissolution of enamel and dentine caused by organic or inorganic acids.¹ The source of acid is normally either dietary acids² or regurgitation of stomach juice³ into the mouth. Enamel and dentine begin dissolution at a pH of approximately 5.5.⁴ In achalasia, bacterial fermentation of food produces lactic acid, with a minimum pH of approximately 3.5,⁵ which has the potential to demineralise teeth if it reaches the mouth. This study investigated whether regurgitated lactic acid fermented from food lying within an achalasic oesophagus causes dental erosion. The aim of the study was to measure the prevalence of dental erosion in patients referred for management of untreated achalasia and to compare the results with a control group.

Patients referred to the oesophageal laboratory from a variety of medical sources for investigation of achalasia were recruited. Manometry was used to diagnose the presence of achalasia in all subjects. Ethics approval was provided from the local hospital and each patient gave informed consent for assessment of erosion. The distribution and severity of dental erosion was determined using the Smith and Knight tooth wear index (TWI).⁶ All tooth assessments were carried out by the first author under ideal conditions. The index scores erosion on a five point scale, with 0 representing no erosion and a score of 4 representing pulpal exposure. A control group, without symptoms or history of gastro-oesophageal reflux disease, were selected from the partners of patients attending for oesophageal tests. Inclusion criteria did not take into account the presence or absence of dental erosion. A dietary questionnaire was used to exclude subjects with a high intake of dietary acids. Mann-Whitney U tests were used to compare patients with controls for differences in tooth wear scores. Intraclass correlation showed good agreement for the erosion scores (0.99).

Fifteen patients with achalasia (six males and nine females) with a mean age of 49 years (SD 18.4) were recruited over a two year period and compared with 32 controls (14 males and 18 females) with a mean age of 43 years (SD 16.8). Median percentage of teeth scoring a TWI of 2 or above was 21.4% (interquartile range (IQR) 11.46–30.77) in patients and 7.76% (IQR 0–12.2) in controls, for all tooth surfaces (p = 0.001). At the moderate level (score 3 and above), with dentine exposed for more than one third of the surface, patients had a median of 0% (IQR 0–16.1) and controls a median of 0% (IQR 0–0; p<0.001). The distribution of the erosion was predominantly on the palatal surfaces of the upper incisors.

Achalasia is an uncommon disorder of the oesophagus in which there is failure of normal peristalsis in the body of the oesophagus and the lower oesophageal sphincter fails to relax.^7,8 The control group were recruited from the partners of the patients attending for oesophageal tests. Unfortunately, it was not feasible to undertake manometry in the controls as this was ethically unacceptable but there remains a possibility that some had asymptomatic reflux but not achalasia. If any controls had asymptomatic reflux they were at more risk of developing dental erosion but the results from the erosion scores seemed not to indicate this.

Ineffective oesophageal motility causes delayed acid clearance and its association with the presence of palatal dental erosion was reported by Bartlett and colleagues.^9,10 The results of this study support the hypothesis that oesophageal motility disorder has an important role in the development of dental erosion, albeit an extreme example. In this case, an obstructive oesophagus causes food fermentation, and in turn regurgitation of fermented food causes dental erosion. The presence of palatal dental erosion in patients with achalasia strongly suggests that the source of the acid within the oesophagus is lactic acid unlike reflux disease where hydrochloric acid from the stomach is responsible.¹¹ This study shows that in patients with achalasia, particular attention to the condition of their teeth needs to be addressed. In conclusion, achalasia is related to palatal dental erosion and the cause of the erosion is fermented foods and not regurgitated gastric juice.