Difference in dental arch size between obese and non-obese patients with obstructive sleep apnoea

A large tongue is recognised as a factor that increases the collapsibility of the upper airway in obstructive sleep apnoea (OSA) patients. We hypothesised that the propensity to develop severe OSA could be minimised if the dental arches were enlarged in obese OSA people who are thought to have a large tongue. We therefore compared the size of the dental arches in obese and non-obese OSA patients. Using a lateral cephalogram and study models, we compared the sizes of the tongue and dental arches in 23 obese and 23 non-obese Japanese male OSA patients, who were matched for age, apnoea hypopnea index (AHI) and maxillomandibular size. The median age (years) and AHI (events per hour) for the obese and non-obese groups were 36·5 and 39·0, and 13·4 and 14·3, respectively. The maxillomandibular size was matched with regard to SNA, SNB and lower face cage obtained from cephalometric measurements. The parameters that were measured for the study model included dental arch width, dental arch length, overjet and overbite. Tongue size (P < 0·05) and both upper (P < 0·01) and lower (P < 0·05) dental arch widths were significantly larger in obese than in non-obese OSA patients, and there was no difference in the severity of OSA between the two groups. These findings suggest that the tongue was larger and dental arches were enlarged in obese patients compared with non-obese patients under the same disease severity. Wider dental arches in obese OSA patients may help to offset the impact of the enlarged tongue on upper airway patency.