Changes in lower incisor irregularity during treatment with oral sleep apnea appliances

The purpose of this study is to test the hypothesis that a flexible oral appliance without incisor coverage (OA_Flex) increases the irregularity of the front teeth compared with a rigid appliance with incisor coverage (OA_Rigid) in patients treated for obstructive sleep apnea (OSA).

Nineteen patients (10 men) who had used OA_Rigid and 22 patients (19 men) who had used OA_Flex with a median age of 61 years (IQR of 56 to 67 years) who had been treated during a median period of 2.9 years (IQR of 2.7 to 3.1 years) were included in the study. There was no difference in age (p = 0.601) or treatment time (p = 0.432) between the two appliance groups. The patients had clinical examinations, responded to a questionnaire, and had impressions taken for plaster casts. The irregularity of the front teeth was measured by Little's Index, where the combined linear displacement of all the front teeth is assessed. Changes between baseline and follow-up were compared between the two groups.

The OA_Flex group increased the irregularity of their lower front teeth by 0.3 mm (p = 0.018), while the OA_Rigid group had unchanged frontal irregularity (p = 0.717). The difference between the groups was significant (p = 0.035). There were no changes in the irregularity of the upper front teeth in either group. Patient satisfaction with treatment did not differ between the two appliances.

The present results support the hypothesis that a flexible OA without incisor coverage increases the irregularity of the lower front teeth compared with a rigid OA with incisor coverage.