Long-term oral-appliance therapy in obstructive sleep apnea: a cephalometric study of craniofacial changes

The aim of this randomized controlled study was to cephalometrically assess possible changes in craniofacial morphology associated with long-term use of an adjustable oral-appliance compared with continuous positive airway pressure (CPAP) in patients with the obstructive sleep apnea/hypopnea syndrome (OSAHS). In addition, we wanted to study the relationship between these possible changes and the degree of mandibular protrusion associated with oral-appliance therapy.

Fifty-one patients were randomized to oral-appliance therapy and 52 patients to CPAP therapy. At baseline and after follow-up (2.3±0.2 years), a lateral cephalogram of all patients was made in maximum intercuspation to determine relevant cephalometric variables. Both baseline and follow-up cephalograms were traced digitally whereupon cephalometric variables were compared. Changes in craniofacial morphology between the oral-appliance- and CPAP group were evaluated with a linear regression analysis.

Compared with CPAP, long-term use of an oral-appliance resulted in small but significant (dental) changes. Overbite and overjet decreased, 1.0 (±1.5)mm and 1.7 (±1.6)mm, respectively. Furthermore we found a retroclination (-2.0 (±2.8)°) of the upper incisors and a proclination (3.7 (±5.4)°) of the lower incisors. Moreover, the lower- and total anterior facial height increased significantly, 0.8 (±1.5)mm and 0.9 (±1.4)mm, respectively. No changes in skeletal variables were found. Linear regression analysis revealed that the decrease in overbite was associated with the mean mandibular protrusion during follow-up (B=-0.029, SE=0.014, p<0.05).

Oral-appliance therapy should be considered as a life long treatment, and there is a risk of craniofacial changes to occur. Therefore, patients treated with an oral-appliance, need a thorough follow-up by a dentist or dental-specialist experienced in the field of dental sleep medicine.