Cranial base considerations between apnoeics and non-apnoeic snorers, and associated effects of long-term mandibular advancement on condylar and natural head position.

One hundred consecutively medically referred patients (58 apnoeic and 42 asymptomatic snorers) were reviewed cephalometrically at six-monthly intervals (6-30 months) following treatment for obstructive sleep apnoea (OSA) and/or habitual snoring by mandibular advancement. Eighty-seven males and 13 females (mean age 49 years, SD 8.5, range 33-74) were included in this study. Reference points and planes in the cranial base, nasopharynx, and mandibular condyle were digitized with a Reflex Metrograph and their means converted to linear and angular measurements. No statistically significant differences were observed between the apnoeic and non-apnoeic groups in either their skeletal or cranial base measurements. All linear cranial base dimensions were, however, reduced in the apnoeic group, with the exception of the distance (S-SE). Following mandibular advancement, statistically significant changes were observed in vertical condylar position (Cd-vert) with changes occurring at 6 (P < 0.012), 18 (P < 0.043), and 24 months (P < 0.007). No changes in horizontal condylar position (Cd-horiz) were found. Significant changes were observed in natural head position (NHP) with a reduction from an extended (NSL-vert 99.7 degrees) to a more upright NHP (NSL-vert 93.0, P < 0.001).