Summary BACKGROUND/OBJECTIVES: The aim of the study was to assess cephalometric predictive markers in terms of craniofacial morphology including posterior cranial fossa and upper spine morphology for mandibular advancement device (MAD) treatment outcome in patients with obstructive sleep apnoea (OSA).

MATERIAL/METHODS: Twenty-seven OSA patients were treated with MAD for 4 weeks. Apnoea-hypopnoea index (AHI) was recorded before and after MAD treatment. The criteria of treatment success were 75 per cent reduction of AHI. Accordingly, two groups occurred: the success treatment group of 8 patients and the no success treatment group of 19 patients. Before MAD treatment lateral cephalograms were taken and analyses of the craniofacial morphology including the posterior cranial fossa and upper spine morphology were performed. Differences between the groups were analysed by Fisher's exact test, t-test, and multiple regression analysis.

RESULTS: Upper spine morphological deviations occurred non-significantly in 25 per cent in the success treatment group and in 42.1 per cent in the no success treatment group. Body mass index (BMI; P < 0.05), maxillary prognathism (S-N-Ss; P < 0.01), mandibular prognathism (S-N-Pg; P < 0.05 and S-N-Sm; P < 0.01), and the distance between sella turcica and the deepest point in posterior cranial fossa (S-D; P < 0.05) was significantly smaller in the success treatment group. The maxillary prognathism (P < 0.05) was the most important factor for the MAD treatment outcome (R (2) = 0.47).

LIMITATIONS: Relatively small sample size.

CONCLUSIONS: The results indicate that BMI, posterior cranial fossa morphology, and retrognathia of the jaws are factors related to MAD treatment outcome. Furthermore, OSA patients with upper spine morphological deviations may respond poorer to MAD treatment.