• Chatpon Jamsirirojrat D.D.S.
• Panunn Sastravaha D.D.S., M.S., Diplomate, Thai Board of Oral and Maxillofacial Surgery, Diplomate, American Board of Oral and Maxillofacial Surgery
• Prakobkiat Hirunwiwatkul M.D., Diplomate, Thai Board of Otolaryngology
• Sukalaya Lerdlum M.D., M.S., Diplomate, Thai Board of Radiology
• Somchai Sessirisombat D.D.S., M.D., M.S., Diplomate, Thai Board of Oral and Maxillofacial Surgery

Objective To evaluate the lateral cephalometric parameters in a group of Thai patients with severe
obstructive sleep apnoea syndrome (OSAS) and primary snoring.

Materials and methods This study was performed in the lateral cephalograms of 190 patients
attending Snoring Clinic at King Chulalongkorn Memorial Hospital during 2003-2007. Using the
respiratory disturbance index (RDI), the patients were divided into two groups, those with an RDI of
five events/hour or below (primary snoring group) and those with an RDI of 30 events/hour or over
(severe OSAS group). Their demographic data, along with nine parameter data from lateral cephalograms,
were collected. Analyses of the data were performed by a descriptive statistic analysis and an
independent t-test at the 95% confident level.

Results Parameters with significant differences between primary snoring and severe OSAS groups
were SNA and MP-H among male patients, and UT-PhW and MP-H among female patients.

Conclusion Lateral cephalograms revealed differences between patients in severe OSA and those in
primary snoring groups. Male patients with severe OSAS possessed a maxilla with a retrognathic
position, together with a hyoid bone with an inferiorly displaced position. Female patients with severe
OSAS possessed a narrower space between uvula tip and posterior pharyngeal wall, together with a
hyoid bone with an inferiorly displaced position.

(CU Dent J. 2008;31:249-60)