Difference in the Function of the Inferior Alveolar Nerve After DOG and BSSO as Reported by the Patient

Oral Abstract Session 3 worth Sleepiness Scale (ESS) score also decreased significantly from 12.9 ⫾ 4.5 pre-operatively to 8.3 ⫾ 3.2 post-operatively (p⫽0.0009). Mean increase in PNS position post-MMA was found to be 8.29mm ⫾ 2.37. SNB showed a mean increase from 78.86° ⫾ 3.63 pre-operatively to 83.27° ⫾ 3.75 post-operatively. Conclusion: In the majority of our OSA patients, MMA surgery effectively eliminated sleep disordered breathing. Previous studies have shown high success rates utilizing a definition of success as post-operative AHI ⬍20, with at least a 50% reduction from the preoperative AHI. Our study suggests that the rate of success is still quite high when using the even more robust definition of surgical success of post-operative AHI⬍5. The change in maxillary and mandibular position, quantified by change in PNS and SNB angles respectively, correlated with significant AHI reduction in the majority of our patients. References Li KK, Powell NB, Riley RW et al.: Long-Term Results of Maxillomandibular Advancement Surgery. Sleep Breath 2000;4:137 Prinsell JR: Maxillomandibular advancement surgery in a site-specific treatment approach for obstructive sleep apnea in 50 consecutive patients. Chest 1999;116:1519

Nasolabial Soft Tissue Changes Associated With Le Fort I Osteotomy Sivabalan Vasudavan, BDSc, MDSc, MPH, Boston, MA (Allareddy V; Sullivan SRl; Padwa BL) Statement of the Problem: Patients with cleft lip and palate often present with maxillary hypoplasia involving all three spatial dimensions. It is common for the cleft lip and palate patient to require sagittal advancement and vertical repositioning of the maxilla to correct for their underlying facial disharmony. Surgical movements of the skeleton can influence the overlying soft tissue dimensions and these factors must be taken into consideration during orthognathic planning. The aim of this study was to identify the key factors which determine nasolabial soft tissue changes in subjects who underwent Le Fort I maxillary osteotomy for maxillary hypoplasia. Materials and Methods: The sample consisted of cleft and non-cleft patients with maxillary hyopoplasia who were treated with a Le Fort I osteotomy. The subjects were classified according to the type of surgical movement performed: 1) maxillary advancement only (n⫽13), 2) maxillary advancement with inferior repositioning (n⫽10) and 3) maxillary advancement with impaction (n⫽14). Malar augmentation with onlay grafting was performed in 22 subjects. Methods of Data Analysis: Pre- (T1) and post-operative (T2) anthropometric nasolabial measures and lateral cephalometric radiographs were evaluated. PostAAOMS • 2009

operative (T2) lateral cephalograms and anthropometric measurements were taken more than six months after Le Fort I osteotomy. The magnification factor was recorded for each radiograph and all measurements were adjusted appropriately by the computer software. Digitization of the lateral cephalometric radiographs was performed using the Dolphin Imaging Program – Premium Version 10.5 (California, USA). The outcome variables included changes in anthropometric measurements (T2-T1) as reported by Farkas. The predictor variables included age, sex, type of surgical movement, use of malar implants, presence of cleft lip/palate and changes in cephalometric values. Multivariable linear regression analyses were used to examine the association between the independent and outcome variables. All regression models were built using the ordinary least squares approach. All tests were two-sided and a p-value ⬍ 0.05 was deemed to be statistically significant. Results: There were 37 patients (18 females and 19 males) who had Le Fort I osteotomy at a mean age of 19 years (range 14-41). There were 16 patients with cleft lip/palate and maxillary hypoplasia and 21 subjects with maxillary hypoplasia alone. After controlling for confounding factors, observed changes in nasal philtrum width were significantly associated with changes in upper anterior facial height (␤ ⫽ ⫺1.5), advancement of the maxillary incisor position (␤ ⫽ ⫺2.0), sagittal position of the maxillary first permanent molar tooth (␤ ⫽ 2.0), the occlusal plane (␤ ⫽ 1.7) and facial convexity (␤ ⫽ 0.9). Similarly, the changes observed in the nasal tip angle were significantly associated with the type of surgical movement (maxillary advancement with impaction, ␤ ⫽ 0.76), lower anterior facial height (␤ ⫽ ⫺1.5), sagittal position of the maxilla (␤ ⫽ 2.1), sagittal position of the maxillary first permanent molar tooth (␤ ⫽ 1.8), upper lip protrusion (␤ ⫽ ⫺1.1) and incisal display (␤ ⫽ ⫺1.9). The nasal tip elevated and the nasal philtrum width increased by 0.4 mm (p ⬍ 0.05). Conclusion: 1) The results of our study demonstrate that the nasal tip and the philtral width are particularly sensitive to maxillary surgical repositioning. 2) Soft tissue nasolabial changes associated with a Le Fort 1 osteotomy are independent of the diagnosis of a cleft lip/palate. References Mansour S et al. An evaluation of soft-tissue changes resulting from Le Fort 1 maxillary surgery. Am J Orthodontics 1983: 84:37-47 Farkas LG. Anthropometry of the Head and Face. New York: Raven Press, 1994

Difference in the Function of the Inferior Alveolar Nerve After DOG and BSSO as Reported by the Patient Erik Michael Baas, DDS, MD, Zwolle, Overijssel, Netherlands (de Lange J; Horsthuis R) 47

Oral Abstract Session 3 Statement of the Problem: Is there a difference in the occurrence of sensory disturbances, as reported by the patient, between a bilateral sagittal split osteotomy and distraction osteogenesis for lengthening of the mandible? Secondly, is there a difference between the objectively obtained test results and the outcome of a questionnaire in the individual patient? Materials and Methods: A patient control study was carried out in 65 patients who underwent a mandibular lengthening procedure in the Isala Clinics between 2001 and 2004. In 30 patients, DOG was performed, while a BSSO was done in the other 35 patients. At least one year after surgery the patients were screened for the function of the IAN. All patients received a questionnaire, as described by Al-Bishri et al 2004 for subjective evaluation of the nerve function. Objective screening of the sensibility of the lower lip and chin area was performed with simple neurological tests using cotton swabs, pin prick tests and Semmes Weinstein Monofilament 3.22. This filament was chosen for the upper normal limit for the detection threshold in the cutaneous region of the lower lip and chin. The separate stimuli of the neurological tests were applied four times to the skin in the area of interest. Right and left sides were tested separately. A positive response to a stimulus was scored in case of at least 75% correct responses out of 4 applied stimuli (3 out of 4 stimuli correct). Methods of Data Analysis: T-tests and ␹2 tests were performed to compare the different variables between the groups. Logistic regression analysis was used to compare the proportion of patients with a neurosensory change of the IAN to patients with a normal IAN function between both groups and to eliminate possible confounding and effect modification. Statistical analyses were performed with SPSS 16 software. Results: A total of 65 patients (130 nerves) was evaluated. In 37 nerves (28.5%), the patient reported loss of function. Within this group, a BSSO had was performed in 26 cases (70.3%) and in 11 cases (29.6%), a DOG had been carried out. Mean age in the group with a reported sensory disturbance was 32 years and in the control group 26 years. After elimination of confounding (age, gender, advancement) there was no significant difference in the risk on reported sensory changes between both treatment options (odds ratio: 0.652 with 95% CI: 0.221-1.920). Moreover, VAS scores for level of complains did not significantly differ between both groups (p⫽ 0.086). However, the categorical scores (mild to severe) were significantly lower in the DOG group (p⫽ 0.18) Age was significantly related to reported sensory changes: advancing age showed a significant increase in the number of nerve disturbances. This was seen in the whole group. However, when split into male and female, only the female population accounted for this effect (odds ratio: 22.8 with 95% CI: 2.580-201.488 for females 48

older than 36 years of age) while in males advancing age had no influence on the number of nerve disturbances. In all groups (male-female, DOG-BSSO, older-younger) the reported sensory disturbances differed significantly from the tested sensory disturbances. Satisfaction was significantly correlated with age (odds ratio 2.558 with 95% CI 1.208-5.416) and independent of the type of operation or gender. Conclusion: There is no difference in the occurrence of sensory disturbances between the two groups, either objectively tested or subjectively reported by the patient. The tested results differed significantly from the reported data in the individual patient. References Al-Bishri A, Rosenquist J, Sunzel B. On neurosensory disturbance after sagittal split osteotomy. J Oral Maxillofac Surg 2004: 62: 14721476 Schreuder WH, Jansma J, Bierman MW, Vissink A. Distraction osteogenesis versus bilateral sagittal split osteotomy for advancement of the retrognathic mandible: a review of the literature. Int J Oral Maxillofac Surg 2007: 36: 103-110

Novel 3-D CT Craniomaxillofacial Skeletal Landmarks for Treatment Planning and Outcomes Assessment Zachary R. Abramson, BS, Boston, MA (Susarla S; White C; Seldin E; Troulis MJ; Kaban LB) Statement of the Problem: Availability of 3-dimensional (3-D) maxillofacial CT scan reconstructions will potentially revolutionize treatment planning and outcomes assessment for craniofacial anomalies. To achieve these goals, anatomic structures must be identifiable in three dimensions, easy to locate, and demonstrate high intra- and inter-examiner reliability. The purposes of this study are to establish and validate a set of novel reproducible 3-D craniofacial landmarks and to evaluate the effect of abnormal anatomy on the reliability of landmark localization. Materials and Methods: A single maxillofacial CT scan with the associated 3-D CT model reconstruction of a patient with left type IIB (small size, abnormal shape, hypoplastic medially and inferiorly displaced temporomandibular joint) hemifacial microsomia was used in this study. Craniomaxillofacial landmarks were defined using a combination of traditional cephalometric definitions adapted to the 3-D environment and novel 3-D definitions created for the purposes of this study. Definitions adapted from traditional cephalometric landmarks included Crista Galli (CG), Bony Sella (BS), Nasion (N), Anterior Nasal Spine (ANS), A point (A), Condylion (Co), Coronoid (Cor), Sigmoid Notch (SN), Gonion (Go), B point (B), Pogonion (Pg), and Menton (Me). Novel CT landmarks included Anterior Frontal Crest (AFC), Anterior Foramen Magnum (AFM), Foramen Ovale (FO) AnAAOMS • 2009