1022 Orthognathic surgery

complex. Depending on the expansiondevice the amount of tipping was up to30% for devices mounted on the teeth.Expansion devices fixed on the palateshowed transversal distraction with hardlyany tipping of teeth and alveolus. Conclu-sion: SARME leads to dentofacial changesdepending on the expansion device.

doi:10.1016/j.ijom.2007.08.200

O10.16A secondary soft tissue procedure aneed or an adjuvant in Le Fort Iosteotomy?

L. Chandra*, K.K. Rai, B.P.R. Kumar,K.V.A. Kumar, M.C. DayanandDepartment of Oral & Maxillofacial Sur-gery, Bapuji Dental College & Hospital,Davangere, Karnataka 577004, India

Predictable soft tissue changes occur afterLe Fort I osteotomy but it is difficult tocontrol them due to their variable adapt-ability. A secondary soft tissue procedure isoften needed to mask soft tissue effects ofthe procedure. The aim of study is to eval-uate whether secondary soft tissue proce-dure is a need after Le Fort I osteotomy orthey can be done whenever needed as adju-vant procedure. Fifteen patients underwentLe Fort I osteotomy. These subjects weredivided in control and study group. Thenumber of patient in the study group waseight and in control group was seven. Thesecondary procedure like reduction of ante-rior nasal spine, alar cinching and V-Yclosure of upper lip were performed instudy group but not in control group. Theparameters which were taken into consid-eration were alar base width, nasolabialangle, nasal tip projection and upper liplength. The patients were evaluated pre-operatively and post-operatively by cepha-lometric analysis for soft tissue changes.The alar base width, nasal tip projection,nasolabial angle and upper lip length werefound to be optimum in the control group.So it can be concluded that secondaryprocedure is always needed to correct pre-dictable soft tissue changes following LeFort I osteotomy.

doi:10.1016/j.ijom.2007.08.201

O10.17Evaluation of advancement versussetback of mandibular orthognathicprocedures, its influence on pharyngealairway

G.C. Veena*, K. Rai, B.P.R. Kumar, B.Jayade, H.R.S. Kumar, DayanandDepartment of Oral Maxillofacial andReconstructive Surgery, Bapuji DentalCollege and Hospital, Davangere, Karna-taka, India

Surgical procedures are routinely per-formed for the correction of congenitaland acquired deformities of the dentofa-cial skeleton. These surgical alterationsinevitably alter and subsequently affectthe soft to hard tissue relationships.Though they have the potential of improv-ing aesthetics and masticatory function,the other aspect to be considered is thechange in the pharyngeal airway afteradvancement and setback procedures. Pro-cedures such as advancement have beenadvocated for the treatment of obstructivesleep apnoea caused due to disproportion-ate anatomy of the airway. The predictablechange in the anteroposterior dimensionsof the oropharynx does have a influenceover the quantity of aggravating or reliv-ing sign of a pre-existing sleep disorder. Inthis presentation we would like to evaluatecases of mandibular advancement and set-back and the comparison of oropharyngealairway morphologies before and after sur-gery, the understanding which will benefitthe various orofacial alterations to be car-ried out.

doi:10.1016/j.ijom.2007.08.202

O10.18Sliding augmentation genioplasty—‘‘How much can we predict’’?

R. Burman*, M. RaiDepartment of Oral & Maxillofacial Sur-gery, K.V.G. Dental College & HospitalKurunjibagh, Sullia 574327 D.K., Karna-taka, India

Objective: To evaluate soft tissue responseto large and small genial advancements inpatients who underwent genioplasties. Theeffects of bony horizontal and bony ver-tical changes on horizontal soft tissuemovement was evaluated. Methods:Twelve patients who underwent augmen-tation genioplasty along with maxillary LeFort I osteotomy were included. Genialsegments were moved to a predeterminedhorizontal and vertical position. Pre-operative, immediate and 6-month post-operative cephalograms were taken fordata analysis. Results: Average surgicaladvancement at bony pogonion was8.2 mm. Average soft tissue advancementwas 94% of the horizontal bony move-

ment. Up to 8 mm horizontal advancementthe soft tissue chin followed the hardtissue 1:1, after which it followed a secondorder polynomial curve. When a combina-tion of bony vertical and horizontal move-ments was used as predictors of soft tissuemovement, the correlation between hardand soft tissue movements increased sig-nificantly. Conclusion: The influence ofhorizontal bony advancement on soft tis-sues appeared to decrease when advance-ment was beyond 8 mm. Verticalmovements greatly influenced the overallresult. Horizontal stability appeared to beinfluenced by the amount of dissectionrather than the amount of advancement.

doi:10.1016/j.ijom.2007.08.203

O10.19Adaptation of lateral pterygoid musclesafter surgical mandibularadvancement

G. Dicker*, P. van Spronsen, R. vanSchijndel, F. van Ginkel, R. Manoliu,B. TuinzingDepartment of Oral and MaxillofacialSurgery/Pathology, Academic Centre forDentistry Amsterdam (ACTA) and VUUniversity Medical Center, PO Box7057, 1007 MB Amsterdam, The Nether-lands

Objectives: Jaw closing muscles arereported to decrease significantly in sizeafter surgical mandibular advancement.In this study, adaptation of lateral ptery-goid muscles (LPM)) after surgery wasexamined. Methods: Eighteen adultpatients (mean age: 29 years) with man-dibular retrognathia and individuallyvarying vertical craniofacial dimensionswere treated with bilateral sagittal splitosteotomies (BSSO), in some cases com-bined with a maxillary osteotomy. Thesample was divided into a short-face (SF,n = 7) and a long-face group (LF, n = 11)using cluster analysis. Coronal MRI scans(slice thickness 4 mm) were taken preo-peratively and 1–5 years postoperatively.The contours of the LPM were segmentedusing customized software (VISIAN1).Multiplanar reconstructions enabled toreslice this muscle perpendicular to itslongitudinal axis. This allowed calcula-tion of maximal cross sectional area(CSA) and volume. Results: Postopera-tively, CSA (+5.7%) and volume(+12.9%) of LPM increased in the SFgroup. In the LF cluster, CSA (+1.5%)and volume (+9.0%) increased in BSSOcases and decreased (CSA, �7.6%;