Mandibular Prognathism by BSSO Study

Mandibular Prognathism by BSSO StudyMETHODOLOGYMETHODOLOGY communityConsisted of all the uncomplainings who reported to the Out Patient Department of Oral And Maxillofacial Surgery for correction of facial deformity involving maxilla and mandible.SampleConsisted of 33 patients who underwent BSSO reverse for mandibular prognathism followed by Rigid Internal Fixation at the Department Of Oral And Maxillofacial Surgery, Mar Baselios Dental College.Inclusion CriteriaPatients above age of 20 years for males 18 years for females.Patients who were treated by BSSO setback along with Rigid Internal Fixation for mandibular prognathism.Exclusion CriteriaPatients undergoing Bimaxillary surgeries.Patients undergoing Genioplasty along with BSSO.Patients with Medically compromised conditions.Patients with Craniofacial anomalies, Syndromes.A retrospective study was conducted on 33 patients (15 females and 18 males), with mean age of 22 years (age range of 19 28 years), who were operated for mand ibular prognathism by BSSO at the department of oral and maxillofacial surgery, Mar Baselios Dental College, Kothamangalam. The patients were selected according to above mentioned inclution and exclusion criterias. The surgical procedure was done by one chief operational surgeon. No maxillomandibular fixation was used postoperatively. Pre and postsurgical orthodontics was carried out at the department of orthodontics and dentofacial orthopaedics, Mar Baselios Dental College, kothamangalam.A standardised askant skull radiograph with adequate quality and exposure was taken pre operatively and after 6 months of follow up in natural head position Frankfurts even bed sheet parallel to the floor, the tongue in relaxed position and the mandible in centric occlusion with exposure values of 80 KVp, 10 mA, and 1.30 seconds.Tracings of the lateral cephalograms were pencil traced on acetate paper. To improve the consistency the tracings and measurements were taken by the same investigator. Horizontal refer line was taken as 7 to SN at nasion. upended reference line was constructed perpendicular to level reference line through Sella. Superimposition of traced preoperative and postoperative lateral cephalogram was done with respect to the horizontal and vertical reference lines. The following cephalometric argues and measurements were used.SSella Center of sella turcicaNNasion Most anterior dapple of fronto hard up sutureANSAnterior Nasal Spine Anterior tip of the nasal spinePNSPosterior Nasal Spine The most posterior aspect of the palatal boneAPoint A Innermost point on sort of maxilla among anterior nasal spine and incisor toothIs cacography outstanding Midpoint of incisal edge of most prominent maxillary central incisorIiIncision Inferior Midpoint of incisal edge of most prominent mandibular central incisorBPoint B Innermost point on contour of mandible between incisor tooth and bony chinPGPogonion Most anterior point on osseous contour of chinMEMenton Most inferior midline point on mandibular symphysisCmColumella point Midpoint of columella of noseSnSubnasale Point at which columella merges with upper lip in midsagittal planeSLSSuperior Labial Sulcus Point of greatest incurvation in middle of upper lip between subnasale and labrale superiusLsLabrale Superius Most anterior point of upper lipLiLabrale Inferius Most anterior point of lower lipSLIInferior Labial Sulcus Point of greatest concavity in midline of lower lip between labrale inferius and flocculent tissue pogonionpgSoft waver Pogonion Most prominent or anterior point on chin in midsagittal planemeSoft Tissue Menton Lowest point on contour of soft tissue chinStomsStomion Superius Most inferior point of upper lipStomiStomion Inferius Most superior point of lower lipSn-StomsUpper lip lengthStomi-meLower lip lengthG-Sn-PGFacial Convexity Angle between soft tissue glabella, subnasale and soft tissue pogonionCm-Sn-LsNasolabial Angle Angle between columella and labrale superiusLi-S LI-pgLabiomental Fold Angle between lower lip and chin contourResearch methodologyIn the horizontal plane linear changes at following hard tissue ANS, A, Is, Ii, B, PG, ME and soft tissue Sn, SLS, Ls, Li, SLI, pg, me, Stoms, Stomi cephalometric points were measured in millimeters with mean and standard deviations were calculated.In the vertical plane linear changes at following hard tissue ANS, A, Is, Ii, B, PG, ME and soft tissue Sn, SLS, Ls, Li, SLI, pg, me, Stoms, Stomi cephalometric points were measured in millimeters with mean and standard deviations were calculated.Scatter plot diagram with correlation Regression Analysis was done for the following points Li vs Ii, SLI vs B, PG vs pg, ME vs me were done in both horizontal and vertical plane.Change in length of lower triad of face upper lip Sn-Stoms length and lower lip Stomi-me length were calculated along with mean and standard deviation.The mean change in facial profile, Nasolabial angle and mentolabial fold were calculat ed.The ratio of change in the soft tissue reference points will be compared with movements of corresponding 4 hard tissue references Li to Ii, SLI to B, PG to pg and ME to me in the horizontal plane.SURGICAL PROCEDUREAll the patients had undergone BSSO for correction of horizontal mandibular excess mandibular prognathism. All surgeries were carried out by the same surgeon.During the positioning of the patient before surgery the head end of the table is tilted by about 15. Hypotensive anaesthesia technique was used. Both these are think to reduce intra operative bleeding.At the beginning of the procedure 2% lignocaine hydrochloride with 1 2,00,000 epinephrine is infiltrated into the buccal vestibule upto the midramus vicinity of the mandible on both sides.Incision and dissectionThe incision is placed over the anterior aspect of the ramus extending from the midramus vicinity running down over the external oblique ridge upto the first molar region where it curves down to the buccal vestibule. Retracting the soft tissues buccally, before placing the incision prevents the initial exposure of the buccal fat pad. A sharp dissection is done in the ramus upto the periosteum.Periosteal dissection is started on the lateral aspect of the mandibular body from anterior ramus upto the second molar region extending to the inferior mete. On the lateral aspect of the ramus dissection may be miniskirtmal that to achieve proper access and visibility. Medial dissection is done subperiosteally with a Howarths periosteal elevator and should be above the level of lingula and mandibular foramen which usually coincides with the deepest concavity of the anterior border of ramus. Later a channel retractor is inserted for medial retraction so as to protect the mandibular neurovascular bundle.OsteotomyOsteotomy is done with surgical micromotor and burs. Its initiated on the cortical bone of the medial side of ramus above the lingula extending from behind the mandibular foramen half t o two-third of the anteroposterior dimension of the ramus running down onto the superior aspect of the body of the mandible and thus extended to the external oblique ridge over the lateral aspect of the mandibular body upto the 1st molar region.Extending the cut towards the 1st molar region gives better accessibility for intraoral plating. The depth of the cut should be minimal only to reach the cancellous bone. The vertical cut is extended to include the inferior border so that the direction of the split is controlled. During the vertical cut a channel retractor is placed on the lateral aspect so as to protect the buccal soft tissues and facial artery.Following the osteotomy, a small spatula osteotome is malleted into the site beginning from the medial cut, down the ramus, over the body upto the vertical cut. The spatula osteotome is directed laterally down the stairs the cortical plate so that the neurovascular bundle is protected. Later larger osteotomes are used and finally th e fragments are prised apart using a smith spreader.As the fragments are prised the neurovascular bundle is visualized and care is taken to maintain it to the medial tooth bearing fragment. If the neurovascular bundle is found to be attached to the proximal condylar particle a small periosteal elevator is used to free the bundle and bring it to the medial fragment. Once this is done osteotomes in a wedging fashion or the Smith spreader is used vigourously until the spilt of the fragments are completed. The osteotomy is repeated on the opposite side of the mandible. When the mandible is setback, release of the medial pterygoid and masseter muscle is stripped, if needed to prevent the displacement of the condylar segment posteriorly.Later the tooth bearing medial segment is pushed back as much as needed and the overlapping buccal plate of the proximal condylar segment is trimmed such that the proximal segment rest passively on the cancellous part of medial segment with condyle in pr oper position. stabilization and fixationThe position of jaw is adjusted and intermaxillary fixation is done with splint in position. Rigid internal fixation using 2mm four hole mini plate with gap and 2 6mm monocortical screws is the preferred way of fixation. The intermaxillary fixation is removed after the rigid fixation.Wound closureWounds are irrigated and bleeding is controlled. Wounds are unkindly with 3-0 vicryl sutures in layers.1