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Mandibular Prognathism by BSSO Study




  • Consisted of all the patients who reported to the Out Patient Team of Oral And Maxillofacial Surgery for correction of facial deformity concerning maxilla and mandible.


  • Consisted of 33 patients who underwent BSSO setback for mandibular prognathism followed by Rigid Internal Fixation at the Division Of Dental And Maxillofacial Surgery, Mar Baselios Tooth College.

Inclusion Criteria

  1. Patients above years of twenty years for males & 18 years for females.
  2. Patients who had been treated by BSSO setback along with Rigid Internal Fixation for mandibular prognathism.

Exclusion Criteria

  1. Patients having Bimaxillary surgeries.
  2. Patients considering Genioplasty along with BSSO.
  3. Patients with Medically compromised conditions.
  4. Patients with Craniofacial anomalies, Syndromes.

A retrospective research was conducted on 33 patients (15 females and 18 males), with mean age of 22 years (age range of 19 - 28 years), who were handled for mandibular prognathism by BSSO at the office of dental and maxillofacial surgery, Mar Baselios Tooth School, Kothamangalam. The patients were determined according to previously listed inclution and exclusion criterias. The medical procedure was done by one key operating surgeon. No maxillomandibular fixation was used postoperatively. Pre and postsurgical orthodontics was completed at the division of orthodontics and dentofacial orthopaedics, Mar Baselios Dentistry College, kothamangalam.

A standardised lateral skull radiograph with enough quality and vulnerability was considered pre operatively and after six months of follow up in natural mind position [Frankfurt's horizontal plane parallel to the floor, the tongue in comfortable position and the mandible in centric occlusion] with publicity ideals of 80 KVp, 10 mA, and 1. 30 mere seconds.

Tracings of the lateral cephalograms were pencil traced on acetate paper. To enhance the persistence the tracings and measurements were taken by the same investigator. Horizontal guide line was taken as 7 to SN at nasion. Vertical reference point line was built perpendicular to horizontal reference brand through Sella. Superimposition of traced preoperative and postoperative lateral cephalogram was done with respect to the horizontal and vertical research lines. The following cephalometric details and measurements were used.


Sella: Center of sella turcica


Nasion: Most anterior point of frontonasal suture


Anterior Nasal Back: Anterior tip of the sinus spine


Posterior Nasal Spine: The best posterior facet of the palatal bone


Point A: Innermost point on contour of maxilla between anterior sinus spine and incisor tooth


Incision Superior: Midpoint of incisal edge of most prominent maxillary central incisor


Incision Poor: Midpoint of incisal edge of most visible mandibular central incisor


Point B: Innermost point on contour of mandible between incisor tooth and bony chin


Pogonion: Most anterior point on osseous contour of chin


Menton: Most poor midline point on mandibular symphysis


Columella point: Midpoint of columella of nose


Subnasale: Point at which columella merges with upper lip in midsagittal plane


Superior Labial Sulcus: Point of best concavity in midsection of higher lip between subnasale and labrale superius


Labrale Superius: Most anterior point of higher lip


Labrale Inferius: Most anterior point of lower lip


Inferior Labial Sulcus: Point of most significant concavity in midline of lower lip between labrale inferius and smooth tissue pogonion


Soft Muscle Pogonion: Most visible or anterior point on chin in midsagittal plane


Soft Tissues Menton: Lowest point on contour of soft tissue chin


Stomion Superius: Most substandard point of top lip


Stomion Inferius: Most superior point of lower lip


Upper lip length


Lower lip length


Facial Convexity: Perspective between soft tissue glabella, subnasale and soft tissue pogonion


Nasolabial Position: Position between columella and labrale superius


Labiomental Flip: Perspective between lower lip and chin contour

Research methodology

  • In the horizontal plane linear changes at pursuing hard tissues [ANS, A, Is, Ii, B, PG, Me personally] and smooth cells [Sn, SLS, Ls, Li, SLI, pg', me', Stoms, Stomi] cephalometric points were assessed in millimeters with mean and standard deviations were computed.
  • In the vertical plane linear changes at pursuing hard structure [ANS, A, Is, Ii, B, PG, ME] and soft tissue [Sn, SLS, Ls, Li, SLI, pg', me', Stoms, Stomi] cephalometric items were measured in millimeters with mean and standard deviations were calculated.
  • Scatter plot diagram with Correlation & Regression Evaluation was done for the following things Li vs Ii, SLI vs B, PG vs pg', Me personally vs me' were done in both horizontal and vertical planes.
  • Change long of lower third of face; higher lip [Sn-Stoms] size and lower lip [Stomi-me'] length were computed along with mean and standard deviation.
  • The mean change in cosmetic profile, Nasolabial position and mentolabial collapse were calculated.
  • The proportion of change in the soft tissue reference points will be weighed against movements of equivalent 4 hard structure recommendations: Li to Ii, SLI to B, PG to pg' and ME to me' in the horizontal aircraft.


All the patients experienced been through BSSO for correction of horizontal mandibular surplus [mandibular prognathism]. All surgeries were carried out by the same plastic surgeon.

During the placement of the patient before surgery the top end of the desk is tilted by about 15. Hypotensive anaesthesia technique was used. Both these are designed to reduce intra operative bleeding.

At the start of the procedure 2% lignocaine hydrochloride with 1: 2, 00, 000 epinephrine is infiltrated into the buccal vestibule upto the midramus region of the mandible on both factors.

Incision and dissection

The incision is positioned above the anterior facet of the ramus stretching from the midramus region working down within the external oblique ridge upto the first molar region where it curves down to the buccal vestibule. Retracting the smooth tissue buccally, before placing the incision stops the initial coverage of the buccal fat pad. A well-defined dissection is performed in the ramus upto the periosteum.

Periosteal dissection is started out on the lateral aspect of the mandibular body from anterior ramus upto the second molar region stretching to the second-rate border. Within the lateral aspect of the ramus dissection may be little only to achieve proper access and presence. Medial dissection is done subperiosteally with a Howarth's periosteal elevator and should be above the level of lingula and mandibular foramen which usually coincides with the deepest concavity of the anterior boundary of ramus. Later a channel retractor is put for medial retraction to be able to protect the mandibular neurovascular bundle.


Osteotomy is done with operative micromotor and burs. Its initiated on the cortical bone of the medial side of ramus above the lingula increasing from behind the mandibular foramen [half to two-third of the anteroposterior dimension of the ramus] operating down onto the superior aspect of your body of the mandible and then prolonged to the exterior oblique ridge over the lateral facet of the mandibular body upto the 1st molar region.

Extending the trim towards the very first molar region offers better ease of access for intraoral plating. The depth of the lower should be minimal only to reach the cancellous bone. The vertical slice is extended to add the inferior boundary so that the direction of the divide is controlled. During the vertical slash a route retractor is located on the lateral aspect so as to protect the buccal soft tissues and facial artery.

Following the osteotomy, a small spatula osteotome is malleted in to the site beginning from the medial slash, down the ramus, over your body upto the vertical lower. The spatula osteotome is aimed laterally beneath the cortical plate so that the neurovascular bundle is protected. Later bigger osteotomes are being used and lastly the fragments are prised aside by using a Smith spreader.

As the fragments are prised the neurovascular package is visualized and health care is taken up to maintain it to the medial tooth bearing fragment. When the neurovascular bundle is found to be attached to the proximal condylar portion a tiny periosteal elevator is utilized to free the bundle and bring it to the medial fragment. Once this is performed osteotomes in a wedging fashion or the Smith spreader can be used vigourously until the spilt of the fragments are completed. The osteotomy is repeated on the contrary area of the mandible. Once the mandible is setback, release of the medial pterygoid and masseter muscle is stripped, if needed to avoid the displacement of the condylar section posteriorly.

Later the tooth bearing medial section is pushed back approximately needed and the overlapping buccal plate of the proximal condylar portion is trimmed such that the proximal segment slumber passively on the cancellous part of medial section with condyle in proper position.

Stabilization and fixation

The position of jaw is changed and intermaxillary fixation is done with splint constantly in place. Rigid internal fixation using 2mm four hole mini plate with space and 2 6mm monocortical screws is the most well-liked way of fixation. The intermaxillary fixation is removed following the rigid fixation.

Wound closure

Wounds are irrigated and bleeding is operated. Wounds are closed with 3-0 vicryl sutures in levels.


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