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OMFS-0137ReconstructionadvancedMaxilla and mandible

Class III skeletal deformity with anterior crossbite

23-year-old male

Draft — educational study aid, pending faculty review.

§Chief complaint

Lower jaw sticks out and I cannot bite my front teeth together

§Medical & dental history

  • 01Fit and well; growth complete confirmed on hand-wrist radiograph
  • 02Full dentition, good oral hygiene, pre-surgical orthodontics for 14 months

§Clinical examination

  • 01Concave profile, prominent chin, negative overjet of 6 mm
  • 02Maxillary hypoplasia with paranasal flattening; lower facial third increased
  • 03Class III molar and canine relationship bilaterally, anterior and posterior crossbite
  • 04TMJ asymptomatic, mouth opening 48 mm

§ figuresFigures (2)

Fig. 1Pre and post Orthodontics were done by Dr, Vipin Challiyil and Orthognathic surgery was done by Dr. Aju Ommen .

“Orthognathic surgery” · Challiyan · CC BY-SA 4.0 · Wikimedia Commons

Fig. 2Osteotomies of the maxilla and mandible. 1. Lefort I 2. Bilateral sagittal split 3. Genioplasty

“Orthognatic surgery” · Henry Grey · Public domain · Wikimedia Commons

Verified open-access images only, reproduced for education under their stated licences · no AI-generated or illustrative artwork · Orthognathic Surgery figures pending faculty review.

§Differential diagnosis

Skeletal Class III from maxillary hypoplasia with mandibular prognathismCephalometric SNA reduced, SNB increased, ANB negative
Dentoalveolar Class III (pseudo Class III)Correctable by orthodontics alone; forward mandibular posturing
Condylar hyperplasiaProgressive asymmetry with active uptake on bone scan
Post-traumatic malocclusionHistory of facial fracture

§Final diagnosis

Skeletal Class III deformity: maxillary hypoplasia with mandibular prognathism, requiring bimaxillary surgery

Cephalometric analysis distinguishes true skeletal Class III from a dentoalveolar (pseudo) Class III, which can be corrected by orthodontics alone. A negative ANB with reduced SNA confirms the maxilla is the major contributor here, so a bimaxillary approach gives the best facial result.

§Investigations

  • 01Lateral cephalogram — SNA 76, SNB 85, ANB -9 degrees
  • 02CBCT with 3D virtual surgical planning and printed splints
  • 03Study models and digital occlusal set-up
  • 04Photographic and functional records; bone scan to confirm no active condylar growth

§Treatment plan

  • 01Pre-surgical orthodontic decompensation (completed)
  • 02Bimaxillary surgery: Le Fort I maxillary advancement 5 mm with mandibular setback 4 mm via BSSO
  • 03Genioplasty as required for chin projection
  • 04Post-surgical orthodontics and long-term retention

§Surgical procedure

  • 01Le Fort I osteotomy, downfracture and advancement, fixation with four L-shaped plates
  • 02Bilateral sagittal split osteotomy setback with bicortical screws, IAN identified and protected
  • 03Intermediate and final splints from virtual planning; occlusion checked before closure

§Follow-up & outcome

  • 01Guiding elastics for 4 weeks; soft diet 6 weeks
  • 02Stable Class I occlusion at 6 months
  • 03Lower lip paraesthesia largely resolved by 9 months; patient satisfaction high

§Clinical pearls / learning points

  • 01Decompensate the arches fully before surgery or the skeletal movement will be limited.
  • 02Inferior alveolar nerve disturbance after BSSO is common and must be consented for explicitly.
  • 03Virtual surgical planning improves accuracy but does not replace intraoperative occlusal checking.

§References

  • Proffit WR, White RP, Sarver DM. Contemporary Treatment of Dentofacial Deformity.

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