This is about the pre-surgical procedures which have to be analyzed before the orthognathic surgeries of mandible.

1. ORTHOGNATHIC SURGERIES OF
MANDIBLE
By:
Dr. R. Seshan Rakkesh. B.D.S

2. Synopsis:
 Introduction
 Types of Skeletal and Dentofacial deformities.
 Associated problem list.
 Clinical features.
 Treatment List.
 Presurgical Analysis
 Collecting patient data
 Frontal view analysis
 Profile
 Final treatment options.

3.  Defenition:
Introduction:
 It is the surgery in which the jaw bones are intentionally
sectioned at various sites to correct the dentofacial
deformities and then repositioned at the desired
position.
 Osteotomy:
 Simple splitting of the bone.
 Ostectomy:
 Removal of part of the bone .

4. Dentofacial deformities are considered in three planes
- Antero posterior plane
- Vertical plane
- Transverse plane

5. Types of Severe Skeletal and Dentofacial
 Mandibular
Excess : Mandibular prognathism
Deficiency : Mandibular retrognathism
 Maxilla
Excess : Vertical Maxillary Excess (VME)
Deficiency : Vertical Maxillary Deficiency
(VMD)
Deformities.

6.  Combination
 Bimaxillary protrusion.
 Nasomaxillary hypoplasia associated with prognathic
mandible.
 Nasomaxillary hypoplasia associated with cleft lip and palate.
 Facial Symmetry
 Asymmetric prognathism of the mandible.
 Unilateral condylar hyperplasia.
 Hemifacial hypertrophy (rare)

7. Clinical Features:

8. MANDIBULAR EXCESS:
• Facial Features:
1. Prominent chin is the dominant feature
2. A Concave profile.
3. Lip incompetance.
4. Obtuse gonial angle.
5. Middle third of the face appears to be deficient.
6. Labiomental fold may be diminished / absent.
7. Nasolabial angle may be acute.
8. Anterior facial height may be increased.

9. • Dental Features:
1. Angle’s class III malocclusion will be seen.
2. Reverse horizontal overjet in the incisor area.
3. Posterior cross bite.
4. Maxillary teeth may be protrusive.
5. Mandibular anterior teeth may be tilted lingually
6. An anterior open bite may be seen.

10. MANDIBULAR DEFICIENCY
 Facial features:
 Convex profile.
 Bird face deformity.
 Short upper lip.
 Everted lower lip.
 Acute gonial angle.
 Lip strain evident during closure of mouth.

11.  Dental features:
 Angle’s class II molar malocclusion.
 Increased overjet.
 Accentuated curve of spee of lower anterior.
 Fanning of lower anterior teeth or crowding.
 Skeletal deep bite may be present.

12. CONDITIONS WITH FACIAL ASYMMETRY.
 Asymmetrical mandibular prognathism.
 With anterior open bite .
 Without anterior open bite.
 Unilateral condylar hyperplasia.
 Hemimandibular elongation.
 Hemimandibular hypoplasia.
 Hemifacial hypertrophy (rare).

13. Asymmetrical mandibular prognathism
 With Anterior open bite:
 Severe facial asymmetry
 Eccentric bilateral mandibular protrusion.
 Deviation of the chin.
 High gonial angle.
 Midline of mandibular arch shifted
 Without anterior open bite:
 Eccentric bilateral mandibular protrusion.
 Deviation of chin.
 Class III dental malocclusion.
 Associated mandibular hypoplasia.

14. Unilateral Condylar Hypoplasia
 Hemimandibular Elongation:
 Horizontal displacement of mandible & chin to
unaffected side.
 Lateral crossbite on unaffected side.
 Occlusal plane slopes upward to the unaffected side.
 Sever cases – Lateral open bite on the affected side.
 IOPA, OPG – Elongation of the condyle.
 Hemimandiblar hyperplasia:
 One side of face enlarged.
 Unilateral bowing of inf. Border of mandible.
 Lip line slopes downward on affected side.
 Associated TMJ pain symptoms on the affected side.
 RADIOLOGICALLY – Enlagered hemimandible on the
affected side.

15. ASSOCIATED PROBLEM LIST
 Esthetic problem.
 Functional problems.
 Psycological problems.
 Impairment of mastication.
 Associated speech problems.
 Succeptibility to caries and periodontal problems.
 Possibe TMJ joint pain dysfunction.
 Impact on digestion – general health.

16. TREATMENT OPTIONS
 Severe skeletal dentofacial deformity can be correted
by:
 Growth modification.
 Orthodontic camouflage.
 Orthognathic surgery.

17. GROWTH MODIFICATIONS
 Useful in children where the growth potential and
modification of growth can be achieved.
 Achieved using.
 High pull headgear – complete or partial maxillary fixed
appliance.
 Myofunctional appliance – 14 to 16 hrs a day.
 Limitations – only small amount of changes can be
brought.

18. ORTHODONTIC CAMOUFLAGE
 Biologically accepted compensations, to mask the
skeletal malocclusion by orthodontic treatment.
 Done only if:
 Orthodontist is able to carry out biologically acceptable
dental compensations.
 With desired soft tissue results.
 Willingness of patient to cooperate.
 Growth potential study is done.

19. ORTHOGNATHIC SURGERY
 Surgical repositioning of the jaw and / or
dentoalveolar segments.
 For correction of severe skeletal discrepancy.

20. Objective of surgery
 Achieve best function.
 Achieve best aesthetics.
 Achieve best stability.
 Oral and Maxillofacial surgeons and
Orthodontist are equal partners.

21. Timing of surgery
 Can be done only when the patient is in
actively growing stage.
 Must be warned about the resurgery later on.
 Best timing is when the growth potential of
patient is over.

22. Diagnosis and Treatment planning
 Phase 1:
 Assemble the database.
 Synthesize the problem list.
 Diagnosis.
 Team conference.
 Phase 2:
 Interdisciplinary problem list.
 Dentofacial problems in order of priority.
 Tentative treatment plan.
 Patient / team conference.
 Definitive plan.

23.  Phase 3:
 Preparatory therapy – endodontic periodontics, prosthesis.
 Definitive orthodontic – surgical treatment.
 Continuous team monitoring, re-evaluation, interaction,
modifying therapy.
 Phase 4:
 Maintenance.

24. Goal of surgery
 Produce a concise list of patient’s problems.
 Synthesize the various treatment possibilities into a
rational plan that gives maximum benefit to patient.

25. STEPS IN PROCESS
 Personal data.
 Facial esthetic analysis.
 Lateral cephalometric analysis
 Occlusal analysis and Model analysis
 Dental arch form
 Dental alignment
 Dental occlusion.
 Tooth mass relation
 Final treatment plan
 Presurgical orthodontics.
 Surgery plan
 Postsurgical orthodontics
 Maintenance.

26. Facial esthetic analysis
 Two types of facial analysis is done before the surgery.
They are.
 Frontal view analysis
 Profile / lateral view analysis
 Face is divided into
-upper third
-middle third
-lower third
 Face evaluation
-patient is asked to sit in upright position
-pupillary plane ,plane of ear,frankfort horizontal
plane parallel to the floor
-patient should be examined with the teeth in centric
position, relaxed lips& in straight position

27. Frontal view analysis
 14 landmarks are to be assessed in the front view analysis
as recommended by LARRY WOLFORD.
 Forehead, eyes, orbits and nose – symmetry, size and
deformity.
 Normal intercanthel distance is 32 + 3mm.
 Normal intepupillary distance is 65 + 3mm.
 Intercanthal distance, alar bone width and palpebral fissure
width must be equal..
 1/2* intercanthal distance = width of nasal dorsum.
2/3* intercanthal distance = width of nasal lobule.
 Vertical line through medial canthus and perpendicular to the
pupillary plane should be + 2mm on the alar bases.
 Upper lip
males – 22 + 2mm
females – 20 + 2mm

28.  Normal upper tooth to lip relationship exposes 2.5 + 1.5 mm
of incisal edge with lips in repose.
 Face should be reasonably symmetric, both vertically and
transversely.
 lip incompetence if present should be measured from
upper lip stomion to lower lip stomion in centric occlusion
and lip repose (0-3 mm)
 Smile line –
 The vermilion of the upper lip should fall at the cervicogingival
margin with 1-2 mm of exposed gingiva. ( asked to give full
smile to detect a ‘gummy smile’).
 The distance from the gabella to subnasal and subnasal to
menton should be 1:1.(upper lip length normal).
 The length of the upper lip should be 1/3 the length of
lower facial third.
 Lower eyelid in level with or slightly above most inferior
aspect of iris.

29. Profile or Lateral view analysis
 For determining vertical and antero -posterior plane
problems of the jaws.
 Facial profile can be:
 Straight profile.
 Convex profile.
 Concave profile.

30.  Facial contour angle :
 Relative cancavity or convexity of the facial profile.
 Normal -> -8 to -11 degrees.
 Formed between the upper facial contour plane and the
upward extension of the lower facial contour plane.
 If angle is anterior to the upper contour plane then it is
negative.
 Nasolabial angle :
 Formed at the subnasale by a line drawn tangent to the
base of the nose with a line from the upper lip to
subnasale.
 Normal -> 100 ° to 110° in males and 110 ° to 120 ° in
female
 Larger angulation indicates convex face ( associated to
recessive chin).

31.  Lip position :
 Upper lip must protrude over lower facial contour plane by
3.5mm.
 Lower lip protrude by 2.2mm.
 Lower lip, Chin-throat angle :
 Angle between a line from the lower lip to the soft tissue
pogonion and a line drawn tangent to the soft tissue contour
below body of mandible.
 Normal -> 110 ° + 8 °.
 Larger angulation indicates recessive chin.
 Lower angulation indicated excessive chin.
 Chin to throat length :
 Distance between angle of the throat and soft tissue menton.
 Normal -> 51 + 6 mm.
 Increased value shows concave face and acute lower lip, chin
throat angle.

32. Evaluation of 5 major esthetic masses
of the face.
Forehead Nasofrontal angle
Eyes Interpupillary distance – 6.5 mm
Intercantha distance – 3.5 mm
Outercanthal disance – 9.8 mm
Nose Length, width, projection and
nasolabial angle - 90° to 120°
Lips Interlabial gap – 3 mm
Length, width, procumbency and
recumbency
Chin Mentolabial sulcus, lip chin complex,
Prominence and deficiency.

33. Oral Examination
 Basic occlusal relationship
 Anterior overbite or open bite
 Anterior overjet and any cross bite
 Health of the dentition
 Tooth size discrepancies
 Curve of wilson & spee
 Dental crowding
 Missing, carious, periodontal evaluation
 Anatomical functional tongue abnormalities
 Dental modal analysis

34. CEPHALOMETRIC ANALYSIS
 By SALZMAN(1964)
 Establishing two dimensional relationships of craniofacial
components
 Classifying skeletal &dental abnormalities
 Analyzing growth & development responsible for
dentofacial pattern
 Planning treatment for orthodontic
 Determining dentofacial growth changes at after treatment
 Predicting hard & soft tissue contours

35. SOFT TISSUE LANDMARK
 Glabella
 Soft tissue nasion
 Subnasaale
 Labiale superius
 Labiale inferius
 Soft tissue pogonion
 Soft tissue menton
 Angle of throat
 The upper&lower facial contour plane

36. CEPHALOMETRIC PREDICTION
TRACING
 By BELL,PROFITT,WHITE(1980)
 Simple and accurate method of prediciting results
 Quantification of the surgical movements
 Accurately predict the resultant facial profile
 Provides a visual aid with a single overlay
 Comparing with actual postsurgical
cephalometric tracing for re-evaluating
the surgical results

37. Posteroanterior cephalometric
analysis
 Assessing asymmetry of the facial skeleton by using three
vertical lines
 FIRST LINE-Midline of nose&chin&dentalarch
 SECOND LINE-Line passing through zygomatic arch
 THIRD LINE-Passing through the angle of the mandible

38. CEPHALOMETRIC POINTS&PLANES
 Nasion
 Anterior nasal spine
 Sella
 Pogonion
 Posterior nasal spine
 Point(A)
 POINT(B)
 Subnasale

39. MADIBULAR SURGERIES

40. Types of surgery
 Two types of mandibular surgeries.
 Mandibular body osteotomies.
1. Intraoral procedures.
 Ant. Body osteotomy
 Post. Body osteotomy
 Midsymphysis osteotomy
2. Segmental subapical mandibular surgeries.
 Ant. Subapical mandibular osteotomy.
 Post. Subapical mandibular osteotomy.
 Total subapical mandibular osteotomy.
3. Genioplasties.
 Augmentation genioplasty
 Reduction genioplasty
 Straightening genioplasty
 Lengthening genioplasty

41.  Mandibular ramus osteotomies
1. Subcondylar ramus osteotomy
 Extraoral subcondylar ramus osteotomy(subsigmoid).
 Intraoral subcondylar ramus osteotomy(subsigmoid).
 Arching ramus osteotomy(extraoral).
2. Intraoral modified sagittal split osteotomy.

42. SOFT TISSUE INCISIONS
 Mand. Body surgeries - Degloving vestibular incision
intraorally.
 Extra oral ramus osteotomies - submandibular
Ridson’s incision and postramal Hind’s incision.
 Intra oral ramus osteotomies – incision similar to 3rd
molar extraction.

43. Anterior Body Osteotomy
 INDICATION:
 Mandibular prognathism with functional posterior
occlusion
 Class III malocculsion with or without anterior open
bite

44. Posterior body steotomy
 INDICATION
 Missing Posterior teeth
 Class III deformity
 For correction of Cross Bite

45. Midsymphysis Osteotomy
The Complete vestibular incision can be planned if it is
combined with posterior or anterior body osteotomy

46. Segmental Subapical Mandibular
Surgeries
 Used to reposition anterior,posterior oe entire
mandibular dentoalveolar segment
 Ant. Subapical mandibular osteotomy.
 Post. Subapical mandibular osteotomy.
 Total subapical mandibular osteotomy

47. Anterior Subapical Mandibular
Osteotomy
INDICATION
 Correcting mandibular dento alveolar proclination
 Closing mild anterior open bite
 Leveling an accentuated curve of spee
 Correcting mandibular dental arch asymmetry
Used as an adjunctive with other surgical procedures:
 With anterior maxillary osteotomy to correct bimaxillary
protrusion
 With mandibular advancement to level the curve of spee
 With genioplasty procedure

48. Posterior Subapical Mandibular
Osteotomy Procedure
INDICATION
 Uprighting the posterior segment which is in extreme
linguoversion or buccoversion
 Closing a Premolar or molar space
 Levelling Supraerupted Posterior teeth

49. Total Subapical Mandibular
Osteotomies

50. GENIOPLASTIES
 Genioplasty can be used as a single procedure or it
can be used as an adjunctive procedure along with
other major osteomies of the jaw bone.
 Deformities of the chin should be considered in all 3
planes,
 AP
 Vertical
 Transverse
 It can be used to augment, reduce, straighten or
lengthen the chin.

51. Augmentation Genioplasty
 Used to increase the chin projection.
 Sliding horizontal osteotomy of the symphysis
region.
 Autogenous bone graft
 Alloplastic material – silastic, hydroxyapatite.

52. Reduction Genioplasty
 Reduction of the symphysis region can be achieved
both in the anteroposterior and vertical planes or in
both planes depending on the need of the patient.

53. Straightening Genioplasty Procedure
Indication:
* In Facial asymmetry, where the complete correction of the
asymmetry cannot be achieved by appropriate jaw osteoto
mies. E.g., TM joint ankylosis.
* The horizontal osteotomy is done and segment Is shifted
laterally and than contoured to get desired result.

54. MANDIBULAR RAMUS
OSTEOTOMIES

55. Subcondylar Vertical Osteotomy
 It was proposed by Caldwell – Letterman in 1954.
 The indications for extraoral subsigmoid vertical
ramus osteotomy are,
 Major setback of mandible more than 10 mm.
 Asymmetric setback of the mandible.
 Reoperation of previously operated case.

56. Intraoral Modified Sagittal Split
Osteotomy
 Also called as - Bilateral Sagittal Split Osteotomy
 It performed on the mandibular ramus and body.
 First described by Obwegeser and Trauner and later modified by
Dal Pont, Hunsuck and Epker.
 Transoral incision, similar to that used for IVRO.
 The osteotomy splits the ramus &the posterior body of the
mandible sagittally, Which allows either setback or
advancement.
 This is highly cosmetic procedure, as it is done intraorally plus
there is broader bony contact of the osteotomised segments
ensuring good healing.
Drawback:
* High level of operative skill
* Experience tominimize the surgical complication.