Orthognathic surgery decision making , treatment planning and timing of surgery

 

Presented by Dr. Cathrine Diana PG III

1.Introduction to craniofacial deformities

a. Various treatment options

2. Introduction to orthognathic surgery

a. History

b.Timing of surgery

A. Indication

B. Basic therapeutic goals

C. Soft tissue limitation

3. Data collection

4. diagnosis/problem list

5. cephalometric analysis

6. Treatment plan

7. prediction tracing

8. Model surgery

9. virtual treatment planning

10. Predictable Soft tissue changes

• Leo Tolstoy said that , “ i Am convinced that nothing has so marked influence on the direction of a man’s mind as his appearance…

Introduction

• genetic factors• environmental factorsPre-natal

• genetic factors• environmental

factorsPost-natal

• All these factors give rise to the following types of changes in craniofacial skeleton for which the patient seeks correction

Combination

Transverse defect

Antero- posterior

defect

Vertical defect

Various treatment options

1. Growth modification by dentofacial orthopedics:

1.

• to alter the growth pattern by changing the relationships of the jaws

• In growing age

2.• Accurate diagnosis• Appropriate direction and amount of force

3.

• Prolonged treatment time• Patient non- compliance• Expensive • Variable stability

Camouflage by orthodontic

• mild skeletal discrepancy

• Accepted soft tissue profile

• satisfactory occlusion at the expense of facial aesthetics.

Envelope of discrepancy

• Maxilla Mandible

3 5 252

5

15

51012

4

6

10

7 12 15

25

15

25104

6

10

Orthognathic surgeryGrowth modulationOrthodontic treatment

Orthognathic surgery

• the art and science of diagnosis, treatment planning and execution of

treatment by combining orthodontics and oral and maxillofacial surgery to

correct musculoskeletal, dento-osseous and soft tissue deformities of the

jaws and associated structures.

• Dr. Harold Hargis coined the term orthognathic surgery

• Hullihen is regarded as the first surgeon to describe a mandibular

orthognathic surgical procedure. In 1849, he reported an anterior

subapical osteotomy.

• Jaboulay and Berard (1898), Kostecka (1931) performed operations on

condylar neck and upper part of ramus by closed blind approach.

• Surgical treatment for mandibular prognathism started in early 19th

century.

• In 1959, Trauner and obwegeser introduced sagittal split osteotomy as the

beginning of a new era of orthognathic surgery.

• American surgeons modify the technique for maxillary surgery that has

been developed in Europe

• Epker, bell and wolford developed lefort-1 maxillary downward

fracture ,so that we can keep the maxilla stable in all 3 planes of spaces

• By 1980 progress has reached such an extent to reposition either or both

the jaws to move chin in all 3 planes of spaces. Rigid internal fixation made

it possible for comfort and better immobilization was achieved

Timing

After growth completion – only treatment option

Delay in mandibular prognathism

Rarely done before adolescent growth spurt

Indication

• Impaired mastication

• TMJ pain and dysfunction

• Psychological effects

• When dentofacial orthopaedics can no longer prevent severe jaw

discrepancy.

• When skeletal discrepancy is too severe to be corrected by orthodontics

alone to give a satisfactory dental occlusion and facial aesthetics.

• Internally motivated patient

Basic therapeutic goals

function

aesthetics• macro• mini• micro

stability• Minimal

treatment time

Basic therapeutic goals

Soft tissue limitations

• Pressure on teeth by lips ,cheek, tongue -STABILITY.

• Periodontal attachment apparatus -ORAL HEALTH.

• Temporo-mandibular muscular and connective tissue attachments-

FUNCTION.

• Soft tissue integuments of face primarily determine AESTHETICS.

Data collection

• Patient concerns or chief complaints

• Clinical examination

• Radiographic imaging and analysis

• Dental model analysis

Patient interview

• Chief complaint of patient

• Patient concern and motivation

• Time and cost of surgery and treatment on the whole.

Co -decision maker

Problem list

Risk – benefits

Alternate treatments

Patient expecttion and reality

History taking

• Medical history

• Dental and orthodontic history

• Diagnostic factors and risk factor:

• Congenital or developmental deformity

• Acquired deformity

• TMJ dysfunction

• Infection, psychological impairment, bone and soft tissue pathoses

• Bleeding dyscrasias, compromised vascularity

• Allergies, respiratory problem, poor patient compliance, neuromuscular

imbalance.

• Habits – mouth breating, thumb sucking, tongue thrusting

Patient preparation

• The patient should sit upright in a straight-backed chair with the examiner

seated directly opposite at eye level.

• The Frankfort horizontal plane should be parallel to the floor.

• mandibular condyles should be seated in glenoid fossae with the teeth

lightly touching.

• Evaluate centric occlusion and centric relation.

• Patient’s lips should be relaxed and not forced together

Frontal facial evaluation

The distance from glabella to subnasale and subnasale to menton should be approximately in a 1:1 ratio, providing that the upper tip length is normal.

• Forehead, eyes, orbits and nose are

evaluated for symmetry, size and deformity.

• Symmetry of canthi

• Eyelids – ptosis, entropion, ectropion

• Sclera, ocular imbalance

• Scleral show – mid facial defieciency

• ICD -32 ± 3 mm and 35 ± 3 mm blacks

• IPD65 ± 3 mm.

• The intercanthal distance, alar base width

and palpebral fissure width should all be

equal.

Frontal facial evaluation

Width of nasal dorsum should be one half

the intercanthal distance and width of the

nasal lobules should be 2/3rd the

intercanthal distance.

• A vertical line through the medial canthus

and perpendicular to the pupillary plane

should fall on the alar bases ± 2 mm

• Cheek prominence

• 8 – 12 mm laterally and 10 – 20 mm

inferior to lateral canthus

•Ears -Upper 1/3rds just above the canthal

level.

Frontal facial evaluation

Lips• Width of lips equal to interpupillary distance• If asymmetry exists- Cleft lip- Facial nerve dysfunction- Dental skeletal deformity• Lip incompetence is common in children• What looks like incompetent lips in childhood or early adolescence is

merely a reflection of incomplete soft tissue growth• Females : Upper lip - till 14 yrs, Lower lip - continues to grow up to the age

of 16• Males : growth of both upper & lower lip continues till late teens• The length of the upper lip should be 1/3rd the length of the lower facial

third, almost 22 ±2 mm in males and 20 ±2mm in females

A normal upper tooth – to lip relationship

exposes 2.5 ± 1.5 mm of incisal edge to

lips.

The facial midline, nasal midline, lip

midline dental midline all should be in line

and face should be reasonably symmetric,

vertical and transversely.

During smiling the vermilion of the upper

lip should fall at the cervicogingival

margin with no more than 1 to 2 mm of

exposed gingival.

Lips

Profile view• Fore head Slopes anteriorly

• Accentuated at supra orbital rim

• Frontal bossing

• Supra orbital hypoplasia• The distance form glabella to subnasale and

from subnasale to soft tissue menton should be in a 1:1 ratio if the upper lip length is normal.

• Lateral orbital rims – 8 to12 mm behind the anterior projection of globe. Globe is 0-2 mm anterior to IO rim

• A line perpendicular to Frankfort horizontal and tangent to the globe should fall on the infraorbital soft tissues ± 2 mm.

• Alar base has to be supported by skeletal

nasal bone.

• Nasal bridge – 5 – 8 mm ant to globes

• Nasal tip ( prn ) – subnasale : subnasale –

alar base crease = 2:1

• If values of 1: 1 – maxillary defeciency

• Naso labial angle – 90 to 110 degrees

• The length of the upper lip should be 1/3rd

the length of lower facial height (third). Lower

lip stomion to soft tissue menton should be

twice the vertical dimension of the upper lip if

the upper lip is normal in length

Profile view

Clinical facial examination - Profile view

• Mandibular area

With the maxilla in normal AP

position and the upper lip normal

thickness, ideal chin projection is 3

± 3 mm posterior to a line through

subnasale that is perpendicular to

a clinical Frankfort horizontal.

Labiomental fold

• The labiomental sulcus should form a shallow S curve, with the upper and lower portions similarly shaped. The prominence of the chin should be slightly less than the prominence of the lower lip.

– Neck – chin angle – 110

– Throat length– 50 mm

• skin laxity, cervical facial lipomatosis, high mandibular plane angle are conditions – obscure the definition

TMJ Examination

•The range of movements

• Deviation from normal

movements

• Any pain during movement

• The joint sounds.

Intra-oral examination

• Periodontal health (pre-existing periodontal disease exacerbated with

orthodontic treatment) along with H/O smoking, excess alcohol

consumption, bruxism etc. check adequacy of attached gingiva, especially

in mandibular anterior region. Correct these problems if present.

• Tooth size discrepancy

• Occlusal relationship (class I, II, III)

Dentition• Vertical– Overbite– Plane of occlusion– Curve of spee

• Transverse :

Posterior Cross bite – max. deficiency

Horizontal• Anatomical variation• Crowding / spacing• Overjet• Missing, decayed, retained primary teeth• Impacted teeth

Soft tissues

• General periodontal condition

• Tongue size, position and activity

• Mentalis muscle activity

• Finger or thumb sucking

Evaluation Of nose

• H/O nasal trauma, nasal airway obstruction, allergies, sinus problems, mouth vs. nasal breathing and previous surgeries

• Examination of internal and external nasal structures.

Photographs

• To keep a record of the clinical findings. Photographs are taken at different angles:

• Frontal view – at rest and smiling

• Profile view• Oblique View• Occlusion/bite• Canting

Pre-surgical orthodontics

The basic presurgical orthodontic goals are as follows:• Align and position teeth over basal bone• Avoid excessive intrusion or extrusion of teeth• Decompensate teeth• Avoid unstable expansion of the dental arches• Avoid class II and class III mechanics (unless required for dental

decompensation correction in the arches)• Perform stable and predictable orthodonticsTreatment includes: inter-proximal reduction of teeth (slenderizing teeth), space creation, extractions, altering axial and mesio-distal inclination on incisors, protraction and retraction of teeth, distalization of posterior teeth and various inter-arch mechanics.

• Positioned Long axis of max. CI 22 ° and labial surface is 4 mm anterior to

the NA line

• Positioned maxilla and normal occlusal plane angle.

• Positioned Long axis of mand. CI 20 ° and labial surface is 4 mm anterior

to the NB line

• Satisfy arch length requirements

• Pre-surgical phase takes 24 – 30 months.

Radiographs

Lateral Cephalograms: taken with jaws in CR, teeth slightly touching and lips

relaxed. If bite is closed, second lateral ceph is taken with condyles still in CR

but jaws open till lips just begin to separate. Head position such that FH is

parallel to the floor. Intensifying screens may be used for proper visualization

of hard and soft tissues.

• P-A  Cephalograms: taken to asymmetries. Head is kept 5 degrees down

from clinical FH plane.

• OPG and IOPAs: taken to assess tooth alignment, root angulation, pathosis

and nerve/canal position assessment

• Other radiographs like TMJ tomograms, water’s view, CT, MRI may be

taken if required (Eg. CT may be done in cleft cases to determine the

amount of bone in the cleft)

Dental study models

• Arch length analysis• Tooth size analysis• Incisor angulation• Arch width analysis• Curve of Spee/ wilson• Cuspid-molar relation• Tooth arch symmetry

Diagnosis and treatment planning

 • Keep in mind: treatment of patient not photograph/radiograph Developing diagnostic list• Functional problems• Aesthetic problems • Dental problems• The jaws relation and facial proportion including the nose and the

ears.• Periodontal condition.• Speech pattern.• Psychological condition.

Cephalometric analysis

• The cephalometric analysis helpful in diagnosing the problem, helps in treatment planning and also allows clinician to evaluate changes after surgery.

• These analyses primarily designed to evaluate the position of the teeth with the existing skeletal pattern.

• HARD TISSUE ANALYSIS - COGS, STEINERS, WITS APPRAISAL, SCHWARZ ANALYSIS

• SOFT TISSUE ANALYSIS -COGS, HOLDAWAY• PA CEPH ANALYSIS FOR SYMMETRY – gurmmons analysis

COGS analysis

HORIZONTAL PLANE (HP), which is a surrogate Frankfort plane, constructed by drawing a line 7 o from the line S to N.

• Ar- PTM :– The relationship of maxilla to

the cranial base

Horizontal skeletal profile

• N-A –Pg (Angle): gives an indication of the overall facial convexity. A positive (+) angle of convexity denotes a convex face; a negative (-) angle denotes a concave face.

Vertical skeletal and dental

• Middle third facial height : Distance from N to ANS

• Posterior maxillary height : PNS-N

• Lower third facial height : ANS – GN

• Divergence of mandible posteriorly : M.P-H.P angle(clockwise or counter - clockwise rotations of the maxilla and mandible)

• U1 to NF: Anterior maxillary dental height

• L1 to MP: Anterior mandibular dental height

These two measurements define how far the incisors have erupted in relation to NF and MP respectively.

• Max. molar to NF : Posterior maxillary dental height

• Mand. Molar to MP: Post mandibular dental height

Max-mand. Relation• ANS-PNS: This measurement along with the

N-ANS and PNS– N gives a quantitative description of the maxilla in the skull complex.

• Ar - Go : Length of Mandibular ramus

• Go - Pg : Length of Mandibular body

• Ar - Go - Gn Angle : Gonial angle that represents the relationship between ramal plane and MP. Vertical /Horizontal growth

• B - Pg : Distance from B point to line perpendicular to MP through Pg describes chin prominence.

Dental

• OP- upper HP:

• AB – OP:

• U1 to NF angle & L1 to MP angle: These angulations determine the procumbency or recumbency of the incisors.

Steiner’s analysis

S.No

Measurement Mean

1. SNA 820

2. SNB 800

3. ANB 20

4. SND 760

5. M.P to SN 320

6. U1 to N-A 4mm

7. U1 to N-A (angle) 220

8. L1 to N-B 4mm

9. L1 to N-B (angle) 250

10. Interincisal angle 1300

11. Occ. Plane to S-N (angle) 140

Wits appraisal

• AO is 2mm ahead of BO - skeletal class I

Holdaway’s soft tissue analysisMeasurement Mean

Facial angle 90-920

Upper lip curvature 1.5-4mm (2.5)

Skeletal convexity at point A

-2 to +2

H-line angle 7-150

Nose tip to H-line Upto 12mm

Upper sulcus depth 3-7mm

Upper lip thickness 15mm

Upper lip strain Same as ULS

Lower lip to H-line 0mm -1to +2mm

Lower sulcus depth 5mm

Soft tissue to chin thickness

10-12mm

Cogs soft tissue analysis

The first horizontal plane

connects the medial aspects of

the zygomaticofrontal sutures.

The second horizontal plane

connects the center of the

zygomatic arches.

The third horizontal plane

connects the jugal processes.

A fourth horizontal plane runs

through the menton and is

parallel to the first plane

Grummons article JCO 1987

Gurmmon’s analysis

MSR-J maxillary width

MSR-Ag mandibular width

MSR-NC width of NCNasal septum deviation

MSR-Co Asymmetry in condyle

MSR-Me Mandibular symmetry

LINEAR ASYMMETRYMAXILLARY MANDIBULAR COMPONENTS

Limitations of cephalometric analysis

1)Growth pattern not taken into consideration

2)Mean values are based on different population

3)Two dimensional representation of three dimensional object

4)Form and functions not taken into consideration

Prediction tracing (surgical treatment objective /STO)

• Establish pre-surgical orthodontic goals• Develop accurate surgical objective that will achieve the best functional

and esthetic results• Create a facial profile objective that can be used as a visual aid in

consultation with patient and family members.

Prediction tracing (surgical treatment objective /STO)

• Only maxillary surgery – vertical position • Only mandibular surgery• Double- jaw surgery1. Vertical position of maxillary incisor2. A-P position of maxillary incisor3. Occlusal plane angulation

Computerized Chephalometry• First, Profile Image & Lateral

Cephalogram of the patient should be

taken in Natural Head Position.

• An image of lateral cephalogram is

scanned into pt’s file or direct digital

cephalogram is entered.

• An “electronic tracing” is then

produced by using digitization pad to

enter points.

• Pt’s Profile Image is then entered into

file.

Computerized Chephalometry• Digital tracing is then “sized” to fit &

coordinate with the facial image, using

profile as the overlay reference.

• The small boxes on teeth & jaws seen

at this point respresent treatment

“handles” by which teeth & osseous

segments can be moved in simulation

of treatment changes.

Analytic model surgery

Facebow transfer and mounting

Reference line marking

Analytic model surgery

1. Isolated mandibular surgery2. Isolated maxillary surgery3. Segmental maxillary surgery4. Combined – doublejaw surgery

Post-surgical orthodontics

• Post surgical should start within 4-8 weeks. detailing of

occlusion requiring 4-6 months

• GOALS: posterior cross bite correction, extrusion for leveling

and setting, detailing occlusion, root paralleling.

Virtual surgical planning• performed on a virtual model composed of

a three-dimensional (3D) scan of the maxillofacial skeleton and a 3D scan of the dental arch

• Standard CT with 1mm cut and dental model

• Super impositio n of Soft tissue profile• key anatomical land marks like ANS, Point A,B pog, were markedVirtual surgery starts by setting the maxillary position followed by mandible

• occlusal splints can be fabricated using CAD/CAM technique.

The two major soft- ware systems for 3D virtual planning are SimPlant &

Dolphin 3D

Virtual planning appears to be an accurate and reproducible method

for orthognathic treatment planning as difference of maximum 2 mm

Soft tissue changes• Nasal tip elevation-1mm for 6mm superior movement of U1

• Nasiolabial angle decreases 1-4 degree per 1mm advancement

• Low angle cases-maxillary superior reposition if 10 mm then forward auto

rotation -3mm

• High angle cases-maxillary superior reposition if 10 mm then forward auto

rotation -6.5mm

• The type of soft tissue manipulation employed, in particular the use of the alar

base cinch suture and V-Y closure techniques, were important factors in

determining the response of the upper lip to the surgery. The maxillary soft

tissues moved forward 90% of the hard tissue change and showed 20%

shortening of the upper lip, with the changes in the nasolabial angle British Journal of Oral and Maxillofacial Surgery Volume 30, Issue 5, October 1992,

• For the impaction group,(1) the upper lip closely followed the movement of the maxillary central incisor in the horizontal plane (2) the mandibular soft tissue followed the skeletal mandibular autorotation on an approximately 1:1 basis, (3) the lower border of the upper lip moved superiorly approximately 40 percent of the vertical maxillary change, and (4) there was a superior vertical change in all of the maxillary soft-tissue. • For the advancement group,(1) a progressive increase in the horizontal soft-tissue movement from the tip of the nose to the free end of the upper lip was observed and (2) vertical change in the soft-tissue and horizontal movement of the mandibular soft tissue was unpredictable

Surgery first approach• Recently popularized• To eliminate pre- operative orthodontic phase• Need proper case selection - only anterio-posterior discrepancy• The segment movement is based on lower lip and chin contour, height of

the lower facial region, and the consonance of the smile arc,• Duration of treatment upto 12 months

Hierarchy of stability

Head & Face Medicine 2007, 3:21

summary• Proper patient selection and treatment planning are necessary

• Radiographs are adjuvant to clinical diagnosis

• Priority has to be given for Patient expectations

• Basic therapeutic goals taken into consideration

• soft tissues are the limiting factors

• REFERENCES• Peterson’s principles of oral and maxillofacial surgery (volume 2)• Oral and maxillofacial surgery: raymond J Fonseca (volume 2: orthognathic surgery)• Text book of oral and maxillofacial surgery - Kruger• Essentials of orthognathic surgery: Johan P. Reyneke• Orthodontic cephalometry: Athanasiou • Dentofacial deformities-Epker Fish • A systematic review on soft-to-hard tissue ratios in orthognathic surgery part I: Maxillary

repositioning osteotomy JOURNAL OF CRANIOMAXILLOFACIAL SURGERY 2012.• Current Status of Surgical Planning for Orthognathic Surgery: Traditional Methods versus 3D

Surgical Planning Jeffrey A. Hammoudeh, MD, DDS, Lori K. Howell, MD, Shadi Boutros, MD, DDS, Michelle A. Scott, DDS, MS, and Mark M. Urata, MD, DDS Plast Reconstr Surg Glob Open. 2015 Feb; 3(2): e307

• Virtual planning in orthognathic surgery. Int. J. Oral Maxillofac. Surg. 2014; 43: 957–965.• Computer-aided planning in orthognathic surgery—systematic review. Int. J. Oral Maxillofac.

Surg. 2015; 44: 329–342• PLANNING OF ORTHOGNATHIC SURGERY – ‘A NEW ERA. Prof Dr K C Gupta , Dr Rajbir Kaur

Randhawa , Dr Rashi Yadav, Prof Dr S M Agrawal, Prof Dr P G Makhija, Dr Anurag Bhargav, Dr Madhur Navlani NJDSR,Vol.1, January, 2012

• Soft tissue changes associated with double jaw surgery Alan C. Jensen, DDS, MS, Peter M. Sinclair, DDS, MSD, Larry M. Wolford, DDS (AM J ORTHOD DENTOFAC 1992;101:266-75

• An evaluation of soft-tissue changes resulting from Le Fort I maxillary surgery Stephen Mansour, D.M.D., Charles Burstone, D.D.S., M.S, Harry Legan, D.D.S. American Journal of Orthodontics Volume 84, Issue 1, July 1983, Pages 37-47

• A three dimensional analysis of soft and hard tissue changes following bimaxillary orthognathic surgery in skeletal III patients A.M. McCance, FDSRCPS, MSc, MOrthRCS J.P. Moss, FDSRCS, PhD, MOrthRCS, W.R. Fright, PhD, D.R. James, FRCS, FDSRCS, A.D. Linney, PhD. British Journal of Oral and Maxillofacial Surgery Volume 30, Issue 5, October 1992, Pages 305-312

Thank you…