ORTHOGNATHIC SURGERY

DIAGNOSIS & TREATMENT PLANNING IN ORTHOGNATHIC SURGERYPRESENTED BY-NIKHIL SRIVASTAVAMODERATED BY-Dr. DEEPIKA KENKERE

ContentsIntroductionDevelopment of orthognathic surgeryTiming of treatmentEnvelope of discrepancyTreatment objectivesIndicationsContraindicationsSystematic Clinical Patient evaluationRadiographic evaluationVisualised Treatment ObjectiveModel surgeryPhases of orthognathic surgeryOrthognathic ProceduresConclusion

INTRODUCTION

ORTHOGNATHIC SURGERY is 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 deformity of the jaws and associated structures .

So briefly the surgical procedures undertaken to improve the facial profile and aesthetics which are primarily focused on the correction of disproportions of underlying jaws (Gnathos- Greek) and their alignment ( Orthos Greek) are collectively grouped as orthognathic surgery.

DEVELOPMENT OF ORTHOGNATHIC SURGERYHullihen in 1849 was the first to perform osteotomy on the mandible to treat deformity caused by a burn.Later Blair reported mandibular body osteotomy in 1906 and horizontal osteotomy of the ramus with external approach in 1907.The introduction of sagittal split ramus osteotomy in 1957, by HL Obwegeser marked the beginning of the modern era in orthognathic surgery. This technique was further modified by Dal Pont in 1961. In 1921 a German surgeon , Herman Wassmund, reported his initial attempt to correct a dentofacial deformity by maxillary osteotomy. Obwegeser later started to perform maxillary surgery and described Lefort 1 osteotomies in 1969. The Lefort 1 downfracture technique by Bell in 1975 allowed repositioning of maxilla in all 3 planes of space.

In 1969 Horowitz emphasized the importance of orthodontics in the field and integrated it with orthognathic surgery.By 1980s it was possible to reposition either or both jaws , move the chin in all three planes of space, and reposition dentoalveolar segments surgically as desired.In 1990s rigid internal fixation greatly improved patients comfort by making immobilization of jaws unnecessary.With the introduction of distraction osteogenesis in 1992 by McCarthy and its rapid development since then made possible for larger jaw movements and treatment at an earlier age.

MODE OF TREATMENTGrowth Modification

Orthodontic Camouflage

Orthognathic Surgery

ENVELOPE OF DISCREPANCYProffit and Ackerman have described the process that most clearly allows clarification of treatment goals.With the ideal position of upper and lower teeth shown by the origin of x and y axis the envelope of discrepancy shows the amount of change that could be produced by orthodontic tooth movement alone, orthodontic tooth movement combined with growth modification and orthognathic surgery.There is more potential to retract than procline teeth and more potential for extrusion than intrusion.

ENVELOPE OF DISCREPANCY

The inner circle, or envelope, represents the limitations of camouflage treatment involving only orthodontics;

The middle envelope illustrates the limits of combined orthodontic treatment and growth modification;

The outer envelope shows the limits of surgical correction.

10Envelope of discrepancy

10101564725515122

Envelope of discrepancy

101025645515212 35

TIMING OF SURGERYThere is a definitive sequence in which growth is completed in maxilla and mandible. Growth in width is completed first, then growth in length and finally growth in height.Transverse growth of jaws completes before adolescent growth spurt by 12 yrs, but as jaws grow in length they also tend to become slightly wider.Growth in length and height continues through puberty, growth in facial height continues after cessation in growth in length upto adulthood.Orthognathic surgery should be delayed until growth is completed in patients with excessive growth ,especially mandibular prognathism.In growth deficiencies surgery can be considered earlier but rarely before adolescent growth spurt.

TREATMENT OBJECTIVESThree treatment objectives are fundamental in orthognathic surgery:1.Function2.Esthetics3.Stability

These three objectives form the basis of goals in treating patients with dentofacial deformities and often go hand in hand.

INDICATIONSGenerally ,those deformities in patients which cannot be camouflaged by conventional orthodontic methods are candidates for orthognathic surgeries.Non growing patients under surgical envelope i.e. a positive overjet greater than 8mm, a negative overjet of 4mm or greater, transverse discrepancy greater than 3mm and vertical over 5mm are not orthodontically treatable.Orthognathic surgery is required for cleft palate patients who have small maxilla due to the growth inhibitory effects caused by the surgery of the lip and palate by scarring.

3.Jaw deformity due to the ankylosis of TMJ, unilateral or bilateral .4. Those who have severe post surgical traumatic jaw deformities due to malunited fractures.5. In patients with obstructive sleep apnea to enlarge the oral space and therefore prevent the tongue falling back during sleep.6. Facial asymmetry caused by unilateral condylar hyperplasia.7. Deformities in syndromic patients

CONTRAINDICATIONSMild to moderate discrepanciesGrowing childrenUncontrolled systemic conditionsPsychological state of the patientUncontrolled pathologic conditions

Systematic patient evaluation

1. ESSENTIAL PATIENT EVALUATIONS

2.ADJUNCTIVE EVALUATIONS.

GENERAL PATIENT EVALUATION:In this patients complete medical and dental history should be taken.Any medical conditions which may complicate general anesthesia or the surgical procedure should be evaluated.In dental history any periodontal or periapical conditions should be noted and managed.Also the orofacial functions such as speech, mastication , respiration etc. must be evaluated

SOCIOPSYCHOLOGIC EVALUATION:It is important to consider patients motives for treatment and to determine the patients expectations from treatment.There are mainly 2 causes for the patients dissatisfactionFailure of clinician to inform the patient clearly of realistic and probable treatment results( specially esthetic results)Overoptimistic expectations of the patient regarding the results of the treatment

Three important parameters which are to be checked before proceeding with clinical examination are:- Natural head position Centric relation Relaxed lip posture

Once after these 3 things are established one can go ahead with facial examination.

ESTHETIC FACIAL EVALUATION:Clinical assessment of face is the most valuable of all diagnostic procedures.Examination should be done with head in natural head position, lips relaxed and teeth in centric occlusion.

Facial evaluation should be done in:Frontal viewProfile view

FRONTAL ANALYSIS:It is important to assess facial form, transverse dimensions, facial symmetry & vertical relationship in the upper, middle and lower thirds of face and lips.

Facial form:Facial height to width proportion is 1.3:1 for females and 1.35:1 for males. Bigonial width 30% less than bizygomatic widthShort square facial types are often associated with a Class II deep bite , vertical maxillary deficiency .Long narrow face: Vertical maxillary excess ,anterior open bite, mandibular anteroposterior deficiency.

FACIAL TYPES

TRANSVERSE DIMENSIONS:Rule of fifths (Sarver)Face is divided into five equal parts from helix to helix of outer ear.

SymmetrySymmetry checked in relation to facial midline formed by glabella, nasal bridge, nasal tip, philtrum, dental midline and midpoint of chin.

Vertical relationshipDistance from trichion to glabella, glabella to subnasale and subnasale to menton should be even (1/3rd) Lower third can be divided into upper 1/3rd from Sn to stomium and lower 2/3rd from stomium to menton.

In middle third Evaluation of eyes- Scleral show indicates midface deficiency

Cheekbones- nasal base-lip contour line should be a smooth curveInterruption in maxillary area -maxillary AP deficiencyInterruption in lower region - Mandibular excess

Normal upper lip length 20 mm females, 22 males.Lower lip length 40mm females, 44 mm males.Lips evaluated in relaxed position and jaws moved apart until lips just part. Competency, symmetry and shape must be evaluated.Incisor exposure evaluated. Influenced by: Vertical ht of maxilla, lip length, maxillary incisor crown length, shape of cupids bowCant of occlusal plane evaluated relating to interpupillary plane especially in asymmetries.Gingival exposure estimated upto 2mm is normal Amount of surgical superior repositioning dictated by amount of tooth exposure, lip length, crown length and gender

PROFILE ANALYSIS:In profile the cheek contour, lips,, nose, nasolabial angle, chin, chin-throat area should be evaluated.

Lip position relates to underlying dental position such as maxillary protrusion - lack of lip support. Mentolabial sulcus deep in Class II pts whereas flattened in Class III pts.Surgical or orthodontic retraction of maxillary incisors should be avoided in large nasolabial angles. Normal 85-110 degThe chin shape and position must be considered especially while considering genioplasties.Presence of double chin, chin throat length and angle must be noted while considering mandibular setback and advancement procedures.. Chin throat angle normal is 110 deg.

The nasal projection measured horizontally from subnasale to nasal tip is normally 16 to20mm ,

. Nasal projection is an indicator of maxillary antero posterior position.

This length becomes particularly important when planning for anterior movement of maxilla.

Nasal projection

Orbital rim

The orbital rim is an antero-posterior indicator of maxillary position.

Deficient orbital rims may correlate positionally with a retruded maxillary position because the osseous structures are often deficient as groups ,rather than in isolation.

The Eye globe normally is positioned 2-4mm anterior to the orbital rim.

The surgical maxillary versus mandibular decision is influenced by the orbital rim position.

Deficient orbital rims dictates the need for maxillary advancement with all other parameters being normal..

Radiographic Evaluation

LATERAL CEPHALOMETRIC EVALUATION:Although clinical evaluation must be the primary diagnostic tool cephalometric analysis must be the primary tool in determining surgical treatment.

SOFT TISSUE ANALYSIS

Horizontal relations measured with reference to a true vertical line passing through subnasale.

LIP PROMINENCE

FACIAL CONTOUR ANGLE

SKELETAL ANALYSIS

Cephalometrics for Orthognathic surgery by Charles BurstoneCOGS has the following characteristics, which make it particularly adaptable for evaluation of surgical orthognathic problems: Chosen landmarks and measurements can be altered by surgical procedures. It includes all facial bones and a cranial base reference.Rectilinear measurements can be transferred to study cast for mock surgery. Standards & statistics are available for variations in age(5yrs-20yrs) and sex.It includes dental, skeletal and soft tissue variables. It can be computerised.

Baseline for comparison of most data is a horizontal plane (HP), a surrogate FH plane, 7 deg from SN plane.Most measurements are made from projections either parallel or perpendicular to HP.

MEASUREMENTFEMALESMALESCRANIAL BASEAr-Ptm (11 HP)32.1mm37.1mmPtm-N (11HP)50.9mm52.8mmHORIZONTALN-A-Pog ang2.63.9N-A (11 HP)-2 3.7mm0.0 3.7mmN-B (11 HP)-6.9 4.3mm-5.3 6.7mmN-Pg (11HP)-6.5 5.1mm-4.3 8.5mmVERTICALN-ANS (L HP)50 2.4mm54 3.2mmANS-Gn (L HP)61.3 3.3mm68.63.8mmPNS-N (L HP)50.6 2.2mm53.9 1.7mmMP-HP24.2 523 5.9U1-NF27.5 1.7mm30.5 2.1mmL1-MP40.8 1.8mm45 2.1mmU6-NF23 1.3mm26.2 2 mm

MAXILLA & MANDIBLEFEMALEMALEPNS-ANS (11HP)52.5 3.5mm57.5 2.5mmAr-Go (linear)46.8 2.5mm52 4.2mmGo-Pg (linear)74.3 5.8mm83.7 4.6mmB-Pg (11MP)7.2 1.9mm8.9 1.7mmAr-Go-Gn (angle)122 6.9119 6.5DENTALOP upper- HP (angle)7.1 2.56.1 5.1A-B (11 OP)0.40 2.5-1.1 2U1- NF (angle)112 5.3111 4.7L1- MP (angle)95.9 5.795.9 5.7

POSTEROANTERIOR CEPHALOMETRIC ANALYSIS:

Usually advised in patients with facial asymmetry1. Triangle analysis: Triangles are constructed to evaluate the symmetry of the maxilla, mandible and chin.

DEVELOPMENT OF VISUAL TREATMENT OBJECTIVES.Accurate and realistic visual treatment objectives are developed from the lat ceph tracing in combination with all data from systemic patient evaluation.Two types of VTO: the pretreatment objective & immediate presurgical prediction tracing.PRETREATMENT VTO :Used for overall treatment planning . Consists of:Orthodontic prediction tracing to illustrate desired presurgical tooth movements and resulting soft tissue changes.Surgical prediction tracing predicting surgical repositioning of jaws and soft tissue changes.

IMMEDIATE PRESURGICAL VTO:Prediction tracing few days before surgery plans the definitive surgical movements and soft tissue changes.Model surgeries are also performed at this stage

Uses of VTO:To assess accurately the profile esthetic results of proposed surgery and orthodontics.To evaluate treatment options.To determine desirability of adjunctive surgical procedures such as genioplasty.Help determine the sequencing of surgery and orthodontics.To help decide if extractions are necessary & which teeth to extract.To determine anchorage requirements.

ORTHODONTIC PREDICTION TRACINGCorrect planning of orthodontic tooth positioning before surgery and accurate execution of presurgical orthodontic plan will enhance surgical potential and esthetic results.The following steps are followed in prediction tracing of mandibular advancement.

Step 1: Original tracing in black .Draw ideal facial depth angle (Between line passing through N to pt A & FH plane: 90 deg)Draw ideal facial contour angle (between upper facial plane and lower facial plane: -11 to -15 deg)

Step 2: Prediction tracing done in red anterior to vertical osteotomy line and above horizontal osteotomy line .Repositioning of chin done. Teeth, lowerlip & chin traced in dotted line.

Assessment of occlusal plane and curve of spee

Step 3: Mandibular advancement along occlusal plane

Step 4: Trace remaining structures

Step 5: Placing teeth in ideal position

Step 6: Decision regarding tooth extractionStep 7: Establishment of molar relation and arch length post extraction.

Step 8: Soft tissue prediction and completion

MODEL SURGERYThe primary goal of the model surgery is to functionally and spatially simulate the patients jaw and dental structures as accurately as possible to allow accurate simulation of the interdental surgery.The preoperative structures can be measured and recorded. The surgical movement of the jaws or dentoalveolar segments as indicated by prediction tracings, is simulated on the cast and the specific spatial changes are then recorded.

The first step in defining the patients deformity in three planes of space is to place the dental casts on an anatomic articulator using facebow transfer in centric occlusion. Next the plaster is trimmed to simulate the maxilla and mandible as closely as possible.Reference lines are drawn on the mounted casts to record their positions in three planes of space.

MODEL SURGERY FOR MANDIBLEDraw a horizontal osteotomy line parallel to the mandibular occlusal plane.Draw vertical reference lines from the cusps of the molar, canine, and central incisors to the base of the cast.Measure the length of the vertical lines and record the data.Cut the mandibular cast on the horizontal osteotomy line.Advance the cast into more favorable dental occlusion.Measure anteroposterior vertical and rotational movements and compare them with the premovement data.

MODEL SURGERY FOR MAXILLADraw horizontal osteotomy line as close as possible to lefort I Draw 2 horizontal lines, one line 5mm above the osteotomy line and one line 5mm below it( 10mm total between lines) this is done because the lateral walls of the maxilla are not parallel and taper downword.Draw vertical lines from the buccal cusps of the teeth to the base of the cast.Measure the length of vertical lines and record the data.Cut the cast along the osteotomy line.

Perform anteroposterior cast repositioning a. advance the cast b. superior repositioning c. down fracture.

PHASES OF ORTHOGNATHIC SURGERYThe complete treatment protocol in orthognathic surgeries can be divided into 3 stages:Presurgical orthodonticsSurgical phase.Postsurgical orthodontics

Stage of treatment Time required Comments1. Presurgical orthodontics 9-18monthsInterval varies with difficulty of alignment2. Surgery /hospitalization1-5daysHospital stay typically requires 1 or 2 days. One jaw surgery now can done without overnight hospitalization3. Patient under surgeons care before beginning postsurgical orthodontics3-8 weeksLess time is required with rigid fixation (3 to 5 weeks) than with maxillomandibular fixation (5 to 8 weeks)4. Postsurgical orthodontics3-6 monthsInterval longer than 6 months indicates a problem or inadequate preparation

Time estimates for surgical orthodontic treatment

Procedures Effects Maxillary advancementWidens nasal baseHighlights Para nasal areasReduces nasal prominenceHighlights upper lipShades the chinMaxillary setbackRetracts Para nasal areasIncreases upper lip lengthDecreases interlabial gapLowers tip of the noseHighlights chin

Different orthognathic procedures and effects involved

Mandibular advancementIncreases height of the lower third Increases chin projectionReduces lower lip eversionIncreases lower lip protrusionMandibular setbackIncreases lower lip showReduces height of the lower thirdReduces chin prominenceReduces lower lip eversionReduces lower lip protrusionHighlights paranasal areas

DIAGNOSIS AND TREATMENT PLANNING

Data base (case history, patient examination, Radiographic and model analysis)

Problem list in priority order Diagnosis

Possible solution to the problem Tentative treatment plan.

Discussed with the patient & modified

Optimal treatment plan

Execution of treatment

MANDIBLE Ramus osteotomiesOblique subcondylar osteotomyThe vertical subsigmoid osteotomyThe sagittal split and its modificationsThe inverted L and C osteotomies of the ramusCondylectomyOsteotomies of the body of the mandible Segmental proceduresGenioplastiesMAXILLA 1. Lefort I2.lefort II3. lefort III 4. Segmental osteotomy

Surgical TechniquesBSSO

Genioplasty

Surgical TechniquesLe Fort ILe Fort IILe Fort III

Le Fort ILe Fort IILe Fort III

CONCLUSIONOrthognathic surgery has created vast and exciting opportunities in treatment with dentofacial deformities and has relieved the orthodontist of having only compromised treatment to offer patients with skeletal disharmony.A well-planned, systematic & synergestic approach from both specialities of orthodontics and surgery is required to provide the best successful treatment for such cases.

REFERENCES Essentials Of Orthognathic Surgery Johan P. ReynekeOrthodontics & Orthognathic Surgery : Diagnosis & Treatment Planning-Jorge GregoretMaxillofacial Surgery- Peter Ward BoothPetersons Principles of Oral and Maxillofacial Surgery

THANK YOU