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10.2 Major surgical procedures

1. Introduction

Our understanding of the concepts of craniofacial growth is continually

evolving andd the application of this knowledge to clinical practice particularly tothe surgical field is also enormously increasing. The surgeons now a days areable to correct the various orofacial abnormalities that have resulted fromarrested and perverted development of cranio facial complex.

Major surgical procedures that are undertaken concurrent with orthodontictherapy are

1. Orthognathic surgeries which deals with surgical correction of jaws.

2. Facial esthetic/cosmetic surgeries like rhinoplasty, blepharoplasty etc..,

3. facial reconstruction surgeries like cleft palate and lip repair surgeriesetc..,

The aim of this chapter is to provide a basic view of the principles oforthognathic surgery. Orthognathic surgery is the surgical correction ofunderlying skeletal anomalies or malformations involving the mandible or themaxilla.. Modification of a severe skeletal discrepancy in adults is not possible byredirection of growth as growth potential is culminated. They cannot be effectivelymasked by camouflage. In such adult patients surgical correction may beindicated. Orthognathic surgeries are major surgical procedures carried out along

with orthodontic therapy to correct dentofacial deformities or severe orofacialdisproportions involving the maxilla! the mandible or both in combination. "urgeryis not a substitute for orthodontics in these patients. Instead! it must be properlycoordinated with orthodontics and other dental treatment to achieve good overallresults. This orthognathic surgeries are combined surgical orthodonticprocedures which involve the team work of orthodontist! an maxillofacial surgeonand some times plastic surgeon.

The team! led by the orthodontist and the oral surgeon! carefully develops aproblem list! which is reviewed with the patient. The desired outcome of theideal treatment plan of orthodontic treatment and jaw surgery is to achieve

stability! function! and facial balance.

Malformations of the jaws or skeletal aberration may be present at birth#congenital$! or they may become evident as the patient grows and develops#ac%uired$. They can cause esthetic disharmony! structural and functionaldeficiencies and defects. These include disfigurement of face ! masticatoryproblems! abnormal speech patterns! breathing problems! early loss of teeth and

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dysfunction of the temporomandibular joint. The objective of orthognathic surgeryis to restore the esthetic harmony! functional efficieny and structural balance .

&. Principle of Orthognathic surgeryOrthognathic surgery basically involves planned intentional fracturing or

sectioning of the facial skeletal parts and repositioning them as desired inacceptable functional position. Orthognathic surgeries can be performed in themaxilla as well as the mandible or both the jaws to correct jaw discrepancies inall the three planes of space. They can be done at the level of basal bone itselfor limited to alveolar bone. They should be performed as a team with the oralsurgeon and the orthodontist being important members of the team.

3. Indications of orthognathic surgery

1. "keletal discrepancy' "ignificant (lass II or III skeletal patterns

&. )acial imbalances or asymmetries' *ong lower face! gummy smile etc..!

+. *imitations of tooth movements ' ,eed to keep teeth relatively upright andin the bone

-. elapse potential of orthodontic treatment' /xcessive dental extrusion#vertical elastics$! expansion or tipping or teeth may not be stable

4 .Steps in orthognathic surgery

The planning and execution of orthognathic surgeries are done in amethodical manner. The following are the steps involved in Orthognathicsurgery0

i. (linical diagnosis and evaluationii. interdisciplinary approach and pre orthodontic dental careiii. resurgical orthodonticsiv. "urgical treatment objective # "TO$v. Mock surgery

vi. "urgery and stabili2ationvii. ostsurgical orthodontics and occlusal detailing.viii. retention

i. Clinical diagnosis and preoperatie ealuation

reoperative diagnosis is very important for the success of orthognathic surgery.

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The diagnosis is aimed at determining the nature! position! severity and thepossible etiology of the dentofacial deformity. The extent of the malocclusion inall the three planes is thouroughly evaluated.

a. !eneral "edical ealuation0 The patient3s general medical history should

be recorded to rule out any systemic condition that may compromise the surgicalprocedure.

b. #ental ealuation0 The patient3s overall dental health should be evaluated.articular attention is paid towards the muscles of mastication andTemperomandibular joint. ulpo periodontal problems should be controlledprior to the surgical intervention.

b. Socio $ psychological ealuation 0 The patients is to be assessed todetermine whether he 4she is aware of the dentofacial deformity and expectationfrom treatment outcome. This helps in determining the patient5s motivation

towards surgery

c. Cephalo"etric ealuation0 (ephalometric evaluation is an important andobligatory tool in locating the nature and severity of the skeletal problems and inselecting the favourable sites for surgical correction. (ephalometric analysesoften have been used as the cornerstone in the differential diagnostic process forskeletal imbalances. The lateral cephalogram and anteroposterior cephalogramare evaluated. The commonly used (ephalometric analysis are the 6urstoneanalyses and the 7uadrilateral analysis. )rontal cephalometric analysis helps indetermining facial asymmetry.(ephalometric analyses using a 8acobson or 6roadbent 6olton template method

and the Moorrees mesh are able to graphically %ualify #demonstrate which jaw isnot in balance$ and %uantify #demonstrate the degree to which each jaw! bothdental and skeletal component! contribute to the imbalance$. The templateproved to be a simple! %uick! and reliable tool to demonstrate the direction andapproximate amount of surgery needed to correct the skeletal disharmony

Indications for surgery include the problems that are too severe for orthodonticsalone. The amount and range of movement possible can be evaluated from/pker3s envelope of of discrepancies. The envelope of discrepancy outlines thelimits of hard tissue change toward ideal occlusion . The limits vary both by thetooth movement that would be needed #teeth can be moved further in somedirections than others$ and by the patient5s age . 9rowth potential in childrenhelps to treat conditions by orthodontics alone # 1:mm of overjet$ but the samehas to be treated by surgical means in adults..d. %adiographic e&a"ination 0 ; complete radiographic survey of themaxillofacial region is necessary prior to the surgical intervention .

Intraoral periapical radiographs 0 These radiographs help in determining the

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condition of the teeth and alveolar bone. resence of pathology around the toothcan also be determined using these radiographs. ;ny pulpal or periodontalinfections should be eradicated before surgery

anaromic radiographs 0 Orthopantomogram or O9 offers a wide range view of

the entire dentofacial region. It gives us the periapical and periodontal status ofthe dentition. ;ny impacted4embedded or ectopic teeth! which may come in theline of the osteotomy should be preferably extracted < months prior to surgery.These radiographs are also useful in evaluation of maxillary sinuses !temperomandibular joint. and other bony pathologies in maxillo mandibularregion. anoramic view points out to the asymmetry of the face also

"ubmentovertex view 0 This view is used to determine the buccolingualthickness of the mandible as well as degree of deformity of the face. It is alsouseful is assessing the condition of condyles.

=and wrist '>rays 0 They are useful for growth assessment and to determineskeletal age or maturity. Orthogntahic surgeries are indicated after active growthperiod or after attaining skeletal maturity.

e. Photographs0 reoperative photographs are necessary in order to have arecord of pretreatment profile. 6oth the extraoral facial photographs and theintraoral photographs are taken. )rontal and lateral facial photographs areusually taken in a natural head position. Morphometric measurements can alsobe done on these photographs

g. 'aluation of "asticatory syste"0 The temperomandibular joint is evaluatedby inspection! palpation! auscultation and by radiographic examination toevaluate joint movements and an pathology. Muscles of mastication areinspected and palpated to evaluate the force of contraction and any underlyingpathology.

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'p(er enelope of discrepancy ) fig 1*The maximum amount of movements possible by three different means of treatment is given by 'p(er enelope ofdiscrepancies. It has three envelops. The perimeter of each envelope gives the maximum range of movements possibleby different methods of treatment.

Inner envelopeonly orthodontic treatmentMiddle envelope orthodontic and growth modification

Outermost envelope?orthognathic surgery

+a,le sho-ing the a"ount of "oe"ent possi,le at incisor region ,y different "ethods ) anterioposterior andertical direction*. %efer figure. 'p(er enelope of discrepancies / and

;mount of retractionpossible

;mount ofprotractionpossible

;mount ofbite opening# intrusion$possible

;mount of biteclosing# extrusion$possible

Ma&illary Mandi,le Ma&. Mand Ma& Mand Ma& Mand

Only OrthodonticTreatment @ mm

+ mm & mm Amm&mm -mm -mm & mm

Orthodontic tooth

movement combinedgrowth modification

1& mm A mm A mm 1:mm A mm < mm < mm A mm

Orthognathic surgery 1A mm &A mm 1: mm 1&mm 1Amm 1:mm 1: mm 1A mm

ossibility of each type of treatment is not symmetric with respect to plane of space. )or example toothmovement by orthodontic means alone is more possible anterioposteriorly than vertical direction.9rowth modification is more effective in mandibular deficiency#1:mm$ than mandibular excess# Amm$

# 1$ There is more potential to retract than protract the teeth

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#&$ There is more potential for extrusion #correction of open bite$ then intrusion #correction of deep bite$ #+$ since growth of the maxilla cannot be modified independently of the mandible! the growth modificationenvelope for the two jaws is same. #-$ surgery to move the jaws back has more potential than to advance the mandible

+a,le sho-ing the a"ount of "oe"ent possi,le at posterior region ,y different "ethods ) transerse andertical direction*. %efer figure. 'p(er enelope of discrepancies /c and #

;mount of expansionpossible on each side

;mount ofcontractionpossible on eachside

;mount ofintrusionpossible

;mount ofextrusionpossible

Ma&illary Mandi,le Ma&. Mand Ma& Mand Ma& Mand

Only OrthodonticTreatment + mm

&mm

& mm 1 mm&mm -mm +mm + mm

Orthodontic toothmovement combinedgrowth modification

- mm -mm + mm & mm + mm < mm - mm A mm

Orthognathic surgery @ mm Amm - mm + mm 1:mm 1:mm 1: mm 1: mm

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2.pre orthodontic dental care

;ny indicated periodontal or general dental care related to maintaining teeth orimproving dental health should be performed prior to orthodontics and surgical

intervention. The objective is to maintain as many teeth as possible and stabili2ethe periodontium. estorative work has to be completed in indicated cases.

3. Pre surgical orthodontics

The aim of the resurgical orthodontics is to position the teeth to the mostdesirable position over basal bone in preparation for intended surgery. Buringthis presurgical orthodontic phase occlusal detailing is not done. This presurgical orthodontic fixed appliance will remain in place during surgery andprovide fixation during healing. referabbly the fixed appliance should be

edgewise or straightwire appliance. ;fter surgical fixation is released! anothershorter period #- to < months$ of orthodontics is indicated to detail the occlusionbefore retainers are fitted.

The following procedures are undertaken as part of pre surgical orthodontics.

1. Tooth alignment within the arches 0 "pacing !rotations and crowding are to beeliminated during the presurgical orthodontic treatment. )ixedappliances are preferred as they offer better control and it is possible toalign several teeth. "pace may be needed for these maneuvers whichcan be gained by interdental stripping or even extractions. /xtractions

during presurgical orthodontics is generally undertaken to relievemoderate to severe crowding within the dental arches and toaccommodate segmental bone cuts. If space calculations permit to alignthe arch it is better to avoid extractions at this stage./xtractions can bedone at the time of surgery.

2. Inter arch coordination 0 ;ny cross bites whether locali2ed or segmentalshould be corrected at this phase. (rossbites with narrow maxillary archre%uire some form of arch expanision procedures. ;s a general ruleorthodontic expansion or contraction to coordinate the upper and thelower arches should be carried out prior to the surgery so as to providecorrect post operative occlusal interdigitation.

3. Incisor inclinations and Becompensation 0 Most of the severe skeletal jawdiscrepancies are partly compensated by change in axial inclination of theanterior teeth in opposite direction. )or example in class II skeletalcondtions the upper anteriors retrocline to compensate for maxillaryprognathism and lower incisors procline to compensate for mandibularretrognathism. This is called as natural compensation. In mild skeletal

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cases this compensation is further enhanced by comouflage by selectiveextraction of certain teeth which is described in earlier chapters. Incontrast to dental camouflage! in preparation for orthognathic surgery! it isnecessary to remove any dental compensations present and to place theteeth in a favorable position with their supporting bone. This is called as

presurgical deco"pensation. This usually means that the plannedmovement of the teeth before surgery must be in the opposite directionfrom the movement with dental camouflage treatment # fig &$

.

)or example in (lass II skeletal malocclusions associated with mandibularretrognathism! there is natural dental compensation in the form of proclined loweranteriors to partially offset or mask the skeletal discrepancy. In such casesdecompensation is typified by maxillary anterior teeth proclination andmandibular anterior teeth retroclination.

In (lass lll patients with prognathic mandible dental compensation is exhibited inthe form of lingually tipped lower incisors and proclined upper central incisors . Insuch cases decompensation is typified by retroclination of maxillary anteriorsand proclination of mandibular anteriors.

In other words after presurgical decompensation the condition appears to be stillworse. This should be explained to the patient as the condition is temporary andgets corrected after surgery.

4. +he surgical treat"ent o,jectie )S+O *

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The postsurgical profile of the patient can be predicted with some degree ofaccuracy by cephalometric means. This is called as Csurgical treat"ento,jectie )S+O* or Cprediction tracingD. It is a twodimensional visualprojection of the changes in osseous! dental! and soft tissues as a result of

orthodontics and orthognathic surgical correction of the dentofacial and occlusaldeformity. The purpose of the "TO is threefold0 #1$ establish presurgicalorthodontic goals! #&$ develop an accurate surgical objective that will achieve thebest functional and esthetic result! and #+$ create a facial profile objective whichcan be used as a visual aid in consultation with the patient and family members

/ssentially! after knowing the location and severity of deformityE the osteotomyand the extent of movement of the osteotomi2ed segment is determined. On anacetate tracing of the cephalogram! the osteotomi2ed segment is cut out andmoved as calculated. The soft tissue follow the movement of bone in a ratio

determined by the type of movement and the techni%ue performed. These tissuechanges are marked on the tracing to give the postoperative profile. =owever!these soft tissue changes are only meant to be a guide for prediction tracingsand are variable.

5. Moc( surgery 0 Fsing prediction tracings as a guide a surgical plan isformulated and then the surgery is simulated on articulated working models Themodels are cut and repositioned in the desirable position and the segmentssecured in their new position with sticky wax. The mock surgery thus helps in

evaluation of treatment outcome and any possible modifications re%uired in thesurgical treatment plan are noted. The acrylic occlusal splints are constructed innew occlusal position which are of immense help post surgically.

6. Surgery and sta,ili5ation) fig 3*

The next step involves the intentional or surgical fracturing and repositioning ofthe bony segments. Immobili2ation of bone fracture sites is a necessity forproper healing of the bone. The upper and lower arch are stabili2ed with the helpof the existing fixed appliance. Intermaxillary fixation usually spans for

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7. Post $ surgical orthodontics

Buring this phase! the final detailing of the occlusion and esthetic root parallelingis carried out. Most cases of postsurgical orthodontics are completed by -