these slight facial asymmetries are acceptable esthetically . however , significant asymmetry may cause functional as well as esthetic problems .
the etiology of facial asymmetry can be divided into three components : congenital , developmental and acquired.1,2 however etiology for certain cases remains unknown .
facial asymmetry may be present along with class i or class ii malocclusions , but it most commonly occurs in cases with class iii malocclusions.3,4 depending on the craniofacial structures involved , facial asymmetry can be classified into - skeletal , dental and functional .
dental factors mainly include early loss of deciduous tooth , congenital missing tooth or teeth , and certain habits .
patients having facial asymmetry are evaluated through clinical assessment , cephalography and more recently with the use of three - dimensional imaging techniques .
clinical examination includes a visual inspection of the entire face , palpation to differentiate between soft tissue and bony defects and comparison of dental midline with a facial midline .
in addition to the frontal aspect , viewing mandible from an inferior or submental vertex view sometimes helps to determine the extent of mandibular asymmetry in relation to the rest of the face .
the dental midline needs to be evaluated in different positions such as in centric relation , open mouth , at initial contact and in centric occlusion .
true skeletal and dental asymmetry will not show any change in the midline discrepancies in centric relation and in centric occlusion .
whereas , asymmetry due to occlusal interference may result in functional shift of the mandible on initial tooth contact . in most of the cases ,
clinical examination needs to be supplemented by other diagnostic aids such as - study models , face bow transfer and various imaging techniques to accurately localize the asymmetric structures .
interpretation of lateral cephalogram in diagnosing asymmetries is of limited value.5,6 panoramic view provides information regarding gross anomalies , supernumerary or missing teeth .
any variations in the shape and height of mandibular ramus and condyles on both sides can be assessed and compared.7 however , the cephalometric postero - anterior projection provides valuable information and helps in proper diagnosis .
it can be obtained at centric occlusion and open mouth positions to determine the extent of functional mandibular deviation .
more recently the newer imaging techniques like three - dimensional computed tomography and three - dimensional photography are being used to accurately localize the discrepancy .
a detailed study of various diagnostic records obtained on the patient is necessary to determine the cause , extent and location of asymmetry .
a 17-year - old female patient reported for orthodontic treatment with a chief complaint of irregular teeth and an unesthetic smile .
intraoral findings showed class ii subdivision right malocclusion with severe crowding of upper and lower anteriors , anterior cross bite in relation to upper laterals and lower canines and a lower midline deviation of 3 mm to right ( figure 1 ) .
pre - treatment photographs . all the routine essential diagnostic records , which include extraoral radiographs ( figure 2 ) lateral cephalogram ( figure 2a ) , orthopantomogram ( figure 2b ) , photographs and study models were advised . face bow transfer ( figure 3 ) was recorded on the patient ( figure 3a ) and transferred on to the articulator ( figure 3b ) , to evaluate the midline shift .
in addition to these , two cephalographs with postero - anterior ( pa ) view ( figure 4 ) in centric occlusion ( figure 4a ) and open mouth position ( figure 4b ) were advised to differentiate between skeletal and dental asymmetry .
panoramic radiograph showed that condyle of the left side was slightly larger than the right side , suggesting mild hyperplasia of the left condyle .
the lateral cephalometric tracing showed a good anteroposterior skeletal relationship with a vertical growth pattern .
face bow transfer indicated presence of skeletal midline shift , which was confirmed with the radiographic analysis of pa view cephalograms ( figure 5 ) in occlusion ( figure 5a ) and in open mouth position ( figure 5b ) .
( a ) in occlusion ( b ) open mouth position . after assessing patients perception of her facial asymmetry and expectations of treatment results , advisability of surgical correction was not considered .
alignment and leveling of teeth were carried out using pre - adjusted edgewise appliance following extraction of maxillary first premolars and mandibular second premolars .
significant improvement was observed in the patient 's dental esthetics including alignment of upper and lower anteriors , achievement of ideal overjet and over bite and angle 's class i molar relation ( figure 6 ) .
the cephalometric evaluation of skeletal and dental changes pre- and post - orthodontic treatment are summarized in table 1 .
panoramic radiograph showed that condyle of the left side was slightly larger than the right side , suggesting mild hyperplasia of the left condyle .
the lateral cephalometric tracing showed a good anteroposterior skeletal relationship with a vertical growth pattern .
face bow transfer indicated presence of skeletal midline shift , which was confirmed with the radiographic analysis of pa view cephalograms ( figure 5 ) in occlusion ( figure 5a ) and in open mouth position ( figure 5b ) .
radiographic analysis of pa view cephalographs . ( a ) in occlusion ( b ) open mouth position . after assessing patients perception of her facial asymmetry and expectations of treatment results , advisability of surgical correction was not considered .
alignment and leveling of teeth were carried out using pre - adjusted edgewise appliance following extraction of maxillary first premolars and mandibular second premolars .
significant improvement was observed in the patient 's dental esthetics including alignment of upper and lower anteriors , achievement of ideal overjet and over bite and angle 's class i molar relation ( figure 6 ) .
the cephalometric evaluation of skeletal and dental changes pre- and post - orthodontic treatment are summarized in table 1 .
when patients complain of facial asymmetry and seek treatment , it is first essential to determine the underlying causes .
this entails a thorough case history , radiographic analysis , facebow transfer and imaging studies.8,9 true dental asymmetry can be managed by orthodontic treatment alone using asymmetric extraction mechanics and by use of combination of intraoral elastics . for pronounced tooth irregularities , composite buildups or prosthodontic restorations may be indicated .
more severe discrepancies may need orthodontic alignment of teeth to achieve proper occlusion and function .
occlusal splints help in evaluating the presence and extent of functional shift by eliminating habitual posturing and deprogramming of musculature . in cases with contracted maxillary arches leading to shifting of mandible
, rapid maxillary expansion may be indicated to achieve proper intercuspation of posterior teeth in centric relation.10 severe skeletal asymmetries require a combination of orthodontic and surgical management .
surgical treatment planning may include orthognathic facial bone contouring surgery , genioplasty and contouring of soft tissues such as the masseter muscle and buccal fat pads.11,12 the extent of soft tissue changes as a result of related skeletal structure mobilization may be difficult to predict accurately.13 if later a second operation is required for adjustment of symmetry , alloplastic implants and fat injections for volume augmentation , as well as bone contouring and liposuction for volume reduction , can be carried out.14 more recent advances in three - dimensional photography have provided a valuable tool in diagnosis and treatment planning of dentofacial asymmetries with their proven accuracy and precision.15,16 however , decisions regarding intervention of dentofacial deformities depend upon the patient 's awareness of the esthetic problem , the extent of occlusal deformity and concomitant sagittal or vertical jaw imbalance.17
a systematic and comprehensive examination , diagnosis and treatment plan is requirements for successful management of dentofacial asymmetries .
contributions from soft tissue , dental and skeletal elements leading to facial asymmetry should be evaluated in detail for arriving at an accurate diagnosis .
patient complaints and desires should be addressed carefully before finalizing the treatment plan since they may vary from unrealistic expectations to a total lack of concern even in the presence of severe discrepancies . in the presence of less severe skeletal , dental and soft tissue deviations , intervention with treatment procedures
 dentofacial asymmetry is quite common and when sufficiently severe can require surgical orthodontic intervention . 
 asymmetries can be classified according to the structures involved into skeletal , dental and functional . in diagnosing asymmetries , 
 a thorough clinical examination and radiographic survey are essential to determine the extent of soft tissue , skeletal , dental and functional involvement . 
 dental asymmetries , as well as a variety of functional deviations , can be managed orthodontically , whereas significant structural facial asymmetries require a comprehensive orthodontic and orthognathic management . with less severe dental , skeletal and soft tissue deviations the advisability of treatment 
 should be carefully considered . 
 the following article also contains a case report highlighting the importance of proper diagnosis in treatment plan for management of dentofacial asymmetry . 