ETIOLOGY AND DIAGNOSIS OF FACIAL ASYMMETRY

SEMINAR

1. ETIOLOGY & DIAGNOSIS OF FACIAL ASYMMETRY DR SHEHNAZ JAHANGIR II ND YEAR MDS DEPT. OF ORTHODONTICS & DENTOFACIAL ORTHOPAEDICS

2. CONTENTS INTRODUCTION DEFINITIONS PREVALENCE ETIOLOGY DEVELOPMENT OF ASYMMETRY CLASSIFICATION OF ASYMMETRY LITERATURE REVIEWS

3. DIAGNOSIS PATIENT EVALUATION CLINICAL EXAMINATION RADIOLOGICAL EXAMINATION VARIOUS ANALYSIS ADJUNCTIVE EVALUATION TMJ IMAGING PHOTOGRAPHIC ASSESSMENT DENTAL CAST ASSESSMENT CONCLUSION

4. INTRODUCTION No human Face – symmetric Goal of orthodontic treatment - create a balanced and harmonious facial proportion

5. DEFINITIONS Symmetry: “Equality or correspondence in the form of parts distributed around a centre or an axis, at the two extremes or poles, or on the two opposite sides of the body.” (Steadman’s Medical dictionary) Clinically, symmetry means balance, where as asymmetry means imbalance. Bishra SE, Burky PS, Kharaouf JG Dental and facial asymmetries: A review. Angle Orthod 1994;64(2):89-98

6. Dorland’s medical dictionary defines symmetry as “the similar arrangement in form and relationship of parts around a common axis on each side of a plane of the body”. And asymmetry as “ dissimilarity in corresponding parts or organ on opposite sides of the body which are normally alike”. Clinically asymmetry means imbalance.

7. In most individuals the right side of the face is slightly larger than the left ,and usually there is some asymmetry in facial examination. In persons with asymmetry, the lower face is affected much more frequently than the middle or upper thirds.

8. Facial Asymmetry – “Imbalances that occur between homologous parts of the face affecting the proportion of these parts to one another with regard to size, form, and position on opposite sides of a plane, line or point.” The division of normal from the abnormal – clinician’s sense of balance and patient’s perception of imbalance Bishra SE, Burky PS, Kharaouf JG Dental and facial asymmetries: A review. Angle Orthod 1994;64(2):89-98 Introduction

9. Right & left facial asymmetries Tooth size Cleft lip Cleft lip Cheong YW, Lo LJ. Facial Asymmetry: Etiology, Evaluation, and Management. Chang Gung Med J 2011;34:341-51

10. Asymmetry of the upper face- 5%, Middle third -36% Lower third /deviation of the chin-75%

11. Prevalence of asymmetry Among orthodontic patients Mandibular midline deviation 62% Maxillary midline deviation 39% Molar classification asymmetry 22% Maxillary occlusal asymmetry 20% Mandibular occlusal asymmetry 18% Facial asymmetry 6% Chin deviation 4% Nose deviation 3% Bishra SE, Burky PS, Kharaouf JG Dental and facial asymmetries: A review. Angle Orthod 1994;64(2):89-98

12. THE POTENTIAL ETIOLOGIES OF FACIAL ASYMMETRY

13. GENETIC A. Hemifacial facial microsomia . B. Uniteral cleft lip and palate C. Multiple neuro fibromatosis . INTRA-UTERINE PRESSURE during pregnancy and significant pressure in the birth canal during parturition can have observable effects on the bones of the fetal skull. Molding of the parietal and facial bones from these pressures can result in facial asymmetry. These effects are generally transient with rapid restoration of the normal relationships of the skull within a few weeks to several month

14. ENVIRONMENTAL FACTORS a.sucking habits b.asymmetrical chewing habits caused by dental caries, extractions, and trauma. FUNCTIONAL DEVIATION. Due to any premature contact. .

15. LOCALISED PATHOLOGY a.Osteochondroma of the mandibular condyle b.condylar hyoplasia,hyperplasia c.irradiation d.lymphangioma e.fibrous dysplasia etc.

16. TRAUMA OF THE HARD AND SOFT TISSUES. Untreated fracture of condyle INFECTION AND INFLAMMATORY CONDITION OF TMJ AND OTHER BONY STRUCTURE Trauma and infection within the temporomandibular joint could result in ankylosis of the condyle to the temporal bone that leads to unilateral mandibular underdevelopment on the affected side and damage to a nerve may indirectly lead to asymmetry from the loss of muscle function and tone.

17. MUSCLE DYSFUNCTION Affect the jaw growth in two ways 1.Formation of bone at the point of muscle attachment depends on the activity of the muscle 2.the musculature is an important part of the total soft tissue matrix , whose growth carries the jaws downwards and forwards

18. DEVELOPMENT OF ASYMMETRIES

19. Syndromes with severe facial asymmetries: Hemifacial microsomia Retinoic acid syndrome clefting syndrome craniosynostosis Thalidomide tetrology SEMINARS IN ORTHOD 1998;4 ;

20. 1. Many of these aymmetries appear to be related to abnormalities occuring early during embryonic development. Change in the number or migration pathway of neural crest cells. Premature fusion of craniofacial sutures 20 SEMINARS IN ORTHOD 1998;4;

21. Specific mutations have been identified in muscle segment homeobox ( Msx ) and Fibroblast growth factor-receptor genes . Mutation in SONIC HEDGEHOG leads to HOLOPROSENCEPHALY SEMINARS IN ORTHOD 1998;4 ;

22. 2. Asymmetric skeletal development of individual craniofacial structures. Asymmetric development within the cranial base can lead to asymmetries in the positions of the glenoid fossa . SEMINARS IN ORTHOD 1998;4;

23. A fossa that is in a more anterior position relative to the contralateral fossa may produce a rotation of the mandible relative to the maxilla and an asymmetric occlusion, even if the maxilla and the mandible are not significantly asymmetric in form. . SEMINARS IN ORTHOD 1998;4;

24. This could lead to a Class III relationship on the side of the more forward positioned fossa and condyle and a Class II relationship on the contralateral side SEMINARS IN ORTHOD 1998;4;

25. Rotations of the maxilla relative to the cranial base can also produce an asymmetric occlusal relationship, even when the glenoid fossae are symmetrically positioned. SEMINARS IN ORTHOD 1998;4;

26. Differences in the number or differentiation of precursor cells within a primordial facial structure is responsible for such facial deformities. SEMINARS IN ORTHOD 1998;4 ;

27. Mandibular asymmetries may be related not only to asymmetric positioning, but also to asymmetric morphologyof the mandible. Differences in the length of the body of the mandible, as well as differences in the height of the developing ramus , can lead to asymmetries.

28. Classifications

29. Am J Orthodontics 1961 Lundstrom ASYMMETRIES QUANTITATIVE NO. OF TEETH CLEFT PALATE QUALITATIVE 1.SIZE OF TEETH 2.LOCATION OF TEETH IN DENTAL ARCHES 3. LOCATION OF DENTAL ARCHES IN HEAD

30. Plint and Ellisdon Apparent True Skeletal AP disproportion Skeletal transverse discrepancies Maxillary narrowness with atypical soft tissue behavior- thumb sucking Local factors- teeth in crossbite

31. Henderson Morphological classification Lower facial enlargement Lower facial deficiencies Mid third asymmetries Upper facial asymmetries Facial clefts

32. Lower facial enlargement Unilateral Condylar hyperplasia New growth Asymm . Masseteric hypertrophy Hemimand . hypertrophy

33. Lower facial deficiencies Mand . Hypoplasia congenital acquired Hemifacial hypoplasia

34. Mid third asymmetries Cleft Localized maxillary pathology Secondary maxillary asymmetries Parry romberg synd. Hemifacial hypoplasia

35. Upper facial asymmetry Cranial asymmetry Acquired cranial asymmetry Orbital dystopia

36. Angle orthod 1994;64;89 , Bishara Kharouf Structural classification of dentofacial asymmetries Dental Skeletal Muscular Functional

37. A. Dental Asymmetries : can be due to Local factors Early loss of deciduous teeth or permanent teeth. Ankylosis of primary molars Ectopic eruption congenitally missing teeth(retained primary), supernumerary teeth. caries habits size of teeth Shape of arches

38. B. Skeletal Asymmetries : Their deviation may involve one bone such as maxilla or mandible or it may involve a no. of skeletal and muscular structures on one side of the face.

39. C) Muscular Asymmetries : Hemifacial atrophy cerebral palsy, abnormal muscle function TORTICOLLIS: Excessive tonic contraction of the muscles such as sternocleidomastoid, leads to the facial asymmetry because of the growth restriction on the affected side.

40. D) Functional Asymmetry: can result from the mandible being deflected laterally or antero - posteriorly, if occlusal interferences prevent proper intercuspation in centric relation b y malposed tooth or constricted maxillary arch, TMJ derangements (ant. displaced disc without reduction)

41. A computer – based assessment of structural and displacement asymmetries of the mandible Schmid , Morgini , Felisio Am J Of Orthod Dentofac Orthop 1991 In the growing patient, craniomandibular asymmetry with transverse deviation of the mandible and the chin, with no genetic or congenital origin and without a history of trauma, infection, or tumor , is possibly the result of mandibular displacement consequent to occlusal alterations. If the mandibular displacement is not detected and treated in a timely manner, adaptive mandibular asymmetry may develop. Depending on the elapsed time between the onset of mandibular displacement and the examination, the patient can show displacement asymmetry, structural asymmetry, or a combination of both. The last possibility may be the most frequent in a population of growing patients.

42. Successful treatment during the growing period is possible in some patients. If the subject remains untreated, asymmetry can become a permanent feature in the adult. However, mandibular displacement may not be all or even part of the cause of a craniomandibular dysfunction. In such cases any kind of orthopedic treatment may be completely or partially ineffective. Because the symmetry in one of the control subjects improved in the absence of intervention, other factors besides treatment may be responsible for the different degrees of symmetry improvement in the treated patients.

43. Associations of mandibular and facial asymmetries – a review Pirttiniemi Am J Of Orthod and Dentof Orthopedics 1994;106:191-200 Acc to time of onset of asymmetric development

44. Dimitroulis Acc to causes of asymmetry Aberrant condylar growth Aberrant mandibular growth Hemifacial atrophy Hemifacial hypertrophy Hemifacial microsomia Traumatic deformities Neoplastic diseases

45. CLASSIFICATION ACCORDING TO THE INVOLVEMENT OF FACIAL PLANE SAGITTAL ASYMMETRY TRANSVERSE ASYMMETRY Class II DFD Class III DFD VERTICAL ASYMMETRY

46. The terms LATEROGNATHY and LATEROCULATION should be differentiated LATEROGNATHY LATEROCLUSION Center of mandible not aligned with facial midline at rest and in occlusion True crossbite True anatomical asymmetry Prognosis unfavourable Skeletal midline shift of mandible only in occluion . In postural rest both midlines well aligned Functional non - true malocclusion.

47. Literature review

48. Bercu Ficher in 1954 suggested that facial asymmetries are very often present with dental asymmetries and are clinical importance in the treatment of malocclusion of teeth .

49. Edward A. Cheney in 1961 described four types of dentofacial asymmetries, which requires special considerations in the management of malocclusion. These were (a) unilateral anteroposterior displacement. (b) Vertical displacement . (c) Lateral displacement and (d) rotary displacement.

50. Shah and joshi in 1978 said the total facial structures were bigger on right side in pleasing symmetrical faces. Some as Vig and Hewitt in 1974 state that left side of face is larger.

51. The Angle Orthodontist: Vol. 70, No. 1, pp. 81–88. Trpkova B. et al 2000 They found that females with bilateral TMJ internal derangement have greater vertical mandibular asymmetry than do females with unilateral TMJ internal derangement or females with normal TMJs.

52. DIAGNOSIS

53. ESSENTIAL PATIENT EVALUATIONS FOR FACIAL ASYMMETRY A General patient evaluation 1. Medical History 2. Dental evaluation a Dental history b Dental health B Social- psychologic evaluation C Esthetic facial evaluation   a Photograph for facial evaluation d.Duration of asymmetry    b Front-face analysis e.Level of asymmetry    c Profile analysis D Cephalometric evaluation 1.    Soft tissue 2.    Skeletal relations 3.    Dental relations  E Panoramic or full-mouth periapical evaluations     

54. F Occlusal evaluation A Functional B Static 1. inter arch 2 .intra arch 3. tooth mass G . Masticatory muscle and temporomandibular joint evaluation   1.   Masticatory muscle   2. Mandibular movements   3  Temporomandibular joint symptoms 4.Temporomandibular joint signs

55. Clinical examination When asymmetry first noticed ( congenital , developmental) Progress H/O trauma , infection, surgery. Family history Cranial vault Forehead unilateral flattening Eyes - intercanthal and interpupillary levels Malar prominences Nose -level of alar bases Lips -level of comissures Chin point Dental midlines Cant Biopsy

56. Diagnosis BISHARA Clinical examination: 1.Evaluation of the dental midlines 2. Vertical occlusal evaluation: 3. Transverse and antero posterior occlusal evaluations . 4. Transverse skeletal and soft tissue evaluation.

57. A)Clinical evaluation. Evaluation of the dental midlines Mouth open Centric relation At initial contact In centric occlusion. True asymmetries of skeletal or dental origins, if uncomplicated by other factors, will exhibit similar midline discrepancies in centric relation, and in centric occlusion. Functonal shift - Mask or accentuate the asymmetry

58. Vertical occlusal evaluation The presence of a canted occlusal plane could be the result of an unilateral increase in the vertical length of the condyle and ramus . The maxilla or temporal bone supporting the glenoid fossa could be at different levels on each side of the head . asking the patient to bite on a tongue blade and relating it to the interpupillary plane.

59. Vertical skeletal asymmetries associated with progressively developing unilateral open-bites may be the result of condylar hyperplasia or neoplasia

60. Transverse and antero -posterior occlusal evaluations Asymmetry in the Bucco -lingual relationship, e.g. a unilateral posterior crossbites , should be carefully diagnosed to determine if it is skeletal, dental or functional. If there is a mandibular deviation from centric relation to centric occlusion, the lower dental midline and chin point should be compared to other midsagittal dental skeletal and soft tissue landmarks in the open, initial contact and closed mandibular positions . If functional shift over long period of time - give occlusal splint Occlusal view of arches disclose side to side asymmetries, differences in B-L angulation Maybe rotation of entire arch need mounting on anatomic articulator using face bow transfer.

61. Transverse skeletal and soft tissue evaluation Deviations in dorsum and tip of nose and philtrum and chin point need to be determined. Inferior view of mandible

62. B)RADIOLOGICAL EXAMINATION : In addition to the clinical evaluation, differentiation between various types of asymmetries can be aided by the use of radiographs. A number of projections are available to properly identify the location and cause of the asymmetry.

63. The lateral cephalogram : Provides little useful information on asymmetries in ramal height, mandibular length and gonial angle . It is limited by the fact that the right and left structures are superimposed on each other and are at different distances from the film and x-ray source resulting in significant differences in magnifications. Useful in vertical asymmetries to see inferior border.

64. The panoramic radiograph Useful projection to survey the dental and bony structures of the maxilla and mandible. Is evaluated for overt sinus, intranasal(septum and Turbinates ) , TMJ , size shape and position of the condyle , periapical , periodontal and dental pathology The presence of gross pathology, missing or supernumerary teeth can be determined . The shape of the mandibular ramus and condyles on both sides can be grossly compared. Geometric distortions are significant disadvantage.

65. Postero -anterior projection Valuable tool in the study of the right and left structures since they are located at relatively equal distances from the film and x-ray source . So the effects of unequal enlargement by the diverging rays are minimized and the distortion is reduced . Comparison between sides is therefore more accurate since the midlines of the face and dentition can be recorded and evaluated. Can be obtained in CO and mouth open

66. LOCALIZATION OF ASYMMETRY : PA VIEW ANATOMIC APPROACH BISECTION APPROCH TRIANGULATION APPROACH

67. ANATOMIC APPROACH Harvold found that Zygomatico –frontal structures and crista galli are relatively symmetric structures as compared to other facial land marks that are further distant from the cranial base. Construction of the horizontal line through the Z-F sutures to act as the horizontal axis. A vertical line perpendicular to the horizontal axis is constructed to pass through and bisect the base of the crista galli . This vertical line approximates the anatomic midsagittal plane of the head.

68. BISECTION APPROACH In cases where it is difficult to accurately identify Crista Galli or the Zygomatico -frontal sutures,the bisection approach may be used. With the bisection approach bilateral landmarks are located and bisected. A reference line is then constructed, passing through as many of the mid-points of these bilateral landmarks. If a mid-point is obviously off in relation to most other midpoints, it may be advisable to exclude such a point. Evaluation of the bilateral asymmetry then follows the same principles as with the anatomic approach.

69. TRIANGULATION APPROACH The triangulation approach can be used to study the relative asymmetry of the component areas of the facial complex. Following the identification of bilateral structures and the midline on the radiograph, triangles are constructed that divide the face in to various components. The right and left triangles are then compared for symmetry.

70. Limitations of PA Cephalogram : Chances of apparent distances will be affected by a tilt of the head in the head holder. Precise measurements of the structures are difficult .

71. Various analysis are: Rickett’s analysis Svanholt and solow analysis Grummon’s analysis Grayson’s analysis Hewitt analysis Chierici method

72. RICKETT’S ANALYSIS Construction of midsagittal plane . A transverse plane is constructed by connecting the center of the zygomatic arches, then a perpendicular is constructred to the transverse plane through the top of the nasal septum or crista galli . Skeletal asymmetry is evaluated by relating the point ANS and pogonion to this mid sagittal plane. Dental Assymetr y can be evaluated by relating the upper and lower incisor roots to the midsagittal plane.

73. Using the MSR plane, Various transverse and vertical reference planes are constructed to measure the Nasal cavity width, Mandibular width, Maxillary width, Intermolar and intercuspid width which are then compared with the clinical norms of Ricketts.

74. GRUMMONS ANALYSIS :This a comparative and quantitative PA analysis. The analysis consist of different components including 1.A midsagittal reference line. 2.Horizontal reference line, 3. Mandibular morphology analysis 4 Volumetric analysis. Maxillo mandibular comparison of asymmetry. 6. Linear asymmetry assessment. 7. Maxillomandibular relation. 8. Frontal vertical proportion analysis

75. The midsagittal reference line Constructed from crista galli through ANS to the chin point. Horizontal reference lines are 1.Z line, 2.ZA line, 3.J line( jugal process). 4.One parallel to the z plane through menton

76. Mandibular morphology analysis Triangle are formed by connecting the head of the condyle,the antegonial notch and the menton and the triangles on either sides are compared . Volumetric analysis polygon is formed by connecting Condylon , antegonial notch, menton and a perpendicular from MSR and the right and left side polygon are compared.

77. Maxillo mandibular comparison of asymmetry Four lines are constructed perpendicular to MSR from Ag and from J bilaterally. Line connecting cg and J and lines from Cg to Ag are also drawn. Two pairs of triangles are formed in this Way , and each pair is bisected by MSR. If symmetry present, the constructed lines also form two triangles namely J – Cg – J and Ag – Cg – Ag.

78. Linear asymmetry assesment Perpendicular projection are drawn from the MSR to CO, NC, J, Ag and Me and the linear distance from MSR to the particular point on either side and vertical discrepancies are calculated Frontal vertical proportion analysis Ratios of skeletal and dental measurements are made with respect to MSR and those ratios can be compared with common facial esthetic ratios and measurements

79. GRAYSON ANALYSIS Landmarks are identified in different frontal planes at selected depth of the craniofacial complex and subsequent skeletal midlines are constructed. In this way the analysis enables visualization of midlines and midpoints in the third ( sagittal ) dimension..

80. HEWIT ANALYSIS Analysis of craniofacial asymmetry is performed by dividing the craniofacial complex into constructed triangles so called triangulation of face . The different angles, triangles and component areas can be compared for both the left and right side.

81. SUBMENTO VERTEX VIEW S ub- mento -vertical projections made on 10 subjects by CLIFFTON. T. FORSBERG , and CHARLES.J.BURSTONE and the resulting publication of AJO 1984 March , infers that the Sub- mento -vertical projection is particularly more useful than the PA projection. The S-V projection allows the utilization of anatomic landmarks on the cranial base , remote from the facial bones, for determination of the mid- sagittal axis , which is more reliable.

82. Infraorbital pointer is used to position patient's Frankfort horizontal plane parallel to the film cassette.

83. Acuscape 3D frontal image A , 3D image of patient-specific digital model with soft tissue photograph texturing added virtual patient. Digital model can be rotated to any angle, and planes can be cut to show underlying skeletal and dental tissues. B , 3D model showing skeletal and tooth morphology, with photograph texturing. Conventional 2D lateral and frontal cephalometric analyses can be viewed simultaneously. C , Model rotated to true submental vertex view to analyze symmetry.. D , Simple 3D “stick” model of skeletal landmarks connected in 3D space.

84. ADJUNCTIVE EVALUATIONS A number of patients seeking consultation for correction of their facial deformity benefit from additional evaluation to ascertain more completely the true nature of their deformity or to plan better for treatment. The following is a list of adjunctive evaluations A . Comprehensive psychologic evaluation               B.   Computer-assisted analysis 1 Video manipulation 2.Three-dimensional 3. CT scan reconstruction

85. C.Additional radiographs 1.Rest-position lateral cephalogram 2.Temporomandibular joint laminograms 3.Sinus series 4 Computed tomographic scans 5. Radionucleotide scans D.Diagnostic occlusal splint E Nasoendoscopy H Masticatory muscle evaluation 1.Electromyography and bite force determinations 2.Masseter muscle biopsy.

86. TMJ Imaging Radiographic and other imaging modalities should be used to investigate the TMJ when the patient presents with facial asymmetries and a continuously changing intermaxillary relationship. comprehensive TMJ imaging my include Conventional radiograph. Conventional tomography Computerized tomography. Arthroscopy Magnetic resonance imaging . Radionucleotide imaging to determine bone turnover activities.

87. PHOTOGRAPHIC ASSESSMENT Rakosi VERTICAL REFERENCE PLANE: Soft tissue nasion-Subnasale UPPER HORIZONTAL PLANE: B ipupillary plane LOWER . HORIZONTAL PLANE: Parellel to Bipupillry plane through the Stomion . BILATERAL MARKING OF ORBITAL POINT.

88. Use of overlay grid with central cross.

89. THE ESTHETIC FACIAL EVALUATION INCLUDES A.Photograph B.Front face analysis C.Profile analysis D. Duration E.Level of asymmetry F.Type of deformity G.Anterior teeth in occlusion and slightly apart PHOTOGRAPH FOR FACIAL EVALUATION FRONT FACE FRONT FACE SMILING

90. SUBMENTAL VIEW The submental view is taken with the patient , s head hyper extended about 45 degrees. It is useful to assess symmetry and projection of the anterior cranial vault, orbital areas and cheeks. Nasal deformities are also well documented and studied in this view

91. SUPERIOR VIEW The superior view is taken with the patient's head hyperflexed about 45 degrees. Like the submental view, it is useful in assessing anterior cranial vault, orbital cheek and nasal deformities. It is often more useful than the submental view for demonstrating and diagnosing cheek deformities .

92. THREE QUARTER FACE VIEWS Three quarter face views are taken with the patient's head turned midway (45 degrees) between the front face and profile view. The primary use of this view is to document and diagnose facial anomalies associated with the auricular and preauricular areas, the mandibular angle, the ascending ramus of the mandible, the nose, and the cheeks.

93. The photographic method illustrates the difference in the configuration of the two sides of the face. TRUE FRONTAL PICTURE 11 yr –old boy with a noticeable difference between the right and left sides of the face FIRST COMPOSITE FRONTAL PICTURE Altered facial form after photomontage of the two right sides of the face. SECOND COMPOSITE FRONTAL PICTURE Frontal view after photomontage of the two left sides.

94. FACIAL MIDLINE The evaluation of facial asymmetries is initially carried out by constructing on a front face photograph a line that represents the patient's true facial midline. Midlines are assessed with upper most condylar position with the teeth in their initial contact position. The relative positions of soft tissue landmarks (nasal bridge, nasal tip, philtrum , chin point) and dental midline landmarks (upper incisor midline, lower incisor midline) are noted . Facial keys to orthodontic diagnosis and treatment planning – part II Arnett and Bergman Am J Orthod Dentofac Orthop 1993 ;103:395-411

95. Facial level To examine facial levels a reliable horizontal landmark line is necessary. With the patient in natural head posture, the pupils are used as the horizontal reference line and adjacent structures are measured relative to this line. Structures compared with the pupil line are 1.upper canine level 2.lower canine level, and 3.chin and jaw level. Mandibular deviations commonly have upper and lower occlusal cants with chin and jaw line canting associated.

96. IDEAL FACIAL PROPORTION TRANSVERSE FACIAL PROPORTION Rule of fifth describe the ideal transverse relationship of the face. The face is sagitally divided in to five equal parts from helix to helix of outer ear . Each of the segments should be one eye distance in width A-THE CENTRAL FIFTH OF THE FACE B- THE MEDIAL TWO FIFTH C- THE OUTER TWO FITTH

97. VERTICAL FACIAL RELATION- THE FACIAL ONE THIRDS A well proportioned face is vertically divided in to equal thirds by horizontal lines,from hairline to midbrow , midbrow to subnasale , and subnasale to soft tissue menton . The thirds are within a range of 55 to 65 mm , vertically . The equality of the middle and the lower thirds should not be used as the determining factor in facial height changes. The appearance of the landmarks (incisor exposure , interlabial gap ) within the lower third are more important in assessing balance than are the equality of the middle and the lower thirds.

98. THE LOWER ONE THIRD - LIPS The lips are measured independently in a relaxed position. The normal length of upper lip is measured from subnasale to upper lip inferior The lower lip is measured from lower lip superior to soft tissue menton . During examination the relationship of the lips to the facial midline, its relationship to incisors during rest , smiling and the inter labial gap should be noted. The width of the lips from commissure to commissure is normally about equal to the Inter pupillary distance. If asymmetry exists one must determine if the existing asymmetry is primarily the result of

99. 1.an intrinsic lip deformity, as exists in many patients with clefts, 2. facial nerve dysfunction, or 3.an underlying dental-skeletal asymmetry. Each of these conditions requires different treatment considerations

100. CHIN The chin is evaluated for symmetry, vertical relations, and morphology and its relationship to the mandibular angles and inferior border of the mandible. Often the chin may be more tapered or more square than the rest of the face.

101. MIDDLE THIRD- NOSE AND CHEEKS Normal alar base width should be approximately the as the inter- canthal distance, which should be the same as the width of the eye . The significance of alar width in orthognathic Surgery is most recognized in maxillary surgery. Movement of maxilla in LeFort I osteotomies Often results in widening of the nasal base,Which in some cases may be acceptable but in most cases is not esthetically favourable . Evaluation of the cheeks consists of sequential assessment of the malar eminences, infraorbital rims, and paranasal areas for symmetry and normal projection.

102. MANDIBLE The most common asymmetric dentofacial deformities involve the mandible. The chin may contribute to the asymmetry, if it is more asymmetric than the mandible as a whole or may be noncontributory when it is no more asymmetric than the mandible. Mandibular asymmetries are usually accompanied by dental compensations where the teeth have adapted to the altered soft-tissue matrix surrounding the asymmetric mandible.

103. MAXILLA An isolated asymmetry of the portion of the maxilla with in the lower third face-the alveolus and associated dentition- is extremely rare . Most often an isolated maxillary asymmetry is dental rather than skeletal because of loss of teeth, unless such asymmetry is due to trauma.

104. Dental cast assessment Markings on cast Facial midline irt dental midline. Buccal segment markings to indicate CR. Molar and premolar widths Tipping of teeth.

105. INTRAARCH ANALYSIS - MAXILLARY ARCH Rakosi Arch should be analysed for both transverse and AP symmetry. AP reference plane is constructed using mid palatal raphe as a reference Plane and the tuberosity plane( drawn perpendicular to AP plane ) is used as a transverse reference plane .The position of teeth and arch symmetry can be measured with respect to these planes

106. INTRAARCH ANALYSIS-MANDIBULAR ARCH - Rakosi Construction of mandibular midline is more difficult than maxillary midline The anterior point can be precisely marked using mental spine film or by using the lingual frenum The posterior point is determined by a perpendicular , which runs from the posterior edge of the MPR from the maxillary to the mandibular cast

107. SYMMETROGRAPH Asymmetrical arch shape in transverse and AP direction , can be assessed using a template, oriented to MPR and tuberosity plane

108. Occlusal plane considerations

109. CONCLUSION Asymmetry in the craniofacial areas can be recognized as differences in the size or relationships of the two sides of the face. This may be the result of discrepancies either in the form of individual bones or a mal-position of one or more bones in the craniofacial complex. The asymmetry may also be limited to the overlying soft tissues. The point at which normal asymmetry becomes abnormal cannot be easily defined and is often determined by clinicians sense of balance and the patients perception of the imbalance.

110. THANK YOU