FACIAL ASSYMMETRY INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
Contents Introduction Etiology Classification Diagnosis Treatment of Dental asymmetries: Diverging occlusal plane Asymmetric buccal occlusion Unilateral dental crossbite Asymmetric arch form Midline discrepancies Treatment of skeletal asymmetry www.indiandentalacademy. com
Variations in the size, shape and relationship of the dental, skeletal and soft tissue facial structures are important in providing each individual with his or her own identity. Perfect bilateral body symmetry is largely a theoretical concept that seldom exists in living organisms. Right-left differences occur everywhere in nature where two congruent but mirror image types are present. In general, mammals have marked asymmetry as to the placement of the viscera in the body cavity. Man frequently experiences functional as well as morphological asymmetries, e.g. right and left handedness as well as preference for one eye or one leg. Some of these asymmetries are embryonically rooted and are associated with asymmetry in the central nervous system.
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Symmetry: “Equality or correspondence in form of parts distributed around a center 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 while significant asymmetry means imbalance Perfect bilateral symmetry RARE!! Peck and Peck (Angle 1991):- evaluated bilateral facial symmetry in 52 “exceptionally well-balanced” white adults and observed that there is less asymmetry and more dimensional stability as the cranium is approached. A slight tendency toward right-side dominance was not statistically significant. www.indiandentalacademy.com
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Vig and Hewitt (Angle 1975): - Evaluated 63 P.A cephs of “normal” children 9-18 years old. Overall asymmetry found in Most children; Left side larger cranial base mandibular region Right side larger maxillary region Dentoalveolar region greatest degree of symmetry compensatory change. The point at which “normal” asymmetry becomes “abnormal” cannot be easily defined and is often determined by the clinician’s sense of balance and the patient’s perception of the imbalance.
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Thomas.p. George, A. Valiathan: used various aids to assess facial assymetry like direct observation, radiographic technique, mechanical method and photographic technique, and found that a small degree of bilateral facial assymetry serves to characterise and individualize the estheticaly pleasing face rather than to disfigure it
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ETIOLOGY: I)
SKELETAL ASYMMETRIES:
1) GENETIC FACTORS: 2) INTRAUTERINE DISTURBANCE: 3) PATHOLOGY: 4) INFECTIONS AND INFLAMMATIONS: 5) FRACTURES AND TRAUMAS: II) DENTAL ASYMMETRIES: 1) ANKYLOSIS OF PRIMARY MOLARS: 2) ECTOPIC EPUPTIONS OF MAXILLARY PERMANENT FIRSTMOLARS 3) PREMATURE DECIDUOUS TOOTH EXFOLIATION: 4) CONGENITALLY MISSING TEETH: 5) SPACE LOSS DUE TO INTERPROXIMAL CARIES 6) ECTOPIC ERUPTION OF MANDIBULAR LATERAL INCISORS: 7) SUPERNUMERARY TEETH 8) HABITS: www.indiandentalacademy. com
I)
SKELETAL ASYMMETRIES:
1)
GENETIC FACTORS:
1% of all newborn infants have multiple anomalies or birth defects, 40% of which can be diagnosed as a specific, recognized syndrome. >300 known syndromes varying degrees of facial and occlusal asymmetries. Asymmetries appear to be related to abnormalities that affect either the number or migration pathway of neural crest cells. Premature fusion of craniofacial sutures facial asymmetry Molecular and genetic mechanisms : - Specific mutations have been identified in Muscle segment homeobox (Msx) Fibroblast growth factor receptor genes lead not only to facial clefting and synostoses, but also to congenitally missing teeth. Mutation in sonic hedgehog gene holoprosencephaly (loss of midline structures - Mild from absence of one maxillary central incisor. www.indiandentalacademy. com
Hemifacial microsomia: Varying degrees of mandibular asymmetry dental occlusion affected. Secondary growth distortion due to inadequate mandibular vertical growth ďƒ failure of growth in midface. Defect in proliferation and migration of early embryonic neural crest cells.
Congenital hemifacial hypertrophy Rare form of overgrowth involving both soft and calcified tissue. Right side is more commonly affected
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Facial photographs of a patient with hemifacial microsomia. The discrepancies involve one side of the face only and include asymmetries in the mandibular body, ramus and condyle as well as the external and internal structures of the ear. www.indiandentalacademy. com
2) INTRAUTERINE DISTURBANCE: 2% if newborn infants ďƒ deformations caused by nondisruptive mechanical forces during intrauterine life (after organogenesis); fetus is prone to deformation because of its great plasticity and rapid growth. example: muscular torticollis Postural scoliosis Plagiocephaly 3)Pathology: Osteochondroma of manidbular condyle: facial asymmetry, open bite on involved side, mandibular deviation. www.indiandentalacademy. com
Unilateral condylar overgrowth •Familial pattern •Bilateral differences in vascularity •Earlier traumas •Intrauterine pressure •Endocrine disorders. Progressive hemifacial atrophy (Romberg syndrome) • Subcutaneous tissues fat and bone affected. •Left side affected more •Occlusion and dentition may be affected underdevelopment of roots on affected side and failure of eruption, causing open bite on affected side. •Cause: - Trauma/ endocrine/ slow viral infection / nerve www.indiandentalacademy. failure. com
4) INFECTIONS AND INFLAMMATIONS: •Middle ear infections ankylosis of TMJ •Rheumatoid arthritis in childhood 5) FRACTURES AND TRAUMAS Condylar fractures may produce impaired growth and function:Condylar injury ↓ Intra articular bleeding and hematoma ↓ Ankylosis ↓ www.indiandentalacademy. com
Facial asymmetry (Displacement of chin to affected side, short ramus and upward tilting of the occlusal plane on the affected side.) According to Profit et al (1980), incidence of condylar fractures in childhood may actually be high and many cases may remain undiagnosed. Fractured condyle compensatory growth (Lund 1974) ↓ Overgrowth on affected side ↓ Lower incisal midline shift to opposite side. * Damage to a nerve may indirectly lead to asymmetry from the loss of muscle function and tone. www.indiandentalacademy. com
II) DENTAL ASYMMETRIES: Asymmetries within the maxillary or mandibular arch can produce asymmetric occlusal relationships. 1) ANKYLOSIS OF PRIMARY MOLARS:
•occurs in 4.1% of Caucasians •affected tooth appears “submerged” •asymmetric axial inclination of adjacent teeth •asymmetric molar occlusion •shift of midline toward affected side of arch •Arch asymmetry and asymmetric canine relationships. 2) ECTOPIC EPUPTIONS OF MAXILLARY PERMANENT FIRST MOLARS •4.3% of Caucasians. •Untreated ectopic eruptions lead to premature loss of the primary second molar tooth and subsequent loss of arch length on the affected side. •Asymmetric molar relationship, arch length-tooth size discrepancy and impaction of second premolar tooth. www.indiandentalacademy. com
3) PREMATURE DECIDUOUS TOOTH EXFOLIATION: Unilateral loss of some of the leeway space will result in a developing asymmetry in the molar occlusion 4) CONGENITALLY MISSING TEETH: 5% of population Most common: mandibular second premolars, maxillary lateral incisors, and maxillary second premolars. Congenitally missing mandibular premolars ↓ Primary molar retained ↓ Prevent mesial movement of permanent molar into leeway space ↓ Class II relationship on affected side. 5) SPACE LOSS DUE TO INTERPROXIMAL CARIES 6) ECTOPIC ERUPTION OF MANDIBLAR LATERAL INCISORS: Can cause premature exfoliation of primary canines. Shift in dental midline on affected side 7) SUPERNUMERARY TEETH 8) HABITS: asymmetric archwww.indiandentalacademy. forms com
A case presenting a number of dental arch asymmetries including: retained mandibular left second deciduous molar; congenitally missing mandibular left second premolar; and unilateral anterior crossbite between the maxillary lateral incisor and mandibular canine. www.indiandentalacademy. com
CLASSIFICATION OF DENTOFACIAL ASYMMETRIES: Dental Skeletal Muscular:-hemifacial atrophy or cerebral palsy, or with masseter hypertrophy. Function: Can result from the mandible being deflected laterally or anterposteriorly if occlusal interference’s prevent proper intercuspation in centric relation. Causes: constricted maxillary arch malposed tooth. In some cases, TMJ derangement and incoordination, accompanied by an anteriorly displaced disc without reduction, may result in a midline shift during opening, caused by interference’s in mandibular translation on the affected side. www.indiandentalacademy. com
2) According to Lundstrom (AJO 1961) Quantitative asymmetry: differences in the number of teeth on each side or the presence of cleft lip palate. Qualitative asymmetries: differences in the size of teeth, their location in the arches, or the position of the arches in the head. 3) Dental asymmetries in orthodontics can be classified into 4 groups: Diverging occlusal planes Asymmetric left to right buccal occlusion, with or without midline deviation. Unilateral crossbite Asymmetric arch form
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DIAGNOSIS OF FACIAL AND DENTAL ASYMMETRIES: The proper assessment of a patient with a facial asymmetry involves a comprehensive evaluation including History physical examination radiographic evaluation photographs growth studies (if indicated) Clinical examination: patient should be seated upright with good posture orbit, globe, nose and zygoma are evaluated for form and symmetry Auricles are inspected for symmetry in form, projection and placement. www.indiandentalacademy. com
Birds-eye view” is useful to assess asymmetries of the frontal zygomatic, nasal, mandibular, and chin regions. “Worms-eye view” reveals mandibular, nasal, molar, and glabellar asymmetries. The angles of the mandible are evaluated for projection and symmetry. Bilateral palpation of the inferior border of the mandible from chin to angle of the mandible can help to identify vertical asymmetries not visualized readily.
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Asymmetries in the mandible may be observed clinically from a frontal view, by observing the point of the chin as it relates to the rest of the facial structures.
Looking at the mandible from an inferior view sometimes helps determine the extent of its involvement in relation to the rest of the face. www.indiandentalacademy. com
INTRA-ORAL EXAMINATION: 1) Evaluation of dental midlines: should be done in the following positions: Mouth open In centric relation At initial contact In centric occlusion True asymmetries (skeletal or dental) exhibit similar midline discrepancies in centric relation and in centric occlusion. Asymmetries due to functional interference’s mandibular shift following initial tooth contact. This shift may be in same or opposite direction of the dental or skeletal discrepancy may accentuate or mask the discrepancy. www.indiandentalacademy. com
2) Vertical occlusal evaluation: The cant in the occlusal plane readily observed by asking the patient to bite on a tongue blade to determine how it relates to the interpupillary plane Causes could be: Unilateral increase in the vertical length of the condyle and ramus. Maxilla or temporal bone supporting the glenoid fossa could be at different levels on each side of the head. Progressively developing U/L open bite condylar hyperplasia or neoplasia www.indiandentalacademy. com
3) Transverse and antero-posterior occlusal evaluations: Unilateral posterior crossbite dental/ skeletal/ 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 lardmarks in the open, initial contact and closed mandibular positions. In some cases, a clinical examination may not be sufficient to detect a functional shift acquired over a prolonged period of time. “Occlusal splint” will allow the musculature to freely guide the mandible to its proper relationship without the distracting influence of occlusal interferences. Arch asymmetry could also be due to rotation of entire maxilla or mandible. Diagnosis of a rotary displacement of maxilla may require mounting the dental casts on an anatomic articulator using a face bow transfer. www.indiandentalacademy. com
II) RADIOGRAPHIC EXAMINATION: Lateral caphs: limited value. Reasons: Right and left structures are superimposed on each other with differences in magnification. predetermined orientation using ear rods assumption is made that external auditory meati are symmetrical panoramic radiograph: Gross pathology/ Missing / Supernumerary teeth can be determined Shape of mandibular ramus and condyles on both sides can be grossly compared Postero-anterior projection (PA ceph): Valuable tool in the study of right and left structures since they are located at relatively equal distances from the film and x-ray source. Can be obtained in centric occlusion as well as with mouth open. The latter position might help determinethe extent of the functional deviation, if any. Localization of the asymmetry from the P.A ceph: Structures to be used in the construction of the mid-sagittal reference plane need to have a relatively high degree of symmetry. www.indiandentalacademy. com
1. THE ANATOMIC APPROACH:
Harvold (AJO 1954) recommended the construction of a horizontal line through the zygomatico-frontal 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 crista galli. This vertical line approximates the anatomic midsagittal plane of the head. Nasion and ANS fall on or near this plane 90% of the time. Perpendiculars from bilateral structures can be constructed to this vertical plane. Differences ďƒ asymmetry 2. THE BISECTION APPROACH: Bilateral landmarks are located and bisected. A reference line is then constructed, passing through as many of the midpoints of these bilateral landmarks as possible. 3. THE TRIANGULATION APPROACH: Following the identification of bilateral structures and the midline on the radiograph, triangles are constructed that divide the face into various components. The right, left triangles are then compared for symmetry. Three dimensional imaging techniques computerized tomography photogrammetry optical scanning www.indiandentalacademy. Disadv : - Costly com
RECENT STUDIES: Edler et al (AJO 2003) described an approach for the measurement of asymmetry from photographs with digitized mandibular outlines, and found close correlation between measurements taken from photographs and digitized cephalomatric radiographs. The measurement of asymmetry from a photograph seems appropriate because it is noninvasive and also soft-tissue appearance is taken into account. Relationship between transverse dental anomalies and skeletal asymmetry (Kusayama et al. AJO March 03) To recognize the relationship between a transverse dental anomaly and skeletal asymmetry, frontal cephalometric and 3 dimensional dental model analysis were carried out on 44 adult Japanese Class III patients, who required surgical www.indiandentalacademy. orthodonticTreatment. com
Characteristic dental anomalies in the facial asymmetry group included asymmetry of Curve of spee Molar inclination Dental arch form lateral overjet and slanting of occlusal plane. ďƒ high correlation between dental anomalies and skeletal asymmetry.
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TREATMENT OF DENTAL ASYMMETRIES: I TREATMENT OF DIVERGING OCCLUSAL PLANES a) CANTED ANTERIOR OCCLUSAL PLANE: ( in transverse direction)
Vertical elastics: exert extrusive force on both maxillary and mandibular arches. If both upper and lower occlusal planes are equally diverging and the treatment plan calls for extrustion, this is a viable option. In patients with a canted maxillary anterior occlusal plane and a deep bite, the cant can be corrected in combination with overbite correction. One-piece intrustion arch of .017x .25” Titanium molybdenum alloy Tied to that side of the anterior segment requiring intrusion.
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If canine also requires intrusion, this is better performed after the incisor intrusion (.017 x .025 TMA cantilever from molar auxiliary tube is tied underneath bracket) When there is no deep overbite problem and only one side requires extrusion, a unilateral cantilever can be used to correct the occlusal cant. The cantilever 0.017 x 0.025� TMA, comes out of the auxiliary tube of the first molar on the side where the extrusion is to take place, and is hooked around the anterior segment. A force of approx. 30 gm is sufficient.
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b) Canted posterior occlusal plane (in anteroposterior direction) A variation of the intrusion arch can also be used to correct a cant of the posterior occlusal plane in patients with deep overbite Cantilever with hook side effects: - extrusion of buccal segment and unilateral intrusion of anterior segment. The magnitude of force is increased to 150gm that causes a large tip-back moment on the buccal segment, thereby flattening the occlusal plane.
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Unilateral cant of the occlusal plane, in which the posterior occlusal plane on one side is steeper than the occlusal plane on the contralateral side:- can be corrected with the use of a precision palatal arch in the maxilla and/or a precision lingual arch in the mandible (depending on the location of the problem). A lingual arch with a tip-back activation on the steep side and a tip forward activation on the contralateral side will deliver the desirable moment to correct a cant of the mandibular occlusal plane.
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2. TREATMENT OF ASYMMETRIC LEFT AND/OR RIGHT BUCCAL OCCLUSION: a) Differences in left and right molar rotation:
CORRECTION: TPA with equal amounts of antirotation activation, .018 x.025 stainless steel wire tied into all teeth except rotated molar. www.indiandentalacademy. com
CORRECTION: TPA with equal amounts of antirotation activation, .018 x.025 stainless stell wire tied into all teeth except rotated molar. TPA with equal amounts of antirotation activation. 0.018 x 0.025 stainless Steel wire tied into all teeth except the rotated molar
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b) Differences in right and left molar axial inclinations: M-D axial inclination of molar is assessed by tracing a horizontal anteroposterior line connecting the tip of the buccal cusps of molar.
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•To correct uniarch molar asymmetries a lingual or palatal arch (0.032 TMA) activation is made to deliver a tip-forward moment on the Class I side and a tipback moment on the Class II side.
Unilateral Class II elastics can be used in associated with a continuous arch wire, but this approach has a number of side effects.Cant of anterior occlusal plane resulting from extrustive component of class II elastics
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Open-coil springs or sliding jigs is used to tip back the molar unilaterally to correct its mesiodistal axial inclination (More predictable before the eruption of the second molar) side effect of coil spring mesial force to premolars and canine Unilateral Class II elastics can be used to counteract the mesial force delivered by the coil spring. Side effect:Extrusive component of Class II elastics Skewing of the dental arches Flaring of lower incisors.
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Unilateral tip-back bends incorporated in 2x4 appliances or continuous arch wires. The force system includes a unilateral tip-back moment at the molar on the side of the tip-back bend, but also a unilateral intrustive force on the anterior portion of arch on same side. UNILATERAL INTRUSIVE FORCE ďƒ CANTING OF ANTERIOR OCCLUSAL PLANE
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Jasper Jumper (activated unilaterally):Continuous round wire in the maxillary arch .heavy rectangular arch wire in the mandibular arch. Maxillary molar tip-back force + intrusive force Mandibular arch anterior section of the arch will have applied a mesial and intrusive force => cant of the lower anterior occlusal plane on the side where the Class II correction is needed + flaring of the lower incisors. Skewing of the maxillary and mandibular arches asymmetric overjet and midline Unilateral intrusive force leads to Canting of anterior occlusal plane www.indiandentalacademy. discrepancy. com
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Three-piece base arch + palatal arch: (shroff; AJO 1995) and (Shroff, Linduar and Burstone, EJO 1997)
3-piece base arch ďƒ delivers bilateral tipback moments + intrudes anterior teeth. Palatal arch ďƒ unilateral tip-back activation on the side that needs molar uprighting Opposite side ďƒ tip-forward moment from palatal arch + tip- back moment from 3-piece base arch * Buccal segments of wires are not used with the 3 piece base arch in order to encourage distal drifting of the premolars and canines as the molar uprights on that side of the arch. www.indiandentalacademy. com
Asymmetric Headgear: (Hack and Weinstein AJO 1958) Eccentric cervical traction can be obtained clinically by making the arm of the face bow longer on the side on which the greater force is desired. Disadvantage: A net lateral force is produced at the inner bow which has a tendency to create a lingual crossbite on the side that receives the greater distal force. Patient compliance
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Asymmetric extractions:
In Class II subdiv:- usually mandibular midline is displaced to Class II side 4 premolar extractions Success is dependent on headgear wear, diagonal elastics. Janson et al (AJO 2003): 51 patients with Class II subdiv GP I (28) – 4 premolar ext. Gp II (23) – 3 premolars (2 maxillary + 1 mandibular on Clas I side) In GP II greater improvement of initial midline deviation and slightly better treatment success rate. Cl I canine and molar relation on Cl I side Cl II molar and Cl I canine relation on Cl II side with coincidence of dental midlines www.indiandentalacademy. com
III) TREATMENT OF UNILATERAL DENTAL CROSSBITE: (Steinbergen and Nanda 1995 AJO) Can be performed with a lingual arch (0.032 x 0.032 inch TMA) in the mandible and transpalatal arch (TPA) in the maxilla. Diagram represents force system needed to correct unilateral dental crossbite. Lingually tipped upper molar: Rigid arch wire tied to all teeth except molar in crossbite. Buccal root torque placed in TPA on side that is not in crossbite Expansion activation built in to the Tpa The vertical forces which cause side effects on the two molars, are small and usually not expressed because occlusal forces are larger. Note: The moment- force ratio on the correct side should be larger to prevent this side from tipping www.indiandentalacademy. buccally com
IV) TREATMENT OF ASYMMETRIC ARCH FORM: Orthodontists often use an asymmetrically shaped arch wire or asymmetric inter-arch elastics to correct on asymmetric arch form. A more efficient way is to use a cantilever (.017 x .025 TMA), from the first molar, with a hook that is attached in the area where the arch needs to be expanded or contracted. The cantilever can be inserted on top of a light arch wire, for example 0.016� TMA. A TPA or lingual arch connecting the molars should be in place to prevent rotation of the molar to which the cantilever is attached.
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V) MIDLINE DISCREPANCIES- DIAGNOSIS AND TREATMENT: Establishing skeletal midline: using PA head film : 1. From horizontal planes in cranial base, perpendiculars are drawn through crista galli or some other midline point. Disadvantage:horizontal planes are difficult to establish The planes may not be parallel to each other. 2. By bisecting the distance between bilateral points on the greater wing of sphenoid or the orbits or other lateral points on the outside of the skull. Disadvantage: Differences in width between right and left sides may exist even in the most symmetric individuals. 3.Median palatal raphe may be used as a guide. Disadvantage: There may be error in establishing a perpendicular to the raphe Many raphes are not linear, but display curvature. www.indiandentalacademy. com
4.Apical base midline: Tracing is done on PA head-film. A treatment occlusal plane is established, and to that occlusal plane, the midlines of the maxilla and mandible are evaluated.
Skeletal problem with apical base discrepency
Upper midline to right without apical base discrepancy
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Presence of apical base discrepancy ďƒ treatment becomes more difficult because translation of teeth across midline may be required. No apical base discrepancyďƒ treatment is simplified because simple single forces can be used to tip teeth to correct the midlines
Dental midlines correspond.Apical base discrepancy is masked by compensatory tipping www.indiandentalacademy. com
Establishing facial midline: center of philtrum good guide to the placement of maxillary dental midline. The “V” at the vermilion border forms a good landmark that is easily identified by orthodontists and patients.
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Treatment of asymmetric midlines: Angle , used class III elastics with a tandem anterior diagonal elastic in conjunction with arch expansion for the correction of midline discrepancies
Alexander 1987,advocates the use of heavy anterior diagonal elastic supported by Cl II or Cl III elastics,depending on th etype of malocclusion.
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Begg and Kesling 1977, stated that the proper balancing of spaceclosing elastics coupled with appropriate Class II traction, keeps the midlines coordinated with one another
Strang and Thompson 1958, introduced a double vertical spring loop assembly to move the four incisors "en masse� www.indiandentalacademy. com
The arch wire as originally designed has somewhat limited activation potential,so a modification of this arch wire configuration using round wire would enable the practitioner to achieve a greater range of activation. This would result in a faster correction without the need for soldering spurs and without encountering the labiolingual offset difficulties associated with the use of full-sized rectangular arch wires.
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Proffit 1986, admits that minor discrepancies in midline coordination can be handled in the finishing stages with asymmetric Class II and Class III elastics as opposed to unilateral elastics or by using unilateral Class II or Class III intermaxillary elastics in tandem with an anterior diagonal elastic
Gianelly and Paul 1970, advocated a biomechanical system for midline correction with second-order bends used to move teeth on one side distally and create a space for shifting the midline.
Lewis (AJO 1976) advocated the use of distal spring mechanics bolstered by a sliding yoke of Class II traction to distalize upper posterior teeth. Thus, the maxillary teeth on the Class II side are moved one by one distally until coincident midlines are achieved. www.indiandentalacademy. com
Use of diagonal/ asymmetric elastics seem to link midline discrepancies and their correction with the cause being a mandibular shift or rotation of some sort. If this shift or rotation was not the causative factor but rather the midline deviation was the result of drifting of teeth, with the face being symmetric, then use of such mechanics would effect a change in mandibular position.
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TREATMENT OF SKELETAL ASYMMETRY: Mandibular asymmetry: I Functional mandibular shift: Adolescents:Maxillary sutural expansion Arch coordination and crossbite elastics Adults:2 or 3-piece maxillary expansion via Lefort 1 Osteotomy Surgically assisted maxillary expansion Arch coordination via orthodontics II True Mandibular asymmetry: Adolescents:“Hybrid Functional Appliance”a bite block is incorporated between the teeth on the normal side while the appliance on the shorter side is constructed to allow space for dentoalveolar eruption. www.indiandentalacademy. com
The bite block prevents maxillary and maxillary dentoalveolar eruption on the affected side, thus reducing the amount of compensation in the maxilla. The functional appliance on the affected side can distract the condyle and encourage growth and remodeling. Hybrid functional appliances may be successful in improving the growth potential of a hypoplastic condyle, but its main use is to keep the maxilla transversely level and control maxillary asymmetry It works best in growing patients with unilateral condylar fractures. Adults: Bilateral ramus osteotomics Distraction Osteogenesis of mandible. Camouflage through bone grafting or alloplastic augmentation through dermal grafts, fat grafts and silicone injections.
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Transverse cant of maxilla (Maxillo-mandibular asymmetry): Hybrid functional appliances Maxillomandibular surgery. Chin asymmetry: Lateral or vertical movement of chin via inferior border osteotomy. Camouflage via bone graft, ostectomy or alloplastic augmentation
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CONCLUSION: Patients presenting with significant clinical asymmetry pose special diagnostic and treatment challenges to the orthodontist. Determination of underlying cause of the asymmetry, meticulous clinical and radiographic evaluation and related dental cast analysis in centric relation and occlusion, as well as thorough review of the past medical and dental history, are necessary to evaluate the asymmetry in 3 planes of space. Asymmetries may be skeletal/ dental or functional in origin or combination of the above. It is essential to determine if the asymmetry is stable or progressive in nature, secondary to abnormal growth or pathology, before formulating a treatment plan. In the management of dental arch asymmetries, the clinician should select the appropriate force system and the appliance design necessary to address the asymmetry while minimizing undesirable side effects. www.indiandentalacademy. com
REFERENCES: 1.Thomas George. P, A.Valiathan,Padmapriya:A posteroanterior cephalometric study of facial asymmetry. JPFA 2000:14:53-59 2.Thomas George. P, A.Valiathan:Assymetry of Face, KDJ vol16 No.3 Pg 805-810 3. Van Steenbergen and R. Nanda: Biomechanics of Orthodontic correction of dental asymmetries. AJO 1995; 107: 618-24
4. Bishara et al:Dental and facial asymmetries a review. Angle 1994; 64: 89-98 5. Charles Burstone:Diagnosis and Treatment planing of patients with asymmetries. Semin Orthod 1998; 4: 153-164 6. Shroff and Siegel:Treatment of patients with asymmetries using asymmetric Mechanics, Semin Orthod 1998; 4: 165-179 www.indiandentalacademy. com
7. Jerrold and Lowenstein:The midline: Diagnosis and treatment, AJO 1990; 97: 453-62 8. David Sarver: Esthetic orthodontics and orthognathic surgery ,Mosby 1998 pg 24-28 9.Graber and Varnarsdal: Current principles and techniques in orthodontics ,4th ed; Mosby 2005pg 26-40 10. Janson et al :Class II subdivision treatment success rate with symmetric and asymmetric extraction protocals. AJO 2003; 124: 25764 11. Haack and Weinstein:The mechanics of centric and eccentric cervical teaction ,AJO 1958; 44: 346-357. 12.Dahan.J:A simple digital procedure to assess facial assymetry. AJO 2002;122:110-116 www.indiandentalacademy. com
13.Edler R, Wertheim D, Greenhill D: Clinical and computerized assessment of mandibular assymetry. EJO 2001;23:185-191
14. Janson et al :Cl II Subdiv: Treatment success rate with symmetric and asymmetric extracton Protocols. AJO 2003; 124: 257-64 15. Edler et al :Comparison of radiographic and photographic measurement of mandibular asymmetry. AJO 2003 (Feb) Pg. 167-174. 16. kusayama et al:Relationship between transverse dental anomalies and skeletal asymmetry. AJO 2003; 123: 329-37.
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