cefalometria frontal 2

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Great smiles have harmony, symmetry, and abroadness consistent with the individuals facialform, morphology, and balance. Smiles communi-cate, are expressive, and especially beautiful whenfull. People do not perceive narrow arch smiles to beappealing. A proportional smile fills the lip embra-sures and eliminates black triangles. We see this asbeauty in nature, and such symmetry is preferred bythe public. Orthodontic capabilities have increasedwith improved 3-dimensional knowledge of dentofa-cial growth and refined facial orthopedic procedures.The technology of tooth movement, fixed functionalappliance efficiencies, space-gaining methods, and

nonextraction approaches further enhance facialesthetics and symmetry of the outcome. Optimaltransverse dimension should be developed foresthetic and functional advantages. Facial, skeletal,and dental midlines should be centered, with pleas-ing facial and dental proportionality.1,2

FFACIAL ASYMMETRACIAL ASYMMETRYY

Definitive treatment philosophy

Maxillofacial and plastic surgeons, orthodontists,periodontists, and/or restorative colleagues canmake significant and positive improvements forpatients with asymmetric smiles. Beneficial resultsoccur structurally, dentally, emotionally, and estheti-cally for those patients having dentofacial dysplasiawith associated malocclusion. Progressive clinicianstoday must capably handle these asymmetric anddysfunctional patients in an interdisciplinary teamapproach. The frontal analysis applications describedin this two-part article3 provide meaningful, practical,

Frontal Cephalometrics: Practical Applications,Part 2

Duane Grummons, DDS, MSD1/Robert M. Ricketts, DDS, MS2

Aims: To (1) demonstrate the needs and benefits of three-dimensional diagnostic and treat-ment applications; (2) illustrate practical clinical applications of anteroposterior images andfrontal analysis; and (3) enhance utilization of the Ricketts and Grummons frontal analyses.Methods: Frontal analysis methods and applications are specified and integrated into facial,smile, jaw, and occlusal therapies. Asymmetry conditions must be differentially diagnosedand effectively treated. Frontal and related image analysis and tracing steps are detailed.Results: Asymmetry of facial parts is the rule, rather than the exception. Dental and facialmidlines, occlusal plane, chin location, and smile esthetics are primarily emphasized. Beau-tiful facial proportions and smile harmony can be developed despite initial facial dysmor-phosis and disproportions. Conclusions: Patients view themselves from the frontal perspec-tive, so this carries priority when assessing problems. It is important to know the etiology ofasymmetry to assist others with genetic counseling. Facial harmony and smile beauty areoptimal when facial and maxillary dental midlines are aligned. The maxillary dentitionwidth should be sufficiently wide to be in harmony with the individual patient facial mor-phology. The occlusal plane should be level and the chin centered as much as possible.Best facial development and proportionality exist when the skeletal and dental componentsare optimized transversely and are symmetric. World J Orthod 2004;5:99119.

1Private Practice of Orthodontics, Spokane, Washington, USA.2 This WJO 2-part article is the last publication involving Dr Rick-etts before his death.

CORRESPONDENCEDuane Grummons DDS, MSD, 9425 N Nevada, Suite 100,Spokane, WA 99218-1283, USA. E-mail: [email protected] or [email protected]

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and progressive information regarding asymmetricand often complex treatment situations. Ordinarycases may be routine, while unusual asymmetryproblems challenge the understanding and expertiseof the therapeutic team. Tools available to differen-tially handle such disproportional and dysfunctionalpatients have advanced significantly. Better patientmanagement and predictable treatment responsescan occur with therapy based upon fundamentals ofbasic science, with clinical sensibility in comprehen-sive and definitive clinical approaches. Answers andapproaches for these asymmetric patients empha-size facial orthopedic, orthodontic, restorative,orthognathic surgical, and/or intracapsular temporo-mandibular joint (TMJ) management. All this stressessensible and progressive treatment, provided in acaring manner.4 Knowledge is knowing facts; wisdomis knowing what to do with them.

Attractiveness and Health

Beauty or attractiveness really is in the eye of thebeholder; a genetic component exists. Men whosephotographs show facial asymmetry are reportedmore likely to have psychological problems, difficultieswith concentration, and lower intelligence than thosemen judged to be facially symmetric.5 Males whosefaces are viewed as high in symmetry are rated asmore attractive, dominant, sexy, and healthy. Womenwhose photographs exhibit facial asymmetry showpoorer health, emotional instability, and are lessactive lifestyles, and were less happy and less intelli-gent than those whose photographs are facially sym-metric. We choose our friends, mates, employees, androle models based in part on their facial symmetry.Having a symmetric face does not automatically implysuperior traits, but human facial asymmetry has longbeen a critical factor for evaluation of attractiveness.There is cross-cultural agreement; faces judged asattractive in one society are judged to be equallyattractive in other societies.6,7 People with attractivefaces receive more positive reactions than those withunattractive faces8 and are given positive attributespurely on the basis of facial beauty.9

Facial actions

Jaw asymmetry may be obvious cosmetically, andoften there is a functional impairment, resulting indifficulty with facial actions, expressions, chewing,biting, and swallowing. The face can appear asym-metric during facial expression, with one sideappearing more expressive. The source of this asym-

metry is in facial motion and structural facial asym-metry.10 Structural asymmetry (neutral expression)accounts for asymmetry at peak expression for joy,anger, and disgust. Expressions are produced moreintensely on the left side of the face, consistent withthe hypothesis that the right cerebral hemisphere isdominant for the expression of facial emotion.

EXAMINAEXAMINATION AND EVTION AND EVALUAALUATIONTIONFOR ASYMMETRIESFOR ASYMMETRIES

Examine patients from directly in front while they areseated, and level the interpupillary plane horizontalwith the floor to look for facial asymmetries.11 Lookfor any cant of the occlusal plane, which can bemeasured from the inner canthus of the eye to thetip of the canine. It is clinically relevant to observemidline discrepancies and important to recognizefacial asymmetries. Malar hypoplasia is confirmedby examining the patient from above. Examine andnote any asymmetry of the middle or lower third ofthe face, while examining the patient in front. Thismay be facilitated by placing marks on the patientsface and by analyzing a clinical photograph (Fig 1).Clinicians must do a thorough diagnosis at the onsetand observe important clues during treatmentregarding facial asymmetries that may be subtle orlatent.

Photographic images

The following images should be taken and examined:

Full face frontal and angular three-quarter views atrest, smiling, and animated

Right profile; both profiles if asymmetry is observedAnterior teeth in occlusion and slightly apartRight and left buccal segments

In addition, black and white, computer-reversedembossed images of the patients frontal and profileviews can be useful for treatment planning. Familyphotographs are also helpful in establishing the originof the deformity and predicting the postoperativenorm. For images to be of greatest value, hair shouldbe retracted or removed from the face. To construct aphotographic montage, profile photographs are cutand computer flipped; the pieces are then rearrangedto give an impression of what is likely to be achieved byfacial orthopedics or surgery.12 This method is empiri-cal and simplistic, but it can be helpful (Fig 2). Themontage has limitations, the most obvious being softtissue representation (Fig 3). Since the montage does

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not accurately superimpose on the lateral skull imageor radiograph, computerized simulations can do this.

Cast analysis

Analysis in the mandibular dental arch regardingteeth in the frontal dimension concerns mandibularmolar and premolar width, dental midlines, and den-tal to skeletal midline. The maxillary molars relativeto the mandibular molars are measured from thewidest points on the buccal contours. Thus, the con-dition and position of the mandibular arch becomesthe basis, since it is the most limiting factor andinfluences maxillary arch emplacement. Even a rou-tine cast analysis reveals asymmetry, especially in aunilateral malocclusion (Fig 4). When one side of themandibular arch is tipped lingually more than theopposite side1 (Figs 5 to 7), the clinician should beparticularly observant.

For uncomplicated cases, a hinge articulator maybe used. For complex cases, especially those withfacial asymmetry and craniofacial problems, a face-bow recording and/or anatomic articulator areessential. Important markings on the casts, madewhile directly comparing on the patient are:

Facial midline in relation to the dental midline. Thiscan be marked on the patients gingivae and teethwith a felt-tipped pen before taking the impres-sions. The ink mark will be transferred to the cast.

Buccal segment markings to indicate the centricrelationship on the casts, or that of maximal inter-cuspation, ie, habitual occlusion. Maximal intercus-pation is the final relationship to which the surgicaljaw movements are usually planned. However, thepreoperative difference between centric relationand habitual occlusion may be large, and can giverise to misleading predictions of movement.

Fig 1 (a) Significant hemimandibu-lar hyperplastic asymmetry. (b) Facialassessment is facilitated with acetateoverlay upon patient photo.

a b

a b

Fig 2 Interocclusal bite registrationwith vertical and horizontal referencesto reveal dental and maxillomandibu-lar asymmetries. Dental floss is heldvertically as a further visual guide.

Fig 3 Facial image cropped at facial midline, then copied and flipped; thisresults in a useful symmetric facial projection image.

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Radiographs and digital imaging

Understanding the importance of 3-dimensionalanatomy, Ricketts introduced the frontal cephalo-metric radiographic analysis to aid in diagnosis.1317

A craniostatic posteroanterior (PA) view of the skullhelps to reveal facial bone asymmetry. However,remember that the head may be tilted in the head-holder if the external auditory meati are asymmetric,giving a distorted radiographic image (Fig 8). Clini-cians routinely use 2-dimensional images, includingpanoral radiographs (Fig 9), facial and intraoral pho-tographs, and cephalometric tracings. These 2-dimensional views have limitations; such geometric,rotational, and head positioning errors mean thatthe anatomy is not accurately represented. Someelements can be obscured, and calibrating the viewsis a problem (Fig 10). True 3-dimensional informationincludes plaster casts of the teeth, which so oftenare not accurately merged or calibrated with theother diagnostic information.

Use of an interactive 3-dimensional digital modelof a patients anatomy (Fig 11) would greatly improvethe ability to determine different treatment options,monitor changes over time, predict and consistentlydisplay fine treatment results, and measure treat-ment outcomes more accurately.18 The Acuscapemethod (Acuscape International, Glendora, CA, USA)combines standard cephalometric radiographs androutine photographs to create a 3-dimensional matrixand a 3-dimensional digital patient.19 Three-dimen-sional radiographic imaging of dental structures isbecoming a reality due to the advent of cone beamcomputer tomography (CT) and 3DX multi-imagemicrocomputer tomography (NewTom, Aperio, Sara-sota, FL, USA). Whether viewing bone, periodontal lig-ament space, enamel, dentin, or pulp, the 3DXimages are better than can be generated by the med-ical CT machine (Figs 12 to 14). The calculated skindose for the 3DX scan is about 1/400 the medical CTscana huge reduction. Many companies are workingon cone beam units able to image the whole head,

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Fig 4 (a) Class II, subdivision right malocclusion. (b) Mandibular midline to right side due to mandibular asymmet-ric skeletal deficiency. (c) Left-side relationship is Class I dental.

Fig 5 (a) Mandibular premolars andmolars are in lingually compressedpositions with excessive unilateralcrowding. (b) With narrow maxillae,the mandibular posterior teeth inclineinward.

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Fig 6 (left) The mandibular occlusalradiographic image is particularly use-ful to locate asymmetric variations,such as dental and skeletal midlines,chin location, arch irregularity, trans-verse compensations, and lingualangulations.

Fig 7 (right) Dental arch asymmetryand asymmetric arch-length excessrequired 6 incisors in final result tocreate best occlusion and stable sym-metric outcome.

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Fig 8 (a) Asymmetric mandibular borders, which can be due to true skeletal asymmetry, or the head may betipped sideways to fit into the cephalostat due to asymmetric auditory meatus/porion locations. (b) Typical morphol-ogy of ramal and condylar process. (c) Morphologic adaptive changes on the asymmetric short side. (d) Frontalimage reveals maxillomandibular asymmetry. (e) Frontal asymmetry tracing. (f) Mandibular borders are different;compare the two sides.

ed

f

Fig 9 By tracing the ramaland condylar processes frompanoral image of mandible(a), the two sides can becompared for reliable asym-metry assessment (b).

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Fig 10 (left) Frontal xeroradiographclearly depicts anatomy.

Fig 11 (right) Acuscape 3-dimen-sional frontal image (Acuscape Ser-vices, Glendora, CA, USA).

which will ultimately replace today's cephalometricand panoral images with one 3-dimensional scan.

Three-dimensional, corrected TMJ tomographyreveals TMJ degenerative joint disease (DJD) whichcommonly occurs subsequent to facial macro- ormicrotrauma, facial jaw asymmetry, complex Class IIor Class III skeletal/dental malrelationships, majordental rehabilitation, dental crossbite, deep-bite con-ditions, open bite (anterior) conditions, multiplemissing posterior teeth, and/or parafunction that isexcessive or long-term.4

MAXILLOMANDIBULAR MAXILLOMANDIBULAR ASYMMETRASYMMETRY FEAY FEATURESTURES

Many facial asymmetries are mild or so slowly pro-gressive that they are not clinically significant. Other

facial asymmetries necessitate reevaluation andbecome recognizable during adolescent growth.There are dental, skeletal, and functional asymme-tries; most are a combination. The simplest asymme-try to treat is the dental asymmetry, if recognized andtreated in the mixed dentition stage. These asymme-tries can be due to premature loss of teeth, as whenone primary canine is exfoliated significantly earlierthan its contralateral. Ankylosed teeth can also leadto a dental asymmetry. A dental asymmetry recog-nized early is routine to correct and manage; waitinguntil the permanent dentition stage creates a prob-lem more complicated and costly to overcome. A den-tal asymmetry demonstrates a symmetric skeletonand growth pattern. A functional asymmetry involvesa symmetric jaw and dentition, while the patient func-tions in an asymmetric way. Untreated functionalshifts usually result in a skeletal asymmetry.20 A

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Fig 12 (a) Frontal 3-dimensionalimage generated with NewTom 9000(Aperio Services, Sarasota, FL, USA).(b) NewTom frontal image, coronalsection.

Fig 13 Ramal process and zygo-matic arch asymmetries are evidentwhen right/left sides are compared.

Fig 14 (a) Hemimaxillary and hemi-mandibular skeletal and dental asym-metries captured by NewTom 90003-dimensional imaging technologies.(b) Asymmetric mandibular morpho-logic variations.

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b

a

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skeletal asymmetry is characterized by a symmetricdentition without functional shift. It can be present atbirth, with growth subsequently being symmetric(nonprogressive asymmetry), or may be a progressiveskeletal asymmetry that worsens with continuedasymmetric growth. Most individuals with asymmetricfacial growth have compensations in the dentition. Aproblem list should be generated to differentiallydiagnose and treat facial asymmetries.

Asymmetry assessment and treatment strategies

When a developing asymmetry is recognized, theclinician should promptly take the appropriateprogress records, reevaluate the case, and establisha specific, differential treatment strategy with alter-natives. Remove the orthodontic appliances at theright stage, if the patient is younger, and wait forgrowth to be completed. Treat with definitive jawsurgery later. Watch for latent growth, especially if amandibular hyperplasia is suspected. Surgeonsreadily diagnose asymmetries when they evaluatepatients after growth is completed, but such a diag-nosis is more difficult in younger patients becausethe asymmetry may not be as developed nor as rec-ognizable. After patients complete their adolescentgrowth, problems become evident. Facial asymmetrysubsequent to a ramal or mandibular body hemihy-pertrophy, condylar process elongation, or aplasiamay also occur.

Functional observations:

Occlusal and transverse plane asymmetry; panoraland cephalometric views

Lower border superimpositions; on cephalogramand panoral images

Distance between first molars and the verticalramus; panoral view

TMJ dysfunction; manual jaw posturing or position-ing splint

Dental casts; midlines coincident or not

Structural asymmetry:

Signs of developing asymmetriesAsymmetric canine buccal overjetAsymmetric mandibular canine positions within archUnilateral posterior open bite Crossbites that develop Second molar unerupted on asymmetric sideTipping of the occlusal planeMidlines no longer coincident

Body length and ramal height not symmetric, nor isthe distance from the second molar to the anteriorborder of the ramus

Vertical asymmetries observed on lateral cephalo-metric images, with lack of superimposition of theocclusal plane and lower borders of the mandible

Frontal cephalometric images reveal changing den-tal and skeletal midlines, changing chin location,occlusal plane and gonial angle changes

Asymmetry development:

Rule out oral pathosis, such as infratemporal fossaor condylar tumor

Check for displaced or degenerative disc withchange in jaw position or morphology

Consider trauma as etiology of asymmetryIdentify likely patients for eventual orthognathic

surgeryMaintain maxillary midline coincident with the

face, and the mandibular midline reasonably coin-cident with underlying mandibular skeletal support

Coordinate arches to compensate for the asymme-try, or set up the arches for eventual jaw surgery

Consider dental compensations, but not beyondthe biologic limits; or decompensate the dentitionfor later surgery

Limit maxillary occlusal plane tipping by usingocclusal splints and/or a transpalatal arch or quad-helix appliance for anchorage support

By 8 years of age, 80% of adult head size hasdeveloped. Thus, the facial orthopedist and ortho-dontist have only 20% of remaining growth to influ-ence and utilize to augment the result othopedicallyand occlusally. At 13 years of age, 90% of head sizehas developed and thus only 10% remains. The dif-ference of this 20% at 8 years and 10% at 13 repre-sents twice the capability for the orthodontist to uti-lize. The clinician clearly wants to be treating thesefacial orthopedic problems by 7, 8, or 9 years ofage.12,2122

FRONTFRONTAL ANALAL ANALYSISSIMPLIFIEDYSISSIMPLIFIED

Treatment planning often requires at least twopatient evaluations with clinical interviews, photo-graphic and video imaging, dynamic and animatedassessments, cephalometry, and dental casts. Atleast two parameters should be used to confirm anypart of the asymmetry analysis. For instance, com-pare the external facial proportions with the mea-surements of the hard tissue cephalometry, or theradiographic incisors angulation measurements,

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compared with the study casts and the patient. Bothlinear and angular measurements are useful anddirective, but must be used rationally. Some patientshave values at the extremes of the normal range (Fig15). In such cases, de-emphasize the measure-ments in favor of other methods of prediction, suchas a template or sensible clinical judgments.3,23

Frontal (PA) radiographs or digital images are rec-ommended when the clinician is analyzing and pro-viding functional jaw orthopedics, orthognathicsurgery, asymmetry mechanics, TMJ disease man-agement, and/or treating jaw growth disorders. Aspart 1 of this article explained, two versions of theRicketts and Grummons frontal analyses are usedworldwide.3,24 The simplified version is the mostpractical and useful analysis (Fig 16). It permits theclinician to readily observe the midsagittal reference(MSR) line to compare right and left sides for dispro-portional relationships and specific location andextent of facial asymmetry.25 The complex frontalanalysis version is volumetric and intended for com-puterized processing and analysis.26,27 The MSR isthe skeletal midline reference line that compares theright and left sides of a patients face to detectskeletal and dental asymmetry. It is constructedfrom the anatomic christa galli (Cg), verticallythrough the anterior nasal spine (ANS), and

extended inferiorly beneath the chin (Me). From spe-cific skeletal and dental landmarks (Figs 17 and 18),perpendicular lines can be drawn laterally (trans-versely) to assess relationships between skeletaland dental references. Observing down the MSRline, the intersection of the right and left referencescan be easily compared where they intersect theMSR to see and measure asymmetries.2,3,24 Forexample, if the line from the right side antegonion(Ag) is 3 mm above the intersection of the left Agline, then the clinician knows that these points areasymmetric by 3 mm vertically.

There are several specific facial growth conceptsthat the clinician should keep in mind when usingthe frontal analyses:

1. Frontal growth. Using the behavior of the normalin width as reference and indicator.

2. Nasal width. The inside border of the nasal cavity(Nc) increases only 0.5 mm per year until ma-turity.

3. Maxillary width. The increase between J points is1 mm per year. When the measurement increasesby 6 mm in 24 months, the clinician can hopethat essentially 4 mm of that is orthopedic.

4. Mandibular width. Width increases 1.35 mm ayear at Ag points until maturity.

ba c

Fig 15 (a) Facial neuromotor deficit creates soft tissue asymmetry. (b) Mandibular developmental asymmetry. (c)Dentofacial compensations with asymmetry. (d) Transverse constriction irregularities. (e) Mandibular asymmetrywith maxillary compensations. (f) Tracing of same image.

e

d

f

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ba

Maxillary widthOcclusal planeFacial midlineupper dental to facialDental midlinesupper to lowerChin location

c

Fig 16 (a) Grummons frontal analy-sis. (b) Ricketts frontal analysis. (c)Frontal asymmetry indicators.

Fig 17 Anatomic renderings by Kunihiko Miyashita, DDS, in Contemporary CephalometricRadiography (Tokyo: Quintessence, 1986). Reprinted with permission.

1. Sagittal suture or longitudinal suture2. Maxillary sinus3. Orbital surface (frontal bone)4. Superior orbital fissure5. Superior border of petrosal part6. Foramen rotundum7. Zygomatic arch8. Mastoid process9. Occipital condyle

10. Nasal cavity11. Basion12. Mental foramen13. Mental spine14. Angle of mandible15. Anterior nasal spine16. Nasal septum17. Coronoid process18. Condylar head or condyle19. Orbital plate or lamina papyracea (ethmoid bone)20. Supraorbital margin21. Articular tubercle22. Styloid process23. Perpendicular plate (ethmoid bone)24. Coronal suture25. Crista galli26. Frontal sinus27. Frontozygomatic suture28. Odontoid process

Fig 18 Anatomic relationships at lateral facial region. Line drawing and legend by KunihikoMiyashita, DDS, in Contemporary Cephalometric Radiography (Tokyo: Quintessence, 1986).Reprinted with permission.

1. J point2. Malar (Ma)3. Maxillare (Mx)4. Maxillary first molar5. Zygomatic arch6. Inferior border of the skull base7. Second molar8. Lateral wall of the maxillary sinus9. Oblique line

10. Outer surface of the upper part of the maxillarysinus

11. Inferior border of the zygomatic bone12. Maxillary sinus13. Outer surface of the maxillary tuberosity

5. Mandibular molar width. Mandibular first perma-nent molars change little in width once erupted.Any measurable increases or decreases in inter-molar width is probably an induced change. Maxil-lary molars tend to be stable but are altered bytongue conditions and breathing changes. Usuallywidth changes are associated with treatmenteffects.

6. Mandibular first premolar width. Once the firstpremolars reach the plane of occlusion, littlewidth change can be expected.

7. Frontal growth and angular parameters. This fol-lows a triangular form from the Ag points andmeets at the nasion region. The vertex of a trian-gle for maxillary growth at J has an apex level withthe top of the orbits.

In the lateral perspective, the mandibular incisorposition receives priority; in the frontal, the maxillaryincisor dominates treatment decisions. Maxillo-mandibular analysis starts with the nasal width,then proceeds to the maxillae, particularly the maxil-lary incisors to facial midline, then to the maxillarymolars, and finally to the mandibular arch.1,15,17,28,29

ASSESSMENT OF THE CHINASSESSMENT OF THE CHIN

The chin is worthy of special consideration. Theneed for chin surgery may be difficult to predictbecause many procedures influence its position. Thevertical chin height and its prominence can be inde-

pendently modified surgically by reduction, lateralmovements, and/or augmentation. If in doubt, chinprofile changes should be examined preoperativelywith a lateral cephalometric and frontal predictiontracing. If still in doubt, educate the patient thatpostoperative correction may be indicated. Again, itis important to compare the dental midlines to eachother and with the midlines of the face, nose,philtrum, and the chin. Various mandibular discrep-ancies can be resolved with a rotation genioplastyafter the dental relationships have been corrected(Fig 19).

Derotation of an asymmetric chin is estheticallyimportant. If the asymmetry also includes a tilt in thetransverse occlusal plane, this can be simultane-ously leveled with osteotomies of both jaws (bimaxil-lary procedure) or asymmetric mandibular advance-ment with greater occlusal gap on one sidecompared to the other, so the lower jaw borders canbecome symmetric on both sides.

ESTHETIC CONCERNS OF ESTHETIC CONCERNS OF MAXILLARMAXILLARY ASYMMETRY ASYMMETRYY

The maxillary midline is one of the most sensitiveesthetic concerns of patients. Treatment decisionsfor asymmetries often revolve around the position ofthe maxillary incisors relative to the facial midline.Clinicians must determine what level of asymmetrythat orthodontic treatment alone can correct, andassess when and if surgery is needed to correct the

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Fig 19 (a) Mandibular body asymmetry disguised bygenioplasty procedure. (b) Chin centered despite ramaland body regional asymmetry. (c) Chin relocated to sym-metric position to disguise underlying mandibular asymme-try.

deformity. Soft tissues can compensate or camou-flage the underlying skeletal asymmetry and makethe decision more challenging. According toKokich,30 a maxillary midline deviation of 4 mm fromthe facial midline is needed for the general dentistor layperson to recognize the defect, while Grum-mons found that patients could perceive maxillarydental to facial midline variations once they reachedonly 2 mm.2,12 The patient can ultimately decidewhether to pursue surgery to correct the midlinedeviation. Canting or tilting of the maxillary anteriorteeth can occur when attempting to move the maxil-lary midline. Therefore, bodily movement and teethuprightness are important in midline correction.

TRANSVERSE AND OCCLUSALTRANSVERSE AND OCCLUSALPLANEPLANE

Clinical examination and study casts will indicatewhether orthodontic treatment or segmental surgicalcorrection is required to coordinate the dentalarches. Avoid tipping of molars to buccal excesswhen orthodontically expanding the maxillary arch,since molars will relapse back to physiologic axialinclination. Nongrowing patients should undergoexpandsion with surgical assistance. Whenever thereis a surgical alteration in the maxillary occlusal plane,a mandibular osteotomy is typically required to matchit, or at least other movements with differential poste-rior teeth eruption to the new postoperative occlusalplane. Identify the positive attributes of a patientssmile and protect those pleasing characteristics. Theresponsibility of the orthodontist includes under-standing growth and development in dentoskeletalterms, and also soft tissue growth, maturation, andaging because of individualized dynamics.

The transverse cant of the maxillary occlusalplane can be due to differential dental eruption (Fig20). Display of the anterior teeth can be modifiedorthodontically, surgically, or with cosmetic periodon-tics. Skeletal asymmetry of the mandible will resultin a compensatory cant to the maxilla, often requir-ing orthognathic correction. The oblique view of thesmile reveals characteristics of the smile not obtain-able on the frontal view and certainly not obtainablethrough any cephalometric analysis. The palatalplane may be canted anteriorly or posteriorly. In themost desirable orientation, the occlusal plane is con-sonant with the curvature of the lower lip on smile.Modification of the occlusal plane in preadolescentscan be accomplished with growth modification appli-ances such as vertical control functional appliances,the differential Herbst appliance, and high-pull head-gear. In late adolescent and adult patients, surgical

modification of the maxillary occlusal plane is oftenindicated. Clockwise occlusal plane rotation by max-illary or double-jaw surgery may harmonize the posi-tions of the maxillary incisal edges with the lips.23

TURBOSTURBOS

Turbos or bonded resin adhesives to the occlusalsurfaces help to establish a new and improvedmandibular reference position. While these turbosare in place on primary molars, the permanent firstmolars can erupt several millimeters more. Thus, amore optimal vertical dimension with leveled andsymmetric functional occlusal plane can be estab-lished. With this, the TMJs become postured opti-mally (decompressed), airway and head posture arehelped, and the incisors can clear during function.Unilateral bonding can be at a different height thanthe contralateral side, so that asymmetric posterioreruption can be encouraged and guided. Thisimproves occlusal plane symmetry.

ASYMMETRIC PROTRACTIONASYMMETRIC PROTRACTIONFFACEMASK THERAPYACEMASK THERAPY

The Grummons protraction facemask (Great LakesOrthodontics, Tonawanda, NY, USA) is effective in influ-encing midfacial hypoplasia and maxillary Class III defi-ciency without compression on the chin and unfavor-able TMJ overloading. It facilitates anterior movementof the maxillary skeletal complex and/or maxillary andmandibular teeth (functional jaw orthopedics). Oneside can be protracted more than the opposite side;hence asymmetric forward and inferior movements.The earlier the treatment, the more the face adapts tothe concept and responds to the therapy. The later thetreatment, the more the treatment plan must adapt tothe face.21 Movements can be greater on one sidethan the other, which alters the maxillary midline andocclusal plane toward the treatment objectives, withbetter facial and dental symmetry.

MAXILLARMAXILLARY TRANSVERSE Y TRANSVERSE APPLIANCE THERAPYAPPLIANCE THERAPY

A common clinical situation is a child with an appar-ent unilateral crossbite, but when the mandible ispositioned in centric relation, the crossbite is actu-ally bilateral. Long-term, those individuals with a uni-lateral posterior crossbite with a CR-CO shift havebeen shown to have a higher incidence of temporo-mandibular disorders.4,31 Assessment of dental arch

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asymmetry in the mixed dentition may be useful inexploring dysmorphogenesis.32 Transverse intra-archasymmetries exceed AP asymmetries in magnitudeand prevalence. In addition, individuals with obstruc-tive airway conditions have abnormally high asym-metry values. Dental arch asymmetry in childrenwith large overjets is evident 30% of the time, withtransverse asymmetries of 2 mm or more at themaxillary first permanent molars.

A maxillary transverse hypoplasia results in narrowposterior segment, with a constricted and linguallycompensated lower curve of Wilson and a constrictedarch form. When one side of the maxillary component

is more narrow than the other, asymmetric lowercompensation exists, reflecting opposing arch irregu-larities. The side of greater constriction is the side ofgreater asymmetry, with the maxillary arch serving asthe template for the mandibular arch.12,21 Oftenasymmetric crowding in the mandibular arch mirrorsthe asymmetric skeletal problem in the maxillaryarch. As the maxillary arch differentially expands, themandibular arch can unlock and become trans-versely uprighted and symmetrically aligned.33,34 Asmandibular dental compensations are reversed, themandibular posterior compressed arch is buccallyuprighted to normalize the curve of Wilson. Care is

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b ca

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Fig 20 Maxillary vertical asymmetry.(a) Unilateral nonreducing TMJmeniscus and advanced osteoarthro-sis caused mandibular asymmetry onthe short side. (b) Occlusal planetipped as a compensation to mandi-bular asymmetry. (c) Occlusal planeand smile made level with symmetricfacial components after maxillary sur-gical, orthodontic, and periodontaltherapies. Frontal imaging at (d) pre-treatment and (e) posttreatment, and(f) frontal summary analysis. Thepatient had a Class II malocclusion.(g) Asymmetric smile plane. (h)Short-side Class II problems. (i) Opti-mized occlusal correction. (j) Differen-tial posterior tooth eruptions to levelthe occlusal plane.

necessary to avoid expansion beyond the transverseguidelines, as described by Ricketts1 and Grummons2

for each facial pattern (wider in brachyfacial patients,less wide in mesofacial, and tapered for dolichofacialpatients).3 The envelope of stability determines thetransverse parameter of correction. Mandibular alveo-lar widening and favorable alveolar orthopedic remod-eling occur when an expansion appliance is used inthe mandibular arch while primary molars/caninesare present. Asymmetric mandibular arch wideningcan be achieved by placing the expansion screw atthe corner of the arch, rather than at the midline.4

MANDIBULAR ARCH AS MANDIBULAR ARCH AS THE TTHE TARGET ARCHARGET ARCH

The current logic is mandibular arch management asthe target arch, with orthopedic emphasis (skeletal)to improve jaw proportions, conditions, and relation-ships. Treatment planning and limitations lie withthe restrictions of the mandibular arch. Angles clas-sification was based on the maxillary molars. How-ever, science has proven that the greatest clinicalrestrictions lie in the mandibular alveolus and themandibular dental arch, particularly in the mandibu-lar transverse dimension and its treatment. Whilethe maxillary arch can be significantly widened tocorrect transverse hypoplasia, the final width deter-minant is the mandibular arch, with which the maxil-lary arch must coordinatemuch like fitting the lidon a box. The transverse dimension can be altered(orthopedically if early; later by distraction osteogen-esis and orthognathic surgery) with stable results.Narrow or transverse restrictions of the maxillae arecompensated by narrower mandibular posteriorarches or crossbites. Often, one side is more narrowthan the other, so maxillary and mandibular asym-metric arch width and lingual tooth angulations areobserved. Differential widening and transverseuprighting during treatment must also be adminis-tered. Therefore, in planning mandibular molar posi-tions, the changes to be made in the maxillary widthare influenced by the mandibular posterior widthguidelines. A lingually inclined mandibular posteriorarch form can be asymmetric from one side to theother (see Figs 5 and 6).

MODE OF ACTIONMODE OF ACTIONBONE PHYSIOLOGYBONE PHYSIOLOGY

Mandibular dentoalveolar expansion is usuallydesired in response to maxillary orthopedic expan-sion. Arch development while posterior primary

molars are still in place produces significant alveolardevelopment, with growth and favorable remodeling.During the mixed dentition stages, development ofthe intermolar and interpremolar widths (rather thanarch reduction by extraction therapy) is favored tounlock mandibular posture for optimal AP growthand development. Treatment to develop the maxil-lary width permits the mandibular arch to undergotransverse uprighting (lateral decompensation) whileuprighting the mandibular posterior teeth trans-versely and aligning roots underneath the crownswithin the periodontal support. As the maxillary archwidth increases, more anterior mandibular posturingand placement can occur.2,4,35,36

As the mandibular arch is widened and reshaped,the incisors can actually become uprighted (ratherthan flared) and optimally uprighted within the alveo-lar support. Significant changes in 3 dimensions canbe made in the midface, particularly if started early.If delayed, they must be surgically assisted or cor-rected later, or the patient is left with impairmentsand compromises. Obtaining skeletal congruity is afirst priority; otherwise, compensations abound. Ona practical basis, the greatest transverse skeletaltreatment potential lies in the maxillary arch. Thereexists the ability to: (1) affect the palatal suture; (2)affect other midfacial sutures; (3) change function;and (4) modify the maxillary alveolar process.

Untreated Class II cases have apical base defi-ciencies that can worsen over time. These can varyfrom right to left sides, which results in lower facialthird regional asymmetry. Nice orthopedic and ortho-dontic changes can predictably occur with appli-ances that require little compliance from patients.With facial and dentoalveolar symmetry, estheticand functional occlusal benefits become apparent inthe results. The transverse perspective deservesgreat appreciation and attention with todays 3-dimensional treatments and esthetic emphasis.

MANDIBULAR ASYMMETRMANDIBULAR ASYMMETRY Y

The asymmetric mandibular short side characteristi-cally has Class II skeletal and dental relationships.The midline is typically off-center and toward the defi-cient side. The occlusion is usually Class II on theshort side, with end-to-end buccal segments as atreatment limitation in the final result. The skilledclinician might equilibrate or provide coronoplasty, asneeded, for an improved final functional result.Mandibular canines are often asymmetric in thearch, and the occlusal plane is usually higher on theshort side. There are fewer masticatory muscle fiberswith less cross-sectional area on the deficient side.

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Asymmetric mandibular morphology in Class IIIcases, unilateral condylar remodeling, or TMJ degen-erative changes resulting in Class II changes on theaffected side, and traumatic cases with Class II mal-occlusion on the affected side with anterior openbite, can also occur.

Asymmetric extractions are often necessary tocamouflage the underlying skeletal Class II or IIIproblems. Surgical intervention for maxillomandibu-lar dysplasia is often indicated and beneficial. Thisresults in more optimal mandibular and dental pro-portions, stability, and symmetry for best patientbenefits. Functional jaw orthopedics or growth modi-fication should be applied early and differentially,with the short side advancing more than the con-tralateral side. This results in optimal midline place-ment and 3-dimensional correction. In functional jaworthopedic therapy, the astute and perceptive clini-cian will differentially distract and elongate the shortside, so the mandibular border, occlusal plane, andmidlines become more symmetric. Space within thearches (arch length) can be gained by midsagittaljaw development orthopedics with lateral widthincreases and from differential Herbst therapygrowth modification benefits (Fig 21).2,35

Mandibular elongation and hyperplasia

It is important to distinguish between mandibularasymmetry due to unilateral elongation and hyperpla-sia, since the cessation of growth is different. Elonga-

tion involves ongoing growth of the mandible, withexcessive length of the body and/or condyle alongnormal growth lines resulting in a more obtuse gonialangle. Horizontal elongation results in a superimposi-tion of the occlusal planes and the lower borders ofthe mandible, and it can affect the opposite side.

With vertical elongation, there need be no changein the lower midline nor deviation to the oppositeside. A unilateral open bite can occur in patientswith elongation in the condylar process. This mayalso occur in patients treated excessively with aNance or fixed transpalatal arch with unilateral openbite because compensatory vertical eruption of themolars cannot occur due to prolonged molar anchor-age. Elongation tends to stop when growth stops.

Horizontal and vertical components can be com-bined. With hyperplasia, there is increased bulk ofbone that results in a more acute gonial angle. Thereis also increased distance between the apices of theteeth and the lower border of the mandible on oneside. These affect superimposition of the lower bor-ders of the mandible on cephalograms.1,20

TMJ AND MASTICATMJ AND MASTICATORTORY Y DYSFUNCTIONAL ISSUESDYSFUNCTIONAL ISSUES

It is clear that many patients with dentofacial defor-mities have coexisting TMJ disorders.1 Age, gender,dental wear, unilateral posterior tooth contact in theretruded position, and posterior crossbite correlatedwith TMJ clicking. Jaw movement deflection and

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b ca

d

e

f

Fig 21 (a) Class II mandibular skeletal deficiency. (b) Symmetric maxillary occlusal plane. (c) Class II, subdivision 1malocclusion. (d) Asymmetric mandibular casts confirm asymmetric Class II relationships. (e) Mandibular postureoptimized and overcorrected. (f) Mandibular growth modification (asymmetric Herbst therapy) yields symmetric andoptimized Class I outcome.

asymmetric occlusal sl ide relate to temporo-mandibular dysfunction (TMD), mandibular asymme-try, and transverse discrepancy. In children, therecan be a relationship between TMD and certainocclusal factors, as well as between TMD and poorposture. In a primary dentition group, the TMD signsof highest incidence were deviation during opening(12.5%), clicking (50%), and posterior condylar dis-placement (75.5%). These three signs significantlycorrelate with occlusal factors such as frontal openbite, deviation of soft tissue, midline asymmetry,deep overbite, large overjet, crossbite, and bruxism.TMJ articular surface degenerative and/or remodel-ing changes occur with resultant mandibular asym-metry to varying degrees, depending upon the patho-sis. Functional shifts in older patients should betreated with deprogramming splints to achieve amore reproducible mandibular reference position,and then be reevaluated and treated, using articu-lated casts to evaluate the dental and skeletal posi-tions. Images should be retaken in centric relation orpostural position, so reliable treatment decisionscan be made. An individual may appear symmetricin habitual occlusion and asymmetric after depro-gramming and stabilization orthotic therapy.

Loss of vertical height of the mandibular ramusmay cause hypercontacts of posterior teeth on theaffected side. Progressive loss of vertical ramal heightusually occurs. A posterior open bite relationship sub-sequent to an increase of mandibular ramus lengthmay induce loss of posterior teeth contacts on theaffected side. If progressive, this may displace themandible contralaterally with a crossbite or asymmet-ric relationship. The mechanism of TMJ articular carti-lage degeneration is primarily microtrauma (ie, para-function) with chronic joint overloading common indistress-related repetitive bruxism. Macrotrauma,caused by a direct blow, can also precipitate progres-sive chondromalacia or softening of articular cartilage.Without favorable remodeling, breakdown occurs, witheventual asymmetric anatomic parts (Figs 22 and 23).When mandibular growth is disturbed on the fracturedcondylar side, a mandibular deviation and maxillarycanting to the affected side results (Figs 23 to 25). Fol-lowing the completion of growth, the asymmetries canbe corrected by combined orthodontic-surgical treat-ment. Facial asymmetry is common subsequent toearly condylar fractures.4,37

Mandibular asymmetry secondary toTMJ and/or mandibular dysfunction

When relapses are encountered, an understanding ofthe biology of the occlusion is employed to explain

the reasons for such failures. The underlying causesneed investigation from a biologic viewpoint. Home-ostasis is the function of various parts and organs tomaintain the whole system in equilibrium. When thisis disturbed, disease ensues. Because the TMJ is nor-mally suspended and not part of the antigravity sys-tem, it usually is not subjected to heavy or prolongedmechanical loading. When normal loading pressureis present, it is of a gliding nature and is relativelyintermittent. When clenching of the jaws or continu-ous forces due to muscular imbalances compressthis joint over long duration, it becomes overloadedand disturbed. Displacements of the condyle anddisc occur and a new asymmetric equilibrium mustbe attained over time. A pathologic compression inthe joint occurs; destructive or unfavorable adaptivechanges ensue. When the conditions becomechronic, joint space is lost. The tissues, in an effort toreach homeostasis, reduce and modify and a newmuscular status evolves. Advanced resorption of thecondyle can be a part of the adaptive process. Softtissue changes precede hard tissue remodeling; thusthe disc remodels first (see Fig 20).4,38

Adaptation is adjustment to environmental condi-tions due to localized excessive remodeling; itresults in local irregularities of the articular joint tis-sues. Remodeling is fundamental rebuilding of adultsoft and hard tissues; this maintains proportionsand relationships between form and function withinstructures throughout adult life. When growth is com-pleted, remodeling generally takes over. Favorableremodeling is physiology at work and is termedadaptation. Arthrosis (degenerative joint disease,

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Fig 22 Subcondylar fracture (AP and lateral views) ongrowing patient and subsequent progressive remodel-ing and repair to essentially normal conformation.

AP Lateral

osteoarthrosis) is primarily a noninflammatory jointdisease, characterized by a break in the continuity ofthe articular tissue with negative adaptation or sec-ondary changes in the underlying tissues. Degenera-tive joint disease is a disease of overloading, leadingto articular surface changes and structural asymme-try. At the minimum, todays orthodontist must beinformed regarding common TMD with a thoroughunderstanding of pain mechanisms and asymmetricstructural consequences.

In most cases of facial asymmetries, the mandibleis primarily affected and compensatory changes occurin the maxilla.39 The goal when treating mandibular

asymmetries is to achieve coincident skeletal symme-try. Intercept the problem early when there is a func-tional asymmetry in the mixed dentition by doing max-illary expansion and permit symmetric neutralmandibular positioning. In young people, functionalshifts can lead to disc derangements and asymmetricadaptations in the condylar fossa that may be progres-sive. A longstanding functional shift creates an envi-ronment in the TMJ for future asymmetric growth, evenif it is not genetically programmed. Condylar displace-ment occurs on the non-crossbite side, where themandible may be positioned anteriorly and inferiorly.30

Evidence of joint remodeling in cases with functional

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b ca

Fig 23 (a) Condylar process fractured into the infratemporal fossae. (b) Unfavorable medial condylar process dis-placement. (c) Gradual formation of condylar process 1 year later on adolescent patient. (d) After 18 months ofmandibular unilateral TMJ distraction appliance therapy. (e) The condylar process developed in 4 years, and facialsymmetry was restored. (f) Full range of TMJ motion established.

e fd

b

Fig 24 (a) Subcondylar fractureresulting in posttraumatic mandibularasymmetry; typical frontal tracing(Ricketts). (b) Asymmetric frontaltracing (Grummons) of same skull.

a

shifts exists in children with crossbites, while morecondylar asymmetry exists than in adults withuntreated crossbites where the condyles were sym-metric.31 A steeper condylar eminence develops onthe crossbite side and a shallower eminence on thenon-crossbite side, indicating fossa remodeling.40 Theshape of the fossa affects the growth of the mandible.An alteration in shape of the condylar path induceschanges in growth of the mandible. This asymmetricgrowth may continue even after correction of a cross-bite, if the amount of remodeling was significant.

SURGICAL CORRECTION OFSURGICAL CORRECTION OFFFACIAL ASYMMETRIESACIAL ASYMMETRIES

Mandibular elongation involving excessive verticalgrowth often requires surgery because of the unilat-eral open bite and necessary changes in theocclusal plane. A mild mandibular body elongation iseasier to intercept, with compensatory expansion ofthe maxilla. Hyperplasias and vertical elongationsusually require surgery, whereas body elongationhas the possibility of orthodontic correction.

Definitive evaluation of facial morphology (dolicho-cephalic facial type, divergent jaws pattern; brachy-cephalic facial type, convergent jaws pattern) andhard/soft tissue assessment includes cephalometrics

(lateral and frontal), articulated casts, 3-dimensionaldata and treatments, facial photographs (frontal,three-quarter, and lateral views), smile dynamics, andanimation studies. Functional matrix and neuromus-cular findings further influence decisions and treat-ments. The 4-D functional spatial model includesassessment of the transverse, AP, vertical propor-tions, range of motion, and time (maturation).

Frontal and lateral cephalometric analyses shouldinterrelate to facial photographs; frontal and lateralanimated smile observations become interrelated toinformation about the functional matrix (breathing,swallowing, muscles, range of motion, posture, andhabits). At the finish of therapy, clinicians mustlocate the dentition in the maxillomandibular staticneutral zone in all dimensions (Fig 26).

MANDIBULAR DISTRACTIONMANDIBULAR DISTRACTIONOSTEOGENESIS OSTEOGENESIS

For nongrowing patients, mandibular midline expan-sion for greater skeletal and dental arch widthimprovements is being accomplished successfullywith mandibular surgicallyassisted distraction osteo-genesis (DO).The distance from the molars to a refer-ence line of J-Ag at the level of the frontal occlusalplane can be modified in this way.41,42

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b ca

e fd

Fig 25 Mandibular border asymmetry. (a) Pretreatment mandibular asymmetry. (b) PA cephalogram. (c) Frontaltracing. (d) Posttreatment. (e) Posttreatment PA image. (f) Frontal symmetry and triangles.

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b ca

e fd

h ig

k lj

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Fig 26 (a to l facing page) Steps in analyzing and treatment planning maxillomandibular asymmetry from the frontalperspective. (a) Maxillomandibular skeletal asymmetry with dental compensations; baseline frontal asymmetryanalysis to establish frontal visualized treatment objectives (FVTO) steps. (b) Upper facial third landmarks. (c) Asym-metric maxillary component added to frontal tracing. (d) The maxillary component is moved to symmetric midlineand occlusal plane placement. (e) Overlay of asymmetric and symmetric maxillary components. (f) Mandibular asym-metric component. (g) Mandibular component relocated to symmetric midline placement. (h) Overlay of mandibularasymmetric and symmetric components. (i) Maxillary jaw leveled, mandibular jaw moved asymmetrically forwardand to midline, followed by mandibular posterior teeth erupted to leveled occlusal plane. (j) Maxillary and mandibularcomponents in symmetric placement as part of frontal visualized treatment goals (FVTG). (k) Asymmetric chin loca-tion and maxillary jaw still misaligned. (l) Symmetric chin placement as camouflage and maxillary componentremains asymmetric. (m) Maxillary component and chin made symmetric. (n) Both jaws remain asymmetric; chinrelocated to appear symmetric at chin midline. (o) Both jaws moved to level occlusal plane and to correct midlinesand chin. (p) FVTG reveals maxillomandibular symmetry with chin location undecided (may be acceptable or mayneed mentoplasty). (q) Maxillary jaw leveled while mandibular jaw and chin remain asymmetric. (r) Mandibular jawbody remains asymmetric though chin is moved to symmetric midline position, which disguises the underlying max-illomandibular issues. (s) Both jaws and chin optimally symmetric. (t) Superimpositions of maxillomandibular andchin treatment changes.

n om

q rp

s t

CRANIOCERCRANIOCERVICAL ISSUESVICAL ISSUES

The relationships of the cervical vertebrae can alertthe clinician to possible abnormalities regardinghead rotation or side-bend in the PA radiograph withthe mouth wide open.4,36 Cervical (C2) and odontoidprocess regions are visible and able to be evaluatedin this view (Fig 27).

SUMMARSUMMARYY

The orthodontist must apply the optimal treatmentapproach for the specific needs and unique asym-metric circumstances of each individual patient,rather than expecting and/or requiring that eachpatient fit a clinician-preferred treatment approach.Applying such a philosophy and belief systeminsures that clinicians will be more exacting, and thepatient will benefit immeasurably from symmetricresults with specific 3-dimensional lifelong advan-tages. Orthodontists are well-trained regarding sagit-tal, AP, and vertical discrepancies, but currently lessemphasis is placed on the transverse and frontaldimensions. Patients view themselves and shapeself-perceptions from the frontal perspective, so thisview must have greater significance. Early orthope-dic intervention and nonextraction approaches pro-vide for best functional occlusion, symmetric andproportional structural stability, with a final symmet-ric, esthetic smile and optimized lip support. Mansmind, once stretched by new ideas, can neverremain the same.

ACKNOWLEDGMENTSACKNOWLEDGMENTS

The families of these authors remain consistently supportive. Theeditorial guidance from Dr Thomas Graber is exceptional. TeriAnyan and Cari Wharton of my capable staff also deserve signifi-cant acknowledgment and gratitude.

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