wjo_5_1_Kondo_2

9MMorphologic abnormality of the neck muscles,particularly the sternocleidomastoid (SCM) andupper trapezius muscles, and asymmetric activitiesof the masseter, temporalis, and other masticatorymuscles are often found in patients with occlusalabnormality with lateral deviation of the mandible,

severely asymmetric posterior vertical occlusaldimension, and marked morphologic abnormality ofthe condyle and ramus.1,2 Characteristics commonto these patients include narrowing or loss of theatlanto-occipital joint space and morphologic abnor-mality of the cervical spine, such as C2-C3 fusion.2

Another characteristic is dysfunction of the atlanto-occipital and atlantoaxial joints, with the dens pro-truding 6 mm or more above the McGregor line3 intothe cranial base, causing the cranium to tilt to theside with SCM muscle contraction and rotate to theside with upper trapezius contraction. The result islimited upper neck movement, particularly head

Features and Treatment of Skeletal Class III Malocclusion with Severe Lateral Mandibular Shift and Asymmetric Vertical Dimension

Etsuko Kondo, DDS, DDSc1

Aim: To highlight the effectiveness of orthodontic treatment and bilateral equalization of thevertical occlusal dimension, along with the correction of asymmetric cervical and mastica-tory muscle activities in patients with Class III malocclusion with lateral deviation of themandible and severely asymmetric condyle and ramus. Methods: Two normally growingand one nongrowing Japanese patients with severe lateral deviation of the mandible, asym-metric vertical occlusal dimension, and severely asymmetric temporomandibular joints arediscussed. In addition to orthodontic treatment, all patients received physiotherapy of thecervical muscles and gum-chewing training for elimination of the masticatory muscularimbalance. Patients also had postural training during treatment. All patients were treatedwith a bite plate to equalize the bilateral posterior vertical dimension, followed by full multi-bracketed treatment to establish a stable form of occlusion and to improve facial esthetics.Results: This interdisciplinary treatment approach resulted in normalization of stomatog-nathic function, elimination of temporomandibular joint dysfunction symptoms, andimprovement of facial appearance and posture. In growing patients, the significantresponse of the fossa, condyle, and ramus on the affected side during and after occlusalcorrection contributed to the improvement of cervical muscle activity. In contrast, lessimprovement was observed in the growing patient who did not receive physiotherapy ofthe neck muscles, postural training, or masticatory habit training during the posttreatmentperiod. The nongrowing patient showed little morphologic improvement of the cervicalspine, condyle, and fossa during treatment and after retention, even with physiotherapy ofthe neck muscles and attention to posture and masticatory habits. Conclusion: Based onthese results, early occlusal improvement, combined with physiotherapy to achieve muscu-lar balance of the neck and masticatory muscles, was found to be effective. It is importantto assess the morphology and function of the neck muscles and cervical spine prior toocclusal therapy in patients with an asymmetric vertical dimension, lateral deviation of themandible, and asymmetric temporomandibular joint structures. Therapy should correlateorthopedic and surgical patient management as needed. World J Orthod 2004;5:924.

1Private Practice of Orthodontics, Tokyo, Japan.

CORRESPONDENCEDr Etsuko Kondo, 2-3-4 Tamagawadenenchofu, Setagaya-ku,Tokyo, Japan 158-0085. E-mail: [email protected]

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Kondo WORLD JOURNAL OF ORTHODONTICS

rotation. Various modalities, such as physiotherapyof the neck muscles and gum-chewing training forelimination of masticatory muscle imbalance, shouldbe employed, along with tooth positioner wear forharmonization of occlusion and muscle activity. Thepatient is instructed to pay due attention to postureand gait during daily activities and to do exercisesfor postural balance. As a result, morphologic abnor-mality of the cervical spine and muscles can beimproved, with downward movement of the dens,resulting in a normal head posture and smooth headrotation. Masticatory muscle activities became sym-metric, accompanied by marked morphofunctionalimprovement of the neck muscles, cervical spine,temporomandibular joints (TMJ). In contrast, lessimprovement has been observed in growing patientswith a strongly contracted upper trapezius muscle,without physiotherapy of the neck muscles or atten-tion to posture and unilateral masticatory habitsafter treatment. Asymmetry of the neck musclesincreased over time, leading to the recurrence ofmorphologic abnormality of the cervical spine,condyle, and ramus. The distance from the apex ofthe dens to the McGregor line increased again to 6mm or more, accompanied by increased limitation ofhead rotation and progression of morphologic abnor-mality of the ramus, with occasional TMJ symptoms.Thus, occlusal correction combined with physiother-apy of the neck muscles and attention to postureand masticatory habits significantly contributed tothe morphologic improvement of the condyles andramus, and reduced the postretention incidence ofTMJ symptoms. Growing patients who receivedocclusal correction and physiotherapy of the neckbefore completion of the permanent dentition bene-fited far more from the treatment than did nongrow-ing patients. Three Japanese patients, two growingand one nongrowing, are presented to illustrate thedifferences in treatment outcome.

CASE 1CASE 1

This growing patient was a Japanese female, 9 years11 months of age, with a skeletal Class III malocclu-sion, with severe lateral deviation of mandible to theleft and severely asymmetric posterior verticaldimension between right and left sides. She hadpoor head posture due to mild contraction of theright SCM and left upper trapezius muscles. She alsohad a left unilateral masticatory habit. The primarycomplaints were anterior crossbite and temporo-mandibular dysfunction (TMD) in the left joint. Thepatient received physiotherapy twice a month duringtreatment, and was observed for 7 years 8 months.

Diagnosis

Facial photographs (Fig 1a) showed that the profilewas concave with a short upper lip, a favorablenasolabial angle at 100 degrees, and a prominentchin. The mandible deviated to the left as the headtilted to the right side, with SCM muscle contraction,and rotated to the left, with upper trapezius musclecontraction, creating poor head posture and facialasymmetry. The range of active head movement waslimited slightly on the right.

Intraoral photographs (Fig 1b) and dental casts(Fig 1d) showed that the patient was in the early per-manent dentition stage. The molars and canine onboth sides were full Class III with a mandibular lat-eral deviation of 7.0 mm to the left and significantlack of posterior vertical occlusal height on the left,unilateral masticatory habit side. Clicking was notedat 33.0 mm on wide opening in the right joint, with amandibular shift to the left.

The panoral radiograph (Fig 1c) showed a roundcondyle and a short ramus on the mandibular leftside, with lower posterior vertical dimension and acontracted upper trapezius muscle. All permanentteeth were present.

The lateral cephalogram at pretreatment (Fig 2b)showed that the cervical spine was a lordosis type,with narrow intervertebral space between C2, C3,and C4, causing a protrusion of 5.0 mm on the supe-rior edge of dens above the McGregor line. Thiscaused the restriction of the atlantoaxial joint, result-ing in poor head posture. The apices of the maxillaryanterior and posterior teeth were in close proximityto the nasal floor, suggesting a severe lack of maxil-lary vertical alveolar height in the anterior and poste-rior regions. The skeletal Class III malocclusion wasdue to a retruded maxilla and a prognathic mandible(SNA, 75.0 degrees; SNB, 83.0 degrees; ANB, 8.0degrees). The maxillary and mandibular incisors hada favorable inclination (U1 to SN, 107.0 degrees; L1to DC-L1i line, 85.0 degrees). The functional occlusalplane to AB plane angle was 70.0 degrees, with aresulting Wits appraisal of 14.0 mm (Fig 3).

The anteroposterior (AP) cephalogram at pretreat-ment (Fig 2a) showed the cranium and the dens ofC2 tilted to the right side. The affected left ramuswas shorter, resulting in facial asymmetry. Thiscaused the occlusal plane to tip in a direction oppo-site to the tilt of the cranium.

The axial cephalogram (see Fig 2a) showed thatthe contraction of the upper left trapezius muscleinduced hypertrophy of the temporal and occipitalbone. This may have caused a narrowing of the inter-vertebral spaces between C2, C3, and C4, withexcessive protrusion of 5.0 mm of the apex of dens

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VOLUME 5, NUMBER 1, 2004 Kondo

Pretreatment (9yY11M) Posttreatment (12Y 7M) 5 years 6 months posttreatment (18Y 1 M)

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Fig 1 Case 1. Comparison of (a) facial photographs, (b) intraoral photographs, (c) panoramic radiographs, and (d)dental cast photographs from pretreatment to 5 years 6 months posttreatment.

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above the McGregor line, resulting in dysfunction ofthe atlantoaxial joint. There was limited head rota-tion and asymmetric masticatory muscle activity andcondylar movement, causing asymmetric growth ofthe condyle, ramus, and other joint structures in thisgrowing patient.

The joint radiographs (see WJO web edition, atwww.quintpub.com) showed a difference in size andshape between right and left condyle and ramus,with a more round condyle and short ramus on theleft side. The left condyle was located slightly moreposteriorly in the fossa.

Electromyographically (Fig 2c), the left temporalismuscle showed hyperactivity in rest position after 30minutes of myopulsing, causing asymmetric mastica-tory muscle activities between the right and leftsides.

These findings implicated the imbalance of neckmuscle activity, and the unilateral masticatory habitgreatly affected the formation of the left joint areaand enhanced mandibular dysfunction. This resultedin underdevelopment of the mandible on the leftside, characterized by morphologic abnormalities ofthe ramus and condyle, causing asymmetric growth


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Fig 2 Case 1. Comparison of (a) AP and (b) lateral cephalograms and (c) EMG findings from pretreatment to 5years 6 months posttreatment.

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Fig 3 Case 1. Tracings of cephalograms and composite tracings from pretreatment to 5 years 6 months posttreat-ment (on S-N at sella, ANS-PNS at anterior nasal spine, Go-Me at gonion).

of the mandible and asymmetric vertical dimensionbetween the right and left sides, causing severemandibular lateral deviation to the left.

Treatment

If the case were to be treated by four premolarextraction, the mandibular incisors would be lin-gually inclined and the nasolabial angle would beincreased, resulting in a dished face with a promi-nent chin and a narrow tongue space, causing possi-ble airway problems.

The decision was made to treat the case bynonextraction using the Alexander technique, with abite-opening plate and Class III elastics, to eliminatethe asymmetric vertical dimension between the rightand left sides. The patient concurrently receivedphysiotherapy for neck and masticatory muscles,with vigorous gum chewing. The patient wasinstructed to pay attention to posture during dailyactivities.

Course of treatment

Orthodontic treatment was started (at 10 years ofage) with a bite-opening plate in the mandibular archand an Alexander appliance in the maxillary arch.Physiotherapy of the neck muscles was instituted.

Two months after the start of treatment (10 years2 months of age), the anterior crossbite was almosteliminated and TMD symptoms had disappeared.The Alexander appliance was then placed in themandibular arch and vertical elastics were used inthe posterior area.

Thirty-one months after the start of treatment (12years 7 months of age), the AP skeletal and occlusaldisharmonies had been corrected, with an equalizedvertical dimension. A dramatic occlusal improve-ment had been obtained and was maintained duringthe 5 years 6 months posttreatment retentionperiod. Tongue and masticatory muscle myotherapycontinued to the present, and a retainer and a toothpositioner were used for 2 years posttreatment.

Treatment results

The facial photographs at 5 years 6 months posttreat-ment (see Fig 1a) showed favorable improvement ofthe head and cervical posture. The SCM and uppertrapezius muscles were restored to symmetry and theleft unilateral masticatory habit was eliminated. Theactive head movement was normalized in all directions.

Intraoral photographs and dental casts (see Figs2b and 2d) showed the stable and functional occlu-sion. The equalized bilateral posterior vertical dimen-sion was established with nonextraction and main-tained during 5 years 6 months posttreatment. Theoverjet and overbite were normal at 3.0 mm. Thepanoral radiograph and joint radiographs at 5 years6 months posttreatment (see Figs 1c and 2c)showed that all roots were parallel, with no abnor-mality. The malformed condyle and ramus on the leftside were markedly improved. Both condyles were incomparable positions in the articular fossae, both onocclusion and on wide opening of 42.0 mm, indicat-ing that normal jaw function had been attained by 5years 4 months posttreatment. There has been norecurrence of clicking or other TMD sequelae after 5years 4 months posttreatment.

The lateral cephalogram at 5 years 6 monthsposttreatment (see Fig 2b) showed a normal cervicalspine, lordosis type, with widened intervertebralspaces between C2, C3, and C4, resulting in reduc-tion of the apex of the dens to the McGregor linefrom 5.0 mm to a normal 2.0 mm. As a result, nor-mal atlantoaxial joint movement, and other cervicaljoint movements and active head movements, weremaintained for more than 5 years.

The composite tracing (see Fig 3) showed a favor-able maxillary and mandibular response. The ANBangle increased from 8.0 degrees to 1.5 degrees.The maxillary and mandibular incisors had a favor-able inclination, with an increased maxillary alveolarvertical height of 4 mm. The functional occlusalplane moved down posteriorly 12 degrees. The toothaxis of maxillary and mandibular posterior teeth andthe AB plane were perpendicular to the functionalocclusal plane. The upper lip height increased 5.0mm and the nasolabial angle was 100 degrees, cre-ating an attractive and harmonious lip profile.

The composite tracing superimposed on themandibular area at gonion (see Fig 3) showedincreased ramus and alveolar height of the posteriorarea on the affected side. The left side was largerthan the right (nonaffected) side. The resultingramus and posterior vertical height became almostequal at 5 years 6 months posttreatment, creating asymmetric face.

The AP cephalograms at 5 years 6 months post-treatment (see Fig 2a) confirmed that the tilt of thecranium and occlusal plane were eliminated. Bothrami were almost the same height, creating a sym-metric frontal view.

The electromyocardiogram (EMG) record at 5years posttreatment (see Fig 2c) showed symmetricmasticatory muscle activity. Optimal masticatorymuscle activity had been attained, creating a well-

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balanced face. The skeletal Class III case, withsevere lateral deviation and deficient posterior verti-cal occlusal dimension, was successfully treated andmaintained more than 5 years posttreatment.

CASE 2CASE 2

This growing Japanese female, 10 years 11 monthsof age, had a Class III malocclusion with severe lat-eral deviation of the mandible to the left, severeasymmetric vertical occlusal dimensions betweenthe right and left sides, and severely deformedcondyle and ramus on the left. She had poor headposture, due to contraction of the left upper trapez-ius and right SCM muscles. She also had a left uni-lateral masticatory habit. The patients primary com-plaints were lateral deviation of the mandible andTMD in the left joint. The patient received physiother-apy for the neck muscles during orthodontic treat-ment, but she did not receive physiotherapy post-treatment. The patient was observed for 8 years 11months posttreatment.

Diagnosis

The facial photographs (Fig 4a) showed that the orig-inal profile was concave, with a short upper lip. Themandible deviated to the left, as the head tilted tothe right side with SCM muscle contraction. Thehead rotated to the left with upper trapezius musclecontraction, and a shortened left masseter muscle,creating markedly poor head posture and facialasymmetry. The range of active head movement waslimited on the right side.

Intraorally (Fig 4b), the patient was in the earlytransitional dentition stage and had a Class III molarrelationship on the right. The mandible deviated 8.0mm to the left on occlusion and the maxillary archwas constricted. The dental cast (Fig 4d) showed aseverely asymmetric vertical occlusal dimensionbetween the right and left sides, with a reduced ver-tical dimension on the left, unilateral masticatoryhabit side. Clicking was noted at 28.0 mm of wideopening in the right joint, with a mandibular shift tothe left.

The panoral radiograph (Fig 4c) showed a short,thick ramus and a malformed condyle on the left,deviated side during chewing. All permanent teethwere present.

The lateral cephalogram at pretreatment (Fig 5b)showed a straight cervical spine, with narrow inter-vertebral spaces between C2 and C3 and betweenthe occipital bone and C1, causing a protrusion of

6.0 mm of the superior edge of dens above theMcGregor line. This caused the restriction of theatlanto-occipital and atlantoaxial joints, resulting inpoor head posture. The apices of both the maxillaryand mandibular posterior teeth were in close proxim-ity to the nasal floor and the lower border of themandible, respectively, suggesting a severe lack ofalveolar height in both the anterior and posteriorregions. A prognathic mandible existed (SNA, 81.0degrees; SNB, 85.0 degrees; ANB, 4.0 degrees).The mandibular plane angle was low (SN-GoMe,28.0 degrees). The mandibular incisors wereprocumbent, with a short vertical position (L1 to DC-L1i, 84.0 degrees; L1 to GoMe, 105 degrees). Thefunctional occlusal plane to AB plane angle was 73degrees with a Wits appraisal of 13.0 mm (Fig 6).

The AP cephalogram (Fig 5a) showed the craniumand the dens of C2 severely tipped to the right. Theaffected left ramus was shorter, resulting in facialasymmetry. This caused the occlusal plane to tip ina direction opposite to the tilt of the cranium.

The axial cephalogram (Fig 5c) showed the effectsof strong contraction of the upper trapezius on theleft, which induced severe hypertrophy of the tempo-ral and occipital bones on the same side. It may alsohave caused a narrowing intervertebral spacebetween C2 and C3. The straightening of the cervi-cal spine has led to excessive protrusion into the cra-nial base of 6.0 mm of the apex of dens above theMcGregor line, causing dysfunction of the atlanto-occipital and atlantoaxial joints and limited headrotation. The resulting asymmetric masticatory mus-cle activity and condylar movement produced asym-metric growth of the condyle, ramus, and other jointstructures in this growing patient. Electromyographi-cally (Fig 5d), both of the left temporalis and mas-seter muscles were hypertonic.

These findings indicated that the imbalance ofneck muscle activity and the unilateral masticatoryhabit were affecting the formation of the left jointarea, inducing mandibular dysfunction. This resultedin underdevelopment of the mandible on the leftside, characterized by morphologic abnormalities oframus and condyles, causing asymmetric growth ofthe mandible and asymmetric vertical dimensionsbetween the right and left sides, producing severemandibular left lateral deviation.

Treatment

If the case was to be treated by four premolar extrac-tion, the profile would be a dished face with a promi-nent chin and narrow tongue space, causing prob-lems for the airway and disturbing nasal breathing.

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Fig 5 Case 2. Comparison of (a) AP cephalograms, (b) lateral cephalograms, (c) axial cephalograms, and (d) EMGfindings from pretreatment to 5 years 4 months posttreatment.


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Fig 6 Case 2. Tracings of cephalograms and composite tracings from pretreatment to 5 years 4 months posttreat-ment (on S-N at sella, ANS-PNS at anterior nasal spine, Go-Me at gonion).

Thus, a decision was made to treat the case bynonextraction, using a full bracket system with apalatal expansion lingual arch and bite-openingplate to eliminate the asymmetric vertical dimensionbetween the right and left sides. Treatment includedmuscle training by constant, vigorous gum chewingand instructions to pay due attention to posture dur-ing daily activities.

Course of treatment

Orthodontic treatment was started, when the patientwas 11 years of age, with full appliances and a biteplate. Physiotherapy of the neck muscles wasstarted. At 6 months after the start of treatment (11years 6 months of age), the maxillary arch wasexpanded and the anterior crossbite and the leftmandibular deviation were almost eliminated.Migraine, dizziness, tinnitus, and TMD symptomsdisappeared.

At 42 months after the start of treatment (14years 6 months of age), a stable occlusion, with anequalized vertical dimension, had been established.The retention period was 5 years 4 months. Tongueand masticatory muscle myotherapy has been con-tinued to the present. A retainer and a tooth posi-tioner were used for 2 years.

Treatment results

The posttreatment facial photographs (see Fig 4a)showed favorable improvement of the facial profileand head posture. However, imbalance of cervicaland masticatory functions recurred during posttreat-ment due to little morphologic improvement of thestrongly contracted upper trapezius muscle, whichremained even with physiotherapy of the neck mus-cles. The patient did not receive physiotherapy of theneck muscles after treatment. The left unilateralmasticatory habit and limited active head movementremained.

Intraoral photographs and the dental cast (seeFigs 4b and 4d) showed a well-seated posteriorocclusion and matched midline. A Class I canine andmolar relationship, normal overjet, and an overbiteof 3.0 mm were established at the end of activetreatment. However, the asymmetric posterior verti-cal dimension was not improved, even at 5 years 4months posttreatment, and there was recurrence ofthe mandibular deviation of 3.0 mm to the leftbecause of the remaining imbalance of cervical andmasticatory function, with a unilateral masticatoryhabit.

The panoral radiograph at 5 years 4 months post-treatment (see Fig 4c) showed that roots of both max-illary and mandibular posterior teeth on the right sidewere almost parallel, but the left posterior teeth weremesially inclined because of the existing unilateralmasticatory habit and the contracted upper trapeziusmuscle. However, the severely deformed condyle andramus on the left side were markedly improved andalmost symmetric between right and left sides at theend of posttreatment. The recurrence of the asym-metric condyle and ramus were observed at 5 years4 months posttreatment, however.

Posttreatment, the lateral cephalogram (see Fig5b) showed that the cervical spine changed from astraight type to normal lordosis type, with widenedintervertebral space and space between the occipi-tal bone and C1, resulting in a reduction of the apexof dens to the McGregor line from 6.0 mm to 4.0mm at the end of active treatment. However, thepatient experienced a renarrowing of the spacebetween the occipital bone and C1 (normal space,4.0 mm to 9.0 mm), resulting in the apex of the densto the McGregor line increasing again to 6.0 mm.This was accompanied by increased limitation ofhead rotation and progression of morphologic abnor-mality of the ramus and condyle on the left side.Occasional TMJ symptoms were experienced duringthe 5 years 4 months posttreatment period.

The composite tracing (Fig 6) showed that a favor-able maxillary and mandibular response wasobtained. As a result, the ANB angle increased from4.0 degrees to 2.5 degrees. The maxillary andmandibular incisors had a favorable inclination, withincreased maxillary alveolar vertical height of 4.0mm. The functional occlusal plane moved down pos-teriorly 7.0 degrees, so that both tooth axes of maxil-lary and mandibular posterior teeth and the ABplane were perpendicular to the functional occlusalplane, resulting in a stable occlusion, which wasmaintained for more than 5 years posttreatment.

The composite tracing on the mandibular plane atgonion (see Fig 6) shows the increase in ramus andalveolar height of the posterior area on the left,affected side was larger than on the non-affectedside during active treatment. However, during 5years 4 months posttreatment, the increase oframus height on the non-affected side (right) waslarger than the affected side (left). This causedrecurrence of the short ramus and reduced neckcondyle on the left.

The AP cephalogram at 5 years 4 months posttreat-ment (see Fig 5a) showed a much shorter facial heightand shorter ramus on the left. The occlusal plane tilt ina direction opposite to the tilt of the cranium becameworse in the 5 years 4 months posttreatment period.

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The axial cephalogram (see Fig 5c) revealed amarked difference in shape between left and rightsides in both the occipital and temporal bones,which became worse due to the strongly contractedleft upper trapezius during the 5 years 4 monthsposttreatment period.

The joint radiographs at 5 years 4 months post-treatment (see web edition) showed that the differ-ences in size and shape of the right and leftcondyles still remained. Both condyles were in com-parable positions in the fossae, both on occlusionand on wide opening at 42.0 mm, indicating thatnormal jaw function remained at 5 years 4 monthsposttreatment. Occasional clicking was noted onopening in the right joint, and there was a recur-rence of trismus pain during the 5 years 4 monthsafter treatment. Electromyographically, at 5 years 4months posttreatment, the left temporalis muscleremained hypertonic.

This growing patient had difficult problems,including a strongly contracted upper left trapeziusmuscle and a unilateral masticatory habit. The cor-rection of all these problems was difficult and couldnot be done by orthodontic treatment only, with nophysiotherapy of the cervical spine and muscles andno patient cooperation.

CASE 3CASE 3

This adult female patient was 34 years 9 months ofage, with a Class I malocclusion, mandibular devia-tion to the left, and a severely malformed condyle,ramus, and fossa on the same side. She had poorhead posture due to the morphologic abnormality ofthe cervical spine (fusion of occipital bone and C1,and fusion of C2 and C3) and contraction of theright SCM and hyperactivity of both the masseterand temporalis muscles on the left. The patient hadbeen orthodontically treated for Class III malocclu-sion, by four first premolars extraction, at 14 yearsof age. She suffered constantly from stiff shoulders,tinnitus, and migraine, and complained of occa-sional TMD symptoms of the left joint. The patientwas observed for 6 years 3 months.

Diagnosis

The facial photographs (Fig 7a) showed themandible severely deviated to the left as the headtilted to the right with right SCM muscle contraction.She had asymmetric masseter muscles, with ashortened left masseter muscle, creating severefacial asymmetry and poor head posture on frontal

view. The range of active head movement was lim-ited to the right side.

Intraoral photographs and the dental cast (Figs7b and 7d) showed the molars in Class I with anunmatched midline, deviated to the left by 3.0 mm,a posterior crossbite, an asymmetric posterior verti-cal dimension, and reduced vertical dimension onthe left. The maximum opening was 32.0 mm. Click-ing occurred early in the left joint on opening, withincreased mandibular shifting to the left.

The lateral cephalogram at pretreatment (Fig 8b)showed the cervical spine was a straight type, withnarrow intervertebral space, with fusion of occipitalbone and C1 and fusion of C2 and C3, causing a6.0-mm protrusion of the superior edge of densabove the McGregor line. These caused the restric-tion of the atlanto-occipital and atlantoaxial joints,causing a poor head posture and a tilted androtated cranium. There was a strong antegonialnotch with a shorter ramus on the left side, suggest-ing hyperactivity of the left masseter muscle.

The cephalometric analysis (Fig 9) revealed afavorable jaw relationship (SNA, 78.0 degrees; SNB,72.0 degrees; ANB, 6.0 degrees) and favorable incli-nation of the maxillary incisors and the mandibularincisors (U1 SN, 92.5 degrees; L1 to DC-L1i line,83.0 degrees).

The AP cephalogram (Fig 8a) showed the craniumand dens of C2 severely tilted to the right, and amuch shorter facial height and ramus on the left,causing the occlusal plane to tip in a direction oppo-site to the tilt of the cranium, resulting in severefacial asymmetry.

The panoral (Fig 7c) and joint radiographs (seeWJO web edition, at www.quintpub.com) showed atrophic condyle, shallow fossa, and a severely thin,short ramus on the left, with masseter musclehyperactivity. The left joint space was larger in habit-ual occlusion than the right joint. Deformity of theleft condyle and disc apparently diminished the self-seating capacity, making the disc susceptible toanterior displacement and causing left TMJ symp-toms. Electromyographically (Fig 8d), the left mas-seter and both temporalis muscles showed hyper-electric activities in rest position.

The axial cephalogram (Fig 8d, center) showedthat a contracted right SCM muscle induced cranialrotation and hypertrophy of the temporal bone onthe right side. This may have caused a straight cervi-cal spine and pushed the dens of the axis up intothe cranial face, causing excessive protrusion (6.0mm) of the dens of apex above the McGregor line,fusion of occipital bone and C1, fusion of C2 andC3, and dysfunction of the atlanto-occipital andatlantoaxial joints. As a result, there was limited

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Pretreatment (34Y 7M) Posttreatment (36Y 9M) 4 years 2 months posttreatment (40Y 1 M)

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head rotation, asymmetric masticatory muscle activ-ity, and abnormal condylar movement, causing atrophic condyle and a severely thin, short ramus onthe left.

Treatment

Treatment was aimed at functional improvement ofthe cervical and masticatory muscles through phys-iotherapy, correction of the jaw relationship by maxil-lary expansion, and unloading of the joints throughocclusal improvement, using full appliances and apalatal expander.

After 2 weeks of splint wear (34 years 7 monthsof age), the TMD symptoms disappeared. Placementof a palatal expander and a full edgewise appliancewas then done (34 years 9 months of age). Thepalatal expander was worn for 6 months.

At 14 months after the start of treatment (35 years9 months of age), the appliance was removed. A sta-ble occlusion was established. A tooth positioner andretainer were used for 2 years posttreatment.

The postretention period was 4 years 2 months.The occlusion remained stable and there were fewerTMD complaints, but occasional clicking remained.

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a

b

c

Fig 8 Case 3. Comparison of (a) AP cephalograms, (b) lateral cephalograms, and (c) EMG findings and axialcephalogram from pretreatment to 4 years 2 months posttreatment.

Treatment results

The facial photographs (see Fig 7a) showed that thetilted head and occlusal plane were not adequatelyimproved, even 4 years 2 months posttreatment. Asa result, the head movement showed limited flexionand rotation to the right.

Intraoral photographs and the dental cast (Figs7b and 7d) showed a stable occlusion; this wasmaintained for 4 years posttreatment. However, theposteriorly asymmetric vertical dimension remained.

The posttreatment lateral cephalogram (Fig 8b)showed a straight type of cervical spine, with fusionof occipital bone and C1 and fusion of C2 and C3remaining. The apex of the dens still remained at6.0 mm protrusion to the McGregor line.

The AP cephalogram (Fig 8a) demonstrated nei-ther poor head posture nor differences in ramuslength and facial height between the right and leftsides or the occlusal plane tilt. The tilted dens couldnot be improved during treatment or posttreatment.

The panoral (Fig 7c) and joint radiographs (seeweb edition) showed a slight increase in size of theleft condyle both during and after treatment,though the severely malformed condyle and ramuson the left side still remained. Electromyographi-cally (Fig 8d), 4 years 2 months posttreatment, thelef t masseter and r ight temporal is musclesremained severely hypertonic with abnormal elec-tric activities, indicating masticatory function couldnot improved.

This adult patient showed little morphologicimprovement of the cervical spine, ramus, condyle,and fossa, both during and after retention, even withphysiotherapy of the neck muscles and attention toposture and masticatory habits. As a result, occa-sional clicking persisted with the left joint and TMDsymptoms recurred twice a year during the 4 years 2months posttreatment period. These were resolvedspontaneously, though mild tinnitus, dizziness, andmigraine remained.

DISCUSSION AND CONCLUSIONDISCUSSION AND CONCLUSION

The cervical spine and muscles serve to stabilizehead position and play an important role in the com-plex movement of the head. They also assist the mas-ticatory muscles in smooth mandibular movement.The axis of the second vertebrae with the dens con-stitutes the atlantoaxial joint and is involved in upperneck movement. In these patients, the cranium wastilted to the SCM muscle contraction side and wasrotated to the upper trapezius muscle contractionside. The contracted SCM and/or contracted uppertrapezius muscles induced hypertrophy of the tempo-ral and occipital bones on the affected side. This mayalso cause fusion or morphologic abnormality of theC2-C3 joint, straightening the cervical spine andpushing the dens of the axis up into the cranial base.These changes trigger dysfunction of the atlanto-occipital and atlantoaxial joints and disturbance of

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Fig 9 Tracings of pretreatment and 7 years 2 months posttreatment cephalograms.

head rotation, which in turn produces marked asym-metry of masticatory muscle activity, with hyperactiv-ity and hypertonicity, as the head tilts away from theside of the unilateral masticatory habit. Morphologicabnormality of the condyle and ramus develop on thehypertonic side. This may be due to excessive com-pressive loading by the closing muscles, which actsto deflect the mandible and deforms the mandibularnotch and condyle, as reported by Soma.4 Asymmet-ric masticatory muscle activity can also induce asym-metric mandibular movement and growth in growingchildren. The marked dysplasia of the condyle andramus observed in the adult patient can be attrib-uted to the contraction of the right SCM muscle,causing hyperactive masseter muscles, morphologicabnormality of the cervical spine present from child-hood, causing dysfunction of the mandible, as well asthe atlanto-occipital and atlantoaxial joints, and limi-tation of head rotation. Thus, movement of the leftcondyle remained restricted for many years, leadingto underdevelopment of the condyle and ramus onthat side. This, in turn, aggravated morphologicabnormality of the cervical spine and abnormal activi-ties of the neck and masticatory muscles, accentuat-ing the tilt and rotation of the cranium. The con-tracted masseter muscle remained hypertonic,producing severe facial asymmetry and poor headposture and worsening the morphologic abnormalityof the condyle and ramus. Graber5 stressed that thearticular process thickens as the force of the tempo-ralis increases. These observations support thehypothesis that contraction of the SCM and uppertrapezius muscles may induce mandibular dysfunc-tion, resulting in underdevelopment of the mandibleon the affected side.

In case 1, movement of the left condyle was dis-turbed, with contraction of the right SCM and the leftupper trapezius muscles, adversely affecting thecondylar growth. The physiotherapy of the neck mus-cles helped eliminate the morphologic abnormality ofthe cervical spine, limitation of rotational head move-ment, and asymmetric masticatory muscle activity.The occlusal treatment was also effective in unload-ing the joint and achieving a stable occlusion con-ducive to smooth jaw movement. As a result, therange of motion of the af fected condyle wasrestored, allowing more symmetric mandibular move-ment. The morphology of the condyle and ramus wasalso improved to near symmetry before completionof the permanent dentition, and excellent symmetrywas achieved during the remaining growth.

In case 2, movement of the left condyle was dis-turbed, with strong contraction of the left uppertrapezius and right SCM muscle, adversely affectingcondylar growth. The morphologic abnormality of thecervical region was aggravated due to a lack of atten-

tion to head and body posture, unilateral masticatoryhabit, and strong contraction of the upper trapezius.The distance from the dens to the McGregor lineincreased to 6.0 mm. The patient continued to experi-ence limited head rotation and hypertonicity of themasseter and temporalis muscles, further increasingthe morphologic abnormality of the condyle andramus on the hypertonic side. Physiotherapy of thecervical area, combined with occlusal treatment at anearly stage of growth and development, helped nor-malize the dens-to-cranium relationship, function ofthe atlanto-occipital and atlantoaxial joints, head rota-tion, and masticatory muscle activity. This, in turn,helped improve the morphology of the condyle andramus. The TMJ undergoes major changes in morphol-ogy from the mixed dentition period to the completionof the permanent dentition. Occlusal treatment andcorrection of morphologic abnormality of the cervicalspine and muscles at an early stage of growth anddevelopment can be expected to allow the patient toobtain symmetric masticatory muscle activity andsmooth mandibular movement. This will contributegreatly to healthy development and functional recoveryof the TMJ and the maxillofacial skeleton as a whole.In complex cases with occlusal abnormality, lateraldeviation of the mandible, and asymmetric verticaldimension between right and left sides, combinedwith morphologic abnormality of the cervical spine andmuscles, it is important for the orthodontist to collabo-rate with an orthopedic surgeon in early comprehen-sive treatment and management of the problems priorto completion of the permanent dentition.

ACKNOWLEDGMENTSACKNOWLEDGMENTS

It gives us great pleasure to be able to publish these cases thoughthe kindness and editing of Professor T. M.Graber. The authorwants to thank the team members who made this report possible:Shiho Arai, Michiyo Sasaki, Junko Noda, Sumie Suzuki, ToshitsuguSakuma.

REFERENCESREFERENCES

1. Kondo E, Aoba TJ. Case report of malocclusion with abnormalhead posture and TMJ symptoms. Am J Orthod DentofacialOrthop 1999;116:481493.

2. Kondo E, Nakahara R, Ono M, et al. Cervical spine problemsin patients with temporomandibular disorder symptoms: Aninvestigation of the orthodontic treatment effects for growingand nongrowing patients. World J Orthod 2002;3:295312

3. McGregor M. The significance of certain measurements ofthe skull in the diagnosis of basilar impression. Br J Radiol1948;21:171181.

4. Soma K. Distribution of occlusal stress on mandible, denti-tion and teeth. J Stomatol Soc Jpn 1993;60:19.

5. Graber TM. Orthodontics: Principles and Practice (ed 3).Philadelphia: WB Saunders, 1997:129179.

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Posttreatment (14Y 6M) 5 years 4 months posttreatment (19Y 10 M)

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