Prevention of temporomandibular disorder-related signs and symptoms inorthodontically treated adolescents

A 3-year follow-up of a prospective randomized trial

Mikko Karjalainen, Yrsa k Bell, TapioJämsä and Sära KarjalainenPublic Health Center of Turku and Section of Postgraduate Education, Department of OraIDevelopment and Orthodontics, and Department of Pediatric Dentistry, Institute of Dentistry,University of Turku, Turku, Finland

Karjalainen M, Le Bell Y, Jämsä T, Karjalainen S. Prevention of temporomandibular disorder-relatedsigns and ryrnptoms in orthodontically treated adolescents. A 3-year follow-up of a prospective randomizedtrial. Acta Odontol Scand i997;55:319 324. Oslo. ISSN 0001-6357'

Recommendations about the need for occlusal adjustment after malocclusion therapy are inconclusive. Atotal of 123 orthodontically treated healthy adolescents (BB girls, 35 boys; 14.8 + 1.7 years old) agreed toparticipate in the present study. The subjects were interviewed and examined for signs and symptoms

ielated to temporomandibular disorder (TMD) and were randomly a.llocated to intervention (rz = 63) andcontrol (z = 6Ö) gtorps. At base line, occlusal adjustment was carried out for the intervention group andrepeated every 6 months thereafter as needed. Mock adjustments were perlormed for the conlrol group. Atthi end of the 3rd year il8 subjects (96%) turned up for re-examination. The number of subjects withpalpatory pain of the masticatory muscles, and with occlusal centric slides decreased significantly_ in theintewention group but not in the control group (P< 0.001). In conclusion, occlusal adjustment therapymay prevent the occrrr"r.. of TMD signs in orthodontically treated healthy adolescents. Z Dmtal occlusion;

occlusal aQjushnmt; prnmtion; temporomandibul.ttr disordus

Sira Karjalainm, Deparhnmt of Pedintrfu Dentistry, h*titute of Dmtistry, Unitusity of Turku, I-emminkiiiseflkatu 2, FIN'20520 Turku, Finland

Controversial opinions exist on the associations betlveen

»4nptoms and signs related to temporomandibulardisorders (TMD) and malocclusions. Distal occlusion,posterior crossbite and deep bite may have associationswith the development of TMD (1, 2), but the overallcorrelation between TMD ry.rnptoms and malocclusionsis low (2). This may partly be due to problems in thestudy designs conventionally applied (3). Subjects whohave been treated for malocclusions have lower clinicaldysfunction indexes than those who have untreatedmalocclusions (4,5). TMD-related symptoms and signs

occur ilrespective of the pattern of orthodontic treat-ment (6 B). On the other hand, long-term relapse afterorthodontic treatment is commoner than is generallybelieved (9). Methods to prevent treatment relapse inorthodontic treatment, other than'overcorrecting',surgery of transseptal fibers (10), or modifying theperiod of retention, are few (l l). Occlusal interferencesmay have a traumatic effect on the dentition (12) andseem to be associated with TMD-related signs and

».rynptoms even in 5- to lO-year-old children (13).

Recent results suggest that the elimination of interfer-ences after orthodontic treatment improves the healthof the stomatognathic system (14). Our aim was,therefore, to study longitudinally the significance ofocclusal adjustment in preventing TMD-related signs

and sl,rnptoms and treatment relapse in adolescentswith experience of malocclusion therapy.

Subjects and methods

SuQjects

A total of l38 healthy adolescents whose orthodontictreatment, including retention, was completed duringthe year 1991 at the Public Health Center in Turku,were invited to participate in the present study. Thepreceding orthodontic treatment had been carried outby one orthodontist and with fixed appliances. Forty percent of the subjects had malocclusions with bilateral and2+o/o with unilateral class-Il molar relationship; the re-maining 36% had malocclusions with class-I molarrelationship before the start of the orthodontic treat-ment. Subjects with class-I and class-Il molar relation-ships were evenly distributed between the interventionand control groups. None of the children had previouslybeen interviewed, examined, or treated for TMD-related signs or syrnptoms. Altogether 123 subjects (BB

girls, 35 boys), whose mean (s) age was l4.B (1.7) years,agreed to participate. The subjects were randornlyallocated to intervention (n = 63) and control (z = 60)groups, and informed consent was obtained. The studywas approved by the Ethics Committee of the PublicHealth Center of Turku, Finland. One subject wasexcluded because of manifest TMD, and four did notwant to continue in the study. We report the follow-upof the 96% who received both examinations.

320 M. Kaialainen * al. ACTA ODONTOL SCAND 55 (1997)

Table l. The number of subjects with s1'rnptoms in the intervention (z = 63) and in the control (z = 60) group at base line and at the 3-yearfollow-up examination

S;,'rnptoms

Base line 3-year follow-up

lntervention, z (%) Control, z (%) Intervention, r (o/o) Control. z (o/o)

Specfic slanptoms

Jaw painChewing painFatigue ofjawsLuxation or

locking of the jaws

Joint sounds (clickingor crepitation)

Nighttimetooth-grinding

Daltimetooth-grinding

Non-specific symptomsRecurrent

headacheEar sl, nPtomsThroat painNeck painBack painVertigoGlobus

»r:nptomDilficulties in

swallowing

10 (15)

+ (7)

2 (3)

1e (3 1)

3 (s)0 (0)

2 (3)

2 (3)

3 (5)

I (2)

5 (B)

4 (7)

2 (3)

1 (2)

7 (t2)0 (0)

0 (0)

2 (3)

0 (0)

6 (10)4 (7)

7 (t2)s (B)

13 (22)

l0 (r7)

3 (s)

t7 (28)

r1 (18)0 (0)

4 (7)

4 (7)

4 (7)

6 (10)

2 (3)

2 (3)

0 (0)

0 (0)

4 (7)

t6 (27)

e (15)

0 (0)

11 (le)

I (2)

1e (32)

e (15)

3 (s)

e (15)

B (r3)0 (0)

2 (3)

I (2)

2 (3)

4 (7)

5 (B)

s (e)

0 (0)

5 (e)

0 (0)

4 (7)

I (2)

No significant differences were found between the intervention and control groups (Tisher's exact test).

Interairu and clinical examinatiln

The participants were interviewed for the occurrenceof s),rnptoms related to TMD on the basis of a list of 18questions: the occurrence of recurrent headache ()2episodes a month), pain in the jaws, throat, nech andback, ear s).mptoms, pain in the temporomandibularjoints at rest and during chewing. The occurrence ofday- and night-time grinding, vertigo, stiffness in jaws,dfficulties in swallowing, globus ryrnptoms, joint sounds(clicking or crepitation of the temporomandibularjoints), and spontaneous luxation or locking of the jawswere also asked about. The questions were designed togive dichotornized, yes/no answers. The interview wascarried out at base line and annua\ thereafter. In thisreport the results of the initial and the 3-year follow-upinterviews are given. Two of the authors (Y. Le Bell andT. Jämsä), with special expertise in stomatognathicphysiology, were carefully calibrated before the studyand carried out the interview and the clinical examina-tions throughout the study. The exarniners wereunaware of whether occlusal adjustment had beenperformed. Palpatory tenderness was recorded if painwas noted on either side of the seven masticatorymuscles: Mm. temporalis, temporalis insertion, pter-ygoideus lateralis and medialis, masseter superficialisand profunda, and digastricus posterior. For statisticalanalysis subjects with no palpatory tenderness in any of

the listed muscles were classified as sign-free subjects,whereas those with one or several painful muscles wereregarded as subjects with TMD signs. Clicking, crepi-tation, and tenderness on movement or on maximalopening of the joint were evaluated by bidigital palpa-tion and auscultation. Deviation of the. mandible onopening and closing was also recorded. Mandibular mo-bility was recorded as maximal opening (millimeters)and as maximal movements to the right, to the left, andforward.

The articulation pattern of the teeth was recorded ascanine guidance, group contact, or other. The presenceof occlusal interferences in retruded, protruded, andmedio- and latero-truded positions of the mandible (13)was examined by using GHM foil (0.008 mm, IIanel-GHM-DentaI GmbH, Niirtingen, Germany). Occlusalcentric slides in vertical, horizontal, and lateral direc-tions were also recorded (14). The examination wascarried out at base line and annually thereafter.

VTeahnmt

Occlusal adjustment, aiming to eliminate any slidesbetvyeen retruded and intercuspal position, contact onthe mediotrusion side, and post-canine contact on thelaterotrusion side or during protrusion, was performedfor all subjects in the intervention group as described by

ACTA ODONTOL SCAND 55 (1997)

TMD-related symptoms

lntervention Control

Fig. 1. The number ofsubjects in the intervention and in the controlgroups with (Yes) and without G.{") *y of the symptoms listed inTable I at base line and after the 3-year period of follow-up. Thenumbers on the horizontal lines indicate subjects with no change insymptoms; those on the descending lines indicate new subjects withsyrnptoms, and those on the ascending lines indicate new as).rnpto-matic subjects. *Fisher's exact.

Riise (15). Maintenance adjustments were carried outevery 6 months during the follow-up period as needed.Mock adjustments with non-abrasive burs was per-formed for the control group. All adjustments werecarried out by two dentists (\d. Karjalainen and DrAnna Arve), both of whom had expertise in performingocclusal equilibration.

Prnmtion of TMD 321

Statistical anafisis

Fisher's exact test was used to analyze the differencein the frequency distributions of TMD-related ryrnp-toms and signs between the groups and betvveen the twoexaminations. Analysis of variance (ANOVA) forrepeated measures was used to analyze the differencesbetween groups in occlusal centric slides. P values less

than 0.05 were considered significant.

Results

Sltmptoms anl signs

Recurrent headaches and ear syrnptoms had de-creased in both groups by the 3-year follow-upexamination, but the change was not significant (Table1). At the same time, the number of qrmptom-freesubjects increased in both groups without any significantdifferences between groups (Fig. l). The proportion ofsubjects with reported temporomandibular joint soundsincreased from 17 o/o to 29% over the observation period(P < 0.02) (Fig. 2), whereas no such dilference wasfound in the frequency of recorded sounds (Fig. 2).There was a weak correlation betvveen reported andrecorded joint sounds at base line (r = 0.345), whichwas much stronger at the end of the 3rd year of follow-up (r = 0.676). No differences were found in reported or

No

Yes

Reported temporomandibular joint sounds

Intervention Control Total

Recorded temporomandibular joint sounds

lnterventiou Control

Baseline 3 years

Total

Yes

Fig. 2. The number of subjects with (Yes) and without §o) reported (interview) and recorded (auscultation)temporomandibular joint sounds at base line and after the 3-year period of follow-up. For furtherexplanation, see the legend to Fig. 1.

322 M. Karjalnircn et al.

Palpatory pain of the masticatory muscles

Infervention Control

Beseline 3 years

Yes

ACTA ODONTOL SCAND s5 (1997)

masticatory muscles decreased in the interventionqoup. Since prevention is the best approach to treatall chronic diseases including TMD,- äcdusal adjust-ment, successfully used to treat manifest TMD earlier(16, l7), was here tested for preventive purposes. Wecannot agree with earlier studies claiming that earlytreatment of occlusal conditions to prevent the devel-op^ment of TMD would not be justified scientifically(lB). On the contrary, we have shor,r,n here that stableocclusion-that is, an occlusion without interferencesand slides between intercuspal and retruded position-qay significantly reduce the many risks of TMD.Indeed, the positive results of the treatment method arebelieved to be due to elimination of occlusal risk factorsof-lMD (15). Needless to say, further follow-up of thesesubjects will be required to answer the question whetherTMD in adulthood can be prevenled by carefuladjustment of occlusion.

, . Th. - nurnber of sl,rnptomatic subjects was clearly

higher both at base line and after 3 years than reportedearlier for non-patients in a similar age range (19, 20).This may indicate that subjects undergäing träatment orwith recently treated malocclusions genäraly have ahigher frequency of TMD-related sy'rnptoms thansubjects with no history of malocclusion or malocclusiontherapy, as has been shown in earlier studies (14,21).On the other hand, TMD-related symptoms have beenshown to increase with age also in iubjects with norecorded malocclusions but are then described to be

ryostly occasional and mild (22). The large variation inthe prevalence of TMD-related ry.rnpioms in non-patients has also been recognized earlier (1, 7) and isthought to be due to growth-related adaptation of themasticatory apparatus. Contrary to the prevalence ofslrnptoms, that of reported joint sounds increasedduring the- follow-up period. However, the frequencyof recorded joint sounds remained the same. The weakcorrelation between reported and recordedjoint soundsat base line is probably due to the study effect: oursubjects leamed to recognize and report their existing

Table 2. Occlusal centric slides (mean and standard deviation (s), inpm) 11

tne intervention (z = 63) and in the control (a = 60) group atbase line and at the 3-year follow-up examination

Fig..3. The number of subjects *ith E s) and without so) palpatorytenderness of the masticatory muscles in the intervention u.rd-in thäcontrol groups at base line and after the 3-year period offollow-up.For further explanation, see the legend to Figurä l.

recorded temporomandibular joint sounds between thegroups at base line or after the 3-year follow-up (Fig. 2).

The number of subjects with painful- mu-sctesdecreased significantly in the intervention group duringthe 3-year Ql]ow;up period, whereas ,o irr.h changäwas observed in the control group (Fig. 3).

Occlusion and mandibular moaanntt

Occlusal adjustment resulted in reduced horizontal,vertical, and lateral slides between retruded u.dintercusp_al position in the intervention group, whereasno significant changes were recorded for titre controlgroup (Table 2). The number of subjects with bilateralgroup contact decreased significantly in the interventiongroup as opposed to a slight increase in the controlgroup (P < 0.04) (Table 3). Ove{et and overbite in rhetvvo. groups did not differ and remained unchanged

!y.hq the follow-up period (median (range), 3 l0-B)mm).

No differences were observed between groups inmaximal . opening at base line or at ttre 3-yru,examination-(median (range), 52 (38-72) mm). Furtiier-more, no di{ferences were observed in maximal lateralmovement to the right or to the left at base line or at thefinal examination (median (range), l0 (5-15) mm). Maxi-mal protrusion did not change during the follow-upand was the same in the two groups (median (range),

^5

(l-10)mm).

Discussion

We have shown that in a short-term perspective of 3years, o^cclusal adjustment improves ocölusal stability interms of reduced amount of slides between retruded andinter.cuspal position and, at the same time, more equallydistributed tooth contacts between the upper and io*eidental arches without prematurities. Moreover, thenumber of subjects with palpatory pain in the

lntervention Control

Direction of slide Mean FHorizontal

Base line3-year follow-up

VerticalBase line3-year follow-up

LateralBase line3-year follow-up

1.1 0.1l 0 0.1

1.0 0.10.9 0.1

0.4 0.10.5 0.1

0.9 0.10.5 0.I

0.5 0.10.3 0.1

LI0.7

0.10.1

NS0.001

NS0.001

NS0.003

* ANOVA for repeated measurements.

ACTA ODONTOL SCAND 55 (1997)

Table 3. Articulation pattern at base line and at the 3-year follow-upexamination in the intervention and in the control group

Intervention, Control,nn

Canine guidance bilateralBase line3-year follow-up

Group contact bilateralBase line3-year follow-up

Other patternBase line3-year follow-up

* Fisher's exact test.

joint sounds more accurately over time. Our findingsare partly in line with earlier results showing an increasein reported joint sounds in 15- to l8-year-old adoles-cents (23) but do not support the occurrence of a similarincrease in recorded joint sounds. The prevalence ofrecorded joint sounds at base line and at the end of the3rd year were both higher than reported earlier forhealthy adolescents (23,24). The use of a stethoscope injoint sound assessment may explain the difference withregard to the findings obtained by palpation and thenaked ear (2a). The reason for the high prevalence ratescompared with those obtained earlier by auscultation(23) is probably the difference in the examination set-up. In our study the clinical examination and thepreceding interview were both carried out by the samedentist, unlike in the study referred to above (23).Therefore, awareness of the results of the interviewmight have increased the detection rate ofjoint soundsin our study.

The present results do not yet answer the question ofwhether orthodontic treatment relapse can be pre-vented by careful occlusal adjustment. The fact that wefound no indication of treatment relapse, which,however, is known to start shortly after retention (l l),suggests that our methods were too crude to detectsubtle changes in the orthodontically treated occlusion.However, on the basis of the interference-free occlusionand the reduced frequency of masticatory muscletenderness on palpation, more stable results and alower frequency of treatment relapse can be predictedfor our intervention group as compared with the controlgroup. More accurate measurements on cast modelsand a longer follow-up are in progress.

In conclusion, occlusal adjustment after orthodontictreatrnent improves occlusal stability and reduces thenumber of case§ of palpatory tenderness in themasticatory muscles.

Acknoul.edgmwnts.lThe financial support of the Finnish DentalSociety to the first author is gratefully acknowledged. The authorsalso wish to thant Dr Kalle Virta for referring orthodontic patients tous and Dr Anna Arve, whose contribution in perlorming occlusaladjustment has been valuable and untiring. The authors are also

Pramtion of TMD 323

grateli,rl for the skilled assistance of Ms Rauni Miikinen and Ms OutiSallinen.

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F

15

22

2023

2415

1632

2l9

222l

NS

324 M. Karjakhoz et al.

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Received for publication 14 February 1997Accepted 15 May 1997

ACTA ODONTOL SCAND 55 (1997)

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