ÖZET ABSTRACT

Amaç: Derin örtülü kapanışlı vakalarda sabit anterior biteplane tedavisinin dentoiskeletsel yapılar ve çiğne-me kasları üzerine etkilerini değerlendirmektir.

Bireyler ve Yöntem: Çalışma grubu ortalama yaşları 9,9± 0,9 yıl olan 17 hastayı içermektedir. Hastaların Sınıf II maloklüzyonu, derin örtülü kapanışı ve azalmış alt anterior yüz yüksekliği bulunmaktadır. Bireylerden sabit anterior biteplane tedavisinden önce (T0) ve sonra (T1) lateral sefalometrik radyograflar ve elektro-miyografik kayıtlar alınmıştır. Sefalometrik ve elektro-miyografik değişkenlerin istatistiksel analizi Bağımlı-t testi ve Wilcoxon İşaret testi ile değerlendirilmiştir.

Bulgular: Ortalama tedavi süresi 8,5±2,1 aydı. Sonuçlar alt yüz yüksekliğinin ve toplam yüz yük-sekliğinin arttığını göstermiştir. Mandibula öne hare-ket etmiştir. Maksiller ve mandibular keserler labiya-le eğimlenmiştir. Derin örtülü kapanış ve overjet azal-mıştır. Vertikal olarak, tedavi sırasında mandibular posterior dişler erüpte olmuştur. Tedavi başlangıcında hastanın istirahat pozisyonundaki elektromiyografik aktiviteleri normalden yüksek bulunmuştur ve teda-vi sonunda değişmemiştir. Tedavi başlangıcında diş sıkma sırasında en yüksek aktiviteyi anterior tempora-lis ve masseter kaslar göstermiştir ve tedaviden sonra anlamlı değişiklik oluşmamıştır.

Aim: To evaluate the effects of fixed anterior bitepla-ne treatment on dentoskeletal structures and mastica-tory muscles in deep bite patients.

Subjects and Method: The sample is comprised of 17 patients with the mean age of 9.9 ± 0.9 years. The patients had Class II malocclusion, deep bite, and reduced lower anterior facial height. Lateral cephalo-metric radiographs and electromyographic recordings were obtained from the subjects before (T0) and after fixed anterior biteplane treatment (T1). The statistical analysis of the cephalometric and electromyographic variables were evaluated by using Paired-t test and Wilcoxon Signed Ranks test.

Results: The mean treatment time was 8.5±2.1 months. The results showed that the lower anteri-or facial height and total facial height increased. The mandible moved in a forward position. The maxillary and mandibular incisors inclined labially. Deepbite and overjet reduced. Vertically, the mandibular pos-terior teeth erupted during treatment. The electrom-yographic activities of the patients during rest positi-on were found to be higher than normal at the begin-ning of the treatment and maintained at the end of the treatment. It was found that anterior tempora-lis and masseter muscles showed the highest activity

Hacettepe Diş Hekimliği Fakültesi DergisiCilt: 34, Sayı: 1-2, Sayfa: 10-22, 2010

Evaluation of the Effects of Fixed Anterior Biteplane Treatment on the Dental and

Skeletal Structures and Masticatory Muscles in Patients with Deep Bite

Derin Örtülü Kapanış Vakalarında Sabit Anterior Biteplane Tedavisinin Dental ve İskeletsel

Yapılar ve Çiğneme Kasları Üzerine Etkilerinin Değerlendirilmesi

*Bengisu AKARSU DDS, PhD, *Semra CİGER DDS, PhD* University of Hacettepe, Faculty of Dentistry, Department of Orthodontics

ARAŞTIRMA (Research)

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INTRODUCTION

Morhological characteristics of deep bite are classified as dental, skeletal and soft tissue. Over-eruption of mandibular and maxillary incisors, retroclination of the mandibular and maxillary incisors, infra-occlusion of the mandibular and maxillary posterior teeth are the dental factors that contribute to a deep bite1,2. The skeletal fac-tors are shown as increased posterior vertical fa-cial growth compared to anterior vertical facial growth and excessive growth of the mandibular ramus3. Soft tissue factors are high lower lip line and lateral tongue thrust4,5.

Muscular characteristics of the patients with deep bite are different from the subjects with ideal bite. Patients with deep bite had greater masticatory muscle activities comparing to nor-mal subjects6-8. Because of the increased activi-ties of the masticatory muscles in patients with deep bite, depression of the molar teeth could occur, and the vertical growth of the lower ante-rior face and posterior dentoalveolar region limi-ted9. In this situation, the treatment of deep bite becomes more complex and the stability of the results can not be maintained easily. Electrom-yography (EMG) is a technique providing to re-cord the electrical signals produced by muscular fibrils and transmitted through the tissues. The electrodes used to record these electrical signals can be placed on the skin surface over the musc-le or near the muscle subdermally with the need-les or into the muscle with the needles. Needle electrodes are not used routinely because their

insertion is an invasive method. Surface EMG is a non-invasive method providing to evalua-te whole muscle structure with bipolar electro-des placed on skin surface and don’t cause pain or discomfort for the patient10,11. Surface EMG has been commonly used by the researchers in the recent years to compare the muscular acti-vity of the persons with craniomandibular disor-ders with that of the normal persons or to com-pare the changes in muscular activity resulted from the treatment with that before therapy. It has been shown that the surface EMG yields re-peatable measurements11.

Deep bite can be corrected with intrusion of the incisors12-14, extrusion of the posterior te-eth13,15,16, flaring of the anterior teeth16,17, and/or surgery18,19. Excessive overbite may impede the growth of the mandible and mandibular dento-alveolar region20,21. It may cause temporoman-dibular joint disorders22,23 and increased masti-catory muscle activities8,10,11. Hence, early treat-ment of deep bite is critical. In growing patients, allowing more eruption of the lower posterior te-eth than the upper teeth rotates up the occlusal plane posteriorly in the direction that facilitates Class II correction24. Although removable functi-onal appliances provide such modifications, ex-cellent patient cooperation is necessary for a suc-cessful treatment. To eliminate the need for pa-tient cooperation, fixed anterior biteplane has been used in patients with deep bite25-28.

Forsberg and Hellsing25 demonstrated that fixed anterior biteplane therapy is effective in

ANAHTAR KELİMELERBiteplane, derin örtülü kapanış, elektromiyografi.

KEYWORDSBiteplane, deepbite, electromyography

during teeth clenching at the beginning of the treat-ment and no significant change occured after the tre-atment.

Conclusion: Early treatment of deepbite by using a fixed anterior biteplane, effectively improved sagittal and vertical problems, and no significant change was found on the activities of the masticatory muscles.

Sonuç: Sabit anterior biteplane ile derin örtülü kapa-nışın erken tedavisi sagital ve vertikal problemleri etkili şekilde düzeltmiştir ve çiğneme kaslarının aktivi-tesinde anlamlı değişiklik bulunmamıştır.

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reduction of deep bite. Ballester and Langlade26 introduced the modifications and treatment indi-cations of a semifixed biteplane. Fixed anterior biteplane was found effective in alleviating pain, daily headache in the region of anterior temporal muscles and clicking in temporomandibular jo-int27,28. However, the examination of masticatory muscles was limited with the palpation of musc-les in these studies25,28. Therefore, the aim of the present study was to evaluate the effects of the fixed anterior biteplane on dentoskeletal structu-res and masticatory muscles activities.

SUBJECTS AND METHOD

Subjects

The sample is comprised of 17 patients with the mean age of 9.9 ± 0.9 years (Table I). The pa-tients had Class II malocclusion, deep bite more than 3 mm, reduced lower anterior facial height, brachyfacial growth pattern, and mixed or early permanent dentition. None of the subjects had any previous orthodontic treatment.

To carry out the study, the ethics committee decision dated 23-06-2004 with the registration number of LUT 04/30 was received from Ethics Committee of Medical, Surgical and Drug Rese-arch of Hacettepe University.

The initial views of one patient are presented in Figure 1-5.

Orthodontic treatment

In each patient, the first maxillary molars were fitted with orthodontic bands and then al-ginate impressions were taken. On the maxillary dental cast, a lingual arch extended between the first maxillary molars was made and welded to the bands. The arch was also equipped with occ-lusal stops resting on the deciduous molars or the first premolar. If the maxillary incisors had a lin-gual inclination, labiolingual springs were placed behind the central incisors. Bite registration was taken for achieving Class I molar relationship ca-using a separation of the upper and lower molars of approximately 4 mm. The dental models were

FIGURE 1-5

Extraoral and intraoral photographs of a patient before fixed anterior biteplane treatment.

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TABLO I

Sample description

n Boys Girls Mean age (T0) Average treatment time

17 8 9 9.9±0.9 years 8.5±2.1 months

transferred to the articulator, thereafter an incli-ned acrylic anterior biteplane was prepared and was placed to upper first molars (Fig 6-8). The views of the patient after fixed anterior biteplane treatment are presented in Figure 9-13. In 9 pa-tients, lower and upper Hawley appliances were used for retention after the fixed anterior bitepla-ne treatment. In 8 patients, the teeth were bon-ded for the treatment of the other malocclusions present such as irregularity or diastema and the fixed orthodontic therapy was continued.

Cephalometric evaluation

In order to assess dental and skeletal changes resulting from treatment, two lateral cephalo-metric radiographs were taken on each patient. The first radiograph was taken when patients re-gistered at the orthodontic department (T0). The second lateral cephalometric radiograph was ta-ken when the bite had opened and the Class I molar relationship had been achieved (T1). The mean treatment time with fixed anterior bitepla-ne was 8.5±2.1 months (Table I). Radiographs were taken using the same cephalostat by one investigator on natural head position and in stan-dard conditions. On each cephalogram, 19 land-marks were identified. From these landmarks, 16 angular and 15 linear measurements were deri-ved and are listed in Table II and III.

EMG evaluation

EMG records were taken by using a surface electromyography system (BioPAK Version 2,03 System, BioResearch INC., Milwaukee, Wiscon-sin) at T0 and T1.

To get the EMG records, disposable bipo-lar surface electrodes and BioEMG 8- channel amplifier were used. EMG records were done on masseter (MM), anterior temporalis (TA),

anterior digastricus (DA), and sternocleidomasto-ideus (SCLM) muscle groups. During the recor-ding, the patient was asked to sit with the back upright and the soles of the feet easily flatting on the floor, looking straight ahead and in a positi-on that prevented he computer monitor from be-ing seen. The skin surface was cleaned with alco-hol before attaching the bipolar surface electro-des on where the muscles to be recorded in EMG were palpated and on the region to be used for static grounding. Thus, the resistance of the skin to the transmission of electrical activity was di-minished and better attachment of the electro-des was achieved.

To determine the anterior temporalis musc-le (TA) and masseter muscle groups, the patients were asked to close the mouth tightly and the muscles were palpated in this position and the-ir movements were observed. To determine the sternocleidomastoideus (SCLM) muscle group, the patient was asked to incline the neck against the side where the electrode would be placed and slightly backward. In this position, the location in which the electrode would be placed was deter-mined with palpation and observation. To deter-mine the anterior digastricus (DA) muscle group, the patient was asked to incline the head slightly backward and swallow. The chin of the patient was palpated and the movement of the muscles was observed. Bipolar surface electrodes were placed over the right and the left muscle groups parallel to the muscle fibrils. An electrode was placed in the neck area of the patient towards the shoulder for static grounding. To avoid elect-ronic noise, it was regarded that the electrodes weren’t placed on hairy skin and were closely at-tached. After completing the placement of the surface electrodes, the amplifier was connected.

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EMG records were obtained in the following positions:

1. Physiological resting position: After swallo-wing, the patient was asked to leave his/her jaw relaxed and not to contact the teeth. Be-fore the measurement, the posture of the patient was evaluated and it was ensured that the patient was in a comfortable position. Af-ter such determination of the resting positi-on, the electromyographic activity was recor-ded throughout about 10 seconds.

2. Clenching teeth: The patient sitting in the resting position was asked to clench the teeth as tight as possible and then relax. This pro-cedure was repeated a couple of times during 10-second recording.

3. Swallowing: Before initializing the recording process, the patient was asked to collect the

FIGURE 6-8

Intraoral views of the fixed anterior biteplane appliance.

FIGURE 9-13

Extraoral and intraoral photographs of the patient after fixed anterior biteplane treatment.

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saliva in the mouth. Then, the program was run. The patient was asked to swallow and the recording was completed by stopping the program.

The muscular contractions during physiologi-cal activities recorded with bilaterally placed sur-face electrodes were measured in microvolt (µv).

When the relaxing EMG records were evalua-ted, 3 regions were randomly marked on the ac-tivity images obtained throughout the recording and the mean electromyographic activities for the right and the left muscle groups were recor-ded (Figure 14).

STATISTICS

Sample Size Estimation

A sample size of 17 was required to detect at least 2.9 and 1.4 milimeters increase between be-fore and after treatment, regarding for ANS-Me and L6-MP, respectively, with a power of 90% at the 5% significance level. The increases of 2.9 and 1.4 millimetres were taken from reference study25. Sample size estimation was performed by using NCSS and PASS 200029.

Statistical calculations were performed with SPSS 11.5 software. Shapiro-Wilk test was used

TABLO II

Comparison of skeletal measurements on lateral cephalometric analysis at T0 and T1.

Skeletal parameters Mean S.D. Minimum Maximum p

SNAoT0 78.8 3.15 73.3 87.3

0.285†

T1 79.1 2.89 73.2 87.2

SNBoT0 73.9 2.80 69.5 81.3

<0.001†,***T1 75.1 3.03 71.4 83.4

ANBoT0 4.9 1.61 3.3 9.2

0.022†,*T1 4.2 1.40 1.8 7.9

FH-NAo T0 89.7 2.67 84.8 92.90.222†

T1 89.2 2.38 83.2 93

Maxillary heighto T0 60.0 3.04 54.4 64.80.758‡

T1 60.4 3.61 53.9 69

FH-NPgoT0 85.4 3.49 77 90.9

0.332‡

T1 86.1 2.20 82.3 89.4

Facial axisoT0 86.6 3.49 81 94.4

0.868‡

T1 86.7 3.43 80 93.1

FMAoT0 21.7 4.60 10 27.1

<0.001†,***T1 24.1 4.16 15.1 30.5

GoGnSNoT0 32.5 4.31 23.2 38

0.002†,**T1 34.1 4.40 24.5 41.2

Lower facial heightoT0 39.7 2.67 33.5 45

<0.001†,***T1 43.8 2.98 36.9 50

N-ANS mmT0 53.7 3.23 47.5 59.5

0.480†

T1 53.9 2.99 49 59.5

N-Me mmT0 114.2 5.40 106.5 126

<0.001†,***T1 118.4 4.67 111.5 127

ANS-Me mmT0 62.7 4.24 52.2 71.5

<0.001‡,***T1 67.0 3.04 61.7 72

S.D.= Standard deviation; p= probability; † Paired t-test, ‡ Wilcoxon Sign Rank test.*p<0.05; **p<0.01; ***p<0.001

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TABLO III

Comparison of dental measurements on lateral cephalometric analysis at T0 and T1.

Dental parameters Mean S.D. Minimum Maximum p

U1-FHoT0 108.5 8.83 93.9 127.2

0.037†,*T1 112.4 4.43 105.1 126.1

U1-SNoT0 97.7 9.99 81.2 121.5

0.021†,*T1 102.5 6.11 94 121.8

U1-NAoT0 18.9 8.05 1.4 34.2

0.024†,*T1 23.7 4.41 16.3 34.6

U1-NA mmT0 2.0 2.57 -3.5 7.2

0.017‡,*T1 3.5 1.67 0.5 6

FMIAoT0 64.5 5.49 56.1 74.7

<0.001†,***T1 59.1 6.47 47 72.6

IMPAoT0 93.9 4.77 85.4 103.4

0.040†,*T1 96.9 6.41 88 108

L1-NBoT0 20.2 5.32 12.3 28.7

<0.001†,***T1 25.5 5.92 15.2 37

L1-NB mmT0 2.9 1.84 0 6

<0.001†,***T1 4.5 1.86 0 8

L1-APg mmT0 -1.3 1.93 -5 2.8

<0.001†,***T1 0.8 1.95 -4 4.8

Overjet mmT0 6.3 1.86 3 9.5

0.044†,*T1 5.1 1.33 2.5 7.5

Overbite mmT0 5.7 1.53 4 8.7

<0.001†,***T1 1.0 1.01 -0.7 3

Lower incisor extrusion mm

T0 4.9 1.68 2 8<0.001†,***

T1 1.7 0.96 0 3.3

U1-Palatal plane (PP) mm

T0 28.1 2.11 25.9 32.50.895†

T1 28.1 1.69 16.4 31

U6-PP mmT0 20.1 2.75 16.4 28.5

0.500†

T1 20.4 2.44 17 26.4

U6-Ptv mmT0 13.3 2.65 9.3 18.4

0.600†

T1 13.1 2.71 9 18.3

L1-MandibularPlane (MP) mm

T0 39.5 2.49 36 45.30.347†

T1 39.2 2.10 34.5 43

L6- MP mmT0 29.7 2.74 25 36 <0.001†,***T1 32 2.89 28 39.5

L6- Ptv mmT0 11.3 3.06 6 16.5

0.002†,**T1 13.0 2.50 8.5 18.3

S.D.= Standard deviation; p= probability; † Paired t-test, ‡ Wilcoxon Signed Rank test.

*p<0.05; **p<0.01; ***p<0.001

to test the normality of distribution for continuo-

us variables. The non-parametric Wilcoxon Sig-

ned Ranks test was utilized for parameters where

the data were not normally distributed. The sta-

tistical analysis of the parameters that normally

distribute were evaluated by using Paired-t test. The statistical significance was established at p<0.05.

In order to evaluate measurement error, the analysis was repeated by the same investigator

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for all patients in two weeks interval. Intraclass coefficient correlation was found to be between 0.9407 and 0.998.

RESULTS

Cephalometric findings

Skeletal and dental findings are presented in Table II and Table III.

EMG findings

Findings during the rest position

When muscle functions at rest position in MM, SCLM and DA muscle groups in left and right and TA in right, the difference between T0 and T1 periods was not statistically significant (Table IV). The EMG activity of the TA in left at rest position had a significant decrease of mean 3.51 ± 5.29 µV.

Findings at clenching teeth position

Right DA and left SCLM activity decreased from T0 to T1 was found to be statistically signi-ficant (Table V).

Findings during swallowing

When muscle functions at swallowing were evaluated, it was seen that in TA, MM, DA muscle groups in left and right and SCLM in left, the difference between T0 and T1 peri-ods was not statistically significant. Only a sig-nificant decrease was found in SCLM muscle in right (Table VI).

DISCUSSION

Skeletal Findings:

The measurements which are used to assess facial growth pattern increased at T1. Fixed ante-rior biteplane appliance increased the vertical di-mensions of the patients with deep bite and these result are in accordance with previous studies25,26. The upper face height (N-ANS) and maxillary he-ight angle did not show any significant change. It can be assumed that fixed anterior biteplane had an inhibiting effect on the vertical development of the maxilla. It was found that the fixed anterior bi-teplane group had more than twice as large inc-rease in the measurements associated with upper

FIGURE 14

Electromyographic recordings by using BioPAK .

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TABLO IV

Comparison of electromyographic activities of masticatory muscles during resting position at T0 and T1.

Rest Mean S.D. Minimum Maximum p

TA(µV)

RT0 8.6 11.38 0.3 48.7

0.093†

T1 3.8 4.92 0.1 19.1

LT0 7.8 6.42 1.3 27.4

0.015‡,*T1 4.3 5.04 0.8 20.5

MM(µV)

RT0 6.6 11.66 0.4 47.2

0.507†

T1 5.2 7.09 0 22.5

LT0 4.2 4.09 0.4 14.2

0.234†

T1 3.7 3.75 1.2 16.5

SCLM(µV)

RT0 12.0 19.92 0.1 69.2

0.056†

T1 8.3 15.91 0.1 50

LT0 5.1 3.25 1.6 14.4

0.120‡

T1 3.6 2.07 0.7 7

DA(µV)

RT0 5.7 6.23 0.8 27.4

0.343†

T1 3.6 2.18 0.1 7.4

LT0 4.1 5.21 0.2 21.9

0.297†

T1 2.6 1.68 0.1 6

S.D.= Standard deviation; p= probability; † Wilcoxon Signed Rank test, ‡ Paired t-test, *p<0.05

TABLO V

Comparison of electromyographic activities of masticatory muscles during clenching of the teeth at T0 and T1.

Teeth Clenching Mean S.D. Minimum Maximum p

TA(μV)

RT0 47.4 33.27 0.6 108

0.423†

T1 40.9 31.84 0.8 93.4

LT0 58.1 35.55 0.4 129.1

0.470†

T1 51.3 33.76 9.4 109.2

MM(μV)

RT0 36.3 24.74 0.4 97.2

0.540†

T1 41.2 33.11 1.2 120.9

LT0 31.0 20.10 3.9 83

0.297†

T1 40.6 33.02 0.1 139.1

SCLM(μV)

RT0 6.4 3.25 0.3 14.9

0.582†

T1 7.2 4.14 1.6 17.6

LT0 28.0 55.62 0.3 229.1

0.014‡,*T1 14.2 32.85 0.2 134.6

DA(μV)

RT0 11.7 5.76 5.6 26.3

0.009‡,**T1 7.6 6.43 0.1 28.8

LT0 10.2 4.70 3.3 21.4

0.447†

T1 8.9 6.42 0.7 28.3

S.D.= Standard deviation; p= probability; † Paired t-test, ‡ Wilcoxon Signed Rank test.

*p<0.05; **p<0.01

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face height than the untreated group had, in the study of Forsberg and Hellsing25.

The increase of SNB angle and facial depth angle, the decrease of ANB angle at T1 in the present study could show anterior position of the mandible after fixed anterior biteplane tre-atment. Forsberg and Hellsing25 did not find any significant change in SNB and ANB angle in their untreated patient group in a period of 8 months.

Dental Findings:

With regard to the dental findings, the distan-ce of lower incisors to mandibular plane (L1-MP) was not changed significantly at the end of the treatment. This is consistent with previous stu-dies25,30. Forsberg and Hellsing25 found that L1-MP increased in untreated group. So it can be said that the fixed anterior biteplane therapy in-hibits the lower incisor extrusion. On the other hand, significantly decreased distance between lower incisor and occlusal plane (lower incisor

extrusion) and significantly increased distance of the lower molars to mandibular plane (L6-MP) at T1 could show relative intrusion of the lower in-cisors due to the mandibular posterior teeth ext-rusion that changes the occlusal plane.

Deep bite was succesfully corrected by extru-sion of mandibular posterior teeth and relative intrusion of mandibular anterior teeth in accor-dance with the previous studies using fixed an-terior biteplane25-27. Overjet showed statistically significant decrease at T1. Labially inclination of the lower and upper incisors and anterior positi-on of the mandible might be responsible on the overjet correction.

Muscular Findings:

Increased EMG activities of MM, TA, SCLM and DA muscles at rest position were recorded at T0. These results support the findings of the inves-tigators who reported that the patients with short face had a greater level of EMG activities in the masticatory muscles than normal subjects6,31,32 .

TABLO VI

Comparison of electromyographic activities of masticatory muscles during swallowing at T0 and T1.

Swallowing Mean S.D. Minimum Maximum p

TA μV

RT0 17.4 18.08 0.6 57.2

0.175†

T1 12.0 11.84 1.6 40

LT0 15.0 13.23 0.6 42.7

0.334†

T1 11.0 10.48 2.2 40.7

MM μVR

T0 11.4 7.47 3.1 27.30.509†

T1 13.4 9.39 2.2 31.2

LT0 8.6 5.77 0.8 21.7

0.466†

T1 10.1 6.51 2.1 24.2

SCLMμV

RT0 16.8 22.22 0 76.9

0.020‡,*T1 6.1 6.69 0.2 20.2

LT0 10.0 10.19 1.8 37.6

0.508†

T1 11.6 10.04 1.5 39.4

DAμV

RT0 20.4 14.16 2.9 53

0.471†

T1 17.4 9.78 3.8 45

LT0 23.4 17.09 4.4 64.7

0.171†

T1 16.3 11.21 0 44.9

S.D.= Standard deviation; p= probability; † Paired t-test, ‡ Wilcoxon Signed Rank test, *p<0.05

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At T1 stage, in the resting position an in-significant decrease in all muscle activities was determined. Only the decrease in the left TA muscle activities was found to be statistically sig-nificant. In an EMG study with anterior repositi-oning splint designed similar to the fixed anteri-or biteplane used in this study, it was shown that TA and MM activities were decreased33. Thuer et al34 opened the bite with removable biteplane in the children aged between 8-13 years with Class II Division 2 deep overbite and realized the labi-alization of upper incisors. They didn’t find any change in TA and MM activities in the resting position with EMG at the end of the therapy.

It was found at T1 that the mean TA musc-le activities were diminished and the mean MM muscle activities were increased; but these chan-ges weren’t statistically significant. It was shown that increased vertical dimension and mandib-le placed anteriorly decreased temporalis musc-le activities during the clenching of the teeth35. In EMG evaluation with the removable anterior bi-teplane, a decrease in TA and MM muscle activi-ties during the clenching of the teeth was deter-mined after the use of the appliance36.

During swallowing it was established that the EMG activities of the left and the right TA and MM muscles were within normal limits at T010 and weren’t changed significantly at T1. This may be due to the adaptation of the lips and ton-gue to the new position of the maxillary and mandibular incisors.

In the individuals with continuing growth and development, it was reported that correcting the deep overbite with molar extrusion and increasing the lower face height provided stable results15,16. Thanks to the growth potential, neuromuscular system adapts to the new vertical dimension and stability is affected positively. At the end of the evaluations after completing the fixed anterior bi-teplane therapy, 9 patients were bonded and con-tinued their fixed therapy. In 8 patients, retenti-on therapy was initialized with Hawley applian-ce with an anterior inclined plane, because of the lack of the need for the fixed therapy.

We couldn’t present the prolonged follow up of the patients because the same procedure couldn’t have been implemented in the retention period after the fixed anterior biteplane the-rapy. Investigating the effect of the activities of the masticatory muscles on relapse after therapy with long-term studies will be helpful to determi-ne the efficacy of this appliance.

Excessive overbite may limit the growth of the mandible and mandibular dentoalveolar re-gion20,21. Several studies showed an associa-tion between deep bite and temporomandibular joint disorders22,23. Increased masticatory muscle activities was also found in patients with deep bite8,10,11. There are studies supporting that the initiation of the therapy of the deep overbite in early stages would decrease the severity of the malocclusion and ease the therapy37,38.

In the literature, there is no comprehensive study evaluating the effects of the fixed anterior biteplane application in early stages on skeletal and dental structures and masticatory muscles. Considering this deficit, in this study while the effects of the fixed anterior biteplane therapy on skeletal and dental structures were evaluated, the effects on the masticatory muscles were also as-sessed by electromyography method providing quantitative data.

Early treatment of deep bite (at the ages of 8-12 years) by using a fixed anterior biteplane, effectively improved sagittal and vertical prob-lems, and no significant change was found on the activities of the masticatory muscles. Fixed anterior biteplane is a cheap and easy-fabricated appliance for deep bite treatment and might be used as an initial appliance to open the bite and correct the molar relationship.

CONCLUSIONS

At the end of the fixed anterior biteplane tre-atment;

1- Lower facial height and total facial height in-creased,

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2- Mandible moved downward and anteriorly,

3- Maxillary and mandibular incisors inclined labi-ally and mandibular posterior teeth extruded,

4- Overjet and overbite decreased,

5- The electromyographic activities of the mas-ticatory muscles did not show any important change at rest position, during the clenching of the teeth and swallowing.

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CORRESPONDING ADDRESS

Bengisu AKARSU DDS,PhDUniversity of Hacettepe, Faculty of Dentistry, Department of Orthodontics Sihhiye, 06100 Ankara-TURKEY

Phone:+903123052290 Fax: +903091138 E-mail: bengisuakarsu@yahoo.com

Geliş Tarihi : 02.10.2009 Received Date : 02 October 2009 Kabul Tarihi : 25.03.2010 Accepted Date : 25 March 2010

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