顏面不對稱骨性三級異常咬合患者的咀嚼肌肌電活性與咬合力之相關性

Correlation between Electromyographic Activity of Masticatory Muscles and Occlusal Force in Patients with Skeletal Class III Malocclusion and Facial Asymmetry

徐子航(Tzu-Hang Hsu)

指導教授 ： 陳羿貞

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202001231

摘要

目的
顏面不對稱骨性三級異常咬合不僅影響顏面美觀與咀嚼功能，也會影響咬合力及咀嚼肌活性的表現。然而，在過去的臨床經驗中，我們缺乏可靠、準確的儀器量化病患在接受矯正治療之後所得到的改善效果，因此本研究期待藉由科學儀器量化探討齒顎形態與咬合力及咀嚼肌肌電活性的相關性，以期在為患者進行齒顎矯正合併正顎手術治療改善顏面外觀的同時，亦能兼顧生理健康功能的評估。
研究程序及方法
本研究對象為42位接受齒顎矯正合併正顎手術治療的骨性三級異常咬合合併下顎偏斜的患者，於治療前拍攝錐狀射束斷層掃描(CBCT)，透過三維影像測量分析顏面不對稱程度及下顎骨偏斜情形，依照chin deviation和ramus width difference相對的程度差異分類：Group 1病患其下頷點偏斜大於下顎枝寬度差異，且下頷點偏斜側的下顎枝寬度較非偏斜側寬；Group 2病患其下頷點偏斜小於下顎枝寬度差異，且下頷點偏斜側的下顎枝寬度較非偏斜側寬；Group 3病患其下頷點偏斜側的下顎枝寬度較非偏斜側小。
利用數位咬合分析儀器T-Scan III檢視緊咬時的咬合力大小及分布、咬合接觸面積大小及分布。另以表面肌電儀器BioEMG III同步測量咀嚼肌肌電活性大小及其對稱性，並計算asymmetry index、torque coefficient及咬合力轉換效率等指標。此外，亦紀錄患者的主觀慣用咀嚼側。統計分析先以one-way ANOVA檢定三組顏面不對稱患者之間的差異性，再進行有關咬合力與咀嚼肌活性的各項參數之間的相關性分析。
結果
最大咬合力與最大咬合面積呈現高度正相關(Spearman’s ρ = 0.930)，且兩者皆與咀嚼肌肌肉活性總和呈現中度正相關(ρ = 0.461)。然而，咬合力測量及肌肉活性指標在三組之間並無顯著差異，但各組內齒顎形態與咬合及肌肉活性指標之相關性卻呈現不同趨勢，以下所列相關係數皆具有統計顯著性(P<0.05)。
在Group 1中，chin deviation與偏移側顳肌活性呈現高度負相關(ρ = -0.712)且與偏移側整體咀嚼肌活性呈現中度負相關(ρ = -0.494)。Ramus width difference與偏移側顳肌活性、整體咬肌活性總和、最大咬合力及最大咬合面積呈現中度負相關 (ρ = -0.605, -0.540, -0.634, -0.564)。在Group 2中，Chin deviation與偏移側的咬合力呈現中度負相關(ρ = -0.636)，Ramus width difference與偏移側的咬肌肌肉活性則為中度正相關(ρ = 0.661)。在Group 3中，Chin deviation與偏移側的咬合面積存在高度負相關(ρ = -0.783)，ramus width difference與最大咬合面積及最大咬合力皆呈現中度正相關(ρ = 0.700, 0.667)，而顳肌與咬肌肌肉活性與Chin deviation及Ramus width difference則無顯著相關性。
慣用咀嚼側有較高的平均咬合力及咬合接觸面積。慣用右側咀嚼的患者右側咬合力平均大於左側6.32%且右側咬合面積平均大於左側7.44%；而慣用左側者左側咬合力平均大於右側19.34%，左側咬合面積平均大於右側11.96%。咬合力轉換效率受到咬合接觸面積影響最甚，當最大咬合接觸面積越大時，咬合力轉換效率越好(ρ = 0.520)。另外，在Group 1病例中，當ramus width difference差異越大時，咬合力轉換效率越差(ρ = -0.637)。

結論
綜合而言，咬合接觸面積和本研究探討的眾多因素皆存在顯著相關性，隨著顎骨歪斜的程度越大，咬合接觸面積呈現下降的關係。當咬合接觸面積下降，不僅在咬合力、顳肌活性、咬肌活性、咬合力轉換效率也隨之下降。而慣用咀嚼側通常有較多的咬合接觸面積以及較大的咬合力。

關鍵字

顏面不對稱 ； 骨性三級異常咬合 ； 咀嚼肌活性 ； 咬合力 ； 咬合接觸面積 ； 咬合力轉換效率

並列摘要

Objective
Previous studies showed the correlation among facial asymmetry, occlusal force, and masticatory function. However, few studies reported difference between the deviation and non-deviation sides in the Class III patients with mandible deviation. The purpose of this study was to investigate the correlation between masticatory muscle activity and occlusal force in skeletal Class III patients with facial asymmetry, and the changes of functional characteristics after surgical-orthodontic treatment.

Material and methods
This study included a total of 42 patients requiring surgical-orthodontic treatment to correct dentofacial deformity. All the patients presented with Angle Class III malocclusion on at least one side of the dentition. Pre-treatment CBCT images were acquired. Then the patients were categorized into three groups according to the direction and magnitude of transverse ramus discrepancy relative to chin deviation. Groups 1 and 2 included patients with ramus and chin shifted to the same side. Patients in Group 1 exhibited greater chin deviation than ramus discrepancy and the condition was reversed for Group 2. Group 3 patients had a larger ramus width contralateral to the side of menton deviation.
Digital occlusal analyzer (T-scan III) was used to examine the occlusal contact area and occlusal force during 2 seconds clenching while the surface EMG of the temporalis muscle and masseter muscle was recorded by using BioEMG III. The muscle activities at the deviation and non-deviation sides were calculated, including asymmetry index, torque coefficient, and occlusion efficiency. In addition, the patients were asked to report their preferred chewing side. The data were analyzed with one-way ANOVA to investigate differences among the three patient groups with different types of facial asymmetry. Spearman correlation analysis was conducted to check the correlation between the asymmetry parameters of masticatory muscle activity and those of occlusal force.

Results
The study sample consisted of 42 skeletal Class III with facial asymmetry patients. There was no significant difference between 3 groups in occlusion and muscle balance, but the correlation between occlusion and muscle balance was different in 3 groups. The significant results of correlation analysis were listed.
The maximal occlusal force was highly correlated to the maximal occlusal contact area (Spearman’s ρ = 0.930). Besides, both are moderately correlated to total masticatory muscle activity (ρ = 0.461). In group 1, chin deviation was highly negatively correlated to temporalis muscle activity (ρ = -0.712) and moderately negatively correlated to both masticatory muscle activity on the deviated side (ρ = -0.494). Ramus width difference was moderately negatively correlated to maximal occlusal force, maximal occlusal contact area, temporalis muscle activity on deviated side, and total masseter muscle activity on the both side (ρ = -0.634, -0.564, -0.605, -0.540). In group 2, chin deviation was moderately negatively correlated to occlusal force on the deviated side (ρ = -0.636). Ramus width difference was moderately correlated to masseter muscle activity on the deviated side (ρ = 0.661). In group 3, chin deviation was highly negatively correlated to an occlusal contact area on the deviated side (ρ = -0.783). Ramus width difference was moderately correlated to the maximal occlusal contact area and maximal occlusal force (ρ = 0.700, 0.667). Masticatory muscle activity was not significantly correlated to skeletal asymmetry.
The occlusal force and contact area were significantly larger on the preferred chewing side. Right-side chewer’s mean maximal occlusal force was 6.32% larger and the mean maximal contact area was 7.44% larger on the right side. Left-side chewer’s mean maximal occlusal force was 19.34% larger and the mean maximal contact area was 11.96%% larger on the left side. The occlusal contact area was the determining factor of occlusion efficiency. Occlusion efficiency was moderately correlated to the occlusal contact area (ρ = 0.520). Besides, in group 1, occlusion efficiency was negatively correlated to ramus width difference (ρ = -0.637).

Conclusion
Taken together, the occlusal contact area was significantly correlated with most parameters investigated in this study. The occlusal force, temporalis muscle activity, masseter muscle activity, and occlusion efficiency increased with higher occlusal contact area. The occlusal contact area and occlusal force were both higher on the preferred chewing side than the contralateral side. In most cases, the occlusal contact area was negatively correlated to the amount of chin deviation.

並列關鍵字

Facial asymmetry ； skeletal Class III malocclusion ； masticatory muscle activity ； occlusal force ； occlusal contact area ； occlusion efficiency

參考文獻

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