探討不同咬合指示下肌電活動、咬合接觸區域與咬合力間之關係

Abstract

實驗簡介 咬合接觸以及咬合力量的偵測是牙醫師在臨床上的每日例行公事。如何有效的紀錄咬合接觸和咬合力量，以及如何針對不同類型的贋復物做出輕重咬合之差異以利有效之調整，至今仍未有公認之客觀方式。 本實驗旨為探討在監控雙側咬肌之肌電活動下，使受試者做出不同咬合指示時使用Dental Prescale II（DPS II）試片紀錄測得之咬合接觸面積、咬合平均壓力及咬合力量，並分析肌電活動與各項咬合數據間之關係。希望建立一有效且客觀之方式以進行口腔機能診斷、全口重建治療效果評估以及植體贋復物之咬合調整。 實驗材料及方法 主要分成兩部分：首先透過體外實驗針對DPS II試片做基本性質之測試，接著以體內實驗進行不同咬合指示下之咬合數據測試。 體外實驗：使用萬能試驗機（Instron 5566, Instron Corp., USA）針對DPS II試片進行100至1200N之受力測試，觀察其測得數據之變化。 體內實驗：共有24位健康受試者，12位男性及12位女性。對健康受試者在監控咬肌肌電活動（Teethan® , MI, Italy）下針對不同咬合指示進行DPS II咬合測試，探討肌電活動和各項咬合數據之差異及趨勢。 實驗結果 體外實驗之結果顯示，在DPS II測得之接觸面積、平均壓力、最大壓力以及力量值皆和萬能試驗機之施力大小呈現正相關，其中在施力500N以下各項數據之線性關係較為明顯。此外，為比較DPS II測得力量之可信度，實驗結果顯示DPS II測得之力量值和萬能試驗機之施力之迴歸分析下，迴歸係數為為0.7819，相關係數為0.998，呈現極高度線性正相關。 體內實驗針對咬合力量－肌電活動關係之線性迴歸分析中，迴歸係數（muscle activities/bite force ratio）不論性別，慣用側和非慣用側之間無統計學上顯著差異；不論是否為慣用側，男性和女性之間亦無統計學上顯著差異。相關係數部分，咬合力量－肌電活動關係不論性別和慣用側與否都呈現高度正相關，亦即每個個體隨著肌電活動越高，DPS II測得之咬合力量就越大。 最後針對不同咬合指示下，DPS II測得之各項數據探討，結果顯示客觀視覺回饋70%和35%之間，肌電活動和各項咬合數據都有統計學上顯著差異，但慣用側和非慣用側間無顯著差異；主觀咬合指示輕重咬之間，肌電活動和各項咬合數據也都有統計學上顯著差異，但慣用側和非慣用側間無顯著差異。其中結果顯示不論輕重咬合，咬合平均壓力幾乎都在70%以上，也就是在後牙區域不論在輕重咬合皆能提供一定程度的穩定咬合；另外，在監控肌電活動下確實能夠使受試者做出輕咬以及重咬在各項咬合數據之差異。 結論 根據本實驗結果，可得出以下結論： (1) DPS II試片隨著受力增加，和各項數據（接觸面積、壓力以及力量）皆呈現正相關。 (2) DPS II試片測得之力量約為萬能試驗機真實施力值之78.2%。 (3) 個體之咬合力量－肌電活動關係皆呈現高度線性正相關。因此透過監控肌電活動以預測咬合力量之大小確為一可信之方式。 (4) 個體之咬合力量－肌電活動關係之咬合力量－肌電活動比率（muscle activities/bite force ratio）和性別及慣用側與否等差異無顯著相關。 (5) 不論客觀或主觀之咬合指示，受試者皆可以在肌電活動和各項咬合數據上做出輕重程度之顯著差異；但各項數據和慣用側與否並無顯著相關。 (6) 透過監控肌電活動，可以有效使受試者執行輕咬以及重咬之差別，此一方式有利於臨床上植體贋復物之咬合調整。

Introduction Detecting occlusal contacts and occlusal force are daily work to dentists. However, there is still no effective way to record occlusal contact and occlusal force and no valid method to adjust different types of prostheses under various occlusal tasks. In this study, we acquired occlusal data, including contact area, pressure and force from Dental Prescale II (DPS II) while monitoring the surface electromyography (sEMG) activities of bilateral masseter muscles under different occlusal tasks, then we analyzed the correlation between each occlusal data (occlusal contact area, pressure and force) and sEMG activities. The aim of this study was to establish a valid and efficient way in our daily practice for diagnosis in oral function, occlusal adjustment in implant prostheses and evaluation of the treatment results in full mouth rehabilitation. Materials and Methods This study had two parts. In vitro study: using universal testing machine (Instron, Instron Corp., USA) to provide standard force from 100N to 1200N to test the DPS II sample and then analyze the acquired data with linear regression analysis. In vivo study: there were 24 healthy participants, 12 men and 12 women. Our in vivo study was to explore the acquired data from DPS II while monitoring the surface EMG activities (Teethan® , MI, Italy) of bilateral masseter muscles under different tasks, including objective visual feedback tasks (70%, 35%) and subjective heavy and light force tasks. Results The results from our in vitro study showed that the measured contact area, average pressure, maximum pressure and force from DPS II were all highly positively correlated with the standard force from universal testing machine, and the positively linear relations were more evident with the standard force below 500N. Moreover, to investigate the reliability of the measured force from DPS II, the linear regression analysis showed that the regression coefficient was 0.7819, the correlation coefficient was 0.998, which represented the extremely high positively linear correlation. The first results from this in vivo study were about bite force-EMG relation. There was no significant difference in muscle activities/bite force ratio regardless of gender and preferred side. In terms of correlation coefficient, the results showed every bite force-EMG relation exhibited high positive correlation. It meant that when we observed higher EMG activities in participants, we expected them to have higher bite force. The last results from this in vivo study were about the analysis of measured data (sEMG activities, occlusal contact areas, occlusal average pressure and occlusal force) from DPS II under different tasks. The results from visual feedback instructions showed that there were significant differences in every measured data between 70% and 35% instructions, but there was no significant difference between preferred side and non-preferred side in every measured data; the results from heavy/light force instructions showed that there were significant differences in every measured data between heavy and light force instructions, but there was no significant difference between preferred side and non-preferred side in every measured data as well. In addition, the measured occlusal average pressure from DPS II was mostly above 70% regardless of heavy or light force instructions, and it meant that the posterior tooth played an important role in posterior support regardless of heavy or light force. Last but not least, we could conclude that participants were able to make significant differences in every measured data during heavy and light force tasks while monitoring sEMG activities of bilateral masseter muscles and this could be a valid and objective way for us to perform occlusal adjustment in delivering implant prostheses. Conclusions Based on the results from this study, we can make conclusions as followed: (1) The measured data (contact area, pressure and force) from DPS II were positively correlated with the standard force exerted. (2) The measured force from DPS II was about 78.2% of the standard force exerted. (3) The bite force-EMG relation showed high positively linear relation in every subjects. (4) The muscle activities/bite force ratio showed no significant difference regardless of gender and preferred side. (5) Regardless of objective or subjective instructions, participants were able to make significant differences with heavier and lighter force in every measured data; however, there was no significant difference between preferred side and non-preferred side. (6) Monitoring the EMG activities could be a valid and objective method to make subjects capable of performing heavy and light force with significant differences, and this method could be use in occlusal adjustment on implant prostheses.