第一乳臼齒與對應不鏽鋼牙套之形態比較

Comparison of Morphology of Primary First Molars with Related Stainless Steel Crowns

趙子婷(Tzu-Ting Chao)

指導教授 ： 蔡恒惠

臺北醫學大學/口腔醫學院/牙醫學系碩博士班/碩士(2014年)

https://doi.org/10.6831/TMU.2014.00025

摘要

當兒童的乳臼齒發生大範圍的齒質缺損時，不鏽鋼牙套(stainless steel crown, SSC)是最好的復形物，能帶來最好的牙冠全面包覆，且有堅固耐用的優點，在齲齒率盛行的台灣，不鏽鋼牙套的應用特別重要。但是牙醫師在施行不鏽鋼牙套的修型時，往往發現預製牙套的尺寸選擇以及牙套修剪、調整，都是棘手的問題；這些問題可能拖延臨床治療時間，造成兒童看診的不適，長久來說也可能導致牙套提早脫落，或有牙套周圍牙齦發炎及牙齒再次蛀蝕的隱憂。一般公認乳牙形態之中，最特別的當屬第一乳臼齒，但是目前關於台灣兒童第一乳臼齒的形態特色，很少被研究；而台灣地區使用的預製型不鏽鋼牙套，都是由國外進口，也可能與國人之牙齒形態有所差異。因此本研究目的是希望藉由探討台灣地區第一乳臼齒與進口不鏽鋼牙套的形態關係，探索台灣兒童的乳牙特徵，並找出有效挑選及修剪不鏽鋼牙套方式，有效率且安全地為兒童患者製作牙套，並提高牙套固位性，避免周圍牙齦發炎。在本研究中，我們採用63位(33位女性，30位男性)台灣地區兒童的上下顎牙齒石膏模型，及市售全尺寸上下右側第一乳臼齒不鏽鋼牙套，均使用Microscribe G2三次元測繪臂進行三度空間立體掃描，將模型及牙套的座標輸入電腦。再者，我們利用電腦軟體Graph-R繪製牙齒與牙套之立體模型，並利用該軟體觀察牙齒與牙套在咬合面及頰側面的特徵，並指出相異之處。本研究發現，台灣地區兒童的下顎第一乳臼齒近遠心徑在男女生上的平均值分別7.75±0.37mm，女性為7.41±0.41mm (Student t test; p＜0.001)，有男大於女的特色，但是在上顎第一乳臼齒的大小卻沒有性別差異。另外目前的兒童牙科教科書中的下顎第一乳臼齒咬合面，皆呈現一狹長的菱形，近遠心徑明顯大於頰舌側徑，但本研究發現，台灣地區有58.73%咬合面呈現近遠心徑近似於頰舌側徑的方形或三角形，並且其近遠心徑與頰舌側徑比值(MD distance/BL distance ratio)與菱形的下顎第一乳臼齒有統計上的差異(ANOVA; p＜0.001)，這樣的特色可能增加操作者調整不鏽鋼牙套的困難。而上顎的不鏽鋼牙套，施作時可能遇到牙套頰舌側徑不足的問題。依據本研究結果，本研究假說：市售牙套與台灣地區兒童之第一乳臼齒形態互異，應可成立。並且可作為未來不鏽鋼牙套相關設備開發及牙齒3D立體形態後續深入研究之參考資料。

關鍵字

第一乳臼齒 ； 不鏽鋼牙套 ； 乳牙形態

並列摘要

The first choice of restoration for a severely decayed primary molar is a stainless steel crown (SSC). The primary first molars not only have unique shape but also have more variations in morphology than any other permanent or primary teeth. Many dentists consider that there is difficulty in SSC fabrication of primary first molar during clinical practice.
Accurate quantification of variation in tooth shape is important in studies of dental morphology. The aim of this study was to examine some significant and clinical relevant aspects of the primary first molars in Taiwanese children and the related SSC (3M ESPE, No.2~No.7), such as the crown mesiodistal(MD) distance / buccolingual(BL) distance ratios.
The materials comprised the dental casts of 63 children (33 girls, 30 boys) who have no caries, no dental fillings and intact clinical crowns of all primary molars. The right primary first molars of each dental casts and SSC were scanned by Microscribe G2 Digitizers (Immerion Inc., California, USA) to build 3D data set. Standardized photographs of the occlusal surfaces of the dental casts and SSCs were obtained. All digital information was inputted into a personal computer. The 3D data set of dental casts and SSCs were translated by software Graph-R (Graph-R Project, Japan) for 3D drawing and calculated by Microsoft Excel (Excel 2013,Microsoft corporation, Washington, USA) and software Keynote (Keynote version 6.1,Apple Inc., California, USA) for data analysis.
Our results showed that the MD distance of lower primary first molar showed a statistically significant difference between boys (7.75mm) and girls (7.41mm) (Student T test; p <0.001). The crown size of lower primary first molars was greater in boys than that of girls in Taiwan. The crown size of upper primary first molar showed no significant difference among the genders. Besides, the textbooks of pediatric dentistry always describe the occlusal surface of lower primary molar and related SSC as a rhomboid shape. However, We found that 58.73% of Taiwanese lower primary molar showed a triangle or square shape in the occlusal surface. The triangle/square molars (1.04~1.13) had statistically significant shorter mesiodistal/buccolingual distance ratio (MD/BL ratio) than rhomboid molars (1.23) (ANOVA; p <0.001). These results demonstrate that there is difference between the morphology of Taiwanese primary fist molar and related 3M ESPE SSC. Understanding the morphologic characteristics of different types of primary molars is important for the dentist to prepare the decayed tooth and apply the preformed SSCs to fit the tooth. According to these results, we suggested the method presented here is feasible for further more advanced human studies .

並列關鍵字

primary first Molars ； stainless steel crown ； SSC ； morphology

參考文獻

32. 林妤珊,黃純德,陳俊志. 2014.臺灣六到十二歲學童之第一大臼齒齲齒型態之演變(Changes of First Permanent Molars of Children Aged from Six to Twelve Years Old in Taiwan).臺灣兒童牙醫學雜誌.14:2 2014.06[民103.06].頁55-60.

2. Abu Alhaija ES, Qudeimat MA. 2003. Occlusion and tooth/ arch dimensions in the primary dentition of preschool Jordanian children. Int J Paediatr Dent. 13:230-9.

6. Bernardini F, Rushmeier H. 2002. The 3D Model Acquisition Pipeline. COMPUTER GRAPHICS forum. 21:149–172.

10. Koora K, Sriram CH, Muthu MS, Chandrasekhar RR, Sivakumar N. 2010. Morphological characteristics of primary dentition in children of Chennai and Hyderabad . Journal of Indian Society of Pedodontics and Preventive Dentistry, Vol. 28, No. 2, April-June, 2010. p. 60-67

11. Mahtab M, Maryam M, Gita R, Mehran R. 2011. Microleakage of Adhesive and Nonadhesive Luting Cements for Stainless Steel Crowns. Pediatr Dent. 33:501-4.