口內掃描機不同咬合紀錄掃描模式對牙冠外形重建的影響

研究目的自從1980年代，CAD/CAM進入牙科領域後，牙科數位化開始蓬勃發展，且適用範圍越來越廣。CAD/CAM的第一個步驟為口內資料取得並轉成數位化檔案，一般傳統以印模材印模後轉印成石膏模型，再經由掃描石膏模型獲得檔案。口內掃描機(intraoral scanner)發明後直接將口內狀況掃描成數位化檔案，使得口內資料取得簡單、快速、並減少許多誤差的可能，如印模材和石膏模型的膨脹收縮導致的變形、印模材的污染等。而口內掃描機在操作過程上的高效率成為牙科數位化的近程發展的趨勢。已有不少研究著重在各家口內掃描機在掃描精準度的呈現，或是製成補綴物的密合度上。目前尚未有針對口內掃描機對於咬合及補綴物外形呈現的精準度做比較研究，且以TRIOS (3Shape, Denmark)口內掃描機為主體的研究仍十分少見。因此，本研究以TRIOS掃描機在不同掃描設定下所設計與製作的補綴物外形來做比較，以探討口內掃描機在補綴物外形及咬合再現的表現。材料與方法：取一標準樹脂牙模型，右下第一大臼齒以全瓷冠修磨方式修形。以TRIOS數位口內掃描機在牙齒修型前先掃描樹脂牙，以此為標準設定，再以數位口內掃描機兩種不同咬合紀錄方式掃描修磨過的牙齒模型。Ａ組為五組只紀錄頰側的咬合紀錄，Ｂ組則為五組紀錄頰側與舌側兩組咬合紀錄。紀錄完成的檔案轉移至牙冠設計軟體(3Shape Model Designer)中，以同一位操作者在十組支台齒上設計全瓷牙冠。設計完成的牙冠檔案與標準設定檔案匯入三維模型比較軟體(Geomagic studio 2012)，以邊緣和牙冠內部對齊為比較基準面，比較A, B兩組與標準設定的牙冠外形差異度，並繪製出彩圖代表各部份不同距離差異。將Ａ組的五組設計好的牙冠檔案以CAD/CAM製作成實體全鋯冠，以三維模型掃描機(3Shape D800 3D scanner)掃描此五個全瓷冠成三維檔案，此五個檔案為AF組。再將此五組檔案以同樣方式與標準設定比較。三組與標準設定所得外型之所有平均距離差和絕對值平均距離差以Mann-Whitney U 檢定分析，定義p=0.05。結果：平均距離（絕對值平均距離）差：A組 -0.220 (0.447) mm, B 組 -0.089 (0.480) mm，兩組經由統計分析後平均距離之 p值為0.690，絕對值平均距離之 p值為1，兩者皆大於所設定之顯著性指標 p=0.05，表示A, B兩組與標準設定的牙冠外形並沒有顯著性差異。而AF組的平均距離（絕對值平均距離）差為 -0.132 (0.388) mm，與Ａ組統計分析後之平均距離p值為0.690，絕對值平均距離p值為0.841，兩者接大於所設定之顯著性指標p=0.05。而由距離差異彩圖可見，軟體設計牙冠相較於標準設定牙冠的外形較為外凸，尤其在咬合面近心處與頰側處。結論：數位印模額外增加舌側咬合紀錄並不會影響到牙冠外形的精確性。以CAD/CAM製作出來的補綴外形與軟體內建之外形比較並無顯著差異性。以內建軟體製作之牙冠有較凸之外形。

關鍵字

數位口內掃描機； TRIOS ；數位印模；牙冠外形；咬合紀錄

並列摘要

Backgrounds and Objectives: Since the introduction of the computer-aided design/computer-aided manufacturing technology (CAD/CAM) in the early 1980s, continuous advancements in dental digital field have evolved, and the indication spectrum has been widely expanded. The data capture component, also called digitizers, is the basic inevitable component used before further processes can take place. And with the introduction of intraoral scanner in dental field, the data acquisition becomes much easier, time saving, and prevent potential errors conventional impression usually makes, such as expansion, shrinkage, and distortion of impression materials and/or the gypsum master model, disinfection of impression......, etc. The efficiency of intraoral scanner makes it a trend in dentistry nowadays, and there are more and more studies evaluating the precision of digital scanning or the fitness of prosthesis fabricated via intraoral scanner digitization procedure. So far, the evaluation of morphology precision made by intraoral scanners are not available. Therefore, the aim of this study was to evaluate the crown morphology rebuilding of the abutment tooth by using the TRIOS (3Shape, Denmark) intraoral scanner in different scanning modes. Materials and Methods: An acrylic model of a mandibular first molar was prepared to receive a full ceramic crown. Digital impression was taken using TRIOS intraoral scanner before preparation as reference (Ref.).And the digital prepared impression was taken by two different methods, group A was only taking buccal bite registration, and group B was taking both buccal and lingual bite registrations. The digitized data were transferred into model designer software for full ceramic crown design, and the designed data were entered into 3D distance inspection software, which superimposed the records (A, B groups and Ref.) by fitness in marginal and internal areas, calculated crown contour deviation for every pixel, and color-coded the results to aid visualisation. Then the five digital crowns designed in A group were fabricated to real all zirconia crown by CAD/CAM, and the five all zirconia crowns were digitized by an 3D scanner (3Shape D800), and the digitized files were compared with the Ref. as the same way just mentioned. Furthermore, the deviation and absolute deviation data were analysed statistically with Mann-Whitney U test. (p=0.05) Results: Mean deviation (absolute deviation) were: A group -0.220 (0.447) mm, B group -0.089 (0.480) mm. Difference between two groups were not statistically significant at P>0.05 (mean deviation, p= 0.690; mean absolute deviation, p=1) Mean deviation (absolute deviation) of AF group were: -0.132 (0.388) mm. Difference between A and AF group were not statistically significant either (mean deviation, p= 0.690; mean absolute deviation, p=0.841) Qualitatively, all zirconia crowns contour were overcontour especially on mesial occlusal surface and buccal contour. Conclusions: Extra lingual bite registration did not influence the contour appearance on the designed tooth model. The restorations fabricated by CAD/CAM do not have significant difference compared with the designed digital models. The crown contours designed by model designer software were usually overcontour

並列關鍵字

intraoral scanner ； TRIOS ； digital impression ； crown morphology contour ； bite registration

參考文獻

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口內掃描機不同咬合紀錄掃描模式對牙冠外形重建的影響

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