由台灣人三牙根下顎第一大臼齒的探討到鎳鈦旋轉器械應用於根管清創研究

Prevalence and Morphometric Study of Three-rooted Mandibular First Molars in a Taiwanese Population and Shaping Performance Evaluation Using NiTi Rotary Instrumentation Technique

涂明君(Ming-Gene Tu)

指導教授 ： 蔡吉政

高雄醫學大學/口腔醫學院/牙醫學研究所/博士(2008年)

摘要

壹、
本研究的目的是以回溯性研究利用二維牙根尖X-光片及三維牙科電腦斷層影像分析。臺灣人下顎第一大臼齒發生第三牙根的機率，及其對稱性發生比例，並針對有第三牙根之牙齒作形態之觀察分析以期輔助診斷與增進根管治療之成功率。收集731個既存牙根尖x-光片病例檔中篩166病例及I-Cat影像資料庫中568筆病例篩選71 個雙側下顎第一大臼齒健全存在之病例。記錄分析下顎三牙根第一大臼齒的發生數目、性別比、單雙側發生的比例；並針對有第三牙根者之各牙髓根管入口長軸角度分析與根管入口間距離做探討，所有的收集與測量的數據輸入SAS軟體1.3版本，進行統計分析。在本研究以2D根尖X-光片評估台灣人下顎三牙根第一大臼齒的發生率(21.09%)比以3D斷層掃描影像統計所得出的數據(38.03%)較少。台灣人下顎三牙根第一大臼齒發生率以兩種方式分析結果相同點是: (1)右側發生率高於左側 (2)男女性發生率相當 (3)2/3的受測者會對稱性發生。遠心舌側根管的偏向舌測的角度比其他三個根管(近心頰測、近心舌測、遠心頰測)角度為大(男性: 30° vs. 16.4°、 13°、 22.7°；女性: 32° vs. 16.3°、13°、20°)。遠心舌側根管入口與近心頰側根管入口、近心舌側根管入口、遠心頰側根管入口各有 2.7 mm，3.5 mm 及4.4 mm的距離。此數據可供牙醫師做根管治療的參考資訊，增加治療成功率。

貳、
本計劃目的是比較不同年級牙醫學生對三類鎳-鈦旋轉式器械的操作效率及修形品質的差異性評估，找出適合初學者牙醫學生最適合的鎳-鈦旋轉式器械學習以供教學之憑據。兩組在學的牙醫系四、五年級學生在同等環境下學習三種馬達帶動式鎳-鈦旋轉式器械：ProTaper, HERO shaper®，K3等系統清創擬彎曲根管的透明樹脂塊。所有術前與術後修形的樹脂塊經過掃描、紀錄，以重疊影像對根管自牙根尖0-4 mm處作比較。所有修形根管分別維持在：ProTaper組根尖孔25號、0.08錐度；HERO Shaper®組根尖孔30號、0.04錐度；K3組根尖孔25號、0.06錐度；根尖孔保持10號的通暢性。收集所有的資料與數據作統計分析。本實驗結果：就三種旋轉式器械操作三組花費時間牙五比牙四短，在ProTaper 及K3等系統兩組有顯著差異(p ＜.001)，而在HERO Shaper® 兩組花費時間在四分鐘內且兩組無顯著差異；根尖4 mm處兩組學生在維持修形寬徑(Total canal width)與再現性(reproducibility)以ProTaper最好、 HERO Shaper®最差。而在維持修形管腔原曲度方面(centering canal shape)則牙五在三種器械上操作成品比牙四較佳。鎳-鈦旋轉式器械再現性因學過傳統不銹鋼牙銼針修形的牙五與未學過牙四的學生而有所差異，操作時間會因練習及熟練度有所縮短，但整體而言兩組0-4 mm根尖區的修形均具有相
當的連續性錐度外型(Continuous tapering conical shape)符合根管清創標準，因此牙髓病學的課程安排及教學可以盡早以鎳-鈦旋轉式器械作為實習課操作主軸，再輔以傳統不銹鋼器械根管清創教學，可以建立牙醫學生牙髓病實習操作之學習信心。

關鍵字

二維三維影像 ； 三牙根下顎第一大臼齒 ； 遠心舌側根管 ； 鎳-鈦旋轉式器械 ； 擬彎曲根管的透明樹脂塊 ； 根管修形

並列摘要

Part I
The study of tooth and root canal anatomy is important for dental practice and for reasons of anthropologic significance. The purpose of this retrospective study was to investigate the frequency of the occurrence identified by 2D periapical radiography and 3D dental CT images in order to determine the gender difference of three-rooted mandibular first molars in a Taiwanese (Chinese) population and to investigate the morphology of the extra distolingual roots by 3D images analysis. 731 patients’ periapical radiographs and a total of 568 I-Cat CT images were screened for 2D and 3D study respectively. Data were analyzed the means by Chi-square tests. Angulations and distances were calculated by an ImplantMaxTM software system and data were compared by t-test. The prevalence of three-rooted mandibular first molars was 21.09% and the bilateral incidence of a symmetrical distribution was 68.57% as the results from the 2D investigation. The prevalence of three-rooted mandibular first molars was 38.03%, and the bilateral incidence of a symmetrical distribution was 59.26% as the results from the 3D investigation. There were no significant difference in the incidence of three-rooted teeth on the right side to the left side, unilateral or bilateral and gender in both 2D and 3D evaluation methods. The lingual angulation of the distolingual canal was larger than other three canals (mesiobuccal, mesiolingual and distobuccal) (in male: 30o vs. 16.4o, 13o, 22.7o; in female: 32o vs. 16.3o, 13o, 20o). Orifice distance from the distolingual orifice to mesiobuccal orifice was 4.4 mm, to mseiobuccal orifice was 3.5 mm, and to distobuccal orifice was 2.7 mm by the 3D analysis. Clinicians should be aware of the high racial prevalence of the distolingual root in mandibular first molars among Taiwanese (Chinese) population before initiating endodontic treatment. If there was a distolingual root existed in the mandibular first molar, distance estimation as our results described might be valuable for dentists to achieve successful endodontic treatments.
Part II
The aim of this study is to evaluate the shaping performance using three nickel-titanium (NiTi) rotary instrumentation techniques in two different grade dental students. Modern rotary NiTi instruments are known to produce round root canals with no or minimal apical transportation of curved canal. Two groups of undergraduate dental students, without experience in NiTi rotary instrumentation, were taught and trained three different NiTi rotary instrumentation techniques: ProTaper (Dentsply Co.), HERO Shaper® (MicroMega Co.), K3 system (SybronEndo Co.). Under the same condition, the subjects all used the same rotary armamentarium and 40 degree curved resin blocks (ENDO-TRAINING-BLOC, 0.02 taper, CH-1338, Dentsply), and were allocated the same duration of practice periods. Resin blocks were prepared and the apical portion preparation finished at ProTaper F2 sized 0.25 mm in diameter and 0.08 taper, HERO Shaper® sized 0.30 mm in diameter and 0.04 taper, and K3 system sized 0.25 mm in diameter and 0.06 taper. Canals were scanned before and after preparation. Composite images were prepared for estimation. Material removed, canal width and canal deviation was measured at five levels, beginning from the apex 0 mm to 4 mm by the AutoCAD 2004 software. The time of preparation and instruments failure were also recorded. Data were analysed using Wilcoxon’s rank-sum test. Results from the dental students’ groups: The preparation time between the two groups was statistically different by using ProTaper and K3 system. The preparation time using HERO Shaper® was within 4 minutes and was not statistically significant between both groups. Comparing the apical 0-4 mm canal width and canal shape reproducibility, ProTaper was the best and HERO Shaper® the worst. The fifth-year group performed better centering canal shape performance than did the fourth-year group using three types of NiTi instruments. Although the senior group performed significantly better in the preparation time and canal shaping than did the junior group, but both of the two groups could perform an acceptable continuous tapering conical shape at 0-4mm of the simulated curved canal resin blocks using three NiTi rotary instruments. The results indicate this NiTi rotary instrumentation technique could integrate easily into traditional endodontic laboratory class to motivate the dental students’ learning interest.

並列關鍵字

2D periapical radiography ； 3D I-Cat dental CT ； anatomic NiTi rotary instruments ； root canal preparation ； simulated canal resin block

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壹、

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