| Abstract: | 經過根管治療的牙齒，大部份都會因齒質過度耗損而需要考量使用固定牙冠?復。一般而言，在製作?復牙冠前有必須要在牙根內鑄造牙根釘柱(post)，以增加?復牙冠柱心(core)與齒質的強度與固持力。在牙根釘柱空間修形(post space preparation)的過程中，需要移除已封填在根管內齒冠部分的馬來膠材料(gutta-percha)，便有可能會造成根尖封填材料之鬆脫而影響牙根尖之緊密封閉(seal)能力，導致根管可能有再污染(percolation)的途徑與機會。本論文研究目的在探討牙根釘柱修形空間與根管封填方法(obturation technique)，根管充填糊劑種類(root canal sealer)，根管封填材料移除時機(timing)與馬來膠的移除長度(length)等相關影響因素，是否會有影響根尖密閉能力的可能。
總數190顆單根管牙齒，經髓腔開口，工作長度量測後，使用15號不銹鋼根管銼針(stainless steel file)確認根管路徑後，使用慢速鎳鈦旋轉銼針(rotary nickel-titanium file)以冠部向下修形方式(crown-down technique)，配合沖洗溶液作根管清創擴大修形至根尖直徑為0.30mm及6.0%錐度。以隨機抽樣分組方式，分別用側方擠壓馬來膠充填方法(lateral compaction technique)(30顆)、垂直擠壓馬來膠封填方法(vertical compaction technique)(30顆)、熱塑馬來膠封填方法(thermoplasticized gutta-percha technique)(30顆)等三種方法予以根管封填，另外同時分別以pulp canal sealer(30顆)、tubliseal EWT(30顆)、pulp canal sealer EWT(30顆)等三種不同成份與硬化時間(setting time)的根管充填糊劑予以根管封填。最後使用10顆完全不進行封填或封填後不進行牙根釘柱空間修形的牙齒為控制組。根管封填完成後以模擬口腔環境溫度置放於攝氏370下保存，再分別於封填後瞬間、第3天與第7天三個時間點，利用擠壓針(plugger)以加熱方式將充填根管內靠近齒冠部分(coronal)的馬來膠移除至剩餘約5.0mm的長度。隨後使用2.0﹪甲基藍染料(methylene blue dye)浸泡7天後，再利用骨鑿(chisel)將牙齒依唇－舌方向縱裂為二。最後，在立體放大顯微鏡下配合使用微米尺檢視甲基藍染色劑在根尖微滲漏(microleakage)之長度，記錄資料並以SPSS-One Way ANOVA Test統計分析，分析在不同時間內移除根管內以不同方法封填與不同根管充填糊劑封填的材料，其影響根尖密閉能力的不同影響結果。
根據實驗結果與統計分析發現，使用擠壓針加熱方法移除根管內馬來充填膠後出現的根尖滲漏情形中，以垂直擠壓馬來膠封填方法確認有比較不易滲漏的結果，同時三種不同根管充填劑中以pulp canal sealer EWT的滲漏比其他兩種根管充填糊劑少，而馬來膠移除的長度以5.0厘米為最佳。此外，牙根釘柱修形時間在第7天的滲漏情形也最少。因此本次研究的結果針對臨床牙根釘柱空間修形的時間建議應該考慮根管充填糊劑的成份與硬化時間的關係。如果根管充填糊劑能夠完全硬化後再進行牙根釘柱空間修形製備會有比較佳的根尖密閉性結果。順應如上的建議與研究的結果，臨床上牙根釘柱空間修形的時機建議必須於?復牙冠齒質開始修形削磨前進行準備，如此在根管封填材料完全硬化的情況下，應該會保持較佳的根尖密閉性的效果。惟目前臨床上?復牙冠牙橋的治療計劃，有時候會需要考量其他諸如牙齒美觀，咬合功能等因素，有可能要擬定早期完成?復的要求。因此，需要有更進一步的研究並探討贗復治療與根管治療間彼此的相互協調適應情況，才會獲得更有實效與理想的治療結果，不致破壞根尖封填材料的密閉性而影響根管治療的成功結果。
Endodontically treated teeth usually required intracanal posts in purpose to reinforce the strength of the tooth structure and the retention of the crown. Post space preparation are frequently needed before crown fabrication but it is important not to disrupt the integrity of the remaining filling material that is provided the apical seal. The purpose of this study was to evaluate the effect of different obturation techniques, the types of root canal sealers, the methods and timing of filling material removal during post space preparation had on the apical seal of root canal fillings.
A total of 190 extracted single root canal teeth were collected and stored in formalin solution. The teeth were extracted because of severe periodontal problem or orthodontic reason. The apex was completely formed and the apical constriction had not been destructed. All samples were accessed with a #4 round diamond bur through the occlusal surface and working length were measured with a #15 k-file. The tooth was then prepared utilizing rotary NiTi instrument by crown-down preparation technique.
All the prepared teeth were stored in the physiological saline and randomized divided into two parts and seven groups. The specimens were then obturated as following: lateral compaction method (30 teeth), vertical compaction method (30 teeth), thermoplasticized warm GP method (30 teeth), and root canal sealers using pulp canal sealer (30 teeth), sealapex EWT(30 teeth), pulp canal sealer EWT(30 teeth). Thereafter, the apical 5.0 of the filling materials was left after the coronal portion were removed with hot plugger within immediate after filling, 3, and 7 days after root canal obturation. Finally, 2.0% methylene blue dye was used to demonstrate the microleakage of the apical seal after the above managements. The results were measured, recorded, and statistically analyzed using SPSS-One WAY ANOVA test.
According to the experimental results and statistical analysis, vertical compaction method was superior to lateral compaction method in terms of yielding less dye leakage when heat plugger was to remove root canal filling material. Moreover, the least amount of dye leakage exists when the root canal was filled with vertical compaction using pulp canal sealer EWT. Finally, dye penetration was found more inferior when post space preparation occurs on the 7 days after obturation. In purpose to sustain proper apical seal, it is recommended that post space are better prepared until crown fabrications are ready to be initated. Various techniques, filling materials and ingredients such as AH-plus resin sealer or resilon, a new root canal filling material with methacrylate based, are available for root canal therapy and some esthetic and financial consideration during prosthodontic treatment. Whether or not these differences may affect the outcome of apical seal or post preparation requires further investigation. |
