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根管封闭剂iRootSP及AHPlus对牙根抗折强度的影响

2014-09-24郝晓鸣杨大江江波

中国医学创新 2014年22期

郝晓鸣 杨大江 江波

【摘要】 目的:探讨根管封闭剂iRoot SP及AH Plus对牙根抗折强度的影响。方法:选取45颗符合标准的下颌前磨牙,经根管预备后随机数字表法分为三组,实验组A使用iRoot SP+牙胶尖,组B使用AH Plus+牙胶尖,对照组C不使用根管封闭剂直接使用牙胶尖,三组均行热牙胶垂直加压充填法充填根管。将标本用万能实验机垂直加载直至标本发生折裂,记录牙根折裂时的抗压载荷。结果:实验组A和B的平均抗压载荷值分别为(236.04±34.67)N、(228.55±41.86)N,对照组C为(172.93±12.37)N,实验组与对照组比较差异有统计学意义(P<0.05);实验组之间比较,差异无统计学意义(P>0.05)。结论:根管封闭剂iRoot SP与AH P1us均能够提高牙根抗压载荷,两种封闭剂对牙根抗压载荷的影响短期内无明显差别。

【关键词】 根管封闭剂; iRoot SP; AH Plus; 抗折强度

【Abstract】 Objective: To compare the fracture resistance of roots filled with gutta percha (GP) and different root canal sealers. Method: Forty-five human maxillary premolars match our standards were instrumented and randomly divided into Group A and B, and Group C. Group A was filled with an epoxy resin-based sealer (AH Plus) and GP, Group B was filled with a calcium silicate-based sealer (iRoot SP) and GP, Group C was filled with GP only. All the groups were filled with vertical compaction technique. Compressive loading was carried out using a universal testing machine until fracture occurred, the force required to fracture was measured in Newtons. Result: The mean fracture load values of Groups A and B was (236.04±34.67)N, (228.55±41.86)N, Groups C(185.93±12.37)N, there were no significant differences in fracture strength between Group A and B (P>0.05), which the results were significantly superior to Group C (P<0.05). Conclusion: All the root canal sealers used in the present study increased the fracture resistance of instrumented root canals, there is no difference in root strength between them.

【Key words】 Root canal sealer; iRoot SP; AH Plus; Fracture resistance

First-authors address: Shenzhen Shekou Peoples Hospital, Shenzhen 518000, China

doi:10.3969/j.issn.1674-4985.2014.22.010

iRoot SP是最近被引入牙体牙髓专业的新型生物陶瓷材料,主要用作根管封闭剂和侧穿修补。此类型生物陶瓷材料用作根管封闭剂已被证实具有良好的密闭性、化学稳定性、生物相容性、抗菌活性、X线阻射性和碱性pH[1]。目前有关根管封闭剂iRoot SP对牙根抗折强度的影响方面的研究较少,本实验以人离体单根管下颌前磨牙为研究对象,比较iRoot SP+牙胶尖及树脂型根管封闭剂AH Plus+牙胶尖配合热牙胶垂直加压充填法充填根管后牙根抗压载荷值的变化,探讨其对牙根抗折强度的影响。

1 材料与方法

1.1 标本的制备和分组 选择近期正畸需求拔除的下颌前磨牙45例,实验标本的纳入标准为:(1)经近远中向及颊舌向X线片检测为单根管且未作过牙髓治疗;(2)根尖孔已发育完全,患者年龄为l8~25岁;(3)牙体完整,无龋坏,无隐裂;(4)解剖牙根长度为12~14 mm,牙颈部颊舌径为4~6 mm,牙颈部近远中径3~5 mm;(5)根管通畅;(6)采用Schneider法测定根管弯曲度θ,要求θ<20°[2]。去除附着的结石及牙周组织,常规开髓拔髓,置于含生理盐水中常温储存。

将符合标准的离体牙从釉质牙本质界截断去冠,保留牙根;用游标卡尺测量牙根的根长,颊舌径,近远中径。用随机数字表法将实验标本分成三组,每组15颗。使用SPSS 18.0统计学软件对每一组标本的根长,近远中径和颊舌径进行统计分析。若分析结果显示三组间根长、近远中径和颊舌径的差异无统计学意义,则行进下一步实验;否则,重新分组。三组的根长和颈部颊舌径、近远中径比较,差异无统计学意义(P>0.05),具有可比性。

1.2 根管预备 三组标本采用机用ProTaper镍钛器械(Dentsply,瑞士)通过冠下法行根管预备至F2(工作长度设定为距离根尖1 mm)。预备时辅助使用格兰凝胶,每换用器械时均用1 mL质量分数5.25%次氯酸钠溶液冲洗根管,预备完毕后5 mL生理盐水冲洗,最后纸尖干燥根管。endprint

1.3 根管充填 三组样本经根管充填处理后,用光固化复合树脂材料封闭根管口,三组拍摄颊舌向及近远中向X线片以检查牙根根管充填的质量,合格样本置于100%湿度、37 ℃孵箱中保存1周,使糊剂彻底固化。

1.3.1 实验组A 使用iRoot SP(Innovative BioCreamix Inc,Vancouver,加拿大)根管封闭剂加连续波充填技术充填根管。采用BL热牙胶系统进行根管充填。首先选择比工作长度短5 mm且无约束力的α机工作尖,然后选择0.06锥度的主牙胶尖,尖端调整至距工作长度0.5 mm时回拉有阻力。将所选择的主牙胶尖蘸取一定量的iRoot SP根管封闭剂放入根管内.机工作尖加压加热.进入根管内距工作长度5 mm处,停留1 s,加压加热,迅速取出工作尖,用垂直加压器加压,β机回填至根管口2 mm。

1.3.2 实验组B 使用AH plus (Dentsplv,瑞士)根管封闭剂加连续波充填技术充填根管。用AH plus根管封闭剂和与A组相同的充填方法充填根管。

1.3.3 对照组C 只充填牙胶尖,不加封闭剂。

1.4 抗折强度的测试 用厚约0.2 mm的橡皮膜包裹牙根,用丙烯酸树脂包埋固定,暴露冠方2 mm长度的牙根,进行力学测试。将底部直径为5 mm,顶角为45°的圆锥形加载头固定于万能实验机(Instron,美国)上端,把实验标本置于载物台上,加压头垂直对准根管口处,然后加压,加压速度为1 mm/s,记录牙根折裂力值。牙根折裂判断:万能实验机显示负荷力值突然大幅度下降,辅以听到牙根折断的声响。力值大幅度下降前的最大值记为该牙的抗压载荷,以此评价牙根的抗折强度。

1.5 统计学处理 使用SPSS 18.0统计软件包进行分析,计量资料以(x±s)表示,均行正态分布检验,非正态分布计量资料进行正态转换,各组标本牙根长度、颈部颊舌向长度、近远中向长度测量值和各组标本抗压载荷值的比较分别采用单因素方差分析。P<0.05为差异有统计学意义。

2 结果

实验组A、B和对照组C标本平均抗压载荷分别为(236.04±34.67)N、(228.55±41.86)N、(185.93±12.37)N,实验组A与B平均抗压载荷值均高于对照组C,比较差异有统计学意义(P<0.05),但组A与组B之间平均抗压载荷值差异无统计学意义(P>0.05)。

3 讨论

经根管治疗后的牙齿较健康活牙更易发生牙根折裂。学者们认为,造成根管治疗后的牙齿抗折强度降低的原因主要与根管预备导致的牙体大量丢失、过大的根管充填压力、牙体脱水有关[3-4]。此外,牙髓治疗药物,如MTA、氢氧化钙、次氯酸钠溶液均可显著降低牙本质的抗折能力,增加牙本质的脆性。Andreasen等[5]认为,氢氧化钙因其呈碱性,可中和、溶解牙本质中的酸性蛋白,并使胶原纤维变性,若以此长期充填根管有可能会降低牙本质的抗折强度达到50%。White等[6]研究显示,MTA、氢氧化钙和次氯酸钠包埋或浸泡牙齿5周后,牙齿抗折力分别降低33%、32%和59%,认为牙齿抗折力的降低可能与这些材料的强碱作用造成牙本质基质崩解有关。

牙胶尖作为牙髓病治疗中标准固体根管充填材料,它与根管壁间无粘接性,常与根管封闭剂结合使用以提高根管的封闭性,根管封闭剂不但能够填补牙胶尖之间的空隙,也能够填补牙胶尖与根管壁之间的空隙[7]。AH P1us是新型环氧树脂类根充糊剂,具有体积稳定、流动性好、通过释放低浓度的甲醛而抗菌等优点,已被广泛应用于临床[8]。由于含有双酚环氧树脂,其黏接力强,体积收缩性小,热膨胀系数与牙体组织接近,AH Plus糊剂含有聚硅氧烷油,可使充填材料具有流动性和渗透性,渗入弯曲、细小根管,侧副根管及牙本质小管,与牙胶一起充填能很好地封闭根管系统[9-11]。本研究结果显示,AH P1us组牙根平均抗压载荷值显著高于对照组(P<0.05),这与Top?uo?lu等[12]结果类似,笔者认为AH P1us封闭剂的渗透特性与根管壁之间形成机械扣锁作用能够提高根管充填材料的稳定,因此增强根管牙本质的抗折性能。

iRoot SP是一种新上市生物陶瓷材料不需要调制,直接注射,可以减少误差,用于根管充填的封闭剂。主要由硅酸钙、氧化锆、氧化钽、一价磷酸钙、氢氧化钙和填料组成。不溶于水,不含铝,需水凝固和硬化。iRoot SP的固化反应原理是,iRoot SP糊剂中的钙硅酸盐粉末水解生成硅酸钙水合物凝胶和氢氧化钙,氢氧化钙离子与磷酸盐反应生成羟磷灰石和水。牙本质中约含20%的水[13],这些水可以使iRoot SP发生凝固[14-15]。若根管过分干燥,凝固时间就会相对延长。在这里,包括笔者团队的一些学者会疑问,iRoot SP 封闭剂凝固过程中吸收水分可能会导致牙根牙本质水分丧失及过程产物氢氧化钙造成根管内碱性环境是否会降低牙根的抗折性呢?笔者的实验结果显示,iRoot SP组牙根平均抗压载荷值显著高于对照组(P<0.05)。这也许是因为它反应过程中氢氧化钙离子与磷酸盐反应生成羟磷灰石和水,消耗了部分氢氧化钙离子,补偿了水。而且新生成的羟磷灰石是一种无毒的骨修复和重建材料,而反应生成的水继续与钙硅酸盐反应生成硅酸钙水合物凝胶具有一定的生物活性,可以作为组织修复材料中的纤维增强组分。体外研究证明,iRoot SP在凝固反应发生过程中可以产生羟基磷灰石,这些羟基磷灰石一方面与根管牙本质形成牢固的化学结合,另一方面和牙胶尖结合形成严密的封闭,且凝固反应完成后体积不收缩也不膨胀[14-16]。因此笔者推测根管封闭剂iRoot SP较AH P1us具有更高的结合强度和稳定性,但笔者的实验结果却显示iRoot SP组与AH P1us组牙根平均抗压载荷值差异无统计学意义(P>0.05),所以更多的样本量收集,更长的时间段观察,更精确地测量方法使用,将是笔者今后研究的方向。endprint

本实验从一开始标本的筛选到根管预备方法及根管充填方法的采用尽量作到了组间相同或平衡,故可以认为本实验所测得的力值反映了不同根管封闭剂的使用对牙根抗折强度的影响。本研究结果显示,根管封闭剂iRoot SP与AH P1us均能够强化牙胶尖与根管壁的结合,提高牙根抗压载荷,两种封闭剂对牙根抗压载荷的影响短期内无明显差别。

参考文献

[1] Koch K, Brave D. Bioceramic technology: the game changer in endodontics[J]. Endod Pract,2009,4(2):17-21.

[2] Schneider S W. A comparison of canal preparations in straight and curved root canals[J]. Oral Surg Oral Med Oral Pathol,1971,32(2):271-275.

[3] Chan C P, Lin C P, Tseng S C, et al. Vertical root fracture in endodontically versus nonendodontically treated teeth: a survey of 315 cases in Chinese patients[J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod,1999,87(4):504-507.

[4] Helfer A R, Melnick S, Schilder H. Determination of the moisture content of vital and pulpless teeth[J]. Oral Surg Oral Med Oral Pathol 1972,34(4):661-670.

[5] Andreasen J O, Farik B, Munksgaard E C. Long-term calcium hyoxide as a root canal dressing may increase risk of root flracture[J]. Dent Tranmatol,2002,18(3):134-137.

[6] White J D, Laeefield W R, Chavers L S, et al. The efect of three commonly used endodontic materials on the strength and hardness of root dentin[J]. J Endod,2002,28(12):828-830.

[7] Lee K W, Williams M C, Camps J J, et al. Adhesion of endodontic sealers to dentin and gutta-percha[J]. J Endod,2002,28(10):684-688.

[8] Siqueira JF Jr, Favieri A, Gahyva S M, et al. Antimicrobial activity and flow rate of newer and established root canal sealers[J]. J Endod,2000,26(5):274-277.

[9] Jainaen A, Palamara J E, Messer H H. Effect of dentinal tubules and resin-based endodontic sealers on fracture properties of root dentin[J]. Dent Mater,2009,25(10):73-81.

[10] Mamootil K, Messer H H. Penetration of dentinal tubules by endodontic sealer cements in extracted teeth and in vivo[J]. Int Endod J,2007,40(11):873-881.

[11] Sousa-Neto M D, Silva Coelho F I, Marchesan M A, et al. Ex vivo study of the adhesion of an epoxybased sealer to human dentine submitted to irradiation withEr: YAG and Nd: YAG lasers[J]. Int Endod J,2005,38(12):866-870.

[12] Top?uo?lu H S, Tuncay ?, Karata? E, et al. In vitro fracture resistance of roots obturated with epoxy resin-based, mineral trioxide aggregate-based, and bioceramic root canal sealers[J]. J Endod,2013,39(12):1630-1633.

[13] Tay F R, Loushine R J, Lambrechts P, et al. Geometric factors affecting dentin bonding in root canals: a theoretical modeling approach[J]. J Endod,2005,31(8):584-589.

[14] Loushine B A, Bryan T E, Looney S W, et al. Setting propeflies and cytotoxicity evaluation of a premixed bioceramic root canal sealer[J]. J Endod,2011,37(5):673-677.

[15] Zhang W, Li Z, Peng B, et al. Assessment of a new root canal sealers apical sealing ability[J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod,2009,107(6):79-82.

[16] Zhang H, Shen Y, Ruse N D, et al. Antibacterial activity of endodontic sealers by modified direct contact test against Enterococcus faecalis[J]. J Endod,2009,35(7):1051-1055.

(收稿日期:2014-06-05) (本文编辑:王宇)endprint

本实验从一开始标本的筛选到根管预备方法及根管充填方法的采用尽量作到了组间相同或平衡,故可以认为本实验所测得的力值反映了不同根管封闭剂的使用对牙根抗折强度的影响。本研究结果显示,根管封闭剂iRoot SP与AH P1us均能够强化牙胶尖与根管壁的结合,提高牙根抗压载荷,两种封闭剂对牙根抗压载荷的影响短期内无明显差别。

参考文献

[1] Koch K, Brave D. Bioceramic technology: the game changer in endodontics[J]. Endod Pract,2009,4(2):17-21.

[2] Schneider S W. A comparison of canal preparations in straight and curved root canals[J]. Oral Surg Oral Med Oral Pathol,1971,32(2):271-275.

[3] Chan C P, Lin C P, Tseng S C, et al. Vertical root fracture in endodontically versus nonendodontically treated teeth: a survey of 315 cases in Chinese patients[J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod,1999,87(4):504-507.

[4] Helfer A R, Melnick S, Schilder H. Determination of the moisture content of vital and pulpless teeth[J]. Oral Surg Oral Med Oral Pathol 1972,34(4):661-670.

[5] Andreasen J O, Farik B, Munksgaard E C. Long-term calcium hyoxide as a root canal dressing may increase risk of root flracture[J]. Dent Tranmatol,2002,18(3):134-137.

[6] White J D, Laeefield W R, Chavers L S, et al. The efect of three commonly used endodontic materials on the strength and hardness of root dentin[J]. J Endod,2002,28(12):828-830.

[7] Lee K W, Williams M C, Camps J J, et al. Adhesion of endodontic sealers to dentin and gutta-percha[J]. J Endod,2002,28(10):684-688.

[8] Siqueira JF Jr, Favieri A, Gahyva S M, et al. Antimicrobial activity and flow rate of newer and established root canal sealers[J]. J Endod,2000,26(5):274-277.

[9] Jainaen A, Palamara J E, Messer H H. Effect of dentinal tubules and resin-based endodontic sealers on fracture properties of root dentin[J]. Dent Mater,2009,25(10):73-81.

[10] Mamootil K, Messer H H. Penetration of dentinal tubules by endodontic sealer cements in extracted teeth and in vivo[J]. Int Endod J,2007,40(11):873-881.

[11] Sousa-Neto M D, Silva Coelho F I, Marchesan M A, et al. Ex vivo study of the adhesion of an epoxybased sealer to human dentine submitted to irradiation withEr: YAG and Nd: YAG lasers[J]. Int Endod J,2005,38(12):866-870.

[12] Top?uo?lu H S, Tuncay ?, Karata? E, et al. In vitro fracture resistance of roots obturated with epoxy resin-based, mineral trioxide aggregate-based, and bioceramic root canal sealers[J]. J Endod,2013,39(12):1630-1633.

[13] Tay F R, Loushine R J, Lambrechts P, et al. Geometric factors affecting dentin bonding in root canals: a theoretical modeling approach[J]. J Endod,2005,31(8):584-589.

[14] Loushine B A, Bryan T E, Looney S W, et al. Setting propeflies and cytotoxicity evaluation of a premixed bioceramic root canal sealer[J]. J Endod,2011,37(5):673-677.

[15] Zhang W, Li Z, Peng B, et al. Assessment of a new root canal sealers apical sealing ability[J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod,2009,107(6):79-82.

[16] Zhang H, Shen Y, Ruse N D, et al. Antibacterial activity of endodontic sealers by modified direct contact test against Enterococcus faecalis[J]. J Endod,2009,35(7):1051-1055.

(收稿日期:2014-06-05) (本文编辑:王宇)endprint

本实验从一开始标本的筛选到根管预备方法及根管充填方法的采用尽量作到了组间相同或平衡,故可以认为本实验所测得的力值反映了不同根管封闭剂的使用对牙根抗折强度的影响。本研究结果显示,根管封闭剂iRoot SP与AH P1us均能够强化牙胶尖与根管壁的结合,提高牙根抗压载荷,两种封闭剂对牙根抗压载荷的影响短期内无明显差别。

参考文献

[1] Koch K, Brave D. Bioceramic technology: the game changer in endodontics[J]. Endod Pract,2009,4(2):17-21.

[2] Schneider S W. A comparison of canal preparations in straight and curved root canals[J]. Oral Surg Oral Med Oral Pathol,1971,32(2):271-275.

[3] Chan C P, Lin C P, Tseng S C, et al. Vertical root fracture in endodontically versus nonendodontically treated teeth: a survey of 315 cases in Chinese patients[J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod,1999,87(4):504-507.

[4] Helfer A R, Melnick S, Schilder H. Determination of the moisture content of vital and pulpless teeth[J]. Oral Surg Oral Med Oral Pathol 1972,34(4):661-670.

[5] Andreasen J O, Farik B, Munksgaard E C. Long-term calcium hyoxide as a root canal dressing may increase risk of root flracture[J]. Dent Tranmatol,2002,18(3):134-137.

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(收稿日期:2014-06-05) (本文编辑:王宇)endprint