Karapinar-Kazandag Meric, Basrani Bettina, Tom-Kun Yamagishi Valerie, Azarpazhooh Amir, Friedman Shimon
Department of Endodontics, Faculty of Dentistry, Yeditepe University, Istanbul, Turkey.
Discipline of Endodontics, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
Dent Traumatol. 2016 Apr;32(2):146-52. doi: 10.1111/edt.12230. Epub 2015 Sep 28.
BACKGROUND/AIM: Immature endodontically treated teeth may require reinforcing to reduce the risk of root fracture. This study assessed the fracture resistance of simulated immature tooth roots reinforced with mineral trioxide aggregate (MTA) or two composite resin (CR) materials.
One hundred extracted roots of mature human maxillary incisors were decoronated and sectioned 9 mm further apically from the decoronation line and randomly divided into five groups (n = 20). In Group 1 (negative control), roots received no treatment. In groups 2-5, canals were enlarged to 2.1 mm diameter to simulate immature roots, dressed with calcium hydroxide (Ca(OH)2 ) and incubated for 7 days. After removal of Ca(OH)2 , canals in Group 2 (positive control) were left unfilled. Canals in groups 3, 4 and 5 were filled with MTA, BisFil 2B flowable CR or BisFil II posterior CR, respectively. After further incubation for 30 days, specimens were embedded in acrylic cylinders and horizontally loaded in a universal testing machine at cross head speed of 5 mm min(-1) until fracture occurred. Load (N) at and pattern of fracture were recorded.
Load at fracture was significantly lower (t-test, P = 0.003) in Group 2 (630 ± 199.12) than in Group 1 (896.98 ± 311.79). It did not differ significantly among groups 1, 3, 4 and 5 (anova, P > 0.07). Pattern of fracture did not differ among the groups either.
Within the limitations of this study, root canal filling with MTA and two CR materials affected reinforcement of simulated immature roots to levels comparable with intact roots.
背景/目的：未成熟的经牙髓治疗的牙齿可能需要增强以降低牙根折断的风险。本研究评估了用三氧化矿物凝聚体（MTA）或两种复合树脂（CR）材料增强的模拟未成熟牙根的抗折性。
将100颗拔除的成熟人上颌切牙牙根去冠，并从去冠线向根尖方向再切取9mm，随机分为五组（n = 20）。第1组（阴性对照组）牙根不做处理。第2 - 5组，将根管扩大至直径2.1mm以模拟未成熟牙根，用氢氧化钙（Ca(OH)₂）封药并孵育7天。去除Ca(OH)₂后，第2组（阳性对照组）根管不充填。第3、4和5组根管分别用MTA、BisFil 2B流动型CR或BisFil II后牙用CR充填。进一步孵育30天后，将标本嵌入丙烯酸圆柱体中，并在万能试验机上以5mm min⁻¹的十字头速度水平加载直至发生折断。记录折断时的载荷（N）和折断模式。
第2组（630 ± 199.12）折断时的载荷显著低于第1组（896.98 ± 311.79）（t检验，P = 0.003）。第1、3、4和5组之间无显著差异（方差分析，P > 0.07）。各组的折断模式也无差异。
在本研究的局限性内，用MTA和两种CR材料进行根管充填对模拟未成熟牙根的增强效果与完整牙根相当。
