Bortoluzzi E A, Souza E M, Reis J M S N, Esberard R M, Tanomaru-Filho M
Department of Dentistry and Endodontics, Araraquara Dental School, São Paulo State University, São Paulo, Brazil.
Int Endod J. 2007 Sep;40(9):684-91. doi: 10.1111/j.1365-2591.2007.01266.x.
To evaluate, using an experimental immature tooth model, the fracture resistance of bovine incisors submitted to different reinforcement treatments with mineral trioxide aggregate (MTA).
An immature tooth model was created by sectioning the coronal and apical portions of 40 bovine incisors 8 mm above and 12 mm below the cementoenamel junction. The root canals were irrigated with 1.0% sodium hypochlorite. They were enlarged both coronally and apically using number 703 carbide burs (ISO: 500-104-168-007-021) and their internal diameter was standardized to 2.1 mm. The specimens were assigned to four groups (n = 10): GI-control (without filling); GII-apical MTA plug + filling with gutta-percha and endodontic sealer; GIII-filling with MTA; GIV-apical MTA plug + filling with MTA + metallic post (Reforpost I). A polyether impression material was used to simulate the periodontal ligament. The specimens were submitted to a compressive load at a crosshead speed of 0.5 mm min(-1) in a servo-hydraulic universal testing machine (MTS 810) applied at 45 degrees to the long axis of the tooth until failure. Data were submitted to statistical analysis by the Kruskal-Wallis test at 5% significance level.
GIV presented the highest fracture resistance (32.7N) and differed significantly from the other groups (P < 0.05). No statistically difference was found between GII (16.6N) and GIII (23.4N) (P > 0.05). GIII had a significantly higher fracture resistance than GI (P < 0.05).
The use of MTA + metallic post as an intra-radicular reinforcement treatment increased the resistance to fracture of weakened bovine teeth in an experimental immature tooth model.
使用实验性未成熟牙齿模型,评估经不同矿物三氧化物凝聚体(MTA)强化处理的牛切牙的抗折性。
通过在牙骨质釉质界上方8毫米和下方12毫米处切割40颗牛切牙的冠部和根尖部分,创建未成熟牙齿模型。根管用1.0%次氯酸钠冲洗。使用703号硬质合金车针(ISO:500 - 104 - 168 - 007 - 021)对根管进行冠部和根尖部扩大,使其内径标准化为2.1毫米。将标本分为四组(n = 10):GI - 对照组(不充填);GII - 根尖部MTA充填 + 牙胶尖和根管封闭剂充填;GIII - MTA充填;GIV - 根尖部MTA充填 + MTA充填 + 金属桩(Reforpost I)。使用聚醚印模材料模拟牙周膜。在伺服液压万能试验机(MTS 810)中,以0.5毫米/分钟(-1)的十字头速度,在与牙齿长轴成45度角的方向上对标本施加压缩载荷,直至破坏。数据采用Kruskal - Wallis检验进行统计学分析,显著性水平为5%。
GIV组的抗折性最高(32.7N),与其他组有显著差异(P < 0.05)。GII组(16.6N)和GIII组(23.4N)之间未发现统计学差异(P > 0.05)。GIII组的抗折性显著高于GI组(P < 0.05)。
在实验性未成熟牙齿模型中,使用MTA + 金属桩作为根管内强化处理可提高弱化牛牙的抗折性。