Brito-Júnior M, Pereira R D, Veríssimo C, Soares C J, Faria-e-Silva A L, Camilo C C, Sousa-Neto M D
Interinstitutional PhD program, State University of Montes Claros, Montes Claros, Brazil; Department of Restorative Dentistry, Faculty of Dentistry, University of São Paulo, Ribeirão Preto, Brazil.
Int Endod J. 2014 Oct;47(10):958-66. doi: 10.1111/iej.12241. Epub 2014 Feb 1.
To evaluate the effect of adhesive restorations on fracture resistance and stress distribution in teeth with simulated immature apices and apical plugs of mineral trioxide aggregate (MTA).
Sixty bovine incisors were sectioned 8 mm above and 12 mm below the cemento-enamel junction (CEJ). The root canal was enlarged using a diamond bur, resulting in remaining root canal walls with 0.1-0.2 mm of thickness. A 5-mm apical plug of MTA was placed and the teeth were restored according to the following groups: GP--the root canal was filled with gutta-percha and endodontic sealer; CR--the root canal was filled with light-cured composite resin inserted incrementally; FP--a fibre post was cemented into the root canal; and RFP--the fibre post was relined with composite resin prior to the cementation into the root canal. A load was applied on the crown of all teeth at 135° to their long axis until fracture. Data was analysed by one-way anova and SNK tests (α = 0.05), whilst the fracture pattern was evaluated according to the position of the fracture. Stress distributions in the restored teeth were verified by finite element analysis.
Teeth restored with fibre posts and relined fibre posts were associated with the highest fracture resistance, whilst the GP group had the lowest values. GP and RC groups had similar fracture resistance values (P = 0.109). All fractures types involved the cervical and middle thirds of roots. The GP model had high levels of stress concentration in the cervical and middle thirds of roots. No difference was found amongst the stress concentration in the RC, FP and RFP models.
Restorative protocols alter the fracture resistance and stress distribution of immature teeth after placement of MTA apical plugs.
评估粘结修复对模拟根尖未发育成熟且根尖有三氧化矿物凝聚体（MTA）充填的牙齿抗折性能及应力分布的影响。
选取60颗牛切牙，在牙骨质 - 釉质界（CEJ）上方8mm和下方12mm处截断。使用金刚砂车针扩大根管，使剩余根管壁厚度为0.1 - 0.2mm。放置5mm厚的MTA根尖充填物，然后根据以下分组对牙齿进行修复：GP组——根管内充填牙胶和根管封闭剂；CR组——根管内逐步充填光固化复合树脂；FP组——将纤维桩粘结到根管内；RFP组——在将纤维桩粘结到根管内之前先用复合树脂衬里。以与牙齿长轴成135°的角度对所有牙齿的牙冠施加负荷直至折断。采用单因素方差分析和SNK检验（α = 0.05）分析数据，同时根据折断位置评估折断模式。通过有限元分析验证修复后牙齿的应力分布。
用纤维桩和衬里纤维桩修复的牙齿具有最高的抗折性能，而GP组的值最低。GP组和RC组的抗折性能值相似（P = 0.109）。所有骨折类型均累及牙根的颈部和中部三分之一。GP模型在牙根的颈部和中部三分之一处有较高的应力集中。在RC、FP和RFP模型的应力集中方面未发现差异。
修复方案会改变MTA根尖充填后未成熟牙齿的抗折性能和应力分布。
