In vitro study evaluating the effect of different subgingival root exposure methods and ferrule designs on fracture resistance of residual root
10.7518/hxkq.2014.01.018
- VernacularTitle:不同残根处理术式和肩领设计对残根抗折力影响的实验研究
- Author:
Qingfei MENG
1
;
Lijuan CHEN
;
Jian MENG
Author Information
1. 东南大学医学院附属徐州医院口腔科
- Keywords:
forced eruption;
crown lengthening;
dentin ferrule;
residual root;
fracture resistance
- From:
West China Journal of Stomatology
2014;(1):75-79
- CountryChina
- Language:Chinese
-
Abstract:
Objective To evaluate the effect of different subgingival root exposure methods, namely, crown lengthening or forced eruption, and different ferrule lengths on fracture resistance of a residual root restored with a carbon fiber post-and-core system. Methods Fifty-six extracted endodontically-treated mandibular first premolars were sectioned 1.0 mm coronal to the buccal cementoenamel junction. All the models were divided randomly into seven groups that each consist of eight roots. Group A was given non-ferrule as control. Simulated crown lengthening was performed for the dentin ferrule design in the cervical tooth structure for Groups B, C, and D with a ferrule length of 1.0, 2.0, and 3.0 mm, respectively. Simulated forced eruption was performed with a ferrule length of 1.0, 2.0, and 3.0 mm in the cervical tooth structure for Groups E, F, and G, respectively. After restoration with prefabricated carbon fiber post-and-core system, each specimen was embedded in a self-cured acrylic resin block from 2.0 mm apical to the margins of a cast Ni-Cr alloy crown, then loaded at 150° from the long axis in a universal testing machine at a crosshead speed of 1.0 mm·min-1 until fracture. Data of failure loads and fracture mode were recorded and analyzed. Results Mean failure loads for Groups A to G were (1.13±0.15), (1.27±0.18), (1.02±0.11), (1.05±0.12), (1.63±0.14), (1.92±0.19), and (1.93±0.15) kN, respectively. The effects of root exposure method and ferrule design differed significantly, and two factors exhibited significant interaction (F=33.396,P<0.0001). When the ferrule lengths were the same, fracture loads in the simulated forced erup-tion groups were significantly higher than those of the simu-lated crown lengthening groups (P<0.001). No statistical differences in fracture mode were observed among all groups (P=1.00). Conclusion More than 1.0 mm ferrule placement on the apical crown margin by using forced eruption signifi-cantly increases fracture resistance.
