Anti-Fractures Strength Comparison Of Three Different Post-core Bonding Materials

Objective: The purpose of this in vitro study is to compare the fractureresistance of three bonding materials used in cementing post-core to the firstpremolars, which had been treated by RCT procedure and at last restored withfull crown,so as to improve clinical more suitable pile nuclear bondingmaterial is provided academic basis.Method: Twenty-seven lower premolars recently extracted fromorthodontic patients were divided into three groups (9in each group)randomly. All the teeth were root canal treated and would be restored withpost-core and full crown. A group were prepared as following: keepingresidual tissue above CEJ2mm+Ni-Cr alloy post-core+zinc phosphatecements as bonding materials; group B: residual tissue above CEJ2mm+Ni-Cr alloy post-core+3M glass ionomer cements bonding; group C: residualtooth tissue above CEJ2mm+Ni-Cr alloy post-core+DMG resin cementsbonding. For final casting full crown restorations, preparation should be asthis:crown margin stopped above CEJ0.5mm at the labial surface,1mmshoulder width,8mm from the buccal surface to gingival,2-5convergenceangles. Samples were embedded with self-curing resin at2mm level belowthe CEJ and then fixed on the CMT7104type electronic universal testingmachine by a special metal base. Sustained loads were applied at the junctionbetween buccal1/3and middle1/3in the occlusion surface,135degree to thelong axis of the teeth at a crosshead speed1.0mm/min. Force value wasrecorded for each specimen at the moment the fracture happened.Results:1. The mean loading force were728.93±32.07N,732.667±38.46N, and786.32±51.10N in A,B,C group respectively.2. The data obtained from the three groups were dealt with analysis ofvariance. The results showed that the post-core bonding material was a significant effect factor for tooth fracture resistance (p<0.05). There was nosignificant different between A and B (p>0.05), while the loading force ingroup C was significantly higher than that in group B (p<0.5).Conclusions:1. Different bonding materials might affect the resistantability of tooth after post-core and full crown restored. Bonding materialwhich owns high compressive strength would improve post-core and toothtissue resistant ability than the lower one when tooth meets strong impact orforce.2. The fracture resistance of the mandibular first premolar restored bypost-core and full crown in this study, cemented with three different bondingmaterial, showed that all the samples were able to withstand normalmasticatory force (30-300N) without break, which means all the differentstrength bonding materials can meet the needs of patients with normalfunction.3. Bonding materials owning high compressive strength should bepreferred for they can offer more safety protection, and reduce destructivetooth fracture incidence as far as possible. Try to maintain the health toothtissue as much as possible can improve the tooth fracture resistance, whichwould help dentist keep more teeth, and rdeuce fracture risk.