Microleakage from the crown to the root canal after post space preparation with different timing and remaining length / 中国组织工程研究

ABSTRACT

BACKGROUND: Poor root canal filling or poor post-core crown restoration can cause microleakage between the implant material and the tooth, leading to secondary infection of the periapical tissue and affecting long-term effect of tooth restoration. OBJECTIVE: To analyze the microleakage in a glucose penetration model when post space preparation is performed with different timing and remaining lengths. METHODS: Eighty-six freshly extracted mandibular premolars from the Orthodontics Department of Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University were randomly divided into eight groups positive control group (n=10) undertook root canal preparation; negative control group (n=10) undertook root canal preparation and filling but not post space preparation; A1, B1 and C1 groups (n=11 per group) were subjected to root canal filling immediately followed by post space preparation with the filling material of 4 mm, 5 mm, and 6 mm in length, respectively; A2, B2 and C2 groups were subjected to root canal filling and 1 week after filling, the three groups underwent post space preparation with the filling material of 4, 5 and 6 mm in length, respectively. At 48 hours after post space preparation, the integration of root canal wall and filling material was observed by scanning electron microscopy. The glucose microleakage model was used to detect the amount of glucose leaking from the crown to the root in each group. RESULTS AND CONCLUSION: (1) Under the scanning electron microscope, the fillings were most tightly bonded to the root canal wall in C1, while microcracks were most apparent in A2. (2) According to the measurement of glucose penetration model, A2 showed more microleakage than A1 (P < 0.05), B2 showed more microleakage than B1 (P < 0.05), and there was no statistically significant difference between C1 and C2 (P> 0.05). No significant difference was found among A1, B1 and C1 (P> 0.05), B2 showed no statistical difference in the microleakage from A2 and C2 (P> 0.05), but A2 showed more microleakage than C2 (P′ < 0.017). These results indicate that immediate post space preparation is superior to delayed preparation in reducing the microleakage. For immediate post space preparation, the remaining length of the filling material has no effect on the microleakage, but for delayed preparation, the filling material of at least 5 mm in length should be preserved.