In Vitro Effect of Luting Cement on Fracture Resistance of Primary Maxillary Central Incisors with Fiber Posts.

Objectives: The use of fiber posts in endodontically treated primary maxillary central incisors improves the retention of composite resin restorations. The purpose of this study was to evaluate the effect of 4 different luting cements on fracture resistance of primary maxillary central incisors with fiber posts. Materials and Methods: In this in vitro study, 40 primary maxillary central incisors were endodontically treated and obturated with Metapex. They were then randomly divided into four groups (n=10) for cementation of fiber posts with GC Fuji I glass ionomer luting cement, Panavia F2.0 dual-cure luting cement, Panavia SA Luting Plus cement (self-adhesive), and TotalCem self-adhesive cement. After 1000 thermal cycles, the fracture resistance was measured. Data were statistically analyzed using ANOVA (alpha=0.05). Results: The mean fracture resistance was 267.07±130.01N in TotalCem, 257.27±102.56N in Panavia F2.0 dual-cure cement, 227.82±110.40N in Panavia SA Luting Plus self-adhesive cement, and 220.89±59.96N in GC Fuji I glass ionomer group. There was no statistically significant difference in fracture resistance among the four groups (P=0.714). Conclusion: Type of luting cement had no significant effect on fracture resistance of primary maxillary central incisors with fiber posts. Nonetheless, TotalCem yielded the highest fracture resistance. Considering its self-adhesive property and easy workability, it can be a good option for cementation of fiber posts in endodontically treated primary central incisors.

The Probable Effect of Irrigation Solution and Time on Bond Strength to Coronal Dentin: An In Vitro Evaluation.

INTRODUCTION: The aim of this study was to evaluate the effect of root canal irrigants on the microtensile bond strength of 2-step self-etch adhesive to dentin. METHODS AND MATERIALS: n this study 36 sound extracted human third molars were used. After grinding 3 mm of occlusal surface, teeth were randomly divided into 6 groups based on irrigation material naming normal saline, 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) and also irrigation time (5 or 30 min). Next, teeth were restored with Clearfil SE bond adhesive resin system and Z250 composite. The teeth were then thermo cycled by thermo cycling machine, for 500 cycles between 5º and 55ºC with 60 sec dwell time and 12 sec transfer time. All samples were sectioned into bucco-lingual slabs. The sections were submitted to the micro tensile testing machine at a crosshead speed of 0.5 mm/min until fracture. Data was analyzed using the one-way ANOVA test with the level of significance set at 0.05. RESULTS: Irrigation with normal saline, 5.25% NaOCl and 2% CHX for 5 or 30 min did not significantly change the microtensile bond strength of adhesive to dentin (P=0.729 for time and P=0.153 for material). However the maximum and minimum microtensile bond strength was attributed to normal saline (44.13 N) and NaOCl (31.29 N) groups, respectively. CONCLUSION: Iirrigation solution and time have no influence on microtensile bond strength of two-step self-etch adhesive to coronal dentin.