Can silanization increase the retention of glass-fiber posts? A systematic review and meta-analysis of in vitro studies

Abstract

The role of silanes in the bonding of resin luting agents to glass-fiber posts (GFPs) is a controversial topic, and the question still remains whether post silanization is able to improve the retention of GFPs luted into root canals. Thus, this study was designed to determine whether evidence exists to justify silanization of GFPs before cementation to increase their retention into root canals. In vitro studies that evaluated the retention of GFPs cemented into root canals or artificial substrates and that used silane coupling agents for pretreatment of the post were selected. Searches were carried out in PubMed and Scopus databases with no publication year or language limits. The last search was carried out in August 2014. Two distinct data analyses were carried out: 1) control group (no post pretreatment) vs silane only and 2) post pretreatment + silane vs silane only. Pooled-effect estimates were obtained by comparing the difference between each bond strength mean value and were expressed as the weighted mean difference between groups (p≤ 0.05). A total of 178 articles were found, and 23 were included in the review. The results were affected by the substrate into which the GFPs were luted (teeth or artificial devices). The analysis between control group and silane only for studies that used artificial devices favored the use of silane (p< 0.0001), but considering studies that used teeth as substrate, no significant difference was observed (p=0.35). The analysis between silane only and pretreatment + silane did not show a significant difference between groups when artificial devices were used (p=0.71), whereas the analysis favored the use of post pretreatment + silane over silane (p< 0.00001) only when the GFPs were luted into teeth. In conclusion, this review indicates that silanization improves the retention of GFPs luted into root canals provided that selective surface pretreatments are applied to the post before silanization.