This study evaluated the effect of time and concentrations of sodium hypochlorite on the bond strength of a glass fibre post cemented in a root canal with resin cement. A total of 45 single-rooted extracted human teeth were prepared with Protaper universal files, randomly allocated into nine groups and then subjected to 1% or 4% NaOCl for a period of 1 min or 2 min. Fibre posts were then bonded into the root canal, sectioned and the bond strength tested using a push-out test. A longer irrigation time resulted in a significant reduction (P < 0.05) in bond strength, while a final additional irrigation with distilled water significantly reduced bond strength. The concentration of NaOCl did not significantly affect bond strength. Within the limitations of this study, it was observed that regardless of the concentration of NaOCl used, shorter irrigation times favoured better fibre post bonding.

Introduction The present systematic review assesses the literature which identifies an association between surgical adjunctive procedures for accelerating tooth movement (SAPATM) during orthodontic therapy and orthodontically induced external root resorption (OIERR). By determining the level of association, the results may provide clinical evidence for minimising the deleterious effects of orthodontic tooth movement. Methods Electronic databases including Medline, PubMed, Embase, Scopus, CINAHL, Worldcat, OpenGrey, and the Cochrane Library were searched and followed by further searches from citations of included articles. Searches were undertaken with no restrictions on year, publication status, nor language. The selection criteria included randomised controlled trials (RCTs) conducted using surgical procedures to accelerate orthodontic therapy in conjunction with fixed orthodontic appliances on human patients. The quality of the included studies was assessed using the Cochrane Risk of Bias (RoB) Tool and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Inter-rater agreement of the review authors was used for the inclusion of primary articles, RoB assessment and evaluation of the quality of evidence (GRADE) and was calculated using Cohen’s kappa statistic. Results A total of 1118 articles were retrieved in the initial search. After the review process, 13 article trials met the inclusion criteria. Sample sizes ranged from 20 to 52 patients. Two studies showed a statistically significant reduction in OIERR, with a third showing both an increase and decrease of OIERR on different roots of the same maxillary molar tooth. A significant decrease in treatment time was shown by four studies, while six studies showed increased tooth movement. All included studies were classified as having low to minor concerns of bias and a low quality of evidence. Conclusions There is an apparent shortage of well-designed and reported RCTs on the effect of SAPATM on OIERR. However, there is some evidence to suggest OIERR is reduced following SAPATM. The use of SAPATM is also shown to increase tooth movement and reduce overall treatment time, but its benefits may be considered limited to the initial post-operative period.