Collares FM, Portella FF, Rodrigues SB, Celeste RK, Leitune VCB, Samuel SMW. The influence of methodological variables on the push-out resistance to dislodgement of root filling materials: a meta-regression analysis. International Endodontic Journal, 49, 836-849, 2016. The aim of this systematic review was to evaluate the influence of several methodological variables on the push-out resistance to dislodgment of root filling materials by a meta-regression analysis of the literature. A systematic review was performed by searching the PubMed database using the terms 'push-out' and 'pushout'. Laboratory studies published before March 2015 were included. Two reviewers extracted data regarding country of origin, year of publication, tooth type, smear layer removal, root canal sealer, core material, obturation technique, sample storage, tooth portion, test machine load velocity and slice thickness. Pooled mean resistance to dislodgement of all groups from the included studies was used in a linear meta-regression of random effects (a = 0.05). Of the 850 identified studies, 53 met the inclusion criteria. A meta-regression of the 341 groups extracted from these articles was performed to analyse the influence of each variable on resistance to dislodgement (in MPa). The sealer, core material, obturation technique, slice thickness, storage time, load velocity and tooth portion significantly influence the results (P < 0.05). Irrigant solution and smear layer removal did not influence the resistance to dislodgement of the root filling materials (P > 0.05). Methodological variables such as sealer, core material, root filling technique, tooth type, tooth portion, slice thickness, storage time and load velocity influenced the resistance to dislodgment. The inclusion and standardization of all related variables could lead to a more comparable and reproducible analysis of the resistance to dislodgment of the root canal sealers.

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The present study aimed to evaluate effects of different surface treatments and aging of composite cylinders on bond strength of composite resin repair. Thirty-two composite cylinders were produced and divided into four groups according to type of surface treatment and storage time of composite cylinder and repair. Cylinder surface of control group (G control ) received no treatment before composite repair. Other groups were sandblasted with aluminum oxide (G Al2O3 ), followed by silane (G Al2O3sil ) or adhesive (G Al2O3ad ). Composite cylinders were stored in artificial saliva for either 24 hours or 1 year. Repairs were performed and stored in artificial saliva for 24 hours or 1 year and repair strength was evaluated using microtensile bond strength test. Data were submitted to Student's t test, two-way ANOVA, and post hoc test for storage time and treatment (α = 0.05). G control group showed lower values of aging of composite cylinder and storage time of repair (24 hours or 1 year for both) compared with other groups (p < 0.05). G Al2O3ad and G Al2O3sil groups did not exhibit decreased microtensile bond strength with aged repairs (1 year; p > 0.05). Polymer degradation was significant for composite cylinders during the first year of storage in G control , G Al2O3 , and G Al2O3ad groups (p < 0.05). In G Al2O3sil group, storage time of composite cylinders was not significant (p > 0.05). Aging of composite resin influenced bond strength of restoration repair for up to 1 year. Sandblasting with Al 2 O 3 , followed by application of silane layer, produced high bond strength after composite or repair aging.

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