Microtensile Bond Strength Between Polylactic Acid Absorbable Post And Composite Resin Core

Objective To evaluate the effect of different surface treatments on the microtensile bond strength between PLA post and composite resin core.Methods Twenty-five PLA posts were randomly divided into 5 groups and treated as the following:Group A:coated with total-etch adhesive Prime&Bond NT (PB); Group B:coated with chloroform and then coated with PB; Group C: coated with the mixture of chloroform and PB with the proportion of 1:1; Group D:coated with the mixture of chloroform and PB with the proportion of 1:2; Group E:coated with the mixture of chloroform and PB with the proportion of 2:1. Five quartz fiber posts were set as group F, coated with PB. All treated posts were cemented with composite resin cores and shaped as rod-like bonding specimens and subjected to the microtensile bonding strength (μTBS) test. Failure modes of specimens were evaluated under a stereomicroscope (×40). Surface morphologies of two fractured specimens from each group were assessed by scanning electron microscopy (SEM). Data were statistically analyzed.Results There were significant differences in microtensile bond strength between all the groups (P=0.000). The highest microtensile bond strength was Showed in group C (20.58MPa±3.35MPa), followed by group E (13.35MPa± 3.21MPa), group D (12.80MPa±2.77MPa), group F (12.24MPa±1.40MPa), gr-oup B (10.91MPa±1.61MPa) and group A (5.03MPa±1.48MPa). There were differences between all the groups in fracture mode (P=0.000). In the group C, the most common type of failure was resin cohesive failure.Conclusion The microtensile bond strength between PLA post and composite resin core might be affected by the surface treatments of PLA post. The surface treatment of coating with the mixture of chloroform and PB with the proportion of 1:1 showed better effect on improving the adhesive strength between composite resin core and PLA posts.