Abstract
In this study we investigated the effect of two different dentin pretreatments on the retention of prefabricated posts and on the microleakage of the composite resin cores.
The dentin surfaces of both post space and root face of extracted human single-rooted teeth were treated with either 1) 37% phosphoric acid solution or 2) 37% phosphoric acid solution and then 10% sodium hypochlorite solution. Then, a prefabricated post (AD Post®, Kuraray Co.) was cemented with an adhesive resin cement (Panavia EX®, Kuraray Co.) after application of dentin bonding agent (Clearfil New Bond®, Kuraray Co.). And a composite resin core was built up with light-cured composite resin (Clearfil Photo Core®, Kuraray Co.).
The retention of prefabricated posts was measured after one day immersion into 37°C water, 5, 000 times and 10, 000 times of thermalcycles between 4° and 60°C of water bath. The microleakage was measured after 2, 500 times of thermalcycles between 4° and 60°C in 0.2% aqueous solution of basic fuchsin dye.
The results obtained indicated that phosphoric acid etching was ineffective both on the retention and on the marginal sealing of posts and composite resin cores. Meanwhile, removing of the collagen layer exposed by phosphoric acid etching (30 s) with sodium hypochlorite solution (60 s or 120 s) effectively increased adhesive strength of the adhesive resin to dentin, i. e. the retention of prefabricated posts significantly increased and the microleakage of the composite resin cores was significantly reduced.
These results were supported by SEM observation of interface between adhesive resin and dentin.
