Duration of cleaning and priming of dentine and contraction gap formation.
OBJECTIVE
The effects of the duration of cleaning and priming on the marginal adaptation of a light-activated resin composite in a cylindrical dentine cavity were examined by measuring the width of the wall-to-wall polymerization contraction gap.


METHODS
The dentine cavity was cleaned with ethylene diamine tetra-acetic acid (EDTA) and primed 35 vol% hydroxyethyl methacrylate (HEMA) or glyceryl methacrylate (GM) solution for up to 60 s. The cavity was filled with a light-cured resin composite after the application of a dual-cured dentine bonding agent.


RESULTS
The formation of a contraction gap by the composite appeared to be prevented completely, regardless of the duration of priming with GM solution, when the cavity was cleaned with EDTA for 60 s. When cleaning was limited to just 30 s, GM priming had to be prolonged to 60 s to obtain complete marginal integrity. A significantly wide contraction gap was observed without EDTA cleaning, even when the cavity wall was primed with GM solution for 60 s.


CONCLUSIONS
GM solution was a better dentine primer than HEMA solution, since HEMA priming did not prevent gap formation under any of the conditions tested.
Department of Operative Dentistry, Showa University School of Dentistry, Tokyo, Japan.
M
M
Ohhashi
K
K
Itoh
H
H
Hisamitsu
S
S
Wakumoto
D000134:Acid Etching, Dental; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000379:methods; D018772:Dental Marginal Adaptation; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004492:Edetic Acid; D005989:Glycerides / Q000737:chemistry; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry; D016369:Smear Layer; D013499:Surface Properties; D013997:Time Factors
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005989:Glycerides; D008689:Methacrylates; D011108:Polymers; C069750:glyceryl methacrylate; C005044:hydroxyethyl methacrylate; D004492:Edetic Acid