PubMed · 6598684
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P Fernandez Lorente. [Reconstruction with composites].. https://pubmed.ncbi.nlm.nih.gov/6598684/
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OBJECTIVES: A freeze-fracture technique with critical-point drying has been shown to preserve the structure of collagen in demineralized primed dentine in vitro (Titley K et al. Am J Dent 1994; 7: 22-26). This study utilized the technique to examine the attachment to dentine produced in vivo All-Bond 2 (AB2), Scotchbond Multi-Purpose (SBMP) and Prisma Universal Bond 3 (PUB3). METHODS: Eighteen medium-depth restorations were placed in buccal and/or lingual surfaces of premolar teeth (n = 7) scheduled for extraction for orthodontic purposes. After extraction, the restored teeth were split transversely by freeze-fracture, critical-point dried and examined under SEM. RESULTS: AB2 and SBMP produced significant gap-free attachment to dentine showing similar microscopic structural features. Resin interdiffusion with collagen fibrils of the intertubular matrix was clearly seen. Microspaces, observed at the periphery of the widened tubules and among the interdiffused collagen fibrils, suggested incomplete resin penetration. Fractures occurring parallel with the interface frequently showed detachment in the deepest layers of the hybrid zone. Adhesive gaps were seen at the resin-dentine interface, indicating some clinical technique failure. The PUB3 attachment was generally incomplete, with separation between the primed dentinal surface and the composite restoration. Where present, the bonded interface showed no evidence of true hybridization. CONCLUSION: Dentine conditioning, as a separate step, prior to priming, appears to be an important factor in successful resin-dentine attachment. Critical-point drying revealed variations in the degree of resin interdiffusion with intertubular collagen, suggesting potential sites for bond failure.
OBJECTIVES: To investigate the effectiveness of an indicator gel in revealing exposed dentine. METHODS: Teeth prepared into dentine and then stained with the indicator gel were sectioned for histological examination. RESULTS: The indicator gel was found to stain dentine and thin layers of enamel. CONCLUSION: The gel is suggested to be an effective indicator as an aid to acid etching and in the preparation of teeth for resin-bonded restorations.
OBJECTIVES: 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. CONCLUSION: GM solution was a better dentine primer than HEMA solution, since HEMA priming did not prevent gap formation under any of the conditions tested.