PubMed · 4620525
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A Muangmingsuk. [Acid etch].. https://pubmed.ncbi.nlm.nih.gov/4620525/
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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 AND METHODS: The relationship between dentine bonding and the condition of dentine for four dentine bonding systems (All Bond 2, Clearfil Liner Bond, Scotchbond MP and XR Bond) has been examined. Different dentine conditions were evaluated and correlated with adhesion values. Dentine permeability was calculated using a hydraulic pressure apparatus working under physiological pulpal pressure (6.9 kPa), while remaining dentine thickness (RDT) was measured using pincer calipers. Scanning electron microscopic (SEM) examinations were effected to analyse dentine morphology. These evaluations were considered as an index of the condition of dentine. Shear bond strength tests were used to evaluate adhesion. Dentine samples after the bonding systems application were stored for 24 h under pulpal pressure before bond strength was tested. RESULTS: Scanning electron microscopy examinations indicated that the application of bonding system conditioners caused the removal of smear layer, the demineralization of dentine and the formation of a layer of collapsed collagen fibrils in the intertubular and peritubular dentine. Primers were able to infiltrate the collagen fibrils. A layer of resin infiltrated/reinforced dentine (the so-called 'hybrid layer') was observed for All Bond 2, Clearfil Linear Bond and Schotchbond MP. CONCLUSIONS: Significant correlations were observed only for XR Bond, which proved very sensitive to RDT and dentine permeability despite the presence of smear layer. The other three materials did not show any correlation with dentine conditions. By contrast they showed the highest bond values.
This investigation studied the effects of abrasion and salivary contamination on the shear bond strength of a composite resin bonded to tin-plated gold alloy. Experimental groups (n = 15) consisted of: group 1, no surface treatment; group 2, enamel abraded; and group 3, saliva-contaminated. After surface stressing and bonding, groups were thermocycled before shear testing. Fractured interfaces were analyzed by use of light microscopy and SEM. Specimens in group 3 (12.2 +/- 2.5 MPa) had significantly lower bond strengths than group 1 (17.9 +/- 6.8 MPa). The shear bond strengths of resin bonded to tin-plated metal were significantly affected by salivary contamination but not by abrasion.