The determination of the effect of the internal surface roughness and cement space upon crown retention
Date
1990
DOI
Authors
Juntavee, Niwut
Version
OA Version
Citation
Abstract
This study evaluated crown retention relative to five variables; core materials (amalgam and composite resin core), cements (zinc phosphate, glass ionomer and resin cement), cement film thicknesses (50, 100, and 150 microns), internal surface roughness of retainers, and thermal stress.
Three hundred sixty (360) cylindrical amalgam cores (Valiant, Caulk, Dentsply) and composite resin cores (Core-Paste, Den Mat) were made in a teflon coated aluminum mold. Sixty cores of each type were 8.7, 8.8, 8.9 mm. in diameter and 6.0 mm. in length. Three hundred sixty (360) cylindrical retainers 12.0 mm. in external diameter, 9.0 mm. in internal diameter, 1.5 mm. thickness, and 6.0 mm. in length were made from base metal alloy (Rexillium III, Rx. Jenerix, Wallingford, CT.). One hundred eighty (180) cylindrical retainers were sandblasted with fine (60 microns) aluminum oxide abrasive, and one hundred eighty (180) were sandblasted with coarse (280 microns) aluminum oxide abrasive. All cores were cemented to cylindrical retainers using three types of cement; zinc phosphate cement (Mission, White Dental Inc., NJ, USA), glass ionomer cement (Ketac-Cem, Espe, Premier, PA, USA), and resin cement (Panavia Ex., Kuraray, Japan). Thirty six (36) groups of core-retainer assemblies, consisting of ten (10) samples for each group were obtained according to cement type, cement film thickness, core material, and internal surface roughness of retainers. Each group was subdivided into 2 groups yeilding a total of seventy two (72) subgroups, consisting of thirty six (36) control groups and thirty six (36) experimental groups of five (5) samples each. All samples were stored in 100 % humidity at 37 C Samples in experimental groups were thermocycled one week after cementation. All samples were tested for retentive bond strength by pushing cores from their retainers at a constant rate (0.02 cm/min) with the Instron universal testing machine (Instron Corp., Canton, MA). The values obtained were subjected to a five way analysis of variance (ANOVA). Further statistical analysis of variance was pursued by using the Newman-Keuls test.
The highest bond strength was obtained with composite resin cores (Core-Paste) cemented with resin cement (Panavia Ex.) to retainers with coarse internal surfaces at a cement film thickness of 50 microns. The lowest bond strength was obtained with composite resin cores (Core-Paste) cemented with glass ionomer cement (Ketac-Cem) to retainers with fine internal surfaces at a cement film thickness of 150 microns. Amalgam (Valiant) was superior to the other core materials no matter what type of cement used. Resin cores appear to contribute a lower bond strength than amalgam except when used with resin cement (Panavia Ex.) Zinc phosphate (Mission, White Dental Inc.) and resin cement (Panavia Ex.) appeared to be far better than glass ionomer cement (Ketac-Cem, Espe, Premier) for all samples. Thermocycling reduced the bond strength of all cement-core samples. Cement film thicknesses of 50 and 100 microns proved to be acceptable. Retainers with coarse internal surfaces exhibited a higher bond strength than those with fine internal surfaces.
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Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1990 (Prosthodontics).
Bibliography : leaves 89-105.
Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1990 (Prosthodontics).
Bibliography : leaves 89-105.
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This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.