PubMed · 3861350
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M Busch. 1985. [Basic ceramic coating technic for cold light curable composite veneers].. https://pubmed.ncbi.nlm.nih.gov/3861350/
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STATEMENT OF PROBLEM: Mechanical retentive devices and the application of complicated surface preparation have been indispensable for bonding composite material to the metal substructure of restorations. PURPOSE: This study evaluated the priming effects of 4 metal conditioners on bonding between a prosthetic veneering material and a silver-palladium-based casting alloy. MATERIAL AND METHODS: Four primers designed for conditioning noble metal alloys (Alloy Primer, Metaltite, Metal Primer II, and V-Primer) were assessed (all materials contain organic sulfur compounds). Cast disk specimens made of silver-palladium-copper-gold alloy (Castwell M.C.12) were primed with 1 of the 4 primers, and bonded with a light-activated prosthetic composite material (Axis). Shear testing was performed before and after thermocycling for evaluation of bond durability. RESULTS: All primed groups showed improved 24-hour bond strengths compared with the unprimed group. After thermocycling, 3 groups primed with the Metal Primer II, Alloy Primer, and Metaltite agents exhibited the highest bond strength. CONCLUSION: Use of 1-liquid metal conditioners containing sulfur compounds was a simple and useful method for improving bonding between the alloy and the composite material tested.
The load applied to a tooth surface during mastication is not a constant force and the objective of the research reported in this paper was to evaluate the impact of variable masticatory loads on the mechanisms involved in the wear of a dental composite. A new wear testing machine has therefore been developed, which incorporates a sine cam mechanical system to generate an alternating sine curve load at the wear surfaces to simulate the loading produced by masticatory process. The basic wear pattern is generated by positioning a disc shaped specimen against a rotating cylindrical ring with a normal load applied to the upper surface of the specimen. This approach allows different combinations of static and sine curve loads to be applied, thereby facilitating the study of different wear situations. It was found that the wear behaviour associated with variable loading patterns differed from that of static loading.
OBJECTIVES: The light intensity of curing lights used in private dental offices was measured using commercial curing and heat radiometers and related to uniformity of cure depth of standardized composite specimens. METHODS: The intensity of 130 curing light from 107 dental offices was measured with curing and heat radiometers. Due to analogue readings, results were recorded in steps of 25 mW cm-2 and assigned a category number. A total of 50 lights were randomly selected to polymerize standardized 3 mm thick composite cylinders. The composite was irradiated for 50 s according to the manufacturer's instructions. The Knoop hardness value was measured at the top and bottom surfaces and the uniformity of cure depth was calculated from the ratio of these two values. RESULTS: Light intensity measured by the curing and heat radiometers was in the range of 25-825 and 0-325 mW cm-2, respectively. Functions of maximum likelihood estimation of the top and bottom surface hardness were 57 N/N + 1.3 and 80 N/N + 17.7, respectively (N = light intensity category number). The relationship between the logarithmic transformation of the hardness ratio and light intensity was linear (R2 = 0.84 p < 0.001). CONCLUSION: According to the manufacturer, a curing light is considered as unsuitable for use with a reading of < 200 mW cm-2 by the curing radiometer and > 50 mW cm-2 by the heat radiometer. Applying these criteria to the present study, 46% of the lights (without repetitions) required repair or replacement. The strong correlation found between the hardness ratio and light intensity verifies the usefulness of the curing radiometer in predicting the polymerization ability of the light activation units.