PubMed Health⌕ Search

Biomedical subjects

J B Dennison

Publications and source records attributed to J B Dennison.

At least 37 records · Page 2Linked to original sources
PubMed1985

Three-year evaluation of sealant: effect of isolation on efficacy.

This study analyzes the clinical effectiveness of a sealant (Delton) and its requirements for retreatment to maintain the optimum protection from pit and fissure caries. One hundred paired occlusal surfaces were treated in 29 patients. Two contralateral, partially erupted, noncarious molars with deep occlusal fissures were randomly selected to receive a sealant; one had a rubber dam and the other, cotton rolls for isolation. Each tooth received a prophylaxis with a rubber cup and a pumice slurry. The dryness of the field was evaluated. Each tooth was etched with 37% phosphoric acid for 60 seconds, rinsed for 15 seconds, and dried for 30 seconds. Sealant (Delton Tinted) was applied with a syringe according to manufacturer's instructions. Sealants were evaluated and reapplied where indicated at 6-month intervals. The average 6-month retention rate over 36 months was 95%, regardless of the method of isolation used when the sealant was applied initially. No tooth under treatment with a sealant became carious. The retreatment rate was highest at baseline (8%) and at 6 months (11.3%). Of the total number of retreated sealants, 61% were from the mandibular arch. During the 36 months of this study, 31% of the treated teeth required at least one retreatment.

Acid Etching, Dental↗
PubMed1982

Status report on microfilled composite restorative resin. Council on Dental Materials, Instruments, and Equipment.

Microfilled resins generally have physical properties inferior to those of conventional composites. A lower in organic filler content or higher polymer/filled ratio results in a lower modulus of elasticity, greater thermal dimensional change, less resistance to indentation and abrasion, and greater water sorption. The ability to finish and to maintain a smooth surface texture is a major advantage, although it has not been proved clinically that microfilled resin restorations result in less plaque adherence nor do they enhance soft tissue response. Early clinical trials, after two to three years in vivo, indicate a greater wear resistance for these materials than for conventional composites. At this time, current evidence suggests that a decrease in filler particles size to less than 1 micrometer and a lower filler loading of the resin matrix permit the clinical development and maintenance of a smooth surface texture on restoration surfaces. There is no published evidence that the decrease in many of the physical properties leads to early signs of clinical deterioration and failure. In vivo studies extended for longer periods are necessary to make a knowledgeable judgment on the true clinical value of these composites. A classification system for composite restorative resins is being prepared by the Council on Dental Materials, Instruments, and Equipment. It will be published in a future issue of The Journal.

Chemical Phenomena↗
PubMed1981

Surface roughness of microfilled composites.

Average surface roughness values, profile tracings, and surface microstructures of three microfilled composites and a conventional composite were studied with respect to final finishing procedures. Surfaces cured against Mylar matrix strips were the smoothest and were similar for all composites. White stones produced the roughest surfaces for Isopast, Silar, and Superfil. Silicon carbide disks and aluminum oxide disks produced smoother surfaces. The finished surfaces of the microfilled composites were smoother than the corresponding surfaces of Concise for each finishing instrumentation evaluated.

Acrylic Resins↗
PubMed1980

Surface roughness of two dental amalgams after various polishing techniques.

1. In comparison with standard polishing after 24 hours, no advantage is gained by using an abrasive paste after 10 minutes. Polishing after 24 hours produced a significantly smoother surface for both amalgam alloys on both the simulated proximal and occlusal surfaces. 2. The standard polishing procedures after 24 hours produced a smoother surface than any of the immediate finishing procedures tested. 3. The high-copper amalgam was signijficantly rougher with initial carving and immediate finishing, but surfaces of both alloys were equally smooth when polished after 24 hours. 4. Both amalgam alloys, when condensed against a new matrix band lacked smoothness when compared to the surfaces obtained by finishing after 24 hours. 5. There was a high correlation between arithmetic average roughness and average maximum peak height as quantitative measurements of surface texture.

Chemical Phenomena↗
PubMed1980

Testing of color stability of composites.

The color stability of five commercial composites was evaluated according to a proposed modification of ADA Specification No. 27. After exposure of 24 hours to a sunlamp, light-cured composites showed greater changes in color than conventional and microfilled, amine-cured composites. Factors of evaluator and viewing condition affected discrimination of color differences.

Chemical Phenomena↗
PubMed1979

Thermal expansion of composite resins and sealants.

Linear thermal coefficients of expansion (alpha) of seven commercial composite resins and four pit and fissure sealants were determined between 0 and 60 degrees C on a thermomechanical analyzer. The thermal expansion curves obtained were nonlinear. Values of alpha ranged from 26.5 to 39.6 x 10(-6) degrees C for the composite and from 70.9 to 93.7 x 10(-6)/degrees C for the sealants.

Composite Resins↗