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Biomedical subjects

R B Joynt

Publications and source records attributed to R B Joynt.

28 records · Page 2Linked to original sources
PubMed1987

Effects of composite restorations on resistance to cuspal fracture in posterior teeth.

A clinically acceptable MOD cavity preparation was used instead of a jig-mounted slot preparation in this investigation. Each preparation was proportional to the tooth dimension. The design of the testing instrument ensured that forces applied to the specimens were applied to tooth structure and not to the restorative material. Prepared unrestored teeth were weaker than restored teeth. No significant difference was noted in fracture resistance between teeth restored with amalgam and with composite resin. The method used in this study is replicable, allowing the possibility of comparison studies by using identical procedures. Future research will focus on issues of polymerization method and modulus of elasticity and their effects on fracture resistance of remaining tooth structure.

Bicuspid↗
PubMed1985

Use of technique metal in preclinical education: effect on student products and performance.

As a result of the theft of dental students' gold issue, use of a less expensive technique alloy in a preclinical course was evaluated as a substitute for conventional gold alloy. Three-unit all-metal fixed partial dentures were fabricated by sophomore dental students as part of a fixed prosthodontics preclinical technique course. One group of students used a conventional gold alloy and a second group used a technique alloy. Except for solder joint appearance, similarities in student performance and perceptions indicated that technique alloy is an acceptable, cost-effective substitute for gold in preclinical courses.

Clinical Competence↗
PubMedDate not supplied

Influence of finishing technique on microleakage.

Four different finishing techniques were used in a dentin bonding agent/composite resin restoration to evaluate the possible influence of finishing technique on microleakage. Results indicated that finishing technique affects the ability of the restorative system to resist microleakage. Under the conditions of this study, best results were achieved with a 30-fluted bur followed by a short wet polish. Samples finished dry with polishing disks demonstrated considerable microleakage. This study also suggests that homogeneous nonagglomerated microfilled composite resin does not require disk finishing.

Chi-Square Distribution↗
PubMedDate not supplied

Evaluation of microleakage in tenure-based restorations.

This study evaluates the effects of six composite resins, which use three different curing systems, on the ability of Tenure to resist microleakage. The curing systems were a photoinitiated dual-cure system, a dual-cure system, and light-cure systems. A total of 39 human molars were used. Following 2,000 cycles on a thermocycler, specimens were exposed to 0.2 percent basic fuchsin dye for 24 hours and then examined for microleakage. Results indicated that the composite resin plays an important role in the ability of a restorative system to resist microleakage. The photoinitiated dual-cure system produced significantly less microleakage than light-activated systems. No difference in microleakage was found between light-activated systems and the dual-cure system.

Composite Resins↗
PubMedDate not supplied

Microleakage evaluation in amalgam restorations used with bases.

Marginal leakage in amalgam restorations often precedes the development of secondary caries. One potential way to improve the marginal seal of such restorations, and thus minimize the risk of caries development, is to apply a glass-ionomer base prior to amalgam placement. This study compared microleakage resistance among amalgam restorations placed with and without light-cured glass-ionomer base materials. Preparations were made in extracted human molar teeth. Four groups were studied, including copal varnish, which was used as a control. All specimens were restored with amalgam. Results indicated significantly greater leakage at the cavity wall/base interface for restorations with a copal varnish cavity liner than for those with a glass-ionomer base. Leakage differences among bases were also found at the amalgam/base interface. Best results were obtained with a dual-cure resin-based system. These samples showed minimal leakage at both the cavity wall/base and the base/amalgam interfaces. These findings suggest that light-cured glass-ionomer bases can be effective in the prevention of microleakage in amalgam restorations.

Analysis of Variance↗
PubMedDate not supplied

Leakage patterns associated with glass-ionomer-based resin restorations.

This study compared microleakage patterns for glass-ionomer-cement-based resin systems with and without a separating agent placed between the glass ionomer and resin. Results indicated significant leakage (100%) at the dentin glass-ionomer interface for specimens without a separating agent. Those with a separating agent showed almost no leakage between the dentin and glass ionomer (10%) and some leakage at the resin/glass ionomer interface (40%). These results suggest that the forces of polymerization shrinkage are stronger than the chemical bond between glass-ionomer cement and dentin. This bond fails during resin polymerization, eliminating any supplementary retention gained through chemical adhesion to dentin and opening a pathway for microleakage.

Chi-Square Distribution↗
PubMedDate not supplied

Adhesion of direct restorative materials.

The development of adhesive restorative systems has been a major focus in dentistry. Materials that can attach to tooth structure make it possible to take a far more conservative approach to restorative dentistry.

Adhesives↗
PubMedDate not supplied

Dentin bonding agents and the smear layer.

The morphology and treatment of the smear layer are discussed. Also included are a review of dentin bonding agent classification and chemistry, and a summary of recent bond strength research results. Finally, the current status of dentin bonding agents is discussed.

Dental Bonding↗
PubMedDate not supplied

Effect of dentinal pretreatment on bond strength between glass-ionomer cement and dentin.

Removal of the dentinal smear layer prior to placement of glass-ionomer cement is thought to maximize the strength of glass-ionomer cement/dentin bonding. This study evaluated the effect of three polyacrylic acid pretreatments on bond shear strength between glass-ionomer cement and dentin. Extracted human molars were divided into four groups of 30 specimens each. One group (the control) received no pretreatment. Specimens in the remaining groups were pretreated with one of three commercially available polyacrylic acid conditioners, used according to the manufacturers' recommendations. The results indicated significant differences in shear strength among pretreatment conditions. Since the manufacturers' recommendations varied, it is not clear if these results were due to differences in polyacrylic acid concentration or to other factors, such as application time or placement procedure.

Dental Bonding↗