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Biomedical subjects

C L Davidson

Publications and source records attributed to C L Davidson.

176 records · Page 10Linked to original sources
PubMedDate not supplied

Effect of mechanical load cycling on the marginal integrity of adhesive Class I resin composite restorations.

OBJECTIVES: The purpose of this study was to determine the effect of cycle loading on the sealing capacity of different adhesive systems in Class I restorations in vitro. METHOD: (1) Clearfil Liner Bond/Clearfil Photo Posterior, (2) Scotchbond Multipurpose/Z100, (3) Syntae/Heliomolar, and (4) Gluma 2000/Pekalux were employed to restore Class I cavities in extracted human premolars and molars. For each test group, half of the specimens were subjected to mechanical loading at 125 N for 5000 cycles in a dye solution. After sectioning, dye penetration was assessed. RESULTS: Without loading, no specimen showed leakage, while loading did affect the sealing capacity of groups 3 and 4. Groups 1 and 2 showed no significant increase in leakage after the loading procedure. CONCLUSION: The results indicate that mechanical cycle loading can adversely affect the interface of adhesive Class I resin composite restorations unless hybridizing adhesive systems are used.

Acrylic Resins↗
PubMedDate not supplied

Occupational contact dermatitis of the upper extremity.

Workers in certain occupations are at particular risk for developing contact dermatitis of the hand and upper extremity. Recently published findings concerning risks faced by food handlers, hairdressers, and horticulturists are addressed here. Preventive measures, including protective clothing and barrier creams, also are discussed.

Beauty Culture↗
PubMedDate not supplied

Sealing capacity of a resin-modified glass-ionomer and resin composite placed in vivo in Class 5 restorations.

A 2% methylene blue dye was used to assess the leakage resistance of class 5 resin-modified glass-ionomer and resin composite restorations placed in 17 adults. The teeth were extracted 75 to 90 days after placement of the restorations and immersed for 24 hours in the dye solution. Within 7 days after extraction the teeth were sectioned inciso-apically through the center of the restoration and inspected under a stereomicroscope at X20 to determine the depth of dye penetration. No significant differences between the resin-modified glass-ionomer and resin composite restorations at the incisal or cervical margins were found. Although no more than 30% of the restorations of either group exhibited microleakage, neither of the restorative systems was able to completely prevent leakage at either incisal or cervical margins.

Adult↗
PubMedDate not supplied

Comparison of in vivo and in vitro demineralized dentin with phosphoric and maleic acid.

This article evaluated possible differences between dentin conditioned in vivo and in vitro with 10 percent maleic acid or with 36 percent phosphoric acid. Semispherical Class V cavities were prepared in vivo and in vitro at the cementum-enamel junction and were divided into four groups. After etching procedures, the in vivo samples were extracted and fixated in 10 percent buffered formaldehyde. Both the in vivo and in vitro samples were then fractured in two parts along their long axis, critical-point dried, and subsequently examined with SEM. Both the acids removed completely the smear layer and demineralized the dentin, leaving a layer of collagenous network. No morphological differences were found between in vivo and in vitro dentin samples.

Acid Etching, Dental↗
PubMedDate not supplied

Glass ionomer cement, an intelligent material.

The main task of a dental filling material is to permanently seal the dentinal wound and to restore the anatomy. In particular with respect to the former requirement, glass-ionomer cements exhibit, thanks to it's ingenious composition, unique properties, which allows it to react on external information in such a way that the cement automatically and adequately fulfills it's function as a proper restorative material. Because of it's setting mechanism, glass-ionomer cement restorations have a better perspective to seal the tissue than amalgam or resin composites do. As resistance to wear of glass ionomers is inferior to resin composites it proves to be a better dentin replacement, than a substitute for tooth enamel. Restorations made in a combination of glass-ionomer cement and resin composite, the so called sandwich restorations, have shown to function excellently, both at the tooth interface as well as the outer surface. As any leakage still cannot be excluded, the fluoride release at the margins of the restoration forms a wellcome contribution to the prevention of secondary caries. Once more, glass-ionomer cement shows to be intelligent by automatically activating an advantageous process when the environment requires it.

Dental Bonding↗