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Biomedical subjects

D H Retief

Publications and source records attributed to D H Retief.

At least 91 records · Page 5Linked to original sources
PubMed1985

Pyruvic acid as an etching agent in clinical dentistry.

The objective of this study was to evaluate the use of pyruvic acid as an alternative etching agent to phosphoric acid (H3PO4). Solutions containing 5, 10, 15, 20, 25, and 30 m/m % pyruvic acid and 50% m/m H3PO4 were prepared. The tensile bond strengths of a composite resin to enamel surfaces etched with the respective etching agents were determined. The rates of etching of enamel surfaces by each of the etching solutions were evaluated. Unground and polished enamel surfaces were etched with the respective etching solutions and the surfaces examined by scanning electron microscopy. The tensile bond strengths of the resin to enamel surfaces etched with 10-30% pyruvic acid exceeded those obtained on enamel surfaces etched with 50% H3PO4. The rates of etching of all the pyruvic acid solutions were significantly less than of H3PO4. Well-defined etching patterns were observed on the enamel surfaces etched with all the etching solutions. The results of this laboratory study suggest that pyruvic acid may be a suitable alternative to phosphoric acid as an etching agent in clinical dentistry.

Acid Etching, Dental↗
PubMed1985

The effect of topical fluoride treatment on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin.

Enamel demineralization occurring adjacent to directly bonded orthodontic attachments is of great concern to orthodontists. The topical application of fluorides to enamel surfaces before acid etching and the bonding of the attachments is not recommended by many investigators. The objective of this study was to determine the enamel fluoride acquired from various topical fluoride agents and to determine the effect of the acquired fluoride on the tensile bond strength of an orthodontic bonding system. Fifty extracted maxillary central incisors were mounted in cups and the facial surfaces of the crowns were polished on 600-grit silicon carbide paper. Enamel microbiopsies were performed just off the midpoint of each tooth. Ten teeth served as controls and received no topical fluoride treatment, while a similar number were treated with either APF, SnF2, Duraphat, or Fluor Protector. The teeth were suspended in synthetic saliva 4 minutes after fluoride application. The topical fluoride agents were removed after 24 hours and the teeth were again suspended in synthetic saliva at 37 degrees C for 7 days. Enamel biopsies were again performed just off the midpoint of each tooth on the side not previously biopsied. The enamel surfaces were etched for 1 minute and the tensile bond strength of Concise orthodontic bonding system to the etched enamel surfaces was determined. The enamel surfaces acquired significantly different amounts of fluoride from the topical fluoride agents, but the bond strengths to these surfaces were not significantly different. The results of this in vitro study suggest that the application of topical fluoride agents to enamel surfaces 7 days before the bonding of orthodontic attachments will not have an adverse effect on bond strength.

Acid Etching, Dental↗
PubMed1985

Tensile bond strength of a glass-ionomer cement.

The tensile load strength of a glass-ionomer cement to untreated, etched, and citric acid-cleansed enamel, dentin, and cementum was measured. This study also tested one material for which neither conditioning nor etching was recommended by the manufacturer.

Acid Etching, Dental↗
PubMed1985

Relationship between enamel fluoride concentration and dental caries in a selected population.

The relationship between dental caries experience (DMFT) and enamel fluoride concentration (EnF) was determined in 100 freshman dental students aged between 20 and 26 yr. DMFT was determined by clinical examination and supplemented by bitewing radiographs. Biopsies were performed on the maxillary right canine of each student by etching with 1 M perchloric acid for 5 s. A regression analysis of DMFT and EnF and of square root DMFT and 1nEnF indicated that the correlation coefficients were not significant. Students exposed to fluoridated drinking water had significantly lower DMFT and significantly greater EnF than the students reared in areas with non-fluoridated drinking water.

Acid Etching, Dental↗
PubMed1984

Enamel fluoride uptake and acid resistance in subjects with high and low experimental cariogenicity.

The response of bovine enamel to intra-oral cariogenic environments was studied in human volunteers. Enamel slabs were mounted in dentures and treated with either 10% sucrose or 10% sucrose plus 20 ppm fluoride mouthrinses for one minute five times daily. After one week, these enamel slabs were studied for change in surface hardness and for the degree of fluoride incorporation, or for their resistance to acid acquired by the intra-oral exposure. Among the eight subjects, those with the highest experimental cariogenicity exhibited the highest benefit of enamel from the fluoride in terms of fluoride incorporation and in their resistance to the subsequent acid test. The results suggest that cariogenic activity and fluoride will synergistically improve the tooth resistance to subsequent attack, apparently through mineral exchange that favors the formation of acid-resistant minerals with high fluoride content within enamel lesions.

Acids↗
PubMed1983

Acid resistance of enamel exposed to fluoride-containing orthodontic cements.

In a previous study enamel fluoride uptake from fluoride-containing orthodontic cements was evaluated after a 21-day period. The enamel fluoride uptake from a zinc phosphate cement (A), a zinc phosphate cement containing 5 per cent stannous fluoride by weight (B), and a silicophosphate cement (C) was compared. The results indicated that there was a net loss of fluoride from enamel beneath the orthodontic bands cemented with A while the enamel beneath B and C acquired significant amounts of fluoride. The purpose of the present study was to evaluate enamel fluoride uptake after 12 weeks and the effect of the fluoride uptake or loss by the enamel on acid resistance. Five teeth each had bands cemented with cements A, B and C, respectively, and were individually suspended in synthetic saliva for 12 weeks at 37 degrees C. Following this period the bands were removed, the cements were carefully cleaned off the teeth, and the crowns of the teeth were individually suspended in a lactic acid buffer at pH 4 for 4 weeks. Each tooth crown was then sectioned longitudinally and examined microradiographically to study the degree of enamel demineralization. Characteristic subsurface enamel carieslike lesions were noted on all the specimens studied. The carieslike lesions in the enamel exposed to the fluoride-containing cements were considerably reduced. The enamel which had acquired fluoride from the fluoride-containing cements was apparently more resistant to artificial caries attack.

Acids↗