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Biomedical subjects

D M Barnes

Publications and source records attributed to D M Barnes.

277 records · Page 16Linked to original sources
PubMedDate not supplied

Evaluation of clinical performance of twelve posterior composite resins with a standardized placement technique.

The purpose of the study was to evaluate 12 posterior composite resins with a standard clinical placement technique that could be followed in a practice setting. Important points stressed are the use of rubber dam, care taken to detail on manufacturer's directions, incremental placement technique, and a standard finishing technique. Sixty-one Class II restorations were placed by a single operator. All of the restorations were evaluated at baseline, one and three years using the modified Ryge criteria. Indirect evaluation of wear was completed for each restoration using Leinfelder's technique. Two percent of the restorations at 1 year and 17 percent at 3 years were not clinically acceptable.

Bicuspid↗
PubMedDate not supplied

Flow characteristics and sealing ability of fissure sealants.

This study evaluated the relationship between fissure sealant viscosity, leakage prevention and the incidence of void formation of five commercially available pit-and-fissure sealants. Seventy-two intact, caries free human pre-molars and molars were divided into six test groups of 12 teeth each. All teeth were cleaned with a flour of pumice prophylaxis followed by etching for 60 seconds with 37% H3PO4, rinsing for 30 seconds and drying with oil-free air. Five commercial, light-cured fissure sealants and an unfilled version of one sealant were applied following manufacturers' instructions. Teeth were thermal cycled for 5000 cycles from 5-50 degrees C with a one-minute dwell time at each temperature. Silver nitrate staining followed by mesiodistal sectioning was performed. Leakage and void formation were evaluated at X50 optical magnification. Viscosity was assessed by syringing the fissure sealants into short pipettes, allowing free flow for 30 seconds and then light curing for one minute. The length of unfilled capillary was measured with a Vernier gauge. All experimental data was subjected to a one-way ANOVA, and where differences were detected, they were identified by a post hoc Tukey hsd test at a priori alpha = 0.05. Based on the conditions of the study, viscosity and flow characteristics had no effect on sealing ability or void formation.

Acid Etching, Dental↗
PubMedDate not supplied

The effect of tooth preparation on microleakage behavior.

Many factors contribute to the microleakage of a restoration. One of the more important is the method of cavity preparation. This study compared the microleakage behavior of composite restorations placed in cavities prepared by different techniques. It also compared and correlated the microleakage data produced by an electrochemical vs a staining technique. Class V cavities were prepared in 48 premolars by four techniques: (1) tungsten carbide bur in a high-speed handpiece followed by acid etching; (2) air abrasion (27 microns Al2O3) followed by acid etching; (3) air abrasion (50 microns Al2O3) and (4) air abrasion (27 microns Al2O3), with n = 12 in each group. All teeth were restored with Prime and Bond 2.1 and Tetric Flow, then thermocycled between 5 degrees and 55 degrees C for 5000 cycles with a one minute dwell at each temperature. After thermocycling, a PVC-covered Cu wire was inserted apically into the pulp chamber of each tooth and sealed into position. Leakage was continuously followed by a conductimetric method for 75 days. The teeth then were immersed in 50% AgNO3 for two hours, rinsed in distilled water for 60 seconds, then placed in a rapid photographic developer solution for two hours, followed by rinsing and sectioning for microscopic examination. Electrochemical data were examined by ANOVA and Newman-Keuls multiple comparison tests, while Kruskal-Wallis and Rank Sum Difference tests were used on the staining evaluations. Spearman's rho test was used to correlate the two test techniques. Electrochemical data for cavities prepared with a bur or air abrasion followed by acid etching prior to restoration showed significantly less (p < or = 0.05) microleakage (mean leakage currents of 1.89 & 1.57 microA, respectively) than teeth prepared with air abrasion alone (mean leakage currents of 3.60 & 3.40 microA, respectively). Rank sum AgNO3 staining data (196 & 242 vs 371 & 368) supported these findings. The correlation between the electrochemical and staining data was significant (p < or = 0.05) for all four groups of test specimens.

Acid Etching, Dental↗
PubMedDate not supplied

Ethylene glycol intoxication in ducks.

Ducks maintained over winter in an area used for automobile storage and repair were poisoned by anti-freeze. Signs were weakness, depression, ataxia, and death. Post-mortem lesions consisted of marked nephrosis; numerous oxalate crystals occluded the renal tubules. Levels of ethylene glycol were markedly elevated compared with levels in normal tissues. To further characterize the disease, six healthy ducks were given ethylene glycol in oral doses ranging from 1.1 to 17.8 ml/kg. As the dosage was increased, blood and tissue concentrations of ethylene glycol increased and time to death decreased. Histologic lesions were similar to those seen in the accidentally poisoned ducks.

Animals↗
PubMedDate not supplied

Microleakage of Class 5 composite resin restorations: a comparison between in vivo and in vitro.

The purpose of this study was to determine if a difference exists in microleakage between in vivo and in vitro class 5 composite resin restorations using two variations of a bonding resin (Universal Bond 2 and Universal Bond 3). Class 5 cavities were prepared in 24 matched pairs of teeth on the buccal and lingual surfaces. One tooth of each pair was prepared and restored in vivo and the other in vitro. After preparation and enamel etching, Universal Bond 2 was randomly applied to one surface of each tooth in the pair and Universal Bond 3 to the other surface. Composite resin (Prisma AP.H) was placed in each preparation, light cured, and finished using a standard technique. The in vivo samples were extracted approximately 6 weeks after placement of the restorations. The in vitro samples were thermocycled for 540 cycles (5 to 55 degrees C/1-minute dwell time). All teeth were stained with silver nitrate and longitudinally divided. The teeth were scored on a ranking system of 0 being no leakage to 4 being leakage to the pulpal wall of the preparation. A Wilcoxon matched pairs signed rank test was performed on the data (P < or = 0.05). There were no statistically significant differences in microleakage between restorations using Universal Bond 2 and Universal Bond 3. There were statistically significant differences when comparing the in vivo and in vitro restorations. More microleakage occurred in the in vitro restorations.

Adult↗
PubMedDate not supplied

Microleakage in facial and lingual Class 5 composite restorations: a comparison.

The purpose of this in vitro study was to determine if there is a difference in microleakage between facial and lingual enamel and cementum using two different evaluation techniques. Class 5 preparations were made in 50 teeth on the facial and lingual tooth surfaces and restored using dentin bonding and composite resin. The teeth were thermocycled, silver nitrate stained, and longitudinally sectioned into mesial and distal halves through each restoration. The mesial half was scored using a rank order system. A Kruskal-Wallis one-way ANOVA was performed. The distal half was scored by measurement, and a two-sample t-test was performed. There were no statistically significant differences (P > or = 0.05) in microleakage between facial and lingual tooth enamel or cementum surfaces using either measurement technique.

Analysis of Variance↗