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Biomedical subjects

C M Russell

Publications and source records attributed to C M Russell.

At least 73 records · Page 4Linked to original sources
PubMed1992

Enamel, cementum and dentin fluoride uptake from a fluoride releasing resin composite.

The purpose of this study was to determine the fluoride release by and the enamel, cementum and dentin fluoride uptake from a visible light-cured fluoride-containing resin composite. Seven circular discs of the composite were prepared and the fluoride release in distilled water determined at daily intervals for 14 days, and then after 30, 90, 180, 365 and 550 days. The baseline fluoride concentrations in enamel and cementum were determined in three successive depths by an acid etch biopsy procedure and in dentin by an abrasion biopsy procedure. Composite slabs were prepared and ligated to the enamel, cementum and dentin surfaces and the teeth were suspended in synthetic saliva for 7 or 30 days. After removal of the composite, similar biopsy procedures were performed. The teeth were then immersed in 1 M KOH for 24 hours and similar biopsies done. The fluoride concentrations were adjusted to standardized depths of 2.0 microns for enamel, 4.0 microns for cementum and 10.0 microns for dentin, and the total and bound fluoride uptake calculated. The fluoride release from the composite dropped sharply after 1 day and after 180 days reached a plateau which remained relatively constant up to 550 days. The results of this in vitro study indicated that the mineralized dental tissues acquired fluoride at various depths.

Analysis of Variance↗
PubMed1992

Microleakage of Vitrebond/P-50 Class II restorations.

Thirty extracted human mandibular permanent first and second molars were used in this study. Class II preparations were made extending 1 mm below the CEJ at the mesial and 1 mm above the CEJ at the distal aspects. In 15 of the teeth Vitrebond was applied to all exposed dentin (A) while in 15 teeth the gingival floor was left exposed (B). After cure, the enamel margins were etched with H3PO4 gel and the Vitrebond surfaces were treated with Scotchbond 2. The P-50 was transferred to the approximal boxes and occlusal aspects in three increments, each compressed firmly and cured for 60 seconds. The restored teeth were stored in saline at 37 degrees C for 1 week. The teeth were thermocycled x250 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C with a dwell time of 15 seconds. The teeth were embedded in epoxy resin and five mesiodistal sections cut. Microleakage at the mesial and distal aspects were scored from 0 to 3 depending on the extent of the microleakage. The data were analyzed by the Wilcoxon 2-sample and the matched pair signed rank tests. Leakage above the CEJ was significantly less than below the CEJ and significantly reduced when Vitrebond was extended to the cavosurface margins.

Acid Etching, Dental↗
PubMed1992

Effect of axial load and temperature cycling on microleakage of resin restorations.

This study evaluated the microleakage of Class V resin restorations subjected to temperature and axial load cyclings. The preparations were made at the mesial and distal aspects of 29 mandibular first and second molars. The enamel margins were beveled, acid etched, washed and dried. Kerr XR Bonding System was applied to the dentin and etched enamel and Herculite composite cured in two increments. The teeth were stored in saline for 7 days, thermocycled x500 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C (A); subjected to an occlusal load of 34 MPa in the dye without thermocycling (B); or followed by thermocycling (C). The leakage was scored from 0 to 4 at both the enamel and cementum aspects of the restorations. The data were analyzed by the Kruskal-Wallis test. The microstrain of five restored teeth subjected to an occlusal load of 34 MPa was measured. Microleakage of the mesial restorations was significantly greater at the cementum aspects of the restorations subjected to both temperature and occlusal loading when compared to the restorations subjected to temperature cycling or load cycling only. The microstrain in eight of the 10 restorations was significantly greater at the cementum aspects of the restorations than at the enamel aspects.

Bite Force↗
PubMed1992

Phosphoric acid as a dentin etchant.

This study determined the effect of phosphoric acid (H3PO4) application to dentin on the shear bond strength (SBS) and microleakage of an experimental bonding system. Thirty human maxillary permanent first and second molars were used for the SBS evaluation. In 15 of the teeth the Dentin Conditioner was applied to dentin for 30 seconds (A), while in the remaining 15 teeth the smear layer was removed by the application of a 37% H3PO4 gel for 20 seconds (B). The Primers 1 and 2 were mixed and applied to the conditioned dentin followed by the application of the Dentin Bonding Resin prior to the placement in three increments of the Bisfil-M composite. The specimens were stored in physiological saline at 37 degrees C for 24 hours prior to applying a shear load at a crosshead speed of 0.5 mm. inch-1 in an Instron machine. Shear bond strengths were expressed in MPa. Circular Class V preparations were made on the roots of 30 maxillary permanent canines, 15 restored using the Dentin Conditioner (C) and 15 by removing the smear layer with the H3PO4 gel (D). Microleakage of the restorations was determined quantitatively by means of a spectrophotometric method. The quantitative microleakage was expressed as microgram dye/restoration. The data were analyzed by the Student t-test. The following results were obtained: A: 14.2 +/- 2.2 MPa; B: 7.2 +/- 4.2 MPa; C: 30.0 +/- 28.6 micrograms dye/restoration; (D) 10.3 +/- 8.2 micrograms dye/restoration. Removing the smear layer with H3PO4 reduced the SBS to dentin but decreased the quantitative microleakage significantly.

Acid Etching, Dental↗
PubMed1992

Gluma shear bond strength to enamel and dentin treated with pyruvic acid and glycine.

The purpose of this study was to determine the effect of pyruvic acid and glycine on the shear bond strength (SBS) of the Gluma Bonding System to dentin and enamel. Forty-five mandibular and maxillary permanent first and second molars and 45 maxillary permanent central incisors were used in the study. Fifteen test specimens were prepared with each of the following procedures. Dentin: using the conventional Gluma Bonding System (A); the Gluma 2 Cleanser was replaced with 10% pyruvic acid containing 10% glycine with pH 2.8 (B); or the dentin was etched with 10% pyruvic acid (pH 1.5) followed by the application of 10% glycine with pH adjusted to 9.0 (C). Enamel: etched with Gluma 1 Etchant (D); etched with 10% pyruvic acid containing 10% glycine (E); or etched with 10% pyruvic acid followed by the application of 10% glycine (F). The test specimens were disassembled 15 minutes after cure, stored in physiological saline at 37 degrees C for 24 hours, and the SBS determined in an Instron machine at a crosshead speed of 0.5 mm.min.-1 The SBS was expressed in MPa. The data were analyzed by ANOVA and the Student-Newman-Keuls test. The mean +/- SD of the SBS in MPa were: A: 8.7 +/- 5.2; B: 14.7 +/- 4.6; C: 12.8 +/- 4.8; D: 19.8 +/- 3.8; E: 18.0 +/- 3.1; F: 17.6 +/- 3.5. The application of 10% pyruvic acid containing 10% glycine, and 10% pyruvic acid followed by 10% glycine, resulted in a significant increase in SBS to dentin. The SBS to enamel treated with the three procedures were not significantly different.

Acid Etching, Dental↗
PubMed1991

Determining therapeutic efficacy in recurrent herpes labialis by lesion size analysis.

We devised an experimental model for the analysis of therapeutic efficacy of topical medications for recurrent herpes labialis with a double-blind, placebo-controlled format. Rigid prestudy screening evaluations allowed the enrollment of a homogeneous starting population with characteristic herpetic reactivation in an early stage. Using precise measurements of lesion area for a 5-day period, we evaluated the effects of a novel medication containing tannic acid, which has demonstrated impressive inhibitory effects on herpes simplex virus in many recent studies, and salicylic acid, which has rapid absorption kinetics and substantial topical anti-inflammatory and keratin-disrupting properties. Using parametric and nonparametric tests, we studied differences in mean lesion size and used these measurements to evaluate objective and clinically applicable improvement criteria. Although there were no significant differences in mean lesion size at presentation (day 1) between the active medication and placebo groups, the former demonstrated significantly smaller lesions at days 2 through 5 (p less than 0.05). By day 5, 10 of 14 treated subjects showed improvement as defined by a 25% reduction in lesion size compared with day 1, in contrast to only 2 of 12 subjects in the placebo group (p = 0.0079, Fisher's Exact Test). This model can be employed in the evaluation of topical antiviral agents for herpes labialis in a healthy population, because it standardizes criteria for subject enrollment and provides objective and reproducible measurements of therapeutic efficacy.

Antiviral Agents↗
PubMed1991

The effects of thermal and occlusal stresses on the microleakage of the Scotchbond 2 dentinal bonding system.

The microleakage of the Scotchbond 2 Dentinal Bonding System was evaluated under various experimental conditions. In this in vitro study, Class V restorations involving both enamel and cementum were placed on the buccal surfaces of 54 extracted human permanent canines and on the buccal and lingual surfaces of eight extracted human permanent mandibular molars. The canines were divided into three groups, each undergoing different conditions of thermocycling in 0.5% basic fuchsin or distilled water and storage time in the dye. The molars were subjected to an occlusal load of 8 MPa for 66,000 times prior to being thermocycled. There were no significant differences in microleakage of the restorations placed in the canine teeth; however, microleakage in the group of molars subjected to occlusal stresses was significantly increased. This may have been due to the increased length of the restorations placed in the molar teeth.

Composite Resins↗
PubMed1991

Evaluation of various forms of calcium hydroxide in the monitoring of microleakage.

Calcium hydroxide has been shown to be an effective medium for the in vivo microleakage testing of amalgams. The purpose of this study was to determine the relative effectiveness of several forms of calcium hydroxide in the measurement of this clinical problem. It was also the purpose of this study to determine whether a relationship exists between the pH of the Ca(OH)2 liner and its ability to detect microleakage. Standardized Class V preparations were generated on the buccal surfaces of extracted molars. The axial walls of the preparations were based either with Dycal, Dycal VLC, Pulpdent Liquid, or pure Ca(OH)2. A series of teeth without a calcium hydroxide base served as the negative control. All teeth were restored with a spherical amalgam and kept in de-ionized water. The surfaces of the restorations were then subjected to 20 mL of 2 degrees C water for a period of one min. After three min, a color-indicating pH paper was positioned over the restored area for detection of the presence of hydroxyl ions at the amalgam/tooth interface. Regardless of the form of calcium hydroxide, all indicated extensive microleakage immediately after insertion of the restoration. In all cases, the number of samples generating positive results for leakage decreased over a period of time. The rate of decrease, however, was substantially dependent upon the form of calcium hydroxide used as well as its pH. The reagent grade of Ca(OH)2 generated the greatest percentage of positive results for the longest duration.

Calcium Hydroxide↗
PubMed1990

Effect of surface penetrating sealant on wear rate of posterior composite resins.

Although posterior composite resins have been improved considerably, secondary caries and wear continue to be a major concern. Recent studies suggested that microstructural defects such as voids and microcracks contribute to a weakened surface. The purpose of this study was to evaluate the effect of an experimental surface-penetrating sealant on the wear resistance of a posterior composite resin. At the end of 1 year, the rate of wear of the treated restorations was one-half of those not receiving the surface penetrating sealant.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1990

Shear bond strengths to dentin and fluoride release from fluoride-containing liners.

The purpose of this study was to determine the shear bond strengths of five commercially available fluoride-containing restorative systems to dentin and to evaluate the fluoride release from them. The five systems evaluated were: (A) Vitrabond/Silux; (B) Zionomer Powder Liquid/Perfection; (C) Zionomer Paste Paste/Perfection; (D) TimeLine/Prisma-Fil; and (E) GC Dental Cement/Fuji II. Eighteen test specimens were prepared on the dentin surfaces of extracted human permanent first and second molars ground on 600 grit SiC paper with each system. The bonded cylinders were removed from the assembly apparatus 15 minutes after cure, stored in physiological saline at 37 degrees C for 24 hours and subjected to a shear load at 0.5 mm/min. Five cylindrical specimens were prepared for each system, the discs were suspended in 25 microL glass distilled water and the fluoride release (microgram F/mm2) determined at daily intervals for 15 days and then after 30 and 90 days. The data were analyzed by a one-way analysis of variance and Duncan's multiple range test. The following shear bond strengths (Mean +/- SD) were recorded (MPa): A: 8.86 +/- 1.49; B: 4.24 +/- 1.23; C: 4.41 +/- 1.39; D: 3.85 +/- 1.60; E: 4.81 +/- 1.21. With all the systems, the fluoride release dropped sharply during the first 7 days and then remained constant. The shear bond strength and the fluoride release from Vitrabond/Silux were significantly greater than that of the other systems.

Acrylic Resins↗
PubMed1990

Shear bond strengths of the tenure dentin bonding systems.

A third generation dentinal bonding system, Tenure Solution dentin bonding system, has recently become commercially available. The original system has been modified twice. The objectives of this in vitro study were to determine the shear bond strengths of the three systems to dentin 15 minutes after specimen preparation, after 24 hours storage in physiological saline at 37 degrees C with and without temperature cycling, and after 4 weeks storage with and without temperature cycling. The shear bond strengths decreased with duration of storage but of each storage interval temperature cycling had no adverse effect on shear bond strength.

Benzoates↗
PubMed1990

Extracted human versus bovine teeth in laboratory studies.

The purpose of this study was to determine the shear bond strengths and microleakage of Scotchbond 2/Silux to dentin and to evaluate resin penetration into the dentinal tubules of human and bovine teeth. The shear bond strengths (SBS) were determined on occlusal dentin of 25 human permanent molars (H) and on facial dentin of 25 bovine permanent mandibular incisors (B). The test specimens were stored in physiological saline at 37 degrees C for 24 hours prior to the application of a shear load in an Instron machine at a speed of 0.5 mm/min. Microleakage (ML) of Class V restorations placed on the facial surfaces of the roots of 15 human canines (H) and 15 bovine incisors (B) was determined quantitatively. The restored teeth were thermocycled x500 in 2% methylene blue solution, the dye extracted in 50% HNO3 and the dye concentrations determined spectrophotometrically. The resin penetration into the dentinal tubules was evaluated in the SEM. The following results were obtained: SBS (MPa): H, 6.2 +/- 2.9; B, 4.4 +/- 1.2; ML (microgram dye): H, 4.7 +/- 3.2; B, 15.9 +/- 10.5. The data were analyzed by t-test. The shear bond strength of Scotchbond 2/Silux to human dentin was significantly greater (P = 0.0096) and the microleakage significantly less (P = 0.0004) than to bovine dentin despite the fact that the restorative system penetrated more densely into bovine dentin. The use of bovine teeth instead of human teeth in these types of tests is not indicated.

Age Factors↗
PubMed1990

Laboratory study of the Herculite XR system.

The shear bond strengths of the Herculite XR system to dentin were determined the quantitative microleakage of Class V restorations in dentin evaluated; the fluoride release from the XR-Ionomer determined, and fractured test specimens depicting various failure patterns examined in the scanning electron microscope. The shear bond strength of the XR-Ionomer to dentin was 6.6 +/- 1.7 MPa and the Herculite XR 15.4 +/- 3.7 MPa. Sixteen of the 20 Herculite XR test specimens fractured in dentin. The quantitative microleakage of Class V Herculite XR restorations in dentin was 2.22 +/- 1.94 micrograms dye which was significantly reduced to 0.91 +/- 0.63 micrograms when the XR-Ionomer was placed in the floors of the preparations. The fluoride release from the XR-Ionomer dropped sharply during the first 6 days after which it reached a plateau at approximately 0.5 microgramsF.mm-2.

Composite Resins↗
PubMed1990

Marginal leakage and marginal gap dimensions of three dentinal bonding systems.

Standardized cylindrical Class V preparations, 3 mm in diameter and 1.5 mm deep, were made on the roots of 60 extracted human maxillary permanent canines. The teeth were restored with Scotchbond 2/Silux (S); Gluma/Lumifor (G); and Tenure/Perfection (T), respectively. The root apices were sealed with Copalite/amalgam and two coats of nail varnish applied to the teeth except for 1 mm around the restorations. For the qualitative microleakage evaluation the teeth were thermocycled x500 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C and for the quantitative microleakage evaluation in 2% methylene blue solution. The marginal gap dimensions were measured on cylindrical restorations placed on the facial surfaces of ground root surfaces of 30 teeth. Epoxy replicas were made of the restorations, coated with gold/palladium and examined with the SEM. The maximum marginal gap dimensions were measured. The data were analyzed by ANOVA, Duncan's and their nonparametric analogues. In the qualitative microleakage evaluation the total microleakage was: S: 16; G: 50; T: 18. The quantitative microleakage (micrograms) was: S: 3.1 +/- 2.9; G: 16.1 +/- 5.3; T: 4.4 +/- 4.1. The maximum marginal gap dimensions (microns) were: S: 4.1 +/- 3.6; G: 9.3 +/- 3.4; T: 16.4 +/- 7.0.

Analysis of Variance↗
PubMed1988

Performance of a hydroxypropyl cellulose film former in normal and ulcerated oral mucosa.

Although oral ulcers are commonly encountered in clinical dental and medical practice, current therapeutic options with respect to pain relief are limited. This study evaluated the mucosal binding characteristics and the pain relief and protection properties of Zilactin, a hydroxypropyl cellulose film former. In 12 healthy volunteers, the mean duration of mucosal adherence of Zilactin was 3.92 hours, which was significantly longer than that of a widely available topical preparation (1.38 hours, p = 0.0001). When evaluated in 20 subjects with recurrent aphthous ulcerations, Zilactin demonstrated the ability to significantly decrease ulcer pain over a 4-hour period when compared with the subjects' individual standardized level of initial discomfort, which was used as an internal control for all subsequent steps. Challenge with an irritating citrus beverage was made before and after application of the medication. A significant difference in premedication and postmedication sensitivity was shown (p = 0.0001), indicating that the film provides protection, as well as pain relief. As a result of its unique and tenacious film-forming characteristics, this agent is exceptionally effective in the treatment of oral mucosal ulcerations. Greater awareness on the part of physicians and dentists may lead to the development of additional applications.

Adhesiveness↗