Biomedical subjects

B K Moore

Publications and source records attributed to B K Moore.

121 records · Page 7Linked to original sources

PubMedDate not supplied

Efficacy testing of visible-light-curing units.

This study evaluated (1) the effect of known reductions in the output of curing lights on the depth of cure of various resins as determined by hardness measurements, and (2) the ability of the clinician to detect reduced light output by use of an explorer to compare the hardness of the top and bottom surfaces of resin specimens. Curing light output was reduced stepwise from 10 to 70% with neutral density filters. Hardness values indicated polymerization of the top surface to be generally unaffected by light blockage. Bottom surfaces were greatly affected: more with a 30-second than a 60-second cure time. Three clinicians utilized an explorer to compare the tops and bottoms of specimens of known hardness. Evaluators were unable to routinely detect differences of less than 20 to 30 Barcol numbers. The data indicate that a light meter is a more efficacious means of monitoring curing light performance than is a tactile test of resin surface hardness.

Composite Resins↗

PubMedDate not supplied

Properties related to strength and resistance to abrasion of VariGlass VLC, Fuji II L.C., Ketac-Silver, and Z-100 composite resin.

The purpose of this study was to evaluate the properties related to the strength and resistance to abrasion of new Type II lightcured glass ionomers, VariGlass VLC, and Fuji L.C., and to compare the results with Ketac-Silver and Z-100 composite resin. Each material was tested for strength with an Instron Universal Testing Machine and for resistance to abrasion with a motor-driven machine. The strengths of Z-100 were the highest. Among glass ionomers, Ketac-Silver had higher compressive strength, but lower diametral tensile and transverse strengths than the others; and Fuji II L.C. had higher strengths than VariGlass VLC. VariGlass VLC showed the greatest resistance to abrasion, followed respectively by Z-100, Fuji II L.C. and Ketac-Silver. ANOVA indicated significant differences in strengths and abrasion resistance, except, the volume losses of Fuji II L.C. and Ketac-Silver in the toothbrushing test were not significantly different (p < 0.01). The results support VariGlass VLC and Fuji II L.C. as alternative filling materials in Class III and V situations, but they are not recommended for stress-bearing restorations.

Acrylic Resins↗

PubMedDate not supplied

Effect of die material hue and value on polymerization of indirect resin inlays.

This study investigated the effects of hue and value of mold materials on the polymerization of resin composite inlays fabricated by an indirect process. Three colors of molds were used, and 10 specimens each of three resin composite materials were light polymerized on each of the die materials for each test. The specimens were postirradiation heat polymerized. Compressive strength, flexural strength, Knoop hardness, and bond strength to enamel and dentin were measured. Although differences in properties between specimens polymerized on different die materials were not always significant, the values obtained from the white mold were highest in all tests followed by those obtained on the gray and then the black molds. Correlations (r2) between lightness or value and compressive and flexural strength, hardness, and bond to enamel and dentin values were greater than 0.90. Die color and value appear to be important factors influencing the properties of indirect resin composite inlays even though they are heat polymerized after light activation.

Analysis of Variance↗

PubMedDate not supplied

An in vitro shear bond strength study of enamel/dentin bonding systems on enamel.

The purpose of this study was to compare the enamel shear bond strengths achieved with four acid conditioners employed by current enamel/dentin bonding systems (maleic acid, citric acid, nitric acid, oxalic acid) with a 37% phosphoric acid etching technique. The study also compared enamel shear bond strengths between the manufacturers' enamel/dentin conditioner used with an unfilled enamel bonding resin. The facial surfaces of 135 bovine incisors were ground flat and divided into nine test groups of n=15. Conditioning and bonding procedures were carried out following manufacturers' instructions. The phosphoric acid groups were etched for 15 seconds, rinsed for 30 seconds, and dried for 20 seconds with compressed air. All bonding was accomplished at a constant temperature of 21 degrees C and a relative humidity of 60%. A single composite restorative resin (Z-100) was used with all specimens to eliminate variables between composite materials. All specimens were thermocycled 2500 times (5 to 45 degrees C) and had a total storage time of 21 days prior to shear testing on an Instron at a crosshead speed of 1.0 mm/minute. Shear strengths were calculated by dividing load at failure by specimen area. A light microscope was used to determine failure mode. The data were subjected to Bartlett's test for homogeneity of variance and were found not to be homogeneous. The Welch Test was applied and indicated that the treatments used had influence on bond strength at P<0.05. There was no significant difference in bond strength values between traditional phosphoric acid/enamel bonding resin and Mirage Bond Dentin and Enamel Adhesive, Clearfil Liner Bond System, and Scotchbond Multi-Purpose Dental Adhesive System.

Acid Etching, Dental↗

PubMedDate not supplied

Influence of dentin primer application methods on dentin bond strength.

This study was carried out to determine the influence of dentin primer application methods on bond strength to human dentin. Two dentin bonding restorative systems, Imperva Bond/Lite-Fil II A (Shofu) and Scotchbond Multi-Purpose/Z-100 (3M) were employed. Human molars were mounted in self-cured resin and the buccal surfaces were prepared with #600-grit SiC paper. These surfaces were then conditioned according to each manufacturer's instructions. Two experiments were designed: (1) effect of the primer application procedures (inactive and active application), and (2) effect of the air drying time (0, 1, 5, 10, 20, and 30 seconds). The adhesives were applied and resin composites were bonded to the teeth. Ten samples per test group were stored in 37 degrees C deionized water for 24 hours, and shear tested with a circular knife edge at a crosshead speed of 1.0 mm/minute. A one-way ANOVA followed by the Newman-Keuls multiple comparison at P < 0.05 was done. For both restorative systems, the bond strengths for active application were higher than those for inactive application, but there was no significant difference between the two mean values. According to the air drying time, there appeared to be an optimal range of drying times, longer for Imperva Bond (10-30 seconds) than for Scotchbond MP (1-5 seconds). The data suggest that the bond strengths of employed dentin bonding systems were greatly influenced by the methods of the dentin primer application.

Air↗

PubMedDate not supplied

Influence of bonded amalgam restorations on the fracture strength of teeth.

This study evaluated the effect of bonded amalgam on the fracture strength of teeth using five adhesive systems: Panavia 21, Amalgambond Plus, Imperva Dual Bond, All-Bond 2 Primer/Bonding Resin, and All-Bond 2 Primer/Liner F. Intact teeth and amalgam lined with Copalite were used as control groups. Large MOD preparations were made in 20 extracted maxillary premolars for each group. The teeth were restored with Tytin. All groups were stored in water at 37 degrees C for 15 days and thermocycled 2500 times, over 8-48 degrees C. The specimens were preloaded five times in compression to 10 kg using a 5 mm-in-diameter, cylindrical steel indenter that contacted the teeth only on the cuspal inclines. Then the teeth were loaded to failure at 5.0 mm/min. The failure mode was recorded (amalgam failure, cusp fracture, or failure at the tooth/amalgam interface). The mean fracture strengths were analyzed using ANOVA and Newman-Keuls multiple comparisons. The Imperva Dual Bond group showed the highest mean forces followed by All-Bond 2 Primer/Bonding Resin. The All-Bond 2 Primer/Liner F and Amalgambond Plus groups demonstrated lower means and were not significantly different from the Copalite group. The Panavia 21 group was in between these two groups and was not statistically different from either group. The mean strength of intact teeth was the highest, but its very large coefficient of variation (60%) prevented effective use of these data for statistical comparison. Analysis of the mode of fracture showed that Panavia 21, All-Bond 2 Primer/Bonding Resin, and Amalgambond Plus failed cohesively in the amalgam in 35%, 25%, and 15% of the specimens respectively. This fracture type is a good indication of effective bonding between tooth and amalgam. The most common type of fracture for all the restored groups was the one that occurred at the tooth/restoration interface. This would suggest that current bonding procedures could be improved.

Analysis of Variance↗

PubMedDate not supplied

Comparison of retentiveness of amalgam bonding agent types.

Previous studies on amalgam bonded restorations indicated that amalgam bonding agents increased the bond strength of amalgam to tooth structure. This in vitro study was designed to compare how the mode of curing and the presence of filler in the resin would affect the bond strength of amalgam. The five test groups of lining agents for amalgam restorations included Chemical-cured, Unfilled resin (CU-Clearfil New Bond); Light-cured, Unfilled resin with a delayed chemical-cure property (LU*-Clearfil Photo Bond); Light-cured, Filled resin with a delayed chemical-cure property (LF*-Clearfil Photo Bond + Protect Liner); Dual-cured, Unfilled resin (DU-All-Bond 2); and Varnish (V-Copalite). For each group, 20 class 5 cavity preparations were cut on the facial, lingual, or proximal surfaces of human molars, which were embedded in acrylic resin. The preparations were 2.5 mm deep and 3 mm wide at the pulpal floor with a slightly divergent taper. After treating the preparation with the bonding agent, a 3/4-inch, 18-gauge flat-headed wire nail was placed into the cavity with the head at the pulpal floor of the preparation, and Tytin amalgam was then condensed into the preparation around the nail. The restorations were stored for 24 hours in distilled water at 37 degrees C and then subjected to 2500 thermal cycles (8 degrees C to 48 degrees C). After 1 week, specimens were tested to failure in tension using an Instron Universal Testing Machine (crosshead speed = 2 mm/min) and peak load (kg) was recorded. The mean loads at failure (+/- SD) were LF* 26.4 (+/- 7.0), DU 23.9 (+/- 6.4), LU* 16.0 (+/- 3.1), CU 14.3 (+/- 8.0), and V 9.5 (+/- 5.6). Significant differences were found using a one-way ANOVA and the Games and Howell post hoc test at a significance level of alpha = 0.05. The LF* and DU groups were not significantly different from each other, but they were significantly higher in peak load than all other groups. LU* was significantly higher than the varnish (V) but not significantly higher than CU. CU was not significantly higher than the varnish (V). The adhesives forming a thicker resin interface (the light-cured resin with filled resin liner and the dual-cured unfilled resin) demonstrated significantly greater retention than the light-cured unfilled resin, chemical-cured unfilled resin, and the varnish control.

Adhesiveness↗

PubMedDate not supplied

In vitro corrosion behavior and microstructure examination of a gallium-based restorative.

Concerns of mercury toxicity have led to the development of gallium-based restorative materials to replace dental amalgam. A new gallium-based dental restorative, Galloy, was compared with a high-copper amalgam, Permite, for anodic polarization behavior in deoxygenated Ringer's solution and by immersion testing in normal Ringer's solution at 37 degrees C. Corrosion products were analyzed using energy dispersive X-ray spectrometry and transmission electron diffraction. The data from both sources were consistent with the presence of alpha-Ga2O3 and SnO2 as the primary corrosion products of Galloy. Anodic polarization behavior of Galloy- and Permite-coupled specimens suggests that coupling Galloy with the more noble Permite amalgam may cause accelerated electrochemical corrosion and that Galloy is more corrosion prone than Permite.

Corrosion↗

PubMedDate not supplied

Wear resistance of four luting agents as a function of marginal gap distance, cement type, and restorative material.

This study investigated the effect of marginal gap width, luting cement, and restorative material on the wear resistance of the luting cement in areas where no occlusal contact is present. Three types of resin luting cement and one resin-modified glass-ionomer cement were used with two inlay systems, a resin composite, and an all-ceramic system. Bovine enamel represented tooth structure. Toothbrush abrasion was the wear modality. Three predetermined gap widths were selected: 240 +/- 30 microns, 150 +/- 30 microns, and 60 +/- 30 microns. All specimens were thermocycled. Regardless of the luting cement or the restorative material, there was a significant difference (P < 0.05) in wear resistance of the cement among the three gap distances at both the enamel and restoration interface. Vertical wear of the luting cement at the enamel interface increased linearly with marginal gap distance when all four cements were considered together (r2 > 0.51), regardless of type of restorative material used. The resin-modified glass-ionomer cement showed the least amount of wear for all variables considered. Significant differences in wear were found between the four luting cements at wide gap distances (240 microns) at the enamel interface, regardless of type of restorative material used. No significant differences were found between the two restorative materials at the enamel interface at the three gap distances.

Animals↗

PubMedDate not supplied

A comparison of a hybrid light-cured glass-ionomer base and liner vs. a light-cured resin tooth fragment attachment.

PURPOSE: The purpose of this study was to compare the dislodgement strengths and fracture types for reattached tooth fragments using a light-cured composite resin material, a hybrid light-cured glass ionomer base, and a hybrid light-cured glass ionomer liner. METHODS: Seventy-five bovine incisor teeth were fractured, randomly divided into three groups of equal number, and then luted back together with three different materials (Universal Bonding Agent/TPH Composite Resin; VariGlass VLC Base; and VariGlass VLC Liner: LD Caulk Div Dentsply Int Inc, Milford, DE). The reattached fragments were subjected to thermocycling with a 40 degrees C differential and then were loaded until the force required to dislodge the fragment was reached. RESULTS: The mean dislodgement strengths were 36.8 (+/- 25.6) kg for the composite resin, 36.4 (+/- 26.7) kg for the glass ionomer base, and 31.4 (+/- 29.5) kg for the glass ionomer liner. Cohesive fractures occurred in 73% of the dislodgements. CONCLUSIONS: There was no statistically significant difference demonstrated (P < 0.05) between the three groups in terms of both dislodgement strength and fracture type.

Acrylic Resins↗

PubMedDate not supplied

Evaluation of curing units used in private dental offices.

It is well known that numerous factors influence the light output of curing units, but many dentists are unaware that the output of their curing lights are inadequate. This study was conducted to evaluate the light intensity of visible-light curing units in private dental offices and to assess their curing efficiency by measuring compressive strength of a light-cured resin. Also, in order to determine the maximum light intensity of the curing units, lamps, filters, and fiber optic bundles were replaced by new ones and curing efficiency remeasured. Light intensity was measured by employing a Quantum Radiometer LI-189 at a wavelength of 470 +/- 40 nm using a bandpass filter. Compressive strength of a light-cured resin using the light units was measured employing an Instron Testing Machine at a crosshead speed of 1.0 mm/min. From the evaluation of 105 light units, the light intensity ranged from 28 to 1368 W/m2 (0 approximately 500 W/m2; 41.9%, 500 approximately 1000 W/ m2; 45.7%, 1000 approximately 1500 W/m2; 12.4%). Light intensity of the light unit in private offices decreased 15.9 approximately 82.1% compared to brand-new units. Reduction of light intensity impaired compressive strength of the light-cured resin to varying degrees (148.3 approximately 279.9 MPa) compared with the highest value (317 MPa) obtained from brand-new light units. The replacement of the parts increased the light intensity, with maximum increases of 36.0% for lamps, 157.7% for filters, 46.2% for fiber optics, and 322.7% for all three parts. The results of this study indicated that the light intensities of the curing units used in private practice were lower than expected.

Composite Resins↗

PubMedDate not supplied

The effect of air abrasion on shear bond strength to dentin with dental adhesives.

This study compared the effects of different dentin surface treatments on the shear bond strengths of three adhesive systems. The adhesive systems included a resin-modified glass ionomer, Fuji II LC, and two dentin bonding systems, One Step and Scotchbond Multi-Purpose Plus. The surface treatments compared for each adhesive system were as follows: 1) the controls, which were conditioned, 2) air abrasion at 120 psi without conditioning, 3) air abrasion at 160 psi without conditioning, 4) air abrasion at 120 psi with conditioning, and 5) air abrasion at 160 psi with conditioning. The KCP 1000 Whisperjet was used for all air-abrasive specimens. Controls for each adhesive material (Fuji II LC, One Step, Scotchbond Multi-Purpose Plus) were bonded using manufacturers' recommendations. Results showed that air abrasion significantly lowered bond strength of the resin-modified glass ionomer, conditioned or nonconditioned (P < 0.01). Air abrasion alone significantly lowered bond strengths of the dentin bonding agent systems (P < 0.01). However, air abrasion plus conditioning of the dentin surface resulted in bond strengths that were similar to the conditioned-only specimens (P < 0.01).

Air Pressure↗

PubMedDate not supplied

Resin-modified glass ionomers: dentin bond strength versus time.

Most dentin bond strength tests of resin-modified glass-ionomer cements have been conducted after at least 24 hours' storage in water. In a clinical situation, debonding might occur soon after the restoration was placed if subjected to stress. The purpose of this study was to investigate the rate of development of shear bond strength of resin-modified glass-ionomer cements, two Type IIs of which, Fuji II LC and Vitremer, were used. A conventional glass-ionomer cement, Fuji II, and a resin composite, Herculite XRV/OptiBond system, were also employed as controls. Bovine incisors were mounted in self-curing resin, and the facial surfaces wet ground with 600-grit SiC paper to expose dentin. Materials were condensed into a vinyl mold and bonded following the manufacturers' instructions. The shear bond strengths of 10 specimens per group were measured at a crosshead speed of 1.0 mm/minute after 1, 5, 10, 30, and 60 minutes' and 2, 5, and 24 hours' storage in water at 37 degrees C. One-way ANOVAs followed by the Dunnet test (P < 0.05) were used to test for significant differences between the mean bond strength at 1 minute and each of the other test periods. The test period when there was a significant increase in bond strength was defined as the "initial increasing time." The dentin bond strengths of all the materials tested increased with prolonged storage time. The initial increasing times were 10 minutes for Fuji II LC and OptiBond, 20 minutes for Fuji II, and 60 minutes for Vitremer. The differences in the initial increasing time might have clinical implications if the restoration is subjected to significant stress immediately after placement.

Analysis of Variance↗