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At least 667 records · Page 37Linked to original sources
PubMed1989

Relative microhardness of glass ionomer restorative materials as an indicator of finishing time.

Microhardness was evaluated as an indicator of appropriate finishing intervals for glass ionomer restorative materials. The hardness of several materials was determined after the first hour of mixing. A material clinically documented to be satisfactorily finished after a delay of 15 minutes attained 29% of its 24-hour hardness during that interval. Samples of the other materials finished on reaching this relative hardness, which differed from the manufacturers' suggested finishing delays, showed no differences in surface characteristics, appearance, or surface roughness compared with specimens finished at the recommended times.

Aluminum Silicates↗
PubMedDate not supplied

Brushing abrasion of luting cements under neutral and acidic conditions.

Four resin based materials (Compolute Aplicap, ESPE; Variolink Ultra, Vivadent; C&B Metabond, Parkell and Panavia 21, Kuraray), two carboxylate cements (Poly-F Plus, Dentsply DeTrey and Durelon Maxicap, ESPE), two glass-ionomer cements (Fuji I, GC and Ketac-Cem Aplicap, ESPE), one resin-modified glass ionomer cement (Vitremer, 3M) one polyacid-modified resin composite (Dyract Cem, Dentsply DeTrey) and one zinc phosphate cement (Harvard, Richter & Hoffmann) were investigated according to their brushing resistance after storage in neutral and acidic buffer solutions. For this purpose 24 cylindrical acrylic molds were each filled with the materials. After hardening, the samples were stored for seven days in 100% relative humidity and at 37 degrees C. Subsequently, they were ground flat and polished. Then each specimen was covered with an adhesive tape leaving a 4 mm wide window on the cement surface. Twelve samples of each material were stored for 24 hours in a buffer solution with a pH of 6.8. The remaining 12 samples were placed in a buffer with a pH of 3.0. All specimens were then subjected to a three media brushing abrasion (2,000 strokes) in an automatic brushing machine. Storage and brushing were performed three times. After 6,000 brushing strokes per specimen, the tape was removed. Brushing abrasion was measured with a computerized laser profilometer and statistically analyzed with ANOVA and Tukey's Standardized Range Test (p < or = 0.05). The highest brushing abrasion was found for the two carboxylate cements. The lowest brushing abrasion was found for one resin based material, Compolute Aplicap. With the exception of three resin-based materials, a lower pH led to a higher brushing abrasion.

Analysis of Variance↗
PubMed2002

Two-year clinical and SEM evaluation of glass-fiber-reinforced inlay fixed partial dentures.

PURPOSE: To clinically evaluate conservative fiber-reinforced composite inlay fixed partial dentures (IFPDs) bonded to inlay abutments. MATERIALS AND METHODS: Forty fiber-reinforced composite IFPDs were made for 29 patients. Restorations were manufactured with the composite Targis reinforced by Vectris prefabricated glass-fiber elements and were inserted with a high viscosity insertion technique. Forty bonded IFPDs were examined clinically after 1 year, and 25 after 2 years, using modified USPHS criteria. Twenty-five abutment inlays and 12 pontics were analyzed quantitatively by scanning electron microscopy SEM. Results were tested for statistical significance with ANOVA. RESULTS: Although most clinical criteria were rated "alpha", four IFPDs had to be replaced: two retainers debonded and two presented total delamination of veneering material from fiber framework. Two partial delaminations were repaired intraorally. No fractures of framework were observed. SEM marginal analysis of tooth-composite interface exhibited 96.5 +/- 3.0% continuous margin at baseline, 91.0 +/- 5.7% at the 1-year and 89.6 +/- 5.2% at the 2-year recall. Decrease of marginal quality was statistically significant between baseline and 1 year (P= 0.001), but not between 1- and 2-year recalls.

Acrylates↗
PubMed2004

Effect of hydrofluoric acid on repair bond strength of a laboratory composite.

PURPOSE: To evaluate the repair bond strength of a laboratory processed composite treated with hydrofluoric acid gels of different acid concentrations and for various etching times and repaired with a flowable composite. METHODS: 75 specimens of a laboratory composite (Targis) were prepared in a split metal mold and stored for 24 hours in an incubator at 37 degrees C and 100% relative humidity. The laboratory composite surfaces were then etched for 5, 10, 15, 30, and 60 seconds using three hydrofluoric acid concentrations (5%, 8%, and 9.5%). The repair composite (Tetric Flow) was light-cured in two increments for 40 seconds each in an inverted, truncated cone mold. Storage conditions of specimens before debonding were 24 hours at 37 degrees C and 100% relative humidity. Tensile bond strengths were determined using a testing machine at a crosshead speed of 0.5 mm/minute. A two-way ANOVA was used to determine significant differences. Failure sites were classified. The morphological aspects of the etched composite surfaces were evaluated qualitatively by scanning electron microscopy. RESULTS: There were no differences in the repair bond strengths with respect to the three different acid concentrations or the five etching times tested. The minimum etching time to observe an etched pattern was at 60 seconds with the highest concentration of hydrofluoric acid (9.5%).

Acid Etching, Dental↗
PubMed2003

Resin-modified glass ionomer cement and self-cured resin composite luted ceramic inlays. A 5-year clinical evaluation.

OBJECTIVE: This study evaluated IPS Empress ceramic inlays luted with two chemical-cured luting agents, a resin-modified glass ionomer cement (Fuji Plus (F)) and a resin composite (RC) (Panavia 21 (P)). METHODS: Seventy-nine ceramic inlays were placed in Class II cavities in 29 patients. At least two inlays were placed in each patient to compare the luting techniques intra-individually. In each patient half of the inlays were luted with F and the other half with P. The inlays were evaluated clinically, according to modified USPHS criteria (van Dijken, 1986), at baseline, after 6 months, and yearly during 5 years. RESULTS: At 5 years, 71 inlays were evaluated. Two small partial fractures were observed at 3 years (1P, 1F). One inlay showed recurrent root caries at 4 years (P). Four inlays, two in each group showed non-acceptable color match (2P, 2F). Small defects were observed in 4 inlays (2P, 2F). A slight ditching of the cement margins was observed in both luting groups but did not seem to increase during the second half of the evaluation. No significant difference in durability was observed between the two luting agents. SIGNIFICANCE: IPS Empress inlays luted with the chemical-cured RC and the resin-modified glass ionomer cement functioned satisfactory during the 5 years follow-up.

Adult↗
PubMed2002

Maxillary and mandibular overlay removable partial dentures for the treatment of posterior open-occlusal relationship: a clinical report.

This clinical report describes the use of maxillary and mandibular overlay removable partial dentures to treat a patient with class III skeletal malocclusion and a posterior open-occlusal relationship. Overlay removable partial denture therapy was used as an alternative to other options such as orthodontics and combined orthodontic/oral surgery procedures; it satisfied the esthetic and functional requirements of the patient and provided a stable occlusion. Overlay removable partial dentures are a reversible and relatively inexpensive treatment for patients with congenital or acquired anomalies, but the potential disadvantages of these prostheses include compromised esthetics when the dentures are removed; caries and periodontal disease as a result of poor oral hygiene; and veneer material fracture, debonding, discoloration, and wear.

Chromium Alloys↗
PubMedDate not supplied

Bonding indirect resin composites to metal: part 2. Effect of alloy surface treatment on elemental composition of alloy and bond strength.

PURPOSE: This laboratory study compared the effect of different surface treatments of a medium-gold, high-noble alloy on the shear bond strength of an indirect, highly filled resin composite to the alloy and on the elemental composition of the alloy surface. MATERIALS AND METHODS: Ninety disks, cast in a medium-gold, high-noble porcelain-fused-to-metal alloy (V-Deltaloy), received three different surface treatments: sandblasting with 50-microm Al2O3 (group 1) or 250-microm Al2O3 (group 2) and chemical agents, or with 250-microm Al2O3 without chemical agents (group 3) prior to bonding of an indirect resin composite (Artglass, and chemical agents Siloc-pre and Siloc-bond). The specimens were tested in shear, half of them after 24-hour dry storage at room temperature and the rest after 10-day storage in normal saline solution at 37 degrees C and thermocycling (2,500 cycles between 5 and 55 degrees C). Morphologic and qualitative changes on the alloy surface after sandblasting with 50- or 250-microm Al2O3 were examined by SEM using EDS analysis and compared with polished specimens. Statistical analysis was performed using two-factor ANOVA. RESULTS: The mean shear bond strengths (in MPa) after dry or wet storage and thermocycling were 29 and 24 for group 1, 21 and 18 for group 2, and 17 and 12 for group 3, respectively; there was a statistically significant difference among the groups. Sandblasting of the alloy surface led to statistically significant changes in elemental composition. These changes were of greater magnitude when 50-microm Al2O3 particles were used. CONCLUSION: The particle size used for sandblasting influences the shear bond strength between a high-noble alloy and a highly filled indirect resin composite, as well as the elemental composition of the alloy surface.

Aluminum Oxide↗
PubMed1996

A clinical trial of all-ceramic crown restorations: status, fall 1995.

Although porcelain-fused-to-metal (PFM) restorations are the most widely used full-coverage crown restoration systems, their inherent properties make the achievement of natural aesthetic restorations an elusive task. In contrast, the all-ceramic system (IPS Empress, Ivoclar North America, Amherst, NY) offers excellent translucency and vitality, without the opacity associated with PFM restorations. Its vitality is further enhanced by an adhesive resin cementation method that conducts the color of the underlying tooth structure. This article reports the status of a 5-year investigation, initiated in 1992, of the clinical performance of the IPS Empress all-ceramic system and the resin cementation system used with it.

Adolescent↗