Biomedical subjects

Erica C N Teixeira

Publications and source records attributed to Erica C N Teixeira.

6 recordsLinked to original sources

PubMed2006

An in vitro assessment of prefabricated fiber post systems.

BACKGROUND: The authors conducted a study to characterize the in vitro retention, fracture and light transmission behavior of four different fiber-reinforced resin-based composite root canal posts. METHODS: The authors divided 44 teeth into four groups according to the type of post they would receive: parallel fiberglass posts, double-tapered fiber quartz posts, tapered fiberglass posts and two different types of parallel fiberglass posts. They prepared teeth and cemented posts with dual-cured resin cement. After the specimens aged, the authors conducted pull-out tests. For fracture testing, they loaded posts at 45 degrees in a universal testing machine. They determined load-to-fracture values and relative stiffness. They measured percentage of light transmission by means of a light microscope coupled with a spectrometer. RESULTS: Both tapered posts showed lower retention than did the parallel posts. Scanning electron microscropic analysis indicated that more cement adhered to the surfaces of the parallel fiberglass post than to those of the tapered fiberglass post. All posts demonstrated some plastic behavior, with the double-tapered fiber quartz post being stiffer than the others. CONCLUSION: Parallel fiber-reinforced composite posts showed better retention than did tapered posts when a dual-cured resin-based cement was used. Translucent prefabricated posts have limited light transmission. CLINICAL IMPLICATIONS: Parallel prefabricated fiber posts luted with dual-cured resin-based cement seem to be suitable for clinical application in endodontically treated teeth that require post-and-core restoration, showing good retention and acceptable fracture resistance.

Analysis of Variance↗

PubMed2005

In vitro toothbrush-dentifrice abrasion of two restorative composites.

BACKGROUND: Surface wear can be a problem with directly placed composites. PURPOSE: This study evaluated the in vitro wear and surface roughness of two composites at different cycle intervals after being subjected to toothbrush-dentifrice abrasion. MATERIALS AND METHODS: Twenty specimens of a microhybrid, Filtek Z250 (3M ESPE, St. Paul, MN, USA), and a nanofill composite, Filtek Supreme (3M ESPE), were prepared according to the manufacturer's directions. Each specimen was subjected to toothbrush-dentifrice abrasion (250 g vertical load) using a deionized water-dentifrice slurry (Close-Up, Lever Ponds Ltd., La Lucia, ZA) and toothbrush heads (Oral-B 40, Oral-B Laboratories, Delmont, CA, USA). A brushing sequence of 10,000, 20,000, 50,000, and 100,000 strokes was performed for all samples at a rate of 1.5 Hz. At baseline and each cycle interval, a surface profilometer was used to determine average surface roughness, Ra. At the same intervals, vertical loss of material was measured with a precision micrometer. Data were analyzed using repeated-measures analysis of variance at p value .05. Analyses with atomic force microscopy (AFM) and scanning electron microscopy (SEM) were also performed. RESULTS: After 20,000, 50,000, and 100,000 cycles, Filtek Supreme showed less significant wear than Z250. Filtek Supreme demonstrated higher surface roughness than Z250 after 50,000 and 100,000 cycles. However, AFM and SEM images indicated a more uniform surface topography for Filtek Supreme than for Z250. Abrasion wear and surface roughness increased with each cycle interval for both materials. CONCLUSIONS: Although the initial performance of both materials was similar, a greater number of brushing cycles revealed differences between the wear resistance and generated surface roughness of the materials. CLINICAL SIGNIFICANCE: The wear resistance and roughness results of Filtek Supreme suggest that it is suitable for clinical use, mainly in areas that are more subject to abrasive wear, such as Class V restorations.

Acrylic Resins↗

PubMed2005

Effect on enamel microhardness of two consumer-available bleaching solutions when compared with a dentist-prescribed, home-applied bleaching solution and a control.

BACKGROUND: There exists limited data in the literature regarding the efficacy and safety of consumer-available, paint-on bleaching solutions. PURPOSE: The purpose of this in vitro study was to evaluate the effect of two consumer-available, paint-on bleaching products on enamel microhardness against a control and a dentist-prescribed, home-applied (DPHA) bleaching product. MATERIALS AND METHODS: Eighty enamel slabs were obtained from extracted human teeth and randomly divided into four treatment groups: (1) control; (2) Opalescence (Ultradent Products, Inc., South Jordan, UT, USA); (3) Crest Night Effects (Procter & Gamble, Cincinnati, OH, USA); and (4) Colgate Simply White Night (Colgate-Palmolive Co., Piscataway, NJ, USA). Opalescence is a carbamide peroxide DPHA product, whereas Crest Night Effects and Colgate Simply White Night are consumer-available products. The specimens in groups 2 to 4 underwent 2 weeks of treatment for 8 h/d. Specimens were maintained in artificial saliva at 37 degrees C between treatments. Subsequently, one-half of the specimens in groups 2 to 4 (n=10) underwent an additional seven treatments for 8 h/d, while the other half were stored in artificial saliva, receiving no further treatment. Microhardness was measured as Knoop hardness numbers (KHNs) at baseline and after 1, 7, 14, and 21 treatment days. The results were analyzed for statistical significance both intra- and intergroups using analysis of variance (p=.05). RESULTS: A statistically significant reduction in mean KHN was observed compared with baseline at 1, 7, 14, and 21 treatment days for group 4 and at 7 treatment days for group 3. When compared with the control or DPHA product, group 4 was the only treatment that resulted in significantly lower mean KHNs at 7, 14, and 21 treatment days. CONCLUSION: When evaluating enamel microhardness, consumer available, paint-on bleaching solutions may adversely affect enamel microhardness compared to a control and 10% carbamide peroxide DPHA bleaching solution. CLINICAL SIGNIFICANCE: With numerous consumer-available bleaching products on the market, it is crucial to be judicious in their selection and use. The results of this in vitro study showed that the consumer-available, paint-on bleaching solutions adversely affected enamel microhardness at some time during the study. Consumers should be made aware of this effect on enamel.

Carbamide Peroxide↗

PubMed2004

Dentinal bonding reaches the root canal system.

Several factors can contribute to the achievement of success with endodontic therapy. After an effective microbial-control phase, an adequate canal and coronal filling will guarantee a high probability of success. Gutta-percha has for many years been widely used as a solid material in root fillings associated with different types of sealers. Even associated with a sealer, this material it is not capable of preventing leakage, as has been shown in many studies. In fact, because of gutta-percha's limitations, the seal of a coronal restoration may be as important as the gutta-percha fill in preventing reinfection of the root canal. Although sealers can form close adhesion to the root canal wall, none is able to bond to the gutta-percha core material. Upon setting, the sealer pulls away from the gutta-percha core, leaving a gap through which bacteria may pass. This article describes a new thermoplastic, synthetic root canal filling material, whose design is based on polyester chemistry, that looks and handles like gutta-percha. It is used in the same manner as most bonding systems. After the usual preparation of the root canal, a self-etch primer is used to condition the canal walls and prepare them for bonding to the resin. The resin sealant is introduced in the root canal. It bonds to the primer and to the resin core material; thus, a "monoblock" is formed without the gaps typical in gutta-percha fillings. Studies have shown that leakage of bacteria with this material is significantly reduced compared with gutta-percha.

Dental Leakage↗

PubMed2004

Fracture resistance of roots endodontically treated with a new resin filling material.

BACKGROUND: The authors evaluated the fracture resistance of endodontically treated teeth filled with either gutta-percha or a new resin-based obturation material. METHODS: The authors prepared and randomly divided 80 single-canal extracted teeth into five groups: lateral and vertical condensation with gutta-percha, lateral and vertical condensation with the new resin-based obturation material, and a control group with no filling material. The specimens were stored in 100 percent humidity for two weeks, mounted in polyester resin and loaded to failure. RESULTS: The authors found statistically significant differences among the experimental groups (P < .05). The groups with the new material displayed higher mean fracture loads and the gutta-percha groups lower mean fracture load values than the control unfilled group. However, the differences were not significant. The groups with the new material displayed significantly higher mean fracture loads than gutta-percha groups independent of the filling technique used. CONCLUSIONS: Filling the canals with the new resin-based obturation material increased the in vitro resistance to fracture of endodontically treated single-canal extracted teeth when compared with standard gutta-percha techniques. CLINICAL IMPLICATIONS; If other properties of the new resin-based obturation material compare favorably with those of gutta-percha for filling the root canal, it should be considered as a replacement for gutta-percha, as the results of this study indicate that it could provide enhanced resistance to tooth fracture.

Analysis of Variance↗

PubMed2004

Effect of tray-based and trayless tooth whitening systems on microhardness of enamel surface and subsurface.

PURPOSE: To evaluate the effect of tray-based and trayless tooth whitening systems on surface and subsurface microhardness of human enamel. METHODS: Enamel slabs were obtained from recently extracted human third molars. Specimens were randomly assigned to six groups according to tooth whitening treatment (n = 10): 6.0% hydrogen peroxide (HP) (Crest Whitestrips), 6.5% HP (Crest Professional Whitestrips), 7.5% HP (Day White Excel 3), 9.5% HP (Day White Excel 3), 10% carbamide peroxide (Opalescence), and a control group (untreated). Specimens were treated for 14 days following manufacturers' recommended protocols, and were immersed in artificial saliva between treatments. Enamel surface Knoop microhardness (KHN) was measured immediately before treatment, and at days 1, 7, and 14 of treatment. After treatment, subsurface microhardness was measured at depths of 50-500 microm. Data were analyzed for statistical significance using analysis of variance. RESULTS: Differences in microhardness for treated vs. untreated enamel surface were not statistically significant at any time interval. For 6.5% and 9.5% HP, there was a decrease in surface microhardness values during treatment, but at the end of treatment the microhardness values were not statistically different from the baseline values. For the enamel subsurface values, no differences were observed between treated vs. untreated specimens at each depth. Trayless and tray-based tooth whitening treatments do not significantly affect surface or subsurface enamel microhardness.

Carbamide Peroxide↗