Biomedical subjects

Margareth Oda

Publications and source records attributed to Margareth Oda.

5 recordsLinked to original sources

PubMed2006

Bond strength analysis of intracanal posts used in anterior primary teeth: an in vitro study.

The purpose of this in vitro study is to assess the bond strength of three different posts used to restore primary anterior teeth. These posts were made by composite resin, 0.7 mm alpha-shaped orthodontic wire and dentin posts. Thirty roots of extracted primary anterior teeth, with initial physiological resorption, were mounted in a container filled with self cured resin and were endodontically treated Thirty posts were prepared using three different materials: 10 composite resin posts (Z100), 10 alpha-shaped orthodontic wire and 10 dentin posts. A bulk of composite resin (Z100) was made over the posts using a circular Teflon bisected strip. The specimens were stored in 37 degrees C water solution for 24 hours before tensile bond strength tests in 0.5 mm/min speed were performed (Instron model 4442 test machine--Instron Corporation). The results were submitted to the Kruskal-Wallis test and there were no significant statistical differences among the three types of posts assessed (p = 0.8666). The dentin posts technique might be considered an alternative for rehabilitation in pediatric dentistry, because of the possibility of natural resorption.

Acid Etching, Dental↗

PubMed2005

Antibacterial activity of glass-ionomer cement containing antibiotics on caries lesion microorganisms.

PURPOSE: To assess the total viable bacteria in infected dentin after sealing with glass-ionomer cement containing 1% metronidazole, 1% ciprofloxacin and 1% cefaclor. METHODS: 40 children were selected, with ages ranging from 4-10 years, with primary teeth with active carious lesions without any pulpal involvement. The patients were divided randomly into two groups in accordance to the glass-ionomer cement used to seal the carious lesions: Group 1 (control, n=20), sealing with conventional glass-ionomer cement; and Group 2 (test, n=20) sealing with glassionomer cement including antibiotics. The infected dentin was collected both before and 24 hours after the sealing of the cavities and, after inoculation in blood agar, all the plates were incubated in containers kept at 37 degrees C for 5 days in an atmosphere of 85% N2, 10% CO2 and 5% H2, for subsequent counting of total viable bacteria. RESULTS: The results were analyzed using the Wilcoxon and Mann-Whitney tests. The glass-ionomer cement with 1% of metronidazole, 1% of ciprofloxacin and 1% of cefaclor showed a significantly greater reduction in microbiota in the infected dentin in comparison to the reduction with the conventional ionomer cement (P< 0.01), with a mean reduction of 98.65% of all viable bacteria. The infected dentin after sealing with glass-ionomer cement with antibiotics showed, using scanning electron microscopy, the presence of bacterial aggregates, intertubular dentin with exposure of collagen fibers, and dentin tubules.

Anti-Bacterial Agents↗

PubMedDate not supplied

Surface roughness in ceramics with different finishing techniques using atomic force microscope and profilometer.

This study assessed the finishing and polishing of 3 ceramic materials: Vitadur Alpha, IPS Empress 2 and AllCeram. Surface modification techniques were selected to simulate dental practice. Forty-five specimens of each ceramic were divided into 5 groups of 9 specimens, which were finished using the following procedures: Group 1--glaze; Group 2--glaze, grinding and subsequent polishing with the Eve system; Group 3--glaze, grinding and subsequent polished with the Identoflex system; Group 4--glaze followed by polishing with Identoflex; Group 5--glaze, grinding and subsequent polishing with Shofu kit. Two roughness-measuring instruments were used: a stylus profilometer and an atomic force microscope (AFM). The 135 specimens were evaluated quantitatively with respect to Ra (average roughness) and Ry (maximum roughness height), and the results were examined statistically by ANOVA and Tukey's test, with a significance level of 0.05. The roughness parameter (Ra), measured by the profilometer, and AFM showed that some of the commercial intraoral polishing kits tested achieved a finish equal in smoothness to the glazed surface. According to Pearson's test, no correlation was found between the parameter Ry, measured with the profilometer, and AFM. The profilometer results for Ry demonstrated no significant differences between the final polished surfaces and the initial glazed ones. On the other hand, the Ry values obtained by AFM indicated the tested polishing kits incapability of producing smoothness comparable to the glazed surfaces.

Aluminum Oxide↗

PubMedDate not supplied

Re-attachment of anterior fractured teeth: fracture strength using different materials.

This study compared the fracture strength of two different techniques (bonded only and buccal chamfer) and different material combinations used to reattach tooth fragments. An axial load applied to the buccal area fractured 110 sound permanent lower incisors. Fifty teeth were designated for the bonded only group (no additional preparation) and 50 teeth were designated for a buccal chamfer group. For each group teeth were subdivided into five subgroups (n = 10) according to the restorative material combinations used: 1) adhesive system (A); 2) A + light cured luting cement; 3) A + dual cured luting cement; 4) A + flowable resin and 5) A + hybrid resin. In a control group (resin composite build-up), in the remaining 10 teeth, the crown portion was rebuilt with adhesive and resin composite. Restored teeth were subjected to the same loading in the same buccal area. Fracture strength after restorative procedures for all groups was expressed as a percentage of the original fracture strength and the results were analyzed by two-way ANOVA and Tukey's test for pair-wise comparison. The interaction and the material factor were not statistically significant (p = 0.140 and p = 0.943, respectively). The chamfer group showed higher fracture strength recovery (67.9%) than the bonded only group (41.1%), and both were statistically lower than the resin composite build-up (103.2%). It was concluded that the material used to reattach the fragment is less important than the chosen technique.

Analysis of Variance↗

PubMedDate not supplied

Simultaneous activation technique: an alternative for bonding composite resin to glass ionomer.

PURPOSE: The purpose of this study was to evaluate a new simultaneous activation technique (SAT)-for the union between glass ionomer cements and composite resins. METHODS: Forty primary molars were embedded in self-curing acrylic resin. Class I cavity preparations were performed on the dentin surface and the teeth were randomly divided into 4 groups (N = 10). Two groups were restored with the SAT and 2 by etching the ionomer surface/sandwich technique (ST). The materials tested were Vidrion F (SS/ White), Vitremer (3M), and Z100 (3M). After 24 hours in aqueous solution at 37 degrees C, a tensile test was performed. The microleakage study was also performed by selecting 40 primary molars which were distributed in the same way as in the bond strength test. Furthermore, 1 tooth from each group of the microleakage test was evaluated by means of scanning electron microscopy. RESULTS: The SAT and ST did not show statistically significant differences in both tests. CONCLUSIONS: The SAT is a less complex, quicker, and feasible alternative for the bonding of glass ionomer cements to composite resins in primary molars.

Acid Etching, Dental↗