Pesquisa odontologica brasileira = Brazilian oral research最新文献

Thermocycling simulates, in vitro, thermal changes that occur in the oral cavity. The aim of this study was to evaluate the influence of the number of cycles on microleakage. Class V cavities (1.5 mm deep, 3 mm in height and 3 mm in width) were prepared in bovine teeth, restored with a Single Bond/Z250 restorative system (3M/ESPE) and then divided into five groups of ten teeth each: group 1 was not thermocycled (control group), and groups 2, 3, 4 and 5 were thermocycled 500, 1,000, 2,500 and 5,000 times, respectively (5 degrees -55 degrees +/- 2 degrees C, 15 s dwell time). The teeth were immersed in 0.5% basic fuchsin aqueous solution for 24 h, sectioned and the sections with the highest degree of microleakage were selected, scanned and the extent of dye penetration was measured by the ImageTool program. The results submitted to one-way ANOVA showed no significant differences between the groups (p > 0.05). The averages of microleakage values in millimeters were: group 1 (3.92); group 2 (3.13); group 3 (4.48); group 4 (4.33) and group 5 (3.42). Thus, it was concluded that there is no relation between the increase of the number of cycles and the increase in microleakage.

The effects of two experimental protocols (ovariectomy associated or not with a low calcium diet) used to promote osteoporosis in the rat maxilla and proximal tibia were compared 5 and 11 weeks after surgery. Female Wistar rats were ovariectomized or sham-operated. Half of the ovariectomized rats were fed a low Ca++ diet (ovx*) and the remaining ovariectomized (ovx) and sham animals received a standard chow. At sacrifice, the proximal metaphysis was excised from the tibia and the molars were extracted from the hemi-maxilla. Dry (60 degrees C overnight) and ash (700 degrees C/14 h) weights were measured and the ashes were used for Ca++ measurement by means of a colorimetric method. After 5 weeks, ovx caused no alteration while ovx* decreased proximal metaphysis (17%) and maxilla (35%) bone mass. After 11 weeks, ovx caused a 14% bone mass reduction in the proximal metaphysis but not in the maxilla, while ovx* caused a comparable bone mass reduction (30%) in both bone segments. Calcium concentration was not altered in any experimental condition. The results show that estrogen deficiency is insufficient to cause maxillary osteoporosis in rats over an 11-week period and a long-term ovariectomy is needed to exert deleterious effect on proximal metaphysis bone mass. When a low Ca++ diet is associated with estrogen deficiency, however, a relatively precocious harmful effect is observed, twice as pronounced in the maxilla than in the proximal metaphysis. On a long-term basis, ovariectomy associated with a low Ca++ diet seems to be equally injurious to both proximal metaphysis and maxilla.

The aim of this randomized, double-blind clinical trial was to evaluate the effect of the Paradontax dentifrice on the reduction of plaque and gingivitis. Subjects were randomly allocated into either the test group (n = 15, Paradontax) or the control group (n = 15, standard dentifrice with fluoride). Plaque levels were measured using the Turesky modification of the Quigley & Hein Plaque Index (PI), and gingivitis was evaluated with the Gingival Index (GI). Subjects were asked to brush their teeth with the allocated dentifrice, three times a day, for 21 days. There was no significant difference between groups in relation to the PI and GI medians, at baseline and at the end of the 21-day period. There was no significant reduction in PI in either the test or control groups. There was a significant decrease in GI in the test group. The authors concluded that there was no difference between the dentifrices in the reduction of plaque and gingivitis.

The effects of oral environment stabilization procedures on counts of Candida spp. have rarely been discussed, and no conclusive results are found in the literature. The aim of this study was thus to ascertain the effects of oral environment stabilization procedures with glass ionomer and zinc oxide-eugenol cements on counts of Candida spp. in the oral cavity of children. For this purpose, oral rinses of sterile phosphate-buffered saline were initially collected from 30 boys and 30 girls, positive for Candida in the saliva and aged from 4 to 10 years. Data on the initial quantity of CFU/ml of Candida were obtained. Then, the children were randomly divided into two groups and oral environment stabilization procedures were performed using zinc oxide-eugenol cement or glass ionomer cement. One week after the procedures were performed, oral rinses were collected again and final Candida counts were obtained. An expressive reduction in Candida counts was observed in both groups. The zinc oxide-eugenol and glass ionomer cements were efficient in the reduction of Candida counts and statistically significant differences were observed between initial and final counts in both groups. Considering the percentage of reduction, the zinc oxide-eugenol cement presented more favorable results, with a reduction of 70%. A reduction of 46% was observed with the use of the glass ionomer cement. According to the obtained results, we concluded that oral environment stabilization procedures were efficient in reducing Candida spp. counts, especially when the zinc oxide-eugenol cement was employed.

Modern restorative dentistry has been playing an outstanding role lately since composite resins, allied to adhesive systems, have been widely applied on anterior and posterior teeth restorations. The evolution of composite resins has mostly been verified due to the improvement of their aesthetic behavior and the increase in their compressive and abrasive strengths. In spite of these developments, the polymerization shrinkage inherent to the material has been a major deficiency that, so far, has been impossible to avoid. Using a gas pycnometry, this research investigated the polymerization shrinkage of three packable composite resins: Filtek P60 (3M), Prodigy Condensable (Kerr), and SureFil (Dentsply/Caulk), varying the distance from the light source to the surface of the resins (2 mm or 10 mm). The pycnometer Accupyc 1330 (Micromeritics, USA) precisely records helium displacement, allowing fast and reliable measurements of the volume of composite resin immediately before and after polymerization, without interference of temperature or humidity. Results were not found to be statistically different for the three tested resins, either for 2 mm or 10 mm-distance from the light source to the composite surface.

The purpose of this study was to evaluate in vitro the effects of different associations between irrigating solutions (EDTA-T and citric acid), intracanal medicament (NDP), and Er:YAG laser irradiation on dentin permeability. Fifty-one extracted single-rooted teeth were instrumented and divided into seven groups. Groups GI and GII had final irrigation with a demineralizing solution only (EDTA-T and citric acid, respectively). Groups GIII and GIV had final irrigation with EDTA-T and citric acid, respectively, plus an association of irrigating solution and Er:YAG laser. Groups GV and GVI had final irrigation with EDTA-T and citric acid, respectively, plus an association of intracanal medication and Er:YAG laser. Group GVII (control group) had final irrigation with distilled water. All root canals were filled with NDP associated with rhodamine B dye. After the experimental period, the samples were transversely cut into six 2.0 mm thick slices for subsequent reading using the ImageLab software. Analysis of the results allowed us to conclude that there were statistically significant differences (p < 0.05) between the groups as to the penetration of the dye-intracanal medication solution. Groups III and IV presented smaller values of dentinal permeability when compared to the other groups. The best results were obtained with the interaction between a demineralizing irrigating solution and the association of intracanal medicament and laser Er:YAG (groups V and VI). In these groups the observed penetration of the intracanal medicament plus dye solution in the apical third was, on average, 29% greater than in the other groups.

The minimum requirement for the anti-caries effect of a dentifrice is the presence of available and stable fluoride in the formulation. The concentration of available fluoride in the major dentifrices sold in Brazil has been reported, but few data have been published about its stability, which is temperature-dependent. Thus, the aim of this study was to evaluate the concentration and stability of fluoride in dentifrices sold in Manaus, AM, Brazil, which is a typical tropical city. The concentrations of total fluoride, total soluble fluoride, MFP, and of insoluble fluoride of six Brazilian dentifrices and an imported one were analyzed. The analyses were made when the dentifrices were purchased and during a year of storage at room temperature (28.9 1.16 C) and under refrigeration (26.3 0.88 C). The analyses were performed using an ion specific electrode Orion 96-09. At the time of purchase, all the dentifrices analyzed showed more than 1,000 ppm (mug F-/g; w/w) of soluble fluoride. However, in most of them, this form of fluoride was not shown to be stable. The highest loss of soluble fluoride was found for storage at room temperature, reaching up to 40%. Although all dentifrices comply with the Brazilian guidelines with regard to the concentration of total fluoride (maximum of 0.15%), the instability of soluble fluoride observed in some of them can impair their anti-caries effect and this condition is not contemplated in the Governmental rules.

The aim of this study was to evaluate the influence of storage periods of 24 hours and 3 months on the microleakage of class II cavities. Two methods of assessing microleakage were also compared. Class II cavities were prepared in sound human molars. MO cavities were restored using ABF experimental (Kuraray Medical Inc.) + Z250 composite resin (3M ESPE), and DO cavities were restored using Single Bond (3M ESPE) + Z250. After different storage periods, specimens were thermocycled, immersed in a dye (0.5% methylene blue solution for 4 h) and longitudinally sectioned. Dye penetration was scored according to a 0-4 scale. The extent of microleakage was measured using the ImageLab 2000 program. A statistically significant correlation was verified between both evaluation methods (r = 0.978, p < 0.001). ANOVA revealed a statistically significant difference between the tested adhesive systems regarding microleakage (p < 0.001), although it was not influenced by the different storage periods.

The use of autogenous bone grafts is considered to be the best choice for reconstructive surgery. In the periodontal literature, the utilization of osseous coagulum was suggested by the end of the sixties. The purpose of this study is to consider the use of bone collectors (bone traps) as an alternative method for obtaining material to fill small bone imperfections, such as fenestrations and dehiscences. Thirty samples were obtained from bone drilling during fixture installation in patients (13 men and 17 women, with an average age of 54 years) requiring treatment at the Department of Periodontology and Implant Dentistry, University of Santo Amaro. These samples were fixed in 10% neutral formaldehyde for 24 hours and subjected to histological preparation, in order to evaluate the presence of viable osteoblasts. In addition, the material was placed in a fluid thioglycolate medium and incubated for 24 hours at 36 1 C in aerobiosis and anaerobiosis. Bacterial growth evaluation was made by using six different culture media (MacConkey agar, blood agar base, mannitol salt agar, Anaerokit LTD medium, Anaerokit LTD - bile medium, Anaerinsol). The results show that, if proper care is taken to prevent saliva contamination during the surgical procedure, this method of collecting autogenous bone may be useful in situations where small amounts of bone are required.