Resumo em Inglês:

OBJECTIVES: Production of acids such as lactic acid contributes to establish a cariogenic environment that leads to dental substrate demineralization. Fluoride plays an important role in this case and, as fluoride-releasing materials, glass-ionomer cements are expected to contribute to minimize deleterious reactions. This study evaluated interactions of glass-ionomer cements used in atraumatic restorative treatment (ART-GICs) with an aqueous lactic acid solution, testing the null hypotheses that no changes occur in the pH of the solution or on the surface roughness and mass of the ART-GICs when exposed to lactic acid solution over a 6-week period. MATERIAL AND METHODS: Ketac Molar, Fuji IX, Vitro Molar and Magic Glass were tested, and compared to Filtek Z250 and Ketac Fil Plus as control groups. Six specimens of each material were made according to manufacturers' instructions. The pH of the solution and roughness and mass changes of each specimen were determined over 6 weeks. Each specimen was individually stored in 2 mL of 0.02 M lactic acid solution for 1 week, renewing the solution every week. pH of solution and mass of the specimens were monitored weekly, and surface roughness of the specimens was assessed before and at the end of the 6-week acid challenge. pH and mass data were analyzed statistically by repeated measures using one-way ANOVA and Tukey's post-hoc tests for each material. Paired t-tests were used for roughness analysis. Tukey's post-hoc tests were applied to verify differences of final roughness among the materials. Significance level was set at 5%. RESULTS: The null hypotheses were partially rejected. All materials were able to increase the pH of the lactic acid solution and presented rougher surfaces after immersion, while mass change was minimal and generally not statistically significant. CONCLUSIONS: These findings can be helpful to predict the performance of these materials under clinical conditions. A protective action against the carious process with significant surface damage due to erosion may be expected.

Resumo em Inglês:

OBJECTIVE: The time of contact between the product and enamel surface is important in ensuring the efficacy of fluoride varnishes. Thus, some alternatives could avoid fluoride loss to saliva and improve the anticariogenic action of the product. This study evaluated the effect of an experimental coat on the anticariogenic action of fluoride varnishes. MATERIAL AND METHODS: Enamel bovine blocks were selected by evaluating surface microhardness and randomized into five groups (n=24): placebo, DuraphatTM, DuraphatTM with coat, DuofluoridTM and DuofluoridTM with coat. Twelve blocks from each group were used to analyze calcium fluoride (CaF2) formed on enamel after treatment. The other 12 blocks were subjected to pH cycling for 7 days. The varnishes were kept on enamel for 6 h. Next, the percentage change of surface microhardness (%SMHC) and mineral loss (ΔZ) were calculated. CaF2 retained and fluoride present in the pH-cycled solutions were also measured. RESULTS: The use of the coat did not decrease %SMHC and ΔZ, but all fluoride varnishes had better results when compared to the placebo (ANOVA and Kruskal-Wallis, respectively). The values from CaF2 formed were higher compared to the values of CaF2 retained (non-paired t test, p<0.05). There was a trend to decrease the amount of F in the solutions at the end of pH cycling (Kruskal-Wallis, p<0.05). CONCLUSIONS: Although the experimental coat increased the formation of CaF2 on the enamel surface, it did not significantly improve the anticariogenic action of fluoride varnishes.

Resumo em Inglês:

OBJECTIVES: This study evaluated the effectiveness of different home bleaching agents on color alteration and their influence on surface and subsurface microhardness of discolored bovine enamel. MATERIAL AND METHODS: Forty-five fragments of bovine incisors were randomly allocated into 3 groups (n=15) according to the bleaching agent: 10% carbamide peroxide gel (CP10), 16% carbamide peroxide gel (CP16) and 6.5%-hydrogen-peroxide-based strip (HP6.5). Before bleaching treatment, initial values of Knoop surface microhardness and color (CIEL*a*b*) were obtained and the fragments were artificially stained in hemolyzed rat blood. Then, bleaching treatments were performed over a 21-day period. Color changes (ΔE) were assessed at 7, 14 and 21 days, and final surface microhardness reading was done after 21 days. Thereafter, the fragments were bisected to obtain subsurface microhardness. Data were subjected to ANOVA and Tukey's tests (α=5%). RESULTS: Color changes produced by CP16 were similar to those of CP10, and the color changes produced by these materials were significantly superior to those produced by HP6.5. Color changes at 21 days were superior to 7 days and similar to 14 days. The time did not influence color changes for CP16, which showed similarity between the 14- and 21-day results. No statistically significant differences were found among the home bleaching agents for surface and subsurface microhardness. CONCLUSIONS: Microhardness of bovine enamel was not affected by the bleaching agents. The 16% carbamide peroxide gel was the most effective for bleaching the stained substrate.

Resumo em Inglês:

OBJECTIVE: The aim of this study was to determine the influence of different energy densities on the heat generated during photoactivation of Filtek Z250 (3M/ESPE) and Z100 (3M/ESPE) composite resins with different dentin and composite thickness. MATERIAL AND METHODS: The temperature increase was registered with a type-K thermocouple connected to a digital thermometer (Iopetherm 46). A chemically polymerized acrylic resin base was prepared to serve as a guide for the thermocouple and as a support for 0.5-, 1.0-, and 1.5-mm-thick bovine dentin discs. Circular elastomer molds (1.0 mm-height x 3.0-mm diameter or 2.0-mm height x 3.0-mm diameter) were adapted on the acrylic resin base to standardize the composite resin thickness. A conventional halogen light-curing unit (XL 2500, 3M/ESPE) was used with light intensity of 700 mW/cm². Energy density was calculated by the light intensity applied during a certain time with values of 28 J/cm² for Z100 and 14 J/cm² for Filtek Z250. The temperature change data were subjected to three-way ANOVA and Tukey's test at 5% level. RESULTS: The higher energy density (Z100) promoted greater temperature increase (p<0.05) than the lower energy density (Filtek Z250). For both composites and all composite thicknesses, the lowest dentin thickness (0.5 mm) yielded significantly higher (p<0.05) temperature increase than the other two dentin thicknesses. The 1-mm-thick composite resin layer yielded significantly higher (p<0.05) temperature changes for both composites and all dentin thicknesses. CONCLUSIONS: Temperature increase was influenced by higher energy density and dentin/composite thickness.

Resumo em Inglês:

OBJECTIVES: The aim of this study was to determine the effect of environmental conditions on the degradation of ionomeric and resin sealant materials. MATERIAL AND METHODS: FluroShield, Vitremer, and Ketac Molar disc-shaped specimens (n=18/material) were prepared, polished, subjected to initial hardness and roughness readings. Six discs of each material were randomly assigned to one of three different storage solutions: 0.3% citric acid (CA), demineralization solution (DE), and remineralization solution (RE). The specimens were individually immersed in 3 mL of the test solutions, which were daily changed. After 15 days of storage, new surface roughness and hardness readings were done. Fluoride release in the solutions was measured within 15 days. Data were analyzed by ANOVA and Tukey's and Contrast tests (α=0.05). RESULTS: The storage in CA increased the roughness of Vitremer and Ketac Molar. A significant reduction in hardness was observed for all materials after storage in all solutions. For all materials, the greatest amounts of fluoride release occurred during the 1st day. FluroShield presented the same patterns of fluoride release in all solutions. Ketac Molar and Vitremer released the highest amounts of fluoride in the CA solution. CONCLUSIONS: Ionomeric materials are more susceptible to degradation than resin-based materials under acidic conditions. Acidic conditions lead to a higher fluoride release from ionomeric materials.

Resumo em Inglês:

OBJECTIVE: Narrow diameter implants (NDI) (i.e. diameter <3.75 mm) are a potential solution for specific clinical situations, such as reduced interradicular bone, thin alveolar crest and replacement of teeth with small cervical diameter. NDI have been available in clinical practice since the 1990s, but only few studies have analyzed their clinical outcome and no study have investigated NDI inserted in fresh-frozen bone (FFB) grafts. Thus, a retrospective study on a series of NDI placed in homologue FFB was designed to evaluate their clinical outcome. MATERIAL AND METHODS: In the period between December 2003 and December 2006, 36 patients (22 females and 14 males, mean age 53 years) with FFB grafts were selected and 94 different NDI were inserted. The mean follow-up was 25 months. To evaluate the effect of several host-, surgery-, and implant-related factors, marginal bone loss (MBL) was considered an indicator of success rate (SCR). The Kaplan Meier algorithm and Cox regression were used. RESULTS: Only 5 out of 94 implants were lost (i.e. survival rate - SVR 95.7%) and no differences were detected among the studied variables. On the contrary, the Cox regression showed that the graft site (i.e. maxilla) reduced MBL. CONCLUSIONS: NDI inserted in FFB have a high SVR and SCR similar to those reported in previous studies on regular and NDI inserted in non-grafted jaws. Homologue FFB is a valuable material in the insertion of NDI.

Resumo em Inglês:

OBJECTIVE: The purpose of this study was to investigate the clinical performance of high-strength glass ionomer cement (HSGIC) and resin-modified glass ionomer (RMGIC) in single and multiple surface carious cavities in the field conditions. MATERIAL AND METHODS: A split-mouth design, including ninety-one fillings placed on contra lateral molar pairs of 37 children, was used in permanent dentition. As filling materials, a HSGIC (Ketac Molar/3M ESPE) and a RMGIC (Vitremer/ 3M ESPE) were used with the Atraumatic Restorative Treatment (ART). Baseline and 6, 12 and 24-month evaluations of the fillings were made with standard-ART and USPHS criteria by two examiners with kappa values of 0.92 and 0.87 for both criteria. RESULTS: According to the USPHS criteria, the retention rates of RMGIC and HSGIC restorations were 100% and 80.9% for single surface, and 100% and 41.2% for multiple surface restorations after 24 months, respectively. Irrespective of surface number, RMGIC was significantly superior to HSGIC (p= 0.004), according to both standard-ART and USPHS criteria. CONCLUSION: The results indicate that RMGIC may be an alternative restorative technique in comparison to high-strength GIC applications in ART-field-trials. However, further clinical and field trials are needed to support this conclusion.

Resumo em Inglês:

OBJECTIVES: To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters. MATERIAL AND METHODS: Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (bur-cut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm² cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukey's test (α=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope. RESULTS: The main factor adhesive system was statistically significant (p<0.05). The mean bond strength values (MPa) and standard deviations were: CSE (20.5±3.5), OP (11.3±2.3), AD (11.2±2.8), TY (11.1±3.0), SBMP (21.9±4.0) and SB (24.9±3.0). Different etching patterns were observed for the self-etching primers depending on the enamel treatment and the pH of the adhesive system. CONCLUSION: Although there is a tendency towards using adhesive systems with simplified application procedures, this may compromise the bonding performance of some systems to enamel, even when the prismless enamel is removed.

Resumo em Inglês:

OBJECTIVES: Natural latex does not fall into the category of materials known to be entirely inoffensive. The purpose of this in vitro study was to test the hypothesis that there is no difference in the cytotoxicity between elastics of different colors and those from different manufacturers. MATERIAL AND METHODS: Different latex intraoral elastics of different colors (5/16 = 7.9 mm, mean load) were compared. The sample was divided into 7 groups of 24 elastics each: Group T (TP Orthodontics, natural latex elastics, control); Groups U1, U2, U3, U4, U5 and U6 (Uniden, natural latex elastics and colored elastics, namely, green, pink, yellow, red and purple, respectively). Cytotoxicity assays were performed by using cell culture medium containing epithelioid-type cells (Hep-2 line) derived from human laryngeal carcinoma. The cytotoxicity was evaluated by using the "dye-uptake" test, which was employed at two different moments (0 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukey's test (p<0.05). RESULTS: There was statistically significant difference (p<0.05) between Group T and all other groups (U1, U2, U3, U4, U5 and U6) at 0 and 24 h. No statistically significant difference (p<0.05) was found between Groups U1 and U5, U1 and U6, U2 and U3, U2 and U4, U2 and U5, U2 and U6, U3 and U4, U3 and U5, U3 and U6, U4 and U5, U4 and U6, and U5 and U6 at 0 and 24 h. CONCLUSIONS: The TP Orthodontics elastics promoted less cell lysis compared to the Uniden elastics regardless of their color.

Resumo em Inglês:

OBJECTIVES: The aim of this study was to evaluate the influence of the crown shape on the outcomes of root coverage procedures. MATERIAL AND METHODS: Eighty patients with Miller class I gingival recessions in maxillary canines or premolars were selected. The recession areas were treated using the subepithelial connective tissue grafting. The following clinical parameters were analyzed: crown length (CL) and width (CW), recession height and width, probing depth, clinical attachment level, width and thickness of the keratinized tissue and percentage of root coverage achieved. These measurements were recorded at baseline and 6 months after the surgical procedure. The CW/CL ratio was calculated for each tooth and the median obtained (0.83). Patients were then ranked into two groups, according to the shape of the tooth with gingival recession: Group A - square crown shape (CW/CL values above 0.83) and Group B - long and narrow crown shape (CW/CL values below 0.83). RESULTS: No statistically significant differences (p>0.05) were found between groups in any of the clinical parameters at baseline. After 6 months, both groups presented improved clinical outcomes for all parameters analyzed compared to baseline (p>0.05). The mean percentages and standard deviations of root coverage achieved in Group A and Group B was 91.37 (16.75) and 85.49 (23.55), respectively (p>0.05). CONCLUSIONS: Crown shape did not influence the root coverage obtained with the subepithelial connective tissue graft technique.

Resumo em Inglês:

OBJECTIVE: This study investigated the pulpal effect of topically applied betamethasone to the dentin of rat molars in the vascular phase of inflammation. MATERIAL AND METHODS: Deep cavities were prepared on the occlusal face of the maxillary right and left 1st molars with non-refrigerated inverted-cone steel burs at low speed. Three groups were formed: Group I was composed of right 1st molars; Group II was composed of left 1st molars that received the application of a drop of betamethasone on dentin surface for 5 min; and Group III (control) was composed of right 2nd molars that received no cavity preparation or betamethasone application. Changes in the vascular characteristics of the pulp tissue were checked by calculating the pulp vascular area in relation to its total area and the number of blood vessels per unit area. Data were subjected to ANOVA and Tukey's test (?=0.05). RESULTS: Group I presented a significantly larger number of vessels (p<0.05) than Group II. Regarding the vascular/total area ratio (%), Group I presented statistically significantly higher values (p=0.01) than Groups II and III. CONCLUSION: Betamethasone applied on the dentin of rat teeth proved to reduce the vascular phase of pulp inflammation regarding vessel diameter and number of blood vessels.

Resumo em Inglês:

The purpose of this study was to determine the influence of incrementally added uncured HEMA in experimental HEMA-added glass ionomer cement (HAGICs) on the mechanical and shear bond strength (SBS) of these materials. Increasing contents of uncured HEMA (10-50 wt.%) were added to a commercial glass ionomer cement liquid (Fuji II, GC, Japan), and the compressive and diametral tensile strengths of the resulting HAGICs were measured. The SBS to non-precious alloy, precious alloy, enamel and dentin was also determined after these surfaces were subjected to either airborne-particle abrasion (Aa) or SiC abrasive paper grinding (Sp). Both strength properties of the HAGICs first increased and then decreased as the HEMA content increased, with a maximum value obtained when the HEMA content was 20% for the compressive strength and 40% for the tensile strength. The SBS was influenced by the HEMA content, the surface treatment, and the type of bonding surface (p<0.05). These results suggest that addition of an appropriate amount of HEMA to glass ionomer cement would increase diametral tensile strength as well as bond strength to alloys and teeth. These results also confirm that the optimal HEMA content ranged from 20 to 40% within the limitations of this experimental condition.

Resumo em Inglês:

The internal derangement of the temporomandibular joint (TMJ) represents 8% of all cases of temporomandibular disorders (TMD) posing difficulties to establish an accurate diagnosis and treatment because of its low prevalence. This article presents the case of an 18-year-old Caucasian female patient who came to our Orofacial Pain and TMD Outpatient Service with complaints of intense pain on the right TMJ and limitation of mouth opening (maximum interincisal opening of 29 mm) with deviation to right, which she had been experiencing for the past 3 years. After a detailed clinical interview, a diagnosis hypothesis of nonreducing disc displacement with mouth opening limitation was established. The proposed treatment consisted of intra-joint infiltration with anesthetic in the right TMJ followed by jaw manipulation to recapture the articular disc, which was impeding the complete translation movement of the affected TMJ. After jaw manipulation, a new evaluation was done and showed the re-establishment of jaw dynamics with mouth opening and closing without deviation to the right side, clicking, opening limitation or pain. The patient was followed up at 6 months intervals. Two years after treatment, the patient was reevaluated and her mandibular range of motion without aid increased to 54 mm with no clicking, deviation to right, trismus or pain on the TMJ, indicating success of the treatment approach without recurrence of the pathology.

Resumo em Inglês:

Class III malocclusions are considered one of the most complex and difficult orthodontic problems to diagnose and treat. Skeletal and/or dental asymmetries in patients presenting with Class III malocclusions can worsen the prognosis. Recognizing the dentoalveolar and skeletal characteristics of subdivision malocclusions and their treatment possibilities is essential for a favorable nonsurgical correction. Therefore, this article presents a nonsurgical asymmetric extraction approach to Class III subdivision malocclusion treatment which can significantly improve the occlusal and facial discrepancies.