Effects of different treatments on chemical and morphological features of eroded dentin.

To evaluate the treatment of eroded dentin (Sensodyne Repair & Protect™, Er:YAG laser and combinations). The occlusal surfaces of 25 third molars were sectioned 1.5 mm in thickness. After an erosion cycle (5 min in demineralizing solution + 3 h in remineralizing solution; six cycles a day for 8 days), the samples were divided into five groups (n = 5): (E) erosion - control; (ES) erosion + Sensodyne Repair & Protect (NovaMin); (EL) erosion + Er:YAG laser (40 mJ, 10 Hz, 0.4 W, 50 µs, 3.1 J/cm2, 63 W/cm2); (ELS) erosion + Er:YAG laser + Sensodyne; and (ESL) erosion + Sensodyne + Er:YAG laser. Following storage in ultrapure water (37 °C/14 days), the Ca/P ratio was evaluated by EDXRF and the morphology surfaces examined in SEM. The percentage of exposed dentin tubules was calculated. One-way analysis of variance and Tukey's test at 5% were used to treat the data. The Ca/P ratio was higher in E and ES groups. More exposed dentin tubules were found in E group and less exposed tubules were found in the ES group (p < 0.0001). When the toothpaste and laser were combined, the number of occluded dentin tubules was higher when laser was performed first (ELS). A positive effect was found when the laser and toothpaste were combined.

Multiple Adhesive Layering Influence on Dentin Bonding and Permeability.

The aim was to evaluate the effect of the number of layers on the microtensile bond strength (µTBS), permeability and nanoleakage of an etch-and-rinse adhesive (Adper Single Bond 2). Different numbers of layers (1, 2 and 4) were applied on dentin susbstrate. Specimens were obtained and tested for µTBS. Stick-shaped samples were analysed by scanning electron microscope, to observe silver nitrate penetration. One-way ANOVA and Tukey tests were applied (α=0.05) for µTBS values. The fracture mode was evaluated under a stereomicroscope and a scanning electron microscope (SEM). Groups with two and four layers of bond showed higher µTBS to dentin and they also showed lower adhesive permeability than ONE layer. The silver nitrate uptake occurred in the hybrid layer in practically all groups. Fracture occurred predominantly at the mixed interface. The authors recommend the application of more than one layer of Adper Single Bond 2, because a single layer showed lower µTBS and higher permeability values.

Effect of bleaching agents on the flexural strength of bovine dentin.

The aim of this study was to evaluate the effect of bleaching on the flexural strength of bovine dentin, using bleaching agents containing calcium (Whiteness HP Blue and Whiteness Class) and not containing calcium (Whiteness HP and Whiteness Perfect). Sixty bovine incisor tooth slices were obtained and divided into fve experimental groups (n = 12), such as G1, untreated control group; G2, Whiteness HP Max [35% hydrogen peroxide (HP)]; G3, Whiteness HP Blue (35% HP); G4, Whiteness Class (7.5% HP) and G5, Whiteness Perfect (22% carbamide peroxide). Samples were submitted to bleaching treatment according to the manufacturers' instructions. The control group remained in artificial saliva during bleaching. After bleaching, the enamel was removed and dentin specimens (7 mm length × 1.7 mm width × 0.5 mm thickness) were prepared. Samples were tested in a universal testing machine (EMIC). Data were analyzed by analysis variance (ANOVA) and Tukey's test. Differences between the groups were identified by ANOVA. The mean values (± standard deviation) for the experimental groups, such as (in MPa) G1 = 19.05 ± 2.68 a; G2 = 12.69 ± 4.52 b; G3 = 16.39 ± 3.74 ab; G4 = 14.90 ± 5.60 ab; and G5 = 12.71 ± 2.25 b. Groups with the same lowercase letter were significantly different from each other. The presence of calcium in bleaching agents appeared to influence the flexural strength of bovine dentin after bleaching treatment, for both office bleaching (35% HP) and home bleaching (7.5% HP).

In vitro effect of two resin based materials for treating initial caries lesion around braces, under cariogenic challenge.

Background: Orthodontic treatment makes the patient susceptible to the development of white spot lesions (WSL) due to the greater accumulation of bacterial plaque. The purpose of this in-vitro study was to evaluate the preventive effect of two resin materials on the incidence of these lesions in the region adjacent to the fixed bracket bonded under a WSL-treated area by two resin materials. Material and Methods: 36 extracted human molars presenting natural WSL were included. They were randomly divided into 2 groups for intervention: IC (Infiltration resin Icon®) and PS (resin sealant Pro Seal ®). Braces were bonded just above the WSL. The enamel surface around the brace was treated by one of the tested materials, leaving another part to be control. The samples were submitted again to a cariogenic challenge. The exposed enamel non-treated area from booth groups comprised the control group (E). For morphological analysis, confocal images were taken at baseline, after treatment, and after pH cycling of each sample. Lesion depth were measured (µm) and compared to the enamel thickness to calculate a demineralization index. All groups were compared using the Kruskal Wallis test and Dunn's post-test. Results: PS group showed the lowest demineralization index (0.27 µm) when compared to the control area (0.39 µm) (p<0.05). IC presented a slightly higher percentage of lesions when compared to PS, however, did not differ significantly from the control exposed area. Conclusions: The resin sealant Pro Seal® had a positive protective effect under white spot environmental area and Icon® infiltrant, although showed some protection, did not statistically differ from controls. Key words:Dental Caries, Orthodontics, Dental Enamel, Sealants.

Bond strength and morphology of resin materials applied to the occlusal surface of primary molars.

BACKGROUND: Hydrophilic adhesives may be used as pit and fissure sealants (sealants), but there is concern about the ability of self-etching adhesives to bond sealants to enamel. AIM: To study the bond strength (BS) and morphology of adhesive systems used as sealants. DESIGN: OptiBond FL, OptiBond All-in-One, combined OptiBond All-in-One+OptiBond FL adhesive, and Fluroshield were applied to the occlusal surfaces of 16 primary molars (n = 4). Teeth were stored in distilled water (24 h at 37°C) and sectioned through the interface to obtain sticks (0.8 mm(2) ) tested under a tensile load (0.5 mm/min). Failure modes were observed. Data were analysed by ANOVA and Tukey's tests (α = 5%). The morphology of 12 primary molars was examined in terms of the etching pattern and resin reproduction. RESULTS: Differences in the BS were found (P = 0.001), with OptiBond FL showing the highest (36.84 ± 5.7 MPa), Fluroshield (24.26 ± 2.13 MPa) and OptiBond All-in-One (17.12 ± 4.97 MPa) similar, and OptiBond All-in-One + OptiBond FL adhesive the lowest (9.8 ± 2.94 MPA). OptiBond FL showed the best results in terms of morphology. CONCLUSION: Under the conditions of this study, OptiBond FL was the best material to be used for sealing.

Evaluation of the light energy transmission and bottom/top rate in silorane and methacrylate-based composites with different photoactivation protocols.

AIM: This study investigated the influence of different composite resin organic matrix (methacrylate - Filtek Z350 XT and silorane - Filtek P90) on light energy transmission through the composite and bottom/top rate. MATERIALS AND METHODS: A light-emitting diode (New Blue Phase), light-curing unit was used with different photoactivation protocols (high-continuous mode - HCM, 1400 mW/cm2 for 20 seconds; low-continuous mode - LCM , 700 mW/cm2 for 40 seconds; and soft-start mode - SSM, 140 mW/cm2 for 5s followed by 39 seconds for 700 mW/cm2). Twenty specimens were prepared for each composite. The light energy transmission through the composite was calculated (n=10). The bottom/top rate of the same specimen was calculated (n=10). The data were compared by Tukey's test in different tests (light energy transmission through the composite and bottom/top rate). RESULTS: The light energy transmission through the Filtek Z350 XT composite (HCM - 576 mW/cm2, LCM - 238 mW/cm2, SSM - 232 mW/cm2) did not show statistical difference when compared with Filtek P90 composite (HCM - 572 mW/cm2, LCM - 233 mW/cm2, SSM - 230 mW/cm2). The bottom/top rate of the Filtek Z350 XT composite (HCM - 88.98%, LCM - 90.94%, SSM - 89.92%) was statistically higher than that of the Filtek P90 composite (HCM-77.29%, LCM-77.51%, SSM- 77.79%). CONCLUSION: Light energy transmission through the composite was not influenced by the use of different dental composite restoratives. However, the bottom/top rate of the composites was influenced by the use of different dental composite restoratives. CLINICAL SIGNIFICANCE: Insufficiently polymerized composite resin may present a large number of problems. For this reason, dental composite resins should have the similar deep surface polymerization as the top surface in dental restorations.

Comparison of microleakage in human and bovine substrates using confocal microscopy.

Microleakage in human and bovine teeth was compared. Cavities were prepared on the buccal surface in 20 human and 20 bovine teeth (3 mm x 2 mm in depth). The teeth were divided into 4 groups (n = 10) according to the substrate and adhesive (CLEARFIL SE Bond-CF or Scotchbond 1-SB1). Resin composite (Wave) was applied in two increments, each cured for 30 sec. Specimens were stored in 100% relative humidity at 37 degrees C for 24 hr and submitted to 1,000 thermal cycles, followed by immersion in 0.6% aqueous rhodamine for 48 hr. Specimens were rinsed and sectioned at the center. Microleakage length was measured and the score recorded using the following scale: 0-none, 1-up to enamel junction, 2-up to pulp wall, 3-in pulp wall, 4-beneath pulp wall. Percentage of leakage penetration into the cavity was submitted to an ANOVA and Tukey's test (5%) and the scores submitted to the Kruskal-Wallis and Dunn's multiple comparison tests (5%). When bovine teeth were used, SB1 (87.76%) showed a statistically higher penetration mean than CF (66.22%). When human teeth were used, no difference was found between SB1 (47.35%) and CF (36.01%). When scores were analyzed, SB1 showed no difference to CF. The differences found should be taken into consideration when evaluating adhesive microleakage using bovine teeth.

Microhardness of bovine enamel after different fluoride application protocols.

The aim of the present study was to evaluate microhardness, mineral recovery and the enamel surface after the application of topical fluoride to artificial dental caries. Twenty-five bovine enamel blocks were prepared for artificial caries-like lesions and randomly divided into five groups (n=5): untreated (C control), 1.23% acidulated phosphate fluoride gel (APG), 2% neutral fluoride gel (NFG), 1.23% acidulated fluoride mousse (AFM) and fluoride varnish (5% Duraphat, DFV). Knoop microhardness (KHN) was evaluated after 7 and 14 days of treatment as well as 1 week after 28 days of treatment. Electron and confocal microscopy and energy dispersive spectroscopy were performed. KHN data were treated with two-way ANOVA (material×time) and Tukey's test at a 5% significance level. Differences were found among groups over time (p<0.001). Microhardness varied after 7 and 14 days of treatment and remained stable 1 week after 28 days of treatment. Mineral recovery and enamel topography varied among groups, with the fluoride varnish achieving the most uniform topography.

Durability of enamel bonding using two-step self-etch systems on ground and unground enamel.

This study examined the early and long-term microtensile bond strengths (MTBS) and interfacial enamel gap formation (IGW) of two-step self-etch systems to unground and ground enamel. Resin composite (Filtek Z250) buildups were bonded to proximal enamel surfaces (unground, bur-cut or SiC-treated enamel) of third molars after the application of four self-etch adhesives: a mild (Clearfil SE Bond [SE]), two moderate (Optibond Solo Plus Self-Etch Primer [SO] and AdheSE [AD]) and a strong adhesive (Tyrian Self Priming Etchant + One Step Plus [TY]) and two etch-and-rinse adhesive systems (Single Bond [SB] and Scotchbond Multi-Purpose Plus [SBMP]). Ten tooth halves were assigned for each adhesive. After storage in water (24 hours/37 degrees C), the bonded specimens were sectioned into beams (0.9 mm2) and subjected to microTBS (0.5 mm/minute) or interfacial gap width measurement (stereomicroscope at 400x) either immediately (IM) or after 12 months (12M) of water storage. The data were analyzed by three-way repeated measures ANOVA and Tukey's test (alpha=0.05). No gap formation was observed in any experimental condition. The microTBS in the Si-C paper and diamond bur groups were similar and greater than the unground group only for the moderate self-etch systems (SO and AD). No reductions in bond strength values were observed after 12 months of water storage, regardless of the adhesive evaluated.

Effects of phosphoric acid pretreatment and substitution of bonding resin on bonding effectiveness of self-etching systems to enamel.

PURPOSE: To examine the etching efficacy of three self-etching systems to unconditioned enamel and to phosphoric-acid conditioned enamel using scanning electron microscopy (SEM), and to investigate the microtensile bond strength (muTBS) of three self-etching adhesives to unconditioned enamel used according to the manufacturers' instructions, on phosphoric-acid conditioned enamel, and when their different adhesives were replaced with a control resin after etching. MATERIALS AND METHODS: Clearfil SE Bond (CSE), Tyrian SPE/One-Step Plus (TY), and Adper Prompt L-Pop (AD) were employed. Scotchbond Multi-Purpose Plus (SBMP), an etch-and-rinse adhesive, was used as control. For muTBS evaluation, the buccal or lingual mid-coronal enamel of 30 molars was used. In the first group, self-etching adhesives were applied conventionally, according to manufacturers' directions (group C). A second group of specimens was etched with 35% phosphoric acid before application of the self-etching adhesives (group PA), and the third group of specimens was etched with the self-etching adhesives, rinsed, but bonded using a control bonding resin (group CR). Following restoration with Z250, they were sectioned into beams (0.8 mm2), and stressed to failure. Data were subjected to two-way ANOVA and Tukey's test. The etching efficacy of the self-etching adhesives, phosphoric acid, and prior phosphoric acid + SE application was evaluated under SEM. RESULTS: All self-etching adhesives applied as recommended by the manufacturers showed lower muTBS values than those obtained in PA and CR groups, although this difference was only significant for TY and AD. The means of all self-etching adhesives under PA and CR groups were similar to SBMP. The enamel conditioned with self-etching adhesive showed a less distinct pattern. CSE exhibited the mildest etching pattern. All self-etching adhesives applied after phosphoric acid exhibited a more retentive etching pattern. CONCLUSION: The bond strength values of low-pH self-etching adhesives can be improved by the adjunctive use of phosphoric acid or replacement of the bonding resin.

Does the acidity of self-etching primers affect bond strength and surface morphology of enamel?

PURPOSE: This study examined the ultrastructure and microtensile bond strengths (TBS) of self-etching (with different acidity) and conventional adhesive systems bonded to unground enamel. MATERIALS AND METHODS: Resin composite (Filtek Z250) buildups were bonded to unground enamel surfaces of third molars after adhesive application with the following materials: Clearfil SE Bond (CSE); Optibond Solo Plus Self-Etch (OP); Tyrian Self Priming Etching (TY), and the controls Scotchbond Multi-Purpose Plus (SBMP) and Single Bond (SB). Six teeth were assigned to each material. After storage in waterfor 24 h at 37 degrees C, the bonded specimens were sectioned into beams of approximately 0.8 mm2 and subsequently subjected to microTBS testing at a crosshead speed of 0.5 mm/min. The average values were subjected to one-way ANOVA (alpha = 0.05). The effect of surface conditioning of each material was observed under scanning electron microscopy (SEM). RESULTS: The highest resin-enamel bond strength was observed for SBMP (22.7 +/- 5.2) and SB (26.7 +/- 5.2 MPa). The lowest mean bond strengths were 10.9 +/- 3.2 and 7.8 +/- 1.5 MPa for TY and OP, respectively. CSE showed an intermediate performance (18.7 +/- 4.6 MPa). An overall increase in porosity was evident along the entire enamel surface treated with the self-etching primers; however, no selective demineralization similar to that with 35% phosphoric acid was observed. CONCLUSION: The highest bond strength means and the more retentive etching pattern were observed for the two-step etch-and-rinse adhesives. Among the self-etching systems studied, Clearfil SE Bond should be preferred.

Morphological characterization of the tooth/adhesive interface.

The purpose of this study was to assess the morphological characteristics of the tooth/adhesive interface using different adhesive systems in MOD restorations under scanning electron microscopy (SEM). The tested hypothesis was that the morphology of the bonding interface would vary in different areas of MOD restorations for the three adhesive systems. MOD cavities were prepared in 12 sound extracted human third molars and restored with Filtek Z250 composite resin and one of the following adhesive systems: Experimental ABF (n=4), Clearfil SE Bond (n=4) self-etching primers and Single Bond etch-and-rinse adhesive system (n=4). After 24-h storage in distilled water at 37 degrees C, teeth were sectioned and prepared for SEM. The interfacial morphology varied depending on the adhesive system and also on the evaluated area. The null hypothesis was accepted because the morphology of the tooth/adhesive interface reflected the characteristics of both the dental substrate and the adhesive systems.

Influence of Surface Treatments and Adhesive Systems on Lithium Disilicate Microshear Bond Strength.

The purpose of this study was to evaluate the microshear bond strength of ceramic prosthetic structures reinforced by lithium disilicate cemented with resin cement under conditions of different surface treatments and adhesive systems. Seventy-two rectangular blocks of lithium disilicate (6.5 mm long × 5 mm wide × 1 mm thick) were fabricated, air abraded with 50-µm Al2O3 particles and divided into six groups (n=12) depending on the surface pretreatments. The groups were as follows: 10HF/S/SBM: 10% hydrofluoric acid etched for 20 s (10HF) + silane (S) + Adper Scotchbond Multi-Purpose (SBM); 10HF/S/SB: 10HF + S + Single Bond Universal (SB); 10HF/SBM; 10HF/SB; S/SBM and S/SB. Two 1-mm-long plastic tubes were placed on the specimens, filled with RelyX ARC resin cement and cured for 20 s per tube. The plastic tube was removed, and the microshear bond strength was tested. Data were submitted to analysis of variance and Tukey's tests (α=0.05). Fractured specimens were observed under optical microscopy. For both adhesives, the bond strengths (MPa) of groups treated with acid-etching and silane (10HF/S/SB: 24.82, 10HF/S/SBM: 24.90) were higher (p<0.001) than those of groups treated with acid-etching (10HF/SB: 16.47, 10HF/SBM: 19.94) only or only silane (S/SB: 18.42, S/SBM: 13.24). All groups showed a predominance of failure adhesive. The silanization should be a clinical step in cementing ceramic structures reinforced by lithium disilicate, even with the application of universal adhesive that contains silane in its formulation.

Push-out bond strength of different translucent fiber posts cemented with self-adhesive resin cement.

PURPOSE: Evaluate the bond strength of different translucent fiber posts in the cervical, middle, and apical root thirds cemented with self-adhesive resin cement. MATERIALS AND METHODS: Sixty single-rooted teeth were randomly divided into five groups according to the fiber post used: Reforpost (opaque [control]), exacto, white post, radix, and Macro-Lock Illusion X-RO. The roots were subjected to chemomechanical preparation and cemented with self-adhesive resin cement. The teeth were sectioned into slices of the different root thirds and tested for bond strength (push-out). Two-way analysis of variance and Bonferroni test were used to verify statistical differences between groups (P < 0.05). RESULTS: No significant difference between the root thirds was detected (P > 0.05). However, the performance of the posts demonstrated a significant difference (P < 0.05). RDX had a lower performance in the apical third (P < 0.05). The other fiber posts had the same performance irrespective of the root third evaluated. The predominant failure pattern was adhesive between resin cement and root dentin. CONCLUSION: In general, the different translucent fiber posts showed the same performance. Yet, translucent fiber posts did not show superior bond strength compared with the opaque fiber post in any of the root thirds evaluated.

Influence of 10% sodium ascorbate gel application time on composite bond strength to bleached enamel.

Objective To analyze bond strength to bleached enamel following application of 10% sodium ascorbate gel. Material and methods Forty third molars were allocated into five groups (n = 8): GP - unbleached specimens restored with composite resin; GN - specimens restored immediately after bleaching; and G15; G30 and G60 (test groups) - bleached specimens treated with 10% sodium ascorbate gel for 15, 30 and 60 min before restoration. The teeth were sectioned and the buccal and lingual faces were restored. After storage in distilled water (37 °C/24 h), sticks of ±0.8 mm2 were tested in tensile (0.5 mm/min). Fractures were observed and classified. Data (in MPa) were analyzed with one-way ANOVA and Tukey tests (α = 0.05). Results No differences were found among GP (26 ± 6.0), G15 (23 ± 7.3), G30 (25 ± 6.1) and G60 (25 ± 5.1), with GN (15 ± 5.5) showing the lowest bond strength (p < 0.0001). Conclusion The application of 10% sodium ascorbate gel for 15 min after bleaching with 37.5% hydrogen peroxide restored the bonding to enamel.

Microleakage of four simplified adhesive systems under thermal and mechanical stresses.

PURPOSE: To evaluate microleakage at the dentin margins of Class II resin-based composite restorations using four simplified adhesive systems: Etch & Prime 3.0, Prime & Bond NT, Clearfil Liner Bond 2V and Clearfil SE Bond, upon thermal and mechanical stresses. MATERIALS AND METHODS: Forty slot preparations (5mm x 3mm x 1.5mm) were cut in sound human molars with gingival margins below the cement/enamel junction. All adhesive systems were applied strictly according to manufacturers' instructions. Cavities were restored using Clearfil AP-X composite resin. After finishing and polishing, teeth were submitted to thermal (x700, 5-55 degrees C, 60-second dwell time) and consecutively mechanical cycling (100,000 cycle; 8 Kgf load). Specimens were coated with nail polish, immersed in silver nitrate for 2 hours and sectioned longitudinally with a diamond disc. The extent of leakage was ranked using a 0-4 scale. RESULTS: Statistical analysis was performed using Kruskal-Wallis test. Minimal leakage occurred with Clearfil SE Bond. There was a statistically significant difference (P<0.01) between this system and Clearfil Liner Bond 2V, although the latter also showed low values of dye penetration. No statistically significant difference was found between Etch & Prime 3.0 and Prime & Bond NT. Both showed statistically greater leakage than the two other systems (P<0.01).

The effect of long-term storage on the microleakage of composite resin restorations: qualitative and quantitative evaluation.

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 influence of air temperature for solvent evaporation on bonding of self-etch adhesives to dentin.

OBJECTIVE: This study evaluated the effect of air temperature (warm or cold) for solvent evaporation on bonding and nanoleakage of self-etching adhesives to dentin. MATERIALS AND METHODS: The adhesives Clearfil 3S Bond [S3], OptiBond All-In-One [OB], Adper SE Plus [AD], and Silorane adhesive [SI] were applied on dentin surfaces, and a warm (60 ± 2°C) or cold air (20 ± 1°C) was applied and light-cured. After water storage (24 h), the teeth were sectioned into sticks (0.8 mm(2)) and tested in tensile. Then, they were immersed in a 50% solution of silver nitrate, photo-developed and the nanoleakage observed in a scanning electron microscope. The bond strength and nanoleakage pattern were analyzed by two-way analysis of variance and post hoc Tukey's test (α =0.05). RESULTS: Higher bond strength and lower silver nitrate uptake were observed for the adhesives under warm condition (P < 0.05). AD and SI showed better adhesive results than S3 and OB (P < 0.05). CONCLUSION: The use of a warm air was useful to improve the bonding and diminish the nanoleakage of adhesive systems to dentin.

Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires.

OBJECTIVE: To compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire. MATERIAL AND METHODS: Abzil Kirium Capelozza (Pattern I) and Easy Clip (Roth prescription) incisor brackets were used. An elastomeric ligature or a 0.10-in ligating wire was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten observations were carried out for each bracket-archwire angulation combination. Brackets were mounted in a special appliance, positioned at 90 degrees in relation to the wire and tested in two angulations. Frictional test was performed in a Universal Testing Machine at 5 mm/min and 10 mm of displacement. The means (MPa) were submitted to ANOVA and Tukey's test set at 5% of significance. The surfaces of wires and brackets were observed at SEM. RESULTS: Steel-tied brackets (16.48 ± 8.31) showed higher means of frictional resistance than elastomeric-tied brackets (4.29 ± 2.16 ) and self-ligating brackets (1.66 ± 1.57) (P < 0.05), which also differed from each other (P < 0.05). As for the type of wire, 0.019 x 0.025-in steel wire (5.67 ± 3.97) showed lower means (P < 0.05) than 0.16-in NiTi wire (8.26 ± 10.92) and 0.016 x 0.021-in NiTi wire (8.51 ± 7.95), which did not differ from each other (P > 0.05). No statistical differences (P > 0.05) were found between zero (7.76 ± 8.46) and five-degree (7.19 ± 7.93) angulations. CONCLUSIONS: Friction was influenced not only by the type of bracket, but also by the ligating systems. Different morphological aspects were observed for the brackets and wires studied.

Reliability of ICDAS to Detect Occlusal Caries among Master's Degree students of Dentistry / Confiabilidade do ICDAS para Detectar Cárie Oclusal Entre Mestrandos de Odontologia

The objective of this study was to investigate the reproducibility of the International System for the Detection and Evaluation of Caries (ICDAS) for the diagnosis of caries by students of the Master's Degree in Dentistry (n = 25). The occlusal surfaces of human third molars (n = 14) were evaluated by twenty-five (n = 25) students using the ICDAS index and later a questionnaire was applied on demographic and professional context data. The dental crowns were sectioned in mesial to distal direction to obtain slices of 1mm in thickness which were observed in a stereomicroscope (40X) to identify the greatest extension of caries lesion. Data were analyzed by the Chi-Square, Fisher's Exact and Spearman's Correlation Coefficient at a significance level of 5%. There was an influence in the diagnosis of caries among students and teeth, where the majority of those who declared themselves to be safe missed the diagnosis. There was variability between the diagnosis and the proposed treatment for caries, with a better diagnosis for tooth VII and less for X; greater fit for treatment of teeth XIII, XIV and lower for IV, VI. The histological cut showed that the teeth were more affected by caries than the ICDAS. It was concluded that the ICDAS reproducibility was partially satisfactory when the occlusal surface was evaluated by the master's degree students. (AU).

Este trabalho teve o objetivo de investigar a reprodutibilidade do Sistema Internacional de Detecção e Avaliação de Cárie (ICDAS) para o diagnóstico da cárie, por estudantes de curso de Mestrado em Odontologia (n=25). As superfícies oclusais de terceiros molares humanos (n=14) foram avaliadas por vinte e cinco (n=25) estudantes, utilizando o índice ICDAS, e posteriormente foi aplicado questionário sobre dados demográficos e de contexto profissional. As coroas dentárias foram seccionadas no sentido mésio distal para obter fatias de 1 mm de espessura, que foram observadas em estereomicroscópio (40X) para identificar a maior extensão da lesão de cárie. Os dados foram analisados pelos Testes Qui-Quadrado, Exato de Fisher e Coeficiente de Correlação de Spearman, em nível de significância de 5%. Houve influência do grau de instrução dos estudantes no diagnóstico da cárie em relação ao dente avaliado e a maioria que se declarou segura errou o diagnóstico. Houve variabilidade entre o diagnóstico e o tratamento proposto para a cárie, com maior acerto para diagnóstico do dente VII e menor para o X; maior acerto para tratamento dos dentes XIII, XIV e menor para IV, VI. O corte histológico mostrou que os dentes estavam mais comprometidos pela cárie que o ICDAS. Concluiu-se que a reprodutibilidade do ICDAS foi satisfatória quando a superfície oclusal foi avaliada pelos mestrandos. (AU).