Factors associated with Brazilian adolescents' satisfaction with oral health.

OBJECTIVE: To identify the sociodemographic, clinical and self-reported indicators of oral health associated with Brazilian adolescents' satisfaction with oral health. METHODS: Secondary data were used following the examination of 4,231 adolescents, aged 15 to 19 years, participating in a national oral health survey (SBBrasil 2010). The independent variables were grouped into demographics, predisposition/facilitation, oral health conditions and perceived dental treatment need. Satisfaction with oral health was considered the dependent variable. Ordinal logistic (multiple) regression models tested the variables in sequence (hierarchical), as per the conceptual model, assuming p≤0.05 as the criterion for remaining in the model (Wald test). Adjustment of the model was evaluated with the Akaike information criterion (AIC) and -2 Log L. RESULTS: Participants with perceived treatment need (OR=2.36, 95% CI = 2.14-2.61), toothache (OR=1.18, 1.10-1.28), presence of oral impacts on daily performance (OIDP) (OR= 1.55, 1.44-1.68), severe and very severe dental aesthetic index (DAI) (OR=1.17, 1.08-1.27), were female (OR=1.16, 1.10-1.23), were of black/brown ethnicity (OR=1.10, 1.04-1.17), and had caries in anterior (OR=1.20, 1.08-1.32) and posterior teeth (OR=1.22, 1.13-1.32) presented lower satisfaction with oral health. CONCLUSION: Satisfaction with oral health in Brazilian adolescents is linked to a multidimensional structure of factors that include demographic aspects, such as gender and ethnic group, self-perception aspects, such as perceived treatment need and oral health impact on daily activities, and clinical aspects, such as the presence of toothache, severe malocclusion and caries in anterior and posterior teeth.

Changes in condylar volume and joint spaces after orthognathic surgery.

The aim of this study was to evaluate the changes in condylar volume and joint spaces occurring in patients undergoing bimaxillary orthognathic surgery for the treatment of class II deformities, by means of cone beam computed tomography (CBCT). Initial and follow-up (at least 6 months) CBCT examinations of 114 condyles (57 patients) were studied retrospectively. Linear measurements of the joint space and volumetric analysis of changes in condylar volume were performed using Dolphin 3D Imaging in association with ITK-SNAP 3.0.0 segmentation software. The paired t-test and Pearson correlation coefficient were applied, and a descriptive analysis was performed. Mean condyle volumes were significantly smaller at follow-up (P=0.0125). There were significant reductions in superior and medial joint spaces in the follow-up examinations (both P<0.05). Positive correlations were found when comparing the mean changes in anterior, superior, and posterior space values between the right and left sides. No significant correlation was observed between changes in volume and joint spaces. In conclusion, there was a reduction in mean condylar volume after orthognathic surgery in class II patients. However, changes in volume for each condyle may be variable. Such changes in condylar volume may occur independently on the left and right sides, and do not correlate with changes in joint spaces.

Effect of Restorative System and Thermal Cycling on the Tooth-Restoration Interface - OCT Evaluation.

The present study evaluated the tooth/noncarious cervical lesion restoration interface when using different adhesive systems and resin composites, submitted to thermal cycling (TC), using optical coherence tomography (OCT). Noncarious cervical lesion (NCCL) preparations (0.7 mm depth × 2 mm diameter) were performed on 60 human third molars and randomly divided into six groups, according to the adhesive system and resin composite used: group 1 = Adper Single Bond 2 (SB2) + Aelite LS Posterior (AP); group 2 = SB2 + Venus Diamond (VD); group = SB2 + Filtek Z250XT (Z250); group 4 = Clearfil SE Bond (CSE) + AP; group 5 = CSE + VD; group 6 = CSE + Z250. Selective enamel etching was performed for 30 seconds on groups 4, 5, and 6, while groups 1, 2, and 3 were etched for 30 seconds in enamel and 15 seconds in dentin. All groups were evaluated using OCT before and after TC (n=10). Images were analyzed using Image J software; enamel and dentin margins were separately evaluated. Data from OCT were submitted to PROC MIXED for repeated measurements and Tukey Kramer test (α = 0.05). No marginal gaps were observed in etched enamel, either before or after TC, for all adhesive and resin composite systems. A significant interaction was found between adhesive system and TC for the dentin groups; after TC, restorations with CSE showed smaller gaps at the dentin/restoration interface compared with SB2 for all resin composites. Increased gap percentages were noticed after TC compared with the gaps before TC for all groups. In conclusion, TC affected marginal integrity only in dentin margins, whereas etched enamel margins remained stable even after TC. Dentin margins restored with CSE adhesive system showed better marginal adaptation than those restored with SB2. Resin composites did not influence marginal integrity of NCCL restorations.

Effect of Toothpaste Application Prior to Dental Bleaching on Whitening Effectiveness and Enamel Properties.

OBJECTIVE: The purpose of this study was to investigate the effects on the enamel properties and effectiveness of bleaching using 35% hydrogen peroxide (HP) when applying toothpastes with different active agents prior to dental bleaching. METHODS: Seventy enamel blocks (4 × 4 × 2 mm) were submitted to in vitro treatment protocols in a tooth-brushing machine (n=10): with distilled water and exposure to placebo gel (negative control [NC]) or HP bleaching (positive control [PC]); and brushing with differing toothpastes prior to HP bleaching, including potassium nitrate toothpaste (PN) containing NaF, conventional sodium monofluorophosphate toothpaste (FT), arginine-based toothpastes (PA and SAN), or a toothpaste containing bioactive glass (NM). Color changes were determined using the CIE L*a*b* system (ΔE, ΔL, Δa, and Δb), and a roughness (Ra) analysis was performed before and after treatments. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were analyzed after treatment. Data were analyzed with repeated measures ANOVA for Ra, one-way ANOVA (SMH, ΔE, ΔL, Δa, and Δb), split-plot ANOVA (CSMH), and Tukey post hoc test (α<0.05). The relationship between the physical surface properties and color properties was evaluated using a multivariate Canonical correlation analysis. RESULTS: Color changes were statistically similar in the bleached groups. After treatments, SMH and CSMH decreased in PC. SMH increased significantly in the toothpaste groups vs the negative and positive control (NM > PA = SAN > all other groups) or decreased HP effects (CSMH). Ra increased in all bleached groups, with the exception of NM, which did not differ from the NC. The variation in the color variables (ΔL, Δa, and Δb) explained 21% of the variation in the physical surface variables (Ra and SMH). CONCLUSION: The application of toothpaste prior to dental bleaching did not interfere with the effectiveness of treatment. The bioactive glass based toothpaste protected the enamel against the deleterious effects of dental bleaching.

Alcohol intake may impair bone density and new cementum formation after enamel matrix derivative treatment: histometric study in rats.

BACKGROUND AND OBJECTIVE: Alcohol intake may interfere with bone metabolism; however, there is a lack of information about the outcomes of regenerative approaches in the presence of alcohol intake. Enamel matrix derivative (EMD) has been used in periodontal regenerative procedures resulting in improvement of clinical parameters. Thus, the aim of this histomorphometric study is to evaluate the healing of periodontal defects after treatment with EMD under the influence of alcohol intake. MATERIAL AND METHODS: Twenty Wistar rats were randomly assigned to two groups: G1 = alcohol intake (n = 10) and G2 = non-exposed to alcohol intake (n = 10). Thirty days after initiation of alcohol intake, fenestration defects were created at the buccal aspect of the first mandibular molar of all animals from both groups. After the surgeries, the defects of each animal were randomly assigned to two subgroups: non-treated control and treated with EMD. The animals were killed 21 d later. RESULTS: G1 showed less defect fill for non-treated controls. Bone density (BD) and new cementum formation were lower for G1 when compared to G2, for EMD-treated and non-treated sites. EMD treatment resulted in greater BD and new cementum formation in both groups and defect fill was not significantly different between groups in the EMD-treated sites. The number of tartrate-resistant acid phosphatase-positive osteoclasts was significantly higher in G1 when compared to G2 and in EMD-treated sites of both groups. CONCLUSION: Alcohol intake may produce a significant detrimental effect on BD and new cementum formation, even in sites treated with EMD. A limited positive effect may be expected after EMD treatment under this condition.

Digital radiographs displayed on different devices: effect on the detection of vertical root fractures.

AIM: To evaluate whether the type of display device affects the detection of vertical root fractures (VRFs) on digital radiographs in unfilled canals and canals with fibreglass posts. METHODOLOGY: Forty single-rooted human teeth were decoronated, and the root canals were prepared. The teeth were divided into 2 groups: controls (20 teeth) and with VRF (20 teeth). The VRFs were induced using an universal testing machine. Periapical radiographs of all teeth, with canal unfilled or with a fibreglass post, were obtained using the parallel technique in 3 directions (ortho-, mesio- and distoradial) on storage phosphor plates (VistaScan®). All images were evaluated and re-evaluated after 30 days by 3 examiners on a 5-point scale using 4 different devices (notebook display with full high definition resolution, desktop display with a standard resolution, 8-inch Android(™) tablet with high definition resolution and a 9.7-inch iPad® tablet with Retina resolution). Areas under ROC curves, sensitivity, specificity and accuracy values were compared by anova. RESULTS: The weighted kappa values for intra- and interobserver reproducibility were 0.55-0.88 and 0.31-0.65, respectively. There was a significant difference (P < 0.05) in relation to the area under the ROC curve, specificity and sensitivity when unfilled canals were compared with canals with a fibreglass post; however, no difference was observed for the different devices studied. CONCLUSIONS: The type of display device did not affect the detection of VRFs. Thus, the detection of VRFs can be performed using different screen sizes and resolutions.

Influence of the artefact reduction algorithm of Picasso Trio CBCT system on the diagnosis of vertical root fractures in teeth with metal posts.

OBJECTIVES: To assess the influence of the artefact reduction algorithm (AR) available on the Picasso Trio 3D(®) imaging system (Vatech, Hwaseong, Republic of Korea) on image quality [greyscale values, contrast-to-noise ratio (CNR) and artefact formation] and diagnosis of vertical root fractures (VRFs) in the teeth with intracanal metal posts. METHODS: 30 uniradicular teeth had their crowns removed and their roots endodontically treated to receive intracanal metal posts. In 20 teeth, both complete (n = 10) and incomplete (n = 10) VRFs were created. Each tooth was scanned twice, with and without AR activation. The mean and variation of greyscale values, as well as CNR, were calculated for all images. Subsequently, an evaluator compared the amount of artefact (cupping, white streaks and dark bands) in all images. Five evaluators rated for VRF presence using a five-point scale. RESULTS: Mean greyscale values and CNR were significantly decreased in images acquired with the AR. The usage of the algorithm promoted an overall reduction of image artefacts. Regarding the diagnosis of complete and incomplete VRFs, the use of the AR had an overall negative impact on specificity and accuracy. CONCLUSIONS: While indeed reducing artefact formation, the use of the AR, instead of improving the impact on the diagnosis of VRFs in teeth with intracanal metal posts, had a negative impact on the diagnosis.

Impact of root fillings and posts on the diagnostic ability of three intra-oral digital radiographic systems in detecting vertical root fractures.

AIM: To evaluate (i) the accuracy of three intra-oral digital systems in detecting vertical root fractures (VRFs); and (ii) the influence of different intracanal conditions (without filling, filled with Gutta-percha and metal or fibreglass post). METHODOLOGY: Forty single-rooted human teeth were decoronated and the root canals prepared. VRFs were induced using a universal testing machine on 20 teeth. Radiographic images were obtained using the paralleling technique with three different horizontal angulations on conventional E/F film, two storage phosphor plates (Digora Optime and VistaScan) and one sensor system (SnapShot). All teeth were radiographed with all intracanal conditions tested. All images were evaluated by five examiners. After 30 days, 25% of the images were reviewed. Areas under ROC curves, sensitivity, specificity, accuracy, positive predictive and negative predictive values were compared by anova. RESULTS: The weighted kappa values for intra- and interobserver reproducibility were 0.48-0.74 and 0.57-0.66, respectively. The sensitivity revealed a significant difference between imaging modalities, with higher values for SnapShot (0.53) and VistaScan (0.46), followed by the film (0.41) and Digora (0.38). The area under the ROC curve for SnapShot (0.82) was greater than for the other systems in the teeth with a fibreglass post (VistaScan: 0.70; Digora: 0.64; film: 0.60). CONCLUSION: All systems gave a similar performance for detecting VRFs; all gave a good performance in the absence of intracanal materials, but performed less well in the presence of a metal post or Gutta-percha. In teeth with a fibreglass post, digital systems with higher resolution should be used.

Influence of exposure factors on the variability of CBCT voxel values: a phantom study.

OBJECTIVES: To assess the influence of milliamperage and kilovolt peak (kVp) on the variability of cone beam CT (CBCT) voxel values. METHODS: CBCT scans were obtained from radiographic phantoms in varying concentrations of dipotassium hydrogen phosphate solutions (200-1200 mg ml(-1)) under different protocols of milliamperage and kVp. In addition, scans were performed with and without a dental implant and exo-mass. The variability of CBCT voxel values was measured on each scan, and factorial analysis of variance and the post hoc Tukey test were performed (α = 0.05). Linear regression was performed to assess the relationship between voxel value variability and dipotassium hydrogen phosphate concentration. RESULTS: milliamperage and the presence of a dental implant did not produce significant interference (p = 0.28 and 0.87, respectively) in voxel value variability. Scans at the highest kVp value presented a significant reduction (p ≤ 0.0001) in voxel value variability when only exo-mass was not present. Voxel value variability was not influenced by exo-mass in scans at the highest levels of milliamperage and kVp. The presence of exo-mass produced a significant reduction (p ≤ 0.0001) in voxel value variability in most of the scans. Higher concentrations yielded greater variations in voxel values in all scans, except for those operating at the highest levels of mAs and kVp. CONCLUSIONS: mAs did not influence the variability of CBCT voxel values; higher kVp reduced such variability when only the object was smaller than the field of view.

Influence of an intermediary base on the microleakage of simulated class II composite resin restorations.

The aim of this in vitro study was to qualitatively and quantitatively evaluate the microleakage of Class II cavities restored with a methacrylate-based composite (Filtek Z250, 3M ESPE) or silorane-based composite (Filtek LS, 3M ESPE), varying the application of an intermediary base, using a low-viscosity composite resin (Filtek Z350 Flow, 3M ESPE) or resin-modified glass ionomer cement (RMGIC) (Vitrebond, 3M ESPE) and no intermediary base (control groups). Sixty cavities were prepared on the proximal surfaces of bovine teeth and were randomly divided according to the experimental groups (n=10). Following the restorative procedures and thermocycling, the samples were immersed in methylene blue for two hours. The qualitative evaluation was made using a stereomicroscope, whereby two observers analyzed the infiltration level of the dye within the tooth/filling. Microleakage scores among the groups were compared using the Kruskal-Wallis test followed by the Mann-Whitney test (p≤0.05). The samples were then ground and the powder was prepared for quantitative analysis in an absorbance spectrophotometer. The results were statistically analyzed by analysis of variance and the Tukey test (p≤0.05). Results from the quantitative analysis showed that LS presented higher values of microleakage than did Z250. There was a significant difference between both composites concerning the intermediary materials, with the lowest values obtained using RMGIC as an intermediary base. Results from the qualitative analysis showed that there were no statistically significant differences between composites; however, there were significant differences for both composites concerning the intermediary materials, with the lowest values obtained using RMGIC as an intermediary. It is possible to conclude that using RMGIC as an intermediary base provided lower microleakage, indicating better sealing of the tooth-restoration interface.

Influence of chemical degradation on the surface properties of nano restorative materials.

OBJECTIVES: The aim of this in vitro study was to investigate the effect of chemical degradation on the surface roughness (Ra) and hardness (Knoop hardness number [KHN]) of nano restorative materials. METHODS: Disc-shaped specimens (5-mm diameter; 2-mm thick) of Filtek Z350 and TPH Spectrum composites and the Vitremer and Ketac Nano light-curing glass ionomer cements were prepared according to the manufacturers' instructions. After 24 hours, polishing procedures were performed and initial measurements of Ra and KHN were taken. The specimens were divided into 12 groups (n=10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola. After 30 days of storage, the specimens were reevaluated for Ra and KHN. The pH values of the storage media were measured weekly. Data were tested for significant differences by repeated-measures three-way analysis of variance and Tukey tests (p<0.05). RESULTS: Composites were found to present lower roughness values and higher hardness values than the ionomeric materials under all storage conditions. After degradation, the KHN of all experimental samples decreased significantly, while the Ra of the ionomeric materials increased, depending on the media, with a markedly negative impact of Coca-Cola and orange juice. There was no difference among the storage media for Filtek Z350 with regard to the KHN values. Nanofillers did not show any influence on the roughness and hardness of resin-modified glass ionomer cements and resin composites concerning their degradation resistance.

Variations in caries diagnoses and treatment recommendations and their impacts on the costs of oral health care.

OBJECTIVE: To evaluate the reproducibility of caries detection and treatment planning among public health dentists and estimate the possible impact of their decisions on financial costs. RESEARCH DESIGN AND SETTINGS: Thirty nine dentists working in the public health service of Piracicaba, São Paulo, Brazil made a combined visual-radiographic caries examination of 40 occlusal surfaces of extracted permanent teeth mounted on two dental mannequins and proposed treatment plans for each tooth. Histological validation then evaluated the diagnoses validity and the suitability of the treatment plans. OUTCOME MEASURES: Inter-examiner agreement was calculated by Cohen's Kappa statistics. The sensitivity and specificity of caries detection and treatment decision were calculated. The costs of dental treatment plans for public health system were calculated from a Brazilian public health service fee scale. RESULTS: Inter-examiner agreement for caries detection was moderate (kappa = 0.42) while for treatment decisions it was fair (kappa = 0.29). The sensitivity and specificity were 0.69 and 0.65 for caries detection and 0.56 and 0.65 for treatment decision respectively. Dentists overestimated the presence and depth of carious lesions and there was a tendency to treat enamel lesions using invasive therapeutic procedures. Mean treatment cost across the two cases was 32US$ (range 9-65) while the histologically validated cost was 23US$. CONCLUSION: The variability in caries detection and treatment decision negatively affected the cost of the dental treatment.

Influence of the curing mode on fluoride ion release of self-adhesive resin luting cements in water or during pH-cycling regimen.

This study evaluated the effects of curing modes and storage conditions on fluoride release of resin cements. In phase 1, the cumulative fluoride release rate from samples of the resin cements (Panavia F 2.0, RelyX Unicem, MaxCem, and BisCem) was quantified after 15 days storage in water (n=4). In phase 2, the fluoride release profiles from the same materials were analyzed during pH cycling (n=4). In this second phase, fluoride was measured at specific times (one, two, three, five, eight, and 15 days). Disk-shaped specimens were prepared (10 mm × 0.5 mm), and the materials were either light activated or allowed to autopolymerize. For both phases, the fluoride release was measured using a fluoride ion-specific electrode. The fluoride release in water was not affected by the curing mode of RelyX Unicem and Maxcem resin cements. Panavia F. 2.0 and BisCem resin cements, either light cured or autopolymerized modes, released higher amounts of fluoride in water than the other self-adhesive cements. In phase 2, the concentration of fluoride released decreased from the first day of pH cycling until the 15th day for all resin cements, for both curing modes, regardless of the storage solution used (demineralizing/remineralizing). The fluoride release rate during pH cycling by Panavia F 2.0 and MaxCem was not affected by the curing mode. The effect of the curing mode on fluoride ion release in water or during pH cycling was product dependent.

Association between oral health-related quality of life and atraumatic restorative treatment in school children: an exploratory study.

BACKGROUND: The present study's objectives were to compare the perceptions of oral health-related quality of life (OHRQoL) among school children presents dental caries with that of caries-free school children, and to evaluate the subjective impact of atraumatic restorative treatment (ART) on the OHRQoL of school children. DESIGN: Exploratory study. SETTING: Public school in Piracicaba, Brazil. MATERIALS AND METHODS: The sample was composed of 30 children in the age-group of 8-10 years. The children were divided into two groups: one with caries and other without caries. The information related to OHRQoL was obtained through the administration of the Child Perceptions Questionnaires (CPQ 8-10 ). To evaluate the impact of ART on the school children's OHRQoL, the CPQ 8-10 was re-administered 4 weeks after the initial treatment. For statistical analysis we used the nonparametric Wilcoxon test for two dependent variables (test and re-test groups) and the nonparametric Mann-Whitney test for independent variables (test and control groups). RESULTS: It was observed that children with dental caries reported larger impact of oral health conditions on the quality of life when compared with the caries-free group, especially in the emotional and social well-being domains ( P ≤.05). After the school children who presented with dental caries received ART, there was improvement in the median scores of CPQ 8-10 in all of the domains, but particularly in the functional limitation domain ( P ≤.05). CONCLUSION: Dental caries exerts a strong influence on the OHRQoL of children. ART was shown to be a simple and painless caries management approach that could improve the OHRQoL of school children.

In-depth polymerization of a self-adhesive dual-cured resin cement.

The aim of this study was to assess Knoop hardness at different depths of a dual-cured self-adhesive resin cement through different thicknesses of Empress Esthetic® ceramic.Flattened bovine dentin was embedded in resin. The cement was inserted into a rubber mold (0.8 x 5 mm) that was placed between two polyvinyl chloride plastic films and placed over the flat dentin and light cured by Elipar Trilight-QTH (800 mW/cm2) or Ultra-Lumelight-emitting diode (LED 5; 1585 mW/cm2) over ceramic disks 1.4 or 2 mm thick. The specimens(n=6) were stored for 24 hours before Knoop hardness (KHN) was measured. The data were submitted to analysis of variance in a factorial split-plot design and Tukey's test (a=0.05).There was significant interaction among the study factors. In the groups cured by the QTHunit, an increase in ceramic thickness resulted in reduced cement hardness values at all depths, with the highest values always being found in the center (1.4 mm, 58.1; 2 mm, 50.1)and the lowest values at the bottom (1.4 mm,23.8; 2 mm, 20.2). When using the LED unit, the hardness values diminished with increased ceramic thickness only on the top (1.4 mm,51.5; 2 mm, 42.3). In the group with the 1.4-mm-thick disk, the LED curing unit resulted in similar values on the top (51.5) and center(51.9) and lower values on the bottom (24.2).However, when the cement was light cured through the 2-mm disk, the highest hardness value was obtained in the center (51.8), followed by the top (42.3) and bottom (19.9),results similar to those obtained with the QTH curing unit (center > top > bottom). The hardness values of the studied cement at different depths were dependent on the ceramic thickness but not on the light curing units used.

Student self-confidence in coping with uncooperative behaviours in paediatric dentistry.

During paediatric dental treatment, non-collaboration and fearful reactions are frequently observed in the child client. The dentistry student must be prepared to cope with these reactions, particularly considering the importance of the relationship between dentists and patients in the promotion of oral health. The present study aimed to assess undergraduate dentistry students' perceptions of their ability to cope with non-collaboration situations in paediatric dentistry. A Likert-style questionnaire was used to analyse students' self-confidence levels, and proposed solutions to 10 problem situations the students would be likely to encounter were recorded. The questionnaire was administered to two undergraduate dentistry student groups from two different Brazilian Public Faculties, comprising 122 respondents. The self-confidence analysis indicated that it varied according to the extent of the child's reaction and the invasiveness of the procedure. Responses to the open-ended questions were categorised by solution proposed, and the analysis indicated that the most frequent responses were categorised as follows: tranquilising, explanation and restriction. Significant differences were found in tranquilising (with higher values for Faculty 2 than 1, and higher values for female students than male students at Faculty 2) and restriction (with higher values for female students compared with male student at both Faculties). The results and discussion focused on the aspects of training dentistry students' social and behavioural management skills.

Biodegradation and abrasive wear of nano restorative materials.

The purpose of this study was to evaluate the biomechanical degradation of two nanofilled restorative materials (a resin-modified glass ionomer, Ketac N100 and a composite, Filtek Z350), compared with conventional materials (Vitremer and TPH Spectrum). Twenty specimens obtained from each material were divided into two storage groups (n=10): relative humidity (control) and Streptococcus mutans biofilm (biodegradation). After 7 days of storage, roughness values (Ra) and micrographs by scanning electron microscopy (SEM) were obtained. In a second experimental phase, the specimens previously subjected to biodegradation were fixed to the tooth-brushing device and abraded via toothbrushes, using dentifrice slurry (mechanical degradation). Next, these specimens were washed, dried, and reassessed by roughness and SEM. The data were submitted to repeated measures three-way analysis of variance (ANOVA) and Tukey tests (p<0.05). There was statistically significant interaction among factors: material, storage (humidity/biofilm), and abrasion (before/after). After biodegradation (S mutans biofilm storage), Ketac N100 presented the highest Ra values. Concerning bio plus mechanical challenge, TPH Spectrum, Ketac N100, and Vitremer presented the undesirable roughening of their surfaces, while the nano composite Filtek Z350 exhibited the best resistance to cumulative challenges proposed. The degraded aspect after biodegradation and the exposure of fillers after mechanical degradation were visualized in micrographs. This study demonstrated that the nanotechnology incorporated in restorative materials, as in composite resin and resin-modified glass ionomer, was important for the superior resistance to biomechanical degradation.

Effect of preheating resin composite and light-curing units on the microleakage of Class II restorations submitted to thermocycling.

This in vitro study evaluated microleakage in Class II cavities restored with dental composite and varying light-curing units and the temperature of the composite when subjected to a thermocycling test. Ninety cavities were prepared on the proximal surfaces of bovine teeth and randomly divided according to the light-curing mode (QTH-420 mW/cm2, LED 2nd generation-1100 mW/cm2, or LED 3rd generation-700 mW/cm2) and temperature of the resin composite (23°C, 54°C and 60°C). Following the restorative procedures and thermocycling, the samples were immersed in methylene blue for 12 hours. The samples were ground and the powder prepared for analysis in an absorbance spectrophotometer. All the results were statistically analyzed using the nonparametric tests of Kruskal-Wallis and Dunn (p ≤ 0.05). The results showed that there was no statistical difference between the light-curing modes at a temperature of 23°C. For 54°C, QTH showed a microleakage mean that was significantly lower than those of the LED groups, and for 60°C, QTH had a microleakage mean significantly lower than that of the LED 2nd generation group. There was no statistical difference between the temperatures of the resin composite when LEDs were used. For QTH, 54°C showed statistically lower microleakage than 23°C. The group preheated to 60°C showed no difference when compared to the group heated to 23°C. Preheating the resin composite (54°C and 60°C) did not improve the microleakage means when high-irradiance LED was used; however, it decreased the microleakage means when a QTH with low irradiance was used.

Efficacy of several digital radiographic imaging systems for laboratory determination of endodontic file length.

AIM: To compare the efficacy of different digital radiographic imaging systems for determining the length of endodontic files. METHODOLOGY: K-type endodontic files were introduced into the canals of 40 extracted human permanent single-rooted teeth and fixed in place at random lengths. The teeth were radiographed using Digora Optime, CygnusRay MPS and CDR Wireless digital imaging systems. Six observers measured every file length in all the images and repeated this procedure in 50% of the image samples, and assigned a score to the level of difficulty found. Analysis of variance for differences between digital systems and Tukey's test were performed. The level of intraobserver agreement was measured by intraclass correlation. The assigned scores were evaluated by Kruskal-Wallis and Dunn's tests. RESULTS: The CDR Wireless values did not differ significantly from the actual lengths and the CygnusRay MPS values. The Digora Optime system was significantly different from the others and overestimated the values (P ≤ 0.05). The Digora Optime was significantly easier to use for taking measurements and the CygnusRay MPS the most difficult (P ≤ 0.05). All digital radiographic imaging systems showed excellent agreement with the Intraclass Correlation Coefficient >0.95. CONCLUSIONS: The three digital radiographic imaging systems were precise. The CDR Wireless system was significantly more accurate in determining endodontic file lengths, and similarly to Digora Optime, was considered the least difficult to use when assessing endodontic file lengths.

Effect of curing mode on bond strength of self-adhesive resin luting cements to dentin.

In this study, the in vitro bond strength of dual-curing resin cements to indirect composite restorations when the cement was either light polymerized or allowed to only autopolymerize was evaluated. Occlusal dentin surfaces of 56 extracted human third molars were flattened to expose coronal dentin. Teeth were assigned to eight groups (n = 7) according to resin cement products and polymerization modes: conventional cement (Panavia F 2.0; Kuraray Medical) and self-adhesive cements [RelyX Unicem (3M ESPE), BisCem (Bisco), and G-Cem (GC Corp.)]. Cements were applied to prepolymerized resin discs (2-mm-thick Sinfony; 3M ESPE), which were subsequently bonded to the prepared dentin surfaces. The restored teeth were either light-polymerized through the overlying composite according to manufacturers' instructions or were allowed to only self-cure. After 24 h, the teeth and restorations were sectioned to obtain multiple bonded beams (1.0 mm(2)) and tested in tension at a crosshead speed of 0.5 mm/min until failure. Data (MPa) were analyzed by two-way ANOVA and Tukey test (alpha = 0.05). Light activation of some cement systems (G-Cem and Panavia F 2.0) increased the bond strength, while the curing mode did not affect the bond strength for some (RelyX Unicem and BisCem). The bond strength in the autopolymerized mode varied among products. In general, the use of self-adhesive resin cements did not provide significantly higher bond strengths than that of a conventional material, and two self-adhesive cements yielded significantly lower bond values (regardless of cure mode) than the other products.