Radiographic evaluation of mandibular third molars: an ex vivo comparative study between multilayer and conventional panoramic radiography.

OBJECTIVES: To compare the multilayer panoramic radiography (MPAN) and conventional panoramic radiography (CPAN) in the evaluation of mandibular third molars using cone-beam computed tomography (CBCT) as a reference. METHODS: CPAN, MPAN, and CBCT scans from 33 dry human mandibles were acquired using the OP300 Maxio unit, totalizing 56 mandibular third molars to be evaluated. Three examiners evaluated each third molar according to their position, depth of impaction in the mandibular ramus, proximity between the dental root apexes and the mandibular canal, and the presence of radiographic signs of proximity to the mandibular canal. In addition, when there was a distance between the root apexes and the mandibular canal, it was measured. As a reference, these same parameters were assessed in the CBCT scans by a fourth examiner. For the statistical analysis, the weighted Kappa, Bland Altman, and Wilcoxon tests were performed (α = 0.05). RESULTS: The agreement between the assessments performed in the panoramic modalities with the CBCT ranged from 66.1% to 100.0% for the categorical variables. Overall, the agreement values of CPAN and MPAN with CBCT were similar. The distances between the dental root apex and the mandibular canal for both CPAN and MPAN were significantly underestimated compared to CBCT (p < 0.05). The intra- and interexaminer agreements of the examiners ranged from poor to almost perfect; in general, the agreements were higher in the evaluation performed in the MPAN than in the CPAN. CONCLUSIONS: The MPAN performs similarly to CPAN for evaluating mandibular third molars and their proximity relationship to the mandibular canal. CLINICAL RELEVANCE: Preoperative evaluation of lower mandibular third molars is usually performed using CPAN. Recently, a new tool, MPAN, was developed, which has not yet been tested for the evaluation of mandibular third molars and showed similar performance to CPAN in the present study. Future studies using MPAN are encouraged to evaluate other diagnostic tasks.

How Does Ambient Light Affect the Image Quality of Phosphor Plate Digital Radiography? A Quantitative Analysis Using Contemporary Digital Radiographic Systems.

The aim of this study is to quantitatively evaluate the influence of the duration of ambient light exposure on the image quality of digital radiographs obtained with contemporary phosphor plate (PSP)-based systems. Radiographs of an aluminum step-wedge were obtained using VistaScan and Express systems at five X-ray exposure times: 0.10, 0.20, 0.32, 0.40, and 0.50 s; the resulting dose-area products were, respectively, 21.93, 43.87, 70.19, 87.75, and 109.6 mGycm2. Before PSP read-out, half of the sensitive surface of the PSP plates was exposed to ambient light for 5, 10, 30, 60, and 90 s. The effect of light exposure on brightness, contrast, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and image saturation was compared using ANOVA with the Tukey test (α = 0.05). Ambient light exposure increased brightness and contrast and reduced CNR and SNR in PSP-based radiographs of contemporary digital systems. At the longest X-ray exposure times, ambient light exposure reduced the dark saturation (mean gray values ≤ 1) observed in Express. In conclusion, the negative effects of ambient light observed on the image quality of PSP-based radiographs are directly proportional to the duration of exposure. Clinicians should be aware of such harmful effects when handling and scanning PSP plates in bright environments.

Effect of tooth bleaching and application of different dentifrices on enamel properties under normal and hyposalivation conditions: an in situ study.

OBJECTIVE: The purpose of this in situ study was to evaluate different dentifrices on enamel after bleaching under normal and hyposalivatory conditions. MATERIALS AND METHODS: Twenty-four participants were assigned of which 12 had normal and 12 had low salivary flow. The study was conducted in 6 in situ experimental phases of 24 h duration: placebo, NaF, SnF2, F/Sn/Chitosan, F/Arginine, and F/Bioactive Glass. The specimens were previously bleached in vitro. Microhardness (SMH), roughness (Ra), and color analyses (CIELAB and ΔE00) were performed at baseline (T1), after bleaching (T2) and after in situ phase (T3). Scanning electron microscopy (SEM) and the elemental levels (wt%) of Ca, P, and Na and the proportion between Ca and P were determined using an energy-dispersive X-ray spectrometer (EDS) in T3. The SMH and Ra were analyzed by mixed models for repeated measures and Tukey Kramer. The color and Na% were analyzed by split-plot ANOVA and Tukey test. The EDS were analyzed by Mann's Whitney nonparametric, Friedman, and Nemenyi tests (p<0.05). RESULTS: The dentifrices placebo and NaF in the low flow presented lower SMH and higher Ra in T3 and lower Ca% compared to the same dentifrices in normal flow. For normal flow, SnF2 resulted in greater SMH. For low flow, SnF2, F/Sn/Chitosan, and F/Bioactive Glass resulted in higher SMH in T3 and did not differ from T1. F/Bioactive Glass showed lower Ra among the dentifrices evaluated for both salivary flows, whereas SnF2 showed the highest. F/Bioactive Glass showed a statistically significant difference from placebo for Ca%, P%, Na%. For ΔE*ab and ΔE00 (T1×T3), no differences were found for the dentifrices and salivary flows. CONCLUSION: The low salivary flow had less capacity for remineralization of bleached enamel compared to normal flow. Overall, the dentifrice with bioactive glass had the best performance in bleached enamel under low and normal salivary flow condition. CLINICAL RELEVANCE: It is recommended to use a bioactive glass-based dentifrice after bleaching to promote tooth enamel recovery for patients with or without impaired salivary flow.

Volumetric evaluation of temporomandibular joints in patients with a chewing-side preference: a CBCT study.

This study evaluated the influence of chewing-side preference on the volume of the mandibular condyle and coronoid process and the dynamic parameters of the temporomandibular joint (TMJ). Cone beam computed tomographic scans of both TMJs of 90 individuals with a chewing-side preference were obtained while the patients were in the closed-mouth and maximum mouth-opening positions (test power ≥ 0.80). The preferred chewing side was identified with a chewing gum test as well as by patient self-reports of preferred side and hemispheric dominance (ie, dominant side of the body). Two trained examiners assessed the volume of the mandibular condyle and coronoid process and the dynamic parameters of the TMJs on both sides. The volumes of the mandibular condyle on the 2 sides were compared using a paired t test (α = 0.05). McNemar and Bowker tests of symmetry (α = 0.05) were used for concordance analyses of the dynamic parameters of the TMJ on the chewing and nonchewing sides. No statistically significant difference was observed in the volume of the mandibular condyle (chewing gum test, P = 0.4548; interview, P = 0.7191; hemispheric dominance, P = 0.3471) or coronoid process (chewing gum test, P = 0.7718; interview, P = 0.8072; hemispheric dominance, P = 0.8301) on the chewing and nonchewing sides, regardless of the method used to identify chewing preference. The preferred chewing side also did not significantly affect the dynamic parameters of the mandibular condyle (P = 0.5538). Chewing-side preference does not influence the volume of the mandibular condyle or coronoid process or the dynamic parameters of the TMJ.

Effect of ammonium acryloyldimethyltaurate copolymer on the physical and chemical properties of bleached dental enamel.

OBJECTIVE: To analyze the effect of bioadhesive polymer, Aristoflex® AVC, on enamel physical and chemical properties. MATERIALS AND METHODS: Bovine enamel blocks were divided into CP 10% with carbopol-Whiteness Perfect® (WP-FGM), CP 10% with Aristoflex (A + CP 10%), CP 10% with carbopol (C + CP 10%), Aristoflex (A), carbopol (C), carbamide peroxide 10% (CP 10%) and control (no treatment). The treatment was performed for 4 h during 14 days. The colour (ΔE, ΔL*, Δa* and Δb*), profilometry (Ra) and surface microhardness (KHN) were performed before and after the bleaching treatment. The concentrations of Ca and P were performed on the 1st, 3rd, 7th and 14th days by inductively coupled plasma optical emission spectrometry for the groups WP, A + CP 10%, C + CP 10%, A, C and CP 10% (control without thickener) and the morphology by scanning electron microscopy. RESULTS: All groups with CP 10%, regardless of polymer, differing statistically to ΔE, ΔL*, Δa* and Δb* compared to control group. The group A + CP 10% maintained low values of roughness and microhardness after bleaching. Higher concentration of Ca and P was found in the 1st day of treatment for the WP group compared to the groups A + CP 10% and C + CP 10%. CONCLUSION: The 10% CP associated with the bioadhesive polymer Aristoflex® AVC was effective on the bleaching treatment without changing the physical properties of the dental enamel. Also, this experimental gel caused less mineral loss than the group CP 10% with carbopol (WP-FGM). CLINICAL RELEVANCE: Because the change of Carbopol by Aristoflex, a bioadhesive polymer, does not interfere with the effectiveness of bleaching treatment, it is a promising agent associated to carbamide to maintain the physical properties of enamel after bleaching.

Morphological Evaluation of the Nasopalatine Canal in Patients With Different Facial Profiles and Ages.

PURPOSE: To evaluate the influence of facial profile and age on the morphology of the nasopalatine canal. MATERIALS AND METHODS: One hundred thirty-two cone-beam computed tomograms were classified according to facial profile-mesofacial, brachyfacial, and dolichofacial-and divided into the following age groups: 21 to 30, 31 to 40, 41 to 50, and 51 to 60 years. Measurements were obtained for openings of the incisive and nasopalatine foramina, alveolar bone thickness, and the full length, most constricted region, and volume of the nasopalatine canal. Intra- and inter-examiner agreements were calculated using the intraclass correlation coefficient. After exploratory and descriptive analysis, data were subjected to 2-way analysis of variance and Tukey test for comparisons between facial profiles and age groups. The significance level was 5% (α = 0.05). RESULTS: Intra- and inter-examiner reproducibilities were excellent for all measurements. Patients older than 50 years presented a significantly larger nasopalatine canal than patients 21 to 30 years old for all facial profiles (P ≤ .05). Linear measurements obtained from the nasopalatine canal showed no significant difference between facial profiles and age groups (P > .05). CONCLUSIONS: The nasopalatine canal was not influenced by facial profile but did exhibit an increased volume with aging, particularly after 50 years of age.

Influence of different thickeners in at-home tooth bleaching: a randomized clinical trial study.

OBJECTIVES: To evaluate the effects of 10% carbamide peroxide (CP) with two different thickeners, carbopol (CPc) and natrosol (CPn), on color variation (CV), tooth sensitivity (TS), and cytotoxicity (CC). METHODS: Seventy subjects were distributed into the CPc or CPn groups (n = 35), in a parallel group, randomized, controlled, single-blind clinical trial. Bleaching gels were used by volunteers for 4 h daily for 2 weeks. Color evaluation was performed using a reflectance spectrophotometer, before bleaching treatment (BT), immediately after the first and second weeks of BT, and 1 week and 1 month after BT ended. TS was evaluated using two pain scales, before, during, and after BT. CC was evaluated using MTT after exposure of MDPC-23 cells to the bleaching gels for 4 h. Epoxy replicas of the subjects teeth were made before and after BT and analyzed using a scanning electronic microscope. The data was analyzed using statistical methods. RESULTS: CV and TS showed similar variation between both bleaching gels (p ≤ 0.05). None of the protocols affected cellular metabolism or the surface morphology of enamel. CONCLUSIONS: Bleaching gels with carbopol and natrosol as thickening agents produced similarly effective tooth bleaching and TS, but did not cause cytotoxicity. CLINICAL RELEVANCE: Natrosol could be an alternative as a thickener used in bleaching gels due to its similar bleaching effect and TS when compared with Carbopol.

Double mandibular canal and triple mental foramina: detection of multiple anatomical variations in a single patient.

Having complete information about a patient's mandibular canal and mental foramen is fundamental to performing safer procedures and avoiding intraoperative and postoperative complications. Cone beam computed tomography (CBCT) produces accurate images for the analysis of maxillomandibular bone structures and is widely used in dentistry. The aim of this study is to report a case of mandibular bifid canal associated with triple mental foramina that was revealed with CBCT images. A 45-year-old woman was referred for a CBCT scan of remaining bone quantity to assist in preoperative implant planning. The patient had reported problems related to anesthesia during extraction of the mandibular right second and third molars. Examination showed bilateral bifurcation of the mandibular canal, from the mandibular foramen to the gonial angle. In addition, exteriorization of the mandibular canal was noticed in 3 regions; that is, there were 3 distinct mental foramina. Clinicians must be aware of these anatomical variations in the mandibular region during dental procedures to avoid complications such as difficulty in obtaining anesthesia or postoperative sensory dysfunction.

Juxta-Apical Radiolucency: Prevalence, Characterization, and Association With the Third Molar Status.

PURPOSE: This study aimed to investigate the prevalence of juxta-apical radiolucency (JAR), assessing its association with third molar status and describing its radiologic features through panoramic radiography. MATERIALS AND METHODS: We evaluated 1,050 radiographs (1,830 third molars) for the presence of JAR. The JAR and control groups were classified according to the third molar's angulation, impaction, and root development. The presence of radiographic signs of proximity between the mandibular canal and third molar and the imaging features of JAR also were recorded. RESULTS: JAR was identified in 116 patients (11%) and 130 third molars (7.1%), being significantly associated with female patients and with the second and third decades of life. There also was an association with teeth with a vertical angulation and complete root formation. Radiographic signs of proximity to the mandibular canal were absent in 66.2% of JAR cases. In most cases, there was lamina dura in the juxta-apical area that appeared to overlap the mandibular canal and to have a cortical outline. CONCLUSIONS: JAR is not a rare imaging finding. Given its possible relationship with nerve injuries and its differential diagnostic possibilities, knowing the characteristics of JAR is important to assist professionals in treatment planning and making the correct diagnosis.

Clinical implications, diagnosis, and treatment of a giant frontoethmoid osteoma.

Osteomas are benign, asymptomatic fibro-osseous tumors that are most commonly observed in the paranasal sinuses and sometimes are found in imaging examinations that were taken for other reasons. Giant osteomas are rarely found in the frontal and ethmoid sinuses but, when they are, they may cause intracranial and orbital complications. The aims of this case report are to describe a frontoethmoid osteoma in a 40-year-old woman, discuss the characteristics of this lesion through cone beam computed tomography (CBCT) imaging, and review the options for treatment. A CBCT examination performed for the purpose of orthodontic diagnosis revealed the presence of a large, well-defined, lobular, hyperdense mass that occupied a sizeable area of the frontal sinus and extended to the ethmoid sinus. The patient did not report any pain. Based on the physical and imaging characteristics of the mass, the location and size of the lesion, and the patient's age, the diagnosis was a giant frontoethmoid osteoma. Due to its enhanced field of view, CBCT may enable earlier diagnosis of lesions that affect the maxillofacial region.

Foreign bodies in the interior of the maxillary sinus: diagnosis by cone beam computed tomography.

To avoid complications, the intimate relation between the maxillary sinus and dental roots deserves attention during surgical procedures. Accidental introduction of foreign bodies, such as dental implants, may irritate the maxillary sinus mucosa, causing sinusitis. Cone beam computed tomography (CBCT) has been proven to be suitable for diagnosis in these cases by providing the exact location of the foreign body. The present article reports 3 cases of foreign bodies inside the maxillary sinus associated with inflammatory processes. Imaging examinations, such as CBCT, are an important tool to assist dentists in diagnosing the presence of foreign bodies in the interior of the maxillary sinus.

Adhesion Evaluation of Dentin Sealing, Micropermeability, and Bond Strength of Current HEMA-free Adhesives to Dentin.

PURPOSE: To evaluate dentin sealing (DS), micropermeability (MP), and dentin bond strength (BS) of HEMA-free adhesives after 24 h and one year of artificial saliva storage. MATERIALS AND METHODS: Two HEMA-free (G-ænial Bond and BeautiBond) and All-Bond 3 (the bottle of resin is HEMA-free) adhesives were tested. Adper Single Bond 2, a HEMA-containing adhesive, served as the control. All adhesives were applied according to the manufacturers' instructions and teeth were prepared for DS (n = 5), MP (n = 5), and BS testing (n = 10). DS under a pulpal pressure of 10 psi was performed at 4 time points (when smear layer was present, after EDTA treatment, after adhesive application, and after 1 year). MP was assessed using pulpal pressure of a 20-cm aqueous dye-solution column and confocal laser scanning microscopy. DS, MP, and BS were performed after 24 h or one-year storage. BS and DS data were statistically analyzed using two-way ANOVA, the Tukey-Kramer test (for BS) and Tukey's post-hoc test (for DS) (a = 0.05). A qualitative MP assessment was performed by comparing the accumulation of yellow dye within the resin-dentin interface. RESULTS: Adper Single Bond 2 and All-Bond 3 completely sealed the dentin at 24 h and one year. G-ænial Bond showed statistically significant DS reduction of approximately 15% after one year. BeautiBond showed no DS reduction after one year. The resin-dentin interface created using Adper Single Bond 2 and GA showed dye accumulation primarily after one year. The mean BS of All-Bond 3 was statistically significantly higher than that of other adhesives, while G-ænial Bond and BeautiBond showed statistically significantly lower mean bond strengths than did Adper Single Bond 2 and All-Bond 3. After one-year storage, the mean BS was statistically significantly lower only for G-ænial Bond. CONCLUSION: DS, MP, and BS were not influenced by the absence of HEMA in the tested adhesives.

Adhesion of multimode adhesives to enamel and dentin after one year of water storage.

OBJECTIVES: This study aimed to evaluate the ultramorphological characteristics of tooth-resin interfaces and the bond strength (BS) of multimode adhesive systems to enamel and dentin. METHODS: Multimode adhesives (Scotchbond Universal (SBU) and All-Bond Universal) were tested in both self-etch and etch-and-rinse modes and compared to control groups (Optibond FL and Clearfil SE Bond (CSB)). Adhesives were applied to human molars and composite blocks were incrementally built up. Teeth were sectioned to obtain specimens for microtensile BS and TEM analysis. Specimens were tested after storage for either 24 h or 1 year. SEM analyses were performed to classify the failure pattern of beam specimens after BS testing. RESULTS: Etching increased the enamel BS of multimode adhesives; however, BS decreased after storage for 1 year. No significant differences in dentin BS were noted between multimode and control in either evaluation period. Storage for 1 year only reduced the dentin BS for SBU in self-etch mode. TEM analysis identified hybridization and interaction zones in dentin and enamel for all adhesives. Silver impregnation was detected on dentin-resin interfaces after storage of specimens for 1 year only with the SBU and CSB. CONCLUSIONS: Storage for 1 year reduced enamel BS when adhesives are applied on etched surface; however, BS of multimode adhesives did not differ from those of the control group. In dentin, no significant difference was noted between the multimode and control group adhesives, regardless of etching mode. CLINICAL RELEVANCE: In general, multimode adhesives showed similar behavior when compared to traditional adhesive techniques. Multimode adhesives are one-step self-etching adhesives that can also be used after enamel/dentin phosphoric acid etching, but each product may work better in specific conditions.

School performance and oral health conditions: analysis of the impact mediated by socio-economic factors.

BACKGROUND: Oral problems can cause strong impact on functional, emotional, and social aspects of children and adolescents, as well as changes in school performance. AIM: To evaluate the associations of subjective perceptions of parents, socio-economic factors, and oral clinical conditions of children with their school performance. DESIGN: A case-control design was used with a sample of 1411 schoolchildren aged 8-10 years from city of Piracicaba, São Paulo, Brazil. Clinical conditions were evaluated using the DMFT and dmft indexes. Socio-economic data were obtained using a questionnaire sent to schoolchildren's parents. School performance was evaluated by the final scores of each schoolchild at the end of the 2011 school year. RESULTS: According to the final logistic regression model, the schoolchildren who had carious lesions and underwent curative dental treatment at the beginning of the academic year presented 1.51 more chance of having low performance compared with schoolchildren who had no caries lesions. In addition, socio-economic and demographic variables were associated with a greater chance of poor school performance. CONCLUSION: Socio-economic factors and presence of caries lesions, even if treated, were risk indicators for poor school performance.

Utility of panoramic radiography for identification of the pubertal growth period.

INTRODUCTION: Our aim in this study was to investigate the association between dental mineralization stages and the periods of the pubertal growth spurt (PGS). METHODS: The sample included panoramic and hand-wrist radiographs from 491 subjects (222 boys, 269 girls) aged 7 to 17 years. Dental development was rated, and skeletal maturation was evaluated. The relevant associations were investigated by analysis of ordinal multinomial logistic regression. RESULTS: The second molar (odds ratio [OR] = 4.34) and the first premolar (OR = 2.45) were the best growth predictors for girls. For boys, the second molar (OR = 6.80), second premolar (OR = 2.41), and canine (OR = 3.21) proved to be the best predictors. Stages D and E of the second molar for girls, and stages E and F for boys, corresponded to the onset of the accelerated growth spurt. Stage F of the second molar for girls and stage G for boys corresponded to the peak of the PGS. At the end of the PGS, most teeth had already attained apical closure. In girls, however, most second molars were found at stage G. CONCLUSIONS: An association exists between the dental mineralization stages and the periods of the PGS, especially for second molars. Panoramic radiographs can be used as the first diagnostic tool to estimate the pubertal growth period.

Bond Strength of Resin Cements to Zirconia Ceramic Using Adhesive Primers.

PURPOSE: To evaluate the influence of adhesive primers on the microshear bond strength of resin cements to zirconia ceramic. MATERIALS AND METHODS: Fifty zirconia plates (12 mm × 5 mm × 1.5 mm thick) of a commercially available zirconium oxide ceramic (ZirCad) were sintered, sandblasted with aluminum oxide particles, and cleaned ultrasonically before bonding. The plates were randomly divided into five groups of 10. Three resin cements were selected (RelyX ARC, Multilink Automix, Clearfil SA Cement self-adhesive resin cement), along with two primers (Metal-Zirconia Primer, Alloy Primer) and one control group. The primers and resin cements were used according to manufacturers' recommendations. The control group comprised the conventional resin cement (RelyX ARC) without adhesive primer. Test cylinders (0.75 mm diameter × 1 mm high) were formed on zirconia surfaces by filling cylindrical Tygon tube molds with resin cement. The specimens were stored in distilled water for 24 hours at 37°C, then tested for shear strength on a Shimadzu EZ Test testing machine at 0.5 mm/min. Bond strength data were analyzed statistically by two-way ANOVA and Dunnett's test (5%). RESULTS: The bond strength means in MPa (± s.d.) were: RelyX ARC: 28.1 (6.6); Multilink Automix: 37.6 (4.5); Multilink Automix + Metal-Zirconia Primer: 55.7 (4.0); Clearfil SA Cement: 46.2 (3.3); and Clearfil SA Cement + Alloy Primer: 47.0 (4.1). CONCLUSION: Metal-Zirconia Primer increased the bond strength of Multilink Automix resin cement to zirconia, but no effect was observed for Alloy Primer using Clearfil SA Cement. RelyX ARC showed the lowest bond strength to zirconia.

Quality of life and socio-dental impact among underprivileged Brazilian adolescents.

PURPOSE: To evaluate the influence of clinical variables, individual and contextual characteristics on the quality of life (QL) of underprivileged adolescents in a municipality in the interior of the State of São Paulo, Brazil. METHODS: An analytical cross-sectional study was conducted in Piracicaba, in 2012, with 1,172 adolescents aged 15-19 years, from 21 state schools and 34 Family Health Units. The dependent variables included the socio-dental impact (OIDP) and quality of life (WHOQOL-bref) indices. The dependent variables were classified as individual (DMFT index, CPI Index, age, sex, income, parents' educational level) and contextual (Social Exclusion Index) variable. The multilevel regression model was estimated by the PROC GLIMMIX ("Generalized Linear Models-Mixed") procedure, considering the individuals' variables as being Level 1 and the contextual variables as being Level 2, and the statistical significance was evaluated at level of significance of 5 %. RESULTS: Girls were found to have the worst QL (p < 0.000) and greatest OIDP (p = 0.000). There was an increase in OIDP (p < 0.001) and diminished QL (p < 0.052) with an increase in the periodontal index. This result is marginally significant since the significance probability is marginally greater than 0.05. In turn, there was an increase in QL (p = 0.000) and reduction in OIDP (p < 0.000) with an increase in the family income. Adolescents who resided in areas of greatest social exclusion (p = 0.031) and with greater OIDP (p < 0.000) presented the worst QL. CONCLUSION: Individual and contextual variables were related to the OIDP and QL in underprivileged Brazilian adolescents.

In situ antimicrobial activity and inhibition of secondary caries of self-etching adhesives containing an antibacterial agent and/or fluoride.

PURPOSE: To evaluate the in situ effect of fluoride and MDPB-containing adhesives on antibacterial activity around restorations in conditions of high caries risk. METHODS: Bovine enamel and dentin blocks were restored with a fluoride-containing (One-up Bond F Plus - OP) or a MDPB and fluoride-containing adhesive (Clearfil Protect Bond - PB). Volunteers (n = 17) wore an intra-oral appliance containing three enamel and three dentin blocks, aligned side-by-side and restored with OP or PB and one enamel and dentin block (controls). The cariogenic challenge was carried out in two phases of 14 days each. The counts of total streptococci (TM), mutans streptococci (MS) and lactobacilli (LB) were analyzed in the biofilm formed. Cross-sectional microhardness (CSM) and polarized light microscopy (PLM) evaluated caries lesions around the restorations and the demineralization extension. Data obtained by CSM testing was analyzed by Split-Split Plot ANOVA (P < 0.05). PLM and microbiota results were analyzed by Wilcoxon test (P < 0.05). RESULTS: TM and MS counts were highest for the OP enamel restorations, and these presented higher lesion depths than PB in both the enamel and dentin. The CSM in dentin was the lowest at 60 µm from the restoration wall. None of the adhesives prevented demineralization and bacteria growth, but PB reduced the amount of oral pathogens in enamel and demineralization around restorations in enamel and dentin.

Effect of 7.5% hydrogen peroxide containing remineralizing agents on hardness, color change, roughness and micromorphology of human enamel.

PURPOSE: To determine the microhardness, color change, surface roughness, and micromorphology of tooth enamel submitted to bleaching treatment with 7.5% hydrogen peroxide (HP) with added calcium, amorphous calcium phosphate, sodium fluoride (NaF), and hydroxyapatite (HA). METHODS: 80 enamel slabs were used (n = 10). Three commercial agents [Pola Day 7.5%, Day White ACP 7.5% (DW-ACP), and White Class Calcium 7.5% (WC-Calcium)], three experimental (7.5% HP+NaF, 7.5% HP+HA, and 7.5% PH+NaF+HA), a positive control (with HP), and a negative control (without HP) groups were assessed. The commercial products were applied according to manufacturers' recommendations and the experimental ones were applied for 1.5 hours daily. During and after treatment, specimens were stored in artificial saliva. Tests were performed at baseline, 7, 14, 21, 28, and 35 days. Data were analyzed by ANOVA and Tukey's test (α = 0.05). RESULTS: DW-ACP presented lower microhardness and HP+HA presents the highest values (P < 0.05); only the experimental group presented color change similar to the commercial agents (P > 0.05). Overall, roughness increased with time (P < 0.05) and porosities, and deposition of crystalline structures in groups HP+HA and HP+NaF+HA were noted. The HP+HA agent was capable of reducing the loss of enamel microhardness due to bleaching and also present color change similar to the commercial products.

Impact of the distance of light curing on the degree of conversion and microhardness of a composite resin.

OBJECTIVE: This study evaluated the impact of the distance between the light guide tip of the curing unit and material surface on the degree of conversion and Knoop microhardness of a composite resin. MATERIALS AND METHODS: Circular samples were carried out of a methacrylate micro-hybrid resin-based composite and light cured at 0, 2 and 4 mm distance. Monomer conversion rate was measured using a Fourier-transform Raman spectrometer and Knoop hardness number was obtained using a microhardness tester on the top and bottom surfaces. Data were statistically analyzed by analysis of variance and Tukey's test (α=0.05). RESULTS: Overall, the increase of curing distance reduced the microhardness (p≤0.05), but did not influence the carbon double bond conversion rate (p>0.05) of the composite resin tested; and the top surface showed better properties compared to the bottom (p≤0.05). CONCLUSIONS: The light curing at distance can reduce mechanical properties and could affect long-term durability of the composite restorations. Thus, the use of a curing device with high irradiance is recommended.