Comparative proteomic analysis of dental cementum from deciduous and permanent teeth.

BACKGROUND AND OBJECTIVES: Dental cementum (DC) is a mineralized tissue covering tooth roots that plays a critical role in dental attachment. Differences in deciduous vs. permanent tooth DC have not been explored. We hypothesized that proteomic analysis of DC matrix would identify compositional differences in deciduous (DecDC) vs. permanent (PermDC) cementum that might reflect physiological or pathological differences, such as root resorption that is physiological in deciduous teeth but can be pathological in the permanent dentition. METHODS: Protein extracts from deciduous (n = 25) and permanent (n = 12) teeth were pooled (five pools of DecDC, five teeth each; four pools of PermDC, three teeth each). Samples were denatured, and proteins were extracted, reduced, alkylated, digested, and analyzed by liquid chromatography-mass spectrometry (LC-MS/MS). The beta-binomial statistical test was applied to normalized spectrum counts with 5% significance level to determine differentially expressed proteins. Immunohistochemistry was used to validate selected proteins. RESULTS: A total of 510 proteins were identified: 123 (24.1%) exclusive to DecDC; 128 (25.1%) exclusive to PermDC; 259 (50.8%) commonly expressed in both DecDC and PermDC. Out of 60 differentially expressed proteins, 17 (28.3%) were detected in DecDC, including myeloperoxidase (MPO), whereas 43 (71.7%) were detected in PermDC, including decorin (DCN) and osteocalcin (BGLAP). Overall, Gene Ontology (GO) analysis indicated that all expressed proteins were related to GO biological processes that included localization and response to stress, and the GO molecular function of differentially expressed proteins was enriched in cell adhesion, molecular binding, cytoskeletal protein binding, structural molecular activity, and macromolecular complex binding. Immunohistochemistry confirmed the trends for selected differentially expressed proteins in human teeth. CONCLUSIONS: Clear differences were found between the proteomes of DecDC and PermDC. These findings may lead to new insights into developmental differences between DecDC and PermDC, as well as to a better understanding of physiological/pathological events such as root resorption.

Glass-ionomer cement modifies the gene expression of Streptococcus mutans providing a lower virulent biofilm.

PURPOSE: To evaluate the effect of glass-ionomer cement (GIC) on gene expression (gtfC, gtfD, covR, and vicR) of Streptococcus mutans (S. mutans) biofilms at 2, 4 and 24 hours. METHODS: Six groups were tested according to the materials and time observation, as follows: ceramic (IPS Empress Esthetic), as the control group, and GIC (Ketac Molar Easymix); and time points of S. mutans biofilm formation (2, 4, and 24 hours). Round-shaped samples (10 x 2 mm) of each material were prepared according to the manufacturers' specifications. GIC discs were handled in a laminar flow hood under aseptic conditions and stored at 100% relative humidity at 37°C for 24 hours to complete setting reaction. The samples were placed in a 24-well plate and immersed in 1.5 ml BHI + 1% sucrose with an inoculum of S. mutans UA159 to allow biofilm growth during 2, 4, and 24 hours. Next, the samples were removed, vortexed and centrifuged to collect cell pellets (n=5) for each material and time point. Pellets were stored at -80°C. Then, RNA was purified using the RNeasy Mini Kit protocol. The RNA was converted in cDNA using iScript cDNA Synthesis according to the manufacturer's recommendations. Analysis of gtfC, gtfD, vicR, and covR expressions was performed using Step One Real-Time qPCR device with specific primers for each gene and the analysis normalized by 16S reference gene expression. Data from gtfC, gtfD, and vicR were analyzed by t-test to compare between groups while Mann-Whitney was used to analyze covR expression (α= 0.05). RESULTS: No significant differences at 2 and 4 hours between materials for all analyzed genes were noted. However, in the 24-hour period, a significant decrease in gtfC and vicR expressions were observed, while covR expression increased when GIC was compared to ceramic. CLINICAL SIGNIFICANCE: The use of glass-ionomer cement decreased the virulence of S. mutans biofilms, which may imply a reduced bacterial cariogenic potential.

Synthesis and application of triclosan methacrylate monomer in resin composites.

OBJECTIVES: To evaluate the antibacterial activity, bacterial viability, cytotoxicity, and mechanical/physical properties of a novel methacrylate triclosan-derivative monomer (TM) incorporated in dental resin composite. METHODS: TM was synthesized by esterification and, after characterization by FT-IR, was added to an experimental composite. Samples were divided into two groups according to TM presence, i.e., C1 (control) and C2 (C1 + 14.4% TM). Microbiological properties: Specimens (C1 and C2) were prepared and placed on bacterial suspensions of Streptococcus mutans. Antibacterial activity, MTT, and live/dead bacterial viability were used to test the resin composites. All assays were performed in triplicates. Mechanical properties: Specimens underwent compression (CS) and flexural strength (FS) tests conducted in an Instron universal testing machine at a crosshead speed of 0.5 mm/min. Physical properties: Specimens were assessed for Knoop hardness (KHN) and crosslink density (CD). Fourier transform infrared spectroscopy allowed the degree of conversion (DC) to be evaluated. Data were subjected to appropriate statistical tests according to data distribution and assay (p < 0.05). RESULTS: Microbiological properties: C2 showed the lowest biofilm accumulation and the highest membrane-compromised bacteria in the biofilm. Mechanical/physical properties: For CS, FS, KHN, and DC, there was no significant difference between groups C1 and C2; however, significant difference was observed for the CD assay. CONCLUSIONS: The triclosan methacrylate reduces bacterial adhesion of S. mutans and decreased the formation of bacterial biofilm without affecting important polymer properties. The triclosan methacrylate incorporated in resin composite could greatly reduce the live bacterial adhesion of S. mutans and decrease the formation of bacterial biofilm without affecting important polymer properties. CLINICAL SIGNIFICANCE: The resin composites containing triclosan methacrylate could greatly reduce the bacterial adhesion and biofilm formation. That might prevent the secondary caries round the margins of the restorations.

Comparative Analysis of Root Dentin Morphology and Structure of Human Versus Bovine Primary Teeth.

This study evaluated the structural and morphological differences between human and bovine primary root canals. Primary human maxillary central incisors (H) (n=9) and primary bovine incisors (B) (n=9) were selected. The roots were sectioned in the vestibular-lingual direction, planed and delimited in cervical, middle, and apical thirds. Tubule density (number of tubules per mm2) and diameter were analyzed by scanning electron microscopy (1,000 and 5,000×) using Image J 1.47 software. Data were submitted to two-way repeated measures ANOVA and Tukey tests (α=0.05). The highest tubule density was observed for B (28.527±1.717 mm2) compared with H (15.931±0.170 mm2) (p<0.01). Regarding root thirds, the cervical third presented a greater tubule density (26.417±11.654 mm2) than the apical third (17.999±5.873 mm2). The diameter of the dentin tubules was not different for cervical (3.50±0.08 µm), middle (3.45±0.30 µm) and apical thirds (3.42±0.33 µm) and substrate (H-3.29±0.14 µm; B-3.63±0.06 µm). It could be concluded that: (1) the radicular dentin structure of human and bovine primary teeth and root thirds differ in terms of the tubule density; (2) the radicular dentin morphology of human and bovine primary teeth and root thirds are similar in terms of the diameter of the dentin tubules.

In situ bacterial accumulation on dental restorative materials. CLSM/COMSTAT analysis.

PURPOSE: To evaluate the influence of different restorative materials on the biofilm structure accumulated in situ. METHODS: 15 discs of each material (ceramic; resin composite; resin-modified and conventional glass-ionomers; amalgam) were adapted to palatal devices in order to accumulate biofilm in situ, under a cariogenic challenge (20% sucrose solution, 10x/day). After 7 days, the specimens were carefully removed and visualized by confocal laser scanning microscopy (CLSM). The images were analyzed qualitatively (descriptive analysis about cell viability and architecture) and quantitatively using COMSTAT software (area, bio-volume, mean thickness, maximum thickness and roughness coefficient of the biofilm). The statistical analysis was performed by using the Kolmogorov-Smirnov and Kruskal-Wallis tests (P ≤ 5%). RESULTS: The medians of the biofilm parameters analyzed showed no statistical difference regarding different materials. However, qualitatively, glass-ionomer cements and amalgam showed visually a prevalence of non-viable cells forming small clusters distributed by the biofilm, and voids were presented in smaller proportion in the biofilm volume compared to composite and ceramic.

Bonding orthodontics brackets to enamel using experimental composites with an iodonium salt.

OBJECTIVES: This study investigated whether the addition of diphenyliodonium chloride (DPC) to experimental resin bonding agents would allow fixation of brackets to enamel using shorter light exposure times. METHODS: Photoactivated dimethacrylate-based composites were prepared containing DPC molar concentrations of 0 (control), 0.5 (R05), or 1 per cent (R1). Metallic brackets were bonded to bovine incisors and the bond strengths were evaluated using a shear test. In total, 18 groups were tested (n = 15 per group) defined by three bonding materials (control, R05, or R1), three light-activation time (8, 20, or 40 seconds), and two storage periods (10 minutes or 24 hours). The adhesive remnant index (ARI) was scored under magnification. Data were statistically analysed at a 5 per cent significance level. RESULTS: At 10 minutes, the control composite showed lower bond strengths than the DPC-modified bonding agents for all light-activation times. Differences in bond strengths between both DPC-modified agents were not significant. Lower bond strengths at 10 minutes were generally observed for groups light activated for 8 seconds compared with groups light activated for 20 and 40 seconds. At 24 hours, no significant differences were observed among the light-activation times. The bond strengths at 24 hours were higher than the bond strengths at 10 minutes for all groups. A predominance of ARI scores 2 and 3 was generally observed. CONCLUSION: The use of a ternary photoactivation system containing an iodonium salt in bonding composites may allow bonding brackets to enamel using reduced light exposure times.

Self-assembled peptide P11-4 interacts with the type I collagen C-terminal telopeptide domain and calcium ions.

OBJECTIVES: Evaluate molecularly the role of P11-4 self-assembly peptide in dentin remineralization and its interaction with collagen I. METHODS: The calcium-responsive P11-4 peptide was analyzed by intrinsic fluorescence emission spectrum, circular dichroism spectrum (CD), and atomic force microscope (AFM). Differential light scattering was used to monitor the nucleation growth rate of calcium phosphate nanocrystals in the absence or in the presence of P11-4. AFM was used to analyze the radial size (nm) of calcium phosphate nanocrystals formed in the absence or in the presence of P11-4, as well as to verify the spatial structure of P11-4 in the absence or in the presence of Ca2+. RESULTS: The interaction of Ca2+ with the P11-4 (KD = 0.58 ± 0.06 mM) promotes the formation of ß-sheet antiparallel structure, leads to its precipitation in saturated solutions of Ca/P = 1.67 and induces the formation of parallel large fibrils (0.6 - 1.5 µm). P11-4 organized the HAP nucleation by reducing both the growth rate and size variability of nanocrystals, analyzed by the F test (p < 0.0001, N = 30). P11-4 interacts (KD = 0.75 ± 0.06 µM) with the KGHRGFSGL motif present at the C-terminal collagen telopeptide domain. P11-4 also increased the amount of HAP and collagen in the MDPC-23 cells. SIGNIFICANCE: The presented data propose a mechanism that will help future clinical and/or basic research to better understand a molecule able to inhibit structural collagen loss and help the impaired tissue to remineralize.

Degree of conversion of simplified contemporary adhesive systems as influenced by extended air-activated or passive solvent volatilization modes.

This study evaluated the effect of five methods of solvent volatilization on the degree of conversion (DC) of nine one-bottle adhesive systems using Fourier transform infrared/attenuated total reflectance (FTIR/ATR) analysis. Nine adhesives were tested: Adper Single Bond 2 (SB), Adper Easy One (EO), One Up Bond F Plus (OUP), One Coat Bond SL (OC), XP Bond (XP), Ambar (AM), Natural Bond (NB), GO, and Stae. The adhesive systems were applied to a zinc-selenide pellet and 1) cured without solvent volatilization, 2) left undisturbed for 10 seconds before curing, 3) left undisturbed for 60 seconds before curing, 4) air-dried with an air stream for 10 seconds before curing, and 5) air-dried with an air stream for 60 seconds before curing. FTIR/ATR spectra were obtained, and the DC was calculated by comparing the aliphatic bonds/reference peaks before and after light activation for 10 seconds (FlashLite 1401). The DC means of each material were analyzed by one-way analysis of variance and post hoc Tukey test (p<0.05). The DC of GO and Stae adhesive systems was not affected by the five evaporation conditions. Air-drying for 60 seconds before curing yielded the highest DC for SB, EO, and OC. Extended solvent volatilization time (60 seconds) either with or without air-drying before curing provided the highest DC for AM, NB, XP, and OUP. Thus, the monomer conversion of adhesive systems was material dependent. In general, the 60-second passive or active air-drying modes to volatilize solvents before curing enhanced the degree of conversion for the one-bottle simplified adhesive systems.

Self-assembling peptide-laden electrospun scaffolds for guided mineralized tissue regeneration.

OBJECTIVES: Electrospun scaffolds are a versatile biomaterial platform to mimic fibrillar structure of native tissues extracellular matrix, and facilitate the incorporation of biomolecules for regenerative therapies. Self-assembling peptide P11-4 has emerged as a promising strategy to induce mineralization; however, P11-4 application has been mostly addressed for early caries lesions repair on dental enamel. Here, to investigate P11-4's efficacy on bone regeneration, polymeric electrospun scaffolds were developed, and then distinct concentrations of P11-4 were physically adsorbed on the scaffolds. METHODS: P11-4-laden and pristine (P11-4-free) electrospun scaffolds were immersed in simulated body fluid and mineral precipitation identified by SEM. Functional groups and crystalline phases were analyzed by FTIR and XRD, respectively. Cytocompatibility, mineralization, and gene expression assays were conducted using stem cells from human exfoliated deciduous teeth. To investigate P11-4-laden scaffolds potential to induce in vivo mineralization, an established rat calvaria critical-size defect model was used. RESULTS: We successfully synthesized nanofibrous (∼ 500 nm fiber diameter) scaffolds and observed that functionalization with P11-4 did not affect the fibers' diameter. SEM images indicated mineral precipitation, while FTIR and XRD confirmed apatite-like formation and crystallization for P11-4-laden scaffolds. In addition, P11-4-laden scaffolds were cytocompatible, highly stimulated cell-mediated mineral deposition, and upregulated the expression of mineralization-related genes compared to pristine scaffolds. P11-4-laden scaffolds led to enhanced in vivo bone regeneration after 8 weeks compared to pristine PCL. SIGNIFICANCE: Electrospun scaffolds functionalized with P11-4 are a promising strategy for inducing mineralized tissues regeneration in the craniomaxillofacial complex.

Effect of a Self-Assembly Peptide on Surface Roughness and Hardness of Bleached Enamel.

After bleaching, enamel surfaces are damaged, contributing to erosion and tooth sensitivity. Although fluoride is used after bleaching to try and revert alterations, it is not capable of repairing tooth structure. This study compared the effect of a self-assembly peptide (P11-4), with and without fluoride, and sodium fluoride (NaF 2%) on the Knoop microhardness (KHN) and surface roughness (Ra (µm)) of bleached enamel with an in-office bleaching regimen. Enamel blocks of bovine teeth (5 × 5 × 2 mm) with standardized surface hardness were bleached with 35% carbamide peroxide, following the manufacturer's instructions. The teeth were randomly divided into the following groups (n = 7) according to post-bleaching treatment: no treatment (negative control) (C-); 2% NaF (NaF); Curodont™ Repair (Repair); and Curodont™ Protect (Protect). Specimens were stored in artificial saliva at 37 °C. To evaluate the effect of the post-bleaching treatments, KHN and Ra were measured before bleaching (baseline) and 24 h and 7 days after bleaching. Data were submitted to repeated measures ANOVA and Bonferroni tests (α = 0.05). There were significant interactions between the study factors (p = 0.001). After 7 days, Repair (572.50 ± 79.04) and Protect (583.00 ± 74.76) specimens showed increased surface KHN, with values higher than the NaF (465.50 ± 41.50) and C- (475.22 ± 58.95) baseline values. There was no significant difference in KHN at 24 h among groups (p = 0.587). At 24 h after bleaching, Repair was significantly different from all groups (p < 0.05). Repair showed the lowest Ra (µm) values (0.133 ± 0.035). After seven days, there was no significant difference in Ra values among groups when compared to the baseline. The use of P11-4-based materials after bleaching resulted in the fastest recovery to baseline enamel properties.

Wettability and pre-osteoblastic behavior evaluations of a dense bovine hydroxyapatite ceramics.

In this study, the wettability, cell viability, and roughness of an experimental dense bovine hydroxyapatite [Ca10(PO4)6(OH)2] ceramic block were evaluated so that, in the future, it could be used as a base material for dental implants. The results to commercial zirconia and a commercially pure titanium (Ti) alloy were compared. The surface roughness and contact angles were measured. An in vitro evaluation was conducted by means of tests in which pre-osteoblastic MC3T3-E1 cells were placed in indirect and direct contact with these materials. For cell viability, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and crystal violet test were conducted. A qualitative analysis was conducted using variable pressure scanning electron microscopy (SEM). No statistically significant differences were observed in wettability and roughness tests among the groups. In both the MTT assay and crystal violet test, all groups demonstrated satisfactory results without cytotoxicity. SEM showed cell adhesion and cell proliferation results on the material surfaces after 24 h and 48 h. In conclusion, this dense Ca10 (PO4)6(OH)2 ceramic can be considered as a potential biocompatible material.

Influence of the incorporation of triclosan methacrylate on the physical properties and antibacterial activity of resin composite.

The incorporation of antimicrobials in the composites as an attempt to reduce bacterial adhesion without jeopardizing mechanical properties is a challenge for Dentistry. OBJECTIVE To evaluate the bacterial adhesion and physical properties of a composite containing the methacrylate triclosan- derivative monomer (TM). METHODOLOGY TM was synthesized and added to an experimental composite. Samples were divided into two groups: Control and TM (13.4 wt%). Antibacterial Activity: Three specimens of each material were prepared and placed on bacterial suspensions of Streptococcus mutans for 1, 5 and 10 days. After these periods the counting of the colonies (log10) was performed. Assays was performed in triplicate. Physical Properties: Three-body Abrasion (TBA): Ten specimens of each material were prepared and stored at 37°C/24 h. The surface roughness (Ra) and hardness (KHN) were analyzed. Next, the specimens were submitted to abrasive wear (30,000 cycles) and re-evaluated for Ra and KHN; Sorption/solubility (SS): cylindrical specimens (n=10) were prepared and weighted. The specimens were immersed in deionized water for 7 days at 37°C and then their weight was verified again. SS were calculated using accepted formulas; Diametral tensile strength (DTS): specimens (n=10) underwent test performed in an Instron universal testing machine at a crosshead speed of 1 mm/min. Data were submitted to appropriate statistical tests according to data distribution and assay (p<0.05). RESULTS Bacterial Adhesion: TM showed a significant reduction on biofilm accumulation in the evaluated periods: 1 day (1.537±0.146); 5 days (2.183±0.138) and 10 days (4.469±0.155) when compared with Control: 1 day (4.954±0.249); 5 days (5.498±0.257) and 10 days (6.306±0.287). Physical Properties: For TBA, SS and DTS no significant difference was found between groups Control and TM. The incorporation of methacrylate triclosan-based monomer in the experimental composite reduce bacterial adhesion of S. mutans and did not affect important polymer properties.

Membrane proteome characterization of periodontal ligament cell sets from deciduous and permanent teeth.

BACKGROUND: Physiological roles for the periodontal ligament (PDL) include tooth eruption and anchorage, force absorption, and provision of proprioceptive information. Despite the advances in understanding the biology of PDL cells, there is a lack of information regarding the molecular signature of deciduous (DecPDL) and permanent (PermPDL) PDL tissues. Thus, the present study was designed to characterize the membrane proteome of DecPDL and PermPDL cells. METHODS: Primary PDL cells were obtained (n = 6) and a label-free quantitative proteome of cell membrane-enriched components was performed. Proteome findings were validated by quantitative polymerase chain reaction and Western blot assays in fresh human tissues (n = 8) and primary cell cultures (n = 6). In addition, confocal microscopy was used to verify the expression of target factors in the PDL cell cultures. RESULTS: Comparative gene ontology enrichment analysis evidenced that most stickling differences involved "endomembrane system" (PICALM, STX4, and LRP10), "hydrolase activity" (NCSTN and XRCC6), "protein binding" (PICALM, STX4, GPNMB, VASP, extended-synaptotagmin 2 [ESYT2], and leucine-rich repeat containing 15 [LRRC15]), and "isomerase activity" (FKBP8). Data are available via ProteomeXchange with identifier PXD010226. At the transcript level, high PICALM in DecPDL and ESYT2 and LRRC15 in PermPDL were confirmed in fresh PDL tissues. Furthermore, Western blot analysis confirmed increased levels of PICALM, LRRC15, and ESYT2 in cells and/or fresh tissues, and confocal microscopy confirmed the trends for PICALM and LRRC15 expression in PDL cells. CONCLUSION: We report the first comprehensive characterization of the membrane protein machinery of DecPDL and PermPDL cells, and together, we identified a distinct molecular signature for these cell populations, including unique proteins for DecPDL and PermPDL.

The influence of 30-day-old Streptococcus mutans biofilm on the surface of esthetic restorative materials--an in vitro study.

OBJECTIVE: To evaluate the effects of Streptococcus mutans biofilm/restorative materials interaction on surface roughness, hardness and morphology of materials tested. METHODS: Empress 2 (E2), Filtek Supreme (FS), Vitremer (V) and Ketac Molar Easymix (KM) were tested. Twenty-five disks of each material were made and divided into three storage groups: (1) 100% relative humidity (n=5); (2) growth medium (BHI and 1% sucrose) (n=5); (3) S. mutans biofilm-growth medium (n=15). Before storage, hardness measurements were immediately obtained from group 1 specimens. After 30 days of storage, the specimens were cleaned in order to obtain the surface roughness and hardness values, besides morphology analysis by scanning electron microscopy. RESULTS: The surface roughness and hardness values obtained from E2 and FS specimens did not present statistically significant differences among the groups 1, 2 and 3 and between immediate and 30-day-old specimens of each material. However, group 3 specimens of V and KM showed statistically significant higher surface roughness means than other groups. Group 1 specimens of V and KM also showed higher hardness values than the immediate values. Group 3 specimens of V presented decreased hardness values compared with other groups. The scanning electron micrographs showed an increase in surface degradation from group 1 to group 3 for FS, V and KM. CONCLUSIONS: Thirty-day-old biofilm promotes a negative effect on the surface morphology of FS, V and KM, on the surface roughness of V and KM and on the hardness of V.

Effect of restorative technique and thermal/mechanical treatment on marginal adaptation and compressive strength of esthetic restorations.

This study evaluated the compressive strength and marginal adaptation of composite onlays using indirect and direct techniques after thermal and mechanical cycling. Onlay standardized cavities were prepared in 50 permanent molars and restored with Z-250 resin composite using indirect (IRT) or direct (DRT) restorative techniques. The restorations were either submitted or not submitted to thermal (500 cycles, 5 degrees to 55 degrees C) and mechanical cycling (50,000 cycles, 50N). The teeth were distributed to five groups (n=10): G1-IRT/cycling; G2-IRT/no cycling; G3-DRT/cycling; G4-DRT/no cycling and G5 (control group)-sound teeth. All prepared teeth were stored in 100% relative humidity at 37 degrees C for 24 hours, followed by finishing with Sof-Lex discs. A caries detector solution was applied on the tooth-restoration interface of all teeth for five seconds, followed by washing and drying. Four digital photographs were taken of each tooth surface. The extent of gaps was measured using standard software (Image Tool 3.0). All groups were submitted to compression testing in a universal testing machine (INSTRON) at a crosshead speed of 1 mm/minute until failure. The compressive strength (CS) and marginal adaptation data were submitted to ANOVA and Tukey test (p<0.05). For both evaluation criteria (compressive strength and marginal adaptation), there were no statistically significant differences among the restorative techniques. Deterioration over time was observed for both types of restorations. However, the prevalence of catastrophic fractures increased among direct restorations. The application of thermal/mechanical cycling only influenced marginal adaptation.

Modulated photoactivation methods--effect on marginal and internal gap formation of restorations using different restorative composites.

UNLABELLED: This study evaluated the effect of modulated photoactivation methods on gap formation of restorations using different composites. METHODS: Sixty human third molars were selected, sectioned (two fragments), and ground to expose a flat enamel area. A cavity (5 mm long x 2 mm wide x 2 mm deep--outer margins in enamel and inner margins in dentin) was prepared on the central area of flattened surface. Single bond adhesive system was applied according to manufacturer's instructions. The specimens were assigned into 12 groups (n = 10), according to the restorative composite (Filtek Z250, Herculite XRV, and Heliomolar) and the photoactivation method [continuous light (CL); soft-start (SS); pulse delay (PD); and intermittent light (IL)]. Outer margins were stained using Caries Detector, observed under stereomicroscope, and images were transferred to a computer measurement program. Then, the specimens were sectioned in slices and the internal gaps were assigned using the same method. The length of gaps was expressed as a percentage of total length of the margins. Data (internal adaptation) were submitted to ANOVA and Tukey's test. RESULTS: All restorations showed perfect seal of the enamel outer margins. Modulated photoactivation methods (SS, PD, and IL) showed a significant reduction on internal gap formation when compared with CL, regardless of the composite. Filtek Z250 showed the best internal adaptation, regardless of the photoactivation method. CONCLUSION: Modulated photoactivation methods decrease the internal gap formation of composite restorations, and should be encouraged on clinical practice.

Changes in the masticatory cycle after treatment of posterior crossbite in children aged 4 to 5 years.

INTRODUCTION: The aim of this study was to analyze the dynamics of the masticatory cycle after occlusal adjustment through coronoplasty on deciduous teeth (selective grinding) and composite resin occlusal guidance for posterior crossbite correction. METHODS: Nineteen children, aged 4 to 5 years, with functional posterior crossbites diagnosed at their clinical examinations, were selected. Analyses of masticatory cycles, including lateral excursive movements, were performed before and after treatment by using kinesiographic examinations in the 3 reference planes (frontal, horizontal, and sagittal). The examinations were done during bubble-gum chewing. The data were submitted to sign, Mann-Whitney, and paired t tests concerning the variables: left maximum lateral movement, right maximum lateral movement, total lateral movement (LM), vertical movement (VM), anteroposterior maximum movement, maximum lateral movement (MLM), and total maximum lateral movement (TMLM). RESULTS: The treatment produced increased TMLM, a significant increase of the MLM opposite the crossbite, no statistically significant difference of the crossbite side, and a significant decrease of LM. Left crossbite children showed significant decreases in the LM after treatment; right crossbite children showed significant increases in VM after treatment. CONCLUSIONS: Functional crossbite treatment with selective adjustment and occlusal guiding changed masticatory cycle patterns, producing larger horizontal and vertical planes. The cycles became more symmetric in the frontal plane, increasing the tendency of bilateral alternate mastication.

Sedative effect of oral diazepam and chloral hydrate in the dental treatment of children.

PURPOSE: The purpose was to evaluate two sedation protocols during dental sessions in anxious children. MATERIALS AND METHODS: It was a randomized and double-blind study, with each individual being his/her own control within each protocol. Furthermore, the two protocols were compared. Twenty children (36 to 84 months old) who exhibited "definitely negative" behavior according to the Frankl scale were assigned to receive oral chloral hydrate (40 mg/kg) (Group I) or Diazepam (5 mg) (Group II). Behavior during local anesthesia, application of rubber dam, cavity preparation, restorative procedures was evaluated, considering the degree of sleep, body movement, crying and overall behavior. Vital signs were assessed at three different times. The Wilcoxon, Mann-Whitney, Exact Fisher's and Spearman correlation tests were used to analyze the data. RESULTS: Group I presented higher scores for sleep during the CH session than placebo session during rubber dam application (P = 0.0431) and restoration (P = 0.0431). In Group II there was no statistically significant difference (p > 0.05). There were no statistically significant differences between sessions and groups in the evaluation of body movement, crying and vital signs. Overall behavior in the placebo session was better than in the CH session during local anesthesia, but there was no difference between the two drug regimens. There was influence of age during anesthesia and cavity preparation in Group I and during rubber dam application in Group II. It was concluded that oral diazepam and chloral hydrate had no influence on the behavior management for dental treatment with the studied sample.

Effect of blue and violet light on polymerization shrinkage vectors of a CQ/TPO-containing composite.

OBJECTIVE: To evaluate the effect of light-curing wavelengths on composite filler particle displacement, and thus to visualize localized polymerization shrinkage in a resin-based composite (RBC) containing camphorquinone (CQ) and Lucirin TPO (TPO). METHODS: Three light-curing units (LCUs) were used to light-cure a RBC containing CQ and TPO: a violet-only, a blue-only, and a dual-wavelength, conventional (Polywave®, emitting violet and blue wavelengths simultaneously). Zirconia fillers were added to the RBC to act as filler particle displacement tracers. LCUs were characterized for total emitted power (mW) and spectral irradiant output (mW/cm2/nm). 2-mm high, 7-mm diameter silanized glass cylindrical specimens were filled in a single increment with the RBC, and micro-computed tomography (µ-CT) scans were obtained before and after light-curing, according to each LCU (n=6). Filler particle movement identified polymerization shrinkage vectors, traced using software, at five depths (from 0 up to 2mm): top, top-middle, middle, middle-bottom and bottom. RESULTS: Considering different RBC depths within the same LCU, use of violet-only and conventional LCUs showed filler particle movement decreased with increased depth. Blue-only LCU showed homogeneous filler particle movement along the depths. Considering the effect of different LCUs within the same depth, filler particle movement within LCUs was not statistically different until the middle of the samples (P>.05). However, at the middle-bottom and bottom depths (1.5 and 2mm, respectively), blue-only LCU compared to violet-only LCU showed higher magnitude of displacement vector values (P<.05). Use of the conventional LCU showed filler displacement magnitudes that were not significantly different than blue-only and violet-only LCUs at any depth (P>.05). With respect to the direction of particle movement vectors, use of violet-only LCU showed a greater displacement when close to the incident violet LED; blue-only LCU showed equally distributed particle displacement values within entire depth among the samples; and the conventional LCU showed greater filler displacement closer to the blue LED locations. SIGNIFICANCE: Filler particle displacement in a RBC as a result of light-curing is related to localized application of light wavelength and total emitted power of the light emitted on the top surface of the RBC. When the violet LED is present (violet-only and conventional LCUs), filler particle displacement magnitude decreased with increased depth, while results using the blue-only LED show a more consistent pattern of displacement. Clinically, these results correlate to production of different characteristics of curing within a RBC restoration mass, depending on localized wavelengths applied to the irradiated surface.

Compomer as a pit and fissure sealant: effectiveness and retention after 24 months.

PURPOSE: The aim of this study was to evaluate the effectiveness and retention of occlusal sealing using FluroShield or Compoglass. METHODS: The sample consisted of 57 children aged 7 to 9 years who had 4 sound, fully erupted, first permanent molars (total=228 teeth). Both materials were applied on contralateral teeth in a split-mouth design in 2 groups: (1) FluroShield--left upper molar and right lower molar; (2) Compoglass--right upper molar and left lower molar. The materials were applied under cotton roll isolation by the same operator according to the manufacturers' instructions. The evaluations were carried out at 6, 12, and 24 months. The data were subjected to the G2 (likelihood ratio chi-square test; P<.05). RESULTS: At the 6-month evaluation, Compoglass showed 60% total retention, 23% partial retention, and 17% total loss. FluroShield showed 53% total retention, 31% partial retention, and 16% total loss. At the 12-month recall, Compoglass and FluroShield, respectively, showed 39% and 43% total retention, 38% and 33% partial retention, and 24% and 25% total loss. At the 24-month evaluation, there was a reduction of 56% of the initial sample numbers (32/57), with 22% and 20% having total retention, 52% and 48% partial retention, and 26% and 32% total loss, respectively, for Compoglass and FluroShield. There was no significant statistical difference between the retention of both materials studied. There was no new caries formation during the evaluation period. CONCLUSION: It could be concluded that both materials effectively prevented caries in occlusal surfaces during the follow-up period, although both showed a low retention rates.