An in vitro assessment of type, position and incidence of isthmus in human permanent molars

Root canal anatomical complexities, such as isthmus, may limit the action of the endodontic instruments, irrigant solutions and intracanal medications, leading to endodontic treatment failure. Objectives: This in vitro study assessed the type, position and incidence of isthmus in human permanent molars. Material and Methods: One hundred roots were embedded in transparent resin, and then split at different distances from the apex (1.0–2.5–4.0–5.5–7.0 mm). Following the sample examination in stereomicroscope, ! The highest isthmus incidence was at 7.0 mm from the root apex in all samples, except the distal root of lower molars (at 5.5 mm). In upper and lower molars, type V (complete isthmus with a continuous opening between the two main root canals) was the most " #$% % & ' " molars, type IV had the highest incidence (36% and 23.9%, respectively). Conclusion: It " + - close to the apex. In upper and lower molars, these structures were most frequently found at 7 mm from the apex

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 ceramic28138COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçã

Effect of a mouthrinse containing selected propolis on 3-day dental plaque accumulation and polysaccharide formation

The aim of this study was to evaluate the effect of a mouthrinse containing propolis SNB-RS on 3-day dental plaque accumulation. Six volunteers took part in a double-blind crossover study performed in two phases of 3 days. During each phase the volunteers refrained from all oral hygiene and rinsed with 20% sucrose solution 5 times a day to enhance dental plaque formation and with mouthrinse (placebo or experimental) twice a day. On the 4th day, the plaque index (PI) of the volunteers was scored and the supragingival dental plaque was analyzed for insoluble polysaccharide (IP). The PI (SD) for the experimental group was 0.78 (0.17), significantly less than for the placebo group, 1.41 (0.14). The experimental mouthrinse reduced the IP concentration in dental plaque by 61.7% compared to placebo (p < 0.05). An experimental mouthrinse containing propolis SNB-RS was thus efficient in reducing supragingival plaque formation and IP formation under conditions of high plaque accumulation36644544

Increase In Severity Of Molar-incisor Hypomineralization And Its Relationship With The Colour Of Enamel Opacity: A Prospective Cohort Study.

Predicting risk of posteruptive enamel breakdown (PEB) of molar-incisor hypomineralization (MIH) opacity is a difficult but important clinical task. Therefore, there is a need to evaluate these aspects through longitudinal studies. The aim of this longitudinal study was to analyse the relationship between colours of MIH opacity of children aged 6-12 (baseline) and other clinical and demographic variables involved in the increase in severity of MIH. A blinded prospective 18-month follow-up was conducted with 147 individuals presenting mild MIH. Tooth-based incidence of increase in severity of MIH (PEB or atypical restorations) was used as dependent measurement. Enamel opacities were recorded according to colour shades of white, yellow and brown, allowing assessment of susceptibility to structural loss over time, according to colour of MIH opacity. Poisson regression models were used to adjust the results for demographic and clinical variables. Brown and yellow MIH opacities were at higher risk for PEB and atypical restorations than those of white ones, even after adjustment for clinical and demographic variables. Teeth presenting mild MIH severity associated with yellow and brown enamel opacities were at high risk for increase in severity of MIH than lighter ones. This result could help clinicians determine a risk-based treatment for children with MIH.21333-4

Increase in severity of molar-incisor hypomineralization and its relationship with the colour of enamel opacity: a prospective cohort study

Background. Predicting risk of posteruptive enamel breakdown (PEB) of molar-incisor hypomineralization (MIH) opacity is a difficult but important clinical task. Therefore, there is a need to evaluate these aspects through longitudinal studies.Objective. The aim of this longitudinal study was to analyse the relationship between colours of MIH opacity of children aged 6-12 (baseline) and other clinical and demographic variables involved in the increase in severity of MIH.Materials and methods. A blinded prospective 18-month follow-up was conducted with 147 individuals presenting mild MIH. Tooth-based incidence of increase in severity of MIH (PEB or atypical restorations) was used as dependent measurement. Enamel opacities were recorded according to colour shades of white, yellow and brown, allowing assessment of susceptibility to structural loss over time, according to colour of MIH opacity. Poisson regression models were used to adjust the results for demographic and clinical variables.Results. Brown and yellow MIH opacities were at higher risk for PEB and atypical restorations than those of white ones, even after adjustment for clinical and demographic variables.Conclusion. Teeth presenting mild MIH severity associated with yellow and brown enamel opacities were at high risk for increase in severity of MIH than lighter ones. This result could help clinicians determine a risk-based treatment for children with MIH

Evaluation of physical properties of a nanocomposite after aging, bleaching and staining

Purpose: The objective of the in vitro study was to assess the effect accelerated artificial aging, bleaching agents and coffee staining on the color, gloss, roughness and microhardness of a nanocomposite. Materials and methods: 120 (7 x 2 mm) were prepared and randomly divided into 2 groups (n = 60) depending on the aging. Each group was further subdivided into 6 subgroups (n = 10) according to the bleaching and staining as follows: 10% carbamide peroxide (10% CP), 10% CP + staining, 35% hydrogen peroxide (35% HP), 35% HP + staining, without bleaching treatment (WB) and WB + staining. Scanning electron microscopy was performed for qualitative analysis of the resin surface. Data were submitted to 3- way analysis of variance (ANOVA) and Tukey's test for multiple comparisons. As for Delta E, multiple comparisons were performed by using Tukey's and Dunnett's tests (alpha = 0.05). Results: The bleaching reduced significantly the microhardness of the nanocomposite in without aging groups. All physical properties were found to be negatively changed after the aging process, with bleaching treatment with 10% CP increasing significantly the roughness and loss of gloss compared to the 35% HP. Staining reduced microhardness of both with and without aging nanocomposite as well as the color of the former (E>25), a significantly different result compared to controls. Conclusions: The bleaching reduced the microhardness of the nanocomposite, whereas the aging process changed all the properties studied. The bleaching favored extrinsic staining of the with aging nanocomposite143E256E265COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESsem informaçã

Effects of five carbamide peroxide bleaching gels on composite resin microhardness.

The purpose of this study was to evaluate the effects of five home bleaching products containing 15-16% carbamide peroxide on the microhardness of microhybrid composite resin Z-250 (3M/Espe). A total of 72 specimens were fabricated in cylindrical acrylic matrices (4 x 2 mm), filled with composite resin and photo-activated for 40 seconds. They were divided in 6 study groups (n = 12), according to the bleaching product: Review (SS White), Magic Bleaching (Vigodent), Opalescence (Ultradent), Whiteness Perfect (FGM), Claridex (Biodinâmica), and a control group (not bleached). Specimens were exposed to 1 cc of bleaching gel for 6 hours daily for 2 weeks. The control group specimens were kept in artificial saliva throughout this time. All the specimens were then analyzed in a microhardness tester. Knoop hardness measurements were performed, and the results were submitted to parametric statistical analysis (analysis of variance and Tukey's test). Mean Knoop values and standard deviation were: baseline, 68.52a (4.28); control, 63.42b (7.16); Whiteness Perfect, 57.57c (1.81); Magic Bleaching, 57.22c (3.84); Opalescence, 57.03cd (4.00); Claridex, 53.64de (3.33); Review 51.45e (2.82). Identical letters mean statistical equality according to Tukey's test at the 5% significance level. The products significantly decreased Z-250 (3M/Espe) microhardness