Influence of voxel size on cone beam computed tomography artifacts arising from the exomass.

OBJECTIVES: The objective of this study was to evaluate the influence of voxel size on artifacts arising from the exomass in cone beam computed tomography (CBCT). STUDY DESIGN: An imaging phantom was scanned using 2 CBCT units, each adjusted to 2 voxel sizes: 0.2 and 0.3 mm. From 1 to 3 metal inserts of titanium, cobalt-chromium, or amalgam were placed in the exomass and additional CBCT scans were acquired. Mean voxel gray values were obtained from 16 homogeneous areas of the phantom and averaged, and the standard deviation was calculated to obtain voxel gray value variability. The data were analyzed using 2-way analysis of variance, Tukey, and Dunnett tests (α =.05). RESULTS: Overall, mean voxel gray values and voxel gray value variability did not differ significantly between CBCT scans obtained with voxel sizes of 0.2 and 0.3 mm for either CBCT model tested (P > .05). Despite some exceptions in which significant differences were observed between the 2 voxel sizes (P < .05), the mean voxel gray values and voxel gray value variability resulting from different metal compositions and, in most situations, for different numbers of metal inserts in the exomass were not affected. CONCLUSION: Voxel size has little influence on exomass-related CBCT artifacts.

Impact of dietary acids on the surface roughness and morphology of composite resins.

This in vitro study was performed to evaluate the surface roughness (Ra) and morphology by scanning electron microscopy (SEM) of composite resins that had been stored in acidic solutions typical of those present in the diet. Three composite resins (4 Seasons, Z250, and P90) were selected and divided into three groups (n = 7) according to the solutions tested: G1: distilled water; G2, Coca-cola, and G3: orange juice. The Ra test was repeated after immersion periods of 15, 90, and 180 days. The mean Ra values were subjected to LS means analysis and the Tukey-Kramer (P < 0.05). One test specimen of each composite resin was selected for SEM analysis after each period. The Ra data indicated that P90 had the lowest Ra values. 4 Seasons and Z250 had statistically similar roughness values for all the solutions and evaluation periods. With the exception of 180-day immersion in Coca-cola, 4 Seasons showed significantly higher values than Z250. SEM analysis showed that P90 was the composite resin most resistant to the actions of all acid solutions for the periods analyzed. Interaction between components of the solutions and the active components of other dietary items, as well as oral hygiene, may affect the chemical degradation of composite resins.

Effects of sodium hypochlorite as dentin deproteinizing agent and aging media on bond strength of two conventional adhesives.

This study evaluated the effect of 10% sodium hypochlorite (NaOCl) as deproteinizing agent and storage media on bond strength (BS) of two etch-and-rinse adhesive systems to dentin. Twenty-eight sound extracted human third molars were divided in four groups (n = 7), according to dentin treatment (conventional etching or etching followed by 10% NaOCl application) and adhesive systems (GB-Gluma 2Bond and OS-One-Step). After dentin treatments and adhesive application, a composite block was built-up on dentin surface and teeth were serially sectioned to obtain bonded sticks specimens. The sticks were submitted to three aging conditions: (24H) 24 hr in water (immediate), (SH) 3 hr of NaOCl accelerated-aging or (1Y) 1 year of water storage. Afterward, submitted to microtensile bond strength test (µTBS), failure modes and adhesive interfaces analyzes. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test (α = .05). Dentin deproteinization before bonding significantly reduced µTBS for GB-treated group (p < .05), regardless the aging conditions. Water storage for 1 year (1Y) and NaOCl accelerated-aging (SH) decreased µTBS for both adhesives. Yet, the groups stored in NaOCl (SH) exhibited the lowest BS results (p < .05). Bond strength of deproteinized dentin was dependent on the adhesive system composition and NaOCl accelerated-aging promoted decreased bond strength and further degradation than water storage for 1 year.

Exploring the perception of orthodontic treatment need using the Dental Aesthetic Index and Index of Orthodontic Treatment Need.

INTRODUCTION: This study aimed to explore the perception of orthodontic treatment need by using the Dental Aesthetic Index (DAI) and the Index of Orthodontic Treatment Need (IOTN). METHODS: A cross-sectional study was conducted on a representative random sample (N = 248) of adolescents aged 12 years. The DAI and both components of IOTN were used to evaluate malocclusion. The association between the Dental Health Component of the IOTN with gender and ethnic group were analyzed by chi-square test. The concordances between the indexes were analyzed by the kappa statistic, with 95% confidence intervals (CIs). RESULTS: The prevalence of adolescents with high severity and orthodontic treatment need was 10.5% (95% CI, 6.7-14.3), 36.5% (95% CI, 32.3-44.3), and 73.4% (95% CI, 67.9-78.9) for the Aesthetic Component of the IOTN, Dental Health Component of the IOTN, and DAI, respectively. The indexes showed high agreement for the cases with low treatment need, whereas low concordance was observed for the cases with high treatment need. CONCLUSIONS: The perception of orthodontic treatment need was assessed differently using DAI and IOTN.

Women's sense of coherence and its association with early weaning / Senso de coerência da mulher e sua associação com o desmame precoce

Abstract Objective: To investigate whether there is an association between sense of coherence levels and early weaning. Method: This study had a quantitative nature and a cross-sectional design. Factors associated with early weaning (interruption of maternal breastfeeding) were investigated in a sample of 425 women older than 18 years, mothers of children up to 36 months of age who were not twins, with no sensory or motor deficiencies, without distinction of ethnicity or social class. The chi-squared test, with a significance level of 5%, was used to evaluate the association between the dependent variable (early weaning) and the independent variables (socioeconomic, demographic factors and sense of coherence level). Variables with p ≤ 0.20 were tested by the multiple logistic regression model. Odds ratio and the respective 95% confidence intervals were estimated. All statistical tests were performed using the SAS 9.2 software. Results: The results showed that mothers with greater sense of coherence were 1.82 times more likely to maintain breastfeeding for longer periods (p = 0.02). Conclusions: The identification of mothers with low sense of coherence allows the early intervention of health professionals, contributing to decrease the rates of early weaning in the population.

Resumo Objetivo: Investigar se há associação entre níveis de senso de coerência e desmame precoce. Método: O presente estudo tem natureza quantitativa e delineamento transversal. Foram investigados fatores associados ao desmame precoce (interrupção da oferta do leite materno à criança) em uma amostra de 425 mulheres com idade superior a 18 anos, sem distinção de etnia ou classe social, mães de crianças com até 36 meses, que não fossem gêmeos ou apresentassem deficiências sensoriais ou motoras. Foi feito o teste de qui-quadrado, com nível de significância de 5%, para testar a associação entre a variável dependente (desmame precoce) e as variáveis independentes (socioeconômicas, demográficas e nível de senso de coerência). As variáveis que apresentaram p ≤ 0,20 foram testadas no modelo de regressão logística múltipla. Os odds ratio e os respectivos intervalos de 95% de confiança foram estimados. Todos os testes estatísticos foram feitos com o programa SAS 9.2. Resultados: Os resultados apontaram que mães com maior senso de coerência possuem 1,82 vez mais chance de manter o aleitamento por mais tempo (p = 0,02). Conclusões: A identificação de mães com baixo senso de coerência permite a intervenção precoce dos profissionais de saúde, contribui para diminuir as taxas de desmame precoce na população.

Women's sense of coherence and its association with early weaning.

OBJECTIVE: To investigate whether there is an association between sense of coherence levels and early weaning. METHOD: This study had a quantitative nature and a cross-sectional design. Factors associated with early weaning (interruption of maternal breastfeeding) were investigated in a sample of 425 women older than 18 years, mothers of children up to 36 months of age who were not twins, with no sensory or motor deficiencies, without distinction of ethnicity or social class. The chi-squared test, with a significance level of 5%, was used to evaluate the association between the dependent variable (early weaning) and the independent variables (socioeconomic, demographic factors and sense of coherence level). Variables with p≤0.20 were tested by the multiple logistic regression model. Odds ratio and the respective 95% confidence intervals were estimated. All statistical tests were performed using the SAS 9.2 software. RESULTS: The results showed that mothers with greater sense of coherence were 1.82 times more likely to maintain breastfeeding for longer periods (p=0.02). CONCLUSIONS: The identification of mothers with low sense of coherence allows the early intervention of health professionals, contributing to decrease the rates of early weaning in the population.

Comparative evaluation of 3 microbond strength tests using 4 adhesive systems: Mechanical, finite element, and failure analysis.

STATEMENT OF PROBLEM: Bond strength (BS) values from in vitro studies are useful when dentists are selecting an adhesive system, but there is no ideal measuring method. PURPOSE: The purpose of this in vitro study was to investigate the influence of the evaluation method in the BS between dentin and composite resin. MATERIAL AND METHODS: Molars with exposed superficial dentin (N=240) were divided into 3 groups according to the test: microtensile (µTBS), microshear (µSBS), and micropush-out (µPBS). Each one was subdivided into 4 groups according to the adhesive system: total etch, 3- and 2-step; and self-etch, 2- and 1-step). For the µPBS test, a conical cavity was prepared and restored with composite resin. An occlusal slice (1.5 mm in thickness) was obtained from each tooth. For the µSBS test, a composite resin cylinder (1 mm in diameter) was built on the dentin surface of each tooth. For the µTBS test, a 2-increment composite resin cylinder was built on the dentin surface, and beams with a sectional area of 0.5 mm2 were obtained. Each subgroup was divided into 2 (n=10) as the specimens were tested after 7 days and 1 year of water storage. The specimens were submitted to load, and the failure recorded in units of megapascals. Original BS values from the µTBS and µSBS tests were normalized for the area from µPBS specimens. Original and normalized results were submitted to a 3-way ANOVA (α=.05). The correlation among mechanical results, stress distribution, and failure pattern was investigated. RESULTS: Significant differences (P<.05) were found among the adhesive systems and methods within both the original and normalized data but not between the storage times (P>.05). Within the 7 days of storage, the original BS values from µTBS were significantly higher (P<.001) than those from µPBS and µSBS. After 1 year, µSBS presented significantly lower results (P<.001). However, after the normalization for area, the BS values of the µTBS and µPBS tests were similar, and both were higher (P<.001) than that of µSBS in both storage times. In the µSBS and µTBS specimens, cohesive and adhesive failures were observed, whereas µPBS presented 100% of adhesive failures. The failure modes were compatible with the stress distribution. CONCLUSIONS: The storage time did not affect the results, but differences were found among the adhesives and methods. For comparisons of bond strength from tests with different bonding areas, the normalization for area seemed essential. The microshear bond test should not be used for bond strength evaluation, and the microtensile test needs improvement to enable reliable results regarding stress concentration and failure mode. The micropush-out test may be considered more reliable than the microtensile in the bond strength investigation, as demonstrated by the uniform stress concentration and adhesive failure pattern.

Development and validation of a questionnaire to evaluate infection control in oral radiology.

OBJECTIVES: To create and validate a questionnaire to evaluate infection control in oral radiology. METHODS: The questionnaire was developed after review of the literature, which included published articles and the biosafety protocols available from healthcare agencies. The initial version of the questionnaire was composed of 14 multiple choice questions and was divided into 3 domains on handwashing, disinfection/protection of surfaces and disinfectant used. Content validity was assessed by two expert committees, which reviewed the content and scope of the questionnaire and the relevance of each item, respectively. Reliability was evaluated using test-retest and internal consistency methods with 115 undergraduate dentistry students. Construct validity was assessed using the known-groups technique and factor analysis. The known-groups technique involved 641 undergraduate dentistry students, 20 PhD students and 15 oral radiology professors. In the factor analysis, 3 radiology technicians also participated in addition to the 641 undergraduates, 20 PhD students and 15 oral radiology professors. RESULTS: The content validity results were found to be satisfactory to excellent for the ordinal variables (intraclass correlation coefficient = 0.722-1.000) and good to great for the yes/no questions (kappa = 0.662-0.913) in terms of reliability and good internal consistency (Cronbach's alpha = 0.88). After a factor analysis, some questions were excluded, and the questions were grouped into new domains. Significant differences were observed between answers from different groups. The final version of the questionnaire was composed of nine domains. CONCLUSIONS: The questionnaire created was found to exhibit good psychometric properties for assessing infection control in oral radiology.

Influence of quality of life, self-perception, and self-esteem on orthodontic treatment need.

INTRODUCTION: In this study, we aimed to assess the relationship between normative and perceived orthodontic treatment need associated with quality of life, self-esteem, and self-perception. METHODS: The sample included 248 schoolchildren aged 12 years. The normative aspect of orthodontic treatment was assessed by the Dental Health Component and the Aesthetic Component of the Index of Orthodontic Treatment Need. The subjects were further evaluated for their oral health-related quality of life, self-esteem, and self-perception of oral esthetics. The Aesthetic Component of the Index of Orthodontic Treatment Need was considered as the response variable, and generalized linear models estimated by the GENMOD procedure (release 9.3, 2010; SAS Institute, Cary, NC). Model 1 was estimated with only the intercept, providing the basis for evaluating the reduction in variance in the other models studied; then the variables were tested sequentially, considering P ≤0.05 as the criterion for remaining in the model. RESULTS: In the model, self-perception and self-esteem were statistically significant in relation to the perceived need for treatment. The normative need was significantly associated with the outcome variable and was not influenced by independent variables. CONCLUSIONS: The normative need for orthodontics treatment was not overestimated by the perceived need, and the perceived need was not influenced by sex and the impact on quality of life.

Association between malocclusion and the contextual factors of quality of life and socioeconomic status.

INTRODUCTION: The purpose of this study was to examine associations among malocclusion and the contextual factors of quality of life and socioeconomic status. METHODS: A cross-sectional study was conducted with a population-based sample of 1256 children from 7 to 10 years old. Malocclusion was assessed clinically; oral health-related quality of life (OHRQoL) was assessed using the Brazilian version of the child perceptions questionnaire; socioeconomic status was determined from data made available by the Research and Planning Institute of Piracicaba, São Paulo, Brazil. Initially, bivariate analyses were performed; after this, starting with variables with P ≤0.20, multilevel multiple logistic regression models were estimated, in which the binomial distribution, function of the logistic connection, and criteria for remaining in the model at P ≤0.05 were considered. RESULTS: Of the children, 82.1% had some type of malocclusion. Increased age associated with low socioeconomic status was the determinant for occlusal problems. The determination of low OHRQoL appears to be associated with the socioeconomic status in the individual factors, and increased overjet appears to be associated with factors at the contextual level. CONCLUSIONS: Socioeconomic status and age are risk factors for malocclusion. Of the malocclusions evaluated, increased overjet had the most negative influence on the OHRQoL.

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 × 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 ∆E, multiple comparisons were performed by using Tukey's and Dunnett's tests (α = 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 nanocomposite.

Development of the portuguese version of the instrument for assessing hygiene - HI23 / Desenvolvimento da versão em português do instrumento para avaliação em higiene- HI23

Hand hygiene is part of standard precautions and it has been emphasized that education of this practice depends on the individual's experience in general hygiene. The Hygiene Inventory (HI-23) assess the domains General Hygiene, in the fields of Hands, Personal, Household and Food. Aim: To make the transcultural adaptation of the HI-23 scale for Portuguese­Brazil and to investigate and describe the hygiene behavior according to the HI-23 scale among dental students. Material and Methods: The cross-cultural adaptation process consisted in five steps: two translations, two back translations, review committee, pre-test with a population sample, and reproducibility and reliability of the instrument adapted. For the intra-examiner reproducibility it was applied kappa statistics. The statistical Cronbach's alpha verified the reliability of the HI-23 scale adapted to Portuguese. The adapted instrument was applied to 292 students of Dentistry from 1st to 5th year of graduation from a Faculty of Dentistry. Results: There was good reproducibility (0.43≥κ≥0.81) and good internal consistency (Cronbach's alpha=0.75) for the questions of the questionnaire. The adapted instrument applied among academics, showed that students have good and adequate hygiene pattern for most questions, except for the hygiene in the preparation of food and utensils used to prepare them, in the time spent washing hands, and cleanliness regarding the exchange of clothing (pants/skirt). Conclusion: The transcultural adaptation of the instrument for the Brazilian version was successfully obtained. The instrument can be safely applied to measure the profile of hygiene among professional of the health area.

A higiene das mãos é parte das precauções padrão e tem sido enfatizado que a educação dessa prática depende da experiência individual em higiene geral. O Inventario em Higiene (HI-23) avalia os domínios Higiene Geral, Mãos, Pessoal, Doméstica e na Alimentação. Objetivo: Realizar a adaptação transcultural da escala HI-23 para o português-Brasil e investigar e descrever o comportamento em higiene segundo o HI-23, entre acadêmicos de Odontologia. Material e Métodos: O processo de adaptação transcultural consistiu em cinco etapas: duas traduções; duas retrotraduções, comitê de revisão, pré-teste com uma amostra da população alvo, reprodutibilidade e confiabilidade do instrumento adaptado. Para a reprodutibilidade intraexaminador foi aplicada a estatística kappa. A estatística alfa de Cronbach verificou a confiabilidade da escala HI-23 adaptada para o português. O instrumento adaptado foi aplicado a 292 estudantes de Odontologia do 1º ao 5º ano do curso de graduação de uma Faculdade de Odontologia. Resultados: Houve boa reprodutibilidade (0,43≥k≥0,81) e boa consistência interna (alfa de Cronbach=0,75) para as perguntas do questionário. O instrumento adaptado aplicado entre os acadêmicos, mostrou que os estudantes possuem um padrão de higiene bom e adequado para a maioria das questões, com exceção da higiene no preparo de alimentos e utensílios utilizados para prepará-los, no tempo gasto para lavagem das mãos e no asseio quanto a troca de vestimenta (calça/saia). Conclusão: A adaptação do instrumento para a versão brasileira foi obtida com sucesso. O instrumento pode ser aplicado com segurança para medir o perfil em higiene entre profissionais da área da saúde.

Dental adhesives and strategies for displacement of water/solvents from collagen fibrils.

OBJECTIVES: To evaluate the influence of temperature of evaporation in adhesive systems with different solvents on the apparent modulus of elasticity and mass change of macro-hybrid layers modified by proanthocyanidins (PACs). METHODS: Adhesive resin beams (A) from Single Bond Plus (SB), Excite (EX) and One Step Plus (OS) were prepared after solvent evaporation at 23°C or 40°C (n=12). Macro-hybrid layers (M) (n=12) were prepared using demineralized dentin beams sectioned from extracted human third molars. The demineralized dentin specimens were infiltrated with each one of the three adhesive systems at 23°C or 40°C; with or without prior dentin treatment with PACs for 10min. The apparent modulus of elasticity (E) and mass change (Wmc, %) of adhesives beams and resin-infiltrated specimens were assessed in dry and wet conditions after immersion in water (24h, 1, 3 and 6 months). The E was statistically analyzed by Tukey-Kramer test and the Wmc, % by Kruskal Wallis, and Dunn (α=0.05). RESULTS: Solvent evaporation at 40°C resulted in higher E values for adhesive resin beams at all storage conditions, regardless of the adhesive system (p<0.05). Increased mass loss (3 months: -0.01%; 6 months: -0.05%) was observed in One Step resin beams (p≤0.05). In the macro-hybrid layer models the pretreatment with PACs along with solvent evaporation at 40°C increased E and decreased the Wmc, % (3 months: -2.5; 6 months: 2.75%) for adhesives evaluated over time (p<0.05). No significant differences in ratio (resin/dentin) were found for the macro-hybrid layers (p>0.05). SIGNIFICANCE: Improved solvent evaporation at higher temperature, and increased collagen cross-linking induced by PACs, enhanced the mechanical properties resulting in highly stable macro-hybrid layers over 6 months storage.

Crown fracture: Failure load, stress distribution, and fractographic analysis.

STATEMENT OF PROBLEM: The outcomes from load-to-failure tests may not be applicable to clinical situations. PURPOSE: The purpose of this study was to critically evaluate the efficacy of load-to-failure tests in the investigation of the fracture load and pattern of metal-free crowns. MATERIAL AND METHODS: Four groups were formed from 128 bovine roots restored with metal posts, resin cores, and feldspathic, leucite, or lithium disilicate ceramic systems or polymer crowns. Each group was divided into 4 (n=8) according to the cement: zinc phosphate, self-adhesive resin, autopolymerizing resin, and glass ionomer. Mean fracture loads from compressive tests were submitted to ANOVA and Tukey HSD test. Finite element and fractographic analyses were performed and associated with the fracture load and pattern. RESULTS: Significantly higher fracture load values were obtained for the lithium disilicate ceramic, but finite element and fractographic analyses showed that the cement effect could not be determined. The finite element analysis showed the cement likely affected the fracture pattern, confirmed that stresses in the cements were little affected by the crown materials, and found that the stressed conditions were lowest in the lithium disilicate compared with other crowns for all cement combinations. The stressed conditions in the crowns depended more on the adhesive properties than on the elastic modulus of the cement materials. The level of the stressed condition in the crowns at the occlusal surface was about the same or higher than along their cement interface, consistent with the fractography, which indicated fractures starting at the load point. Higher stress levels in the crowns corresponded with a lower number of catastrophic fractures, and higher stresses in the cements seemed to reduce the number of catastrophic fracture patterns. The highest stressed conditions occurred along the occlusal surface for crown materials with a low elastic modulus or in combination with adhesive cements. CONCLUSIONS: The method used was not appropriate either for investigating the crowns' fracture load and pattern or for stating the role of the cements within the crown-cement-tooth interaction.

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.

The effect of photopolymerization on the degree of conversion, polymerization kinetic, biaxial flexure strength, and modulus of self-adhesive resin cements.

STATEMENT OF PROBLEM: Understanding the effect of the degree of conversion on the mechanical properties of auto- and dual-polymerizing self-adhesive resin cements leads to a better estimation of their performance in different clinical scenarios. PURPOSE: The purpose of this study was to evaluate the effect of photopolymerization on the degree of conversion (DC) and polymerization kinetic of 4 dual-polymerized resin cements, 20 minutes after mixing, and its effects on the mechanical properties (biaxial flexural strength [FS] and modulus [FM]) after short-term aging. MATERIAL AND METHODS: Conventional (RelyX ARC and Clearfil Esthetic Cement) and self-adhesive resin cements (RelyX Unicem and Clearfil SA Cement) were applied to a Fourier infrared spectrometer to assess the DC (n=5) under the following 3 polymerization conditions: direct light exposure (dual-polymerizing mode), exposure through the prepolymerized disk, or autopolymerizing. The polymerization kinetic was recorded for 20 minutes. Then, disk-shaped specimens (n=11) were prepared to evaluate the effect of polymerization on the FS and FM in both extreme polymerization conditions (dual-polymerizing or autopolymerizing). Data were statistically analyzed by 2-way repeated measure ANOVA (DC) and by 2-way ANOVA (FS and FM), followed by the Tukey-Kramer post hoc test (α=.05). RESULTS: Autopolymerizing groups exhibited reduced DC means, whereas intermediate values were observed when resin cements were polymerized through the disk. All groups exhibited higher DC at the end of 20 minutes. The polymerization kinetic revealed a rising curve, and materials, when directly photopolymerized, reached a plateau immediately after light exposure. Regarding the flexural biaxial testing, most of the resin cements were affected by polymerization mode and differences among groups were product dependent. CONCLUSIONS: The resin cements achieved immediate higher DC and mechanical properties when photopolymerized. The total absence of photoactivation may still impair their mechanical properties even after short-term aging.

Efficacy of tooth bleaching with the prior application of a desensitizing agent.

AIM: In the present study, we evaluated the efficacy of bleaching on enamel and opposite dentin surfaces using 35% hydrogen peroxide (HP) with the prior application of a desensitizing agent. METHODS: Thirty bovine dental fragments, with thicknesses of 1 mm enamel and 1.75 mm dentin, were stained in a solution of black tea. The fragments were randomly divided into three groups (n = 10) according to the following protocols: (a) 2% neutral fluoride + bleaching; (b) desensitizing agent + bleaching; and (c) without desensitizer + bleaching. The bleaching efficacy was evaluated four times: after staining with tea (baseline) and after each of the 3 weeks of bleaching, by means of the CIE Lab method using a reflectance spectrophotometer. The data coordinate L* was evaluated by an analysis of repeated measures with PROC MIXED and Tukey-Kramer's test. The ΔE values were subjected to anova and Tukey's test (α = 0.05). RESULTS: The 35% HP treatment showed greater efficacy on deep dentin after removal of the enamel stains, with increasing means during all times in all treatments. CONCLUSION: The use of a desensitizing agent prior to the bleaching session did not affect the mechanism of action of 35% HP with regard to tooth depth.

Characterization of highly osteoblast/cementoblast cell clones from a CD105-enriched periodontal ligament progenitor cell population.

BACKGROUND: It is known that periodontal ligament (PDL) harbors a heterogeneous progenitor cell population at different stages of lineage commitment. However, characterization of PDL stem cells committed to osteoblast/cementoblast (O/C) differentiation remains to be elucidated. The present study is carried out to isolate single cell-derived, cluster of differentiation (CD)105-positive PDL clones and to characterize the clones that present high potential to differentiate toward O/C phenotype in vitro. METHODS: Isolation of single cell-derived colonies (clones) from a CD105-enriched PDL progenitor cell population was performed by the ring-cloning technique. Cell clones were evaluated for their O/C differentiation potential, metabolic activity, and expression of STRO-1 protein. Additionally, the clones that showed potential to O/C differentiation were characterized by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) for expression of runt-related transcriptor factor 2 (RUNX2), alkaline phosphatase, CD105, and CD166 during osteogenic induction. RESULTS: Six PDL-CD105(+) clones were obtained, three being highly O/C clones (C-O) and three others that did not have the ability to produce mineralized matrix in vitro (C-F). The C-O group showed lower metabolic activity compared with the C-F group, and both cell groups were positively immunostained for STRO-1. qRT-PCR analysis demonstrated an increased expression of transcripts for RUNX2 and CD166 during the maturation of C-O cells toward O/C phenotype. CONCLUSIONS: These results provide evidence that PDL-CD105(+) purified progenitor cells comprise a heterogeneous cell population that presents a cell subset with high O/C potential and, further, that surface antigen CD166 is modulated during the O/C maturation of this cell subset.

Photodynamic therapy during supportive periodontal care: clinical, microbiologic, immunoinflammatory, and patient-centered performance in a split-mouth randomized clinical trial.

BACKGROUND: This study investigates the effect of photodynamic therapy (PDT) as monotherapy during supportive periodontal therapy. METHODS: A split-mouth, randomized controlled trial was conducted in patients with chronic periodontitis (N = 22) presenting at least three residual pockets (probing depth [PD] ≥5 mm with bleeding on probing [BOP]). The selected sites randomly received the following: 1) PDT; 2) photosensitizer (PS); or 3) scaling and root planing (SRP). At baseline and 3 and 6 months, clinical, microbiologic (real-time polymerase chain reaction analyses), cytokine pattern (multiplexed bead immunoassay), and patient-centered (regarding morbidity) evaluations were performed. RESULTS: All therapies promoted similar improvements in clinical parameters throughout the study (P <0.05), except that BOP was not reduced in the PS protocol (P >0.05). Lower levels of Aggregatibacter actinomycetemcomitans were observed in the PDT and SRP protocols at 3 months when compared with the PS protocol (P <0.05). An inferior frequency detection of Porphyromonas gingivalis was observed in the PDT protocol at 3 and 6 months and in the SRP protocol at 6 months from baseline (P <0.05). In addition, PDT protocol presented inferior frequency of P. gingivalis at 3 months when compared with the other therapies (P <0.05). Only patients in the PDT protocol exhibited augmented levels of anti-inflammatory interleukin (IL)-4 and reduced proinflammatory IL-1ß and IL-6 throughout the study (P <0.05). Intergroup analyses showed reduced IL-10 and increased interferon-γ and IL-1ß levels in the PS protocol when compared with the other therapies during follow-ups (P <0.05). No differences in morbidity were observed between the therapies (P >0.05), although the need for anesthesia was higher in SRP-treated sites (P <0.05). CONCLUSION: PDT as an exclusive therapy may be considered a non-invasive alternative for treating residual pockets, offering advantages in the modulation of cytokines.