Effect of the casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) associated to adhesive procedures on bond strength of a pit and fissure sealant

Orientador: Flavio Henrique Baggio AguiarDissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Odontologia de PiracicabaResumo: O objetivo deste trabalho foi investigar, in vitro, o efeito da aplicação de uma pasta contendo fosfopeptídeo de caseína - fosfato de cálcio amorfo (CPP-ACP) (MI Paste - MI) previamente ao protocolo adesivo na resistência da união de um selante resinoso de fóssulas e fissuras ao esmalte dental humano. Foram utilizados 98 espécimes de esmalte proximal de terceiros molares totalmente erupcionados, divididos em 14 grupos experimentais (n=7): G1/G8- condicionamento ácido (CA) (Scotchbond Etchant), sem a aplicação de sistema adesivo; G2/G9- CA + resina hidrófoba de um sistema adesivo convencional de três passos (Scotchbond Multipurpose Plus); G3/G10- CA + sistema adesivo convencional de dois passos (Single Bond 2); G4/G11 - CA + sistema adesivo autocondicionante de passo único (Clearfil S3 Bond); G5/G12- CA + sistema adesivo autocondicionante de dois passos (Clearfil SE Bond); G6/G13- sistema adesivo autocondicionante de dois passos; G7/G14- adesivo autocondicionante de passo único. MI foi aplicada previamente ao protocolo adesivo apenas nos grupos de G1 a G7. Após selamento das superfícies (FluroShield), foram confeccionados blocos retangulares (palitos) (~0,7mm2 de área seccional) para o ensaio de microtração. O teste foi efetuado imediatamente após confecção das amostras por meio da Máquina de Ensaio Universal, na velocidade de 0,5 mm/min. Após, o padrão de fratura foi analisado por meio de Microscopia Eletrônica de Varredura (MEV). Os valores de resistência da união foram analisados por meio de ANOVA dois fatores com parcela subdividida. A aplicação da pasta contendo CPP-ACP previamente aos sistemas adesivos convencionais e àqueles autocondicionantes sem condicionamento ácido prévio aumentou os valores de resistência da união. Houve predomínio de fraturas mistas nos grupos que receberam MI Paste, ao passo que, naqueles em que não se aplicou MI Paste a maior prevalência foi de fraturas adesivas. O contato do esmalte com CPP-ACP anteriormente à aplicação dos sistemas adesivos é um método eficaz para aumentar a resistência de união entre esmalte e selantes de fóssulas e fissuras.Abstract: This study evaluated the effect of applying a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) containing paste (MI Paste - MI) previously to adhesive procedures on the microtensile bond strength of a pit and fissure sealant to human enamel in vitro. Ninety eight fragments were obtained from proximal surfaces of totally erupted third molars. Specimens were divided into 14 experimental groups (n=7): G1/G8- phosphoric acid conditioning (PA) (Scotchbond Etchant) and no adhesive system; G2/G9- PA + hydrophobic resin of a three step adhesive system (Scotchbond Multipurpose Plus); G3/G10- PA + etch-and-rinse two-step adhesive system (Single Bond2); G4/G11- PA + all-in-one adhesive (Clearfil S3-Bond); G5/G12- PA + two-step self-etching adhesive system (Clearfil SE-Bond); G6/G13- all-in-one adhesive; G7/G14- two-step self-etching adhesive system. MI was applied on the enamel before adhesive strategies only for groups from G1 to G7. After sealing (FluroShield), beams with approximately 0.7 mm2 of sectional area were cut for microtensile test, which was executed trough a universal test machine at a speed of 0.5 mm/min. Fractured specimens were analyzed by scanning electronic microscopy to determine failure modes. Bond strength data was statistically analyzed by two-way ANOVA with subparcels. Groups which MI was applied on the enamel followed by sealant bonding with etching-and-rinse and self-etching adhesives without additional enamel acid etching presented higher means than other which MI was not applied. Higher frequency of cohesive failures was observed for groups with MI, while adhesive fractures were more prevalent in groups without MI. Applying a CPP-ACP containing paste before adhesive systems to the enamel is an effective method to increase bond strength of the sealant tested.MestradoDentísticaMestre em Clínica Odontológic

Influência do tipo de compósito e tempo de exposição aos raios-x na produção de artefatos radiográficos em modelo de restaurações classe II

Aim: To evaluate the effect of the exposure time and the type of composite in the production of radiographic artifact at the tooth / restorative interface. Materials and Methods: In 20 healthy bovine incisors, cavity preparations and class II restorations were made using composite resins Filtek Bulk Fill One (group 1) and Filtek Z350 (group 2). Then, the teeth were exposed to obtain digital radiographs, varying the exposure time by 0.07, 0.10, 0.14, 0.20 and 0.25s. The images were evaluated for investigation of the presence of artifact through the analysis of the modified number of pixels (QPXD) and the average gray value in class II (MGVR) restorations, using the Image J software (National Health Institute). Results: The presence of artifact was observed in all evaluated samples, regardless of the type of restorative material and the exposure time employed. There was no statistically significant difference in QPXD and MGVR between the resins used (ANOVA 2 factors, p p> 0.05). The MGVR analysis indicated that there were no statistically significant differences between resins or between exposure times (p> 0.05). There was a correlation between QPXD and MGVR (r = 0.29) for Filtek Bulk Fill One resin. Discussion: This study reveals the importance of attention to the region of the tooth-restoration interface by the Surgeon-Dentist, who must combine the radiographic findings diagnosed using digital tools to clinical signs in order to compose a unique therapeutic project with a real need for intervention, if there is such need. Conclusion: The presence of altered pixels on dentin in the region of the tooth-restoration interface was identified in all specimens. The variation in the exposure time as well as the type of the restorative composite did not influence the increase or decrease of QPXD and neither in MGVR. However, there was a correlation between QPXD and MGVR for Filtek Bulk Fill One resin.Objetivo: Avaliar o efeito do tempo de exposição e do tipo de compósito na produção de artefato radiográfico na interface dente/material restaurador. Materiais e Métodos: Em 20 incisivos bovinos hígidos foram feitos preparos cavitários e restaurações classe II utilizando resinas compostas Filtek Bulk Fill One (grupo 1) e a Filtek Z350 (grupo 2). Em seguida, os dentes foram expostos para obtenção das radiografias digitais, variando o tempo de exposição em 0,07, 0,10, 0,14, 0,20 e 0,25s. As imagens foram avaliadas para investigação da presença de artefato através da análise do número de pixels modificado (QPXD) e do valor médio de cinza nas restaurações de classe II (MGVR), utilizando o software Image J (Instituto Nacional de Saúde, Bethesda, MD, EUA). Resultados: Observou-se a presença de artefato em toda amostra avaliada, independente de tipo de material restaurador e tempo de exposição empregado. Não se observou diferença estatisticamente significativa na QPXD e nos MGVR entre as resinas utilizadas (ANOVA 2 fatores, p p>0,05). A análise do MGVR indicou que não houve diferenças estatisticamente significativas entre as resinas nem entre os tempos de exposição (p>0,05). Observou-se uma correlação entre a QPXD e o MGVR (r=0,29) para a resina Filtek Bulk Fill One. Discussão: Como significado clínico, o presente estudo revela a importância da atenção à região da interface dente-restauração por parte do Cirurgião-Dentista, o qual deve aliar os achados radiográficos diagnosticados com o auxílio de ferramentas digitais aos sinais clínicos, para compor um projeto terapêutico singular com uma real necessidade de intervenção, caso haja. Conclusão: Foi identificado a presença de pixels alterados sobre a dentina na região da interface dente-restauração em todos os corpos de prova. A variação do tempo de exposição como também o tipo do compósito restaurador não influenciou no aumento ou diminuição do QPXD e nem tão pouco no MGVR. Contudo houve correlação entre o QPXD e o MGVR para a resina Filtek Bulk Fill One

CPP–ACP pretreatment effect on microshear bond strength of simplified etch-and-rinse adhesive systems plus a flowable composite to enamel

This study evaluated the effect of a casein phosphopeptide–amorphous calcium phosphate based paste (MI Paste) on the microshear bond strength (MSBS) of different simplified etch-and-rinse adhesive systems on enamel. Roots were removed from 90 bovine incisors, and the facial enamel was ground flat. Teeth were randomized into nine groups, according to the enamel pretreatment (without or with application of MI Paste for 1 or 2 min) and the adhesive system used (Single Bond, Stae, or Ambar). Composite cylindrical blocks (2 mm height × 1 mm diameter) were built, stored in water for 24 h, and subjected to the microshear test in a universal testing machine with a load of 0.5 mm/min. Failure modes were analyzed using scanning electron microscopy. Data were submitted for statistical analysis by a two-way ANOVA, followed by multiple comparisons with Tukey test (α = 5%). The Ambar group presented the highest MSBS values. Pretreatment with MI Paste for 2 min improved bonding in the Single Bond and Stae groups. In all groups, adhesive failures were most frequent. In conclusion, Ambar presented better performance and did not need any pretreatment. The enamel MSBS of the other simplified adhesive systems was improved by the pretreatment with MI Paste, depending on the time of application29210911

Effect of irradiation times on the polymerization depth of contemporary fissure sealants with different opacities

The aim of this study was to evaluate the depth of curing of 10 contemporary blue light-activated dental flowable materials at several opacities, influenced by different irradiation times using FT-IR spectroscopy. Fifty-five specimens (n = 5) with a 5-mm diameter and 1-mm thickness of translucent (Opallis Flow T), yellowed (Master Flow A2; Opallis Flow A2; Natural Flow A2; Fluroshield Yellowed), and opaque materials (Master Flow OA2; Natural Flow O; Opallis Flow OA3.5; Opallis Flow OP; Fluroshield White) were obtained at six curing times (10s, 20s, 30s, 40s, 50s, and 60s) using a high-intensity LED (Coltolux, Coltène/Whaledent). The degree of conversion (DC) (%) was obtained using the Nexus 470 FTIR Spectrometer (Nicolet Instruments, USA). The FTIR-ATR spectra for uncured and cured samples were analyzed using a ZnSe crystal. The top and bottom surfaces of the cured specimens were analyzed to obtain the depth of curing. Two-way ANOVA was used to analyze the data. The highest curing depth was obtained by Natural Flow OA2, while the lowest was shown by Master Flow OA2. The shortest curing time generated similar depths of cure in comparison with the most extensive for Opallis Flow A2 and Fluroshield Yellowed. Therefore, depth of curing, influenced by the irradiation time, was dependent on the materials. Using the Natural Flow OA2 opaque sealant and the 10-s curing time for Opallis Flow A2 and Fluroshield Yellowed may represent alternative approaches to sealing tooth fissures

Impact of adhesive and photoactivation method on sealant integrity and polymer network formation

We evaluated the influence of photoactivation method and hydrophobic resin (HR) application on the marginal and internal adaptation, hardness (KHN), and crosslink density (CLD) of a resin-based fissure sealant. Model fissures were created in bovine enamel fragments (n = 10) and sealed using one of the following protocols: no adhesive system + photoactivation of the sealant using continuous light (CL), no adhesive system + photoactivation of the sealant using the soft-start method (SS), HR + CL, or HR + SS. Marginal and internal gaps and KHN were assessed after storage in water for 24 h. The CLD was indirectly assessed by repeating the KHN measurement after 24 h of immersion in 100% ethanol. There was no difference among the samples with regard to marginal or internal adaptation. The KHN and CLD were similar for samples cured using either photoactivation method. Use of a hydrophobic resin prior to placement of fissure sealants and curing the sealant using the soft-start method may not provide any positive influence on integrity or crosslink density

Comparison of the clinical efficacy of at-home and in-office bleaching

Background: There is a lack of consensus regarding the superiority of the two vital bleaching methods. Aims: To compare the clinical efficacies of the two methods at home and in- office. Materials & Methods: Data was collected from PubMed, Embase, Cochrane, Lilacs, Scielo and BBO. Two independent researchers selected the articles, ie., only randomized clinical trials. Where there was no initial agreement, researchers reached a consensus. The search strategy initially yielded 483 titles. After the exclusion by titles, 408 articles remained and following the abstract-based evaluation, only 5 were subjected to further analysis. Results: The most of the authors did not find any statistically significant differences between at home and in-office bleaching procedures. Conclusion: Both the at home and in-office methods alone or in association are equally efficient when a 14 day protocol is used

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1β, TNF-β, GPX, FGF-2 and osteocalcin in rats

Objectives: To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. Material and Methods: Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). Results: The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). Conclusions: Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days

Influência de protocolos adesivos simplificados na resistência ao cisalhamento de bráquetes ortodônticos

O objetivo deste trabalho foi avaliar in vitro a resistência ao cisalhamento de bráquetes ortodônticos metálicos. Para isto, foram utilizados três sistemas de fixação: resina convencional ortodôntica Transbond XT- 3M ESPE, cimento resinoso Rely-X U100-3M e resina Flow Filtek Z350 XT-3M ESPE. Foram selecionados 30 dentes bovinos recém-extraídos, com esmalte, sem defeitos e sem manchas. Os dentes foram limpos individualmente e armazenados em solução de timol 0,5% em temperatura ambiente por sete dias. Logo após, foram divididos aleatoriamente em 3 grupos, cada um com 10 dentes. Foi realizada profilaxia e em seguida escolhida a área mais plana do dente para fazer o condicionamento com ácido fosfórico a 37%, aplicação do adesivo selecionado e colagem do bráquete ortodôntico com o sistema de fixação selecionado. Utilizou-se um aparelho de luz led Radii (SDI) para fotoativar o sistema de fixação durante o procedimento da colagem. Em seguida, os dentes foram submetidos ao teste de resistência ao cisalhamento, em uma máquina eletrônica de ensaios eletromecânicos SHIMADZU AG-I, (10KN), com velocidade de pressão de 0,5mm/min e carga de ruptura registrada em Megapascal (MPa). Os resultados foram submetidos a estatística, utilizando análise de variância (ANOVA) e teste de Tukey ao nível de 5%de significância. Baseado nos resultados obtidos, os bráquetes apresentaram diferença adesiva de resistência ao cisalhamento. Pôde-se concluir que a resina ortodôntica transbond XT-3MESPE mostrou ser a mais resistente ao cisalhamento dos bráquetes ortodônticos