O presente estudo teve por objetivo avaliar o efeito das interações moleculares entre solventes e monômeros com a matriz de dentina desmineralizada, nas alterações das propriedades mecânicas, na taxa de evaporação e na resistência de união (RU). As propriedades mecânicas da dentina desmineralizada foram determinadas através da análise do módulo de elasticidade máximo aparente (EMax) e do relaxamento das tensões (RT). Os resultados permitiram concluir que o Emax foi dependente do tipo de solvente utilizado e do tempo. A taxa de enrijecimento da matriz desmineralizada foi maior para acetona e etanol, intermediária para o ar, metanol e propanol, menor para o HEMA e praticamente nenhuma para água. Da mesma forma, o RT dependeu da solução em que os espécimes foram equilibrados, previamente ao ensaio mecânico, e do tipo de deformação induzida ao espécime. De uma maneira geral, a resposta da matriz desmineralizada (RT) foi maior quando equilibrada em acetona, propanol e etanol, intermediária para HEMA, butanol e metanol e menor para água. A tensão máxima gerada com o tempo foi maior quanto maior a deformação inicial induzida (3-5-10%). A taxa de evaporação e a perda de massa total (%) de misturas experimentais à base de 35%HEMA/65%solventes foram determinadas através da medida de perda de massa em função do tempo, a partir de duas superfícies distintas (cubos de dentina desmineralizados x superfície livre). A taxa de evaporação e a perda de massa foi maior para HEMA/acetona (H/AC) e HEMA/metanol (H/M), intermediária para HEMA/etanol (H/E) e menor para HEMA/água (H/A), sendo esses valores superiores a partir dos cubos de dentina. A RU foi determinada pelo emprego do teste de microtração. Para verificar a influência do aspecto de brilho superficial, foram aplicadas 2 ou 3 camadas de misturas experimentais (35%HEMA/65%solventes) sobre a dentina previamente condicionada. Os maiores valores de RU foram obtidos com a manutenção do brilho superficial para todas as soluções testadas (ou seja, com a aplicação de 3 camadas). A durabilidade da RU obtida com o uso das soluções experimentais (35%HEMA/65%solventes) aplicadas sobre dentina desmineralizada seca foi avaliada após 24hs , 6 meses ou 1 ano de armazenagem em água deionizada. O valor de RU sofreu uma redução com a referida armazenagem para a maioria das soluções testadas. Os maiores valores de RU foram obtidos para H/M e H/E em todos os períodos avaliados. Este estudo desenvolveu uma linha de raciocínio que empregou a teoria dos parâmetros de solubilidade para descrever e analisar as interações moleculares que ocorrem durante a execução de um procedimento adesivo à dentina, procurando estabelecer as relações de causa e efeito. / The present study aimed to test the effect of the molecular interactions between solvent and pure monomers with demineralized dentin matrix on its mechanical properties, evaporation rate and consequent change in the bond strength (BS). The mechanical properties were determined by measuring the apparent maximum modulus of elasticity (EMax) and stress relaxation (SR). The results indicated that the Emax is both time and solvent dependent; accordingly, the SR was both strain and solvent dependent. The weight loss (%) and evaporation rate of experimental mixtures (35%HEMA/65%solvents) were determined by the measuring of weight loss over time from different surfaces (demineralized dentin cubes x free surface). The overall evaporation rate and weight loss were higher for dentin cubes and dependent of solvents. The bond strength (BS) was determined by the microtensile test. The effects of surface shininess on bond strength of experimental primers to dentin were evaluated. Dentin surfaces were acidetched, primed with experimental mixtures in two (not shiny) or three (shiny) coats. For the all primers the presence of a shiny surface significantly improved resin-dentin bond strengths. The influence of storage time in resin dentin bond strength mediated by experimental HEMA/solvent primers was determined. Part of specimens were tested after 24 hour storage in deionized water (control) and remaining specimens were tested after 6 months and 1 year of storage in the same condition. Water storage resulted in reduced bond strength for most of the primers. This study develops a rationale that employs the solubility parameter theory to describe and analyze molecular interactions that occur during adhesive procedure to dentin, seeking to establish the cause-effect relationship.

Orientadores: Américo Bortolazzo Correr, Mário Alexandre Coelho Sinhoreti / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-09-11T21:16:44Z (GMT). No. of bitstreams: 1 Feitosa_VictorPinheiro_M.pdf: 1748839 bytes, checksum: 19481c535f5edd50191d7995d2529e9f (MD5) Previous issue date: 2011 / Resumo: O objetivo neste estudo foi avaliar o efeito do tempo de fotoativação de adesivos de passo único e da pressão pulpar simulada na resistência da união e nanoinfiltração de compósitos resinosos à dentina humana. Este estudo foi separado em 2 Capítulos. No Capítulo 1 verificada a influência do aumento do tempo de fotoativação para um sistema adesivo autocondicionante de passo único (Clearfil S3 Bond) submetido ou não à pressão intrapulpar simulada. Foram obtidas superfícies planas em dentina profunda de terceiros molares, os quais foram separados em quatro grupos (n=5). O adesivo foi aplicado seguindo a recomendação do fabricante e fotoativado por 10 segundos (recomendação fabricante) ou 40 segundos (tempo de fotoativação aumentado). A fotoativação realizada com o aparelho de luz de lâmpada halógena XL-2500 com irradiância de 600 mW/cm². Os dentes foram restaurados com o compósito nanoparticulado Filtek Z350. Metade dos grupos foi armazenada sob pressão pulpar simulada e a outra metade armazenada em água, sem pressão pulpar simulada. Após 24 horas, os dentes foram cortados em palitos e submetidos ao teste de resistência da união por microtração. Os dados foram submetidos à análise de variância dois fatores e teste de Tukey (p<0.05). resultados mostraram que a pressão pulpar diminuiu significativamente a resistência união para ambos os tempos de fotoativação. O aumento do tempo de fotoativação de 40s resultou em significante aumento de resistência para os grupos com pressão pulpar; entretanto, não foi significativo para os grupos sem pressão. Pode ser concluído que pressão pulpar simulada diminuiu a resistência da união, mas o aumento do tempo fotoativação melhorou a resistência da união a dentina nos grupos armazenados sob pressão pulpar. No Capítulo 2 o objetivo foi avaliar in vitro uma nova metodologia para simular pressão pulpar comparada à metodologia tradicional. Foram utilizados quatro sistemas adesivos (Clearfil S3 Bond, Clearfil SE Bond, Adper Single Bond Plus, and Scotchbond Multi-Purpose), que foram aplicados em superfícies planas de dentina profunda de terceiros molares. Após a restauração com compósito as amostras foram armazenadas em água sem pressão pulpar, submetidas à pressão pulpar convencional ou pela nova metodologia pressão pulpar. Após 24 horas, os dentes foram cortados em palitos e submetidos ao teste de resistência da união por microtração. Os dados foram submetidos à análise de variância dois fatores e teste de Tukey (p<0.05). Os resultados mostraram que os adesivos simplificados (autocondicionante de passo único e de técnica úmida de dois passos) foram negativamente influenciados pela pressão pulpar, mas não houve diferença significativa entre as duas metodologias de simulação da pressão pulpar. Os adesivos autocondicionante de dois passos e de técnica úmida de três passos não foram afetados pela simulação pressão pulpar (p>0,05). O padrão de nanoinfiltração mostrou similaridade entre as duas metodologias. Os maiores valores de resistência da união foram apresentados pelo Scotchbond Multi-Purpose e os menores pelo adesivo Clearfil S3 Bond. Pode ser concluído que ambas as metodologias diminuíram a resistência da união dos adesivos de técnica simplificada, sem haver diferença entre a metodologia experimental e a metodologia convencional para resistência da união e padrão de nanoinfiltração. Conclui-se que aumento do tempo de fotoativação melhorou a união nos adesivos autocondicionante simplificados sob pressão pulpar simulada. Além disso, a metodologia experimental simulação da pressão pulpar pode ser utilizada em substituição a metodologia tradicional. / Abstract: The aim of this study was to evaluate the extended photoactivation time for one-step self-etch adhesives and the simulated pulpal pressure applied into two methods on bond strength of direct restoration of composite resin to human dentin. This work was divided into two Chapters. The Chapter 1 analyzed the influence of extended photoactivation time of one-step self-etch adhesive Clearfil S3 Bond with and without conventional simulated pulpal pressure. It was obtained flat surfaces in deep dentin from extracted third molars and they were divided randomly in four groups (n=5). The adhesive was used in agreement with manufacturer's recommendation (photoactivation time 10s) and with the extended photoactivation time to 40s, after the composite restoration was built up with nanofilled composite resin Filtek Z350. The photoactivation procedures were realized with quartz-tungsten halogen lamp XL-2500 with a standard irradiance of 600mW/cm². Half of the samples were submitted to simulated pulpal pressure and the other half was stored in water without pulpal pressure. After 24 hours, the samples were cut into sticks and the microtensile bond strength test was performed. The results were submitted to two-way ANOVA and Tukey's test (p<0.05). Pulpal pressure decreased bond strength for both photoactivation times and the extended photoactivation time showed significant increase in bond strength for groups with simulated pulpal pressure, however the increase was not statistically significant for groups without pulpal pressure. It can be concluded that simulated pulpal pressure decreased bond strength, however the extended photoactivation time improved the bonding under pulpal pressure simulation. In Chapter 2, a new methodology to simulate pulpal pressure was tested in comparison with the traditional methodology and control groups without pulpal pressure. One adhesive system of each of the four approaches was applied in flat surfaces in deep dentin of extracted molars as in Chapter 1. After the composite was built up, samples were stored in water storage without pulpal pressure, under conventional simulated pulpal pressure or under the new methodology to simulate pulpal pressure. After microtensile test, the results showed no differences between two methodologies of simulated pulpal pressure (p<0.05) and nanoleakage patterns were similar for both methods. Simplified adhesives were more influenced by pulpal pressure than multi-step adhesives, showing significant decrease in bond strength. The highest bond strength values were obtained by the three-step adhesive Scotchbond Multi-Purpose and the lowest were obtained by the one-step adhesive Clearfil S3 Bond. In conclusion, the extended photoactivation time improves bonding for one-step self-etch adhesives under simulated pulpal pressure. In addition, the experimental methodology to simulate pulpal pressure can be used in replacing the conventional methodology. / Mestrado / Materiais Dentarios / Mestre em Materiais Dentários

Objective: Natural tooth is composed of different structures with different optical properties. The aim of this observational study is to investigate the difference between the dentin color and the tooth color in CIE LAB* color coordinates and Delta E at incisal, middle and cervical thirds of maxillary anterior teeth . Methods: Sound natural extracted maxillary anterior teeth were used. Horizontal and vertical grooves were cut into enamel to be used as a reference for the measurement locations. Teeth were mounted on a dentoform with a bite registration material (Regisil, DENTSPLY). An image of the tooth was captured with an image-based spectrophotometer (Spectroshade Micro, MHT Optic Research). The thickness of enamel for each tooth was determined with a radiograph. Enamel was grinded to expose the facial dentin with a diamond bur. Then an image of the facial dentin was captured. The color of the tooth and the dentin was compared based on the CIE LAB color space at nine locations in the incisal, middle and cervical thirds. Color difference between the whole tooth color measurement and the corresponding dentin color measurement was calculated for each tooth. Results: 89 maxillary extracted anterior teeth were included in the study. Based on the paired-samples t-test, the data provided evidence that there was a significant difference between the color of dentin and the color of tooth (p<0.05 in each instance), except for the color parameter L* measured at the incisal third (p=0.9251). For parameters L* and b*, the results indicated that the mean color of dentin was greater than the mean color of tooth, while it was lower for parameter a*. Conclusion: The results of this study suggest that the dentin is higher in value than the tooth. In addition, the dentin color was higher in b* but lower in a* than the tooth color. The difference between the color of the tooth and the dentin was the least in the cervical third.

Die Versorgung von Zahnhartsubstanzdefekten mittels indirekter Restaurationen über Befestigungszemente gehört in Zahnarztpraxen zur alltäglichen Arbeit. Eine stetige Weiterentwicklung der techniksensitiven adhäsiven Befestigungssysteme ergibt eine Bandbreite an unterschiedlichen Befestigungssystemen auf dem Dentalmarkt. Ziel dieser In vitro Studie ist es deshalb, die Haftfestigkeit von adhäsiven, selbstadhäsiven und konventionellen Befestigungssystemen zu indirekten Restaurationsmaterialien sowie Echtzähnen (Dentin), mit und ohne künstliche Alterung, zu überprüfen. Die Haftfestigkeit wurde mithilfe eines Scherfestigkeitstests nach DIN EN ISO 29022:2013 überprüft. Es wurden die Befestigungsmaterialien Panavia™ SA Universal, Visalys® CemCore, G-Cem LinkForce™, Bifix® SE, als Kontrollgruppe Panavia™ V5 und Ketac™ Cem Plus zu den Restaurationsmaterialien Ceramill® zolid ht+ PS (Zirkoniumdioxidkeramik), Enamic® (Hybridkeramik), IPS e.max® CAD (Lithiumdisilikat-Glaskeramik) und Dentin untersucht. Bei den selbstadhäsiven Befestigungszementen Panavia™ SA und Bifix® SE wurden zusätzlich zwei Gruppen zu Dentin mit Konditionierung getestet. Die Befestigungszemente wurden zylinderförmig auf die Restaurationsmaterialien aufgebracht und ausgehärtet. Die Proben mit Alterung wurden zusätzlich für 10.000 Zyklen in einem Thermocycler bei 5°C/55°C gealtert, anschließend wurden alle Proben abgeschert. Die Bruchart wurde in adhäsiver, kohäsiver und gemischter Bruch eingeteilt. Die Ergebnisse belegen zwischen den getesteten Restaurationsmaterialien und Befestigungszementen Unterschiede. Thermocycling hat einen negativen Einfluss auf die Haftfestigkeit. Generell zeigten die Befestigungsmaterialien geringere Haftwerte zu Dentin als zu den Restaurationsmaterialien. Durch zusätzliche Vorbehandlung des Dentins bei Bifix® SE konnten ähnlich hohe Haftfestigkeiten wie zu den Restaurationsmaterialien gemessen werden. Panavia™ V5 zeigte als Kontrollgruppe zu allen Materialien konstante Haftwerte. / The treatment of dental hard tissue defects with indirect restorations is part of the everyday work in dental practices. A continuous further development of adhesive luting systems results in a wide range of different systems on the dental market. Thus the aim of this in vitro study is to test bond strength of adhesive, self-adhesive and conventional systems to CAD/CAM restoration materials and dentin, with and without artificial aging. The adhesive strength was examined using a shear bond strength test. Panavia™ SA Universal,Visalys® CemCore,G-Cem LinkForce™,Bifix® SE, as control group Panavia™ V5 and Ketac™ Cem Plus were luted to CAD/CAM restoration materials Ceramill® zolid ht+ PS (zirconiumdioxide ceramics), Enamic® (hybrid ceramics), IPS e.max® CAD (lithium disilicate glass ceramic) and dentin. In the case of the self-adhesive resin cements Panavia™ SA and Bifix® SE, two extra groups were tested concerning their bond strength to dentin with conditioning. In accordance with DIN EN ISO 29022:2013 cements were applied to the restoration materials and cured. Samples with artificial aging were additionally aged for 10.000 cycles by thermocycling at 5 °C/55 °C, then all samples were subjected by the shear bond strength test. The fracture type was divided into adherent, cohesive and mixed fractures. The results showed differences between tested restoration materials and luting agents. Thermocycling has a negative impact on shear bond strength. Overall, luting agents showed lower adhesion values to dentin than to CAD/CAM restoration materials. Additional pretreatment of the dentin at Bifix® SE presented similarly high bond strengths as for the restoration materials. As a control group, Panavia™ V5 demonstrated constant adhesive bond strength to all restoration materials.

Bacteria are implicated in endodontic infections. They not only infect the root canal lumen but also invade the dentinal tubules where they may remain untouched by contemporary chemomechanical preparation during root canal therapy. The contentious issue is whether the bacteria within these tubules contribute to secondary infections. Many studies have shown that clinicians fail to completely eradicate them during root canal therapy. At present there are no techniques available to detect the effectiveness of the current chemomechanical treatment regime within dentinal tubules. It is difficult to detect bacteria within the dentinal tubules. Culturing techniques have been used routinely as they are versatile and easy to use. However, they are unable to show the distribution of the bacteria within the dentinal tubules. Scanning electron microscopy, on the other hand, shows detailed surface structure in association with bacteria. Histological examination of root dentine specimens under the light microscope also shows the distribution of bacteria within the specimen but not viability. The dilemma posed by these existing techniques is that the results offer limited information; either demonstrating bacterial viability or bacterial distribution within specimens. No techniques able to show both the viability and the distribution of bacteria within the dentinal tubules have been reported to date. Fluorescent stains, in particular SYTO�9 and propidium iodide (LIVE/DEAD� Baclight[TM] viability kit, Molecular Probes Inc., Eugene, Oregon), have made it possible not only to stain bacteria but to differentiate live and dead bacteria. The combination of these two stains has yet to be applied to dental hard tissue in situ and they provide the basis for this investigation. The aim of this study was to evaluate the potential of the LIVE/DEAD� Baclight[TM] stains in conjuction with confocal laser scanning microscopy in the development of a technique to evaluate the viability and distribution of bacteria within dentinal tubules. This was extended to demonstrate the application of this technique by examining three different means of root canal disinfection both qualitatively and quantitatively. An important aspect of this study was to maintain bacterial viability, as well as to get maximum bacterial invasion into dentinal tubules. Results indicated that when the root canals were instrumented with Protaper� files and then irrigated with sodium hypochlorite (NaOCl) and ethylene diaminetetraacetic acid with cetrimide (EDTAC), there was more bacterial invasion into the dentinal tubules than when the root canals were only irrigated with NaOCl and EDTAC. Daily replenishments of nutrients resulted in deeper bacterial invasion into the dentinal tubules. Bacteria colonized the dentinal tubules up to a distance of 594 � 133 [mu]m from the canal. In the untreated tubules, 96 � 4 % of bacteria remained viable (green-fluorescent), whereas the Amoxicillin-treated tubules contained 94 � 6 % dead (red-fluorescent) bacteria. The calcium hydroxide-treated tubules resulted in 92 � 7 % bacterial death while the laser-treated tubules contained 81 � 12 % dead cells, frequently displaying an inner zone of dead cells surrounded by an outer zone of viable cells. The application of the fluorescent stains combined with confocal microscopy offers a new method for assessing the in vitro efficacy of root canal disinfection regimens.

Thesis (Ph.D)--University of Hong Kong, 1997. / A journal entitled Three-dimensional reconstruction of microleakage pattern using a sequential grinding technique by M.S. Gale, B.W. Darvell and G.S.P. Cheung bound at back of the thesis. Includes bibliographical references (leaves 495-520) Also available in print.

Thesis (Ph.D)--University of Hong Kong, 1997. / Includes bibliographical references (leaves 495-520) Also available in print.

Bis-GMA-containing resin-composites undergo biodegradation by human saliva derived esterases, yielding Bis-hydroxy-propoxy-phenyl-propane (Bis-HPPP). The hypothesis of this study is that the exposure of dental restorations to saliva-like esterase activities accelerates marginal bacterial microleakage. Resin-composites (Scotchbond, Z250, 3M) bonded to human dentin were incubated in either buffer, or dual-esterase media (pseudocholinesterase/cholesterol-esterase; PCE-CE) with activity levels simulating that of human saliva, for up to 90 days. Incubation solutions were analyzed for resin degradation by-products using high-performance liquid-chromatography. Post-incubation, specimens were suspended in a chemostat-based biofilm fermentor cultivating Streptococcus mutans NG8 for 7 days. Bacterial microleakage was assessed by confocal laser scanning microscopy. Bis-HPPP production, as well as depth and spatial volume of bacterial cell penetration within the interface increased with incubation time. Biodegradation and bacterial microleakage were significantly higher for 30 and 90 day PCE-CE vs. buffer incubated groups (p<0.05). Conclusion: An overall decline in interfacial integrity was observed following exposure to human saliva-like esterases over time.

Bis-GMA-containing resin-composites undergo biodegradation by human saliva derived esterases, yielding Bis-hydroxy-propoxy-phenyl-propane (Bis-HPPP). The hypothesis of this study is that the exposure of dental restorations to saliva-like esterase activities accelerates marginal bacterial microleakage. Resin-composites (Scotchbond, Z250, 3M) bonded to human dentin were incubated in either buffer, or dual-esterase media (pseudocholinesterase/cholesterol-esterase; PCE-CE) with activity levels simulating that of human saliva, for up to 90 days. Incubation solutions were analyzed for resin degradation by-products using high-performance liquid-chromatography. Post-incubation, specimens were suspended in a chemostat-based biofilm fermentor cultivating Streptococcus mutans NG8 for 7 days. Bacterial microleakage was assessed by confocal laser scanning microscopy. Bis-HPPP production, as well as depth and spatial volume of bacterial cell penetration within the interface increased with incubation time. Biodegradation and bacterial microleakage were significantly higher for 30 and 90 day PCE-CE vs. buffer incubated groups (p<0.05). Conclusion: An overall decline in interfacial integrity was observed following exposure to human saliva-like esterases over time.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 96-105).