Correlation between clinical performance and degree of conversion of resin cements: a literature review

AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used

Technical aspects involved in the removal of calcium hydroxide intracanal medication

A busca por alternativas de controle microbiano tem sido uma preocupação constante na Endodontia. O objetivo desse artigo é revisar aspectos técnicos relacionados à remoção da medicação intracanal de hidróxido de cálcio. Como auxiliar da sanificação e controle microbiano, a medicação intracanal de hidróxido de cálcio (Ca(OH)2) é a mais indicada nos casos de polpas necróticas e lesões periapicais crônicas. Entretanto, ela não é facilmente removida do canal radicular e os resíduos oriundos dessa medicação podem afetar a qualidade da interface da obturação endodôntica, em especial quando um cimento obturador resinoso é utilizado. A eficácia de remoção da medicação intracanal de Ca(OH)2 tem sido investigada usando vários produtos e técnicas, tais como a utilização de substâncias químicas auxiliares, recapitulação com instrumento memória e ativação ultrassônica passiva. A literatura é unânime em reconhecer a permanência de resíduos em todos os métodos relatados, principalmente no terço apical, sendo que a ativação ultrassônica tem demonstrado melhores resultados, na remoção da medicação intracanal de Ca(OH)2.The search for an effective method of microbial control has been a constant concern in endodontics. The aim of this literature review was to discuss the technical aspects related to the removal of intracanal calcium hydroxide. As an adjunct to sanifi cation and microbial control, calcium hydroxide [Ca(OH)2] intracanal medication is more suitable in cases of pulp necrosis and chronic periapical lesions. However, it is not easily removed from the root canal, and its residue can affect the interface quality of the endodontic fi lling, especially when a resin sealer is used. The removal effi cacy of Ca(OH)2 medication has been investigated using several products and techniques, such as auxiliary chemicals, recapitulation with memory instrument and passive ultrasonic activation. The literature unanimously recognizes the persistence of residues with all the reported methods, particularly in the apical third, and ultrasonic activation has shown the best results in the removal of Ca(OH)2 medication

Correlation between clinical performance and degree of conversion of resin cements: a literature review

However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photocured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. 6SHFL¿F PHDVXUHV DUH WR EH WDNHQ WR HQVXUH D KLJKHU '& RI WKH OXWLQJ V\VWHP WR EH XVH

Correlation between water uptake and biaxial flexural strength in restorative composites

Embora o envelhecimento de compósitos resinosos tenha sido o objeto de investigação de diversos estudos, a correlação entre resistência e sorção de água não foi estabelecida. Portanto, o objetivo do presente estudo foi verificar se existe uma correlação estatisticamente significativa entre a resistência à fl exão biaxial e o ganho de peso devido a sorção de água para dois compósitos comerciais, um à base de metacrilatos e outro à base de silorano. Discos (15 mm de diâmetro por 1 mm de espessura) foram confeccionados com Filtek Z250 ou Filtek Silorane (ambos da 3M ESPE) e armazenados a seco por 30 dias. Em seguida, eles foram pesados em uma balança analítica e imersos em água destilada a 37°C por 1, 2, 5, 7, 30 ou 60 dias (n = 10). Após o período de imersão, os discos foram novamente pesados e imediatamente fraturados em um dispositivo do tipo “pistão sobre três esferas”. Os dados de ganho de massa (em porcentagem) e resistência à fl exão biaxial foram submetidos a ANOVA de dois fatores / teste de Tukey e teste de correlação de Pearson (a = 0,05). O ganho de massa foi semelhante para os dois compósitos para um dado período de armazenamento e não variou significativamente entre um e sete dias. Para o Filtek Z250, a resistência diminuiu gradualmente com a imersão prolongada, ao passo que, para o Filtek Silorane, ela diminuiu abruptamente entre 30 e 60 dias. Correlações estatisticamente significativas foram encontradas entre resistência e ganho de massa para ambos os compósitos. Entretanto, uma correlação mais forte foi encontrada para o Filtek Z250 (r = -0,706, p < 0,001) comparado com o Filtek Silorane (r = - 0,361, p < 0,01). Portanto, foi possível concluir que a resistência é linearmente dependente do ganho de água e que essa correlação é material-dependente.Though aging of resin composites has been the subject of several investigations, the correlation between strength and water uptake has not been established. Therefore, the purpose of the present study was to verify if there was a statistically significant correlation between biaxial flexural strength and weight gain due to water uptake for two commercial restorative composites, one methacrylate-based and one silorane-based. Discs (15 mm in diameter by 1 mm thick) were built with either Filtek Z250 or Filtek Silorane (both from 3M ESPE) and dry stored for 30 days. Then, they were weighted in an analytical balance and immersed in distilled water at 37 oC for 1, 2, 5, 7, 30 or 60 days (n=10). After the immersion period, the discs were re-weighted and immediately fractured on a “piston-on-three-ball” device. Mass gain (in percentage) and biaxial flexural strength data were subjected to two-way ANOVA/Tukey test and Pearson’s correlation analysis (alpha: 5%). Mass gain was similar for both composites in a given storage period, and did not vary significantly between one and seven days. For Filtek Z250, biaxial strength decreased gradually with prolonged immersion, while for Filtek Silorane, it decreased abruptly between 30 and 60 days. Statistically significant correlations were found between strength and mass gain for both composites. However, a stronger correlation was found for Filtek Z250 (r=-0.706, p<0.001) compared to Filtek Silorane (r= - 0.361, p<0.01). Therefore, it was possible to conclude that strength is linearly related to water uptake and this correlation is material-dependent

Dental Adhesives-Surface Modifications of Dentin Structure for Stable Bonding

The latest advancements in dentin bonding have focused on strategies to impair degradation mechanisms in order to extend the longevity of bonded interfaces. Protease inhibitors can reduce collagen degradation within the hybrid layer (HL). Collagen cross-linkers allow better adhesive infiltration and also inhibit proteases activity. Particles added to adhesive can promote mineral precipitation within the HL, reducing nanoleakage and micropermeability, besides possible antimicrobial and enzymatic inhibition effects. Most of these approaches are still experimental, and aspects of the adhesive under the clinician's control are still determinant for the long-term stability of adhesive restorations

Aspectos técnicos envolvidos na remoção da medicação intracanal de hidróxido de cálcio

The search for an effective method of microbial control has been a constant concern in endodontics. The aim of this literature review was to discuss the technical aspects related to the removal of intracanal calcium hydroxide. As an adjunct to sanifi cation and microbial control, calcium hydroxide [Ca(OH)2] intracanal medication is more suitable in cases of pulp necrosis and chronic periapical lesions. However, it is not easily removed from the root canal, and its residue can affect the interface quality of the endodontic fi lling, especially when a resin sealer is used. The removal effi cacy of Ca(OH)2 medication has been investigated using several products and techniques, such as auxiliary chemicals, recapitulation with memory instrument and passive ultrasonic activation. The literature unanimously recognizes the persistence of residues with all the reported methods, particularly in the apical third, and ultrasonic activation has shown the best results in the removal of Ca(OH)2 medication.A busca por alternativas de controle microbiano tem sido uma preocupação constante na Endodontia. O objetivo desse artigo é revisar aspectos técnicos relacionados à remoção da medicação intracanal de hidróxido de cálcio. Como auxiliar da sanificação e controle microbiano, a medicação intracanal de hidróxido de cálcio (Ca(OH)2) é a mais indicada nos casos de polpas necróticas e lesões periapicais crônicas. Entretanto, ela não é facilmente removida do canal radicular e os resíduos oriundos dessa medicação podem afetar a qualidade da interface da obturação endodôntica, em especial quando um cimento obturador resinoso é utilizado. A eficácia de remoção da medicação intracanal de Ca(OH)2 tem sido investigada usando vários produtos e técnicas, tais como a utilização de substâncias químicas auxiliares, recapitulação com instrumento memória e ativação ultrassônica passiva. A literatura é unânime em reconhecer a permanência de resíduos em todos os métodos relatados, principalmente no terço apical, sendo que a ativação ultrassônica tem demonstrado melhores resultados, na remoção da medicação intracanal de Ca(OH)2