Effect of Dietary Challenges on the Flexural Properties of Resin-based Composites

@#This study aims to compare flexural strength and flexural modulus of different resin-based composites (RBCs) and to determine the impact of dietary solvents on flexural properties. Forty specimens (12x2x2mm) for each of two conventional (Aura Easy [AE]; Harmonize [HN]) and one bulk fill (Sonic Fill 2 [SF2]) were fabricated using customised plastic moulds. Specimens were light-cured, measured and randomly divided into four groups. The groups (n=10) were conditioned for 7 days at 37°C: in one of media: air (control), artificial saliva (SAGF), 0.02N citric acid and 50% ethanol–water solution. After conditioning, the specimens subjected to flexural testing. Two-way ANOVA and one-way ANOVA (post hoc: Tukey’s or Dunnett T3 tests) were used at =0.05. Significant differences in flexural properties were observed between materials and conditioning media. Flexural strength and modulus values ranged from 124.85MPa to 51.25MPa; and 6.76GPa to 4.03GPa, respectively. The highest flexural properties were obtained with conditioning in air. Exposure to aqueous solutions generally reduced flexural properties. In conclusion, the effect of dietary solvents on flexural properties were material and medium dependent. For functional longevity of restorations, patients’ alcohol intake should be considered during material selection. Dietary advice (reduce alcohol consumption) should be given to patients post operatively.

Increased longevity of resins based composite restorations and their adhesive bond: a literature review / Aumento de longevidad de restauraciones de resinas compuestas y de su unión adhesiva: revisión de tema

ABSTRACT. Introduction: the goal of this literature review is to analyze the findings included in the literature concerning different alternatives to increase longevity of resin-based composite restorations and their adhesive bond. Methods: bibliographies in the EBSCO database (Elton B Stephens Company) were reviewed using the following key words: "composite repair bond strength"; "restorations sealing"; composite restorations longevity"; "restorations refurbishment"; "composite bond strategy"; "dental adhesive collagen cross linking"; "proanthocyanidin dentin bond strength"; "multiple layer dentin bond strength", and "dentin adhesive evaporation bond strength". Clinical and laboratory results were analyzed in terms of repairing, sealing, and refurbishing defective restorations, in addition to improvements in impregnation of adhesive surfaces, resistance of adhesive polymers, and the progress recently made concerning resistance to hydrolytic collagen degradation. Results: repairing, sealing, or refurbishing defective restorations allow keeping tooth structure healthy, reducing potential damage to dental pulp, as well as operatory pain, often caused without anesthetics. New bonding management techniques provide adhesive procedures with increased longevity. Conclusions: repairing, refurbishing, or sealing defective composite resins increase the longevity of restorations and restored teeth by using minimally invasive dental techniques. Other methods, such as improving impregnation of adhesive surfaces, increasing adhesive polymers strength, and hydrolytic degradation of collagen are promising advances that modify the management of bonding techniques, providing patients with restorative treatments of increased longevity.

RESUMEN. Introducción: el objetivo de esta revisión es analizar los resultados de las diferentes alternativas que presenta la literatura para incrementar la longevidad de las restauraciones con base a resinas compuestas. Métodos: fueron revisadas las bibliografías en la base de datos EBSCO (Elton B Stephens Company), en idioma inglés bajo los siguientes acrónimos " composite repair bond strengh"; "restorations sealing"; composite restorations longevity; "restorations refurbishment"; "composite bond estrategy"; "dental adhesive collagen cross linking"; "proanthocyanidin dentin bond strength";" multiple layer dentin bond strength"; and "dentin adhesive evaporation bond strength". Se examinan los resultados clínicos y de laboratorio de reparación, sellado y remodelado de restauraciones defectuosas, además de las mejoras en la impregnación de las superficies adhesivas, la resistencia de los polímeros adhesivos y los avances en el aumento de la resistencia a la degradación hidrolítica del colágeno. Resultados: la reparación, sellado y remodelado de restauraciones defectuosas permite la preservación de estructura dentaria sana, reducción del potencial daño a la pulpa dental y reducción del dolor operatorio, la mayoría de las veces efectuado sin uso de anestésicos. Nuevas técnicas para el manejo de la adhesión proporcionan incremento en la longevidad de los procedimientos adhesivos. Conclusiones: la reparación, remodelado y sellado de resinas compuestas defectuosas, incrementa la longevidad de las restauraciones y de los dientes restaurados con la aplicación de técnicas de odontología mínimamente invasiva. Adicionalmente otras metodologías, tales como mejoras en la impregnación de las superficies adhesivas, aumento de la resistencia de los polímeros adhesivos e incremento de la resistencia a la degradación hidrolítica del colágeno constituyen promisorios avances que modifican el manejo de las técnicas adhesivas, que permitirá ofrecer tratamientos restauradores de mayor longevidad a la población.

Nano Composites.

Nanotechnology was first described in 1959 by physicist Richard P Feynman, who viewed it as an unavoidable development in the progress of science, and has since been part of mainstream scientific theory with potential medical and dental applications since the early 1990s. Nanotechnology’s most tangible contribution to dentistry to date has been the restoration of tooth structure with Nanocomposites. Nanocomposites are characterized by filler-particle sizes of <= 100 nm, which offer these materials aesthetic and strength advantages over conventional microfilled and hybrid resin-based composite (RBC) systems. They offer advantages primarily in terms of the smoothness, polishability and precision of shade characterization, notwithstanding the flexural strength and microhardness they offer similar to those of the better-performing posterior RBCs. The strength and aesthetic properties of the resin based Nanocomposite makes it possible for it to be used for both anterior and posterior restorations. This article aims to address the current major uses of practical nanotechnology in dentistry, mainly the restoration of tooth structure with RBCs that make use of nanoparticles.

Survival rate of sealed, refurbished and repaired defective restorations: 4-year follow-up

The most common treatment in general dental practice is the replacement of restorations affected by secondary caries or marginal deficiencies. Alternative treatments to replacement of defective restorations, such as marginal sealing, refurbishment and repair, have demonstrated improvement of their clinical properties with minimal intervention. The aim of this clinical study was to estimate the median survival time (MST) of marginal sealing, repair and refurbishment of amalgam and resin-based composite restorations with localized defects as a treatment to increase the restoration longevity. A cohort of 66 patients, with 271 class I and II restorations clinically diagnosed with localized defects was longitudinally assessed. Each restoration was assigned to one of the following 5 groups: Marginal Sealing (n=48), Refurbishment (n=73), Repair (n=27), Replacement (n=42), and Untreated (n=81). Two calibrated examiners assessed the restorations at baseline and annually during 4 years, using the modified Ryge criteria: marginal adaptation, anatomic form, roughness, secondary caries and luster. Fifty-two patients with 208 restorations were assessed after 4 years; the distribution of restorations in the groups was as follows: Marginal Sealing (n=36), Refurbishment (n=63), Repair (n=21), Replacement (n=28) and Untreated (n=60). Kaplan Meier test indicated that the Sealed margins group showed the lowest MST while the Repair group showed the highest MST for restorations examined after 4 years of follow up. Defective amalgam and resin-based composite restorations treated by sealing of marginal gaps, refurbishment of anatomic form, luster or roughness, and repair of secondary caries lesions, had their longevity increased.

Na clínica odontológica geral, o tratamento mais comum é a substituição de restaurações com cárie secundária ou defeitos marginais. Tratamentos alternativos às substituições de restaurações defeituosas, como selamento marginal, recuperação, e reparo, têm proporcionado melhorias das propriedades clínicas, com um mínimo de intervenção. O objetivo deste estudo foi avaliar o tempo médio de sobrevida (median survival time - MST, na sigla em inglês) de selamento marginal, recuperação e reparo de restaurações de amálgama e compósitos resinosos com defeitos localizados, como tratamento para aumentar a longevidade das restaurações. Este foi um estudo longitudinal envolvendo 66 pacientes com 271 restaurações classe I e II, clinicamente diagnosticadas e com defeitos localizados. Cada restauração foi incluída num dos seguintes grupos: Selamento Marginal (n=48), Recuperação (n=73), Reparo (n=27), Substituição (n=42) e Sem tratamento (n=81). Dois examinadores calibrados avaliaram as restaurações no início e anualmente durante 4 anos, usando os critérios de Ryge modificados: adaptação marginal, forma anatômica, rugosidade, cárie secundária e brilho. Cinqüenta e dois pacientes com 208 restaurações foram avaliados após 4 anos; a distribuição das restaurações nos grupos foi a seguinte: Selamento Marginal (n=36), Recuperação (n=63), Reparo (n=21), Substituição (n=28) e Sem tratamento (n=60). O teste de Kaplan Meier mostrou que o grupo do Selamento Marginal apresentou o menor valor de MST, enquanto que o grupo do Reparo mostrou o maior valor, para as restaurações avaliadas após o acompanhamento de 4 anos. As restaurações de amálgama e compósitos tratadas com selamento de fissuras marginais, recuperação da forma anatômica, brilho ou rugosidade e reparo de cárie secundária, tiveram aumento de longevidade.