Long-term Performance of Refurbished Amalgam Restorations: 10-year Follow-up.

PURPOSE: This prospective, blinded clinical trial assessed the performance of amalgam restorations that were refurbished, replaced, or not treated. MATERIALS AND METHODS: Twenty-three patients were included, ages 18-80 years, with 63 amalgam restorations that had one or more defects in their clinical features, such as defective anatomic form, roughness and/or luster according to United State Public Health Service (USPHS) criteria. Restorations were randomly assigned to either refurbishment (A: n = 21), replacement (B: n = 21) or untreated (C: n = 21) groups. Two calibrated examiners evaluated the restorations at baseline (Kappa = 0.74) and after 10 years (Kappa = 0.84), according to eight parameters: anatomy, roughness, luster, secondary caries, marginal adaptation, occlusal contact, marginal staining and tooth sensitivity. Wilcoxon tests were performed for within-group comparisons, and Friedman tests were used for multiple within-group comparisons. The Mantel-Cox test was used to compare survival curves. RESULTS: After 10 years, 49 restorations (77.8%) were assessed (group A: n = 19; group B: n = 13; group C: n = 17). Over a decade, the three groups showed similar clinical performances for all studied parameters: anatomy (p = 0.410), roughness (p = 0.930), luster (p = 0.984), secondary caries (p = 1.0), marginal adaptation (p = 0.433), occlusal contact (p = 0.33), marginal staining (p = 0.470), and tooth sensitivity (p = 0.784). CONCLUSIONS: Amalgam restorations that have defective anatomic form, roughness and/or luster performed similarly for all studied parameters, whether they were refurbished, replaced or left untreated after 10 years in patients with low and intermediate caries risk. Most of the restorations were classified as clinically acceptable after ten years. Restorations in all three groups tended to deteriorate over time.

Rol del 10-metacriloxidecilfosfato dihidrogenado en el cambio de paradigma de los sistemas adhesivos integrados en la dentina / The Role of 10-methacryloyloxydecyl dihydrogen phosphate in the paradigm of change to adhesive systems integrated to dentin

La aplicación de adhesivos dentarios autograbantes que contienen 10-metacriloxidecilfosfato dihidrogenado supera la resistencia a la biodegradación de la interfase adhesiva de los sistemas tradicionales de grabado total. El mecanismo de acción se basa en la formación de múltiples nanocapas de calcio unido a 2 moléculas 10-metacriloxidecilfosfato dihidrogenado sobre la dentina; estas múltiples capas de 3,5 nm son las que protegerían las fibras colágenas del fenómeno de hidrólisis. Las nanocapas explicarían su alta estabilidad en el tiempo y la fortaleza de la unión, probadas tanto en estudios clínicos como de laboratorio. La interacción con la hidroxiapatita sucede con ácidos de pH bajos, pero mayores que los tradicionales, por lo que surge la necesidad de recomendar el grabado selectivo previo del esmalte. El uso de metacriloxidecilfosfato dihidrogenado permite el cambio de filosofía adhesiva desde el grabado total a la integración adhesiva de la dentina.

Applying self-etching dental adhesives containing 10-MDP overcomes the resistance to biodegradation of the adhesive interface of traditional total etch. The mechanism of action is based on the formation of multiple nano-layers of calcium and two molecules of 10-MDP on the dentin surface. These multiple layers of 3.5 nm protect the collagen fibers from hydrolysis phenomenon. The nano-layer explains its high stability and bond strength over time, tested both by clinical and laboratory studies. Hydroxyapatite interaction occurs with acids of low pH, but are higher than traditional, thus increasing the need to recommend the previous selective etching of the enamel. The use of MDP allows a change of philosophy from the total-etch adhesive to adhesive integration of the dentin.