Mechanical Reinforcement Strategy of Calcium Phosphate Cements by Loading Polymers / 中国医疗器械杂志

Calcium phosphate cement (CPC) is well known for the excellent bioactivity and biocompatibility, however, CPC has been used only for the repair of non-load bearing bone defects due to its brittle nature and low flexural strength. Polymer reinforced CPC has been considered as one of the most effective strategies for mechanical reinforcement. This paper summarizes various kinds of polymers loaded CPC:fiber reinforcement, microsphere reinforcement and dual setting cements. It is aimed to analyze the advantages, disadvantages and principles of the polymers reinforced CPC, and so as to lay a foundation for the further research of improving and manufacturing the CPC with ideal mechanical properties.

Influence of glass fiber reinforcement and resin viscosity on the resistance to fracture of Adhesive Partial Fixed Prostheses / Influência do reforço de fibra de vidro e viscosidade da resina sobre a resistência a fratura de Prótese Parciais Fixas Adesivas

Objective: The aim of this study was to evaluate the influence of glass fiber reinforcement and resin viscosity on the resistance to fracture of adhesive fixed partial prosthesis (AFPP). Materials & Methods: A stainless steel molding was constructed simulating oclusal preparation for AFPP on a maxillary first pre-molar (4 x 4 x 2 mm) and molar (6 x 4 x 2 mm), with a proximal slot (2 x 1 x 4 mm) and with 7 mm of distance between them. These moldings were duplicated in polyurethane (n = 60) and divided into two groups according to the resin viscosity: G - Grandio SO (VOCO) (n = 30) and GHF – Grandio SO Heavy flow (VOCO) (n= 30). These groups were subdivided into three subgroups according to the glass fiber reinforcement used (n = 10): Subgroup N – without glass fiber reinforcement; Subgroup V – GRANDTEC (VOCO); subgroup S – everStick C & B (Stick Tech). Four increments divided into 2 layers, 2 in the lower part and 2 in the upper part of the preparations were light-cured according to the manufacturers’ instructions. A vertical load was applied on the center of the pieces at a speed of 1mm/min. Data were obtained in Kgf and submitted to two-way ANOVA and Tukey test (α = 0.05). Results: ANOVA showed significant differences for glass fiber reinforcement. Subgroup N (24.45 ± 3.60)a was significantly different from subgroup S (32.54 ± 6.94) b and subgroup V (37.18 ± 5.33) c. Conclusion: The glass fibers tested were capable of improving the resistance to fracture of AFPP. GRANDTEC fiber exhibited the greatest values of resistance to fracture and for the resins studied the viscosity did not influence on the resistance to fracture of AFPP.

Objetivo: O objetivo deste estudo foi avaliar a influência do reforço com fibra de vidro e viscosidade da resina na resistência à fratura de prótese parcial fixa adesiva (PPFA). Material e Método: Um molde de aço inoxidável foi confeccionado simulando preparos oclusais para PPFA em primeiro pré-molar superior (4 x 4 x 2 mm) e molar (6 x 4 x 2 mm), com uma caixa proximal (2 x 1 x 4 mm) e 7 mm de distância entre eles. Esses moldes foram duplicados em poliuretano (n = 60) e divididos em dois grupos de acordo com a viscosidade da resina: G – Grandio SO (VOCO) (n = 30) e GHF - Grandio SO Heavy flow (VOCO) (n = 30). Estes grupos foram subdivididos em três subgrupos de acordo com o reforço de fibra de vidro utilizado (n = 10): Subgrupo N - sem reforço de fibra de vidro; Subgrupo V - GRANDTEC (VOCO); subgrupo S – everStick C & B (Stick Tech). Quatro incrementos divididos em 2 camadas, 2 na parte inferior e 2 na parte superior dos preparos foram fotopolimerizados de acordo com as instruções dos fabricantes. Uma força vertical foi aplicada no centro das peças a uma velocidade de 1 mm/min. Os dados foram obtidos em Kgf e submetidos a ANOVA a 2 fatores e teste de Tukey (α = 0,05). Resultado: A ANOVA mostrou diferenças significativas para reforço de fibra de vidro. Subgrupo N (24,45 ± 3,60) a foi significativamente diferente do subgrupo S (32,54 ± 6,94)b e subgrupo V (37,18 ± 5,33)c. As fibras de vidro testadas foram capazes de melhorar a resistência à fratura de PPFA. Conclusão: A Fibra GRANDTEC apresentou os maiores valores de resistência à fratura e, para as resinas estudadas, a viscosidade não teve influência na resistência à fratura de PPFA.

Fracture process characterization of fiber-reinforced dental composites evaluated by optical coherence tomography, SEM and optical microscopy

This study used optical coherence tomography (OCT) compared to scanning electron microscopy (SEM) and optical microscopy (OM) to evaluate qualitatively crack propagation and final fracture in restorative composite materials - Filtek Z250 and Filtek Z350 (3M ESPE) - with fiber reinforcement after cyclic loading. Samples were made using a split mold. Initially, 3-point bending tests were performed to determine the maximum force and tension at the fracture moment using samples without fiber reinforcement. Then, mechanical cycling tests were performed using samples with glass fiber embedded internally. The failures were analyzed using the 3 methods described before. OCT permitted good characterization of internal crack propagation of the dental composites, which, however, could not be visualized by either SEM or OM. OCT was proven to be laboratory research tool that is easy to use, does not require any specific preparation of the samples, and is less expensive than SEM.