Dynamics of the natural genesis of ß-TCP/HAp phases in postnatal fishbones towards gold standard biocomposites for bone regeneration.

The search for gold-standard materials for bone regeneration is still a challenge in reconstruction surgery. The ratio between hydroxyapatite (HAp) and ß-tricalcium phosphate (ß-TCP) in biphasic calcium phosphate ceramics (BCPs) is one of the most important factors in osteoinduction promotion and controlled biodegradability, configurating what is currently considered as a possible gold standard material for bone substitution in reconstructive surgery. Exploring the natural genesis of the HAp and ß-TCP phases in fishbones during their postnatal growth, this study developed a biphasic bioceramic obtained from the calcination of Nile tilapia (Oreochromis niloticus) bones as a function of their ages. The natural genesis dynamics of the structural evolution of the ß-TCP and HAp phases were characterized by physicochemical methods, taking into account of the age of the fish and the material processing conditions. Thermal analysis (TGA / DTA) showed complete removal of the organic matter and transitions associated with the transformation of carbonated hydroxyapatite (CDHA) to HAp and ß-TCP phases. After calcination at 900 °C, the material was characterized by: X-ray diffraction (XRD) and refinement by the Rietveld method; Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR-ATR); Raman spectroscopy; Scanning Electron Microscopy (SEM) and Flame Atomic Absorption Spectroscopy (FAAS). The analysis allowed identification and quantitative estimate of the variations of the HAp and ß-TCP phases in the formation of the BCPs. The results showed that the decrease in ß-TCP against the increase in the HAp phases is symmetrical to the dynamics of the natural genesis of these phases, surprisingly maintaining the balanced phase proportion even when bones of young fishes were used. The microstructure analysis confirms the observed transformation. In addition, in vivo tests demonstrated the osteoinductive potential of BCP scaffolds implanted in an ectopic site, and their remarkable regenerative functionality, as bone graft, was demonstrated in alveolar bone after tooth extraction. MTT cytotoxicity assay for BCP samples for MC3T3-E1 pre-osteoblasts and L929 fibroblasts cells showed viability equal or higher than 100%. A logistic empirical model is presented to explain the three stages of HAp natural formation with fish age and it is also compared to the fish size evolution.

Analysis of bone formation and membrane resorption in guided bone regeneration using deproteinized bovine bone mineral versus calcium sulfate.

Guided Bone Regeneration (GBR) is a technique based on the use of a physical barrier that isolates the region of bone regeneration from adjacent tissues. The objective of this study was to compare GBR, adopting a critical-size defect model in rat calvaria and using collagen membrane separately combined with two filling materials, each having different resorption rates. A circular defect 8 mm in diameter was made in the calvaria of Wistar rats. The defects were then filled with calcium sulfate (CaS group) or deproteinized bovine bone mineral (DBBM group) and covered by resorbable collagen membrane. The animals were killed 15, 30, 45 and 60 days after the surgical procedure. Samples were collected, fixed in 4% paraformaldehyde and processed for paraffin embedding. The resultant sections were stained with H&E for histological and histomorphometric study. For the histomorphometric study, the area of membrane was quantified along with the amount of bone formed in the region of the membrane. Calcium sulfate was reabsorbed more rapidly compared to DBBM. The CaS group had the highest percentages of remaining membrane at 15, 30, 45 and 60 days, compared to the DBBM group. The DBBM group had the highest amount of new bone at 45 and 60 days compared to the CaS group. Based on these results, it was concluded that the type of filling material may influence both the resorption of collagen membrane and amount of bone formed.

Immediate complete denture: a contemporary view

AIM: The objective of this study was to describe the advantages, disadvantages, indications and some limitations of the Immediate Complete Denture (ICD) treatment. MATERIAL AND METHODS: An electronic and manual search was made in SciELO, SCOPUS, MEDLINE/PubMed databases from 1972 to 2015. Publications in Portuguese, Spanish and English were selected to write this narrative review of the literature. CONCLUSION: Despite the limitations of this study it was conclude that treatment with ICD is the best option because of its satisfactory results.

Estudo do comportamento do sulfatode cálcio: bioatividade e solubilidade em fluido corpóreo simulado / Studying the behavior of calcium sulfate: bioactivity and solubility in simulated body fluid

Com a finalidade de correção de defeitos ósseos, diversos materiais sintéticos têm sido utilizados, entre os quais está o sulfato de cálcio. Objetivo: o objetivo do presente estudo foi avaliar, in vitro, a bioatividade do sulfato de cálcio em fluido corpóreo simulado (SBF). Métodos: quatro corpos de prova foram preparados em matrizes de policloreto de vinila (PVC) circulares, misturando-se o sulfato de cálcio nas proporções de líquido/pó recomendadas pelo fabricante, com água destilada. As amostras ficaram imersas em 50ml de SBF, a 36,5ºC, por até 21 dias, sendo que a solução foi renovada a cada três dias. A bioatividade foi verificada por meio de Espectroscopia no Infravermelho por Transformada de Fourier (FTIR). Resultados: no teste de bioatividade in vitro, a análise por FTIR detectou a presença de apatita sobre o substrato de sulfato de cálcio, demonstrando tratar-se de um material bioativo. Além disso, foi observada uma redução expressiva do tamanho da amostra vinculada ao processo de reabsorção. Conclusão: dentro das limitações do estudo, pode-se concluir que o sulfato de cálcio é um material bioativo e rapidamente reabsorvido...

Several types of synthetic material have been used to correct bone defects, among which is calcium sulfate. Objective: the present in vitro study aimed at assessing the bioactivityof calcium sulfate in simulated body fluid (SBF). Methods: four specimens were prepared in polyvinyl chloride (PVC) circle matrices by mixing calcium sulfate with distilled water, as recommended by the manufacturer. Samples were immersed in 50 ml of SBF, at 36.5 ºC, for no longer than 21 days. The solutionwas renewed every three days. Bioactivity was assessed by means of Fourier transform infrared spectroscopy (FTIR). Results: The in vitro bioactivity test, carried out by means of FTIR analysis, revealed the presence of apatite formation over calcium sulfate substrate, thereby proving it to be a bioactive material. In addition, there was significant reduction in the size of the sample, which was associated with the process of resorption. Conclusion: within the limitations of the present study, it is reasonable to conclude that calcium sulfate is a bioactive material which is quickly absorbed...

Efeito de diferentes elastômeros na adaptação cervical de coroas totais metálicas / Effect of different elastomers on cervical fit of full metal crowns

Objective: The aim of this study was to evaluate the cervical fit of full metal crowns using four different elastomers. Methods: A stainless steel metallic die similar to a prepared first upper molar was obtained. Four di-fferent elastomeric impression materials were utilized: polysulfide (A), polyether (B), condensation silicone (C) and addition silicone (D). Forty molds were created, 10 for each group. It was obtained 40 gypsum abutments. After the end of this stage, it was performed complete metal crowns on all specimens. Crown displacement was measured through a comparative microscope, obtaining diametrically opposite points. Results: The re-sults were the following: Group D (31.97 um), Group B (49.57 um), Group A (51.12 um), Group C (61.12 um). The analysis of variance (ANOVA) test and a Tukey test for multiple comparisons were used to analyze the results. Conclusions: There were significant differences among all groups, except for Groups A and B. The major result of displacement was Group C. The best results were shown by Group D (p < 0.05).

Preferências por açúcar e prevalência de cárie dentária em populaçöes desfaveladas de Bauru-SP-Brasil / Taste preference for sweetness in poor school children in Bauru-Brazil: influence on dental caries

Este estudo trasversal foi delineado para estimar a preferência por açúcares em escolares e diferenças apresentadas por grupos de diferentes inserçöes sociais e econômicas. Adicionalmente, com objetivo de avaliar se a preferência gustativa por açúcar mostrava-se associada à prevalência de cárie, foram examinados 527 escolares do grupo etário 10 a 15 anos, procedentes de dois grupos sociais. O primeiro grupo era oriundo de uma escola da área periférica do município (nD8) e o segundo provinha de uma populaçäo com extremas privaçöes sociais, em processo de desfavelamento (ny). A preferência por açúcar foi avaliada por meio de uma versäo modificada do Sweet Preference Inventory. Cada criança provou 5 soluçöes de um suco de fruta, cuja concentraçäo de açúcar variou de 0 a 1,17 Molar (0 a 400g/mol.). A prevalência de cárie foi avaliada por meio do CPOS. No grupo de maiores privaçöes sociais (Desfavelamento), 28,9 por cento preferiram o suco mais adoçado, enquanto no outro grupo 29,3 por cento preferiram esta soluçäo. Os testes de Mann-Whitney e coeficiente de correlaçäo de Spearman foram aplicados para análise estatística (p<0,05). Os resultados mostraram que o nível socioeconômico näo apresentou influência sobre a preferência por açúcar, mas foi significantemente associado à prevalência de cárie