Physical and mechanical characterization of a porous cement for metaphyseal bone repair

OBJECTIVE: Macroporous cement with mechanical properties similar to cancellous bone may improve the treatment of large bone defects in relation to solid acrylic cement. The aim of this study was to compare physical and mechanical characteristics of a polymethyl methacrylate (PMMA) based porous cement with cancellous bone. METHODS: Compressive strength and pore size, interconnectivity, and distribution of cylindrical porous PMMA cement samples containing 10% (G1), 20% (G2) or 30% (G3) effervescent components were analyzed. Results were compared to bovine cancellous bone (G4) and solid PMMA (G5) samples. RESULTS: Scanning electron microscopy (SEM) of all experimental samples (G1 - G3) revealed a random distribution and a wide size variation of pores ranging from 50 µm to 3 mm. Micro-CT showed that G2 have high porosity and lower interconnectivity of pores. No significant differences in yield strength and Young's modulus were observed among G1, G2 and G3. G4 samples were slightly stronger and less elastic than the other groups. Solid PMMA is extremely strong and inelastic. CONCLUSIONS: PMMA based porous cement met the expected characteristics. High porosity with large and interconnected pores may allow for bone ingrowth. Strength and elasticity similar to cancellous bone may enhance mechanical stimuli to bone remodeling. Observational Descriptive Study.

Effect of toothbrushing with different toothpastes at commerciallypure titanium surface roughness / Efeito da escovação com diferentes dentifrícios na rugosidade superficial do titânio comercialmente puro

Objective: To evaluate the effect of brushing, using toothpastes with different fluoride concentrations, on the surface of commercially pure titanium (cp Ti). Methods: Discs (13x4mm) made of cp Ti, embedded in PVC rings and metallographically polished have their surface roughness measured. Tooth brushing simulations (50,400 cycles) were performed: speed of 80mm/s, distance of 10mm distance, at 240 cycles/min. Three toothpastes were tested: Prevident 5000 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil), Colgate Total 12 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil) and Tandy (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil), with 5000, 1300 and 500ppm fluoride concentrations, respectively. The brushings had 7.14g and 14.28g of toothpaste, both for 50mL of deionized water. The surface roughness was reevaluated and data were analyzed by two-way ANOVA and Tukey?s test for the effect of brushing and toothpastes. Results: At the beginning, no significant difference (p=0.09) of roughness was noted among the experimental groups (Prevident, Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil): 0.160±0.019; Colgate Total 12 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil): 0.159±0.030; Tandy (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil): 0.157±0.019) but roughness decreased after the 1st (p<0.05) (0.094±0.010) and 2nd (0.089± 0.012) brushings (p<0.05) with Prevident 5000 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil), with no significant difference between the 1st and 2nd brushings (p=0.16). Discs brushed with Colgate Total 12 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brazil) presented surface roughness similar (p=0.090) at the beginning and after the 1st brushing (0.133±0.029), and between the 1st and 2nd (0.113±0009) brushings (p=0.402); roughness after the 2nd brushing was statistically greater than at the beginning (p<0.05). Tandy (Colgate- Palmolive Ind. e Com. Ltda., São Paulo, Brazil) toothpaste caused a surface roughness significantly lower (p<0.05) after the 2nd brushing (0.113±0.010), compared to the 1st (0.147±0.020) and the starting point, which were statistically similar (p=0.090). Conclusion: The results suggest that brushing using toothpastes with fluoride causes a decrease in the surface roughness of cp Ti, mainly when greater fluoride concentrations are present.

Objetivo: Avaliar o efeito da escovação com dentifrícios contendo diferentes concentrações de flúor na superfície do titânio comercialmente puro (Ti cp). Métodos: Discos (13x4mm) de Ti cp, embutidos em anéis de PVC e polidos metalograficamente, tiveram a rugosidade superficial avaliada. A simulação da escovação (50400 ciclos) teve velocidade de 80mm/s, curso de 10mm, com 240 ciclos/min. Foram testados três dentifrícios: Prevident 5000, (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil); Colgate Total 12 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil) e Tandy (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil), com 5000, 1300 e 500ppm de flúor, respectivamente. As escovações tiveram 7,14g e 14,28g de dentifrício, ambas para 50ml de água deionizada. A rugosidade superficial foi reavaliada e os dados analisados por ANOVA - dois fatores e teste de Tukey quanto ao efeito da escovação e dos dentifrícios. Resultados: Inicialmente não houve diferença significante (p=0,09) na rugosidade dos grupos experimentais Prevident, (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil): 0,160±0,019; Colgate Total 12 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil): 0,159±0,030; Tandy (Colgate- Palmolive Ind. e Com. Ltda., São Paulo, Brasil): 0,157±0,019), mas houve diminuição da rugosidade após a 1ª (0,094±0,010) (p<0,05) e 2ª (0,089±0,012) escovações (p<0,05) com Prevident 5000 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil), sem diferença significativa entre as demais (p=0,16). Discos escovados com Colgate Total 12 (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil) apresentaram rugosidade semelhante inicialmente (p=0,090) e após a 1ª escovação (0,133± 0,029), e entre a 1ª e a 2ª escovações (0,113±0,009) (p=0,402); a rugosidade após a 2ª escovação foi significativamente maior que a inicial (p<0,05). O dentifrício Tandy (Colgate-Palmolive Ind. e Com. Ltda., São Paulo, Brasil) causou rugosidade superficial significativamente menor (p<0,05) após a 2ª escovação (0,113±0,010), comparada à 1ª (0,147±0,020) e a inicial, que foram semelhantes (p=0,090). Conclusão: Os resultados sugerem que a escovação com dentifrícios fluoretados diminui a rugosidade superficial do Ti cp, mais significativamente quanto maiores as concentrações de flúor presentes.