Effect of the aging of titanium and zirconia abutment surfaces on the viability, adhesion, and proliferation of cells and the adhesion of microorganisms.

STATEMENT OF PROBLEM: The longevity of dental implants depends on the maintenance of peri-implant tissue and absence of inflammation. How the physical-chemical properties intrinsic to each material over time can affect adhesion, given constant cell turnover and biofilm development, remains unclear. PURPOSE: The purpose of this in vitro study was to evaluate the influence of aging on the viability, adhesion, and proliferation of normal oral keratinocytes (Nok-si) and on the multispecies biofilm formation of Fusobacterium nucleatum (F. nucleatum), Porphyromonas gingivalis (P. gingivalis), and Streptococcus sanguinis (S. sanguinis). MATERIAL AND METHODS: Zirconia (ZrO2) and titanium (Ti) disks were analyzed by surface roughness, water contact angle, and X-ray diffraction before and after aging in an autoclave. The Nok-si cell viability was evaluated by using a 3-(4.5-dimethylthiazole-2-yl)2.5-diphenyl tetrazolium bromide assay (MTT), morphology by scanning electron microscopy (SEM), and proliferation and adhesion by using a confocal microscope. Multispecies biofilms were analyzed quantitatively by colony-forming units per milliliter (CFU/mL) and qualitatively by SEM. RESULTS: For Ti, the aging process affected the roughness and wettability. However, for ZrO2, the aging did not affect roughness but did affect wettability and the ratio of the tetragonal to monoclinic phase (P<.05). A significant difference was found in the bacterial growth for Ti (nonaged and aged) in relation to the control, and no differences were found in Ti before and after aging; however, ZrO2 had increased growth of microorganisms after aging. For ZrO2, a statistically significant difference was found between aged ZrO2 and the control (P<.001). CONCLUSIONS: The results indicate that, after the aging, Ti showed better cell adhesion and proliferation and lower biofilm adhesion than zirconia.

Influência de características físicas e química dos materiais de abutments de implantes em zircônia e titânio na adesão e viabilidade de células epiteliais gengivais OBA-9 / Influence of the physical and chemical characteristics of two surfaces implant abutments, zirconia and titanium, in adhesion and viability of gingival epithelial cells OBA-9

Dada à necessidade de uma efetiva barreira tecidual precoce ao redor dos implantes osseointegrados, o presente estudo avaliou, in vitro, a influência das características físicas e químicas de materiais simulando superfícies de abutments de implantes em titânio (T) e zircônia (ZrO2) na adesão de células epiteliais gengivais OBA-9. Para este estudo foram utilizados espécimes em forma de discos (n=13) de titânio e zircônia, e como controles positivo e negativo, discos de esmalte bovino (EB) e lamínulas de vidro (LV), respectivamente. Foram avaliadas previamente a adesão celular a rugosidade superficial (Ra), energia livre de superfície (ELS) e os elementos químicos presentes na superfície identificados por meio de Espectrômetro de raios-X por Dispersão de Energia em Microscópio Eletrônico de Varredura (MEV). Após a adesão celular em 1 e 24 horas, foram avaliadas a viabilidade celular por meio do MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide); e a morfologia das células aderidas sobre as superfícies por meio de MEV. Os dados de viabilidade celular foram avaliados estatisticamente pelo teste de ANOVA a dois critérios fixos ("material" e "período de análise"), enquanto os dados de ELS foram submetidos aos testes de Kruskal-Wallis e Mann-Whitney, considerando um nível de significância de 5%. A superfície de T obteve o maior valor de ELS com 6,2N/m, seguida pela ZrO2 com 5,8N/m, LV com 4,9N/m, e com o menor valor o EB com 4,7N/m. Foi observado que os fatores material (p=0,336) e período de análise (p=0,400) não apresentaram efeito sobre os dados de viabilidade celular, assim como a interação entre eles (material*período de análise, p=0,559). A análise da morfologia celular mostrou que as células aderidas às superfícies de T e ZrO2 apresentaram espraiamento semelhante, sendo este maior quando comparado as superfícies de EB e LV. Concluiu-se que não houve diferença entre a adesão...

Given the need for effective early mucosal barrier around dental implants, the present study evaluated, in vitro, the influence of physical and chemical characteristics of materials simulating abutments implants surfaces in titanium (T) and zirconium (ZrO2) on gingival epithelial cells OBA-9 adhesion. For this study, disks-shaped samples (n=13) of titanium and zirconium were tested, and as positive and negative control groups, bovine enamel disks (BE), and glass coverslips (GCS), respectively. Previously the cellular adhesion surface roughness (Ra), surface free energy (SFE) and the chemical composition of specimens by X-ray Spectrometer Dispersive Energy in Scanning Electron Microscope (SEM) were evaluated. After the periods of cellular adhesion, 1 and 24 hours, the cellular viability was evaluated by MTT Assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and the morphology of the epithelial cells adhered to the surfaces was analyzed using the SEM. The data of cell viability were statistically evaluated by two-way ANOVA ("Material" and "period of analysis"), while the SFE data were submitted to Kruskal-Wallis and Mann-Whitney tests, considering a significance level of 5%. The T specimens showed the highest values of SFE (6.2 N/m), followed by ZrO2 (5.8 N/m), GCS (4.9 N/m), and BE (4.7 N/m). It was observed that the factors material (p = 0.336) and periods of analysis (p = 0.400) showed no effect on cell viability data, as well as the interaction between them (material* period of analysis, p = 0.559). The analysis of cell morphology showed that cells adhered to the T and ZrO2 surfaces presented similar spreading, which was higher compared to the BE and GCS surfaces. It was concluded that there was no difference between the cellular adhesion to different materials for implant abutments, T and ZrO2, in evaluated periods. However, cell spreading was qualitatively higher in rougher surfaces and greater titanium and zirconia SFE