Grinding With Diamond Burs and Hydrothermal Aging of a Y-TZP Material: Effect on the Material Surface Characteristics and Bacterial Adhesion

Abstract

The aim of this study was to evaluate the effect of grinding with diamond burs and low-temperature aging on the material surface characteristics and bacteria adhesion on a yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) surface. Y-TZP specimens were made from presintered blocks, sintered as recommended by the manufacturer, and assigned into six groups according to two factors-grinding (three levels: as sintered, grinding with extra-fine diamond bur [25-μm grit], and grinding with coarse diamond bur [181-μm grit]) and hydrothermal aging-to promote low-temperature degradation (two levels: presence/absence). Phase transformation (X-ray diffractometer), surface roughness, micromorphological patterns (atomic force microscopy), and contact angle (goniometer) were analyzed. Bacterial adhesion (colony-forming units [CFU]/biofilm) was quantified using an in vitro polymicrobial biofilm model. Both the surface treatment and hydrothermal aging promoted an increase in m-phase content. Roughness values increased as a function of increasing bur grit sizes. Grinding with a coarse diamond bur resulted in significantly lower values of contact angle (p<0.05) when compared with the extra-fine and control groups, while there were no differences (p<0.05) after hydrothermal aging simulation. The CFU/biofilm results showed that neither the surface treatment nor hydrothermal aging simulation significantly affected the bacteria adherence (p>0.05). Grinding with diamond burs and hydrothermal aging modified the Y-TZP surface properties; however, these properties had no effect on the amount of bacteria adhesion on the material surface.

Effect of surface properties of ceramic materials on bacterial adhesion: A systematic review

“…Microbiological tests were performed on different ceramic materials, including feldspathic ceramics, 8,22,40,43 zirconia, 20–22,29–31,34–36,38,39,41,42,44,45 zirconia‐reinforced lithium silicate, 30,41 aluminum‐zirconia, 20,22,31 aluminum, 33 leucite, 11,33,41 lithium disilicate, 11,20,31,34,37,41,44 vitreous ceramics 20,31 and fluorapatite veneering porcelain 32 …”

“…The included studies measured the roughness by confocal laser microscope, 41,44 roughness analyzer/contact rugosimeter, 8,22,30,39,40 profilometer, 31–34,36,37,43 optical interferometer, 45 and atomic force microscopy 21,29,38,42 …”

“…The evaluation of microbial adhesion to ceramics was evaluated through colony forming units, 8,11,30,37,39,41 viable cell, 21,22,30–32,34,41 confocal laser‐scanning microscopy evaluation, 20,29,32,40,43–45 SEM evaluation, 8,30,32,35,36,40–43 liquid scintillation method, 33 atomic force measurement, 38 and epifluorescence microscopy 38 …”

Physical and biological implications of accelerated aging on stereolithographic additive-manufactured zirconia for dental implant abutment

“…In addition, Deville et al indicated that the aging kinetics of zirconia is critically influenced by the surface stress state, and the tetragonal to monoclinic transformation preferentially occurs on neighboring areas of residual stress concentration [6,32]. Thus, it can be assumed that the effects of LTD (i.e., grain pullout) on the zirconia surface first occur in the proximity of grains with the highest topography (superficial layer), where an uneven distribution of stress is most likely to co-exist with increased susceptibility to water contact, resulting in reduced surface roughness compared to non-aged zirconia [32,33]. With increasing aging time, phase transformation is extended to the entire surface and inside the crystal grain via a nucleation and growth mechanism, yielding Ra values comparable to those of non-aged samples [6,9,32].…”

Efeito de diferentes protocolos de desgaste nas características superficiais e comportamento mecânico da zircônia (Y-TZP)

“…Clinicamente, o aumento da rugosidade superficial em mais de 0,2 µm têm sido associado ao acúmulo de biofilme e consequentemente, ao aumento do risco à carie e à inflamação periodontal, se a peça protética estiver exposta no ambiente bucal (Bollen et al, 1997). Entretanto, Dutra et al (2017) Alguns estudos constataram que o aumento da rugosidade superficial pode provocar a diminuição da resistência à flexão da zircônia (Kosmac et al, 2008;Iseri et al, 2010;Canneto et al, 2016), enquanto alguns estudos não encontraram esta correlação (Curtis et al, 2006;Subasi et al, 2014;Preis et al, 2015;Lee et al, 2016;Hatanaka et al, 2016;Pereira et al, 2015;Khayat et al, 2017;Ozer et al, 2017) e outros afirmaram que pode haver o aumento da resistência à flexão (Ho et al, 2009;Pereira et al, 2016A;Ramos et al, 2016). Outra propriedade que possui relação com a resistência e comportamento mecânico dos materiais dentários é o módulo de elasticidade.…”