Chitosan coating effects on biological response to niobia-modified yttria-stabilized zirconia

PURPOSE The impact of chitosan (Ch) surface modification on the osseointegration of niobia-modified yttria-stabilized zirconia (Y,Nb-TZP) implants was assessed using a rabbit tibia model. MATERIALS AND METHODS Y,Nb-TZP and SLA discs and implants were prepared and coated with Ch of 95% degree of deacetylation (DDA). MC3T3-E1 cells and human gingival fibroblasts were cultured onto discs (n = 3) for cell proliferation, adhesion, osteogenic differentiation and gene expression analysis. Specimen surface characteristics were assessed using scanning electron microscopy and confocal laser scanning microscopy. Eight rabbits underwent tibial implant placement and were euthanized at 2 and 8 weeks after surgery (n = 4). Bone-to-implant contact (BIC) and bone area (BA) were quantified through histomorphometric evaluation. One-way ANOVA with Tukey’s post hoc test was used for statistical analysis ( P < .05) unless otherwise specified. RESULTS Ch-coated Y,Nb-TZP discs supported cell attachment, proliferation, and osteogenic differentiation in vitro , with increased osteogenic and early focal adhesion gene expression, compared with uncoated controls. However, in vivo evaluation in rabbit tibiae showed no improvement in bone-to-implant contact or bone area around Ch-modified implants relative to uncoated Y,Nb-TZP or SLA controls, and osseointegration did not occur in the Ch-coated groups. CONCLUSION. Although Ch promoted osteogenic activity in vitro , these effects did not translate in vivo , and the coating failed to enhance osseointegration on Y,Nb-TZP implants. This gap underscores the complexity of host responses and the need to refine Ch properties for further evaluation under clinically relevant conditions.