Ana Flávia Sanches Borges

Hydroxyapatite-based (HA) bioceramics are attractive for dental-biomaterial development, but their mechanical and chemical limitations remain challenging. This study screened bovine-HA formulation-processing routes with zirconia-based additions by three-point flexural strength and then assessed chemical solubility, Vickers hardness, and qualitative surface morphology of the mechanically selected route after an acidic challenge. In Phase 1, pure HA and HA containing 1, 5, or 10 wt% 3Y-TZP or an exploratory nominal ZrO ₂ whisker-synthesis product were evaluated under formulation-specific sintering schedules. Overall flexural-strength differences were significant ( p < 0.001). HA + 1 wt% 3Y-TZP showed the highest observed median [117.0 (94.8, 122.0) MPa], although its pairwise comparison with pure HA [84.0 (77.0, 88.0) MPa] did not reach significance (DSCF p = 0.095). In Phase 2, aggregate chemical solubility was 2,112.5 μg/cm ² for pure HA and 2,057.0 μg/cm ² for HA + 1 wt% 3Y-TZP; both exceeded the 2 limit applicable to covered substructure ceramics in ISO 6872:2024 Classes 2–4, while monolithic ceramics are subject to the more stringent 2 limit. HA + 1 wt% 3Y-TZP showed higher Vickers hardness than pure HA before (435.9 ± 26.4 vs. 217.0 ± 5.6 HV0.3) and after testing (426.9 ± 38.9 vs. 196.7 ± 10.5 HV0.3; Bonferroni-adjusted p < 0.001 for both). Pure HA showed a within-route decrease of −20.3 HV0.3 (95% CI: −33.1 to −7.5; adjusted p = 0.048), whereas the selected route showed a change of −9.0 HV0.3 (95% CI: −44.3 to 26.4; adjusted p = 1.000). Direct comparison of the changes was not significant (difference, −11.3 HV0.3; 95% CI: −46.7 to 24.1; adjusted p = 1.000), so differential hardness resistance to the acidic challenge was not demonstrated. Because composition and thermal history were not independently controlled, the findings should be interpreted as route-level screening rather than as an isolated zirconia effect or clinical validation.

The objective of this study was to create injectable photo‐crosslinkable biomaterials, using gelatin methacryloyl (GelMA) hydrogel, combined with a decellularized bone matrix (BMdc) and a deproteinized (BMdp) bovine bone matrix. These were intended to serve as bioactive scaffolds for dentin regeneration. The parameters for GelMA hydrogel fabrication were initially selected, followed by the incorporation of BMdc and BMdp at a 1% (w/v) ratio. Nano‐hydroxyapatite (nHA) was also included as a control. A physicochemical characterization was conducted, with FTIR analysis indicating that the mineral phase was complexed with GelMA, and BMdc was chemically bonded to the amide groups of gelatin. The porous structure was preserved post‐BMdc incorporation, with bone particles incorporated alongside the pores. Conversely, the mineral phase was situated inside the pore opening, affecting the degree of porosity. The mineral phase did not modify the degradability of GelMA, even under conditions of type I collagenase‐mediated enzymatic challenge, allowing hydrogel injection and increased mechanical strength. Subsequently, human dental pulp cells (HDPCs) were seeded onto the hydrogels. The cells remained viable and proliferative, irrespective of the GelMA composition. All mineral phases resulted in a significant increase in alkaline phosphatase activity and mineralized matrix deposition. However, GelMA‐BMdc exhibited higher cell expression values, significantly surpassing those of all other formulations. In conclusion, our results showed that GelMA‐BMdc produced a porous and stable hydrogel, capable of enhancing odontoblastic differentiation and mineral deposition when in contact with HDPCs, thereby showing potential for dentin regeneration.

Objetivo: avaliar o efeito da desinfecção na estabilidade dimensional de três diferentes materiais de moldagem. Material e métodos: utilizando matriz específica (norma ADA.1933) foram obtidos moldes em silicone de adição, poliéter e alginato (n=60) que foram subdivididos em 6 subgrupos (I- controle (apenas lavados); II- Bacterend OX 0,5%; III- Bacterend OX 1%; IV- Bacterend OX 2%; V- peróxido de hidrogênio 1%- BlueM VI-hipoclorito de sódio 1%). Foram realizadas medidas, por um único operador calibrado, em microscópio comparador (Mitutoyo MFG. Co. Ltd., Japão), da matriz metálica e de cada espécime, em pontos determinados. As medidas foram realizadas 3 vezes e a média foi calculada. Foi utilizada a fórmula (A-B/Ax100) para cada espécime. Os dados foram tabulados e analisados estatisticamente. Para avaliar a diferença entre grupos, a variável quantitativa foi testada para distribuição normal com o teste de Shapiro-wilk. A diferença entre dois grupos foi avaliada pelo teste de Man-Withney (p<0,05) Resultados: Comparados aos grupos controle, os subgrupos II, III e V não mostraram alterações dimensionais nos 3 materiais de moldagem; os subgrupos IV (nos materiais AS e P) e todos os subgrupos VI mostraram alteração dimensional estatisticamente significantes. Conclusão Com base nos dados coletados parece lícito concluir que o ácido peracético em equilíbrio 0,5% ou 1% e o peróxido de hidrogênio 1% não promovem alterações dimensionais nos moldes em silicone de adição (VPS), poliéter (Impregum) ou alginato (Hidrogun). Ácido peracético em equilíbrio na concentração 2% não deve ser utilizado em silicones e hipoclorito de sódio 1% em nenhum dos materiais.