Estabilidade de cor de diferentes sistemas cerâmicos fresados no CAD/CAM e polidos com diferentes métodos / Color stability of different ceramic systems milled in CAD/CAM and polished with different methods

A descoloração ou perda de translucidez dos materiais cerâmicos usados em odontologia ainda hoje é um problema, especialmente pelo comprometimento estético. Com o objetivo de comparar a estabilidade de cor, blocos de dissilicato de lítio (IPS e.max CAD HT) e de silicato de lítio reforçado com zircônia (Vita Suprinity HT) fresados no desenho de um disco com dimensões de 1,5 × 7 × 12 mm3 (n = 120) foram preparados usando 3 procedimentos de acabamento de superfície: glaze, polimento mecânico e coloração externa e glaze. Em seguida, cada grupo foi dividido em 2 subgrupos de armazenamento, chá preto e café (n = 10/grupo). As mensurações de cor foram medidas com espectrofotômetro (VITA Easyshade) no estágio inicial e após 1 semana, 2 semanas, 1 mês, 2 meses de armazenamento. As alterações de cor (ΔE) foram calculadas e analisadas estatisticamente usando ANOVA (α < 0,05). Observamos que, para ambos os materiais cerâmicos, o procedimento de glaze apresentou valores de mudança de cor estatisticamente menores do que os outros grupos (p < 0,05) após o armazenamento em ambas as bebidas. Os grupos de dissilicato de lítio apresentaram valores de alteração de cor estatisticamente menores em relação aos grupos de silicato de lítio reforçados com zircônia. Conclui-se que, o glaze sozinho levou a uma maior estabilidade de cor em relação ao polimento mecânico e coloração externa o dissilicato de lítio apresentou maior estabilidade de cor em comparação com o silicato de lítio reforçada com zircônia.

The discoloration or loss of translucency of ceramic materials used in dentistry is still a problem today, especially due to aesthetic compromise. In order to compare color stability, lithium disilicate (IPS e.max CAD HT) and zirconia-reinforced lithium silicate (Vita Suprinity HT) blocks were milled into a disc design with dimensions of 1.5 × 7 × 12 mm3 (n = 120). The specimens were prepared using 3 surface finishing procedures: glaze, mechanical polishing and external staining and glaze. Then, each group was divided into 2 storage subgroups, black tea and coffee (n = 10/group). Color measurements were measured with a spectrophotometer (VITA Easyshade) at the initial stage and after 1 week, 2 weeks, 1 month, 2 months of storage. Color changes (ΔE) were calculated and statistically analyzed using ANOVA (α < 0.05). We observed that, for both ceramic materials, the glaze procedure presented statistically lower color change values ​​than the other groups (p < 0.05) after storage in both beverages. The lithium disilicate groups showed statistically lower color change values ​​than the zirconia-reinforced lithium silicate groups. It is concluded that, glaze alone led to greater color stability compared to mechanical polishing and external staining, lithium disilicate showed greater color stability compared to zirconia-reinforced lithium silicate.

Comparative Clinical Study Using Short and Conventional Implants in Bilateral Jaw Posteriors.

The aim of this study was to clinically and radiographically compare extra short and standards implants. Forty-two implants were installed in 10 selected patients. They received prosthetic loading only after the conventional waiting time for osseointegration and the prostheses were made ferulized. Radiographic shots were performed to evaluate vertical and horizontal bone losses at times T1 (prosthetic installation), T2 (6 months follow-up) and T3 (12 months follow-up). Biological parameters such as bone level around the implants (CBL) were evaluated, CBL alteration (CBLC), total crown length (TCL) and implant/crown ratio (ICR) were digitally calculated. All implants included in the study were submitted to the analysis of the implant stability quotient (ISQ) at the time of implant installation (T0) and at 12 months of prosthetic function (T3). Data were statistically tested. The ICR was higher in the test group than in the control group (p<0.0001). The CBL measurements at the beginning of the study were 0.21±0.19 mm and 0.32±0.38 mm and at 12 months 0.65±0.24 mm and 0.87±0.34 mm, respectively in the test and control groups. CBLCs and CBL were similar at all times (p>0.05). No correlation was found between CBLC and ICR parameters, as well as between ISQ and implant length. We may conclude that standards and extra short implants can provide similar clinical results in prosthetic rehabilitation of the atrophic jaw over 12 months of follow-up.