In-vivo evaluation of potential optical changes in the peri-implant soft tissue caused by implant-supported fixed prostheses using titanium abutment infrastructure

The aim of this study is to evaluate, in vivo, the potential optical changes that may occur in the peri-implant soft tissue (PST) following implant applications. A total of 90 implants placed in the maxilla (anterior region = 39; premolar region = 51) of 46 patients (female = 26; male = 20) were included in the study. Titanium abutments and metal-supported porcelain restorations were used in the fabrication of the prostheses. Initial color measurements (L0*, a0*, b0*) were taken prior to implant surgery; the second color measurements (L1*, a1*, b1*) were taken with healing caps in place; the third color measurements (L2*, a2*, b2*) were taken upon delivery of the prostheses; and the fourth color measurements (L3*, a3*, b3*) were taken one month after permanent cementation, all performed with a colorimeter. The first-to-second measurement difference was calculated as (∆E00*)1, the first-to-third measurement as (∆E00*)2, and the first-to-fourth measurement as (∆E00*)3. Statistical analyses were conducted using Friedman and Wilcoxon tests with Bonferroni correction, and Mann-Whitney U test was applied for anterior PST and premolar PST comparisons. Significant differences were found in PST values. The L0* values (APST = 62.7; PPST = 63.2) were higher than the L1*, L2*, and L3* values. In the APST group, the a0* value (11.4) was lower than the a1*, a2*, and a3* values, while in the PPST group, the highest a* value was observed in a0* (13.3). The b0* values in both the APST and PPST groups were lower than the b1*, b2*, and b3* values. In the APST group, a2* and a3* values showed a significant increase compared to the a0* value (p<0.05), and the b3* value significantly increased compared to the b0* value (p<0.05). All ∆E00* values in the APST and PPST groups indicated a clinically 'incompatible' (∆E00*>1.8) color change. The ∆E00* values in the PPST group were higher than those in the APST group, with the greatest color change observed between the first and second measurements in the PPST group ((∆E00*)1 = 4.54). In implant-supported fixed prostheses using titanium abutments and metal-supported porcelain, the brightness of the peri-implant soft tissue color decreases across different treatment stages and outcomes, with a shift toward a more yellow hue.