Spectrophotometric evaluation of coronal discoloration induced by intracanal medicament-scaffold combinations in regenerative endodontic treatment

To comparatively evaluate the effect of different intracanal medicament and blood-derived scaffold combinations on coronal discoloration in regenerative endodontic treatment (RET) using a standardized in vitro model. Two hundred extracted human maxillary incisors were prepared to simulate immature permanent teeth and randomly assigned to four intracanal medicament groups ( n = 50 each): UltraCal XS, Bio-C Temp, modified triple antibiotic paste (mTAP), and no-medicament control. After a 3-week medicament phase, each group was subdivided according to the scaffold used ( n = 10): blood clot, platelet-rich plasma (PRP), leukocyte- and platelet-rich fibrin (L-PRF), advanced platelet-rich fibrin (A-PRF), and injectable platelet-rich fibrin (i-PRF), resulting in 20 experimental groups. Color measurements were obtained with a spectrophotometer at baseline (T0), during the medicament phase (T1-T3), and after scaffold placement (T4-T6). Color change was calculated using the CIEDE2000 (ΔE00) formula. Intergroup comparisons were performed using one-way ANOVA with Tukey post hoc testing, and time-dependent changes were analyzed using repeated-measures ANOVA and two-way mixed ANOVA (α = 0.05). Coronal discoloration was significantly influenced by the intracanal medicament-scaffold combination. Within the mTAP groups, scaffold-dependent differences were significant at T5 and T6 ( p = 0.006 and p = 0.001, respectively), with the blood clot subgroup showing the greatest discoloration. Within the control groups, scaffold-dependent differences were significant at all post-scaffold time points (T4-T6; all p < 0.001), whereas no significant scaffold-dependent differences were observed within the UltraCal XS or Bio-C Temp groups (all p > 0.05). Significant time-dependent increases in discoloration were observed in the Bio-C Temp/blood clot and Bio-C Temp/A-PRF subgroups (both p < 0.001), in the mTAP/blood clot subgroup ( p = 0.005), and in the control/L-PRF and control/A-PRF subgroups ( p = 0.024 and p = 0.041, respectively). A significant group × time interaction confirmed that post-scaffold discoloration patterns differed according to the specific medicament–scaffold combination ( p < 0.05). The most unfavorable discoloration profile was observed in the mTAP groups, particularly when combined with blood clot, whereas calcium-based medicaments showed a more favorable and stable color behavior. Among the blood-derived scaffolds, PRP and i-PRF were associated with the most favorable color profiles.