Histologic analysis of peri-implant soft tissue around external hexagon and morse taper implant connections

Twenty patients rehabilitated with screw-retained full-arch implant-supported prostheses functioning for at least one year were included.This clinical study included 20 patients rehabilitated with screw-retained full-arch implant-supported prostheses in function for at least 1 year. Participants were allocated into two groups according to the implant-abutment connection design: external hexagon (EH; n = 10) and Morse taper (MT; n = 10). One peri-implant soft tissue biopsy specimen was obtained from each patient and processed for hematoxylin-eosin staining. Histological evaluation assessed epithelial hyperplasia, epithelial organization, inflammatory infiltrate intensity, and connective tissue fibrosis. Data normality was assessed using the Shapiro-Wilk test. Intergroup comparisons were performed using the Mann-Whitney U test, with a significance level of = 0.05.Mean epithelial hyperplasia scores were 2.0 in the EH group and 1.6 in the MT group (P = 0.690). Mean fibrosis scores were 2.2 (EH) and 2.4 (MT) (P = 0.841). Inflammatory infiltrate scores were 0.4 in the EH group and 2.0 in the MT group (P = 0.095). No statistically significant differences were observed between groups for any evaluated parameter. The combined histologic score also showed no significant intergroup difference (P = 0.222).Within the limitations of this clinical study, peri-implant soft tissue architecture and inflammatory profiles were similar between external hexagon and Morse taper implant-abutment connections in full-arch rehabilitations following at least one year of functional loading.