A comparative evaluation of peri-implant soft and hard tissues between internal hexagonal and internal conical type of implant-abutment connection: A randomized controlled trial.

AIM: To compare the effect of internal hexagonal and internal conical implant-abutment connection (IAC) on peri-implant hard and soft tissues.

SETTINGS AND

DESIGN

Parallel arm, randomized controlled trial.

MATERIALS AND

METHODS

A total of 44 participants requiring rehabilitation with single implant-supported crown in the posterior region were enrolled and randomly allocated to two groups (n = 22). Participants in Group 1 were rehabilitated with implants with internal hexagonal IAC while in Group 2 with implants having internal conical IAC. Following delayed loading protocol, implants were restored with single implant-supported crown and baseline data along with subsequent follow up data at 3rd, 6th, and 12th months after occlusal loading were recorded.

STATISTICAL ANALYSIS USED: Data were analyzed using the Statistical Packages for Social Sciences (SPSS) version 29.0. Categorical variables were represented as counts/percentages, whereas continuous variables were denoted as mean ± standard deviation. Unpaired t-tests and Chi-square tests were used for group comparisons.

RESULTS

At 12 months, crestal bone loss was lower in the internal conical group (0.78 ± 0.03 mm) than the internal hexagonal group (0.81 ± 0.02 mm; P < 0.001). Probing depth was consistently shallower in the internal conical group (3.17 ± 0.09 mm vs. 3.47 ± 0.17 mm; P < 0.001). Interleukin-1β levels were significantly lower in the internal conical group across all time points, with large effect sizes.

CONCLUSION

Internal conical IAC showed lower inflammation, improved bone preservation, and shallower probing depths compared to internal hexagonal IAC. Despite small structural effect sizes, the inflammatory response indicated a meaningful biological advantage. Both IAC remain viable, with selection guided by patient-specific needs and long-term outcomes.