The effect of triangular cross-section neck design on crestal bone stability in the anterior mandible: A retrospective study with a 5-year follow-up.

OBJECTIVES: The objective of this study, which included a 5-year follow-up, was to compare peri-implant soft tissue health, crestal bone loss (CBL), and buccal bone thickness (BBT) around triangular cross-section neck (TN) or round neck (RN) implants, using cone-beam computed tomography.

MATERIALS AND METHODS: This study was initially designed as a prospective 1-year randomized controlled study and then extended with a 5-year retrospective evaluation of clinical and radiographic records. In the initial 1-year study, a total of 20edentulous patients receiving 40 implants with similar diameters were randomly assigned to the RN or TN groups using a split-mouth design. Pocket probing depths (PPD), plaque index (PI), and gingival index (GI) were recorded at postoperative month 12. CBL and BBT at three levels (0, -2, and -4 mm) were evaluated 1 year after insertion. Five years after insertion, PPD, PI, GI, CBL, and BBT were recorded as patients were recalled for clinical and radiographic monitoring.

RESULTS: Nineteen patients completed the study. After 5 years, no significant differences in PPD, PI, and GI scores and BBT values between the two groups (p > .05). The mean ± SD CBL values at the final follow-up visit were -0.71 ± 0.69 mm for TN and -1.03 ± 0.86 mm for RN (p < .01).

CONCLUSIONS: These results suggest better crestal bone preservation using implants with TN when compared to RN after a 5-year follow-up. However, TN showed similar results to RN regarding peri-implant soft tissue health and BBT.