Single implants with different neck designs in the aesthetic zone: a randomized clinical trial

Objectives: To compare single implants in the aesthetic zone with different neck designs for marginal bone-level changes and clinical outcome measures. Materials and methods: Ninety-three patients with a missing anterior tooth in the maxilla were randomly assigned to be treated with an implant with a 1.5mm smooth neck (smooth group), a moderately rough neck with grooves (rough group) or a scalloped moderately rough neck with grooves (scalloped-group). Implants were installed in healed sites and were loaded after 3 months. Follow-up visits were conducted at 6 and 18 months after implant placement. Results: The scalloped group showed significantly more radiographic bone loss from implant placement to 18 months (2.01 +/- 0.77mm) compared with the smooth group (1.19 +/- 0.82mm) and rough group (0.9 +/- 0.57mm). Furthermore the scalloped group showed significantly deeper pocket depths and a higher bleeding score. There were no between-group differences in soft tissue levels. Survival rates were 97% for the smooth group and 100% for the rough and scalloped groups (P>0.05). No significant differences in outcome were found between the smooth group and rough group. Conclusion: For anterior tooth replacements, implants with a scalloped neck showed more marginal bone loss and less favourable clinical outcome compared with implants with a 1.5mm smooth neck or implants with a rough neck.