Long-term effectiveness of 6 mm micro-rough implants in various indications: A 4.6- to 18.2-year retrospective study

To evaluate the long-term effectiveness of 6 mm implants in various indications with a micro-rough surface after 4.6-18.2 years in function and to assess key factors associated with implant survival, success, and biologic/technical complications.

Fifty-five patients with seventy-four 6 mm implants placed from 2000 to 2013 attended the re-examination assessing well-established clinical and radiographic parameters, biologic and prosthetic complications, and patient-reported outcome measures.

Five implants were lost after a mean follow-up period of 9.1 years resulting in a survival rate of 93.2%. All losses occurred in free-end situations in the mandible. Smoking habit significantly reduced implant survival (hazard ratio 36.25). Two implants exhibited a history of peri-implantitis, and one implant showed progressive marginal bone loss (MBL) resulting in a success rate of 89.2%. The mean MBL amounted to 0.029 mm. Increased MBL was found for implants placed in the maxilla (0.057 mm) and for implants with a diameter of 4.1 mm (0.043 mm). Soft tissue thickness (1.39 mm) and width of keratinized mucosa (1.91 mm) had no effect on MBL. Patient-reported outcome measures showed high satisfaction (mean VAS scores 88%) and high quality of life (mean OHIP-G14 score 2.2).

The present study demonstrated survival and success rates of 93.2% and 89.2% for 6 mm implants used in various indications. A factor leading to higher implant failure was smoking, whereas modulating factors increasing annual MBL included implants placed in the maxilla and implants with a diameter of 4.1 mm compared to 4.8 mm.