Clinical Evaluation of Short and Standard-Length Implants in Posterior Regions of the Partially Edentulous Maxilla and Mandible: A Prospective Comparative Study.

PURPOSE: To compare clinical outcomes of short (6 and 8 mm) and standard-length (11 and 13 mm) implants in posterior sites.

MATERIALS AND

METHODS

In this prospective observational study, implant survival and success rates, soft tissue conditions, and marginal bone level change (MBLC) were observed over a period up to 36 months. Short and standardlength OsseoSpeed Astra Tech implants were used to replace two or three missing teeth. A total of 38 patients-with 42 standard-length implants and 64 short implants-were available for follow-up. Data regarding the patients' medical history and clinical and radiographic parameters were analyzed. No implant loss or mobility was recorded throughout the observation period.

RESULTS

Regarding an MBLC of ≥ 2 mm, no significant difference in the success rates of short (76.9%) and standard-length (76.2%) implants was found. Considering MBLC in each group, success rates of short (88.7%) and standard-length (100%) implants differed significantly (log-rank test, P = .028). Compromised medical history, implant site location (maxilla or mandible), bone quality, type of prosthetic restoration (single nonsplinted or splinted crowns or fixed partial dentures), and keratinized mucosa width ≥ 2 mm were not associated with MBLC. Premature cover screw exposure and MBLC ≥ 2 mm were significantly associated within short implants (P = .045) but not standard-length implants (P = .853). Short implants in smokers were at a higher risk of MBLC > 3/10 of implant length compared to nonsmokers (P = .022).

CONCLUSIONS

Short and standard-length implants revealed comparable survival and success rates regarding MBLC ≥ 2 mm but differed significantly considering MBLC > 3/10 of the endosseous implant length. Short implants are more prone to MBLC compared to standard-length implants, especially in smokers or when premature cover screw exposures occur.