A retrospective study evaluating the survival and radiographic outcome of implants with low primary stability
15541 Poster Display Clinical Research – Peri-implant Biology
Background
Primary implant stability has been considered one of the important predictors for long-term success of implant therapy. However, proper initial stability of implants might not be attained owing to overpreparation of osteotomy site or poor bone quality of implantation site. Nevertheless, with help of development of implant surface modification, vital bone formation achieved by secondary stability can lead to the success of implant osseointegration.
Aim/Hypothesis
There is a need of more studies on whether low primary implant stability would negatively influence the success of implant therapy. Therefore, this retrospective study analyses outcomes of implants placed with low primary stability and factors that may be related to implant failures.
Material and Methods
This retrospective study included 156 patients, restored with 169 implants that presented manual rotation when placing the cover screw or healing abutment at the time of implant placement within an observed follow-up time of a minimum of 34 days and a maximum of 9.28 years. All implant surgeries were performed by 11 experienced surgeons at a single specialist clinic, Department of Periodontology, Dental Hospital of Yonsei University, Seoul, Korea from 2008 to 2018. Descriptive statistics, survival analyses (life tables and Kaplan-Meier estimates), and radiographic assessment based on marginal bone level measurements were performed. Four Kaplan-Meier analyses were performed, depending on the 1)type of surgery 2)bone quality 3)implant position of the jaw, and 4)unit of prosthesis. A final sample of 86 patients with 93 implants were included in radiographic assessment where the MBLs were grouped into 2 groups of 0–2-year and 2–4-year interval and compared under 4 factors aforementioned.
Results
7 implants failed in 7 patients, rendering cumulative survival rates (CSR) of 94.74% (95% CI- 89.11–97.50) and 94.33% (95% CI- 88.30–97.30) at implant- and patient-level, respectively. Kaplan-Meier estimates showed implant loss was found only in advanced surgery group (7 implant loss in 82 implants) when compared to simple surgery group (no implant loss in 87 implants) (P = 0.005), and no significant difference were found in CSRs between implants under bone quality (P = 0.059), position of the jaw (P = 0.254), and unit of prosthesis (P = 0.369). No significant differences were found between MBL changes under type of surgery and implant position of the jaw.
Conclusion and Clinical Implications
Within the limitations of this retrospective study, implant placement with low primary stability might not negatively affect the survival rates of implants provided that a protected and unloaded healing is guaranteed. The information that dealt with a relatively large sample size, the use of different implant systems, surgical techniques, and various implant locations may provide clinicians with useful information and also add to the external validity of the present study.
