Immediate- Versus Delayed-Implant Placement Following Tooth Extraction: Survival Analyses and Factors Associated With Survival

AAOMS 89th Annual Meeting, Honolulu, HI, October 2007

Authors
Markiewicz, MR.
Chuang, SK.
Weed, M.
Dodson, TB. 

Abstract
Statement of the Problem: Conventional implant practice dictates a delay between tooth extraction and implant placement. Some investigators advocate inserting implants immediately after the tooth is extracted. Advantages of immediate over delayed implant placement following extraction include shorter treatment time, fewer visits, and a diminished time period of functional and esthetic deficiency. Offsetting the advantages of immediate implant placement may be an increased risk for implant failure.
Purpose: The purpose of this study was to answer the following clinical question: “Among implants inserted, do those placed immediately after tooth extraction, when compared to those placed at some time after tooth extraction, have a decreased likelihood of survival one-year after insertion?” A secondary purpose was to identify prognostic factors associated with one-year implant survival.
Materials and Methods: Using a retrospective cohort design, the investigators enrolled a sample of subjects having at least one implant inserted between 7/1/01-8/31/05 at the Implant Dentistry Centre, Boston, MA. The primary predictor variable was the timing of implant placement following extraction (immediate vs delayed). An immediate implant was defined as an implant inserted immediately following the extraction. A delayed implant was defined as an implant inserted at any time after the day of tooth extraction. The outcome variable was implant survival at one-year after insertion. Secondary explanatory variables were categorized as demographic, health status (e.g. ASA status, tobacco use), implant-specific (diameter, length, coating), anatomic (location), and perioperative variables (e.g. staging, dentoalveolar reconstructive procedures, antibiotic use, implant stability at stage 2). Descriptive statistics, Kaplan- Meir survival analysis, as well as univariate and multivariate Cox proportional hazards regression analyses were completed using SAS (version 9, SAS Institute Inc, Cary, NC). Level of statistical significance was set apriori at α = 0.05. 
Results: The study sample was composed of 161 patients having 963 implants inserted (412 immediate-placed vs. 551 delayed-placed). The mean duration of clinical follow-up amongst the study sample was 26.2 months. The one-year unadjusted Kaplan-Meier survival rates for immediate- and delayed-placed implants were 87.5% and 92.8%, respectively (p_0.06). Multivariate analysis revealed no statistically significant difference in overall follow-up survival time between immediate- and delayed-placed implants (p_0.4) (Hazard Ratio _ 0.7, 95%CI: 0.3, 1.6). After adjusting for potential confounders, factors significantly associated with implant survival (p_0.05) were implant length, bone quality at the implant site, coated implants, two-stage implant placement (insertion and subsequent uncovering at a future visit), and implant stability at the uncovering stage of treatment. 
Conclusions: Implant survival at one year was not statistically statistically different between implants placed immediately after tooth extraction and those placed in a delayed manner in the unadjusted or adjusted analyses. The data support the hypothesis that there is no significant difference in survival between implants immediately or delayed placed following tooth extraction. After adjusting for potential confounders, the investigators found implant staging, implant length, bone quality at the implant site, and coated implants were associated with an increased likelihood of implant survival at five years post-insertion. 
References: Casap N, Zeltser C, Wexler A, Tarazi E, Zeltser R. Immediate placement of dental implants into debrided infected dentoalveolar sockets. J Oral Maxillofac Surg. 2007 Mar; 65(3):384-92 Lindeboom JA, Tjiook Y, Kroon FH. Immediate placement of implants in periapical infected sites: a prospective randomized study in 50 patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006 Jun;101(6):705-10