Clinical evaluation of narrow diameter implants versus standard diameter implants with bone augmentation in posterior jaws:study protocol for a randomized controlled clinical trial

Background: Nowadays, narrow diameter implants are being increasingly used in posterior regions with insufficient bone width to avoid invasive bone augmentation procedures. Recent studies have indicated that narrow implants with a diameter of 3.3 to 3.5mm showed comparable survival rate with standard diameter implants. However, there are no high-quality clinical trials comparing the clinical outcomes of narrow diameter implants to standard diameter implants with augmentation procedures in atrophic posterior region. The purpose of present study is to evaluate the clinical efficacy of narrow diameter implants in posterior jaws. Methods/Design: This study is designed as a prospective, single-center, 2-arm parallel, randomized controlled clinical trial. Patients in need of single implant crowns in posterior jaws will be included in the study according to clear defined inclusion-and-exclusion criteria. Randomized number table will be used to assign the patients into two groups: group 1: narrow diameter implant group (NDI); group 2: standard diameter implant with bone augmentation group (SDI). Implant survival rate, mechanical complications, marginal bone loss, peri-implant conditions and patients’ satisfaction will be recorded. Clinical and radiological re-evaluations will be performed at 6, 12, 36, 60 months after the final crowns delivery. Discussion: Our findings will help evaluate the clinical efficacy of narrow implant in posterior region. If the results were favorable, narrow implants might be recommended as a viable alternative for posterior region with insufficient bone width. Trial registration: Clinicaltrials.gov identifier: ChiCTR1800020426 (registered on 29 December 2018)