Dentinal Defects, Cracks, and Fracture Generation during Ultrasonic Root-End Preparation: A Systematic Review and Meta-Analysis of In Vivo Studies.

Abstract

Introduction: To evaluate whether ultrasonic root-end preparation in surgical endodontics contributes to the formation of cracks, fractures, or dentinal defects.

Methods: This systematic review was registered with prospective register of systematic reviews (CRD42021251665) and conducted in accordance with the preferred reporting items for systematic reviews and meta analyses 2020 guidelines. Only clinical studies involving surgical endodontics, human participants, and ultrasonic tips for root-end preparation were included; in vitro and animal studies were excluded. A comprehensive search was performed across PubMed, Clinical Trial Registry, and Cochrane databases. Prevalence data on cracks, dentinal defects, and fractures were extracted from the included studies and analyzed using MedCalc (v22.023). The strength of evidence was assessed using Agency for Healthcare Research and Quality standards. Bias in randomized controlled trials was assessed using the Cochrane Risk of Bias-2 tool, while the Joanna Briggs Institute Critical Appraisal tools were used to evaluate bias in cohort studies.

Results: Seventeen studies met the inclusion criteria: five investigated cracks, one assessed both cracks and fractures, three evaluated dentinal defects and fractures, and eight focused solely on fractures. A meta-analysis was conducted for thirteen of these studies. Five studies reported a 4.5% prevalence of crack with up to 3 years follow-up, while five other studies reported a 2.6% prevalence of fracture with the same timeframe. Prevalence increased to 5.3% in another three studies with 10 years follow-up. A 40% prevalence of dentinal defects was observed in three studies with up to 3 years of follow-up. Cracks did not significantly impact healing based on the risk ratio but did increase the hazard ratio (HR) for development at 3 years. Dentinal defects significantly affected the healing as per risk ratio but did not increase the HR for development at 3 years; while fractures significantly impacted the risk and HR. Significantly greater fractures were seen in retreatment cases and posterior teeth. A key limitation of this review is that most included studies were cohort design, with only two randomized controlled trials. Moreover, there is a lack of studies directly comparing ultrasonic root-end preparation with other methods, limiting the strength of the conclusions.

Conclusions: Ultrasonic root-end preparation results in a significantly greater number of dentinal defects than cracks and fractures. Fractures and dentinal defects impacted healing significantly, while cracks did not. Besides, cracks and fractures also increased the HR for any surviving tooth at 3 year analysis.