Effect of retreatment instruments on microcrack formation: a microcomputed tomography study

Area of Science:

• Endodontics
• Dental Materials Science
• Biomaterials

Background:

• Root canal retreatment is a common dental procedure.
• Assessing the potential for iatrogenic damage during retreatment is crucial for preserving tooth structure.
• Microcracks can compromise the long-term prognosis of endodontically treated teeth.

Purpose of the Study:

• To compare the incidence of microcracks in root canal-prepared teeth using three different retreatment systems.
• To evaluate the efficacy of ProTaper Universal Retreatment (PTUR), Mtwo Retreatment (MTR), and D-RaCe (D-RC) systems in terms of microcrack formation.

Main Methods:

• Forty-two mandibular premolars were instrumented and obturated.
• Specimens were divided into three groups (n=14) for retreatment with PTUR, MTR, or D-RC systems.
• High-resolution microcomputed tomography (micro-CT) was used to scan teeth before instrumentation, after obturation, and after retreatment to detect microcracks.

Main Results:

• The ProTaper Universal Retreatment (PTUR) system exhibited the highest percentage of microcracks.
• The Mtwo Retreatment (MTR) and D-RaCe (D-RC) systems resulted in comparable and lower numbers of microcracks than PTUR.
• All evaluated retreatment systems were associated with the formation of microcracks.

Conclusions:

• All tested root canal retreatment systems have the potential to induce microcracks in teeth.
• Clinicians should exercise caution and be aware of the risk of microcrack formation when performing root canal retreatment.
• Further research may explore modifications to retreatment protocols to minimize microcrack propagation.