Comparative evaluation of dentin microcrack formation after root canal preparation with different nickel-titanium instrument systems based on micro-CT: a systematic review and meta-analysis.
- 1The State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan, Hubei, 430079, China.
- 2Center for Evidence-Based Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China.
- 3The State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan, Hubei, 430079, China. [email protected].
Abstract
Background
Dentin microcracks following root canal treatment may progress to vertical root fractures, a severe clinical complication. Engine-driven nickel-titanium (NiTi) instruments are associated with dentin microcrack initiation, but current evidence remains inconsistent. This review systematically synthesizes micro-CT-derived evidence on the effects of different NiTi instrument systems on dentin microcrack formation.Methods
A systematic search of PubMed, EMBASE, Scopus, Web of Science, Cochrane Library, and grey literature was performed from inception to October 1, 2025. Eligible studies were ex vivo investigations comparing dentinal microcrack incidence after root canal preparation with various NiTi instruments. Two reviewers independently conducted study selection, data extraction, and risk-of-bias assessment using adapted JBI and CRIS checklists; meta-analysis was performed for sufficient comparable data.Results
Twenty-four ex vivo studies were included from 256 initially retrieved records, covering all tested NiTi instrument subgroups with a pooled total sample of 1082 extracted mandibular and maxillary teeth. Studies testing instruments including RECIPROC, WaveOne, ProTaper Next, the HyFlex series, and TRUShape reported a 0% microcrack incidence under specific experimental conditions. Meta-analysis revealed the following findings: (1) Thermally treated instruments had significantly lower microcrack incidence than conventional ones (pooled incidence: 1% vs. 9%, p = 0.0046); (2) ProTaper Gold had significantly lower microcrack incidence than ProTaper Universal (pooled incidence: 3% vs. 16%, p = 0.0403); (3) ProTaper Universal had higher microcrack incidence in moderately to severely curved canals (20°-40°) (30%) than mildly curved canals (< 20°) (11%), though the difference was not statistically significant (p = 0.2230); (4) There was no significant difference in microcrack incidence between reciprocating and rotary instruments (p = 0.2095); (5) No significant difference in microcrack incidence between RECIPROC Blue and WaveOne Gold, both reciprocating systems (p = 0.3978); (6) WaveOne Gold did not differ significantly from conventional WaveOne (p = 0.6813), nor did RECIPROC Blue from conventional RECIPROC (p = 0.5334); (7) XP-endo instruments consistently demonstrated an almost 0% microcrack incidence across studies. They may effectively prevent dentinal microcracks even in moderately to severely curved canals. Funnel plot showed good symmetry, indicating no significant publication bias.Conclusion
Within the limitations of this ex vivo meta-analysis, instrument kinematics did not influence microcrack formation, while thermally treated NiTi instruments significantly reduced risk. Thermally treated systems are preferred, and highly flexible, advanced-design instruments should be prioritized for curved canals to minimize dentin microcracks.
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BibTeX
@article{li2026comparative,
title = {{Comparative evaluation of dentin microcrack formation after root canal preparation with different nickel-titanium instrument systems based on micro-CT: a systematic review and meta-analysis.}},
author = {Ang Li and Jimin Zhang and Yijun Lin and Huiying Dai and Feiyang Guo and Min Nie},
journal = {BMC oral health},
year = {2026},
month = jul,
doi = {10.1186/s12903-026-09363-7},
url = {https://europepmc.org/article/MED/42897518},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Comparative evaluation of dentin microcrack formation after root canal preparation with different nickel-titanium instrument systems based on micro-CT: a systematic review and meta-analysis.
AU - Ang Li
AU - Jimin Zhang
AU - Yijun Lin
AU - Huiying Dai
AU - Feiyang Guo
AU - Min Nie
PY - 2026
DA - 2026/07/01
JO - BMC oral health
DO - 10.1186/s12903-026-09363-7
UR - https://europepmc.org/article/MED/42897518
AB - Background Dentin microcracks following root canal treatment may progress to vertical root fractures, a severe clinical complication. Engine-driven nickel-titanium (NiTi) instruments are associated with dentin microcrack initiation, but current evidence remains inconsistent. This review systematically synthesizes micro-CT-derived evidence on the effects of different NiTi instrument systems on dentin microcrack formation.Methods A systematic search of PubMed, EMBASE, Scopus, Web of Science, Cochrane Library, and grey literature was performed from inception to October 1, 2025. Eligible studies were ex vivo investigations comparing dentinal microcrack incidence after root canal preparation with various NiTi instruments. Two reviewers independently conducted study selection, data extraction, and risk-of-bias assessment using adapted JBI and CRIS checklists; meta-analysis was performed for sufficient comparable data.Results Twenty-four ex vivo studies were included from 256 initially retrieved records, covering all tested NiTi instrument subgroups with a pooled total sample of 1082 extracted mandibular and maxillary teeth. Studies testing instruments including RECIPROC, WaveOne, ProTaper Next, the HyFlex series, and TRUShape reported a 0% microcrack incidence under specific experimental conditions. Meta-analysis revealed the following findings: (1) Thermally treated instruments had significantly lower microcrack incidence than conventional ones (pooled incidence: 1% vs. 9%, p = 0.0046); (2) ProTaper Gold had significantly lower microcrack incidence than ProTaper Universal (pooled incidence: 3% vs. 16%, p = 0.0403); (3) ProTaper Universal had higher microcrack incidence in moderately to severely curved canals (20°-40°) (30%) than mildly curved canals (< 20°) (11%), though the difference was not statistically significant (p = 0.2230); (4) There was no significant difference in microcrack incidence between reciprocating and rotary instruments (p = 0.2095); (5) No significant difference in microcrack incidence between RECIPROC Blue and WaveOne Gold, both reciprocating systems (p = 0.3978); (6) WaveOne Gold did not differ significantly from conventional WaveOne (p = 0.6813), nor did RECIPROC Blue from conventional RECIPROC (p = 0.5334); (7) XP-endo instruments consistently demonstrated an almost 0% microcrack incidence across studies. They may effectively prevent dentinal microcracks even in moderately to severely curved canals. Funnel plot showed good symmetry, indicating no significant publication bias.Conclusion Within the limitations of this ex vivo meta-analysis, instrument kinematics did not influence microcrack formation, while thermally treated NiTi instruments significantly reduced risk. Thermally treated systems are preferred, and highly flexible, advanced-design instruments should be prioritized for curved canals to minimize dentin microcracks.
SN - 1472-6831
ER -