Evidence map›Paper›PMID 39920428›Full record

ArticleClinical oral investigations2025

Dynamic photoelastic analysis of stress distribution in simulated canals using different heat-treated flat-side rotary instruments.

Kleber Kildare Teodoro de Carvalho, Paulo Takeji Moriya, Anil Kishen, Jorge N R Martins, Emmanuel João Nogueira Leal Silva, Murilo P Alcalde, Francisco Manuel Braz Fernandes, Erick Miranda Souza, Marco Aurélio Versiani

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Article in Clinical oral investigations, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.

0numbers the graph read from it
0cells of the map it votes in
5citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

5 citing papers in PubMed.

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4 · The record

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PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

9 authors.

Kleber Kildare Teodoro de CarvalhoDepartment of Endodontics, Núcleo de Estudos Odontológicos (NEO), São Paulo, Brazil.
Paulo Takeji MoriyaPrivate Practice, São Bernardo do Campo, São Paulo, Brazil.
Anil KishenFaculty of Dentistry, University of Toronto, Toronto, ON, M5G 1G6, Canada.
Jorge N R MartinsDepartment of Endodontics, Faculdade de Medicina Dentária, Universidade de Lisboa, Lisbon, Portugal.
Emmanuel João Nogueira Leal SilvaDepartment of Endodontics, Fluminense Federal University, Rio de Janeiro, Brazil.
Murilo P AlcaldeBauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
Francisco Manuel Braz FernandesCENIMAT/I3N, Department of Materials Science, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal.
Erick Miranda SouzaDepartment of Dentistry II, Federal University of Maranhão, São Luís, Maranhão, Brazil.
Marco Aurélio VersianiDepartment of Endodontics, Fluminense Federal University, Rio de Janeiro, Brazil. marcoversiani@yahoo.com.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

objectivesThis study aimed to compare the stress produced by three heat-treated flat-side prototype rotary instruments and a non-flat side instrument on the internal walls of simulated canals with three different curvature degrees using the photoelastic technique. MATERIALS AND

methodsThirty-six resin blocks with simulated canals, comprising three curvature types (45°, 60°, and double curvature), were used in the study, with 12 blocks allocated to each curvature type. These blocks were further divided into four experimental groups (n = 9 per group) based on the heat treatment of the instruments: gold, silver, blue, and a control group with non-flat-side gold instruments. The blocks were analyzed using a circular polariscope setup, with real-time birefringence patterns captured by a digital camera. Stress on canal walls was evaluated using a semi-quantitative scale. Supplementary tests (stereomicroscope, SEM, energy-dispersive X-ray spectroscopy, and DSC) were performed to interpret the results further. Data were analyzed using the Kruskal-Wallis test (α = 5%).

resultsInter- and intra-observer agreements were 0.91 and 1, respectively. All instruments exhibited high stress patterns on canal walls. The highest stress was observed in the 45° and 60° blocks (middle third) and the double curvature blocks (apical third). The flat-side gold instrument recorded the highest stress in the coronal third, and the flat-side blue in the apical third (p < 0.05). All instruments displayed some degree of distortion after use.

conclusionsInstrument type and canal curvature significantly influenced stress distribution across root canal thirds. All flat-side instruments exhibited high stress patterns, warranting caution in curved canals due to potential distortion and performance impact. CLINICAL RELEVANCE: This study recommended caution when using newly designed flat-side instruments in curved canals due to potential stress on canal walls and greater distortion, which may affect performance and durability.

Indexed as

Dental InstrumentsDental Pulp CavityDental Stress AnalysisRoot Canal PreparationElasticityEquipment DesignHot TemperatureHumansMaterials TestingMicroscopy, Electron, ScanningSpectrometry, X-Ray EmissionStress, MechanicalSurface PropertiesFlat-sideNickel-titaniumPhotoelasticityPhotoelastic modelRotary instrumentsStress distribution

Identifiers

PMID39920428

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.