{"doi":"10.1111/iej.12233","title":"Fatigue life enhancement of NiTi rotary endodontic instruments by progressive reciprocating operation","abstract":"<jats:title>Abstract</jats:title><jats:sec><jats:title>Aim</jats:title><jats:p>To evaluate the effect of reciprocating amplitude and progressive angular increment on fatigue life enhancement of NiTi rotary endodontic instruments.</jats:p></jats:sec><jats:sec><jats:title>Methodology</jats:title><jats:p>ProTaper F2 instruments were operated in steel artificial canals with both stationary reciprocating (<jats:styled-content style=\"fixed-case\">SR</jats:styled-content>) and progressive reciprocating (<jats:styled-content style=\"fixed-case\">PR</jats:styled-content>) motions. The <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> motions involved symmetric to and fro reciprocation of ±180<jats:sup>o</jats:sup>, ±135<jats:sup>o</jats:sup>, ±90<jats:sup>o</jats:sup>, ±60<jats:sup>o</jats:sup> and ±45<jats:sup>o</jats:sup>. The <jats:styled-content style=\"fixed-case\">PR</jats:styled-content> motions were ±45<jats:sup>o</jats:sup> stationary motion superimposed with angular increments of 7<jats:sup>o</jats:sup>, 11<jats:sup>o</jats:sup>, 22.5<jats:sup>o</jats:sup> or 31<jats:sup>o</jats:sup> whenever an instrument completed 1, 10 or 30 reciprocating cycles (rc). The fatigue lives were compared with those under continuous rotation (<jats:styled-content style=\"fixed-case\">CR</jats:styled-content>) and a reciprocating operation with a forward 144<jats:sup>o</jats:sup> and backward 72<jats:sup>o</jats:sup> motion proposed by Yared (2008). The statistical significance of these operating modes on fatigue life was examined using one way <jats:sc>anova</jats:sc> and <jats:italic>post hoc</jats:italic> Tukey's tests at <jats:italic>P</jats:italic> = 0.05. Fractographic analysis was also applied to probe the fracture mechanisms of different rotation motions.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Fatigue life increased with decreasing reciprocating amplitude. Operating in the <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> increased fatigue life by 355% over that in the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content>. Except for the 22.5<jats:sup>o</jats:sup> increment, all <jats:styled-content style=\"fixed-case\">PR</jats:styled-content> motions yielded longer fatigue lives than the <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> motion. A progressive reciprocating operation with a ± 45<jats:sup>o</jats:sup> reciprocating amplitude and a + 7<jats:sup>o</jats:sup> progressive angular increment every 10 reciprocating cycles (±45<jats:sup>o</jats:sup>/10rc/+7<jats:sup>o</jats:sup>) increased fatigue life by 990% over that in the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content> motion. In terms of life enhancement over the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content> motion, the larger the curvature the less are the differences between different movements. Single crack initiation sites were found in the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content> and <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> motions, while three crack initiation sites were typical in the ±45<jats:sup>o</jats:sup>/10rc/+7<jats:sup>o</jats:sup> motion.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Fatigue life increased with decreasing reciprocating amplitude in stationary reciprocation. A progressive reciprocating operation with ±45<jats:sup>o</jats:sup>/10rc/+7<jats:sup>o</jats:sup> motion led to significant fatigue life enhancement and multiple fatigue crack initiation in NiTi endodontic instruments.</jats:p></jats:sec>","journal":"International Endodontic Journal","year":2014,"id":659475,"datarank":0.5101796072493234,"base_score":3.4011973816621555,"endowment":3.4011973816621555,"self_citation_contribution":0.5101796072493234,"citation_network_contribution":0.0,"self_endowment_contribution":0.5101796072493234,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":29,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1721525,"name":"Y. H. Huang","orcid":null,"position":1,"is_corresponding":false},{"id":1721527,"name":"C. W. Chi","orcid":null,"position":2,"is_corresponding":false},{"id":1721528,"name":"C. P. Lin","orcid":null,"position":3,"is_corresponding":false},{"id":1721522,"name":"C. S. Shin","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Fatigue life enhancement of NiTi rotary endodontic instruments by progressive reciprocating operation","abstract":"<jats:title>Abstract</jats:title><jats:sec><jats:title>Aim</jats:title><jats:p>To evaluate the effect of reciprocating amplitude and progressive angular increment on fatigue life enhancement of NiTi rotary endodontic instruments.</jats:p></jats:sec><jats:sec><jats:title>Methodology</jats:title><jats:p>ProTaper F2 instruments were operated in steel artificial canals with both stationary reciprocating (<jats:styled-content style=\"fixed-case\">SR</jats:styled-content>) and progressive reciprocating (<jats:styled-content style=\"fixed-case\">PR</jats:styled-content>) motions. The <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> motions involved symmetric to and fro reciprocation of ±180<jats:sup>o</jats:sup>, ±135<jats:sup>o</jats:sup>, ±90<jats:sup>o</jats:sup>, ±60<jats:sup>o</jats:sup> and ±45<jats:sup>o</jats:sup>. The <jats:styled-content style=\"fixed-case\">PR</jats:styled-content> motions were ±45<jats:sup>o</jats:sup> stationary motion superimposed with angular increments of 7<jats:sup>o</jats:sup>, 11<jats:sup>o</jats:sup>, 22.5<jats:sup>o</jats:sup> or 31<jats:sup>o</jats:sup> whenever an instrument completed 1, 10 or 30 reciprocating cycles (rc). The fatigue lives were compared with those under continuous rotation (<jats:styled-content style=\"fixed-case\">CR</jats:styled-content>) and a reciprocating operation with a forward 144<jats:sup>o</jats:sup> and backward 72<jats:sup>o</jats:sup> motion proposed by Yared (2008). The statistical significance of these operating modes on fatigue life was examined using one way <jats:sc>anova</jats:sc> and <jats:italic>post hoc</jats:italic> Tukey's tests at <jats:italic>P</jats:italic> = 0.05. Fractographic analysis was also applied to probe the fracture mechanisms of different rotation motions.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Fatigue life increased with decreasing reciprocating amplitude. Operating in the <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> increased fatigue life by 355% over that in the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content>. Except for the 22.5<jats:sup>o</jats:sup> increment, all <jats:styled-content style=\"fixed-case\">PR</jats:styled-content> motions yielded longer fatigue lives than the <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> motion. A progressive reciprocating operation with a ± 45<jats:sup>o</jats:sup> reciprocating amplitude and a + 7<jats:sup>o</jats:sup> progressive angular increment every 10 reciprocating cycles (±45<jats:sup>o</jats:sup>/10rc/+7<jats:sup>o</jats:sup>) increased fatigue life by 990% over that in the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content> motion. In terms of life enhancement over the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content> motion, the larger the curvature the less are the differences between different movements. Single crack initiation sites were found in the <jats:styled-content style=\"fixed-case\">CR</jats:styled-content> and <jats:styled-content style=\"fixed-case\">SR</jats:styled-content> motions, while three crack initiation sites were typical in the ±45<jats:sup>o</jats:sup>/10rc/+7<jats:sup>o</jats:sup> motion.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Fatigue life increased with decreasing reciprocating amplitude in stationary reciprocation. A progressive reciprocating operation with ±45<jats:sup>o</jats:sup>/10rc/+7<jats:sup>o</jats:sup> motion led to significant fatigue life enhancement and multiple fatigue crack initiation in NiTi endodontic instruments.</jats:p></jats:sec>","is_dataset_classified":null,"base_score":3.4011973816621555,"endowment":3.4011973816621555,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"24355085","pmcid":null,"openalex_id":"https://openalex.org/W2114501500","authors":[],"funders":[{"funder_name":"National Science Council, Taiwan","grant_id":"NSC 96-2628-E-002-223-MY3","title":null}],"total_grants":1,"fwci":2.6347,"citation_percentile":0.88379721,"influential_citations":0,"citation_trend":[{"year":2015,"count":5},{"year":2016,"count":3},{"year":2017,"count":7},{"year":2018,"count":4},{"year":2019,"count":1},{"year":2020,"count":1},{"year":2021,"count":3},{"year":2022,"count":3},{"year":2024,"count":1},{"year":2025,"count":1}],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fiej.12233","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/pdf/10.1111/iej.12233","host_type":"publisher"},{"url":"https://doi.org/10.1111/iej.12233","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/24355085","host_type":"repository"}],"fields_of_study":["Endodontics and Root Canal Treatments","Dental materials and restorations","Dental Anxiety and Anesthesia Techniques","Dental Instruments","Materials Testing","Nickel","Root Canal Therapy","Titanium"],"mesh_terms":["Dental Instruments","Materials Testing","Nickel","Root Canal Therapy","Titanium"],"keywords":["Reciprocating motion","Rotation (mathematics)","Materials science","Amplitude","Nickel titanium","Physics","Composite material","Mathematics","Shape-memory alloy","Optics","Geometry","Bearing (navigation)","Fractographic Analysis","Cyclic Fatigue Failure","Fatigue Life Enhancement","Niti Endodontic Instrument","Progressive Reciprocation","Stationary Reciprocation"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-12T06:59:29.256062Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}