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This process yielded 48 resin replicas per specimen (total\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200996), evenly distributed into six groups (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u20098 per group). Each group underwent instrumentation with either WaveOne Gold (WOG) or ProTaper Next (PTN) nickel-titanium (NiTi) systems via one of three access approaches: traditional lingual (TLAC), incisal ridge (IAC), or labial (LaAC). Pre- and post-instrumentation micro-computed tomographic scans were analyzed for iatrogenic errors, canal volume\/surface area changes, unprepared areas, and apical diameter. Data were statistically evaluated using three-way analysis of variance (ANOVA) with LSD post hoc test, with the significance level set at\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.05.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Canal straightening occurred only in the LaAC and IAC groups (9 cases each), whereas apical perforations (22 cases) were exclusive to Specimen 2 replicas. Three-way ANOVA revealed that percentage increases in canal volume and surface area, proportion of unprepared area, and maximum apical diameter following instrumentation were all significantly affected by tooth prototype (all\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001), accessing cavity design (all\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.01), and the instrument used (all\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.01). In Specimen 1 replicas (spacious canals), PTN with TLAC resulted in a lower proportion of unprepared areas than PTN with LaAC (36.7% \u00b1 8.9% vs. 47.6% \u00b1 7.8%;\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.05); however, both techniques preparing only one canal. In contrast, PTN with IAC prepared both canals and achieved the most complete preparation (18.8% \u00b1 3.2% unprepared,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.05). The use of WOG significantly improved outcomes in the LaAC group, reducing unprepared areas to 13.9% \u00b1 4.8% (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.05). Similar trends emerged in Specimen 2 replicas, though the narrower anatomy increased procedural difficulty. WOG consistently outperformed PTN: IAC prepared both canals in all cases (8\/8), while LaAC succeeded in 87.5% (7\/8). Unprepared surfaces were significantly lower with IAC (8.0% \u00b1 5.5%) and LaAC (9.3% \u00b1 8.2%) than with TLAC (34.2% \u00b1 5.1%; both\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.01).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>IAC demonstrated superior efficacy for instrumentation of mandibular incisors with Vertucci Type III canals compared to TLAC and LaAC. WOG enhanced LaAC performance and surpassed PTN overall. Access design and instrument selection critically influence procedural success.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s12903-026-07991-7","type":"journal-article","created":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T00:29:39Z","timestamp":1772238579000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Influence of access cavity design on instrumentation efficiency in 3D-printed replicas of mandibular incisors with Vertucci Type III canals"],"prefix":"10.1186","volume":"26","author":[{"given":"Lu","family":"Wang","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Panpan","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenyuan","family":"Zhou","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhongyang","family":"Shan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chao","family":"Liu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yifen","family":"Shen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nan","family":"Geng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yongchun","family":"Gu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,2,28]]},"reference":[{"key":"7991_CR1","volume-title":"Woelfel\u2019s dental anatomy","author":"RC Scheid","year":"2012","unstructured":"Scheid RC. 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J Endod. 1999;25(3):206\u20137.","journal-title":"J Endod"}],"container-title":["BMC Oral Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/article\/10.1186\/s12903-026-07991-7","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12903-026-07991-7.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12903-026-07991-7.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T19:03:10Z","timestamp":1781636590000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1186\/s12903-026-07991-7"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,28]]},"references-count":48,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,12]]}},"alternative-id":["7991"],"URL":"https:\/\/doi.org\/10.1186\/s12903-026-07991-7","relation":{},"ISSN":["1472-6831"],"issn-type":[{"value":"1472-6831","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,28]]},"assertion":[{"value":"28 September 2025","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"20 February 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"28 February 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The human mandibular incisors used in this study were obtained from the Department of Dentistry, Ninth People\u2019s Hospital of Suzhou. All methods have been performed in accordance with the Declaration of Helsinki and have been approved by the Ethics Committee of Ninth People\u2019s Hospital of Suzhou with the approval number # KY2022-089-01. Informed consent was obtained from all subjects and\/or their legal guardian(s).","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethics approval and consent to participate"}},{"value":"Not applicable.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Consent for publication"}},{"value":"The authors declare no competing interests.","order":4,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing interests"}}],"article-number":"596"}}