{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,29]],"date-time":"2026-08-29T05:17:54Z","timestamp":1787980674028,"version":"build-2784847793"},"reference-count":34,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T00:00:00Z","timestamp":1787788800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Peking University School and Hospital of Stomatology","award":["PKUSS-NCRI-24B02"],"award-info":[{"award-number":["PKUSS-NCRI-24B02"]}]},{"award":["PKUSS-NCRI-24B02"],"award-info":[{"award-number":["PKUSS-NCRI-24B02"]}],"id":[{"id":"https:\/\/ror.org\/02v51f717","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["82571132"],"award-info":[{"award-number":["82571132"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["82271009"],"award-info":[{"award-number":["82271009"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["82571132"],"award-info":[{"award-number":["82571132"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"award":["82271009"],"award-info":[{"award-number":["82271009"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004826","name":"Beijing Natural Science Foundation","doi-asserted-by":"publisher","award":["L222116"],"award-info":[{"award-number":["L222116"]}],"id":[{"id":"10.13039\/501100004826","id-type":"DOI","asserted-by":"publisher"}]},{"name":"China Oral Health Foundation","award":["A2021057"],"award-info":[{"award-number":["A2021057"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Bioengineering"],"abstract":"<jats:p>Repeatable acquisition of smiling and rest-related facial states is essential for longitudinal three-dimensional (3D) facial imaging, yet the effect of task instructions may depend on the state and measurement. This within-participant study compared conventional (CONV) and state-specific phoneme-guided (PHON) acquisition in 162 adults. For SMILE, CONV elicited a posed smile, whereas PHON used \/t\u0283\/ articulation followed by maintenance of the resulting perioral configuration; for the REST-related condition, CONV elicited relaxed rest, whereas PHON used sustained \/m\/ to define a closed-lip reference configuration rather than unconstrained physiological rest. Each protocol\u2013state condition was recorded twice. Within-session repeatability was characterized by absolute error between repeated acquisitions, technical error of measurement, intraclass correlation coefficient [ICC(2,1)], and Bland\u2013Altman agreement. State-specific protocol differences were assessed using paired Wilcoxon signed-rank tests with Holm correction. During SMILE, PHON reduced median error for the 3D Sn\u2013Gn distance (3.79 vs. 2.36 mm), interlabial distance (3.48 vs. 1.84 mm), and sagittal lip step (1.33 vs. 0.66 mm; adjusted p &lt; 0.001), but increased commissure-distance error (1.50 vs. 1.89 mm; adjusted p = 0.007). During the REST-related condition, no prespecified linear outcome differed after correction. Phoneme guidance changed, rather than uniformly improved, repeatability, and its effect depended on facial state and outcome.<\/jats:p>","DOI":"10.3390\/bioengineering13090994","type":"journal-article","created":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T13:26:03Z","timestamp":1787837163000},"page":"994","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Repeatability of Phoneme-Guided Versus Conventional Acquisition of Smiling and Rest-Related Facial States Using 3D Stereophotogrammetry: A Within-Participant Study"],"prefix":"10.3390","volume":"13","author":[{"given":"Weijing","family":"Dang","sequence":"first","affiliation":[{"name":"Department of Orthodontics, Peking University School and Hospital of Stomatology and National Center of Stomatology, Beijing 100081, China"},{"name":"National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China"},{"name":"Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China"},{"name":"Department of Nursing, Peking University School and Hospital of Stomatology and National Center of Stomatology, Beijing 100081, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2681-8092","authenticated-orcid":false,"given":"Liang","family":"Lyu","sequence":"additional","affiliation":[{"name":"Department of Orthodontics, Peking University School and Hospital of Stomatology and National Center of Stomatology, Beijing 100081, China"},{"name":"National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China"},{"name":"Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China"},{"name":"Eighth Clinical Division (Shijingshan Clinical Division), Peking University School and Hospital of 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China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3987-6723","authenticated-orcid":false,"given":"Jiajia","family":"Zheng","sequence":"additional","affiliation":[{"name":"National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China"},{"name":"Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China"},{"name":"Eighth Clinical Division (Shijingshan Clinical Division), Peking University School and Hospital of Stomatology and National Center of Stomatology, Beijing 100043, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7625-4600","authenticated-orcid":false,"given":"Dawei","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Orthodontics, Peking University School and Hospital of Stomatology and National Center of Stomatology, Beijing 100081, 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