{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T15:25:08Z","timestamp":1787757908597,"version":"build-2784847793"},"reference-count":20,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"5","content-domain":{"domain":["lww.com","ovid.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2022,5]]},"abstract":"<jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>Anchorage control is one of the components in the treatment of extraction cases. However, what determines more or less anchorage loss is still an unanswered question. Aim: The purpose of this study was to investigate the most important factors contributing to the anchorage loss of maxillary first molars in premolar extraction cases.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Materials and Methods:<\/jats:title>\n                    <jats:p>The study included 726 upper premolar extraction cases, including 214 male patients and 512 female patients, and the mean age was 14.4 \u00b1 4.5 years old (range: 9-45). Factors including physiological characteristics, treatment mechanics, and cephalometric variables were collected and their influences on the angulation changes of maxillary first molars were analyzed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>\n                      The mean angulation change of maxillary first molar after treatment was 2.81\u00b0(mesial tipping). The change of UM\/PP showed a statistically significant difference in different sex (male 3.84\u00b0 \u00b1 5.26\u00b0 vs female 2.38\u00b0 \u00b1 5.10\u00b0), age (adult -0.05\u00b0 \u00b1 4.73\u00b0 vs teenager 3.46\u00b0 \u00b1 5.07\u00b0), and molar relationship (Class II 3.28\u00b0 \u00b1 5.15\u00b0 vs Class I 2.36\u00b0 \u00b1 5.19\u00b0). There are six variables accounted in the regression analysis (\n                      <jats:italic toggle=\"yes\">R<\/jats:italic>\n                      = 0.608,\n                      <jats:italic toggle=\"yes\">R<\/jats:italic>\n                      <jats:sup>2<\/jats:sup>\n                      = 37.0%). Among them, the pre-treatment molar tipping (Standardized Coefficients: -0.65) and the pre-treatment incisor\/molar height ratio (Standardized Coefficients: -0.27) were the most important factors influencing anchorage loss during treatment.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion:<\/jats:title>\n                    <jats:p>Compared with treatment-related factors, the patient's physiological characteristics play a more important role in anchorage loss. The pre-treatment angulation of the maxillary first molar is the most influential factor in changes to maxillary molar angulation, which are often predisposing anchorage loss.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.4103\/njcp.njcp_1791_21","type":"journal-article","created":{"date-parts":[[2022,5,20]],"date-time":"2022-05-20T00:26:30Z","timestamp":1653006390000},"page":"664-669","update-policy":"https:\/\/doi.org\/10.1097\/lww.0000000000001000","source":"Crossref","is-referenced-by-count":2,"title":["A Retrospective Study of Factors Contributing to Anchorage Loss in Upper Premolar Extraction 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