{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T03:22:25Z","timestamp":1785554545385,"version":"3.56.0"},"reference-count":42,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2019,4,2]],"date-time":"2019-04-02T00:00:00Z","timestamp":1554163200000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Projects of Development and Application of Suitable Health Technology of Shanghai Hospital Development Center","award":["SHDC12014226"],"award-info":[{"award-number":["SHDC12014226"]}]},{"name":"Strengthening Public Health System in Shanghai","award":["GWIV-12"],"award-info":[{"award-number":["GWIV-12"]}]},{"name":"Projects of Shanghai Municipal Commission of Health and Family Planning","award":["2016ZB0102-01"],"award-info":[{"award-number":["2016ZB0102-01"]}]},{"name":"Project of Characteristic Medical Specialty in Minhang Shanghai","award":["2017MWTZ20"],"award-info":[{"award-number":["2017MWTZ20"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Epidemiological data on malocclusion among Chinese children are scant. The aim of this study was to provide detailed information on the prevalence of malocclusion in early mixed dentition children in Shanghai, China.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A cross-sectional survey was conducted from September 2016 to April 2017, and 2,810 children aged 7- to 9- years were selected from 10 primary schools by cluster random sampling. Several occlusal parameters, including Angle molar relationship, overjet, overbite, open bite, anterior and posterior crossbite, midline displacement, scissors bite, and teeth crowding and spacing, were clinically registered by five calibrated orthodontic dentists.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We found that 79.4% children presented one or more occlusal anomalies. Angle Class I, Class II and Class III molar relationship were recorded in 42.3%, 50.9% and 5.9% of the sample, respectively. The proportion of Class III increased from 5.0% at age 7 to 7.8% at age 9. In the sagittal plane, increased overjet &gt;3 mm was observed in 40.8% subjects, while the prevalence of severe overjet (&gt;8 mm), anterior edge-to-edge (zero overjet) and anterior crossbite were 5.2%, 8.1% and 10.5%, respectively. Vertically, deep overbite &gt;2\/3 overlap was found in 6.2% of the children and open bite in 4.3%. Boys exhibited a higher rate of overbite than girls. For the transversal occlusal anomalies, 36.1% of the children had a midline displacement, which was followed by posterior crossbite (2.6%) and scissors bite (1.0%). Teeth space discrepancies were also common anomalies and anterior crowding (&gt;2 mm) affecting 28.4% of the children, while anterior spacing (&gt;4 mm) affecting 9.5%. Girls showed a higher prevalence of anterior crowding and a lower frequency of teeth spacing than boys.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Our study demonstrated that malocclusion is prevalent among children in the early mixed dentition, and more health resources should be warranted to meet the challenge of prevention or early intervention of malocclusion.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.7717\/peerj.6630","type":"journal-article","created":{"date-parts":[[2019,4,2]],"date-time":"2019-04-02T05:09:47Z","timestamp":1554181787000},"page":"e6630","source":"Crossref","is-referenced-by-count":27,"title":["Prevalence of malocclusion and occlusal traits in the early mixed dentition in Shanghai, China"],"prefix":"10.7717","volume":"7","author":[{"given":"Xin","family":"Yu","sequence":"first","affiliation":[{"name":"Department of Pediatric Dentistry, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"},{"name":"Oral Biomedical Engineering Laboratory, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hao","family":"Zhang","sequence":"additional","affiliation":[{"name":"Oral Biomedical Engineering Laboratory, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"},{"name":"Department of Preventive Dentistry, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Liangyan","family":"Sun","sequence":"additional","affiliation":[{"name":"Oral Biomedical Engineering Laboratory, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"},{"name":"Department of Orthodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jie","family":"Pan","sequence":"additional","affiliation":[{"name":"Oral Biomedical Engineering Laboratory, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"},{"name":"Department of Orthodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuehua","family":"Liu","sequence":"additional","affiliation":[{"name":"Oral Biomedical Engineering Laboratory, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"},{"name":"Department of Orthodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Chen","sequence":"additional","affiliation":[{"name":"Oral Biomedical Engineering Laboratory, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"},{"name":"Department of Orthodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, China"},{"name":"Minhang Preventive Dental Clinic, Shanghai, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4443","published-online":{"date-parts":[[2019,4,2]]},"reference":[{"key":"10.7717\/peerj.6630\/ref-1","doi-asserted-by":"publisher","first-page":"59","DOI":"10.1186\/s40510-014-0059-4","article-title":"Association between breastfeeding duration, non-nutritive sucking habits and dental arch dimensions in deciduous dentition: a cross-sectional study","volume":"15","author":"Agarwal","year":"2014","journal-title":"Progress in Orthodontics"},{"issue":"4","key":"10.7717\/peerj.6630\/ref-2","doi-asserted-by":"publisher","first-page":"123","DOI":"10.1590\/S2176-94512011000400019","article-title":"Prevalence of malocclusion in children aged 7\u201312 years","volume":"16","author":"Almeida","year":"2011","journal-title":"Dental Press Journal of Orthodontics"},{"key":"10.7717\/peerj.6630\/ref-3","doi-asserted-by":"publisher","first-page":"5048","DOI":"10.1038\/s41598-017-05393-y","article-title":"Association between duration of breastfeeding and malocclusions in primary and mixed dentition: a systematic review and meta-analysis","volume":"7","author":"Boronat-Catala","year":"2017","journal-title":"Scientific Reports"},{"issue":"5","key":"10.7717\/peerj.6630\/ref-4","doi-asserted-by":"publisher","first-page":"477","DOI":"10.1093\/ejo\/cjp031","article-title":"Malocclusion and occlusal traits in an urban Iranian population. 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