To investigate whether there are differences in attachment gingival width (AGW) and clinical crown width/length ratio (CCW/CCL) of maxillary anterior teeth in a population of adult college students with anomalous passive eruption (APE) as compared to the normal population, and its association with related factors.

Between October and November 2022, we included 60 university students (28 males and 32 females) from Guangdong Province, whose ages ranged from 20 to 23 years old and underwent the following clinical data collection: AGW, gingival sulcus depth, clinical crown length (CCL), clinical crown width (CCW), gingival biotype, anterior occlusal relationship, upper lip height, and gender, height and weight. Oral respiratory history was obtained by using a questionnaire. Independent samples t-test, chi-square test and Mann-Whitney test were used for comparison between groups.

Seven males and 12 females out of 60 participants were diagnosed with APE. There were no statistically significant differences between patients with APE and the normal population in terms of oral respiratory history, gender, height, body mass index, upper lip height, anterior occlusal relationship and gingival biotype. APE was associated with an increase in AGW (P<0.05) and CCW/CCL (P<0.05). Among individuals with APE, lateral incisors had the highest prevalence (UR2: 94.7%, UL2: 78.9%), followed by cuspids (UR3: 42.1%, UL3: 42.1%), while central incisors had the lowest prevalence (UR1: 26.3%, UL1: 21.1%). In addition, among the right and left homonymous teeth, the CCL was greater in the right lateral incisors and cuspids than in the left lateral incisors and cuspids.

APE was associated with increased AGW and CCW/CCL. AGW and CCW/CCL can be used as reference indicators in the diagnosis of patients with suspected APE. In addition, the clinical features favoring lateral incisors and cuspids should be taken into consideration in clinical diagnosis and treatment of APE.