Abstract: Objective: To explore the evaluation value of high frequency ultrasound on gingival thickness (GT) and morphology of anterior teeth. Methods: A total of 138 teeth were selected from 35 volunteers. GT (GT0, GT2) of 2 mm below the gingival margin of anterior teeth were measured by gingival puncture and high frequency ultrasound. The gingival morphology of anterior teeth was analyzed by ultrasonic measurement, including the height of supraosseous gingiva (SOG) on the labial central crest, the distance from cemento-enamel junction (CEJ) to the alveolar crest (BC), and the width of keratinized gingiva. Results: There was no statistical significant difference between GT0 measured by gingival puncture and GT2 measured by high frequency ultrasound in 35 subjects with right upper central incisor, left upper central incisor, left lower central incisor, and right lower central incisor (P>0.05). The receiver operating characteristic (ROC) Curve was drawn, and the results showed that the area under curve (AUC) of GT2 for diagnosing gingival biotypes measured by high-frequency ultrasound was 0.821 (95%CI: 0.752-0.891), the specificity and sensitivity were 71.8% and 78.3%, respectively, indicating high diagnostic value. According to the analysis of intra class correlation coefficient (ICC), the thickness of 2 mm below the gingival margin measured by high-frequency ultrasound at each tooth position was consistent with the results obtained by gingival puncture method (ICC>0.6). There was no statistical significant difference in the results of GT2 and gingival morphology indexes SOG and CEJ-BC measured by high frequency ultrasound in different gender subjects (P>0.05). According to Pearson correlation analysis, GT2 at each tooth position was positively correlated with SOG (r=0.719,r=0.426,r=0.489,r=0.597,P<0.05), and also positively correlated with the keratinized gingival width (r=0.512,r=0.498,r=0.647,r=0.562,P＜0.05), while there was a negative correlation with CEJ-BC (r=-0.485,r=-0.452,r=-0.382,r=-0.402,P＜0.05). Conclusion: The width of keratinized gingiva in the upper front teeth is wider than that in the lower front teeth. High frequency ultrasound measurement of GT in the front teeth is consistent with gingival puncture method, and can be used as an effective method for clinical measurement of GT and determination of gingival biotype. The measured GT is correlated with gingival morphology, SOG height, CEJ-BC, and keratinized gingiva width.

Key words: gingival thickness, gingival morphology, high frequency ultrasound, enamel cementum boundary