Abstract: Objective To measure the thickness of palatal mucosa in a Chinese population, analyze the change rules and relevant factors, and observe the thickness,histologic characteristics, and distribution rules in different layers. Methods Measurements of the palatal mucosa were obtained in 45 measure points, from 36 adults who were divided into three groups according to gingiva biotypes by bone sounding method. And residual soft tissues were collected from the palatal graft of periodontal augmentation procedures and stained using Harris hematoxylin. The platal mucosa with entire layers were selected as samples, and immunohistochemistry technology was applied to observe the histologic characteristics and distribution rules of connective tissues under the microscope.Biopsies with all layers of palatal mucosa were chosen for further histologic analysis. Results The overall mean thickness of palatal masticatory mucosa was(3.52±1.02)mm,(3.26±0.81)mm in canine region,(3.57±1.05)mm in the first premolar region,(3.72±1.04)mm in the second premolar region, (3.33±0.96)mm in the first molar region,(3.73±1.11)mm in the second molar region. No difference was observed between genders and ages. An association was observed between the thickness and biotypes. HE staining showed that the layer of connective tissues of palatal mucosa had dense collagenous fiber, the thickness of lamina propria increased from canine region to the first premolar region and then decreased toward the posterior palatal area. The submucosa layers were obvious in the second premolar region, loose connective tissues were seen in the first molar region, while the posterior palatal area contained abundant adipose tissue, vessels and glands. Conclusions In the Chines population, the thickness of palatal mucosa decreases from the canine to the posterior palatal area and increases in the second molar area. And the thickness of palatal mucosa increases from gingival margin to the midpalatal suture in the canine, the first premolar and the second molar areas. The lamina propria of palatal mucosa contains dense connective tissues while the submucosa layer, which tends to occur from the second premolar area, contains abundant adipose tissue,vessels and glands.

Key words: thickness of palatal mucosa, Gingival biotype, HE staining