Cytomorphometric Evaluation of Oral Mucosa among Children undergoing Acrylic Removable Orthodontic Appliances: An in vivo Study

The use of acrylic appliances in the oral cavity warrants biocompatibility evaluation. This study aimed to carry out an in vivo investigation of the cytomorphometric changes of oral mucosa among children undergoing acrylic removable orthodontic appliances. In this observational clinical study, acrylic removable orthodontic appliances were delivered to 25 orthodontic patients and followed for 3 months. Mucosal samples were collected by gentle brushing of the internal part of the right and left buccal mucosa before appliance delivery (T0) and 1 week (T1), 1 month (T2), and 3 months (T3) following appliance delivery. The cells were immediately prepared for cytomorphometric analysis. There was no significant difference in the nuclear area between different time intervals. Cytoplasmic area in the right side of the buccal mucosa was significantly larger 1 month following appliance delivery (T2), compared to T0 (P=0.018) and T1 (P=0.036). On the right side, nuclear to cytoplasmic ratio values in T2 were significantly less than those in T0 (P=0.008) and T1 (P=0.002). Moreover, T3 values were lower than T1 values (P=0.048). The results of micro-nucleation and apoptosis analysis did not show statistically significant differences between different time intervals. Orthodontic acrylic appliances may not be a factor in inducing morphologic changes of oral mucosa cells; nevertheless, they may promote some transient cytometric effects. It seems that they do not cause any significant damages to the oral mucosa in long term.