Hızlı üst çene genişletmesi uygulanan sıçanlarda farklı molekül ağırlıklarında hyaluronik asit preparatlarının kemik oluşumuna etkisinin histomorfometrik ve biyokimyasal olarak incelenmesi

The aim of this study was to evaluate the histomorphometric and biochemical effect of locally applied hyaluronic acid solution with different molecular weight on bone formation in the long and short term, injection applied into the midpalatal suture area in rats. This study was conducted on 48 male Sprague-Dawley rats with an average weight of 360,31±52,2 gr.The rats were divided into 3 groups; control (saline application only), LMWHA (low molecular weight hyaluronic acid), HMWHA (high molecular weight hyaluronic acid). Two different time intervals were examined for each group: 10th and 20th days groups after injection. In all groups, rats maxillas were expanded with stainless steel helix expansion spring. On the 5th day, helix spring was removed and replaced with retention wire. Simultaneously with retention procedure, 0,05 ml (50 μl) high and low molecular weight hyraluronic acid and saline solution was locally injected to midpalatal suture area. After the 10th and 20th day of injection rats were sacrified. Blood samples were collected and upper jaw samples were dissected and prepared for histological examination. For histomorphometric examination, dissected and trimmed blocks were longitudinally sectioned serially, 10 μm thickness intervals were applied parallel to long axis of the incisors. The sections were stained with Masson's trichrome were analyzed by photo microscope. Bone and connective tissue volume measurements were made. Blood serum plasma were obtained from blood samples by centrifugation, and the amount of HA (hyaluronic acid) in the serum was determined using HA measurements kits. Bone formation amount showed a significant difference between the control and experimental groups on the 10th and 20th days (p<0,05). Bone area (m2), and bone perimeter (m) and blood serum HA values of each group were examined. As a result of histomorphometric examination, high molecular weight hyaluronic acid solution significantly increased bone formation in the long and short term compared to low molecular weight hyaluronic acid and control groups (p<0,05). Also low molecular weight HA groups showed significantly high bone formation values according to control groups (p<0,05). When blood serum HA levels were examined, LMWHA groups showed high values but there was no significant difference between the blood serum HA values of experimental and control groups (p> 0,05). In this study, it was aimed to accelerate bone formation, shorten orthodontic retention time and decrease relapse with a minimally invasive approach, and also aimed to elucidate the systemic spread characteristics of locally applied HA solutions by analyzing to blood serum HA data biochemically. Bone formation is increased by local application of high and low molecular weight hyaluronic acid. This study shows that, local injection of HMWHA and LMWHA solution in midpalatal suture area after rapid maxillary expansion stimulated new bone formation that may shorten retention time and may reduce the risk of relapse. Key words: Rapid maxillary expansion, hyaluronic acid, accelerated bone formation, orthodontic relapse, blood plasma, rats