Effect of low-level laser therapy after rapid maxillary expansion on proliferation and differentiation of osteoblastic cells.

The aim of this study was to investigate the osteoblastic activity of cells derived from the midpalatal suture upon treatment with low-level laser therapy (LLLT) after rapid maxillary expansion (RME). A total of 30 rats were divided into two groups: experimental I (15 rats with RME without LLLT) and experimental II (15 rats with RME + LLLT). The rats were euthanized at 24 h, 48 h, and 7 days after RME, when the osteoblastic cells derived from the rats' midpalatal suture were explanted. These cells were cultured for periods up to 17 days, and then in vitro osteogenesis parameters and gene expression markers were evaluated. The cellular doubling time in the proliferative stage (3-7 days) was decreased in cultured cells harvested from the midpalatal suture at 24 and 48 h after RME + LLLT, as indicated by the increased growth of the cells in a culture. Alkaline phosphatase activity at days 7 and 14 of the culture was increased by LLLT in cells explanted from the midpalatal suture at 24 and 48 h and 7 days after RME. The mineralization at day 17 was increased by LLLT after RME in all periods. Results from the real-time PCR demonstrated that cells harvested from the LLLT after RME group showed higher levels of ALP, Runx2, osteocalcin, type I collagen, and bone sialoprotein mRNA than control cells. More pronounced effects on ALP activity, mineralization, and gene expression of bone markers were observed at 48 h after RME and LLLT. These results indicate that the LLLT applied after RME is able to increase the proliferation and the expression of an osteoblastic phenotype in cells derived from the midpalatal suture.

Effect of surgically assisted rapid maxillary expansion on masticatory muscle activity: A pilot study.

BACKGROUND: The aim of the present study was to analyze the electromyographic (EMG) activity of masseter and temporal muscles of adult patients submitted to surgically assisted rapid maxillary expansion (SARME) before and after the surgery. MATERIALS AND METHODS: The sample consisted of 19 adults, with ages ranging from 20 to 47 years (mean 25.4 years), with bilateral posterior cross bite requiring SARME treatment. The electromyographic activity of masseter and temporal muscles was analyzed before treatment (T1) and after the surgical procedure (T2). The mean interval between the two electromyographic analyses was 15 days. RESULTS: The muscular active was electromyographically analyzed during the clinical situation of habitual gum chewing (10 sec), dental clenching (4 sec), mouth opening and closing (10 sec), rest (10 sec), protrusion (10 sec), and right and left laterality (10 sec). The measured differences between T1 and T2 data were evaluated using the paired t-test (SPSS 17.0 for Windows). The electromyographic analysis showed that the activity of the masseter and temporal muscles decreased significantly after the SARME in all the clinical situations after the surgery. CONCLUSION: According to the results of the present study, individuals after SARME surgery presented patterns of electromyographic contraction similar to those developed by dentate individuals during the movements of mandibular excursion.