Periostin is an extracellular matrix protein highly expressed in collagen-rich tissues subjected to continuous mechanical stress. Functionally, periostin is involved in tissue remodeling and its altered function is associated to numerous pathological processes. In orthodontics, periostin plays key roles in the maintenance of dental tissues and it is mainly expressed in those areas where tension or pressing forces are taking place. In this regard, high expression of periostin is essential to promote migration and proliferation of periodontal ligament fibroblasts. However little is known about the participation of periostin in migration and adhesion processes of bone remodeling cells. In this work we employ the mouse pre-osteoblastic MC3T3-E1 and the macrophage-like RAW 264.7 cell lines to overexpress periostin and perform different cell-based assays to study changes in cell behavior. Our data indicate that periostin overexpression not only increases adhesion capacity of MC3T3-E1 cells to different matrix proteins but also hampers their migratory capacity. Changes on RNA expression profile of MC3T3-E1 cells upon periostin overexpression have been also analyzed, highlighting the alteration of genes implicated in processes such as cell migration, adhesion or bone metabolism but not in bone differentiation. Overall, our work provides new evidence on the impact of periostin in osteoblasts physiology.

The purpose of this prospective case control study is to describe in growing patients with mandibular hypoplasia, treatment outcomes following functional therapy in terms of volumetric changes in nasopharynx and oropharynx, that is, upper and lower pharynx. We recruited 60 study participants aged between 8 and 12 years having mandibular Class II malocclusion and a reduced upper airway (UA) size, as determined by McNamara cephalometric analyses. Forty patients received Twin Block treatment, whereas the remaining 20 patients did not receive treatment, thus constituting the control group. The control group included patients who did not start treatment after their first visit but returned for a consultation one or 2 years later. All patients underwent an initial teleradiography examination of the skull and a final teleradiography examination to measure changes using McNamara cephalometric analysis of the UA. Pretreatment and posttreatment changes were assessed using Student's t test for independent samples with a significance level of 0.05. Both anatomical structures analyzed—the upper pharynx (nasopharynx) and lower pharynx (oropharynx)—showed significant increases after treatment regardless of whether the patients were boys or girls. The controls showed a decrease in UA size on average after approximately 2 years of growth. A clear relationship exists between the mandibular advancement achieved with TB treatment and an increased UA size. Therefore, the appliance is considered suitable for improving the respiratory quality of growing patients with a decreased UA size.