The application of a new clear removable appliance with an occlusal splint in early anterior crossbite.

BACKGROUND: The effectiveness of anterior crossbite treatment in preschool-aged children depends on the treatment design and patient compliance. Common early treatment appliances with steel wires and acrylic resin can bring about numerous problems, such as toothache, sore gums and mucous membrane injury. The aim of this study was to propose a new clear removable appliance to provide preschool-age children with an improved experience of early occlusal interference treatment. METHODS: Appliances were designed with the help of 3-dimensional (3D) digital reconstruction oral models and fabricated using 3D printing technology and the pressed film method. Then, the mechanical properties of the original dental coping sheet and thermoformed aligners were assessed in a simulated intraoral environment. Preschool-age participants who displayed anterior crossbite were recruited in this study. Records (photographs and impressions) were taken before the treatment (T1), during the treatment (T2) and at the end of the treatment (T3). The effects of treatment were evaluated by clinical examination and questionnaires. RESULTS: Normal degrees of overbite and overjet in the primary dentition were achieved using this new appliance. Dental and soft tissue relationships were improved. Questionnaires showed that the safety evaluation, degree of comfort and convenience grades of the appliance were all relatively high. CONCLUSION: This explorative study demonstrates that our new clear removable appliance is able to correct early-stage anterior crossbite in a safe, comfortable, convenient and efficient way. Thus, it is a promising method to correct a certain type of malocclusion, and its clinical use should be promoted in the future.

The Dual Effects of Reactive Oxygen Species on the Mandibular Alveolar Bone Formation in SOD1 Knockout Mice: Promotion or Inhibition.

The status of reactive oxygen species (ROS) correlates closely with the normal development of the oral and maxillofacial tissues. Oxidative stress caused by ROS accumulation not only affects the development of enamel and dentin but also causes pathological changes in periodontal tissues (periodontal ligament and alveolar bone) that surround the root of the tooth. Although previous studies have shown that ROS accumulation plays a pathologic role in some oral and maxillofacial tissues, the effects of ROS on alveolar bone development remain unclear. In this study, we focused on mandibular alveolar bone development of mice deficient in superoxide dismutase1 (SOD1). Analyses were performed using microcomputerized tomography (micro-CT), TRAP staining, immunohistochemical (IHC) staining, and enzyme-linked immunosorbent assay (ELISA). We found for the first time that slightly higher ROS in mandibular alveolar bone of SOD1(-/-) mice at early ages (2-4 months) caused a distinct enlargement in bone size and increased bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and expression of alkaline phosphatase (ALP), Runt-related transcription factor 2 (Runx2), and osteopontin (OPN). With ROS accumulation to oxidative stress level, increased trabecular bone separation (Tb.Sp) and decreased expression of ALP, Runx2, and OPN were found in SOD1(-/-) mice at 6 months. Additionally, dosing with N-acetylcysteine (NAC) effectively mitigated bone loss and normalized expression of ALP, Runx2, and OPN. These results indicate that redox imbalance caused by SOD1 deficiency has dual effects (promotion or inhibition) on mandibular alveolar bone development, which is closely related to the concentration of ROS and the stage of growth. We present a valuable model here for investigating the effects of ROS on mandibular alveolar bone formation and highlight important roles of ROS in regulating tissue development and pathological states, illustrating the complexity of the redox signal.

Effect of canonical NF-κB signaling pathway on the differentiation of rat dental epithelial stem cells.

BACKGROUND: Nuclear factor-κB (NF-κB), an important transcription factor, participates in many physiological and pathological processes such as growth, differentiation, organogenesis, apoptosis, inflammation, and immune response, including tooth development. However, it is still unknown whether NF-κB participates in the regulation of dental epithelial stem cells (DESCs) in postnatal rat incisors. Here, we investigated the specific differentiation regulatory mechanisms of the canonical NF-κB signaling pathway in DESCs and provided the mechanism of cross-talk involved in DESC differentiation. METHODS: After adding the activator or inhibitor of the NF-κB signaling pathway, Western blot and quantitative real-time PCR were used to analyze the expressions of amelogenesis-related genes and proteins and canonical transforming growth factor-ß (TGF-ß) signaling. In addition, we used amelogenesis induction in vitro by adding the activator or inhibitor of the NF-κB signaling pathway to the amelogenesis-induction medium, respectively. Recombinant TGF-ß was used to activate the TGF-ß pathway, and SMAD7 siRNA was used to downregulate the expression of SMAD7 in DESCs. RESULTS: We found that the expression of amelogenesis-related genes and proteins as well as TGF-ß signaling were downregulated, while SMAD7 expression was increased in NF-κB-activated DESCs. In addition, NF-κB-inhibited DESCs exhibited opposite results compared with NF-κB-activated DESCs. Furthermore, the canonical NF-κB signaling pathway suppressed the canonical TGF-ß-SMAD signaling by inducing SMAD7 expression involved in the regulation of DESC differentiation. CONCLUSIONS: These results indicate that the canonical NF-κB signaling pathway participated in the regulation of DESC differentiation, which was through upregulating SMAD7 expression and further suppressing the canonical TGF-ß-SMAD signaling pathway.