The osteoclastic activity in apical distal region of molar mesial roots affects orthodontic tooth movement and root resorption in rats.

The utilization of optimal orthodontic force is crucial to prevent undesirable side effects and ensure efficient tooth movement during orthodontic treatment. However, the sensitivity of existing detection techniques is not sufficient, and the criteria for evaluating optimal force have not been yet established. Here, by employing 3D finite element analysis methodology, we found that the apical distal region (A-D region) of mesial roots is particularly sensitive to orthodontic force in rats. Tartrate-resistant acidic phosphatase (TRAP)-positive osteoclasts began accumulating in the A-D region under the force of 40 grams (g), leading to alveolar bone resorption and tooth movement. When the force reached 80 g, TRAP-positive osteoclasts started appearing on the root surface in the A-D region. Additionally, micro-computed tomography revealed a significant root resorption at 80 g. Notably, the A-D region was identified as a major contributor to whole root resorption. It was determined that 40 g is the minimum effective force for tooth movement with minimal side effects according to the analysis of tooth movement, inclination, and hyalinization. These findings suggest that the A-D region with its changes on the root surface is an important consideration and sensitive indicator when evaluating orthodontic forces for a rat model. Collectively, our investigations into this region would aid in offering valuable implications for preventing and minimizing root resorption during patients' orthodontic treatment.

Insight into the roles of melatonin in bone tissue and bone­related diseases (Review).

Bone­related diseases comprise a large group of common diseases, including fractures, osteoporosis and osteoarthritis (OA), which affect a large number of individuals, particularly the elderly. The progressive destruction and loss of alveolar bone caused by periodontitis is a specific type of bone loss, which has a high incidence and markedly reduces the quality of life of patients. With the existing methods of prevention and treatment, the incidence and mortality of bone­related diseases are still gradually increasing, creating a significant financial burden to societies worldwide. To prevent the occurrence of bone­related diseases, delay their progression or reverse the injuries they cause, new alternative or complementary treatments need to be developed. Melatonin exerts numerous physiological effects, including inducing anti­inflammatory and antioxidative functions, resetting circadian rhythms and promoting wound healing and tissue regeneration. Melatonin also participates in the health management of bone and cartilage. In the present review, the potential roles of melatonin in the pathogenesis and progression of bone injury, osteoporosis, OA and periodontitis are summarized. Furthermore, the high efficiency and diversity of the physiological regulatory effects of melatonin are highlighted and the potential benefits of the use of melatonin for the clinical prevention and treatment of bone­related diseases are discussed.

An injectable liposome for sustained release of icariin to the treatment of acute blunt muscle injury.

OBJECTIVES: Icariin, extracted from Epimedium, is a kind of flavonoid and possesses osteogenesis and antioxidant. This study aimed to evaluate the therapeutic effects of icariin liposome on acute blunt skeletal muscle injury in rats. METHODS: Icariin liposome was prepared by the thin-film dispersion method. After muscle injury, the corresponding treatment measures were given every day for two weeks. Recovery and mechanism of muscle injury were evaluated by QRT-PCR, HE, immunohistochemistry, malondialdehyde, superoxide dismutase and serological tests. KEY FINDINGS: The particle size, polydispersity index, zeta potential, encapsulation efficiency and drug loading of icariin liposomes were 171.37 ± 38.23 nm, 0.27 ± 0.01, -5.59 ± 1.36 mV, 78.15 ± 2.04% and 15.62%, respectively. The QRT-PCR showed that icariin liposome significantly promoted the expression of MHCIIB and vimentin. Through HE, immunohistochemistry, ELISA and serological tests, we found that icariin liposome effectively promoted desmin expression, reduced collagen I expression and inhibited the production of pro-inflammatory factors, including TNF-α and IL-6. Icariin liposome therapy significantly reduced the level of malondialdehyde and increased the activity of superoxide dismutase. CONCLUSIONS: Icariin liposome has excellent therapeutic effects on acute blunt muscle injury in rats by improving immunity, repairing cytoskeleton and cellular integrity, anti-inflammation, anti-fibrosis and antioxidant stress.