Biological effect of bone marrow mesenchymal stem cell- derived extracellular vesicles on the structure of alveolar bone in rats with glucocorticoid-induced osteoporosis.

BACKGROUND: Glucocorticoids are used for the treatment of autoimmune disorders; however, they can elicit several side effects such as osteoporosis. Several approaches can be made to treat glucocorticoid-induced osteoporosis, including the use of stem cells. However, the therapeutic effect of mesenchymal stem cells depends on its released factors, including extracellular vesicles. Extracellular vesicles have been recognized as important mediators of intercellular communication as they participate in many physiological processes. The present study was designed to investigate the effect of bone marrow mesenchymal stem cells derived extracellular vesicles on the structure of alveolar bone in rats with glucocorticoid-induced osteoporosis. METHODS: Thirty adult albino male rats were divided into 3 groups: control group (CG), glucocorticoid-induced osteoporosis (GOG) and extracellular vesicles treated group (ExTG). Rats in the GOG and ExTG groups were injected with methylprednisolone acetate (40 mg/kg) intramuscularly in the quadriceps muscle 3 times per week for three weeks in the early morning. Afterwards, the rats in GOG group received a single vehicle injection (PBS) while each rat in the ExTG group received a single injection of extracellular vesicles (400 µg/kg suspended in 0.2 ml PBS) in the tail vein. Rats were euthanized 1 month after injection. Mandibles were dissected and the molar segments were prepared for histological preparation, scanning electron microscopy (SEM), and energy dispersive x-ray (EDX). RESULTS: Histology and scanning electron microscopyof bone tissue showed alveolar bone loss and bone resorption in the GOG group. while in the ExTG group, alveolar bone demostrated normal bone architecture. EDX showed that calcium percentage in GOG group was lower than ExTG group,which showed no statistically significant difference from the control group. CONCLUSIONS: Extracellular vesicles may be a promising treatment modality in the treatment of bone diseases and in bone regeneration. However, further research is needed before stating that extracellular vesicles s can be used to treat bone disorders especially when translating to humans.

A comparative histological study of the effect of TheraCal LC and biodentine on direct pulp capping in rabbits: an experimental study.

OBJECTIVES: This study histologically compared the effect of TheraCal LC and biodentine on direct pulp capping using a rabbit model. MATERIALS AND METHODS: A direct pulp capping procedure was performed on 40 mandibular central incisors of 20 healthy, male New Zealand white rabbits. TheraCal LC and biodentine were applied to exposed pulp and 10 randomly selected rabbits were euthanized after the first and second week. Incisors were extracted and prepared for histological processing and examination to check the dentine bridge thickness, continuity, and extent of pulp inflammation. A blinded data analysis was performed, and groups were compared using a Wilcoxon signed-rank test while changes across time within each group were assessed using the Mann-Whitney U test. RESULTS: When comparing the dentine bridge thickness, biodentine showed a significantly thicker dentine bridge in the first and second week (mean 28.16 µm, 33.66 µm), while TheraCal LC showed a dentine bridge in the second week only (mean 15.93 µm). Regarding dentine bridge continuity, biodentine showed a significantly better dentine bridge in the first week. Additionally, there was no difference in the second week. Furthermore, there was no statistically significant difference between each of the materials regarding the extent of inflammation. CONCLUSIONS: Biodentine in vivo showed better results concerning thickness and continuity of the dentine bridge after direct pulp capping in rabbit incisors. Both biodentine and TheraCal LC had a similar inflammatory effect on the pulp. CLINICAL RELEVANCE: Biodentine is more successful as a direct pulp capping material compared to TheraCal LC.

Evaluation of simvastatin grafting around immediate dental implants in dogs.

INTRODUCTION: Simvastatin (Zocor; MSD), a cholesterol-lowering drug, is used systemically in treatment of osteoporosis due to its bone-forming potential. The present study was conducted to evaluate the regenerative potential of an optimized simvastatin formulation as a grafting material around immediate dental implants in experimental animals. MATERIALS AND METHODS: The drug was formulated as granules in cellulosic polymeric matrix. Surgical extractions of left and right mandibular third premolars were performed in 10 dogs. The left side of the mandible was the study group, where Microdent (Implant Microdent System S.L-Comapedrosa, Barcelona, Spain) implants were immediately seated and simvastatin granules were packed. The right side constituted the control group where only implants were placed. Five dogs were killed at 1 month and 5 at 3 months. The implants were removed and specimens were processed and stained with hematoxylin and eosin and trichrome stains. RESULTS: Healing occurred in both groups, with better findings in simvastatin-filled defects, as evidenced by bone regeneration, with neovascularization. CONCLUSIONS: Simvastatin granules allowed for osteogenesis around immediate implants, resulting in their osseointegration.