METHODS: This systematic review was performed conforming to preferred reporting items for systematic review and meta-analysis (PRISMA) model. Four different databases (PubMed, Science Direct, Scopus and Medline databases) as well as manual searching were adopted. Relevant studies from January 2000 till September 2021 were retrieved. Critical Appraisal Skills Programme (CASP) was used to assess the quality of the selected studies.
RESULTS: Out of 755 articles, only 14 which met the eligibility criteria were included. Six studies found that titanium dioxide nanotube (TNT) reduced oxidative stress and promoted osteoblastic activity through its effect on Wnt, mitogen-activated protein kinase (MAPK) and forkhead box protein O1 (FoxO1) signaling pathways. On the other hand, three studies confirmed that titanium dioxide nanoparticles (TiO2NPs) induce oxidative stress, reduce ostegenesis and impair antioxidant defense system as a significant negative correlation was found between decreased SIR3 protein level and increased superoxide (O2 •-). Moreover, five studies proved that titanium implant alloy enhances the generation of ROS and induces cytotoxicity of osteoblast cells via its effect on NOX pathway.
CONCLUSION: TiO2NPs stimulate a wide array of oxidative stress related pathways. Scientific evidence are in favor to support the use of TiO2 nanotube-coated titanium implants to reduce oxidative stress and promote osteogenesis in bone remodeling. To validate the cellular and molecular cross talk in bone remodeling of the present review, well-controlled clinical trials with a large sample size are required.
METHODS: Eighty (80) male, 6-week-old Sprague Dawley rats were grouped in to four groups, the first group was irradiated with (940 nm) diode laser, second group with LIPUS, and third group with combination of both LLLT and LIPUS. A forth group used was a control group in an incomplete block split-mouth design. The LLLT and LIPUS were used to treat the area around the moving tooth once a day on days 0-7, then the experiment was ended in each experimental endpoint (1, 3, 7, 14, and 21 days). For amount of tooth movement, models were imaged and analyzed. Histological examination was performed after staining with (hematoxylin and eosin) and (alizarin red and Alcian Blue) stain. One step reverse transcription-polymerase chain reaction RT-PCR was also performed to elucidate the gene expression of RANK, RANKL, OPG, and RUNX-2.
RESULTS: The amount of tooth movement, the histological bone remodeling, and the RT-PCR were significantly greater in the treatment groups than that in the control group. Among the treatment groups, the combination group was the highest and the LIPUS group was the lowest.
CONCLUSION: These findings suggest that LLLT and LIPUS can enhance the velocity of tooth movement and improve the quality of bone remodeling during orthodontic tooth movement.
OBJECTIVE: This review aimed to provide an overview of the relationship between mevalonate pathway and bone metabolism, as well as agents which act through this pathway to achieve their therapeutic potential.
DISCUSSION: Mevalonate pathway produces farnesyl pyrophosphate and geranylgeranyl pyrophosphate essential in protein prenylation. An increase in protein prenylation favours bone resorption over bone formation. Non-nitrogen containing bisphosphonates inhibit farnesyl diphosphate synthase which produces farnesyl pyrophosphate. They are used as the first line therapy for osteoporosis. Statins, a well-known class of cholesterol-lowering agents, inhibit 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, the rate-determining enzyme in the mevalonate pathway. It was shown to increase bone mineral density and prevent fracture in humans. Tocotrienol is a group of vitamin E commonly found in palm oil, rice bran and annatto bean. It causes degradation of HMG-CoA reductase. Many studies demonstrated that tocotrienol prevented bone loss in animal studies but its efficacy has not been tested in humans.
CONCLUSION: Mevalonate pathway can be exploited to develop effective antiosteoporosis agents.
Objectives: The current study aimed at determining the effects of degarelix on bone turnover, bone densitometry, and bone mechanical strength in male rats.
Methods: Eighteen male Sprague-Dawley rats were randomly divided into sham (SHAM), orchidectomized (ORX), and degarelix-induced (DGX) groups. Chemical castration was performed by subcutaneous degarelix injection (2 mg/kg) at the scapular region. The rats were scanned for baseline bone mineral area (BMA), bone mineral content (BMC), and bone mineral density (BMD) using dual-energy x-ray absorptiometry (DXA). Following six weeks of experimental period, BMA, BMC, and BMD were measured again with DXA and blood was collected for testosterone and bone biomarkers (osteocalcin and C-terminal of type I collagen crosslink (CTX-1)) measurements. The rats were euthanized and femora were dissected for bone biomechanical strength analysis.
Results: Bilateral orchidectomy and degarelix administration significantly lowered serum testosterone level, decreased whole body BMC, femoral BMA, femoral BMC, and femoral BMD (P < 0.05) compared with the SHAM group. However, no significant changes were observed in bone biochemical markers and bone mechanical strength in all experimental groups.
Conclusions: In conclusion, degarelix administration had comparable effects on bone as bilateral orchidectomy. Administration of degarelix provides an alternative method of inducing testosterone deficient-osteopenia in male rats without need for removing the testes.