Investigation of the Effects of Thymoquinone and Dental Pulp-Derived Mesenchymal Stem Cells on Tibial Bone Defect Models.

The thymoquinone obtained from Nigella sativa increases osteoblastic activity and significantly reduces the number of osteoclasts, thereby accelerating bone healing. In addition, mesenchymal stem cells isolated from various tissues are considered a potential cell source for bone regenerative therapies. The aim of this study is to investigate the effectiveness of thymoquinone, a current and novel agent, in combination with mesenchymal stem cells derived from the dental pulp in promoting bone healing. In the study, 28 male Sprague Dawley rats were used. The rats were divided into 4 groups, each consisting of 7 rats: the control group (group 1) (n=7), thymoquinone group (group 2) (n=7), stem cell group (group 3) (n=7), stem cell+thymoquinone group (group 4) (n=7). A bone defect of 4 mm in diameter and 5 mm in length was created in the left tibial bones of all rats with a trephine bur. In group 1, no procedure was applied to the defect area. Group 2 was applied thymoquinone (10 mg/kg) with oral gavage. In group 3, stem cells were used locally to the defect area. In group 4, stem cells and thymoquinone (10 mg/kg) was applied to the defect area. All rats were killed on the 28th day of the experiment. Tibia tissues extracted during sacrifice were histomorphologically examined in a fixative solution. Significant differences were found in terms of new bone formation and osteoblastic activity values in the "thymoquinone" (P<0.05), "stem cell" (P<0.05), and "stem cell+thymoquinone" (P<0.05) groups compared to the "control" group. In addition, while there was no significant difference in the "thymoquinone" group compared to these stem cell+thymoquinone group in terms of osteoblastic activity (P>0.05), the difference in terms of new bone formation was found to be significantly lower. No significant differences among the other groups were observed in new bone formation and osteoblastic activity (P>0.05). According to the results of our study, stem cell+thymoquinone treatment for bone defects is not only more effective than thymoquinone or stem cell treatment alone but also induces greater development of bone trabeculae, contributes to the matrix and connective tissue formation, and increases the number of osteoblasts and osteocytes involved in bone formation.

Three-Dimensional Finite Element Analysis of the Effect of Endosteal Implants with Different Macro Designs on Stress Distribution in Different Bone Qualities.

PURPOSE: The aim of this study was to analyze stress distribution on four different implant designs and four different qualities of cortical bone surrounding the implant crest modules using three-dimensional finite element analysis. MATERIALS AND METHODS: Four different implant designs of the same diameter and length (3.75 ± 11.5 mm) were used. Rhinoceros 4.0 3D modeling software was used for preparing the four types of bone quality (D1, D2, D3, and D4). Mandibular second premolar crowns were constructed as prosthetic superstructures of the implants, and a total force of 300 N was vertically applied to the crowns. Stress distribution on dental implants and cortical bone of D1, D2, D3, and D4 bone quality was evaluated. RESULTS: Among all of the implants, the maximum von Mises stress value on cortical bone surrounding the neck region of the implants was found in D4 bone quality, while the minimum stress was detected in D1 bone quality. The stress distribution on the threads of dental implants exhibited the most homogeneous distribution in D1 bone quality, while higher von Mises stress values were observed in the apical blade segment of the implants in D3 and D4 bone quality. CONCLUSION: It was found that the maximum stress of cortical bone surrounding the implant crest module decreased as the bone density increased. The microthreads on the implant crest module might cause an increase in stress to cortical bone surrounding the neck region of implants.

The effect of low-level laser therapy on the healing of hard palate mucosa and the oxidative stress status of rats.

OBJECTIVE: The biostimulation effects of low-level laser therapy (LLLT) have been demonstrated recently. This study investigated the effects of LLLT on palatal mucoperiosteal wound healing and oxidative stress status in rats. MATERIAL AND METHOD: Forty-two male Wistar rats weighing 250-300 g were used in this study. A standardized full-thickness wound was created in the mucoperiosteum of the hard palates of the rats using a 3-mm-diameter biopsy punch. Treatment using a GaAlAs laser at a wavelength of 940 nm and a dose of 10 J/cm(2) was initiated after surgery and repeated on the 2nd, 4th, and 6th days post-surgery. Seven animals from each group were sacrificed on the 7th, 14th, and 21st days after surgery. Total antioxidant status and total oxidative status were measured in serum. RESULTS: The histopathological findings revealed reduced numbers of inflammatory cells on the 7th day, increased mitotic activity of fibroblasts on the 14th and 21st day, and the same degree of collagen synthesis and vascularization on the days 7, 14, and 21 in the LLLT group compared with the control group. No significant differences in total oxidative status and total antioxidant status were observed between the groups. CONCLUSION: LLLT using a GaAlAs laser at a wavelength of 940 nm and a dose of 10 J/cm(2) elicited a positive healing effect on palatal mucoperiosteal wounds likely via the induction of fibroblasts. The oxidative stress status was not affected by LLLT.

The effects of low-level laser therapy on palatal mucoperiosteal wound healing and oxidative stress status in experimental diabetic rats.

OBJECTIVE: The biostimulation effects of low-level laser therapy (LLLT) have recently been demonstrated. In this study, we aimed to investigate the effects of LLLT on palatal mucoperiostal wound healing and oxidative stress status in experimental diabetic rats. MATERIALS AND METHODS: Forty-two male Wistar rats that weighed 250-300 g were used in this study. Experimental diabetes was induced in all of the rats using streptozotocin. A standardized full thickness wound was made in the mucoperiosteum of the hard palates of the rats using a 3 mm biopsy punch. The rats were divided into groups: 1 (control group, non- irradiated), and 2 (experimental group, irradiated). Treatment using a GaAlAs laser at a wavelength of 940 nm and at dose of 10 J/cm(2) began after surgery, and was repeated on the 2nd, 4th, and 6th days post-surgery. Seven animals from each group were killed on the 7th, 14th, and 21st day after surgery. Biopsies were performed for the histological analysis and blood samples were collected by cardiac puncture for biochemical analysis. RESULTS: The histopathological findings revealed reduced numbers of inflammatory cells, and increased mitotic activity of fibroblasts, collagen synthesis, and vascularization in rats in group 2. The total oxidative status was significantly decreased in the laser-treated group on the 21st day. CONCLUSIONS: LLLT elicits a positive healing effect on palatal mucoperiostal wounds, and modulates the oxidative status in experimental diabetic rats.

Effects of systemic zoledronic Acid administration on osseointegration of hydroxyapatite-coated and resorbable blast material surface implants in rabbit models.

PURPOSE: It is unknown whether zoledronic acid (ZA) interferes with initial bone healing at implant sites. The goal of this study was to examine the effects of systemic zoledronic acid administration on osseointegration of hydroxyapatite (HA)-coated and resorbable blast material surface (RBM) implants in rabbit models. MATERIALS AND METHODS: Twenty-eight male New Zealand rabbits (aged 6 to 12 months) were used in this study. Rabbits were randomly assigned to four groups. In group A, HA-coated implants were placed in the right tibia of seven rabbits. In group B, RBM-surface implants were placed in the right tibia of seven rabbits. In group C, HA-coated implants were placed in seven rabbits with intravenous (IV) administration of ZA. Finally, in group D, RBM-surface implants were placed in seven rabbits with IV administration of ZA. For groups C and D, IV zoledronic acid (0.1 mg/kg) was performed monthly during the entire osseointegration period. All of the rabbits were sacrificed 12 weeks after the implantation, and tibial specimens were harvested. Histomorphometric bone-to-implant contact (BIC) analysis and the data were statistically analyzed. RESULTS: The highest BIC percentage was detected in group D, with a mean value of 56.73%±1.85%, as compared with 45.80%±3.77% in group C, 35.11%±0.76% in group B, and 31.14%±1.04% in group A. CONCLUSIONS: Histomorphometric analyses showed significant improvement in the osseointegration of implants in the RBM-surface ZA group compared with the HA-coated ZA group. The results of this study suggest that systemic ZA administration may improve osseointegration of titanium implants in bone.

Distraction osteogenesis is inhibited by cancer radiotherapy with Co 60.

AIM: To investigate the effects of radiotherapy on distraction osteogenesis performed on the same bone in an area that has not received radiation. Radiotherapy (Co60) was carried out in a region where tumors may develop, and then, on the assumption that the tumoral region had been removed, distraction osteogenesis was carried out, and the effects were investigated. METHOD: Thirty New Zealand rabbits were randomized into two groups, a study group (15 rabbits) and a control group (15 rabbits). In the study group, Co60 was administered by teletherapy to the distal half of the left tibia. Rabbits in the control group were kept in the same environment for the same period, but were not subjected to radiotherapy. Four weeks after radiotherapy, osteotomy was performed on the proximal part of the left tibia of all subjects, and distraction was carried out until 10mm. After distraction was completed, the outcomes were evaluated radiologically, scintigraphically, and histopathologically, and the results were compared. RESULTS: New bone formation achieved through distraction osteogenesis in the study group animals was inadequate, while new bone tissue achieved in the control group was superior (P < 0.001). CONCLUSION: Radiotherapy has a negative effect on distraction osteogenesis, even if performed on a different part of the bone.