Effect of Topical PTH 1-34 Functionalized to Biogran® in the Process of Alveolar Repair in Rats Submitted to Orchiectomy

(1) Background: There are many therapies for osteoporosis control and bone maintenance; anabolic drugs such as teriparatide and bone grafts help in the repair process and stimulate bone formation. Thus, the aim of the present study was to evaluate the behavior of repaired bone in the presence of PTH (teriparatide) associated with Biogran® (biomaterial) through a sonochemical procedure after extraction in rats. (2) Methods: The insertion of Biogran® with PTH in the alveolus was performed 30 days after incisor extraction. Euthanasia occurred after 60 days. (3) Results: The use of local treatment of PTH loaded with Biogran® in healthy rats promoted good results for micro-CT, with an increase in percentage and bone volume, number and trabecular separation and less total porosity. Greater immunostaining for Wnt, β-Catenin and osteocalcin proteins and lower expression for Thrombospondin-Related Adhesive Protein (TRAP), which shows an increase in the number of osteoblasts and inhibition of osteoclast action. However, the treated orchiectomized groups did not obtain such expressive results. (4) Conclusion: The use of Biogran® with PTH improved alveolar repair in rats. However, new researches with more efficient doses must be studied to collaborate effectively with the formation of a quality bone after the orchiectomy.

Assessment of Bone Regeneration Using Tooth Ash and Injectable Platelet Rich Fibrin: A Microcomputed Tomographic (CT) Analysis

Introduction: One of the main challenge of bone graft or socket preservation in particular is to get good quality and quantity of bone in short time prior to implant bed preparation. The buccal bone at the crest of the ridge is a very thin bone and usually resorb faster than the rest of alveolar bone which may hinder an optimum dento-osseous implant insertion. The purpose of this study will be to assess the bone regeneration capabilities of Tooth Ash Particles (TAP) with injectable Plasma Rich Fibrin (i-PRF) and Tooth Ash Particles (TAP) alone at defects created in the goat mandible bone using micro-computed tomographic (micro-CT). Materials and Methods: A total, 54 bone defect (5 mm × 8 mm) were performed in the 18 goats. The created defect received different treatment (Tx): Tx.A: Unfilled defect (allow natural bone regeneration; Tx.B: Tooth Ash particle (TAP) alone; Tx.C: Tooth Ash + injectable PRF (TAP/i-PRF). Six goats, were sacrificed at different time points:Group 1: at 2nd week, Group2: at 5th week and Group3 at 8th week. The newly formed bone (NFB) was analyzed using micro-CT at different time points. Quantitative and qualitative assessment were carried out namely; the volume of new bone formation (NF-BV) within the defect and its mineral density (NF-BMD), Trabecular Thickness (Tb Th), Trabecular Number (Tb N) and Trabecular Separation (Tb Sp). Result: By 8th week, the mean NF-BV was 69.482 ± 6.554 mm3 (cubic millimeter), 65.872±6.804 mm3, 26.820±14.643 mm3, while the mean NF-BMD was 0.417±0.119g/mm3, 0.786±0.036 g/mm3, 0.805±0.033 g/mm3 for the defects which received Tx.C, Tx.B and Tx.A respectively. At 8th weekTb Th of NFB was 0.612±0.168, 0.913±0.112, and 0.701 ±0.126, Trabecular Number of NFB was 2.062±0.946, 1.002±0.155, and 1.816±2.042 and, Trabecular Separation of NFB was 0.330 ±0.131, 0.559 ±0.110, and 0.495 ±0.258 for the defects which received Tx.A, Tx.B and Tx.C respectively. Conclusion: Micro-CT study demonstrated that tooth ash particles mixed with injectable Platelet Rich Fibrin (i-PRF) on mandibular bone defect in goat’s model, resulting in new bone with significantly higher volume, mineral density and less remodeling rate when compared with normal bone regeneration of unfilled defects.

Bone structure determined by HR-MDCT does not correlate with micro-CT of lumbar vertebral biopsies: a prospective cross-sectional human in vivo study

Background Osteoporosis is characterized by a deterioration of bone structure and quantity that leads to an increased risk of fractures. The primary diagnostic tool for the assessment of the bone quality is currently the dual-energy X-ray absorptiometry (DXA), which however only measures bone quantity. High-resolution multidetector computed tomography (HR-MDCT) offers an alternative approach to assess bone structure, but still lacks evidence for its validity in vivo. The objective of this study was to assess the validity of HR-MDCT for the evaluation of bone architecture in the lumbar spine. Methods We conducted a prospective cross-sectional study to compare the results of preoperative lumbar HR-MDCT scans with those from microcomputed tomography (μCT) analysis of transpedicular vertebral body biopsies. For this purpose, we included patients undergoing spinal surgery in our orthopedic department. Each patient underwent preoperative HR-MDCT scanning (L1-L4). Intraoperatively, transpedicular biopsies were obtained from intact vertebrae. Micro-CT analysis of these biopsies was used as a reference method to assess the actual bone architecture. HR-MDCT results were statistically analyzed regarding the correlation with results from μCT. Results Thirty-four patients with a mean age of 69.09 years (± 10.07) were included in the study. There was no significant correlation for any of the parameters (bone volume/total volume, trabecular separation, trabecular thickness) between μCT and HR-MDCT (bone volume/total volume: r = − 0.026 and p = 0.872; trabecular thickness: r = 0.074 and r = 6.42; and trabecular separation: r = − 0.18 and p = 0.254). Conclusion To our knowledge, this is the first study comparing in vivo HR-MDCT with μCT analysis of vertebral biopsies in human patients. Our findings suggest that lumbar HR-MDCT is not valid for the in vivo evaluation of bone architecture in the lumbar spine. New diagnostic tools for the evaluation of osteoporosis and preoperative orthopedic planning are urgently needed.

Validation of a rabbit model of irradiated bone healing: preliminary report

Introduction: External radiotherapy can lead to severe bone alteration. The aim of this pilot study was to validate a model for assessment of postextractional bone healing in the irradiated rabbit mandible. Material and method: The radiation protocol consisted of 5 sessions delivering 8.5 Gy each. Surgery was performed immediately after completion of radiotherapy. Sacrifices were performed from Day 0 to Day 42. Results: The bone mineral density and the trabecular number were decreased after radiotherapy whereas trabecular separation increased. The main differences between irradiated and non-irradiated rabbits were observed at Day 28 and 42. Discussion: Radiation seems to cause a delay in bone healing. It decreases bone quality and bone mineral density. Five sessions seem to be a valuable compromise between tissues effect and feasibility of the experiment. Conclusion: This model seems to be valuable for evaluating postextractional bone healing in the irradiated rabbit mandible.

Effects of Leukocyte-Platelet-Rich Plasma on the Alveolar Bone Changes During Orthodontic Tooth Movement in Rabbits: A Micro-CT Study

Objective: To investigate the effects of leukocyte-platelet-rich plasma (L-PRP) on the alveolar bone changes at the compression and tension sides during orthodontic tooth movement. Materials and Methods: Around 20 New Zealand white rabbits were used in a split-mouth design. The maxillary first premolar was moved mesially with a nickel-titanium closed-coil spring. One side of the maxilla was randomly injected with L-PRP, while the contralateral side served as the control which received normal saline. The alveolar bone adjacent to the maxillary first premolar was scanned using microcomputed tomography at days 0, 7, 14, and 28. Microstructural parameters including bone volume fraction, trabecular thickness, and trabecular separation of alveolar bone were assessed on the compression and tension sides of the maxillary first premolar. Results: Compared between the groups, the L-PPR group showed a significantly decreased bone volume fraction on the compression side on days 7 and 14 but significantly increased bone volume fraction on the tension side on day 14. However, there were no statistically significant differences in the parameters of trabecular thickness and trabecular separation. Conclusion: Local administration of L-PRP may promote bone resorption on the compression side and bone formation on the tension side at the initial stage of orthodontic tooth movement.

Measurement of trabecular bone parameters with different bone thickness and voxel size in mice using micro CT

Micro-CT is one of the best modalities in assessing bone morphology and microarchitecture in small animal models. Voxel size is directly related to the image resolution as it influences the bone morphology results. The purpose of this study was to assess the effects of t different thicknesses of structures on the trabecular bone qualitative parameters. It was also to find out the most appropriate voxel size when scanning a certain or specific body part with different thicknesses. Five BALB-C breed mice carcasses were scanned using two different voxel sizes of 18 and 35 µm. The scanning acquisition times were recorded to be compared and the trabecular bone parameters measurements were taken. Both trabecular number and trabecular separation were increased in thicker structures meanwhile bone volume fraction and trabecular thickness values were inconsistent with the increment of the structure thickness. The bone volume fraction, trabecular thickness and trabecular separation were higher in larger voxel size and vice versa for trabecular number. The scanning acquisition time has no apparent correlation with the trabecular bone parameters. The thickness of the bone structure did affect trabecular number and trabecular separation significantly but less affecting bone volume fraction and trabecular thickness. All trabecular bone parameters were found affected by the size of scanning voxel size used. The usage of 35 µm voxel was more recommended than 18 µm to save time and give out less radiation dose to specimen unless the detailed features of the trabecular pattern was very important.

Viscoelastic Properties of the Hindfoot Bones

Category: Hindfoot Introduction/Purpose: Obtaining and maintaining compression at an arthrodesis site is a key factor in achieving successful bony union. Bones, like other collagen containing tissues, are known to exhibit viscoelastic properties that may lead to stress relaxation at the arthrodesis site. The viscoelastic properties of the hindfoot bones when subjected to compression (as occurs during fusion surgery) are not known. The objective of this study was to quantify the viscoelastic properties of hindfoot bones under compression by measuring the time course of stress relaxation. Methods: 19 cadaveric human bone cubes 10 mm on each side consisting of trabecular and subchondral bone were cut from the hindfoot bones including the talus, calcaneus, and distal tibia. Each cube was scanned with micro computed tomography (µCT) to quantify bone volume/total volume ratio (BV/TV), trabecular thickness, trabecular separation, trabecular number, and connectivity density. Each specimen was then immersed in a saline bath and compressed 1 mm at a strain rate of 1 mm/s using an MTS machine (Fig 1). This compressed position was then held for 3 hours while the load was recorded. Following the compression test, each specimen was re-scanned with µCT. Results: Two distinct patterns of load relaxation were found. The first consisted of a uniform exponential decay. The second had a similar exponential decay but included a plateau occurring between 1-6 minutes. This second pattern was reflected in the average fractional load relaxation graph (Fig 2). The average peak load was 24.14 kg (SD ± 15.07 kg) and average end relaxation was 2.93 kg (SD ± 3.81 kg). The average time to achieve 95% decay in total load was 34.7 min (SD ± 29.1 min) although removing some outliers, it decreased to 24.9 min (SD ± 18.4 min) which is more representative of the overall data. Averages of BV/TV, trabecular thickness, and trabecular separation increased after stress relaxation while average connectivity density and trabecular number decreased. Conclusion: These data suggest that, due to the viscoelastic properties of bone, approximately 95% of an applied compressive load generated by a fixed displacement is lost within the first 30 minutes. Applied clinically, these findings may have a significant impact on the optimal surgical technique used for osteosynthesis and arthrodesis. Specifically, these data call into question whether the compression applied during surgery can be maintained throughout the healing phase without the application of continuous compression via an external fixator or internal continuous compression device. At minimum, these data suggest that lag or compression screws should be retightened prior to wound closure.

Cross-sex testosterone therapy in ovariectomized mice: addition of low-dose estrogen preserves bone architecture

Cross-sex hormone therapy (XHT) is widely used by transgender people to alter secondary sex characteristics to match their desired gender presentation. Here, we investigate the long-term effects of XHT on bone health using a murine model. Female mice underwent ovariectomy at either 6 or 10 wk and began weekly testosterone or vehicle injections. Dual-energy X-ray absorptiometry (DXA) was performed (20 wk) to measure bone mineral density (BMD), and microcomputed tomography was performed to compare femoral cortical and trabecular bone architecture. The 6-wk testosterone group had comparable BMD with controls by DXA but reduced bone volume fraction, trabecular number, and cortical area fraction and increased trabecular separation by microcomputed tomography. Ten-week ovariectomy/XHT maintained microarchitecture, suggesting that estrogen is critical for bone acquisition during adolescence and that late, but not early, estrogen loss can be sufficiently replaced by testosterone alone. Given these findings, we then compared effects of testosterone with effects of weekly estrogen or combined testosterone/low-dose estrogen treatment after a 6-wk ovariectomy. Estrogen treatment increased spine BMD and microarchitecture, including bone volume fraction, trabecular number, trabecular thickness, and connectivity density, and decreased trabecular separation. Combined testosterone-estrogen therapy caused similar increases in femur and spine BMD and improved architecture (increased bone volume fraction, trabecular number, trabecular thickness, and connectivity density) to estrogen therapy and were superior compared with mice treated with testosterone only. These results demonstrate estradiol is critical for bone acquisition and suggest a new cross-sex hormone therapy adding estrogens to testosterone treatments with potential future clinical implications for treating transgender youth or men with estrogen deficiency.

Meloxicam as a Radiation-Protective Agent on Mandibles of Irradiated Rats

This study evaluated the action of ionizing radiation and the possible radioprotective effect of the non-steroidal anti-inflammatory drug meloxicam on the bone physiology of rat mandibles by assessing the alveolar socket healing and bone strength. Forty male Wistar rats were divided in 4 groups (n=10): control (CG), irradiated (IG), meloxicam (MG), meloxicam irradiated (MIG). A dose of 0.2 mg/kg meloxicam was administered to MG and MIG. After this, IG and MIG were irradiated with 15 Gy radiation dose in the mandible. Forty days after the above procedures, the mandibular first molars were extracted and the animals were killed after 15 or 30 days (n=5). Micro-computed tomography and bending test were used to evaluate alveolar socket healing and bone strength, respectively. At 15 days, bone volume, bone volume fraction and trabecular thickness were higher in the CG and MG than in the IG and MIG; and trabecular separation was higher in the IG compared with the others. At 30 days, there was a difference only in trabecular separation, which was higher in IG than in CG and MG, and MIG did not differ from the others. Bone strength was lower in IG compared with CG and MG, and MIG did not differ from the others. In conclusion, the ionizing radiation affected the bone physiology of rat mandibles, delaying the alveolar socket healing and reducing the bone strength. Moreover, the meloxicam had a positive effect on the trabecular separation in alveolar socket healing and on the bone strength.