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Bulletin of Experimental Biology and... Dec 2023Stimulation of neoosteogenesis is the main mechanism of osseointegration during installation of dental implants, bone tissue recession, and alveolar process augmentation...
Stimulation of neoosteogenesis is the main mechanism of osseointegration during installation of dental implants, bone tissue recession, and alveolar process augmentation in adentia. In experiments on miniature pigs, we used the technology of two-stage splitting of the ridge of the alveolar process of the mandible in combination with a xenograft that was placed between the fragments of the split bone plate. The morphology of the reparative process and the distribution of osteogenic differentiation markers in the compact and trabecular bone of the alveolar crest were studied. Signs of reparative osteogenesis were observed in the bone regenerate that had a lamellar structure, formed osteons, and foci of woven tissue. It was found that the xenograft was replaced by newly formed trabecular bone tissue. These sites were characterized by increased expression of osteocalcin and CD44. Augmentation technology through two-stage splitting provides trophic relationship of osteoprogenitor cells and is an effective method of osteogenesis stimulation in the alveolar process.
Topics: Humans; Animals; Swine; Alveolar Ridge Augmentation; Osteogenesis; Bone Transplantation; Alveolar Process; Osseointegration; Mandible
PubMed: 38194070
DOI: 10.1007/s10517-024-06007-0 -
Bone Mar 2024Osteon morphology provides valuable information about the interplay between different processes involved in bone remodelling. The correct quantitative interpretation of...
Osteon morphology provides valuable information about the interplay between different processes involved in bone remodelling. The correct quantitative interpretation of these morphological features is challenging due to the complexity of interactions between osteoblast behaviour, and the evolving geometry of cortical pores during pore closing. We present a combined experimental and mathematical modelling study to provide insights into bone formation mechanisms during cortical bone remodelling based on histological cross-sections of quiescent human osteons and hypothesis-testing analyses. We introduce wall thickness asymmetry as a measure of the local asymmetry of bone formation within an osteon and examine the frequency distribution of wall thickness asymmetry in cortical osteons from human iliac crest bone samples from women 16-78 years old. Our measurements show that most osteons possess some degree of asymmetry, and that the average degree of osteon asymmetry in cortical bone evolves with age. We then propose a comprehensive mathematical model of cortical pore filling that includes osteoblast secretory activity, osteoblast elimination, osteoblast embedment as osteocytes, and osteoblast crowding and redistribution along the bone surface. The mathematical model is first calibrated to symmetric osteon data, and then used to test three mechanisms of asymmetric wall formation against osteon data: (i) delays in the onset of infilling around the cement line; (ii) heterogeneous osteoblastogenesis around the bone perimeter; and (iii) heterogeneous osteoblast secretory rate around the bone perimeter. Our results suggest that wall thickness asymmetry due to off-centred Haversian pores within osteons, and that nonuniform lamellar thicknesses within osteons are important morphological features that can indicate the prevalence of specific asymmetry-generating mechanisms. This has significant implications for the study of disruptions of bone formation as it could indicate what biological bone formation processes may become disrupted with age or disease.
Topics: Humans; Female; Adolescent; Young Adult; Adult; Middle Aged; Aged; Haversian System; Osteoblasts; Bone and Bones; Osteocytes; Cortical Bone
PubMed: 38184100
DOI: 10.1016/j.bone.2023.116998 -
Journal of the Mechanical Behavior of... Feb 2024Tissue fixation is a prevalent method for bone conservation. Bone biopsies are typically fixed in formalin, dehydrated in ethanol, and infiltrated with polymethyl...
Tissue fixation is a prevalent method for bone conservation. Bone biopsies are typically fixed in formalin, dehydrated in ethanol, and infiltrated with polymethyl methacrylate (PMMA) Since some experiments can only be performed on fixed bone samples, it is essential to understand how fixation affects the measured material properties. The aim of this study was to quantify the influence of tissue fixation on the mechanical properties of cortical ovine bone at the extracellular matrix (ECM) level with state-of-the-art micromechanical techniques. A small section from the middle of the diaphysis of two ovine tibias (3.5 and 5.5 years old) was cut in the middle and polished on each side, resulting in a pair of mirrored surfaces. For each pair, one specimen underwent a fixation protocol involving immersion in formalin, dehydration with ethanol, and infiltration with PMMA. The other specimen (mirrored) was air-dried. Six osteons were selected in both pairs, which could be identified in both specimens. The influence of fixation on the mechanical properties was first analyzed using micropillar compression tests and nanoindentation in dry condition. Additionally, changes in the degree of mineralization were evaluated with Raman spectroscopy in both fixed and native bone ECM. Finally, micro tensile experiments were conducted in the 3.5-year fixed ovine bone ECM and compared to reported properties of unfixed dry ovine bone ECM. Interestingly, we found that tissue fixation does not alter the mechanical properties of ovine cortical bone ECM compared to experiments in dry state. However, animal age increases the degree of mineralization (p = 0.0159) and compressive yield stress (p = 0.041). Tissue fixation appears therefore as a valid conservation technique for investigating the mechanical properties of dehydrated bone ECM.
Topics: Sheep; Animals; Tissue Fixation; Polymethyl Methacrylate; Formaldehyde; Ethanol; Extracellular Matrix
PubMed: 38128472
DOI: 10.1016/j.jmbbm.2023.106294 -
Ultrastructural Pathology Mar 2024Radiation exposure is a major health concern due to bone involvement including mandible, causing deleterious effects on bone metabolism, and healing with an increasing...
Radiation exposure is a major health concern due to bone involvement including mandible, causing deleterious effects on bone metabolism, and healing with an increasing risk of infection and osteoradionecrosis. This study aims to investigate the radiotherapy-induced microstructural changes in the human mandible by scanning electron microscopy (SEM). Mandibular cortical bone biopsies were obtained from control, irradiated, and patients with osteoradionecrosis (ORN). Bone samples were prepared for light microscopy and SEM. The SEM images were analyzed for the number of osteons, number of Haversian canal (HC), diameter of osteon (D.O), the diameter of HC (D.HC), osteonal wall thickness (O.W.Th), number of osteocytes, and number of osteocytic dendrites. The number of osteons, D.O, D.HC, O.W.Th, the number of osteocytes, and osteocytic dendrites were significantly decreased in both irradiated and ORN compared to controls ( < .05). The number of HCs decreased in irradiated and ORN bone compared to the control group. However, this was statistically not significant. The deleterious effect of radiation continues gradually altering the bone quality, structure, cellularity, and vascularity in the long term (>5 years mean radiation biopsy interval). The underlying microscopic damage in bone increases its susceptibility and contributes further to radiation-induced bone changes or even ORN.
Topics: Humans; Microscopy, Electron, Scanning; Osteoradionecrosis; Osteocytes; Haversian System; Mandible
PubMed: 38115187
DOI: 10.1080/01913123.2023.2295458 -
Anatomical Record (Hoboken, N.J. : 2007) Apr 2024Decuriasuchus quartacolonia is a middle-sized basal "rauisuchian" (Pseudosuchia, Loricata) from the Triassic beds of Brazil, whose original description was based on 10...
Bone histology supports gregarious behavior and an early ontogenetic stage to Decuriasuchus quartacolonia (Pseudosuchia: Loricata) from the Middle-Late Triassic of Brazil.
Decuriasuchus quartacolonia is a middle-sized basal "rauisuchian" (Pseudosuchia, Loricata) from the Triassic beds of Brazil, whose original description was based on 10 specimens of equivalent size found in aggregation. In this contribution, we explore the osteohistology of its appendicular bones and a rib, aiming to infer growth patterns and ontogeny. In all analyzed bones (except in the rib) from three individuals, we found fibrolamellar bone (FLB) throughout the cortices, a pattern shared with other histologically sampled basal loricatans. We found evidence that suggests an early ontogenetic stage for all studied specimens: absence of secondary osteons, lack of transition from an inner highly vascularized FLB matrix to a poor vascularized parallel-fibred bone, one line of arrested growth, open vascular canals in the external surface of the cortex and absence of an external fundamental system. In addition, we observed that the neurocentral sutures in the caudal to cervical vertebrae of the holotype are unfused, strongly suggesting that these individuals were not skeletally mature, as had been previously assumed. In addition, our data support the prior hypothesis that Decuriasuchus is the oldest-known archosaur to show evidence of gregarious behavior and adds a probable cause of this as a strategy to obtain food and avoid predation until becoming independent as adults. Furthermore, our results open the possibility that Decuriasuchus may represent an earlier growth stage of the larger Prestosuchus chiniquensis, with two specimens recovered from the same stratigraphic level and paleontological site. Since the adult form of Decuriasuchus remains unknown, a deeper anatomical study is needed to discuss the validity of the species. This study case exemplifies the importance of paleohistology as an essential complementary tool to describe a new morphospecies in vertebrate paleontology.
Topics: Humans; Animals; Brazil; Fossils; Paleontology; Bone and Bones; Vertebrates
PubMed: 38088505
DOI: 10.1002/ar.25365 -
BioEssays : News and Reviews in... Feb 2024Bisphosphonates are a class of drugs which have shown good efficacy in the treatment of post-menopausal osteoporosis, as well as a good safety profile. However,...
Towards understanding how bisphosphonate-dependent alterations to nutrient canal integrity can contribute to risk for atypical femoral fractures: Biomechanical considerations and potential relationship to a real-world analogy.
Bisphosphonates are a class of drugs which have shown good efficacy in the treatment of post-menopausal osteoporosis, as well as a good safety profile. However, side-effects such as risk for atypical femoral fractures (AFF) have appeared, leading to a decline in use of the drugs by many patients who would benefit from the treatment. While patient characteristics have contributed to improved understanding of risk factors, the mechanisms involved that explain AFF risk have not appeared. Recently, the possibility that the mechanism(s) involved drug-induced modification of cells of the nutrient canals of the femur and subsequent compromise in the bone matrix has been published. The present Hypothesis article builds on the concept presented earlier and expands into biomechanical considerations. An analogy of the mechanisms involved to a real-life scenario is also presented. While this analogy has limitations, consideration of the biomechanical implications of progressive alterations to defects presented by compromised nutrient canal-bone matrix also presents potential relationships with AFF risk.
Topics: Humans; Diphosphonates; Osteoporosis; Haversian System; Femoral Fractures; Risk Factors
PubMed: 38059881
DOI: 10.1002/bies.202300117 -
Journal of Oral and Maxillofacial... 2023Osteomyelitis is an inflammatory condition of the bones that often starts with an infection of the medullary cavity and swiftly extends to the haversian system and...
Osteomyelitis is an inflammatory condition of the bones that often starts with an infection of the medullary cavity and swiftly extends to the haversian system and periosteum. If drainage and antimicrobials are ineffective, acute osteomyelitis may progress to chronic osteomyelitis. Here, we offer a unique case that analyzes the radiographic and clinical characteristics of osteomyelitis with underlying disease. Cysts and cyst-like lesions of the jaws must be diagnosed and evaluated using radiographic findings in conjunction with clinical complaints. This case study examines the circumstances that led to the diagnosis of osteomyelitis and demonstrates several noteworthy lessons. As decortication is less invasive and more effective at treating primary chronic osteomyelitis than peripheral or segmental excision of the jaw, and the use of vancomycin as local hard and soft tissue dressing over the surgical site, we emphasize its significance.
PubMed: 38033960
DOI: 10.4103/jomfp.jomfp_533_22 -
Dental Research Journal 2023This study compared the effect of various grafting materials on the area and volume of minerals attached to dental implants.
BACKGROUND
This study compared the effect of various grafting materials on the area and volume of minerals attached to dental implants.
MATERIALS AND METHODS
In this animal study, 13 dogs were divided into three groups according to the time of sacrificing (2 months, 4 months, or 6 months). The implants were placed in oversized osteotomies, and the residual defects were filled with autograft, bovine bone graft (Cerabone), or a synthetic substitute (Osteon II). At the designated intervals, the dogs were sacrificed and the segmented implants underwent micro-computed tomography analysis. The bone-implant area (BIA) and bone-implant volume (BIV) of bone and graft material were calculated in the region of interest around the implant. The data were analyzed by two-way analysis of variance (ANOVA) at < 0.05.
RESULTS
There was no significant difference in BIA and BIV between the healing intervals for any of the grafting materials ( > 0.05). ANOVA exhibited comparable BIA and BIV between the grafting materials at 2 and 4 months after surgery ( > 0.05), although a significant difference was observed after 6 months ( < 0.05). Pairwise comparisons revealed that BIA was significantly greater in the autograft-stabilized than the synthetic-grafted sites ( = 0.035). The samples augmented with autograft also showed significantly higher BIV than those treated by the xenogenic ( = 0.017) or synthetic ( = 0.002) particles.
CONCLUSION
All graft materials showed comparable performance in providing mineral support for implants up to 4 months after surgery. At the long-term (6-month) interval, autogenous bone demonstrated significant superiority over xenogenic and synthetic substitutes concerning the bone area and volume around the implant.
PubMed: 38020252
DOI: No ID Found -
Journal of Anatomy Mar 2024The artiodactyl (deer and sheep) calcaneus is a model that helps in understanding how many bones achieve anatomical optimization and functional adaptation. We consider...
The artiodactyl (deer and sheep) calcaneus is a model that helps in understanding how many bones achieve anatomical optimization and functional adaptation. We consider how the dorsal and plantar cortices of these bones are optimized in quasi-isolation (the conventional view) versus in the context of load sharing along the calcaneal shaft by "tension members" (the plantar ligament and superficial digital flexor tendon). This load-sharing concept replaces the conventional view, as we have argued in a recent publication that employs an advanced analytical model of habitual loading and fracture risk factors of the deer calcaneus. Like deer and sheep calcanei, many mammalian limb bones also experience prevalent bending, which seems problematic because the bone is weaker and less fatigue-resistant in tension than compression. To understand how bones adapt to bending loads and counteract deleterious consequences of tension, it is important to examine both strain-mode-specific (S-M-S) testing (compression testing of bone habitually loaded in compression; tension testing of bone habitually loaded in tension) and non-S-M-S testing. Mechanical testing was performed on individually machined specimens from the dorsal "compression cortex" and plantar "tension cortex" of adult deer calcanei and were independently tested to failure in one of these two strain modes. We hypothesized that the mechanical properties of each cortex region would be optimized for its habitual strain mode when these regions are considered independently. Consistent with this hypothesis, energy absorption parameters were approximately three times greater in S-M-S compression testing in the dorsal/compression cortex when compared to non-S-M-S tension testing of the dorsal cortex. However, inconsistent with this hypothesis, S-M-S tension testing of the plantar/tension cortex did not show greater energy absorption compared to non-S-M-S compression testing of the plantar cortex. When compared to the dorsal cortex, the plantar cortex only had a higher elastic modulus (in S-M-S testing of both regions). Therefore, the greater strength and capacity for energy absorption of the dorsal cortex might "protect" the weaker plantar cortex during functional loading. However, this conventional interpretation (i.e., considering adaptation of each cortex in isolation) is rejected when critically considering the load-sharing influences of the ligament and tendon that course along the plantar cortex. This important finding/interpretation has general implications for a better understanding of how other similarly loaded bones achieve anatomical optimization and functional adaptation.
Topics: Animals; Sheep; Calcaneus; Deer; Lower Extremity; Stress, Mechanical; Biomechanical Phenomena
PubMed: 37953064
DOI: 10.1111/joa.13971 -
Bone Reports Dec 2023Larger animal models with a well-developed Haversian system, as observed in humans, are ideal to analyze cortical bone remodeling in pharmacological studies of...
Evaluation of cortical bone remodeling in canines treated with daily and weekly administrations of teriparatide by establishing AI-driven morphometric analyses and GIS-based spatial mapping.
Larger animal models with a well-developed Haversian system, as observed in humans, are ideal to analyze cortical bone remodeling in pharmacological studies of anti-osteoporosis drugs, although they have some limitations in controlling individual variability in size, weight, age, and number. This study aimed to morphometrically analyze cortical bone remodeling focusing on Haversian canals in dogs using four regimens of TPTD with daily and weekly administrations at lower and higher weekly doses (4.9 μg/kg/week and 19.8 μg/kg/week, respectively) for 9 months. A micro-computed tomography-based analysis showed no significant differences among regimen groups. By establishing artificial intelligence (AI)-driven morphometric analyses and geographical information system (GIS)-based spatial mapping of Haversian canals that does not require confocal microscopy but is possible with more commonly used wide field microscopes, we successfully observed significant morphometric distinctions among regimens applied even in dogs. Our analytical results suggested that the daily higher regimen specifically increased the number of eroded pores creating spaces between existing canals, thus stimulating cortical bone remodeling.
PubMed: 37915737
DOI: 10.1016/j.bonr.2023.101720