Absence Of Bone Resorption Research Articles

Reconstruction of Craniomaxillofacial Bone Defects with 3D-Printed Bioceramic Implants: Scoping Review and Clinical Case Series.

Reconstruction of craniomaxillofacial bone defects using 3D-printed hydroxyapatite (HA) bioceramic patient-specific implants (PSIs) is a new technique with great potential. This study aimed to investigate the advantages, disadvantages, and clinical outcomes of these implants in craniomaxillofacial surgeries. The PubMed and Embase databases were searched for patients with craniomaxillofacial bone defects treated with bioceramic PSIs. Clinical outcomes such as biocompatibility, biomechanical properties, and aesthetics were evaluated and compared to those of commonly used titanium or poly-ether-ether-ketone (PEEK) implants and autologous bone grafts. Two clinical cases are presented to illustrate the surgical procedure and clinical outcomes of HA bioceramic PSIs. Literature review showed better a biocompatibility of HA PSIs than titanium and PEEK. The initial biomechanical properties were inferior to those of autologous bone grafts, PEEK, and titanium but improved when integrated. Satisfactory aesthetic results were found in our two clinical cases with good stability and absence of bone resorption or infection. Radiological signs of osteogenesis were observed in the two clinical cases six months postoperatively. HA bioceramic PSIs have excellent biocompatible properties and imitate natural bone biomechanically and radiologically. They are a well-suited alternative for conventional biomaterials in the reconstruction of load-sharing bone defects in the craniomaxillofacial region.

Chromolaena odorata (L.) R. M. King and H. Robinson Leaves Aqueous Extract Improves the Femoral Head in Ethanol-Induced Osteonecrosis in Rats.

Chronic alcohol consumption damages bone formation and causes bone pathology, including osteonecrosis of the femoral head. The aim of this work was to evaluate the effects of the leaf aqueous extract of Chromolaena odorata (C. odorata) on the femoral head in ethanol-induced osteonecrosis in rats. Animals received alcohol (40°) at 3 g/kg for 12 weeks. A group of animals were sacrificed to attest to the instalment of osteonecrosis by using histopathological analysis. The remaining animals received alcohol concomitantly with the plant extract (150, 300, or 600 mg/kg) or diclofenac (1 mg/kg) for 28 additional days. At the end of the experimental period, biochemical parameters including total cholesterol, triglycerides, calcium, alkaline phosphatase (ALP), reduced glutathione (GSH), malondialdehyde (MDA), nitrite, superoxide dismutase (SOD), and catalase activities were measured. Histopathological and histomorphometry analyses of femurs were also assessed. The administration of alcohol, irrespective of the experimental period, induced a significant increase in total cholesterol (p < 0.05) and triglyceride (p < 0.01) and a decrease in ALP (p < 0.05) and calcium (p < 0.05-p < 0.001) levels. Intoxicated animals showed an alteration in oxidative stress parameters accompanied by a significant drop in bone cortical thickness and density with necrosis and marked bone resorption. The concomitant administration of the plant with ethanol reversed the alcohol-induced bone defect, characterized by the improvement of the lipid profile (p < 0.001), bone calcium concentration (p < 0.05), bone ALP activity (p < 0.001), oxidative stress parameters, improved cortical bone thickness (p < 0.01), and bone density (p < 0.05). These results are supported by the absence of bone resorption with an obvious effect at a dose of 300 mg/kg. The pharmacological effect of the extract on ethanol-induced osteonecrosis of the femoral head is probably due to its osteogenic, hypolipidemic, and antioxidant properties, justifying its use in Cameroonian folk medicine for articulation and bone pain management.

Evaluation of marginal bone loss in implant supported over-dentures

Aim: The purpose of the present research was to assess the marginal bone loss due to stresses encountered in implant supported over-dentures. Methodology: Tridimensional models were built from the images of a computerized tomography of a mandible and 3D laser digitalization of implants, abutments, mucosa, and complete denture. The geometric models of implants and abutments were mounted at the canine region to build reference model 1 - absence of bone resorption. To build the test models the mandible geometric solid was modified to simulate 2-mm vertical bone loss surrounding the implants (model 2) and resorption of the distal ridge (model 3). Finite elements models were generated, and a 100 N static load was applied at the first molar region of each model to compare the von Mises stress distributions in selected points. Results: Von Mises stresses increased on the bone surrounding implants and on the prosthetic components in the model with 2-mm vertical bone loss. The combination of 2-mm vertical bone loss and resorption of the distal ridge did not increase the stresses compared with the model with only bone loss surrounding implants.

An evaluation of the host response to an interspinous process device based on a series of spine explants: Device for Intervertebral Assisted Motion (DIAM®)

The objective of this study was to evaluate the host response to an interspinous process device [Device for Intervertebral Assisted Motion (DIAM®)] based on a series of nine spine explants with a mean post-operative explant time of 35 months. Explanted periprosthetic tissues were processed for histology and stained with H&E, Wright-Giemsa stain, and Oil Red O. Brightfield and polarized light microscopy were used to evaluate the host response to the device and the resultant particulate debris. The host response was graded per ASTM F981-04. Quantitative histomorphometry was used to characterize particle size, shape, and area per ASTM F1877-05. The presence or absence of bone resorption was also evaluated when bony tissue samples were provided. Periprosthetic tissues demonstrated a non-specific foreign body response composed of macrophages and foreign body giant cells to the DIAM® device in most of the accessions. The foreign body reaction was not the stated reason for explantation in any of the accessions. Per ASTM F981-04, a "very slight" to "mild" to "moderate" chronic inflammatory response was observed to the biomaterials and particulate, and this varied by tissue sample and accession. Particle sizes were consistent amongst the explant patients with mean particle size on the order of several microns. Osteolysis, signs of toxicity, necrosis, an immune response, and/or device related infection were not observed. Cyclic loading of the spine can cause wear in dynamic stabilization systems such as DIAM®. The fabric nature of the DIAM® device's polyethylene terephthalate jacket coupled with the generation of polymeric particulate debris predisposes the device to a foreign body reaction consisting of macrophages and foreign body giant cells. Although not all patients are aware of symptoms associated with a foreign body reaction to a deeply implanted device, surgeons should be aware of the host response to this device.

24,25-Dihydroxyvitamin D3 cooperates with a stable, fluoromethylene LPA receptor agonist to secure human (MG63) osteoblast maturation

Vitamin D receptor (VDR) agonists supporting human osteoblast (hOB) differentiation in the absence of bone resorption are attractive agents in a bone regenerative setting. One potential candidate fulfilling these roles is 24,25-dihydroxy vitamin D3 (24,25D). Over forty years ago it was reported that supraphysiological levels of 24,25D could stimulate intestinal calcium uptake and aid bone repair without causing bone calcium mobilisation. VDR agonists co-operate with certain growth factors to enhance hOB differentiation but whether 24,25D might act similarly in promoting cellular maturation has not been described. Given our discovery that lysophosphatidic acid (LPA) co-operated with VDR agonists to enhance hOB maturation, we co-treated MG63 hOBs with 24,25D and a phosphatase-resistant LPA analog. In isolation 24,25D inhibited proliferation and stimulated osteocalcin expression. When co-administered with the LPA analog there were synergistic increases in alkaline phosphatase (ALP). These are encouraging findings which may help realise the future application of 24,25D in promoting osseous repair.

Zoledronic acid – Related osteonecrosis of the jaws. Experimental model with dental extractions in rats

IntroductionBisphosphonate-related osteonecrosis of the jaws (BRONJ) is a pathologic condition of increasing frequency, with a poorly understood pathophysiology and which can be difficult to manage.The aim of this study was to find a reproducible experimental model that directly relates chronic bisphosphonate administration with the development of osteonecrosis with or without tooth extraction, with no other drug involved. Material and methodsTwenty male Wistar rats were divided into 4 groups (n = 5/group). Animals were injected over 9 weeks with zoledronic acid (0.1 mg/kg). In groups 1 and 2 three times a week intraperitoneally, and in group 3 once a week intravenously. A control group (group 4) received intraperitoneal injections of saline solution three times a week. After 8 weeks of treatment, 3 right upper jaw molars were extracted in groups 1, 3 and 4 and all rats were sacrificed 1 week later. The maxillae were histologically analyzed for presence of osteonecrosis foci, number of osteoclasts, vascularity, bone resorption status and presence of abscess. Radiographic examination was performed with a plain radiograph of each hemi-head. ResultsWe found that group 1 (dental extractions and highest cumulative dose of zoledronic acid) had the highest incidence of osteonecrosis (80%), absence of bone resorption (100%) and lowest number of osteoclasts (mean 7.9/field at 40×). Zoledronic acid-treated groups showed variable degrees of osteosclerosis and trabecular disorganization on X-ray study. ConclusionsWe offer a new animal model of BRONJ after zoledronic acid administration and dental extractions, achieving bone changes similar or superior to previous studies, highlighting the dental extraction as an important trigger factor.

Stresses in implant-supported overdentures with bone resorption: a 3-D finite element analysis

PURPOSE: This 3D-finite elements method study evaluated the effect of bone resorption on the stress distribution in overdentures with bone loss surrounding implants and resorption of the distal ridge. METHODS: Tridimensional models were built from the images of a computerized tomography of a mandible and 3D laser digitalization of implants, abutments, mucosa, and complete denture. The geometric models of implants and abutments were mounted at the canine region to build reference model 1 - absence of bone resorption. To build the test models the mandible geometric solid was modified to simulate 2-mm vertical bone loss surrounding the implants (model 2) and resorption of the distal ridge (model 3). Finite elements models were generated, and a 100 N static load was applied at the first molar region of each model to compare the von Mises stress distributions in selected points. RESULTS: Von Mises stresses increased on the bone surrounding implants and on the prosthetic components in the model with 2-mm vertical bone loss. The combination of 2-mm vertical bone loss and resorption of the distal ridge did not increase the stresses compared with the model with only bone loss surrounding implants. The highest stress concentration at marginal bone and implants occurred on the same side of the vertical load application for all models. CONCLUSION: The results suggest that the bone loss surrounding implants increases stress concentration in dental implants, abutments, and marginal bone independently from the bone resorption of the distal ridge.

Progressive increase in bone mass and development of odontomas in aging osteopetrotic c- src-deficient mice

The critical role of c- src in osteoclast-mediated bone resorption has been emphasized by gene deletion experiments in mice. However, the long-term effects of the lack of c- src and impaired osteoclast function on the skeleton remain unknown. To further study the physiological role of c- src and to circumvent the early death of src −/− mice, due to starvation in the absence of erupted teeth, we maintained mice on a liquid diet. At the age of 2 months the src −/− mice presented signs of airway obstruction and all mice died progressively between 2.5 and 6 months of age. Radiography demonstrated severe osteopetrosis of the whole skeleton. Histomorphometrical analysis of the src −/− mice confirmed a significant increase in bone mass with age, resulting in complete loss of bone marrow spaces in some bones and explaining the consistent hepatosplenomegaly, due to extraskeletal hematopoesis. Histopathological examination of the skull revealed the presence of odontomas in the region of the unerupted incisors, with a penetrance of 100% in the aging src −/− mice. Although odontomas are benign lesions, their progressive growth leads to the obliteration of the nasal airways, progressive suffocation, and death in src −/− mice. These results suggest that: (i) in the absence of bone resorption, bone formation continues and leads to progressive accentuation of the osteopetrotic phenotype in src −/− mice; (ii) osteoclastic function is required for regular eruption of the incisors and deficient bone resorption is associated with the development of odontomas; and (iii) src −/− mice die by suffocation due to airway obliteration as a result of progressive odontoma growth.

The Actions and Interactions of Sex Steroids and Growth Factors/Cytokines on the Skeleton

The discoveries that sex steroid receptors for estrogen [estrogen receptor (ER)], androgen [androgen receptor (AR)], and progesterone [progesterone receptor (PR)] are present in the bone-forming osteoblasts (OB) and bone-resorbing osteoclasts (OCL), and that these cells are targets for sex steroid action, have generated much excitement in the field of bone biology. The subsequent discoveries that the sex steroids regulate the production of growth factors and cytokines in these OB and OCL cells and that these factors mediate much of the steroid action on the skeleton have added to the excitement and complexity of the system. Because of the required brevity of this minireview, we will discuss only selected aspects of this field using a limited number of references and review articles. For more information in this field, readers are referred to several recent books and chapters that review bone biology, bone diseases, and the role of sex steroids in bone biology and disease (1–8). As a brief background to this unique system, the skeletal maintenance involves a continuous remodeling at discrete sites termed bone-remodeling units (BRU). As outlined in Fig. 1, the multinucleated boneresorbing OCLs first dissolve bone at these BRU sites, resulting in resorption cavities. While the mechanism(s)/signal(s) that initiates resorption at a given site is unknown, there appears to be a marked regulation of overall bone resorption via the regulation of the OCL differentiation and activity (5–8). These processes are discussed in more detail below. The bone-forming OBs are then recruited by unknown signals, to replace the previously resorbed bone. The identities of the primary factors that couple these processes of resorption to formation to maintain bone mass are also addressed later in this review and are still the subject of much debate. During periods of skeletal growth in children, the increase in bone formation largely involves bone modeling (accretion of bone at surfaces in the absence of bone resorption). The response to mechanical stresses also utilizes mostly modeling. During early adulthood (20–40 yr), bone resorption and formation are in balance and bone mass is maintained. The increased serum estrogen (E) level, which occurs at the onset of puberty in girls, is accompanied by an increase in growth velocity and, ultimately, in the closure of the epiphyseal growth plate and the cessation of linear growth (9). E is the primary hormone responsible for maintaining bone mass in adult women and may serve a similar role along with androgen, in adult men. Finally, during periods of bone loss, such as in postmenopause in women and aging in both genders, bone resorption outpaces bone formation and, in some cases, the bone loss is sufficient to cause osteoporosis. It is currently accepted that in postmenopausal females, a deficiency of E results in osteoporosis, whereas in aging males, the deficiency of E and androgens (A) may lead to bone loss (1–3). Ovariectomized (OVX) animals and postmenopausal women experience increased bone turnover, increased bone resorption, and an overall decrease in bone mass. On the other hand, E replacement therapy inhibits this bone loss by inhibiting bone turnover and bone resorption, which prevents the development of osteoporosis (1, 3). Although, the complete mechanisms of action of E in this protection against bone loss are still unclear, new studies are beginning to elucidate the molecular processes involved. The following review summarizes some of the important molecular events in the actions of sex steroids, primarily estrogens, which 0888-8809/99/$3.00/0 Molecular Endocrinology Copyright © 1999 by The Endocrine Society

Morphological changes in periodontal mechanoreceptors of mouse maxillary incisors after the experimental induction of anterior crossbite: a light and electron microscopic observation using immunohistochemistry for PGP 9.5.

Ruffini nerve endings (mechanoreceptors) in the periodontal ligament (PDL) of mouse incisors were examined to elucidate whether experimentally-induced crossbites cause any changes or abnormalities in their morphology and distribution. Anterior guiding planes were attached to the mandibular incisors of 3-week-old C3H/HeSlc mice. At 3 days and 1, 2, 4, 6, and 8 weeks post-attachment of the appliance, the mice were sacrificed by perfusion fixation. Frozen sagittal cryostat sections of the decalcified maxillary incisors were processed for immunohistochemistry of protein gene product 9.5, followed by histochemical determination of tartrate-resistant acid phosphatase activity to reveal sites of alveolar bone resorption. Despite the absence of bone resorption within the lingual PDL of control mice, distinct resorption sites were seen in the respective regions of the experimental animals. Unlike the controls, many Ruffini endings showing vague and swollen contours, with unusually long and pedunculated micro-projections were observed in the affected lingual PDL of the incisors in the experimental animals with short-term anterior crossbite induction. Club-shaped nerve terminations with few, if any, micro-projections were observed in the lingual PDL of experimental animals with long-term induction, as well as in aged control mouse incisors. Differences in the distribution of Ruffini endings were also observed. These results indicate that changing the direction of the force applied to the PDL results in rapid and prolonged changes in the morphology of Ruffini-like mechanoreceptors.

Bone surface morphology reflects local skeletal metabolism.

The metabolic activity of bone cells is faithfully reflected in the surface topography of mineralized bone surfaces, and this can be easily detected by scanning electron microscopy (SEM). Forming bone surfaces exhibit knobby projections which represent foci of mineralization, resorbing surfaces are scalloped, and resting surfaces undergoing neither activity are smooth, as shown by Boyde and Hobdell 25 years ago. These phenomena are illustrated in vivo by tooth eruption, a local activity in alveolar bone where resorption and formation are polarized around an erupting tooth, and osteopetrosis, a metabolic bone disease characterized by a congenital reduction or absence of bone resorption. The ability to analyze bone metabolism over large areas of the skeleton by SEM offers a convenient and powerful microscopic technique to assess regional and global bone cell activity in an era where the investigative focus is increasingly molecular.

Trapezius osteomyocutaneous flap for mandibular reconstruction.

The recent introduction of myocutaneous flaps has kindled the interest in including bone in the flap to reconstruct the anterior mandibular arch and floor of mouth--still one of the most challenging reconstructions in head and neck surgery. The trapezius osteomyocutaneous compound flap has certain advantages over other osteomyocutaneous flaps; the scapula, being a flat bone, receives relatively more blood supply from the periosteum. The absence of bone resorption at more than two years postoperatively has been encouraging, and it has been possible to reconstruct mandible from angle to angle.

The effect of particle size on the osteogenic activity of composite grafts of allogeneic freeze-dried bone and autogenous marrow.

This study was carried out to determine if particle size is a factor to be considered in the evaluation of the osteogenic activity of freeze-dried bone allografts (FDBA) and, if so, whether small particles enhance or inhibit osteogenesis. Small particle FDBA (100-300 microns) plus marrow and large particle FDBA (1000-2000 microns) plus marrow were placed in plexiglass diffusion chambers secured to the femurs of six Rhesus monkeys. Control chambers contained either marrow alone or were left empty. Two animals were given injections of oxytetracycline hydrochloride at 5 and 7 weeks to obtain intravital osseous labeling. All chambers were removed after 8 weeks. Ten chambers were evaluated for new bone formation by fluorescent microscopy. The contents of 15 additional chambers were evaluated by single blind technique for presence or absence of bone resorption and ossification. The results indicated that there was significantly more new bone formation associated with small particle FDBA (100-300 microns) plus autogenous marrow than with large particle FDBA (1000-2000 microns) plus autogenous marrow. In addition, small particle FDBA (100-300 microns) plus autogenous marrow tended to display more resorption than large particle FDBA (1000-2000 microns) plus autogenous marrow. It was concluded that within the parameters of this study, small particles of FDBA enhance osteogenesis. This study also demonstrated that particle size is a variable to be considered when comparing the osteogenic potential of freeze-dried bone allografts.