Areas Of Bone Remodeling Research Articles

Ontogenetic changes in functional matrices and facial bone remodeling

According to the functional matrix hypothesis, changes in size and shape and localization of facial bones during individual ontogeny are influenced by periosteal and capsular matrices. However, the interaction of the functional matrices with the distribution of areas of bone remodeling has not been extensively studied yet. Here we evaluate the changes in the volume of the paranasal sinuses and orbital capsule with age and their association with facial growth arising from bone remodeling patterns of the upper and middle face in a sample of prehistoric human populations from South America. We found an association between capsule size and bone cell proportions, however the trajectories of variation are ambiguous across bones. The frontal and maxillary sinuses had a significant increase from 4.5 up to 14.5 years old, while the orbital capsule had an increase in volume even in adult stages. In turn, the volume of the frontal sinus increases while the bone formation remains relatively stable in subadults and decreases in adults, while the maxilla and the zygomatic bones display a lower proportion of formation when the bones are growing. Our study contributes with information concerning the covariation between bone growth remodeling and the increments of the capsular matrices.

Inflammatory macrophages interrupt osteocyte maturation and mineralization via regulating the Notch signaling pathway

BackgroundIt is well-known that both macrophages and osteocytes are critical regulators of osteogenesis and osteoclastogenesis, yet there is limited understanding of the macrophage-osteocyte interaction, and how their crosstalk could affect bone homeostasis and mineralization. This research therefore aims to investigate the effects of macrophage polarization on osteocyte maturation and mineralization process.MethodsA macrophage-derived conditioned medium based osteocyte culture was set up to investigate the impact of macrophages on osteocyte maturation and terminal mineralization. Surgically induced osteoarthritis (OA) rat model was used to further investigate the macrophage-osteocyte interaction in inflammatory bone remodeling, as well as the involvement of the Notch signaling pathway in the mineralization process.ResultsOur results identified that osteocytes were confined in an immature stage after the M1 macrophage stimulation, showing a more rounded morphology, higher expression of early osteocyte marker E11, and significantly lower expression of mature osteocyte marker DMP1. Immature osteocytes were also found in inflammatory bone remodeling areas, showing altered morphology and mineralized structures similar to those observed under the stimulation of M1 macrophages in vitro, suggesting that M1 macrophages negatively affect osteocyte maturation, leading to abnormal mineralization. The Notch signaling pathway was found to be down regulated in M1 macrophage-stimulated osteocytes as well as osteocytes in inflammatory bone. Overexpression of the Notch signaling pathway in osteocytes showed a significant circumvention on the negative effects from M1 macrophage.ConclusionTaken together, our findings provide valuable insights into the mechanisms involved in abnormal bone mineralization under inflammatory conditions.

Modulation of Dopamine Receptors on Osteoblasts as a Possible Therapeutic Strategy for Inducing Bone Formation in Arthritis.

Rheumatoid arthritis (RA) is associated with systemic osteoporosis, which leads to severe disability and low quality of life. Current therapies target osteoclasts to reduce bone degradation, but more treatment options would be required to promote bone protection by acting directly on osteoblasts (OB). Recently, the local production of dopamine in inflamed joints of RA has been observed. Thus, in this project, we aimed to determine the implication of the neurotransmitter dopamine in the bone formation process in RA. Dopamine receptors (DR) in the human bone tissue of RA or osteoarthritis (OA) patients were examined by immunohistochemistry. DR in isolated human osteoblasts (OB) was analyzed by flow cytometry, and dopamine content was evaluated by ELISA. Osteoclasts (OC) were differentiated from the PBMCs of healthy controls (HC) and RA patients. Isolated cells were treated with specific dopamine agonists. The effect of dopamine on mineralization was evaluated by Alizarin red staining. Cytokine release in supernatants was measured by ELISA. Osteoclastogenesis was evaluated with TRAP staining. OC markers were analyzed via real-time PCR and bone resorption via staining of resorption pits with toluidine blue. All DR were observed in bone tissue, especially in the bone remodeling area. Isolated OB maintained DR expression, which allowed their study in vitro. Isolated OB expressed tyrosine hydroxylase, the rate-limiting enzyme for dopamine production, and contained dopamine. The activation of D2-like DR significantly increased bone mineralization in RA osteoblasts and increased osteoclastogenesis but did not alter the expression of OC markers nor bone resorption. DR were found in the bone remodeling area of human bone tissue and dopamine can be produced by osteoblasts themselves, thus suggesting a local autocrine/paracrine pathway of dopamine in the bone. D2-like DRs are responsible for bone mineralization in osteoblasts from RA patients without an increase in bone resorption, thus suggesting the D2-like DR pathway as a possible future therapeutic target to counteract bone resorption in arthritis.

What's Your Diagnosis? Symptoms: Ear Pain and Chronic Ear Drainage

What's Your Diagnosis? Symptoms: Ear Pain and Chronic Ear Drainage

Immunocytochemical assessment of cell differentiation of podoplanin-positive osteoblasts into osteocytes in murine bone

In this study, we examined the immunolocalization of podoplanin/E11, CD44, actin filaments, and phosphorylated ezrin in the osteoblasts on the verge of differentiating into osteocytes in murine femora and tibiae. When observing under stimulated emission depletion microscopy, unlike podoplanin-negative osteoblasts, podoplanin-positive osteoblasts showed a rearranged assembly of actin filaments along the cell membranes which resembled that of embedded osteocytes. In the metaphysis, i.e., the bone remodeling site, CD44-bearing osteoclasts were either proximal to or in contact with podoplanin-positive osteoblasts, but the podoplanin-positive osteoblasts also localized CD44 on their own cell surface. These podoplanin-positive osteoblasts, which either possessed CD44 on their cell surface or were close to CD44-bearing osteoclasts, showed phosphorylated ezrin-positivity on the cell membranes. Therefore, the CD44/podoplanin interaction on the cell surface may be involved in the osteoblastic differentiation into osteocytes in the metaphyses, via the mediation of podoplanin-driven ezrin phosphorylation and the subsequent reorganized assembly of actin filaments. Consistently, the protein expression of phosphorylated ezrin was increased after CD44 administration in calvarial culture. Conversely, in modeling sites such as the cortical bones, podoplanin-positive osteoblasts were uniformly localized at certain intervals even without contact with CD44-positive bone marrow cells; furthermore, they also exhibited phosphorylated ezrin immunoreactivity along their cell membranes. Taken together, it seems likely that the CD44/podoplanin interaction is involved in osteoblastic differentiation into osteocytes in the bone remodeling area but not in modeling sites.

The Use of ESEM-EDX as an Innovative Tool to Analyze the Mineral Structure of Peri-Implant Human Bone.

This study aimed to investigate the mineralization and chemical composition of the bone–implant interface and peri-implant tissues on human histological samples using an environmental scanning electron microscope as well as energy-dispersive x-ray spectroscopy (ESEM-EDX) as an innovative method. Eight unloaded implants with marginal bone tissue were retrieved after four months from eight patients and were histologically processed and analyzed. Histological samples were observed under optical microscopy (OM) to identify the microarchitecture of the sample and bone morphology. Then, all samples were observed under ESEM-EDX from the coronal to the most apical portion of the implant at 500x magnification. A region of interest with bone tissue of size 750 × 500 microns was selected to correspond to the first coronal and the last apical thread (ROI). EDX microanalysis was used to assess the elemental composition of the bone tissue along the thread interface and the ROI. Atomic percentages of Ca, P, N, and Ti, and the Ca/N, P/N and Ca/P ratios were measured in the ROI. Four major bone mineralization areas were identified based on the different chemical composition and ratios of the ROI. Area 1: A well-defined area with low Ca/N, P/N, and Ca/P was identified as low-density bone. Area 2: A defined area with higher Ca/N, P/N, and Ca/P, identified as new bone tissue, or bone remodeling areas. Area 3: A well-defined area with high Ca/N, /P/N, and Ca/P ratios, identified as bone tissue or bone chips. Area 4: An area with high Ca/N, P/N, and Ca/P ratios, which was identified as mature old cortical bone. Bone Area 2 was the most represented area along the bone–implant interface, while Bone Area 4 was identified only at sites approximately 1.5 mm from the interface. All areas were identified around implant biopsies, creating a mosaic-shaped distribution with well-defined borders. ESEM-EDX in combination with OM allowed to perform a microchemical analysis and offered new important information on the organic and inorganic content of the bone tissue around implants.

Visual evidence of progression and eventual resolution of nasofrontal suture exostosis over 27 months in a gelding

SummaryA 22‐year‐old Thoroughbred gelding presented with a noticeable external firm and nonpainful swelling over the location of the frontal sinuses. Further radiographic investigation of the swelling identified soft tissue facial swelling, new bone formation and a radiolucent line between two areas of bone remodelling. The horse was diagnosed with a nasofrontal suture exostosis. This is a relatively rare disease of the head but is one of the more common reasons for facial swelling. It is reported that these horses are not painful and that the swelling and bony reaction will resolve over 12–18 months with no treatment needed. It is well described in the current literature what the initial presentation should look like; however, there is a void when it comes to demonstration of the clinical course of the disease. This report provides veterinarians and owners with a visual reference to a relatively typical course of disease, where swelling can enlarge over time and still resolve within 2 years.

Abstract # 3101 Dopamine receptor modulation on osteoblast as a potential therapy for arthritis

Background Dysfunction of either osteoclastic bone resorption or osteoblastic bone formation leads to bone disorders such in rheumatoid arthritis (RA). Several therapies target osteoclasts to reduce bone degradation, but treatments able to induce bone formation are still required. Recently, local production of dopamine in inflamed joints of RA has been described. Thus, we aimed to determine the implication of dopamine in the bone remodeling process. Methods Dopamine receptors (DR) presence in human bone tissue of RA or osteoarthritis (OA) patients, as well as in bone tissue of a murine model of arthritis was determined by immunohistochemistry. DR in isolated human osteoblasts (OB) was analyzed by flow cytometry. The influence of dopamine agonists (DA) on human OB was tested in vitro, supplementing the medium with DA for 24 h. Then, supernatants were collected for cytokine quantification. The effect of DA on mineralization was evaluated by including DA for 14 days in differentiation medium. Results All DR were observed in mouse and human bone tissue, especially in the bone-remodeling zone. Moreover, isolated OB maintained the presence of DR. DA stimulation lead to a significantly increase of proinflammatory cytokines, such as IL6 and CCL2. Furthermore, mineralization was altered after stimulation of OB with DA. Conclusion Dopamine receptors are present in the bone remodeling area and their activation on osteoblast seems to have a modulatory effect on bone homeostasis.

SAPHO syndrome of the right temporomandibular bone and joint in a 25-year-old man

SAPHO syndrome is an association of specific bone, joint, and skin lesions. The acronym SAPHO refers to synovitis, acne, palmoplantar pustulosis, hyperostosis, and osteitis. However, not all these clinical manifestations need to be present to establish the diagnosis. It is a rare disease in which genetic predisposition or an autoimmune response to a microorganism in the skin mimicking a normal bone or joint molecular structure has been proposed. We present a 25-year-old man who presented with 2-year history of difficulty in opening the mouth with associated pain in the right jaw. He also developed progressive right hearing impairment and multiple acne-like rashes on his face 10 months prior to presentation. Examination of the right jaw revealed a tender firm immobile swelling in the region of the temporomandibular joint which was slightly warm to touch. CECT revealed cortical bone erosions of the right temporal squama and condyle with diffuse endosteal sclerosis and hyperostosis of the mandibular condyle and ramus. The temporal squama was partially resorbed with areas of bone remodeling. The right temporomandibular joint was also involved in the sclerotic changes with marked narrowing of its joint space. Based on the clinical and radiological features, a diagnosis of SAPHO syndrome was established. It is essential to make such diagnosis in order to avoid unnecessary and futile treatment.

Development of Controllable Simvastatin-Releasing PLGA/β-TCP Composite Microspheres Sintered Scaffolds as Synthetic Bone Substitutes

The bone remodeling process plays an essential part of the calcium homeostatic system and provides a crucial mechanism for adaptation to physical stress, the repair of damaged bone and the removal of old bone. We reported previously that sustainable release of simvastatin (SIM) from poly (lactic-co-glycolic acid) (PLGA) formulations could induce bone formation. The aim of this study was to develop a simvastatin-releasing PLGA/β-TCP composite microspheres (β-SPMs) sintered scaffolds (β-SPMSS) as a synthetic bone substitute, and investigate the influence of the dissolution medium on the drug release capabilities of these device based on a physicochemical model for bone remodeling. X-ray diffraction analysis (XRD) results showed β-TCP and SIM could be encapsulated into the PLGA microspheres. The β-SPMs and the β-SPMSS were able to produce sustained release of SIM for 1 month in simulated body fluid (SBF), whereas these composites released SIM for 10 days in acetate buffer (AB). The release rate of SIM from β-SPMSS in AB was faster than in SBF, indicating that the β-SPMSS could control drug release with bone cells activity response, and could be used as a scaffold in bone remodeling area. These results suggested that the β-SPMSS could release SIM sustainably, with bone cells activity response, and could be used as a scaffold in bone remodeling area.

Histological Features of the Distal Third Metacarpal Bone in Thoroughbred Racehorses, With and Without Lateral Condylar Fractures

A detailed histopathological study of the distal third metacarpal bone of Thoroughbred racehorses was undertaken to characterize lesions observed previously on magnetic resonance imaging (MRI). The bones were selected and grouped on the basis of MRI features. Representative sections in different planes were processed for histopathology. All lesions observed in the articular cartilage (AC) and subchondral bone (SCB) were recorded and graded with a scoring system, based partially on the Osteoarthritis Research Society International grading system. The scoring system included the severity of the lesion. Descriptive statistics and linear mixed effects models were performed. A positive correlation was observed between the severity of histopathological changes in the superficial and deeper osteochondral tissues, and between the number of race starts and AC score. Age was not correlated with AC or SCB score. A moderate variation in AC and SCB scores was observed between the groups; however, there were differences within individual bones. Bones with focal palmar necrosis (FPN) showed significant differences in the histological scoring of the AC compared with bones without FPN. Bones with incomplete fractures or larger areas of bone remodelling showed significant differences in SCB pathology when compared with bones with FPN. Haematoidin was detected in areas with excessive SCB and cancellous bone sclerosis and/or irregular bone density. This finding is suggestive of poor blood perfusion in these areas.

Hydroxyapatite Dome for Bone Neoformation in Rabbit Tibia.

To evaluate supracortical bone neoformation with the use of hydroxyapatite (HA) hollow domes specially manufactured for osteogenesis promotion. Nine New Zealand rabbits were selected and 18 domes were placed, divided into three groups according to the filler: control (blood clot), vitamin complex, and particulate β-tricalcium phosphate (β-TCP). The healing period was 8 weeks, hence fluorescent markers were applied. After healing, the samples were embedded in resin to prepare slides for light and fluorescence microscopic evaluation of the amount of neoformed bone tissue. Energy dispersive spectroscopy was also used for chemical analysis of the material inside the domes. The quality of neoformed bone tissue with active bone remodeling areas was observed. As a filler, β-TCP showed higher bone formation (14.1%), better quality of neoformed bone tissue with organized structures, and an area of mineralized tissue in the dome. Bone neoformation inside the dome filled with blood clot confirmed the osteoconductive property of HA, as indicated by the migration of osteogenic cells from the blood clot, without the action of another biomaterial (mean area of bone formation for blood clot filler = 7.5%). Bone neoformation was not favored in samples filled with vitamin complex because of the difficulty of blood penetration through the material. HA domes performed well as a scaffold for bone neoformation over the cortical bone of rabbits, and this is based on maintenance of good stability and good integration with bone tissue. β-TCP presented higher values of neoformed bone area compared with the blood clot. HA domes have osteoconductive properties, especially when filled with blood clot, because of the migration of osteogenic cells without action of any other biomaterial. In domes filled with vitamin complex, no bone formation was noted because of the absence of resorption.

In vitro study of human osteoblast proliferation and morphology on orthodontic mini-implants.

To evaluate the proliferation and morphology of human osteoblasts cultured on two brands of mini-implants after 24, 48, and 72 hours, in addition to the chemical composition found on their surface. Two brands of mini-implant (Morelli and Neodent) were evaluated; polystyrene was used as a control group (n = 3). Osteoblasts were cultured on the surface of sterilized mini-implants in a CO2 incubator at different time periods (24, 48, and 72 hours). Osteoblast proliferation was quantified by scanning electron microscopy using up to 5000× magnification, and cell morphology was analyzed by a single observer. For the chemical analysis, spectroscopy X-ray fluorescence was used to identify and quantify chemical components on the surface of the mini-implants. Two-way ANOVA showed no significant interaction between the factors studied (P = 0.686). A Tukey test revealed no significant difference in osteoblast proliferation between the mini-implants at all studied periods; however, a difference in cell proliferation was detected between the Neodent and the control group (P = .025). For all groups, time had a direct and positive effect on osteoblast proliferation (P < .001). The significant elements present in both brands of mini-implants were titanium, aluminum, vanadium, and iron. Osteoblast proliferation was present on the mini-implants studied, which increased over time; however, no significant difference between brands was observed. No difference was seen between the mini-implants evaluated in terms of chemical composition. Cell adhesion after 72 hours suggests that areas of bone remodeling can be achieved, thus initiating the process of mini-implant anchorage.

Distribution of BMP6 in the alveolar bone during mouse mandibular molar eruption

Eruption requires synchrony of the tooth with the surrounding tissues, particularly the bone. One important step during eruption is remodelling of the alveolar bone at the base of the tooth and along the roots. Expression of BMP6 was reported to be increased in the basal half of the dental follicle prior to eruption and inhibition of BMP6 affected bone formation at the base of the alveolar crypt. The aim of this study was to further investigate BMP6 protein in relation to tooth eruption and the corresponding bone remodelling using temporospatial correlations of BMP6 localization with morphogenetic events (proliferation, differentiation, apoptosis and bone apposition/resorption), other BMPs (BMP2 and BMP7) and three-dimensional images of tooth–bone development. BMP6 expression pattern was mapped in the mandibular molar teeth and related structures around eruption. Localization of BMP6 dominated in osteoblasts, in regions of bone formation within the alveolar crypt. These findings positively correlated with proliferation at the tooth base region, osteocalcin expression in the osteoblasts/osteocytes and BMP2 and BMP7 presence in the alveolar bone surrounding the tooth. Osteoclast activity and apoptotic elimination in the root region gradually decreased before eruption and totally ceased at eruption stages. Generally, BMP6 positively correlated with BMP2, BMP7 and osteocalcin-positive osteoblasts, and areas of bone remodelling. Moreover, BMP6 was found in the periodontium and cementoblasts. BMP6 expression in the alveolar bone accompanied tooth eruption. Notably, the expression pattern of BMP6 in the bone did not differ around individual molar teeth at the same stage of development. The expression of BMP6 in periodontal ligaments may contribute to interaction between the tooth and bone during the eruption and anchoring process.

Vascularized bone transplant chimerism mediated by vascular endothelial growth factor.

Vascular endothelial growth factor (VEGF) induces angiogenesis and osteogenesis in bone allotransplants. We aim to determine whether bone remodeling in VEGF-treated bone allotransplants results from repopulation with circulation-derived autogenous cells or survival of allogenic transplant-derived cells. Vascularized femoral bone transplants were transplanted from female Dark Agouti rats (DA;RT1(a) ) to male Piebald Viral Glaxo (PVG;RT1(c) ). Arteriovenous bundle implantation and short-term immunosuppression were used to maintain cellular viability. VEGF was encapsulated in biodegradable microspheres and delivered intramedullary in the experimental group (n = 22). In the control group (n = 22), no VEGF was delivered. Rats were sacrificed at 4 or 18 weeks. Laser capture microdissection of bone remodeling areas was performed at the inner and outer cortex. Sex-mismatched genes were quantified with reverse transcription-polymerase chain reaction to determine the amount of male cells to total cells, defined as the relative expression ratio (rER). At 4 weeks, rER was significantly higher at the inner cortex in VEGF-treated transplants as compared to untreated transplants (0.622 ± 0.225 vs. 0.362 ± 0.081, P = 0.043). At 4 weeks, the outer cortex in the control group had a significantly higher rER (P = 0.038), whereas in the VEGF group, the inner cortex had a higher rER (P = 0.015). Over time, in the outer cortex the rER significantly increased to 0.634 ± 0.106 at 18 weeks in VEGF-treated rats (P = 0.049). At 18 weeks, the rER was >0.5 at all cortical areas in both groups. These in vivo findings suggest a chemotactic effect of intramedullary applied VEGF on recipient-derived bone and could imply that more rapid angiogenesis of vascularized allotransplants can be established with microencapsulated VEGF.

Evaluation of the peri-implant bone around parallel-walled dental implants with a condensing thread macrodesign and a self-tapping apex: a 10-year retrospective histological analysis.

The long-term high percentages of survival and success of dental implants reported in the literature are related mainly to new, innovative implant and thread designs, and new implant surfaces that allow to obtain very good primary and secondary stability in most anatomical and clinical situations, even in low quality and quantity of bone, promoting a more rapid osseointegration. The aim of this retrospective study was a histological and histomorphometrical evaluation of the bone response around implants with a parallel-wall configuration, condensing thread macrodesign, and self-tapping apex, retrieved from man for different causes. A total of 10 implants were reported in the present study, and these implants had been retrieved after a loading period comprised between a few weeks to about 8 years. Mineralized newly formed bone was found at the interface of all the implants, in direct contact with the implant surface, with no gaps or connective fibrous tissue. This bone adapted very well to the microirregularities of the implant surface. Areas of bone remodeling were present in some regions of the interface, with many reversal lines. High bone-implant contact percentages were found. In conclusion, both the macrostructure and the microstructure of this specific type of implant could be very helpful in the long-term high survival and success implant percentages.

Human bone reactions around implants with adverse interfacial bone strain over 20 years

It has been accepted that bone damage and subsequent resorption occurs in cases of adverse interfacial bone strain. Fractured implants represents an important opportunity for evaluating the bone response to overstrain. The objective of the study was to analyze the bone morphology and morphometry around retrieved fractured implants in humans. Five fractured implants retrieved after 22.4 (± 2.8) years were used in the present study. The investigation was conducted in a transmitted brightfield and circularly polarized light Microscope. The parameters considered were the total bone area, total bone remodeling area, bone-remodeling rate (BRR), and bone transverse collagen fibers orientation (CFO). For grouped samples, the BRR was 51.9% (± 10) while the transverse CFO was 13.0% (± 9.7). The interthread BRR was 58.1% (± 4.0) for level 1 and 40.4% (± 12.8) for level 2 with a significant decrease in BRR (p = 0.019) as a function of depth along the implant length. Both bone level and bone quality attains stability to a certain level with respect to implant neck fracture following physiologic interaction between mechanical and biological inputs. The BRR significantly decrease as function of threads depth.

Cell lineage in vascularized bone transplantation.

The biology behind vascularized bone allotransplantation remains largely unknown. We aim to study cell traffic between donor and recipient following bone auto-, and allografting. Vascularized femoral transplantation was performed with arteriovenous bundle implantation and short-term immunosuppression. Twenty male Piebald Virol Glaxo (PVG; RT1(c) ) rats received isotransplants from female PVG (RT1(c) ) rats and 22 male PVG rats received allografts from female Dark Agouti rats (DA, RT1(a) ), representing a major histocompatibility mismatch. Both groups were randomly analyzed at 4 or 18 weeks. Bone remodeling areas (inner and outer cortical samples) were labeled and laser capture microdissected. Analysis of sex-mismatch genes by real-time reverse transcription-polymerase chain reaction provided the relative Expression Ratio (rER) of donor (female) to recipient (male) cells. The rER was 0.456 ± 0.266 at 4 weeks and 0.749 ± 0.387 at 18 weeks (p = 0.09) in allotransplants. In isotransplants, the rER was 0.412 ± 0.239 and 0.467 ± 0.252 at 4 and 18 weeks, respectively (p = 0.21). At 4 weeks, the rER at the outer cortical area of isotransplants was significantly lower in isotransplants as compared with allotransplants (0.247 ± 0.181 vs. 0.549 ± 0.184, p = 0.007). Cells in the inner and outer cortical bone remodeling areas in isotransplants were mainly donor derived (rER < 0.5) at 18 weeks, whereas allotransplants contained mainly recipient-derived cells (rER > 0.5) at 18 weeks. Applying novel methodology, we describe detailed cell traffic in vascularized bone transplants, elaborating our comprehension on bone transplantation.

Peri-implant Bone Response Around a Human Hydroxyapatite-Coated Implant Retrieved After a 10-Year Loading Period: A Case Report

This case report presents a histologic and histomorphometric evaluation of the peri-implant tissues of a HA-coated implant retrieved due to peri-implantitis after a 10-year loading period. The implant was retrieved with a trephine and treated to obtain thin ground sections. At low-power magnification mostly compact, mature bone with small marrow spaces could be observed at the interface with the implant. The coating was always present in the areas where bone was detected, the bone was always in close contact with the coating, and there was no detachment between the metal and coating or between the coating and bone. Areas of bone remodeling were demonstrated by the presence of many secondary osteons and reversal lines close to the implant surface. The bone-implant contact percentage was 36.3% ± 1.2%. The percentage of the implant surface covered by the HA coating without bone, where bone may have detached during retrieval, was 32.6% ± 2.8%. This HA-coated implant, continued to demonstrate more than adequate BIC after many years of function and the potential to maintain osseointegration in the long term.

Introducing a Novel Analysis Technique for Osseointegrated Dental Implants Retrieved 29 Years Postsurgery

To investigate osseointegration of oral implants, which were retrieved from a patient after 29 years in situ, we use novel three-dimensional analysis methods and visualization techniques that supplement conventional two-dimensional analysis. The sample processing involved nondecalcification and embedment in resin. Conventional two-dimensional histomorphometrical methods were conducted. Additionally, the quantification was extended to three-dimensional by using synchrotron radiation micro-computed tomography (SRµCT) technique and two relevant visualization methods for the three-dimensional data were introduced. The three-dimensional results involved three-dimensional quantification and visualization of two implant samples with methods beyond state-of-the-art. Traditional two-dimensional histomorphometrical results revealed a mean bone-implant contact (BIC) of about 50%. In most samples, bone area (BA) was lower inside the treads compared with out-folded mirror images, which were confirmed by the three-dimensional quantification. The BIC along four selected regions showed highest percentages in the bottom/valley region and lowest in the thread-peak region. Qualitative observations revealed ongoing bone remodeling areas in all samples. The apical hole demonstrated high osseointegration. The novel techniques including an animation and an out-folding of BIC and BA enabled a simultaneous visualization of the three-dimensional material obtained from SRµCT data. However, the two-dimensional histological sections were needed for qualitative and quantitative evaluation of osseointegration and, thus, both methods are considered equally important.