The relationship between general osteoporosis of the organism and periodontal diseases.
(25/97)
Osteoporosis and periodontitis are very prevalent diseases and are most common in middle-aged and elderly women. These diseases are related as both damage bone tissue and share common risk factors. Discussions about the association between these two bone-damaging diseases began in 1960. A hypothesis was raised that systemic imbalance in bone resorption and deposition might manifest itself in the alveolar bone earlier than in other bones. When analyzing systemic and local changes in bone density, a number of issues were investigated and attempted to answer the question of whether dental osteopenia is a local manifestation of osteoporosis having similar etiology and risk factors, or it is an independent process depending primarily on factors that cause periodontal disease. Histomorphometric and microradiographic studies showed that increasing porosity of the cortical layer in mandible resulted in the decrease in bone mass. Bone strength is best expressed through bone mineral density, and it can be called a diagnostic criterion of osteoporosis. The examination of bone mineral density is called densitometry and may be performed using dual-energy x-ray absorptiometry. Orthopantomography is a method that is widely applied in odontological practice and is also informative in determining the bone density of the mandible. It can be applied when performing orthopantomographic and vertical linear measurements, as well as in determining indices in the studies of osteoporotic changes. Since many patients attend odontological clinics, nearly all of them undergo orthopantomography. This is a good possibility to investigate osteoporotic changes in the mandible, to select individuals for further studies, and to ensure clinical benefit and good treatment results. (+info)
A quantitative histological study of the vascularity of the rotator cuff tendon.
(26/97)
Previous perfusion studies of the rotator cuff have demonstrated an area of hypovascularity in the distal part of the supraspinatus tendon. This has been implicated in the pathogenesis of its rupture. We performed a quantitative histological analysis of the vascularity of the tendons of supraspinatus and infraspinatus. Vessel number, size and the percentage of the tendon occupied by vessels were measured at 5 mm intervals from the humeral insertions to the muscle bellies. Both tendons were hypovascular in their distal 15 mm. No significant difference was demonstrated between the vascularity of supraspinatus and infraspinatus. We conclude that factors other than vascularity are important in the pathogenesis of supraspinatus rupture. (+info)
Porosity of human mandibular condylar bone.
(27/97)
Quantification of porosity and degree of mineralization of bone facilitates a better understanding of the possible effects of adaptive bone remodelling and the possible consequences for its mechanical properties. The present study set out first to give a three-dimensional description of the cortical canalicular network in the human mandibular condyle, in order to obtain more information about the principal directions of stresses and strains during loading. Our second aim was to determine whether the amount of remodelling was larger in the trabecular bone than in cortical bone of the condyle and to establish whether the variation in the amount of remodelling was related to the surface area of the cortical canals and trabeculae. We hypothesized that there were differences in porosity and orientation of cortical canals between various cortical regions. In addition, as greater cortical and trabecular porosities are likely to coincide with a greater surface area of cortical canals and trabeculae available for osteoblastic and osteoclastic activity, we hypothesized that this surface area would be inversely proportional to the degree of mineralization of cortical and trabecular bone, respectively. Micro-computed tomography was used to quantify porosity and mineralization in cortical and trabecular bone of ten human mandibular condyles. The cortical canals in the subchondral cortex of the condyle were orientated in the mediolateral direction, and in the anterior and posterior cortex in the superoinferior direction. Cortical porosity (average 3.5%) did not differ significantly between the cortical regions. It correlated significantly with the diameter and number of cortical canals, but not with cortical degree of mineralization. In trabecular bone (average porosity 79.3%) there was a significant negative correlation between surface area of the trabeculae and degree of mineralization; such a correlation was not found between the surface area of the cortical canals and the degree of mineralization of cortical bone. No relationship between trabecular and cortical porosity, nor between trabecular degree of mineralization and cortical degree of mineralization was found, suggesting that adaptive remodelling is independent and different between trabecular and cortical bone. We conclude (1) that the principal directions of stresses and strains are presumably directed mediolaterally in the subchondral cortex and superoinferiorly in the anterior and posterior cortex, (2) that the amount of remodelling is larger in the trabecular than in the cortical bone of the mandibular condyle; in trabecular bone variation in the amount of remodelling is related to the available surface area of the trabeculae. (+info)
Absence of mechanical loading in utero influences bone mass and architecture but not innervation in Myod-Myf5-deficient mice.
(28/97)
Although the responses of bone to increased loading or exercise have been studied in detail, our understanding of the effects of decreased usage of the skeleton has been limited by the scarcity of suitable models. Such models should ideally not affect bone innervation, which appears to be a mediator of physiological responses of bone to unloading. MyoD-/-/Myf5-/- (dd/ff) mice lack skeletal muscle, so the fetuses develop without any active movement in utero and die soon after birth. We used micro-compter tomography and histology to analyse their bone development and structure during endochondral ossification in parallel with the establishment of bone innervation. Long bones from mutant mice were found to be profoundly different from controls, with shorter mineralized zones and less mineralization. They lacked many characteristics of adult bones - curvatures, changes in shaft diameter and traction epiphyses where muscles originate or insert - that were evident in the controls. Histologically, dd/ff mice showed the same degree of endochondral development as wild-type animals, but presented many more osteoclasts in the newly layed bone. Innervation and the expression pattern of semaphorin-3A signalling molecules were not disturbed in the mutants. Overall, we have found no evidence for a major defect of development in dd/ff mice, and specifically no alteration or delay in endochondral ossification and bone innervation. The altered morphological features of dd/ff mice and the increased bone resorption show the role of muscle activity in bone shaping and the consequences of bone unloading. (+info)
Development of new software as a convenient analysis method for dental microradiography.
(29/97)
To the end of developing a convenient research tool to calculate the mineralization status of teeth in detail, a new program was developed using Visual Basic for Applications combined with Microsoft Excel 2004. To demonstrate the usefulness of this program, it was used to analyze tooth enamel mineralization after acid exposure. Transverse microradiography images (TMR) of specimens were digitalized with a charge-coupled device camera with a microscope (CCD camera) and a digital film scanner (FS). Subsequently, the mineral content profile of each specimen after de- and remineralization studies were calculated using the Angmar's formula. The newly developed program was applied to calculating the mineral loss (DeltaZ), lesion depth (Ld), surface zone depth (SZd), and lesion body depth (LBd) of tooth specimens. In addition, the outer surface zone (OSZ), inner lesion body (ILB), and sandwich area (SA) between OSZ and ILB- which together constituted DeltaZ - were calculated by the newly developed program. Data obtained with the newly developed program were in good agreement for both CCD camera and FS, indicating that the program was reliable for tooth enamel mineralization research studies. (+info)
Study of subchondral bone adaptations in a rodent surgical model of OA using in vivo micro-computed tomography.
(30/97)
OBJECTIVE: To non-invasively investigate the changes to epiphyseal bone occurring in a longitudinal pre-clinical model of osteoarthritis (OA) using in vivo micro-computed tomography (micro-CT). DESIGN: In vivo micro-CT images were acquired using a bench-top micro-CT scanner, which produces three-dimensional data with isotropic voxel spacing of 0.046 mm. Male rodents were scanned prior to surgical destabilization, consisting of anterior cruciate ligament transection and partial medial menisectomy (ACLX). Subsequent scans were performed every 4 weeks post-ACLX, for up to 5 months. Volumetric bone mineral density (vBMD) was measured in specific, anatomically segmented regions within each image. The ACLX rodent data were compared with the contralateral non-operated hind limb of the same animal, as well as a sham-operated group (SHAM) of animals, for each time point. End-point histology compared changes to cartilage and bone between the ACLX and control animals. RESULTS: The micro-CT protocol produced sufficient spatial resolution and signal-to-noise ratio (SNR=19) to quantify subchondral bone pathology, with an acceptable entrance exposure to radiation (0.36 Gy). Significantly lower vBMD was measured in the ACLX group, vs SHAM rodents, at 1, 4, and 5 months post-surgery (P<0.05). Qualitative observations of ACLX joints revealed significant loss of cartilage, subchondral bone cysts, and calcification of tendon similar to changes found in humans. CONCLUSIONS: This study demonstrates in vivo micro-CT as an effective method for investigating the development of rodent knee OA longitudinally. This method can be applied, in future pre-clinical trials, to non-destructively monitor the efficacy of pharmacological interventions. (+info)
Structure and function of the microbial community in a full-scale enhanced biological phosphorus removal plant.
(31/97)
The structure and function of the microbial community in a full-scale enhanced biological phosphorus removal wastewater treatment plant (WWTP; Skagen) were investigated using the full-cycle rRNA approach, combined with ecophysiological studies. A total of 87 16S rRNA gene sequences were retrieved, and 78 operational taxonomic units were identified. Novel oligonucleotide probes were designed, and quantitative fluorescence in situ hybridization revealed that six hitherto undescribed probe-defined groups within the phylum Bacteroidetes (two groups), and classes Betaproteobacteria (two groups) and Gammaproteobacteria (two groups), were relatively abundant (>1% of total biovolume) in the Skagen WWTP and 10 other full-scale WWTPs with biological P removal. The most abundant was a group of rod-shaped Bacteroidetes attached to filamentous bacteria, which is distantly related to the genus Haliscomenobacter of the family Saprospiraceae, and comprised 9-19% of the bacterial biovolume in all the WWTPs investigated. The other five probe-defined groups were found in all WWTPs, but they were less abundant (1-6%). Two groups had a glycogen-accumulating phenotype and one Dechloromonas-related group had a polyphosphate-accumulating phenotype, and they were potentially all involved in denitrification. In total, about 81% of all bacteria hybridizing with the general eubacterial probe were detected in the Skagen WWTP by using clone- or group-specific probes, indicating that most members of the microbial community had been identified. (+info)
In vivo visualization of the water-refilling process in xylem vessels using X-ray micro-imaging.
(32/97)
BACKGROUND AND AIMS: Xylem vessels containing gases (embolized) must be refilled with water if they are to resume transport of water through the plant, so refilling is of great importance for the maintenance of water balance in plants. However, the refilling process is poorly understood because of inadequate examination methods. Simultaneous measurements of plant anatomy and vessel refilling are essential to elucidate the mechanisms involved. In the present work, a new technique based on phase-contrast X-ray imaging is presented that visualizes, in vivo and in real time, both xylem anatomy and refilling of embolized vessels. METHODS: With the synchrotron X-ray micro-imaging technique, the refilling of xylem vessels of leaves and a stem of Phyllostachys bambusoides with water is demonstrated under different conditions. The technique employs phase contrast imaging of X-ray beams, which are transformed into visible light and are photographed by a charge coupled device camera. X-ray images were captured consecutively at every 0.5 s with an exposure time of 10 ms. KEY RESULTS: The interface (meniscus) between the water and gas phases in refilling the xylem vessels is displayed. During refilling, the rising menisci in embolized vessels showed repetitive flow, i.e. they temporarily stopped at the end walls of the vessel elements while gas bubbles were removed. The meniscus then passed through the end wall at a faster rate than the speed of flow in the main vessels. In the light, the speed of refilling in a specific vessel was slower than that in the dark, but this rate increased again after repeated periods in darkness. CONCLUSIONS: Real-time, non-destructive X-ray micro-imaging is an important, useful and novel technique to study the relationship between xylem structure and the refilling of embolized vessels in intact plants. It provides new insight into understanding the mechanisms of water transport and the refilling of embolized vessels, which are not understood well. (+info)