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PubMedDate not supplied

Bone modeling in the otic capsule of the rat.

Bone modeling determines postuterine gross bone architecture. During growth the shape and proportion of all bones are continuously adapted to function by surface resorption and surface formation. This process is responsible for exchange of most primary endochondral type bone with lamellar endosteal or periosteal bone. By a combination of microradiography, tetracycline fluorescence and osteoid staining of undecalcified material bone modeling in the otic capsule of the rat was studied and compared to well-known modeling patterns in rat long bones. Perilymphatic spaces were found to be enclosed in a layer of primary bone resistant to resorption associated with surface modeling. It is proposed, that this drift barrier is maintained by a control mechanism present inside the perilymphatic space.

Animals↗
PubMed1988

Changes in mineral content, mineral deposition and vascular supply of the mandible after osteotomy.

Circulatory and skeletal damage in the form of a vertical osteotomy of the mandible, proximal to the entry of the inferior alveolar artery and mandibular perforantes, alone or in combination with unilateral or bilateral mucoperiosteal reflections were undertaken on young growing rats. Changes in mineral content and mineral deposition in the hard tissues of the mandibles were studied using microradiography and by labelling with tetracycline and lead acetate. Microangiography was performed to evaluate changes in the vascular supply. Resorption of the compact bone was seen in the central part of the compact bone, in the lower border of the mandible and in the incisal part of the alveolar bone. There was resorption of the cementum and dentin in the molar teeth. Remodelling processes were seen in the compact bone starting from vascular channels and on the surface of the bone trabeculae, ten days after osteotomy. Microangiography revealed that there is a collateral vascular system existing across the midline via the symphysis region, via submucosal tissue, via the mucoperiosteal pedicle to the inferior border of the mandible and via the network of small vessels in the periodontal membrane. It was concluded that the circulation to the peripheral parts of the mandible could in part be kept up by a retrograde flow in the collateral systems when the main circulation had ceased.

Angiography↗
PubMed1988

Bone formation rate in osseointegrated titanium implants. Influence of locally applied haemostasis, peripheral blood, autologous bone marrow and fibrin adhesive system (FAS).

The influence of local application of haemostasis, peripheral blood, autologous bone marrow and Fibrin Adhesive System (FAS) on bone formation rate in osseointegrated titanium implants, were studied. The Bone Harvest Chamber (BHC) implant utilized has a penetrating canal, enabling osseous ingrowth in situ. After integration of one implant into the cortex of the proximal tibial metaphysis of a rabbit, newly formed bone was harvested in repetitive three-week periods. The specimens were quantified by microradiography-videodensitometry and subjected to further histological examination. The amounts of bone formed in two equally treated chambers in the same animal were compared. It was concluded, that the conditions for bone regeneration in an osseointegrated titanium implant are excellent, minimally influenced by locally applied haemostasis, peripheral blood and autologous bone marrow. FAS pretreatment on the other hand was found to impair bone formation.

Animals↗
PubMed1976

Reprecipitation phenomena arising during the preparation of demineralised sections. III Scanning electron microscopic examinations of secondary calcium phosphate deposits.

Sections of teeth partly demineralized in 10% formic acid were examined by X-ray diffraction, microradiography and scanning electron microscopy. In the undemineralized circumpulpal dentin, the tubules were empty, lying in a matrix containing hydroxyapatite. In the "plume" areas of remineralisation, the tubules were filled with mineral deposits. X-ray diffraction revealed the presence of brushite and monetite in these areas. In the outer layers of dentin the tubules were empty, lying in a matrix containing some residual hydroxyapatite. These findings confirmed that the remineralisation process occurred within the dentinal tubules.

Calcium Phosphates↗
PubMed1977

Trabecular architecture of the knee joint.

The trabecular architecture of the human knee joint was studied three dimensionally by microradiography. The trabecular arrangement of the two condylar wheels of the femur was divided into five types. The trabeculae are so arranged that both condyles are able to adjust to mechanical compression and rotary movement. In the tibia, each trabecular arrangement has a different mechanical function. The epiphyseal line can be considered a laminated structure interposed between the compressive forces acting from the articular surface and the forces supporting the architecture of the metaphysis. The mechanics and kinematics of the traecular architecture are discussed.

Adult↗
PubMed2003

Relationship between the fluoride concentration of the fluoride-releasing elastomers and the acquired acid resistance of human enamel in vitro.

The objective of the study was to evaluate the relationship between the fluoride concentration of the fluoride-releasing elastomers and the acquired acid resistance of human enamel. Four kinds of fluoride concentration of the experimental fluoride-releasing elastomers were 1.25, 2.5, 3.75 and 5.0 wt%. An enamel block was cut into two smaller enamel blocks, one of which was set with an elastomer, the other as a control not set with elastomer. A plastic block that had the same shape as the small enamel block was also set with elastomer. Fluoride release and acid resistance tests were carried out. The mineral loss of the demineralized enamel was measured by microradiography. The results showed that the fluoride-releasing ability significantly increased with the increase of fluoride concentration in the elastomer (p < 0.05). The acid resistance of the enamel appeared to be enhanced greatly, however, its change was not proportional to the fluoride concentration in the elastomers.

Absorption↗
PubMed2005

Formation of inhibition layers with a newly developed fluoride-releasing all-in-one adhesive.

This study evaluated the capability of a novel fluoride-releasing, all-in-one adhesive system on forming inhibition layer (radio-opaque layer) as compared with other adhesive systems. Dentin surface was treated with Imperva bond (IB), FL-BOND (FB), Reactmer bond (RE), or FL-BOND S-1 (FS) (which is a novel system). Untreated specimens were categorized as nonbonding group (NB). After storing for 10 days in de-ionized water, the specimens were cut into halves perpendicularly to the pulp chamber and immersed in a buffered demineralizing solution for four days. Longitudinal sections were cut and microradiographed. The width of inhibition layers adjacent to the adhesive surface--at a depth of 50 microm under the demineralization surface--was analyzed. Microradiography revealed distinct inhibition layers adjacent to the experimental surfaces of FB, RE, and FS. No inhibition layers were observed in NB and IB. In particular, the width of the inhibition layer of FS (12.5 microm) was significantly greater than those of FB and RE. These results indicated that a newly developed all-in-one adhesive system, FS, may have a superior ability of forming inhibition layers adjacent to cavity walls, and that it may also protect dentin against further demineralization in case of secondary marginal caries.

Adhesives↗
PubMed1999

Inhibitory effects of combined treatment with vitamin K and D on bone loss of ovariectomized rats: a microradiographic study.

This study was designed to assess the effect of vitamin K and D supplementation on ovariectomy-induced bone loss. Female Sprague-Dawley rats aged 8-9 months were ovariectomized (OVX) or sham operated and divided into five experimental groups: (1) sham operation, (2) ovariectomy (OVX), (3) OVX plus vitamin K supplementation, (4) OVX plus vitamin D supplementation, (5) OVX plus vitamin K and vitamin D supplementation. The trabecular bone area was estimated by bone histomorphometry by microradiography and histological examination. Bone loss in OVX plus vitamin K and vitamin D group was significantly reduced at both 7 and 14 weeks compared with the OVX group. No significant bone loss in OVX plus vitamin K or OVX plus vitamin D groups was found. Similar effect of vitamin K and D supplementation on ovariectomy-induced bone loss was recognized in histological examination. Our findings indicate that vitamin K and D may have synergistic effects on reducing bone loss. This is a valuable information for the treatment of bone loss in postmenopausal women with osteoporosis.

Animals↗
PubMed1975

[Morphogenesis and structure of teleost teeth (Salmo fario L.)].

Tooth formation has been studied in the fry and adult trout (Salmo fario L.) in order to describe their structure and investigate the links between histogenetic and architectural features. Odontoblasts show typical polarized kinetics during their activity; they shrink back from the tooth wall they have elaborated, without leaving any cytoplasmic process (Tomes' fibres); so the dentine in a characteristic way lacks any cellular or canalicular inclusion, at any stage of its development. The tooth as a whole grows from an apical to basal direction; its organic matrix is formed of coarse fibres from the pulp, and fine collagenous fibres formed by the odontoblastic layer. These various fibrillar systems assume definite orientations. Mineralization was studied by fluorescent markers and microradiography. The external apical part of the tooth is hypermineralized, but its structure and pattern of deposition would make it closer to a dentinal differentiation (enameloid) than to an ectodermal enamel. The ameloblasts of the inner epithelium are high, very polarized and active cells, but their participation in tooth tissue formation has not been definitely demonstrated.

Ameloblasts↗
PubMed1975

Physical and biological aspects of repair in dog cortical-bone transplants.

The amount of repair and the time required to accomplish repair of four-centimeter segmental fibular transplants in twenty-one male adult dogs were determined at from two to forty-eight weeks after transplantation by torsional stress testing, microradiography, and tetracycline labeling. The transplanted cortical bone was greatly weakened at from six weeks to six months but was nearly normal at one year. The strength of the transplant appeared to be related to the amount of porosity of the matrix rather than to the quality or completeness of biological repair. Spatially, the repair was ordered rather than random. The initial resorption caused increased porosity which was slowly offset by apposition of new bone, a process which was dependent on general skeletal metabolic activity. Although physical strength was near normal at forty-eight weeks, only 60 per cent of the transplants had been remodeled.

Animals↗
PubMed2001

Lens growth and protein density in the rat lens after in vivo exposure to ultraviolet radiation.

PURPOSE: To investigate lens growth after different doses of ultraviolet radiation (UVR) and to investigate the long-term effect of a near-threshold UVR dose on the refractive index distribution in the lens. METHODS: Sprague-Dawley rats received UVR (lambda(MAX) = 300 nm) unilaterally during a 15-minute period. The exposure dose ranged from 0.1 to 20 kJ/m(2), and the rats were kept for up to 32 weeks after exposure. Intact lenses were photographed and lens wet and dry masses were measured. The protein density was estimated by quantitative microradiography. Freeze-dried lens sections were used for contact x-ray photographs. From the transmission of the microradiographs, protein density and refractive index profiles were calculated along the lens radius with a resolution of 2.5 microm. RESULTS: Lens dry mass in exposed eyes was lower than in nonexposed eyes at one week after exposure. Lens water content was decreased after low UVR doses but increased after high doses. The difference between exposed and nonexposed lenses in dry mass and water content increased with time after exposure. No significant difference was found for the mean protein density in exposed and nonexposed lenses. The protein density increased linearly in the lens cortex, from a minimum in the superficial cortex of 0.26 g/cm(3) to a maximum in the deep cortex of 0.81 g/cm(3). This corresponded to a refractive index of 1.38 and 1.48, respectively. CONCLUSIONS: Lenses exposed to UVR grew more slowly than their nonexposed contralaterals. This growth inhibition was dose dependent. Near-threshold doses led to decreased water content in the lens whereas high doses led to swelling. Six months after near-threshold UVR exposure, no global change of the refractive index was found. However, local variations of the refractive index caused a subtle cortical light scattering.

Animals↗
PubMedDate not supplied

Effect of sealant viscosity on the penetration of resin into etched human enamel.

This study was designed to investigate the relationship between the etched depth, penetration of sealants and marginal seal. Sixty unerupted lower first premolars extracted from patients for orthodontic reasons were thoroughly cleaned and stored in an antiseptic Ringer's solution at 4 degrees C. A "window" on the occlusal of 15 of the premolars, including both mesial and distal pits, was developed by painting nail varnish around the border of the occlusal surfaces. Etching was then done with 35% phosphoric acid for 60 seconds to all 60 premolars. Five of the "window" teeth were evaluated by microradiography to determine the etched depth of the superficial and subsurface enamel. Five were prepared for SEM analysis to observe the change of the superficial etched enamel surface. Another five "window" teeth were embedded in epoxy resin and sectioned parallel to the long axis of the tooth through the fissures in order to observe the subsurface depth of the etch by SEM analysis. The other 45 teeth were divided into three groups of 15 teeth each. Fissures of each group of teeth were sealed using Prisma-Shield (LD Caulk), Concise White Sealant (3M Dental Products) or Teethmate A (Kuraray) sealants and stored in water (37 degrees C) for 24 hours. They were then sectioned and demineralized before being examined by a scanning electron microscope. Photographs of secondary electron image (SEI) were done to gradate the resin-infiltrated enamel and resin tags for these sealants. After SEM observation, the 15 samples of each applied sealant were polished to a high gloss again and placed in a silver nitrate solution for 24 hours before being examined under the SEM equipped with a back-scatter electron detector. Data were then analyzed using the Welch and Student t-tests. Results showed that fissured enamel of unerupted human lower first premolars became porous after etching with 35% phosphoric acid. The low viscosity sealant Teethmate A (approximately 260 mPa.s), penetrated fully and formed a resin-infiltrated layer in enamel beyond the etched depth. However, the high viscosity sealants (Prisma-Shield and Concise White Sealant) did not penetrate enough to ensure that the acid-etched enamel was infiltrated sufficiently by the sealant to insure good marginal seals.

Acid Etching, Dental↗
PubMed1975

On the relationship between tetracycline and the incremental lines in dentine.

Ground and decalcified sections of human, goat and pig teeth were examined using polarized and ultraviolet fluorescence microscopy, microradiography and electron microscopy. The experimental animals were given doses of tetracycline within the range 3-150 mg/kg. After the low doses there was no evidence of any disturbance of mineralization or of structural organization in either the goat or the pig. After the higher doses, however, the tetracycline lines usually corresponded with a disturbance of structural organization and often with a disturbance of mineralization as well. In the human cases, the tetracycline lines sometimes corresponded with a disturbance of mineralization or of structural organization. However, our evidence suggests that the disturbances in the structure or mineralization of the dentine in the human subjects were not caused by the tetracycline. It was concluded that, provided the dose is kept low (3-31 mg/kg) tetracycline can be used as a reliable non-toxic marker in growth studies and is also used in the study of mineral deposition.

Animals↗
PubMed1975

Ligament insertions into the human lumbar vertebral body.

The insertion of the annulus fibrosus and of the perivertebral ligaments into the lumbar vertebral body is studied by histology and microradiography, in post-mortem human material from 0 to 34 years of age. The annulus lamellosus is attached to the edge ring, whose origin is endochondral, and ends in a calcified cartilage. The perivertebral ligaments are fixed to the cortex, that derives from those ligaments; they join the vertebral body via bundle bone.

Adolescent↗
PubMedDate not supplied

In vitro evaluation of fluoride-releasing restorative materials for sealing the root canals of overdenture abutments.

PURPOSE: The purpose of this study was to evaluate the ability of newer fluoride-releasing restorative materials to protect the root surface from acid attack. MATERIALS AND METHODS: The materials used were glass-ionomer cement (GIC), resin-modified glass-ionomer cement (RM-GIC), and a compomer (Comp). A composite resin (CR) was used as the control. The restored teeth were stored in deionized, distilled water for 14 days and subjected to 300 thermocycles (55 degrees C and 5 degrees C). The teeth were cycled in a demineralizing solution (pH 5.0 or 4.0) for 6 hours and in a remineralizing solution (pH 7.0) for 17 hours for 10 days. The depths of lesions created by acid challenge were measured at the interface of the tooth and the restorative material and then at a distance of 50, 100, and 300 microns from the tooth-restoration margin using polarized light microscopy and contact microradiography. RESULTS: At pH 4.0, there was significant difference in the depth at the interface between the tooth and the restorative material (P < .001). The GIC and RM-GIC were protective, and the lesion depths were significantly shallower than for Comp or CR. The protective effect varied depending on the distance from the interface of the tooth and the restorative material. At pH 5.0, the GIC and RM-GIC had no lesions at the interface, while the Comp and the CR had lesions (P < .001). CONCLUSION: Fluoride-releasing glass-ionomer cement seems to be an appropriate material to seal the root canals of overdenture abutments, because it has an inhibiting effect on demineralization at the cavity wall in vitro.

Aged↗
PubMedDate not supplied

Bone conditioning to enhance implant osseointegration: an experimental study in pigs.

PURPOSE: Osseointegration of implants depends on time and the local bone conditions regarding quality and quantity. This led to the bone classification by Lekholm and Zarb. The aim of the present study was to enhance osseointegration of implants through conditioning of the bone bed and to compare in this context the efficacy of bone condensation, an osteoinductive collagen (Colloss), and platelet-rich plasma (PRP). MATERIALS AND METHODS: Porcine frontal skull bone was used for the preparation of Identical-size implant beds. Before placement of the implants (Ankylos, 3.5 x 4 mm), the implant beds were untreated (control) or conditioned with condensation, Colloss, or PRP. The animals were sacrificed after 2, 4, and 8 weeks. The specimens were then compared and analyzed by microradiography, and statistical analysis was performed using the Wilcoxon signed rank test. RESULTS: At the early observation times, significant effects on the sites of topical bone conditioning in comparison to the control group could be seen regarding the implant-bone interface (2 weeks: control 31%, Colloss 60%, condensation 73%, PRP 47%; 4 weeks: control 39%, Colloss 51%, condensation 40%, PRP 42%) and peri-implant bone density (2 weeks: control 31%, Colloss 48%, condensation 59%, PRP 39%; 4 weeks: control 47%, Colloss 53%, condensation 41%, PRP 50%). A leveling of the results between groups was found at 8 weeks (implant-bone interface: control 51%, Colloss 58%, condensation 55%, PRP 62%; peri-implant bone density: control 50%, Colloss 55%, condensation 51%, PRP 51%). DISCUSSION: Overall, bone condensation and Colloss apparently influenced bone formation process from the onset, but over the entire 8-week healing period, differences in bone formation were not significant CONCLUSION: It can be stated that, in the initial healing phase, an effect of topical bone conditioning may be achieved by the different described methods.

Animals↗
PubMed1992

[Periprosthetic membrane island flap with axial pedicle. Experimental study on the effect of time and expanded volume].

This experimental study, conducted in the rat, assessed the influence the volume of expansion and time after expansion on the vascularised area of a periprosthetic membrane axial pedicle (epigastric) expanded island flap. 15 Wistar rats were operated on and divided into 3 series according to the expanded volume (20 cc, 40 cc) and the time (1, 2 months). The membrane vascularisation derived from the pedicle was study by microradiography based on geometric parameters. At equal times, the volume essentially increased the length of the pedicle and had little effect on the vascularised area. For equal expanded volumes, increasing latency time increased the length and especially the width of opacification derived from the pedicle. The periprosthetic membrane axial pedicle island flap is an experimental entity whose vascularised area, obtained after a certain amount of expansion, is influenced more by time than by the volume of expansion.

Animals↗
PubMed2004

[Research methods in dentistry. 6. In vivo and in vitro methods for studying caries lesion progression].

This paper describes some of the most used methods for caries lesion progression measurement in in vivo and in vitro research. Clinical measurements are usually limited to visual inspection. Currently available scoring systems and statistical analyses, making use of changes in lesion stage, have the potential to make caries clinical trials more efficient. A method for light fluorescence measurements is capable of measuring small changes in mineral loss for early lesions, In the laboratory, mainly destructive methods are used. The most widely accepted gold standard at the moment is transversal microradiography (TMR). Other microradiographical methods are described, that allow for longitudinal measurements.

Dental Caries↗