oxytetracycline--anhydrous and fluorexon

Suture expansion stimulates bone growth to correct craniofacial deficiencies but has a high potential of treatment relapse. The objective of this study was to investigate whether there is a dose-dependent relationship between the recombinant human bone morphogenetic protein-2 (rhBMP-2) and bone formation during suture expansion.. Fifty 6-week-old male New Zealand white rabbits were randomly assigned to 5 groups to receive 0 (control), 0.01, 0.025, 0.1, or 0.4 mg/mL of rhBMP-2 delivered by absorbable collagen sponge placed over the interfrontal suture. The suture was expanded for 33 days by 200 g of constant force via a spring anchored with 2 miniscrew implants. Distance of suture expansion, suture volume, and cross-sectional area after expansion were measured using radiographs with bone markers and microcomputed tomography. Suture widths and mineralization appositional rates were calculated based on the widths between bone labels under an epifluorescent microscope. Software (Multilevel Win 2.0; University of Bristol, Bristol, United Kingdom) was used to model distance of suture expansion over time as polynomials to compare group differences. Wilcoxon signed rank tests were performed to compare the suture volume and cross-sectional area, mineral apposition rate, and suture width between groups. The significance level was set at P = 0.05.. Whereas the sutures were expanded in all groups, sutures were expanded by significantly greater amounts in the control and the 0.01 mg/mL groups without fusing the sutures than in the 0.025, 0.1, and 0.4 mg/mL groups with fusing sutures. Compared with the controls, the 0.01 mg/mL group showed significantly lower suture volumes, cross-sectional areas, and suture widths after expansion. The mineral apposition rate was significantly higher in the 0.01 mg/mL group than in the controls from days 10 to 30.. The 0.01 mg/mL dose of rhBMP-2 delivered by absorbable collagen sponge can stimulate bone formation at the bony edges of the suture during suture expansion; however, higher concentrations cause suture fusion. With an appropriate concentration, rhBMP-2 might facilitate suture expansion for clinical uses.

Topics: Alloys; Anatomy, Cross-Sectional; Animals; Bone Morphogenetic Protein 2; Bone Screws; Bone Wires; Calcification, Physiologic; Cranial Sutures; Dose-Response Relationship, Drug; Drug Carriers; Fiducial Markers; Fluoresceins; Fluorescent Dyes; Frontal Bone; Gelatin Sponge, Absorbable; Imaging, Three-Dimensional; Male; Microscopy, Fluorescence; Nickel; Osteogenesis; Osteogenesis, Distraction; Oxytetracycline; Rabbits; Random Allocation; Recombinant Proteins; Stress, Mechanical; Tantalum; Titanium; Transforming Growth Factor beta; X-Ray Microtomography

Vertical bone regeneration of severe atrophic alveolar ridges remains a challenging procedure in implant dentistry.. The aim of this study, accordingly, is to use a rabbit vertical guided bone regeneration model to evaluate whether using a collagen membrane (CM) loaded with small doses of recombinant human bone morphogenetic protein-2 with collagen-binding domain (rhBMP-2/CBD) would enhance two-way vertical bone regeneration. In each of eight rabbits, four titanium cylinders were screwed in perforated slits made into the external cortical bones of the calvaria. The following four treatment modalities were randomly allocated: 1) cylinders filled with mineralized bone matrix and covered with CM/rhBMP-2/CBD; 2) cylinders filled with mineralized bone matrix and covered with CM/rhBMP-2; 3) cylinders filled with mineralized bone matrix and covered with CM alone; or 4) cylinders filled with mineralized bone matrix without a membrane cover.. After 6 weeks, the new bones were examined by histologic analysis. Slender new bone trabeculae were observed in the superficial layer of the titanium cylinders covered with CM/rhBMP-2/CBD, and higher degrees of bone were observed in this group compared with the other three groups. The average area fraction of newly formed bone was significantly more in the CM/rhBMP-2/CBD group compared with the CM/rhBMP-2, CM, or the no membrane control groups (all P <0.01).. The present study demonstrates that CMs loaded with small doses of rhBMP-2/CBD induce new bone formation not only from the surface of the native bone, but also from the superficial structures. The augmented new bone, therefore, is improved in both quantity and quality.

Topics: Animals; Bone Matrix; Bone Morphogenetic Protein 2; Bone Regeneration; Bone Substitutes; Collagen; Female; Fluoresceins; Fluorescent Dyes; Frontal Bone; Guided Tissue Regeneration; Humans; Image Processing, Computer-Assisted; Membranes, Artificial; Osteoblasts; Osteogenesis; Oxytetracycline; Parietal Bone; Peptide Fragments; Rabbits; Random Allocation; Recombinant Proteins; Sialoglycoproteins; Transforming Growth Factor beta

The purpose of this study was to establish the causal relationships between expansion force magnitudes, sutural separation, and sutural bone formation.. Thirty-seven 6-week-old rabbits were randomly assigned to 4 force groups (0, 50, 100, or 200 g). Constant forces were delivered for 42 days by nickel-titanium open-coil springs to miniscrew implants (MSIs) placed in the frontal bone on both sides of the midsagittal suture. Inter-MSI and bone marker widths were measured biweekly to quantify sutural separation and MSI movements. Sutural bone formation was quantified based on the incorporation of fluorescent bone labels administered at days 18, 28, and 38.. Nine of 74 MSIs failed between days 0 and 14, including 4 in the controls and 5 in the 50-g group. A decelerating curvilinear pattern of sutural separation was evident in the 50-g, 100-g, 200-g groups. Bone markers showed that sutural widths increased by 0.6, 3.2, 5.1, and 6.2 mm in the control, 50-g, 100-g, and 200-g groups, respectively. Except for the 200-g group, significantly greater amounts of bone formation were observed between days 18 and 28 than between days 28 and 38. Sutural bone formation also increased with increasing forces up to 100 g; there was no difference between the 100-g and the 200-g groups. Sutural separation explained 71% and 53% of the variations in bone formation between days 18 and 28 and days 28 and 38, respectively.. Within the limits of this study, sutural bone formation is directly related to the amount of sutural separation, which is in turn related to the amount of force applied. The results suggest that there is a level of induced sutural separation that provides the greatest amount of bone formation.

Topics: Alloys; Animals; Biomechanical Phenomena; Bone Screws; Cephalometry; Cranial Sutures; Fluoresceins; Fluorescent Dyes; Frontal Bone; Male; Microscopy, Fluorescence; Nickel; Orthodontic Wires; Osteogenesis; Oxytetracycline; Rabbits; Random Allocation; Stress, Mechanical; Time Factors; Titanium

While both intermittent and continuous forces are commonly used to expand sutures, it remains unclear which force is most effective. Using nickel-titanium (NiTi) open coil springs (50 g) and 3 mm long miniscrew implants (MSIs) for skeletal anchorage, intermittent and continuous forces were used to expand the midsagittal sutures in 18 New Zealand white juvenile male rabbits, 11 weeks of age, for 29 days. In the intermittent group, expansion forces of 50 g were delivered for 5 days (on) and paused for 1 day (off); the on/off cycles were repeated five times. Expansion forces of 50 g were delivered for 29 consecutive days in the continuous group. Longitudinal biometric and histomorphometric analyses were performed to evaluate sutural separation and bone formation using implanted tantalum bone markers and fluorescent bone labelling, respectively. Multilevel modelling procedures were undertaken to compare the groups and time intervals. Continuous forces produced significantly greater overall sutural separation (1.3 mm) than intermittent forces (0.8 mm). Although they were delivered over a period of time 86 per cent as long, intermittent forces produced only 61 per cent of the sutural separation of continuous forces. Between days 7 and 17, continuous forces resulted in significantly greater mineral apposition and bone formation rates than intermittent forces. Intermittent forces produced approximately 59 per cent as much mineral apposition and 61 per cent as much bone formation as continuous forces. Due to greater sutural separation and bone formation, continuous forces provide a more effective approach for separating sutures than intermittent forces.

Topics: Animals; Biomechanical Phenomena; Bone Screws; Calcification, Physiologic; Cephalometry; Cranial Sutures; Dental Alloys; Fluoresceins; Fluorescent Dyes; Frontal Bone; Image Processing, Computer-Assisted; Male; Nickel; Orthodontic Anchorage Procedures; Orthodontic Appliance Design; Orthodontic Wires; Osteoblasts; Osteogenesis; Oxytetracycline; Palatal Expansion Technique; Rabbits; Random Allocation; Stress, Mechanical; Time Factors; Titanium

To determine the effects of phenylbutazone (PBZ) on bone activity and bone formation in horses.. 12 healthy 1- to 2-year-old horses.. Biopsy was performed to obtain unicortical bone specimens from 1 tibia on day 0 and from the contralateral tibia on day 14. Fluorochromic markers were administered IV 2 days prior to and on days 0, 10, 15, and 25 after biopsy was performed. Six horses received PBZ (4.4 mg/kg of body weight, PO, q 12 h) and 6 horses were used as controls. All horses were euthanatized on day 30 and tissues from biopsy sites, with adjacent cortical bone, were collected. Osteonal density and activity, mineral apposition rate (MAR), and percentage of mineralized tissue filling the biopsy-induced defects in cortical bone were assessed. Serum samples from all horses were analyzed for bone-specific alkaline phosphatase activity and concentration of PBZ.. MAR was significantly decreased in horses treated with PBZ. Regional acceleratory phenomenon was observed in cortical bone in both groups but was significantly decreased in horses treated with PBZ. Osteonal activity was similar at all time points in all horses. In control horses, percentage of mineralized tissue filling the cortical defects was significantly greater in defects present for 30 days, compared with defects present for 14 days. Differences in percentage of mineralized tissue were not detected in horses treated with PBZ.. PBZ decreased MAR in cortical bone and appeared to decrease healing rate of cortical defects in horses.

Topics: Alkaline Phosphatase; Animals; Anti-Inflammatory Agents, Non-Steroidal; Biopsy; Bone Density; Bone Remodeling; Chromatography, High Pressure Liquid; Female; Fluoresceins; Fluorescent Dyes; Fracture Healing; Fractures, Bone; Haversian System; Horse Diseases; Horses; Image Processing, Computer-Assisted; Immunoassay; Male; Oxytetracycline; Phenylbutazone; Prostaglandin Antagonists; Random Allocation; Tibia

This study assessed the distribution of active mineral formation sites within the middiaphyseal femoral cross section of swine and determined the extent to which various subsections represented bone formation activity in the entire cross section.. Twenty adult female swine (sows) were injected with two double (10-day intervals) labels 8 months apart. Labels involved fluorochrome markers of active mineral formation sites. Intact femoral middiaphyseal cross sections were embedded in polymethylmethacrylate, cut, and ground to 80 microm for analysis. Each specimen was subdivided into 16 anatomical and eight geometric subsections. Labeled mineralizing surface and mineral apposition rate were determined in the periosteal and endocortical envelopes. The number of labeled osteons per unit area of bone and osteonal mineral apposition rate were determined in the intracortical envelope.. Periosteal mineralizing surface followed a bimodal distribution with highest surface activation on the anterior and posterior segments. Periosteal mineral apposition rate followed a modal distribution with highest apposition rates in the posterior portion of the cross section. The distribution of forming osteons was modal with highest frequencies of labeled osteons in the posterior segment. No significant regional differences were detected for osteonal mineral apposition rate, endocortical mineralizing surface, or endocortical mineral apposition rate. The location of either a single or a combination of two to four subsections that best predicted mineralizing surface and mineral apposition rate in the entire cross section differed with each trait and envelope. Fifty percent of the entire area as alternate anatomical subsections was required to predict > 90% of variation in all traits evaluated. Overall, the predictability of mineralizing surface and mineral apposition rate was similar for geometrically defined subsections.. At least 50% of the cross-sectional area from alternate anatomical subsections must be measured to predict > 90% of variation in periosteal, intracortical, and endocortical mineralizing surface and mineral apposition rate in the sow middiaphyseal femur.

Topics: Animals; Bone Remodeling; Calcification, Physiologic; Diaphyses; Female; Femur; Fluoresceins; Fluorescent Dyes; Oxytetracycline; Periosteum; Reproducibility of Results; Statistics as Topic; Swine

The effect of early weaning on caries progression, dentin formation, and dentin mineralization was examined in four groups of rats. Two groups received a normal diet and were weaned on day 18 or 21, and another two received a sucrose-rich diet and were weaned on day 18 or 21. At age 35 days the lower molars were sectioned sagittally, and the areas of dentin formation and of the dentinal caries were quantified. The width of the predentin zone was measured from histologically stained sections of maxillary molars. Early weaning reduced dentin formation in the group on the high-sucrose diet only the first days; later this effect was partially caught up with. A high-sucrose diet significantly increased caries frequency and extension of caries lesions compared with a normal diet in both early weaned and normally weaned groups. The effect of early weaning on caries frequency and extension in the high-sucrose group was insignificant compared with the normally weaned group on a high-sucrose diet. The predentin zone was wider in the sucrose groups than in the control groups at the end of the experiment. These results indicate that the effect of sucrose on dentin formation was dependent on the stage of physiologic dentin formation, but early weaning as such did not affect this.

Topics: Analysis of Variance; Animals; Anti-Bacterial Agents; Coloring Agents; Dental Caries; Dental Enamel; Dentin; Dentinogenesis; Diet; Diet, Cariogenic; Dietary Sucrose; Disease Progression; Female; Fluoresceins; Fluorescent Dyes; Male; Molar; Oxytetracycline; Rats; Rats, Sprague-Dawley; Tooth Calcification; Weaning

This study was conducted to evaluate biologic responses of autogenous bone (particulate marrow and cancellous bone; PMCB) and beta-tricalcium phosphate ceramics (TCPC) to orthodontic stimuli. Nine dogs served as the experimental animals; three dogs underwent orthodontic tooth movement after grafting, three dogs received PMCB grafting without tooth movement, and three dogs received TCPC grafting without tooth movement. Immediately after extraction of the upper second and/or third incisors, the maxillary alveolar bone was resected bilaterally. Autogenous PMCB obtained from the iliac bone and TCPC were transplanted into each bone defect. Experimental tooth movement was initiated 2 to 4 weeks after the grafting and continued for 9 to 15 weeks. Sectional archwires with open-coll springs were used for distal movement of the upper first incisors into the extraction sites. Oxytetracycline and calcein were employed as bone markers. Sections of grafted areas including the teeth were prepared for light and fluorescence microscopy. The results revealed that both autogenous bone and TCPC presented similar adaptive changes to the original alveolar bone without any external stimuli. TCPC exhibited more prominent biodegradative responses to orthodontic force in association with new cementum formation. Root resorption was also less in the TCPC area than in the PMCB region. It is shown that TCPC is biodegradative in nature and adaptive for remodeling during orthodontic tooth movement. This finding indicates that TCPC may be a better biocompatible alternative to autogenous bone transplanted into bone defects subjected to orthodontic tooth movement.

Topics: Adaptation, Physiological; Alveolar Process; Alveolectomy; Animals; Biocompatible Materials; Biodegradation, Environmental; Bone Marrow Transplantation; Bone Transplantation; Calcium Phosphates; Ceramics; Dental Cementum; Dogs; Fluoresceins; Fluorescent Dyes; Maxilla; Microscopy, Fluorescence; Orthodontic Wires; Oxytetracycline; Prostheses and Implants; Root Resorption; Stress, Mechanical; Tooth Extraction; Tooth Movement Techniques; Transplantation, Autologous

Distribution of bone remodeling units (BRU) in relation to the perilymphatic space was studied in undecalcified temporal bones from adult rabbits labeled in vivo with bone-seeking fluorochromes. Based on recordings of focal bone formation, relative densities of BRUs inside concentric tissue zones around the inner ear spaces were estimated. Zonal densities of BRUs were found to decline towards the perilymphatic space, lending further support to the existence of a local inner ear mechanism in control of capsular bone tissue dynamics. The possible nature of this mechanism is considered briefly with special reference to inner ear electromechanic activity.

Topics: Animals; Anthraquinones; Bone Density; Bone Remodeling; Demeclocycline; Ear, Inner; Fluoresceins; Haversian System; Microscopy, Fluorescence; Oxytetracycline; Phenols; Rabbits; Sulfoxides; Temporal Bone; Tetracycline; Xylenes

Hard and soft diets were fed to weanling rats for up to 8 weeks. Some animals were switched after 4 weeks to the opposite diet. A histomorphometric study of bone formation activity at the mandibular ramus, body, and condyle was made after in vivo fluorochrome labelling. Mineral apposition rates at the lateral and inferior periosteal surfaces of the ramus were lower in the soft diet than in the hard diet animals. The rate of bone formation at the lateral periosteal surface of the ramus was significantly lower in soft than in hard diet animals. The medial periosteal surface of the ramus sometimes changed to bone formation in the soft diet groups. Condylar cartilage zones were somewhat thinner in soft diet groups. In the mandibular body, differences due to dietary consistency were less marked than near the gonial angle. Adaptation of periosteal bone and condylar cartilage to a new dietary consistency occurred within 4 weeks of switching. These results suggest that lateral and inferior periosteal bone growth of the ramus and condylar elongation were slowed in rats consuming soft diets. Decreased functional force during rapid mandibular bone growth causes changes in shape. The changes are due to regional decreases in osteoblast function, realignment of bone formation surfaces in the ramus area, and slowed growth in the condylar cartilage.

Topics: Animals; Cartilage, Articular; Cephalometry; Female; Fluoresceins; Food; Image Processing, Computer-Assisted; Indicators and Reagents; Mandible; Mandibular Condyle; Minerals; Osteogenesis; Oxytetracycline; Periosteum; Rats; Staining and Labeling

Labeling patterns were classified after double bone labeling of four male beagles, 10 months of age. Calcein and oxytetracycline were given on the 18th and the 7th day prior to simultaneous iliac and 11th rib biopsies. Undecalcified sections stained with the Villanueva bone stain were studied by epifluorescence microscopy. Five structures were identified and classified: the first or green label, the interlabel layer of mineralized bone, the second or yellow label, the post double-labeled mineralized bone layer, and osteoid seams. Doubly plus singly labeled surface equalled 40.8 +/- 8.4% of the total trabecular surface of the ilium. Doubly labeled surface as a percent of the total labeled surfaces equaled 55.5% in trabeculae and 68.1% in osteons, whereas green first-singly labeled surface equaled 24.2% and 11.9%, respectively, and yellow second-singly labeled surface equaled 20.3% and 20.0%, respectively. Unequivocal examples appeared in both biopsy sites of all four dogs of bone-forming systems that lacked one or the other label, or both, and also of systems in which cessation of mineralization or of new matrix formation occurred between the two labels and between the second label and the day of biopsy. The findings prove that the On-Off states in active bone-forming sites that have been postulated by other investigators do exist. Since widely different labeling patterns appeared in different bone-forming centers in the same bone and the same animal, a local factor rather than a systemic one should control those differences at the level of the BMU.

Topics: Animals; Bone Development; Dogs; Fluoresceins; Ilium; Male; Minerals; Oxytetracycline; Ribs