Mandibular Jaw Bone Regeneration Using Human Dental Cell-Seeded Tyrosine-Derived Polycarbonate Scaffolds.

Here we present a new model for alveolar jaw bone regeneration, which uses human dental pulp cells (hDPCs) combined with tyrosine-derived polycarbonate polymer scaffolds [E1001(1k)] containing beta-tricalcium phosphate (ß-TCP) [E1001(1k)/ß-TCP]. E1001(1k)/ß-TCP scaffolds (5 mm diameter × 1 mm thickness) were fabricated to fit a 5 mm rat mandibular ramus critical bone defect. Five experimental groups were examined in this study: (1) E1001(1k)/ß-TCP scaffolds seeded with a high density of hDPCs, 5.0 × 10(5) hDPCs/scaffold (CH); (2) E1001(1k)/ß-TCP scaffolds seeded with a lower density of hDPCs, 2.5 × 10(5) hDPCs/scaffold (CL); (3) acellular E1001(1k)/ß-TCP scaffolds (SA); (4) acellular E1001(1k)/ß-TCP scaffolds supplemented with 4 µg recombinant human bone morphogenetic protein-2 (BMP); and (5) empty defects (EDs). Replicate hDPC-seeded and acellular E1001(1k)/ß-TCP scaffolds were cultured in vitro in osteogenic media for 1 week before implantation for 3 and 6 weeks. Live microcomputed tomography (µCT) imaging at 3 and 6 weeks postimplantation revealed robust bone regeneration in the BMP implant group. CH and CL groups exhibited similar uniformly distributed mineralized tissue coverage throughout the defects, but less than the BMP implants. In contrast, SA-treated defects exhibited sparse areas of mineralized tissue regeneration. The ED group exhibited slightly reduced defect size. Histological analyses revealed no indication of an immune response. In addition, robust expression of dentin and bone differentiation marker expression was observed in hDPC-seeded scaffolds, whereas, in contrast, BMP and SA implants exhibited only bone and not dentin differentiation marker expression. hDPCs were detected in 3-week but not in 6-week hDPC-seeded scaffold groups, indicating their survival for at least 3 weeks. Together, these results show that hDPC-seeded E1001(1k)/ß-TCP scaffolds support the rapid regeneration of osteo-dentin-like mineralized jaw tissue, suggesting a promising new therapy for alveolar jaw bone repair and regeneration.

Unique and reliable rat model for the assessment of cell therapy: bone union in the rat mandibular symphysis using bone marrow stromal cells.

Many kinds of bone graft materials have been developed and reported to repair various bone defects. The defects are usually created by surgical resection of pre-existing bone tissue. However, spontaneous healing of bone defects without implantation of materials could be seen, because bone tissue possesses inherent repairing property. The central portion of the lower jaw bone in many animals consists of fibrous tissue and is called the mandibular symphysis. It persists even in old animals and thus can be interpreted as a physiological bone gap or a non-healing bone defect. We implanted calcium phosphate porous ceramics alone or composites of the ceramics and bone marrow stromal cells (BMSCs) into the bone defect (mandibular symphysis) to examine whether it could be filled with new bone tissue, resulting in bone union. Eight weeks after implantation, micro-computed tomography (micro-CT) and histological and biomechanical analyses demonstrated that bone union of the mandibles occurred in all rats with composites but in none of those with ceramics alone. These results showed that the rat mandibular symphysis is a unique bone defect site for the evaluation of bone graft materials. These analyses demonstrated that ceramics alone could not contribute to bone healing in the defect; however, supplementation with BMSCs drastically changed the properties of the ceramics (turning them into osteogenic ceramics), which completely healed the defect. As BMSCs can be culture-expanded using small amounts of bone marrow, the use of the composites might have clinical significance for the reconstruction of various bone tissues, including facial bone.

Effect of low-level laser therapy on bone repair: histological study in rats.

BACKGROUND AND OBJECTIVES: Bone remodeling is characterized as a cyclic and lengthy process. It is currently accepted that not only this dynamics is triggered by a biological process, but also biochemical, electrical, and mechanical stimuli are key factors for the maintenance of bone tissue. The hypothesis that low-level laser therapy (LLLT) may favor bone repair has been suggested. The purpose of this study was to evaluate the bone repair in defects created in rat lower jaws after stimulation with infrared LLLT directly on the injured tissue. STUDY DESIGN/MATERIALS AND METHODS: Bone defects were prepared on the mandibles of 30 Holtzman rats allocated in two groups (n = 15), which were divided in three evaluation period (15, 45, and 60 days), with five animals each. control group-no treatment of the defect; laser group-single laser irradiation with a GaAlAs semiconductor diode laser device (lambda = 780 nm; P = 35 mW; t = 40 s; Theta = 1.0 mm; D = 178 J/cm(2); E = 1.4 J) directly on the defect area. The rats were sacrificed at the pre-established periods and the mandibles were removed and processed for staining with hematoxylin and eosin, Masson's Trichrome and picrosirius techniques. RESULTS: The histological results showed bone formation in both groups. However, the laser group exhibited an advanced tissue response compared to the control group, abbreviating the initial inflammatory reaction and promoting rapid new bone matrix formation at 15 and 45 days (P<0.05). On the other hand, there were no significant differences between the groups at 60 days. CONCLUSION: The use of infrared LLLT directly to the injured tissue showed a biostimulating effect on bone remodeling by stimulating the modulation of the initial inflammatory response and anticipating the resolution to normal conditions at the earlier periods. However, there were no differences between the groups at 60 days.

Molecular structure of the bony tissue after experimental trauma to the mandibular region followed by laser therapy.

OBJECTIVE: We investigated the therapeutic efficiency of laser irradiation and Bio-Oss, both and separately, on the post-traumatic regeneration of bone tissue in rats using infrared spectroscopy as an informative and accurate measuring method. BACKGROUND DATA: The therapeutic effect of low-power laser irradiation on bone tissue regeneration processes in animal models has been studied using morphogenic, biochemical, roentgenographic and electron microscopic measurements. Natural bone minerals, such as Bio-Oss collagen, were recommended for the reconstruction of bone defects in the alveolar process. MATERIALS AND METHODS: 29 male Wistar rats, divided into four random groups in a blinded manner were operated on the right alveolar process. A bone defect was made by penetrating the right alveolar process of the mandible bone using a 3-mm drill. The rats were divided into four groups as follows: Group I, left side served as intact bone and right injured side as the control; Group II, right injured side was treated by organic bovine bone (Bio-Oss); Group III, right side bone defect was treated by HeNe laser (632.8 nm, 35 mW) applied transcutaneously for 20 min to the injured area daily for the following 14 consecutive days; and Group IV, Bio-Oss was placed loosely in the right side defect followed by laser treatment. After 2 weeks, the intact bone and bone replicas of the trauma area were removed and analyzed by infra-red spectroscopy technique. The composition and the structure of the bone tissue mineral substances were determined and compared among the four groups. For quantitative analysis of the regenerative bone process, the Mineralization index was used. An increase in this index indicates regenerative bone processes. RESULTS: The normal state analysis of the IR spectra of the normal alveolar bone tissue within the intervals of 400 to 4000 cm(-1) revealed characteristic absorption bands for the inorganic bone component in spectrum regions 450-1480 cm(-1), and the organic component at 1540-3340 cm(-1). In the case of trauma, the intensity of absorption of the inorganic component was decreased by 54%, and the absorption band became narrow, which can be interpreted as quantitative changes of the bone tissue mineral content. The wavelength characteristics of the inorganic component remained unchanged; that is, the induced trauma under these experimental conditions did not provoke alterations in the structure of the phosphate framework. The organic component showed decreased absorption by 10-15%, compared to the normal bone, and slight displacement of the wavelength, which can be interpreted as changes occurring in the quality of the organic content of the bone tissue. In the Bio-Oss-treated group, the intensity of absorption of the inorganic component increased by 43%, compared to the control injured area; however, there was a decrease of 22.6% in the normal bone. The wavelength characteristics of the inorganic component remained unchanged. The organic component showed similar absorption results in the injured non-treated group and absorption was 10-15% less than in the normal bone. Mineralization Index in the Bio-Oss-treated group was 0.93, compared to 0.63 in the control group and 2.04 in the normal bone. In the laser-treated group, the intensity of absorption of the inorganic component increased by 62, compared to the control injured area, and decreased only 11.4% in the normal bone. The wavelength characteristics of the organic component remained unchanged; that is, the organic component was similar to that of normal bone. Mineralization Index in the laser-treated group increased significantly to 1.86, compared to 0.63 in the control group and 2.04 in the normal bone. In the combined laser and Bio-Oss-treated groups, the intensity of absorption of the inorganic component and organic component was similar to that of normal bone. Mineralization Index in this group increased significantly to 1.98, compared to 0.63 in the control group and 2.04 in the normal bone. CONCLUSION: The results suggest that low-power laser irradiatults suggest that low-power laser irradiation alone and in combination with Bio-Oss enhances bone healing and increases bone repair.

[A trial of using a weak geomagnetic field in treating acute and chronic surgical infection]. / Opyt primeneniia oslablennogo geomagnitnogo polia v lechenii ostroi i kronicheskoi khirurgicheskoi infektsii.

Results of treatment of 147 stomatologic and traumatologic patients with acute and chronic surgical infection are presented. A weak geomagnetic induction field (B approximately 0,125 x 10(-4) T) is a medical factor. Local partial screening of the geomagnetic field in the area of the pathological focus shows high efficiency of treatment of the patients in question. The nearest positive results of treatment equals 99,3%. Long-term positive results--91,9%.

Stimulation of early bone formation by the combination of an osteopromotive membrane technique and hyperbaric oxygen.

Large bone defects often heal incompletely as a result of ingrowth of connective tissue. By using a mechanical hindrance, a porous expanded polytetrafluoroethylene (e-PTFE) membrane, it is possible to prevent fibroblasts and other soft connective tissue cells from entering the defect, thereby allowing osteogenesis to occur unhindered. As evidenced in several investigations, this osteopromotive membrane technique causes a strongly improved bone regeneration of well defined osseous lesions. Hyperbaric oxygen treatment has also been shown to accelerate bone healing. In this study the value of combining the two techniques was investigated. Through-and-through bone defects, 5 mm in diameter, were produced unilaterally in the angular region of the mandibles of adult rats (n = 60); the defects in half the number of animals were covered lingually and buccally with membranes. The animals were then divided into four groups: treatment with membrane alone, treatment with hyperbaric oxygen alone, combined treatment, and no treatment. Histological examination of the defects after 14 days showed that the combination of techniques had resulted in significant improvement in bone healing, compared with hyperbaric oxygen or the membrane technique alone. Synergistic effects can thus be achieved by the use of membranes and stimulatory factors for bone regeneration.

The treatment of radiation necrosis with hyperbaric oxygen (OHP).

Sixty-nine patients with radiation necrosis were received by the authors from January 1, 1969 through August 1, 1975. The patients were categorized according to site of injury. Full treatment protocol is discussed including local wound care, antibiotic coverage, surgical procedures, and the administration of hyperbaric oxygen. Results indicate that the combination of hyperbaric oxygen, properly timed surgery, and antibiotic therapy has resulted in improvement in all cases of radiation necrosis and full healing in most.