Alveolar bone regeneration using absorbable poly(L-lactide-co-epsilon-caprolactone)/beta-tricalcium phosphate membrane and gelatin sponge incorporating basic fibroblast growth factor.

The aim of this study was to evaluate the effects of combining a porous poly(L-lactide-co-epsilon-caprolactone)/beta-tricalcium phosphate membrane and gelatin sponge incorporating basic fibroblastic growth factor (bFGF) on bone regeneration in mandibular ridges. Four full-thickness saddle-type defects (10 mm long x 5 mm deep) were symmetrically created in both edentulous mandibular alveolar ridges of 6 beagles. The dome-shaped membrane was secured to each defect site, and a gelatin sponge containing 200 microg bFGF was implanted on the left side of each defect (experimental group). Only the membranes (control group) were secured to the defect sites on the right. Three and 6 months later, 3 animals were killed. Bone regeneration was analyzed by soft X-ray photographs, micro-computed tomography (CT) images, and peripheral quantitative CT (pQCT), and then examined histologically. Soft X-ray examination revealed an increase in new bone volume in the experimental group 6 months postoperatively. pQCT showed that immature bone density was higher in the experimental group. Micro-CT images revealed well formed new bone along the original contour of the dome-shaped membrane in the experimental group. Histologically, inflammatory infiltration of tissue surrounding the membranes was slight. These results suggest that combining the poly(L-lactide-co-epsilon-caprolactone)/beta-tricalcium phosphate membrane and bFGF-gelatin sponge is promising for alveolar ridge reconstruction.

Nizatidine and cisapride enhance salivary secretion in humans.

BACKGROUND: Salivation plays an important role in the defence of the oesophageal mucosa against gastric acidic reflux and can be evoked by cholinergic stimulation. Both nizatidine and cisapride have been reported to increase acetylcholine concentrations in the cholinergic system. AIM: To investigate the effect of nizatidine and cisapride on salivary secretion, salivary epidermal growth factor and bicarbonate output. METHODS: The salivary volume and concentration of salivary epidermal growth factor and bicarbonate were measured after the administration of nizatidine (150 mg), famotidine (20 mg) and cisapride (5 mg) in 30 male healthy volunteers. RESULTS: Basal and stimulated salivary secretions were found to be increased after the administration of nizatidine and cisapride. In contrast, salivary secretion was not increased by famotidine. Although epidermal growth factor content was not augmented, nizatidine and cisapride administration also increased the bicarbonate output in mastication-stimulated saliva. CONCLUSIONS: Increased salivary secretion and bicarbonate output induced by nizatidine may be useful for the treatment of patients with gastro-oesophageal reflux disease.

Study on the efficacy of biodegradable poly(L-lactide) mesh for supporting transplanted particulate cancellous bone and marrow: experiment involving subcutaneous implantation in dogs.

Poly(L-lactide) (PLLA) mesh sheets, monofilaments and mesh cylinders filled with fresh autogenic particulate cancellous bone and marrow (PCBM) were implanted subcutaneously into the back of 22 adult dogs for 1 yr. Polypropylene (PP) was used as a control. The inflammatory response to PLLA mesh sheets was slight, similar to PP mesh sheets. However, 3 months after implantation, histiocytes and multinucleate giant cells appeared on the surface of the monofilaments of PLLA mesh sheets and gradually increased in number as the monofilaments were degraded and absorbed. Almost no inflammatory cellular infiltration was seen in the tissue around PLLA mesh sheets or between the monofilaments. When a PLLA mesh cylinder filled with PCBM was implanted subcutaneously, the bone formation reached its peak 1 month after implantation, as in the case of a similar PP mesh cylinder, and bone formation was observed along the inner wall of the cylinder. In addition, a vascular net was abundant within the cylinder. The mechanical strength of the test material (PLLA monofilaments) did not change for almost 2 months after implantation, and 80% of its initial strength was retained for 3 months. These observations suggest that a PCBM graft supported by PLLA mesh would be very effective in the reconstruction of damaged maxillofacial bones, since histological tissue reactions associated with biodegradation of the PLLA mesh are mild and the PLLA mesh does not interfere with bone formation of PCBM. It was also found that the PLLA mesh retains its mechanical strength long enough to allow the PCBM transplant to develop sufficient strength to sustain the damaged region.

Reduction in tumour formation on porous polyethylene by collagen immobilization.

After surface modification with collagen immobilization through covalent bonding, porous polyethylene pieces with an average pore size of 400 microns were implanted subcutaneously into the back of rats for 1 yr. It was found that connective tissues with abundant blood vessels were formed clearly, filling more than 90% of the pore volume and bound firmly to the pore walls. A tumour was found in only one of 24 implanted pieces (4.2%). On the other hand, the virgin porous polyethylene pieces without collagen immobilization exhibited inflammatory reactions within the pores and the connective tissues produced filled only 15% of the pore volume. Formation of a malignant histiocytoma was observed in 11 of the 24 pieces which had been implanted (45.8%). Thus, immobilization of collagen on the surface of an artificial material through covalent bonding proved to be very effective not only for firm bonding with soft connective tissues but also for a reduction of tumour formation.

Soft tissue reaction to collagen-immobilized porous polyethylene: subcutaneous implantation in rats for 20 wk.

Collagen-immobilized porous polyethylene, in which the immobilization was through covalent bonding, and virgin porous polyethylene were implanted subcutaneously in rats from 1 to 20 wk. The results were the ingrowth of the connective tissue into collagen-immobilized porous polyethylene was rich and contained a low level of inflammatory cellular infiltration compared with that of virgin porous polyethylene. The material-tissue interface showed that the living body-originated collagen fibres were firmly anchored into the immobilized collagen layer. These results suggested that covalent immobilization of collagen on to the biomaterial surface is useful in promoting the ingrowth of soft tissue and the tissue adhesion.

Functional reconstruction of the jaw bones using poly(l-lactide) mesh and autogenic particulate cancellous bone and marrow.

The goal of the reconstruction of jaw bone defects should be not only to recover deformities, but also to reconstruct the jaw with which the patient can perform normal functions. To achieve this purpose, it is essential that a method of promoting regeneration of physiological bone is developed so that dentures can be accommodated. In this report a new method of functional reconstruction using fresh autogenous particulate cancellous bone and marrow and a poly(L-lactide) mesh tray is presented. This method will make physiological reconstruction of the jaw possible. In the future this method is also expected to assist in the development of simultaneous functional reconstruction of the jaw bone and oral rehabilitation when dental implants are included in the tray.

The effect of hypofunction on the mechanical properties of the periodontium in the rat mandibular first molar.

The right maxillary molars of male rats were removed under ether anaesthesia to eliminate occlusal contact with the mandibular molars. Groups of rats were killed at 1, 2, 4, 8 and 16 days after the experimental procedure. The dissected mandibles were radiographed and length of erupted portion of the tooth, height of alveolar crest and length of tooth were measured. The tensile strength of the periodontal ligament was measured by extracting the first molar from its socket. A marked and progressive decrease of the load required to extract the tooth was found in the first few days after the removal of the opposing teeth. No significant difference in extracting loads was found between the 8- and 16-day groups. Radiography showed that the teeth had erupted, that the height of alveolar crest had decreased and that the length of the root had increased during the experimental period. These changes were detectable only on the 8th or 16th day following the experimental procedure. It is suggested that the reduction in the mechanical strength of the hypofunctional rat molar periodontal ligament is closely associated with the progressive atrophy of the periodontal ligament and that normal functional activity of the teeth is important not only for maintenance of the structural integrity of the periodontal ligament but also to maintain the mechanical strength of the supporting tissues.

Effects of storage of jaws in saline and of velocity of loading on the force required to extract the rat mandibular first molar.

Storage of jaws in cold saline for up to 32 h did not cause significant changes in the ultimate loads required to extract the rat mandibular first molar. The mean ultimate loads were 33.05, 34.91 and 36.38 newtons at the extension rates 1, 5 and 25 mm/min respectively, though the differences were not significant between groups. The force required to extract the tooth would be fairly constant even after the storage of the dissected jaws in cold saline for longer periods of time. Changes in the force required were not detectable within the range of the velocities of loading employed.

Preoperative embolization of meningiomas fed by ophthalmic branch arteries.

BACKGROUND: The efficacy of preoperative embolization for hypervascular meningiomas mainly fed by the branches of the ophthalmic arteries was examined. CASES AND METHODS: Five hypervascular meningiomas mainly fed by the branches of the ophthalmic arteries, four posterior ethmoidal arteries, one anterior falx artery, and one recurrent middle meningeal artery were embolized with Gel-foam powder, polyvinyl alcohol (PVA) particles, and/or microcoils as a preoperative treatment using a microcatheter. RESULTS: Catheterization of the ophthalmic and tumor feeding artery was possible and feeding arteries and lesion embolization were effective to reduce the bleeding during surgery in all cases. In three cases, visual acuity and visual field were preserved. However, in one case, visual acuity and visual field defect appeared due to the migration of Gelfoam powder (Upjohn, Kalamazoo, MI) into the retinal artery. In another case, the retinal artery was embolized with the feeding arteries since the patient was already blind. CONCLUSION: Embolization of hypervascular meningioma feeding vessels arising from the ophthalmic artery is possible and effective with preservation of vision, if embolic agents are injected gently enough not to reflux into the central retinal artery.

Reduction in tumor formation on polyethylene by collagen immobilization.

After surface modification with collagen immobilization through covalent binding, porous polyethylene pieces were implanted subcutaneously into the back of rats for 1 year and the tumorigenesis-reducing effect was examined. In the virgin pieces without collagen immobilization, tumors were observed in 11 out of 24 pieces implanted (45.8%). On the other hand, in the collagen immobilized pieces a tumor was found only in one of 24 implanted pieces (4.2%). These results suggest that immobilization of collagen on the surface of an artificial material through covalent binding is very effective for a reduction of tumor formation.

Mandibular reconstruction using a poly(L-lactide) mesh combined with autogenous particulate cancellous bone and marrow: a prospective clinical study.

The purpose of this study was to evaluate the stability and viability of mandibular bone regeneration using a poly(L-lactide) (PLLA) mesh and autogenous particulate cancellous bone and marrow (PCBM). Sixty-two procedures were undertaken at eight hospitals (22 malignant tumours, 30 benign tumours, five cysts, two osteomyelitis, two trauma, and one atrophy of the alveolar ridge); the success rate was 84%. The follow-up period was between 9 and 200 months (mean 88.2 months). Consequently, bone regeneration at 6 months postoperation was excellent in 35 cases (57%), good in 17 cases (27%), and poor in 10 cases (16%). In six of the 'poor' cases, the PLLA mesh was removed due to local infection early after surgery. Bone resorption>20% was observed in only one of 46 cases with a follow-up term of >1 year. There were no signs of any other adverse effects except in one case where a section of the tray broke off late in the follow-up period. It is concluded that this method is stable and effective due to favourable morphological and functional recovery and low invasiveness. It may thus be a useful alternative procedure for mandibular reconstruction.

Estimation of the remaining periodontal ligament from attachment-level measurements.

AIM: Accurate assessment of the remaining area of periodontal attachment assists in determining the prognosis of a tooth. The aim of this study was to determine formulae to estimate the remaining area of periodontal attachment from attachment-level measures. MATERIALS AND METHODS: Roots of 30 extracted teeth of each tooth type were coated with vinyl acetate solution and alpha-cyanoacrylate monomer to produce a membrane. The membrane was removed after guidelines were drawn to simulate various attachment levels. The root surface area on the apical side of each simulated attachment level was measured using image analysis software. The net or percent root surface area and corresponding attachment level data were fitted to a linear, quadratic, cubic, and exponential functions and a growth curve. RESULTS: The linear function provided the most appropriate fit for the data. For net root surface area, a steeper slope was evident for tooth types with a larger mean total root surface area. For percent root surface area, a steeper slope was evident for tooth types with a shorter root length. CONCLUSIONS: A linear function provides the most appropriate formula for estimation of the remaining area of periodontal attachment based on the attachment-level measurement.

Bacteriological study of autologous cryoprecipitate-derived fibrin glue as the operative sealant.

Fibrin glue (FG) is frequently used to seal and cover the anastomoses in many operations such as cardiovascular surgery or orthopaedic surgery. However, in case of gastrointestinal surgery, anastomoses are potentially contaminated, and FG may promote bacterial growth, increasing the risk of leakage. The purpose of this study was to examine the effect of cryoprecipitate-derived FG (CryoFG) on bacterial growth. Bacterial growth on the CryoFG and on the commercial FG (Beriplast P) was evaluated and compared with that on control medium. In addition, the complement activities were evaluated by heat inactivation or addition of guinea-pig complement to the experimental settings. The CryoFG inhibited the growth of Escherichia coli, whereas the commercial FG had no effect. Heat inactivation of the CryoFG inhibited the bactericidal effect of CryoFG. Addition of guinea-pig complement to the heat-inactivated CryoFG could almost restore the bactericidal activity, suggesting the important role of complement. This study showed that the CryoFG preserved the complement activity, which inhibited the in vitro growth of E. coli. Therefore, we concluded that the application of the CryoFG for gastrointestinal surgical anastomoses not only would be safe but also has the advantage of reducing bacterial infection.

Incorporation of serum albumin into the developing dentine and enamel matrix in the rabbit incisor.

Rabbit serum albumin labeled with 125I was injected into rabbits (650-870 g). The incorporation pattern of the labeled albumin into the developing dentine and enamel matrix was studied 1 h, 6 h, and 3 days after the injection using autoradiography. Silver grains were observed over the predentine 1 h after the injection. They were found over the dentine matrix adjacent to the predentine-dentine junction at 6 h. The silver grain band was concentrated over the internal dentine matrix at 3 days. However, no appreciable amount of the silver grains could be seen over the enamel matrix at any time after the injection. It is possible that there might be some physiological barrier between the extravascular fluid and the enamel matrix. The role of the albumin in dentine is discussed.

Study on incorporation of homologous serum albumin into the developing rabbit incisor.

The incorporation pattern of the rabbit albumin labelled with Lissamine Rhodamine B200 or 125I into the rabbit dentine and the enamel matrices was studied by fluorescence microscopy and/or autoradiography. The fluorescence of the fluorochrome-labelled albumin was observed in the dentine at 6 hours and 3 days. Autoradiographic silver grains were observed over the predentine at 1 hour after the injection. They were found over the dentine matrix adjacent to the predentine-dentine junction at 6 hours. The silver grain band was concentrated over the internal dentine matrix at 3 days. However, an appreciable amount of the fluorescence could not be seen in the enamel at any time after the injection. Also, no significant differences in the number of autoradiographic silver grains were found over the enamel matrix between the experimental groups and the background at any time after the injection. These results suggested that albumin was incorporated into the developing dentine matrix but not into the developing enamel matrix.

A rapid method for measuring the phospholipid synthetic activity of incubated lymphocytes.

A rapid and simple method for estimating the phospholipid synthetic activity of incubated lymphocytes by a Florisil column technique following the uptake of 14C-oleic acid was established. Stimulation of phospholipid synthesis by PHA and inhibitions caused by Tween 20 or Tween 80 and heating were evaluated easily with this method.

Reconstruction of mandibular continuity defects in dogs using poly (L-lactide) mesh and autogenic particulate cancellous bone and marrow: preliminary report.

PURPOSE: This study evaluated the reconstruction of continuity defects in the canine mandible using a poly [L-lactide] (PLLA) mesh tray and particulate cancellous bone and marrow (PCBM). MATERIALS AND METHODS: Eight adult dogs were divided into two groups of four dogs each. In group A, each dog had a tray fixed with stainless steel wires on each side of the mandibular stumps with the concave surface of the tray attached to the inferior border of the mandible (U-fixation). In group B, the concave surface was attached to the superior border (inverted U-fixation). Each tray was filled with PCBM from the ilium. After the operation, the dogs were radiographed, and specimens were examined histologically at 3-, 6-, and 12-month intervals. RESULTS: All of group A showed good clinical healing and the continuity of the mandibular bone was regained within 3 months postoperatively. However, fibrous tissue had invaded through the area above the tray, resulting in a poorly shaped alveolar ridges. In group B, the dogs showed good bony regeneration with well-shaped alveolar ridges. However, two animals in this group had partial exposure of the PLLA mesh tray into the oral cavity. CONCLUSION: It is suggested that a combination of the PLLA mesh and PCBM grafts might be a useful technique for functional reconstruction of the jaw bone, specifically using method A (U-fixation) as a technique to reconstruct continuity defects of the mandible, and method B (inverted, U-fixation) as a promising method for alveolar reconstruction to make wearing dentures possible.

Periodontal ligament cell culture on the hydrophobic substrate coated with proteins of periodontal ligament fibroblast-conditioned medium.

In regenerating periodontal ligament (PDL) around the root of an artificial tooth, an important role is played by some physiologically active substance that promotes adhesion of the cells to the surface of the tooth root and induces cell proliferation and differentiation. In this study, the supernatant of the conditioned medium (CM) of dog periodontal ligament fibroblast (DPLF) was fractionated using an ion exchange chromatography-diethylaminoethyl (IEC-DEAE) column. DPLFs were cultured on hydrophobic dishes coated with each fraction. Cell proliferative activity and alkaline phosphatase (ALPase) activity, including electron microscopic features of the contact surface between the cells and the dish, were investigated. The DPLF-CM was separated by IEC-DEAE column into six fractions. Each fraction promoted an increase in DNA content and ALPase activity of the cultured DPLF, and especially remarkable were fractions 2 and 3. Fraction 2 at a molecular weight (Mw) of 210, 160, 85, 50 and 22 kD, and fraction 3 at Mw = 21 and 23 kD contained the type of proteins not found in other fractions. Electron microscopic analysis revealed that the cells in the coating group were in close contact with the surface of the dishes and that fine fibers protruding from the cell membrane clinged to the dishes. In the control group, a wide gap between the cells and the dishes was observed. These findings suggest that the DPLF-CM fractions contain specific physiological activating factors that induce proliferation and differentiation as well as cell adhesion of the DPLF cells.