Biomedical subjects
Publications and source records attributed to R Beer.
The pulpal response of the glass ionomer cement Ketac fil was investigated in a biological usage test in human and pig teeth. The mainly no or slight pulpal response in all test periods leads to the conclusion that Ketac fil in deep cavities with calcium hydroxide is not necessary.
The biocompatibility of a fast setting glass-ionomer cement and of reference materials (zink-phosphate cement, silicate cement, ZOE, composite) was assessed in a comparative biological study. Cytotoxicity testing revealed 90% counted cell numbers after incubation for 96 hours. Subcutaneous implantation tests resulted in slight, moderate and severe connective tissue reactions. In contrast to these results the three different usage tests revealed slight, reversible pulp reactions in rat incisors, pig and human teeth. After 90 days of testing there was no chronic persistent pulp irritation. It may be concluded that Ketac-Bond, is an acceptable restorative material.
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The biological properties of Scotchbond as a dentin-bonding agent were assessed in cytotoxicity tests, subcutaneous implantation, in an acute vital microscopically controlled test on rat incisors and in an usage test on human teeth. The persistent moderate reactions in human teeth in the test period over 90 days, the strong toxicity in the initial and secondary biological test leads to the conclusion, that there is no clinical indication to use the dentin-bonding Scotchbond without proper pulp protection. According to scanning electron microscopy of the marginal adaptation of the enamel etch technique in connection with enamel bonding to long beveled enamel produced acceptable marginal adaptation of P-30 composite restorations.
The therapy of cervical lesions in the visible facial area is not free of problems. The aim of this study is to investigate the marginal leakage by means of SEM analysis after in vitro and in vivo application of porcelain inlays in the cervical area, bonded to the enamel by a microfilled composite. Our results show, that the bond between composite and enamel is better than the bond between composite and inlay treated with a silane coupling agent. Problems of the leakage size and of the transparency can favourably be influenced by the composite as cementation material.
The root canals of 35 extracted mandibular incisors were instrumented with the ultrasonic-system alone or in combination with hand instruments. Hand instrumentation was compared with ultrasonic instrumentation. Following instrumentation the teeth were prepared for SEM examination. It was concluded that hand instrumentation using reamers was superior to ultrasonic debridement. After initial preparation and finally shaping with hand instruments the ultrasonic device shows good efficiency in cleaning straight root canals.
76 root canal treated teeth were followed up within 2 years after treatment with the help of the periapical index PAI and the root canal filling index WKF-I. The root canals were obturated with gutta-percha and Sealer according to lateral or thermom chanical condensation. Treatment was successful in 26 of the lateral condensated and in 25 of the thermomechanical condensated cases. The thermomechanical condensation method represents an alternative method for filling root canals for those endodontists who are well practiced in this method and ensures a high success rate at exact indication positions. Intense practice on extracted teeth prior to clinical application is a strong prerequisite. The lateal condensation method is the root canal filling technique of choice for the general dental practice.
In order to compare the effects of suture and glue direct nerve connections and nerve transplantations in the sciatic nerve in rats were performed. 4, 6 and 12 weeks later, the nerve anastomosis were histologically studied. In the direct nerve connections, despite a single holding suture, dehiscences were frequently detected with the penetration of the adhesive between the nerve ends. Due to the exact adaptation with the aid of inserted nerve grafts, the anastomoses could be repaired sutureless successfully using a fibrin glue cuff. Since histologically, in comparison to suture, no foreign body granulomas were found, the findings in the literature could be confirmed. No cicatricial contractions of the anastomoses could be found. In the interfascicular nerve transplantation, comparatively good results may be obtained using the two-component adhesive on the Cohn I-fraction basis.
The rat skulls were operated upon using a trephine osteoplastically, and a defined cerebral and dura defect was induced. The repair of the cerebral defect was performed with Cohn I glue, or in combination with collageneous fleece. The dura defect was repaired by suture and/or glueing of a split skin or pedicle galeal-periostal flap. Thanks to using Cohn I glue, at all times sufficient venous hemostasis could be achieved, and in combination with collagen fleece the repair was at an optimum. The histological check-up demonstrated that neurotoxic side-effects were absent and there were no conglutinations with the dura. Suturing of the dura was highly time-consuming and impossible when the dura had been removed near the bone. The use of Cohn I adhesive permitted ready and defect repair commonly applicable. At high tension the combined suture-glueing technique proved to be superior.
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A trepanation model in the rat cranium is represented starting from the permanent enlargement of the microneurosurgical interventions with the necessity of trepanation below the microscope, the suture of the dura mater in regions with difficult access, and the dressing of cerebral tissue defects. A possibility for the microsurgical training is given for the trepanation and the dressing of dural and cerebral defects. Surgical materials and/or drugs for local application can be tested for using them in the neurosurgery too.
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In a comparison of suture and fibrin bonding (using human plasma fraction Cohn I) direct as well as autologous and homologous nerve transplantations were performed in animal experiments. The study was carried out in a total of 66 Nn. ischiadici in Albino Wistar rats. With and without transplants the anastomoses were provided 26 times with the usual microsurgical single-button suture technique and 11 times tith a fibrin adhesive cuff with sequential application of the two components (500 I. U. thrombin/ml, 3,000 units contrycal) or simultaneous application after premixing of the components (5 I. U. thrombin/ml, 50 units contrycal). The qualitative evaluation was carried out after 4, 6, and 12 weeks according to the clinical and histological findings. With the use of sufficiently long transplants the nerve anastomoses could be fixed sutureless with the adhesive cuff more simply than with sutures. Histologically an undisturbed growing forth of the axons without foreign-body reactions and scarred constrictions could be proved. The sutured anastomoses, too, showed a good regeneration; owing to the 2-3 single button-sutures only low-degree tissue reactions occurred around the threads without any greater impairment of the proliferation of the neurites. In case of the direct uniting of the nerves adhesion was only possible in combination with a holding suture. In most cases, however, anastomose dehiscences with a bad result were nevertheless found. The direct nerve suture had to be carried out with 5-7 single-button sutures. In this case, considerably pronounced foreign-body reactions were sometimes found histologically. The nerve regeneration, however, was much better than in case of bonding by adhesion. In contrast to the application in direct nerve joining, the Cohn I adhesive could be used with good results for nerve transplantations.