Rehabilitation with dental implants of oral cancer patients.

The aim of this study was to evaluate the risks and complications of rehabilitation with dental implants after tumour surgery and radiotherapy. After a disease-free survival of 18 months, 29 patients who had undergone oral cancer treatment were rehabilitated with dental implants. The complication rate of implants in irradiated, non-irradiated and grafted bone was analyzed at least 3 years after implant placement. In the healing period, 28.6% of the implants in irradiated bone and 8.4% in non-irradiated bone showed soft tissue complications. Of the implants, 26.7% in the irradiated and 14.7% in the non-irradiated mandibular bone were lost in the first 36 months after placement. Thirty-one point two percent of implants inserted in non-irradiated bone grafts were affected and did not osseointegrate. Of 109 inserted implants, 70 were suitable for prosthetic rehabilitation. There are high complication rates after implant placement in oral cancer patients. Irradiation adversely affects soft tissue healing. Osseointegration is frequently disturbed, especially when implants were placed in non-vascularized bone grafts.

[Regeneration of mouth mucosa in the buccal plane following graft procurement for reconstruction of bulbar urethral stenoses]. / Regeneration der Mundschleimhaut im Planum buccale nach Entnahme zur Rekonstruktion von bulbären Urethrastenosen.

The use of free buccal mucosal grafts in the treatment of urethral strictures has become very popular. In 1996 and 1997 we harvested free buccal mucosal grafts up to 7 cm long and 4 cm wide from 12 patients who underwent urologic surgery for urethral strictures. In 2 patients the donor site was closed primarily by sutures. Four patients received Lyodura and another 4 patients received Syspurderm as temporary wound coverage. In 2 patients Ethisorp patches were used. Donor site pain was judged by the patients on a visual analogue scale during the first postoperative week. The 2 patients who received the Ethisorp patches complained of more intense pain, probably caused by the rigidity of the material. In all patients regeneration of the donor site mucosa was good. During the follow-up period of 4-18 months scar formation at the lower vestibulum was noticed as the only complication. Permanent limitation of mouth opening, stenosis of the parotid duct or hypesthesia did not occur.

[Biocompatibility of a new ionomer bone cement in endoprosthetics. In vitro testing using a mixed bone cell culture]. / Untersuchungen zur Biokompatibilität eines neuen ionomeren Knochenzementes in der Endoprothetik. In-vitro Testung mittels einer gemischten Knochenzellkultur.

Periosteal derived bovine osteoblasts and osteoclasts migrated in culture onto an ionomeric cement, currently evaluated as a cement for orthopaedic implants. Cell cultures were maintained for 4 weeks and used to study the in-vitro behaviour of cells on the material surface. Osteoblasts and osteoclasts colonized the substrate in monolayers and exhibited their phenotypic morphology. Differentiation into both cell lines were demonstrated by immunostaining. Staining for aluminium in cells growing on the bone cement showed an uptake and storage of aluminium in the cells. EDAX-microanalysis revealed high concentrations of Al and Si in the periosteal tissue. Despite uptake of Al in the cells, signs of toxicity were not apparent in the cell culture system.

Biological evaluation of an ionomeric bone cement by osteoblast cell culture methods.

Periosteal derived bovine osteoblast-like cells migrated in culture onto an ionomeric cement. Cell cultures were maintained for 4 weeks and used to study the in vitro behaviour of cells on the ionomeric bone cement (IC). The cells produced bone matrix proteins (osteocalcin, bone sialoprotein II) and were osteoblast-like. The osteoblast-like cells colonized the substrate in monolayers and produced an extracellular matrix as seen by light and scanning electron microscopy. Morphological comparison between cells growing on the ionomeric bone cement and cortical bone revealed no significant difference in phenotypic expression. Staining for aluminium in osteoblasts growing on the IC showed an uptake and storage of aluminium in the cells. Energy dispersive X-ray microanalysis revealed high concentrations of aluminium and silicon in the periosteal tissue. Despite the known toxic effect of aluminium in vivo and in vitro on osteoblasts, no signs of toxicity were apparent on light and scanning electron microscopy analysis.

Characteristics of equilibrium reaction of zolazepam.

The equilibrium reaction of zolazepam, a pyrazolodiazepinone, was studied and analyzed using the approach used previously for other pyrazolodiazepinone derivatives. The intrinsic ring closure equilibrium constant for this reaction was approximately 100 times larger than that observed for pyrazolodiazepinones studied previously. This study illustrates that the diazepinone ring can dominate in equilibrium mixtures formed at pH values far below the pKa of the corresponding form.

Identification and analysis of persistent contaminants associated with gemcadiol.

Application of several analytical probes indicated that certain batches of the investigational new drug gemcadiol (2,2,9,9-tetramethyl-1,10-decanediol) were contaminated with impurities whose nature and source were unknown. Subsequent study showed that these impurities consisted of polymeric material formed by self-condensation of the dialdehyde precursor. Gel permeation chromatographic techniques were found to be useful in the analysis of polymers present in both the aldehyde precursor and the finished drug.

Stability-indicating assay for vidarabine.

A physicochemical procedure for the analysis of vidarabine in aqueous parenteral formulations was needed to assure potency and to define stability. Concurrent with the development of this method, its decomposition products and route in aqueous solution were determined. A quantitative procedure was developed to determine intact drug in the presence of decomposition products, and the results obtained were validated by microbial assay. Spectral (UV and polarimetric) and TLC evidence indicated that, in aqueous solution, hydrolysis without racemization occurs, yielding adenine and arabinose. The sensitivity of the method to decomposition is improved by ion-exchange separation of adenine and drug before UV measurement. Analysis of partially decomposed solutions of the drug by both ion-exchange and microbiological methods gave comparable results.

Equilibrium reaction of pyrazolodiazepinones in aqueous solution.

This study of the behavior of some pyrazolodiazepinones in aqueous solution at near ambient temperature indicated that they form stable equilibrium mixtures consisting of ring and opened forms. Under isothermal conditions, mixtures are produced whose composition is dependent on pH and may vary from that corresponding to essentially complete ring opening to complete closure. Ring closure equilibrium constants were calculated, and the influence of methyl substitution was determined. Substitution of a methyl group for an amido hydrogen in the open form results in a fivefold increase in this constant. Methylation of the terminal amino group, however, did not cause a corresponding increase and may not significantly affect equilibrium.