Dissertation for a Candidate-of-Medicine degree (PhD) in Specialty 14.01.22 – Dentistry. Shupyk National Medical Academy of Postgraduate Education, Ministry of Health of Ukraine, Kiyv, 2020.
In the dissertation we have studied the prevalence rate of the intolerance to dental metal alloys, supplemented the scientific data on using the different methods to make the casted combined fixed aesthetic dental prostheses. The results of using the different types of orthopaedic constructions were analysed for a long time after prosthetic care. We have proposed the improved methodology and stages to produce the fixed partial dentures using the dental alloys made of base metals by creation on the metal part of dental prosthesis the passivating dielectric biocompatible layer of ZrO2. It allows us to increase the resistance of dental metal alloys to corrosion, to improve their mechanical and bio-inert properties, to refine the aesthetic features of the construction, to eliminate the toxic effects on the mucus membrane and periodontium, to carry out the minimal preparation of hard tissues of vital teeth in the tooth cervical area and to use them for replacement of the dentition defects.
By using the experimental methods in aggressive conditions, we have studied the corrosion resistance of bio-inert coating of ZrO2 and proved its efficiency. The clinical methods substantiate the physical and mechanical features of cobalt-chromium and nickel-chromium alloys with bio-inert coating and the advantages of the specified constructions over the traditional casted fixed partial dentures. We have supplemented the scientific data that using the casted combined orthopaedic constructions with a protective bio-inert coating of ZrO2 would be effective in the case of intolerance to metal alloys and galvanosis reaction.
We have examined and performed orthopaedic treatment of 150 patients to achieve the set goals and the purpose of our work. The study groups included 100 patients aged 20-55, who were 58 women and 42 men. We divided the examined patients into the following groups: the first group (I) included 60 patients for whom the fixed partial dentures were made. Subgroup 1A included 30 patients with swaged and soldered fixed partial dentures. Subgroup 1B included 30 patients with combined fixed partial dentures. The second group (II) includes 20 patients with combined metal-ceramic fixed partial dentures with the proposed protective zirconium dioxide (ZrO2) coating. The third group were 20 patients with fixed aesthetic dental prostheses based on zirconium dioxide.
When examining the patients with galvanosis reaction and intolerance to metal alloys, we should take into account subjective examination methods and apply galvanometric methods, study the acidity and viscosity of the fluid in the oral cavity before a medical treatment and for a long time after the treatment. We recommend using the oral hygiene index and analysis of the degree of inflammation of the marginal periodontium and oral cavity to assess the periodontium condition of abutment teeth.
Among the examined patients who came to teaching clinical unit with complications in the use of the fixed partial dentures, 63 of them (42.0%) had symptoms of galvanosis and intolerance to metal alloys. In performing the work, we applied subjective and objective methods of examination while paying attention at the state of the marginal periodontium and hard tooth tissues. When using the casted combined fixed partial dentures with a proposed coating of ZrO2, we can observe a significant improvement in clinical indexes of PMA and Silness-Löe, galvanometric indexes and pH of the fluid in the oral, for a long time.
Having analysed the results of the conducted research, we can argue that the patients of the second group (II), who were proposed the orthopaedic constructions made of cobalt-chromium and nickel-chromium alloys together with a protective bio-inert coating of ZrO2, had the indexes of periodontal tissues close to those we observed in patients of the third group (III) with metal-free constructions and there was a significant improvement in the indexes of PMA, Silness-Löe and Schiller-Pisarev’s test.
In terms of clinical production stages, clinical indexes of the periodontium condition of abutment teeth, galvanometric indexes, the proposed fixed dental construction has significant advantages over commonly used fixed aesthetic constructions and under its bio-inert features, it is as close as possible to the constructions made of zirconium dioxide.
Key words: dentition defects, metal alloys, galvanosis, zirconium dioxide, casted combined fixed partial dentures.
