Nikolov V. Comparative analysis of different techniques of preparation of supporting teeth with ruined crown for fixed porcelain fused metal dentures.

The thesis is devoted to the studies of the efficiency enhancement of patients’ dentoprosthetic rehabilitation with fixed porcelain fused metal constructions in terms of comparative analysis of temporary marginal gingiva retraction methods in case of partial and full tooth crown destruction. Based on the conducted literature review, the first research objective was formulated and achieved. It was directed to the development of the set of active electrodes of authorial construction. Further clinical research was carried out in two sample groups of patients (n=54). Sample group 1 (n=29, 53.7% of the total examined cohort) was made up of the patients, whose supporting teeth gingiva margins were retracted with the help of diathermocoagulation. Sample group 2 consisted of 25 patients (46.3%). Their gingiva margins were retracted with the help of chemical-mechanical technique. The impact of chemical-mechanical retraction and diathermocoagulation on gingiva mucous membrane state was compared on the basis of its microscopy results. It was carried out with the help of the technique of the locating of oral cavity mucous membrane inflammation at the prosthodontic rehabilitation stage (2014 by D. Korol et al). Index evaluation of oral cavity hygienic state and the determination of mucous membrane inflammation ( Sillness J.–Loe H. Index) (Dental Plaque Index) and Shiller–Pisarev Probe (Svrakov’s Index). Thermography of mucous membrane and tooth hard tissues was conducted with the use of thermal camera FLIR ThermaCAM T360. Masticatory efficiency state after prosthodontic rehabilitation was determined with the help of masticatory test according to Ukrainian Utility Patent # 94841 dated from 10 December, 2014. Based on the carried out statistical analysis and summarising of clinical investigation we concluded as follows. According to microscopy results of marginal mucous membrane in 7-day period after porcelain fused metal denture fixation significant increase of mean values of red colour median was fixed in both sample groups. It is the evidence of gradual decrease of hyperemia signs. General regeneration trend had preserved by the thirtieth day after denture fixation. It is indicated by the decrease of graphic signs of mucous membrane hyperemia. This process had brighter manifestations in sample group 2. Index monitoring results have appeared to be statistically comparable and proved that porcelain fused metal denture fixation provides positive effect on hygienic state of prosthesis area and reduces the intensity of mucous membrane inflammation response in the retraction area in the patients of both sample groups. Thermography of mucous membrane and tooth hard tissues over time showed that in spite of the significant temperature prevalence observed at diathermocoagulation directly after its application, regenerative processes in long-term period in the representatives of both sample groups unfolded similarly without any significant statistic difference. Masticatory efficiency determination in patients of both sample groups fixed this index improvement. Statistically grounded reduction of numeric values of masticatory test on the seventh day in both sample groups proves this trend. Almost the same masticatory efficiency was preserved on the 30th day of porcelain fused metal crowns fixation. Thus, it has been proved that the retraction method of marginal gums at the preparatory stage does not influence significantly the dynamic masticatory restoration over investigation. Summing up, we can insist on the efficiency of diathermocoagulation method of supporting teeth preparation when they require prior restoration followed with the manufacturing of fixed porcelain fused metal dentures. It was verified with the help of the carried out clinical, paraclinical and statistic research methods.