The dissertation focuses on increasing the efficiency of treatment of patients with dental discolorations through the substantiation of a complex of actions based on the improvement of clinical and laboratory researches with the application of indirect restorations – ceramic veneers.
Quite often change of teeth colour is a reason of smile aesthetics disturbanceand most of all it’s caused by discoloration, which compiles 15% of overall dental pathologiesstructure and its occurrence in young patients is up to 89%. Nowadays, ceramic veneers are a real alternative for all porcelain andporcelain fused to metal crowns. By using ceramic veneers, person's smile, appearance, self-esteem, image and psychological condition could be changed ratherquickly, while keeping teeth preparation minimal.
We found that pathological changes in the tissues of the oral cavity in patients with discoloration occur more often than in the comparison group, and their number increases in proportion to the patient’s age. The main causes of discoloration were caries and its complications (teeth restored with fillings and restorations), as well as discoloration of teeth under the influence of endodontic pastes (adverse effects after endodontic treatment) – deep/severe discoloration and traumatic damage to teeth.
Electron microscopic examination revealed that the enamel is partially fragmented in acquired discoloration, and there are signs of lysis represented by the formation of small multiple cavities in place of enamel prisms. The lacunae were traced at the enamel-dentin boundary, and the enamel gaps were filled with amorphous substance. On the periphery, there were focal moderately pronounced demarcation bands, the phenomena of «differentiation» were determined due to a decreased expressiveness of enamel prisms.
As shown by the results of the study, the adhesive strength of the first sample fixed on composite cement Calibra and prepared by the classical method was 18.82 ± 0.4 MPa; for the second sample, prepared by the technique of «inlay in the veneer» and fixed on the same material, it was increased by 51 %. The application of the technique of fixing classically prepared teeth for veneers on a heated composite Gradia Direct resulted in the strength of 32.3 MPa. When conducting a comparative analysis with the first sample, we detected an increase in the fixation strength by 71%, and in comparison with the second one – only by 14 %. The adhesive strength of the fourth sample, which was prepared by the suggested «inlay in the veneer» design and fixed on the heated composite Gradia Direct, was 46.5 MPa, which was by 147 % higher than in the first sample, by 64 % than in the second sample and by 44 % than in the third one.
The absence of significant differences in the levels of pro-inflammatory cytokines after 12 months in the groups of indirect restorations suggests that there are no inflammatory phenomena in the marginal periodontium and indicates the absence of antigenic load due to the biocompatible value of dental materials. This proves the possibility and advantages of using the technique of fixing veneers on the heated composite, which can serve as an alternative to composite cements.
According to the criteria for assessing the state of restorations by USPHS, the following results were established. 28 % of restorations of the first group, 55.7 % of the second group, 85.5 % of the third group received a grade of «excellent». 33.6 % of restorations in the first group, 25.7 % in the second group, 5.5 % in the third group received a grade of «good». 11.2 % of restorations in the first group, 11.7 % in the second group, and 5.4 % in the third group were graded as «satisfactory». 27.2 % of restorations in the first group, 11.4 % in the second group, and 3.6 % in the third group needed immediate replacement. The total score for the first group was 3.8, for the second group – 4.3, for the third group – 4.7.
Thus, our studies of direct and indirect restorations after a year of use showed that the highest level of quality, especially color stability, was observed in the group where veneers were made and fixed on the heated composite.
