Evaluation of coronal and apical microleakage and the effect on failure of endodontic treatment

The three-dimensional hermetic root canal obturation that implies sealing of the apical and the coronal part of the tooth, presents one of the conditions for successful prognosis for endodontic therapy in case of pulp inflammation. The goal of this dissertation is to evaluate and determinate the influence of the coronal, and apical microleakage in etiology of periapical pathosis, as well as their part in the failure of the endodontic therapy. Objects of this research were also the specific aims: Determining the coronal microleakage of temporal and permanent restorations (valorization of the linear ink penetration), Determining the microbiological coronal microleakage of temporal and per-manent restorations (penetration of the bacteria Proteus mirabilis), Determining the microbiological apical microleakage in cases of teeth with pe-rapical pathologic lesions, Comparation of the x-ray and the histological intercanal obturation, Determining the role of the technical quality of the canal obturation on the apical microleakage, Verification of the effect of the coronal microleakage on the periapical post-endodontic status. In function of realization of the established aims the experimental object was constructed in three parts. In the first part we determinated the coronal microleakage of ink and the Proteus mirabilis bacteria on 240 one rooted human teeth in in vitro conditioned terms. After the endodontic treatment and the intercanal obturation according two gutta-percha techniques: classic and thermafil, the coronar restorations were realized with temporal material Caviton and permanent filling: composite resin and dental amalgam. Prepared in this manner, the samples were put 20 of each group in ink during seven days period. The rest 20 teeth of each group were sterilized and put in Proteus mirabilis bacteria suspension. In the further procedure the teeth were decalcified and prepared for histological evaluation of the microleakage. The bacteria penetration was determinated on longitude histological sections colored with Brow-Bernn. The second part was consisted of 90 human in vivo endodontic treated teeth, with x-ray verified periapical lesions, indicated for extraction. Depending on the marginal integrity of the coronal restoration and the technical quality of the intercanal obturation, the samples were categorized in three groups and on horizontal histological sections of the apical third the bacterial presence was established. The third part was performed on experimental animals-dogs. Endodontic therapy treatment was performed on 20 incisors, and the coronal temporal cavities were obtured with Caviton (10 teeth) as well as composite resin (10 teeth). Control Rtg for analysis of the periapical conditional state were conveyed after the therapy and after 3 and 6 months as well. The statistic analysis of the received results was realized using the Statistica-for Windows -6 program. The coronal microleakage of ink and bacteria was verified in in vitro conditions in all tested groups. Statistically significant differences were valorized in the ink diffusion in the cases of the permanent as well as the temporal coronal restoration materials. Bacteria penetration with biggest intensity was registered with the temporal restored cavities. The technique of the root canal obturation statistically does not influence the coronal microleakage.. The technical quality of the coronal restoration as well as the canal obturation in case of the in vivo treated teeth with periapical lesions, are in relation with the apical bacteria conta-mination. The x-ray determinated continuity of the intercanal obturation does not match com-pletely with the histological apical evaluation. Using the in vivo conditioned terms with the experimental animals 3 months after the en-dodontic therapy, the surface of the average periapical lesions of the teeth that were previously coronal sealed with temporal material as well as with composite resin were statistically sig-nificant different.. After a 6 month period, the permanently restored teeth reacted with digression of the surface of the periapical lesions. On the basis of the conveyed researches and the received acknowledgements we suggest that the success of the endodontic therapy in cases of pulp inflammations is limited by the sum of actions that follow one another and equally participate in the procedure of the treatment. The coronal and apical microleakage both of them, influence of the prognosis and can also lead to periapical inflammation. But in the success of the endodontic therapy also partici-pated other factors such are: root canal preparation, cleaning, shaping, removed of smear layer, and individual immunological properties. After the three-dimensional hermetic root canal obturation during the pulp inflammation therapy, permanent coronal restoration follows, on indifferent basis, best from the group of the glass-ionomer cements. The time of application of the coronal obturation over the oroficium, and the success rate of the endodontic act as far as the prognosis, crucially determines the survival of the dental organ in the oral environment. Key words: microleakage, linear penetration, diffusion, orofisium, endodontic treatment, root canal obturation, root canal sealer, thermafil gutta-percha, coronal restavration