A Study On Effect Of Premolars With Single Root Canal Of 13～23 Years Old Filled With Four Techniques In Vitro

Researches showed that premolars with single root canals of young group were mostly oval-shaped and thick, the studies of oval-shaped root canals focused on a number of small and narrow root canals, while the preparation and filling of thick oval-shaped root canals were less at present, so the aim of this study was to compare the percentage of gutta-percha- filled area (PGFA) achieved in thick oval-shaped root canals filled with different techniques after were instrumented with ProTaper, it could provide the basis for clinical treatment for this type of root canals, for example, the teeth of abnormal central cusp were abraded.Objective The aim of this study was to compare the PGFAs achived in premolars with single root canals of young patients filled with four different techniques.Methods Four groups of extracted premolars with single root canals of 13~23 years old (totally 40, n=10) were instrumented with ProTaper, then the root canals were filled as follows: cold lateral condensation, injectable thermplasticized gutta-percha ( Obtura-Ⅲ), continuous wave of condensation (SystemB+ObturaⅢ) and modified continuous wave of condensation which is combined the cold lateral condensation (modified Syste- mB+ObturaⅢ) . Cross sections of each tooth were made 2mm,5mm and 8mm from the apex. The samples were prepared for microscopic analysis. Digital image measure - ments of the cross-sectioned area of the canal and the gutta- percha were performed wit- h image analysis program AutoCAD2004 and the PGFAs were calculated. Results 1 A comparison of between four groups: at 2mm from the apex,the PGFAs of cold lateral condensation,injectable thermplasticized gutta-percha, continuous wave of condensation and modified continuous wave of condensation were (90.18±7.30)%, (93.47±6.99)%, (81.95±9.80)% and (87.81±8.13)% respectively, but no significant differences were found between them(P >0.05); At 5mm from the apex, the PGFAs of four groups were (85.97±5.96)%, (96.79±3.57)%, (98.84±1.53)% and (93.84±4.72)%, the last three thermplasticized gutta-percha techniques produced significantly higher PGFAs than the cold lateral condensation (P<0.05), but there were no significant differences between ObturaⅢ,SystemB+ObturaⅢand modified SystemB+ObturaⅢ(P>0.05); At 8mm from the apex, the PGFAs of four groups as follows: (76.64±12.17)%,(97.80±4.99)%,(99.65±6.07)%and (97.24±7.51)%, the result of 8mm was the same as 5mm from the apex, the thermplasticized gutta-percha techniques produced significantly higher PGFAs than the cold lateral condensation(P<0.05), but there were no significant differences between them (P >0.05).2 A comparison of within four groups: there were significant differences between 2mm and 8mm from the apex of cold lateral condensation,the PGFAs of continuous wave of condensation and modified continuous wave of condensation groups showed significant differences between 2mm and 5mm , 2mm and 8mm from the apex (P<0.05),but between other cross sections have no significant differences (P>0.05).Conclusion In this study, the result of premolars with single root canals of 13~23 years old filled on this experimental conditions was that there were no significant differences on the apical third, but the last three thermoplasticized gutta-percha techniques were more effective than the cold lateral condensation in filling upper parts , particularly recommended to use injectable thermplasticized gutta-percha techniques.