Abstract:

Abstract:Objective  To evaluate the   adaptability of gutta percha  point to curved root canals prepared by rotatory nickel titanium(NiTi)instruments,and to investigate the best effect of the adaptability of gutta percha point  and the wall of curved root canals.Methods The plastic curved root canal models were randomly divided into 8 groups.Four groups were named MTwo group,and the other groups were named Sendoline group.They were respectively prepared to 0.06/20#,0.06/25#,0.04/35#,0.04/40#,and 004/20#,0.04/25#,0.04/30#,0.06/30#.All of these models were filled using the single-cone technique.After a week,the models were cutted from the apical foramen to 1,2,3,4,and 5 mm perpendicularly to the model with low speed diamond saw.Photographs were taken using microscope.The filling rates and the widths of the gutta percha point were measured by drawing software.Results The filling rates of gutta percha  point  were minimal at 1 mm section from the apical foramen.The closer it reached the apical foramen,the bigger the  filling rates were seen.The filling rates in various groups at apical section were maximum at 5 mm section from the apical foraman.The filling rates were  decreased and the widths of the gutta percha point were increased with the increasing of the number of gutta percha point.When the root canals were prepared to <30#,the filling rates and the widths  had no significant differences (P>0.05).When the root canals were prepared to ≥30#,the filiing rates in 0.04/35# group and 0.04/40# group at apical section were decreased compared with 0.04/30# group(P<0.05).There were significant differences at 1 and 4 mm sections and there were no significant differences at 2,3,and 5 mm sections in 0.04/40# group compared with 0.04/35# group(P>0.05).The width of the gutta percha point at apical section of 0.04/35# group was increased compared with 0.04/30# group and there were no significant differences at 1,2,and 3 mm sections(P>0.05) and there were significant differences at 4 and 5 mm sections(P<0.05) between 0.04/30# group and 0.04/35# group.The width of the gutta percha point at apical section in 0.04/40# group was increased compared with 0.04/30# group and there was no significant difference at 3 mm section(P>0.05) and there were significant differences at 1,2,4,and 5 mm sections(P<0.05) between 0.04/30# group and 0.04/40# group.The width of the gutta percha point  at apical section in 0.04/40# group was increased compared with 0.04/35# group and there was significant difference at 1 mm section(P<0.05) and there were no significant differences at 2,3,4 and 5 mm sections(P>0.05) between 0.04/35# group and 0.04/40# group.Compared with   0.06 taper groups with the same number，the gutta percha point in 0.04 taper groups had bigger filling rates and smaller widths,but there were no significant differences between them(P>0.05).Conclusion  When the root canals are prepared to <30#,the adaptability of  gutta percha point  to curved root canals is the best,and the filling effect is the  best.

Key words: curved root canal, single-cone technique, rotatory nickel titanium, adaptability