Sealing Ability Of Single Cone Obturation Technique With IRoot SP In Oval Root Canals:A Vitro Study

Objectives: The aim of this study was to evaluate the sealing effect of single cone obturation technique with iRoot SP in oval root canals,in order to provide further reference for the clinical application of single cone obturation technique with iRoot SP and the selection of filling method in oval root canals.Methods: 1.Samples collection,grouping,and processing:a total of 129 oval singleroot canal teeth were collected and crowns were amputated from all samples,standardizing the length of roots to 14 mm.Root canal preparation: Protaper Universal was used to shaped the root canals from a size of SX to F3,the canals were irrigation with 3% sodium hypochlorite and 5ml 17% ethylene diamine tetraacetic acid by ultrasonic therapy instrument for 1 min,following a final flush with 5ml 0.9% saline water,then stored in saline water.The specimens were randomly distributed into 3 groups according to the filling method(n = 43):group A(warm vertical compaction obturation with AH Plus),group B(warm vertical compaction obturation with iRoot SP),and group C(single cone obturation with iRoot SP).2.13 samples were selected randomly from each group for micro computed tomography scanning and three-dimensional reconstruction.The volume proportion of viods and filling materials in the whole root canal,cervical 1/3,middle 1/3 and apical 1/3 of the root canals were measured and calculated.3.15 samples were selected randomly from each group for confocal laser scanning microscopy scanning.The maximum penetration depth,mean penetration depth and the percentage of penetration area of sealers in the dentinal tubules at2 mm,5 mm and 8 mm from the apical were measured and calculated.4.15 samples were selected randomly from each group for apical dye leakage evaluation and transparent teeth preparation.The depth of dye penetration was observed and measured by stereomicroscope.5.Data were analyzed using SPSS 21.0 software(P = 0.05).Results: 1.The reconstructed images of micro computed tomography showed that viods existed in all of the three root canal filling methods.The viods were discontinuously distributed along the root canal,concentrated in the cervical 1/3 and apical 1/3 of the root canal.The percentage of viods volume in the cervical 1/3 of the root canal in group C was significant higher than that in group A,however,lower in the middle 1/3 and apical 1/3 of the root canal(P < 0.05);the percentage of viods volume in the whole and cervical 1/3 of the root canal in group C was higher than group B(P < 0.05);the percentage of viods volume in the whole and apical 1/3 of the root canal in group B was lower than that in group A(P < 0.05).2.The CLSM images presented that sealers were radially distributed along the dentinal tubules from the root canal wall to the root surface,which concentrated unevenly in the mesiodistal or buccolingual directions and was close to the root surface at a distance.For the maximum penetration depth of sealers in dentinal tubules: group C was longer than group A at 2 mm and 5 mm from the apical(P < 0.05)but shorter than group B at 8 mm from the apical;group B was longer than group A at 2 mm from the apex(P < 0.05).For the mean penetration depth of sealers in dentinal tubules: group C was larger then group A at 2mm and 5 mm from the apical(P < 0.05);group B penetrated more than group A at 2 mm from the apical(P < 0.05).For the percentage of penetration area of sealers in dentinal tubules: group A was lower than both group B and group C at 2 mm,5 mm and 8 mm from the apex(P < 0.05).3.Apical dye penetration happened in all groups while group C contributed the smallest in such situation(P < 0.05).Conclusions: 1.Viods existed in all three root canal filling methods inevitably.Warm vertical compaction obturation with iRoot SP showed the best sealing effect in the whole root canal.2.Although more viods were produced in cervical 1/3 of the root canal by single cone obturation with iRoot SP,it showed the similar excellent sealing effect to warm vertical compaction obturation with iRoot SP in the middle and apical parts of the root canal,which was better than warm vertical compaction obturation with AH Plus.3.iRoot SP had better penetration ability in dentinal tubules than AH Plus.