| Objective:This study aimed to complete the fabrication of individualized gutta-percha point with a high degree of confinement to the single thick root canal morphology using cone beam CT,Mimics software and 3D printing technology;By using Mimics reconstruction and calculating the volume of filling material to pulp chamber volume percentage,dye penetration and glucose penetration experiment,we initially evaluated the difference of filling quality between the filling of individualized gutta-percha point with warm vertical compaction technique and three other conventional root canal filling methods for root canal filling of single thick root canal isolated teeth,and analyzed the filling elapsed time of each group in order to provide a new idea for improving the quality of root canal filling.The experimental data were analyzed with SPSS software(version 26.0).Methods:66 single root canal isolated teeth with thick root canals were selected.The crown was sectioned at the neck of the tooth,then randomly divided into 4 experimental groups,positive and negative control groups.15 samples per group in the experimental group,and all samples from experimental groups were scanned with CBCT,reconstructed and printed with individualized gutta-percha point guides,which were used to create individualized gutta-percha point.Group A was filled with individualized gutta-percha point made with 3D printing technology by warm vertical compaction technique,group B was filled by conventional warm vertical compaction technique,group C was filled by single-cone obturation technique,and group D was filled by cold lateral compaction technique;In the control group,3 samples per group were filled by the single-cone obturation technique,but no root canal sealer was used,and the negative control group was recorded as group N and the positive control group was recorded as group P.The filling time of each experimental group was recorded and compared;CBCT and Mimics software were used to calculate the volume of filling material as a percentage of the pulp chamber volume in each experimental group;the filling effect of each experimental group was compared by dye penetration and glucose penetration.Results:1.Successfully fabricated individualized gutta-percha point through 3D printing and other technologies.2.Evaluation of the chairside operation time of individualized gutta-percha point filled by warm vertical compaction technique:When using individualized gutta-percha point for warm vertical compaction technique,the chairside root canal filling time can be effectively reduced.The chairside root canal filling time for the group of individualized gutta-percha point filled by warm vertical compaction technique is 150.60 ± 27.78 s,which was significantly lower than that in the conventional warm vertical compaction technique group(211.50±43.68s)and the cold lateral compaction technique group(728.50±53.15s),with a statistically significant difference(P<0.05);it was greater than that in the single-cone obturation technique group(85.53±17.49s),with a statistically significant difference(P<0.05).3.Evaluation of the filling tightness of individualized gutta-percha point filled by warm vertical compaction technique:(1)The percentage of the volume of filling material in the entire root canal to the volume of the pulp chamber was significantly greater in the group filled with warm vertical compaction technique using individualized gutta-percha point(99.45 ± 0.40%)than in the group filled with conventional warm vertical compaction technique(98.80± 0.42%),the group filled with cold lateral compaction technique(97.47 ± 0.67%),and the group filled with single-cone obturation technique(96.70 ± 0.68%).All differences were statistically significant(P < 0.05);(2)The percentage of the volume of filling material in the cervical 1/3 of the root canal compared to the volume of the pulp chamber(99.42±0.62%)was not statistically significant(P>0.05)in the group filled with warm vertical compaction technique using individualized gutta-percha point compared to the group filled with conventional warm vertical compaction technique(98.64±0.62%);it was significantly greater than that in the group filled with cold lateral compaction technique(97.06±1.02%)and single-cone obturation technique group(95.56±1.73%),with a statistically significant difference(P<0.05);(3)The percentage of the volume of filling material in the middle 1/3 of the root canal to the volume of the pulp chamber(99.66±0.19%)was not statistically significant(P>0.05)in the warm vertical compaction technique using individualized gutta-percha point compared with the conventional warm vertical compaction technique(99.29±0.20%);it was significantly greater than that in the cold lateral compaction technique(98.54±0.55%)and single-cone obturation technique group(98.16±0.84%),with a statistically significant difference(P<0.05);(4)The percentage of the volume of filling material in the apical 1/3 of the pulp chamber volume(99.10 ± 0.49%)was significantly greater than that in the group filled by the conventional warm vertical compaction technique(98.35 ± 0.57%),the group filled by the cold lateral compaction technique(96.63 ± 0.67%)and the group filled by the single-cone obturation technique(96.36 ± 0.67%),when using individualized gutta-percha point for warm vertical compaction technique,all differences were statistically significant(P < 0.05).4.Evaluation of the apical sealability of individualized gutta-percha point filled by warm vertical compaction technique:(1)The results of the dye micro-penetration experiments showed that the dye penetration length in the apical region(1.975 ± 0.296 mm)was not statistically significant(P > 0.05)compared with that of the conventional warm vertical compaction technique group(2.733 ± 0.496 mm)when the individualized guttapercha point was used for the warm vertical compaction technique;it was significantly greater than that of the cold lateral compaction technique filling group(6.446 ± 1.402 mm)and the single-cone method filling group(5.235 ± 0.841 mm),with a statistically significant difference(P < 0.05).(2)The results of the glucose microleakage experiment showed that the amount of glucose microleakage gradually increased in all groups as the time was prolonged;however,at the same time point,the amount of glucose microleakage in each group was in the order of smallest to largest in the group filled with individualized guttapercha point by warm vertical compaction technique,conventional warm vertical compaction technique,cold lateral compaction technique filling group,and singlecone method.On the first and fourth days,the differences in the amount of leakage between the groups were not statistically significant(P > 0.05);on the seventh day,the amount of microleakage of glucose in the filled with individualized gutta-percha point by warm vertical compaction technique group(0.1410 ± 0.0511mmol/l)was not significantly different from that in the conventional warm vertical compaction technique filling group(0.3151 ± 0.0963mmol/l)(P > 0.05),and was significantly smaller than that in the cold lateral compaction technique filling group(0.4310 ±0.3090mmol/l)and the single-cone filling group(0.5260 ± 0.1808mmol/l);the differences were statistically significant(P < 0.05);after the tenth day,the glucose leakage in the filled with individualized gutta-percha point by warm vertical compaction technique group was significantly smaller than that in the conventional warm vertical compaction technique filling group,the cold lateral compaction technique filling group and the single-cone filling group,and the difference was statistically significant(P < 0.05).Conclusions:1.Using technologies such as 3D printing to create individualized gutta-percha point is practical.2.The chairside root canal filling time can be effectively reduced when using a individualized gutta-percha point for warm vertical compaction technique.3.When filling coarse root canals with warm vertical compaction technique using individualized gutta-percha point,good tightness is obtained;especially in the apical 1/3 of the root,the tightness of filling is significantly better than the remaining three conventional filling methods.4.When the coarse root canals were filled with warm vertical compaction technique using individualized gutta-percha point,good apical obturation was obtained;with the gradual extension of time,its microleakage was significantly smaller than the remaining three conventional filling methods. |
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