Effect Of Types Of Lentulo On Post Impression

Objective:The aim of this stud was to evaluate the effect of types of lentulo the numble of root canals and operator's skill on the success rate of post impression.Methods:Two human premolars with one root canal and two root canals were used in this experiment. The crown was removed along the cemento-enamel junction using low-speed saw (Isomet 1000, Buehler, USA) under water cooling. The root canals were preparated and filled as usual. The gutta percha within the the root canal at apex should be left 3-5 mm, and the other gutta percha within the root canal was removed by a serial of Peeso Reamer (#1～#3 or #1～44). The width of the post preparation should not exceed the one-third diameter of the root, and the length of the post preparation was about three-fourths of the root. Four types of lentulo (#25,#30,#35,#40, Mani, Japan) were used in the study. A dental graduate student, a dental postgraduate student and a well-trained dentist took part in the experiment. Ten post impressions for a post preparation with a type of lentulo were taken by the participants. Eighty post impressions were taken by a participant. The quality of the impression was described as follows:excellent:the impression was complete without any defect or bubble; acceptable:The small bubbles or defects on the surface of post impression were not more than 0.5 mm2; the partial defect:The small bubbles or defects was between 0.5 mm2 and 1.0 mm2; failure:there was a defect at the root of the impression or the total defect area was larger than 1.0 mm2.Results:The impression success rate of single root canal was significantly higher than that of two root canals (P＜0.05). There was no significant difference of the impression success rate among the participants (p>0.05). The lentulo (#40) was worse than that (#25,#35) regarding the impression quality (P＜0.05). No significant difference could be found between the other groups (P> 0.05). The lentulo (#35) got the highest success rate for the post impression. Conclusions:1. The number of root canals can influence the success rate of post impression.2. The lentulo (#40) was not recommedated to be used for the post impression of the premolars. The lentulo (#35) was suggested to be used for the post impression of the premolars.