بررسي مقايسه اي ميزان انحراف آپيكال متعاقب استفاده از سه نوع وسيله روتاري به روش كارخانه و يك روش اصلاح شده

Comparison of apical transport in three rotary systems and one modified technique

Background and Aim: Procedural errors such as canal transportation and loss of working length are mainly associated with stainless steel files with insufficient flexibility. Apical transportation may also be attributed to the cutting or non-cutting tip of rotary instruments. The aim of this investigation was to compare apical transportation in three types of rotary instruments (Hero642, Race and K3) using manufacturersʹ guidelines and a modified technique. Materials and Methods: Extracted maxillary or mandibular mesiobuccal roots of permanent human molars with a length of 19-23 mm and curvature between 20 - 40 degrees (according to the Schneider method) were studied. The initial patency of the experimental canals were at least #10 and maximum 15. The samples were divided into six groups of twenty canals. In the first three groups; canals were instrumented using rotary systems according to the manufacturerʹs guidelines whereas in the 4th, 5th and 6th groups, prior to the instrumentation with rotary instruments, apical patency with *15 k hand file, 1-3 gates gliden, #2 peeso reamer and a full passive step back technique were used to create a better access to corona] and middle parts of the canal (modified technique). Statistical analysis was performed using Variance, Duncan and t - tests. Results: The mean degrees of apical transportation among groups instrumented according to the manufacturerʹs guidelines with Hero, Race and K3 rotary instruments were 2.79±1.12, 2.21+1.37 and 1.65±0.79, respectively and in samples instrumented with the modified technique 2.64±1.54, 2.10±1.40 and 1.93±1.23 degrees of apical transportation were recorded in Hero, Race and K3 instruments, respectively. There was a statistically significant difference between the first three groups (P<0.05) that were instrumented according to the manufacturerʹs guidelines, but no statistically significant difference was found in apical transportation between the modified technique groups and the manufacturer guideline groups (P>0.05)Conclusion: The use of modified technique, although leads to much easier instrumentation procedures, has no significant effect on the reduction of apical transportation degree as com- pared with the manufacturerʹs recommended method.