Safety Assessment of Two Hybrid Instrumentation Techniques in a Dental Student Endodontic Clinic: A Retrospective Study.

The aim of this study was to retrospectively assess the safety potential of a hybrid technique combining nickel-titanium (NiTi) reciprocating and rotary instruments by third- and fourth-year dental students in the predoctoral endodontics clinic at one U.S. dental school. For the study, 3,194 root canal treatments performed by 317 dental students from 2012 through 2015 were evaluated for incidence of ledge creation and instrument separation. The hybrid reciprocating and rotary technique (RRT) consisted of a glide path creation with stainless steel hand files up to size 15/02, a crown down preparation with a NiTi reciprocating instrument, and an apical preparation with NiTi rotary instruments. The control was a traditional rotary and hand technique (RHT) that consisted of the same glide path procedure followed by a crown down preparation with NiTi rotary instruments and an apical preparation with NiTi hand instruments. The results showed that the RHT technique presented a rate of ledge creation of 1.4% per root and the RRT technique was 0.5% per root (p<0.05). Three stainless steel hand files separated: two in the RHT group and one in the RRT group. There was no separation of any NiTi file in any of the techniques. The use of the reciprocating and rotary technique for root canal instrumentation by these dental students provided good safety. This hybrid technique offered a low rate of ledge creation along with no NiTi instrument separation.

Periapical microsurgery: an in vivo evaluation of endodontic root-end filling materials.

The purpose of this study was to assess the healing of periapical tissues using three different materials (IRM [L.D. Caulk Inc, Dentsply International Inc, Milford, DE], Geristore [Den-Mat, Santa Maria, CA], and MTA [ProRoot MTA; Dentsply Tulsa Dental Specialties, Tulsa, OK]) after endodontic microsurgery in an animal model. Using beagle dogs as a study model, 48 bicuspids were accessed, instrumented, and intentionally infected. The surgical procedures were performed after 30 days following the radiographic confirmation of periapical radiolucencies. The root canals were still infected and had no disinfection procedure carried out. The root ends were resected, retrograde preparations were completed, and the experimental materials were placed under surgical operating microscopy. After a period of 6 months, digital radiographic images of the periradicular areas were taken. The samples were prepared for histologic evaluation. Although Geristore showed no radiographic difference when compared with the other groups, it showed the least favorable healing in the histologic evaluation. Our histologic and radiographic results showed no statistical difference between MTA and IRM.