In Vitro Post Cementation Using a Surgical Microscope

Objectives: The aim of this in vitro study was to quantify how a magnification system, as a dental operating microscope, could impact significantly on the post placement of endodontically treated teeth. Methods: A total of 10 single-root human teeth, extracted and preserved in a physiological salin solution were selected for the experiment. After endodontical treatment with Ni-Ti instruments and root canal filling with Thermafil® system, all samples were randomly allocated to two groups (n=5) and treated by a single operator. A three-step adhesive system (All Bond 2, Bisco Inc.) in combination with an auto-polymerizing resin cement (C&B, Bisco Inc.)  was used before a passive placement of fiber posts (EndoComposipost, RTD). In the first group (MIC), endodontical canal treatment and adhesive procedures were conducted with a direct visualization through a dental operating microscope (Carl Zeiss, Inc.). In the second group (EYE) the same type of protocol was conducted  with the traditional ‘naked eyes’ technique.The comparison between the two kind of approaches was carried out by means of a Pull-Off Test and fracture surfaces were characterized using stereomicroscope. Statistical analysis was performed applying ANOVA and Fisher’s PLSD test.Values were calculated in daN. Results: MIC group had significantly higher mean pull-out load (16,58 daN) than the other test EYE group (3,94 daN). Standard deviation detected was 7,98 for MIC group and  2,09 for EYE group.Variance analysis reflected a significant statistic difference between the two groups in order with the procedure used (p<0.05). MIC group showed 4 post-fractures and 1 fracture at adhesive-interface. EYE group revealed only adhesive surface decementations. Conclusions: Adhesive luting of posts, realized with the traditional naked eye technique, did not point out a good adhesion at adhesive-dentine interfaces.The operating microscope enhances the operator’s ability in post placement, as confirmed by higher pull-off force values showed in MIC group.