Microtomographic study of canal filling quality after post cementation in curved roots obturated with two different techniques

Aim. Clinicians appreciate simplified endodontic techniques since a lower number of instruments allows to spare operative time. For this reason, single-file reciprocating systems are gaining popularity. Furthermore, the filling procedure can be simplified by using gutta-percha points that match the shape of the last finishing instrument used. There is some evidence supporting the effectiveness of single point filling technique in mostly round canals, but it is still undemonstrated whether the post cementation can influence the filling quality in curved roots. The purpose of the present study was to assess the filling quality in curved roots obturated with the single point technique and restored with a fiber post; the continuous wave of condensation technique was used as reference. Materials and methods. Sample size was calculated based on previously published data (α=0.05; β=0.20; δ=3.0; σ=2.6). Consequently, a total of 26 roots was obtained by cross-sectioning single-rooted extracted teeth at the cervical level. Canal curvature was assessed according to the method of Pruett et al. (1997). Root canals were instrumented with Reciproc (VDW) up to size 40/.06, irrigated with 5.25% sodium hypochlorite and randomly assigned to two filling groups (n=13): G1, single point; G2, continuous wave of condensation technique. All canals were immediately prepared with a post drill and received a No. 2 DT Light Post Illusion X-RO (RTD) cemented with a self-adhesive cement (RelyX Unicem, 3M ESPE). Specimens underwent microtomographic scanning and volumetric data were analyzed for the calculation of filling volume, internal, external and combined voids. Data were statistically analyzed with a Student’s t-test. Three-dimensional reconstructions were created for qualitative assessment by means of dedicated software. Results. The mean filling percentage was 97.12 ±1.78% in G1 and 96.20 ±3.00% in G2. Very limited (<0.5%) amounts of internal and external voids were found, whereas greater amounts of combined voids were detected (2.46 ±1.90% in G1 and 3.55 ±3.00% in G2). There was no statistical difference between the two groups in relation to any volumetric parameter. Qualitative analysis showed almost absence of voids in the volume occupied by the cemented post, with the filling defects concentrating in the apical third where only gutta-percha and sealer were present. Conclusions. The combination of the two filling techniques with DT Light Post Illusion X-RO cementation allowed for effective filling of the canals, in accordance with the findings of previous studies on straight roots. Nevertheless, formation of a limited amount of voids was unavoidable, with an average of less than 5% of the whole canal remaining unfilled. Further studies are needed to assess the clinical relevance of the findings of the present study.