Raffaele Paragliola

Final Rinse Optimization: Influence of Different Agitation Protocols

INTRODUCTION This study examined the effect of different root canal irrigant agitation protocols in the penetration of an endodontic irrigant into dentinal tubules. METHODS Fifty-six human single-rooted teeth were shaped with nickel-titanium instruments, and a final rinse of 5% sodium hypochlorite labeled with 0.2% alizarin red was performed. Specimens were assigned to 7 groups (N = 8) and submitted to the following rinse activation protocols: no agitation (control group), K-File or gutta-percha agitation, or different sonic (EndoActivator [Advanced Endodontics, Santa Barbara, CA] and Plastic Endo, Lincolnshire, IL) and ultrasonic (Satelec [Acteongroup, Merignac, France] and EMS, Nyon, Switzerland) agitations. Specimens were sectioned at 1, 3, and 5 mm from the apex in 1-mm-thick slabs, ground, and prepared for fluorescence microscopy at 100x with a wavelength of 450 milliseconds. Irrigant penetration into dentinal tubules was analyzed by using Kruskal-Wallis analysis of variance followed by post-hoc comparisons. RESULTS Groups were ranked in the following order: control = K-file = gutta-percha < EndoActivator = Plastic Endo < Satelec = EMS. At 1 mm from the apex, the highest score was found for the EMS group compared with the control, K-file, gutta-percha, EndoActivator, and Plastic Endo groups, whereas no difference was found with the Satelec group. CONCLUSION The results support the use of an ultrasonic agitation to increase the effectiveness of the final rinse procedure in the apical third of the canal walls.

Efficacy of two Ni‐Ti systems and hand files for removing gutta‐percha from root canals

AIM   To compare the effectiveness of two Ni-Ti systems and hand files for removing gutta-percha and sealer from root canals. METHODOLOGY   The root canals of 60 single-rooted human teeth were prepared, filled with gutta-percha and sealer (Pulp Canal Sealer; SybronEndo, Orange, CA, USA). Specimens were then divided into three groups (n=20), and root filling material was removed using MTwo Retreatment Files (group 1); R-Endo (group 2); K-files and Gates-Glidden drills (group 3). After retreatment, the efficacy of each technique was assessed using radiographs that were later digitized and the images analysed using AutoCAD 2004. The percentage of residual gutta-percha was calculated for the whole canal as well as for the coronal, middle and apical thirds. Time required, apically extruded debris and the number of fractured instruments were also recorded. Data were statistically analysed using Kruskal-Wallis and Mann-Whitney U-tests. RESULTS   All instrumentation techniques left gutta-percha and sealer remnants inside the root canals. Ni-Ti systems were significantly faster (P < 0.05) than the manual technique and significantly more effective (P < 0.05) in removing gutta-percha particularly from the middle and apical thirds of the root canal. R-Endo instrumentation was significantly more effective (P < 0.05) than MTwo retreatment files in removing gutta-percha from the middle and apical thirds. R-Endo instruments were associated with the least number of cases of apical extrusion. One MTwo instrument fractured. CONCLUSIONS   The Ni-Ti systems were more effective and faster than hand files, although all techniques left gutta-percha and sealer remnants on the root canals.

Comparison of Two Techniques for Assessing the Shaping Efficacy of Repeatedly Used Nickel-Titanium Rotary Instruments

INTRODUCTION The shaping capacity of nickel-titanium (NiTi) rotary instruments is often assessed by photographic or micro-computed tomography (micro-CT) measurements, and these instruments are often used more than once clinically. This study was conducted to compare photographic and micro-CT measurements and to assess if the repeated use of NiTi instruments affected the shape of canal preparation. METHODS Ten new sets of ProTaper Universal instruments (Dentsply-Maillefer, Ballaigues, Switzerland) were used in 60 resin blocks simulating curved root canals. Groups 1 to 6 (n=10) represented the first to sixth use of the instrument, respectively. Digitized images of the prepared blocks were taken in both mesiodistal (MD) and buccolingual (BL) directions and area measurements (mm(2)) were calculated using AutoCAD (Autodesk Inc, San Rafael, CA). The volumes of the same prepared canals were measured using micro-CT (mm(3)). Statistical analysis was performed to detect differences between photographic and volumetric measurements and differences between uses. RESULTS Two-way repeated-measures analysis of variance revealed significant differences between groups (P < .001). Regarding measurement type, there were no significant differences between BL and MD measurements, but there were significant differences between micro-CT and BL measurements (P < .001) and micro-CT and MD measurements (P=.001). Significant differences were also noted between uses. CONCLUSIONS Within the limitations of the present study, micro-CT scanning is more discriminative of the changes in canal space associated with repeated instrument use than photographic measurements. Canal preparations are significantly smaller after the third use of the same instrument.

Evaluation of the fracture resistance of reattached incisal fragments using different materials and techniques

OBJECTIVES When coronal fracture occurs in anterior teeth, fragment reattachment can be a valid alternative to a direct restoration. The aim of this study was to evaluate the influence of the material and the technique used to reattach the fragment. MATERIALS AND METHODS Eighty sound maxillary and mandibular incisors were selected and randomly divided into eight groups (n = 10). The incisal third of each tooth was removed using a saw machine. The fragments in groups 1-4 were reattached using resin-based materials: group 1 adhesive, group 2 flow, group 3 composite, group 4 cement; in groups 5-8, the same materials mentioned before were used but a bevel was also performed on both labial and lingual surfaces. Shear bond strength (SBS) was calculated by applying a load incisal to the reattachment line. A two-way Anova was used to evaluate the influence of materials and techniques on the SBS. RESULTS The technique used was statistically significant (P < 0.001), while the material was not (P = 0.793). CONCLUSIONS The choice of material seems to have no influence on the SBS, whereas a bevel performed on the labial and lingual surfaces can significantly improve the SBS of the reattached fragment.