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State of the art endodontic surgery with controlled retrograde procedures may not be feasible in all teeth due to poor access and other technical difficulties. In selected cases, the possibility to perform the sole apical resection without further retrograde manoeuvres might constitute a substantial clinical advantage. The present study compared the filling quality obtained with standard retrograde procedures with that of an alternative technique without retrograde preparation and filling. Methods: Previously published data served for sample size calculation (α=0.05; β=0.20; δ=3.0; σ=1.5). Twelve single-rooted teeth were selected from a pool of freshly extracted teeth, discarding those with aberrant anatomy. Selected teeth of comparable size were decoronated to obtain 12 mm long roots. The canals were scouted with manual files and the working length acquired. After mechanical glide path establishment, canal shaping was performed with HyFlex rotary files up to size 40, .04 taper (500 rpm; 2.5 Ncm). The roots were analysed with a computed microtomography scanner to identify the possible presence of dentine microcracks. Afterwards, all the canals were filled with the single cone technique with dedicated cones and BioRoot RCS bioceramic sealer. After 24 h, the roots were apically resected with a carbide bur 3 mm from the apex. At this point, the roots were randomly assigned to two groups: no retrograde procedures (n=6); standard retrograde ultrasonic preparation and Biodentine filling (n=6). Lastly, the formation of internal and external voids was quantified by means of a second computed microtomographic analysis. The normality of the distribution and the equality of variance of the microtomographic datasets were tested with a Shapiro-Wilk and a Levene test, respectively; then, the volumes measured in the two groups were statistically compared with an independent sample t-test (p=0.05). Results: Minimal voids volumes were observed in both considered groups. In the group entailing standard retrograde procedures, the mean voids volumes were 1.878±1.492 % of the entire canal space, in the group with sole root-end resection 0.823±0.576 %. The difference was not significant (p=0.137). Irrespective of the considered group, the small amounts of detected voids were mainly located inside the sealer. Conclusion: When executable, filling the canal with the single cone technique and bioceramic sealer associated with simple root-end resection appears to provide an effective seal of the endodontic space. In selected cases, such technique could make the need to perform retrograde preparation and filling less imperative.

Aim: To assess the influence of different motions on the cyclic fatigue resistance of Reciproc instruments simulating the temperature of the clinical conditions. Methods: The sample size was determined using statistical software set with the following parameters: α=0.05, β=0.20, δ=30.0, σ=28.0. The experiment required 54 Reciproc files. Brand new R25 files were randomly allocated to three groups defined by the tested motion: continuous rotation at 300 rpm (n=18), “RECIPROC” mode (n=18), and “WAVEONE” mode (n=18). The same endodontic motor was used for all groups (X-Smart IQ). All files were rotated/reciprocated until fracture inside a custom-designed artificial canal with 60° angle and 5-mm radius of curvature milled in a stainless-steel block. The testing device was electrically heated to keep its internal temperature at 35±1°C, which was constantly monitored with a thermometer. After file separation, the time to failure was registered with a digital chronometer and the length of the fractured fragment measured with a digital calliper. The fracture surface of each file was observed at the scanning electron microscope to perform a qualitative fractographic analysis. The collected data (time to fracture and fracture length) were tested for the normality of the distribution and the equality of variances with a Shapiro-Wilk and a Levene test, respectively. The dependent variables were compared amongst groups by means of a multivariate analysis of variance and Tuckey post-hoc test (p=0.05). Results: The continuous rotation group exhibited the shortest lifespan among the considered groups (85.4±9.5 s to failure). Both reciprocating motions were associated with a significant improvement of fatigue resistance (p

Aim To compare the filling quality obtained with standard retrograde procedures with that of a technique with the potential to simplify the surgical manoeuvres, namely the orthograde placement of 6 mm of mineral trioxide aggregate (MTA) followed by the root-end resection after cement setting. Methodology Sample size was calculated referring to previously published data (a = 0.05; b = 0.20; d = 3.0; r = 1.5). Accordingly, 12 freshly extracted single-rooted teeth were selected and transversally cut to obtain 12 mm long roots. Roots with aberrant anatomy were discarded. After manual scouting and mechanical glide path establishment, canals were shaped with HyFlex instruments up to size 40, 0.04 taper. The roots were randomly assigned to an experimental group (n = 6), where MTA was placed with a carrier and compacted with manual pluggers up to 6 mm from the working length, or to a control group that entailed filling with the single cone technique (n = 6). After 24 h, the roots in the experimental group received backfilling with thermoplasticised gutta-percha and apical resection. In the control group, the roots were resected apically and underwent standard retrograde ultrasonic preparation and MTA filling. The formation of internal and external voids was quantified by means of a computed microtomographic analysis. The normality of the distribution and the equality of variance of the datasets were tested; afterwards, the groups were compared statistically with an independent sample t-test (P = 0.05). Results Void formation was minimal in both experimental and control groups, ranging from 0.00% to 4.42% of the canal volume. In the control group, the voids (1.88 1.49%) were mainly external and related to sealer porosities. In the experimental group, the voids (1.08 0.50%) prevalently accumulated inside the MTA mass and at the interface between MTA and gutta-percha. The differences between the groups were not significant (P = 0.244). Conclusions The orthograde placement of MTA followed by apical resection may constitute a valid alternative to the standard surgical practice to simplify the surgical phases in selected cases.

Aim To evaluate the effect of different motions on the cyclic fatigue resistance of Reciproc Blue reciprocating files simulating the temperature of the clinical environment. Methodology After sample size calculation considering preliminary experimental data (a=0.05; b=0.20; d=30.0; r=32.0), 69 new R25 Reciproc Blue files were divided into three groups of 23 files each according to the tested motion: continuous rotation at 300 rpm, “RECIPROC” mode, and “WAVEONE” mode. All files were activated until fracture inside a stainless-steel artificial canal with 60° angle and 5 mm radius of curvature. The temperature was kept at 35°C and controlled with an internal thermometer inside the testing device. For each file, a single blinded operator measured the time to failure with a digital chronometer and the length of the fractured fragment with a digital calliper. A qualitative fractographic analysis was performed by observing the surface of the fractured files at the scanning electron microscope. The scalar data were tested for the assumptions for using parametric tests and then underwent a statistical analysis with a oneway analysis of variance and Tukey post hoc test (P = 0.05). Results The shortest lifespan of the files was registered in the continuous rotation group (204.1 24.2 s to failure). Both reciprocating motions led to significantly improved fatigue resistance. The “RECIPROC” mode performed better than the “WAVEONE” mode, exhibiting 329.8 31.5 s and 252.9 43.7 s to failure, respectively. No difference in fragment length was observed, confirming the correct positioning of the files inside the artificial canal. The scanning electron microscopic analysis confirmed that all the observed specimens fractured due to cyclic fatigue. Conclusions The results of the present study seem to encourage the use of R25 Reciproc Blue files preferably with their native motion to reduce the fracture risk in the clinical setting.

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Aim To assess the effectiveness of two integrated shaping and filling techniques for the treatment of maxillary central incisors affected by chronic apical periodontitis. Methodology The trial enrolled 60 patients with a maxillary central incisors needing root canal treatment affected by chronic apical periodontitis with periapical radiolucency smaller than 5 mm in diameter. Block-randomization was undertaken to allocate the patients to two treatment groups with different canal shaping and filling protocols: group 1 (G1, n = 30), Revo-S/One Step Obturator; group 2 (G2, n = 30) GTX/GTX Obturator. An independent examiner evaluated the patients at baseline, after 6, 12, 24 and 36 months by performing percussion and palpation tests. At the same time points, standardized periapical radiographs were taken to score the radiographic healing according to a previously published scale. For this analysis, the level of agreement with regard to the scores assigned by two blind evaluators was tested by weighted kappa statistics. Comparability of baseline clinical data, as well as the differences between the two groups and among time points concerning clinical and radiographic data were evaluated with non-parametric tests (p < 0.05). Results All the patients were re-evaluated after 3 years. One patient per group complained of mild symptoms at the end of the observation period. Radiographic healing was progressive during the follow-up. The lesions were classified as totally healed, partially healed and not healed in 93.3%, 3.3% and 3.3% of cases in G1 and in 93.3%, 0% and 6.7% of cases in G2. The differences between groups were not significant (p > 0.05). Conclusions The two integrated endodontic systems were equally effective in achieving high three-year success rates in the treatment of maxillary central incisors with chronic apical periodontitis.

Aim To evaluate the fit against root canal walls obtained with a single-taper post system, placed without further canal enlargement, and a double-taper post system requiring traditional post space preparation with burs. Methodology Twenty straight single-rooted teeth were cut to obtain 14 mm-long roots. Canals were shaped with Mtwo rotary files up to size 40, 04 taper and filled with the continuous wave of condensation technique, leaving an unfilled coronal space of 9 mm. Ten roots were randomly assigned to group 1 (G1) and received a SurgiPost Multiconical single-tapered post, which had previously undergone standardised trimming. In the remaining roots (G2), the post space was prepared with the bur of the DT Light-post system to place a double-taper post of corresponding size. The posts were luted with RelyX self-adhesive cement. Cement thickness was measured on sectioned specimens at the scanning electron microscope (120 readings per post third). Parametric statistical tests were used to compare the cement thickness between the two groups and among post thirds (a = 0.05). Results At the coronal level, cement thickness was minimum and similar in the two groups. The effects of drilling were visible on the canal walls on the apical third of the post in G1, which was characterized by even cement distribution irrespective of the post third. The cement thickness was limited also in G2, but slightly increased at the post tip (p < 0.05). Conclusions The post systems achieved satisfactory fit in straight single-rooted teeth in the coronal and middle post thirds. At the tip of the post, the post space preparation with drills allowed for excellent fit but required further removal of dentine, while single-taper posts provided an inferior fit at this level due to the standardised methodology needed in the research setting.

Unbiased estimates of incidence rates of accidents with blood contaminations (ABC) and time trends is the milieu for assessing the effectiveness of preventive interventions. A standardised procedure for registration and follow-up of ABC was et up in a North Italian hospital since 2002. Accurate estimates of rate denominator, as full-time equivalent (FTE) person-years, was calculated, for exposed workers only and excluding periods of prolonged absence. In the observation period (2004-2011), training courses for head nurses on security procedures were repeatedly carried out as well as the progressive introduction of vacuum blood collection systems (since 2009). 1287 ABC have been reported, corresponding to an overall annual crude incidence rate of 4.73 per 100 FTE. Temporal trends, calculated on the biennial incidence, resulted in a reductions over the time period considered, in particular for needlestick injuries. Our results support the notions on the efficacy of the adopted prevention measures.