In vitro comparison of cyclic fatigue resistance of two rotary single-file endodontic systems: OneCurve versus OneShape

The aim of the present study was to evaluate the difference in cyclic fatigue resistance between OneCurve (OC) and OneShape (OS) endodontic single-file NiTi systems in a severely curved artificial canal. After sample size calculation (α = 0.01; β = 0.20; σ = 20.0; δ = 20.0), 25 OC and 25 OS files were used. An artificial canal with 60° angle and 5-mm radius of curvature was milled in a stainless-steel block reproducing the size and taper of the files used. The test device was electrically heated to maintain the environmental temperature at 37 °C. All files were rotated until fracture; the time to failure was recorded and the number of cycles to fracture (NCF) calculated. The length of the fractured fragments was measured too. Fractographic examination and cross-sectional area calculation were performed by scanning electron microscopy analysis (SEM). Data were statistically analyzed using an independent sample t test. The significance level was set at 0.01. Statistical analysis showed that OC files exhibited significantly greater cyclic fatigue resistance than OS (p  0.01). SEM fractographic analysis confirmed that all the scanned samples separated due to cyclic fatigue. Within the limitations of the present study, OC endodontic instruments resisted to cyclic fatigue better than OS. The improved mechanical resistance of OC could be related to new NiTi alloy used for their manufacturing

Influence of sealer placement technique and powder/liquid mixing ratio on the quality of single cone root canal filling: a micro-CT analysis

Aim: To assess the influence of two different placement techniques and powder/liquid mixing ratio of a bioceramic sealer on the quality of root canal filling by single-cone using a micro-CT analysis. Methods: Thirty-two single-rooted elements with a mesio-distal diameter of 5,00\ub10,50 mm, a buccallingual diameter of 6,50 \ub10,50 mm and a root length of 14,50\ub10,50 mm measured at CEJ level were selected to be included in the study. After creating the coronal access cavity, root canals were scouted with manual files and the working length was acquired. Root canals were shaped with R40 Reciproc Blue and irrigated with NaOCl 5% and EDTA 17% solutions. Prepared samples were randomly assigned into four experimental groups (n=8), according to the sealer placement technique and the powder/liquid mixing ratio: G1, the sealer (BioRoot RCS, Septodont) was mixed in a 1:5 ratio, as suggested by the manufacturer, and carried into the root canal by a dedicated gutta-percha cone up to the working length; G2, sealer placement as group G1, but using 1:6 mixing ratio; G3, the sealer was mixed in a 1:5 ratio and carried into the root canal by a syringe with a cannula (Apexcal, Ivoclar) up to its complete filling, then a dedicated gutta-percha cone was inserted into the canal; G4, sealer placement as group G3, but using 1:6 mixing ratio. All the samples were submitted to micro-CT analysis. Micro-CT scans were acquired after shaping procedures (t0) and after canals obturation (t1) and then compared to evaluate the presence of voids in the gutta-percha, sealer and dentin interfaces. The normality of the distribution and the equality of variance of the microtomographic datasets were tested with a Shapiro-Wilk and Levene test, respectively; the significance of the differences between groups in terms of the formation of voids was ascertained with the Kruskal-Wallis test. The results were considered statistically significant for a p-value < 0.05. Results: Minimal void volumes were observed among groups. G1 performed the best result: total void volumes were 0,253\ub10,175% of the entire canal space. The other experimental groups follow in order of increasing volume: G3 (0,260\ub10,254%), G2 (0,532\ub10,528%), G4 (0,840\ub10,705%), but no statistically significant difference was observed. All groups showed a similar distribution of voids: in the apical and middle third of the root canal the presence of voids was minimal while the greatest void volumes were detected in the coronal third, due to the canal anatomy and the larger amount of sealer. In this canal portion voids were mainly distributed within the sealer. Concerning the sealer viscosity, the more fluid formulation (1:6) showed an increase of void volumes, although without statistical significance. Likewise, no statistically relevant influence was registered regarding the sealer placement technique. Conclusion: All the examined techniques should be considered effective for the clinician. Under the conditions of the present study, the 1:5 powder/liquid mixing ratio should be preferred when associated with both the sealer placement techniques, according to the clinical situation and the operator preferences. When using the low viscosity formulation, the clinician should insert the sealer slowly and in a controlled way, in order to minimize the formation of voids

Influence of two conservative preparation designs on the internal fit of CAD/CAM overlays

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Periapical healing after simplified endodontic treatments: A digital subtraction radiography study

Abstract Aim To evaluate the 6-month outcome of endodontic treatment of periapical lesions with integrated systems by clinical examination and digital subtraction radiography (DSR). Methodology Eighty-four patients with chronic periapical pathosis were randomly allocated to two groups and received endodontic treatment with Revo-S/One Step Obturator (G1, n = 41) or GTX/GTX Obturator (G2, n = 43). Six months later, clinical examination and DSR analysis were performed. Non-parametric statistical methods were used (p Results Total healing, partial healing and failure occurred in 48.4%, 48.4% and 3.2% of cases in G1, in 50.0%, 43.8% and 6.2% of cases in G2, respectively. No significant difference was detected. Conclusions The integrated endodontic techniques allowed for a high 6-month success rate in both groups in accordance with literature data

Root-end resection without retrograde preparation: a micro-CT study

Aim: the gold standard in endodontic surgery is characterized by meticulous retrograde procedures that could be not performable in all teeth due to multiple clinical difficulties. The possibility to perform the only apical resection, when feasible, without further retrograde steps might represent a substantial clinical advantage. The present study analyzes the filling quality achieved with standard retrograde technique in comparison with alternative techniques with or without retrograde procedures. Methods: the sample size was determined using with the following parameters: \u3b1=0.05; \u3b2=0.20; \u3b4=3.0; \u3c3=1.5. Twenty-four 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 EDM rotary files up to size 40.04 taper (500 rpm; 2.5 Ncm). The roots were analyzed with a computed microtomography scanner to identify the possible presence of dentine microcracks. Afterwards, the roots were randomly assigned to two groups: twelve canals were filled with the single cone technique (SCT) with dedicated cones and BioRoot RCS bioceramic sealer; twelve canals were filled with MTA cement (ProRoot MTA) for 6mm in the apical portion with the aid of the MAP System; the empty canal portion was backfilled with thermoplasticized gutta-percha (Obtura III Max System). After 24 h, the roots were apically resected with a carbide bur 3 mm from the apex. At this point, the two groups were randomly subdivided into two further groups of six elements each: G1, SCT and bioceramic sealer without retrograde procedures (n=6); G2, SCT and bioceramic sealer with standard retrograde ultrasonic preparation and MTA filling (n=6); G3, orthograde MTA placement without retrograde filling (n=6); G4, orthograde MTA placement and standard retrograde ultrasonic preparation and MTA 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 groups were statistically compared with the Kruskal-Wallis test and with the Mann-Withney test with Bonferroni\u2019s correction couple comparison. Results: All groups showed minimal voids volumes formation. In the groups characterized by standard retrograde procedures, the mean voids volumes were 1.16\ub10.40 % (G4) and 1.87\ub11.49 % (G2) of the entire canal space, in the groups with the only root-end resection 0.82\ub10.58 % (G1) and 1.08 \ub1 0.50% (G3). The difference between the groups was not statistically significant. Analyzing the volume within the apical 3 mm of the canal after root resection (G1=0.06 \ub1 0.10%; G2=0.76 \ub1 0.81%; G3=2.06 \ub1 .92%; G4=1.53 \ub1 1.79%) the difference between G1 and the other groups was statistically significant (p <0.05). Conclusion: When suitable, filling the canal with the single cone technique and bioceramic sealer or orthograde MTA placement combined with simple root-end resection appears to provide an efficient seal of the endodontic space. These technique could represent a good alternative to the retrograde preparation and filling

Resistance of endodontically treated roots restored with different fibre post systems with or without post space preparation: in vitro analysis and SEM investigation.

Aim: To compare the mechanical resistance to fracture of two conical post systems placed with no preparation of the root canal with that of double taper fibre posts seated in endodontically treated single roots after standard post space preparation using dedicated drills. Methodology: Thirty fibre posts with double (G1, n = 10, DT Light Post) and single taper (G2, n = 10, SurgiPost Multiconical; G3, n = 10, Tech ES Endoshape) were luted with self-adhesive cement in endodontically treated single roots using different post space preparation techniques. The bonded posts were experimentally loaded until failure and the maximum load to fracture was registered. Fracture patterns were qualitatively evaluated and SEM analysis was performed to assess the quality of endodontic treatments and cementation. Data were statistically analysed by means of one-way ANOVA. Results: The mean maximum load to fracture was 165.05 23.46 N in G1, 151.52 16.23 N in G2 and 129.09 15.25 N in G3. Statistically significant differences were pointed out between G1 and G3 (p < 0.01) and G2 and G3 (p < 0.05). No root fractures were evidenced. SEM analyses showed slightly thicker cement ayers at the apical and middle thirds of single taper posts (G2 and G3). Conclusions: DT Light Post and SurgiPost Multiconical fibre posts showed similar properties in terms of mechanical resistance to fracture and higher than those of Tech ES Endoshape. Unrestorable root fractures did not occur with any of the tested posts

Quality of canal obturation assessed by micro-computed tomography: Influence of filling technique and post placement in canals shaped with Reciproc

Abstract Aim To assess by micro-computed tomography (μCT) the quality of fillings in canals shaped with Reciproc considering the effects of filling technique and post insertion. Methodology The canals of 60 single-rooted teeth were instrumented with Reciproc R40 and randomly assigned to four groups (n = 15): G1, single point; G2, as G1 + DT Light Post; G3, continuous wave of condensation; G4, as G3 + DT Light Post. The filling voids were quantified by μCT. Data were statistically analysed by non-parametric test (p Results Filling greater than 96% of the entire canal volume was observed in all groups. The volume of internal voids was greater in G3 than in G4 (p Conclusions Our findings support the use of simplified techniques of canal shaping, filling with matching taper points and post cementation

Efficacy of three different irrigation techniques in the removal of smear layer and organic debris from root canal wall: A scanning electron microscope study

Abstract Aim Aim of this study was to compare the removal of smear layer and organic debris within the tooth canal among conventional needle irrigation, EndoVac and Endoactivator. Methodology Eighty single-rooted extracted human teeth were prepared with rotary NiTi instrumentation and randomly separated into 4 groups. Twenty teeth were used as positive control (Group 1), irrigated with only saline. Teeth assigned to Group 2 ( n = 20) received irrigation with a conventional syringe and a 30-gauge needle (NaviTip, Ultradent, South Jordan, UT); samples in Group 3 ( n = 20) were rinsed with an irrigation device based on apical negative pressure (EndoVac, Discus Dental, Culver City, CA) and teeth in Group 4 ( n = 20) were treated with a sonic irrigation system (EndoActivator, Dentsply Tulsa Dental, Tulsa, OK, USA). The amount of residual smear layer and debris was evaluated under a scanning electron microscope, and a semi-quantitative score was assigned to each root at the coronal, middle and apical thirds; the chi-square test was used to compare the results of the S.E.M. analysis. Results EndoActivator performed the best cleansing for both smear layer and organic debris in all root canal thirds, followed by EndoVac and conventional irrigation ( p > 0.001). EndoVac and conventional irrigation showed better cleaning in the coronal area, whereas EndoActivator performed an homogeneous cleansing at all levels. Conclusions The EndoVac system and the EndoActivator system demonstrated significantly more efficacy in cleansing root canal walls than conventional needle irrigation

Gingival overgrowth caused by Olmesartan Medoxomil: Observational study

Objective: Olmesartan Medoxomil is a type 1 receptor antagonist an antagonist of type 1 receptor (AT1) of angiotensin II (A-II) that inhibits numerous actions of A-II in the renin-angiotensin-aldosterone system (RAAS). A-II is a significant and multifunctional peptide involved in the pathophysiology of blood hypertension and for this reason it represents the main target in several classes of drugs used to treat and control arterial hypertension, such as angiotensin converting enzyme inhibitors (ACE-i), angiotensin receptor blockers (ARB) and renin direct inhibitors. The aim of the study is to evaluate whether the two drugs that have as an active principle Olmesartan Medoxomil, with and without the diuretic hydrochlorothiazide, are able to determine gingival overgrowth. Study Design: 108 subjects were examined and divided into three groups: G1, subjects treated with Olmesartan Medoxomil and hydrochlorothiazide (n=60); G2, subjects received only Olmesartan Medoxomil (n=24); G3, control group without pharmacological therapies (n=24). The plaque index (IP) and the gingival overgrowth index (OI) were recorded, considering the vertical and horizontal components. Results: Vertical overgrowth averaged between 0.17 \ub1 0.15 (G3) and 0.34 \ub1 0.26 (G2) showing statistically significant differences (p <0.05) compared to the other groups. Horizontal overgrowth ranged from 0.18 \ub1 0.26 (G3) to 0.49 \ub1 0.35 (G2) showing statistically significant differences (p <0.05). Conclusions: antihypertensive agents as Olmesartan Medoxomil may result in mild gingival overgrowth in the upper and lower frontal dental elements not related to other etiological factors

A two-year report of a comparative randomized controlled trial on the treatment of upper central incisors with periapical lesions

Aim To evaluate the two-year success rate of primary root canal treatment performed with two integrated shaping and filling systems on upper central incisors with chronic periapical pathosis. Methodology The trial enrolled 60 patients with an untreated maxillary central incisor presenting a chronic periapical lesion smaller than 5 mm in diameter, who were randomly assigned to two treatment groups: G1 (n = 30), Revo-S/One Step Obturator; G2 (n = 30) GTX/GTX Obturator. The patients underwent single-session root canal treatments by an experienced endodontist and were followed up for two years. The clinical evaluation entailed percussion and palpation tests. Two independent examiners rated the radiographic healing on the basis of a previously described scale. Comparability between groups in terms of baseline clinical parameters was tested with a Mann-Whitney test (age, apical gauging) and \u3c72 test (tenderness to percussion and palpation). The comparison of clinical data and radiographic healing scores between the groups and among time points was carried out with non-parametric statistical methods (p < 0.05). Results The two groups were comparable in terms of baseline clinical parameters. All patients were available for the re-evaluation after two years. Only one patient per group was positive to the clinical tests at the final recall. An improvement of radiographic healing scores along the follow-up period was observed. After two years, the lesions were scored 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, without pointing out statistically significant differences between groups. Conclusions Both the two tested integrated shaping and filling systems proved to be effective for the treatment of upper central incisors with periapical pathosis. When monitoring the healing of periapical lesions, follow-up times longer than one year may be required to observe complete healing