Assessment of the shaping ability of R-Motion 30 .04 and 25 .06 in mesial canals of mandibular molars based on automated computational measurement.

INTRODUCTION: The aim of this study was to evaluate changes in geometry following root canal preparation using R-Motion instruments with different apical sizes and tapers. METHODS: 54 mesial canals of mandibular molars with single curvature of angles ranging between 20° and 30° were stratified into 3 groups according to their internal anatomy (R-Motion 25/.06, 30/.04, Reciproc Blue) (n=18 per group). Micro-computed tomography was used to standardize the samples before instrumentation and, after instrumentation, to assess canal transportation, changes in canal volume and centering ability. Canals were irrigated with 17% EDTA and sodium hypochlorite, and the final rinse included subsonic agitation of these solutions. Measurements were analyzed automatically using the Dragonfly software (Come, Montreal, Canada) and were confirmed by a technician and an endodontist, based on a previously validated methodology. The results were analyzed using the Kruskal-Wallis's and Mann-Whitney´s tests. The level of statistical significance was set at 5%. RESULTS: Significant differences were found in the coronal third for canal transportation, with Reciproc Blue R25 having greater values compared with both R-Motion instruments (p<0.05) and greater changes in volume when compared with R-Motion 30/.04 (p<0.05). CONCLUSIONS: R-Motion of apical size and taper 25/.06 and 30/.04 were associated with similar changes in geometry following root canal preparation in curved mesial canals of mandibular molars, whereas Reciproc Blue was associated with greater canal transportation in the coronal root third.

The supplementary use of XP-endo Finisher R after Reciproc enhances the removal of a bioceramic sealer in oval root canals.

This study compared the performance of Reciproc and Reciproc Blue endodontic files in retreatment time and re-establishment of apical patency, plus removal of a bioceramic sealer from the canal surface with the supplementary use of the XP-endo Finisher R. Following preparation, slightly curved oval root canals in mandibular incisors were filled using a corresponding gutta-percha point and a bioceramic sealer. Apical patency achievement was assessed and the time required to reach the original working length was recorded. The samples were split longitudinally and were photographed to assess the material remaining on the canal walls. No significant differences were observed regarding patency achievement or retreatment times when comparing Reciproc and Reciproc Blue. Significant less material remained on the canal walls when Reciproc was followed by XP-endo compared with Reciproc alone, and when the data for Reciproc and Reciproc Blue were pooled.

Regenerative Endodontic Procedure in an Immature Permanent Incisor with Internal Root Resorption: a Case Report.

This report describes a regenerative endodontic procedure of an immature permanent incisor with internal root resorption (IRR) and 4-years follow-up. A healthy 8-year-old man was referred for treatment of tooth #9 after a traumatic intrusion. The periapical radiograph showed an IRR and an open apex with periradicular lesion. A diagnosis of pulp necrosis and chronic apical abscess was achieved. In the first appointment, under local anesthesia and rubber dam isolation, an access cavity was designed and the root canal was chemically cleaned under irrigation with 10 mL 1.5% sodium hypochlorite (NaOCl). The root canal was then dried and calcium hydroxide paste was placed. During the second appointment, the root canal was irrigated with 5 mL of 17% ethylenediaminetetraacetic acid (EDTA) for 5 minutes and dried. The blood clot was established in a time of 3 minutes after the bleeding from the periapical tissue was trigged. White mineral trioxide aggregate (MTA) was placed up to the amelocemental junction and the final restoration of the access cavity was carried out. During periodic clinical and radiographic follow-up, the patient remained symptom free, the periapical region was completely healed, inhibition of the root resorption process achieved, and formation of the new periodontal ligament as well as tooth widening development observed, meeting functional expectations after 48 months. The regenerative endodontic procedures are an available option to treat IRR in severely immature teeth. The available literature on the regenerative endodontic procedures applied to IRR treatment is limited, and more research is needed in this field.

Effectiveness of XP-Endo Finisher and Passive Ultrasonic Irrigation in the Removal of the Smear Layer Using two Different Chelating Agents.

STATEMENT OF THE PROBLEM: The smear layer may harbor microorganisms and necrotic pulp tissue, jeopardizing irrigant penetration. Recently, Dual Rinse®, a weak chelating agent, has been introduced to the market. However, its chelating capacity in the final irrigation protocol with different activation systems has not yet been deeply analyzed. PURPOSE: The aim of this ex vivo study was to evaluate the effectiveness of passive ultrasonic irrigation (PUI) and XP-endo Finisher (XP) on smear layer removal in combination with two chelating agents, ethylenediaminetetraacetic acid (EDTA) and etidronic acid (HEDP). MATERIALS AND METHOD: This in vitro, experimental study evaluated fifty-two single-rooted human teeth were standardized to 16 mm in length. Root canal instrumentation was performed by the ProTaper Gold system up to the F4 file. The apical end of the samples was sealed with wax to simulate a closed system. Teeth from group 1 (n=24) were irrigated with 3% sodium hypochlorite (NaOCl) and 17% EDTA, while teeth from group 2 (n=24) were irrigated with 3% NaOCl mixed 9% HEDP. Both groups were divided into two subgroups (n=12) depending on the activation system used: XP (group XP-EDTA and XP-HEDP) or PUI (group PUI-EDTA and PUI-HEDP). The specimens were evaluated by scanning electron microscopy at 3, 5 and 8mm from the apex. Statistical analysis was performed using ANOVA and Bonferroni tests considering p> 0.05 as significant. RESULTS: PUI-EDTA was the most effective at removing the smear layer, with a statistically significant difference from XP-EDTA (p< 0.042) and group XP-HEDP (p< 0.003). There were no statistically significant differences among the other groups. CONCLUSION: Under the conditions of this ex vivo study, no activation system was able to completely remove the smear layer from the root canal walls. However, the combination of NaOCl with ultrasonically activated EDTA obtained better results than the other treatments.

CFD analysis on the effect of combining positive and negative pressure during the irrigation of artificial isthmuses.

Fluid dynamics generated by irrigation needles have not been deeply analyzed in root canal irregularities such as apical ramifications or isthmus where the cleaning capacity of irrigants might be compromised and hence the treatment outcome. The goal of this study was to compare the key irrigation parameters (flow pattern, irrigant velocity, apical pressure, and shear stress) between two irrigation needles and the additional effect of aspiration cannulas through computational fluid dynamics. A 3D-model consisting of two canals linked by an isthmus was modeled. The abovementioned needles irrigated the primary canal, whereas an aspiration cannula was located inside the secondary canal. Both the geometry definition and spatial discretization were carried out with ANSYS 16.2, through which six different simulations were performed: lateral exit (LE) needle, frontal exit (FE) needle, LE and cannula in crown (LEC), FE and cannula in crown (FEC), LE and cannula in middle third (LEM), FE and cannula in middle third (FEM). FE and FEM showed that the irrigation flow only passes through the isthmus in the most apical section (maximum irrigant velocity / shear stress = 8.44 m/s / 1628.44 Pa and 8.63 m/s / 1185.69 Pa, respectively). However, the remaining simulations showed the irrigation flow passing through the isthmus twice, through the most apical section first and through the upper part of the isthmus later (maximum irrigant velocity / shear stress = 8.48 m/s / 1298.24 Pa (LE), 8.61 m/s / 1261.36 Pa (LEM), 8.61 m/s / 1355.24 Pa (LEC), 8.59 m/s / 1256.87 Pa (FEC)). Furthermore, the highest velocity values were detected when aspiration cannulas were added.

The effect of a preparation containing glycocholic acid and/or agitation on the tissue dissolution ability of sodium hypochlorite.

This study assessed the porcine palatal mucosa dissolution, from artificial grooves, by a final rinse of sodium hypochlorite (NaOCl) solely or mixed with Keratobacter ((KB); or agitation) passive ultrasonic irrigation (PUI) or sonic activation (SA). Soft-tissue samples (n = 123) were weighed and placed inside root canal grooves in central maxillary incisors. The specimens were randomly divided into six test groups (n = 20): NaOCl 3% with or without KB and the irrigation dynamics: positive pressure (PP), SA or PUI. An EDTA intermediate rinse was included. Soft-tissue weights were measured subsequently. The NaOCl + KB_PUI group showed the highest mean weight reduction, whilst the NaOCl_PP group recorded the lowest. NaOCl + KB subgroups were associated with hastened reduction compared with NaOCl subgroups. NaOCl_PP presented with significantly lower weight reduction when compared with the remaining experimental groups. The addition of KB to NaOCl or its agitation enhances tissue dissolution ex vivo. The agitation of KB-containing mixtures offers no further benefits.

Etidronic acid and ethylenediaminetetraacetic acid associated with sodium hypochlorite have limited effect on the compressive fracture resistance of roots ex vivo.

AIMS: To assess the effect of etidronic acid (EA) mixed with sodium hypochlorite (NaOCl) and two ethylenediaminetetraacetic acid-containing preparations (EDTA and SmearClear) alternated with NaOCl, as a final rinse, on root fracture resistance to a compressive force. MATERIALS AND METHODS: Seventy-two premolar roots were randomly allocated to the following groups according to the irrigant solutions. For the EA group, 9% EA + 2.5% NaOCl were used throughout the assays (n = 21). The remaining groups received 2.5% NaOCl during and immediately after chemo-mechanical instrumentation. Intermediately, the roots received 17% EDTA (n = 19), or SmearClear (n = 16), or no irrigation (control) (n = 16) plus a final rinse with 2.5% NaOCl. The specimens were subjected to a vertical compressive force loaded at a crosshead speed of 0.02 mm/s parallel to the long axis of the root until fracture occurred. The results were compared statistically using the one-way analysis of variance for intergroup comparisons. RESULTS: The negative control presented with the highest values, whereas the SmearClear presented with the lowest values, though no significant differences were found when comparing the different groups (P = 0.82). CONCLUSIONS: The use of EA + NaOCl or two EDTA formulations in association with NaOCl does not affect the fracture resistance of previously chemo-mechanically prepared roots.

Comparison of the Volume of Root Canal Irrigant Collected by 2 Negative Pressure Needles at Different Flow Rates of Delivery.

INTRODUCTION: A greater irrigant volume improves the effectiveness of root canal irrigation. The purpose of this study was to compare 2 negative pressure systems regarding the volume of irrigant collected from the apical area in moderately curved canals at 3 different flow rates of delivery in vitro. METHODS: The mesiobuccal canals of 30 molars with a curvature between 20° and 40° were prepared to size #40.04 taper. A closed system was created. The canals were irrigated at 3, 6, and 12 mL/min for 30 seconds using EndoVac (SybronEndo, Orange, CA) and the INP needle (Mixnus Fine Engineering Co Ltd, Nagano, Japan) (both independent variables). A recovery trap was used to collect the irrigant aspirated by the negative pressure needles. Irrigant volume (dependent variable) was measured in milliliters. Data were analyzed using mixed analysis of variance. RESULTS: There was a statistically significant interaction between the negative pressure system and the irrigant volume collected (P < .0005). The mean irrigant volume collected by the different negative pressure systems was greater for INP at 3 (P < .001), 6 (P < .001), and 12 mL/min (P < .001) flow rate. Both negative pressure needles showed statistically significant differences (P < .001) between mean irrigant volume collected at different flow rates. CONCLUSIONS: A greater volume was collected by increasing the flow rate of irrigant delivery for both EndoVac and INP. The INP needle could collect a greater volume of irrigant from the apical third compared with EndoVac at all 3 different flow rates.