ENDO, 02/2018

This review aims to summarise the current knowledge and recommendations regarding the diagnosis and treatment of the acute apical abscess in conjunction with the understanding of the microbiological background of this inflammation, thus providing an actual insight for the clinician. Keywords: antibiotics, apical abscess, drainage, incision, microbiology

Perforation of the root canal is a serious complication of root canal treatment that may even result in tooth loss. Many different concepts and materials for perforation repair have been described and investigated over the decades. This article reviews the literature and summarises the relevant research findings on this subject. Keywords: Bioceramics, matrix techniques, MTA, repair materials, perforation repair

Objectives: The aim of the present study was to evaluate the efficacy of R-Endo and D-RaCe Retreatment instruments with and without using passive ultrasonic irrigation on the removal of root canal filling material, and the time required for its removal. Materials and methods: Sixty mandibular premolars with single canals were decoronated; the root canals prepared using the Revo-S rotary system and obturated with gutta-percha size (25/.06), using lateral compaction technique. Roots were divided into four equal groups (n = 15) according to the retreatment rotary system and the final irrigation technique used in the removal of root canal filling material into: R-Endo retreatment system with conventional irrigation (R-Endo/C), R-Endo retreatment system with passive ultrasonic irrigation (R-Endo/PUI), D-RaCe retreatment system with conventional irrigation (D-RaCe/C) and D-RaCe retreatment system with passive ultrasonic irrigation (D-RaCe/PUI). Roots were split into two halves longitudinally and the canal walls photographed using a digital camera connected to a stereomicroscope. The remaining filling material in each root canal third was evaluated using Image-J software. Data were analysed using the Mann-Whitney U test for the rotary system comparisons and irrigation techniques, while Friedman's test was used to compare between the different root canal levels. Results: There was a statistically significant difference in the total area percentage of the remaining filling material among the four groups (P < 0.05). The D-RaCe/PUI group showed the least amount of the remaining root canal filling material, followed by R-Endo/PUI, then D-RaCe/C, while the R-Endo/C showed the highest amount. Conclusion: D-RaCe/PUI group was the fastest and the most efficient technique in the removal of the root canal filling material. Keywords: D-RaCe, passive ultrasonic irrigation, R-Endo, retreatment, stereomicroscope The authors declare that they have no conflict of interest.

Aim: The aim of this study was to assess the shaping ability and surface topography of WaveOne Gold (WOG) reciprocating and OneShape (OS) rotating single file systems. Materials and methods: Thirty mesiobuccal canals with severe curvature (25 to 40 degrees) were assigned to two equal groups according to the instrument used for preparation - WOG or OS files. The shaping ability was assessed by measuring canal transportation and centring ratio. Data were statistically analysed using an independent sample t test to compare between more than two groups in independent samples. A paired sample t test was used to compare between two groups in dependent samples. Surface topography of new and used instruments was analysed using scanning electron microscopy (SEM) and the chemical profile of those instruments was inspected using energy dispersive X-ray spectroscopy (EDS). Results: The differences between both instruments were not of statistical significance at any level for canal transportation and centring ratio. However, when OneShape was used, the mean centring value at 3 mm (0.62 ± 0.24) was significantly higher than at 5 mm (0.35 ± 0.25) (P = 0.02). SEM examination revealed machining grooves in all new instruments. After instrumentation, OS showed unwinding of the flutes with deformation at the edges; while WOG showed very little blunting at the edges and tip. EDS analysis showed that the as-received files were composed mainly of nickel and titanium for WaveOne Gold and OneShape; with traces of iron and nitrogen. However, oxygen constituted 6.58 wt% of the WOG composition. After usage, the elementary composition of WOG remained almost the same. Conversely, OneShape instruments had less nickel and titanium, and more nitrogen. Moreover, oxygen appeared as a new element in the composition Conclusions: Both instruments are considered safe for instrumentation of severely curved root canals. However, surface characteristics and chemical profile suggest that it is safer to use OneShape file for only a single molar with severely curved canals. Keywords: EDS, OneShape, reciprocation, SEM, severe canal curvature, shaping ability, WaveOne Gold

Purpose: To assess the influence of two root canal filling systems on root fracture resistance. Materials and methods: Thirty extracted single-canal mandibular premolars were decoronated to a length of 13 mm and randomly distributed into one control group (receiving no treatment) and two other groups according to the filling system used: bioceramic EndoSequence BC Sealer/BC Points; and AH Plus/conventional gutta-percha cones. Canals from the two experimental groups were prepared up to an instrument size 40/.04 and filled with the test system using the single cone technique. After storage at 100% humidity and 37°C for 2 weeks, each root was subjected to a compression test using a universal testing machine at 0.5 mm/min speed until vertical fracture occurred. Data were statistically analysed by the Kruskal-Wallis test, with the significance level set at P < 0.05. Results: There was no significant difference between the load required to fracture roots filled with the two obturation systems (P > 0.05). Untreated roots showed a slightly higher fracture resistance value when compared to the treated ones, but not to the point of reaching statistical significance (P > 0.05). Interpretation: Roots filled with either the EndoSequence BC system or AH Plus/gutta-percha showed statistically similar fracture resistance when compared with untreated roots. Keywords: bioceramic-coated points, bioceramic sealer, epoxy resin sealer, fracture resistance, root canal filling The authors deny any conflicts of interest.

Aim: The aim of this study was to investigate the effect of a silver nanoparticle intracanal medicament on root canal dentine microhardness compared with calcium hydroxide. Materials and methods: Silver nanoparticles were prepared and characterised using an optical spectrophotometer and a transmission electron microscope. A total of 60 teeth were selected. Teeth were decoronated and root canals were cleaned and shaped using ProTaper NiTi files. Roots were divided into three groups; calcium hydroxide, silver nanoparticles, as intracanal medicaments, and control group (n = 20). Microhardness was measured using the Vickers test after either 3 days or 1 week (n = 10) in coronal, middle and apical thirds. One-way ANOVA, followed by the Tukey post hoc test, was used to compare between two groups in non-related samples. Results: Results showed that silver nanoparticles showed a significant incremental increase in dentine microhardness (270.50 VHN ± 132.01) than both the control group (155.00 VHN ± 15.11) and the calcium hydroxide group (61.55 VHN ± 11.63), which showed the lowest dentine microhardness during both test periods. Conclusion: The use of silver nanoparticles could provide a substitute to calcium hydroxide as an intracanal medicament that increases the dentine microhardness of root canal-treated teeth. Clinical significance: Nanosilver as an intracanal medication showed a gradual increase of microhardness of dentine over time. Together with its antibacterial effect it could provide a substitute to calcium hydroxide that has a detrimental effect on the dentine microhardness. Keywords: calcium hydroxide, dentine, intracanal medicament, microhardness, silver nanoparticles

Introduction: Exploration is an important step of root canal preparation, because it allows the clinician to negotiate the canal to its terminus and determine its complexity. Different instruments have been developed specifically for this purpose. This study compared the buckling resistance of hand stainless steel and pathfinding nickel-titanium rotary instruments in artificial canals with different depths. Materials and methods: A total of 30 PathFile, ScoutRace and C-Pilot instruments were evaluated. The buckling resistance was tested using acrylic resin blocks with a flat surface or with 3 mm and 6 mm deep artificial canals. The load required to generate a lateral displacement of 1 mm was recorded. Data were statistically analysed using one-way analysis of variance (ANOVA) and Student-Newman-Keuls test for multiple comparisons at a significance level of P < 0.05. Results: On the flat surface, C-Pilot showed the greatest buckling resistance. In 3 mm deep canals, PathFile showed resistance similar to that of C-Pilot files on the flat surface. In 6 mm deep canals, both nickel-titanium instruments showed greater buckling resistance than C-Pilot on the flat surface (P < 0.001). Conclusions: The buckling resistance of nickel-titanium pathfinding instruments increases with the depth of the canal. Keywords: buckling resistance, endodontic instruments, endodontic treatment, glide path, narrow root canal