To flat or not to flat? Exploring the impact of flat-side design on rotary instruments using a comprehensive multimethod investigation

AIM

To assess the influence of a flat-side design on the geometry, metallurgy, mechanical performance and shaping ability of a novel nickel-titanium rotary instrument.

METHODOLOGY

Sixty-five new 25-mm flat-side rotary instruments (size 25, taper 0.04) and their nonflat-side prototypes (n = 65) were assessed for major deformations and examined regarding macroscopic and microscopic design, determination of nickel and titanium elements ratio, measurement of phase transformation temperature and evaluation of mechanical performance parameters including time/cycles to fracture, maximum torque, angle of rotation, maximum bending and buckling strengths and cutting ability. Additionally, unprepared canal areas, volume of hard tissue debris and percentage reduction of dentine thickness were calculated for each tested instrument after preparing mesial canals of mandibular molars (n = 12), using micro-CT imaging. Statistical analyses were performed using the U-Mann-Whitney test and independent Student t-test (α = 5%).

RESULTS

The number of spirals (n = 8) and blade direction (clockwise) were similar between both flat and nonflat instruments, whilst the helical angles were equivalent (⁓25°). Flat-instruments showed inconsistencies in the homogeneity of the gold colour on the flat-side surface, blade discontinuity, and incomplete and variable S-shaped cross-sections. The titanium-to-nickel ratios were equivalent, but significant differences in the R-phase finish and austenitic start phase transformation temperatures were observed between the flat and nonflat-side instruments. The flat-side instruments demonstrated superior cutting ability compared to the nonflat instruments, as well as, significantly lower values for time to fracture, rotation to fracture and maximum torque to fracture (p < .001). No statistical difference was observed between tested instruments regarding angle of rotation (p = .437), maximum bending (p = .152) and buckling load (p = .411). Preparation protocols using flat and nonflat instruments did not show any statistically significant differences (p > .05). All flat-side instruments exhibited deformation after shaping procedures.

CONCLUSIONS

The flat-side instrument showcased enhanced cutting ability compared to its nonflat counterpart. However, it exhibited inferior performance in terms of time, rotation and maximum torque to fracture, along with distinct phase transformation temperatures. No differences were observed in the titanium-to-nickel ratios, angle of rotation, maximum bending, buckling load, preparation time, percentage of untouched canal walls, volume of hard tissue debris and percentage reduction of dentine thickness.

Success rate of permanent teeth pulpotomy using bioactive materials: A systematic review and meta-analysis of randomized clinical trials

BACKGROUND

The results of vital pulp treatments in permanent teeth have been encouraging. Currently, pulpotomy treatment for permanent teeth primarily utilizes mineral trioxide aggregate (MTA) as the dressing material, followed by calcium hydroxide. While other calcium-silicate-based cements have been suggested for pulpotomy, there is a limited number of studies evaluating their long-term effectiveness.

OBJECTIVES

The objective of this systematic review and meta-analysis was to evaluate the success rate of pulpotomies performed on permanent teeth, comparing the use of ProRoot MTA with that of calcium hydroxide and other bioceramic materials.

METHODS

A comprehensive search was conducted in several electronic databases, including PubMed, Cochrane Library, Scopus, Web of Science, Embase and Science Direct until December 2022. The search was guided by PICOS criteria, including only randomized clinical trials (RCTs) that evaluated the success rate of pulpotomy treatments in permanent teeth using ProRoot MTA in comparison to calcium hydroxide and other bioceramic materials. The quality of the included studies was assessed using the RoB-2 tool to evaluate the risk of bias, and relevant data were extracted and analysed in RevMan software 5.3 using fixed-effect models. The GRADE tool was used to determine the overall quality of evidence.

RESULTS

The initial search retrieved 1072 studies and, after eliminating duplicates, 677 studies were screened and 28 studies were considered for eligibility. In the final selection process, 16 studies were included in the systematic review, with 10 being determined as having a high risk of bias. Pulpotomy showed an overall mean success rate of 92% after 1 year. The meta-analysis indicated a significantly higher success rate for pulpotomies utilizing MTA in comparison with calcium hydroxide, while no significant difference was seen between MTA and calcium-enriched mixture (CEM) or Biodentine. The GRADE assessment revealed an overall low level of evidence for the included studies.

DISCUSSION

Most randomized controlled trials exhibited a significant absence of control over confounding factors.

CONCLUSIONS

This systematic review and meta-analysis demonstrate that pulpotomy is a highly effective treatment for managing permanent teeth. The results indicate that the success rate of pulpotomy using ProRoot MTA is significantly higher than when using calcium hydroxide. However, the certainty of evidence supporting these findings is low, and there is a need for well-designed RCTs to assess the long-term outcomes of pulpotomy using newer bioceramic materials.

REGISTRATION

This systematic review was registered in the PROSPERO database (registration number CRD42023393970).

Volumetric changes in root canal sealers in ex vivo and a novel animal model approach

AIM

This study aimed to evaluate the volumetric change of root canal sealers through micro-computed tomographic analysis using a novel in vivo model and to compare the results with those obtained using an ex vivo test.

METHODOLOGY

Eighteen single-rooted teeth were cut to 5 mm length from the root apex. The root canals were uniformly enlarged and filled with EndoSequence BC Sealer or AH Plus Jet root canal sealers. Samples were stored at 37°C and 95% relative humidity for 24 h and then scanned with a micro-CT device. Twelve samples (n = 6 for each sealer) were implanted in the subcutaneous tissue of Wistar rats, while six samples (n = 3 for each sealer) were immersed in 20 mL of phosphate-buffered saline (PBS) at 37°C at neutral pH. After 7 and 30 days, teeth were removed from subcutaneous tissue or PBS and rescanned. Statistical analysis of volume changes was performed using Shapiro-Wilk's test and independent t-test (p < .05).

RESULTS

AH Plus Jet had smaller volume changes (-2.2 to +0.77%) than EndoSequence BC Sealer (-2.0 to +4.0%) (p < .05), in the two tested models. The volume of the root canal sealers decreased over time (p < .05), in vivo. AH Plus Jet results varied between the in vivo and ex vivo results (p < .05), while EndoSequence BC Sealer presented similar volume losses for both experimental models (p > .05).

CONCLUSION

EndoSequence BC Sealer lost more volume than AH Plus Jet. The experimental conditions influenced the volumetric change of AH Plus Jet but not the EndoSequence BC Sealer. The ex vivo model should be further explored as a methodological alternative to assess the volumetric changes of root canal sealers without causing harm to animals.

What is the microbial profile in persistent endodontic infections? A scoping review

INTRODUCTION

This scoping review aimed to map the evidence about the microbiota found in persistent endodontic infections.

METHODS

The study protocol was prospectively registered and is available at https://osf.io/3g2cp. The electronic search was performed in MEDLINE via PubMed, Lilacs, BBO, Scopus, Web of Science, Cochrane Library and EMBASE. The eligibility criteria were based on the PCC acronym, where P (Population): patients with teeth presenting persistent endodontic infection; C (Concept): microbial profile; and C (Context): undergoing endodontic retreatment. Clinical studies that evaluated the microbial profile of samples collected from root canals of teeth undergoing retreatment, using classical or molecular methods, were included. Studies that did not show a minimum period of one year between primary endodontic treatment and retreatment or did not radiographically evaluate the quality of primary root canal filling were excluded. Two reviewers independently selected the articles and collected data.

RESULTS

From a total of 957 articles, 161 were read in full and 32 studies were included. The most prevalent species were Enterococcus faecalis, Parvimonas micra, Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, Dialister invisus, Propionibacterium acnes, Tannerella forsythia and Treponema denticola. Cases with symptomatology or inadequate root canal filling presented an increase in specific bacterial species compared to no symptomatology or adequate filling. A greater number of microorganisms was observed in teeth with inadequate coronal restoration compared to adequate restoration.

CONCLUSION

Persistent endodontic infections have a polymicrobial profile identified by the commonly used methods for bacterial detection/identification and are subject to the limitations present in each of those methods.

3D Surface Scanning-A Novel Protocol to Characterize Virtual Nickel-Titanium Endodontic Instruments

The nickel-titanium (NiTi) instruments' geometry plays an important role in their performance and behavior. The present assessment intends to validate and test the applicability of a 3D surface scanning method using a high-resolution laboratory-based optical scanner to create reliable virtual models of NiTi instruments. Sixteen instruments were scanned using a 12-megapixel optical 3D scanner, and methodological validation was performed by comparing quantitative and qualitative measurements of specific dimensions and identifying some geometric features of the 3D models with images obtained through scanning electron microscopy. Additionally, the reproducibility of the method was assessed by calculating 2D and 3D parameters of three different instruments twice. The quality of the 3D models created by two different optical scanners and a micro-CT device was compared. The 3D surface scanning method using the high-resolution laboratory-based optical scanner allowed for the creation of reliable and precise virtual models of different NiTi instruments with discrepancies varying from 0.0002 to 0.0182 mm. The reproducibility of measurements performed with this method was high, and the acquired virtual models were adequate for use in in silico experiments, as well as for commercial or educational purposes. The quality of the 3D model obtained using the high-resolution optical scanner was superior to that acquired by micro-CT technology. The ability to superimpose virtual models of scanned instruments and apply them in Finite Element Analysis and educational purposes was also demonstrated.

Comparative analysis of reciprocating and flat side heat-treated rotary single-file systems: design, metallurgical characteristics, and mechanical performance

AIM

To compare through a multimethod assessment two flat side single-file rotary instruments with three single-file reciprocating systems.

METHODOLOGY

A total of 290 new NiTi single-file rotary (AF F One Blue 25/0.06 and Platinum V.EU 25/0.06) and reciprocating (One Files Blue R25, Reciproc Blue R25, Reciproc R25) instruments were selected, carefully examined for any major deformations, and evaluated regarding their macroscopic and microscopic design, nickel and titanium elements ratio, phase transformation temperatures and mechanical performance (time/rotation to fracture, maximum torque, angle of rotation, microhardness, maximum bending and buckling strengths). Nonparametric Mood's median, one-way ANOVA post hoc Tukey, and T-test statistical tests were used (α=5%).

RESULTS

Tested instruments had identical blade counts and near-identical helical angles of approximately 24° (rotary instruments) and 151° (reciprocating instruments). The flat side analysis revealed a few inconsistencies, such as discontinuity segments, different orientations, and gaps in the homogeneity of the bluish color. Microscopically, flat side instruments exhibited blade discontinuity and an incomplete S-shaped cross-section. The surface finish was smoother for One Files Blue and more irregular for both rotary instruments. There were distinct phase transformation temperatures among all instruments. All heat-treated instruments were in an R-phase arrangement, and Reciproc was in an R-phase plus austenite at test temperature (20°C). Compared to the reciprocating instruments, both flat side instruments exhibited lower results in the cyclic fatigue tests using two clockwise kinematics, maximum torque, angle of rotation, and maximum buckling strength (p<0.05). The rotary systems also exhibited low flexibility (p<0.05). AF F One Blue had the lowest microhardness, while Reciproc had the highest value.

CONCLUSION

This multimethod investigation revealed that the flat side rotary instruments underperformed the reciprocating instruments regarding cyclic fatigue (with two different clockwise kinematics), maximum torque, angle of rotation, maximum buckling strength, and flexibility. Manufacturing inconsistencies were also observed in some of the flat side instruments, including discontinuity segments, different orientations, and in the homogeneity of their bluish color given by the heat treatment.

Multimethod analysis of 3 rotary instruments produced by electric discharge machining technology

AIM

This study aimed to compare 3 rotary instruments produced by the EDM process with the heat-treated ProTaper Gold system regarding design, metallurgy, mechanical properties and shaping ability.

METHODOLOGY

HyFlex EDM (25/.~), Neoniti (25/.06), EDMax (25/.06), and ProTaper Gold (25/.08v) instruments (n=58 per group) were compared regarding design, metallurgy and mechanical performance. Unprepared canal areas were calculated for each system after preparation of mesiobuccal, mesiolingual and distal canals of mandibular molars (15 canals per group) using micro-CT technology. Statistical analyses were performed using One-way ANOVA post hoc Tukey and Kruskal-Wallis post hoc Dunn´s tests (α=5%).

RESULTS

All instruments had asymmetrical blades, no radial lands, no major defects, and almost equiatomic nickel/titanium ratios, but different cross-section designs, tip geometries, and surface appearances. Although instruments had distinct transformation temperature curves, they showed crystallographic martensitic arrangement at 21 °C and mixed austenite plus R-phase at body temperature. Neoniti and HyFlex EDM showed similar results in all mechanical tests (p>0.05), while EDMax and ProTaper Gold had similar time to fracture (p = 0.841), maximum bending load (p = 0.729), and cutting ability (p = 0.985). ProTaper Gold showed the highest torque to failure (p<0.001) and HyFlex EDM the lowest buckling resistance (p<0.001). Mean percentages of unprepared canal areas ranged from 20.4% to 25.7% in the mesial canals, and from 20.8% to 26.2% in the distal canal, with no statistical differences among systems (p>0.05).

CONCLUSIONS

Instruments' geometry and phase transformation temperatures influenced the results of the mechanical tests, but not their shaping ability.

Optimization of automated preparation of long oval-shaped root canals using supplementary instrumentation

This study compared the preparation of long oval-shaped root canals using WaveOne Gold and XP-endo Shaper systems, both supplemented or not with manual instrumentation. Twenty-four long oval-shaped canals of mandibular incisors were distributed into two groups according to the instrumentation: WaveOne Gold Primary or XP-endo Shaper systems. All root canals were manually instrumented with a size 25 K-file after automated preparation. The specimens were scanned by using a micro-CT device (17.42 µm) before and after automated preparation and manual instrumentation. The increased surface of the root canal and the percentage of untouched areas were assessed. Both WaveOne Gold and XP-endo Shaper systems increased the root canal surface and had similar untouched areas (p>0.05). Supplementary instrumentation increased the surface of the root canal and decreased the untouched walls (p<0.05). WaveOne Gold and XP-endo Shaper systems provided a similar preparation of long oval-shaped canals and manual instrumentation improved their preparation.

Design, metallurgy, mechanical properties, and shaping ability of 3 heat-treated reciprocating systems: a multimethod investigation

OBJECTIVE

This study aimed to compare 3 reciprocating systems regarding design, metallurgy, mechanical properties, and shaping ability.

MATERIALS AND METHODS

New Reciproc Blue R25, WaveOne Gold Primary, and REX 25 instruments (n=41 per group) were analyzed regarding design, metallurgy, and mechanical performance, while shaping ability (untouched canal walls, volume of removed dentin, and hard tissue debris) was tested in 36 anatomically matched root canals of mandibular molars. Results were compared using one-way ANOVA post hoc Tukey and Kruskal-Wallis tests with a significant level set at 5%.

RESULTS

All instruments showed symmetrical cross sections with asymmetrical blades, no radial lands, no major defects, and an almost equiatomic nickel and titanium ratio. The highest R-phase start temperatures were observed with WaveOne Gold (46.1°C) and REX (44.8°C), while Reciproc Blue had the lowest R-phase start (34.5°C) and finish (20°C) temperatures. WaveOne Gold had the lowest time to fracture (169 s) and the highest maximum load (301.6 gf) (P <0.05). The maximum torque of Reciproc Blue (2.2 N.cm) and WaveOne Gold (2.1 N.cm) were similar (P >0.05), but lower than REX (2.6 N.cm) (P <0.05). No statistical differences were observed among instruments in the angle of rotation (P >0.05) and in the shaping ability in both mesial and distal canals (P >0.05).

CONCLUSION

Although the overall design, temperature transition phases and mechanical behavior parameters were different among tested instruments, they were similar in terms of shaping ability.

CLINICAL RELEVANCE

All tested heat-treated NiTi reciprocating systems showed similar shaping ability, without clinically significant errors.

Association between Apical Periodontitis and Chronic Diseases: An Umbrella Review

Introduction

To assess the methodological quality of systematic reviews (SRs) that evaluated the association between apical periodontitis (AP) and chronic diseases.

Materials and Methods

A systematic search was performed in the databases PubMed, Virtual Health Library, Scopus, Cochrane Library, Embase, Web of Science and Open Grey. SRs that evaluated the association between any chronic disease and AP, and that had performed a valid risk of bias assessment were included. The AMSTAR-2 tool was used for quality assessment and each included systematic review received a final categorization as having "high", "moderate", "low", or "critically low" quality.

Results

Nine studies that met the eligibility criteria were included. The diseases investigated were cardiovascular diseases, diabetes mellitus, HIV, osteoporosis, chronic liver disease, blood disorders and autoimmune diseases. The systematic reviews included in this umbrella review showed a 'low' to 'high' quality of evidence.

Conclusion

There are substantial heterogeneity and several methodological concerns in the included studies. It was observed a positive association between diabetes mellitus and apical periodontitis with limited evidence, no association between HIV and apical periodontitis and a positive association between apical periodontitis and cardiovascular disease, blood disorders, chronic liver disease, osteoporosis and autoimmune diseases with moderate evidence.

Guided Access Cavity Preparation Using a New Simplified Digital Workflow

INTRODUCTION

This study evaluated the precision of a simplified workflow using only preoperative cone-beam computed tomographic (CBCT) scans to gain guided access to root canals of extracted mandibular molars. A workflow using CBCT scanning associated with 3-dimensional oral scanning was used as a reference for comparison. The influence of the presence of coronal restoration in the simplified workflow was also evaluated.

METHODS

Forty-five mandibular molars were randomized into 3 groups: a control group in which digital planning was performed with CBCT and oral scanning and 2 experimental groups in which digital planning was performed only with CBCT examination. In experimental group 1, teeth had no coronal restorations, whereas in group 2 teeth presented with coronal composite restorations. After digital planning, the teeth were accessed using the guides, and a new CBCT scan was made to overlap the pre- and postoperative examinations. Precision was measured by calculating the deviation between the planned and prepared cavities in millimeters and angle. Data were compared using 1-way analysis of variance (P < .05).

RESULTS

All root canals were accessible after access preparation in all tested groups. Deviations of the planned and prepared access cavities were low, with a mean value of 0.55, 0.58, and 0.47 mm and 1.98°, 2.45°, and 1.43° for the control group, group 1, and group 2, respectively. No significant differences in millimeters or angle were observed among the 3 tested groups (P > .05).

CONCLUSIONS

The simplified digital workflow using only CBCT examination allowed a high level of precision in obtaining access in extracted molars with and without coronal restoration, presenting similar results compared with the digital workflow using CBCT and 3-dimensional oral scanning.

Mechanical performance of original; yellowish and blueish ProFile instruments: isolating heat-treatment as a variable

The present study aimed to perform two different heat-treatments in an austenitic NiTi ProFile instrument and to compare the mechanical performance of original and heat-treated instruments. Heat treatment of ProFile (tip size 25 and 0.06 taper) instruments were carried out in a furnace in argon atmosphere using a heating rate of 10° C/min. After reaching the programmed temperatures of 450 ºC or 500 ºC the system remained at a constant temperature for 10 minutes; followed by cooling in water at room temperature. Afterwards; the three groups (n=30 per group) of instruments were compared regarding their cyclic fatigue (n=10 per group); bending (n=10 per group); and buckling resistance (n=10 per group). After cyclic fatigue tests; a scanning electron microscope was used to analyze the fracture surfaces and observe the fracture mode. Statistical analysis was performed using One-way ANOVA and Student-Newman-Keuls test; with an alpha type error set at 0.05. Yellowish and blueish coloration was observed in the ProFile instruments after 450 ºC or 500 ºC heat treatments; respectively. Conventional ProFile instruments showed the lower cyclic fatigue; and the higher bending and buckling resistance (P<0.05). In contrast; yellowish ProFile instruments (heat treated at 500° C) showed the higher cyclic fatigue; and the lower bending and buckling resistance (P>0.05). It can be concluded that the different heat treatments performed on ProFile instruments increased its cyclic fatigue resistance and improved the flexibility and buckling resistance.

Micro-CT assessment of gap-containing areas along the gutta-percha-sealer interface in oval-shaped canals

AIM

To assess the interfacial adaptation (gap-containing areas) of two root canal sealers (EndoSequence BC Sealer and AH Plus) to a conventional gutta-percha (GP) cone (GP-sealer interface) in oval-shaped canals filled using the single cone technique.

METHODOLOGY

Sixteen teeth with oval-shaped canals were selected, scanned in a micro-computed tomographic device, and pair-matched according to the volume, aspect ratio and configuration of root canals. Root canals were then sequentially prepared with WaveOne Gold Primary and Large instruments, followed by filling with WaveOne Large GP points associated with either the premixed calcium-silicate EndoSequence BC Sealer or the epoxy resin-based AH Plus sealer (n = 8 per group) using the single cone technique. After 7 days stored in phosphate-buffered saline solution at 37°C, the specimens were rescanned and the reconstructed images segmented in order to differentiate the filling materials (sealer and GP cone) to the dentine. A total of 453 cross-sectional slices were assessed and categorized according to the presence or absence of gaps at the GP-sealer interface. Mann-Whitney U-test verified the differences between groups and were considered significant at alpha = 5%.

RESULTS

Gaps were non-homogenously distributed in two-dimensional axial cross-section images and none of the specimens showed completely gap-free areas along the entire GP-sealer interface. Root canals filled with EndoSequence BC Sealer and AH Plus displayed 171 (37.75%) and 136 (30.02%) slices with gaps in the GP-sealer interface and these frequencies were statistically significant (p = .000).

CONCLUSIONS

Although none of the specimens had a gap-free area along the entire GP-sealer interface, oval canals filled with AH Plus showed less gaps than the ones filled with EndoSequence BC Sealer.

The impact of TruNatomy and ProTaper Gold instruments on the preservation of the periradicular dentin and on the enlargement of the apical canal of mandibular molars

INTRODUCTION

This study aimed to evaluate the preservation of the periradicular dentin and the enlargement of the apical canal of mandibular molars with TruNatomy and ProTaper Gold instruments.

METHODS

Twenty mandibular molars were scanned in a micro-CT device, anatomically paired, and distributed into 2 groups (n=10). In the ProTaper Gold group, mesial and distal canals were prepared up to F2 (25/.08v) and F3 (30/.09v) instruments, while in the TruNatomy group, mesial and distal canals were enlarged until Prime (26/.04v) and Medium (36/.03v) instruments, respectively. After a new scan, surface area, volume, unprepared areas, transportation, percentage of dentin removal, and dentin thickness parameters were calculated. Data were compared between groups using Mann-Whitney, Student t-test, and the non-metric multidimensional scaling test with alpha set at 5%.

RESULTS

No difference was found between groups regarding unprepared canal areas and reduction of dentin thickness (P > 0.05). Transportation was lower than 0.1 mm in all groups and statistical differences were observed only at the apical third of the mesiobuccal canal with lower values in the TruNatomy group. ProTaper Gold removed more dentin than TruNatomy at the coronal level of mesial roots (1.8% and 1.0%, respectively) (P < 0.05).

CONCLUSIONS

TruNatomy and ProTaper Gold were efficient for performing canal preparation in mandibular molars. The tested systems were similar in terms of untouched canal walls and remaining dentin thickness, and slightly different in the apical transportation of mesial canals and percentage of dentin removal at the coronal third, but without clinically significant errors.

Design, Metallurgical Features, and Mechanical Behaviour of NiTi Endodontic Instruments from Five Different Heat-Treated Rotary Systems

The current study aimed to compare the F1 endodontic instruments from five different heat-treated rotary systems regarding their design, metallurgical properties, and mechanical performance. Five F1 root canal shaping instruments (ProTaper Gold [PTG], Premium Taper Gold, Go-Taper Flex, EdgeTaper Platinum, and Super Files Blue)—plus, a conventional ProTaper Universal (PTU)—which were evaluated regarding their design, nickel/titanium ratio, phase transformation temperatures, microhardness, cyclic fatigue, and torsional and bending strengths. Mood's median test was used for the statistical comparison with a significance set at 5%. The instruments were similar regarding the nickel/titanium ratio and overall design. Go-Taper Flex had the closest transformation temperatures to PTG. PTU and Go-Taper Flex had the highest microhardness (408.3 and 410.5 HVN). The time to fracture of Super Files Blue was three and seven times higher than PTG and PTU, respectively. No difference was observed in the maximum torque to fracture among PTG (1.30 N·cm) and the other systems, except for the Premium Taper Gold (1.05 N·cm) and Go-Taper Flex (1.10 N·cm). Significantly lower bending loads than PTG (269.2 gf) were observed for the EdgeTaper Platinum (158.3 gf) and Premium Taper Gold (103.5 gf) instruments. Super Files Blue outperformed PTG in the cyclic fatigue test, while EdgeTaper Platinum and Premium Taper Gold were more flexible. Premium Taper Gold and Go-Taper Flex showed lower torsional strength.

Confocal laser scanning microscopy evaluation of roots subjected to activation protocol in endodontic microsurgery

This study evaluated the penetration of the irrigant subject to activation after performing retro-preparation in endodontic microsurgery. Forty mandibular premolars were prepared and filled. Subsequently, 1 mm from the root apex was cut using a multi-blade bur and the retro-preparation was performed. In group 1, the retro-cavity was cleaned with 2 mL of saline and then with 2 mL of 5.25% NaOCl gel mixed with 0.1% Rhodamine B. In group 2, the retro-cavity was cleaned with 2 mL of saline, 17% EDTA gel was activated ultrasonically for 30 s and 5.25% NaOCl gel was mixed with 0.1% Rhodamine B and activated for 30 s. After 7 days, the roots were cut at 1mm from the apex and the slices were evaluated with confocal laser scanning microscopy. The samples of group 2 showed statistically better results. The activation protocol proposed resulted in enhanced irrigant penetration when compared to the traditional.

Influence of access cavity preparation on the dentine thickness of mesial canals of mandibular molars prepared with reciprocating instruments

AIM

To evaluate the influence of traditional and conservative access cavity preparations on the remaining dentine thickness in the coronal third of mesial canals of extracted mandibular molars prepared with reciprocating instruments using micro-computed tomography as the analytical tool.

METHODOLOGY

Seventy extracted mandibular molars were scanned at a pixel size of 19 μm. From this initial sample, 20 teeth were selected, pair-matched and distributed into two groups (n = 10) according to the access cavity preparation: traditional (TradAC) or conservative (ConsAC). The root canals were sequentially enlarged with Reciproc Blue R25 (size 25, 0.08v taper) and R40 (size 40, 0.06v taper) instruments. A new scan was performed and the postoperative stacks were coregistered with their respective preoperative datasets. A colour-coded cross sections of the roots were created and used to identify and measure the smallest dentine thickness related to both MB and ML canals at 1.0-mm intervals from the furcation level of up to 5 mm in the apical direction, in both mesial and distal aspects of the roots, before and after preparation. The statistical analyses were performed with paired-samples t-test, independent-samples Student T-test and Chi-Square test with a significance level of 5%.

RESULTS

At all levels of both groups, dentine thickness before preparation was greater than after preparation (p < .05). No difference in the percentage of dentine reduction was observed between TradAC and ConsAC groups (p > .05), but a significantly greater reduction was observed to the distal aspect of the roots (p < .05). After root canal preparation, dentine thinner than 0.5 mm was observed mostly along the distal aspect of the root (10% to 15%) of the MB and ML canals, with no influence of the access cavity type on its incidence to either mesial (X²  = 1.66; p = .2) or distal (X²  = 0.40; p = .5) directions. In the TradAC group, dentine thickness in most slices was greater than 1.0 mm after preparation (n = 124) whilst, in the ConsAC, it ranged from 0.5 to 1.0 mm (n = 136).

CONCLUSION

Traditional or conservative access cavity preparation in extracted mandibular molars did not influence the remaining dentine thickness in the coronal third of mesial canals enlarged with thermomechanically treated nickel-titanium reciprocating instruments.

Influence of the use of chelating agents as final irrigant on the push-out bond strength of epoxy resin-based root canal sealers: A systematic review

This systematic review (PROSPERO - CRD42020150722) was performed to answer the following question: Does the use of chelating agents affect the dislodgment resistance of epoxy resin-based root canal sealers? A search was conducted in PubMed, EMBASE, Scopus, LILACS and Web of Science, hand searching of two endodontic journals and grey literature until September 2020. Extracted data included: teeth used, sample size, root canal preparation, irrigant, chelating solution, neutralisation solution, type of resin-based sealer and obturation approach, storage method and duration, root third and slice thickness, plunger dimension and loading direction and the push-out testing parameters and values. The search retrieved a total of 2.389 studies. After analysis, 12 studies fulfilled the eligibility criteria and were included. Most of the final irrigation protocols with chelating agents had a positive impact and promoted an improvement in the dislodgment resistance of epoxy resin-based sealers to the root dentin.

Methodological proposal for evaluation of adhesion of root canal sealers to gutta-percha

AIM

To compare the bond strength of an epoxy resin-based sealer and two calcium silicate-based sealers (CSS) to gutta-percha discs using a new method.

METHODOLOGY

Round discs of gutta-percha (n = 60), measuring 10 mm in diameter and 2 mm in thickness, were placed on a glass plate and a drop of each sealer (AH Plus, EndoSequence BC Sealer and EndoSeal MTA) was placed on their surface. Another identical disc was placed onto the first one and a standardized weight (0.0981 N) applied over them using a specially developed apparatus. Ten samples prepared for each sealer were submitted to a microshear bond strength test accomplished by a specially designed set-up coupled to a universal testing machine. The Kruskal-Wallis test followed by a post hoc procedure was used to compare groups considering the preliminary analysis of the raw data had indicated the nonadherence to a Gaussian distribution (Shapiro-Wilk, p < .05). Alpha error was set at 5%.

RESULTS

Overall, no premature failure occurred. All sealers had some degree of adhesiveness to gutta-percha discs but with a significant difference amongst them (Kruskal-Wallis, p = .019). The epoxy resin-based sealer (AH Plus) had significantly higher median shear bond strength values (1.43 MPa; 1.40-1.83) compared to EndoSeal MTA (0.53 MPa; 0.46-0.73) (p = .021) and EndoSequence BC Sealer (0.45 MPa; 0.34-0.46) (p = .023), whilst the lowest median value was observed with EndoSequence BC Sealer (0.45 MPa; 0.34-0.46) (p < .05).

CONCLUSIONS

CSS sealers had weaker bonding to gutta-percha when compared to the epoxy resin-based AH Plus sealer. The proposed methodology is an innovative and reproducible method for testing the bond strength of root canal sealers to gutta-percha.

Design, metallurgical features, mechanical performance and canal preparation of six reciprocating instruments

AIM

To compare six reciprocating instruments regarding their geometric design, metallurgical characteristics, mechanical behaviour and ability to prepare root canals.

METHODOLOGY

A total of 246 new 25-mm NiTi instruments (41 per group) from six reciprocating systems (Reciproc, Reciproc Blue, One Files, One Files Blue, Reverso Silver, and WaveOne Gold) were evaluated throughout a multimethod approach regarding their design using stereomicroscopy (number of blades and helix angle) and scanning electron microscopy (blades symmetry, cross section and surface finishing), nickel-titanium composition, phase transformation temperatures, mechanical performance (cyclic fatigue, torsional and bending resistance) and unprepared canal surface area on anatomically matched mandibular molars assessed by micro-CT. One-way ANOVA and post hoc Tukey's or Mood's median tests were selected depending on sample distribution with significance level set at 5%.

RESULTS

The instruments had similarities regarding their metal composition and unprepared canal area, whilst differences in phase transformation temperatures and geometric design (number of blades, surface finishing and tip geometry) were observed. Overall, no difference was observed regarding the maximum torque values (P > 0.05), whilst One Files (72 s) and One Files Blue (414 s) had the shortest and longest times to fracture, respectively (P < 0.05). Similar angles of rotation were observed in Reciproc (310°), One Files (285°) and Reverso Silver (318°) instruments (P > 0.05), which were significantly lower than Reciproc Blue (492°), One Files Blue (456°) and WaveOne Gold (492°; P < 0.05). Maximum bending load demonstrated that Reciproc Blue (201.3 gf) was significantly more flexible that the other instruments (P < 0.05).

CONCLUSION

Although there were similarities in metal composition and percentage of unprepared canal surface, the instruments had differences in the overall geometric design, phase transformation temperatures and in the four mechanical resistance parameters (time to fracture, maximum torque, angle of rotation and maximum bending load).

Influence of variations in the environmental pH on the solubility and water sorption of a calcium silicate-based root canal sealer

AIM

To evaluate the influence of pH variation on the solubility and water sorption of a premixed calcium silicate-based root canal sealer (EndoSequence BC Sealer) compared to the gold standard based on epoxy resin (AH Plus Jet) after immersion in distilled water and phosphate-buffered saline (PBS).

METHODOLOGY

Solubility and water sorption were evaluated after immersion in distilled water or PBS at several pHs (5, 7 and 12) and the values were calculated as percentages of the original mass after 24 h, 7 and 30 days of immersion. The crystalline structures present in the sealers and surface precipitates were assessed by X-ray diffraction. The Shapiro-Wilk's test revealed that data were normally distributed; thus, statistical analysis was performed using one-way anova and Tukey's tests or independent t-test, assuming a 5% α-error.

RESULTS

EndoSequence BC Sealer was associated with significantly greater water sorption and solubility compared to AH Plus Jet in all tested conditions (P < 0.05). The acid environment increased the 24 h solubility of EndoSequence BC Sealer immersed in PBS (P < 0.05) and did not induce significative changes in the water sorption (P > 0.05). Alkaline pH reduced the solubility of EndoSequence BC Sealer and increased that of AH Plus Jet at all experimental times and soaking media (P < 0.05). Alkaline environment also significantly increased the water sorption of AH Plus Jet immersed in PBS (P < 0.05). Immersion in PBS significantly reduced the solubility of EndoSequence BC Sealer and significantly increased that of AH Plus Jet (P < 0.05). Precipitates on the surface of EndoSequence BC Sealer corresponding to hydroxyapatite and calcium carbonate were detected after immersion in PBS at pH 5 and 7 for 30 days.

CONCLUSIONS

EndoSequence BC Sealer had significantly greater solubility and water sorption than AH Plus Jet. Although the alkaline pH and soaking media directly influenced the solubility and water sorption of the sealers, the solubility of AH Plus Jet remained within the limits recommended by ISO 6876, whilst the solubility of the EndoSequence BC Sealer did not comply with ISO recommendations in all the conditions tested.

Do orthodontic tooth movements induce pulp necrosis? A systematic review

BACKGROUND

Orthodontic tooth movements are performed by applying forces on teeth, which may cause alterations within the dental pulp. Previously published systematic reviews on the subject only included a small number of studies that assessed pulp status through reliable diagnostic methods. Since then, new evidence has been published, and a further systematic review on the subject is necessary.

OBJECTIVES

To evaluate whether there is scientific evidence to support the possibility that orthodontic tooth movements could induce pulp necrosis.

METHODS

A systematic search of articles published until June 2020 was performed using MeSH and free terms in the PubMed, Cochrane Library, LILACS, SciELO, Web of Science, EMBASE, Open Grey and Grey Literature databases. Randomized clinical trials (RCTs), nonrandomized clinical trials (nRCTs) and longitudinal (prospective or retrospective) studies that evaluated the pulp status of teeth subjected to orthodontic movements using laser Doppler flowmetry or pulse oximetry were included. The revised Cochrane risk of bias tools for randomized trials (RoB 2) and nonrandomized interventions (ROBINS-I) were used to assess the quality of the included studies. Relevant findings were summarized and evaluated. The overall quality of evidence was assessed through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool.

RESULTS

Initial screening of databases resulted in 353 studies. In total, 285 studies were excluded because they were duplicates. Of 68 eligible papers, fourteen met the inclusion criteria and were selected for full-text reading. Two studies were excluded due to the methods used to evaluate pulp status. Twelve studies (five RCTs, one nRCT and six prospective) were included. Four RCTs were classified as having an unclear risk of bias and one as having a high risk of bias. The nRCT was classified as having a low risk of bias. Two prospective studies were classified as having a moderate risk of bias and four as having a serious risk of bias. The GRADE analysis demonstrated a low to very low quality of evidence.

DISCUSSION

Significant limitations regarding the randomization processes within the included RCTs and a lack of control of confounders on most nonrandomized and longitudinal studies were verified.

CONCLUSIONS

This systematic review indicates that orthodontic movements do not induce loss of pulp vitality with low to very low certainty of evidence.

Effect of different final irrigation protocols on pulp tissue dissolution from an isthmus model

This study assessed the pulp tissue dissolution from isthmus of a two-rooted maxillary premolar using different final irrigation protocols. After root canal preparation, the surface of the tooth was reduced to an extent that the isthmus could be observed, and 1 mg of pulp tissue was introduced into the isthmus which was covered with a glass slide. Following six groups were tested: syringe and needle; subsonic activation; sonic activation; ultrasonic activation; heating followed by sonic activation; and heating followed by ultrasonic activation. Before and after each experiment a photograph of the isthmus was taken at 30× to register the area of the pulp tissue. Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney tests (P < 0.05). Syringe and needle group showed the lower value of pulp tissue dissolution followed by subsonic irrigation procedures. Pulp tissue dissolution was significantly higher when heating was followed by sonic or ultrasonic activation.

Influence of ultraconservative access cavities on instrumentation efficacy with XP-endo Shaper and Reciproc, filling ability and load capacity of mandibular molars subjected to thermomechanical cycling

AIM

To evaluate the influence of ultraconservative access cavities (UltraAC) on canal shaping and filling ability and load capacity of mandibular molars after root canal preparation with XP-endo Shaper (XP) or Reciproc (RC), under simulated clinical conditions. Traditional access cavities (TradAC) were used for comparison.

METHODOLOGY

Forty extracted mandibular molars were scanned by micro-computed tomographic and, based on similar anatomical features, were divided into four groups (n = 10), according to the type of access cavity and canal instrumentation protocol: TradAC/RC, TradAC/XP, UltraAC/RC and UltraAC/XP. All root canal procedures were performed with the teeth placed in a dental mannequin. Teeth were scanned after root canal instrumentation and filling. Unprepared canal area, dentine removed, accumulated hard tissue debris (AHTD), canal transportation, presence of voids and filling material remnants within the pulp chamber were analysed. After restorative procedures, the teeth were subjected to thermomechanical cycling and to a load capacity test. Statistical analyses were performed using two-way anova test, considering the randomized blocks design (P < 0.05).

RESULTS

The percentage of unprepared canal area was significantly lower in TradAC groups when compared to UltraAC groups (P < 0.05), regardless of the instrument used. The UltraAC/XP group had significantly lower percentage of root dentine removed when compared to other groups (P < 0.05). UltraAC/XP and TradAC/XP groups had significantly lower percentages of AHTD than UltraAC/RC and TradAC/RC groups (P < 0.05). Regarding canal transportation, in the MB root canals, the TradAC/XP group had significantly lower values than other groups (P < 0.05). In general, in ML and distal root canals, TradAC/XP and UltraAC/XP groups had significantly lower values of canal transportation when compared to other groups (P < 0.05). Moreover, the UltraAC/RC had the greatest canal transportation values in MB and distal canals. The UltraAC groups had significantly greater percentages of voids and volume of remaining root filling material within the pulp chamber after cleaning procedures than TradAC groups (P < 0.05). There was no difference in the load capacity amongst groups (P < 0.05).

CONCLUSION

The UltraAC/XP and UltraAC/RC groups had significantly greater areas of unprepared canal walls, significantly more voids and volume of root filling material remnants within the pulp chamber after canal filling. UltraAC/XP was associated with significantly less root dentine removal and significantly more AHTD whilst TradAC/XP had overall significantly less canal transportation. No differences were observed in the load capacity amongst groups.

Efficacy of an arrow-shaped ultrasonic tip for the removal of residual root canal filling materials

This study aimed to evaluate the efficacy of supplementary methods to remove the remaining root filling material from root canals. Twenty mandibular single-rooted teeth were instrumented with Reciproc 25/0.08 and filled with gutta-percha and AH-Plus sealer, followed by a micro-CT scanning. The retreatment procedures were performed, the samples were rescanned and divided into two groups (n = 10) according to the supplementary method: XP-endo Finisher R and Clearsonic tip. The samples were rescanned and the volume of remaining root filling material was quantified. Data were analysed statistically (P < 0.05). The amount of filling material removed after supplementary methods was higher compared with retreatment procedure (P < 0.05). XP-endo Finisher R promoted a greater percentage of filling materials reduction in the entire root canal and apical third compared with Clearsonic tip (P < 0.05). Supplementary methods were effective in the reduction of root filling materials. XP-endo Finisher R removed more root filling material than Clearsonic tip.

Preserving dentine in minimally invasive access cavities does not strength fracture resistance of restored mandibular molars

AIM

To evaluate the correlation between the volume of dental hard tissues removed and the fracture resistance of mandibular molar teeth with ultraconservative (UltraAC) or traditional (TradAC) access cavity preparations.

METHODOLOGY

Sixty recently extracted and intact mandibular first molars were scanned in a microcomputed tomographic (micro-CT) device, anatomically matched and assigned at random to 2 groups (n = 30), according to the access cavity type: UltraAC or TradAC. After access preparation, mesial and distal canals were prepared using Reciproc instruments and a new scan was taken. The volumes of pulp chamber and dental hard tissues in each specimen were measured before and after the experimental procedures, and the percentage volume reduction of hard tissues calculated for the entire tooth and for the crown separately. Teeth were then root filled, restored and subjected to fracture resistance tests in an universal testing machine. The force required to fracture was recorded in Newtons (N). The adherence of the variables to a Gaussian curve was verified using a Shapiro-Wilk test. Skewed data were analysed with nonparametric Wilcoxon signed rank or Spearman correlation tests, whilst the normally distributed data were analysed with a dependent samples Student t-test. Level of significance was set at 5%.

RESULTS

Pre-operatively, no difference was observed between groups regarding the volume of pulp canal space or dental hard tissues (P > 0.05). After access preparation, volumes of the removed hard tissues from the entire tooth and from the crown were significantly greater in teeth prepared with TradAC than with UltraAC (P < 0.05). No significant difference was observed in the fracture resistance values between TradAC (902.9 ± 347.8 N) and UltraAC (948.7 ± 405.7 N) groups (P = 0.975). The Spearman test was unable to identify a correlation between fracture resistance and percentage volume of removed dental hard tissues in the entire root (P = 0.525, r = -0.084) or only in the crown (P = 0.152, r = -0.187).

CONCLUSION

The volume of hard dental tissues removed, although greater in teeth with TradAC compared to UltraAC, did not correlate with the fracture resistance results, indicating that a minimally invasive access cavity did not increase the resistance of restored mandibular first molars to fracture.

Solubility of bioceramic- and epoxy resin-based root canal sealers: A systematic review and meta-analysis

This systematic review and meta-analysis evaluated whether epoxy resin-based root canal sealers present an increased solubility than calcium silicate-based root canal sealers. A systematic search was performed in the following databases: PubMed, Science Direct, Scopus, Web of Science and Open Grey. The inclusion criteria consisted of in vitro studies that compared the solubility of epoxy resin-based and calcium silicate-based sealers. The quality assessment and data extraction of the selected articles were performed. The meta-analysis of the pooled data and the subgroups according to the root thirds were carried out using the RevMan software (P < 0.05). After the duplicate removal and eligibility criteria assessment, a total of 22 studies were included all of them were considered as having a low risk of bias. The meta-analysis demonstrated overall lower solubility of AH Plus. AH Plus presented lower solubility than Bio-C Sealer, BioRoot RCS, MTA Fillapex, Sealer Plus and Total Fill BC Sealer.

Comparison of design, metallurgy, mechanical performance and shaping ability of replica-like and counterfeit instruments of the ProTaper Next system

AIM

To compare the ProTaper Next (PTN) system with a replica-like and a counterfeit system regarding design, metallurgy, mechanical performance and shaping ability.

METHODOLOGY

Replica-like (X-File) and counterfeit (PTN-CF) instruments were compared to the PTN system regarding design (microscopy), phase transformation temperatures (differential scanning calorimetry), nickel-titanium ratio (energy-dispersive X-ray spectroscopy), cyclic fatigue, torsional resistance, bending strength, and untouched canal areas in extracted mandibular molars (micro-CT). anova, post hoc Tukey's and Kruskal-Wallis tests were used according to normality assessment (Shapiro-Wilk test) with the significance level set at 5%.

RESULTS

Overall similarities in design and nickel-titanium (Ni/Ti) ratio were observed amongst instruments with the X-File having a smoother surface finish. PTN and PTN-CF had mixed austenite plus R-phase (R-phase start approximately at 45 ºC and near 30 ºC, respectively), whilst X-File instruments were austenitic (R-phase started at approximately at 17 ºC) at room temperature (20 ºC). PTN-CF had the greatest inconsistency in the phase transformation temperatures. Time to fracture of PTN-CF X2 and X3 was significantly shorter than PTN and X-File instruments (P < 0.05), whilst no difference was noted in maximum torque to fracture amongst the tested systems (P > 0.05). X-Files and PTN-CF had a stress-induced phase change during bending load. Mean unprepared surface areas of root canals were 25.8% (PTN), 31.1% (X-File) and 32.5% (PTN-CF) with no significant difference amongst groups (P > 0.05).

CONCLUSION

Similarities amongst the systems were noted in the Ni/Ti ratio and maximum torque to fracture, whilst differences were observed in the design, phase transformation temperatures and mechanical behaviour. The ProTaper Next counterfeit instruments could be considered as the less secure system considering its low-cyclic fatigue resistance. Apart from these differences, the unprepared canal surface areas, obtained with the tested systems, were similar.

Glide Path with Reciprocating Driven Pathfinding Instrument: Performance and Fracture Rate

INTRODUCTION

This study assessed the number of mesial and distal canals of mandibular molars in which the R-Pilot pathfinding reciprocating instrument reached the working length (WL) during macro glide path procedure. Fracture and deformation rates were also evaluated.

METHODS

One hundred fifty-six root canals of 52 teeth were scouted to the length of the apical foramen. Then the R-Pilot instrument was positioned at the canal orifice and activated. The instrument was moved by using a pecking motion and light apical pressure. This procedure was repeated in an attempt to reach the WL. The type of fracture and/or instrument deformation was assessed by scanning electron microscopy, whereas the roots with fractured instruments were scanned through micro-computed tomography. The percentage frequency distribution of fractures, deformations, and root canals in which the R-Pilot reached the WL were recorded and statistically compared by using the Pearson's χ² test with α = 5%.

RESULTS

R-Pilot instruments reached the WL in 139 root canals (89.10%), and χ² test showed a significant difference between the observed frequencies and the expected frequencies (χ² = 95.41, P = .000). The observed frequencies of fractures (2.56%) and deformations (1.92%) were also significantly lower than the expected (fracture: χ² = 140.41, P = .000; deformation: χ² = 144.23, P = .000). Fractures occurred mostly at the apical and curved parts of the root canals.

CONCLUSIONS

R-Pilot reached the WL in 89.10% of the root canals of mandibular molars with fracture and deformation rates of 2.56% and 1.92%, respectively.

Final Endodontic Irrigation with 70% Ethanol Enhanced Calcium Hydroxide Removal from the Apical Third

INTRODUCTION

The purpose of this study was to evaluate the cleanliness of root canal walls and dentinal tubules after attempting to remove the calcium hydroxide dressing with different irrigant solutions and the use of nonactivated irrigation or passive ultrasonic irrigation (PUI).

METHODS

After root canal instrumentation, 80 single-rooted teeth were filled with calcium hydroxide mixed with propylene glycol and 0.1% rhodamine B dye and inserted into canals with a Lentulo spiral. The calcium hydroxide dressing was initially removed with 10 mL saline solution and reinstrumentation with the master apical file. Then, the samples were randomly assigned into 8 experimental groups (n = 10) according to the irrigant solution with or without PUI: 2.5% sodium hypochlorite, 17% ethylenediaminetetraacetic acid + 1.25% sodium lauryl ether sulfate (EDTA-T), 37% phosphoric acid, or 70% ethanol. A final flush with 5 mL saline solution was performed. The percentage of clean root canal walls and the depth of clean dentinal tubules were measured with images of confocal laser scanning microscopy. The groups were compared using the 2-way analysis of variance test with the Bonferroni post hoc test for depth analysis and the Kruskal-Wallis with Dunn post hoc test for the perimeter analysis.

RESULTS

Irrigation with 70% ethanol presented a significantly higher percentage of clean root canal walls and a higher depth of clean dentinal tubules when compared with irrigation with 2.5% sodium hypochlorite and 17% EDTA-T for both irrigation methods (P < .05). No differences were observed between nonactivated irrigation or PUI protocols (P > .05).

CONCLUSIONS

Seventy percent ethanol enhanced calcium hydroxide removal from the apical root third compared with 2.5% sodium hypochlorite or 17% EDTA-T.

Contrast-enhanced micro-CT to assess dental pulp tissue debridement in root canals of extracted teeth: a series of cascading experiments towards method validation

AIM

To validate a new method for the evaluation of pulp tissue debridement in the root canals of extracted teeth using an impregnation protocol involving potassium triiodide, a radiocontrast solution known as Lugol's, combined with micro-computed tomographic (micro-CT) imaging.

METHODOLOGY

The impact of NaOCl on the radiopacity of Lugol's solution was assessed using a two-fold dilution series of Lugol in distilled water and 5.25% NaOCl, which were then pipetted into transparent dishes and radiographed. To verify the influence of Lugol on the proteolytic effect of NaOCl, a dissolution test was performed using fresh bovine meat. Ten slices did not undergo any tissue processing, whilst twenty slices were fixed in formaldehyde for 24 h. After that, 10 of them were immersed in Lugol for another 24 h. Then, all specimens were placed in NaOCl and the time required for a complete tissue dissolution was recorded. For the last experiments (histological validation and micro-CT assessment), 8 extracted mandibular premolars with formerly vital pulps were immersed in buffered formalin, scanned in a micro-CT device, accessed, immersed in Lugol for 7 days and scanned again. Then, the root canals of 5 teeth were prepared and scanned, and the volume of remaining pulp tissue identified and quantified, whilst 3 teeth were histologically processed. The same specimens were subjected to histological assessment, and the images of the histologic sections were registered with the corresponding micro-CT images to verify whether the pulp tissue in the histological sections matched its counterpart in the Lugol-impregnated tissues identified in the micro-CT slices.

RESULTS

There was no discernible effect on radiopacity when NaOCl was mixed with Lugol's solution. Tissue processing did not affect the time required for the complete dissolution of fresh bovine meat. Histological evaluation revealed a correlation between micro-CT and histological images confirming the identification of Lugol-impregnated pulp tissue in micro-CT images.

CONCLUSIONS

The radiocontrast Lugol's solution was unaffected by NaOCl and did not interfere with its soft tissue dissolution capability. The impregnation protocol using Lugol's solution allowed the visualization of pulp tissue on the micro-CT images and the identification of pulp remnants after chemical-mechanical canal procedures.

Current status on minimal access cavity preparations: a critical analysis and a proposal for a universal nomenclature

In the last decade, several access cavity designs involveing minimal removal of tooth tissue have been described for gaining entry to pulp chambers during root canal treatment. The premise behind this concept assumes that maximum preservation of as much of the pulp chamber roof as possible during access preparation would maintain the fracture resistance of teeth following root canal treatment. However, the smaller the access cavity, the more difficult it may be to visualize and debride the pulp chamber as well as locate, shape, clean and fill the canals. At the same time, a small access cavity may increase the risk of iatrogenic complications as a result of poor visibility, which may have an impact on treatment outcome. This study aimed to critically analyse the literature on minimal access cavity preparations, propose new nomenclature based on self-explanatory abbreviations and highlight the areas in which more research is required. The search was conducted without restrictions using specifics terms and descriptors in four databases. A complementary screening of the references within the selected studies, as well as a manual search in the highest impact journals in endodontics, namely International Endodontic Journal and Journal of Endodontics, was also performed. The initial search retrieved 1831 publications. The titles and abstracts of these papers were reviewed, and the full text of 94 studies was assessed. Finally, a total of 28 studies were identified as evaluating the influence of minimally invasive access cavity designs on the fracture resistance of teeth and on the different stages of root canal treatment (orifice location, canal shaping, canal cleaning, canal filling and retreatment). Overall, the studies had major methodological drawbacks and reported inadequate and/or inconclusive results on the utility of minimally invasive access preparations. Furthermore, they offered limited scientific evidence to support the use of minimally invasive access cavities to improve the outcome of root canal treatment and retreatment; they also provided little evidence that they preserved the fracture resistance of root filled teeth to a greater extent than traditional access cavity preparations. It was concluded that at present, there is a lack of supporting evidence for the introduction of minimally invasive access cavity preparation into routine clinical practice and/or training of undergraduate and postgraduate students.

Bending, buckling and torsional resistance of rotary and reciprocating glide path instruments

AIM

To evaluate the bending, buckling and torsional resistance of ProGlider (PG) (Dentsply Sirona, Ballaigues, Switzerland), R-Pilot (RP) (VDW, Munich, Germany) and WaveOne Gold Glider (WOGG) (Dentsply Sirona).

METHODOLOGY

Ninety instruments were used: 30 PG (size 0.16, .02v taper), 30 RP (size 0.125, .04 taper) and 30 WOGG (size 0.15, .02v taper). The bending resistance test was performed on 10 randomly selected instruments of each system according to ISO 3630-1 specifications. For the buckling resistance test, a loading was applied in the axial direction of each instrument using a universal test machine, with a 20 N cell and 15 mm min^-1 speed, in the axial direction. When a lateral elastic displacement of 1 mm occurred, the force was registered. The torsional resistance test was performed according to ISO 3630-1 specifications. Statistical analysis was performed using one-way anova and post hoc Student-Newman-Keuls test (P < 0.05).

RESULTS

WOGG had the lowest bending resistance, whilst RP had the highest bending resistance (P < 0.05). RP also had the highest buckling resistance, and WOGG had the lowest (P < 0.05). PG had intermediate results regarding bending and buckling resistance, with significant differences to RP and WOGG (P < 0.05). RP had the highest torsional strength and the lowest angular deflection when compared to PG and WOGG (P < 0.05). No differences in the torsional strength and angular deflection were observed between WOGG and PG (P> 0.05).

CONCLUSION

The glide path instruments had different behaviours in term of bending, buckling and torsional resistance.

The influence of the addition of surfactants to sodium hypochlorite on the removal of hard tissue debris

AIM

To evaluate the effect of the addition of surfactants to sodium hypochlorite (NaOCl) on the removal of accumulated hard tissue debris (AHTD), before and after final irrigation with 17% EDTA, from mesial canals of mandibular molars through microcomputed tomographic (micro-CT) analysis.

METHODOLOGY

Thirty moderately curved mandibular mesial roots with Vertucci type II canal configuration were selected and scanned in a micro-CT device at an isotropic resolution of 22.9 μm. The specimens were assigned to three groups (n = 10) with respect to the root length, degree of curvature of the mesial root, volume and 3D anatomy of the root canals according to the irrigating solution used during root canal preparation: 2.5% NaOCl and 0.1% Benzalkonium Chloride, 2.5% NaOCl and 0.1% Tween 80 and 2.5% NaOCl without additives. The root canals were instrumented up to Reciproc R25 instrument. Then, the specimens were scanned again after canal preparation and after final irrigation with 17% EDTA, and the registered data sets were examined to evaluate the percentage of AHTD. For comparison between the different groups before and after using 17% EDTA, the Kruskal-Wallis test was used with a significance level of 5%. For comparison between the same groups before and after using 17% EDTA, the Wilcoxon test was used with a significance level of 5%.

RESULTS

None of the irrigant solutions tested was able to completely eliminate hard tissue debris from mesial canals of mandibular molars. There were no significant differences in the percentage of AHTD amongst the different irrigation solutions (P > 0.05). Final irrigation with 17% EDTA significantly reduced the percentage of AHTD (P < 0.05), without differences amongst the groups (P > 0.05).

CONCLUSIONS

The addition of surfactants to NaOCl did not affect the removal of AHTD from mesial canals of extracted mandibular molars. Final irrigation with 17% EDTA significantly improved AHTD removal.

Effects of alcohol and nicotine consumption on the development of apical periodontitis in rats: a correlative micro-computed tomographic, histological and immunohistochemical study

AIM

To evaluate the effects of alcohol and nicotine, when used alone or simultaneously, in the development of apical periodontitis induced in rats, using a correlative analytic approach with micro-CT, histological and immunohistochemical analysis.

METHODOLOGY

Twenty-eight male Wistar rats were arranged into four groups: Control, Nicotine, Alcohol and Alcohol + Nicotine. The alcohol groups were exposed to self-administration of a 25% alcohol solution, whilst the other groups drunk only filtered water. The nicotine groups received daily intraperitoneal injections of a solution with 0.19 μL of nicotine per mL, whilst the other groups received saline solution. The pulps of the left mandibular first molars were exposed for 28 days to induce periapical lesions. Throughout the experiment, drug administration was maintained, and the animals had their weight and solid and liquid consumption measured. After euthanasia, the mandibles were removed and the area, volume and major diameter of the periapical lesions were measured using micro-computed tomography images. The samples were submitted to histopathological evaluation and immunohistochemistry for RANKL and PTHrP. Statistical analysis was undertaken with a significance level of 5%. Nonparametric data were analysed using the Kruskal-Wallis test followed by Dunn's test, whilst one-way anova followed by Tukey's test was performed for parametric data.

RESULTS

The alcohol groups had lower solid and liquid consumption and gained less weight when compared to the nonalcohol groups (P < 0.05). The Alcohol + Nicotine group had lesions with significantly larger volume and area when compared to the other groups (P < 0.05), whilst the Alcohol or Nicotine groups had significantly larger lesions than the control group (P < 0.05). There was no significant difference in the largest diameter of the lesions amongst groups (P > 0.05). The experimental groups had greater inflammatory response scores than the control group (P < 0.05), and the representative samples had more pronounced immunoreaction against RANKL and PTHrP antibodies.

CONCLUSIONS

Alcohol and nicotine consumption exacerbated the inflammatory response and the development of periradicular lesions in rats. The association of both substances enhanced their harmful effects.

Does tobacco smoking predispose to apical periodontitis and endodontic treatment need? A systematic review and meta-analysis

BACKGROUND

Controversial findings exist in the literature regarding the association between tobacco smoking and development of apical periodontitis or need for root canal treatment, with some studies reporting an increase in the prevalence of these outcomes in smokers, whilst others reporting no association.

AIM

To evaluate if there is scientific evidence to support an association between tobacco smoking and a greater prevalence of apical periodontitis and/or root canal treatments.

DATA SOURCES

A systematic search was performed using MeSH terms and free terms in the PubMed, Scopus, Virtual Health Library (VHL), Cochrane library and Open Gray databases.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS

Observational studies that evaluated the association between smoking and the development or healing of periapical lesion and/or the prevalence of root canal treatment in humans were included.

STUDY APPRAISAL AND SYNTHESIS METHODS

A quality assessment of included studies was performed, and the relevant information and findings were evaluated. A meta-analysis using nine included studies was performed through RevMan software, and the certainty of evidence was evaluated through GRADE.

RESULTS

Fifteen studies were included, of which 10 were classified as low risk of bias, 4 were considered as moderate risk of bias and 1 as high risk of bias. Ten studies reported that smoking was associated with a greater prevalence of periapical periodontitis and/or root canal treatment. Five studies reported no association. Nine studies were included in the pooled meta-analysis, comprising two subgroups: apical periodontitis and root canal treatment. From these nine studies, eight studies were included in the apical periodontitis subgroup meta-analysis and demonstrated that this condition was significantly more prevalent in smokers when compared to the nonsmokers (odds ratio = 2.78[CI: 1.60, 4.85], P < 0.001; I²  = 79%; no adjusted odds ratio). Three studies were included in the root canal treatment subgroup meta-analysis and demonstrated an increased prevalence in smokers when compared to the nonsmokers (odds ratio = 2.73 [CI: 1.06, 2.83], P < 0.001; I²  = 72%; no adjusted odds ratio). The pooled meta-analysis demonstrated that smokers had twice the chance of having apical periodontitis and/or root canal treatment when compared to nonsmokers (odds ratio of 2.42 [CI: 1.59, 3.68], P < 0.01; I²  = 85%). The GRADE analysis demonstrated moderate certainty of evidence.

LIMITATIONS

Several confounding factors were identified such as misinformation regarding the period of time subjects had smoked, as well as the frequency of smoking and the number of cigarettes consumed. No adjustment in odds ratio data for confounding was performed.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

This systematic review and meta-analysis indicate that tobacco smokers have an increased prevalence of periapical periodontitis and root canal treatments with moderate certainty of evidence.

The effect of ozone therapy in root canal disinfection: a systematic review

AIM

To answer the following focused question: 'As regards microorganism load reduction for patients undergoing root canal treatment, is the use of ozone therapy comparable to conventional chemomechanical techniques using sodium hypochlorite (NaOCl)?'

DATA SOURCES

A systematic review was conducted using controlled vocabulary and free-text key words in the following databases: PubMed, Science Direct, Scopus, Web of Science and Open Grey until 2 November 2018. Additional studies were sought through hand searching of endodontic journals.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS

The inclusion criteria comprised studies that compared microbial reduction in root canals after treatments with ozone and NaOCl in extracted mature human teeth or randomized clinical trials.

STUDY APPRAISAL AND SYNTHESIS METHODS

The quality assessment of included laboratory studies was performed with the following parameters: (i) sample size calculation, (ii) samples with similar dimensions, (iii) control group, (iv) standardization of procedures, (v) statistical analysis and (vi) other risk of bias. For randomized clinical trials, the qualitative analysis of the studies was performed from the bias risk assessment using the tool 'Bias Risk Assessment of Randomized Controlled Studies' Cochrane Handbook 5.0.2.

RESULTS

The search resulted in 180 published studies. After removal of duplicate studies and full-text analysis, eight studies were selected and seven were considered low risk of bias (seven ex vivo studies and one random clinical trial). Overall, the results demonstrated that ozone therapy provides significantly less microbial load reduction than NaOCl. As an adjunct in chemomechanical preparation, ozone was ineffective in increasing the antimicrobial effect of NaOCl. Ozone performance was strongly associated with the application protocol used: it is dose, time and bacterial strain dependent, besides the correlation with the use of complementary disinfection sources.

LIMITATIONS

A restricted number of randomized clinical trial was found, and the difference amongst the methodology of the studies did not allow a meta-analysis to be performed.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Although the selected studies had limitations, this review reached a satisfactory methodological and moderate evidence quality contributing to important preliminary information regarding ozone therapy. As regards load reduction of microorganisms for patients undergoing root canal treatment, ozone is not indicated neither to replace nor to complement the antimicrobial action of NaOCl.

XP-endo Finisher R instrument optimizes the removal of root filling remnants in oval-shaped canals

AIM

To evaluate the performance of XP-endo Finisher R instruments when removing root filling remnants from oval-shaped canals using microcomputed tomographic (micro-CT) imaging as the analytical tool. Passive ultrasonic irrigation (PUI) was used as a reference technique for comparison.

METHODOLOGY

Twenty mandibular incisors with oval-shaped canals were matched based on similar anatomic features of the canal (volume, aspect ratio and 3D configuration) after scanning procedures. The canals were prepared with Reciproc R25 instruments, filled with gutta-percha and AH Plus sealer using the single-cone technique and retreated up to a Reciproc R40 instrument. After retreatment procedures, the specimens were rescanned, and the homogeneity between the specimens, the oval-shaped anatomy and the remaining filling material were confirmed. The pair-matched samples were assigned to two experimental groups (n = 10), according to the supplementary approach used: XP-endo Finisher R or PUI. Each sample was scanned after each endodontic procedure. The volume of remaining root filling material was quantified before and after the use of each supplementary approach. This analysis was performed considering the total canal (Student t-test) and also by thirds (anova procedure followed by a Bonferroni correction). Data were analysed statistically with a significance level of 5%.

RESULTS

The volume of root filling material at baseline was similar between the groups (t-test, P = 0.787). XP-endo Finisher R removed significantly more root filling material compared to PUI (t-test, P = 0.015), as it removed a mean of ≅32% material compared to 12% for the PUI. There was no difference in the amount of root filling material removed in the root canal thirds after using both supplementary approaches (one-way anova, P = 0.07 for XP-endo Finisher R and P = 0.886 for PUI).

CONCLUSIONS

Both supplementary approaches significantly reduced the volume of remaining root filling material from oval-shaped canals. The XP-endo Finisher R instrument removed significantly more root filling material than PUI. None of the supplementary approaches was able to render oval-shaped canals completely free from remaining root filling material.

Volume and/or Time of NaOCl Influences the Fracture Strength of Endodontically Treated Bovine Teeth

Abstract The aim of this study was to evaluate whether amplifying the volume and/or time of contact of NaOCl affects the fracture strength of endodontically treated bovine teeth. Four bovine incisors from 10 animals were allocated into 4 groups using a split-mouth design. Root canals were instrumented using a sequence of 4 manual stainless steel files and irrigated with a 5.25% alkalized NaOCl solution. The total volume and time of irrigation, per sample, varied among the groups as following: standard volume and time of contact - 15 mL/11.5 min; volume raise - 30 mL/11.5 min; time of contact raise - 15 mL/19 min; and volume and time of contact raise - 30 mL/19 min. Samples were subjected to a fracture resistance assay. At p=0.05, two-way ANOVA statistically scrutinized the results. Effect size of NaOCl time of contact and volume were also calculated (η2). The variation in time (p=0.000), volume of irrigation (p=0.000) and the combination of both (p=0.038) negatively influenced the fracture resistance. Standard volume and time of irrigation showed the highest fracture strength while isolated increase in volume or time reduced in 25% and 37%, respectively, the fracture resistance; the simultaneous increase in volume and time of irrigation promoted a reduction of 47%. Effect size of NaOCl time of contact was superior (0.746) than the volume (0.564). Raising the volume and/or time of a 5.25% alkalized NaOCl solution reduces the fracture resistance of endodontically treated bovine teeth.

Evaluation of Apically Extruded Debris Using Positive and Negative Pressure Irrigation Systems in Association with Different Irrigants

This study evaluated the amount of apically extruded debris after chemo-mechanical preparation (CMP) using positive and negative pressure irrigation systems [Conventional irrigation (CI) and EndoVac (EV)] in association with different irrigants [6% Sodium Hypochlorite (NaOCl), 2% Chlorhexidine gel + saline solution (CHXg + SS), 2% Chlorhexidine solution (CHXs) or Saline solution (SS)]. Eighty mandibular premolars with single root canals were selected and randomly assigned into 8 groups (n = 10) according to the irrigation system and the irrigant used during CMP: G1 (EV + NaOCl), G2 (EV + CHXg + SS), G3 (EV + CHXs), G4 (EV + SS), G5 (CI + NaOCl), G6 (CI + CHXg + SS), G7 (CI + CHXs) and G8 (CI + SS). Reciproc® R25 files (25/.08) were used during the CMP and the extruded debris from each tooth was collected in pre-weighted Eppendorf tubes and dried. The average weight of debris was assessed using a microbalance, and the data were statistically analyzed using ANOVA and the post hoc Tukey's test (a = 0.05). All groups were associated with debris extrusion. EV was the irrigation system with less extruded debris (p < 0.05). No differences were observed regarding the irrigant when EV was used. When CI was used, CHXg + SS were associated with lower debris extrusion (p < 0.05). It was concluded that no irrigation protocol succeeded in preventing debris extrusion. EV resulted in lower levels of debris extrusion than CI. The use of CHXg + SS resulted in lower debris extrusion.

Frequency of root resorption following trauma to permanent teeth

This retrospective study evaluated the frequency of development of root resorption in dental trauma cases involving supporting tissue. For 249 traumatized teeth of 125 patients aged between 7 and 51 years, we collected data on the gender and age of the patient, the teeth involved, the type of trauma, and the period between dental injury and initial examination. Radiographic parameters examined in relation to root resorption included the presence of inflammatory external root resorption, internal root resorption, replacement resorption, and canal calcification. Data were analyzed by chi-squared test, Fisher's exact test, and mult iple logistic regression (P < 0.05). The results indicated that there was a significant relationship between the period from the date of injury until initial examination and the occurrence of inflammatory external resorption (P = 0.0199), as well as the type of injury (P = 0.0406). Furthermore, external resorption was most frequently associated with intrusive luxation (92.8%), followed by avulsion (89.0%), lateral luxation (80.2%), and extrusive luxation (77.4%). Among the types of dental injury, replacement resorption was observed more frequently in cases of avulsion (87.2%). The only factor that was significantly associated with this type of resorption was the type of injury (P < 0.0001). Root resorption is observed more frequently and its risk of development is higher in cases of severe trauma, especially avulsion and intrusive luxation.

Micro-CT assessment of dentinal micro-cracks after root canal filling procedures

AIM

To evaluate the frequency of dentinal micro-cracks after root canal filling procedures with GuttaCore (GC), cold lateral compaction (CLC) and warm vertical compaction (WVC) techniques in mandibular molars using micro-computed tomographic analysis.

METHODOLOGY

Thirty mesial roots of mandibular molars, with a type II Vertucci's canal configuration, were prepared to working length with a Reciproc R40 instrument and randomly assigned to one of the three experimental groups (n = 10), according to the technique used for root filling: GC, CLC or WVC. The GC group was filled with a size 40 GC obturator, whilst CLC and WVC groups used conventional gutta-percha cones. AH Plus sealer was used in all groups. The specimens were scanned at an isotropic resolution of 14.25 μm before and after root canal preparation and after root filling. Then, all pre- and postoperative cross-sectional images of the roots (n = 41 660) were screened to identify the presence of dentinal defects.

RESULTS

Overall, 30.75% (n = 12 810) of the pre- + post-filling images displayed dentinal defects. In the GC, CLC and WVC groups, dentinal micro-cracks were observed in 18.68% (n = 2510), 15.99% (n = 2389) and 11.34% (n = 1506) of the cross-sectional images, respectively. All micro-cracks identified in the post-filling scans were also observed in the corresponding post-preparation images.

CONCLUSION

Root fillings in all techniques did not induce the development of new dentinal micro-cracks.

Evaluation of radioprotective effect of aloe vera and zinc/copper compounds against salivary dysfunction in irradiated rats

The aim of this study was to evaluate the radioprotective and reparative effects of compounds based on aloe vera, zinc, and copper against salivary gland dysfunction in Wistar rats. A total of 150 Wistar rats were randomly divided into 12 groups, in which the animals received aloe vera and/or zinc and copper. In eight of these groups the animals were also subjected to irradiation before or after administration of the substances. After 27 days, sialometry tests were performed. Data were analyzed using ANOVA and the Tukey test (P < 0.05). Rats that had been administered aloe vera before or after irradiation showed a significantly higher salivary flow rate than rats that had been simply irradiated. When both substances were administered, a statistically significant difference in the salivary flow rate was observed in comparison with the irradiation alone group seven days after irradiation. The present results suggest that aloe vera exerts positive protective and reparative effects, and can be considered a potential radioprotective substance.

Comparison of apically extruded debris after large apical preparations by full-sequence rotary and single-file reciprocating systems

AIM

To evaluate the amount of apically extruded debris produced by ProTaper Universal (PTU), ProTaper Next (PTN), WaveOne (WO) and Reciproc (R) systems after large apical preparations.

METHODOLOGY

Sixty mandibular premolars with a single canal were selected and randomly assigned into 4 groups (n = 15) according to the system used for root canal preparation: PTU, PTN, WO and R groups. Canal preparations were performed up to size 40 in each group. Distilled water was used as an irrigant, and the apically extruded debris from each tooth was collected in pre-weighted glass vials and dried. The average weight of debris was assessed using a microbalance, and the data were analysed statistically using one-way analysis of variance and the post hoc Tukey multiple comparison test (α = 0.05).

RESULTS

The PTU system was associated with significantly more debris than the other systems (P < 0.05). No significant differences were found between PTN, WO and R systems (P > 0.05).

CONCLUSIONS

All systems were associated with apical debris extrusion when canals were prepared to a large apical size. The PTU system was associated with more debris extrusion.

Morphological changes related to age in mesial root canals of permanent mandibular first molars

The aim of this study was to evaluate age-related morphological canal changes in mesial root canals of mandibular first molars of known ages. Fifty-six specimens were selected for this study and distributed into the following four age groups (n. 14): a) Group of children under 13 years, b) Group of adolescents (from 14 to 19 years), c) Group of young adults (from 20 to 39 years) and d) Group of older adults (over 40 years). The specimens were in perfect condition because after extraction they were carefully cleaned, sterilized, identified and stored in water. In order to improve the cleaning, they were placed in 1% sodium hypochlorite solution for four hours and rinsed in 10 vol. hydrogen peroxide for 8 hours. After that, a clearing technique was performed to illustrate root canal anatomy. Digitalized images of all samples were obtained by use of a stereomicroscope. Canals were noticeably simpler in older adults: they were sharply defined and narrow, sometimes too narrow. Calcification nuclei were not found and there were only a few remains of internuclear spaces. The canal system appeared cleaner, clearer and more sharply defined than in the other age groups. It may be concluded that there is a correlation between aging and morphological changes in the mesial root canals of mandibular first molars.

Knowledge of Dentists on the Management of Tooth Avulsion Injuries in Rio de Janeiro, Brazil

PURPOSE

To evaluate dentists' professional experience and knowledge of emergency management of tooth avulsion injuries in Rio de Janeiro, Brazil.

MATERIALS AND METHODS

A total of 100 questionnaires were evaluated. The first part of the questionnaire consisted of questions regarding personal information. The second part evaluated dentists' knowledge of emergency management in cases of dental avulsion. The responses for each question were counted and expressed as percentages.

RESULTS

All dentists had a college degree or above. Only three dentists had a Master's or PhD degree. Most of the dentists (94.5%) considered time and storage media important for the prognosis of avulsed teeth. However, the dentists did not show consistent responses about the adequate time and ideal storage media to transport avulsed teeth.

CONCLUSION

The study highlighted Brazilian dentists' need for continuing education in order to improve current knowledge in emergency management of avulsed teeth.

Influence of cone beam CT enhancement filters on diagnosis ability of longitudinal root fractures

OBJECTIVES

To determine whether cone beam CT (CBCT) enhancement filters influence the diagnosis of longitudinal root fractures.

METHODS

40 extracted human posterior teeth were endodontically prepared, and fractures with no separation of fragments were made in 20 teeth of this sample. The teeth were placed in a dry mandible and scanned using a Classic i-CAT® CBCT device (Imaging Sciences International, Inc., Hatfield, PA). Evaluations were performed with and without CBCT filters (Sharpen Mild, Sharpen Super Mild, S9, Sharpen, Sharpen 3 × 3, Angio Sharpen Medium 5 × 5, Angio Sharpen High 5 × 5 and Shadow 3 × 3) by three oral radiologists. Inter- and intraobserver agreement was calculated by the kappa test. Accuracy, sensitivity, specificity and positive and negative predictive values were determined. McNemar test was applied for agreement between all images vs the gold standard and original images vs images with filters (p < 0.05).

RESULTS

Means of intraobserver agreement ranged from good to excellent. Angio Sharpen Medium 5 × 5 filter obtained the highest positive predictive value (80.0%) and specificity value (76.5%). Angio Sharpen High 5 × 5 filter obtained the highest sensitivity (78.9%) and accuracy (77.5%) value. Negative predictive value was the highest (82.9%) for S9 filter. The McNemar test showed no statistically significant differences between images with and without CBCT filters (p > 0.05).

CONCLUSIONS

Although no statistical differences was observed in the diagnosis of root fractures when using filters, these filters seem to improve diagnostic capacity for longitudinal root fractures. Further in vitro studies with endodontic-treated teeth and research in vivo should be considered.