Comparative Evaluation of Extrusion of Apical Debris in Primary Maxillary Anterior Teeth Using Two Different Rotary Systems and Hand Files: An In Vitro Study.

Successful outcome of pulp therapy depends on good chemomechanical preparation of the canals. This is completed with the help of various upcoming rotary and hand files. However, during this preparation, there might be an apical extrusion of the debris which may result in postoperative complications. The aim of this study was to evaluate and compare the number of debris apically extruded during canal preparation using two different pediatric rotary file systems and conventional hand file systems in primary teeth. 60 primary maxillary central incisors that were extracted due to trauma or untreated dental caries with no signs of resorption were taken. Canal preparation was executed using three different file systems: Group A: Group A hand K file system, Group B Kedo S Plus, Group C Kedo SG Blue. For each of these files using the Myers and Montgomery model, the pre- and post-weight of the eppendorf tube was assessed to quantify the number of apical debris. The maximum extrusion of apical debris was noticed with the Hand K-file system. The least debris was noticed in the Kedo S Plus file system. Statistical analysis revealed that there were highly significant differences in apical extrusion and debris when comparing hand files and rotary files and also between the two rotary files used. Apical debris collection is an unavoidable outcome of canal instrumentation. Among the file systems compared, rotary files had lesser extrusion when compared to hand files. Among the rotary files, Kedo S plus showed normal extrusion compared to SG Blue.

Shaping ability of novel nickel-titanium systems in printed primary molars.

BACKGROUND: Manual or mechanized instruments can be used for root canal preparation. Manual instrumentation using K-files is widely used in primary teeth, but there are many limitations. Mechanized root canal preparation can lead to easy access to all canals, decrease instrumentation time, and result in more funnel-shaped root canals, resulting in a more predictable uniform paste fill. AIM: This study aimed to evaluate the shaping ability and instrumentation time of VDW.ROTATE™ and EdgeTaper Platinum™ during the preparation of resin-printed primary molars. Hand K-files were used as a reference for comparison. DESIGN: Sixty-six resin-based maxillary second primary molars, obtained from extracted tooth cone-beam computed tomography (CBCT) image and printed on a three-dimensional printer, were divided into three groups: VDW.ROTATE™, EdgeTaper Platinum™, and K-files. The specimens were scanned using CBCT imaging before and after root canal preparation. Images were registered using a dedicated software, and changes (Δ) in the canal area, volume, and untouched canal surface were calculated. Instrumentation time was evaluated. Data were statistically analyzed using the SPSS program. RESULTS: There was no significant difference among the tested file systems for Δ canal volume and area (p > .05). VDW.ROTATE™, however, showed significantly lower untouched canal surface area than other systems in all roots (p < .001). The VDW.ROTATE™ was found to be significantly faster (6.47 ± 0.39 min) than EdgeTaper Platinum™ (7.71 ± 0.73 min) and K-files (8.22 ± 0.72 min), (p < .05). CONCLUSIONS: The shaping ability and the instrumentation time were directly influenced by the root canal instrumentation system used during the preparation of resin-printed primary molars, with VDW.ROTATE™ being the faster system and associated with the lower amount of untouched canal surface area.

Shaping Ability of Reciprocating and Rotary Systems After Root Canal Retreatment: a CBCT Study

Abstract The purpose of this in vitro study was to evaluate the shaping ability of reciprocating and continuous rotary systems after root canal retreatment. After preparation and root canal filling, mesial canals of 54 mandibular molars were distributed into 3 groups (n=18), according to the filling material removal and re-instrumentation protocols: WOG group - WaveOne Gold system; PTN group - ProTaper Next system; and PTU group - ProTaper Universal system. Cone-beam computed tomographic (CBCT) images acquisition of the mesial root canals was performed at different moments: (1) before instrumentation (unprepared root canals), (2) after preparation and filling, (3) after filling material removal and (4) re-instrumentation. The apical transportation (AT), centering ability (CA) and change in root canal diameter were assessed by CBCT analysis. The remaining filling material quantification was performed by radiographic examination. The statistical analyses were performed using the 3-way ANOVA, Tukey-Kramer, Kruskal-Wallis and Dunn multiple Comparison tests (p<0.05). The tested instruments did not show full CA (=1.0). PTN group had greater AT at the 5th mm in comparison with the WOG group (p<0.05). After re-instrumentation, WOG group had greater root canal diameter change at the 1st and 5th mm than PTN and PTU groups (p<0.05). There was no significant difference among groups when comparing the amount of remaining filling material after re-instrumentation (p>0.05). The tested systems provided minimal alteration in root canal morphology at the apical portion after root canal retreatment. However, WOG promoted greater change in root canal diameter.

Resumo O objetivo deste estudo in vitro foi avaliar a capacidade de modelagem de sistemas rotatórios e reciprocantes após o retratamento do canal radicular. Após o preparo e obturação do canal radicular, os canais mesiais de 54 molares inferiores foram distribuídos em 3 grupos, de acordo com os protocolos de remoção do material obturador e re-instrumentação: (n=18): grupo WOG - sistema WaveOne Gold; Grupo PTN - sistema ProTaper Next; e grupo PTU - sistema ProTaper Universal. A análise das imagens de tomografia computadorizada de feixe cônico foi realizada em diferentes momentos: (1) antes da instrumentação (canais radiculares não preparados), (2) após o preparo e obturação, (3) após a remoção do material obturador e (4) re-instrumentação. O transporte apical (TA), a capacidade de centralização (CC) e a mudança no diâmetro do canal radicular foram avaliados por análise tomográfica. A quantificação do restante do material obturador foi realizada por exame radiográfico. As análises estatísticas foram realizadas utilizando os testes de ANOVA de 3 fatores, Tukey-Kramer, Kruskal-Wallis e Comparações Múltiplas de Dunn (p<0,05). Os instrumentos não apresentaram CC perfeita (=1,0). PTN apresentou maior TA no 5º mm em comparação ao grupo WOG (p<0,05). Após a re-instrumentação, o grupo WOG apresentou maior aumento no diâmetro do canal radicular no 1° e 5° mm do que os grupos PTN e PTU. Não houve diferença significativa entre os grupos em relação à remoção do material obturador (p>0,05). Os sistemas testados proporcionaram alteração mínima na morfologia do canal radicular na porção apical após o retratamento do canal radicular. No entanto, WOG promoveu maior alteração no diâmetro do canal radicular.

Effect of mode of rotation on apical extrusion of debris with four different single-file endodontic instrumentation systems: Systematic review and meta-analysis.

This systematic review and meta-analysis evaluated whether single-file endodontic instrumentation systems with the reciprocating type of motion are responsible for more debris extrusion than single-file endodontic instrumentation systems with the full rotational type of motion. Electronic and manual searches were performed following the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analysis - PRISMA. We included studies comparing rotary (Neoniti and/ OneShape) versus reciprocating (WaveOne and/ Reciproc) systems. We evaluated the quality of studies and performed statistical analysis using R-Project software. Eight studies of high quality were included to perform the meta-analysis. Subgroup analysis was also done. The overall risk of bias was too low. In conclusion, single-file reciprocating systems tend to generate more extrusion of debris than single-file rotary systems.

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 periradicular dentin and the enlargement of the apical canal of mandibular molars with TruNatomy (Dentsply Sirona, Ballaigues, Switzerland) and ProTaper Gold (Dentsply Sirona) instruments. METHODS: Twenty mandibular molars were scanned in a micro-computed tomographic 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, whereas in the TruNatomy group, mesial and distal canals were enlarged up to the prime (26/.04v) and medium (36/.03v) instruments, respectively. After a new scan, the surface area, volume, unprepared areas, transportation, percentage of dentin removal, and dentin thickness parameters were calculated. Data were compared between groups using the Mann-Whitney test, the Student t test, and the nonmetric multidimensional scaling test with alpha set at 5%. RESULTS: No difference was found between groups regarding unprepared canal areas and the reduction of dentin thickness (P > .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 < .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 the percentage of dentin removal at the coronal third but without clinically significant errors.

Root canal instrumentation efficacy of non-fused and fused primary molar roots: a micro-computed tomography study.

PURPOSE: Pulpectomy may be indicated in restorable primary teeth exhibiting irreversible pulpitis or pulpal necrosis. The purpose of this study was to compare the cleaning and shaping efficacy of NiTi systems (Reciproc® Blue and MTwo®) with manual stainless-steel instrumentation in primary molars using micro-CT analysis. METHODS: Fifty-seven maxillary second primary molars were scanned using micro-CT. Teeth with three divergent roots were divided randomly (n = 15) according to instrument type (K file, MTwo®, and Reciproc® Blue). Teeth with root fusion were instrumented manually as a separate group (n = 12). Pre- and post-instrumentation micro-CT images were superimposed, and the instrumentation area (IA) and procedural complications were recorded. RESULTS: No statistically significant differences in IA between file systems was observed in the non-fused teeth. The mean IA of fused roots was significantly lower than in the non-fused distobuccal (p = 0.003) and palatal (p < 0.001) roots. The root segment had a significant effect on IA (p < 0.001) and the highest mean IA was observed in the apical third. Manual instrumentation had fewer procedural complications compared with rotary systems. CONCLUSION: No differences were determined in the cleaning and shaping effectiveness of all systems in non-fused teeth. Uninstrumented areas (> 60%) occurred in both non-fused and fused primary teeth with fewer procedural complications observed after manual instrumentation.

Sealer penetration: effect of separated file's cross-section, taper and motion characteristics.

OBJECTIVES: The separated root canal instruments may affect the quality of root canal filling, hence the success of endodontic treatment. The aim of this study was to evaluate the effects of separated file fragments of nickel-titanium rotary systems with different cross-section, taper and motion characteristics on the apical sealer penetration in oval-shaped root canals via confocal laser scanning microscope (CLSM). MATERIALS AND METHODS: Distal roots of 60 mandibular molars with oval-shaped root canals were randomly divided into 4 groups as follows: group 1, FlexMaster Nickel Titanium Rotary File System (NTRFS) (separated instrument: 30/.06); group 2, ProTaper Next NTRFS (X3); group 3, ProTaper Universal NTRFS (F3); group 4, Revo-S NTRFS (AS30/.06). Root canals were filled with gutta-percha and AH plus labelled with 0.1% rhodamine B using a warm vertical compaction technique. Each specimen was horizontally sectioned at 1st, 3rd and 5th mm from apical foramen. Amount of maximum and average penetration depths, penetration percentage and sealer penetrated area were measured and analysed with one-way repeated measures of ANOVA and the Bonferroni post hoc tests. p < 0.05 was considered significant. RESULTS: The penetration depth, percentage and penetrated area of the sealer increased from apical to coronal in all systems. The maximum and average penetration depths and penetration areas were higher in FlexMaster and Revo-S groups at the 3rd mm (p < 0.05). At the 5th mm, the Revo-S group had a higher penetration percentage, when compared with ProTaper Next and ProTaper Universal groups (p < 0.05). CONCLUSIONS: In the 1st mm, separated fragments of any system did not allow the penetration of the sealer, while it was observed that the files with constant taper showed more positive results in terms of sealer penetration at apical 3rd and 5th mm. CLINICAL RELEVANCE: In the presence of a separated file, the taper of the file might significantly affect the amount of penetrated sealer into the dentinal tubules as compared with the cross-section and motion characteristics of the file.

Safety of large preparation with different instruments in the buccal canals of maxillary molars.

This study aimed to evaluate the influence of large apical preparations with Reciproc (REC), Hyflex CM (HCM) and Twisted File Adaptive (TFA) systems using micro-computed tomography (MCT). Ninety mesiobuccal (MB) and distobuccal (DB) root canals of maxillary molars (n = 45) were scanned using MCT before and after the shaping procedures. The root canals (n = 15) were prepared until REC 40.06, HCM 40.04 and TFA 35.04. The root canal transportation (RCT), centring ability (CA), change in volume of the root canal and at different levels (VC), remaining dentine thickness (RDT), removal of dentine wall (RDW) and working time (WT) were evaluated. Data were analysed using the Kruskal-Wallis and Dunn tests, and the one-way ANOVA and Tukey tests with a level of significance set at 5%. No significant difference among the instruments was found regarding the RCT, CA, RDT, RDW and WT (P > 0.05), in larger apical preparations in curved MB and straight DB canals of maxillary molars.

Evaluation of Apical Transportation by Three Rotary Systems in Extracted Teeth with Curved Canals / Evaluación de la transportación apical con tres sistemas rotatorios en dientes extraídos con conductos curvos

Abstract The aim of this study was to compare the apical transportation in extracted teeth using three different rotary nickel-titanium systems (Mtwo, Hyflex CM, and Typhoon). Sixty extracted first molars were randomly divided into three groups (n=20 in each group) with similar root canal curvatures (25-52 degrees). All root canals were prepared to size 30 using a crown-down preparation technique for each rotary system. Loss of working length and apical transportation were determined by X-ray evaluation. Comparisons between the groups were performed using one-way analysis of variance (ANOVA) or Kruskal-Wallis tests, and the post hoc analyses employed were Dunn´s or Tukey´s multiple comparison tests. No significant differences were detected between the different rotary systems in the loss of working length and apical transportation. This in vitro study showed that the use of these three rotary systems are safe and useful for instrumentation in curved canals; however, further in vivo research is essential to compare the effectiveness and safety of these systems for use in curved canals.

Resumen El objetivo del presente estudio fue comparar la transportación apical en dientes extraídos utilizando tres sistemas rotatorios de níquel-titanio (Mtwo, Hyflex CM y Typhoon). Sesenta primeros molares extraídos se dividieron aleatoriamente en tres grupos (n=20 en cada grupo) con curvaturas del conducto radicular similares (25-52 grados). Todos los conductos radiculares se prepararon usando una técnica corono apical para cada sistema rotatorio. La pérdida de la longitud de trabajo y la transportación apical se determinaron mediante evaluación radiográfica. Las comparaciones entre los grupos se realizaron utilizando análisis de varianza de una vía (ANOVA) o Kruskal-Wallis, y los análisis post hoc empleados fueron las pruebas de comparación múltiple de Dunn o Tukey. No se detectaron diferencias significativas entre los diferentes sistemas rotatorios en la pérdida de la longitud de trabajo y transportación apical. Este estudio demostró que el uso de estos tres sistemas es seguro y útil para su instrumentación en conductos curvos; sin embargo, investigación in vivo es necesaria para comparar la efectividad y seguridad de estos sistemas para su uso en conductos curvos.

A micro-computed tomographic assessment of root canal preparation with conventional and different rotary files in primary teeth and young permanent teeth.

BACKGROUND: Root canals of primary teeth are commonly prepared with endodontic files that are originally manufactured for permanent teeth. AIM: This micro-computed tomography (micro-CT) study evaluated and compared the changes in root canal morphology after preparation with different conventional and rotary files in primary teeth and young permanent teeth. DESIGN: Seventy-two extracted primary and permanent molars were selected and randomly assigned to three subgroups according to the file systems used (n = 12/each). After pre-scanning of teeth with micro-CT, root canals were prepared with One Shape and Revo-S rotary systems and conventional endodontic files. After rescanning procedure, changes in canal volume, surface area, uninstrumented surface area, and apical transportation were evaluated. Mann-Whitney U test, Kruskal-Wallis test, and Conover's multiple comparison test were used for statistical analysis (P = .05). RESULTS: Instrumentation with rotary files resulted in significantly greater volume and surface area of root canals and less uninstrumented areas (P < .001) than with manual files (P < .001). Primary molars showed significantly less apical transportation than permanent teeth (P < .001). CONCLUSIONS: Preparation of canals with rotary files could be a viable alternative to conventional files in primary teeth. Regardless of the file system used, uninstrumented areas still exist in both primary teeth and permanent teeth.

The Effect of Reciprocating and Rotary Systems on Postoperative Endodontic Pain: A Systematic Review and Meta-analysis.

Introduction: The objective of this study was to evaluate the influence of the instrumentation kinematics on endodontic postoperative pain. Methods and Materials: PubMed, Scopus, Web of Science, Lilacs, Cochrane Library and the System for Information on Gray Literature in Europe were searched electronically without time or language limitations up to June 2020. Subsequently, data extraction, quality assessment and meta-analysis were conducted. The meta-analysis was performed using random-effects inverse-variance methods, and heterogeneity was tested using the I 2 index (P<0.05). Results: A total of 318 articles were successfully identified in the search. Sixteen studies were used in qualitative synthesis and fourteen used for quantitative synthesis. Meta-analysis showed that patients treated with reciprocating system had lower risk of pain 48 h after endodontic treatment (Risk ratio [RR]=1.04, 95% Confidence interval [CI]=1.01-1.06, P=0.003) (I2=0%), but the mean postoperative pain for the reciprocating system was greater 24 h post endodontic treatment (Standardized mean difference [SMD]=0.25, 95% CI=0.06 to 0.44, P=0.01) (I2=43%). Other time points presented similar rates of postoperative pain (P>0.05). The certainty of evidence ranges from very low to high. Conclusions: The rate of postoperative endodontic pain was low, and reciprocating systems evoked more pain within the 24 h interval. Overall, the incidence and level of postoperative pain did not vary between reciprocating and rotary systems. There is no consensus if there is a relationship between the kinematics (rotary and reciprocating) and the incidence of postoperative pain.

Root canal preparation using S5, Mtwo, and ProTaper Universal nickel-titanium systems: a comparative ex-vivo study.

OBJECTIVES: To examine various parameters of root canal preparation using three rotary nickel-titanium systems (S5, Mtwo, and ProTaper Universal [PTU]). METHOD AND MATERIALS: One hundred and twenty curved root canals were prepared to size 30. The following parameters were evaluated: straightening, changes of root canal cross-section, safety issues, cleanliness of canal walls, and working time. Statistical analysis was performed with the Kruskal-Wallis test, Wilcoxon-Mann-Whitney test, and analysis of variance (P < .050). RESULTS: All three systems maintained the curvature well with no significant difference between the groups. With regard to the cross-section, no significant differences for any of the root canal thirds (coronal, P = .589; medial, P = .898; apical, P = .474) were found. Preparation with S5 resulted in two, with Mtwo in one, and with PTU in three procedural incidents. Debris scores 1 and 2 were found in 56% (S5), 46% (Mtwo), and 60% (PTU) of the specimens, respectively. Smear layer scores 1 and 2 were found in 85% (S5), 73% (Mtwo), and 78% (PTU). Results for removal of debris and smear layer were not significantly different between the three groups. Mean working time was significantly shorter for Mtwo (293 seconds) than for S5 (329 seconds) (P = .001) or PTU (369 seconds) (P = .001). CONCLUSION: All three systems respected the original root canal curvature well and were safe to use. None of the three systems was able to prepare the entire circumference of the root canals, and to remove debris and smear layer completely.

Effect of Root Canal Preparation Techniques on Crack Formation in Root Dentin.

INTRODUCTION: The aim of this study was to assess the frequency of root crack formation caused by the use of manual instrumentation, 2 rotary systems, and 1 reciprocating system using light-emitting diode transillumination. METHODS: One hundred fifty mandibular premolars were randomly divided into 5 groups (n = 30): control 1, no intervention; control 2, instrumented with hand files; group 3, instrumented with ProTaper Universal rotary files (Dentsply Maillefer, Ballaigues, Switzerland); group 4, instrumented with OneShape rotary files (Micro-Mega, Besancon, France); and group 5: instrumented with the WaveOne reciprocal system (Dentsply Maillefer, Ballaigues, Switzerland). After root canal preparations, the roots were sectioned at 3, 6, and 9 mm from the apex with water irrigation. The slices were inspected under a stereomicroscope with light-emitting diode transillumination from the buccal, lingual, mesial, and distal directions at ×40 magnification to determine the presence/absence of cracks (dentinal defects). The chi-square test was used to analyze the data. RESULTS: There was a significant difference among the groups in crack frequency (P < .05). The 2 single systems had significantly higher cracks than the other 3 groups. At 3 mm from the apex, there were significantly more cracks in groups 4 and 5 than in groups 1, 2, and 3 (P < .05). At 6 mm from the apex, no significant difference was noted (P > .05). At 9 mm from the apex, the frequency of cracks in group 3 was significantly higher (P < .05). CONCLUSIONS: According to the results, using rotary instrumentation can result in some dentinal defects, and single-file systems, regardless of motion type, can cause significantly higher crack formation in the apical third of root canals.

Assessment of apical transportation caused by nickel-titanium rotary systems with full rotation and reciprocating movements using extracted teeth and resin blocks with simulated root canals: A comparative study.

OBJECTIVES: : We compared apical transportation in the WaveOne and ProTaper Next systems, which are rotary nickel-titanium systems with reciprocating and continuous rotation movements, respectively, using manual measurements obtained from resin blocks with simulated root canals and double digital radiographs of extracted teeth. MATERIALS AND METHODS: : We used 30 resin blocks with simulated root canals and 30 extracted teeth for this study. The same endodontist performed root canal shaping using the WaveOne or ProTaper Next system. We assessed apical transportation by measuring the amounts (in mm) of material lost 1 mm from the apical foramen in the resin blocks and by using double digital radiography for the extracted teeth. Significant differences between groups were assessed using t-tests. P < 0.05 was considered statistically significant. RESULTS: : The amount of apical transportation differed significantly between the two systems when resin blocks were used for assessment (P < 0.05), but there were no significant differences when extracted teeth were used (P < 0.05). CONCLUSIONS: In the current study, there was no significant difference in apical transportation between natural teeth prepared using WaveOne and those prepared using ProTaper Next. However, significant differences were observed between the two systems with resin blocks. These findings indicate that the use of resin blocks is not an accurate method for apical transportation evaluation.

Computed tomography evaluation of root canal transportation using ProTaper, Race and Sendoline rotary systems: an ex vivo study.

BACKGROUND: This ex vivo study aimed to compare transportation of the mesiobuccal root canal of mandibular first molars instrumented with ProTaper, Race and Sendoline rotary systems using cone beam computed tomography (CBCT). MATERIALS AND METHODS: Forty-five mesiobuccal canals of mandibular first molars were randomly divided into three groups of 15. Root canals in each group were instrumented with the ProTaper, Race or Sendoline rotary system according to the manufacturers' instructions. Root canal preparations were performed by one operator, while root canal wall measurements were made by another operator blinded to the group allocation of teeth. The pre- and post-chemomechanical preparation CBCT scans were obtained and evaluated at 3, 6 and 9 mm levels from the apex. The amount of root canal transportation at these levels was calculated. Data were analyzed using SPSS version 17 via Mann-Whitney and Kruskal-Wallis tests. P<0.05 was considered significant. RESULTS: No significant difference was noted in canal transportation among the groups (P>0.05), but ProTaper showed the least and Sendoline caused the most canal transportation in the coronal third. CONCLUSION: ProTaper, Race and Sendoline rotary systems are not significantly different in terms of canal transportation. Although all rotary files cause root canal transportation, ProTaper and Race showed the least amount of canal transportation in the coronal and apical thirds, respectively.

Root canal preparation in 3-rooted maxillary premolars through hand, rotary, and reciprocating techniques: a microcomputed tomography evaluation.

Endodontic management of 3-rooted maxillary premolars is a challenge due to their complex anatomy and narrow root canal walls. This study aimed to evaluate, by microcomputed tomography (µCT), the apical enlargement and centering ability promoted by hand, rotary, and reciprocating instrumentation in 3-rooted maxillary premolars. Eighteen teeth were divided into 3 groups (n = 6) according to the preparation technique: crown-down hand, rotary, and reciprocating instrumentation. Instruments with similar apical diameters were used (25 and 40 mm for buccal and palatal canals, respectively). Centering ability and canal enlargement were evaluated through the comparison of µCT images obtained before and after instrumentation. Distances of 0, 2, 4, and 6 mm from the apical stop were considered. Differences between canal areas before and after instrumentation were calculated. In addition, distances between the original canal center and the prepared canal center at the apical stop were measured in both the mesiodistal and buccopalatal directions. Significant differences in enlargement areas and centering ability among the techniques were determined using 2-way analysis of variance and Tukey post hoc test (P > 0.05). Root canal enlargement was similar for all techniques. Excessive enlargement was observed in only a few specimens, and root perforation did not occur. Some specimens presented untreated canal areas. In mesiobuccal and distobuccal roots, reciprocating instrumentation promoted more centered preparations than hand instrumentation when measured in the mesiodistal direction (P > 0.05). There were no other statistically significant differences. The results established that hand, rotary, and reciprocating techniques presented similar safety margins for instrumentation of the apical third of 3-rooted maxillary premolars. Reciprocating instrumentation presented some advantages over hand preparation regarding centering ability.

The influence of new heat­treated NiTi alloy on shaping ability and apical transportation of maxillary molars. The evaluation of the larger apical preparation on mesiobuccal and distobuccal canals of maxillary molars: a micro-computed study / Influência de diferentes tratamentos na liga de Ni-Ti no preparo e transporte apical de molares superiores. Avaliação do efeito da variação do diâmetro do preparo apical de canais mesio-vestibulares e disto-vestibulares de molares superiores: análise por meio de microCT

The aim of this study was to evaluate canal transportation; centering ability; dentin thickness; change in volume, and time spent on shaping ability of maxillary molars prepared with mechanized NiTi file systems composed of a conventional NiTi alloy (Mtwo), a CM-Wire (Prodesign R and Hyflex CM) NiTi alloy, R-phase (Twisted File Adaptive) and an M-Wire (Reciproc) NiTi alloy]. With the purpose of understanding the role of new treated NiTi alloys in larger apical preparations, this type of preparation was evaluated in the mesiobuccal (MB) and distobuccal canal (DB) of maxillary molars, as well as, in the second mesiobuccal (MB2) canals in extracted maxillary first molars by means of micro-computed tomographic (micro- CT) imaging. For the second mesiobuccal canal (MB2) evaluation, thirty maxillary molars with Vertucci type IV canal configuration were selected and randomly divided into 3 groups (n = 10): Reciproc [REC; VDW, Munich, Germany], Prodesign R [PDR; Easy, Belo Horizonte, Brazil] and Mtwo [MO; VDW, Munich, Germany]. To assess the mesiobuccal and distobuccal canals, a total of 45 extracted maxillary molars were selected according to the following criteria: MB canals exhibiting curvatures according to the Weine classification in the 20-30 degree range; and DB canals presenting curvatures in the 0-5 degree range. These teeth were randomly assigned to three groups, Reciproc (REC) [40.06]; Hyflex CM (HF) [40.06] [Coltene, Cuyahoga Falls, OH, USA] and Twisted file Adaptive (TFA) [35.04]. After root canal preparation, all the teeth were scanned to evaluate parameters previously cited. In particular, the percentage of negotiability of the MB2 canal was evaluated. All parameters were statistically compared using the Kruskal-Wallis and Dunn's Multiple comparison tests within groups with a significance level of 5%. For MB2 canals, no statistically significant difference was observed among the three groups with regard to the values of canal transportation, centering ability, remaining dentin thickness in the coronal third, number of specimens with thickness under 0.5 mm in the danger zone, and apical volume (P>0.05). However, the entire volume of the canal in Group MO differed statistically from that of Group PDR (P<0.05), but Group REC did not differ statistically from Groups MO and PDR (P>0.05). Group PDR demanded more time to reach WL than use of the MO and REC systems. For MB and DB canals, the trend of canal transportation was towards inner curvature in apical third, while in the coronal third it was towards the outer curve. There was no difference in apical transportation values in the first apical millimeters for both canals. In MB canal, at 3 and 4 mm, the Reciproc transportation value was significantly lower than that of Hyflex CM(P<0.05). In the DB canal, at 2 and 4 mm, Reciproc showed substantially higher values than Group TFA (P<0.05). There was no statistically significant difference between the two canals among the three systems for centering ability in the apical third and the remaining dentin thickness (RDT). For DB canal, there was no significant difference in shaping time, but in the MB canal, Group TFA was swifter than Reciproc and Hyflex CM. The initial changes in volume (apical/entire) after canal preparation was statistically significant within groups in MB and DB canals for percentage and volume of dentin removed. TFA had the lowest values for the apical and entire volumes of dentin removed in both canals compared with Reciproc and Hyflex CM (P<0.05). TFA had the lowest percentage of dentin removed from the entire MB canal, and from the apical and entire volume of DB canal. For negotiating and shaping the MB2 canal, the three file systems had similar performance. However, the REC system reached the full working length faster than PDR. The MO and REC systems removed more dentin in the inner furcation area when compared with PDR. For MB and BD canals, the heat treated NiTi alloy systems used for larger apical preparation evenly maintained the morphology of the MB and DB canals of maxillary molars. In shaping procedures, the larger apical preparation produced slight canal transportation without evidence of significant preparation errors. However, these variations may not be feasible of clinical significance. Use of TFA was swifter for preparing the MB canal and produced fewer changes in volume parameters. The TFA system was able to preserve the original canal anatomy with less canal transportation than the Reciproc and Hyflex CM systems.(AU)

O objetivo deste estudo foi avaliar o transporte do canal, a centralização do canal, a espessura dentinária, a alteração volumétrica e o tempo de trabalho de diferentes sistemas mecanizados de níquel-titânio compostos por ligas convencional (Mtwo) e tratados termicamente (CMWire (Prodesign R e Hyflex CM), M-Wire (Reciproc) e fase-R (Twisted file adaptive) em preparos de canais em molares superiores. O papel dos novos instrumentos de níquel titânio tratados termicamente em preparos apicais mais amplos de canais mésio-vestibulares e distovestibulares dos molares superiores foi avaliado, como também o preparo do canal mésiopalatino (CMP), por meio da microtomografia computadorizada (µ-CT). No estudo do canal mésio-palatino, 30 primeiros molares superiores com configuração tipo IV de Vertucci foram selecionados e divididos em 3 grupos (n = 10): Reciproc [REC; VDW, Munich, Germany], Prodesign R [PDR; Easy, Belo Horizonte, Brazil] and Mtwo [MO; VDW, Munich, Germany]. No estudo dos canais mésio-vestibulares e disto-vestibulares, o total de 45 molares superiores foram selecionados com angulação da raiz mésio vestibular de 20 a 30 graus e apresentando a raiz disto-vestibular com angulação de 0 a 5 graus, de acordo com a classificação de Weine. Os dentes foram aleatoriamente distribuídos em 3 grupos (n=15): Reciproc (40.06) [REC, VDW, Munich, Germany]; Hyflex CM (40.06) [HF, Coltene, Cuyahoga Falls, OH, USA]; e Twisted file Adaptive (35.04) [TFA, SybronEndo, Orange, CA]. Após o preparo dos canais mésio-palatino, mésio-vestibular, e disto-vestibular, todos os dentes foram escaneados para avaliação dos parâmetros previamente citados. Especificamente, na avaliação do canal mésiopalatino, foi avaliada a porcentagem de canais que alcançaram patência. Todos os parâmetros foram avaliados estatisticamente pelo teste de Kruskal-Wallis e pelo teste Dunn's de múltipla comparação entre grupos, com nível de significância de 5%. O canal mésio-palatino não apresentou diferença estatisticamente significante em relação ao transporte, centralização, remanescente de dentina no terço cervical, quanto ao número de espécime abaixo de 0,5 mm de espessura na zona de perigo e no volume apical (P>0.05). O volume total do canal no grupo MO diferenciou-se do volume total do grupo PDR (P<0.05), enquanto essa diferença não foi evidenciada entre os grupos REC comparado aos grupos MO e PDR (P>0.05). O grupo PDR demandou maior tempo para atingir o comprimento de trabalho comparado aos sistemas MO e REC. Na análise dos canais MV e DV dos molares superiores, o transporte coronal direcionou-se para o interior da curvatura do canal, enquanto no terço apical o transporte direcionou-se para o lado externo da curvatura. O transporte apical no primeiro milímetro de ambos os canais (MV e DV) foi equivalente entre os grupos (P>0.05). O canal MV apresentou nos níveis 3 e 4 mm transporte do grupo Reciproc significantemente menor do que no grupo Hyflex CM (P<0.05). Em relação ao transporte apical, no canal DV, nos milímetros 2 e 4 apicais do grupo Reciproc transportou significantemente mais comparado ao grupo TFA (P<0.05). Contudo, a centralização apical de ambos os canais e a quantidade de remanescente dentinário apical não se diferiram estatisticamente (P<0.05). O preparo do canal MV foi mais rápido com o sistema TFA comparado ao Reciproc e do Hyflex CM (P<0.05), enquanto no canal DV não foi evidenciado diferenças em relação ao tempo de preparo (P>0.05). A porcentagem e o volume de dentina removida em todo o canal e na região apical, após o preparo do canal apresentou diferenças significantes entre os grupos. O grupo TFA teve as menores porcentagens e valores de dentina removida no volume total do canal e no volume apical, em ambos os canais, comparado com os sistemas Reciproc e Hyflex CM (P<0.05). No canal MP, os três sistemas avaliados prepararam e patenciaram semelhantemente os canais MP. Contudo, o sistema Reciproc foi mais rápido para alcançar o comprimento de trabalho do que o sistema Prodesign R. Os grupos Mtwo e Reciproc removeram mais dentina na região voltada para o interior da furca quando comparado ao Prodesign R. Os sistemas compostos por ligas tratadas termicamente em preparos com maior ampliação apical mantiveram a morfologia dos canais MV e DV. Os sistemas promoveram discretos transportes, sem evidência de erros no preparo. Contudo, essas variações não são passíveis de significância clínica. O grupo do TFA foi mais rápido e promoveu menores alterações nos parâmetros volumétricos. O grupo do TFA foi capaz de preservar a anatomia original do canal com menor grau de transporte comparado ao Reciproc e Hyflex CM.(AU)

In vitro comparison of gutta-percha-filled area percentages in root canals instrumented and obturated with different techniques.

PURPOSE: To evaluate the efficacy of different obturation techniques in root canals instrumented either by hand or rotary instruments with regard to the percentage of gutta- percha-filled area (PGFA). MATERIALS AND METHODS: One hundred and sixty extracted mandibular premolars with single, straight root canals were studied. Root canals were prepared to an apical size of 30 by hand with a modified crown-down technique or the ProTaper and HEROShaper systems. Teeth were divided into eight groups (n=20) according to the following instrumentation and obturation techniques: G1: Hand files+lateral condensation (LC), G2: Hand files+Thermafil, G3: ProTaper+LC, G4: ProTaper+single-cone, G5: ProTaper+ProTaper-Obturator, G6: HEROShaper+LC, G7: HEROShaper+single-cone, G8: HEROShaper+HEROfill. Horizontal sections were cut at 1, 3, 5, 7, 9, 11 and 13 mm from the apical foramen. A total of 1120 sections obtained were digitally photographed under a stereomicroscope set at 48X magnification. The cross-sectional area of the canal and the gutta-percha was measured by digital image analysis and the PGFA was calculated for each section. RESULTS: The mean of the PGFA in Thermafil (G2), ProTaper-Obturator (G5) and HEROfill (G8) groups was significantly higher than the other groups. In G3 and G4, PGFA showed no significant difference in the apical segments whereas PGFA was significantly higher at the middle and coronal segments in G3. In G6 and G7, PGFA showed no significant difference in the apical and middle segments whereas PGFA was significantly higher at the coronal segments in G6. CONCLUSION: The carrier-based gutta-percha obturation systems revealed significantly higher PGFA in comparison to single-cone and lateral condensation techniques.

The Effect of Foraminal Enlargement of Necrotic Teeth with a Continuous Rotary System on Postoperative Pain: A Randomized Controlled Trial.

INTRODUCTION: This single-blind, randomized controlled trial aimed to evaluate whether foraminal enlargement (FE) with a continuous rotary system during endodontic treatment causes more postoperative pain than nonforaminal enlargement (NFE). METHODS: Seventy qualified patients were randomized into 1 of 2 groups in a 1:1 ratio using a series of random numbers: the FE group and the NFE group. The patients were followed up for 7 days to evaluate between-group differences in the outcome measures. The study participants were selected from among patients who had necrosis and apical periodontitis in the maxillary or mandibular molar teeth. The primary outcome was to assess postoperative pain severity, and the secondary outcome was to evaluate analgesic consumption during the follow-up period. Pain severity was evaluated for the first 7 days using a visual analog scale (VAS). The VAS consisted of a 100-mm line. Pain severity was assessed as no pain (0-4 mm), mild pain (5-44 mm), moderate pain (45-74 mm), and severe pain (75-100 mm). The quality of life of patients during the follow-up period was assessed using a quality of life scale. The Student t test was used to identify statistically significant differences between the study groups (P < .05). RESULTS: A significant difference was noted in postoperative pain in the first 2 days; the FE group experienced more pain than the conventional NFE group (P < .05). In the FE group, 12 and 11 patients (34% and 31%) had severe postoperative pain (VAS score, >74 mm) on the first day and second day, respectively. VAS pain scores between the groups were not different (P > .05) on other days. No significant difference was found in analgesic consumption between the groups (P > .05). CONCLUSIONS: On the basis of the VAS results, this randomized controlled trial indicates that FE causes more pain on the first 2 days after an endodontic treatment.

Efficacy of CM-Wire, M-Wire, and Nickel-Titanium Instruments for Removing Filling Material from Curved Root Canals: A Micro-Computed Tomography Study.

INTRODUCTION: The aim of this ex vivo study was to evaluate the removal of filling material after using CM-wire, M-wire, and nickel-titanium instruments in both reciprocating and rotary motions in curved canals. METHODS: Thirty maxillary lateral incisors were divided into 9 groups according to retreatment procedures: Reciproc R25 followed by Mtwo 40/.04 and ProDesign Logic 50/.01 files; ProDesign R 25/.06 followed by ProDesign Logic 40/.05 and ProDesign Logic 50/.01 files; and Gates-Glidden drills, Hedström files, and K-files up to apical size 30 followed by K-file 40 and K-file 50 up to the working length. Micro-computed tomography scans were performed before and after each reinstrumentation procedure to evaluate root canal filling removal. Statistical analysis was performed with Kruskal-Wallis, Friedman, and Wilcoxon tests (P < .05). RESULTS: No significant differences in filling material removal were found in the 3 groups of teeth. The use of Mtwo and ProDesign Logic 40/.05 rotary files did not enhance filling material removal after the use of reciprocating files. The use of ProDesign Logic 50/.01 files significantly reduced the amount of filling material at the apical levels compared with the use of reciprocating files. CONCLUSIONS: Association of reciprocating and rotary files was capable of removing a large amount of filling material in the retreatment of curved canals, irrespective of the type of alloy of the instruments. The use of a ProDesign Logic 50/.01 file for apical preparation significantly reduced the amount of remnant material in the apical portion when compared with reciprocating instruments.