Apical transportation using Mtwo or Reciproc retreatment systems in severely curved canals: a micro-computed tomographic study.

OBJECTIVE: To assess apical root canal transportation using Mtwo or Reciproc during retreatment of severely curved canals, using a multi-analytical approach. METHODS: Forty mesial canals from mandibular molars (Vertucci type IV) were evaluated before and after endodontic retreatment to compare apical transportation with Mtwo retreatment or Reciproc. The systems were used on the same root but alternating the mesial canals. The analyses were performed by micro-computed tomography. Four evaluations were performed: (a) longitudinal transportation, (b) horizontal transportation, (c) variation in the angle of curvature of the canal, and (d) canal-root width ratio. Horizontal transportation and canal-root width ratio were evaluated in 1-, 3-, and 5-mm levels. RESULTS: Longitudinal transportation occurred in all samples, with a mean of 0.13 mm for Mtwo and 0.17 mm for Reciproc. Horizontal transportation increased as distant from the apex was the evaluated level, in mean. However, the transport was not observed in all samples. The mean angle of curvature was 4.16 for Mtwo and 3.03 for Reciproc. Canal-root width decreased as distant from the apex was the evaluated level. No significant differences were observed considering all tested variables, independently of the retreatment system or evaluated level (p > 0.05). CONCLUSION: Mtwo retreatment and Reciproc presented similar apical transportation (horizontal or vertical). CLINICAL RELEVANCE: Both Mtwo retreatment and Reciproc systems could be considered safe regarding apical transportation.

Deciduous Molars Complexity Anatomy Reveled by Computed Microtomography.

OBJECTIVE: The aim of this study was to analyze the internal morphology of deciduous molars through the use of computed microtomography in a sample from Rio de Janeiro. MATERIAL AND METHODS: Thirty maxillary and 30 mandibular deciduous molars (n = 60), divided in first and second primary molars, were scanned by computed microtomography. The teeth were evaluated for root number, root canals, Vertucci classification, root curvature, presence of lateral canals, furcation dentin thickness, structure model index (SMI), volume, and canal surface area. RESULTS: The results showed 100% of maxillary molars had three roots and Vertucci type I canal was more prevalent in this group. In the mandibular ones, type IV was more frequent in the mesial root and class I in the distal root and the cavo-interradicular canal occurred in 2 specimens. Dentin thickness in the furcation region measured 1.53 and 1.59 mm in the maxillary and mandibular, respectively. Volume and area parameters varied according to the evaluated canals and SMI demonstrated that all canals had a cylindrical shape. CONCLUSION: More detailed information about the internal anatomy of the primary molars has been described, which may help strategies in the preparation of these root canals.

Disinfection and Shaping of Vertucci Class II Root Canals after Preparation with Two Instrument Systems and Supplementary Ultrasonic Activation of Sodium Hypochlorite.

INTRODUCTION: This study compared disinfection and shaping after root canal preparation with either XP-endo Shaper or TruNatomy instrument systems, supplemented by ultrasonic activation of sodium hypochlorite (NaOCl) with either stainless-steel (SS) or nickel-titanium (NiTi) inserts. METHODS: Mesial roots from mandibular molars with Vertucci class II configuration were divided into 2 groups (n = 24) based on anatomically paired micro-computed tomography (micro-CT) analyses. Pre and postpreparation micro-CT scans were obtained to evaluate the shaping performance. The canals were contaminated with a mixed bacterial culture for 30 days and then subjected to preparation with either XP-endo Shaper or TruNatomy instruments using NaOCl irrigation. Supplementary ultrasonic activation of NaOCl was conducted using either an SS (TruNatomy group) or NiTi (XP-endo Shaper group) insert. Bacteriological samples were taken from the canals before preparation (S1), after preparation (S2), and after the supplementary approach (S3). Bacterial reduction was evaluated using a quantitative real-time polymerase chain reaction. RESULTS: Preparation with both instrument systems significantly reduced bacterial counts (P < .01). After preparation, 36% (TruNatomy) and 35% (XP-endo Shaper) were negative for bacteria. These values increased to 59% and 65% after ultrasonic activation with the SS and NiTi inserts, respectively. The quantitative data in S2 showed that XP-endo Shaper promoted a significantly higher bacterial reduction than TruNatomy (P < .05). No significant intragroup differences were observed after ultrasonic activation (P > .05), probably because the SS insert promoted a significantly higher S2-to-S3 reduction than the NiTi insert (P < .01). Micro-CT analysis revealed no significant differences in the unprepared areas between the groups (P > .05). CONCLUSIONS: The XP-endo Shaper caused a significantly higher bacterial reduction than TruNatomy in Vertucci class II canals. Better antibacterial results after ultrasonic activation were observed for the SS ultrasonic inserts than for the NiTi inserts.

Canal transportation using Mani GPR or HyFlex NT during the retreatment of curved root canals: A micro-computed tomographic study.

This study assessed the apical transportation using Mani GPR or HyFlex NT during the retreatment of curved root canals. Thirty-eight roots were analysed using micro-CT for the comparison of apical transportation produced by two retreatment systems. Longitudinal transportation, horizontal transportation, variation in the canal angle of curvature and variation in the canal/root width ratio were analysed. Longitudinal transportation was frequently observed, regardless of the system used. The canals retreated with Mani GPR showed a significantly higher horizontal transportation at 1 mm from the root apex (P < 0.01) and greater variation of the canal curvature angle (P < 0.01). The canal/root width ratio was similar between groups (P > 0.05). In conclusion, longitudinal transportation occurred more frequently in the mesial canal walls. Mani GPR showed greater horizontal transportation at 1 mm short of the apex, and higher variation of the canal curvature angle compared with HyFlex NT.

Matching the Dimensions of Currently Available Instruments with the Apical Diameters of Mandibular Molar Mesial Root Canals Obtained by Micro-computed Tomography.

INTRODUCTION: This micro-computed tomographic study investigated the original anatomic diameters of the apical portion of mandibular molar mesial canals and matched them to the dimensions of instruments that are currently available and commonly used for apical preparation. METHODS: One hundred eight mandibular molar mesial roots with Vertucci type IV configuration were scanned by micro-computed tomographic imaging, and the largest anatomic diameter of both mesial canals at 1, 2, 3, and 4 mm short of the apical foramen was measured. Canal diameters were compared with the dimensions of 10 endodontic instruments for simulation of preparation 1 mm short of the apical foramen. Accordingly, the instruments with a diameter larger than the largest canal diameter were regarded as having the potential to prepare 100% of the canal walls at each specific point or over the 4-mm apical segment. RESULTS: At 1 and 2 mm short of the apical foramen, a 45/.02 instrument had a larger diameter than the mesiobuccal canal diameter in 73% and 55% of the teeth, respectively. Corresponding figures for the mesiolingual canal were 65% and 55%. When the entire 4-mm apical segment was considered, a 40/.06 instrument had better results, being larger than the apical canal in about 20% of the specimens. Overall, 78% of the apical canals would not be completely prepared by any instrument. Based on the mean (median) anatomic diameters, the adequate instrument dimensions would be 40/.10 (40/.08) for mesiobuccal canals and 45/.08 (40/.09) for mesiolingual canals. CONCLUSIONS: The dimensions of the available instruments are not compatible with complete apical preparation in the majority of cases. The ideal instrument size/taper to include all the canal walls in apical preparation is too large and may not be safe for clinical use.

Dentinal Microcrack Development after Canal Preparation: A Longitudinal in Situ Micro-computed Tomography Study Using a Cadaver Model.

INTRODUCTION: The purpose of this study was to evaluate the development of dentinal microcracks after root canal preparation with Reciproc and ProTaper Universal systems using an in situ cadaver model by means of a micro-computed tomography (micro-CT) imaging system. METHODS: At autopsy, 8 maxillary bone blocks having at least the first and second premolar teeth (n = 16) were excised, scanned at a resolution of 13.18 µm, and randomly distributed into 2 groups (n = 8) according to the preparation protocol: Reciproc and ProTaper Universal systems. Root canals were prepared up to R25 and F2 instruments in the Reciproc and ProTaper Universal groups, respectively. After the preparation procedures, the specimens were scanned again, and the registered preoperative and postoperative cross-section images of the roots (n = 19,060) were screened to identify the presence of dentinal defects. RESULTS: In the Reciproc group, 9176 cross-section images were analyzed, and no crack was observed. In the ProTaper Universal group, 244 of 9884 cross-section slices (2.46%) had dentinal defects; however, all defects were already present in the corresponding preoperative images, indicating that no new microcrack was created after canal preparation. CONCLUSIONS: In situ root canal preparation of maxillary premolars with Reciproc and ProTaper Universal systems did not induce the formation of dentinal microcracks in a cadaver model as observed by micro-CT.

Disinfecting Effects of Rotary Instrumentation with Either 2.5% Sodium Hypochlorite or 2% Chlorhexidine as the Main Irrigant: A Randomized Clinical Study.

INTRODUCTION: This randomized clinical study compared the antibacterial effects of irrigation with either 2.5% sodium hypochlorite (NaOCl) or 2% chlorhexidine (CHX) during the preparation of infected root canals with rotary nickel-titanium instruments. METHODS: The root canals of 50 single-rooted teeth with apical periodontitis were prepared by using BioRaCe rotary instruments (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and irrigation with either 2.5% NaOCl (n = 25) or 2% CHX (n = 25). Samples were taken from the canal at baseline (S1) and after (S2) chemomechanical preparation. DNA was extracted from the clinical samples, and the reduction of the levels of total bacteria and streptococci was evaluated by means of a 16S ribosomal RNA gene-based quantitative polymerase chain reaction assay. RESULTS: All S1 samples were positive for the presence of bacteria. After chemomechanical preparation using either 2.5% NaOCl or 2% CHX, 44% and 40% of the root canals still had detectable bacteria, respectively. As for total bacterial counts, a mean number of 3.7 × 10(5) bacterial cell equivalents was present in S1 samples from the NaOCl group, with a substantial reduction in S2 to a mean of 5.49 × 10(2) cell equivalents (P < .001). In the CHX group, a mean bacterial load of 8.77 × 10(4) cell equivalents occurred in S1, with a significant reduction in S2 to a mean of 2.81 × 10(3) cells (P < .001). The differences in both the presence/absence and quantitative data were not statistically significant (P > .05). Both irrigation protocols were highly effective in reducing the levels of Streptococcus species (P < .001). CONCLUSIONS: No significant difference was observed for the clinical antibacterial effectiveness of rotary preparation using either 2.5% NaOCl or 2% CHX as the main irrigant.

Micro-Computed Tomography Analysis of the Root Canal Morphology of Palatal Roots of Maxillary First Molars.

INTRODUCTION: A thorough knowledge of root canal anatomy is critical for successful root canal treatments. This study evaluated the internal anatomy of the palatal roots of maxillary first molars with micro-computed tomography (microCT). METHODS: The palatal roots of extracted maxillary first molars (n = 169) were scanned with microCT to determine several anatomic parameters, including main canal classification, lateral canal occurrence and location, degree of curvature, main foramen position, apical constriction presence, diameters 1 and 2 mm from the apex and 1 mm from the foramen, minor dentin thickness in those regions, canal volume, surface area, and convexity. RESULTS: All canals were classified as Vertucci type I. The cross sections were oval in 61% of the canals. Lateral canals were found in 25% of the samples. The main foramen did not coincide with the root apex in 95% of the cases. Only 8% of the canals were classified as straight. Apical constriction was identified in 38% of the roots. The minor and major canal diameters and minor dentin thickness were decreased near the apex. The minor dentin thickness 1 mm from the foramen was 0.82 mm. The palatal canals exhibited a volume of 6.91 mm(3) and surface area of 55.31 mm(2) and were rod-shaped. CONCLUSIONS: The root canals of the palatal roots were classified as type I. However, some factors need to be considered during the treatment of these roots, including the frequent ocurrence of moderate/severe curvatures, oval-shaped cross-sections, and lateral canals, noncoincidence of the apical foramen with the root apex, and absence of apical constriction in most cases.

Host-Bacterial Interactions in Post-treatment Apical Periodontitis: A Metaproteome Analysis.

INTRODUCTION: This study evaluated the bacterial and human metaproteome of root apexes and the matched inflammatory lesions from teeth with post-treatment apical periodontitis. METHODS: Root apexes and matched inflammatory lesions from root canal-treated teeth with apical periodontitis were obtained during periradicular surgery. All root canal fillings were rated as adequate on the basis of radiographs and cone-beam computed tomography. The specimens were cryopulverized and subjected to metaproteomic analysis for human and bacterial proteins by using a mass spectrometry platform that is based on nanoflow liquid chromatography coupled with linear ion trap quadrupole Velos Orbitrap. RESULTS: The metaproteome analyses revealed the presence of viable and metabolically active human and bacterial cells in both apexes and lesions. Several bacterial proteins of interest for pathogenicity and therapeutics were identified in both apexes and lesions, including proteins related to antibiotic resistance, proteolytic function, stress response, adhesion, and virulence. Many human proteins related to immune defense mechanisms were also detected in both root apex and lesion specimens, including immunoglobulins, complement system, and proteins linked to T-cell and B-cell activation, neutrophil microbicidal processes, antigen recognition/presentation, bone resorption, and protection against tissue damage. CONCLUSIONS: Occurrence of host defense factors from the innate and adaptive immune responses and bacterial virulence, survival, and resistance proteins in matched root apexes/periradicular inflammatory lesions indicates a complex and dynamic host-pathogen interaction in teeth with post-treatment apical periodontitis.

Short-chain Fatty Acids in Infected Root Canals of Teeth with Apical Periodontitis before and after Treatment.

INTRODUCTION: Short-chain fatty acids (SCFAs) are bacterial metabolic end products that may function as virulence factors. This study evaluated the occurrence of SCFAs in infected root canals before and after treatment. METHODS: Samples were taken from root canals of teeth with apical periodontitis before (S1) and after (S2) chemomechanical preparation with either NaOCl or chlorhexidine as the irrigant and then after interappointment medication with calcium hydroxide (S3). High-performance liquid chromatography was used for detection of SCFAs. Selected bacterial taxa that are recognized producers of the target SCFAs were identified by real-time polymerase chain reaction. RESULTS: Butyric acid was the most common fatty acid in S1, followed by propionic acid. Both molecules were also found in S2 and S3 from both NaOCl and chlorhexidine groups. Lactic acid was not present in detectable levels in S1, but it occurred in 1 postinstrumentation sample and in 9 samples taken after calcium hydroxide medication. Of the target taxa, Fusobacterium nucleatum was the most prevalent in S1 (76%), followed by members of the Actinobacteria phylum (71%), Streptococcus species (59%), and Parvimonas micra (53%). Gram-positive taxa, especially streptococci, were the most prevalent bacteria in S2 and S3. SCFA detection was matched with the respective potential producer species in most cases. CONCLUSIONS: This first report of SCFAs in infected root canals suggests that these molecules may play a role in the pathogenesis of apical periodontitis. Significance of persistence of SCFAs after treatment and its effects on the long-term outcome await elucidation.

Metaproteome analysis of endodontic infections in association with different clinical conditions.

Analysis of the metaproteome of microbial communities is important to provide an insight of community physiology and pathogenicity. This study evaluated the metaproteome of endodontic infections associated with acute apical abscesses and asymptomatic apical periodontitis lesions. Proteins persisting or expressed after root canal treatment were also evaluated. Finally, human proteins associated with these infections were identified. Samples were taken from root canals of teeth with asymptomatic apical periodontitis before and after chemomechanical treatment using either NaOCl or chlorhexidine as the irrigant. Samples from abscesses were taken by aspiration of the purulent exudate. Clinical samples were processed for analysis of the exoproteome by using two complementary mass spectrometry platforms: nanoflow liquid chromatography coupled with linear ion trap quadrupole Velos Orbitrap and liquid chromatography-quadrupole time-of-flight. A total of 308 proteins of microbial origin were identified. The number of proteins in abscesses was higher than in asymptomatic cases. In canals irrigated with chlorhexidine, the number of identified proteins decreased substantially, while in the NaOCl group the number of proteins increased. The large majority of microbial proteins found in endodontic samples were related to metabolic and housekeeping processes, including protein synthesis, energy metabolism and DNA processes. Moreover, several other proteins related to pathogenicity and resistance/survival were found, including proteins involved with adhesion, biofilm formation and antibiotic resistance, stress proteins, exotoxins, invasins, proteases and endopeptidases (mostly in abscesses), and an archaeal protein linked to methane production. The majority of human proteins detected were related to cellular processes and metabolism, as well as immune defense. Interrogation of the metaproteome of endodontic microbial communities provides information on the physiology and pathogenicity of the community at the time of sampling. There is a growing need for expanded and more curated protein databases that permit more accurate identifications of proteins in metaproteomic studies.

Development of periradicular lesions in normal and diabetic rats.

Evidence suggests that diabetic patients are more significantly affected by problems of endodontic origin. This study sought to radiographically and histologically examine the development of periradicular inflammation in control and in diabetic rats after induction of pulpal infection. The pulps of the mandibular first molars of normal and streptozotocin-induced diabetic rats were exposed and left in contact with their oral cavities for 21 and 40 days. Afterwards, the animals were sacrificed, the mandibles were surgically removed, fixed in formalin and then radiographed in a standardized position. The radiographic images of the periradicular lesions were scanned and computerized images were evaluated for the total area of the lesions using a specific software. Representative specimens were also prepared for histopathological analysis. Radiographic analysis revealed that diabetic rats presented significantly larger periradicular lesions when compared with control rats, regardless of the experimental period (p<0.05). Histopathological examination of representative specimens revealed larger periradicular lesions and more severe inflammatory exudate in the group of diabetic rats when compared with the control group. Data from the present study indicated that diabetic rats can be more prone to develop large periradicular lesions, possibly due to reduction in the defense ability against microbial pathogens.

Development of periradicular lesions in normal and diabetic rats%Desenvolvimento de lesões perirradiculares em ratos normais e diabéticos

Evidências indicam que pacientes diabéticos são mais significativamente afetados por problemas de origem endodôntica. Este estudo avaliou radiográfica e histologicamente o desenvolvimento de inflamação perirradicular em ratos controle e diabéticos depois da indução de infecção pulpar. As polpas dos primeiros molares inferiores de ratos normais ou diabéticos foram expostas e deixadas em contato com a cavidade oral por 21 e 40 dias. Em seguida, os animais foram sacrificados, as mandíbulas removidas cirurgicamente, fixadas em formalina e depois radiografadas em posição padronizada. As imagens radiográficas das lesões perirradiculares foram escaneadas e as imagens computadorizadas avaliadas quanto à área total das lesões usando software específico. Espécimes representativos foram preparados também para análise histológica. A análise radiográfica revelou que os ratos diabéticos apresentaram lesões periradiculares significativamente maiores quando comparados com os ratos normais, independentemente do período experimental (p<0.05). O exame histológico de espécimes representativos revelou lesões perirradiculares mais extensas e com exsudato inlflamatório severo no grupo de ratos diabéticos quando comparado com o grupo controle. Os dados deste estudo indicam que ratos diabéticos podem ser mais propensos a desenvolver lesões perirradiculares extensas, possivelmente devido à diminuição da capacidade de defesa contra patógenos microbianos.

Development of periradicular lesions in normal and diabetic rats

Evidence suggests that diabetic patients are more significantly affected by problems of endodontic origin. This study sought to radiographically and histologically examine the development of periradicular inflammation in control and in diabetic rats after induction of pulpal infection. The pulps of the mandibular first molars of normal and streptozotocin-induced diabetic rats were exposed and left in contact with their oral cavities for 21 and 40 days. Afterwards, the animals were sacrificed, the mandibles were surgically removed, fixed in formalin and then radiographed in a standardized position. The radiographic images of the periradicular lesions were scanned and computerized images were evaluated for the total area of the lesions using a specific software. Representative specimens were also prepared for histopathological analysis. Radiographic analysis revealed that diabetic rats presented significantly larger periradicular lesions when compared with control rats, regardless of the experimental period (p<0.05). Histopathological examination of representative specimens revealed larger periradicular lesions and more severe inflammatory exudate in the group of diabetic rats when compared with the control group. Data from the present study indicated that diabetic rats can be more prone to develop large periradicular lesions, possibly due to reduction in the defense ability against microbial pathogens.

Evidências indicam que pacientes diabéticos são mais significativamente afetados por problemas de origem endodôntica. Este estudo avaliou radiográfica e histologicamente o desenvolvimento de inflamação perirradicular em ratos controle e diabéticos depois da indução de infecção pulpar. As polpas dos primeiros molares inferiores de ratos normais ou diabéticos foram expostas e deixadas em contato com a cavidade oral por 21 e 40 dias. Em seguida, os animais foram sacrificados, as mandíbulas removidas cirurgicamente, fixadas em formalina e depois radiografadas em posição padronizada. As imagens radiográficas das lesões perirradiculares foram escaneadas e as imagens computadorizadas avaliadas quanto à área total das lesões usando software específico. Espécimes representativos foram preparados também para análise histológica. A análise radiográfica revelou que os ratos diabéticos apresentaram lesões periradiculares significativamente maiores quando comparados com os ratos normais, independentemente do período experimental (p<0.05). O exame histológico de espécimes representativos revelou lesões perirradiculares mais extensas e com exsudato inlflamatório severo no grupo de ratos diabéticos quando comparado com o grupo controle. Os dados deste estudo indicam que ratos diabéticos podem ser mais propensos a desenvolver lesões perirradiculares extensas, possivelmente devido à diminuição da capacidade de defesa contra patógenos microbianos.

Herpervírus em infecções endodônticas / Herpesviruses in endodontic infections

Infecções por vírus são comuns na cavidade oral e estima-se que mais de 90% da população humana apresentam infecção viral em algum momento de suas vidas. Até pouco tempo atrás, a identificação de vírus era onerosa e laboriosa, mas, com o advento de métodos mais simples, sensíveis e específicos, como as técnicas moleculares, ficou mais fácil e rápida a identificação de vírus e diversos quadros patológicos. Estudos recentes têm detectado Herpevírus em doenças periodontais e em lesões perirradiculares de origem endodôntica, mas sem que fosse definido um papel claro destes microorganismos nestas patologias. Estudos adicionais são necessários para estabelecer o papel destes e de outros vírus na patogênese de doenças da cavidade oral.