Mental foramen and apical foramen: A dangerous anatomical proximity.

The study evaluated the spatial position of the mental foramen (MF) using 300 cone-beam computed tomography. The spatial position was analyzed with the horizontal location and relative location (distance between apical foramen and MF). The horizontal location was assessed through three positions (positions 1, 2, and 3). The relative location was determined with the x, y, and x coordinates of the root apex of mandibular premolars and the MF. Student's t-test and chi-square were performed. The most common horizontal location (52%) was position 2, which means between the premolars (p < 0.05). The relative location of the MF to the root apex of the second premolar was closer than the first premolar (p < 0.05). The distance between the root tip of the second premolar and the MF was 5.27 mm, with a minimum value of 1.87 mm. Clinicians should be aware of the possible neural results to the mental nerve of an endodontic infection and the extrusion of irrigation solutions.

An Ex-Vivo Study Comparing the Accuracy of the E-Connect S+ and Morita Tri Auto ZX2+ Endodontic Handpieces in Root Canal Length Determination.

INTRODUCTION: This ex vivo study evaluated the accuracy of the Electronic Apex Locator (EAL) and Automatic Apical Stop (AAS) functions of the E-Connect S+ and Morita Tri Auto ZX2+ cordless apex locators in determining patency length. METHODS: Sixty-four human teeth with a single root were randomly allocated into E-connect or Morita groups (n = 32). The canals were accessed and preflared, after which a size 15 K-file was inserted into the canal to the major foramen and recorded as the actual length (AL). Matched measurements were taken using the AAS and EAL functions and visually confirmed with confocal microscopy. The variance between canal length (mm), the persons correlation (ρ) between function and AL, and the accuracy (%) of the canal length relative to the AL (Δmm) between devices and functions were assessed. RESULTS: Regardless of device or function, all measurements were within 1±Δmm and correlated strongly (ρ > 0.97) with the AL. When considering a more stringent clinically acceptable range of 0.5±Δmm from the AL, all devices and functions demonstrated similar accuracy levels (84%-94%). However, at lower tolerance ranges, the E-connect device with the EAL function exhibited the highest accuracy. On average, all devices and functions stopped short of the AL (mean Δmm>0). CONCLUSION: The E-Connect S+ and Morita Tri Auto ZX2+ apex locators provided reliable accuracy in determining the position of the major foramen. These findings demonstrate a high level of reproducibility in canal length measurements using both cordless endodontic handpieces, regardless of whether the EAL or AAS functions were employed.

Measurement of the apical anatomy of immature maxillary central incisors using cone-beam computed tomography.

OBJECTIVE: To investigate the CBCT findings of the apical anatomy of immature maxillary central incisors. METHODS: CBCT images of 100 immature maxillary central incisors in Nolla 8 and 100 immature maxillary central incisors in Nolla 9 were collected. The mesiodistal and carniocaudal diameters of the apical foramen of immature maxillary central incisors were measured by software included with CBCT, as well as the mesiodistal, carniocaudal and facioligual diameters of the apical shadow. The apical shadow and apical foramen diameters were compared between Nolla 8 and Nolla 9. Data were analyzed using the MedCalc software package. RESULTS: For immature maxillary central incisors, the mesiodistal and facioligual diameters of the apical foramen were 2.75±0.68 mm and 3.28±0.74 mm in Nolla 8 and 1.50±0.51 mm and 1.92±0.79 mm in Nolla 9. The mesiodistal, facioligual and carniocaudal diameters of the apical shadow were 3.84±0.73 mm, 4.49±0.68 mm and 3.41±1.27 mm in Nolla 8 and 2.76±0.60 mm, 3.41±0.80 mm and 2.06±0.65 mm in Nolla 9, respectively. CONCLUSIONS: The immature maxillary central incisors in Nolla 8 have a larger apical shadow and apical foramen than those in Nolla 9. The apical region of the maxillary central incisors in Nolla 8 was more likely to have a broad, blurred lamina dura. With the development of the apical foramen, the lamina dura in the apical region tended to be clear and sharp. CLINICAL SIGNIFICANCE: To our knowledge, this is the first study to radiologically analyse the in vivo anatomy of the apical foramen and apical shadow of immature maxillary central incisors. The results of this study provide a more detailed understanding of the apical anatomy of the immature maxillary central incisor for the diagnosis and treatment of apical lesions.

The difference distance between the apical foramen and the anatomical apex in primary teeth-An in vitro study.

INTRODUCTION: The apex area in the primary teeth changes continuously due to the physiologic resorption, therefore; the apical foramen (AF) may not correspond to the anatomic apex (AA), which gives a big challenge to achieve successful endodontic treatment. The aim of this research was to study the difference distance (DD) between the position of the AA and AF, besides the difference acceptance (DA) in primary teeth, and the effect of the following variables: root canal curvature, resorption degree, and canal size on DD and DA separately. METHODS: In this research, 180 root canals from 60 primary teeth were studied. Two lengths of each canal were measured by a K-file from a certain point in the crown; the first length was until the AA and the second was until the AF. Then DD was obtained by calculating the difference between those two lengths. Statistical analysis tests were done. A p value of <.05 was considered significant at a 95% confidence level. RESULTS: The percentage of canals with 0 mm DD was 34.4%, while it was 1.1% with DD of 6 mm. The percentages of acceptable ( ≤ 2 mm) and unacceptable ( > 2 mm) difference were 84.4% and 15.6%, respectively. There was a significant difference in the DD value between the three groups of curvature degree and the three groups of canal size. There was a significant difference between the DA in the three groups of canal size. CONCLUSION: DD has a wide variation value in primary teeth regardless of the degree of root resorption, which has not affected this value or the accepted difference; however, DD and acceptable difference values are somehow affected by the degree of root curvature and canal size. We recommend adding acceptable difference as a criterion when considering pulpectomy treatment in primary teeth.

Evaluating the efficacy of endodontic microsurgery for teeth with an undeveloped root apex and periapical periodontitis after nonsurgical treatment failure.

AIM: To determine the efficacy of endodontic microsurgery for teeth with an undeveloped root apex and periapical periodontitis caused by an abnormal central cusp fracture after failed nonsurgical treatment. METHODOLOGY: Eighty teeth in 78 patients were subjected to endodontic microsurgery. All patients were clinically and radiologically examined 1 year postoperatively. The data were statistically analyzed using SPSS 27.0 software. RESULTS: Of the 80 teeth in 78 patients, periapical lesions had disappeared in 77 teeth at 1-year postoperative follow-up, with a success rate of approximately 96.3% (77/80). The efficacy of endodontic microsurgery was not affected by sex, age, extent of periapical lesions, and presence of the sinus tract. Between-group differences were not statistically significant (P > 0.05). CONCLUSIONS: Endodontic microsurgery can be an effective alternative treatment option for teeth with an undeveloped root apex and periapical periodontitis caused by an abnormal central cusp fracture after nonsurgical treatment failure.

Clinical Accuracy and Precision of 3 Multifrequency Electronic Apex Locators Assessed through Micro-Computed Tomographic Imaging.

INTRODUCTION: This study aimed to compare the in vivo accuracy and precision of 3 electronic apex locators (EALs) in determining the position of the major foramen using micro-computed tomographic (micro-CT) technology. METHODS: After access preparation of 23 necrotic or vital teeth from 5 patients, canals were negotiated, and hand files were used to determine the position of the foramen with 3 EALs: Propex Pixi (Dentsply Maillefer, Ballaigues, Switzerland), Woodpex III (Woodpecker Medical Instrument Co, Guilin, China), and Root ZX II (J Morita, Tokyo, Japan). After fixing the silicon stop to the file, teeth were extracted and scanned in a micro-CT device with and without the instrument inserted into the canal. Data sets were coregistered, and the accuracy and precision of the EALs were determined at a tolerance level of ±0.5 mm by measuring the distance from the tip of the instruments to a tangential line crossing the margins of the foramen. Statistical comparisons were performed using Friedman with post hoc related samples sign and Spearman tests (α = 5%). RESULTS: A significant difference was detected comparing the accuracy of Root ZX II (100%), Woodpex III (86.96%), and Propex Pixi (52.17%) (P < .05). There was a lack of significance in the relationship between the pulp status and the accuracy of the tested EALs (P > .05). Propex Pixi was significantly less precise than Root ZX II (P < .05), whereas no difference was found between Woodpex III and Root ZX II or Propex Pixi (P > .05). CONCLUSIONS: EALs presented similar precision, but Woodpex III and Root ZX II showed better accuracy to determine the position of the apical major foramen than Propex Pixi.

Platelet-rich Fibrin Promotes the Proliferation and Osteo-/odontoblastic Differentiation of Human Dental Pulp Stem Cells.

BACKGROUND: Pulp regeneration is a promising strategy that promotes the continued development of young permanent teeth with immature apical foramen. Platelet-rich fibrin (PRF) was found to stimulate the proliferation and differentiation of osteoblasts, but its effects on osteoblast/odontoblast differentiation of human dental pulp stem cells (hDPSCs) are unknown. METHODS: The hDPSCs were isolated and identified using known surface markers by flow cytometry. The CCK-8 assay and the expression of Ki67 and PCNA were used to examine hDPSC proliferation. After 7 days of culture in an osteo-/odontoblastic induction medium with various concentrations of liquid PRF (0, 10% and 20%), the early stage of osteogenesis-intracellular alkaline phosphatase (ALP) was checked. After 21 days of culture, matrix mineralization was checked using Alizarin Red S and quantified. The mRNA and protein levels of osteo-/odontoblastic genes, including RUNX2, DSPP, DMP1 and BSP, were measured by qRT-PCR. The notch signal was checked by Western blot to analyze three key proteins (Notch 1, Jagged 1 and Hes 1). RESULTS: PRF-treated groups showed higher expression of Ki-67 and PCNA, higher ALP activity, and the higher dose showed a stronger induction. PRF promoted osteo-/odontoblastic differentiation of hDPSCs indicated by elevated protein levels and mRNA levels of the expression of osteo-/odontoblastic markers. The three key proteins in Notch signaling showed an increase compared with the control group and increased as the PRF concentration increased. CONCLUSION: PRF can promote the proliferation and osteo-/odontoblastic differentiation of hDPSC, which may be through the Notch signaling pathway.

Clinical effects of iRoot BP plus and mineral trioxide aggregate in treatment of apical periodontitis with open apical permanent teeth / 口腔医学

Objective@#To analyze and evaluate the clinical application effect of bioceramic material mineral trioxide aggregate and iRoot BP plus on the formation of apical barrier in adult teeth with incomplete apical foramen.@*Methods@#A total of 200 permanent teeth with apical periodontitis whose apical foramen were not closed were randomly divided into two groups, and the apical barrier was prepared with MTA and iRoot BP plus, respectively. The operation time of MTA and iRoot BP plus and effects of different types of apical foramen destruction, lesion range of apical area, the filling of apical area and patients' age on the treatment success rate was analyzed and compared. @*Results@#The operation time of preparing apical barrier in iRoot BP plus group was shorter than that in MTA group, and the difference was statistically significant (P<0.05). However, different types of apical foramen destruction, lesion scope of apical area, filling of apical area and patients' age had no effect on the treatment success rate of the two groups (P>0.05). @*Conclusion@#The clinical effects of MTA and iRoot BP plus in the treatment of apical periodontitis of permanent teeth with unclosed apical foramen are similar, but the operation performance of iRoot BP plus is better.

Morphological alterations of the apical foramen after foraminal enlargement: a systematic review of ex vivo studies / Alterações morfológicas do forame apical após ampliação foraminal: uma revisão sistemática de estudos ex vivo

Foraminal enlargement has been recommended to optimize the disinfection of infected root canals, although some authors still claim that the foramen should be kept in its original shape and position. This study aimed to evaluate morphological alterations of apical foramen after foraminal enlargement through a systematic review. An electronic search was conducted until April 2022. Ex vivo studies evaluating influence of foraminal enlargement in the morphologic changes of apical foramen were included. Studies without a control group or available full text were excluded. Foraminal deformation and area increase were considered as primary outcomes. Risk-of-bias assessment was performed according to a modified Joanna Briggs Institute's Checklist. From 702 studies retrieved, five were eligible. Most studies used single-rooted teeth, and rotary systems for instrumentation ranging from ­ 2 mm to + 1 mm to the apex. All studies found increased major foramen deformation after foraminal enlargement. Among four studies that evaluated foraminal area, all found increased area after foraminal enlargement. Insufficient data for touched/untouched walls by instruments and dentinal microcrack formation was observed. A low risk of bias was found. Foraminal enlargement during root canal preparation seems to increase deformation and major apical foramen area. Future investigations with standardized methodologies are encouraged (AU)

A ampliação foraminal tem sido recomendada para otimizar a desinfecção de canais radiculares infectados, embora alguns autores ainda afirmem que o forame deve ser mantido em sua forma e posição originais. Este estudo teve como objetivo avaliar alterações morfológicas do forame apical após ampliação foraminal por meio de uma revisão sistemática. Uma busca eletrônica foi realizada até abril de 2022. Foram incluídos estudos ex vivo que avaliaram a influência da ampliação foraminal nas alterações morfológicas do forame apical. Foram excluídos estudos sem grupo controle ou com texto completo indisponível. A deformação foraminal e o aumento da área foram considerados desfechos primários. A avaliação do risco de viés foi realizada de acordo com uma lista de verificação modificada do Instituto Joanna Briggs. Dos 702 registros recuperados, cinco foram elegíveis. A maioria dos estudos utilizou dentes unirradiculares e sistemas rotatórios para instrumentação, com comprimento de trabalho variando de ­ 2 mm a + 1 mm até o ápice. Todos os estudos encontraram aumento da deformação do forame maior após ampliação foraminal. Dos quatro estudos que avaliaram a área foraminal, todos encontraram aumento de área após alargamento foraminal. Foram observados dados insuficientes para paredes tocadas/intocadas pelos instrumentos e formação de microfissuras dentinárias. Um baixo risco de viés foi encontrado. A ampliação foraminal durante o preparo do canal radicular parece aumentar a deformação e a área do forame apical. Futuras investigações com metodologias padronizadas são incentivadas (AU)

Comparative evaluation of working length determined using integrated apex locator and root ZX mini under various irrigating solutions: An in vivo study.

Background: Electronic apex locators (EALs) are frequently used as adjuvant to radiographs in working length (WL) determination. The introduction of integrated apex locators (IALs) further simplified the root canal treatment by continuous monitoring of the apex while root canal shaping. Aim: The aim of this study was to evaluate the efficacy of radiographs, EAL, and IAL in determining the WL in the presence of various irrigants. Materials and Methods: The present in vivo study was carried out on 30 patients who were divided into 10 in each group, based on the type of irrigant used; 0.9% saline (Group 1), 0.2% chlorhexidine (Group 2), and 2.5% of sodium hypochlorite (NaOCL) (Group 3). In each group, WL is determined using conventional radiographs, Root ZX Mini (EAL), and CanalPro CL2i (IAL). Statistical Analysis: Kruskal-Wallis test and Friedman's two-way ANOVA test were used for statistical analysis. Results: Mean WL was comparably lower with Root ZX Mini, while the WL by CanalPro CL2i and the radiographic method were comparable. In all methods, the type of solutions used did not influence the WL, with a higher mean WL when NaOCL is used as an irrigant. Nevertheless, the above comparisons were not statistically significant. Conclusion: the irrigation solutions employed in this study had no impact on the performance of apex locators and radiographs.

Apical transportation with different root canal preparation techniques using edgEEvolve rotary instruments.

Background: This study aimed to investigate the extent of apical transportation following instrumentation with EdgeEvolve rotary instruments applying single-length and crown-down techniques. Materials and Methods: In this experimental in-vitro study, 60 mandibular molars with mesiobuccal curvatures of 20°-40° were selected, and digital radiographic images were taken. Teeth were randomly assigned into two groups of single-length and crown-down preparation techniques. In both mentioned groups, EdgeEvolve rotary system was used. After preparation, the same as the previous ones, digital radiographic images were taken from the canals. The data were analyzed using Student' t-test and ShapiroWilk normality test (P = 0.05). Results: The mean standard deviation (SD) for apical transportation in the single-length and the crown-down group was 4.42 (2.9) and 7.48 (3.9) degrees, respectively (P < 0.05). The mean SD of the preparation time in the single-length and crown-down group was 135.07 (30.8) and 109.07 (20.8), respectively (P < 0.05). The apical transportation and the time of preparation between the two groups were significant. Conclusion: Using EdgeEvolve rotary instruments canal preparation with both single-length and crown-down techniques led to some degrees of apical transportation.

Micro-CT Study of the In Vivo Accuracy of a Wireless Electronic Apex Locator.

INTRODUCTION: This study aimed to compare the in vivo accuracy of Wirele-X and RootZX II electronic apex locators (EALs) in determining the position of the major foramen using micro-computed tomography (micro-CT) as the analytical tool. METHODS: Eleven vital teeth planned for extraction from 5 patients were used. After conventional access cavity preparation, root canals were flared and negotiated up to the apical third with sizes 08 and 10 K-files followed by irrigation with 2.5% NaOCl. K-type files were used to determine the working length of the selected canals using Root ZX II and Wirele-X apex locators until their numeric displays read "0.0." After fixing the silicon stop to the file, teeth were extracted and imaged in a micro-CT device using a double-scan protocol. Image stacks, with and without the file in the root canal, were then co-registered and the measurement error calculated as the absolute difference between the tip of the file and the major foramen. Positive and negative values were recorded when the file tip was detected beyond or short of the major foramen, respectively. Accuracy was determined on stable measurements within ± 0.5 mm when the file tip did not extend beyond the major foramen. The χ2 test was applied to compare the ability of the EALs to detect the position of the major foramen, and the t test for dependent variables was used to verify differences in the 2 measurements obtained in each tooth. Significance level was set at 5%. RESULTS: Within a tolerance level of ± 0.5 mm, no significant differences were observed between the tested EALs regarding the absolute distance values (P = .82) or in their ability to detect the position of the major foramen (χ2 = 0.2588; P = .6109). The accuracy of the Root ZX II and the Wirele-X apex locators within ± 0.5 mm were 81.8% and 90.9%, respectively. CONCLUSIONS: Root ZX II and Wirele-X performed similarly regarding the in vivo detection of the major foramen. Using strict criteria, the accuracy of the Root ZX II and the Wirele-X apex locators were 81.8% and 90.9%, respectively.

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.

Influence of heat treatment of nickel-titanium instruments on the accuracy of an electronic apex locator integrated with endodontic motor.

Context: Manufacturers have produced a wide variety of nickel-titanium (NiTi) alloys, but the available literature is limited on the accuracy of some integrated electronic apex locators (EAL) used with different NiTi heat treatments in working length (WL) determination. Aim: This study aims to evaluate ex vivo , the influence of different heat treatments of NiTi instruments, and the diameter of the apical preparation on the accuracy of an EAL used during root canal preparation using an integrated EAL and motor unit. Materials and Methods: Nineteen extracted human mandibular incisors were included in the study. The WL control was determined by the visual method. Instruments of Mtwo, Reciproc, Reciproc Blue, WaveOne Gold, Twisted File Adaptive, and Hyflex CM systems, with diameters from 0.25 mm to 0.50 mm, were used to measure WL during root canal preparation. The electrical resistivity of instruments with a diameter of 0.25 mm from each system was evaluated using an Inductance, Capacitance, and Resistance (LCR) meter. Statistical Analysis Used: Data were statistically analyzed using Fisher's exact test and Kruskal-Wallis test. Results: The different heat treatments and different diameters did not influence the precision of the EAL (P > 0.05). Conclusion: The heat treatment and the diameter of the apical preparation did not influence the accuracy of WL determination by an EAL integrated with the endodontic motor.

The Effect of Long Service Life on the Accuracy of Dentaport ZX Electronic Apex Locator.

Introduction: Electronic apex locators are among the most acceptable instruments for determining root canal length. The present study aimed to evaluate the effect of long service life on the accuracy of the Dentaport Root ZX (DP ZX) electronic apex locator (EAL). Materials and Methods: In this study, fifty single-rooted freshly extracted human teeth were used. After determining the root canal length with a K-file and a dental operative microscope, the canals were measured with four separate DP ZX apex locators (two with more than 6 years of life service while two others had less than 6 years of life service). Data were analyzed by repeated ANOVA measurement. Results: No significant difference was found between the EALs with different years of life services (P=0.62). All EALs could determine root canal length with high accuracy of more than 94%. Conclusion: Based on the results of this in vitro study, the long service life had no significant impact on the accuracy of DP ZX EALs in terms of root canal length determination.

Accuracy of Four Apex Locators in Premolars with Root Resorption: An In vitro Study.

Introduction: The aim of the present in vitro study was to compare the accuracy of the working length measurements of four foramen locators: Root ZX mini, Raypex 6, Woodpex III and Propex Pixi in uniradicular premolars with simulated root resorption. Materials and Methods: For this study, 30 single-rooted permanent premolars were selected. The samples were divided into two groups: 15 teeth with simulated external root resorption and 15 teeth with internal resorption. Each sample was immersed in containers with alginate covering only the root part. Measurements were acquired from the four foramen locators and compared with the working length measurements that have been previously obtained with the direct visual technique and the use of a Digital USB Microscope under 5×. Next, the Shapiro-Wilk normality test was applied. The ANOVA test and t-test for related samples were performed, in order to analyze the measurements obtained. Results: In the teeth with external resorption, no statistically significant differences in the measurements were obtained with Raypex 6 and Propex Pixi foramen locators, but there were statistically significant differences with Root ZX mini and Woodpex III Root Zx mini [Root Zx mini (P=0.040) and Woodpex III (P=0.000)]. On the other hand, in the samples with internal root resorption, there were no statistically significant differences in measurements with the Root ZX mini, Propex Pixi and Raypex 6 foramen locators. However, there were significant differences with Woodpex III. Conclusions: Based on this in vitro study, Raypex 6 had the highest accuracy in premolars with simulated external resorption and Root ZX mini was the most accurate in teeth with simulated internal resorption. Furthermore, external root resorption affects the accuracy of foramen locators more than internal resorption.

Avaliação das alterações morfológicas do forame apical após ampliação foraminal: uma revisão sistemática / Evaluation of morphological alterations of apical foramen after foraminal enlargement: a systematic review

Este trabalho de revisão sistemática propôs-se a avaliar as alterações morfológicas do forame apical após procedimento de ampliação foraminal. Foi realizada busca eletrônica nas bases de dados PubMed/Medline, Scopus, Web of Science, SciELO, Embase, Google Acadêmico e listas de referência até abril de 2022. Apenas estudos ex vivo avaliando a influência do alargamento foraminal nas alterações morfológicas do forame apical foram incluídos. Estudos sem um grupo controle ou texto completo disponível foram excluídos. Deformação foraminal e aumento de área do forame foram considerados os desfechos primários. A avaliação do risco de viés foi realizada de acordo com uma lista de verificação modificada do Joanna Briggs Institute. Setecentos e dois estudos foram recuperados, dos quais treze eram elegíveis para análise qualitativa. A maioria dos estudos utilizou molares superiores ou inferiores com canais radiculares curvos e sistemas rotatórios e reciprocantes para instrumentação. O comprimento de trabalho determinado pelos estudos incluídos variou de dois milímetros aquém a um milímetro além do forame apical. Em relação à deformação foraminal, dos estudos incluídos nesta revisão, oito encontraram aumento da deformação do forame após ampliação foraminal, enquanto cinco não observaram influência significativa. Entre oito estudos que avaliaram a área foraminal, todos encontraram aumento da área após ampliação foraminal. Dados insuficientes para paredes tocadas/intocadas pelos instrumentos endodônticos e formação de microtrincas dentinárias foram observados. Um baixo risco de viés foi encontrado. Dentro das limitações desta revisão, nota-se que a ampliação foraminal durante o preparo do canal radicular parece aumentar a deformação e a área do forame apical, especialmente quando o comprimento de trabalho excede o limite do forame maior em, pelo menos, um milímetro. No entanto, não foi possível concluir se existe um protocolo conservador, porém eficaz, para ampliação foraminal, devido à grande heterogeneidade metodológica dos estudos. Futuras investigações com metodologias padronizadas são encorajadas a fim de se fornecer evidências mais robustas.

This systematic review aimed to evaluate the morphological alterations of the apical foramen after foraminal enlargement procedure. Electronic searches were performed in PubMed/Medline, Scopus, Web of Science, SciELO, Embase, Google Scholar databases and reference lists until April 2022. Only ex vivo studies evaluating the influence of foraminal enlargement on morphological changes of the apical foramen were included. Studies without a control group or full text available were excluded. Foraminal deformation and increased area were considered the primary outcomes. The risk of bias assessment was performed according to a modified Joanna Briggs Institute checklist. Seven hundred two studies were retrieved, of which thirteen were eligible for qualitative analysis. Most studies used maxillary or mandibular molars with curved root canals and rotary and reciprocating systems for instrumentation. The working length determined by the included studies ranged from two millimeters short to one millimeter beyond the apical foramen. Regarding foraminal deformation, of the studies included in this review, eight found an increase in foramen deformation after foraminal enlargement, while five did not observe a significant influence. Among eight studies that evaluated the foraminal area, all found an increase in the area after foraminal enlargement. Insufficient data for touched/untouched cemental walls by endodontic instruments and formation of dentin microcracks were observed. A low risk was found in the risk of bias analysis of eligible studies. Within the limitations of this review, it is noted that foraminal enlargement during root canal preparation seems to increase the deformation and area of the apical foramen, especially when the working length exceeds the limit of the greater foramen by at least one millimeter. However, it was not possible to conclude whether there is a conservative but effective protocol for foraminal enlargement due to the great methodological heterogeneity of the studies. Future investigations with standardized methodologies are encouraged in order to provide more robust evidence.

Radiographic and electronic working length comparison. An in vivo study of three Electronic Apex Locator devices.

The aim of this study is to compare the working length measured with Root ZX (EAL1), Propex II (EAL2) and Endo Analyzer Model 8005 (EAL3) with radiographic measurements during endodontic treatment. Fifty single canal teeth scheduled for endodontic treatment were selected for the study. After endodontic access preparation, pulp chamber was irrigated with 5mL of 5% sodium hypochlorite (NaOCl). The canal was scouted with a size 10 K-file introduced slightly over the apex to verify the canal patency. The working length (WL) was measured using all three EAL devices and radiographically. All measured working lengths were recorded and compared using ANOVA for repeated measures considering the multiple comparison of paired data Least Significant Difference (LSD). The WL mean values for EAL1 were 19.1 ± 1.7 mm; for EAL2 were 19.4 ± 1.7; for EAL3 were 19.4 ± 1.6 and for RG were 19.2 ± 1.7. The Pearson correlation coefficients indicated that the following correlation between electronic devices and radiographic WL: EAL1- 0.986, EAL2- 0.953 and EAL3- 0.931. Considering the mean values compared to radiographic measures, Root ZX gave better results than the other tested EAL devices. Endo Analyzer Model 8005 showed the worst performance.

Is canal overinstrumentation able to produce apical root dentinal microcracks in extracted teeth?

AIM: To assess the impact of mechanical overinstrumentation of root canals in extracted teeth on the development of dentinal microcracks in the apical portion of the root by means of micro-computed tomographic (micro-CT) analysis. Root canal preparation short of the canal terminus and at the apical foramen (AF) were used as controls. METHODOLOGY: Twenty 2-rooted maxillary premolars with two canals were selected, scanned in a micro-CT device and the root canals prepared sequentially using Reciproc M-Wire R25 instruments to working lengths: 1 mm short of the AF (AF - 1 mm), at the AF (AF), and overinstrumentation (AF + 1 mm). A micro-CT scan of each specimen was performed after each time point. After reconstruction and co-registration procedures, the images were screened from the cementoenamel junction to the apex (n = 55 352) to identify the presence of dentinal microcracks in the apical third of the root. RESULTS: After the analyses of 55 352 slices, dentinal microcracks were visualized in 12.45% of the images (6892 slices), with 5.73% (3174 slices) in the cervical, 3.57% (1976 slices) in the middle and 3.15% (1740 slices) in the apical third. All dentinal microcracks observed at all time points (AF - 1 mm, AF and AF + 1 mm) were already present in the corresponding images before canal instrumentation. Therefore, no new microcracks were detected, regardless of the working length used for canal instrumentation. CONCLUSION: Reciprocating root canal preparation either short, at or beyond the AF (overinstrumentation) did not create dentinal microcracks in the roots of extracted 2-rooted maxillary premolars.