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.

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.

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.

Clinical accuracy and precision of 3 multi-frequency electronic apex locators assessed through micro-CT 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, Woodpex III and Root ZX II. 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. Datasets were co-registered, 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 tested EALs (P > .05). Propex Pixi was significantly less precise than Root ZX II (P < .05), while no difference was found between Woodpex III to either 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 foramen than Propex Pixi.

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-CT as analytical tool.

METHODS

Eleven vital teeth from 5 patients planned for extraction 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 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 Chi-square test was applied to compare the ability of the EALs to detect the position of the major foramen, while T test for dependent variables was used to verify differences in the two 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=0.82) or in their ability to detect the position of the major foramen (Χ²=0.2588; p=0.6109). 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.

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.

Evaluation of Temperature Increase From Joule Heat in Numerical Tooth Model by Applying 500 kHz Current for Apical Periodontitis Treatment-Effect of Applied Voltage and Tooth Conductivity

For apical periodontitis treatments, a new method with the insertion of an electrode into the root canal of a tooth and application of a current at 500 kHz to sterilize the area by Joule heat has attracted attention. However, few studies have quantified the temperature increase in the root canal. This study aimed to investigate the basic characteristics of the temperature increase in a simple and standard tooth model when energizing a current at 500 kHz to the numerical tooth model with typical electrical and physical properties. We developed a numerical model of a standard tooth (dentin) and periodontal tissues consisting of an alveolar bone, cortical bone, and gingiva, and physiological saline in a root canal and calculated the temperature increase inside the numerical model by a coupled analysis of current and heat when a voltage was applied across the electrodes. The calculated results for the different applied voltages showed a temperature increase at the apical portion of the root canal, which increased with the applied voltage even for the same total supplied energy. The temperature increase occurred at the apical portion of the root canal as the tooth conductivity decreased. When the tooth conductivity was high, a current passed through the dentin, which led to a decrease in the temperature at the apical portion of the root canal. However, a chemical solution with a higher conductivity in the root canal tended to increase the temperature at the apical portion of the root canal, regardless of the tooth conductivity. More efficient approaches for increasing the spatial and temporal temperature for the tooth model target are needed. © 2021 Bioelectromagnetics Society.

Morphological Changes of the Root Apex in Permanent Teeth with Failed Endodontic Treatment

OBJECTIVE

To determine the number, shape and diameter of apical foramina as well as changes in root apex morphology of permanent teeth with failed endodontic treatment.

METHODS

Clinical records were collected for teeth diagnosed with posttreatment periapical periodontitis that subsequently underwent endodontic microsurgery. Resected root apices were examined with stereomicroscopy. The number, shape and diameter of apical foramina were recorded. Scanning electron microscopy (SEM) was used to investigate the presence and extent of apical external root resorption and evaluate how it was influenced by sex, age, tooth position, periapical radiolucency size and periapical lesion biopsy results. External root resorption was classified according to site (periforaminal or foraminal), and the extent of resorption was graded as 0, 1, 2 or 3.

RESULTS

A total of 112 teeth with 112 apices were examined. The mean diameter of the main apical foramina was 420.78 µm. The apical foramen was most commonly irregularly shaped (68.39%). The incidence of multiple foramina was 48.21%. SEM revealed that 96.43% of apices had periforaminal resorption (PR) and 94.64% had foraminal resorption (FR). The existence and extent of external root resorption were not correlated with sex, age, tooth position, periapical radiolucency size or periapical lesion biopsy results (P > 0.05).

CONCLUSION

Apical foramina of permanent teeth with failed endodontic treatment were commonly irregularly shaped, with a mean diameter of approximately 420 µm. Nearly half of the samples had multiple foramina. There was a high prevalence of apical external root resorption. A relationship may exist between morphological changes in the root apex and treatment failure.

Comparison of three different apex locators in determining the working length of mandibular first molar teeth with irreversible pulpitis compared with an intraoral periapical radiograph: A block randomized, controlled, clinical trial

AIM

The aim of the present study was to assess the clinical accuracy APEX and 0.5 marks of three different apex locators - iPex II, Root ZX, and Apex ID - before and after canal preparation in the mandibular first molar.

METHODS

Sixty patients between the ages of 13-60 years participated in the study. After access gaining and canal preparation stages files were inserted with the apex locator clip attached until the electronic apex locators (EALs) shows readings of APEX and 0.5 marks and same is confirmed with periapical radiographs. Eighteen apex locator readings were recorded from each tooth, and 1080 readings were obtained from the 60 patients.

RESULTS

Differences among readings from apex locators and radiographic readings were assessed using paired t test. Only in two patients (1 male and 1 female) were the APEX mark readings different from the radiograph estimation. When the 0.5 mark readings of three different EALs were compared with each other, we could observe that the readings from Root ZX differed significantly (P < 0.05).

CONCLUSIONS

In the present study, we observed the negligible differences in readings between the EAL at the APEX mark readings, coinciding with the radiographic observation. Clinically, we recommend the apical foramen be located with the apex locators' APEX mark readings prior to identifying the apical constriction position.

Comparative evaluation of apical constriction position in incisor and molar teeth: An in vitro study

Objective:

The apical constriction (AC) and the apical foramen (AF) are the principal reference points used to determine the apical limit for instrumentation and root canal filling. AC varies in different races, and the aim of the current study was to measure and compare the distances from AC to AF and the anatomical apex (AA) in incisor and molar teeth in the Iranian population.

Materials and Methods:

Forty-five roots of incisor teeth and 45 roots of molar teeth were selected randomly in Isfahan Province, Iran. If the foramen was located toward the mesial or distal side of the apex, the cut was made mesiodistally, and if it was toward the buccal or lingual side, the section was made accordingly. Roots were examined under a microscope at ×25 magnification. The distances from AC to AF and AA were then estimated using a Motic camera. Descriptive statistics were used. The independent t-test was also used to compare distances in incisors and molars, and P = 0.05 was deemed to indicate statistical significance.

Results:

The mean distances between AC and AF were 0.847 ± 0.33 mm in incisors and 0.709 ± 0.27 mm in molars. The mean distances between AC and AA were 1.23 ± 0.39 mm in incisors and 1.01 ± 0.38 mm in molars. In an independent t-test, the distances between AC and AF differed significantly in incisors and molars (P = 0.035), but the distances between AC and AA did not (P = 0.172).

Conclusion:

The end points for root canal therapy should be 0.85 mm in incisors and 0.70 mm in molars.

Accuracy and consistency of electronic root canal length determination with electrically isolating rubber stoppers

The aim of this study was to investigate the influence of an isolating silicone stopper on the measuring accuracy and display consistency of three electrometric apex locators. The length of the canal to the major foramen was determined electrometrically using an ISO size 10 file in 20 extracted teeth each with natural crowns (Group I), amalgam fillings (Group II) or base-metal crowns (Group III), The measurements were performed with isolating or conventional silicone stoppers using three different apex locators with a four-level scale consistency rating. The use of isolating stoppers resulted in a more consistent display than with conventional stoppers, independent of the presence or type of coronal restoration (P = 0.017). Across all coronal restorations, the position of the major foramen could be determined to within ± 0.5 mm without significant differences (P = 0.79) using conventional and isolating stoppers. The use of modified isolating stoppers provides a significant increase in display consistency.

Influence of different sized files on the accuracy of two electronic apex locators

The aim of this study was to evaluate the impact of different file sizes on the accuracy of two electronic apex locators (EALs). Thirty extracted human single-rooted permanent mandibular incisors were used. A #10 K-file was inserted in the root canal until its end could be observed (using a light microscope) through the apical foramen. One millimetre was subtracted to establish working length (WL). Electronic readings were performed using MiniApex Locator or Root ZX II, from #10 K-file to #130 K-file. Statistical analysis was performed by two-way anova and Tukey test (P ≤ 0.05). From #60 to #130 K-file, observed differences were noted between the values obtained with both EALs and WL (P ≤ 0.05). The MiniApex Locator showed increased means when measurements were made with #50 to #70 and with #120 (P = 0.008) and #130 (P = 0.005) K-files. File sizes influenced the accuracy of EALs - the greater the instrumentation size, the higher mean differences compared to WL.

Comparison of four electronic root canal length measurement devices

OBJECTIVE

The objective of this study is to evaluate the performance of four electronic root canal length measurement devices (ERCLMDs) [Root ZX, Raypex 6, ProPex II, and VDW Gold with ERCLMD] in wet and dry root canals with different major foramen diameters, in association with three file positions within the final 1 mm of canals.

MATERIALS AND METHODS

Fifty roots were divided into five groups that were instrumented apically to the terminus diameter using K-files 15, 20, 30, 40, and 60. ERCLMD measurements were made when the file tip was at major foramen, 0.5 mm and 1.0 mm short of the foramen, when the apex touched to the surface of saline or was immersed 3 mm into saline, and when the canal was dry or was irrigated with saline. The differences between the electronic lengths and the actual lengths were calculated. The data were analyzed using the three-, two-, and one-way ANOVA and the LSD test (p < .05).

RESULTS

Overall, the four ERCLMDs demonstrated 12.8% unstable and beyond the foramen measurements (11.3%). About 85% of the beyond the foramen measurements had foramen diameters 0.40 and 0.60. ERCLMD comparisons related to the file positions in the foramen diameters showed significant differences between ERCLMDs in each foramen diameter (p < .05).

CONCLUSIONS

All ERCLMDs provided highly accurate measurements within the final 1 mm of the foramen. Wet or dry canals and apex conditions did not adversely affect the accuracy of the ERCLMDs' readings. ProPex II located the file positions in the teeth with different foramen diameters more accurately than the other ERCLMDs.

Optimized 14 + 1 receive coil array and position system for 3D high-resolution MRI of dental and maxillomandibular structures

OBJECTIVES

The purpose of this study was to design, build and test a multielement receive coil array and position system, which is optimized for three-dimensional (3D) high-resolution dental and maxillomandibular MRI with high patient comfort.

METHODS

A 14 + 1 coil array and positioning system, allowing easy handling by the technologists, reproducible positioning of the patients and high patient comfort, was tested with three healthy volunteers using a 3.0-T MRI machine (Siemens Skyra; Siemens Medical Solutions, Erlangen, Germany). High-resolution 3D T1 weighted, water excitation T1 weighted and fat-saturated T2 weighted imaging sequences were scanned, and 3D image data were reformatted in different orientations and curvatures to aid diagnosis.

RESULTS

The high number of receiving coils and the comfortable positioning of the coil array close to the patient's face provided a high signal-to-noise ratio and allowed high quality, high resolution, 3D image data to be acquired within reasonable scan times owing to the possibility of parallel image acquisition acceleration. Reformatting the isotropic 3D image data in different views is helpful for diagnosis, e.g. panoramic reconstruction. The visibility of soft tissues such as the mandibular canal, nutritive canals and periodontal ligaments was exquisite.

CONCLUSIONS

The optimized MRI receive coil array and positioning system for dental and oral-maxillofacial imaging provides a valuable tool for detecting and diagnosing pathologies in dental and oral-maxillofacial structures while avoiding radiation dose. The high patient comfort, as achieved by our design, is very crucial, since image artefacts due to movement or failing to complete the examination jeopardize the diagnostic value of MRI examinations.

Accuracy of three electronic apex locators in determining the apical foramen in multi-rooted teeth: Randomised clinical and laboratory study

This study aimed to compare the accuracy of three electronic apex locators (EALs), Raypex 5, Apex NRG and ProPex II, in locating the apical foramen (AF) in vivo. Thirty multi-rooted teeth were included in the study. Distances from the file tip to the radiographic apex from the buccal (R1) and mesial (R2) aspect were measured after extraction. The distance from the file tip to the AF (L) was measured microscopically. Raypex 5, Apex NRG and ProPex II were accurate to within ± 0.5 mm in 84.6%, 78.6% and 66.7% of cases, respectively. R1, R2 and L measurements between the EALs were not statistically different (P > 0.05). R1 and L correlated positively (r(2) = 0.817; P < 0.001). There were no significant differences in all measurements between vital and non-vital root canals (P > 0.05). There was no statistically significant difference between the EALs. There was a positive correlation between electronic and radiographic measurements when locating the AF.