Major Apical Foramen Research Articles

Comparative Evaluation of Accuracy of Two Apex Locators with Different Irrigants: An In-Vitro Study

Aim: The aim of this in-vitro study will be to evaluate and compare the accuracy of two apex locators in the presence of various irrigants. Methods and Material: The study will be conducted on 80 extracted straight, single-rooted permanent human teeth with mature apices. The teeth will be decoronated. Access cavity preparations will be done and working length will be established with 10 K file or 15 k-file into the canal until its tip emerged through the major apical foramen at ×10 magnification under a stereomicroscope. All the samples selected will be divided into four groups on the basis of irrigants used. Group 1 will be dry without irrigants, used as control, in Group 2 saline will be used as irrigant, in Group 3 sodium hypochlorite will be used as irrigant and in Group 4 chlorehexidine will be used as irrigant. Each group again will be subdivided into two groups on the basis of two different apex locators used (Root ZX Mini J. Morita) and CanalPro (Coltene). All the samples will be embedded in gelatin filled polyurethane bottles to simulate the periodontium. Statistical analysis used: Subsequently, the data will be statistically analysed using one-way analysis of variance (ANOVA) and paired t-test. Results: In this study, group 2 canal pro apex locator is accurate and sodium hypochlorite irrigant shows maximum variation. Conclusions: Canalpro showed accurate values than Root ZX and sodium hypochlorite showed more variations

Morphological changes of the apical foramen after enlargement: A scoping review of in vitro studies.

To outline the current evidence on root morphological changes after enlarging the apical foramen with NiTi instruments. A search was performed in the Virtual Health Library, PubMed, EMBASE, Scopus, Web of Science, Science Direct and SciELO databases, in addition to a manual search in Google Scholar, between January 2017 and October 2023. Articles published in English that describe in vitro studies investigating root morphological changes after instrumentation 1 mm beyond the major apical foramen were included. The quality of evidence in the included studies was also analyzed. The search retrieved 367 articles. Of these, four studies were eligible for data synthesis and analysis, all of them in vitro studies. Synthesis of the results of these in vitro studies showed a larger number of root morphological changes such as experimental dentinal microcraks in samples submitted to instrumentation beyond the apical foramen when compared to micro-CT images obtained before preparation. The in vitro studies analyzed in this scoping review indicate that instrumentation beyond the major foramen of the root canal, promotes morphological changes in this area and that the adoption of standardized methodologies would not only increase the accurate detection and characterization of these changes but also facilitate the application of these findings in clinical trials and patient care. Key words:Endodontics, apical morphology, root canal preparation.

Reprint of: The Effect of Mineral Trioxide Aggregate Obturation Levels on the Outcome of Endodontic Retreatment: An Observational Study

IntroductionNo clinical studies have examined the effect of mineral trioxide aggregate (MTA) obturation levels on the outcome of endodontic retreatment. This retrospective study examined treatment outcomes in three cohorts that compared overfilling, flush filling, and underfilling after orthograde retreatment using MTA. MethodsTwo hundred fifty patients with 264 teeth diagnosed with previously treated root canals and apical periodontitis retreated in a private endodontic practice were included. All teeth received MTA obturation and the extent of the final filling level was measured in relation to the major apical foramen. After 6-month follow-ups, all nonhealing cases were treated surgically. After 24- to 72-month reviews, the effect of preoperative lesion size and the degree of MTA obturation level were assessed. Multiple linear regression and time-to-event analysis using Stata 17 software (StataCorp LLC, College Station, TX) were used to evaluate the data. ResultsWithin the three cohorts, 99 out of 108 overfilled teeth (91.7%), 90 out of 103 flush fills (87.4%), and 10 out of 53 underfilled teeth (18.9%) healed and were successfully retreated without surgery at 48-months. When surgical outcomes were included, the combined healed proportion was 93.2%. Preoperative lesion size was found to be an important predictor for retreatment nonhealing. A 1-mm increase in lesion size at baseline resulted in an estimated 11% (95% CI 1.04, 1.18)–38% (95% CI 1.22, 1.58) increase in the risk of surgery. Compared to overfilling and flush filling, underfilling was associated with an approximately three-fold increase in requiring surgery and characterized by delayed healing. ConclusionMTA obturation is a viable retreatment option for teeth with nonhealing endodontic treatment. MTA overfills or flush fillings do not adversely affect healing outcomes. However, MTA underfilling increases the chances for nonhealing and surgical intervention.

Influence of different working lengths on the shaping ability of Reciproc Blue in the apical third and apical foramen

Aim: This study aimed to assess the shaping ability of Reciproc Blue in the apical third and apical foramen of moderately curved canals at different working lengths (WLs), by micro-computed tomography. Methods: Thirty-six mesial roots (mesiobuccal and mesiolingual canals) were included, each with 2 separate root canals and independent apical foramina, according to type IV of Vertucci’s classification of first and second mandibular molars. The canals were instrumented at three different WLs: G-1, 1mm short of the major apical foramen; G0, at the major apical foramen; G+1, 1mm beyond the major apical foramen. The groups were assessed for changes in root canal volume and untouched wall area in the apical third. Groups G0 and G+1 were also compared for percentage of untouched walls at the apical foramen. One-way ANOVA (post hoc Tukey test) and Student’s t-test adopted a 5% level of significance. Results: Root canal volumes (mm3) in the apical third were 22.86±10.46, 44.48±24.91, and 55.71±21.32 in G-1, G0 and G+1, respectively. G-1 volume following instrumentation increased significantly less than that of G0 or G+1 (P>.05); G0 did not differ from G+1. The percentage of untouched wall area in the apical third did not differ among the three groups (P>.05). G0 and G+1 did not differ regarding untouched walls in the major apical foramem walls. Conclusion: Extending the WL from 1mm short of the apical foramen to a point at and beyond the WL increases the apical third volume without increasing the prepared area. Untouched surface areas of the apical foramen were not modified by instrumentation at or beyond the foramen.

The Effect of Mineral Trioxide Aggregate Obturation Levels on the Outcome of Endodontic Retreatment: An Observational Study

IntroductionNo clinical studies have examined the effect of mineral trioxide aggregate (MTA) obturation levels on the outcome of endodontic retreatment. This retrospective study examined treatment outcomes in three cohorts that compared overfilling, flush filling, and underfilling after orthograde retreatment using MTA. MethodsTwo hundred fifty patients with 264 teeth diagnosed with previously treated root canals and apical periodontitis retreated in a private endodontic practice were included. All teeth received MTA obturation and the extent of the final filling level was measured in relation to the major apical foramen. After 6-month follow-ups, all nonhealing cases were treated surgically. After 24- to 72-month reviews, the effect of preoperative lesion size and the degree of MTA obturation level were assessed. Multiple linear regression and time-to-event analysis using Stata 17 software (StataCorp LLC, College Station, TX) were used to evaluate the data. ResultsWithin the three cohorts, 99 out of 108 overfilled teeth (91.7%), 90 out of 103 flush fills (87.4%), and 10 out of 53 underfilled teeth (18.9%) healed and were successfully retreated without surgery at 48-months. When surgical outcomes were included, the combined healed proportion was 93.2%. Preoperative lesion size was found to be an important predictor for retreatment nonhealing. A 1-mm increase in lesion size at baseline resulted in an estimated 11% (95% CI 1.04, 1.18)–38% (95% CI 1.22, 1.58) increase in the risk of surgery. Compared to overfilling and flush filling, underfilling was associated with an approximately three-fold increase in requiring surgery and characterized by delayed healing. ConclusionMTA obturation is a viable retreatment option for teeth with nonhealing endodontic treatment. MTA overfills or flush fillings do not adversely affect healing outcomes. However, MTA underfilling increases the chances for nonhealing and surgical intervention.

Correlation between the major apical foramen and readings from display’s numbers of two electronic apex locators: An ex vivo study

Objective: The aim of this study was to determine the correlation between the distance from the file tip to the apical foramen and the readings on displays of two Electronic Apex Locators. Methodology: 46 human teeth were accessed, and electronic measurements were obtained at the display levels: 2.0; 1.5; 1.0; 0.5 and “apex”, these electronic measurements were repeated. Results: At the 0.0 and 0.5 display numbers, there was an accurate detection of the apical foramen: 93.5% for the Root ZX II and 93.5% for the RomiApex A-15 (± 0.5 mm). Analysis of variance (ANOVA) revealed that the accuracies of the two devices did not differ (p>0.05). At 2.0, 1.5 and 1.0, the accuracy was low and there was a significant difference in the accuracy of booth devices (p=0.000). When evaluating repetition of measurements, there was a high level of reproducibility (the ICCs ranged between 1.000 and 0.992 for the Root ZX II and between 1.000 and 0.989 for the RomiApex A-15) in all evaluated display’s levels. Conclusions: Both devices displayed high accuracy and reproducibility at the 0.0 and 0.5 display numbers.

Comparative Evaluation of Dentinal Microcrack Formation before and after Root Canal Preparation Using Rotary, Reciprocating, and Adaptive Instruments at Different Working Lengths—A Micro–computed Tomographic Study

IntroductionThis study aimed to compare root dentinal microcrack formation after root canal shaping using rotary, reciprocating, and adaptive instruments at different working lengths using micro–computed tomographic imaging. MethodsOne hundred eighty extracted mature mandibular molar mesial roots with 2 separate canals were selected. The mesial roots were resected at the cementoenamel junction and randomly divided into 4 groups (n = 45) based on the nickel-titanium file system used: ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Gold (Dentsply Maillefer), Twisted File Adaptive (SybronEndo, Orange, CA), and Reciproc Blue (VDW, Munich, Germany). Each of the 4 groups were then subdivided into 3 groups (n = 15) depending on the working length used for root canal preparation (ie, instrumentation 1 mm short, flush, and 1 mm beyond the major apical foramen). The roots were imaged with micro–computed tomographic scanning before and after root canal preparation. The cross-sectional images generated were screened to detect the presence of new microcracks. ResultsThe ProTaper Universal system significantly increased the number of postinstrumentation microcracks at all working lengths (P ≤ .05). No significant increase (P > .05) in postinstrumentation microcracks was observed in the ProTaper Gold, Twisted File Adaptive, or Reciproc Blue groups. ConclusionsRotary instrumentation induced a higher number of dentinal microcracks compared with reciprocating and adaptive instruments. Instrumentation at different working lengths did not significantly influence the formation of dentinal microcracks.

A laboratory study of the accuracy of three electronic apex locators: influence of embedding media and radiographic assessment of the electronic apical limit.

To evaluate several factors that might interfere with the use of electronic root canal length measurement devices (ERCLMDs) in a laboratory setting, including two different embedding media (alginate and electroconductive gel), three different types of devices and the radiographic view on the assessment of the electronic readings. Thirty single-rooted extracted human mandibular premolars were selected. After access and canal pre-flaring, a size 10 K-file was inserted in the canal up to the major apical foramen under magnification (×10), and this length was recorded as the actual length (AL) of the canal. Teeth were mounted on a specific endodontic training kit platform (ProTrain). Two different embedding media (electroconductive gel and alginate) and three different ERCLMDs: Apex ID (SybronEndo, Glendora, CA, USA), CanalPro Apex Locator (Coltene-Endo, Cuyahoga Falls, OH, USA) and the Root ZX II (J. Morita, Tokyo, Japan), were tested. Following the measurement at the 0.5 mark of each ERCLMD using alginate, two periapical radiographs (bucco-lingual and proximal views) were taken. The difference between the electronic readings and the AL, as well as the distance from the file tip to the apex of the roots on the radiographs, was calculated. Data were analysed statistically (two-way anova, Tukey's and chi-squared tests) at 5% significance level. The incidence of over-extended readings was significantly greater (P<0.05) when using the ProTrain electroconductive gel, except for Root ZX II at the 0.5 mark. Root ZX, CanalPro and Apex ID had similar accuracy when the 0.0/APEX mark was used to locate the foramen. For the radiographic method, no difference was found between the devices or radiographic views. Compared with alginate, the conductive gel of the ProTrain kit negatively affected most of the electronic readings. The three evaluated ERCLMDs had similar accuracy in locating the apical foramen when using the mark 0.0/APEX and alginate as the embedding media. Although the ProTrain platform allows radiographs to be exposed in both bucco-lingual and proximal views, no difference was found between the views when evaluating the apical limit provided by the 0.5 mark in mandibular premolars embedded in alginate.

The use of micro-computed tomography to determine the accuracy of electronic working length with two apex locators.

This study evaluated the precision of electronic working length by microcomputed tomography using two electronic apex locators (EALs). Twenty single-rooted permanent teeth without caries or restorations were selected as the subject teeth. The positions of the minor apical constriction (AC) and major apical foramen (AF) were measured by electronic root canal length, and microcomputed tomography was performed with the file inserted and fixed in the root canal. All teeth were measured individually and independently by two operators. The Mann-Whitney U-test was used to statistically test the AC and AF values using two EALs; P < 0.05 was defined as statistically significant. This was 65.0% within 1.5 mm in the case of two EALs on AC. This was more than 90.0% within 1.0 mm in the case of two EALs on AF. Comparison of the differences between the respective AC and AF of the measurements obtained using the two EALs revealed no significant difference. The two EALs are devices that can greatly improve the accuracy of WL control.

Histopathological Investigation of Dental Pulp Reactions Related to Periodontitis.

Objective:Since the 1960s, there has been contradictory evidence regarding the association between periodontal pathology and the status of the pulp. The purpose of this study was to evaluate the histopathological changes of pulp tissue with severe periodontal disease, including vertical bone loss involving the major apical foramen, and compared them with the histological pulpal status of teeth with healthy periodontium.Methods:This case-controlled study included 35 intact teeth with severe periodontitis of hopeless prognosis (test group) and 35 teeth without periodontitis extracted for orthodontic reasons (control group). For each tooth, periodontal and endodontic parameters such as probing depth and pulpal vitality were recorded, and the pulp tissue was evaluated histologically. The data were analysed with a significance level of 0.05.Results:Vital pulp was observed in all specimens of both groups (P=1). Pulpal inflammation in the apical portion was observed in 81.71% of the severe periodontitis group, whereas all teeth in the control group demonstrated no signs of pulpal inflammation. Dystrophic calcification and pulp stones were observed in 7.5% of the periodontitis group and 5.7% of the healthy group (P>0.05). Pulp fibrosis was observed in 22.8% of the periodontitis group and 2.8% of the control group (P=0.012). Pulpal necrosis was not noted in either group. In the periodontitis group, internal resorption was present in 22.8% of cases (P=0.005) and external resorption was present in 80% of cases (P<0.001). In the control group, no internal or external resorption was observed in any of the specimens. No differences were noted in the study patients with regard to sex or age.Conclusion:Periodontal disease does not significantly affect pulp vitality and pulpal calcifications. However internal and/or external resorption was significantly different between the two groups as well as apical inflammation and pulp fibrosis.

Apically Extruded Debris following Programmed Over Instrumentation of Curved Canals with Three Nickel Titanium Rotary Instruments

Objectives This in vitro study aimed to compare the amount of mixed and dried debris extruded with three endodontic NiTi (nickel–titanium) systems at three levels beyond the major apical foramen. The null hypothesis is that there would be no differences between the different rotary systems in terms of apically extruded debris. Materials and Methods Forty-eight roots of human extracted molars with 20 to 40-degrees curvature were divided randomly into three groups ( n = 16) instrumented with ProTaper Next, BT RaCe, and WaveOne Gold, respectively. Instrumentation was performed at the major foramen and over instrumented 0.5 mm, 1.0 mm and 1.5 mm beyond. Irrigation was performed with sodium hypochlorite. Apically extruded debris was collected. Results Comparison of mixed extruded debris (solution/debris)and dried debris according to group and level of instrumentation showed that WaveOne Gold at the foramen and ProTaper Next beyond the foramen ( p < 0.0001) resulted in significantly less extruded debris than other files and within the four levels using repeated measures analysis of variance ( p < 0.0001b). Conclusions All systems exhibit extruded debris during instrumentation but in different amounts.

Quantitative Analysis of the Anatomy of Mesial Roots of Mandibular First Molars with Vertucci Type I Root Canal Configuration by Means of Micro-Computed Tomography

Aim: This study aimed to evaluate root canal morphology of Vertucci type I root canal configuration detected in mesial roots of mandibular first molar teeth using micro-computed tomography (Micro-CT).&#x0D; Methodology: Micro-CT datasets of 269 specimens were evaluated for the detection of specimens with Vertucci type I root canal configuration for further analysis. Major and minor diameter, area, perimeter and roundness of root canal cross-sections at the beginning and midline of each root thirds were measured and recorded. The presence of apical delta, accessory canals, and deviation of major apical foramen from anatomical apex were investigated. Data was analyzed using descriptive analysis, ANOVA-Tukey and Kruskal-Wallis H-Wilcoxon signed-rank tests.&#x0D; Results: Vertucci type I canal configuration was present in the 4.46% of the specimens. The specimens often showed accessory root canals (50%) and apical deltas (41,6%). From the visual analysis of the 3D and 2D images, significant differences were detected among coronal, middle and apical thirds of the specimens regarding major and minor diameter, area, perimeter and roundness (P &lt; 0.05).&#x0D; Conclusion: Three- and two-dimensional analyses of mesial roots with Vertucci type I canal configuration indicated that this type of configuration presents large buccolingual diameters with long oval shape and has isthmus at coronal and middle thirds. At the apical third the root canals often terminate in an oval cross sectional shape.&#x0D; &#x0D; How to cite this article: Keles A, Keskin C. Quantitative analysis of the anatomy of mesial roots of mandibular first molars with Vertucci type I root canal configuration by means of micro-computed tomography. Int Dent Res 2020;10(1):17-21. https://doi.org/10.5577/intdentres.2020.vol10.no1.4&#x0D; &#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Prevalence of major apical foramen mismatching the root apex in root canals of human permanent teeth

The periapical radiograph is used to determine the working length in endodontic treatment. However, this radiograph does not define the position of the major apical foramen. Objective: This ex vivo laboratorial study aims to determine the prevalence of the major apical foramen mismatching the root apex in human permanent teeth, because when present, this mismatch makes the radiographic method inaccurate for determining the working length. Material and methods: This study used 400 human permanent teeth: 100 incisors, 100 canines, 100 premolars, and 100 molars, totalizing 634 canals (Ethics Committee, Federal University of Ceará #263/10). The access and negotiation of the root canals were performed with K-type files #10 and #15 until the tip of the instrument were visible at the root foramen through 5-fold magnifying glass. Periapical radiographs were performed on bucco-lingual incidence for single-rooted teeth; the incidence angle was changed for multi-rooted teeth. The films were processed and then analyzed by three calibrated examiners (Kappa 80%). Descriptive statistics and chi-square test were used for analyzing of the results. Results: The prevalence of major apical foramens mismatching the root apex was 19.72% of the canals studied. The incisors showed the lowest prevalence (9%, p&lt;0.05) while the highest prevalence was seen in canine teeth (28%). Conclusion: According to the methodology applied, the prevalence of major apical foramens mismatching the root apex foramens make necessary an adjunct method for determining the working length, because it alone was not capable of determining the foramen position.

Influence of Root Canal Curvature on the Accuracy of Root ZX Electronic Foramen Locator: An In Vitro Study.

Introduction:The aim of this in vitro study was to evaluate the correlation between accuracy of Root ZX electronic foramen locator and root canal curvature. Methods and Materials:One hundred and ten extracted mandibular molars were selected. Access cavity was prepared and coronal enlargement of mesiobuccal canal was performed. A #10 Flexofile was inserted into the mesiobuccal canal, and a radiography was taken to measure the degree of curvature by Schneider's method. The actual working length (AWL) was defined by inserting the file until its tip could be observed at a place tangential to the major apical foramen and then 0.5 mm was subtracted from this measurement. For the electronic working length (EWL) measurement, the apical 3 or 4 mm of the root was embedded in alginate as the electrolyte material. The file was inserted into the root canal to the major foramen, until the APEX reading was shown on the electronic device and then pulled back until the visual display showed the 0.5-mm mark. The AWL was subtracted from the EWL to define the distance between the file tip and the point 0.5 mm coronal to the major apical foramen. Data were analyzed using the Pearson’s correlation coefficient. Results:The accuracy of Root ZX within ±0.1 mm and ±0.5 mm was 38.2% and 94.6%, respectively. There was no correlation between the distance from the EWL to the AWL and the degree of root canal curvature (r=0.097, P=0.317). Conclusion:Root canal curvature did not influence the accuracy of Root ZX foramen locator.

The influence of determining the working length with an apex locator on the amount of apically extruded debris following instrumentation with ProTaper Next and HyFlex CM

Aim: The amount of apically extruded debris caused by new nickel-titanium rotary systems after determination of the working length (WL) with an apex locator has not been investigated. To compare the amount of apically extruded debris with ProTaper Next (PTN) and HyFlex CM systems after determination of WL with/without an apex locator. Materials and Methods: Forty-eight extracted mandibular incisor teeth divided into four groups were used in this study. In Groups 1 and 2, a 10 K-file was progressed until it was just visible at the major apical foramen and WL was recorded as 1 mm short. In Groups 3 and 4, the WL was determined with the Root ZX (sensitivity of 0.1) using a 10 K-file. During the instrumentation, the PTN was used to X2 in groups 1 and 3, and the HyFlex CM was used to 25/.06 in groups 2 and 4. Distilled water was used as an irrigant. Debris was collected in tubes then stored in an incubator at 68°C for 5 days to evaporate the distilled water. The Eppendorf tubes, including the extruded debris, were weighed to obtain final weights. The amount of extruded debris was calculated by subtracting the weight of the empty tube from the weight of the dry tube. Data were analyzed by Kruskal–Wallis and Mann–Whitney U -test. Results: Less apically extruded debris was obtained in Group 3, with a significant difference compared to Group 1 and Group 2 ( P Conclusions: The usage of apex locator to determine the WL decreased the amount of apically extruded debris. In addition, PTN caused less apical debris extrusion after determination WL with/without apex locator.

A Stereomicroscopic Evaluation of Dentinal Cracks at Different Instrumentation Lengths by Using Different Rotary Files (ProTaper Universal, ProTaper Next, and HyFlex CM): An Ex Vivo Study.

Introduction. The aim of the present study was to evaluate the dentinal cracks after root canal preparation with rotary files: Gates Glidden, ProTaper Universal, ProTaper Next, and HyFlex CM at different instrumentation lengths. Methodology. Sixty-five mandibular premolars were mounted in the acrylic tube with simulated periodontal ligaments and the apex was exposed. The root canals were instrumented with different rotary files, namely, ProTaper Universal, ProTaper Next, and HyFlex CM, to the major apical foramen (AF), short AF, and beyond AF. The root apex was stained with 1% methylene blue dye and digital images of apical surface of every tooth were taken and development of dentinal defects was determined by using stereomicroscope. Multinomial logistic regression test was performed to identify influencing factors. Results. Instrumentation with rotary files terminated 2 mm short AF and did not cause any cracks. Significantly less cracks were seen when instrumentation with rotary files terminated 1 mm short apical foramen when compared with the instrumentation terminated at or beyond apical foramen (p < 0.05). Conclusion. ProTaper Universal rotary files caused more dentinal cracks than ProTaper Next and HyFlex CM. Instrumentation short AF reduced the risk of dentinal defects.

The Validity of Cone-beam Computed Tomography in Measuring Root Canal Length Using a Gold Standard

IntroductionThe distance between a coronal reference point and the major apical foramen is important for working length determination. The aim of this in vitro study was to determine the accuracy of root canal length measurements performed with cone-beam computed tomographic (CBCT) scans using a gold standard. MethodsA total of 162 teeth (198 root canals) in 16 dry human dentulous mandibles were scanned using a 3DX-Accuitomo CBCT scanner (Morita 3DX; J Morita Mfg Corp, Kyoto, Japan). The root canal length was measured with CBCT data. All teeth were extracted atraumatically and endodontically accessed; the root canal length was measured blindly using a #10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) and served as the gold standard. ResultsThe mean absolute difference of the CBCT-based root canal length from the gold standard was 0.46 mm (95% confidence interval, 0.41–0.50 mm). Only in 9 of 198 (4.5%) roots did the difference between the CBCT-based root canal length and the gold standard exceed 1 mm. ConclusionsCBCT-based root canal length measurements are accurate and reliable when compared with a gold standard.

Microcomputed tomography analysis of the root canal morphology of single‐rooted mandibular canines

To investigate the anatomy of single-rooted mandibular canine teeth using microcomputed tomography (μCT). One hundred straight single-rooted human mandibular canines were selected from a pool of extracted teeth and evaluated using μCT. The anatomy of each tooth (length of the roots, presence of accessory canals and apical deltas, position and major diameter of the apical foramen and distance between anatomical landmarks) as well as the two- and three-dimensional morphological aspects of the canal (area, perimeter, form factor, roundness, major and minor diameter, volume, surface area and structure model index) were evaluated. The results of the morphological analysis in each canal third were compared statistically using Friedman's test (α=0.05). The length of the roots ranged from 12.53 to 18.08mm. Thirty-one specimens had no accessory canals. The location of the apical foramen varied considerably. The mean distance from the root apex to the major apical foramen was 0.27±0.25mm, and the major diameter of the major apical foramen ranged from 0.16 to 0.72mm. Mean major and minor diameters of the canal 1mm short of the foramen were 0.43 and 0.31mm, respectively. Overall, the mean area, perimeter, form factor, roundness, major and minor diameters, volume, surface area and structure model index (SMI) were 0.85±0.31mm(2) , 3.69±0.88mm, 0.70±0.09, 0.59±0.11, 1.36±0.36mm and 0.72±0.14mm, 13.33±4.98mm(3) , 63.5±16.4mm(2) and 3.35±0.64, respectively, with significant statistical difference between thirds (P<0.05). The anatomy and morphology of the root canal of single-rooted canines varied widely in different levels of the root.

Incidence of Apical Root Cracks and Apical Dentinal Detachments after Canal Preparation with Hand and Rotary Files at Different Instrumentation Lengths

IntroductionThe aim of this study was to compare the incidence of apical root cracks and dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths. MethodsTwo hundred forty mandibular incisors were mounted in resin blocks with simulated periodontal ligaments, and the apex was exposed. The root canals were instrumented with rotary and hand files, namely K3, ProTaper, and nickel-titanium Flex K files to the major apical foramen (AF), short AF, or beyond AF. Digital images of the apical surface of every tooth were taken during the apical enlargement at each file change. Development of dentinal defects was determined by comparing these images with the baseline image. Multinomial logistic regression test was performed to identify influencing factors. ResultsApical crack developed in 1 of 80 teeth (1.3%) with hand files and 31 of 160 teeth (19.4%) with rotary files. Apical dentinal detachment developed in 2 of 80 teeth (2.5%) with hand files and 35 of 160 teeth (21.9%) with rotary files. Instrumentation with rotary files terminated 2 mm short of AF and did not cause any cracks. Significantly less cracks and detachments occurred when instrumentation with rotary files was terminated short of AF, as compared with that terminated at or beyond AF (P < .05). The AF deviated from the anatomic apex in 128 of 240 teeth (53%). Significantly more apical dentinal detachments appeared in teeth with a deviated AF (P = .033). ConclusionsRotary instruments caused more dentinal defects than hand instruments; instrumentation short of AF reduced the risk of dentinal defects.

Microcomputed tomography analysis of mesiobuccal orifices and major apical foramen in first maxillary molars.

Objective:Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots.Materials and Methods: Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed.Results:The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex. Conclusions:Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex.Clinical Relevance:These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system.