Anatomic Apex Research Articles

Residual dentin thickness in mesial roots of mandibular molars prepared with Lightspeed rotary instruments and Gates-Glidden reamers.

We sought to measure the residual dentin thickness (RDT) in the mesial roots of mandibular molars after instrumentation with Lightspeed and Gates-Glidden rotary instruments. Study design Thirty extracted, untreated human mesial roots of mandibular molars were separated from the distal roots and embedded in clear polyester resin. The roots were cut horizontally at 1, 4, and 7 mm short of the anatomic apex. The diameter of each mesiobuccal canal was measured by using a stereo measuring microscope at each level in the buccolingual and mesiodistal directions. The dentin thickness was measured in each level in the mesial, distal, buccal, and lingual directions. Sections were reassembled with a muffle. The canals were enlarged to the working length with Lightspeed rotary instruments, of which the average size used was a No. 50 file. The coronal third was flared with No. 2 Gates-Glidden reamers. Slices were separated again, and the RDT and canal diameters were measured. The minimal measured RDT after instrumentation at the 1-, 4-, and 7-mm levels was 0.70 +/- 0.28 mm, 1.04 +/- 0.18 mm, and 1.09 +/- 0.19 mm, respectively. The average diameter of the canals after instrumentation at the 1-, 4-, and 7-mm levels was 0.50 +/- 0.04 mm, 0.52 +/- 0.05 mm, and 0.74 +/- 0.08 mm, respectively. The canal diameter did not exceed one third of the root diameter at all levels. Root canal preparation of mandibular mesial roots with Lightspeed instruments to No. 50 in the apical third and Gates-Glidden reamers to No. 2 in the coronal third does not significantly decrease the RDT.

Analysis of temperature rise on the root surface during continuous wave of condensation technique

This study was conducted to evaluate the temperature rise on the root surface while the root canal is being obturated using continuous wave of condensation technique. Maxillary central incisor was prepared for repeated canal obturation. Ten thermocouples (Omega Engineering Inc., Stanford, USA) were placed at 1 mm increment from the anatomical root apex. The real temperature of Buchanan plugger was recorded before insertion into the root canal. The root canal was obturated with continuous wave of condensation technique as described by Buchanan and the root surface temperature was recorded during obturation at temperature settings of System B HeatSource (Model 1005, Analytic technologies, Redmond, WA, USA). After completion of the temperature recording, the dentinal-cementum thickness at each sites was measured. The data were analyzed using one-way ANOVA followed by Scheffe's test and linear regression test. The results were as follows. 1. When the temperature was set at on the digital display of System B HeatSource, the real temperature of the plugger at the 1mm point from the tip revealed respectively. 2. The position of 8 mm from the anatomical apex showed the highest temperature increase at each temperature settings and it was significantly higher than those of other positions (p setting respectively. These results suggest that it be relatively kind to the supporting tissues of the root that the root canal is obturated using continuous wave of condensation technique at temperature settings on digital temperature display of System B HeatSource.

The Effect of an Apex Locator on Exposure to Radiation During Endodontic Therapy

The objective of this study was to investigate whether the use of an electronic apex locator results in a reduction in X-ray exposure during endodontic therapy. Fifty, sound, extracted, single-rooted canine and incisor teeth were selected and randomly divided into two groups (A and B) of 25 teeth. The working length was determined radiographically with (group B) and without (group A) adjunctive use of an apex locator by one operator. After working length determination, the teeth were sectioned and the actual working length measured for comparison. For group A, 14 retake radiographs were required to determine the working length, whereas group B required no retake radiographs; this difference was highly significant (p < 0.001). The electronic apex locator was extremely accurate in locating the apical foramen with all teeth tested within 0.5 mm of the anatomical apex and 11 (44%) teeth at the apical foramen. In contrast, 15 (60%) teeth tested using radiographs alone were within 0.5 mm of the anatomical apex and only 4 (16%) teeth were actually at the anatomical apex. It was concluded that using an electronic apex locator as an aid to endodontic therapy could potentially reduce the number of diagnostic radiographs required for working length determination. Location of the apical foramen using a combination of an electronic apex locator and radiographs to determine working length is more accurate than using radiographs alone.

Measurement of the Distance Between the Minor Foramen and the Anatomic Apex by Digital and Conventional Radiography

The purpose of this study was to determine the distance between the minor foramen and the anatomic apex from digital and conventional radiographs. Thirty permanent single-canal teeth with mature root apex were used. After access preparation, a K-file was inserted into the canal until the tip of the file was just seen at the minor foramen under a x40 stereomicroscope. The file was fixed in the canal by filling the access with composite resin. The teeth with files in the canals were radiographed using a Schick CDR digital system and conventional radiography with E-speed film. For digital radiographs, the distance between the file tip and the center of radiographic apex was directly measured from the computer screen by using Schick CDR measurement software. For conventional radiographs, the distance was measured under a stereomicroscope at a magnification of x10 with a calibrated millimeter ruler. The mean distance was 0.494 mm measured from conventional radiographs and 0.594 mm from digital radiographs. These results agree with the current conception that endodontic working length should terminate 1 mm from the radiographic apex. There was a significant difference between the measurements on digital radiographs and those on conventional radiographs (p < 0.05, paired t test). However, the 0.1-mm difference has no clinical significance, because clinically, the working length is generally measured to the nearest 0.5 mm.

Evaluation of the anatomical alterations of lower molars mesial root’s apical third

The anatomical apex of the mesial root of the lower molars presents a morphological complexity related to the number and shape of the root canals as well as of the apical foramen and isthmus presence. The knowledge of the complexity of the endodontic system of the molar root area is essencial to select more carefully the best instrumentation and obturation technique, to obtain a more successful endodontic therapy.

Cecal apical changes with appendicitis: diagnosing appendicitis when the appendix is borderline abnormal or not seen.

In most cases, CT of appendicitis shows a distended appendix with periappendiceal inflammation. A distended appendix, however, is not always visualized. In these patients, identifying changes at the anatomic cecal apex can secure a diagnosis of appendicitis. Cecal apical changes with appendicitis include focal cecal apical thickening, the arrowhead sign, and the cecal bar. This pictorial essay describes and illustrates the spectrum of CT appearances of cecal apical changes that can be seen with appendicitis.

Two canals in mesiobuccal roots of maxillary molars

The purpose of this study was to examine extracted root canal treated maxillary molars cleared for: (i) the presence of a mesiopalatal (MP) canal in both first and second molars, (ii) the extension of MP canal from the pulp to the apical area, and (iii) the incidence of two foramina in the MB root. Seventy-two extracted maxillary molars (42 first and 30 second molars) were root canal treated by graduate students. The mesiobuccal (MB) roots of these samples were rendered transparent using a clearing technique. The results demonstrated that 52.3% of first and 40% of second molars had two canals obturated in the MB root. After clearing the same roots, the presence of MP canals rose to 80.9% and 66.6%, respectively. The MP canals were root canal treated as far as the foramen in 35.2% of first and 35% of second molars. However, after making them transparent, 91.1% and 90% showed the presence of this canal to the anatomical apex. The MB roots of the root canal treated first molars showed the presence of two foramina in 47% of cases but in 88.2% after clearing. The second molars showed 50% and 70%, respectively. The differences between root canal treated teeth before and after clearing were significantly different in almost all comparisons in both first and second molars. The only exception was when the presence of two foramina was compared before and after the clearing process in second molars (McNemar test P < 0.05).

Examination of external apical root resorption with scanning electron microscopy

Objective External apical root resorption may be evident histologically but not visible radiographically until it is advanced. If working length is determined without considering this resorption, overinstrumentation or overfilling may occur. This study used scanning electron microscopy to examine the appearance and to compare the incidence of external apical root resorption in 40 teeth with differing pulpal and periapical diagnoses. Study design After extraction, 46 roots were sectioned horizontally 6 mm from the anatomic apex and prepared for scanning electron microscopy examination. Photomicrographs were scored by two blinded independent examiners. Apical resorption was categorized as: none, partial, or complete. Presence or absence of a funneling appearance of the resorption was also recorded. Results Kruskal Wallis showed a significant difference in resorption between groups; teeth with irreversible pulpitis/normal periapex had the least resorption. Duncan's multiple range test found radiographic apical lesions to have more resorption than those without lesions; teeth with necrotic pulps had more resorption than those with vital pulps. Conclusions Pulp necrosis with radiolucent apical pathosis is more likely to demonstrate resorption.

Morphologic criteria for root canal treatment of primary molars undergoing resorption

The endodontic anatomy of primary molars is difficult to predict because of the balance of resorption and hard tissue deposition. In particular, the resorption causes perforating lacunae across the wall of the root, even at the furcation level, and modifies shape, dimension and position of endodontic apex. The phenomenon can be so deep as to compromise endodontic therapy. The first aim of the study was to verify if reliable criteria can be found for treatability in primary molars undergoing resorption, i.e. if it is possible to predict if perforating lacunae are present or not. The second aim of the study was to verify if other informations needed for endodontic treatment, as shape, dimension and location of the apex, and curvature of the root canal can be predicted. For the study, 80 extracted primary molars, 75 of which pulpally involved by caries, were selected. The treatability was evaluated in term of root length, root shape, dimension and shape of endodontic apex, age of the patient and X-ray index of resorption. The association between variables was performed by multiple correspondence analysis. The results suggested that root length was the most reliable criterion of the integrity of the root. The borderline of treatability was at the length of 4 mm. The position of endodontic apex related to anatomical apex, and the lingual related to the buccal root length were analyzed by linear regression analysis. The canal length was often similar to the root length (i.e. the endo and anatomical apices were very close) in lower and upper molars. However, in lower molars, if two or more canals were present in the same root, a discrepancy was observed between buccal and lingual root length. This finding was constant in first lower molars. In addition regression analysis provided a linear function between the lengths of the buccal and lingual side of the same root in lower molars. Its coefficient b was 0.73.

Sealing ability of thermoplasticized gutta-percha fill techniques as assessed by a new method of determining apical leakage

One hundred fifty-nine extracted single-rooted maxillary human teeth were instrumented and randomly divided into nine groups of 17 teeth each and 6 control teeth. Experimental groups were obturated with Thermafil, Obtura II, Ultrafil Regular Set gutta-percha, and Ultrafil Firm Set gutta-percha, each with or without root canal sealer. A control group was obturated using the lateral condensation technique and sealer. Teeth were immersed in a resorcinol-formaldehyde resin for 5 days at 4 degrees C, and the resin was allowed to polymerize completely for 4 days at room temperature. Teeth were then sectioned horizontally at 1.5, 2.5, and 3.5 mm from the anatomical apex, and examined under a stereomicroscope at x25 magnification. The resin filled the spaces in the gap between the canal wall and the gutta-percha and this was measured at each of the three levels. The ratio of the area of the resin to the total area of the canal was obtained as the mean leakage area. The results showed no significant difference in the mean leakage area at the same level for the different obturation materials. However, the leakage was significantly less for all materials when root canal sealer was used.

Study of the apices of human permanent teeth with the use of a scanning electron microscope

The apical region of the roots of 38 maxillary incisors, 25 mandibular incisors, 29 maxillary second premolars, 92 mandibular first and second premolars, 12 maxillary first molars, and 17 mandibular first molars were prepared and studied with the use of a scanning electron microscope. The number and size of the main apical foramina, their distance from the anatomic apex, and the existence and size of accessory foramina were recorded, summarized, and statistically analyzed. More than one main foramen was observed in all groups except for the palatal root of maxillary molars and the distal root of mandibular molars. Accessory foramina were also observed in all groups of teeth. The distal roots of mandibular molars had the largest size main foramen (mean value, 392 μm), whereas the maxillary premolars had the largest accessory foramina (mean value, 53.4 μm) and the most complicated apical morphologic makeup. The distance of the main foramen from the anatomic apex never exceeded 1 mm. The highest values were observed at the mandibular incisors (978 μm), the distal root of mandibular molars (818 μm), and the upper premolars (816 μm). All values showed satisfactory fitting to normal distribution.

An experimental study of the sealing ability of a dentinal apical plug treated with bonding agent

The purpose of this study was to evaluate the sealing ability of a dentinal apical plug treated with a bonding agent. Ninety human lower premolars were used. The teeth were divided into three groups. in groups 1 and 2, to prepare an apical isthmus of 1 mm in length, the first apical seat was prepared with a #45 K file 1 mm short of the anatomical apex and with a #60 K file 2 mm short for the second apical seat. Dry dentin fillings were packed in the apical isthmus with a #60 K file. In group 1, the root canal was obturated with gutta-percha and Canals root canal sealer by the lateral condensation method. In group 2, following an application of the bonding agent to the plug, the root canal was obturated in the same way. In group 3 (control), a single apical seat was prepared with a #60 K file 1 mm short of the apex and the root canal was obturated similarly. The teeth of three groups were immersed in a 1% methylene blue solution for 1, 2, and 4 wk. Dye penetration depth from the apical foramen was determined. Group 2 showed no leakage after 4 wk. Groups 1 and 3 showed dye penetration into the root canal, and in these two groups dye penetration increased with time.

Leakage evaluation with and without vacuum of two gutta-percha fill techniques

Two sets of 30 roots were obturated either with lateral condensation or a halothane dip technique. Fifteen roots from each group were immersed in India ink with vacuum and 15 without vacuum. Each root was coated with nail polish and wax, leaving only its apical end open for ink penetration. The roots were cleared and three linear measurements were made: distance of ink penetration coronal to the gutta-percha apical tip; distance from the gutta-percha tip to major foramen; and distance from the major foramen to anatomical apex. The average length of ink penetration coronal to the apical extension of the gutta-percha for the lateral condensation groups combined was 1.33 mm and for the halothane groups combined was 2.15 mm. There was no significant difference between vacuumed and not vacuumed for degree of ink penetration. The gutta-percha of the halothane-dipped groups advanced significantly closer to the foramen than the lateral condensation groups (0.38 mm versus 0.65 mm).

Root canal configuration of the mandibular first premolar

One hundred six human mandibular left and right first premolars, previously extracted due to nonrestorable caries, periodontal disease, or orthodontic reasons, were sectioned perpendicular to the long axis of the root starting at the cementoenamel junction. Three-millimeter sections were made with an ultrathin separating disc to the level of the anatomical apex. After 1 day in 5.25% NaOCl, each section was rinsed in phosphate-buffered saline, evaluated with a stereomicroscope, and photographed. The slides were projected and the shape of the canal, incidence of multiple canals, level of bifurcation, and any other variant anatomy were recorded. Seventy-six percent of the premolars demonstrated Type I canals and 24% contained Type IV. The shape of the canals was predominantly oval or round. An interesting finding was the number of C-shaped canals which were associated predominantly with Type IV canal systems. This occurred in 14% of the roots.

An SEM investigation of the mesiolingual canal in human maxillary first and second molars

The mesiolingual orifices of 21 maxillary first molars and 37 maxillary second molars were examined with the scanning electron microscope. The mesiobuccal roots of these teeth were also typed by means of a clearing technique. The results demonstrated that 90% of first molars and 70% of second molars had two canals in the mesiobuccal root. Type 3 canal systems occurred in 33% of first molars and 35% of second molars. Eighty-one percent of first molars and 59% of second molars had a separate mesiolingual canal orifice. The mean diameter of the mesiolingual orifice was 0.49 mm in first molars and 0.42 mm in second molars. The mean distance of the mesiolingual orifice from the mesiobuccal orifice was 2.31 mm in first molars and 2.06 mm in second molars. In type 3 roots, the average distance of the mesiolingual foramen to the anatomic apex was 2.0 mm for first molars and 1.45 mm for second molars.

An anatomical study of the position of the mesial roots of mandibular molars

In order to determine the position of the anatomical apex of the mesial roots of the first and second molars, the horizontal distance from the outer surface of the buccal cortical plate to the apex and the vertical distance from the superior border of the neurovascular bundle to the apex were examined in 33 human cadaver mandible halves. The vertical distances were compared with measurements taken from periapical radiographs between the apex of each mesial root and the superior border of the mandibular canal prior to sectioning. The means of the horizontal buccal distances of the second molar were found to be significantly greater than those of the first molar. The means of the vertical distances of the second molar were found to be significantly less than those of the first molar. A high correlation was found between the vertical anatomic and radiographic measurements. In the majority of the sections, the neurovascular bundle was found in the lingual half of the mandible.

An evaluation of the apex locator endocater

The purpose of this study was to relate the relationship of the apical constriction to the anatomical apex and to determine the ability of the Endocater (Hygenic Corp., Akron, OH), using commercially bonded coated probes to locate the position of the apical constriction, in permanent teeth that were intact and had not been subjected to previous endodontic manipulation. Using local anesthesia and rubber dam isolation, conventional access cavities were prepared at ultra high speed with water coolant in teeth treatment planned for extraction. The Endocater was used to determine the working length. The probes were sealed in place with autopolymerizing composite resin and the teeth extracted. The teeth were sectioned buccolingually, and the position of the probe in relation to the anatomical apex and apical constriction was measured with the use of an ocular microscope. In 17.1% of the canals, the probes bound in the coronal portion of the canals and would not reach the apical portion of the root. In those teeth in which the probes reached the apical portion of the root, the Endocater was able to locate the apical constriction within 0.5 mm in 93.4% of the canals.

Stereomicroscopic evaluation of canal shape following hand, sonic, and ultrasonic instrumentation

This study evaluated the root canal shape after using sonic, ultrasonic, and hand instrumentation on the mesial canals of extracted human mandibular first and second molars. One-hundred and five mesial roots were randomly divided into six experimental groups and one untreated control group of 15 roots each. The following instrumentation techniques were evaluated in the experimental groups: hand instrumentation with K-Flex files, sonic instrumentation with the Endostar 5, sonic instrumentation with the Sonic Air MM 3000, and ultrasonic instrumentation with the Cavi-Endo unit. Each technique was directly compared with each other. The mesial roots were instrumented alternating the techniques between the buccal and lingual canals in each group so that a direct comparison could be made. All canals were instrumented to a size corresponding to a #30 K-Flex file 1 mm from the anatomical apex. The roots were then sectioned perpendicular to the long axis so the apical and middle thirds could be evaluated with the stereomicroscope for canal shape. The control group was sectioned and examined without instrumentation. A significantly more regular shape was obtained at both levels with hand instrumentation than was obtained with either sonic or ultrasonic techniques. The comparisons between the sonic and ultrasonic techniques showed significantly better shapes were obtained with the Sonic Air MM 3000 instrument.

The cardiac apex and its superficial blood supply.

The cardiac apex was defined and 3 types were presented: the anatomical apex, the base of which was established at the incisura apicis cordis; the amplified anatomical apex, twice the volume of the preceding; and the geometric apex, the distal third of the ventricles. These types of cardiac apex were studied in connection with the superficial branches of the coronary arteries at their level. The investigation was conducted on 81 normal hearts (56 males and 25 females) of 60 Caucasian and 21 non-Caucasian individuals. The arteries were injected with colored gelatine mixed with a radiopaque substance. The number of branches decreased from the geometric (the largest type) to the anatomical apex (the smallest): 27 on the surface of the geometric apex, 14 on the surface of the amplified anatomical apex, and 7 on the surface of the anatomical apex. The sternocostal aspect had a higher number of superficial branches than the diaphragmatic aspect in all types of cardiac apex. Sexual differences were found in the incidence of the r posterior ventriculi sinistri intermedius on the amplified anatomical apex as it was more frequent in females than in males. In the geometric apex there were 3 branches also more frequent in females: r anterior ventriculi sinistri inferior, r posterior ventriculi sinistri lateralis I, and r posterior ventriculi sinistri lateralis IV.

An in vitro model for evaluation of electronic rootcanal length measuring devices

An experimental model was developed to evaluatethe accuracy of three apex locators. The experimental assembly consisted of a polystyrene tube containing 0.2 mg of agar in 100 ml of phosphatebuffered saline. This solution completely surrounded the roots of the teeth tested, as the periodontal ligament does in vivo. A file was introduced into the root canal space until the device tested indicated that the apical foramen had been reached. A control group in which the working lengths were established 1.0-mm short of the radiographic apex was used. As a group, the devices were able to locate the apical foramen at a mean distance of 0.223 mm from the anatomical apex. No significant difference was found between the control group and the different devices in their ability to accurately locate the apical foramen. This study indicates that apex locators are very accurate in determining the location of the apical foramen. In addition, the experimental model can serve as a teaching aid. An experimental model was developed to evaluatethe accuracy of three apex locators. The experimental assembly consisted of a polystyrene tube containing 0.2 mg of agar in 100 ml of phosphatebuffered saline. This solution completely surrounded the roots of the teeth tested, as the periodontal ligament does in vivo. A file was introduced into the root canal space until the device tested indicated that the apical foramen had been reached. A control group in which the working lengths were established 1.0-mm short of the radiographic apex was used. As a group, the devices were able to locate the apical foramen at a mean distance of 0.223 mm from the anatomical apex. No significant difference was found between the control group and the different devices in their ability to accurately locate the apical foramen. This study indicates that apex locators are very accurate in determining the location of the apical foramen. In addition, the experimental model can serve as a teaching aid.