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

Introduction

The 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.

Methods

A 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.

Results

The 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.

Conclusions

CBCT-based root canal length measurements are accurate and reliable when compared with a gold standard.     

Analysis of C-shaped Canals by Panoramic Radiography and Cone-beam Computed Tomography: Root-type Specificity by Longitudinal Distribution

Introduction

The purpose of this study was to document the characteristics of C-shaped canal systems in permanent mandibular second molars using a combination of orthopantomogram (OPT) and cross-sectional cone-beam computed tomographic (CBCT) imaging.

Methods

Two hundred participants (94 men and 106 women, mean age = 35 years) who underwent both routine CBCT and OPT examinations were enrolled. One endodontist and 1 oral radiologist examined the images of 339 mandibular second molars and described the radiographic features of C-shaped canals from OPT images as confirmed by CBCT imaging. Root morphology was classified as nonfused (NFRI–II) or fused (FRI–III) based on OPT images. Cross-sectional root canal configurations (C1–C5) were identified from CBCT imaging at 3 different levels (coronal, middle, and apical). Frequency distributions of root morphology and root canal configurations were compared at each level, and interobserver reliability was tested using the Cohen kappa test.

Results

Of the 339 teeth, 29 (8.6 %) had C-shaped root canal systems. Most of the root canals were NFR type (86%); only 2% had C-shaped root canals (all NFRII). In the FR category, 23 teeth with C-shaped canals were equally distributed between the FRI and FRII subtypes. Interobserver agreement was almost perfect (κ = 0.89 and κ = 0.91; right and left second molars, respectively). Per CBCT imaging, the most common configuration was C3 at all levels; no C5 case was detected.

Conclusions

OPT usage can assist in recognizing and diagnosing C-shaped root canal systems. Radicular fusion or proximity is a characteristic feature of C-shaped canal systems. However, nonfused root appearances should also be considered suspicious.     

A Rare Root Canal Configuration of Bilateral Maxillary First Molar with 7 Root Canals Diagnosed Using Cone-beam Computed Tomographic Scanning: A Case Report

Introduction

The complexity of the root canal system of maxillary molars presents a constant challenge in the diagnosis and treatment of these teeth. This case report describes the importance of a surgical operating microscope and cone-beam computed tomographic (CBCT) imaging.

Methods

Root canal treatment of a left maxillary first molar with 3 roots and 7 canals was successfully performed. Seven canals were identified with the help of a surgical operating microscope and CBCT imaging. CBCT images also confirmed the 3 roots and 7 canals in the right maxillary first molar.

Results

CBCT images confirmed a type IV canal pattern in the distal and palatal root, whereas the mesial root had a type VIII canal pattern.

Conclusions

The use of a surgical operating microscope and CBCT imaging helps the clinician to diagnose unusual anatomy of a tooth and facilitate successful endodontic treatment.     

Precision of Endodontic Working Length Measurements: A Pilot Investigation Comparing Cone-Beam Computed Tomography Scanning with Standard Measurement Techniques

Introduction

The objective of this pilot investigation was to evaluate the utility and precision of already existing limited cone-beam computed tomography (CBCT) scans in measuring the endodontic working length, and to compare it with standard clinical procedures.

Methods

Three patients referred to the department received limited CBCT scans for diagnostics and preoperative treatment planning of cystic jawbone pathologies. Part of the therapy consisted of root canal treatments before surgical enucleation of the lesion. For the determination of the working length, the root canal length was measured with an electronic apex locator (EAL) by the endodontist. This measurement was compared with the root canal length as measured on the respective CBCT scans by an examiner not involved in the endodontic treatment. The interrater agreement between the two examiners was analyzed to determine the feasibility of this technique.

Results

In the three included patients, 9 teeth with a total of 10 root canals were treated. For these canals, a strong correlation was found between the endodontic working length as measured in the CBCT images and the EAL measurements (Pearson correlation coefficient ranging from 0.904 to 0.968).

Conclusions

Based on the present findings, an already existing CBCT scan of teeth to be endodontically treated can be useful to determine the endodontic working length in combination with clinical measurements such as the EAL. Future prospective studies should evaluate if and when intraoral radiography for measuring the length of root canals can be avoided when CBCT images are available.     

Evaluation of Root Canal Configuration of Maxillary Molars in a Brazilian Population Using Cone-beam Computed Tomographic Imaging: An In Vivo Study

Introduction

The aim of this study was to analyze and characterize root canal morphology of maxillary molars of the Brazilian population using cone-beam computed tomographic (CBCT) imaging.

Methods

Patients referred for a CBCT radiographic examination for accurate diagnosis and treatment planning were enrolled in the study. A total of 620 healthy, untreated, fully developed maxillary first and second molars were included (314 first molars and 306 second molars). The following observations were recorded: (1) number of roots and their morphology, (2) number of canals per root, (3) fused roots, and (4) primary variations in the morphology of the root canal systems.

Results

First and second molars showed a higher prevalence of 3 separate roots, mesiobuccal, distobuccal, and palatal, with 1 canal in each root (52.87% and 45.09%, respectively). Two canals in the mesiobuccal roots represented 42.63% of teeth, whereas mesiobuccal roots of second molars presented 2 canals in 34.32%. The most common anatomic variation in the maxillary first molar was related to the root canal configuration of the mesiobuccal root, whereas the root canal system of the maxillary second molar teeth showed more anatomic variables.

Conclusions

Mesiobuccal roots of maxillary molar teeth had more variation in their canal system than the distobuccal or palatal roots. The root canal configuration of the maxillary second molars was more variable than the first molars in a Brazilian population. CBCT imaging is a clinically useful tool for endodontic diagnosis and treatment planning.     

Detection of Various Anatomic Patterns of Root Canals in Mandibular Incisors Using Digital Periapical Radiography, 3 Cone-beam Computed Tomographic Scanners,and Micro–Computed Tomographic Imaging

Introduction

The purpose of this study was to compare the accuracy of digital periapical (PA) radiography and 3 cone-beam computed tomographic (CBCT) scanners in the identification of various internal anatomic patterns in mandibular incisors.

Methods

Forty mandibular incisors were scanned using micro–computed tomographic imaging as the gold standard to establish the internal anatomic pattern. The number of root canals and internal patterns were classified into type I (single canal, n = 12), type Ia (single oval canal, n = 12), and type III (2 canals, n = 16). The teeth were placed in a human mandible, and digital PA radiography and 3 CBCT scans (Kodak 9000 3D [Carestream Health, Rochester, NY], Veraviewepocs 3De [J Morita MFG Corp, Kyoto, Japan], NewTom 5G [QR Srl, Verona, Italy]) were performed. Two blinded examiners classified each tooth's anatomic pattern, which were then compared with the micro–computed tomographic determinations.

Results

Considering type I and type Ia, which both presented with 1 root canal, there was a high degree of accuracy for all methods used (P > .05). The same result was found for type III. When identifying the shape of single canals (type I), CBCT imaging was more accurate compared with PA radiography. Concerning oval canals (type Ia), there was a significant difference between PA radiography and NewTom CBCT (PA radiography = 44%, NewTom = 88%). However, there were no significant differences between the 3 CBCT units.

Conclusions

Double-exposure digital PA radiography for mandibular incisors is sufficient for the identification of the number of root canals. All CBCT devices showed improved accuracy in the identification of single root canal anatomy when a narrow canal was present. However, the identification of oval canals was improved only with the NewTom CBCT device.     

Symmetry of Root and Root Canal Morphology of Maxillary and Mandibular Molars in a White Population: A Cone-beam Computed Tomography Study In Vivo

Introduction

The aim of the present study was to use cone-beam computed tomography (CBCT) to analyze root canal anatomy and symmetry of maxillary and mandibular first and second molar teeth of a white population.

Methods

A total of 201 patients who required CBCT examinations as part of their dental diagnosis and treatment were enrolled in the present study. Overall, 596 healthy, untreated, well-developed maxillary and mandibular molar teeth (161 maxillary first molars, 157 maxillary second molars, 117 mandibular first molars, and 161 mandibular second molars) were examined by CBCT to establish the symmetry in root and canal anatomy between right and left sides in the same patient by evaluating the number of roots and root canals and the root canal configuration.

Results

Three separate roots with 3 separate canals was the normal anatomy of maxillary first and second molars. Most mandibular first and second molars had 2 separate roots, and the majority had 3 canals. In the present study, first molars, both maxillary and mandibular, exhibited greater asymmetry than the second molars. Maxillary first molars were found to be symmetrical in 71.1% of patients, whereas maxillary second molars were symmetrical in 79.6%. The remaining 28.9% and 20.4% of patients, respectively, showed asymmetry. Around 30% of the mandibular first molars and 20% of the mandibular second molars showed asymmetry.

Conclusions

The results of the present study reported a percentage of symmetry that varied from 70%–81%. These variations in symmetry should be taken in high consideration when treating 2 opposite molars in the same patient, because their anatomy may be different in up to 30% of the cases.     

Use of Cone-beam Computed Tomography to Evaluate Root Canal Morphology and Locate Root Canal Orifices of Maxillary Second Premolars in a Chinese Subpopulation

Introduction

The aim of this study was to investigate root canal morphology and locate root canal orifices of maxillary second premolars in a Chinese subpopulation using cone-beam computed tomographic imaging.

Methods

A total of 392 cone-beam computed tomographic images of maxillary second premolars were obtained from 238 patients who required a preoperative assessment for implant surgery or orthodontic treatment. The number of roots and root canals and root canal configuration were investigated and categorized using Vertucci's criteria. The distance between the root canal orifice and the anatomic apex and the distance between root canal orifices in those teeth with 2 root canals were measured and evaluated. The Fisher exact test was used to analyze the correlation between the number of roots and sex.

Results

Among the 392 teeth, 86.5% (n = 339) had 1 root; 45.4% (n = 178) of the teeth had 1 root canal, and 54.3% (n = 213) had 2 root canals that ranged from type II–type V. The majority of teeth with 2 root canals showed a type IV canal configuration (n = 79, 20.2%) followed by type II (n = 64, 16.3%), type III (n = 45, 11.4%), and type V (n = 25, 6.4%). Only 1 tooth had 3 root canals. No significant difference was found between the number of roots and sex (P > .05). Among the 213 teeth with 2 root canals, the most frequent distribution of the distance between the root canal orifice and the anatomic apex was 5–10 mm (n = 157). The distance between the 2 orifices of 189 teeth was 1–4 mm.

Conclusions

The frequency of teeth with 2 root canals was high in maxillary second premolars. The internal morphology of teeth with 2 root canals was variable. This study provided useful information about the root canal morphology of maxillary second premolars in a Chinese subpopulation.     

Morphology of Mandibular First Molars Analyzed by Cone-beam Computed Tomography in a Korean Population: Variations in the Number of Roots and Canals

Introduction

The aim of this study was to determine the root and canal morphology of the mandibular first molars in a Korean population of Mongolian origin by retrospective analysis of a large number of cone-beam computed tomography (CBCT) images.

Methods

A total of 976 subjects with bilateral mandibular first molars were examined by using in vivo CBCT methods. The number and configuration of roots, the number of root canals, and the canal configuration based on Vertucci's classification were determined.

Results

Overall, 25.82% of examined molars had 3 roots, 73.51% had 2 roots, and 0.67% had 1 root. The incidence of fourth canal was 50.36%. A right-sided predominance was noted for extra distal roots (P < .001), whereas a left-sided predominance was observed for extra distal canals (P < .001). No significant sex-related differences were shown for their prevalence. The bilateral prevalence rate was 69.13% for extra distal roots and 78.08% for extra distolingual (DL) canals. In the mesial roots, type IV canal was the most frequent (76.86% for 2-rooted molars and 72.96% for 3-rooted molars). In the distal roots, type l was the most common (66.62% for 2-rooted molars and 99.40%–100% for 3-rooted molars). The incidence of 2 canals in distobuccal roots, first reported in this study, was 0.15%.

Conclusions

Among mandibular first molars, there is a high prevalence of a separate DL root and/or a separate DL canal, and such molars commonly have 4 canals in the Korean population. CBCT is a useful tool for determining root and canal morphology.     

Comparative Study of Different Novel Nickel-Titanium Rotary Systems for Root Canal Preparation in Severely Curved Root Canals

Introduction

We compared the effects of 6 different rotary systems on transportation, canal curvature, centering ratio, surface area, and volumetric changes of curved mesial root canals of mandibular molar via cone-beam computed tomographic (CBCT) imaging.

Methods

Mesiobuccal root canals of 120 mandibular first molars with an angle of curvature ranging from 20°–40° were divided into 6 groups of 20 canals. Based on CBCT images taken before instrumentation, the groups were balanced with respect to the angle and radius of canal curvature. Root canals were shaped with the following systems with an apical size of 25: OneShape (OS) (MicroMega, Besancon, France), ProTaper Universal (PU) F2 (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next X2 (Dentsply Maillefer), Reciproc (R) R25 (VDW, Munich, Germany), Twisted File Adaptive (TFA) SM2 (SybronEndo, Orange, CA), and WaveOne primary (Dentsply Tulsa Dental Specialties, Tulsa, OK). After root canal preparation, changes were assessed with CBCT imaging. The significance level was set at P = .05.

Results

The R system removed a significantly higher amount of dentin than the OS, PU, and TFA systems (P < .05). There was no significant difference among the 6 groups in transportation, canal curvature, changes of surface area, and centering ratio after instrumentation.

Conclusions

The 6 different file systems straightened root canal curvature similarly and produced similar canal transportation in the preparation of mesial canals of mandibular molars. R instrumentation exhibited superior performance compared with the OS, TFA, and PU systems with respect to volumetric change.     

Morphologic Micro–Computed Tomography Analysis of Mandibular Premolars with Three Root Canals

Introduction

This study aimed to describe the anatomy of mandibular premolars with type IX canal configuration by using micro–computed tomography.

Methods

Mandibular premolars with radicular grooves (n = 105) were scanned, and 16 teeth with type IX configuration were selected. Number and location of canals, distances between anatomic landmarks, occurrence of apical delta, root canal fusion, and furcation canals, as well as 2-dimensional (area, perimeter, roundness, major and minor diameters) and 3-dimensional (volume, surface area, and structure model index) analysis were performed. Data were statistically compared by using analysis of variance and Kruskal-Wallis tests (α = 0.05).

Results

Overall, specimens had 1 root with a main canal that divided into mesiobuccal, distobuccal, and lingual canals at the furcation level. Mean length of the teeth was 22.9 ± 2.06 mm, and the configuration of the pulp chamber was mostly triangle-shaped. Mean distances from the furcation to the apex and cementoenamel junction were 9.14 ± 2.07 and 5.59 ± 2.19 mm, respectively. Apical delta, root canal fusion, and furcation canals were present in 4, 5, and 10 specimens, respectively. No statistical differences were found in the 2-dimensional and 3-dimensional analyses between root canals (P > .05).

Conclusions

Type IX configuration of the root canal system was found in 16 of 105 mandibular premolars with radicular grooves. Most of the specimens had a triangle-shaped pulp chamber. Within this anatomic configuration, complexities of the root canal systems such as the presence of furcation canals, fusion of canals, oval-shaped canals in the apical third, small orifices at the pulp chamber level, and apical delta were also observed.     

Area and 3-dimensional Volumetric Changes of Periapical Lesions after Root Canal Treatments

Introduction

This study compared the changes in size of periapical lesions after root canal treatment as revealed by periapical radiography (PA) and cone-beam computed tomography (CBCT) imaging using area and 3-dimensional volumetric measurements and assessed the outcome of the treatments based on these parameters.

Methods

Both PA and CBCT scans were taken preoperatively and at recall. In total, 50 teeth (71 roots) with evidence of periapical bone loss on both PA and CBCT images were endodontically treated and followed for 10–37 months. The area and volume of periapical lesions were measured, and changes were presented in the following 4 categories: lesion undetected, lesion reduced in size, lesion unchanged, or lesion enlarged. The McNemar and chi-square tests were used to compare the lesion changes determined by CBCT imaging and PA.

Results

The 4-category diagnosis made using both methods were in agreement in 39 of 71 (54.9%) roots, whereas disagreement was observed in 32 of 71 (45.1%) roots (P < .001). At recall, lesion was absent in 11 of 71 (15.5%) roots on CBCT scans and 32 of 71 (45.1%) roots on PA (P < .001). When success was defined as the absence of a lesion or a reduction in size of a lesion, 55 (77.5%) roots on CBCT imaging showed success and 63 (88.7%) roots on PA (P = .073).

Conclusions

Changes in lesion size after root canal treatment determined with 3-dimensional volumetric CBCT data and 2-dimensional PA data are different. The outcome of root canal treatments determined with PA could be untrue.     

Root and Root Canal Morphology in Maxillary Second Molar with Fused Root from a Native Chinese Population

Introduction

Root fusion is an anatomic variation in maxillary second molars (MSMs); however, the nature of this canal morphology as it relates to its root anatomy has not been fully clarified. The purpose of this study was to investigate the relationship between features of fused roots and root canal anatomy in MSMs using micro–computed tomographic imaging.

Methods

One hundred eighty-seven extracted MSMs were scanned with the μCT50 (Scanco Medical, Bassersdorf, Switzerland), and their root and canal morphology was classified and analyzed using the classifications proposed by Yang and Vertucci. The number and position of canals that merged were recorded and compared among different root fusion types.

Results

One hundred eight (57.75%) MSMs had 3 separate roots, and 79 (42.25%) had fused roots. Of the 79 fused roots, 22 showed partial canal merging, and 6 had complete canal merging. Canal merging was found with teeth with 3-root fusion more often than in those with 2-root fusion (P < .05). Of 28 merged canals, 16 occurred between mesiobuccal and distobuccal canals and 9 among mesiobuccal, distobuccal, and palatal canals.

Conclusions

MSMs with fused roots may present a complicated root canal system as a result of canal merging.     

Radiographic Healing after a Root Canal Treatment Performed in Single-rooted Teeth with and without Ultrasonic Activation of the Irrigant: A Randomized Controlled Trial

Introduction

The aim of this study was to compare the outcome of a root canal treatment with and without additional ultrasonic activation of the irrigant.

Methods

Single-rooted teeth with radiographic evidence of periapical bone loss were randomly assigned to 2 treatment groups. In both groups syringe irrigation was performed, and in one group the irrigant was also activated by ultrasound. Ten to 19 months after treatment, the teeth were examined by using periapical radiography (PA) and cone-beam computed tomography (CBCT). Area and volume of the periapical lesions were measured, and the outcome was presented in 4 categories: absence, reduction or enlargement of the radiolucency, or uncertain. Lesions were classified as reduced or enlarged when the change in size of the radiolucency was 20% or more.

Results

The recall rate was 82%, and 84 teeth were analyzed. CBCT detected significantly more post-treatment lesions than PA (P = .038), but the percentages of absence and reduction of the radiolucency together revealed by CBCT and PA were similar (P = .383). The CBCT results showed that absence of the radiolucency was observed in 16 of 84 teeth (19%) and reduction of the radiolucency in 61 of 84 teeth (72.6%), but there was no significant difference between the results of the 2 groups (P = .470). Absence and reduction of the radiolucency together were observed in the ultrasonic group in 39 of 41 teeth (95.1%) and in the syringe group in 38 of 43 teeth (88.4%).

Conclusions

Root canal treatments with and without additional ultrasonic activation of the irrigant contributed equally to periapical healing.     

Three-dimensional Analysis of Root Canal Curvature and Direction of Maxillary Lateral Incisors by Using Cone-beam Computed Tomography

Introduction

Root canal curvature can affect the technical quality of endodontic treatment. Prior studies measured canal curvature mainly by 2-dimensional radiography. The aim of this study was to measure the 3-dimensional (3D) root canal curvature and canal direction of maxillary lateral incisors by using cone-beam computed tomography (CBCT) and mathematical modeling.

Methods

The CBCT images of 186 maxillary lateral incisors from 110 patients were used to measure 3D root canal curvature by using V-works and kappa software. In addition, the direction of each root canal was determined by measuring the orientation of the apical one-third with respect to the coronal two-thirds.

Results

All 186 maxillary lateral incisors were found to have canal curvature that was mainly oriented in the disto-palatal direction. The point of maximum curvature was located 0.5 mm from the root apex.

Conclusions

Maxillary lateral incisors have 3D canal curvature that is maximal near the root apex, oriented in the disto-palatal direction. These CBCT analyses provide valuable information for root canal instrumentation of maxillary lateral incisors.     

Root Canal Morphology of South Asian Indian Mandibular Premolar Teeth

Introduction

The purpose of this study was to study the root canal morphology of South Asian Indian mandibular premolars using a tooth clearing technique.

Methods

Two hundred mandibular premolar teeth were collected from different dental schools and clinics in India. After pulp tissue removal and root canal staining with Indian ink, the specimens were decalcified with 5% nitric acid, dehydrated in ethyl alcohol, and subsequently cleared in methyl salicylate.

Results

Of the 200 mandibular premolars, 100 were first premolars and 100 were second premolars. Of the first premolars, 94% had a single root, whereas 6% were 2 rooted. Seventy-six percent had a single canal, 22% had 2 canals, and 2% had 3 canals. Eighty-two percent had a single apical foramen, 16% had 2 foramens, and 2% teeth had 3 apical foramens. Eighty percent of teeth had type I, 6% had type II, 10% had type IV, 2% had type V, and 2% teeth had type IX root canal anatomy. Of the 100 second premolars, 92% had a single root, whereas 8% teeth were 2 rooted and fused. Fifty-eight percent of teeth had a single canal, and 42% had two canals. Eighty-eight percent had a single apical foramen, and 12% had 2 foramens. Sixty-six percent had type I, 30% had type II, and 4% had type V root canal anatomy.

Conclusions

A high prevalence of 2 canals was noted in the first and second premolars. Also, 20% of first premolars and 34% of second premolars had a root canal anatomy other than type I.     

Impact of Three Radiographic Methods in the Outcome of Nonsurgical Endodontic Treatment: A Five-Year Follow-up

Introduction

The periapical film radiograph (PFR) and digital periapical radiograph (DPR) techniques have some limitations in the visualization of small periapical lesions (PLs) when compared with cone-beam computed tomography (CBCT). However, the evidence supporting their effectiveness is very limited. This retrospective longitudinal cohort study evaluated the outcome of endodontic treatments measured/monitored by PFR, DPR, and CBCT during a 5-year follow-up and also determined the prognostic factors that influenced treatment success.

Methods

A total of 132 teeth (208 roots) with vital pulps received endodontic treatment. The periapical indexes with scores ≥2 for PFR and DPR and ≥1 for CBCT indicated the presence of PLs. Prognostic factors were determined by bivariate and multivariate analyses. Statistical significance was defined at a P level <.05.

Results

CBCT detected a higher number of PLs (18.7%, n = 39 roots), followed by DPR (7.7%, n = 16 roots) and PFR (5.7%, n = 12 roots). Likewise, CBCT was more sensitive than PFR and DPR in detecting deficiencies in extension and density of the root canal filling (P ≤ .001). Of the 17 prognostic factors evaluated, 4 were significantly associated with poor outcome to the treatment (P < .05): root canal curvature, disinfection of gutta-percha, presence of missed canals, and the quality of definitive coronal restoration.

Conclusions

The success outcome of endodontic treatment after 5 years in teeth with vital pulps varied with each radiographic method: 94.3%/PFR, 92.3%/DPR, and 81.3%/CBCT.     

Correlation of Root Dentin Thickness and Length of Roots in Mesial Roots of Mandibular Molars

Introduction

The purpose of this study was to analyze the relation of tooth length and distal wall thickness of mesial roots in mandibular molars at different locations (ie, 2 mm below the furcation and at the junction between the middle and apical third).

Methods

Forty-five mandibular first molars were taken, and the length of each tooth was measured. Then, specimens were divided into three groups according to their length: group I–long (24.2 mm ± 1.8), group II–medium (21 mm ± 1.5) and group III–short (16.8 mm ± 1.8). mesial root of each marked at two levels - at 2 mm below the furcation as well as at junction of apical and middle third of roots. The minimum thickness of the distal root dentine associated with the buccal and lingual canals of the mesial roots was measured, The distance between the buccal and lingual canals and the depth of concavity in the distal surface of the mesial roots were also measured.

Results

Statistical analysis was performed by using analysis of variance and the Student-Newman-Keuls test. The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < .001) between groups 1 (long) and 3 (short).

Conclusions

Distal wall thickness of the mesiobuccal root and distal concavity of the mesial root of mandibular first molars were found to be thinner in longer teeth compared with shorter teeth.     

Histologic Examinations of Teeth Treated with 2 Scaffolds: A Pilot Animal Investigation

Introduction

A growing body of evidence is building a case for the possibility of tissue regeneration within the root canal of necrotic teeth, allowing for continued root development. However, it remains unknown what type of tissue is produced after regenerative endodontics. The purpose of this study was to use blood clots and platelet-rich plasma (PRP) as scaffolds in regenerative endodontics under ideal conditions in a ferret model to examine the tissues generated within the root canals.

Methods

The pulps of 21 canine teeth from 7 young ferrets were extirpated using broaches without filing the canal walls. Bleeding was stimulated from the periapical tissues, and a blood clot was induced in the canal space to the level of the cementoenamel junction in 12 teeth. PRP was prepared and placed in the canals to the level of the cementoenamel junction in 9 teeth. The coronal access was sealed with mineral trioxide aggregate. Seven canines were not operated on and served as controls. Three months later, block sections including each canine and its surrounding tissues were removed for histologic evaluation. The tissues found in the canals of experimental teeth were compared with those in the control teeth.

Results

Almost all of the experimental teeth showed the presence of intracanal bonelike tissue. No evidence of dentinal wall thickening or apical narrowing was noted in the experimental teeth.

Conclusions

In this experimental model, the use of either PRP or blood clots during regenerative endodontics leads to the formation of intracanal bonelike tissue without continual root maturation.     

Radiographic Identification of Separated Instruments Retained in the Apical Third of Root Canal–filled Teeth

Introduction

The aim of the study was to compare the diagnostic ability to radiographically detect separated stainless steel (SS) versus nickel-titanium (NiTi) instruments located at the apical third of filled root canals with either AH 26 (Dentsply DeTrey GmbH, Konstanz, Germany) or Roth sealer (Roth International Ltd, Chicago, IL).

Methods

Sixty single-rooted extracted human teeth with 1 straight root canal were instrumented to a size 25 apical diameter. In 40 teeth, apical 2-mm segments of SS (n = 20) or NiTi (n = 20) files were intentionally fractured in the apical part of the root canal. The remaining 20 teeth without fractured files served as a control group. Subsequently, the root canals were filled using laterally condensed gutta-percha and either AH 26 sealer (AH) or Roth sealer (Roth). All teeth were radiographed using conventional Kodak film (Eastman Kodak Co, Rochester, NY) and a charge-coupled device digital sensor. The evaluation of the images for the presence of a fractured instrument was performed independently by 2 blinded observers. The data were statistically analyzed using McNemar and Fisher exact tests.

Results

The kappa values were 0.76 and 0.615 for the first and second observers, respectively, and 0.584 between the observers. There were no significant differences in the diagnostic ability between digital and conventional radiography or the different root canal sealers (AH vs Roth, P > .05). The sensitivity to detect fractured SS was significantly higher than NiTi (P < .05).

Conclusions

It may be difficult to radiographically detect a retained separated instrument. It is easier to radiographically detect fractured SS than NiTi instruments retained at the apical third of the root canal.