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.     

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.     

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.     

Morphological Characteristics and Classification of Mandibular First Molars Having 2 Distal Roots or Canals: 3-Dimensional Biometric Analysis Using Cone-beam Computed Tomography in a Korean Population

Introduction

The aim of this study was to determine the morphologic characteristics of mandibular first molars having 2 canals in distal roots. Interorifice distance, buccal bone thickness, and root curvature were evaluated using cone-beam computed tomography images in a Korean population.

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.     

Root canal morphology of permanent three-rooted mandibular first molars: Part III--An odontometric analysis

Introduction

The purpose of this study was to quantitatively analyze the root canal morphology of three-rooted mandibular first molars by micro-computed tomography (micro-CT) scans.

Methods

Twenty three-rooted mandibular first molars were scanned by micro-CT scans. The teeth were reconstructed three-dimensionally by software Mimics 10.01 (Materialise, Leuven, Belgium). The levels of the root apexes and furcations; the diameters; wall thicknesses; and tapers of the mesiobuccal (MB), mesiodistal (ML), distobuccal (DB) and distolingual (DL) canals were determined. The buccolingual/mesiodiatal (BL/MD) diameter ratios (ΔC) and the prevalence of long oval canals (ΔC > 2) at different levels were calculated.

Results

The level of distal furcations was significantly (P < .01) lower than that of MD furcations with an average of 1.09 mm. The buccal and lingual walls were significantly (P < .05) thicker than the mesial and distal for the MB, ML, and DB canals. Among four canals, the DL canal had the smallest mean value of ΔC at each level. The average BL taper was greater than the MD for each canal except the middle portion of the DL canal.

Conclusion

The vertical length, width, BL/MD diameter ratio, wall thickness, and BL taper of the DB canals are on average greater than the DL canals. The MB, ML, and DB canals are more oval, whereas the DL canals are relatively rounder. The geometric data of root canals are useful for endodontic treatment on three-rooted mandibular first molars.     

Cone-beam Computed Tomographic Scans in Comparison with Periapical Radiographs for Root Canal Length Measurement: An In Situ Study

Introduction

The primary aim of this study was to compare the precision of root canal length determination on cone-beam computed tomographic (CBCT) scans and periapical radiographs (PAs) with the actual root canal length. The secondary aim was to examine the influence of tooth type on root canal length measurements as assessed on CBCT scans and PAs.

Methods

In total, 40 root canals of 33 teeth (molars, premolars, canines, and incisors) out of 5 dentate maxillas of human cadavers were included. Root canal length measurement was performed by a consensus panel (2 examiners) on CBCT scans (3D Accuitomo 170; J Morita, Kyoto, Japan) and digital PAs. After straight-line access opening, a #15 file was fixated in every root canal at the length measured on CBCT scans. All teeth were extracted, and the root canal containing the file was uncovered. Measurements made on images taken with a digital camera (AxioCam; Carl Zeiss, Sliedrecht, The Netherlands) linked to a stereozoom microscope (Stemi SV6, Carl Zeiss) were used as the actual root canal length.

Results

When all roots were examined together, it was not clear which method is better for all types of teeth. For root canals of anterior teeth, there was no significant difference between the 2 methods. For root canals of posterior teeth, CBCT images gave results significantly closer to the actual root canal length in comparison with PAs (t value = −1.96; critical value is 1.74 with a significance level of 0.05).

Conclusions

Root canal length measurements of posterior maxillary teeth were more accurate when assessed by CBCT images than PAs.     

Evaluation of Root and Canal Morphology of Maxillary Permanent First Molars in a North American Population by Cone-beam Computed Tomography

Introduction

The purpose of this study was to evaluate the number of roots and canal morphology of maxillary permanent first molars in a North American population.

Methods

Three hundred seventeen cases with bilateral maxillary first molars were included. All images from cone-beam computed tomography were carefully reviewed by 2 endodontists. Frequency of number of roots, presence of an additional mesiobuccal canal (MB2), and Vertucci canal type for each root were tabulated. Age, gender, and ethnicity differences were calculated with the χ² test. The intra-rater reliability was assessed by using the Cohen kappa statistic.

Results

The fused root rate was 0.9%. The occurrence of 3-rooted maxillary first molars differed between left and right sides (P = .03). MB2 occurrence only showed statistically significant differences among age groups (P = .005). In the mesiobuccal roots, the most common Vertucci classifications of canal types were type IV (2-2, 41.9%), type I (1, 28.3%), and type II (2-1, 26.3%). There was a statistically significant difference in Vertucci classification of canal type among 5 ethnic groups (African American, Asian, Hispanic, Other, and Non-Hispanic white, P < .001).

Conclusions

Cone-beam computed tomography facilitates the identification of root and canal configuration. The information gained about the tooth anatomy and canal morphology before treatment could potentially facilitate root canal therapy.     

Three Root Canals in the Mesiobuccal Root of Maxillary Molars: Case Reports and Literature Review

Introduction

The knowledge of root canal anatomy is essential to ensure a successful outcome of surgical and nonsurgical root canal treatment. The aims of this article were to present 2 cases of maxillary molars with 3 mesiobuccal root canals and to review the available literature on this anatomic variation.

Methods

The first case described a nonsurgical root canal treatment of tooth #16 in a 29-year-old man with the aid of a dental operating microscope. In the second case, an extracted maxillary right first molar was scanned by a micro–computed tomographic system and reconstructed 3-dimensionally using modeling software.

Results

In both cases, the mesiobuccal root had 3 canals (type 3-2 in case I and type 3-3 in case II), whereas the distobuccal and palatal roots had a single canal. The literature review showed that the overall incidence of 3-canaled mesiobuccal roots in maxillary molars ranged from 1.3%–2.4% and that the most common root canal configuration was type 3-2.

Conclusions

Clinicians should always anticipate the presence of extra canals in maxillary molars and use all the available tools to locate and treat these.     

Clinically Relevant Dimensions of 3-rooted Maxillary Premolars Obtained Via High-resolution Computed Tomography

Introduction

This study aimed to characterize the dimensions of a selection of 3-rooted maxillary premolars through high-resolution computed tomographic analysis considering measures of clinical interest for root canal treatment, such as root wall thickness, canal diameters, and distances between 2 canals in fused roots and between the root apex and foramen.

Methods

Fifteen 3-rooted human maxillary premolars extracted for therapeutic reasons were individually scanned using a high-resolution desktop high-resolution computed tomographic system. Starting from the apical foramen, the selected cross-sectional images corresponding to each millimeter of the roots were evaluated. Measures of clinical interest were determined using Image J software (version 1.41; National Institutes of Health, Bethesda, MD).

Results

Root wall thickness as thin as 0.4 and 0.6 mm was detected in the apical portion of buccal and palatal roots, respectively. In the cervical portion, buccal roots had narrower root walls (0.817–1.670 mm) compared with palatal roots (1.361–2.720 mm). In all thirds, the palatal canal was wider compared with the mesiobuccal and distobuccal canals. In the buccopalatal direction, all roots had thicker root walls toward the furcation, whereas in the mesiodistal direction the mesiobuccal and distobuccal roots had the thinnest walls along their distal and mesial aspects, respectively. Both buccal canals revealed dentin apposition 2 mm from the canal orifice, resulting in cervical constriction. Generally, the distance between the root apex and the foramen was greater in distobuccal roots in comparison with the others with a tendency for foramina to be eccentric.

Conclusions

Three-rooted premolars are a clinical challenge not just because of their low frequency and difficulties regarding diagnosis and root canals access but also because of their fragile roots. These phenomena are critical in terms of the amount of dentin removed during the preparation of root canals and during post space preparation.     

A Cone-beam Computed Tomographic Study of Root and Canal Morphology of Maxillary First and Second Permanent Molars in a Thai Population

Introduction

Understanding tooth anatomy is crucial for effective endodontic treatment. This study investigated the roots and root canal morphology of maxillary first and second permanent molars in a Thai population using cone-beam computed tomographic (CBCT) imaging.

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.     

Micro-computed tomography evaluation of the preparation of long oval root canals in mandibular molars with the self-adjusting file

Introduction

The aim of this study was to assess the shaping potential of a novel nickel-titanium instrument, the self-adjusting file (SAF), in long oval root canals in distal roots in mandibular molars.

Methods

Twenty mandibular molars with long oval distal root canals were selected and scanned preoperatively and postoperatively by using micro-computed tomography at an original resolution of 20 μm. Canals were shaped with the SAF, three-dimensionally reconstructed, and evaluated for volume, surface area, canal transportation, and prepared surface. Data were statistically contrasted by using paired t tests and regression analysis.

Results

Preoperatively, canal volume was 7.73 ± 2.13 mm³, and canal area was 42.83 ± 8.14 mm². Volumes and surface areas increased significantly (P < .001) by 4.84 ± 1.73 mm³ and 3.34 ± 1.73 mm², respectively, and no gross preparation errors were detected. Unprepared canal surface varied between individual canals, and mean unprepared surface was 23.5% ± 8.9%. Prepared areas were significantly larger compared with rotary canal preparation done in a previous study. Canal transportation scores were higher in the coronal root canal third (106 ± 50 μm) compared with the apical third (81 ± 49 μm).

Conclusions

In vitro, preparation of long oval-shaped root canals in mandibular molars with the SAF was effective and safe. Moreover, shapes generated with the SAF were more complete compared with rotary canal preparation.     

The Radix Entomolaris and Paramolaris: A Micro–Computed Tomographic Study of 3-rooted Mandibular First Molars

Introduction

The morphology of the supernumerary third root (radix) in mandibular first molars was examined by micro–computed tomography (μCT) scanning.

Methods

Nineteen permanent mandibular first molars with radix were scanned in a μCT device to evaluate their morphology with respect to root length, root curvature direction, location of radix, apical foramen, accessory canals and apical deltas, and distance between canal orifices as well as 2- and 3-dimensional parameters of the canals (number, area, roundness, major/minor diameter, volume, surface area, and structure model index). Quantitative data were analyzed by 1-way analysis of variance and the Tukey test (α = 0.05).

Results

The mean length of the mesial, distal, and radix roots was 20.36 ± 1.73 mm, 20.0 ± 1.83 mm, and 18.09 ± 1.68 mm, respectively. The radix was located distolingually (n = 16), mesiolingually (n = 1), and distobuccally (n = 2). In a proximal view, most radix roots had a severe curvature with buccal orientation and a buccally displaced apical foramen. The spatial configuration of the canal orifices on the pulp chamber floor was mostly in a trapezoidal shape. The radix root canal orifice was usually covered by a dentinal projection. The radix differed significantly from the mesial and distal roots for all evaluated 3-dimensional parameters (P < .05). The radix canal had a more circular shape in the apical third, and the mean size of the minor diameter 1 mm short of the foramen was 0.25 ± 0.10 mm.

Conclusions

The radix root is an important and challenging anatomic variation of mandibular first molars, which usually has a severe curvature with a predominantly distolingual location, and a narrow root canal with difficult access.     

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.     

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.     

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.     

Concurrent relationship between additional canals of mandibular first molars and maxillary first molars using cone-beam computed tomography

Objective

To investigate the bilateral concurrence and relationships between distolingual (DL) roots and DL canals of the mandibular first molars and second mesiobuccal (MB2) canals of the maxillary first molars using cone-beam computed tomography (CBCT).

Methods

A total of 150 CBCT images showing all mandibular and maxillary first molars were retrospectively investigated in a South Korean subpopulation. The patient age, sex, positions of first molars, and presence of roots and canals were assessed. The frequency, bilateral concurrence of DL roots, DL canals, and MB2 canals, and concurrent relationship of DL roots or DL canals with MB2 canals were investigated. Data were analyzed using Fisher’s exact test and odds ratios from binary logistic regression.

Results

The prevalences of DL roots, DL canals, and MB2 canals were 24.7, 42.7, and 56.0 %, respectively, and showed significant bilateral concurrence. A concurrent relationship between DL roots and MB2 canals was not demonstrated, whereas the presence of a DL canal was significantly correlated with the presence of an MB2 canal on the same side.

Conclusions

The presence of a DL root of the mandibular first molar, a strong ethnic characteristic, could not predict the presence of an MB2 canal of the maxillary first molar. The correlation between DL canals and MB2 canals on the same side and the significant bilateral concurrence, whether present or absent, of DL roots, DL canals, and MB2 canals can aid clinicians in the prediction of additional canals in the first molars.     

Canal Transportation,Unprepared Areas,and Dentin Removal after Preparation with BT-RaCe and ProTaper Next Systems

Introduction

This study compared the shaping ability of ProTaper Next (Dentsply Sirona, Tulsa, OK) and BT-RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) instrument systems in the mesial canals of mandibular molars using micro–computed tomographic (micro-CT) imaging.

Root and canal morphology of the mesiobuccal and distal roots of permanent first molars in a Kuwait population--a clinical study

Aim To identify the number of roots and canal configurations in permanent first molars of the indigenous Kuwaiti sub‐population and compare them against a similar group of non‐Kuwaiti population in different age groups and gender, and to determine the frequency of a second canal in the mesiobuccal root of maxillary first molars and distal root of mandibular first molars that could be located and treated in routine practice without using magnification or special lighting conditions. Methodology A total of 220 permanent first molar teeth of patients scheduled for root canal treatment over a period of 1 year were included. Patients were identified and grouped according to their nationality as Kuwaiti and non‐Kuwaiti (which included Filipinos, Indonesian Indians, Srilankans, Egyptians, Saudi Arabians and Syrians). In both nationality groups, patients were successively distributed into four groups based on their age. The first age group included patients below 20 years, the second 21–30 years, the third 31–40 years and the fourth were over 40 years. The first three groups comprised of 15 male and 15 female patients whilst the fourth group had 10 patients of each gender. Teeth with open apices, resorptions and calcification were excluded from the study. The teeth included were both clinically and radiographically examined for number of roots, the canal configuration and the presence of the additional mesiobuccal and distal canals and recorded. The simplified classification of canal configurations proposed by Weine was utilized. Results The incidence of a second canal in the mesiobuccal (MB) root of maxillary first molars and the distal root of mandibular first molars was not influenced significantly by nationality and gender. All the 110 maxillary first molars treated had three roots; 58% of MB root had one canal and 42% had two canals. The majority of the mesial roots had Weine type II canal configuration when the second mesiobuccal canal was present. All distobuccal and palatal roots had a single or type I canal configuration. Of the 110 mandibular first molars that were treated, 96% had two roots and 4% had three roots. When present, the third root was located either buccal or lingual to the main distal root. Overall 51% of the single distal roots had one canal whilst 49% had two canals. The mesial root frequently had a Weine type II canal configuration as did the distal root when a second canal was present. Pearson’s correlation analysis of both molars revealed a significant (P < 0.05) negative correlation (r = ?0.274, r = ?0.144) between age and number of canals as well as the type of canal. Conclusions The incidence of a second canal in distal roots of permanent mandibular first molars was 49% in the Kuwaiti population and this was similar to other Asian ethnic populations. Adopting modified access and troughing procedures revealed a 42% frequency of MB2 canals in maxillary first molars. The incidence of a second canal in both mesiobuccal roots of maxillary molars and distal roots of mandibular molars decreased significantly with age; no differences were noticed amongst the nationalities and gender studied. The possibility of extra roots should be anticipated in mandibular molars.