Jong-Ki Lee

Mesiobuccal root canal anatomy of Korean maxillary first and second molars by cone-beam computed tomography

OBJECTIVE The aim of this study was to investigate the types of canal configurations and the incidence of a second mesiobuccal (MB2) canal in Korean maxillary molar mesiobuccal (MB) roots by analyzing cone-beam computed tomographic (CBCT) images. STUDY DESIGN Three-dimensional CBCT images of 458 maxillary first molars and 467 second molars from 276 Korean patients were analyzed to determine the incidence of an MB2 canal, the types of canal configurations, and the correlations between the incidence of an MB2 canal and age, gender, and tooth position. RESULTS The incidence of 2-canaled MB roots was 71.8% in first molars and 42.2% in second molars, with the most common configurations being Weine types III and II. The frequency of an MB2 canal decreased with age in both molars (P < .05). CONCLUSIONS Types III and II canal configurations were the most prevalent in the 2-canaled MB roots of Korean maxillary molars.

Three-dimensional analysis of maxillary first molar mesiobuccal root canal configuration and curvature using micro-computed tomography.

OBJECTIVE The complex anatomic configuration of the maxillary first molar mesiobuccal (MB) root canal system has been the subject of several studies. The purpose of this investigation was to analyze the 3-dimensional (3D) characteristics of the maxillary first molar MB canal system using micro-computed tomography (microCT). STUDY DESIGN Extracted maxillary first molars (46) were scanned by microCT and their canals reconstructed by 3D modeling software. RESULTS In these MB roots, nearly two-thirds (65.2%) had 2 canals, fewer than one-third (28.3%) had only 1 canal, and a few (6.5%) had 3 canals. The most common root canal configuration was 2 distinct canals (type III: 37.0%), followed by 1 single canal (type I: 28.3%), 2 canals that joined together (type II: 17.4%), 1 canal that split into 2 (type IV: 10.9%), and 3 canals (type V: 6.5%). CONCLUSION MicroCT provided an in-depth analysis of canal configurations, as well as length, curvature, and location of calcified segments.

Comparison of Alternative Image Reformatting Techniques in Micro–Computed Tomography and Tooth Clearing for Detailed Canal Morphology

INTRODUCTION Micro-computed tomography (MCT) shows detailed root canal morphology that is not seen with traditional tooth clearing. However, alternative image reformatting techniques in MCT involving 2-dimensional (2D) minimum intensity projection (MinIP) and 3-dimensional (3D) volume-rendering reconstruction have not been directly compared with clearing. The aim was to compare alternative image reformatting techniques in MCT with tooth clearing on the mesiobuccal (MB) root of maxillary first molars. METHODS Eighteen maxillary first molar MB roots were scanned, and 2D MinIP and 3D volume-rendered images were reconstructed. Subsequently, the same MB roots were processed by traditional tooth clearing. Images from 2D, 3D, 2D + 3D, and clearing techniques were assessed by 4 endodontists to classify canal configuration and to identify fine anatomic structures such as accessory canals, intercanal communications, and loops. RESULTS All image reformatting techniques in MCT showed detailed configurations and numerous fine structures, such that none were classified as simple type I or II canals; several were classified as types III and IV according to Weine classification or types IV, V, and VI according to Vertucci; and most were nonclassifiable because of their complexity. The clearing images showed less detail, few fine structures, and numerous type I canals. Classification of canal configuration was in 100% intraobserver agreement for all 18 roots visualized by any of the image reformatting techniques in MCT but for only 4 roots (22.2%) classified according to Weine and 6 (33.3%) classified according to Vertucci, when using the clearing technique. CONCLUSIONS The combination of 2D MinIP and 3D volume-rendered images showed the most detailed canal morphology and fine anatomic structures.

Antimicrobial efficacy of a human β-defensin-3 peptide using an Enterococcus faecalis dentine infection model

AIM To assess the antibacterial efficacy of a human β-defensin-3 (HBD3) peptide against Enterococcus faecalis biofilms. METHODOLOGY Standardized human dentine blocks were infected with E. faecalis ATCC 29212 for 3 weeks. Aqueous calcium hydroxide paste (n = 12, CH), a 2% chlorhexidine gel (n = 12, CHX), an HBD3 peptide gel (n = 12) and saline (n = 12) were tested as experimental groups. A mismatched peptide gel group (n = 12, MP) and sterilized but noninoculated block group (n = 12) were included as controls. After 1 week of medication, the dentinal samples at the depth of 200 and 400 μm were collected from medicated canal lumens. Bacterial growth was assessed by spectrophotometric analysis of optical density (OD) after 72 h of incubation. Statistical analysis was performed with repeated-measures anova and Tukeys post hoc test. RESULTS The HBD3 group was associated with significantly lower OD values (P < 0.05) than the CH or CHX groups at both depths. The CH group did not differ significantly from MP or Saline group at either depth (P > 0.05). There was no significant difference (P > 0.05) in the OD values of the inner (200 μm) and outer (400 μm) dentinal samples for any group. CONCLUSIONS The HBD3 peptide inhibited the growth of E. faecalis biofilms in infected dentine blocks.

A biometric study of C‐shaped root canal systems in mandibular second molars using cone‐beam computed tomography

AIM To investigate the configuration of C-shaped canals in mandibular second molars, canal wall thickness and the orientation of the thinnest area at 1-mm intervals from the canal orifice to the apex by using cone-beam computed tomographic (CBCT) images. METHODOLOGY Three-dimensional CBCT images of 92 Korean mandibular second molars having C-shaped root canals were analysed to determine their configuration using a modification of Meltons classification, as well as the thinnest walls and their location. Associations between configuration type and distance from the canal orifice to the apex, as well as associations between the directional orientation of the thinnest root wall and distance from the canal orifice to the apex, were assessed by Fishers exact test. Because serial measurements of minimum wall thicknesses were correlated with individual teeth, a mixed-effects analysis was applied. RESULTS The most common configuration types were Meltons type I in the coronal region and Meltons type III in the apical region. Mean thicknesses of the thinnest root canal walls were 1.39 ± 0.38, 0.85 ± 0.25 and 0.77 ± 0.20 mm in the coronal, middle and apical regions, respectively. The thicker the root canal walls at the orifice region, the greater the decrease in thickness towards the apical region (P < 0.05), with the linguo-central root area being the thinnest. The pattern of decreasing thickness from the orifice to the apex formed a nonlinear cubic curve. CONCLUSIONS The most prevalent configuration types were Meltons type I (coronal region) and type III (apical region). The linguo-central root area was the thinnest in C-shaped root canals of Korean mandibular second molars. These anatomical variations should be considered during surgical or nonsurgical endodontic procedures.

Minimum-intensity projection for in-depth morphology study of mesiobuccal root

OBJECTIVE This micro-computed tomography (MCT) study investigated the utility of thin-slab minimum-intensity projection (TS-MinIP) technique as an adjunct to 3-dimensional (3D) modeling for in-depth morphology study. STUDY DESIGN One hundred one extracted maxillary first molars were scanned for microtomographic analysis (SkyScan). Two-dimensional TS-MinIP and 3D images of mesiobuccal (MB) roots were produced and analyzed to record the number and configurations of the canals, the incidence and location of accessory canals, loop, and intercanal connections, and number of foramina. RESULTS Multiple-canal MB roots were present in 76.2%, and all of the roots had intercanal communications. Weine type III configuration was the most common in the multiple-canal roots. Accessory canals were found in 78.2% of the roots. Configurations that were nonclassifiable were found in 10.9% of the MB roots. CONCLUSIONS MB root canal anatomy was complex, and MinIP may serve as an adjunct to 3D modeling for in-depth morphology study.

Comparison of mandibular first molar mesial root canal morphology using micro-computed tomography and clearing technique

Abstract Objective. Micro-computed tomography (MCT) with alternative image reformatting techniques shows complex and detailed root canal anatomy. This study compared two-dimensional (2D) and 3D MCT image reformatting with standard tooth clearing for studying mandibular first molar mesial root canal morphology. Materials and methods. Extracted human mandibular first molar mesial roots (n = 31) were scanned by MCT (Skyscan 1172). 2D thin-slab minimum intensity projection (TS-MinIP) and 3D volume rendered images were constructed. The same teeth were then processed by clearing and staining. For each root, images obtained from clearing, 2D, 3D and combined 2D and 3D techniques were examined independently by four endodontists and categorized according to Vertucci’s classification. Fine anatomical structures such as accessory canals, intercanal communications and loops were also identified. Results. Agreement among the four techniques for Vertucci’s classification was 45.2% (14/31). The most frequent were Vertucci’s type IV and then type II, although many had complex configurations that were non-classifiable. Generally, complex canal systems were more clearly visible in MCT images than with standard clearing and staining. Fine anatomical structures such as intercanal communications, accessory canals and loops were mostly detected with a combination of 2D TS-MinIP and 3D volume-rendering MCT images. Conclusions. Canal configurations and fine anatomic structures were more clearly observed in the combined 2D and 3D MCT images than the clearing technique. The frequency of non-classifiable configurations demonstrated the complexity of mandibular first molar mesial root canal anatomy.