• The Journal of the Korean dental association
• /
• v.50 no.4
• /
• pp.203-210
• /
• 2012

Objective: The aim of this study was to investigate the incidence of the C-shaped canal of permanent mandibular second molar (PMSM) in Korean sub-population using Cone-Beam CT (CBCT) data and analyze the types of C-shaped canal. Materials & Methods: The protocol for this study was approved by the Institutional Review Board at the Pusan National University Hospital (E-2011039). Among the CBCT images taken of patients who visited the St. Bennedict Dental Hospital (Busan, Korea) from May 2008 to April 2011 for implant surgery and surgical removal of impacted teeth, high-quality CBCTs from 705 patients (361 male and 342 female) were screened and 607 PMSMs of 383 patients were evaluated retrospectively. All PMSMs were anatomically analyzed in detail by using image viewer software (EasyDent; Vatech). PMSMs were evaluated in the axial plane to investigate the shape of root and canals. The C-shaped canals were classified into five types. The total incidence, gender ratio, bilateral and unilateral appearance. and the correlation between right-side and left-side occurrences of C-shaped PMSMs were computed and compared statistically using the chi-square test. Results: Among the 607 PMSMs of 383 CBCTs of 187 females and 196 males, 198 PMSMs(32.6%) had C-shaped root and 158 PMSMs(26.0%) had C-shaped canals. The shape of C-shaped root canals at the furcalion level did not have significant change at the level of mid root (P<0.0001). Female had more prevalence of C-shaped root canals than male (P<0.0001). The prevalence of bilateral occurrence of C-shaped root canals was higher than unilateral occurrence. Conclusions: The occurrence of C-shaped PMSMs among a Korean population was 32.6% and was higher than other countries and ethnicities. Understanding the prevalence of PMSMs with a C-shaped root and/or canal in a Korean population may be useful for successful endodontic treatments.

• Imaging Science in Dentistry
• /
• v.51 no.1
• /
• pp.27-34
• /
• 2021

Purpose: This study was performed to compare the ability of limited- and large-volume cone-beam computed tomography (CBCT) to display isthmuses in the apical root canals of mandibular molars. Materials and Methods: Forty human mandibular first molars with isthmuses in the apical 3 mm of mesial roots were scanned by micro-computed tomography (micro-CT), and their thickness, area, and length were recorded. The samples were examined using 2 CBCT systems, using the smallest voxels and field of view available for each device. The Mann-Whitney, Friedman, and Dunn multiple comparison tests were performed (α=0.05). Results: The 3D Accuitomo 170 and i-Cat devices detected 77.5% and 75.0% of isthmuses, respectively (P>0.05). For length measurements, there were significant differences between micro-CT and both 3D Accuitomo 170 and i-Cat(P<0.05). Conclusion: Both CBCT systems performed similarly and did not detect isthmuses in the apical third in some cases. CBCT still does not equal the performance of micro-CT in isthmus detection, but it is nonetheless a valuable tool in endodontic practice.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.36 no.2
• /
• pp.88-94
• /
• 2020

Purpose: The purpose of this study was to analyze the sagittal root position of maxillary anterior teeth and report the frequency of each classification in Korean for immediate implant placement. Materials and Methods: A retrospective review of cone-beam computed tomography (cone-beam CT) images was conducted on 120 patients (60 male and 60 female) who fulfilled the inclusion criteria. After reorientation of the axis, cone-beam CT images were evaluated and the relationship of the sagittal root position (SRP) of the maxillary anterior teeth to its associated osseous housing was recorded. Class I, II, and III were classified respectively when the root was positioned on the labial, central, and palatal aspect of the alveolar bone. Class IV was the position that at least two thirds of the root is engaging both the labial and palatal cortical plates. Then, the angulation of the root axis and the alveolar bone axis was measured. Descriptive statistics and Kruskal-Wallis test were used to compare the angulation according to the root position and SRP class. Results: The frequency distribution of sagittal root position of maxillary anterior teeth indicated that 81.1%, 10.3%, 1.9%, and 6.7% were classified as Class I, II, III, and IV, respectively. The sagittal angulation at approximately 77.5% of central incisor, lateral incisor, and canine was < 20 degrees, but the angle at more than 42.7% of canine was ≥ 20 degrees. Within the class, the angulation was statistically significantly greater in Class I (16.19) compared to Class II (8.72) and Class III (9.93), and smaller in Class IV (3.79). Conclusion: Within the limitation of this study, a majority of the maxillary anterior roots were positioned close to the buccal cortical plate. However, some roots have very thin alveolar bone and sagittal angulation larger than 30 degrees. Therefore, cone-beam CT analyses of the sagittal root position and the sagittal angulation are recommended for the selection of the appropriate dental implant treatment approach.

• Journal of Periodontal and Implant Science
• /
• v.46 no.2
• /
• pp.116-127
• /
• 2016

Purpose: The objective of this study was to investigate the relationships between primary implant stability as measured by impact response frequency and the structural parameters of trabecular bone using cone-beam computed tomography(CBCT), excluding the effect of cortical bone thickness. Methods: We measured the impact response of a dental implant placed into swine bone specimens composed of only trabecular bone without the cortical bone layer using an inductive sensor. The peak frequency of the impact response spectrum was determined as an implant stability criterion (SPF). The 3D microstructural parameters were calculated from CT images of the bone specimens obtained using both micro-CT and CBCT. Results: SPF had significant positive correlations with trabecular bone structural parameters (BV/TV, BV, BS, BSD, Tb.Th, Tb.N, FD, and BS/BV) (P<0.01) while SPF demonstrated significant negative correlations with other microstructural parameters (Tb.Sp, Tb.Pf, and SMI) using micro-CT and CBCT (P<0.01). Conclusions: There was an increase in implant stability prediction by combining BV/TV and SMI in the stepwise forward regression analysis. Bone with high volume density and low surface density shows high implant stability. Well-connected thick bone with small marrow spaces also shows high implant stability. The combination of bone density and architectural parameters measured using CBCT can predict the implant stability more accurately than the density alone in clinical diagnoses.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.29 no.1
• /
• pp.23-36
• /
• 2013

To evaluate the 3-dimensional features of the grafted bone with maxillary sinus augmentation and to assess the relation between the degree of bone resorption and the type of bone grafting source and implant, and the operation method. A retrospective chart review of patients receiving sinus augmentation procedures for implant positioning was conducted: radiographic analysis of the volume and area of bone grafts was performed. The volumetric remodeling.measured at 6 months after implant positioning as the percentage of residual bone graft.was correlated to type of graft materials and operation methods. 53 dental implants positioned with sinus bone graft in 15 patients at Wonkwang University Sanbon Dental Hospital. Computed tomography scans,taken implant positioning after 6 months, showed greater resorption values for the group of $Puros^{(R)}$ graft alone from the group of mixed with $Puros^{(R)}$ and various bone graft (P<0.05, respectively). And resorption values according to operation methods have statistically significant difference(P<0.05). Volume change ratio of bone graft showed greater values for the group of delayed implant position from the group of simultaneously implant placement with bone graft. Retrospective data analysis shows that the method of graft with $Puros^{(R)}$ alone may occur greater resorption of graft materials than mixed graft material with $Puros^{(R)}$ and other graft materials. The group of simultaneously implant placement with bone graft also display smaller resorption ratio of bone graft than the group of delayed implant placement.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.35 no.4
• /
• pp.214-219
• /
• 2019

Purpose: The aim of this study was to evaluate the correlation between inter-condylar width and inter-maxillary first molar width to present the criteria for prosthetic reconstruction of dental arch width in maxillary and mandibular fully edentulous patients. Materials and Methods: 120 Koreans (60 males and 60 females) who underwent the cone beam computerized tomography (Cone-beam CT) were selected. The Cone-beam CT images were analysed using Invivo 5.1. After reorientation of axis, inter-maxillary first molar width was measured by clicking both mesio-buccal cusp tip of maxillary first molar. And inter-condylar width was measured by clicking both middle points of condyles. The collected data were analysed with SPSS Version 20.0 and statistical significance of the correlation between inter-condylar width and inter-maxillary first molar width was verified by Pearson's correlation analysis. Results: The mean inter-condylar width of Korean was 105.9 mm, and that of male (108.3 mm) was statistically significantly wider than the female (103.4 mm). The inter-maxillary first molar width of Korean was 57.1 mm, and that of male (57.9 mm) was statistically significantly wider than the female (56.2 mm). Pearson's correlation analysis between inter-condylar width and inter-maxillary first molar width showed a Pearson correlation coefficient of 0.614 and statistically significantly positive correlation. Conclusion: Intercondylar width and inter-maxillary first molar width showed positive correlation and the average ratio of inter-condylar with and inter-maxillary first molar width was 1:0.54. Based on the results of this limited study, inter-condylar width can be used as a guide for setting up dental arch width in fully edentulous patient.

• Imaging Science in Dentistry
• /
• v.45 no.4
• /
• pp.205-211
• /
• 2015

Purpose: This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods: Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. Results: The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Conclusion: Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

• Imaging Science in Dentistry
• /
• v.34 no.1
• /
• pp.7-12
• /
• 2004

Purpose: To investigate the anatomical structure of the incisive canal radiographically by a cone beam computed tomography. Materials and Methods: 38 persons (male 26, female 12) were chosen to take images of maxillary anterior region in dental CT mode using a cone beam computed tomography. The tube voltage were 65, 67, and 70kVp, the tube current was 7 mA, and the exposure time was 13.3 seconds. The FH plane of each person was parallel to the floor. The images were analysed on the CRT display. Results: The mean length of incisive canal was 15.87 mm±2.92. The mean diameter at the side of palate and nasal fossa were 3.49 mm±0.76 and 3.89 mm± 1.06, respectively. In the cross-sectional shape of incisive canal, 50% were round, 34.2% were ovoid, and 15.8% were lobulated. 87% of incisive canal at the side of nasal fossa have one canal, 10.4% have two canals, and 2.6% have three canals, but these canals were merged into one canal in the middle portion of palate. The mean angles of the long axis of incisive canal and central incisor to the FH plane were 110.3°±6.96 and 117.45°±7.41, respectively. The angles of the long axis of incisive canal and central incisor to the FH plane were least correlated (r= 0.258). Conclusion : This experiment suggests that a cone beam computed radiography will be helpful in surgery or implantation on the maxillary incisive area.

• The Journal of the Korean dental association
• /
• v.52 no.6
• /
• pp.363-369
• /
• 2014

The cutaneous sinus tract is an uncommon disease. It is difficult to diagnose exactly of odontogenic cutaneous sinus tract for dentists or dermatologists except experienced clinicians or previously known clinicians. Many patients may be treated with repeated surgical excisions, biopsies, and antibiotic medications, but most of them could be frustrated with the recurrence of disease. There are several methods for diagnosis of odontogenic cutaneous sinus tract - such as GP cone tracing, conventional computed tomography(CT), periapical x-ray imaging, and cone beam computed tomography(CBCT). This case report describes the diagnosis and treatment of odontogenic cutaneous sinus tract that referred from medical doctors.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.30 no.3
• /
• pp.215-222
• /
• 2014

Purpose: The aim of this study was to investigate differences between the morphology of the mandibular symphysis and four facial skeletal types. Materials and Methods: 40 cone-beam computed tomographies were selected and classified in to 4 groups according to their vertical and anterior-posterior skeletal patterns. The bone volume ($mm^3$) of the symphysis, the cross sectional area corresponding to the 4 mandibular incisors' axis: the cross sectional area of total bone ($mm^2$), the area of the cancellous bone ($mm^2$) and the thickness (mm) of labial and lingual alveolar bone at 2 mm, 3 mm under the cemento-enamel junction (CEJ) were measured. General linear model (GLM), Kruskal-Wallis test and Tukey honestly significant difference (HSD) test were subsequently used for statistical analysis. Results: The lingual cortical bone thickness of the lateral incisors at 2, 3 mm under CEJ was greater in the Class I low angle group than the other 3 groups (P < 0.05). There were no statistically significant differences in the volume of the mandibular incisor bony support, cross-sectional area of total bone and cancellous bone at the mandibular incisor' axis. Conclusion: Patients in Class I, low angle group have a thicker lingual mandibular symphysis than Class I, high angle patients.