• Original Article

    Correction of Movement Error in Parallel-beam CT for Dental Implantology

    치과 임플란트 치료를 위한 평행광 CT의 움직임 에러 수정

    윤석환, 김성균, 허성주, 곽재영, 임재홍, 노승준, 전경택

    Seokhwan Yoon, Seong-Kyun Kim, Seong-Joo Heo, Jai-Young Koak, Jae-Hong Lim, SeungJoon Noh, Kyungtaek Jun

    Purpose: The purpose of this study is to correct the errors that may occur because of the patients' movement during the CT ... + READ MORE
    Purpose: The purpose of this study is to correct the errors that may occur because of the patients' movement during the CT scanning, and thus, to obtain more precise CT images, additionally to investigate the possible use of parallel Beam CT in the dental treatment. Materials and Methods: Applying the Radon transform using phantom image, the same image and the sinogram with the ones by CT scanning were obtained. The possible movement errors that patients may cause during the CT scan were given to the data images. The maximum width of errors was designed to reach 1 mm. The fixed point was identified in the errored CT projected images, and each projected image with errors was adjusted so that each fixed point is placed on the same axial plane, then the fixed point was traced on the sinogram. On the traced trajectory of the fixed point, the part deviated from the sinusoidal curve was modified using the Virtual Alignment Method. Results: The quality of reconstructed image was remarkably degraded when the movement errors were given. The movement errors were corrected by moving the fixed point to the center of sinogram and this relocation of fixed point did not cause any distortion of image or change of size. Conclusion: The movement errors during CT scanning were corrected using the fixed point inside of the image. The more precise CT images obtained through this method are expected to be of extensive application in the area of dental implantology. - COLLAPSE
    June 2020
  • Original Article

    Investigation of Optimal Cement Space in 3D Printed 3-unit Resin Prosthesis: A Pilot Study
    Gae-jun Jang, Seong-Kyun Kim, Seong-Joo Heo, Jai-Young Koak, Ji-Man Park
    Purpose: The purpose of this study was to investigate the optimal cement space in the 3D printed 3-unit resin fixed partial denture ... + READ MORE
    Purpose: The purpose of this study was to investigate the optimal cement space in the 3D printed 3-unit resin fixed partial denture. Materials and Methods: A model was fabricated for mandibular premolar and molar implant abutments. Forty resin prostheses were fabricated using stereolithography (SLA) 3D printer. A cement space of 90 µm (CS 90) was given for 20 specimens and a cement space of 100 µm (CS 100) was given for 20 specimens. The groups of each cement space were divided into 10 groups by a layer thickness (50 µm and 100 µm) and a build orientation (0°, 30°, 45°, 60° and 90°). The prostheses were seated and scanned with micro-CT. Marginal, axial and occlusal gaps were measured and statistically analyzed using Kruskal-Wallis and Mann-Whitney U test (α = .05). Results: In CS 90 groups, marginal gap (MG) value was 88.43 ± 41.77 µm, mid axial gap (AX) value was 92.74 ± 58.43 µm, axio-occlusal angle gap (AN) value was 80.49 ± 56.97 µm and occlusal gap (OC) value was 166.75 ± 52.38 µm. In CS 100 groups, MG value was 69.12 ± 40.17 µm, AX value was 113.43 ± 64.20 µm, AN value was 92.99 ± 55.73 µm and OC value was 161.79 ± 50.40 µm. In CS 100 group, MG showed smaller value in comparison to CS 90 group (p < .05). Conclusion: For the SLA 3D printed 3-unit resin fixed partial denture, setting the cement space to 90 µm or less is not recommended due to the interference in seating. - COLLAPSE
    June 2020
  • Original Article

    The Effect of ZrO2 Slurry Application to the Pre-sintered Zirconia Surface on Bonding Strength
    Yong-Bum Jo, Jong-Ju Ahn, So-Hyoun Lee, Taeseok Park, Jung-Bo Huh
    Purpose: This study was conducted to evaluate the roughness changes of zirconia surface after applying three different concentrations of ZrO 2 slurry ... + READ MORE
    Purpose: This study was conducted to evaluate the roughness changes of zirconia surface after applying three different concentrations of ZrO 2 slurry (ZirADD, PNUADD, Busan, Korea) to the pre-sintered zirconia surface and shear bond strength between zirconia and self-adhesive resin cement. Materials and Methods: Experimental groups were classified into control and three test groups according to the surface treatment with different slurry concentration (15% (ZA15), 30% (ZA30), and 50% (ZA50) group). After sintering all the specimen, roughness change was measured, and bond strength of the self-adhesive resin cement was examined. Results: Surface roughness values(Ra) significantly increased after applying ZrO 2 slurry. ZA50 group showed the highest surface roughness value compared to others (p < .05). But the shear bond strength value (MPa) showed that ZA30 group was the highest value among the groups (p < .05). Conclusion: Within the limitations of this study, ZrO 2 slurry application on pre-sintered zirconia surface can be an effective method to obtain strong bond between zirconia and self-adhesive resin cement by increasing zirconia surface roughness after zirconia sintering process. - COLLAPSE
    June 2020
  • Clinical or Case Report

    Combined Sinus Floor and Alveolar Ridge Augmentation Simultaneously Performed with Extraction of Ankylosed Maxillary Molar: A Case Report

    유착된 상악 대구치 발치와 동시에 상악동 골이식술과 치조골 증대술 복합 시행 증례

    Jisun Huh, Jisun Seo, Seoyeon Jung, Wonse Park

    허지선, 서지선, 정서연, 박원서

    This is a case report of combined sinus floor augmentation and alveolar ridge augmentation using a titanium mesh simultaneously performed with extraction ... + READ MORE
    This is a case report of combined sinus floor augmentation and alveolar ridge augmentation using a titanium mesh simultaneously performed with extraction of an ankylosed maxillary molar. An 18-year-old male presented with discomfort in the upper right molar. The maxillary right first molar was diagnosed with chronic apical periodontitis, ankylosis, and secondary dental caries. It was determined as hopeless prognosis due to the extensive secondary caries so we planned extraction of the tooth. Due to the pneumatization of the maxillary sinus and the vertical defects of the alveolar ridge, the bone dimension was insufficient for future implant placement. Sinus floor augmentation and alveolar ridge augmentation were performed simultaneously with extraction. Buccal flap was elevated for approach to the ankylosed root and the sinus. Piezosurgery was used for atraumatic removal of ankylosed tooth and the sinus window formation without the Schneiderian membrane perforation. Demineralized bone matrix and bovine bone mineral were grafted into the sinus and on the defected ridge. The sinus window was covered with a collagen membrane and a titanium mesh was installed at the ridge. Primary closure was achieved with buccal advanced flap and palatal rotational flap. Though there was titanium mesh exposure during the healing process, but sufficient bone formation was achieved. And the implant placement and the restoration procedures were successfully completed. - COLLAPSE
    June 2020
  • Clinical or Case Report

    Implant Surgery with Both Sinus Bone Graft in the Maxillary edentulous patient: A Case Report

    상악 무치악 환자에서 양측 상악동골이식을 동반한 임플란트 식립술: 증례보고

    Youngdeok Chee

    지영덕

    There are a variety of prosthetic methods for restoring edentulous patients. Among them, the dental implant is a stable and easily applicable ... + READ MORE
    There are a variety of prosthetic methods for restoring edentulous patients. Among them, the dental implant is a stable and easily applicable option. When the remaining bone is insufficient for supporting the dental implant, alveolar bone augmentation can stably retain implant, and its prognosis will be favorable. The maxillary sinus elevation with bone graft procedure is relatively easy and has a good prognosis. In these cases, remaining maxillary teeth were extracted, bone grafts with maxillary sinus elevations were performed at the bilateral maxillary molar region at a onemonth interval, and ten implants were placed seven months later. Two weeks after the sinus elevation surgery, the sutures were removed. Postoperative healing was normal without any inflammatory reaction, and the implant-supported fixed prosthesis was delivered to the patient. The patient was satisfied with the results from the esthetic and functional aspects. Implant surgery to rehabilitate the edentulous area are a useful and attractive procedure. It is helpful to increase the implant stability by sinus grafting bone. - COLLAPSE
    June 2020