• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.110-116
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• 2010

Purpose: The X-ray attenuation coefficient based on CT images is used for attenuation correction in PET/CT. The polychromatic X-ray beam can introduce beam-hardening artifact on CT images. The aims of the study were to evaluate the effect of dental metal prostheses in phantom and patients on apparent tracer activity measured with PET/CT when using CT attenuation correction. Materials and Methods: 40 normal patients (mean age $54{\pm}12$) was scanned between Jan and Feb 2010. NEMA(National Electrical Manufactures Association) PET $Phantom^{TM}$ (NU2-1994) was filled with $^{18}F$-FDG injected into the water that insert implant and metal prostheses dental cast. Region of interest were drawn in non-artifact region, bright steak artifact region and dark streak artifact region on the same transaxial CT and PET slices. Patients and phantom with dental metal prostheses and dental implant were evaluated the change rate of CT Number and $SUV_{mean}$ in PET/CT. A paired t-test was performed to compare the ratio and the difference of the calculated values. Results: In patients with dental metal prostheses, $SUV_{mean}$ was reduced 19.64% (p<0.05) in the non-steak artifact region than the brightstreak artifact region whereas was increased 90.1% (p>0.05) in the non-steak artifact region than the dark streak artifact region. In phantom with dental metal prostheses, $SUV_{mean}$ was reduced 18.1% (p<0.05) in the non-steak artifact region than the bright streak artifact region whereas was increased 18.0% (p>0.05) in the non-steak artifact region than the dark streak artifact region. In patients with dental implant, $SUV_{mean}$ was increased 19.1% (p<0.05) in the non-steak artifact region than the bright streak artifact region whereas was increased 96.62% (p>0.05) in the non-steak artifact region than the dark streak artifact region. In phantom with dental implant, $SUV_{mean}$ was increased 14.4% (p<0.05) in the non-steak artifact region than the bright streak artifact region whereas was increased 7.0% (p>0.05) in the non-steak artifact region than the dark streak artifact region. Conclusion: When CT is used for attenuation correction in patients with dental metal prostheses, 19.1% reduced $SUV_{mean}$ is anticipated in the dark streak artifact region on CT images. The dark streak artifacts of CT by dental metal prostheses may cause false negative finding in PET/CT. We recommend that the non-attenuation corrected PET images also be evaluated for clinical use.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.3
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• pp.375-381
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• 2000

The conventional approach for replacing missing maxillary lateral incisors dictates the placement of either a conventional porcelain-fused-to-metal (PFM)bridge, resin-bonded fixed partial denture, or single implant prosthesis. However, several appearance-related disadvantages have been reported in the use of a prosthesis which incorporates a metal substructure. To address these limitations, metal -free restorative alternatives have been recently developed to expand the clinical options when fabrication of these prostheses is indicated. This clinical report describes the treatment of patients with a missing maxillary lateral incisor where the dentition was non-invasively restored with resin-bonded fixed partial denture(RBFPD) using In-Ceram and Targis-Vectris system.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.499-518
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• 2003

The surface characteristics of titanium have been shown to have an important role in contact ossseointegration around the implant. Anodizing at high voltage produces microporous structure and increases thickness of surface titanium dioxide layer. The aim of present study was to analyse the response of rat calvarial osteoblast cell to commercially pure titanium and Ti-6A1-4V anodized in 0.06 mol/l ${\beta}$-glycerophosphate and 0.03 mol/l sodium acetate. In this study, rat calvarial osteoblasts were used to assay for cell viability and cell proliferation on the implant surface at 1,2,4,7 days. 1. Surface roughness was 1.256${\mu}m$ at 200V, and 1.745${\mu}m$ at 300V. 2. The thickness of titanium oxide layer was increased 1 ${\mu}m$ with the increase of 50V. 3. The proliferation rate of osteoblastic cells was increased with the increase of the surface roughness and the thickness of titanium oxide layer. 4. There was no difference in cell viability and cell proliferation between commercially pure titanium and Ti-6A1-4V anodized at the same condition. In conclusion, the titanium surface modified by anodizing was biocompatible, produced enhanced osteoblastic response. The reasons of enhanced osteoblast response might be due to reduced metal ion release by thickened and stabilized titanium dioxide layer and microporous rough structures.

• The Journal of Advanced Prosthodontics
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• v.8 no.3
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• pp.207-213
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• 2016

PURPOSE. A recently introduced direct drill-guiding implant surgery system features minimal tolerance of surgical instruments in the metal sleeve by using shank-modified drills and a sleeve-incorporated stereolithographic guide template. The purpose of this study was to evaluate the accuracy of this new guided surgery system in partially edentulous patients using geometric analyses. MATERIALS AND METHODS. For the study, 21 implants were placed in 11 consecutive patients using the direct drill-guiding implant surgery system. The stereolithographic surgical guide was fabricated using cone-beam computed tomography, digital scanning, computer-aided design and computer-assisted manufacturing, and additive manufacturing processes. After surgery, the positional and angular deviations between planned and placed implants were measured at the abutment level using implant-planning software. The Kruskal-Wallis test and Mann-Whitney U test were used to compare the deviations (${\alpha}=.05$). RESULTS. The mean horizontal deviations were 0.593 mm (SD 0.238) mesiodistally and 0.691 mm (SD 0.344) buccolingually. The mean vertical deviation was 0.925 mm (SD 0.376) occlusogingivally. The vertical deviation was significantly larger than the horizontal deviation (P=.018). The mean angular deviation was 2.024 degrees (SD 0.942) mesiodistally and 2.390 degrees (SD 1.142) buccolingually. CONCLUSION. The direct drill-guiding implant surgery system demonstrates high accuracy in placing implants. Use of the drill shank as the guiding component is an effective way for reducing tolerance.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.183-192
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• 2008

Modern dental reconstructions do not only aim at restoring the patient's mastication, but rather at improving general well-being and quality of life, especially in terms of esthetics. The media, the internet, advertising, and many other facts of society contribute to an increased cosmetic awareness. A 35-year-old male patient presented with as follows: 1) the porcelain fracture of ceramo-metal restoration on #11 and #23, 2) the inclination of incisal plane to horizontal reference plane, 3) the dental midline deviation to facial midline, and 4) the lack of symmetry on upper anterior dentition. The patient requested an aesthetic improvement using fixed prosthodontics including implant-supported restorations. In the upper anterior region, one of the goals of the conventional as well as implant prosthesis is to achieve restorations with the dental attractiveness and beauty in the respect of dental, dentofacial, and facial compositions. This case report presents geometrically improvement of dental esthetics using conventional and implant prosthesis with soft and hard tissue augmentation.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.3
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• pp.244-249
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• 2015

With the recent progress of digital technology, the computer guided surgery utilizing a guide template in the placement of implant has been actively performed, and the method employing the intraoral scanner at the implant prosthesis introduced. Fabrication method of the guide template can be largely classified into design-related rapid prototyping (RP) system and vector milling system, and each of the method has its own weakness in the clinical application despite of excellent accuracy. Thus, in this case study, a working model was fabricated by the wax RP technology using images acquired by CBCT and an intraoral scanner, and the metal bushing was picked up with orthodontic resin cast upon the wax model. Using this method, a surgical guide template was fabricated and used in surgery. From this, we could obtain a satisfactory outcome clinically in the implant placement and the fabrication of the final prostheses and thus report this case herein.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.171-175
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• 2019

Mandible with severe alveolar bone atrophy poses a significant challenge in terms of reproducing clinically acceptable anatomy for a removable prosthesis. To overcome this potential complication, altered cast impression technique is often recommended to capture accurate and functional gingiva tissues. It becomes possible to get proper anchors functional impression by placing 2 implants crowns which were impossible in previous implant overdenture impression technique. In this case, an 80-year old female patient with severe mandibular ridge atrophy was treated with an implant-assisted removable partial denture with two implant crowns on the canine area. An altered cast impression was taken with an individual tray on a metal framework of removable partial denture on both posterior edentulous areas. The patient was satisfied with the final prosthesis after failure of 2 previous prostheses. Clinician had a difficult time to manage disabled patient and patient were suffered with ill-fitting denture due to inaccurate impression in conventional overdenture condition. The oral rehabilitation was completed with placing 2 implants as proper anchor.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.288-295
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• 2019

Passive fit of prosthesis is an essential property of implant supported prosthesis for long term success and minimization of complications. And the property is determined mostly by fabrication procedure. There were limitations of extensive implant prosthesis because conventional casting method generate contraction error of long span prosthesis. However, Computer-aided design/Computer-aided manufacturing (CAD/CAM) technology of 3D printing and milling metal framework can overcome those limitations. This case is a full mouth rehabilitation using extensive implant fixed prosthesis. Removable interim prosthesis was made for esthetic, functional evaluation and a guide for implant insertion. After the insertion, implant fixed interim prosthesis was delivered. After additional evaluation and adjustment, final prosthesis was designed with CAD, the fabricated with CAM. Milling technique was used for anterior screw type implant superstructure and 3D printing technique was used for the anterior and posterior implant copings. Fit of the final restoration was favorable. The practitioner and patient were both esthetically and functionally satisfied with the final result.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.201-208
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• 2008

Statement of problem: A new implant impression technique which use abutments as impression coping, and use resin cement as a splinting material was described. Accuracy of this technique was compared with conventional closed tray and resin splinted open tray technique for a $15^{\circ}$ angled 3-implant model Material and methods: A dental stone master model with 3 linearly positioned implant analogue and a reference framework which was passively fitted to it were fabricated. The center analogue was perpendicular to the plane of model and the outer analogues had a $15^{\circ}$angulation forward or backward. 10 closed tray impressions, 10 resin splinted open tray impressions, 10 abutment-resin framework cementation impressions and 10 abutment-metal framework cementation impressions were made with additional silicone material and poured with dental stone. A light microscope with image processing was used to record the vertical gap dimension between reference framework and analogue of duplicated cast made with each 4 impression techniques. Statistical analysis used one-way ANOVA with post-hoc tests Tukey test of .05 level of significance Results: Significant difference in the vertical gap dimension was found between closed tray technique; 74.3 (${\pm}33.4$)${\mu}m$ and resin splinted open tray technique, and two other new technique. (P<.05) Abutment-metal framework cementation technique;42.5 (${\pm}11.9$)${\mu}m$ was significantly different from resin splinted open tray technique. (P<.05) Abutmentresin framework cementation technique;51.0 (${\pm}14.1$)${\mu}m$ did not differ significantly from resin splinted open tray technique;50.3 (${\pm}16.9$)${\mu}m$. (P>.05) Conclusion: Within limitations of this study, the accuracy of implant level impressions of resin splinted open tray technique was superior to that of closed tray technique. A new technique using abutment and metal framework cementation was more accurate than resin splinted open tray technique.

• The Journal of Advanced Prosthodontics
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• v.3 no.2
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• pp.96-100
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• 2011

An 18-year-old male presented severe hypodontia due to hypohidrotic ectodermal dysplasia was treated with Le Fort I maxillary osteotomy with simultaneous sinus floor augmentation using the mixture of cortical autogenous bone graft harvested from iliac crest and organic Bio-Oss to position the maxilla in a right occlusal plane with respect to the mandible, and to construct adequate bone volume at posterior maxilla allowing proper implant placement. Due to the poor bone quality at other sites, ridge augmentation with onlay graft was done to construct adequate bone volume allowing proper implant placement, using tissue harvested from the iliac bone. Seven implants were placed in the maxilla and 7 implants were inserted in the mandible and screw-retained metal ceramic FPDs were fabricated. The two year follow up data showed that dental implants should be considered as a good treatment modality for patients with ectodermal dysplasia.