• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.305-310
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• 2017

Nowadays, the development of dental scanner and CAD/CAM technology can facilitate the fabrication of hybrid prosthesis. Double scanning technique, scanning a trial prosthesis and master model, made it possible to realize virtual design and simplify the laboratory work. Instead of using the metal or zirconia framework with composite, ceramic or denture tooth, the new high performance polymer Polyetherketoneketone (Pekkton, Cendres+$M{\acute{e}}taux$, Biel, Switzerland) as a framework with Polymethyl methacrylate (PMMA) veneering teeth (Visio-lign, Bredent, Senden, Germany) was used in this case. This case report showed an acceptable treatment outcome and satisfaction of patient using Pekkton and Visio-lign. However, long term clinical evaluation is needed.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.154-166
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• 2004

Statement of problem: In distal extension removable partial denture, the preservation of health of abutment teeth are very important, but they are always subjected to unfavorable stress. Purpose: The purpose of this study was performed to investigate the effects of abutment splinting and design of direct retainer on the stress distribution of abutments in unilateral distal extension removable partial dentures. Material and method: Abutments were splinted by different method. In group 1, autment teeth were not splinted, in group 2, canine and 1st premolar were splinted, and in group 3, canine, 1st and 2nd premolars were all splinted. Three different types of direct retainer such as Akers clasp, RPI clasp, and wrought wire clasp were designed. Strain was measured with Switch & Balance Unit(SB-10, Measurement Group Instruments Division, Raleigh USA) and Strain Indicator(P-3500, Measurement Group Instruments Division, Raleigh, USA) 15kg of vertical and oblique loads was applied at central fossa of missing 2nd molar area. Results : The strain on lingual side of 2nd premolar was the greatest, and abutment splinting induced decrease of strain on buccolingual side of 2nd premolar. The strain of loaded area was decreased by abutment splinting and there was no statistical difference of strain between Group2 and Group 3, and strain on 2nd premolar in wrought wire clasp was the least. Conclusion: Within the limitations of this study, splinting of two distal abutment teeth is enough for stress distribution widely, and wrought wire clasp was more benefitable than others.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.150-165
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• 1998

For the purpose of evaluating the effect of both direct retainer design and bony absorption degree around abutment of indirect retainer on the supporting tissue of abutment of indirect retainer, dislodging force was transmitted to unilateral distal extension RPD bases. Analysis of stress distributed within the supporting tissue around abutment of indirect retainer was carried out. Using three-dimensional photoelastic stress analysis method and the conclusion is a follows. 1. According to the extent of force which the direct retainer of the most distal abutment tooth, the amount of force transmitted to the abutment tooth of indirect retainer was small. 2. Of all the cases, Mandibular first premolar which was used abutment tooth of indirect retainer, buccal, mesial and distal sides represented compression stress and lingual side represented tensile stress. 3. The more bone resorption of abutment tooth of indirect retainer, the more distortion of buccal and distal side of abutment tooth was existed and the extent of compression stress which was existed and distal side to abutment tooth was large. 4. When the alveolar bone around the abutment with indircet retainer is normal. The amount of force transmitted on abutment with indirect retainer was small in the order of Akers clasp, RPA clasp, RPI clasp. 5. When the alveolar bone around the abutment with indirect retainer has been absorbed 20% and 30%, the amount of force transmitted on abutment with indirect retainer was small in the order of RPA calsp, RPI clasp, Akers clasp. 6. When denture is displaced, shape of the direct retainer reciprocating abutment affect much the function of indirect retainer.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.3
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• pp.243-253
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• 2009

This report described a technique utilizing a computer-aided design (CAD) /computer-aided machining (CAM) - guided surgical implant placement and prefabricated fixed complete denture for an immediately loaded restoration. A patient with an edentulous maxilla and mandible received 6 implants in maxilla and 6 implants in the mandible using CAD/CAM surgical templates. Prefabricated provisional maxillary and mandibular implant supported fixed prostheses were connected immediately after implant installation. Provisional prostheses were evaluated for aesthetics, function during 6 months. Definitive prostheses were fabricated.

• Imaging Science in Dentistry
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• v.45 no.1
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• pp.41-47
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• 2015

Purpose: This study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides. Material and Methods: Three gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturer's imaging software. The same measurements were then taken with the CBCT software. Results: The anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study. Conclusion: The proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

• The Journal of Advanced Prosthodontics
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• v.2 no.4
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• pp.134-141
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• 2010

PURPOSE. The objective of this study was to evaluate fracture strength of collarless metal-ceramic FPDs according to their metal coping designs. MATERIALS AND METHODS. Four different facial margin design groups were investigated. Group A was a coping with a thin facial metal collar, group B was a collarless coping with its facial metal to the shoulder, group C was a collarless coping with its facial metal 1 mm short of the shoulder, and group D was a collarless coping with its facial metal 2 mm short of the shoulder. Fifteen 3-unit collarless metal-ceramic FPDs were fabricated in each group. Finished FPDs were cemented to PBT (Polybutylene terephthalate) dies with resin cement. The fracture strength test was carried out using universal testing machine (Instron 4465, Instron Co., Norwood MA, USA) at a cross head speed of 0.5 mm/min. Aluminum foil folded to about 1 mm of thickness was inserted between the plunger tip and the incisal edge of the pontic. Vertical load was applied until catastrophic porcelain fracture occurred. RESULTS. The greater the bulk of unsupported facial shoulder porcelain was, the lower the fracture strength became. However, there were no significant differences between experimental groups (P > .05). CONCLUSION. All groups of collarless metal-ceramic FPDs had higher fracture strength than maximum incisive biting force. Modified collarless metal-ceramic FPD can be an alternative to all-ceramic FPDs in clinical situations.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.177-194
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• 1991

The purpose of this study was to analyze the magnitude and distribution of stress using a photoelastic model from a distal extension removable partial dentures with three kinds of mandibular major connectors, that is, lingual bar, linguoplate, and swing-lock attachment. A photoelastic model was made of the epoxy resin(PC-1) and hardener(PCH-1) and coated with plastic cement-1 (PC-1) at the lingual surface of the epoxy model and set with three kinds of chrome-cobalt removable partial dentures. A bilateral vertical load of 15kg to the middle portion of the metal bar crossing both the first molars of the right and the left, and a unilateral vertical load of 12.5kg to the right first molar were applied with the use of specially designed loading device and the reflective circular polariscope was used to analyze the photoelastic model under each condition. The following results were obtained : 1. When the bilateral vertical load was applied, the magnitude and distribution of the stress concentration of the edentulous area and the terminal abutment or adjacent teeth was in the order of lingual bar, linguoplate, swing-lock attachment. 2. When the unilateral vertical load was applied, the magnitude and distribution of the stress concentration of the edentulous area and the terminal abutment or adjacent teeth was in the order of lingual bar, linguoplate, swing-lock attachment. 3. When the unilateral vertical load was applied, the magnitude and distribution of the stress concentration of the termial abutment or adjacent teeth on the non-loaded side showed the least stress distribution in case of swing-lock attachment. 4. When the bilateral vertical load and the unilateral vertical load were applied the swing-lock attachment showed the mildest uniform stress distribution on the edentulous area and the alveolar bone around the abutment teeth.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.1-10
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• 2008

The purpose of this study was to compare the oral health status of elderly people living in nursing home with private home in Busan, Kimhae and Jinju in Gyeongnam province for development oral healthy policy of elderly people. 253 elderly subjects aged more than 65 in a hall for the aged and special medical treatment hospital are made up questions. The date was analysed using the SPSS 13.0 program. The obtained result were as follows. 1. 39.5 percent elder people recognize that their subjective oral health is not good. In the case of above three times in brushing tooth a day, 29 percent people are less their oral health is good. As the number of times of brushing tooth decreases, the percent feeling their oral status good decrease(p<.05). 2. The respondents who have visited the dentist within one year are less than people with no visit. Also the percent having a mind that their oral health status is good is higher in the respondents having scaling than them without scaling(p<.05). The respondents who answer that their diet is not bad is most in the ratio of people feeling subjective oral health status good(p<.001). 3. The portion of people feeling their oral status not healthy is highest in the respondents without tooth(p<.05). 4. Among the respondents answering their subjective oral health is not good, the some problem of conversation due to no tooth or denture and relation with others is issued each(p<.001). This study suggests that perceived toothbrusing frequency and periodic scaling with oral health among the elderly. The finding of this study will helpful to policy makers to design plants to increase the oral health related quality of life among the elderly.

• Journal of Technologic Dentistry
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• v.39 no.1
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• pp.35-42
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• 2017

Purpose: The purpose of this paper was to evaluate the occurrence of errors regarding adaptation by conducting a three-dimensional assessment comparing the bridge type dental restoration after the cutting process, which has multiple abutments, with a single type dental restoration. Methods: By using ten identical files obtained by scanning the master model, thirty designs were created consisting of ten maxillary right first premolars and ten maxillary right first molars with single crown abutments, along with ten bridge designs with the identical abutment. A 5-axis milling machine was used to produce the design file. The produced denture prostheses were scanned using a silicone replica for a STL file. An evaluation was conducted using 3D analysis software on the master model and each of the thirty data files. Results: The RMS value of the pre-molar (14) was $38.4{\pm}4{\mu}m$ for single and $54.7{\pm}6{\mu}m$ for bridge abutment; therefore, a statistically significant difference was observed for single and bridge designs although both shared the same abutment form (P<.05). Also, the RMS value of the molar (16) was $47.6{\pm}2{\mu}m$ and $56.6{\pm}5{\mu}m$ for the single and bridge designs, respectively, thereby presenting a statistically significant difference (P<.05). Conclusion: As a result, dental prosthesis fabricated using the single method presented better internal adaptation outcomes.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.354-361
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• 2011

There are still many limitations on fabricating dentures using digital method while computerized production of fixed prostheses utilizing intraoral scanner and CAD/CAM technology has propagated rapidly. Recently the digital solution of fabricating removable partial denture by applying haptic input device, electronic surveying, and rapid prototyping was introduced. In this case presentation, five patients were treated with surveyed crown and removable partial dentures by this digital solution. Fit of dentures was excellent except for one case which showed morphological difference between the actual teeth and that of master cast by the erroneous impression process. There also was not any problem of stability and retention after adaptation in the clinical setting.