• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.61-69
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• 2020

Purpose: Zirconia fixed partial dentures with mandibular 2^nd premolar and 2^nd molar as abutments are fabricated and then the effects of inter-abutment distance on fracture resistance of zirconia fixed partial dentures is studied. Materials and Methods: The materials used in this study are Cameleon S zirconia block and S2 zirconia block, which are divided into CS Group and S2 Group applying different inter-abutment distance for each material, and the sintered zirconia fixed partial denture was luted to the epoxy resin die using a temporary luting cement, and then the fracture resistance was measured by placing a 6 mm diameter hardened steel ball on the occlusal surfaces of the pontics and applying pressure at a cross head speed of 1.0 mm/min on a universal testing machine with a load cell of 5.0 kN. Results: The fracture resistance of zirconia fixed partial dentures is not significantly affected by inter-abutment distance The fracture resistance of zirconia fixed partial dentures in CS Group was significantly higher in 15 mm of inter-abutment distance than in 13 mm and 17 mm of inter-abutment distance (P < 0.05). The fracture resistance of zirconia fixed partial dentures in S2 Group was not significantly different between the three groups (P > 0.05). Conclusion: The fracture resistance of zirconia fixed partial dentures with mandibular 2^nd premolar and 2^nd molar as abutments does not significantly affected by the inter-abutment distance.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.1
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• pp.11-20
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• 2004

Problem : The several studies were reported to the effects of individual tooth tray with the parallel tooth, but not reported to the effect of individual tooth tray with severe undercut in impression making. Purpose : The purpose of this study is to examine the effect of individual tooth tray; 1) the accuracy of impression in terms of distance. 2) reproducibility of pocket. Material and methods : In this study, a metal model with 3 teeth including tooth prepared 30-degree undercut and gingival crevice of the depth 5mm, width 0.4mm was cast. Impressions of the metal model were taken in 5 times used 4 kinds of impression materials with individual tooth tray and another impression taking were made with conventional method without individual tooth, used same materials, procedure. The stone models were made. Distances between abutments were measured with a Micromeasurescoup-mm. Result : The following results were obtained ; 1. In the comparisonof inter-abutment distance between parallel tooth without individual tooth tray, 4elastomeric materials have not significant difference to the metal model(p>0.05). 2. In the comparisonof inter-abutment distance with undercut tooth without individual tooth tray, 4elastomeric materials have a significant difference to the metal model(p<0.05), especially polyether's dimensional change is large. 3. If individual tooth tray was used to take impression in abutment teeth with severe undercut, more stable results was achieved easily than conventional method. (p>0.05). 4. It is not true that the pressure of impression material with individual tooth tray increased to gingival sulcus. Conclusion : By the results, I knew the fact that individual tooth tray was useful impression method on the teeth with severe undercut for the dimensional stability. Also, I could not confirm the fact that individual tooth tray would increase the penetrating pressure into cervice.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.4
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• pp.222-231
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• 2020

To use the external connection implant (EXT) appropriately, the inter-implant distance should be carefully considered during placement, and the bones raised above the implants should be trimmed during the second surgery. The hex abutment is more useful than the non-hex abutment. EXT is particularly useful when the inter-arch space is limited. The tissue level (TL, internal butt connection) implant has a biomechanical advantage of coronal wall thickness and a biological advantage of an inherent transmucosal smooth surface. During TL implant restoration, an abutment can be selected using the abutment and fixture margins with considerations for the inter-arch space. Since no single type of implant can satisfy all the cases, it is necessary to select the appropriate type, considering the occlusal force and the bone condition.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.238-247
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• 2004

Statement of problem: Major objective in making on implant-supported prosthesis is the production of superstructure that exhibits a passive fit when connected to multiple abutments. One requirement to ensure passive fit is to make an accurate impression. Purpose : The purpose of this study was to compare the accuracy of master cast fabricated by using different impression methods at the different impression levels. Material and method: The master model used in this study was resin block having low implant analogs. Impression method studied were 1) direct method on fxiture level (Group FIX-D), 2) indirect method on fixture level(Group FIX-I), 3) modified indirect method on fixture level(Group FIX-M), 4) direct method on abutment level(Group AB-D) and 5) indirect method on abutment level(Group AB-I). Each of the five groups took 10 impressions. Fifty impressions were made for master cast by using Impregum $F^{(R)}$ impression material loaded on individual tray. Three dimensional measuring microscope was used to measure the inter-implant distance. Error rate of each inter-implant distance were calculated and evaluated. Results : The results were as follows. 1. Group FIX exhibited higher accuracy than group AB. 2. In group FIX, modified indirect method showed the highest accuracy, while indirect method showed the lowest accuracy. In group Ab, indirect method showed the higher accuracy than direct method. 3. Group FIX showed larger horizontal error than group AB. But, group AB showed the larger vertical error than group FIX. 4. Group Fix-M showed smallest vertical and horizontal error. Conclusion: An impression method have more effect on accuracy of master model than an impression level. A modified indirect method showed smallest vertical and horizontal error.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.1
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• pp.63-72
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• 2006

Purpose: The purpose of this study was to compare the accuracy of master cast fabricated by using different impression methods at the different impression levels. Material and Method: The master model used in this study was resin block having low implant analogs. Impression method studied were 1) direct method on future level (Group FIX-D), 2) Indirect method on fixture level(Group FIX-I), 3) Modified indirect method on fixture level(Group FD(-M), 4) Direct method on abutment level(Group AB-D) and 5) Indirect method on abutment level(Group AB-I). Each of the five groups took 10 impressions. Fifty impressions were made for master cast by using Impregum $F^(R)$ impression material loaded on individual tray. Three dimensional measuring microscope was used to measure the inter-implant distance. Error rate of each inter-implant distance were calculated and evaluated. Results: The results were as follows. 1. Group FIX exhibited higher accuracy than group AB. 2 In group FIX, modified indirect method showed the highest accuracy, while indirect method showed the lowest accuracy. In group Ab, indirect method showed the higher accuracy than direct method. 3. Group FIX showed larger horizontal error than group AB. But, group AB showed the larger vertical error than group FIX. 4. Group Fix-M showed smallest vertical and horizontal error.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.124-129
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• 2017

PURPOSE. This study evaluated the effect of span length on the adaptation of implant-supported cobalt chromium frameworks fabricated by three techniques. MATERIALS AND METHODS. Models with two solid abutment analogs at different inter-abutment distances were digitized using a laboratory scanner. Frameworks of two-, three-, and four-unit fixed prostheses were designed by a computer. Six dots with a diameter of 0.2 mm were preset on the surface of each framework. A total of 54 implant-supported cobalt chromium frameworks were fabricated by milling, selective laser melting (SLM), and cast techniques. The frameworks were scanned and exported as Stereolithography files. Distances between two dots in X, Y, and Z coordinates were measured in both the designed and fabricated frameworks. Marginal gaps between the framework and the abutments were also evaluated by impression replica method. RESULTS. In terms of distance measurement, significant differences were found between three- and four-unit frameworks, as well as between two- and four-unit frameworks prepared by milling technique (P<.05). Significant differences were also noted between two- and three-unit frameworks, as well as between two- and four-unit frameworks prepared by cast technique (P<.05). The milling technique presented smaller differences than the SLM technique, and the SLM technique showed smaller differences than the cast technique at any unit prostheses (P<.05). Evaluation with the impression replica method indicated significant differences among the span lengths for any fabrication method (P<.05), as well as among the fabrication methods at any unit prostheses (P<.05). CONCLUSION. The adaptation of implant-supported cobalt chromium frameworks was affected by the span length and fabrication method.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.2
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• pp.320-334
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• 1996

Dental cast and die materials are essential material using in almost dental prsthodontic procedure and it's most important requirement is accuracy for reqorducing the oral anatomical structures. In this study, 5 abutments A, B, C, D, E were fabricated on the metal master model to simulate the arch form and specimens were poured with 4 cast materials. Inter-abutment distances, A-B, A-C, A-D, A-E, B-C, B-D were calculated using the photo-scanning and the deviations from the metal master model were also evaluated. The results were as follows; 1. The distance between A-B, A-C, A-D, A-E, B-C, B-D of the abutments A, B, C, D, E of each cast material was calculated. And after comparing the deviations between the metal master model. $Fujirock^{(R)}$ showed the lowest value with $0.20{\pm}0.22mm$, and the deviation increased in the order of $Suprastone^{(R)}$, Epoxy $Die^{(R)}$, Die $Keen^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and Epoxy $Die^{(R)}$, Die $Keen^{(R)}$. 2. In each calculation area, the difference in measurements between cast material and metal master model showed singificant difference between A-B and Cross arch measure-ments of A-D, B-D, A-E(p<0.05). 3. The difference in measurements between cast material and metal master model in the A-B area showed $Fujirock^{(R)}$ to be the lowest with $0.05{\pm}0.04$mm and increased in the order of Die $Keen^{(R)}$, $Suprastone^{(R)}$, Epoxy $Dies^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and $Suprastone^{(R)}$, Epoxy $Die^{(R)}$ (p<0.05). 4. The difference in measurements between cast material and metal master model in the B-C area showed $Fujirock^{(R)}$ to bo the lowest with $0.17{\pm}0.11$mm and increased in the order of $Suprastone^{(R)}$, Die $Keen^{(R)}$, Epoxy $Dies^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and Die $Keen^{(R)}$, Epoxy $Die^{(R)}$(p<0.05). 5. The difference in measurements between cast material and metal master model in the B-D area showed $Fujirock^{(R)}$ to bo the lowest with $0.13{\pm}0.07$mm, Epoxy $Dies^{(R)}$and increased in the order of $Suprastone^{(R)}$, Die $Keen^{(R)}$. There was significant difference between $Fuji-rock^{(R)}$ and Die Keen(p<0.05). 6. In this experiment, Epoxy $Dies^{(R)}$ showed mean contraction in every calculation area. And when reconstruction cross arch restorations it is thought that distortion should be considered in every cast material.