Journal Detail Information

1

Cite

Share

A THREE DIMENSIONAL PHOTOELASTIC STRESS ANALYSIS OF OMPLANT-SUPPORTED MANDIBULAR OVERDENTURE ACCORDING TO IMPLANT NUMBER AND ATTACHMENT TYPE.

Sang Hoon HAN ; Yoon Sup TAE ; Tae Ho JIN ; Hye Won CHO

The Journal of Korean Academy of Prosthodontics.1997;35(3):577-608.

The purpose of this study is to evaluate the stress distribution in the bone around dental implants supporting mandibular overdenture according to the number of implant and the type of attachment. Two or four implants were placed in an edentulous mandibular model and three dimensional photoelastic stress analysis was carried out to measure the fringe order around the implant supporting structure and also to calculate principle stress components at cervical area of each implant. The attachments tested were rigid and resilient type of Dolder bar, Round bar, Hader bar and Dal-Ro attachment. The results were as follows; 1. In 2-implant supported overdenture using Round bar, Hader bar, and Dal-Ro attachment, compressive stress pattern was observed on the supporting structure of implant on loaded side, while tensile stress pattern in unloaded side. 2. In 2-implant supported overdenture using Dolder bar, the rigid Dolder bar shared the occlusal loads between 2 implants in a more favorable manner than was exhibited by the resilient type, while the resilient type placed a more stress on the distocervical area of the implant on the loaded side. But compressive stress pattern was observed in both the loaded and unloaded sides in either case. 3. In 2-implant supported overdenture, rigid and resilient type of Dolder bar exhibited more cross arch involvement than the Round bar, Hader bar, or Dal-Ro attachment. 4. In 4-implant supported overdenture using resilient Dolder bar and Hader bar, stress turned out to be distributed evenly among the implants between loaded and unloaded side, but ther was no reduction in the magnitude of the stress in the surrounding structure of implant contratry to 2-implant supported overdenture.. 5. The stress pattern at cervical area of implant was different with the number of implant or the type of attachment but the overload, harmful to surrounding structure of implant, was not observed.
Dental Implants ; Denture, Overlay*

2

Cite

Share

EFFECTOF SOLDERING CONDITION ON THE TENSILE STRENGTH TITANIUM SOLDER JOINT WITH 14K GOLD SOLDER.

Jeoung Ho CHOI ; Tae Jo KIM ; Kwang Yeob SONG ; Charn Woon PARK

The Journal of Korean Academy of Prosthodontics.1997;35(3):566-576.

This study was performed to evaluate the tensile strength of solder joint in titanium and the wettability of 14K gold solder on titanium. Two pieces of titanium rod 30 mm in length and 3mm in diameter were butt-soldered with a 14K gold solder using the electric resistance heating under flux-argon atmosphere, the infrared heating under argon atmosphere, and the infrared heating under vacuum-argon atmosphere. A tensile test was performed at a crosshead speed of 0.5mm/min, and fractere surfaces were examined by SEM. To evaluate the wettability of 14K gold solder on titanium, titanium plates of a 17x17x1mm were polished with #80-#2000 emery papers, and the spreading areas of solder 10mg were measures by heating at 840 * for 60 seconds. The solder-matrix interface regions were etched by the solution of 10% KCN-10%(NH4)2S2O8, and analyzed by EPMA. The results obtained were summarized as follows: 1. The maximun tensile strength was obtained when the titanium surface was polished with #2000 emery paper and soldered using the electric resistance heating under fluxargon atmosphere. Soldering strengths showed the significant difference between the electric resistance heating and the infrared heating(p<0.05). 2. The fracture surfaces showed the aspect of brittle fracture, and the failure developed along the interfaces of solder-matrix reaction zone. 3. The EPMA data for the solder-matrix interface region revealed that the diffusion of Au and Cu occurred to the titanium matrix, and the reaction zone showed the higher contents of Au, Cu and Ti than others.
Argon ; Atmosphere ; Diffusion ; Electric Impedance ; Heating ; Hot Temperature ; Joints* ; Tensile Strength* ; Titanium* ; Wettability

3

Cite

Share

BICOMPATIBILITY OF BICOMTALS IN RABBIT BONE.

Chong Hyun HAN ; Seong joo HOE ; Chong Pyong CHUNG ; Young KU ; In Chul RHYU ; Yong Chang CHOI

The Journal of Korean Academy of Prosthodontics.1997;35(3):557-565.

Screw-shaped implants of commercially pure (c.p.) titanium, c.p. niobium, c.p. zirconium, and stainless(Sus 304) were inserted in the rabbit tibial over 12 weeks of follow-up. New developed torque gauge instrument was used to evaluate the implant holding power and a image analysis program coupled to a microscope was used for histomorphometry. The three best consecutive threads of each implant were measured. Quantitative analyses at 12 weeks revealed a partial bone contact to the four kinds investigated metals. There were no obvious adverse tissue reactions to any of the biomaterials. At 12 weeks the average removal torques for titanium, niobium and zirconium were better than that needed for Sus 304 screws, on the other hand high score of bony contact ratio of titanium and niobium were showed in comparison to those of zirconium and Sus 304. There was no significant differences in the amount of interfacial bone of zirconium and Sus 304 whereas there was significant differences in the torque forces of niobium and Sus 304. Three months after implant insertion, the average removal torque was 6.64 Ncm for the titanium, 6.57 Ncm for the niobium, 6.38 Ncm for the zirconium, and 4.25 Ncm for the Sus 304. On average bone contacts there were 51.24% in the titanium, 48.19% in the niobium, 31.79% in the zirconium, 23.54% in Sus 304. Biocompatibility of the titanium, niobium and zirconium was acceptable level in comparison to the Sus 304.
Biocompatible Materials ; Follow-Up Studies ; Hand ; Metals ; Niobium ; Titanium ; Torque ; Zirconium

4

Cite

Share

THE CLINICAL STUDY ON SHORT TERM PROGNOSIS OF IN-CERAM ALUMINA BRIDGE RESTORATION.

Byung Woan JO ; Jae bum PARK ; Jye Jynn ANN

The Journal of Korean Academy of Prosthodontics.1997;35(3):544-556.

All ceramic restorations except In-Ceram Alumina system gave a good esthetics and an exellent marginal fidelity. The flexural strength of them had about 150MPa, so the indication is only single crown. By using In-ceram Alumina System(450MPa), it is thought to be possible to construct bridge for its high flexural strength. But the prognosis is unclear. The purposes of this study are to clear short term prognosis of In-Ceram bridge restorations, to elucidate its clinical significance. Among 22 In-Ceram Bridge restored in our department, 11 In-Ceram bridges with follow up were used. The period of placement is from 1 to 18 months. The results were as follow : 1. Among follow up 11 bridges, 2 bridges were fractured. One is 4 unit in maxillary lateral incisors, the other is 3 unit bridge in maxillary canine and premolar. Including 11 bridge without follow up, failure rate is very low(2/22). 2. The fracture sites are connector areas between abutment and pontic. To maintain In-Ceram bridge for long term period, it is needed to remove the nonphysiologic occlusal force and to have sufficient thickness of alumina core. For estabilishing clinical use of In-Ceram bridges, it is thought to need clinical research during long term period.
Aluminum Oxide* ; Bicuspid ; Bite Force ; Ceramics ; Crowns ; Denture, Partial, Fixed ; Esthetics ; Follow-Up Studies ; Incisor ; Prognosis*

5

Cite

Share

A STUDY OF IMPRESSION TECHNIQUE USING PUTTY MATERIAL OF PVS IMPRESSION MATERIAL.

Young Chan JEON ; Kyung soo NAH

The Journal of Korean Academy of Prosthodontics.1997;35(3):535-543.

In order to compare the accuracy of impression technique using the addition silicone putty and improved heavy body material, impression were taken for the natural 6 maxillary anterior teeth, and for the metal mast model that has full arch shape with 4 cylindrical abutment teeth, Marginal gingiva was retracted by routine method using retraction cord, and two techniques were tried to compare the length of impression materials in the gingival sulcus. This was aimed to see the effect of viscosity and hydraulic pressure of impression materials for the subgingival impression. Impressions for the full arch-shaped metal master model were taken to compare the linear stability of the different impression materials and their related techniques. The conclusions were as belows : 1. The one-step impression technique showed longer extension of impression material in gingival sulcus than two-step impression technique. 2. High viscosity and hydraulic pressure of impression material were useful to take subgingival impression. 3. There was no statistically significant difference for the two-dimensional accuracy of impression technique, but two-step technique showed better trend than one-step technique.
Gingiva ; Silicones ; Tooth ; Viscosity

6

Cite

Share

THREE DIMENSIONAL FINITE ELEMENT STRESS ANALYSIS OF THE MANDIBULAR CONDYLE DURING UNILATERAL CLENCHING.

Do Hyun NAM ; Seong Joo HOE ; Kwang Nam KIM

The Journal of Korean Academy of Prosthodontics.1997;35(3):517-534.

It has been held that excessive mechanical forces to the osseous and soft tissues of the TMJ result in joint dysfunction. Understanding the stress pattern on TMJ is very important in TMJ research. But, it is very difficult to measure directly the biomechanical stress distribution in the TMJ during functional movement was studied through animal experiment or mathematical model . It was observed and compared the stress distribution occuring in the working and balancing condyle when lower right canine, lower right first molar and lower right second molar were clenched by the three dimensional finite element analysis. Also, stress distribution in the working and balancing condyles were observed and compared when 20 forward and buccal bite forces were applied to the first molar The results were as follows : 1. Stress distribution in the condyles during unilateral clenching of the first molar, second molar, canine showed no difference. In the working condyle, tensile force was concentrated on the lateral aspect of the condylar articular surface and condylar neck. And compressive force was concentrated on the anteromedial and lateral aspect of condyle. In the balancing condyle, tensile and compressive force was concentrated on the lateral aspect of the condylar articular surface and stress transmission to the temporal bone was not observed. 2. When lateral force were applied to the first molar, tensile force were concentrated on the medial aspect of the condylar neck and condylar posterior surface in working and balancing condyle. Compressive force was concentrated on the anteromedial and lateral surface of condyle and stress transmission to the temporal bone was not observed. 3. During unilateral clenching, stress in the working condyle decreased as the occlusal load moved posteriorly while the stress in the balancing condyle increased when lateral forces were applied to the first molar, the incremental amount of stress was greater than vertical load. 4. During unilateral clenching, the average balancing/ working stress ratio was 2.52. There was a greater concentration of stress in the balancing condyle. The ratio increased at the occlusal load moved posteriorly and decreased considerably when lateral forces were applied to the first molar
Animal Experimentation ; Bite Force ; Finite Element Analysis ; Joints ; Mandibular Condyle* ; Models, Theoretical ; Molar ; Neck ; Temporal Bone ; Temporomandibular Joint

7

Cite

Share

STUDY OF THE EFFECT OF ULTRASONIC INSTRUMENTATION ON BOND STRENGTH OF SEVERAL DENTAL CEMENTS.

Woo Sang KIM ; Ju Hwan LIM ; In Ho CHO

The Journal of Korean Academy of Prosthodontics.1997;35(3):504-516.

Ultrasonic instruments transfer electrical energy to mechanical energy resulting in vibration used for various dental treatments. If we could know the effect of ultrasonic instruments on the dental cements within the cast crown, we could take care when conducting periodontal surgery and when using the ultrasonic instruments to remove cast crown, it would be much more convenient. The purpose of this study was to compare the bond strength of several dental cements according to ultrasonic instrumentation time In this study 4 types of cements were used to cement the specimens. They were treated with ultrasonic instrumentation for 0-5 minutes and the change in bond strength were statistically compared The results were as follows : 1. The tensile bond strength of zinc phosphate cement decreased according to the increase in time of ultrasonic instrument and showed significant differance between 0 minutes and the others and between 1 minute and 2,3,4,5 minutes (P<0.05) 2. The tensile bond strength of polycarboxylate cement decreased according to the increase in time of ultrasonic instrument and showed significant differance between 5 minutes and the others and between 4 minute and 0 minutes (P<0.05) 3. The tensile bond strength of zinc phosphate cement decreased according to the increase in time of ultrasonic instrument and showed significant differance between 5 minutes and the others (P<0.05) 4. The tensile bond strength of resin cement showed no statistically differences according to the ultrasonic instrumentation time In conclusion, it this considered that zinc phosphate cement is most affected by ultrasonic instrumentations and resin cement is the least affected. When using ultrasonic instruments the result above should be used as an index.
Crowns ; Dental Cements* ; Polycarboxylate Cement ; Resin Cements ; Ultrasonics* ; Vibration ; Zinc Phosphate Cement

8

Cite

Share

A PHOTOELASTIC ANALYSIS ON TOOTH SUPPORTING STRUCTURE AND RESIDUAL RIDGE ACCORDING TO DENTURE DESIGN FOR REMAINING MANDIBULAR CANINES.

Il Pyung KIM ; Joon Won KOH ; Tai Ho JIN

The Journal of Korean Academy of Prosthodontics.1997;35(3):486-503.

The purpose of this study was to evaluate the stress patterns developed in abutment and residual ridge according to removable denture design in case of remaining mandibular cannies The removable denture design in this study were as foolows ; 1. Removable partial denture with non-splinted abutment 2. Removable partial denture with splinted abutment 3. Overdenture with telescopic crown 4. Overdenture with O-Ring attachment 5. Overdenture with combination bar attachment Photoelastic stress analysis was used to record the isochromatic fringe patterns and to calculate principal stress components at measuring points. The results were as follows : 1. In case of removable partial denture with non-splinted abutment, stress of root area at the loaded side was the largest. No significant differences in stress of root area were observed between loaded side and unloaded side. 2. No significant differences in stress of residual ridge at the loaded side were observed between removable partial denture with splinted abutment and removable partial denture with non-splinted abutment 3. In case of combination bar attachment retained overdenture stress of root area was the largest and in case of telescopic crown retained overdenture stress of root area was lowest. 4. In case of attachment retained overdenture, stress of residual ridge was lower but stress of root area was larger than in case of removable partial denture
Crowns ; Denture Design* ; Denture, Overlay ; Denture, Partial, Removable ; Dentures* ; Periodontium* ; Splints ; Tooth*

9

Cite

Share

A STUDY OF THE TENSILE LOAD OF SEVERAL CLASPS ACCORDING TO VARIOUS UNDERCUT AREA.

Boong Hwan KIM ; Ju Hwan LIM ; In Ho CHO

The Journal of Korean Academy of Prosthodontics.1997;35(3):470-485.

A fundamental principle in clasp selection for a specific abutment is the reduction of the transmission of excessive forces to the abutment tooth. Those forces include tilting, tipping, and stress on the abutment tooth. The flexibility of a clasp was believed to directly affect the reduction of such forces. Opinions have been expressed concerning the proper type of clasp to be used to prevent stress on periodontium. In order to evaluate and compare the various designs of a clasp system, it is necessary to measure these force. This study compared the average measurements of forces required to dislodge three kinds of circumferential clasps having different amount of undercuts : the first with a round retentive arm, the second with a half round retentive arm, the third with a wrought wire retentive arm under tensile load. Three commonly used undercuts( 0.01, 0.02, 0.03 inch) were created on nine cast crowns, premolars and molars. The test was run six times for a same clasp. The means of tensile load required to dislodge each of the different clasps were compared statistically using the ANOVA test and multiple range test (Duncan test) The results were as follows. 1. The amount of tensile load of the wrought wire clasp was significa-ntly different from the cast round or half round clasp(P<0.05) 2. The more amount of the undercut, the more tensile load was need-ed to dislodge the clasp. There were significant difference among them(P<0.05) 3. The molar showed higher tensile load than the premolar, and there was significant difference(P<0.05) 4. The means of tensile load according to clasp types showed signific-ant differences at the molar between wrought wire clasp and cast clasp (P<0.05), but did not at the premolar
Arm ; Bicuspid ; Crowns ; Molar ; Periodontium ; Pliability ; Tooth

10

Cite

Share

THE TENSLE BOND STRENGTH AND ELASTIC MODULUS OF THE SOFT DENTURE LINING MATERIALS.

Byung Jin KIM ; Jun Won KOH ; Yong Keun LEE ; Hye Won CHO

The Journal of Korean Academy of Prosthodontics.1997;35(3):458-469.

This study was to compare the tensile bond strength and flexibility of four different soft liners(Coe Soft, Soft Relining, Soft Liner, Dura Base Soft) before & after thermocycling. Each soft liner was bonded to denture base resin block, and measured the tensile bond strength and modulus of elasticity using Universal testing machine. The mean value of tensile bond strength and modulus of elasticity for each experimental groups were statistically processed by SPSS(Statistical Package of Social Sience). The obtained results were as follows : 1. Dura Base Soft had the highest tensile bond strength and Coe Soft had the lowest tensile bond strength. 2. Coe Soft had the lowest modulus of elasticity, and Dura Base Soft had the highest modulus of elasticity of all the soft liners. 3. Thermocycling \ no effects on the tensile bond strength and modulus of elasticity of all the soft liners. 4. The failure modes of Coe Soft, Soft Relining, Soft Liner were mainly cohesive failure and that of Dura Base Soft were mainly adhesive failure.
Adhesives ; Denture Bases ; Dentures* ; Elastic Modulus* ; Pliability

DISPLAY OPTIONS

Cite

Share

Cite

Share

Cite

Share

Cite

Share

Cite

Share

Cite

Share

Cite

Share

Cite

Share

Cite

Share

Cite

Share