EFECTS OF LATERAL GUIDANCE AND CHEWING PATTERN ON MASTICATORY MUSCLE ACTIVITY AND OCCLUSAL CONTACT / 대한치과보철학회지

This study was performed to investigate the influence of lateral guidance pattern and chewing pattern on masticatory muscle activity and occlusal contact pattern. Twenty-five patients with temporomandibular disorders and thirty students without temporomandibular disorders were selected for this study. Electromyographic examination and occlusal contact examination were performed simultaneously with Bio-Pak System(Bioresearch Inc.,U.S.A.) and T-Scan System(Tekscan Co., USA). The obtained results were as follows : 1. The EMG activity of masseter and anterior temporal muscle in patient group with canine guidance was higher than with non-canine guidance, but there was no significant difference(p>0.05). 2. The EMG activity of anterior temporal muscle in normal group with non-canine guidance was higher at preferred chewing side than at opposite side(p0.05). 5. The occlusal contact force at preferred chewing side was higher in patient group than in normal group(p<0.05).

A STUDY ON THE PRESSING ACCURACY OF THE REUSED IPS-EMPRESS INGOT / 대한치과보철학회지

IPS-empress system is one of widely used all ceramic system. The purpose of this study was to determine the pressing accuracy of refused IPS%Empress ingot. 10 specimens were made using new ingot first, and using the rests of the specimen the another group of specimens were made next. Finally, the third group of specimens were made with same procedure mentioned above. The results obtained in this study were as follows ; 1. The pressing accuracy of the first group of specimen was 96.1%, that of the second group was 95.4%, and that of the third group was 95.4%. There was no statistical signifcance among them, that is, the reuse of the IPS-Empress ingot did not influence on the pressing accuracy. 2. the common site of the defect in pressed ingot was central area at the margin opposite of sprue hole.

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

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.