Mechanical properties of various types of dental alloys were evaluated by measuring tensile strength, Vicker's hardness, elongation, 0.2% proof stress and modulus of elasticity. Specimens were made from dental casting alloys, dental alloys for ceramometal, chromium cobalt base metal alloys for casting, and wrought base metal alloys, respectively.
It was expected that results of the test reveal the selection criteria of the dental alloys. The followings are the results of this test:
1. Heat treatment has effect upon 0.2% proof stress of the alloys, but does not have upon modulus of elasticity. Required Time-Temperature for heat treatment should be obeyed strictly.
2. Base metal alloy features high modulus of elasticity and low 0.2% proof stress thus its metal frame needs to be bulky when it is used for long-span bridge or adhesion bridge being subjected by severe occlusal force.
3. High-gold dental alloy for ceramometal may not be suitable for long-span bridge.
4. Chromium cobalt wrought alloy is suitable for the clasp of removable partial denture. But, care should be taken when the wrought wire is subjected to heat such as soldering. Severe heat treatment lowers 0.2% proof stress.
5. The Pt added high gold casting alloy, namely MAX G, has superior 0.2% proof stress and high modulus of elasticity among the gold casting alloys. This indicates that MAX G is suitable for long-span and adhesion bridges.
6. The gold alloys for ceramometal, namely TGB 50 and TGB 30, have superior 0.2% proof stress and modulus of elasticity among the gold alloys.

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The accuracy of the partial veneer crown margins is very important to dentists, and especially in the case of partial veneer crown which has longer margin, an incomplete or inaccurate marginal fit can be key to the longevity of case gold restorations.
Thirty extracted maxillary premolars with smooth axial surface free of defects were selected. An MOD onlay preparation was completed in each specimen, and a wax pattern was fabricated directly on the tooth. A type IV casting alloy was used. The effectiveness of four different marginal finishing techniques was evaluated. The results of this study indicate:
1) The adaptation of horizontal margins was significantly inferior to that of vertical margins prior to cementation.
2) About 2 μ for marginal opening was obtained by using the burnishing technique with Spratley knife and white polishing stone.
3) Burnishing produced a significant improvement in marginal adaptation when compared with the untouched margin. The burnishing technique with Spratley knife and white polishing stone was significantly superior.
4) Burnishing during cementation with Spratley knife and white polishing stone was not significantly effective.

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Posterior preparation should be designed so that the restoration fulfills the requirements of correct crown contour, precise monginal integrity and optimal occlusion. In this report, clinical significance of posterior preparation design is described.
In order to avoid the overcontoured crown morphology, it is essential to consider enough axial reduction and proper location of the finishing line for the posterior abutment teeth. Placing the finishing line on the enamel surface is the most common and widely accepted marginal design. In many cases, however, it is mandatory to locate crown margin on the root surface due to cervically mutilated condition of the abutment tooth. It should be reasonable to place finishing line at the level of gingival crest or infragingivally less than 0.5 mm deep so that marginal integrity and gingival health are maintained.
Thickness of the margin is also the factor which prevents distortion and secures long lasting restoration. This is especially important for the partial veneered crown which is not as strong as the full veneered crown under the severe occlusal stress.
In addition to those principles, the following factors have to be considered when desining preparation of posterior abutment teeth:
1. Occlusal plane if any abnormality or irregularity.
2. Position of the abutment teeth if any version,
3. Abutment for removable partial denture.
4. Hemisected or Bifurcated tooth.

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More than a decade has passed since the Bioceram Implant was introduced for clinical usage. The procedure for this implant has been improved year by year, and successfully applied by many dentists. The purpose of this report is to point out clinically important considerations which are essential to achieve implant.
Indications are carefully determined. Patient selection, local inspections including alveolar mucosa, alveolar bone, existing teeth, X-ray examinations and study casts are all important for the diagnosis. Type of Bioceram Implants has to be selected in accordance with bone morphology and number of missing teeth.
Surgical operation needs much attention to perform rigid osseousintegrated implant. Mucoperiosteal flap formation, bone drilling, and bone tapping are important steps requiring careful procedures.
Suprastructure fulfills the requirements of optimal occlusion and crown contour. It is prefered to provide organic occlusion so that the posteriors are protected from lateral force. Laboratory phase of fabrication of suprastructure is ver critical unless proper design is established.

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Etiologies and characteristics of collapsed occlusion were classified into 4 types, and procedures of oral rehabilitation for type 1 and type 2 were described in the previous report Part 1. Type 3 and type 4 cases are reported in this article.
Oral rehabilitation procedure for type 3 requires the most careful approach due to anterior prognathism and lost vertical dimension. Consecutive clinical steps have to be obeyed. Diagnosis including general and local examinations are necessary. Local examination consists of TMJ x-rays, Krough-Poulsen's muscle palpation, and MKG examination. Prior to prosthetic treatment, periodontic, endodontic and orthodontic treatments are mandatory so as to establish optimal physiologic condition of the mouth. Bite raising by trial and error is made by means of occlusal splints. After vertical dimension is established, provisional restorations are inserted so that any unfavorable reactions being caused by the forementioned treatment steps can be evaluated. Final restorations are fabricated by means of the gnathological procedure which secures exact duplication of the tooth anatomy and precise occlusion.
Type 4 is open-bite case which needs orthodontic or prosthodontic anterior correction, in general. The distal molar is the key to occlusion for treatment. Oral rehabilitation is mandatory to obtain functional and esthetic mouth condition.
Maintenance phase consisting of periodical recall and strict plaque control is very important for every case of oral rehabilitation.

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