Two systems that use the milling method for cutting restorations from uniformly baked ceramic blocks have been receiving considerable attention as epoch-making apparatuses for the fabrication of ceramic inlays. They are the Cerec system from Siemens, which uses current CAD/CAM techniques, and the Celay system from Microna, which applies the conventional lathe method and cuts a pattern fabricated in the mouth or on a model by the indirect method. We report here investigations that we carried out comparing the Cerec and Celay systems with the series of steps for the indirect method, and include comparisone with the direct method.

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Because it is possible with laser welding to weld two parent metals and obtain excellent mechanical properties and corrosion resistance, discoloration and weakening of the weld do not readily occur in the oral cavity.
Convention methods of welding similar and dissimilar metals include four that use solder (flame soldering, furnace soldering, infrared soldering and electrical resistance soldering) and the plasma wellding method that does not use solder. When these methods are employed, most of the time is spent with operations before the welding, such as investing the parts to fix their position and drying the investment material, and with operations after the welding, such as removal of the investment and post-treatment of the metal. Furthermore, adjusting the flame and management of temperature are in general based on the “feel” of the operator and requires experience and intuition.
A special characteristic of dental laboratory laser welding machines that ameliorate these problems is that, beyond improving the problems of conventional methods, it is possible with pure titanium and cobalt chrome alloys to weld both parent metals without changing the physical character of the welded portion. In addition, it is possible to rapidly perform stable, high quality operations under identical conditions.
In this report I carried out investigations comparing the weld strength of conventional flame and infrared soldering with that of a dental laser welding machine (Dental Laser DL 2000, Dentoram) that has many of these features.

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We have had several yers of clinical experience with casting dental titanium. Although we have learned various things about titanium casting during this time, we still encounter problems with this material and cannot say that we have fully mastered the technique. Although failures certainly arise with conventional dental castings and with industrial castings, is seems that rate of failures with dental titanium is even greater.
Although various reasons are given for casting failures and numerous countermeasures have been proposed, it should be pointed out that it is difficult to obtain a predictable outcome and that the countermeasures often do not hit the mark. Among these issues, we have centered our attention on the character of the molten liquid.

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There are many types of equipment of making acidic electrolyzed water from tap water. We utilized one of them : OXILYZER which is made by Miura Electric Co., Akita, Japan. Aqua oxidized water (AOW) is acidic water with a pH under 2.7 and is processed by electrolysis through a small NaCI mediated specific membrane. It has over 1, 100 mV of oxi-redx potential and includes Cl₂, OH·, O₃, ClO.
This acidic water has a strong bactericidal effect to bacteria and virus but there are few reports concerning its bactericidal activity to periodontopathic bacteria. We investigated the bactericidal effect of AOW to periodontopathic bacteria, two strains of Actinobacillus actinomycetemcomitans (Aa), two strains of Porphyromonas gingivalis (Pg) and a strain of Fusobacterium nucleatum (Fn) . Staphylococcus aureus (Sa) 209 P, Escherichia coli (Ec) B and Salmonella enteritidis (Se) SER were used for comparison of the bactericidal activity of AOW to periodontopathic bacteria.
AOW was obtained from an OXILYZER and stored in a polyethilene bottle and kept in a dark cold place totally blocked from light.
Bacterial strain Aa : Y4 and ATCC 29522, Pg : 381 and ATCC 33277, Fn : ATCC 23726 were grown at 37°C in BHI (5% CO₂), BHI contained hemin, menadion and yeast extract (anaerobic condition), and GAM broth (anaerobic condition), respectively. After washing by centrifugation, each bacteria was suspended in PBS and adjusted to the optical density of 0.3 at 540 nm light length with 0.1% gelatin containing Hanks' balanced salt solution (GHBSS) .
Serum and saliva were obtained from volunteers of healthy student. Saliva was sterilized through a millipore filter with a 0.45μm pore size.
Bactericidal activity was performed by colony count seeding and grown on BHI or Anaero columbia blood agar or GAM medium after treatment with AOW.
The following results were obtained:
1. Bactericidal effect and effective concentration of AOW
Periodontopathic bacteria were AOW sensitive and were killed in one minute, from the original 25% AOW, while it needed more time and a higher concentration to kill Ec, Sa and Se.
2. The effect of serum and saliva on bactericidal activity of AOW.
To Aa and Pg, the addition of serum or saliva in a concentration of 1% of AOW had the effect of bactericidal activity. However, the bactericidal activity was completely lost by the addition of 10% serum in AOW. To Fn, the bactericidal effect was lost in only 1% of serum or 10% salivary addition.
3. Stability of bactericidal activity of AOW.
AOW was kept in a polyethilene bottle at 4°C with shading from light. The bactericidal activity was examined by withdrawing AOW from the shielded bottle weekly. The activity was well preserved until 5 months. After 21 weeks, a slight decrease of bactericidal activity was observed in 25% AOW.
4. Cause of decrease of bactericidal activity by addition of 10% serum to AOW.
The addition of serum to AOW caused a decrease of oxi-red potential from 1144.8 to 479.0. pH from 2.52 to 5.60, and HClO from 19.4 ppm to undetectable.
In conclusion, AOW is a useful disinfectant of periodontopathic bacteria in vitro. The oral environment is very complex. We must pay careful attention not only to the decrease of bactericidal activity of AOW by salivary flow and bleeding, but also the effect of AOW on the mucosa.

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The amounts of disocclusion during protrusive movement were measured using leaf gauge, on study catsts of 18 young subjects with normal dentition and free of TMD, mounted on a semiadjustable articulator. The results were compared statistically with those of adult subjects reported by Haramoto, et al. Statistical difference between the two populations was found on first and second molars but not on premolors, at the 99% level of confidence. The reasons for the significant differences between the two populations were discussed. The statistical difference of sagittal condylar path inclinations which existed between the two was attributed as one of the reasons. However, the residual reason was not clarified.

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The amounts of disocclusion on nonworking and working sides during lateral movement were measured using leaf gauge, on study casts of 18 young subjects with normal dentition and free of TMD, mounted on a semiadjustable articulator. The results were compared statistically with those of adult subjects reported by Hobo, et at. On nonworking side, statistical difference between the two poulations was found on first and second molars but not on premolars, at the 99% level of confidence. On working side, statistical difference between the two was found only on second molars but not on premolars and first molars. The reasons for the significant diferences between the two populations were discussed. On nonworking side, the statistical difference of sagittal condylar path inclinations which existed between the two was attributed as one of the reasons. However, the residual reasons were not clarified.

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It is possible to determine the physiological position of the mandible that is appropriate for patients with craniomandibular disorders (CMD) by employing a gnothostomatic diagnostic system. If the present position of the mandible is diagnosed as a deranged reference position (DRP), it is then necessary to reposition the mandible by establishing the therapeutic reference position (TRP) that is the goal of treatment, and fabricating provisional restorations or a splint at that position. Furthermore, it is very important during full mouth oral rehabilitation to determine the final mandibular position before fabrication of the prostheses, and to then reconstruct the occlusion.
As a method of objectively and scientifically determining the mandibular position and movements, we carry out treatment using the computerized axiograph (Cadiax System, Gamma Co., Austria) . In order to place the position of the mandible in an even more stable position with the final prostheses, we reconstructed occulusion with sequential functional guidance in the occlusal form.
We would like to report and discuss clinical evaluation of this gnathostomatic system, progress during treatment, and the final prosthetic restoration that we performed.

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Dental implant therapy can be classified according to the following conditions; immediate placement right after the tooth extraction and placement following complete healing of oral mucosa and bone regeneration. However, there is no background on the propriety in the immediate placement implants. Therefore, in view of bacterial points, we examined the existence of residual bacteria and considered the propriety in the immediate placement. As a result, the residual bacteria that contained some of the infectious bacteria were detected immediately after the extraction.
This result suggests that immediate placement poses the risk of infections in the implant.

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