Bone-derived cells can generate calcified afibrillar globular accretions, directly on a polystyrene culture dish in vitro. Cells anchored to the first formed accretions will produce collagen fibers. While being produced, the collagen layer undergoes calcification. Clearly, the calcified globular accretions may act as a substratum conditioning layer prior to overt bone formation. Similar deposits can be seen on the retrieved implants. Most dental implants are designed to perform stabilization and initial anchorage in bone. However, there seems to be no consideration for the effects of surface roughness on mineralized globular accretions formation. In this study, the deposition of calcified globular matrix on differing surface roughness following 3 weeks of culturing was investigated.
Three different degrees of surface roughness were produced on the bottom of 35 mm tissue culture dishes as follows:1)unabraded (smooth surface), 2) abraded the surface using ＃600 silicon carbide sandpaper, and 3)sandblasted the surface. Bone marrow cells obtained from the femora of rat were cultured for 3 weeks in the above dishes. After culturing, these samples were prepared for SEM.
On the smooth-surfaced dishes, mineralized globular matrix was produced homogeneously and densely. However, on the 600-grit-surfaced dishes, mineralized globular accretions were only observed on the top of scratches. Globular accretions could not be seen in the sulcus of scratches. Globular accretions were also observed at the top of pit but not at the bottom of pit.
The results demonstrated that substratum surface roughness influences the distribution of mineralized globular accretions in culture by rat bone marrow derived cells.

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The effect of premature loading on hydroxyapatite (HA) coated blade form implants placed in dog mandibles was histologically examined. Two dogs weighing 25 kg were used in this study. Four implants, two HA implants and two titanium (Ti) implants as control, were placed in the dog mandibles. Restoration was splinted with neighboring natural tooth 4 weeks after implant placement.The animals were sacrificed either 4 or 24 weeks after the installation of restoration. Histologic sections disclosed that Ti implant had become encapsulated with fibrous layer, and HA implant showed good adaptation between the HA coating layer and bone tissue. Consequently, these findings suggested that HA implant would tolerate premature loading, and that there was a possibility of a shorter healing period prior to loading.

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The crystal structure of chitosan depends on the extract material.α-chitin is extracted from crustacea and shrimp.β-chitin is extracted from squid. The properties of deacetylation chitosan depends on the chitin. There are many products created from chitin and chitosan.
In this study, the relationship between viscosity, pH volume of chitosan solution and molecular weight or deacetylation of chitosan was determined. The obtained data was used to understand the relationships between tensile strength, elongation of chitosan film and the molecular weight or deacetylation of chitosan. The results were as follows:
1. A low molecular weight of chitosan and film could not be created.
2. When low deacetylation of chitosan was neutralized, it wrinkled.
3. No difference in viscosity for each chitosan solution due to dissolving in malic and malonic acid was observed.
4. The pH of each obtained chitosan powder was more than 8.
5. The pH of chitosan solution made by dissolying in malic acid was higher than that by dissolving in malonic acid.
6. The pH of each mixed hydroxyapatite and chitosan solution was higher than that of each chitosan solution.
7. Tensile strength and elongation of chitosan films were influenced by the deacetylation of chitosan.
8. Tensile strength and elongation of chitosan film showed no difference with regard to the use of organic acids.

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　The purpose of this study was to investigate the dynamics of nickel contained in shape memory alloy implants （SMI）．An SMI removed from a patient 4 years after placement was studied by X-ray photoelectron spectroscopy．The conclusions were as follows：
　1．Oxygen，titanium，carbon，and nitrogen were detected on the implant surface；no nickel was detected．
　2．The titanium on the implant surface was present as TiO₂． A small amount of Ti（OH）₂ was also detected．
　3．The metal peak of titanium was first detected at a depth of 4 nm and that of nickel was detected at a depth of 0.67 nm．
　4． At a depth of 0.67 nm from the implant surface，nickel was present as NiO and metal．Titanium was present as TiO₂, TiO_X，and TiO．
　The results of this study did not allow us to determine whether nickel was not initially present on the implant surface or it had undergone elution in the body．Studies are urgently needed to clarify this point．

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It is important to keep biological activity of mucoperiosteal flap tissue for remodelling the cortical bone around implant post neck during implanting operation. For five years, bactericidal action of electrolytic acid water (EAW) has been circulated, and the irrigation and/or spray of EAW for surgical field has been recommended as an irrigating solution with a disinfecting effect.
To evaluate EAW irrigation for implant surgery, a histopathological study on the tissue aggression of EAW was carried out for 10 min. EAW immersion of mucoperiosteal tissue fragments obtained from human oral mucosa, and compared with that of aqua dest., Hanks solution (PBS), KN solution (for store of transplant-tooth) and povidone-iodine (disinfectant).
Povidone-iodine and aqua dest. demonstrated tissue damage with peculiar reaction of cytotoxicity respectively, especially at the epithelial layer and periosteal, but lamina propria was relatively intact because of depth from the surface of the tissue fragment. On the contrary, Hanks solution and KN solution could keep the normal condition in all layers of epithelium, periosteum and propria.
It will not be recommended to use EAW, aqua dest. and chemical disinfectant for the purpose of protecting bone and soft tissue from bacterial contamination, drying and heat generation during bone drilling. Hanks solution and KN solution containing antibiotics are highly recommendable.

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Electrolytic acid water (EAW) has a strong bactericidal action (benefit) and severe cytotoxicity (risk). The action ends immediately after clinical use because EAW is restored to the former state of just water. These characteristics should be considered in clinical usage because of being very different from ordinary disinfectants.
In this study, the cytotoxicity of EAW was investigated by tissue culture test using MEM＋10% FBS and bone marrow cells derived from monkey tibia, and the bactericidal action of EAW is tested by MBC of bacterial cultivation in relation to Cl contents in EAW. In addition, the decreasing effects of bovine serum, human saliva, and peptone solution on the bactericidal action of EAW was measured by MBC for MRSA and MSSA.
Cytotoxicity of EAW was 50% less than the EAW/MEM rate. The bactericidal action of EAW was decreased with deactivating effect of Cl and disappeared completely in less than 3 ppm of Cl content. In addition, the bactericidal action of EAW was inhibited by human saliva (5.0% or more), peptone (2.5% or more),and bovine serum (1.3% or more).
The cells of tissue have the same microorganisms as bacteria. Strong bactericidal action usually has high cytotoxicity. These effects mainly depend upon the Cl content in EAW, which is easily influenced by biological substances of blood, tissue fluid, and saliva. EAW should be used with sufficient knowledge of the above mentioned data.

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This study was conducted to investigate whether or not Terudermis^® would be applicable as artificial gingiva in humans. Thirty-two cases (24 patients) were selected from a patient population visiting the clinic of Kanagawa Dental College. Terudermis composed of collagen matrix and silicone layer was applied to the partial gingival defect immediately after mucogingival surgery. Clinically, in most cases, the healing process was favorable and superior hemostasis and proliferation of granulation tissue were observed. The patients had no complaints of discomfort or pain. The enlargement of attached gingiva, obviously distinguished from alveolar mucosa, was observed in 10 cases that underwent vestibular extension operation and an average of clinically increased width was 2 mm. The above results confirmed that Terudermis was a superior wound covering material and suggested that it could enhance the extension of attached gingiva in humans.

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Application of implants in dental and oral surgery has increased．However，complications have been occasionally found to result from implant operation．Since implants are buried in bone tissue at one end and exposed to the intraoral environment at the other，there is a high risk of infection．Perforation of the maxillary sinus often results in maxillary sinusitis．Therefore when implants are indicated，more careful consideration is required for application to the maxilla than to the mandible．
Two cases which developed maxillary sinusitis following implant operation in the maxilla visited our clinic．This paper describes problems associated with implant operation in the maxilla．
　In one case，maxillary sinusitis was attributed to：（1）inadequate distance between the molar alveolar ridge and the maxillary sinus floor following implant insertion，（2）inadequate initial fixation，and（3）attachment of the denture to the upper end of the lower structure，which had been inserted incorrectly but could not be removed．In the other case，it seemed to have been caused by an error in selecting a suitable lower structure．

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Recently, dental implant has been recognized as a viable treatment. It is needless to say that examination and diagnosis are important for satisfactory prognosis. CT is used for the detailed diagnosis in addition to conventional radiography.
A radiographic examination stent for CT was constructed of aluminum pipes (outside diameter: 3.8 mm, length:10 mm) for indication of the fixture and the wax coated as contrast medium (barium sulfate).
Due to this stent, satisfactory results in dental implant cases have been obtained. The CT using this stent provided useful information as follows:
1. In multiplanner reformation images without artifact, whether or not the position and direction of the indicator for the aluminum pipe were optimum were observed.
2. Final implant prostheses was confirmed using the wax coated contrast medium.

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Many cases of posterior edentulous maxilla have thin and qualitatively poor alveolar bone. It is often impossible to apply implant in these cases. However, the sinus lift technique may provide sufficient bone augmentation for implants.
In our clinic this sinus lift technique has been used with autogenous bone grafting since 1993. From September 1993 to September 1994, 4 sinus lifts and 8 implants were performed for 3 patients.
To evaluate this technique, these implants were checked with periodontal parameters and the sinuses were checked with CT scan.
Results: Plaque index, probing pocket depth, and probing attachment level were considered successful.
The presence of peri-implant radiolucencies were analyzed with standardized radiographs.
CT scan did not show any postoperative problems in the maxilla. CT scores of alveolar bone around the implants were about the same as that of the other side of the alveolar bone.
Three-dimensional CT scan clearly showed the resorption the bone graft.

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The masticatory function of patient with Brånemark implant in edentulous mandible was evaluated by electromyography (EMG), mandibular movement (MKG), and bite force. EMG and MKG during gum chewing and bite force in clenching were recorded at insertion of the old full denture and at 1 week, 2 months, 2.5 months, 3 months and 4 months after insertion of implant bridge.
The time parameter (duration and interval) of EMG burst was changed slightly, but the mean value of mean voltage was increased and CV became stable.
The chewing route showed decreased lateral deviation and improved reproducibility.
Bite force was increased greatly.
These results suggested that evaluation of function of implant bridge could require defined data and original parameter.

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In the case of imaging of upper jaw canine and first premolar by panoramic radiography, the shape and position were investigated and compared with that by tangential tomography of the maxillodental area on SCANORA^®using the steel ball model.
1. When the incline degree of the occlusal plane on the horizontal light beam of SCANORA was changed from 0°to 30°, round shapes resembling steel balls were gradually changed into oval shapes,and the distance of 2 steel balls was shortened in panoramic radiography. This tendency became clearer away from the occlusal plane.
2. In tangential tomography, the shape and position were not changed independently of the incline degree of the occlusal plane.
3. Panoramic radiography is routinely practiced. If the information of upper jaw canine and first premolar were not sufficient, tangential tomography of the maxillodental area of SCANORA should be carried out.

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This report describes the implant restoration for a 22-year-old female with a congenitally missing tooth. After finishing orthodontic treatment, an implant was placed, and the healing process was uneventful. After the second surgery, a ceramometal crown was fabricated. Implant restoration seems to be useful for young edentulous patients, and especially welcome to congenitally edentulism.

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Cases with unfavorable postoperative courses after implantation at other medical facilities were treated at our department of oral surgery.
There was a total of 10 cases, eight with intraosseouse implants and two with subperiosteal implants, treated at our department from 1987 to 1993 because of an unfavorable postoperative course.
There were six males and four females with the average age of 61.3 years. After implantation, nine cases had osteitis around the implant, of which two were complicated with anterooral fistula. In the other cases, central carcinoma was detected in the implanted region. For most of them, the procedure was to remove the implants, but there were one case for which resection was performed because the site of the implant was affected by central carcinoma, one case for which fistel closure was done, and one case for which both sinusotomy and fistel closure were performed. The implant remains foreign to the organisms, and there are problems that have yet to be solved. Therefore, it is necessary for the operator to be prudent to evaluate the adaptability and respond to requests from the patient.

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This article describes an impression technique to ensure the accurate relationships between the coping for casting, analog, and impression coping using self-curing resin splint there of. The most important thing is to splint the laboratory analogs using self-curing resin at the time of the impression.This technique would provide accurate working casts and reduce the frequency of superstructure trouble caused by a conventional impression technique.

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The connection of mobile teeth and implants has always been regarded as a contraindication.
In order to save mobile teeth in 5 patients aged 49～73, the mobile teeth were connected to implants and observed for 3～5 years.
As a result, clinical and radiographical findings showed good prognosis.

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