Three kinds of bone filling materials were prepared by combining powder, including CaO, CaSiO3 and hydroxyapatite (HAP), and chitin and chitosan. The proportion of CaO, CaSiO3 and HAP was 4.5%, 6.0% and 89.5%. This powder 0.54 g (A), 0.67 g (B) and 0.80 g (C) were kneaded with chitin and chitosan sol 2.2 g and hardened, respectively. These materials were evaluated in the experiment animal and osteoblastic cells. The purpose of this study was to discuss which materials were most desirable for the bone filling materials. In an animal experiment, tissue reactions were similar in each material and were characterized by granulation tissue formation with inflammation. In the osseous tissue, repairs at defected sites(B and C) and direct relationship between material A and bone were seen. Cultured cell examination revealed that DNA contents and alkaline phosphatase activity in material A were significantly higher than those in control. Results of this study indicated that material A, 0.54 g mixed in chitin and chitosan sol 2.2 g, was most effective for the bone formation.
The influence of the dental plaque accumulation on the tissues around implants in animals has been confirmed in recent experimental studies. However, various results were reported in these studies. Therefore, this study was carried out to compare the effects of long-standing plaque accumulation with or without the placement of ligatures in the peri-implant tissues. Three beagle dogs were used in this study. The mandibular right and left 3 rd and 4 th premolars were extracted to establish recipient sites for implants. After 3 months of healing, 10 titanium fixtures were implanted and straight post connections were carried out in the 2nd stage procedure after 3 months. After 1 month of healing, biodegradable surgical sutures were placed in a submarginal position around the neck of fixture abutments. New ligatures were made in addition every month. The remaining implants were not ligated. Radiographic and chinical examination comprising Plaque Index (PlI), Gingival Index(GI), loss of attachment, gingival recession and mobility were evaluated at ligated implants and non-ligated implants 1～8 months after the implantation of the straight post. Microorganisms around implants were checked at 3 and 7 months. All dogs were sacrificed at the end of the experiment. The animals were perfused with a fixative, and block biopsies were obtained from the implant sites. The biopsies were prepared for histometric analyses. The results from the clinical and histological examinations revealed that (1) the loss of attachment around ligated implants increased more than non-ligated implants, (2)histometric signs of tissue destruction were more pronounced at the ligated implants than non-ligated implants. In the ligated sites, the mean bone loss was 2.7±0.8 mm, non-ligated site 1.3±0.5 mm.
IBM (insoluble bone matrix) delivery system as an effective carrier of rhBMP-2 (recombinant human bone morphogenetic protein-2) is well acknowledged, but the mechanism is unclear. The long-term results of rhBMP-2, in IBM particle implants, were examined by heterotopic bone formation in rats. The purpose of this study was to evaluate the delivery system for finding a suitable carrier which can be applied clinically.
Chondroblast cells conforming to the shape of lacunae with the basophilic matrix were observed at one and two weeks after implantation. The chondroid tissue was partially absorbed at two weeks after implantation. Bone formation and remodelling were noticed from two weeks. Both endochondral and intramembranous ossification were observed, and the former was predominant at two weeks. A bone marrow-like structure was observed at three weeks and fat marrow was found from four weeks.New bone formation and absorption were not active from seven weeks after implantation. IBM particles were covered by new bone in a stable state. By the end of nine weeks mature bone tissue was still present. Thus rhBMP-2 and IBM composites have high osteoinductive ability, and the newly-formed bone was relatively stable for a long time.This result suggested that IBM provides an excellent immobilization system of rhBMP-2 in the early period of rhBMP-2 induced bone formation. After remodeling the new bone, IBM seems to become part of the new bone matrix.
When placing endosseous implants, there are cases of the height and/or the width of available bone being insufficient. In these situations augmentation is performed using bone grafting materials such as autogenous bone, allografts, and alloplasts. Bone grafting materials can act through one or a combination of three mechanisms: osteogenesis, osteoinduction and osteoconduction. Autogenous bone is the only osteogenic material available and is the most predictable grafting material. However, when autogenous bone must be harvested from intra-or extra oral sites, it puts the patient through the stress of additional surgery and does not permit use in large quantities. On the other hand, allografts and alloplastic bone grafting materials are readily available and recent advances in biomaterial technology and treatment methods have increased their predictability.
In this study, properties and performance of a resorbable bioactive glass (BioGran) were investigated with regard to bioactivity and bone-forming ability. The bioactive glass was grafted to the bony defects and biopsies were taken when endosseous implants were placed. The samples were examined by conventional histlogic techniques, elemental composition and distribution assayed by an electron probe microanalyzer. The results suggested that BioGran exhibits osteoconductive properties and efficacy as an alloplastic bone grafting material.
The purpose of this study was to evaluate procedures to improve the reconstruction of the maxillary edentulous ridge with flabby tissue by application of hydroxyapatite granules (HAP).
The edentulous ridge contour analyzing system (ERCAS) was deverloped and improved, and an edentulous ridge with flabby tissue was designed by application of HAP. Furthermore, the reconstructed ridge was evaluated.
The following methods were used to evaluate the therapeutic usefulness:
1. The analytical items of ERCAS
1) The edentulous ridge on the occlusal view
2) The edentulous ridge contour
3) The artificial tooth position on the edentulous ridge
2. The measurement of denture mobility by Mandibular Kinesiograph (MKG)
3. A questionnaire on diet and masticatory performance of food classified according to hardness.
4. Examination of the mucosal tissue of the edentulous ridge with HAP by tissue reflectance spectrophotometry.
The results were as follows:
1. The reconstructed edentulous ridge was enlarged in the labial and buccal directions by the application of HAP.
2. Application of HAP and the use of Levin's bladed teeth decreased denture movement while chewing and improved the masticatory performance.
3. The mucosal tissue of the edentulous ridge with HAP showed the same properties as those of the normal edentulous ridge.
4. ERCAS is useful to design the edentulous ridge for reconstruction and to evaluate the treatment results.
The maxillary sinus floor augmentation (sinus lift) was performed in posterior edentulous maxilla cases which had insufficient alveolar bone height. This article outline describes the surgery and surgical techniques for sinus lift harvesting from iliac bone to 7 patients (14 maxillary sinuses) of partially or totally edentulous bilateral-maxilla, and evidence of postoperative bone height using dental CT pictures. The surgical procedures were done at lateral approach method in the buccal site of bilateral-maxilla, and the left iliac crest was chosen as the donor site bone which had prepared corticocancellous bone block and particular bone. The block bone was inserted in the sinus maxilla and particular bone placed around the block bone.Six months after, alveolar bone height was investigated to measured by dental CT scan. The results were that the height was measured at 13.6～22.6 mm (mean:18.7mm) in individual sinus, and obtained adequate alveolar bone height for endosseus implant.6～8 months after, we performed implant placement, then the bone quality was felt to stiffness and firmness in bone graft regions. In postoperative observations, there appeared a few level of bone reducing, therefore all of the implants survived without morbidity in the observation periods. We considered that the iliac bone which prepared corticocancellous bone block was useful for bilateral maxilla sinus lift.
In the previous report, endosseous implant system (IAT Fit II) treated by wire type electric discharge machining had excellent biocompatibility to bone and the high rate of achieving osseointegration in report 1. In this report, the longitudinal data of 217 IAT Fit II implants and 84 superstructures fixed in 64 patients between 1995 to 1997 is presented.
1. The survival rate of the implant bodies during the observation period was 99.5% with 100% of the superstructures remaining clinically functional.
2. Among the 84 superstructures fixed, 41 were cement-retained, and 43 were screw-retained. All superstructural components were bridge-type.
3. Complications occurred in 1 case with fixed-screws and 2 fractured implant bodies, which were replaced successfully.
4. No complication of loosing fixed-screw was reported during the observation period.
The results suggested that the ITA Fit II implant system implant body-abutment-superstructure-complex had excellent prognosis.
Preoperative imaging can provide important information for osseointegrated implant treatment. The use of cross-sectional CT images in the buccolingual direction, which are reconstructed from axial CT images, allow a more detailed design of fixture placement to be planned before surgery. The alveolar shape, including the width, height and angle to the occlusal plane, strongly influences the outcome, especially in the upper incisor regions. Therefore, the detailed measured shape using reformatted cross-sectional images may enable the prognosis to be made more accurately. However, no well-established method for measurement has been developed and no study on the standard shape of edentulous alveolar process has been reported on reformatted CT images.
The purpose of this study was to establish a method to measure the width, height and angle to the occlusal plane of the alveolar process on reformatted CT images and to present their standard values in the maxillary anterior region. CT images of 83 patients (34 males and 49 females) were examined.
The results were as follows.
A method to measure the edentulous alveolar process on reformatted CT images was established.
The angle of inclination of the edentulous alveolar process was similar in the central and lateral incisor regions, but that in the canine region was larger.
The height and width in the edentulous alveolar process of the central incisor region were large.
Surface of alumina-coated titanium implant was observed under an optical microscope, electron micro analyzer and X-ray photoelectron spectroscope after 11 years and 8 months of application.
Favorable intial clinical results were obtained in an alumina-coated titanium implant the same as that of bare titanium implants. Alumina coating of 2μm thick disappeared during application of 11 years. Surface of the implant was composed of organic and inorganic compounds originated in body fluids and titanium oxides.
The frequency of use of dental implants has been increasing in clinical practice in accordance with the development of popularity of osseointegration.
It is possible to obtain a lot of information on implants from various journals and textbooks. However, only a few reports have been made on the actual situation of implant treatment in real clinical practice.
Therefore, a questionnaire survey was conducted to investigate the actual situation of implant applications including examination, diagnosis, system used, surgical procedure, prosthodontics, and maintenance, the methods used in implant clinical practice.
Questionnaires were sent to 600 dentists who actually do implant practice from the members of the Japan Society of Oral Implantology as subjects. The dentists were requested to fill out the questionnaine and return it. Three hundred seven questionnaire from were returned, a response rate of 51.2%.
A questionnaire survey was conducted to investigate the actual situation of clinical application of implants in Japan. This survey enabled meaningful in understanding the tendency of clinical practice of using implants.
Due to the results, it is expected that use of implants will be established as a safer and more predictable treatment method.