Although hydorxyapatite (HA) is biocompatible material, it cannot support the biological load when used as a simple substance. In view of this, a titanium implant whose surface was coated with HA was developed. A thick HA coating, however, leads to peeling, shedding, and erosion, which causes harmful effects on the living body, resulting in implant removal.
These problems can be solved by developing an implant thinly coated with HA. Although there are several methods to coat implants with HA, the heat decomposition method is the only technique to coat them with ultrathin HA.
In the present animal experiment, we prepared implants ultrathinly coated with HA (4 μm) by the heat decomposition method, and inserted them into the femurs of rabbits. The changes of the tissues around the implants were histopathologically evaluated over time.
The implant used was Platon Implant of 3.0×6 mm whose pure titanium surface was coated with HA by the heat decomposition method (HA type). We prepared pure titanium implants as controls matched for shape (Ti type).
The implanted sites were observed 2, 4, 8, and 12 weeks after implantation.
According to regular technique, resected femur samples were embedded in Rigolac and horizontally cut into non-decalcification polish sections of approximately 60 μrn in thickness.
All the non-decalcification polish samples collected during observation periods were stained with toluidine blue,to study the changes with time of the tissues around the implants, from the aspect of histopathology.
Although osteogenesis was recognized in the tissues around implants at 2 and 4 weeks after implantation, osteogenesis observed around HA type was more remarkable than that observed around Ti type. Low power magnification, at and after the eighth week, disclosed an increase in bone density in the tissues around both types of implants, and the histoiogical differences between the areas around HA type were gradually obliterated. The high power magnification, however, showed closer contact of HA implant surface with bone.
These experimental results suggested that implants coated with HA by the heat decomposition method could be used in clinical treatment because of their practical usefulness.
The osseointegration type of implant is now the prevailing modality in dental implant operation. Evaluation of the jawbone is, therefore, important for patients scheduled for an implant operation. Methods like QCT and DEXA, which are currently used to measure bone mineral content in other bones, cannot be employed for quantitative evaluation of bone in the jaw. In addition, the instruments required are so expensive that they may not be practical for introduction into clinical dentistry.
To measure bone mineral content in the jawbone, we developed a TV-image analysis system using dental X-ray films.On applying this system, the following results were obtained.
1. Quantitative evaluation of bone quality could be achieved simply and rapidly by this system.
2. The relation between age and bone mineral content differed between the sexes. In all age groups examined,the mean values of bone mineral content were higher in males than in females.
3. Standard average values of mandibular bone mineral content by age and sexes could be determined. This allows screening of patients prior to implant operation.
4. The bone mineral content in bones adjacent to the site of implant, which remained unchanged after installation, was found to increase before attachment of a superstructure.
5. In contrast to the increased bone mineral content in adjacent bones, the bone mineral content in mandibular alveolar crest tended to be decreased for some time.
IMZ® Implants have been in clinical use at the PDI Attached Saitama Dental Clinic (Meikai University School of Dentistry, Post-Doctoral Institute of Clinical Dentistry) since 1989. In this study, the authors investigated 336 fixtures of cases over 2 years after the attachment of superstructures, by December 1999:
1. Number of patients according to the time elapsed since attachment of the superstructure to the fixture
2. Number of patients according to age
3. Number of fixtures implanted according to age
4. Number of fixtures implanted according to fixture size
5. Time elapsed since implantation according to fixture size
6. Number of fixtures according to implanted site
7. Defect state and number of fixtures
8. The connection between the fixture and natural teeth
9. Number of patients in whom fixtures were removed, and number of fixtures removed
10. Number of fixtures removed according to implanted sites, and rate of fixture removal
11. Number of fixtures removed according to fixture size, and rate of fixture removal
12. Survival rate (Minimal survival rate)
More small fixtures were implanted in our clinic than in other dental clinics, because bone width and anatomical problems were taken into account. The minimal survival rate of fixtures was 88.4%, when the fixtures of patients whom we were unable to follow up (those who did not revisit our clinic) were included in the number of fixtures removed. This figure is higher than that reported in other clinics, which may have important implications for the clinical value of IMZ® Implants.
An oral implant for partially or fully edentulous patients is very useful for the reconstruction of occlusal function. Recently it has become widely used by many practitioners, and quite a few of these implant therapies have been reported. On the other hand, reports of failure of clinical therapeutic approaches with oral implant are relatively few. We report 30 failed implants in 20 patients. This investigation is based on clinical evaluations of patients who visited our clinic over the last 14 years. The results are as follows:
1. The patients were 11 males and 9 females. The ages of the patients ranged from 22 years to 80 years.
2. The chief complaint of these patients was swelling and pain at the implant site. This was the most common complaint (7 cases), followed by mobility of the fixture and pain (2 cases), mobility of the fixture (2 cases), pain (2 cases), fracture of the fixture (2 cases), altered sensation (2 cases), sensory disturbance (2 cases), and no complication (1 case).
3. Materials and the type of implant:metal implant (10 cases), alumina ceramic implant (10 cases), and endosteal implant (18 cases) are the most frequent, followed by endodontic and endosteal implant (1 case), and subperiosteal implant (1 case).
4. The major etiologic factors leading to failure are classified into three types:local infection (13 cases), impaired healing (4 cases), and overload (3 cases).
5. Thirteen patients complained immediately and wanted to remove the implant. Two patients had no complaint at their first consultation.
For design of the superstructure of implants, overdentures are regarded as an indispensable alternative in the aspects of lip-support, speech, cleansability, economy, and aesthetics. As a retainer of overdentures, magnetic attachments have attracted attention due to their many useful aspects; for example, they can reduce lateral adverse force.
We have developed various types of Magnetic Attachments of a Cap Shape (MACS) that can be applicable to implants. We applied them in many clinical cases, obtaining good results. In this study, for further detailed evaluation of three types of MACS, such as those applied to ITI, POI, and 3i, among various types of MACS applied to implants used in overdentures, we examined the fit, using a scanning electron microscope (SEM) and a retentive force test using dental force gauges, and evaluated the results with those of the clinical application of MACS. MACS applied to various types of implants used in overdentures are composed of a removable keeper that is directly connectable to the fixture or component using screws, and of a magnet that has a resin cap to cover the keeper.
As a result, the three types of MACS showed good of fit by SEM observation. Regarding measurements by the retentive force test, 772.6 gf was measured in the MACS applied to ITI, 760.3 gf in that applied to POI, and 448.7 gf in that applied to 3i, showing sufficient suction force in all three types. As a result of clinical application of MACS, dislocation due to an improperly installed magnet, and falling of the magnet in later days, were prevented. Moreover, the magnet attachments were applicable to implants with a simple manipulation using self-curing resin without complicated laboratory procedure, and were excellent in retention force, feeling of use, and maintenance, showing a good clinical course. Because the keeper was removable, it was considered that adverse effects on magnetic resonance imaging (MRI), and deterioration of the keeper due to casting or treatment with acids, were prevented. From these results, it was suggested that MACS may have useful applicability for implant overdentures.
So called mucous cyst arised in the maxillary sinus is often radiographically found in clinic without any episode and considered to be unnecessary objective disorder to treat. However, this mucous cyst should be enucleated when discomfortable symptoms occur due to enlargement.
Based on this reason, preliminary procedure on enucleation of antral mucous cyst performed before or at the same time of maxillary sinus lift procedure was retrospectively discussed. Subjects were four patients with mucous cysts enucleated in our department over the ten years and ten months from August 1989 to June 2000. Our operative technique was that the mucous membrane at anterior site of the maxillary sinus was exposed, and then we made a horizontal incision line with a No.11 blade, and the mucous cyst was directly separated from the bottom of the sinus membrane. This anterior mucosal window was re-sutured, and bone or artificial materials were grafted, in the manner according to our previous report. During an average follow-up period of 52.8 months, no secondary complication, such as maxillary sinusitis or edematous swelling of mucosa, or recrrence of the mucous cyst, and no problems following placement of implants, have been observed. It seems that this technique for enucleation of a mucous cyst including deals with maxillary sinus mucosa can be extended the indication of maxillary sinus lift procedure and placement of dental implants in maxilla.
471 cases (374 patients) were evaluated as to alveolar bone height of posterior edentulous in maxilla using panorama X-ray films. Those cases were classified not only several modality of edentulous type which were 4567, 567, and 67 but also partially and completely edenturism. Those cases were measured by the distance from the alveolar ridge to the maxillary sinus floor and converted by 1.2 magnification in ideal implantation positions 4,5,6,6', and 7 (the first molar was divided into two points), respectively. Then the possibility ratio of implant treatment, which decided of alveolar height over 11.0 mm, was examined in each type of edenturism. In addition, the form of the maxillary sinus floor was investigated. The results were as follows.
1. The patients'mean age was 65.6 years (range 23 to 94), and classification of edentulous type was as follows: 4567 was 298 cases, 567 was 78 cases, and 67 was 95 cases.
2. The mean distance from the sinus floor to the alveolar ridge was as follows:4 was 14.1 mm (range 0.5 to 38.0), 5 was 10.8 mm (range 0.5 to 34.0), 6 was 8.3 mm (range 0.5 to 28.0), 6' was 7.8 mm (range 0.5 to 22.0), and 7 was 10.0 mm (range 0.5 to 28.0).
3. The possibility ratio for implant treatment was as follows:4567 was 37.9%, 567 was 33.3%, and 67 was 25.3%.
4. The investigation about sinus floor forms and the possibility ratio was as follows: mono-concave type was 312 cases (possibility ratio 37.8%), two-concave type was 99 cases (32.3%), three-concave type was 37 cases (16.2%), and four-concave type was 23 cases (30.4%).
In the above-mentioned, most of posterior edentulous cases in the maxilla had inadequate alveolar bone height for implant treatment. We should more often consider some countermeasures to obtain adequate bone volume in this region.
The purpose of this retrospective study was to designate an outline of criteria for the clinical evaluation of patients treated with dental implants. In this paper, the contents of our survey are also reported briefly. A total of 2,261 patients (957 males and 1,304 females), ranging in age from 10 to 88, participated in this study. The patients in their 40s and 50s represented 62.1% of the total number of subjects. The number of implants examined was 5,092, which had been placed in 2,969 cases. The numbers of cases and implants placed during the 1990s were higher by 2.7 times and 3.6 times compared with the 1980s, respectively. The mean number of implants was 2.3 for males and 2.2 for females. Those who had systemic health problems accounted for 11.7% of the total number of patients, of which 49.5 percent were suffering from some form of circulatory disease, out of the total number of systemic diseases. Cigarette smokers, habitual drinkers, and in particular drug users, were very few, but there was a gender difference in these habits. Many implants were planted in the mandible, free end missing parts, partially endentulous dental arches and the molar region. The prostheses supported by implants were mostly cement-retained bridges for retention and implant/implant bridges for connection. Regarding the implant design, screw-type implants were frequently used. The surface of most implants was coated with hydroxyapatite. Many implants were 10-15 mm long and 3 mm in diameter. Bone quality and bone quantity in both the maxilla and the mandible were medium. The mean number of years after implant placement was 5.5 years. As for the present condition, 85.4% of the cases and 87.8% of placed implants were favorable. The above-mentioned findings suggested that further studies would be helpful to dentists practicing implant treatments.
Early recovery of normal mastication and aesthetic performance after the extirpation of a large radicular cyst in a site from a right lower inciser tooth to the second premolar tooth in a 42-year-old male,was attained by use of two implants of one-piece screw implant, AQB (HA-coated Ti), space maker Ti plate, barrier membrane of e-PTFE and autogenous bone chips/mill transplantation. While membrane exposure was observed slightly,bone regeneration around the implants was significantly recognized by clinical evaluations and histopathological observation of biopsy after removing the barrier membrane.
It was certified that the bone formation was sufficient to retain these two implants under physiological mastication. These procedures may be recommendable as a method of early functional recovery in the case of a large bone defect.
So-called osseointegrated implants, such as Brånemark®, ITI®, and IMZ®, introduced in the 1980s, induced more predictable implantology, and eventually the survival rate went up high. However, the position of the implant socket used to be absolutely governed by the condition of the residual alveolar ridge. Guided bone regeneration(GBR) challenged this common knowledge and extended the indication of implant surgery.
There are two approaches for GBR: a staged approach,and a simultaneous approach that is performed when the implant is placed. But the latter has limited indication.
Buser classified the residual alveolar ridge into 4 classes, and advised that the simultaneous approach is contraindicated for a class 4 type of alveolar ridge,which has crator-like bone resorption,leaving about 5.00 mm ridge in bucco-lingual width.
However, the operator encounters many patients who demand less time-consumming implant service. The author has tried to answer their demands and challenged this difficulty by executing the simultaneous approach in class 4 alveolar ridge in daily clinic.
In simultaneous GBR, Goretex Ti-reinforced GTAM® was used to cover autografted bone chips, which were harvested from the implant socket and the other part of the alveolar ridge. The applied implants were all TPS ITT screw type.The periodentological observation of the postoperative progresses of 6 cases was performed for 3 years postoperatively. Probing attachment level (PAL) and probing pocket depth (PPD), using a WHO probe,were measured chronologically at the insertion of prostheses, 1 year later, 2 years later, and 3 years later, respectively.
As for PAL, the average values were 2.7 mm, 2.7 mm, 2.5 mm, and 2.5 mm at insertion time, 1 year later, 2 years later,and 3 years later, respectively. The total average of measurement of PAL was 2.6 mm. As for PPD, the average values were 1.3 mm, 1.4 mm, 1.4 mm, and 1.4 mm at the insertion of prostheses, 1 year later, 2 years later, and 3 years Iater, respectively. The total average was 1.4 mm.
These values of the measurements indicated that the peri-implant pocket was kept in shallow, healthy condition for 3 years postoperatively. And the author expects this healthy-condition will continue, like other approach. From the result, the author concluded that simultaneous GBR can be indicated in the so-called class 4 type of residual alveolar ridge.
Former public relations committee of the Japanese Society of Oral Implantology surveyed the academies of oral implantology in foreign countries, implant systems available in Japan, and basic and clinical papers of each implant system.
The results were as follows.
There were fourteen academies of oral implantology in Asian and Oceanian areas, eleven academies in North American areas, twenty-five academies in Europe area, thirteen academies in Central and South America areas, four academies in Middle East area. Also, there was one academy in Africa area.
Thirty-seven implant systems were available in Japan. Twenty-three implant systems in the foreign countries and fourteen implant systems in Japan.
No papers were published in several implant systems. The papers of the Brånemark system were published most frequently.