The purpose of this study was to evaluate how the application of OSTEOINDUCTAL® after tooth extraction affects alveolar bone formation. OSTEOINDUCTAL® is a calcium hydroxide pharmaceutical. Twenty-one Wistar rats were divided into two groups. In both groups, teeth were extracted. The control group underwent no further treatment. OSTEOINDUCTAL® was applied after tooth extraction in the experimental group. The experimental animals were sacrificed for specimen preparation at 4 weeks and 8 weeks. After paraffin embedding, tissues were sliced at 5 μm thickness and stained with H-E. From each specimen, the proportions of the bone dimensions were calculated using a Micro Scope System (MS-803, MORITEX, Tokyo, Japan). In the control group, the bone formation was slight at 4 postoperative weeks, and a pit formed by the invasion of the gingival connective tissue after extraction of the tooth lacuna was clearly present. In the experimental group, considerable new bone was formed. The experimental group had significantly more the bone formation at 4 weeks. However, at 8 weeks, the difference between the control and the experimental groups was only slight.
The results of this study suggest that OSTEOINDUCTAL® may speed up postoperative bone induction.
It is known that chitosan, extracted from a hard shell, is a biomaterial that is easily decomposed and absorbed in living substances, and it exhibits a lower level of antigenicity. Since chitosan showing alow deacetyl tendency can cause bone resorption,the present study used chitosan with a high deacetyl property, to produce a composite film incorporated with hydroxyapatite (Hap). The pH value of composite films was controlled. After absorbing physiological solution and Ringer's solution into these composite films, animal studies were conducted. The following main conclusions were obtained.
1. The film that had absorbed Ringer's solution exhibited osteogenesis after 8 weeks. These observations can be considered due to the slow-dissolving of the mineral components from the films and dissolving films itself.
2. Hap particles did not migrate from film.
In this study, microvascular changes of periodontal and peri-implant tissue after experimental induction of inflammation were investigated, using a vascular resin cast method, to gain insight into the cause-and-effect relationship between inflammation and microcirculation.
A titanium-screw implant was inserted into oneside of mandibular bone of beagle dogs, while the other side of the premolars served. In the experimental group, 90 days after implantation, dental floss was placed around the cervical area of an implant fixture and the premolars, to enhance the accumulation of plaque, for another 90 days, but the control group received no placement of dental floss. Plaque control, including brushing, rinsing, and cleaning, was prohibited during this period. To make a vascular resin cast model, synthetic resin was injected into the inferior alveolar arteries. Soft tissues of specimens were digested by a proteinase solution. All of the specimens were examined by scanning electron microscopy.
The vasculature beneath the sulcular epithelium (SE) formed vascular loops, while that of the junctional epithelium (JE) was arranged in a fishnet pattern.
In the case of periodontitis, the arrangement of the SE and JE both changed into glomerulus vascular loops. Vessels in peri-implant soft tissue (PIT) formed a dense network. Under that, a ring-shaped vascular network of connective tissue surrounded the implant neck. In the peri-implantitis, granulated blood vessels of PIT grew toward the apex, and the surrounding alveolar bone was resorbed.
These findings indicate that periodontal and peri-implant vasculature changed easily by experimental inflammation, and that it is more difficult to maintain the vascular structure of PIT than natural periodontal tissue. Protection of microcirculation from inflammation in PIT would ensure that peri-implantitis would be amenable to treatment.
In three adult dogs, the dental root of the premolar of extraction was divided into small tips after freezing (-20℃,3 months), and the tips were transplanted into own bone cavity of mandibular bone. Tissue specimens 1, 3 and 5 weeks after operations were made for observation under the light microscope.
1. In the case of the filling of frozen dental root tips, the osseous addition of frozen dental root tips was active 3 weeks after operation. These had been more active 5 weeks after, and frozen dental root tips were made up to bone by the absorption for replacement.
2. In the case of the own transplant of dental root tips immediately after extraction, compared with frozen dental root tips, osseous addition was similarly found at 3 weeks after operation. However matured bone trabeculae and progressed bone remodeling were found more clearly 5 weeks after.
3. We found no differences between bony interfaces on the frozen dental root tips and extracted dental root tips, and the ratios of bony interfaces were about 0% after 1 week, 54% after 3 weeks, and 73% after 5 weeks.
The application of enamel matrix derivative (EMD) has recently been reported to be effective in periodontal regeneration. EMD appears to induce both periodontal tissue and calcified tissue. Both experimentally and clinically, EMD has been recognized as useful in tooth replantation and autotransplantation.
Dental implant and autotransplantation have been used in the recovery of missing teeth. These procedures may also be effective for orthodontic treatment.
The objective of the present study was to determine if EMD could affect root resorption and the loss of functional epithelium after tooth autotransplantation.
In 4 adult male beagle dogs, bilateral maxillary first and second premolars (Pl and P2) were extracted with forceps. P1 and P2 on one side of each animal, were transplanted to the sockets of P1 and P2 on the other side, with EMD treatment (treated side), while P1 and P2 on the contralateral side of each animal were transplanted in the same fashion without EMD treatment (control side). During 2 weeks after splinting with composite resin, the animals were fed a soft diet. All animals were sacrificed 6 weeks after autotransplantation, and dissected specimens around maxillary P1 and P2 were decalcified by a conventional method. The specimens were cut sagittally, including the crown cusp and root apex of P1 and P2, and tissue sections were evaluated histologically. Using each tissue section, the crown root ratio was determined, and the root resorption rate was defined as the area of root resorption/total root area including cementum × 100(%), and it was calculated by two dimensional computer analysis.
Statistically significant differences were found between EMD-treated and non-treated groups in tooth mobility as measured by PeriotestR and the crown root ratio. However, there was no difference in the root resorption rate (average 2%) among the four groups examined (EMD-P1,EMD＋P1, EMD-P2, EMD＋P2).
These results suggest that the application of EMD stimulated the regenerative potential of connective tissue, such as periodontium and gingiva. However, EMD-treatment did not stimulate the regenerative potential of calcified tissue, such as cementum and alveolar bone.
This paper analyzes clinical application of the Brånemark system implant® over the 10 years from 1989 to 1999, especially the 17 of 126 patients where fixtures were later removed. A total 515 fixtures were installed, and 32 fixtures were removed; the 10-year cumulative survival rate of the fixtures was 93.2%. Thirty-two fixture removals were conducted:16 at the time of second-stage surgery, 12 during use of a temporary prosthesis, and 4 after final prosthesis installation. Maxillary removal accounted for 18 fixtures. Of these, 17 were posterior maxillary. The remaining 14 fixtures were mandibular removals. In cases in which the posterior maxilla was more than 4 mm in diameter and 13 mm in length, the survival rate was a low 66.7%, with more than half of the patients exhibiting bone quality of 3 or 4 (LEKHOLM＆ZARB).
In cases in which osseointegration was attained, the fixture's survival rate was good even after the installation of a final prosthesis. However, the finding that a significant number of patients exhibited bone quality issues in the posterior maxilla, requires reconsideration of both surgical procedures and the type of fixture itself.
Short-length (6 and 8 mm), wide-diameter (4.8 mm) implants were placed into the lateral part of the maxilla in 28 patients, as they had insufficient bone height. The 6-and 8-mm length implants were placed into the sights where the average bone heights were 6.3 and 9.9 mm, respectively.
Although a 6-mm implant was lost in early phase,remainder 47 implants were undergoing maintenance in the 22 month of an average follow-up time.
An alveolar bone graft, followed by the insertion of threaded titanium endosseous (Brånemark System) implants, was performed in two patients with cleft lip and palate.
One patient, with bilateral cleft lip and palate, underwent an iliac bone graft after orthodontic treatment. An oronasal fistula was simultaneously closed by bilateral labial flaps and a tongue flap. Brånemark System implants were placed for treatment of congenital missing lateral incisors, 17 months after the grafting. The other patient, with unilateral cleft lip and alveolus, underwent a chin bone graft. Although necrotic bone resulting from exposure of the palatal side of the grafted bone was removed, most of the grafted bone survived. Six months later, occlusal reconstruction using Brånemark System implants was performed. The postoperative course was uneventful in both cases. Moreover, these patients were satisfied with both esthetic and functional results, which improved the patient's QOL.
These results indicate that endosseous implants combined with bone grafting are more reliable than conventional procedures for occlusal reconstruction in patients with alveolar cleft.