Boneject® is a powdered bone filling substance consisting of atelocollagen solution and natural hydroxyapatite prepared from bovine bones.
Implants were placed in 15 patients and Boneject® was concurrently applied to implant sites lacking sufficient alveolar bone. Postoperatively, the sites applied Boneject® were studied clinically and pathologically. The type of Boneject® used was KF300, with a particle diameter of 300 to 600 μm.
Postoperative evaluations were performed by roentgenographic examination and clinical examination, including assessment of the status of wound healing. The hardness of the region filled with Boneject® was tested by test puncture with an engine reamer at the time of secondary operation. In addition, tissue samples were taken from the filled region in 10 patients and were examined under alight microscope.
The results were as follows:
1. After the operation, there were no distinct signs or symptoms of infection or poor wound healing in any patient.
2. By roentgenographic examination, increased radiolucency was seen in 3 patients after 6 months. In addition, 2 patients showed evidence of partial absorption at the filled site. No patients showed increased radiopacity.
3. Puncture tests could be performed at 10 sites. The filled sites were relatively soft in many patients, even during secondary operation.
4. Pathological examinations were performed in 10 patients. Evidence of osteogenesis between the Boneject® particles was found in all of these patients. In 3 patients, bone had formed between almost all particles, and there was good fusion between newly-formed bone and the Boneject® particles. No patient had any findings of inflammation or reaction to a foreign substance.
The amount and rate of new bone formation at the sites filled with Boneject® did not necessarily correlate with clinical or roentgenographic findings. It is considered that biopsy specimens of bone should be examined to evaluate the state of osteogenesis at sites applied Boneject®.
Cell function in gingival tissue seems to be governed by the extracellular matrix and soluble factors in the local environment. Accordingly, in this study, the effect of extracellular matrix materials on oral mucosal keratinocyte (OMK) and oral mucosal fibroblast (OMF) proliferation, matrix synthesis, and the response to transforming growth factorβ (TGF-β) was investigated.
After culturing keratinocytes and fibroblasts on tissue culture dishes coated with type I collagen (CI), type IV collagen(C IV), laminin (LM), and fibronection (FN) for 4 days, the cells were counted with a CytoFluor II fluorescence multiplate reader. Ability to synthesize collagen-associated proteins and proteoglycans (PGs) was measured by the metabolic labeling method using 14C-proline and 35S-sulfate, and fluorograms were prepared and evaluated. All experiments were performed with and without the addition of TGF-β, and the results were as follows:
1. All four types of matrix material significantly promoted OMK proliferation. OMF proliferation, on the other hand, was significantly promoted by LM and FN.
2. TGF-β significantly inhibited OMK proliferation on all of the matrix materials, including plastic, but OMF proliferation was significantly inhibited on plastic alone.
3. Among the major collagen-associated proteins, C I,C IV and FN significantly promoted OMF synthesis of 190-kDa and 170-kDa proteins, and C I and C IV significantly inhibited OMF synthesis of 140-kDa and 120-kDa proteins. TGF-β significantly promoted the synthesis of 170-kDa protein on C IV, and synthesis of 140-kDa and 120-kDa proteins on C I.
4. PG synthesis by OMKs yielded only PG-1,and this was significantly promoted by C I and LM. TGF-β significantly inhibited PG synthesis only on CI.
5. OMFs were found to express PG-I and PG-II, and all of the matrix materials promoted the synthesis of PG-I and PG-II. TGF-β significantly promoted the synthesis of PG-I on LM only, and the synthesis of PG-II on C I, C IV, and LM.
The above results show that the four different types of extracellular matrix material examined alter keratinocyte and fibroblast proliferation and matrix synthesis. In a similar manner, differences in the characteristics of the extracellular matrix cause changes in the cell response to TGF-β.These results show that the components of the extracellular matrix have important effects on the growth and differentiation of OMKs and OMFs, and on the action of soluble factors, suggesting that determination of these distinctive properties will make it possible to apply them to a variety of biomaterials.
Hydroxyapatite (HAP) is considered one of the best bioactive ceramics because of high bone conduction/induction in osteogenic tissue. Although it has several characteristics of an ideal bone substitute, it does not have bone induction in heterogenous tissue. On the other hand, partially-purified bone morphogenetic protein (BMP), which contains BMP-2 and can induce differentiation of mesenchymal cells into osteoblast, was extracted from bovine bone matrix. In this study, porous HAP-BMP complex was inserted into the bone defect in case of HAP-coated implant, an integral implant system for the dog mandible.
The results showed significant increases in the height and the area of the new bone in the porous HAP-BMP complex experimental group as compared with the control group. From the results above, it was considered that porous HAP-BMP composite maintains the thickness of regenerated tissue of the bone defect around implant.
In this study, neurosensory dysfunction of the inferior alveolar nerve was evaluated histopathologically after implant placement posterior to the mental foramen and nerve repositioning in dogs.
Titanium endosseous implants were placed in the cortical bone of the mandibular base after extraction of the 4th premolar tooth and inferior alveolar nerve repositioning.
The animals were sacrificed at 1 week and 2, 3, and 6 months after surgery, and the mandibles were removed and fixed in 10% neutral buffered formalin. The samples were embedded in paraffin or Technovit® 7200 for light microscopic observation.
One week postoperatively, histological findings showed that there were marked endoneural edema and degenerative changes of the myelin sheath and axon on the implants. In these cases, some of the degenerative changes were found on the distal side of the nerve fibers but most of them were intact.
Two and three months postoperatively, regenerative findings showed that there was the degeneration of myelin sheath and axon on the implants but on the proximal and distal sides of the nerve fibers,most of them were intact.
Six months postoperatively, regenerative changes could not be distinguished from normal findings of nerve fibers on the implants.
Based on these findings, it was thought that the neurosensory dysfunction of the inferior alveolar nerve after implant placement and nerve repositioning was largely due to segmental demyelination of the nerve on the implants, many of which could be recovered.
The mixture of crude BMP and type I collagen as a carrier was implanted in the subcutaneous tissues of 4-week-old and 6-month-old rats. The effect of aging on ectopic bone formation was evaluated after H＆E and type II collagen immunohistochemical staining. On day 7, type II collagen was detected around chondrocytes in 4-week-old rats while in 6-month-old rats, chondrocytes were absent and type II collagen was negative. On day 14, a large number of chondrocytes were observed with strong staining to type II collagen in 4-week old rats but in 6-month-old rats, chondrocytes were hardly seen. On day 21, a large number of trabecular bones with hematopoietic bone marrows were observed in 4-week-old rats but in 6-month-old rats, hematopoietic bone marrow was absent. The absence of chondrocytes on day 7 and their sparsity on day 14 in 6-month-old rats indicates that crude BMP may induce ectopic bone formation mainly through the intramembranous ossification mode in 6-month-old rats but in 4-week-old rats, mainly through endochondral ossification. The results suggested that the differentiation of mesenchymal cells to hard tissue forming cells was delayed and bone formation was quantitatively less in 6-month-old rats than in 4-week-old rats, and that the difference in the ossification mode could be one of the reasons causing the delay and reduction of hard tissue formation in 6-month-old rats.
Part 4． Histopathological Observation of Chitin and Chitosan Films Containing Synthesized Hydroxyapatite under the Periosteum of Rabbits Tibiae：Influence of Deacetylation Degrees and Molecular Weights of Chitin and Chitosan
Kota Yokoyama, Koji Mori, Kazunori Yamakura, Mitsuharu Nakajima, Toshi ...
1997 Volume 10 Issue 3 Pages
Published: June 30, 1997
Released: August 05, 2017
Chitin and Chitosan films (CCF) containing synthesized hydroxyapatite (HA) were made from five different deacetylation degrees and molecular weights of chitin and chitosan. The purpose of this study was to observe tissue reactions and effects of synthesized HA containing CCF under the periosteum of rabbit tibiae on osseous tissue. Histopathological examination was performed at 2, 4, 8, and 12 weeks after CCF implantation. At 2 weeks, in a 65% deacetylation degree CCF, granulation tissue formation with marked inflammatory cell infiltration was observed at implanted sites. In contrast, in more than 88% deacetylation degrees, their inflammatic reactions were mild, and HA components of CCF surrounded by granulation tissue or fibrous connective tissue were present. In addition, newly-formed fibrous bone or osteoids were found in such tissue. These findings were observed in all CCF,except for a 65% deacetylation degree, until 12 weeks after implantation. Cortical bones at implanted sites showed cancellous bone-like appearante caused by endochondral ossification and Haversian canal dilation, but these changes were also observed in CCF unimplanted controls. At 8 and 12 weeks, these osseous tissue changes diminished, and the tissue tended to become compact bone. The effect of different molecular weights on tissue reactions was not clarified in this study. Due to the results of this study, it was found that tissue reactions for CCF under the periosteum depended on deacetylation degrees of chitin and chitosan, and these reactions were considered to be necessary for bone substitute developments to select chitin and chitosan which are suitable for bone repair.
Subcutaneous combined grafts with HA granules and bone marrow were done in the rabbit, and 1) bone formation and modality of HA-bone complex in the combined grafts with HA granules and fresh autogenous bone marrow, 2) bone formation with combined grafts of HA granules and homogeneous bone marrow, and 3) comparison of bone formation in the combined grafts with four categories of HA granules and autogenous bone marrow were investigated.
Our newly developed HA granules and three kinds of HA granules on the market were used in the present experiment. Autogenous or homogeneous bone marrow was obtained from New Zealand white rabbit tibia. Combined materials of each HA granule and bone marrow (volume ratio; 1:1) were grafted on the abdominal subcutaneous tissues of the rabbits. Specimens, removed progressively and stained with hematoxylin and eosin after decalcifying, were observed histologically.
The results were as follows:
1. In the combined grafts with HA granules and fresh autogenous bone marrow, new bone formation, which was induced by osteoprogenitor factor in bone marrow, connected with HA granules in proportion to its maturation and ossicles similar to growing bone with marrow inside were formed.
2. The process of this bone formation was essentially the same as that in fresh autogenous bone marrow used as control.
3. Bone formation in combined grafts of HA granules and homogeneous bone marrow was not recognized.
4. As for compassion of bone formation in combined grafts of four categories of HA granules and autogenous bone marrow, the process of bone formation was different due to chemical composition and shape of HA granules. Especially, in HA granules of Ca excessive contained type and high solubility shape, initial osteoconduction and HA-bone complex formation were disadvantageous.
5. These findings suggested that, considering the behavior of HA granules, this combined graft is used effective in clinical application to soft tissue.
This study was conducted to investigate clinical evaluation of the POI®3-piece implant system (Kyocera, Japan), and follow-up was performed for 2 years after placement of the superstructures.Twenty-three fixtures were inserted and were clinically examined. The clinical parameters were probing depth, bleeding on probing, and other clinical points at 1 year,1 year 6 months, and 2 years after the placement of the superstructures. Probing depth at 1 year ranged from 0.5 mm to 1.5 mm (mean: 1.0 mm), and no bleeding on probing was recognized around the fixtures.
At 1 year 6 months, the probing depth of every fixture indicated the same as at 1 year, and 3 fixtures showed bleeding on probing. The probing depth at 2 years ranged from 1.0 mm to 2.0 mm (mean: 1.2 mm). The probing depth around 5 fixtures increased, and 3 fixtures showed bleeding on probing. However, these implants were clinically maintained and no unusual bone resorption around fixtures was indicated by X-ray photography at 2 years.
It was considered that these results were achieved by plaque control. From this point of view, it was suggested that plaque control was a very important factor for prevention of peri-implantitis.
Al2O3 Implants (Bioceram®） which were installed more than 10 years ago in our clinic, were studied. The number of cases and implants were 75 and 106 respectively. First, the survival and removal rate thereof were checked. A questionnaire was given to the patients in order to find out how satisfied they were with the implants and whether they could masticate well or not. The implants were classified and evaluated by radiographic examination.
As a result, the age of the patients widely ranged from 19 to 69 years. The implant sites were concentrated in the mandibular molar area. 80.2% of examined cases could be followed up, and the 10-year survival rate was 85.9%. Within 4 years, there were no removed implants, however, after 4 years, some implants were removed mostly due to periimplantitis. More than 85% of the patients were satisfied with implants, and 80% of the patients masticated well. By radiographic examination, T-type Bioceram® implant was considered to be the most stable type. The results of this study suggested that the key to long-term success of the implant was to have regular checkups.
This paper describes a case of masticatory rehabilitation using endosseous implant after replacement of the deltopectoral (DP) flap covering the mandibular alveolus with a free mucosal graft.The patient, a 62-year-old Japanese male, underwent 40 Gy of irradiation therapy and hemiglossectomy after a diagnosis of squamous cell carcinoma of the right side tongue, and the defect including the tongue, oral floor, and mandible was reconstructed by the DP flap in 1981.
The postoperative course was uneventful except for the masticatory disturbance due to the inflammatory hypertrophic change of the DP flap. The movable DP flap was replaced with palatal mucosa to obtain attached mucosa for the placement of an endosseous implant in 1993.
Then Brånemark implant was placed in 1994 after 15-session-HBO (hyperbaric oxygen therapy).
The obtained results have been satisfactory both esthetically and functionally for more than 2 years postoperatively.