PubMed · 7038101
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F M Gardner, C G Stankewitz. 1982. Using removable gingival facades with fixed partial dentures.. https://doi.org/10.1016/0022-3913(82)90153-6
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The origin of fibroblasts, their proliferative activity and roles in the early stages of periodontal repair were investigated in order to better understand the periodontal healing process in furcation defects of the beagle dog after guided tissue regenerative therapy. Newly divided cells were identified by immunolocalization of bromodeoxyuridine (BrdU) injected 1 hour prior to sacrificing the animals. At 1 and 2 weeks after creation of the defects, the lesions were occupied primarily by granulation tissue. Under this condition, periodontal ligaments (PDL) fibroblasts in a coronal portion of the remaining PDL close to wounds proliferated actively, migrated along the root surface and formed fibrous connective tissue on the surface. Similarly, the fibroblasts adjacent to the bone surface also showed proliferative activity and engaged in active formation of fibrous connective tissue on the bone surface. The majority of labeled cells in both areas were located in the extravascular area. At 3 and 4 weeks, the defects were filled with an increased amount of new connective tissue and bone. The labeled fibroblasts were preferentially found in the most coronal portion of connective tissue formed on the root surface that was in direct contact with inflamed tissue, and the collagen fibers projected into granulation tissue. In areas of active bone formation, numerous labeled fibroblasts were located in connective tissue adjacent to the newly-formed bone. However, fibroblasts in the endosteum of new bone were rarely labeled These results indicate that fibroblasts involved in periodontal repair originate primarily from both the remaining PDL and alveolar bone, and actively engage in fibrous connective tissue formation in the early stages of periodontal repair The ability of PDL fibroblasts to proliferate, migrate, and form connective tissue on the root surfaces in the early repair stages appears to play a crucial role in the formation of the PDL and cementum, and consequently, in periodontal regeneration in the absence of root resorption and ankylosis. As the formation of new connective tissue and bone continues, the precursor cells for fibroblasts and osteoblasts are supplied locally through the continued divisions of the fibroblastic cells in association with the newly-formed connective tissue. Paravascular and endosteal cells appear to be minor contributors to new cell population during furcation defect repair in the beagle dog.
The blade-/plate-form implant is the only endosseous implant which has proved to be successful under three different types of integration: fibrous integration, when the layer of fibrous or collagenous tissue interspersed between implant and bone is less than 125 microns; fibro-osseous integration, when there is a combination of thinly defined fibrous connection with 22% or less direct bone contact with the implant; and osseous integration, when there is 23% or more direct bone-to-implant contact, with no evidence of fibrous connective tissue anywhere. The blade implant is an unique versatile device which has passed with success the test of time (some of them being in function for as long as 28 years) and deserves more attention from implantologists around the world.
The purpose of this study was to investigate the mechanisms of bone resorption in the rat dentoalveolar complex occurring as a result of orthodontic appliance therapy. Utilizing whole body radioactive cobalt 60 (Co60) irradiation in combination with orthodontic tooth movement, the activation, recruitment, and life span of osteoclasts was studied. Thirty-four adult Fischer 344 rats were irradiated with 10 and 20 Gray of Co60. Twelve days after irradiation, each rat was fitted with an orthodontic appliance; the rats were sacrificed 7, 14, or 21 days after appliance placement. To serve as controls, another group of 12 rats was subjected to orthodontic treatment only. Histologic sections were prepared from decalcified maxillary alveolar process, and osteoclasts were counted. In the control group, osteoclasts were presence in the periodontal membrane for four weeks after appliance placement, and the largest number of osteoclasts was observed in the second week. The smaller total irradiation dose (10 Gray, administered in 5 daily fractions) induced a transient reduction in the bone marrow cell count of more than 90%, followed by a complete rebound. The peak osteoclst number also was increased 110%. In contrast, the higher total dose (20 Gray, administered in 10 daily fractions) resulted in a reduction of 60% in bone marrow cellularity and a decrease in the peak osteoclast number by 40%. Fluctuations in bone marrow cellularity generally corresponded to similar variations in the osteoclast number, but there was an apparent lack of correspondence between bone marrow cell and white blood cell values. The total period of osteoclastic presence in the periodontal membrane following orthodontic activation, normally four weeks in duration, was reduced by one week in the irradiated animals. These findings lead us to speculate that the mechanisms of osteoclast activation and recruitment following orthodontic appliance therapy may involve three consecutive waves of osteoclast maturation. The total duration of osteoclastic bone resorption lasts 4 weeks, but the osteoclast lie span is calculated to be 9 to 10 days (9 days x 3 waves = 27 days). If the results of this study are proved to be reproducible, a scientific basis may have been provided to support the common practice in orthodontics wherein the duration between orthodontic appointments is 4-5 weeks.