PubMed · 1057824
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
D E Lange. 1975-05-10. [Flap surgery].. https://pubmed.ncbi.nlm.nih.gov/1057824/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The purpose of this study was to examine the morphological changes in alveolar bone osteocytes on the pressure side during experimental tooth movement, using quantitative evaluation on hematoxylin and eosin-stained sections, the TUNEL method, confocal laser scanning microscopy (CLSM), and transmission electron microscopy. In 8-week-old Wistar rats, the left first molar was forced to move mesially with an average load of 10 g by a nickel-titanium superelastic wire. After 6 hours, nuclear condensation and fragmentation appeared in osteocytes adjacent to the hyalinized periodontal ligament (PDL). These cells showed TUNEL-positive reaction. The number of osteocytes with apoptosis progressively increased up to 1 day. At 1 and 2 days, cytoplasmic and nuclear destruction and distribution within the lacunae occurred and increased up to 4 days. The proportion of necrotic osteocytes and near empty lacunae peaked at 2 and 4 days, respectively. At 7 days, necrotic osteocyte and empty lacunae numbers returned to the level of control bone, probably due to resorption of the alveolar bone containing apoptotic and necrotic osteocytes. Ultrastructually, the osteocytes showed apoptotic morphology at 6 and 12 hours and 1 day; at 2 and 4 days, several osteocytes exhibited characteristics of necrosis and destructive images of the surrounding bone matrix, which resulted in enlargement of the lacunae. The present results demonstrate that osteocytes in alveolar bone adjacent to the hyalinized PDL underwent cell death via apoptosis and "secondary necrosis" during orthodontic tooth movement, which may be associated with the subsequent bone resorption.
The objective of the present study was to evaluate the feasibility of using a calcium phosphate cement (CPC) in the reconstruction of a defective alveolar ridge in conjunction with implant placement. The CPC consisted of an equimolar amount of tetracalcium phosphate and dicalcium phosphate anhydrous. At the beginning of the experiment, all mandibular premolar teeth of mature beagle dogs were extracted. After 1 month of healing, alveolar bone was reduced to make a space for a CPC block that was prefabricated from a CPC mixed with water at a powder/liquid ratio of 5 g/mL. After an additional month, 8-mm long hydroxyapatite-coated titanium implants were placed in such a way that the apical half was embedded into alveolar bone and the coronal half in the preformed CPC block. The dogs were sacrificed and biopsies were obtained at 1, 3, and 6 months after surgery. Sections that included implants were evaluated for integration of the CPC block to the alveolar bone and of the implant to the alveolar bone. Additional sections without the implants served as controls. The results obtained from this study show that the CPC ridge augmentation gradually is replaced by natural bone. Six months after surgery, histopathologic features of the augmentation area were quite similar to those of natural alveolar bone. The coronal half of the implants, previously surrounded by the CPC block, was firmly fixed by natural bone. Therefore, this method may be useful for increasing the height of the alveolar ridge.
In earlier studies of Astra Tech and Brånemark System implants, high survival rates and small marginal bone changes have been demonstrated. The aim of this study was to compare the two systems, primarily with regard to marginal bone changes, but also with regard to other clinical variables of interest. The present paper describes the results after three years. Sixty-six patients were included in the study and randomly assigned to treatment with Astra Tech implants (n = 184) or Brånemark System implants (n=187). The marginal bone level was radiographically examined at fixture insertion, at abutment connection, at baseline (delivery of the prosthetic construction) and at 1- and 3-year follow-up examinations. Between fixture insertion and the baseline examination, the pattern of marginal bone resorption differed between the two systems. However, there was no significant marginal bone change between baseline and the 1-year examination or between the 1- and 3-year examinations. Nor were there any differences between the systems. The mean bone loss in the upper jaw between BL (baseline) and 3 years was 0.2 +/- 0.3 mm for Astra Tech implants and 0.2 +/- 0.1 mm for Brånemark System implants. The corresponding figures for the lower jaw were 0.3 +/- 0.2 mm and 0.2 +/- 0.1 mm. The survival rate of Astra Tech implants was significantly higher (98.9%) than for Brånemark System implants (95.2%). However, five of the nine implant losses in the Brånemark group occurred in one patient. For that reason, this result must be interpreted with caution. The number of patients with implant losses did not differ significantly between the systems. Few complications were recorded up to 3 years.