The aim of the present study was to evaluate bone formation following maxillary sinus augmentation using bovine bone substitute material Bio-Oss in combination with venous blood by means of histologic and histomorphometric examination of human biopsies. This involved a total of 15 sinus floor elevation procedures being carried out on 11 patients (average age of 49.6 years) according to the technique described by Tatum (1986). The subantral sinus cavity was augmented using bovine apatite combined with venous blood. After an average healing phase of 6.8 months, trephine burrs were used to take 22 bone biopsies from the augmented sinus region. Then 38 Brånemark implants were inserted in both the osteotomies resulting from bone sampling and in regular sites in the augmented posterior maxilla. Histomorphometric analysis of ground sections from the bone biopsies prepared according to the standard method of Donath & Breuner (1982) produced an average percentage of newly-formed bone of 14.7% (+/- 5.0%) and a proportion of residual xenogenic bone substitute material of 29.7% (+/- 7.8%). Some 29.1% (+/- 8.1%) of the surface of the Bio-Oss granulate was in direct contact with newly-formed bone. Histologically, newly-developed bone became evident, partly invaginating the particles of apatite and forming bridges in the form of trabeculae between the individual Bio-Oss particles. Despite the absence of osteoclastic activity, the inward growth of bone indicates slow resorption of the xenogenic bone graft material. When the implants were uncovered, after an average healing phase of 6 months, 4 of the 38 implants had become loose. Of these 4 implants, 1 had to be subsequently explanted, while the others remained as "sleeping implants" and were not included in the implants superstructure. Thus, the resulting clinical survival rate, prior to prosthetic loading, was 89.5%.

No abstract

No abstract

No abstract

The aim of this study was to investigate experimentally the effect of long term orthodontic loading on the stability as well as on the peri-implant bone findings of short titanium screw implants (Bonefit, submersion depth 6 mm, phi 4 mm) inserted in regions with reduced vertical bone height. For this purpose, 6 maxillary premolars (1P1, 2P2, 3P3) were extracted from each of 2 foxhounds and reduction of alveolar bone height was performed by osteotomy. After a 16-week healing period, 8 implants (4 per dog) were inserted in the edentulous areas. Simultaneously, 2 implants (1 per dog) were positioned in the palatal suture (one-stage surgery). After an 8-week implant healing period, the fixtures in the P1/P2 areas (n = 4) and the palate (n = 2) were loaded (test implants) by means of transpalatal bars running anteriorly, fixed on the implants in the P1/P2 areas, and Sentalloy traction springs (approximately 2 N continuous force) inserted midsagittally between palatal implants and bars (force application period: 26 weeks). The fixtures in the P2/P3 areas served as controls (n = 4). Clinical measurements and histological evaluation revealed no implant dislocation of the loaded fixtures. These results suggest that short titanium screw implants inserted in the alveolar bone and palatal suture region retain their stability during long-term orthodontic loading, even following a relatively short unloaded implant healing period. Furthermore, it seems that long-term orthodontic loading may induce marginal bone apposition adjacent to the implants.