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The pathogenesis of bisphosphonate-related osteonecrosis of the jaw (BRONJ) remains unknown, and the development of a reliable experimental model would help to improve our understanding of it. We used 12 domestic pigs of which 6 made up the experimental group and were treated with zoledronate 4mg intravenously weekly for 5 weeks, while the control group (n=6) were given no drugs. On day 60 the right second maxillary and mandibular third molars were extracted. Thirty days later 3 animals in each group were killed; the rest were killed 90 days later. Histopathological specimens from the extraction sites were analysed for bone density, collagen architecture, density of osteons, and the amount of non-mineralised bone. Bone density, amount of non-mineralised bone, and density of osteons differed significantly between the 2 groups (p0.001 in each case), but the chromatic pattern dictated by the collagen architecture did not. Our results correspond to the observations that have been made in patients with BRONJ, which means that the histomorphometric conditions seen in patients can be reproduced in this experimental setting.

Introduction Recently new concepts for the treatment of oral squamous cell carcinomas (SCC) have been developed, which include preoperative simultaneous neoadjuvant radiochemotherapy (RCT) and one stage operation with excision of the tumour and reconstruction. When we consider long-term survival, we find substantial evidence that combined treatment based on neoadjuvant radiochemotherapy is superior to adjuvant treatment including operation and postoperative radiation. Patients and methods We studied two groups consisting of 74 patients given neoadjuvant treatment and 54 treated surgically. Ninety-nine patients suffered from stage III and IV diseases according to the UICC-criteria. Long-term survival was estimated by the Kaplan–Meier method. Results Neoadjuvant treatment increased the prospect of a long-term survival free of tumour. Kaplan–Meier curves estimated a 5-year tumour-free survival in oral squamous cell carcinoma category T1 as 83% in the neoadjuvant group and 70% in the adjuvant group; the corresponding figures for T2 were 79% and 57%, for T3 68% and 33% and for T4 51% and 30%, respectively. The difference for T1, T2 and T4 tumours were significant. The preoperative radio- and chemotherapy were shown to be effective by the fact that pathohistologically resection specimens were free of tumour in 28 patients in the neoadjuvant group. Four patients died during the preoperative combination treatment. Of the patients, 65% in the adjuvant group and 72% in the neoadjuvant group survived the observation period. Conclusion The neoadjuvant treatment results in better 5-year-survival rate than adjuvant treatment.

The osteoinductive potential of the periosteum can be stimulated by raising the periosteum using a type of distraction. This was tested and confirmed in an animal experiment in 6 Goettingen minipigs. A titanium mesh was implanted beneath the periosteum and then raised. Bone formed underneath the mesh, with rows of micro-pillars similar to those found after osteodistraction. The main advantages of dynamic periosteal elevation are that invasion and morbidity are minimal. Clinically it might be applicable in craniomaxillofacial surgery, in augmentation before implantation, and in reconstruction of the skull.

In 1998 we harvested a total of 127 bone grafts from the iliac crest of 65 male and 53 female patients aged 8-80 years. We measured the quantity of bone obtained, the operating time and the donor site morbidity of the anterior approach (n=81) compared with the posterior approach (n=46). The mean volume of bone harvested was 15 cm(3) (range: 9-25.5) of monocorticocancellous- or bicortico-cancellous bone chips or those from a trephine bur. The mean operating time for the anterior approach was 35 min (range: 22-48), for the posterior approach 40 min (range: 32-55). There were 15 complications, which were limited to those in whom the volume of bone exceeded 17 cm(3). The posterior approach caused less morbidity, notably in the form of significantly less pain and irregularity of gait. The patient has, however, to be repositioned during operation, which added to its total duration.

Inflammatory lesions of the vascular endothelium after preoperative radiotherapy often cause healing-delayed healing of free flaps in the irradiated graft bed. We investigated changes in neovascularization in the transition area between grafted tissues and irradiated tissues of the graft bed. We irradiated the neck(30 and 50 Gy total dose) in 102 Wistar rats and then grafted a free myocutaneous gracilis flap to the irradiated region of the neck 4 weeks later. We examined histologically the tissues of the graft, the transition area between the graft and the irradiated graft bed, and the graft bed. In contrast to control rats, the tissues in the irradiated animals showed a qualitatively reduced and a more irregular capillary distribution, with substantial fibrosis in the irradiated graft bed. We also found significant differences in vascularization and mean capillary lumen in the transitional zone between graft and graft bed in the irradiated rats compared with controls (P = 0.004 and P < 0.001, respectively). Both number and diameter of capillaries were reduced in the irradiated graft bed tissue. The graft failed to improve vascularization in the transitional zone between graft and irradiated tissue, so we conclude that it is the vascularization status of the bed tissue rather than that of the transplant tissue that is the limiting factor for graft healing.

The use of distraction osteogenesis in the hypoplastic maxilla and midface is still controversial. Since the beginning of 1998, 25 patients have been treated with osteodistraction techniques for various reasons. Among them were four patients who were treated by high LeFort I osteotomies and insertion of a newly developed subcutaneous distraction device in the malar region. Distraction osteogenesis was successful in all four cases resulting in a mean sagittal bone gain of 12.0 mm (range 7-14) at the level of distractor fixation. All patients were kept under orthodontic supervision during osteodistraction. The final occlusal relation was satisfactory. Cephalometric measurements after distraction showed an anterior rotational movement of the midface region. As the question of relapse and further growth is still not clear, Delaire masks are used to stabilize the surgical result after removal of the distractor. The importance of long-term follow-up is stressed.