Surgical removal of keratocystic odontogenic tumours via a Le Fort I osteotomy approach: a retrospective study of the recurrence rate.

The keratocystic odontogenic tumour (KCOT) is one of the most aggressive odontogenic cysts and has a high recurrence rate. The treatment of these tumours is the subject of debate. A KCOT in the posterior maxilla with sinus involvement is rare. Few reports have been published in the literature. The purpose of this study was to evaluate the recurrence rate after surgical removal of maxillary KCOTs via a Le Fort I osteotomy. A search was performed to identify patients with a follow-up time of at least 5 years. Nine patients were included in the study. The following clinical variables were analyzed: age at surgery, sex, symptoms, site and size of the tumour, surgical approach, and recurrence rate. The surgical approaches were curettage (n=6) and enucleation (n=3). Recurrence was seen in three patients (33%); all had multilocular tumours. No recurrence was seen in patients with unilocular tumours. The Le Fort I osteotomy approach allows direct visualization and ensures wide excision, minimizing the risk of recurrence. In this series, cases with a multilocular KCOT showed a higher risk of recurrence due to the difficulty of removing the tumour in total. All recurrences took place within 2 years of the intervention; a 5-year follow-up is recommended.

Randomised trial of bisphosphonate-coated dental implants: Radiographic follow-up after five years of loading.

The results of a randomised trial with bisphosphonate-coated dental implants have been reported previously. Each patient received one coated and one uncoated implant in a double-blind split-mouth design study. After 6 months of osseointegration, resonance frequency analysis indicated better fixation of the coated implants. Reduced marginal bone resorption was also shown. However, it was not known whether the advantage of the bisphosphonate coating would persist over time. The radiographic results at 5 years after implant installation are reported herein. A blinded investigator measured marginal resorption on fresh radiographs obtained for 14 of the 16 patients (two had died) and compared these with the post-implantation images. Non-parametric statistics were used. All implants functioned well. The median marginal bone loss for control implants was found to be 0.70mm, which is less than usually reported in the literature. The bisphosphonate-coated implants showed even less resorption (median 0.20mm). The median difference within each pair of implants after 5 years of use was 0.34mm (95% confidence interval 0.00-0.75mm; P=0.04). The present data suggest that bisphosphonate-coated implants enable prolonged preservation of the marginal bone.

Prevention of osteonecrosis of the jaw by mucoperiosteal coverage in a rat model.

There is evidence for a link between the use of systemic bisphosphonates and osteonecrosis of the jaw (ONJ). This condition has the appearance of chronic osteomyelitis, and antibiotics prevent the development of ONJ in animal models. Clinically, ONJ can sometimes be treated successfully by mucoperiosteal coverage. If ONJ is indeed primarily caused by bacterial infection, immediate coverage of the extraction alveolus might reduce the risk of ONJ developing in risk patients. Therefore, we studied whether immediate mucoperiosteal coverage after tooth extraction could prevent the development of ONJ in a rat model. Thirty rats were randomly allocated to three groups (10 in each): (1) group I (controls): extraction, no drug treatment; (2) group II (non-coverage): extraction, dexamethasone plus alendronate; (3) group III (coverage): extraction, dexamethasone plus alendronate, plus coverage with a mucoperiosteal flap. Rats were examined for macroscopic ONJ-like wounds after 2 weeks. All animals in the non-coverage group developed large ONJ-like changes. The coverage and control groups showed an intact overlying mucosa in all rats. Findings were confirmed with histology. Bisphosphonates and dexamethasone caused ONJ-like lesions after tooth extraction in a rat model. This was prevented by immediate mucoperiosteal coverage. The risk of ONJ in patients using bisphosphonates might be reduced by mucoperiosteal coverage after tooth extraction.

Effect of local vs. systemic bisphosphonate delivery on dental implant fixation in a model of osteonecrosis of the jaw.

Locally applied bisphosphonates may improve the fixation of metal implants in bone. However, systemic bisphosphonate treatment is associated with a risk of osteonecrosis of the jaw (ONJ). We hypothesized that local delivery of bisphosphonate from the implant surface improves the fixation of dental implants without complications in a setting where systemic treatment induces ONJ. Forty rats were randomly allocated to 4 groups of 10. All groups received a titanium implant inserted in an extraction socket. Group I received the implants only. Group II received dexamethasone (0.5 mg/kg). Group III received dexamethasone as above plus alendronate (200 µg/kg). Group IV received zoledronate-coated implants and dexamethasone as above. The animals were sacrificed 2 weeks after tooth extraction. All 10 animals with systemic alendronate treatment developed large ONJ-like changes, while all with local treatment were completely healed. Implant removal torque was higher for the bisphosphonate-coated implants compared with the other groups (p < 0.03 for each comparison). Micro-computed tomography of the maxilla showed more bone loss in the systemic alendronate group compared with groups receiving local treatment (p = 0.001). Local bisphosphonate treatment appears to improve implant fixation in a setting where systemic treatment caused ONJ.

Bisphosphonate coating might improve fixation of dental implants in the maxilla: a pilot study.

This pilot study evaluates the clinical stability of bisphosphonate-coated dental implants placed using a two-stage surgical procedure in five patients. Each patient received seven regular Brånemark implants, one of which was coated with bisphosphonate in a fibrinogen matrix. The coated implant was inserted where the bone was expected to have the least favourable quality. The level of the marginal bone around each implant was measured by intraoral periapical radiographs and implant stability was recorded using resonance frequency measurements. Frequency values (ISQ) were obtained peroperatively before flap closure and after 6 months at abutment connection. At abutment connection the bisphosphonate-coated implants were removed en bloc in two patients for histological examination. An animal experiment had previously confirmed that gamma-sterilization did not reduce bioactivity of the bisphosphonate coating. In each patient, the bisphosphonate-coated implant showed the largest improvement in ISQ level of all implants. Their values at the start tended to be lower, and the absolute value at 6 months did not differ. No complications occurred with the coated implants. Histology showed no abnormalities. Improvement in ISQ values was an expected effect of the bisphosphonate coating, but could be due to the choice of insertion site. This finding warrants a randomized, blinded study.