Distraction osteogenesis of free flap reconstructed mandible following ameloblastoma resection for optimal functional rehabilitation.

This case highlights the use of a custom-made distractor (Synthes GmbH, Oberdorf, Switzerland), used to increase bone height prior to rehabilitation with implant placement, in a patient following excision of an ameloblastoma and reconstruction of her mandible with a fibular flap. A 27-year-old patient had her mandible reconstructed following wide resection of an ameloblastoma. Although a 2.0 LOCK reconstruction plate (Synthes GmbH, Oberdorf, Switzerland) was used for fixation of the fibular bone, the vertical deficiency between the reconstructed segment and the occlusal plane made oral rehabilitation impossible. To overcome this, the fibular bone segment was vertically distracted following a latency period of 4 days. Distractor was left in place for 20 weeks for bone consolidation. Following device removal implants were placed. The novelty of this approach included fixation of the lower arm of the distractor on the LOCK plate. The distractor was unidirectional with two arms of different length. The lower arm composed of a 2.0 mini-plate to fit exactly on the 2.0 LOCK plate whereas the upper arm used a standard 1.5 mini-plate. Advantages of this custom-made distractor included: (i) No need for removal of the reconstruction plate, (ii) no need for an extraoral surgical approach, and (iii) no need for additional drilling to fit the lower arm of the distractor. Technical details and limitations are presented.

A novel closed-loop electromechanical stimulator to enhance osseointegration with immediate loading of dental implant restorations.

The degree of osseomechanical integration of dental implants is acutely sensitive to their mechanical environment. Bone, both as a tissue and structure, adapts its mass and architecture in response to loading conditions. Therefore, application of predefined controlled loads may be considered as a treatment option to promote early maturation of bone/implant interface prior to or in conjunction with crown/prosthesis attachment. Although many studies have established that the magnitude, rate of the applied strain, and frequency have significant effects on the osteogenic response, the actual specific relationships between strain parameters and frequency have not yet been fully defined. The purpose of this study was to develop a stimulator to apply defined mechanical stimuli to individual dental implants in vivo immediately after implantation, exploring the hypothesis that immediate controlled loading could enhance implant integration. An electromechanical device was developed, based on load values obtained using a two-dimensional finite element analysis of the bone/implant interface generating 1000 to 4000 pe and operated at 30 and 3 Hz respectively. The device was then tested in a cadaveric pig mandible, and periosteal bone surface strains were recorded for potential future comparison with a three-dimensional finite element model to determine loading regimens to optimize interface strains and iterate the device for clinical use.

Multiple-site osteosarcomas of the jaw in a single patient. A true case of a metachronous lesion?

A case of multiple-site osteosarcomas in the jaw of a 56-year-old patient is reported. The disease occurred consecutively at three different sites (left maxilla, left mandible, right mandible) separated by time intervals of 12 and 18 months, respectively. Metachronous osteosarcomas of the long bones is a rare form of osteosarcoma and implies multiple lesions appearing at different times, each one behaving clinically as a primary lesion. The pathogenesis of this disease is unknown as it is unclear whether the lesions represent independent primary tumours or metastatic disease.

Rehabilitation of severe maxillary atrophy with zygomatic implants. Clinical report of four cases.

Rehabilitation of the severely resorbed maxilla poses a difficult challenge, for both restorative and surgical colleagues, as the typically large maxillary sinuses in this group of patients require extensive bone grafting if root form dental implant placement is considered. Acceptance is low, due to disadvantages associated with: i) an additional surgical procedure for an iliac bone graft harvesting and, ii) an overall delay in delivery of the final implant-supported prosthesis. The zygomatic implant placement procedure does not require any adjunctive procedures. Furthermore, the ability to immediately use existing dentures and the lack of need for bone grafting and prolonged hospitalisation makes this treatment modality more acceptable to the patient. Four cases are reported that demonstrate the successful treatment of a severely atrophic maxilla with either a fixed prosthesis supported by two zygomatic and a minimum of three standard dental implants or an overdenture supported by two zygomatic and one standard dental implant.

A novel approach to bite force measurements in a porcine model in vivo.

A novel device for a bite force measurement system in a porcine model is described. A single polyethylene layer was vacuum-formed into a splint, and a force sensor was fitted on to the splint occlusal surface and seated with a silicone layer. This design enabled the measurement of bite forces on selected teeth in a large animal model with either natural dentition or single implant crowns and could be used in assessing information on biomechanical adaptation of the bone-implant interface to masticatory loads. Preliminary recordings of force values obtained during mastication in the premolar region (200-560 N) and various limiting factors of the technical design are discussed.