Osteoradionecrosis related to mastication and parafunction

Guided implant surgery on oral cancer patients: in vitro study

PURPOSE

Many oral cancer patients (OCPs) are unable to wear conventional prostheses due to the disease and treatment effects, so they are candidates for oral rehabilitation with osseointegrated implants. A guide suitable for OCPs was designed and tested.

METHODS

Image-guided systems based on a custom template for oral implant placement are now widespread among healthy patients, but this has not been extended to OCPs. The EasyGuideT system (Keystone Dental, Burlington, MA, USA) for template stabilization is used on healthy edentulous patients, achieved by bone screws, mini-implants or stereolithography with a bone support. All these systems are invasive and cannot be used in many oral cancer patients. We adapted the EasyGuideT to OCP rehabilitation. The first stage focused on developing a template-positioning system for use on edentulous mandibles that is non-invasive, repeatable, stable on the oral mucosa, consistent with the operating room asepsis, and comfortable for the patient. This repositioning system consists of a cube fiducial marker and an extra-oral support using a facial thermoplastic mask. The mask is linked to the surgical template through the cube. The second stage consisted of direct evaluation of the repositioning system reproducibility, performed on 5 adult cadaver skulls.

RESULTS

The translation errors and rotation errors obtained using the modified EasyGuideT system were satisfactory in ex vivo experiments on cadaver skulls.

CONCLUSION

A non-invasive repositioning system for image-guided implant surgery on oral cancer patients is clinically feasible using a cube fiducial marker and extra-oral support with a facial thermoplastic mask.

Oral sequelae of head and neck radiotherapy

In addition to anti-tumor effects, ionizing radiation causes damage in normal tissues located in the radiation portals. Oral complications of radiotherapy in the head and neck region are the result of the deleterious effects of radiation on, e.g., salivary glands, oral mucosa, bone, dentition, masticatory musculature, and temporomandibular joints. The clinical consequences of radiotherapy include mucositis, hyposalivation, taste loss, osteoradionecrosis, radiation caries, and trismus. Mucositis and taste loss are reversible consequences that usually subside early post-irradiation, while hyposalivation is normally irreversible. Furthermore, the risk of developing radiation caries and osteoradionecrosis is a life-long threat. All these consequences form a heavy burden for the patients and have a tremendous impact on their quality of life during and after radiotherapy. In this review, the radiation-induced changes in healthy oral tissues and the resulting clinical consequences are discussed.

Conservative management of osteoradionecrosis

A retrospective records analysis of 32 patients with mandibular osteoradionecrosis seen between August 1960 and September 1995 was undertaken to determine the effectiveness of nonsurgical/nonhyperbaric oxygen conservative management. Two patients died before final analysis. Of those alive, 65.5% of patients were spared resection, having lesions resolve (48.3%), improve (3.4%), or asymptomatically stabilize (13.8%). Sequestrum production allowing "gentle" removal predicted a more favorable clinical course when managed conservatively compared with nonsequestrating lesions (p < 0.05). Criteria to define clinical osteoradionecrosis are proposed.