Segmental Mandibular Resection Research Articles

下顎骨部分切除後の治癒過程における微細血管構築について

In this study, the relationship between osseous hiealing and microvascular changes was investigated utilizing an osseous-microvascular corrosion casting specimen of mandibular segmental defects (5×3mm) made using an ultrasonic blade in the rabbit. Specimens were prepared at 1, 2, 3 and 4 weeks postoperatively, and studied under light and scanning electron microscopes. At 1 week, neovascularization arose from preexisting vessels of inferior alveolar artery and mandibular periosteum. New bone formation was first seen at the fundus of the defect, and newly-formed trabeculae spread richly between new sinusoidal capillaries. At 2 weeks, there were increased signs of vascularization at the fundus of the defect, and the sinusoidal capillaries gave rise to new capillarise that had independent lumina and formed an interconnected network. Newly formed trabeculae developed to establish a bridge between the cut ends of the defect. At 3 weeks, the new bone formation or deposition observed previously increased in thickness. At 4 weeks, the defects were filled with the newly-formed bone, which rose to the level of the mandibular border. The periosteal vascular network was gradually remodeled to a normal pattern.It is concluded that microvasculature formed during all stages of osseous healing after mandibular segmental resection contributes to new bone formation and development. It is therefor beneficial to maintain the existing vessels of the inferior alveolar artery using an ultrasonic blade.

Osseointegrated implants in microvascular fibula free flap reconstructed mandibles

In the past, prosthodontic rehabilitation of patients who underwent segmental mandibular resection relied on removable prostheses, which were less than ideal. The advent of the microvascular free flap has provided improved appearance and function through reconstruction of the skeletal integrity of the mandible. In select patients Osseointegrated implants strategically placed in the reconstructed mandible can be used to restore masticatory function. Patient selection criteria and techniques are discussed.

CHANGING TRENDS IN THE MANAGEMENT OF CARCINOMA OF THE ORAL CAVITY AND OROPHARYNX

Two groups of patients with squamous cell carcinoma of the oral cavity and oropharynx treated by radical surgery were studied. Special emphasis was placed on analysing changing trends in reconstruction and the management of the mandible and their influence on complication rates, length of hospital stay and tumour control rates. Group 1 consisted of 97 patients treated between 1980 and 1984 and Group 2 consisted of 153 patients treated between 1987 and 1991. Anatomical distribution of cancers and clinical stages were similar in the two groups. The major trends identified were: (i) the increasing use of free flaps for reconstruction (0 in Group 1, 41% in Group 2); (ii) more conservative mandibular resection and the increasing use of mandibular swing procedures (1% in Group 1, 16% in Group 2) rather than segmental mandibular resection (44% in Group 1, 13% in Group 2); (iii) fewer procedures per patient (2.6 per patient in Group 1, 1.2 per patient in Group 2); and (iv) a decrease in mean duration of hospital stay from 34 to 16 days and fewer complications. Patients in Group 2 also had a lower rate of local recurrence of cancer when compared with patients in Group 1 (19 vs 29%).

The use of liquid nitrogen cryotherapy in the management of locally aggressive bone lesions

Cryosurgery has a unique role in the management of locally aggressive osseous lesions. By using a combination of enucleation and cryosurgery to devitalize the surrounding bone, the need for segmental mandibular resection is decreased. This article reviews 37 cases managed successfully in this manner.

Erosion and heterotopic bone formation after alloplastic temporomandibular joint reconstruction.

Twenty-three temporomandibular joint arthroplasties using metallic condylar prostheses were performed because of severe ankylosis (8 patients), segmental mandibular resections in tumor surgery (9 patients), and after extensive trauma (2 patients). A clinical and radiological follow-up study showed heterotopic bone formation in 52% of cases and glenoid fossa resorption in 43%. In one patient with rheumatoid arthritis the condyle eroded through the skull base 10 months after surgery. Seven prostheses (30%) were removed and/or exchanged during the average 27.6-month follow-up.

Results of irradiation in the squamous cell carcinomas of the anterior faucial pillar-retromolar trigone.

Between January 1966 and August 1981, 159 patients with previously untreated squamous cell carcinomas of the anterior faucial pillar or retromolar trigone received definitive radiation therapy at The University of Texas M. D. Anderson Hospital and Tumor Institute. All except 11 patients were treated by external radiation including combination of electron beams with high-energy photons or 60Co to doses ranging from 60 Gy to 75 Gy. In the N0 patients, as a rule, only the ipsilateral subdigastric nodes were treated electively to a dose of 50 Gy. The 5-year determinate survival rate for the overall group was 83%. The cumulative recurrence rate showed that 92% of the patients had recurrence by 2 years. Therefore, all patients except those who died with no evidence of local disease less than 2 years after treatment were evaluated for local control. The failure rate for the evaluable patients was 29% for T1 lesions, 30% for T2 lesions, 24% for T3 lesions, and 40% for T4 lesions. After salvage surgery, which consisted of intraoral resection in one-third of the patients and of a composite operation in the other two-thirds, the ultimate failure rate was 0% for T1 lesions, 6% for T2 lesions, 8% for T3 lesions, and 20% for T4 lesions. Whereas stage was a poor indicator for treatment outcome, there was a significantly higher failure rate for infiltrative and/or ulcerated lesions (35%) than for exophytic or superficial lesions (15%). Histologic grade was of no prognostic significance, nor was there any significant difference in the failure rate for lesions originating on the anterior faucial pillar versus that for lesions on the retromolar trigone. Following radiotherapy, 30% of the patients developed some degree of bone exposure but only 5.6% (9 patients) required a segmental mandibular resection. The probability of bone exposure was not dose related and more likely reflected tumor location on the mucoperiosteum. Of the whole group, 16 patients (10%) experienced a neck failure with 8 ultimate failures after salvage surgery. Among the 16 patients who had neck failures, 13 were originally staged N0; 6 of these patients had failures that occurred in the electively treated ipsilateral subdigastric area, but the field was too small to cover the nodes adequately. Aspects of the radiotherapy techniques with combined electron and photon beams that may influence the treatment outcome are discussed.

Mandibular involvement by oral squamous cell carcinoma.

Detecting mandibular bone involvement by oral carcinoma prior to definitive therapy poses a difficult problem for the head and neck surgeon. A retrospective study of 104 patients who underwent segmental mandibular resection for oral squamous cell carcinoma was undertaken to detect the incidence of mandibular bone involvement. Specimens from 23 patients (22%) demonstrated tumor invasion on decalcified histologic examination. Histologic evidence of bone involvement was correlated with the site of lesion, stage of the disease, the grade of tumor, the clinical impression of bone involvement, and the presence or absence of neck disease. Bone invasion on histologic examination was also compared with preoperative bone scans and radiographs. The data obtained demonstrates significant mandibular involvement with alveolar tumors and lesions clinically adjacent to the mandible. There was also a high incidence of histologic bone involvement in patients who had radiologic or bone scan evidence of tumor erosion. We support segmental mandibulectomy on the basis of providing adequate tumor margins for patients fulfilling these criteria.

Masticatory rhythm analyzing method and clinical application.

The rhythm of mastication is one of the important factors in evaluating the masticatory function. This masticatory rhythm should be observed from both the mandibular movements and masticatory muscular activities. In addition, the changes in the rhythm from the beginning to the end of the mastication process should be reflected by the chosen parameters. In order to achieve this, a new analyzing method was devised in which the electromyographic burst duration time was divided into three divisions based upon the mandibular movement phase, and two parameters were chosen to represent the rhythm. In this paper, the new method was used on the patients with a temporomandibular joint dysfunction and patients who had a mandibular segmental resection in order to evaluate its validity and clinical applicability. By the comparison of the masticatory rhythms before and after treatment, the effectiveness of this analyzing method in evaluating the masticatory functions was shown.