Junnosuke Ishii

Laser surgery as a treatment for oral leukoplakia.

Various treatment procedures for oral leukoplakia have been reported. However, after some treatments, oral leukoplakia show recurrence and/or malignant transformation, even following complete resection. Furthermore, patients with oral leukoplakia may develop new lesions in other oral cavity locations. Laser surgery for oral mucosal lesions has been reported to have many advantages, and it is widely used in the treatment of oral leukoplakia. In previous studies, recurrence and malignant transformation from the lesion have occasionally been observed following laser surgery. We reviewed the records of oral leukoplakia patients treated with laser surgery to assess its clinical usefulness. It has been reported that the rate of recurrence was 7.7-38.1%, while malignant transformation was 2.6-9% for oral leukoplakia treated with laser surgery. In the present study, there was 29.3% recurrence and 1.2% malignant transformation after laser surgery. This was similar to previous findings. This suggests that non-homogeneous leukoplakia on nonkeratinized epithelia, i.e. the tongue mucosa has a high risk for malignant transformation, so lesions should be excised after detecting abnormal epithelia using vital tissue staining. The wound healing process after laser surgery was satisfactory and no significant complications were observed. Management of oral leukoplakia prevents not only recurrence and malignant transformation, but also postoperative dysfunction: laser surgery is an excellent procedure that is able to overcome these problems.

Management of oral leukoplakia by laser surgery: relation between recurrence and malignant transformation and clinicopathological features.

OBJECTIVE The aim of the present study was to assess the clinical usefulness of laser surgery for oral leukoplakia. BACKGROUND Recurrence and/or malignanT transformation of oral leukoplakia have occasionally been observed following laser surgery. It is reported that the rate of recurrence was 7.7-38.1%, while malignant transformation was 2.6-9%. MATERIALS AND METHODS A total of 154 oral leukoplakias from 116 patients were treated in our department. Comparisons with the rate of recurrence, malignant transformation and clinical futures, epithelial dysplasia, location, and treatment procedure were examined. To evaluate recurrence and malignant transformation, the cases were restricted to those with a minimum follow-up of 6 months. RESULTS A total of 97 lesions fulfilled this criterion. The rate of recurrence had no association with the location or the epithelial dysplasia, although it differed with the treatment procedure. The rate of recurrence in laser surgery was approximately 29%. Malignant transformation was observed in four of 97 lesions. They were observed in 13.6% of tongue cases and 1.8% of gingival cases. Three of four lesions were treated with excision surgery, and the remaining one treated with laser vaporization. Only 1.2% malignant transformation in laser surgery was revealed. CONCLUSION Laser excision is suitable for leukoplakia cases on non-keratinized epithelia (i.e., the tongue and buccal mucosa), while laser vaporization is suitable for the gingival cases. Management of oral leukoplakia prevents not only recurrence and malignant transformation, but also postoperative dysfunction. We believe that laser surgery is an excellent procedure.

Clinical Assessment of Laser Monotherapy for Squamous Cell Carcinoma of the Mobile Tongue

OBJECTIVE Laser monotherapy for squamous cell carcinoma of the mobile tongue treated with CO2 laser was carried out on 18 cases between 1979 and 1997. MATERIALS AND METHODS Three cases recurred after laser surgery. As a subsequent therapy, radiotherapy was performed on two of them and laser surgery was repeated on the remaining one. No recurrences were found in the two patients who died from other diseases after laser surgery. RESULTS The cure rate of primary tumors was 83.3%. One patient had subsequent metastasis after laser surgery. The rate of recurrence and subsequent metastasis was compared between a group of patients treated with laser surgery and a group treated with radiotherapy (interstitial implant). No differences were found in the rate of recurrence between the two groups. While 22 of 52 patients had a subsequent metastasis in the group treated with interstitial implant, only one patient had it in the group treated with laser surgery. There was a statistical difference between these two groups (p < 0.01).

Mucosal Reconstruction Using an Artificial Dermis after KTP Laser Surgery

OBJECTIVE The aim of the present study is to assess the clinical effectiveness of the artificial dermis. BACKGROUND DATA We have previously observed prolonged postoperative pain and bleeding in patients receiving potassium titanyl phosphate (KTP) laser surgery for oral mucosal diseases. MATERIALS AND METHODS The artificial dermis was placed on the wound and fixed to the surrounding oral mucosa by silk suturing. The silicon sheet of the artificial dermis and the sutures were removed on the seventh postoperative day. Postoperative bleeding from the oral mucosa, duration of postoperative pain, and the period required for healing were all assessed clinically. The results were compared to those in a group of similar cases which were treated without the artificial dermis. In this retrospective review, we considered 20 cases of tongue lesion treated by KTP laser (10 leukoplakias, nine squamous cell carcinomas, and one metastatic renal cell carcinoma to the tongue), nine of which were followed by application of an artificial dermis to prevent postoperative pain and bleeding, and 11 of which were not. RESULTS No postoperative bleeding was observed in the group of cases treated with an artificial dermis, although it was observed in 45.5% in the group of cases treated without an artificial dermis. There was a statistical difference between these two groups (p < 0.03). CONCLUSION It was concluded that use of artificial dermis prevented postoperative bleeding.

Use of Magnetic Abutments for Short Endosseous Implants Following a Fibula Bone Graft in an Oral Cancer Patient: A Case Report

Dental implant treatment is an indispensable portion of oral rehabilitation in patients who are to undergo reconstructive surgery following the removal of an oral cancerous lesion. However, ideal dental implant treatment cannot be achieved easily in patients who have undergone mandibular reconstruction with a free vascularized flap, usually because of the limited length, height, and width of the bone graft. Shorter implants (< 10 mm in length) therefore are occasionally used in vascularized fibula graft sites. In such cases, however, shorter implants tend to be overloaded, thereby endangering its longevity. In this article, we discuss how a magnetic abutment system was introduced for such a patient. This was designed to discourage overloading of the mandatory short implants. The outcome was successful without overloading 1.5 years after the placing of the mandibular overdenture.

Inhibitory Effect of Low Power Laser Irradiation on Neurite Elongation from Dorsal Root Ganglion (DRG)

We applied low power laser irradiation on cultured dorsal root ganglion (DRG) which was excised from mouse. Continous wave Ca-Al-As diode laser of 830 nm wave length and 20 mW power output was irradiated for 5-15 minutes. Neurite elongation from DRG was inhibited significantly by laserirradiation. It also inhibited neurite elongation of single neuron isolated from DRG. Especially that of small diameter neuron was significantly inhibited. By immunostaining. neurites including substance P and/or CGRP were shown to be affected severely. These results suggest that inhibitory effect of laser irradiation on neurite elongation may relate to the mechanism of pain attenuation. 緒言 低出力レーザー照射による除痛効果は近年、 医科歯科の臨床において広く応用されつつある が、その作用機序については不明な点が多い。 先に我々はXenopusの 培養三叉神経節を用いて、 神経線維の伸長が低出力レーザーの照射によっ て有意 に抑制 される事実 を発見 した(1)。 そこで 今回の研究では、哺乳類 においても同様の現象 が起 こるかを確かめ るために、マウス培養知覚 神経節(dorsal root ganglion,以 下DRG)を 用 いて、低出カ レーザ ー照射による神経線維の 伸 長への影響について検討 した。