The results of CO2 laser surgery in patients with oral leukoplakia: a 25 year follow up.

Oral leukoplakia is an important premalignant lesion of the oral mucosa. We treat this lesion prophylactically with CO2 laser evaporation. In the period from 1976 to 2001, a group of 200 patients with 282 oral leukoplakias were treated by CO2 laser evaporation. In a follow up period of 1-219 months (mean 52), 251 treated leukoplakias (89.0%) did not show a recurrence. Twenty eight (9.9%) local recurrences were observed in 5 to 168 months after treatment. Three (1.1%) squamous cell carcinoma, occurred in the treated area respectively 7, 17 and 19 month after CO2 laser evaporation. This large study with a long follow up shows that laser treatment is a good prophylactic treatment for oral leukoplakia.

Distribution of aluminum phthalocyanine disulfonate in an oral squamous cell carcinoma model. In vivo fluorescence imaging compared with ex vivo analytical methods.

Photosensitizer-induced fluorescence is studied as a technique for the detection of cancer. Therefore we investigated the ability of a photosensitizer, aluminum phthalocyanine disulfonate (AIPcS2), to localize in tumor tissue. In vivo endoscopic fluorescence imaging, fluorescence microscopy, conventional spectrofluorometry and high performance liquid chromatograpy combined with diode laser-induced fluorescence (HPLC-Dio-LIF) were used. Squamous cell carcinomas were induced with 4-nitro-quinoline-1-oxide (4NQO) in the mucosa of the palate of the rat. In vivo fluorescence images, taken after injection of 1.5 mumol/kg AIPcS2 intravenously, showed that 4NQO-treated palates had higher fluorescence signals than normal palates. Areas displaying locally high amounts of AIPcS2 fluorescence (hot spots) were present only in 4NQO-treated rats 2-8 h but had disappeared 24 h after injection. However, HPLC-Dio-LIF showed that the relative AIPcS2 content was highest at 24/48 h in biopsies taken in the areas of the hot spots. Fluorescence microscopy revealed that AIPcS2 was present only between 2 and 8 h in the epithelial layer, while in biopsies the connective tissue contained large quantities of AIPcS2 at 24/48 h. In vivo fluorescence imaging appears to show mainly fluorescence from the epithelial layer and the ex vivo analytical techniques mainly show the connective tissue fluorescence. Care should be taken when interpreting data using one technique only.

Carbon dioxide laser evaporation of leukoplakia of the lower lip: a retrospective evaluation.

The purpose of this study was the retrospective evaluation of the treatment results of CO2 laser evaporation for 27 cases of leukoplakia of the lip. The data were derived from 23 patients who presented with leukoplakia of the lower lip during the period 1978-96. Four patients developed a second primary leukoplakia of the lip resulting in 27 cases of leukoplakia. All lesions were treated with a CO2 laser equipped with an operation microscope and micromanipulator. Short-term evaluation showed complete epithelialisation 4 weeks after CO2 laser evaporation; there was minimal scar formation and no subsequent interference with normal lip function. During long-term evaluation, four recurrences (14.8%) were diagnosed which developed between 5 and 31 months after treatment, these were retreated with CO2 laser evaporation. There was no development of squamous cell carcinoma in the CO2 laser-treated area. Selective removal of affected epithelium with minimal damage to surrounding structures is possible using CO2 laser evaporation, followed by excellent wound healing and good functional result. Treatment can be performed under local anaesthesia on an outpatient basis. The recurrence rate is low compared with the recurrence rate after surgical excision. Therefore, CO2 laser evaporation is considered a reliable and effective treatment modality for leukoplakia of the lip.

In vivo photo-detection of chemically induced premalignant lesions and squamous cell carcinoma of the rat palatal mucosa.

Photo-detection using in vivo fluorescence was studied for different stages of chemically induced premalignant lesions and squamous cell carcinoma (SCC) of the Wistar rat palatal mucosa. It was found that the epithelial dysplasia (numerically expressed in the epithelial atypia index (EAI) of the rat palate, induced by repeated application of the carcinogen 4-nitroquinoline 1-oxide (4NQO), showed an increase approximately proportional to the duration of the application period. Photo-detection of the lesions using Photofrin-induced fluorescence was studied with dual-wavelength excitation and the subtraction of images, in an attempt to reduce the autofluorescence. The Photofrin dose was 2.5 mg kg-1. This was based on a dose-response study for normal tissue damage by photodynamic therapy (PDT) in this animal model, because the underlying rationale was to study photo-detection as a method of locating additional (early) malignancies in patients treated by PDT. Fluorescence intensities 24 and 48 h after injection of Photofrin were shown to increase with the duration of 4NQO application and with increasing EAI. For an EAI greater than 15, there was a statistically significant difference (p < 0.01) between the fluorescence signals obtained with and without the injection of Photofrin. Fluorescence signals of these lesions without the use of Photofrin (autofluorescence) also showed an increase with increasing stages of epithelial dysplasia of the rat palate. However, the fluorescence signals obtained with Photofrin were always higher than those of the autofluorescence. From this study, we conclude that photo-detection with Photofrin has potential in distinguishing chemically induced premalignant lesions and squamous cell carcinomas from the normal rat palatal mucosa. Photofrin (2.5 mg per kg of body weight) certainly adds to the sensitivity of photo-detection, but autofluorescence alone also has promising features for detecting premalignant and malignant lesions of the oral mucosa.

Peripheral ameloblastoma. A case report and review of the literature.

Peripheral ameloblastoma is a benign odontogenic tumor with the same histological characteristics as the centrally located ameloblastoma, but appearing in the gingiva and mucosa of the tooth-bearing area of the jaws. A review is presented of 53 cases: 45 being reported as peripheral ameloblastoma and 8 as basal cell carcinoma of the gingiva, including the case presented. Based on the review it is recommended to treat this lesion by local excision including a small margin of healthy tissue. Local recurrence is unlikely, unless incomplete removal is performed.

Comparison of epithelial dysplasia--the 4NQO rat palate model and human oral mucosa.

Epithelial dysplasia in the rat palatal mucosa was induced by application three times a week of the carcinogen 4-nitroquinoline 1-oxide (4NQO). With the Epithelial Atypia Index (EAI), the successive stages of 4NQO-induced epithelial dysplasia were compared with specimens of human oral epithelial dysplasia. It appeared that there was a close similarity between the histologic features of 4NQO-induced dysplasia in the rat palatal mucosa and human oral epithelial dysplasia. Thus, the 4NQO rat palate model seems to be appropriate to study and assess new treatment modalities of premalignant epithelial lesions of the oral mucosa in man.

Photofrin-mediated photodynamic therapy of chemically-induced premalignant lesions and squamous cell carcinoma of the palatal mucosa in rats.

Photodynamic therapy (PDT), an experimental cancer therapy, was studied in an animal model of chemically-induced epithelial dysplasia and squamous cell carcinoma. PDT was performed 24 hours after i.v. injection of 2.5 mg/kg bw Photofrin, and using 100 J/cm2 incident light at two activation wavelengths (514.5 nm or 625 nm). Two days after PDT, the majority of rats macroscopically showed a marked erythema of the entire palatal region. Microscopically all the rats showed oedema, haemorrhage, and necrosis of the epithelium of the intermolar area. The long-term results were not so favourable. No evidence of disease was found in 6 out of 20 rats in the 514.5 nm group and in 2 out of 20 rats in the 625 nm treated group. Epithelial dysplasia was found in 14 out of 20 rats in the 514.5 nm group, and in 18 out of 20 rats of the 625 nm treated group. Squamous cell carcinomas were found in 4 out of 20 rats treated with 514.5 nm and in 7 out of 20 rats in the 625 nm treated groups. Comparing both treatment wavelengths, better results were obtained in the 514.5 nm groups as this wavelength gave less normal tissue damage. Based on the results of this study the application of PDT for the treatment of field cancerization and squamous cell carcinoma of the oral cavity, is discussed.

Long-term functional outcome of mandibular reconstruction with stainless steel AO reconstruction plates.

Mandibular continuity defects are usually reconstructed with bone grafts. However, factors associated with the tumour and the patient can still be reasons to choose reconstruction plates. The aim of this study was to find out the results of mandibular reconstructions with stainless steel AO reconstruction plates after a long follow-up period. The records of 36 patients were reviewed for personal data and the history of disease, treatment and complications. Patients with failed reconstructions were compared with those in whom the procedure had been successful. Patients and surgeons gave their opinion on the functional and cosmetic results. The mean follow-up was 39 months (range 4-99); 4 patients were withdrawn because they developed early recurrent disease and in 17 patients the reconstruction failed. We found no significant differences between the successful and the failed group. Fourteen patients could be evaluated for functional outcome, 10 of whom were totally or satisfactorily rehabilitated. Therefore, stainless steel reconstruction plates can be used in patients when other options are inappropriate.

Efficacy of a synthetic polymer saliva substitute in reducing oral complaints of patients suffering from irradiation-induced xerostomia.

OBJECTIVE: A saliva substitute based on polyglycerylmethacrylate, lactoperoxidase, and glucose oxidase (Oral Balance) has been developed. The aim of this study was to evaluate the effect of Oral Balance on the dryness-related oral complaints in patients suffering from irradiation-induced xerostomia. METHOD AND MATERIALS: The efficacy of Oral Balance on the dryness-related complaints of 28 patients was assessed by means of self-administered questionnaires. Each patient completed an initial questionnaire about dryness-related symptoms and then was given the moistening gel. The patients were instructed to apply the gel as often as desired. After 2 weeks and 3 months, the patients were asked to complete a progress questionnaire. The severity of xerostomia was measured with a saliva absorption method. RESULTS: All patients suffered from moderate-to-severe xerostomia, the severity of which did not change during the experimental period. Three patients did not complete the study. In the other 25 patients, the application of Oral Balance tend to diminish the sensation of oral dryness and improve oral functioning. Statistically significant reduction of the dryness-related complaints was observed only in the patients suffering from severe xerostomia. CONCLUSION: Use of Oral Balance is of potential benefit in patients suffering from severe xerostomia.

[Photodynamic therapy of the oral mucosa]. / Fotodynamische therapie van het mondslijmvlies.

Photodynamic therapy (PDT) is a new therapeutic modality in head and neck oncology. PDT is based on the accumulation of a photosensitive dye in (pre)malignant tissue. When sensitizer containing tissue is exposed to light of a proper wavelength and dose, a photochemical reaction between the dye and the light will occur. The result may be tumornecrosis. Besides a tumor destructive effect, photosensitizers are also capable to show fluorescence, when stimulated by light of an appropriate wavelength. This fluorescence photo-detection (PD) can be used for early detection and localization of tumors or even premalignant epithelial changes, in tissues exposed to the delivered light. In this study several aspects of PDT and PD are described.

[Hypertrophy of the inferior labial frenum]. / Het hypertrofisch frenulum van de onderlip.

Hypertrophy of the inferior labial frenum, which is present in approximately 8% of the population, can give rise to prosthodontic or periodontal problems. In contrast to hypertrophy of the superior labial frenum, there is no relation to orthodontic problems. The indications for extirpation of a hypertrophic inferior labial frenum are discussed.

[Treatment of mouth cancer. General principles as well as surgical aspects]. / Behandeling van mondkanker. Algemene principes alsmede enkele chirurgische aspecten.

An overview is presented of the various treatment modalities in head and neck cancer, the emphasis being on oral cancer. Evaluation of the neck with regard to the possible presence of regional lymph node metastases is an integral part of the examination and treatment of patients with oral cancer. A strong plea is made for a multidisciplinary approach in the treatment and rehabilitation of this patient group.

[Prevention of oral cancer]. / Preventie van mondkanker.

Etiology control is the most important primary prevention of oral cancer. The use of tobacco and alcohol increases the risk of a squamous cell carcinoma of the oral mucosa. The dentist can play an important role in the secondary prevention or screening for premalignant lesions, asymptomatic malignancies and second primary tumours of the oral cavity. Because of their age, edentulous patients run a high risk of oral cancer. Therefore, a regular oral check-up of these patients should be recommended.

[Peripheral facial nerve palsy]. / Perifere nervus facialis-paralyse.

There are different etiological factors concerning the acute peripheral facial nerve palsy. In the majority of the cases, however, no etiological factor can be found. These cases are called idiopathic facial palsy or Bells palsy. Perhaps local anaesthetics could play a role as an etiological factor. By means of a case-report this form of facial nerve palsy will be discussed.

[Team approach in maxillofacial oncology]. / Teambehandeling bij maxillofaciale oncologie.

The most frequent malignant tumour in the head and neck region this area is the squamous cell carcinoma of the upper aerodigestive tract. In the Netherlands the incidence of these tumours is low, about 2000 new cases a year. Multidisciplinary treatment of these tumours is mandatory because of the extension of the lesion in the area of other disciplines. The variety of diagnostic and therapeutic possibilities and the supportive care ask for a multidisciplinary approach. The low incidence of head and neck cancer in the Netherlands and the complexity of the treatment of these tumours were the reason to concentrate the care for these patients in multi disciplinary head and neck cancer centres.

[Relations of human papillomavirus and lesions of the oral mucosa]. / Relatie humane papillomavirus en afwijkingen van het mondslijmvlies.

Recently there has been an increased interest in the possible role that viruses and especially the Human Papilloma virus (HPV) could play in the etiology of lesions of the oral mucosa. A distinction has to be made between the so-called low-risk types of the virus (HPV-2, 6, 11, 13 and 32) which can be found in benign oral mucosal lesions, and the high-risk type (HPV-16), which predominantly is found in malignant oral mucosal lesions.

[Lasers in dentistry 8. Use of lasers in oral and maxillofacial surgery]. / Lasers in de tandheelkunde 8. Het gebruik van lasers bij mondziekten en kaakchirurgie.

Since the 1970's lasers are used in oral and maxillofacial surgery. The effect of a laser on tissue is determined by the wavelength of the laserlight and the tissue specific absorbtion. Lasers are used for evaporation, excision and coagulation of tissue. The CO2-laser, the Nd:YAG-laser and the Argonlaser are used for these purposes. Light and laserlight are used for the diagnosis of mucosal lesions. By using different excitation wavelength autofluorescence of lesions can be detected and analysed. An artificial neural network can be used to analyse these data. Photodynamic Therapy (PDT) is a cancer therapy based on the more or less specific absorption of a drug in tumour, that can be activated with light of a specific wavelength. Activation of this drug causes tumour destruction due to the formation of oxyginradicals. PDT is limited by the penetration of the activating light and is therefore only suitable for the treatment of superficial tumours.