Abstract
A comparative evaluation of low-level laser and CO 2 laser therapies was performed, for the treatment of oral lichen planus (OLP). In a randomized open clinical trial, 28 patients with 57 lesions were randomly assigned to two groups. One group received CO 2 laser therapy, the other received low-level laser therapy (LLLT) for 5 sessions every other day. Participants were examined before the treatment, after 2 weeks, and at 1, 2 and 3 months, to assess the changes in sign and symptom scores. Improvements in size of lesions, in pain and clinical response scores were achieved in both groups. After 3 months, clinical response showed 100% and 85% partial to complete improvement in LLLT and CO 2 laser surgery, respectively. This demonstrates a quick and pronounced beneficial effect in controlling symptoms related to OLP. Both methods may be effective in the treatment of OLP, and can be used as alternative therapy alongside standard treatment modalities. The present study showed that LLLT displayed better results than CO 2 laser therapy as alternative or additional therapy, but further investigations in comparison with standard treatment modalities with a prolonged follow-up period will be necessary to confirm the efficacy of laser therapy in the treatment of OLP.
Oral lichen planus (OLP) is a common, chronic, immunological mucocutanous disease that commonly involves the oral mucosa. This form is refractory to treatment. The most widely accepted treatment for OLP is topical corticosteroids that relieve the symptoms rather than cure the disease. The disadvantages of this treatment include candidiasis, thinning of the oral mucosa, patient compliance with the treatment, and discomfort during application. Alternative treatments include retinoid, cyclosporine, tacrolimus, and CO 2 laser surgery.
Therapeutic laser treatment can be applied in many fields of dental research. Examples of successful clinical application of laser are CO 2 laser surgery in the oral cavity. An advantage of laser therapy is the sealing of blood vessels which reduces haemorrhaging during the operation. Postoperative oedema is reduced as lymphatic vessels are sealed, and pain related to the lesion is reduced or eliminated as nerve supplies are sealed. Laser decreases the possibility of cicatrixial contractions. One of the most important benefits of laser therapy is great patient compliance. It promotes tissue healing and reduces oedema, inflammation, and pain. In low-level laser therapy (LLLT), the ability to non-thermally and non-destructively change cell function is known as laser biostimulation and is the basis for the use of lasers. The advantages of this method are anti-inflammatory effects, acceleration of wound healing, analgesic effects, vasodilatation and modulation of the immune system.
In a clinical trial of 25 patients with OLP treated using diode laser (980 nm), 12% had recurrence. In a prospective cohort study, Cafaro et al. managed 13 unresponsive patients with OLP resistant to standard therapy using LLLT. They reported significant reductions in size and pain with no side effect.
Regarding the chronic inflammatory nature of OLP, T-cell mediated auto-immune phenomena are thought to be involved in the pathogenesis of OLP. Therefore applying alternative methods such as LLLT, which aim to modulate inflammatory responses related to the disease, seems more reasonable and efficient than using methods such as CO 2 laser surgery which deal with the symptoms.
CO 2 laser surgery is still beneficial. It is thought that additional benefits can be achieved by simultaneously applying infra-red and red light in LLLT, to affect the surface and depth of the lesion. A method that is easier, less time consuming, and with a low recurrence rate might be more favourable than conventional therapies. The aim of this study was to compare the efficacy of LLLT with CO 2 laser surgery in the treatment of OLP.
Materials and methods
The ethics committee of Tehran University of Medical Sciences, Iran, approved the study protocol. Informed consent was obtained from all participants.
28 patients with OLP (21 females and 7 males) were selected from those referred to the Department of Oral Medicine, Faculty of Dentistry, Tehran University of Medical Sciences between March 2009 and September 2010. Inclusion criteria were a clinical and histopathological diagnosis of OLP based on ‘a modified definition of the World Health Organization (WHO)’. Using this modified definition, the patients were clinically diagnosed with lichen planus owing to the presence of bilateral lesions and the presence of reticular lesions elsewhere in the oral cavity, and histopathologically diagnosed by the presence of well defined band-like zones of inflammatory infiltration confined to the superficial part of the connective tissue, consisting mainly of mature lymphocytes and vacuolar alteration of the basal layer of the epithelium. Patients demonstrating histological signs of dysplasia, lichenoid drug reactions, drug consumption in the past month, pregnancy or any localized or systemic disease were eliminated or asked to discontinue their treatment for a minimum of 1 month before entering the investigation, as were patients receiving immunosuppressive or immune-modulatory treatments, or any systemic or local drugs. Patients with lesions adjacent to an amalgam filling were excluded from the study sample.
The patients were evaluated by an oral medicine specialist for demographics, medical history, presence of pain and discomfort, duration of disease, type, size, and scores of the lesions, and these data were recorded.
This clinical trial was a balanced block open study. The patients were randomly assigned to two groups by separate pockets on which were written the name of a laser. Each pocket was read by enrolling a new patient to the study and the type of laser was determined. One group ( n = 13 with 27 lesions) was given CO 2 laser irradiation surgery (Deka, Italy, 10,600 nm, 3 W). The applied dose was determined from the results of a pilot study on 7 patients. The laser operation was carried out on an outpatient basis under local anaesthesia. The oral mucosa lesions were removed superficially with a defocused laser at about 3 W, and evaporation was continued until the sub-mucosal connective tissue was reached. For postoperative care, diphenhydramin syrup and an analgesic such as a non-steroidal anti-inflammatory drug (NSAID) were prescribed for 2 weeks.
The second group ( n = 15 with 30 lesions) received LLLT using a diode laser (Mustang, Russia) with two probes, infra-red light (Ga–As, 890 nm, 0.3–0.5 J/cm 2 ) and red light (633 nm, CW, 0.3–0.5 J/cm 2 ). The selected dose was determined from a pilot study on 7 patients. Each patient received light exposure for 5 sessions every other day.
All participants, in both groups, were examined at baseline (before treatment), after 2 weeks and at 1, 2 and 3 months, to assess the effectiveness of treatment. During each appointment, the longest distance in centimetres from end to end of the reticular pattern, atrophic and erosive red area of the lesions was measured exactly with a scaled tongue blade, and digital photographs were taken.
Response rates were assessed clinically by three measures. First, a reduction in pain and discomfort (symptom). A visual analogue scale (VAS) was used to rank the severity of the patient’s symptom ranging from 0 (no pain) to 10 (extreme pain). Second, a reduction in the size of the lesions, determined by a scaled tongue blade. This was performed to compensate for the limitations of Thongprasom sign scoring, which determines only the measures of area ≥1 cm 2 or <1 cm 2 . Third, a reduction in clinical response (sign). This was assessed by Thongprasom sign scoring as follows: 5 (white striae with erosive area ≥1 cm 2 ), 4 (white striae with erosive area <1 cm 2 ), 3 (white striae with atrophic area ≥1 cm 2 ), 2 (white striae with atrophic area <1 cm 2 ), 1 (mild white striae only), and 0 (no lesions, normal mucosa).
Treatment outcomes were defined as changes in sign, symptom and size of the lesions between baseline and the last session. The symptomatic response, the clinical response and reduction of lesion size for each patient were calculated by subtracting each score from the initial score. Positive and negative values were considered as improvement and worsening, respectively.
Statistical analysis
The Mann–Whitney U -test was used for evaluation of clinical response scores and pain (VAS) changes compared to their baselines. The unpaired Student’s t -test was used for assessing the size reduction of the lesions. P values less than 0.05 were considered statistically significant.
Results
The study sample consisted of 28 patients suffering from OLP (7 males, 21 females) with a mean age of 50.7 years, and a total of 57 lesions. 30 lesions were treated with LLLT and 27 lesions were treated with CO 2 laser surgery. The LLLT group consisted of 4 males and 11 females, the CO 2 laser group consisted of 3 males and 10 females. The buccal mucosa was the most common site for OLP (48%), followed by the gingiva (33%) and tongue (19%).
There was no significant difference in the mean baseline lesion (before treatment) size between LLLT (mean ± SEM; 3.2 ± 0.2 cm) and CO 2 laser surgery (3.1 ± 0.2 cm). The unpaired Student’s t -test showed that the lesion size reduction was significantly higher in LLLT than CO 2 laser surgery in all the follow-up stages ( P < 0.05; Fig. 1 ).
The median (min, max) clinical response scores at baseline were 5 (2, 5) in both CO 2 laser surgery treated and LLLT patients. The clinical response (sign) improved during follow-up in both groups.
Approximately 85% of the CO 2 laser surgery group experienced partial to complete clinical improvement, but 15% had no response. In the LLLT group, 100% demonstrated partial to complete improvement ( Figs. 2 and 3 ). There was a significant difference in clinical response between the two groups. Improvements in clinical signs were significantly higher in the LLLT group in all follow-up stages ( P < 0.05; Table 1 ).
| Clinical response | Follow-up sessions | |||||||
|---|---|---|---|---|---|---|---|---|
| 2 weeks | 1 month | 2 months | 3 months | |||||
| CO 2 | LLLT | CO 2 | LLLT | CO 2 | LLLT | CO 2 | LLLT | |
| −2 (2 degrees worsening) (%) | 7 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 0 (no change) (%) | 63 | 14 | 26 | 0 | 15 | 0 | 15 | 0 |
| 1 (degree improvement) (%) | 4 | 0 | 4 | 0 | 4 | 0 | 4 | 0 |
| 2 (2 degree improvement) (%) | 15 | 55 | 41 | 50 | 44 | 46 | 41 | 35 |
| 3 (3 degree improvement) (%) | 11 | 14 | 11 | 27 | 19 | 27 | 18 | 31 |
| 4 (4 degree improvement) (%) | 0 | 17 | 15 | 15 | 15 | 15 | 22 | 19 |
| 5 (5 degree improvement) (%) | 0 | 0 | 3 | 8 | 3 | 12 | 0 | 15 |
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