**1. Introduction**

According to the World Health Organization, leucoplakia is defined as a "white patch that cannot be associated either clinically or histopathologically to other diseases" so the diagnosis is by exclusion.

Leucoplakia is the most common oral precancerous alteration and appears as a white, chronic lesion, that cannot be removed with rubbing. Leucoplakia is characterized by an abnormal keratinization of the mucosa. The prevalence in the general population ranges from 0.6% to 5% and is more frequent in those between 40 and 50 years old [1]. The cause is multifactorial and there

are several predisposing factors such as: mechanical irritation, dental materials causing galvanic currents, contact with carcinogens such as tobacco and alcohol and gastroesophageal reflux [2,3]. The predisposition to malignant transformation seems associated to a higher CD8+ cells levels in premalignant lesion [4].

The presumed diagnosis is based on the anamnesis and the clinical aspect, while the diagnosis can only be confirmed after both an incisional and excisional biopsy and its subsequent histological examination [5].

Some epidemiological studies have identified the occasional possibility of spontaneous regression of leucoplakias. However, in the vast majority of cases various surgical and non-surgical treatments are proposed such as elimination of the chronic irritative factors, surgical treatment with a scalpel, electrocautery, laser or cryosurgery; conservative treatment is to be considered only if the patient denies consent to surgery or if the areas have a low probability of malignant transformation [6–10].

Hyperkeratoses are benign lesions that usually appear in areas subjected to frictional trauma, for example in adherent gingiva under the prosthetic flanges, the retromolar trigon and the edge of the tongue, where the patient often tends to bite. During intraoral examination, hyperkeratosis tends to have a verruciform or corrugated appearance. Histological examination shows hyperkeratosis, acanthosis, hypergranulosis and inflammation of the stroma.

Although it is benign, some precancerous lesions such as leucoplakia can mimic the characteristics of the hyperkeratosis. The clinical appearance of the lesion can help clinicians in the differential diagnosis between leucoplakia and hyperkeratosis; in fact hyperkeratosis shows less definite margins than the first. Investigating the habits of the patient could be helpful [11,12]. Follow-ups must be on-going even if the histology does not manifest dysplasia, since hyperkeratosis could evolve towards a malignant transformation due to the reoccurrence of the trauma.

It has been many years since laser therapy has been introduced in dentistry and in particular in periodontal field where it succeeded in eliminating pathogenic bacterial niches in inaccessible areas, such as deep pockets, root concavities and furcation areas in a less- traumatic way [13]. One of the most effective laser therapy in decontaminating periodontal pockets and in giving improvement in CAL, PPD and BOP was the photodynamic therapy based on the use of three components: light, oxygen free radicals and photosensitizer [14–17].

Another option in the treatment of chronic periodontitis is the use of a desiccant agen<sup>t</sup> as an adjunct to scaling and root planing (SRP). This protocol resulted in a greater reduction in clinical, microbial and inflammatory mediators compared to SRP alone [18].

The aim of the study is to find a laser-assisted protocol for the surgical excision of leucoplakia and hyperkeratosis that can both improve the clinical aspect of the lesion and be sustainable for patients. The null hypothesis has been identified in the following statement: the treatment is effective and efficient at the same time; where effectiveness was tested with the following criteria: size of the lesion, tactile perception, discomfort and pain; and efficiency with the following criteria: pain and discomfort perceived during the treatment.
