*3.1. Sample Characteristics*

20 patients were included in this study, of which 9 were affected by hyperkeratosis and 11 were affected by leucoplakia.

The sample consisted of 11 men (55%) with an average age of 55 years old and 9 women (45%) with an average age of 67 years old, the average age of the sample was of 61 years old. The site of onset of lesions in the oral cavity of the different patients was homogenous (Figure 1); the year of onset can be seen in Figure 2.

60% of patients had metals of dental origin such as gold; titanium or mercury derived from amalgam, 65% were carriers of both crowns and mobile prostheses and 45% of individuals had resin restorations on various elements. 35% of patients used alcoholic mouthwash, 25% had malocclusions in particular mono and bilateral cross-bite or third class and that 35% show detrimental habits, in particular episodes of morsicatio.

### *Int. J. Environ. Res. Public Health* **2019**, *16*, 210

**Figure 1.** Areas of lesions' presentation.

**Figure 2.** Year of onset of the lesions.

### *3.2. Analysis of the Lesion Size*

The variation of this parameter is evaluated consecutively with one-week intervals between one observation and the next. As the dimension at time T0 was considered as an independent variable and as the variable dependent was dimension at time T1, the coefficient of the regression of this analysis was 0.81. This meant that the lesion dimension between the two time intervals taken into consideration, reduced by an average of 19%. This same reasoning was applied to the independent and dependent variables respectively before T1 and T2, then T2 and T3 and finally T3 and T4. The coefficients of the regression analysis obtained are, in order, 0.39; 0.60; 0.80. The size between the different time intervals is reduced on average by 61%, 40% and 20% respectively. The P value was always inferior to 0.05% (Table 1).


