## 4 Discussion  
To the authors' knowledge, the first study that evaluated radiomorphometric indices in orthopantomographies as well as fractal dimension performed in children with OI and compared to children with normal BMD was that by [PERSON] et al. in 2015 [25] and in 2016 [1]. However, over the years, multiple studies have addressed the correlation between adult BMD on panoramic radiographs [19; 20; 21; 28; 29; 30], postulating that this is a feasible screening tool for bone mass identification but requiring further investigation to include a child population with low BMD. The present study is comparable to the one performed by [PERSON] et al. in 2015 [25] and 2016 [1]. It uses similar methodology but is applied to a Spanish child population, with the aim of evaluating radiomorphometric indices and fractal dimension in children with OI to check for possible alterations in mandibular cortical in reference to treatment received with panidronate. One of the limitations of the present study is that it was retrospective in time, which conditioned data availability. The study groups and control group were balanced with respect to age and gender, ruling out any undesirable correlations that might influence the result. The researchers of the present study highlight that, in the research conducted by [PERSON] et al. in 2015 and 2016, the orthopantomographies of the patients with OI included in the study were taken at different times in the patient's life, during the panidronate cycle, and indicate possible bone alterations before and after treatment with more or fewer cycles in the radiographs. In general, the results of the present research show that the relationship between FD and MCW in the OI group is conducive to a relationship of mild intensity, in which the statistical evidence is insufficient, and less so in the control group. [PERSON] et al. in 2016 [1] point to the existence of a relationship between FD and MCW but not in all age groups (less significant in the group aged 11 to 14). Their explanation is that, in that age range, the patients had received more cycles of panidronate than at the beginning of the treatment. \begin{table}
\begin{tabular}{l c c c c c c} \hline \multirow{2}{*}{**Variable**} & \multirow{2}{*}{\begin{tabular}{c} **Total Sample** \\ **(n = 41)** \\ \end{tabular} } & \multicolumn{3}{c}{**Group**} & \multicolumn{2}{c}{**Contrast Test**} \\ \cline{3-8}  & & \(\leq\)**11 Years** & & \(\geq\)**12 Years** & **Value** & **\(p\)-Value** \\ \hline  & & **OI (n = 17)** & \
\begin{tabular}{c} **Control** \\ **(n = 10)** \\ \end{tabular} & **OI (n = 4)** &
\begin{tabular}{c} **Control** \\ **(n = 10)** \\ \end{tabular} & \\ \hline SVE & & & & & 9.95 & 0.002 \\ \hline Thin & 73.2\% (30) & 94.12\% (16) & 80\% (10) & 0\% & 60\% (6) & \\ Not thin & 26.8\% (11) & 5.88\% (1) & 20\% (2) & 100\%(4) & 40\% (4) & \\ \hline MCI & & & & & 8.67 & 0.013 \\ \hline C1 & 34.1\% (14) & 5.88\% (1) & 40\% (4) & 25\% (1) & 20\% (2) & \\ C2 & 43.9\% (18) & 52.94\% (9) & 60\% (6) & 25\% (1) & 80\% (8) & \\ C3 & 22.0\% (9) & 41.18\% (7) & 0\% & 50\% (2) & 0\% & \\ \hline FD–Cortical & & & & & & \\ Bone & 1.8831 (0.0488) & 1.8788 (0.0543) & 1.89152 (0.0363) & \(-0.76\) & 0.450 \\ \hline MCW & & & & & & \\ Median (SD) & 2.8911 (0.6076) & 2.7885 (0.5308) & 3.0889 (0.7130) & \(-1.53\) & 0.135 \\ \hline \end{tabular} SD: Standard deviation.  
\end{table} 
Table 6: Intergroup analysis. Differences in the radiological parameter variables, according to the age of the participants (n = 41). The statistically insufficient relationship between FD and MCW found in the results of the present study can be explained by the smaller size of study sample and the small amount of data on drug intake administered. However, with respect to MCW in relation to OI, a lower mean value was found in this group of subjects compared to the control group. This suggests a possible tendency for subjects with OI to generally present lower MCW values than children with normal BMD.