## 4 Results  
The distributions of clinical variables in the study groups are presented in Table 2.  
Palatal suture opening, confirmed by opening a diastena between the upper central incisors and being visible on intraoral radiographs, was successful in 69 patients (72.6% of total group of patients), including 36 growing patients (81.82% of adolescents) and 33 adults (66.67% of adult patients), as presented in Figure 2a,b. The difference in diastena occurrence between the adolescent group and the adult group was statistically insignificant \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Characteristic**} & \multirow{2}{*}{**Overall Cohort (N = 95)**} & \multicolumn{4}{c}{**Age Group**} \\ \cline{3-5}  & & **Adolescents** & **Adults** & **\(p^{\,\epsilon}\)** \\  & & \(n_{1}\) = 44 \({}^{a}\)** & \(n_{2}\) = 51 \({}^{a}\)** & \\ \hline
**Skeletal stage**: Mdn (Q1, Q3) \({}^{b}\) & 6.00 (4.00, 6.00) & 4.00 (3.00, 5.00) & 6.00 (6.00, 6.00) & **\textless{0.001 }\({}^{d}\)** \\ \hline
**Diastema occurrence** & 69 (72.63\%) & 36 (81.82\%) & 33 (64.71\%) & 0.062 \\ \hline
**Level of pain on NRS during the SRME activation:** Mdn (Q1, Q3) \({}^{b}\) & 4.00 (2.50, 6.00) & 5.00 (4.00, 7.00) & 3.00 (2.00, 5.50) & **0.009 \({}^{d}\)** \\ \hline
**Main disadvantage reported:** & & & & \\ pain & 18 (18.95\%) & 12 (27.27\%) & 6 (11.76\%) & 0.054 \\ pressure sores & 14 (14.74\%) & 7 (15.91\%) & 7 (13.73\%) & 0.765 \\
**speech difficulties** & **48 (50.53\%)** & **20 (45.45\%)** & **28 (54.90\%)** & **0.358** \\ headache & 2 (2.11\%) & 0 (0.00\%) & 2 (3.92\%) & 0.497 \({}^{e}\) \\ other aliments & 12 (12.63\%) & 4 (9.09\%) & 8 (15.69\%) & 0.335 \({}^{e}\) \\ no ailments & 2 (2.11\%) & 1 (2.27\%) & 1 (1.96\%) & 1.000 \({}^{e}\) \\ \hline
**Level of pain on the NRS during fixed** & & & & \\
**appliance therapy**: Mdn (Q1, Q3) \({}^{b}\) & 4.00 (2.00, 6.00) & 4.50 (3.00, 6.00) & 4.00 (2.00, 6.00) & 0.493 \({}^{d}\) \\ \hline pain & 19 (20.00\%) & 12 (27.27\%) & 7 (13.73\%) & 0.100 \\
**pressure sores** & **31 (32.63\%)** & **13 (29.55\%)** & **18 (35.29\%)** & **0.551** \\ speech difficulties & 2 (2.11\%) & 1 (2.27\%) & 1 (1.96\%) & 1.000 \({}^{e}\) \\ eating difficulties & 5 (5.26\%) & 1 (2.27\%) & 4 (7.84\%) & 0.369 \({}^{e}\) \\ other aliments & 19 (20.00\%) & 8 (18.18\%) & 11 (21.57\%) & 0.681 \\ no ailments & 20 (21.05\%) & 10 (22.73\%) & 10 (19.61\%) & 0.710 \\ \hline \hline \end{tabular}  
* _Note:_ _N_--cohort size; _n_--group size; _Mdn_--median; _Q1_--first quartile (25%); _Q3_--third quartile (75%); _p_--p_-value of statistical test. \({}^{a}\)_n_ (%); \(B\) _Mdn_ (Q1, Q3); \({}^{c}\) [PERSON]’s chi-square test; \({}^{d}\)_Mann-Whitney U test. \({}^{e}\) [PERSON]’s exact test.  
\end{table} 
Table 2: Comparative analysis of clinical parameters and adverse effects associated with the use of Haas-type expanders and fixed orthodontic appliances for overall cohort and stratified by age groups. (\(p\) = 0.062). The youngest patients without a diastema were an 11y-11 mo-old girl and a 13y-2 mo-old boy. The oldest male patient with a diastema was a 36y-2 mo-old Class III male whose orthopedic nonsurgical treatment with an SRME Haas-type acrylic bonded expander, face mask and fixed appliance was associated with marked changes, both on the dental and skeletal level, as seen in Figure 5, whereas the oldest female patient was a 41y-11m-old Class III woman. No statistically significant differences referred to pain or discomfort were found between patients with and without diastema, neither in the whole study group nor in the age subgroups. The average pain level reported on the NRS in the whole group of patients during SRME screw activation and FA therapy was equal (4.00). A statistically significant difference (\(p\) = 0.009) was apparent in pain levels during the SRME screw activation of the Haas-type appliance between adolescent patients, who reported a significantly higher median pain level (5.00), compared to adults (3.00) (Figure 6a).