Comparazione di due tipi di vite da espansione del mascellare superiore. Studio clinico randomizzato multicentrico

Background and Rationale: The expansion of the maxilla is a very common clinical procedure to treat latero-posterior cross-bite and more generally the transverse maxillary deficiency in growing patients. Recently, several studies have shown that pain could be reduced by changing the amount of force exerted during palatal expansion. Objective of the study: The objective of this study is to evaluate the efficacy of an expansion screw of the maxilla that uses moderate and continuous forces compared to a screw for rapid standard expansion, which uses heavy and intermittent forces. In particular, in this thesis the subjective variables, including pain, were compared in patients with prepubertal stage. Methods: This is a superiority, two-centre, two arms parallel balanced randomization trial with a blinded examiner. Patients in the prepubertal stage were included with a discrepancy between the two arches of at least 3 mm, for which an expansion of the maxilla was indicated. An expansion screw using moderate continuous forces (test group, expansion screw with leaf Ni-Ti springs) was compared to a traditional rapid expansion screw that uses intermittent heavy forces (control group, expansion screw with telescopic guides). The primary response variable was the VAS mean on pain calculated in the first 12 weeks of therapy. The VAS scales on speech, oral hygiene, patient satisfaction and complications were also evaluated. Results: Twenty-eight patients in the test group and 28 patients in the control group were randomized and included in the study. There were no dropouts. The mean of the VAS for pain was 0.3 ± 0.4 in the test group and 0.6 ± 0.5 in the control group. The difference was -0.3 (95% CI from -0.5 to -0.0; P = 0.017) in favor of the test group. The difference in pain was marked in the first week (test group 2.2 ± 2.3; control group 3.7 ± 2.6; difference -1.5; 95% CI from -2.7 to -0.3; P = 0.019). The mean of the VAS for phonation was 0.6 ± 0.7 in the test group and 0.9 ± 0.9 in the control group. The difference was -0.3 (95% CI from -0.8 to 0.1; P = 0.132) in favor of the test group. The average of the VAS for the oral hygiene was 1.2 ± 1.3 in the test group and 1.1 ± 1.0 in the control group. The difference was 0.1 (95% CI from -0.5 to 0.7; P = 0.802) in favor of the control group. The average of the VAS for satisfaction was 8.7 ± 1.9 in the test group and 8.9 ± 1.5 in the control group. The difference was -0.1 (95% CI -1.1 to 0.9; P = 0.813) in favor of the control group. Four patients in test group and 8 patients in control group showed complications (OR = 0.42, 95% CI 0.11 to 1.59, P = 0.200). For many variables, there was a difference between the two centers. Conclusions: Patients in the test group experienced a lower degree of pain, especially in reference to the first week following the application of the expander. For the other variables no significant differences were reported between the two treatments. The study was registered in the ISRCTN register on 08/11/2016 with the number ISRCTN18263886.