The effectiveness of the basal expansion plate in comparison with the traditional expansion plate during the slow maxillary expansion: a randomized clinical trial

Although slow maxillary expansion is commonly used, numerous studies have demonstrated that the increase in dental arch width is primarily due to buccal tipping of the lateral teeth, often accompanied by recession of the vestibular alveolar process. This investigation addresses whether buccal shields inserted in a modified expansion plate can improve tooth movement, prevent vertical resorption of the alveolar process, and produce skeletal changes. For this purpose, frontal- and lateral cephalograms, along with cast models of 40 patients (17 males and 23 females; age: 10.28 ± 1.65) were studied. All patients were treated with slow maxillary expansion, and according to the plate used, patients were divided randomly into 2 groups:- 1^st group, 20 patients were treated with a modified plate, called the Basal Expanding Plate (BEP), and - 2^nd group, 20 patients were treated with a Traditional Expansion Plate (TEP). Measurements included the alveolar process height, inter-alveolar width, distance between the apex of the meso-buccal root of the upper first molar on two sides, and distance between the top of the meso-buccal cusp of the first upper molar bilaterally. were studied. Blinding was applied only for data analysis. The data obtained were subjected to statistical analyses using t-tests to detect significant group differences. The results revealed significant differences in basal width (BEP:2.62 ± 1.32, TEP:-1.87 ± 1.82), tooth root movement whereas it was buccal movement in BEP group (3.70 ± 2.40) and palatal movement in TEP group (-22.2 ± 3.63), and alveolar process dimensions between the two groups after treatment whereas it increased in BEP group in both sides (1.77 ± 1.65, 1.37 ± 1.22) while it decreased in TEP group in both sides too (-0.82 ± 0.81, -1.00 ± 0.84). Also, the difference was significant in S-N: Go-ME angle, whereas it decreased in the BEP group(-0.03 ± 3.02) and increased in the TEP group (0.40 ± 3.36). Based on the results, it can be concluded that the buccal shields of the basal expansion plate can improve the type of tooth movement, the inter-alveolar width and the height of the vestibular alveolar process during the maxillary dental arch expansion.Trial registration ISRCTN69542858 (27/11/2023).