OBJECTIVE: The aim of the present pilot study was to evaluate the efficacy of the miniscrew-supported distal jet appliance versus traditional distal jet appliance in terms of amount of upper first molar distalization and the dentoalveolar side effects, obtained in six months.
MATERIAL AND METHODS: 20 patients were randomly assigned to receive a treatment with miniscrew-supported distal jet appliance (Group A) or with traditional distal jet appliance (Group B). To ensure a minimally invasive miniscrew insertion a computer-guided surgical guide was designed and subsequently manufactured using a 3D printer. Digital models and lateral cephalograms were obtained and analyzed before orthodontic treatment and at 6-month follow-up. The amount of upper first molar distalization and the dentoalveolar side effects were assessed both on digital models and on lateral cephalograms. In order to reduce the bias in the selection of subjects, considering that the sample size was too small to represent the entire spectrum of subjects in the target population, the results were analyzed at 6 months from the start of therapy. A descriptive statistical analysis was carried out. Intergroup differences were determined using T- test. The significance was set at P ≤0.05. The intra-operator reliability was calculated and a 2 sample T-test was used with significance estabilished at P ≤0.05.
RESULTS: In Group A, a greater maxillary first molar distalization was recorded in 6 months of follow-up with a statistically significant difference between the groups (P=0.002). Considering the dento-alveolar side effects, in Group A, a spontaneous distalization of the first premolars and a retroclination of central incisors were observed. In Group B, on the other hand, the first premolars tipped mesially (mesial drift) and a proclination of the maxillary central incisors (incisal flaring) was observed, causing a loss of anterior anchorage. The transverse widths of the dental arch increased in both groups, and a greater tendency of maxillary first molar rotation was observed in the group with traditional distal-jet appliance.
CONCLUSIONS: The present pilot study compared two maxillary molar distalization systems: the traditional distal jet appliance versus the miniscrew-supported distal jet appliance. The skeletal anchorage device achieved a greater first molar distalization at 6-month follow-up and did not cause dento-alveolar side effects, such as the mesial drift of the premolars and the incisors. Randomized controlled trials are needed to confirm these preliminary results.
CLINICAL IMPLICATION: Maxillary molar distalization is the most frequently used non-extraction treatment in the correction of Class II malocclusion. The use of traditional intra-oral devices shows unreliable results. Nowadays the use of miniscrew-supported appliances helps prevent anchorage loss. The present pilot study has provided results that, in the short follow-up, demonstrate a greater amount of maxillary molar distalization without the anchorage loss observed in traditional distal-jet appliances. These results should encourage the clinical use of supported-miniscrew orthodontic appliances but randomized controlled trials are needed to confirm these preliminary results.
Author: Tommaso Albonetti
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