## 2 Materials and Methods  
We retrospectively analyzed data from patients treated with distractors anchored to temporary orthodontic intraosseous implants between July 2019 and June 2022 at our clinic. Consent was obtained from the Bioethical Committee of the Regional Medical Chamber to conduct the research (decision no. OIL/KBL/49/2022). All patients treated with the orthodontic implants were included in the study in the first step, regardless of age and sex. To maintain the homogeneity of the study group, patients with the same type of implants (Dual-Top JS jet screw o 2.5-JS-012/014/016 mm) and the same distraction screw (Power Screw, Tiger Dental, Bregenz, Austria) were included in the next step of the study. None of the patients had a prior history of orthodontic treatment with fixed appliances or surgically assisted maxillary expansion. The exclusion criterion was a cleft lip or cleft palate. Patients were divided into an adolescent group (those below eighteen years of age) and an adult group (those eighteen and over). Application of the distractors proceeded as follows:  
1. Following cone beam computed tomography (CBCT) examination and analysis of the intended location of the mini-implant, the temporary orthodontic implant screws were inserted under local anesthesia. Dual-Top JS jet screw implants (Tiger Dental, Bregenz, Austria) with a diameter of 2.5 mm were used. Four implants were inserted in each patient: two mesially and two distally. Depending on the amount of bone available, implants of 12, 14, or 16 mm in length were inserted by the same operator (BWL). 2. After two weeks of the healing, an alginate impression with transfers caps was taken. A master cast was produced in the in-house laboratory from Class IV plaster with four laboratory analogues. The distractor size was chosen based on the clinical situation (the available screw body sizes were 8 mm, 10 mm, 12 mm, 14 mm, and 16 mm). We refer to the appliance as the PS4 Distractor, after the Power Screw (PS) and the number of implants on which it was placed. The master cast with the selected screw and four collars for adhesive bonding was sent to the laboratory. All distractors were made in the same laboratory (Ortolab, Czestochowa, Poland). 3. After a further three weeks, the distractor was cemented onto the implants using SDI Riva Self Cure HV Glass Ionomer (Melbourne, Australia) cement by the same operator (BWL). An example is presented in Figure 1. 4. The patient (or the patient with his or her parents) was instructed on how to deal with the distractor as follows: The screw should be turned twice daily, in the morning and the evening. Each screw has six surfaces, each of which should be counted when turning. Each surface is marked with one, two, or three black dots for visual saliency. A full turn of the screw would result in an expansion of 1 mm, whereas turning the screw by one sixth of a full rotation (one surface) would give an expansion of 0.17 mm. A Power Screw open-ended spanner is used to turn the screw, with the correct direction of rotation being from the upper to the lower incisors. The patient should open the mouth as widely as possible, placing the spanner on the hexagon of the screw body so that the handle is near the upper front teeth. The spanner should then be turned until it is positioned just before the lower teeth (on the tongue). The spanner should then be detached, turned 180\({}^{\circ}\) around the longitudinal axis, and placed back on the upper teeth; it should then be moved downwards again, as shown in Figure 2. 5. This usually results in rotation by one and a half surfaces. The same procedure should be repeated in the evening, resulting in a screw spread of 0.5 mm per day. The patient (and parents, where applicable) were informed that once the diastema appears, the turning should be decreased from two to one turns in the morning and one turn in the evening. The diastema should be considered to have appeared when a pin can move freely between the central incisors: this means that a gap of 1 mm has appeared. 5.