Study Design and Population

The study sample consisted of 17 retrognathic hyperdivergent patients who had previously received treatment at the graduate orthodontic clinic of Texas A&M University College of Dentistry. Both the original treatment study and the current follow-up assessing post-treatment stability were conducted prospectively. Inclusion criteria for all participants were: (1) bilateral Class II molar and canine relationships of end-on or greater, (2) an SNB angle at least one standard deviation below age- and sex-specific norms, (3) a lower anterior facial height (ANS-Me) exceeding age- and sex-specific averages, and (4) fully erupted premolars. This study was reviewed and approved by the Institutional Review Board of Texas A&M University College of Dentistry (IRB number 2014-0750-BCD-FP).

The same orthodontist treated each participant. The course of treatment has already been explained. With bands on maxillary first molars and occlusal stops for the erupting maxillary second molars, Dentaurum Variety SP (Dentaurum GmbH & Co. KG Ispringer, Germany) was the rapid palatal expander (RPE) that was utilized. Following maxillary expansion, two miniscrew implants (MSIs) were positioned lateral to the maxillary first molars in the posterior palate. They were then loaded with 150 g NiTi coil springs that were connected to the RPE. During the intrusive phase, the maxillary premolars and molars were treated with orthodontic brackets and segmental wires. To reduce incisor extrusion, no appliances were applied to the front six teeth. Buccal MSIs were positioned in the mandible between the first molars and second premolars, and they were secured to the mandibular orthodontic bracket for the first molar using stainless steel ligatures. Lower lingual arches were positioned to limit tilting, and 150 g coil springs were used to invade the lower molars of two patients who needed further mandibular rotation. The remaining dentition was bonded and the malocclusions were fixed after sufficient posterior intrusion had been obtained. A number of the patients needed to be extracted. After orthodontic treatment was finished, posttreatment (T2) records were acquired.

Mandibular-bonded 3-3 lingual retainers and maxillary full coverage thermoplastic retainers were given to all but two of the treated individuals. Thermoplastic retainers were employed by the two patients who refused mandibular-bonded ones. A 0.030-inch stainless steel wire that was fitted to the teeth, micro-etched, and bonded to the canines was used to create the lingual retainers. On the day of appliance removal, the maxillary retainers were lengthened to accommodate the second molars and thermoformed from Essix sheets to a thickness of 0.015 inches. After six months, patients were told to wear the retainers exclusively at night for the rest of their lives, with the exception of mealtimes.

Of the initial 17 participants, 14 were included in the current study (nine females and five men). Due to inadequate data or geographic displacement, three subjects could not be remembered. The sample's pretreatment age was 13.4 ± 0.7 years (T1), posttreatment age was 16.8 ± 1.3 years (T2), and recall age was 20.4 ± 0.9 years (T3). After around twenty-five months, the orthopedic phase came to a close. Posttreatment (T2-T3) lasted 3.6 ± 1.6 years, whereas treatment (T1-T2) lasted 3.5 ± 0.9 years. Since majority recurrence happen 12 months or more after active orthodontics, posttreatment data were obtained at that time.

Summary

• Study involved 17 retrognathic hyperdivergent patients from Texas A&M University College of Dentistry.
• Participants met specific inclusion criteria related to dental relationships, SNB angle, facial height, and erupted premolars.
• Treatment was conducted prospectively, approved by IRB (number 2014-0750-BCD-FP).
• All patients treated by the same orthodontist using Dentaurum Variety SP rapid palatal expander (RPE).
• After maxillary expansion, miniscrew implants (MSIs) loaded with NiTi coil springs were placed for further treatment.
• • Orthodontic treatment included brackets and segmental wires, with measures taken to prevent incisor extrusion.
• Mandibular-bonded and thermoplastic retainers provided post-treatment; night-time wear recommended indefinitely.
• From 17 participants initially, 14 were included in the study, with a mean age at pretreatment of 13.4 years.
• Posttreatment data collected after 3.6 years of follow-up to assess stability of results.