Abstract
Abstract Introduction The aim of this study was to evaluate the short- and long-term effects of hybrid-Hyrax, Alt-RAMEC and applied, miniscrew reinforced, heavy intermaxillary elastics on a modified lingual arch in growing skeletal Class III patients. Methods Fifteen subjects (seven male, eight female) were included, with an average age of 12.52 ± 0.94 years, of cervical vertebrae maturation (CVM) stage CS2-CS4 and skeletal Class III malocclusions due to a retrognathic maxilla. Nine weeks of Alt-RAMEC were followed by eight to nine weeks of maxillary protraction with heavy 400 gm Class III elastics worn 24 h/day. Treatment was finalised with orthodontic fixed appliances. Cone beam computed tomographic (CBCT) scans were taken initially (T1), at the end of maxillary protraction (T2) and four years after active orthopaedic treatment (T3). Cephalometric measurements were performed on reconstructed lateral cephalograms and the differences between time intervals were calculated using an analysis of variance (ANOVA). Results A positive overjet was achieved in all but one subject. From T1 to T2, A point advanced 3.12 ± 3.42 mm and from T2 to T3 advanced a further 2.21 ± 3.49 mm. Significant initial increases in SNA of 1.05° ± 1.10° (p = 0.004), ANB of 2.71° ± 1.01° (p = 0.00), Wits of 4.49 ± 2.21 mm (p = 0.00) and overjet of 4.90 ± 1.66 mm (p = 0.00) were accomplished and maintained without significant changes in the vertical dimension. Upper and lower incisor inclinations were not affected by the protraction protocol but significantly increased (U1-PP: 8.39° ± 5.59°) between T2 and T3. SNB decreased initially by 1.67° ± 1.34° (p = 0.00) but relapsed due to residual mandibular growth and a counterclockwise rotation of the mandibular plane. Conclusion The hybrid-Hyrax Alt-RAMEC combined with miniscrew reinforced heavy Class III elastics resulted in a favourable and stable Class III correction.
Highlights
The aim of this study was to evaluate the short- and long-term effects of hybrid-Hyrax, Alt-RAMEC and applied, miniscrew reinforced, heavy intermaxillary elastics on a modified lingual arch in growing skeletal Class III patients
The root mean square error ranged between 0.13° (SNB) and 1.77° for the angular measurements and between 0.13 mm and 0.75 mm (VR-Pog) for the linear measurements
An analysis of the co-ordinate system showed a significant forward and downward movement of all included skeletal, dental and soft tissue points (p < 0.05). In this prospective clinical trial, the short-term and long-term effects of the hybrid-Hyrax appliance combined with the Alt-RAMEC protocol for nine weeks followed by eight to nine weeks of miniscrew reinforced bilateral 400 gm Class III elastics on a modified lingual arch were evaluated in Class III maxillary retrusive, growing subjects
Summary
The aim of this study was to evaluate the short- and long-term effects of hybrid-Hyrax, Alt-RAMEC and applied, miniscrew reinforced, heavy intermaxillary elastics on a modified lingual arch in growing skeletal Class III patients. Correlations between hard and soft tissue changes have shown that forward soft tissue movement was 50–79% of the corresponding maxillary hard tissue movement, while downward and backward movement of the soft tissues was 71–81% of the changes seen in the mandibular hard tissues.[6] Despite a skeletal contribution in the correction of the maxillomandibular discrepancy, FM treatment with or without RME has been related to individual variations in treatment response and a series of dentoalveolar side effects These include forward movement of the maxillary dentition, increased proclination of the maxillary incisors, retroclination of the mandibular incisors, a counterclockwise rotation of the maxilla and a clockwise rotation of the mandible.[7,8]
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