Comparison of two maxillary protraction protocols: tooth-borne versus bone-anchored protraction facemask treatment

Abstract

BackgroundProtraction facemask has been advocated for treatment of class III malocclusion with maxillary deficiency. Studies using tooth-borne rapid palatal expansion (RPE) appliance as anchorage have experienced side effects such as forward movement of the maxillary molars, excessive proclination of the maxillary incisors, and an increase in lower face height. A new Hybrid Hyrax bone-anchored RPE appliance claimed to minimize the side effects of maxillary expansion and protraction. A retrospective study was conducted to compare the skeletal and dentoalveolar changes in patients treated with these two protocols.MethodsTwenty class III patients (8 males, 12 females, mean age 9.8 ± 1.6 years) who were treated consecutively with the tooth-borne maxillary RPE and protraction device were compared with 20 class III patients (8 males, 12 females, mean age 9.6 ± 1.2 years) who were treated consecutively with the bone-anchored maxillary RPE and protraction appliances. Lateral cephalograms were taken at the start of treatment and at the end of maxillary protraction. A control group of class III patients with no treatment was included to subtract changes due to growth to obtain the true appliance effect. A custom cephalometric analysis based on measurements described by Bjork and Pancherz, McNamara, Tweed, and Steiner analyses was used to determine skeletal and dental changes. Data were analyzed using a one-way analysis of variance.ResultsSignificant differences between the two groups were found in 8 out of 29 cephalometric variables (p < .05). Subjects in the tooth-borne facemask group had more proclination of maxillary incisors (OLp-Is, Is-SNL), increase in overjet correction, and correction in molar relationship. Subjects in the bone-anchored facemask group had less downward movement of the “A” point, less opening of the mandibular plane (SNL-ML and FH-ML), and more vertical eruption of the maxillary incisors.ConclusionsThe Hybrid Hyrax bone-anchored RPE appliance minimized the side effect encounter by tooth-borne RPE appliance for maxillary expansion and protraction and may serve as an alternative treatment appliance for correcting class III patients with a hyperdivergent growth pattern.

Differential treatment effects of two anchorage systems for rapid maxillary expansion: a retrospective cephalometric study

“…Several clinical studies and case reports with different treatment protocols have combined this hybrid hyrax with facemasks for maxillary protraction in Class III patients [48,[54][55][56]69]. Some of these studies [54][55][56] demonstrated advancement of the maxillary complex by statistically significant amounts which, due to the extraoral forces from facemasks, were larger than reported in the present study.…”

Stress and displacement pattern evaluation using two different palatal expanders in unilateral cleft lip and palate: a three-dimensional finite element analysis

“…Recently, Ngan et al had reported that in non-cleft class III individuals, the hybrid HYRAX bone-borne expansion device along with maxillary protraction yielded desirable sagittal skeletal change with minimal dental side effects [41]. Also Lin et al had concluded that in non-cleft individuals bone-borne maxillary expansion produced greater transverse orthopedic effects [42].…”

Bone-anchored maxillary protraction in patients with unilateral complete cleft lip and palate and Class III malocclusion

“…Importantly, comparison of the long-term results of early FM therapy and BAMP, when available, will be very interesting. A number of treatment protocols using a maxillary expansion and protraction reported favorable short-term results in non-cleft subjects of 9-12 years old in terms of A point advancement [7,[25][26][27][28][29]. Most of the studies were retrospective, with relatively small sample size or without untreated controls.…”

“…Less dental compensations are demonstrated when a facemask used in combination with a Hybrid Hyrax, a rapid palatal expansion appliance which is both tooth-and bone-borne. [7]. Protocols of maxillary expansion and protraction, such as the Alternate Rapid maxillary Expansions and Constrictions protocol(Alt-RAMEC), proposed by Liou et al, showed favorable skeletal results up to 17 to 21 years of age in some patient, but with evident dental compensation [8,9].…”