Post-pubertal effects of the Alt-RAMEC/FM and RME/FM protocols for the early treatment of Class III malocclusion: a retrospective controlled study

Summary

Objective

To assess the stability of the effects of the modified Alt-RAMEC and facial mask (FM) protocol at a post-pubertal observation.

Methods

Twenty-one Class III patients (11 males and 10 females, 6.5 ± 0.7 years) treated consecutively with the Alt-RAMEC/FM approach and presenting with lateral cephalograms taken before treatment (T1), after treatment (T2), and at post-pubertal observations (T3) were compared with 22 Class III patients (9 males and 13 females, 6.9 ± 1.2 years) treated with the rapid maxillary expansion (RME) and FM protocol and with 15 Class III untreated subjects (7 males and 8 females, 6.2 ± 2.2 years). At T3, all patients showed a post-pubertal skeletal maturation stage (CS4–CS6). Descriptive statistics and statistical comparisons between the three groups at T1 and for the T3–T1, T2–T1, and T3–T2 changes were assessed by means of the ANOVA or Kruskal–Wallis test.

Results

During the overall observation period, Alt-RAMEC/FM and RME/FM protocols produced statistically significant favourable effects when compared with the Control group (ANB + 2.8° and +2.2°, respectively; Wits appraisal +4.4 mm and +2.7 mm, respectively). No statistically significant differences were found between the outcomes of the Alt-RAMEC/FM and RME/FM protocols neither at the post-pubertal or short-term observations.

Limitations

Retrospective study and the comparison with an historical control sample of subjects with untreated Class III malocclusion.

Conclusions

The Alt-RAMEC/FM protocol cannot be recommended as the approach of choice for the therapy of Class III dentoskeletal disharmony in very young subjects compared to the conventional RME/FM protocol.

Introduction

The Alternate Rapid Maxillary Expansion and Constriction (Alt-RAMEC) protocol was introduced by Erik Liou in 2005 with the aim of disarticulating more extensively the circum-maxillary sutures and enhancing the effects of maxillary protraction in cleft patients (1). Since the first years after its introduction, the Alt-RAMEC protocol has been adopted within the orthopedic treatment of Class III dentoskeletal disharmony in association, in most of the cases, with the facial mask (FM) (2–4).

Several studies evaluated the effects of the Alt-RAMEC/FM protocol with respect to the conventional orthopedic therapy for Class III dentoskeletal disharmony, represented by Rapid Maxillary Expansion (RME) and FM, with inconsistent results (2–4).

Liu et al. (5) in a randomized controlled trial analysed the effects of a 7 weeks Alt-RAMEC/FM protocol versus the conventional RME/FM protocol in a 7 to 13-year-old Chinese Class III patients sample. The authors found that the Alt-RAMEC/FM group showed a statistically significant greater maxillary advancement (SNA 2.7°, A-VRL 3.04 mm, and A-NP 2.48 mm) with respect to the RME/FM group (SNA 1.9°, A-VRL 2.11 mm, and A-NP 1.78 mm). Nevertheless, the authors stated that the difference between the two groups in terms of amount of maxillary protraction could not be considered clinically significant.

A 3D study, that evaluated the effects of a 6 week Alt-RAMEC/FM protocol with respect to the RME/FM protocol, examined the pre-treatment and post-treatment cone beam computed tomographies (CBCTs) of thirty-four 6-year-old Caucasian Class III patients (6). The authors reported that there was no statistically significant difference between the Alt-RAMEC/FM group (ANS AP 2 mm) and the RME/FM group (ANS AP 2 mm) in terms of maxillary advancement. Otherwise, a very recent study that investigated the outcomes of the Alt-RAMEC/FM therapy versus the outcomes of RME/FM and the FM alone approaches in a sample of 9.5-year-old Class III patients (7), found a statistically significant greater amount of maxillary protraction in the Alt-RAMEC/FM group (SNA Alt-RAMEC/FM versus RME/FM 0.88° and SNA Alt-RAMEC/FM versus FM 1.76°).

In the last years, two systematic reviews and meta-analysis were carried out in order to assess the effectiveness of the orthopedic treatment with the Alt-RAMEC protocol for the correction of Class III dentoskeletal malocclusion (8, 9). Both groups of investigators reported a greater amount of protraction of the maxilla obtained with the Alt-RAMEC/FM protocol with respect to the RME/FM protocol. However, they concluded that high-quality, long-term follow-up studies were needed to confirm the effectiveness and efficiency of the Alt-RAMEC protocol for the correction of Class III dentoskeletal disharmony in growing patients.

On the other hand, one of the most problematic issues regarding the early orthopedic therapy of dentoskeletal Class III disharmony is the long-term stability of treatment outcomes. The literature reports some relapse over the long term of the effects of the early RME/FM protocol (10, 11) due to the unfavourable growth pattern that characterizes subjects presenting with Class III malocclusion (12, 13).

A recent study (14) analysed the medium term effects of the modified Alt-RAMEC/FM therapy (15) with respect to the effects of the RME/FM protocol in a sample of 6-year-old Class III Caucasian patients. The authors did not find any statistically significant difference between the two treatment approaches. However, in this study, the treatment outcomes were not evaluated with respect to the growth changes that occur in untreated subjects with dentoskeletal Class III disharmony.

Therefore, the aim of the present retrospective study was to evaluate the stability at a post-pubertal observation of the effects of the modified Alt-RAMEC/FM approach by means of a comparison with the effects of the conventional RME/FM therapy and with the growth modifications in an untreated Class III sample.

Subjects and methods

The present study obtained the ethical approval (05/2020) from the Pediatric Ethics Committee of the Region of Tuscany, Italy, and informed consent was obtained from each patient family before treatment. In order to detect a clinically relevant difference in Wits appraisal of 2.5 mm, with a standard deviation of 2.3 mm (4), an alpha of 0.05 and a power of 80%, a minimum sample size of 15 patients in each group was required (SigmaStat 4.0, Systat Software Inc., San José, CA, USA).

Twenty-one patients (11 males and 10 females) with Class III dentoskeletal malocclusion and consecutively treated at the Orthodontic Clinic of the University Hospital of Careggi in Florence, Italy with the modified Alt-RAMEC and facial mask protocol (Alt-RAMEC/FM group) (15) during a prepubertal stage of skeletal maturation (CS1-CS2) (16) were included in the study. All patients presented with a lateral cephalogram before treatment (T1, mean age 6.5 ± 0.7 years), and they were re-evaluated with lateral cephalograms after the end of active phase of orthopedic treatment (T2, mean age 8.3 ± 0.8 years) and in the medium term, about 7 years after the end of active phase of treatment with the Alt-RAMEC/FM protocol (T3, mean age 15.2 ± 1.1 years), when they showed a post-pubertal stage of skeletal maturation (CS4-CS6) (16).

The Alt-RAMEC/FM group was compared with a sample of 22 patients (9 males and 13 females) with Class III dentoskeletal malocclusion treated consecutively at the Orthodontic Clinic of the University Hospital of Careggi in Florence, Italy with the conventional RME/FM protocol (RME/FM group). The RME/FM group presented with lateral cephalograms taken at the same observation time points T1 (mean age 6.9 ± 1.2 years, prepubertal stage of skeletal maturation CS1-CS2), T2 (mean age 8.5 ± 1.2 years), and T3 (mean age 15.3 ± 1.2 years, post-pubertal stage of skeletal maturation CS4-CS6), as the Alt-RAMEC/FM group.

All treated patients had to present with the following dentoskeletal features before therapy (T1), when the pretreatment lateral cephalogram was taken, to be included in the study:

1. European ancestry (white);

2. anterior crossbite or edge-to-edge incisor relationship;

3. Class III molar relationship;

4. Wits appraisal (17) of minus 2.0 mm or less;

5. absence of CO-CR discrepancy (indicating pseudo-Class III malocclusion);

6. deciduous or early mixed dentition and

7. prepubertal skeletal maturation (CS1 to CS2) (16).

Both treated groups were compared with a sample of 15 Caucasian subjects (7 males and 8 females) with untreated Class III malocclusion (Control group). Some subjects were enrolled previously in estimates of craniofacial growth in Class III malocclusion (13) while others were derived from the American Association of Orthodontists Foundation (AAOF) Craniofacial Growth Legacy Collection Project (www.aaoflegacycollection.org). Lateral cephalograms at mean ages of 6.2 ± 2.2 years (T1, prepubertal stage of skeletal maturation CS1–CS2), 8.4 ± 1.3 years (T2), and 15.9 ± 1.7 years (T3, post-pubertal stage of skeletal maturation CS4–CS6) were available for the Control group.

Alt-RAMEC/FM protocol

All patients received a maxillary acrylic-splint expander with soldered hooks for the facial mask. The expander was bonded to the deciduous canines and the first and second deciduous molars (18). Patients’ parents were instructed to activate the expansion screw (Leone A2620, Leone Orthodontic Products, Sesto Fiorentino, Firenze, Italy) twice a day (0.20 mm per turn) for 1 week, and then they were instructed to deactivate it twice a day for 1 week. This alternating protocol was repeated twice. After the 4 weeks sequence of Alt-RAMEC therapy, an additional maxillary expansion by means of a twice-daily activation of the expansion screw was performed until the desired maxillary transverse width was achieved. At the end of the expansion phase, a facial mask according to the design of Petit (Dynamic Face Mask, Leone Orthodontic Products, Sesto Fiorentino, Firenze, Italy) was delivered for maxillary protraction. The extraoral elastics produced orthopedic forces of as much as 400–500 g per side and they are attached from the hooks on the maxillary expander to the support bar of the facial mask in a downward and forward direction (at least 30 degrees to the occlusal plane) (19). The patients were instructed to wear the facial mask 14 hours per day for 6 months and then at night only for another 6 months. All patients had to show a positive dental overjet before discontinuing treatment and most of them were overcorrected toward a Class II occlusal relationship. Average duration of Alt-RAMEC/FM treatment was 1.1 ± 0.1 years. After the active therapy with the facial mask, a removable mandibular retractor was worn as retention appliance for at least 1 year by all patients (20). Between the end of the retention period and the post-pubertal observation (T3), three patients underwent a second phase of facial mask treatment and 11 patients underwent a multibrackets therapy.

RME/FM protocol

The acrylic splint expander was delivered to all patients, and it was bonded on the deciduous canines and the first and second deciduous molars. It included the permanent first molars, when they were already erupted in the maxillary arch. The expansion screw (Leone A2620, Leone Orthodontic Products, Sesto Fiorentino, Firenze, Italy) was activated by patients’ parents 1–2 times per day until the desired maxillary transverse width was achieved. Immediately after the end of the expansion phase, the patients began to wear the facial mask. The clinical management of the facial mask therapy was similar to the Alt-RAMEC/FM group. All patients were treated at least to a positive dental overjet before discontinuing treatment and most of them were overcorrected toward a Class II occlusal relationship. Average duration of RME/FM treatment was 1.1 ± 0.2 years. All patients wore a removable mandibular retractor during at least 1 year after the end of orthopedic treatment with facial mask (20). Six patients underwent a second phase of facial mask treatment and 12 patients underwent a multibrackets therapy before the post-pubertal observation (T3).

As it occurs in studies involving any removable device, compliance with the instructions of the orthodontist and staff varied among patients. Therefore, the clinician checked and recorded the degree of compliance at each appointment (every 5 weeks). The compliance was appraised by a means of a 3-point Likert scale (poor, moderate, good) (21). Poor compliance was reported if the facial mask was not worn during the day and not regularly at night, moderate compliance when the facial mask was worn regularly only at night, and good compliance when the facial mask was worn 14 hours per day (at night and 3 hours in the afternoon) for the first 6 months and then at night only for another 6 months.

Cephalometric analysis

A customized digitization regimen and analysis provided by Viewbox 4.0. (dHAL Software, Kifissia, Greece) was utilized for the cephalograms that were examined in the present study. The cephalometric analysis contains measurements from the analyses of Jacobson (17), McNamara (22), and Steiner (23). Eleven variables, 7 angular and 4 linear, were evaluated for each tracing. Magnification was standardized to a 0% enlargement (life size) for all radiographs in the three samples.

Statistical analysis

The Fisher exact test was used to assess differences in gender distribution and in the degree of compliance distribution between groups. Descriptive statistics and statistical comparisons between the Alt-RAMEC/FM group, the RME/FM group, and the Control group at T1 (Starting forms) and for the T3–T1, T2–T1, and T3–T2 changes was assessed by means of the ANOVA with Tukey’s post hoc test for the normally distributed variables or by means of the Kruskal–Wallis with Dunn’s post-hoc test for the non-normally distributed variables.

Method error

Twenty lateral cephalograms, selected randomly, were traced and measured at 2 times within a week by the same operator (CM). The measurements at both times for each patient were analysed with the intraclass correlation coefficient (ICC) for the assessment of the intraobserver repeatibility and with the method of moments’estimator (MME) for the assessment of the random error (24).

Results

As for the ICC an excellent intra-rater agreement was found with the values varying between 0.837 for the Wits appraisal and 0.994 for SNB. The measurements for the MME ranged from a minimum of 0.4 for SNB and molar relationship to a maximum of 1.3 for CoGo.

As for gender distribution, no statistically significant difference was found between the three groups (Fisher exact probability test, P = 0.756).

Appraisal of compliance

The two treated groups showed a similar distribution of ‘poor’, ‘moderate’, and ‘good’ degree of cooperation during the orthopedic therapy (i.e., use of the facial mask). As for the Alt-RAMEC/FM group a ‘good’ degree of collaboration was found for 12 patients, a ‘moderate’ degree of collaboration for 6 patients, and a ‘poor’ degree of collaboration for 3 patients. The RME/FM group presented with 16 patients with ‘good’ degree of collaboration, 4 patients with ‘moderate’ degree of collaboration, and 2 patients with ‘poor’ degree of collaboration. No significant difference was found in the prevalence rates of degree of collaboration between the two groups (Fisher exact probability test, P = 0.585).

Descriptive statistics and statistical comparisons between the three groups at T1 (starting forms) are reported in Table 1. No statistically significant difference was found neither for age at T1 nor for the baseline characteristics.

Table 1.

Descriptive statistics and statistical comparisons (ANOVA with Tukey’s post hoc test or Kruskal–Wallis with Dunn’s post-hoc test) for the starting forms (baseline characteristics at T1)

	AltRAMEC/FM (1) N = 21		RME/FM (2) N = 22		Controls (3) N = 15
Variables	Mean	SD	Mean	SD	Mean	SD	Diff. 1–2	Diff. 1–3	Diff. 2–3	P
Age (yr)	6.5	0.7	6.9	1.2	6.2	2.2	−0.4	0.3	0.7	0.350
SNA (deg)	80.6	3.8	80.2	4.2	80.0	4.0	0.4	0.6	0.2	0.916
SNB (deg)	79.3	3.6	79.0	3.8	78.3	3.0	0.3	1.0	0.7	0.711
ANB (deg)	1.2	1.9	1.2	1.8	1.7	2.2	0.0	−0.5	−0.5	0.750
Wits (mm)	−4.4	1.8	−3.9	1.6	−5.6	2.8	−0.5	1.2	1.7	0.051
SN-Pal. Pl. (deg)	7.9	3.2	8.7	3.8	9.3	2.5	−0.8	−1.4	−0.6	0.457
SN-Mand. Pl. (deg)	34.6	4.8	33.8	5.0	37.2	2.5	0.8	−2.6	−3.4	0.077
Pal. Pl.–Mand. Pl. (deg)	26.7	3.9	25.1	4.9	27.9	2.8	1.6	−1.2	−2.8	0.130
CoGn (mm)	92.8	6.8	89.2	5.6	93.5	6.8	3.6	−0.7	−4.3	0.083
CoGo (mm)	42.1	4.2	41.3	3.0	42.8	3.2	0.8	−0.7	−1.5	0.454
CoGoMe (deg)	129.2	3.0	128.7	4.8	129.0	4.1	0.5	0.2	−0.3	0.910
Mol. Rel. (mm)	2.8	1.2	2.6	1.3	3.7	1.7	0.2	−0.9	−1.1	0.062

Pal.: Palatal; Pl.: Plane; Mand.: Mandibular; Mol.: Molar; Rel.: Relationship; Diff.: Difference; deg (degrees).

Overall changes (T3–T1 changes)

Table 2 reports the descriptive statistics and statistically comparisons between the three groups for the T3–T1 changes. During the overall observation period, both Alt-RAMEC/FM and RME/FM protocols showed statistically significant favourable effects with respect to the untreated Control group in terms of correction of sagittal skeletal intermaxillary relationships (ANB Alt-RAMEC/FM group versus Control group +2.8° and ANB RME/FM group versus Control group +2.2°; Wits appraisal Alt-RAMEC/FM group versus Control group +4.4 mm; and Wits RME/FM group versus Control group +2.7 mm). The Alt-RAMEC/FM group achieved a statistically significant improvement of the molar relationship with respect to the Control group (Mol. Rel. Alt-RAMEC/FM group versus Control group −2.1 mm).

Table 2.

Descriptive statistics and statistical comparisons (ANOVA with Tukey’s post hoc test or Kruskal–Wallis with Dunn’s post-hoc test) for the T3–T1 changes

	Alt-RAMEC/FM (1) N = 21		RME/FM (2) N = 22		Controls (3) N = 15
Variables	Mean	SD	Mean	SD	Mean	SD	Diff. 1–2	Diff. 1–3	Diff. 2–3	P
Age (yr)	8.6	1.1	8.4	1.7	9.7	3.2	0.2	−1.1	−1.3	0.152
SNA (deg)	2.0	2.0	1.9	2.2	0.9	2.5	0.1	1.1	1.0	0.301
SNB (deg)	1.0	2.7	1.5	2.9	2.8	3.2	−0.5	−1.8	−1.3	0.199
ANB (deg)	1.0	2.0	0.4	2.5	−1.8	2.1	0.6	2.8**	2.2*	0.001
Wits (mm)	1.6	3.5	−0.1	2.9	−2.8	3.6	1.7	4.4***	2.7*	0.001
SN-Pal. Pl. (deg)	0.1	2.4	−0.2	2.1	0.5	2.4	0.3	−0.4	−0.7	0.669
SN-Mand. Pl. (deg)	−2.2	3.5	−1.2	3.4	−2.1	4.3	−1.0	−0.1	0.9	0.526
Pal. Pl.–Mand. Pl. (deg)	−2.3	3.7	−1.0	3.1	−2.5	4.1	−1.3	0.2	1.5	0.364
CoGn (mm)	21.9	6.8	24.0	8.4	22.9	6.5	−2.1	−1.0	1.1	0.654
CoGo (mm)	12.5	4.9	13.2	4.9	13.0	4.7	−0.7	−0.5	0.2	0.907
CoGoMe (deg)	−3.5	3.4	−3.6	2.6	−3.1	4.1	0.1	−0.4	−0.5	0.885
Mol. Rel. (mm)	−0.6	1.6	0.0	1.8	1.5	2.2	−0.6	−2.1**	−1.5	0.005

Pal.: Palatal; Pl.: Plane; Mand.: Mandibular; Mol.: Molar; Rel.: Relationship; Diff.: Difference; deg (degrees).

Bold values in the P column indicate statistical significance.

*P < 0.05; **P < 0.01; ***P < 0.001.

As for the comparison between the two treated groups at the post-pubertal observation, no statistically significant differences were observed for any of the cephalometric variables.

Short-term changes (T2–T1 changes)

The descriptive statistics and the statistical comparisons between the three groups for the T2–T1 short-term changes are reported in Table 3.

Table 3.

Descriptive statistics and statistical comparisons (ANOVA with Tukey’s post hoc test or Kruskal–Wallis with Dunn’s post-hoc test) for the T2–T1 changes

	Alt-RAMEC/FM (1) N = 21		RME/FM (2) N = 22		Controls (3) N = 15
Variables	Mean	SD	Mean	SD	Mean	SD	Diff. 1–2	Diff. 1–3	Diff. 2–3	P
Age (yr)	1.8	0.4	1.6	0.5	2.2	2.0	0.2	−0.4	−0.6	0.241
SNA (deg)	2.2	1.5	1.6	1.4	0.1	1.4	0.6	2.1***	1.5*	0.000
SNB (deg)	−1.3	1.8	−1.2	1.5	0.3	1.6	−0.1	−1.6*	−1.5*	0.008
ANB (deg)	3.6	2.2	2.8	1.9	−0.1	1.5	0.8	3.7***	2.9***	0.000
Wits (mm)	1.7	3.1	0.4	1.4	−0.7	2.8	1.3	2.4*	1.1	0.008
SN-Pal. Pl. (deg)	−0.2	1.6	−0.8	1.6	−0.2	1.5	0.6	0.0	−0.6	0.420
SN-Mand. Pl. (deg)	1.5	2.1	1.3	1.6	−0.1	1.7	0.2	1.6*	1.4	0.030
Pal. Pl. – Mand. Pl. (deg)	1.7	2.5	2.1	2.2	0.1	2.1	−0.4	1.6	2.0*	0.037
CoGn (mm)	3.3	2.8	4.5	2.7	5.9	3.0	−1.2	−2.6*	−1.4	0.034
CoGo (mm)	2.1	1.9	2.6	1.7	3.4	2.0	−0.5	−1.3	−0.8	0.166
CoGoMe (deg)	−1.6	2.4	−1.0	2.2	−0.4	1.8	−0.6	−1.2	−0.6	0.283
Mol. Rel. (mm)	−3.6	1.8	−2.9	1.6	0.4	1.0	−0.7	−4.0***	−3.3***	0.000

Pal.: Palatal; Pl.: Plane; Mand.: Mandibular; Mol.: Molar; Rel.: Relationship; Diff.: Difference; deg (degrees).

Bold values in the P column indicate statistical significance.

*P < 0.05; **P < 0.01; ***P < 0.001.

Both Alt-RAMEC/FM and RME/FM protocols produced statistically significant favourable effects during the orthopedic treatment interval (T2–T1). More precisely, the Alt-RAMEC/FM and the RME/FM groups revealed with respect to the Control group a greater amount of maxillary protraction (SNA Alt-RAMEC/FM group versus Control group +2.1°; SNA RME/FM group versus Control group +1.5°), a control of the mandibular projection (SNB Alt-RAMEC/FM group versus Control group −1.6°; SNB RME/FM group versus Control group −1.5°), and an improvement of sagittal intermaxillary skeletal and dental relationships (ANB Alt-RAMEC/FM group versus Control group +3.7° and ANB RME/FM group versus Control group +2.9°; Mol. Rel. Alt-RAMEC/FM group versus Control group −4.0 mm and Mol. Rel. RME/FM group versus Control group −3.3 mm). When compared with the Control group, the Alt-RAMEC/FM group showed a statistically significant increase of the Wits appraisal (Wits Alt-RAMEC/FM group versus Control group +2.4 mm), a statistically significant opening of the mandibular plane angle (SN-Mand. Pl. Alt-RAMEC/FM group versus Control group +1.6°), and a statistically significant better control of mandibular length (CoGn Alt-RAMEC/FM group versus Control group −2.6 mm). On the other hand, the RME/FM group showed a statistically significant greater increase of the Palatal Plane—Mandibular Plane angle (Pal. Pl.–Mand. Pl. RME/FM group versus Control group +2.0°) with respect to the Control group. No statistically significant differences were found for the comparison between the Alt-RAMEC/FM and RME/FM groups.

Post-treatment changes (T3–T2 changes)

Table 4 shows the descriptive statistics and statistical comparisons between the three groups for the T3–T2 interval. During the post-orthopedic treatment period, a statistically significant relapse of the improvement in molar relationship was observed for both the Alt-RAMEC/FM and RME/FM groups when compared with the Control group (Mol. Rel. Alt-RAMEC/FM group versus Control group 1.9 mm and Mol. Rel. RME/FM group versus Control group 1.9 mm). No statistically significant differences were found for any of the cephalometric variables when comparing the Alt-RAMEC/FM group with the RME/FM group.

Table 4.

Descriptive statistics and statistical comparisons (ANOVA with Tukey’s post hoc test or Kruskal–−Wallis with Dunn’s post-hoc test) for the T3–T2 changes

	Alt-RAMEC/FM (1) N = 21		RME/FM (2) N = 22		Controls (3) N = 15
Variables	Mean	SD	Mean	SD	Mean	SD	Diff. 1–2	Diff. 1–3	Diff. 2–3	P
Age (yr)	6.9	1.0	6.8	1.7	7.5	2.4	0.1	−0.6	−0.7	0.461
SNA (deg)	−0.2	2.4	0.3	1.7	0.8	2.3	−0.5	−1.0	−0.5	0.381
SNB (deg)	2.4	2.3	2.7	2.9	2.5	2.5	−0.3	−0.1	0.2	0.913
ANB (deg)	−2.6	2.2	−2.3	2.3	−1.7	1.5	−0.3	−0.9	−0.6	0.466
Wits (mm)	−0.1	3.9	−0.5	2.7	−2.1	2.8	0.4	2.0	1.6	0.161
SN-Pal. Pl. (deg)	0.4	2.5	0.6	2.3	0.7	2.1	−0.2	−0.3	−0.1	0.914
SN-Mand. Pl. (deg)	−3.7	3.2	−2.5	3.7	−2.0	4.0	−1.2	−1.7	−0.5	0.113
Pal. Pl.–Mand. Pl. (deg)	−4.1	3.8	−3.1	3.2	−2.7	3.2	−1.0	−1.4	−0.4	0.444
CoGn (mm)	18.6	6.5	19.5	8.0	17.0	5.2	−0.9	1.6	2.5	0.547
CoGo (mm)	10.4	4.4	10.5	4.5	9.6	4.3	−0.1	0.8	0.9	0.810
CoGoMe (deg)	−1.9	3.2	−2.6	2.7	−2.6	3.6	0.7	0.7	0.0	0.720
Mol. Rel. (mm)	3.0	2.4	3.0	1.9	1.1	1.8	0.0	1.9*	1.9*	0.015

Pal.: Palatal; Pl.: Plane; Mand.: Mandibular; Mol.: Molar; Rel.: Relationship; Diff.: Difference; deg (degrees).

Bold values in the P column indicate statistical significance.

*P < 0.05; **P < 0.01; ***P < 0.001.

Discussion

Among the different new approaches that have been proposed recently for the treatment of Class III malocclusion (9, 25, 26), the Alt-RAMEC protocol has gained much popularity in the orthodontic community (8). However, to the best of our knowledge, no previous study investigated into the post-treatment stability of the Alt-RAMEC approach.

The present retrospective controlled study evaluated the stability at a post-pubertal stage of skeletal maturation of the outcomes of the modified Alt-RAMEC/FM protocol in a sample of Class III patients. Twenty-one 6-year-old patients treated consecutively with the Alt-RAMEC/FM approach and presenting with lateral cephalograms taken before orthopedic treatment (T1), after orthopedic treatment (T2), and at a post-pubertal observation (T3, about 7 years after the end of orthopedic treatment) were analysed and compared with a sample of 22 Class III patients treated consecutively with the conventional RME/FM protocol and with a Control group of 15 subjects with untreated Class III malocclusion. At T3 all subjects showed a post-pubertal stage of skeletal maturation (CS4-CS6). During the T3-T2 observation interval, three patients of the Alt-RAMEC/FM group and six patients of the RME/FM group underwent a second phase of facial mask treatment. As for distribution of second phase of facial mask treatment, no statistically significant difference was found between the two groups (chi-square test, P = 0.502).

Overall changes (T3–T1 changes)

The statistical comparisons of the T3–T1 changes between the three groups revealed that both the Alt-RAMEC/FM and the RME/FM protocols produced statistically significant favourable effects with respect to the growth changes in the Control group in terms of improvement of intermaxillary sagittal skeletal relationships (ANB Alt-RAMEC/FM group versus Control group 2.8° and ANB RME/FM group versus Control group 2.2°; Wits Alt-RAMEC/FM group versus Control group 4.4 mm and Wits RME/FM group versus Control group 2.7 mm). These data are consistent with the results of a long-term controlled study on the stability of the effects of RME/FM therapy in a sample of 22 Class III patients (mean age at T1 9.2 years ± 1.6) (10). For the T3–T1 interval, the authors found that the treated group showed with respect to the Control group a statistically significant improvement of the ANB and Wits appraisal (1.4° and 3.0 mm, respectively). A recent systematic review and meta-analysis on the stability of maxillary protraction in Class III children reported similar outcomes: at the medium term observation, the investigators found a statistically significant mean difference of 1.6° for the ANB between the treated groups and the control groups (11).

As for the stability of maxillary advancement, both treatment approaches evaluated in the present study produced favourable effects with respect to Control group (SNA Alt-RAMEC/FM group versus Control group 1.1° and SNA RME/FM group versus Control group 1.0°). Nevertheless, these values were not statistically significant; however, they were similar to the data reported by the literature (SNA-treated groups versus Control groups mean difference 1.02°) (11).

Looking at the vertical skeletal changes, no statistically significant difference was found in this paper between either the Alt-RMEC/FM and RME/FM samples or the untreated Class III sample as previously confirmed by Masucci et al. and Lin et al. (10–11).

As for the improvement of molar relationship during the T3–T1 interval, only the Alt-RAMEC/FM therapy produced statistically significant stable effects when compared with the Control group (Mol. Rel. Alt-RAMEC/FM group versus Control group −2.1 mm).

Interestingly enough, the comparisons for the T3–T1 changes between the Alt-RAMEC/FM and RME/FM groups did not reveal any statistically significant difference.

Short-term changes (T2–T1 changes)

The evaluation of the short-term effects (T2–T1 changes) of the Alt-RAMEC/FM and RME/FM protocols showed that, when compared with the growth modification in the untreated Control group, both treated groups achieved statistically significant favourable results in terms of maxillary advancement (SNA Alt-RAMEC/FM group versus Control group 2.1°; SNA RME/FM group versus Control group 1.5°), control of mandibular projection (SNB Alt-RAMEC/FM group versus Control group −1.6°; SNB RME/FM group versus Control group −1.5°), and improvement of maxillo-mandibular sagittal skeletal and dental relationships (ANB Alt-RAMEC/FM group versus Control group 3.7° and ANB RME/FM group versus Control group 2.9°; Mol. Rel. Alt-RAMEC/FM group versus Control group −4.0 mm and Mol. Rel. RME/FM group versus Control group −3.3 mm). These data are consistent with the findings of the RCT carried out by Liu et al. (5). For their two samples of 7- to 13-year-old Class III patients treated with the Alt-RAMEC/ FM approach or with the RME/FM approach, these investigators reported favourable improvements for sagittal position of the maxilla, sagittal position of the mandible, and sagittal skeletal intermaxillary relationships (SNA 2.7° and 1.9°, respectively; SNB −1.5°and −2.3°, respectively; ANB 4.2° and 4.3°, respectively). A very recent study (7) which analysed the outcomes of the Alt-RAMEC/FM therapy versus the outcomes of RME/FM and the FM alone approaches in a sample of 9.5-year-old Class III patients found similar results for both the Alt-RAMEC/FM and RME/FM groups (SNA 3.3° and 2.4°, respectively; SNB −1.0°and −1.2°, respectively; ANB 3.4° and 3.9°, respectively).

As for the evaluation of the vertical skeletal variables, the results of the present study showed that the Alt-RAMEC/FM approach produced a statistically significant clockwise rotation of the mandibular plane with respect to the Control group (SN-Mand. Pl. Alt-RAMEC/FM group versus Control group 1.6°), while the RME/FM protocol produce a statistically significant increase of the Palatal plane to Mandibular plane angle when compared to the Control group (Pal. Pl.–Mand. Pl. RME/FM group versus Control group 2.0°). The RCT by Liu et al. (5) reported a similar degree of clockwise rotation of the mandible with respect to SN plane in the Alt-RAMEC/FM group (2.0°), while for the RME/FM group a greater amount of clockwise mandibular rotation was found (3.3°). As for the inclination of the Palatal plane with respect to the SN plane, both the Alt-RAMEC/FM and the RME/FM protocols did not produce any statistically significant change with respect to the Control group. On the contrary, the study by Isci et al. (3) reported a statistically significant closure of the Palatal plane angle after the orthopedic treatment with the Alt-RAMEC/FM approach (SN/ANS-PNS change −1.53°) while Liu et al. (5) found a non-significant counter-clockwise rotation of the Palatal plane at the end of Alt-RAMEC/FM therapy (SN/PP change −1.73°). The inconsistency of these findings with the results of the present study could be explained by some possible differences in the clinical management of the facial mask in terms of inclination of the extraoral elastics.

When the short-term outcomes of the Alt-RAMEC/FM protocol were compared to the short-term effects of the conventional RME/FM protocol, no statistically significant differences were found. These data, which are in agreement with the findings of the 3D investigation by Fischer et al. (6), are apparently not consistent with most of the recent literature on this topic. The RCT by Liu et al. (5) reported that the Alt-RAMEC/FM therapy achieved statistically significant greater favourable effects in terms of maxillary protraction (SNA 0.7°) and limitation of the increase of the mandibular plane angle (−1.3°) with respect to the RME/FM protocol. Similarly, two recent meta-analysis (8, 9) showed statistically significant differences between the Alt-RAMEC/FM and the RME/FM approaches in terms of treatment outcomes.

In particular, Almuzian and collaborators (8) reported that the Alt-RAMEC/FM protocol produced statistically significant greater improvements as for sagittal maxillary position (1.2°) and sagittal intermaxillary relationships (0.7°) than the RME/FM protocol (8). Consistently, the paper by Wu et al. (9) revealed a more efficient maxillary advancement with the Alt-RAMEC/FM therapy with respect to the RME/FM protocol, represented by a statistically significant larger increase of the SNA angle (+0.8°).

However, most of the previous studies on this topic (5, 8, 9) analysed samples of older (mean age about 10–11 years) and ethnically different patients (Asian populations) with respect to the patients included in the present study. Moreover, the expansion/constriction sequence generally lasted longer, and the daily activation rate was higher than the Alt-RAMEC protocol used in this study.

Furthermore, the actual values of the differences between the two treatment protocols effects reported by all these studies, although statistically significant, in most of the cases could probably not be considered clinically relevant.

Post-treatment changes (T3–T2 changes)

When the post-treatment changes (T3–T2 changes) were analysed in the present study, no statistically significant difference was found between the three groups with the exception of the relapse of the improvement in molar relationship observed in the two treated groups with respect to the Control group (Mol. Rel. Alt-RAMEC/FM group versus Control group 1.9 mm and Mol. Rel. RME/FM group versus Control group 1.9 mm).

Therefore, an overall assessment of the findings of this study allows us to affirm that both the Alt-RAMEC/FM and RME/FM approaches, when performed during the early stage of skeletal maturation, were able to achieve very positive effects immediately after orthopedic therapy. During the post-treatment period of 7 years, these favourable changes were partially lost, leading to a slight relapse of the treatment outcomes. However, at the post-pubertal observation, the Alt-RAMEC/FM and the RME/FM protocols revealed a significantly stable improvement of the sagittal skeletal maxillo-mandibular relationships.

On the other hand, both in the short and medium term, neither of the Alt-RAMEC/FM or RME/FM approaches could be considered more effective than the other. According to the results of our study, the Alt-RAMEC protocol does not seem to produce a more favourable stimulation of the circum-maxillary sutures with respect to conventional RME in prepubertal Class III patients. The circum-maxillary sutures during the early developmental stages are not as heavily interdigitated as during the pubertal phases, and, therefore, the sutural disarticulation produced by the Alt-RAMEC protocol before puberty is not so effective. Future studies should investigate if treatment timing can influence the efficacy of the Alt-RAMEC protocol. Moreover, studies assessing the medium or long-term effects of the Alt-RAMEC/FM protocol versus RME/FM protocol when performed in older patients are needed. To date, for these reasons, from a clinical point of view, the Alt-RAMEC/FM protocol cannot be recommended as the approach of choice for the therapy of Class III dentoskeletal disharmony in very young subjects compared to the conventional RME/FM protocol.

Limitations

The limitations of the present study were its retrospective nature and the comparison of the treated groups with an historical control sample of subjects with untreated Class III malocclusion. Moreover, the follow-up was limited to the post-pubertal period when active craniofacial growth, particularly at the mandibular level, was not completed.

Conclusions

1. The Alt-RAMEC/FM and the RME/FM protocols are effective approaches for the treatment of Class III dentoskeletal disharmony in growing patients.

2. At the post-pubertal evaluation, the two treatment approaches showed stable outcomes in terms of improvement of sagittal skeletal maxillo-mandibular relationships.

3. At the short-term evaluation, both Alt-RAMEC/FM and RME/FM protocols produced favourable effects in terms of maxillary advancement, mandibular projection control, and correction of sagittal skeletal and dental intermaxillary relationships.

4. Neither protocol was more effective than the other in either the short or medium term.

Acknowledgements

The authors would like to thank Dr. Maria Laura Avolicino and Dr. Carlotta Olivo for their valuable help in selecting the Class III-treated samples.

Conflicts of interest

None to declare.

Data availability

Data are available on request.