Introduction
When treating a Class III malocclusion, doctors are faced with a predicament. The time of treatment varies, from early intervention during the pre-pubertal phases of development to intervention after the patient has completed active growth. Treatment options include dentofacial orthopedics, camouflage orthodontics, and a combination orthognathic surgical and orthodontic approach.1, 2 The most often used approach for early treatment of these individuals is protraction face mask (PFM) therapy paired with rapid maxillary expansion (RME). Liou introduced the Alt-RAMEC (Alternate Rapid Maxillary Expansion and Contraction protocol) in 2005.3 It enables for sutural mobilisation by opening and closing the RME screw for 7-9 weeks.4, 5 In contrast to standard RME, its application strategy is to enhance the frequency of rapid maxillary expansion by alternating rapid expansion and constriction several times. The Alt-RAMEC procedure was shown to have double the amount of anterior maxillary displacement as the regular RME protocol. Previous research found that using the Alt-RAMEC regimen in conjunction with maxillary protraction resulted in an increase in pharyngeal airway. Volumetric measurements are possible using CBCT (Cone beam computed tomography), which is more beneficial for analyzing the morphology of airway structures.6 The three-dimensional measurement of the airway cavity is superior to the traditional two-dimensional approaches for evaluating it. The goal of this case report is to study and analyse the airway alterations that occur immediately following Alternate Rapid Maxillary Expansion and Constriction utilising CBCT images recorded before and after the technique is applied.
Case History
The patient, 10 years old, came to Department of Orthodontics and Dentofacial Orthopedics with a complaint of backwardly placed upper teeth, an un-aesthetic dental and facial appearance. Patient also had anterior cross-bite in addition to bilateral posterior cross-bite. Class III malocclusion with maxillary retrusion was seen in the patient. (Figure 1)
The treatment objectives were to obtain a normal profile by skeletal correction, correct the Class III dental relationship and obtain Class I canine and Class I incisal relationship.
The patient was delivered a bonded type of RME appliance with a Hyrax expansion screw in the middle and an occlusal splint (extending from the distal of the canines and encompassing the posterior teeth) for the Alt-RAMEC protocol. (Figure 2). The maxilla was expanded and contracted alternating weeks by 4 one quarter turns per day (1 mm) and this was continued for 9 weeks ending with expansion. (Figure 3).
Table 1
Pre-treatment and post-treatment measurements of upper pharyngeal airway, lower pharyngeal airway and total pharyngeal airway.
Two sets of CBCT scans were performed: one before to the start of the therapy and one immediately after the expansion according to the Alt-RAMEC protocol was finished.
The teeth that were bonded for Hyrax maxillary expander were first permanent molar and deciduous second molar on both sides.
For measurement of airway it was divided into 3 parts- anterior nasal compartment, nasal compartment and posterior compartment. Horizontal reference planes and a vertical reference plane was used in both pre-treatment and post-treatment in CBCT scans in the sagittal view. VRP passed through sellion (deepest midpoint on angle formed between nose and forehead) and alar curvature points. HRP 1 passed through infraorbital point and porion. Parallel to HRP 1, two other planes were drawn. HRP 2 passed through posterior nasal spine and HRP 2 passed through most anterior and inferior point of second cervical vertebra.
The nasal compartment was measured volumetrically anterior to VRP. The nasal compartment was measured with HRP 1 as upper border and HRP 2 as lower border. The pharyngeal compartment was measured with HRP 2 as upper border and HRP 3 as lower border. (Figure 5) The airway was assessed in axial plane too so as to make sure that entire air cavity is covered. (Figure 6) (Table 1)
Results
After using the Alt-RAMEC technique, the volume of all compartments of airway increased. The total volume of the pharyngeal airway was also increased. The rise was greater in the nasal compartment than in the others.
Discussion
Alternate rapid maxillary expansion and constriction is a modification of the conventional Rapid maxillary expansion. The use of the Alt-RAMEC regimen prior to maxillary protraction is a successful strategy for treating individuals with Class III malocclusions early.4 The purpose of this strategy is to enhance the efficacy of a device that requires patient cooperation, to increase the ease and effectiveness of the procedure in a short amount of time, to avoid unfavorable dentoalveolar consequences, and to create more skeletal results from the procedure. Increasing the skeletal impact lowers the risk of post-treatment relapse, which is one of the most important problems in orthodontic treatment.7 The Alt-RAMEC protocol accomplishes significantly greater circumaxillary suture disjunction than the Rapid maxillary expansion strategy. The amount of maxillary protraction observed under the Alt-RAMEC protocol was 4-5 mm in 5 months, while it was 1.5-3.0 mm in 10-12 months under the Rapid maxillary expansion protocol.4
The pharyngeal airway space and different craniofacial skeletal pattern morphology of patients, both in anteroposterior aspect (Class I, class II, class III skeletal patterns) and vertical aspect (dolichofacial, mesofacial, brachyfacial) have been co-related and discussed in the orthodontic literature for quite some time. According to several studies, patients with Class III malocclusion typically have velopharynx constriction, pharyngeal airway constriction, nasal obstruction, or choanal stenosis, which can be caused by maxillary hypoplasia and retrusion.8, 9, 10 For decades, lateral cephalometry has been utilized to examine airway size and shape due to its great reproducibility and minimal radiation exposure. The disadvantage of using lateral cephalometric radiographs for upper airway evaluation is that they only give 2-dimensional representations of complicated 3-dimensional anatomic components and do not provide a full-scale image of the upper airway.11 CBCT imaging uses low radiation doses to offer a good picture of tissues with minimum image distortion. The use of CBCT aids in the correct volumetric measuring of the airway.
According to the findings of this case study, the all three compartments of airways as well as the total pharyngeal airway, expanded following the administration of the Alt-RAMEC regimen. Increase was maximum in nasal compartment. This indicates upper pharyngeal airway increased more than lower pharyngeal airway. The forward movement of the retrusive maxilla is responsible for the expansion in upper pharyngeal airway. The increase in lower pharyngeal airway is attributed to increase in the GoMe-SN and FMA angles that are associated with maxillary expansion. There are very few studies in the literature that evaluate the pharyngeal changes after expansion using Alt-RAMEC. Celikoglu M, Buyukcavus12 MH conducted a study to assess changes in pharyngeal airway dimensions after the Alt-RAMEC/FM protocol. The considerable forward movement of the maxilla resulted in an increase in upper pharyngeal airway dimension, but no significant variation in lower pharyngeal airway dimension was noted. Ozbilena E et.al.13 conducted a retrospective study for comparative evaluation of the changes in pharyngeal airway after RME/PFM and Alt-RAMEC/PFM. It was observed that the lower and total pharyngeal airway increased significantly after Alt-RAMECPFM.
