Haas-type Rapid Maxillary Expansion Research Articles

Multistage Treatment of a Class II Division 1 Malocclusion With Severe Crowding

The improvement of facial aesthetics is one of the main reasons why patients with a class II division 1 malocclusion seek orthodontic treatment. There are various techniques available to treat class II malocclusions, one of which is a two-phase approach that includes functional jaw orthopedics as well as fixed orthodontic treatment. The following case report describes the case of a 12-year-old growing female patient AK with a severe class II division 1 malocclusion. The patient was treated initially with Haas-type rapid maxillary expansion. Pre-functional orthodontics was followed with a removable twin block functional appliance and a combination pull headgear for growth modification and correction of her overjet and profile. Thereafter, a fixed, pre-adjusted MBT (McLaughlin Bennet Trevsi) prescription orthodontic appliance was utilized following the extractions of the maxillary first premolars and two lower incisors in the final phase, to ensure well-aligned arches and improved aesthetics and function.

A New Proposal: a Digital Flow for the Construction of a Haas-Inspired Rapid Maxillary Expander (HIRME).

Maxillary expansion is a common orthodontic treatment used for the correction of posterior crossbite resulting from reduced maxillary width. Transverse maxillomandibular discrepancies are a major cause of several malocclusions and may be corrected in different manners; in particular, the rapid maxillary expansion (RME) performed in the early mixed dentition has now become a routine procedure in orthodontic practice. The aim of this study is to propose a procedure that reduces the patient cooperation as well as the lab work required in preparing a customized Haas-inspired rapid maxillary expander (HIRME) that can be anchored to deciduous teeth and can be utilized in mixed dentition with tubes on the molars and hooks and brackets on the canines. This article thus presents an expander that is completely digitally developed, from the first moment of taking the impression with an optical scanner to the final solidification phase by the use of a 3D printer. This digital flow takes place in a CAD environment and it starts with the creation of the appliance on the optical impression; this design is then exported as an stl extension and is sent to the print service to obtain a solid model of the device through a laser sintering process. This “rough” device goes through a post-processing procedure; finally, a commercial expansion screw is laser-welded. This expander has all the advantages of a cast-metal Haas-type RME that rests on deciduous teeth; moreover, it has the characteristic of being developed with a completely digitized and individualized process, for the mouth of the young patient, as well as being made completely of cobalt-chrome, thus ensuring greater adaptability and stability in the patient’s mouth.

Early interceptive treatment in the primary dentition – a case report

This article describes treatment of a patient presenting with a class II malocclusion, maxillary and mandibular crowding, posterior crossbite and an increased deep bite, where the specific treatment goals were achieved in the early mixed dentition by only working on the primary teeth. A Haas-type rapid maxillary expansion (RME) appliance was modified to be anchored on the primary second molars and canines and activated once a day, with each activation equal to 0.20 mm. The appliance was blocked after 30 days and left as a retainer. After 6 months, the RME appliance was removed and bands were cemented to the primary second molars in order to apply traction with headgear. After complete eruption of the mandibular central and lateral incisors, sequential slicing of the lower primary teeth was performed to transfer the leeway space from the distal to the mesial part of the arch. When the patient had entered the permanent dentition, a dental class I relationship was achieved, the crossbite corrected and the crowding improved. The overjet and overbite were also improved. No permanent teeth were involved during this phase of treatment. The outcome of this case report shows that it is possible to work only on primary teeth in the mixed dentition and this can be an effective way to correct a class II malocclusion with deep bite, posterior crossbite and maxillary and mandibular crowding.

Long-term Anteroposterior and Vertical Maxillary Changes in Skeletal Class II Patients Treated with Slow and Rapid Maxillary Expansion

To evaluate a 10-year follow-up of anteroposterior and vertical maxillary changes in skeletal Class II patients treated with slow and rapid maxillary expansion methods. The sample consisted of 70 patients divided into two groups: (1) treated with a cervical headgear with expansion of the inner bow (CHG) and (2) using a Haas-type rapid maxillary expansion appliance in conjunction with cervical headgear (RME-CHG). The CHG group consisted of 40 patients (18 males and 22 females; average age 10.6 years at pretreatment [T1], 13.6 years at posttreatment [T2], and 23.6 years at postretention [T3]). The RME-CHG group consisted of 30 patients (14 males and 16 females; average age 10.4 years at T1, 14.0 years at T2, and 24.6 years at T3). The profiles of SNA and SN-PP angles showed no significant differences in either group at T1, T2, and T3 phases. For the entire sample, the profile analysis between the phases showed reduction in the SNA angle from T1-T2 and an increase from T2-T3. The SN-PP angle showed an increase from T1-T2 and a decrease from T2-T3. Treatment of skeletal Class II patients with slow and rapid maxillary expansions was efficient and stable over the long-term. The profiles of SNA and SN-PP at T1, T2, and T3 achieved with slow and rapid maxillary expansions were clinically equivalent.

Mandibular Behavior with Slow and Rapid Maxillary Expansion in Skeletal Class II Patients

Abstract Objective: To evaluate anteroposterior and vertical mandibular changes in skeletal Class II patients treated with slow or rapid maxillary expansions at 10-year follow-up. Materials and Methods: The sample consisted of 70 patients divided into two groups, treated with (1) a cervical headgear (CHG) with expansion of the inner bow or (2) a Haas-type rapid maxillary expansion (RME) appliance in conjunction with CHG (RME-CHG). The CHG group consisted of 40 patients (18 males and 22 females, with an average age of 10.6 years at pretreatment [T1], 13.6 years at posttreatment [T2], and 23.6 years at postretention [T3]), and the RME-CHG group consisted of 30 patients (14 males and 16 females with an average age of 10.4 years at T1, 14.0 years at T2, and 24.6 years at T3). Results: The profiles of SNB, B-Hor, and Pog-Hor showed significant increases for all treatment phases in both groups. The SN-Go-Gn angle showed no significant decrease from T1 to T2 and a significant decrease from T2 to T3. Conclusions: For the entire sample (CHG + RME-CHG) the profile analysis between the phases showed mean increases in B-Ver and Pog-Ver for both phases.

Arch width Changes with a Rapid Maxillary Expansion Appliance Anchored to the Primary Teeth

To examine the dimensional changes after rapid maxillary expansion (RME) carried out in the transitional dentition with the primary teeth as anchorage. Group A was composed of 31 consecutive transitional dentition patients with posterior quadrant crossbites treated with a Haas-type RME appliance anchored on the maxillary primary molars and canines. No treatment was administered after palatal expansion. Study models were made before RME (T1), at appliance removal (T2), and at least 1 year after appliance removal (T3). A control sample of 60 individuals with posterior quadrant crossbites who had had no orthodontic treatment was categorized into group B (30 individuals with an average age comparable with the treated patients at T2) and group C (30 individuals with an average age comparable with the treated patients at T3). Permanent molar crossbites were corrected at T2, and this correction was maintained at T3 in all patients. The mean permanent maxillary intermolar width was 42.6 +/- 2.3 mm at T1, 46.7 +/- 1.9 mm at T2 (P < .01), and 46.3 +/- 1.8 mm at T3 (P < .01) in group A; 42.9 +/- 2.7 mm (P < .01) in group B; and 44.4 +/- 3.0 (P < .01) in group C. Premolar and canine widths were slightly wider than the control at T3. To avoid undesirable treatment-induced effects on maxillary permanent molars, a stable transverse correction could be achieved with the RME appliance anchored on the primary teeth.

Thin-plate spline analysis of the short- and long-term effects of rapid maxillary expansion.

The aim of this study was to investigate the short- and long-term effects induced by rapid maxillary expansion (RME) on the shape of the maxillary and circummaxillary structures by means of thin-plate spline (TPS) analysis. The sample consisted of 42 patients who were compared with a control sample of 20 subjects. The treated subjects underwent Haas-type RME, followed by fixed appliance therapy. Postero-anterior (PA) cephalograms were analysed for each treated subject at T1 (pre-treatment), T2 (immediate post-expansion), and T3 (long-term observation), and were available at T1 and T3 for the control group (CG). The mean age at T1 was 11 years and 10 months for both groups. The mean chronological ages at T3 were 20 years, 6 months for the treated group (TG) and 17 years, 8 months for the control group. The study focused on shape changes in the maxillary, nasal, zygomatic, and orbital regions. TPS analysis revealed significant shape changes in the TG. They consisted of an upward and lateral displacement of the two halves of the naso-maxillary complex as a result of active expansion in the short-term, and normalization of maxillary shape in the transverse dimension in the long-term (the initial transverse deficiency of the maxilla in the treated group was eliminated by RME therapy both in the short- and long-term). At the end of the observation period, the nasal cavities were larger when compared with both their pre-expansion configuration and the final configuration in the controls. RME with the Haas appliance appears to be an efficient therapeutic means to induce permanent favourable changes in the shape of the naso-maxillary complex.

Long-term effects of rapid maxillary expansion: A posteroanterior cephalometric evaluation

The aim of this study was to investigate long-term effects induced by rapid maxillary expansion (RME), followed by comprehensive orthodontic treatment, in a sample of 42 patients compared with normal growth changes in a sample of 20 subjects. Treated subjects underwent Haas-type RME with 2 turns a day (0.25 mm per turn) until the expansion screw reached 10.5 mm (about 21 days). The Haas expander was kept on the teeth as a passive retainer for an average of about 2 months. Immediately after the Haas expander was removed, fixed standard edgewise appliances were placed. Posteroanterior cephalograms were analyzed for each subject in both groups at T1 (pretreatment) and at T2 (long-term observation). The mean age at T1 was 11 years 10 months for both the treated and the control groups. The mean ages at T2 also were comparable (20 years 6 months for the treated group, and 17 years 8 months for the control group). The study included transverse measurements on dentoalveolar structures, maxillary and mandibular bony bases, and other craniofacial regions (nasal, zygomatic, orbital, and cranial). RME followed by edgewise appliance therapy appears to be an effective procedure to increase transverse facial dimensions in the long term, at both the skeletal and the dentoalveolar levels. Significant pretreatment deficiencies in maxillary width, maxillary incisor apex width, and maxillary first molar width remained corrected at a mean age of about 20 years. The initial deficiency in lateroorbitale width was also eliminated. (Am J Orthod Dentofacial Orthop 2002;121:129-35)

A longitudinal study of skeletal side effects induced by rapid maxillary expansion

Orthopedic expansion of the maxillary arch—rapid maxillary expansion (RME)—is a commonly used treatment technique that has become increasingly popular during the last 25 years. During this time, however, clinicians routinely have imputed a variety of undesirable side effects to RME, particularly bite opening. Whereas there have been many explanations as to the mechanisms underlying such RME-related effects as bite opening, few studies have considered the long-term effects of RME in the vertical and sagittal dimensions of the face. The purpose of this investigation was to examine cephalometrically the long-term effect that the Haas-type rapid maxillary expansion may have on bite opening and on the anteroposterior position of the maxilla. The sample consisted of 25 patients who had undergone RME with the Haas-type expander, followed by standard edgewise therapy. This RME sample was compared with a group of 25 patients who had standard edgewise treatment (SET) only and with a control (CTRL) group of 23 subjects. Mean initial form and mean age at start of treatment for the RME, SET, and CTRL groups were similar. Statistically significant among-group differences were documented for only 2 of 10 cephalometric variables sensitive to anteroposterior and vertical skeletal changes. These differences, however, were not clinically significant. The current investigation implies therefore that RME therapy with the Haas-type expander has little long-term (more than 6 years after treatment) effect on either the vertical dimensions or the anteroposterior dimensions of the face. (Am J Orthod Dentofac Orthop 1997;112:330-7.)