Rapid Palatal Expansion Appliance Research Articles

Comparison of treatment outcomes with banded and bonded RPE appliances

The purpose of this retrospective study was to compare the treatment outcomes with a banded (n = 38) versus a bonded (n = 55) rapid palatal expansion appliance followed by edgewise orthodontics. Both lateral cephalometric radiographs and orthodontic study casts were evaluated at pretreatment and posttreatment time periods. Overall, the banded rapid palatal expansion group had more vertical change than the bonded group. However, most of these changes were less than 1° or 1 mm and may be considered clinically insignificant. This study could not establish superiority of one type of rapid palatal expansion technique over another. (Am J Orthod Dentofacial Orthop 1999;116:31-40)

Clinical results of the maxillary protraction in Korean children

Sixty subjects with ages ranging from 8 to 13 years were divided into two groups according to the intraoral appliances used. Group I consisted of 47 subjects with rapid palatal expansion (RPE) appliances and group II consisted of 13 subjects with labiolingual appliances (La/Li). Group I was subdivided into three subgroups by age and two subgroups by the timing of the protraction. The cephalometric radiographs of all subjects were analyzed before and after correction of anterior crossbite. The following results were obtained: (1) After maxillary protraction, the maxilla and maxillary dentitions moved forward and downward, and the mandible and mandibular dentitions moved backward and downward. (2) The maxilla moved more forward in the RPE group, compared with La/Li group. (3) The palatal plane angle decreased more in the protraction-during-palatal-expansion group than protraction-after-palatal-expansion group. (4) Age did not show any statistically significant difference. (Am J Orthod Dentofac Orthop 1995;108:583-92.)

Surgical-Orthodontic Correction of Transverse Maxillary Deficiency

A conservative osteotomy of the zygomaticomaxillary buttress in combination with a rapid palatal expansion appliance is a dependable technique for the treatment of horizontal maxillary deficiency in adults. This procedure has been used successfully in 56 patients in our series, but 17 patients (30 per cent) required a midpalatal osteotomy. In two patients, overexpansion was not achieved because of necrosis of the mucosa. In three other patients, expansion had to proceed at a slower pace because of mucosal ulceration. There have been no other complications. The procedure is indicated mainly in those patients with a horizontal deficiency who do not require subsequent surgery, but for some patients it may be the preliminary procedure. Twelve patients (21 per cent) had subsequent orthognathic surgery. Follow-up has been from 1 to 12 years and there has been no relapse. In our opinion, the zygomaticomaxillary buttress is the primary area of resistance to lateral movement of the maxilla by rapid maxillary expansion appliances.

Surgical-Orthodontic Correction of Transverse Maxillary Deficiency

A conservative osteotomy of the zygomaticomaxillary buttress in combination with a rapid palatal expansion appliance is a dependable technique for the treatment of horizontal maxillary deficiency in adults. This procedure has been used successfully in 56 patients in our series, but 17 patients (30 percent) required a midpalatal osteotomy. In two patients, overexpansion was not achieved because of necrosis of the mucosa. In three other patients, expansion had to proceed at a slower pace because of mucosal ulceration. There have been no other complications. The procedure is indicated mainly in those patients with a horizontal deficiency who do not require subsequent surgery, but for some patients it may be the preliminary procedure. Twelve patients (21 per cent) had subsequent orthognathic surgery. Follow-up has been from 1 to 12 years and there has been no relapse. In our opinion, the zygomaticomaxillary buttress is the primary area of resistance to lateral movement of the maxilla by rapid maxillary expansion appliances.

Skeletal changes in vertical and anterior displacement of the maxilla with bonded rapid palatal expansion appliances

The purpose of this study was to determine whether anterior and inferior displacement of the maxilla seen with rapid palatal expansion when done with a banded rapid palatal expansion appliance is significantly different from an occlusally bonded rapid palatal expansion appliance. It was hypothesized that the bonded appliance would limit unwanted displacement of the maxilla by producing vertical forces on both arches in a manner similar to a functional appliance. The study was conducted using the bonded appliance on 20 adolescents and comparing the results with those of a banded appliance population—namely, 60 cases from Wertz's study. Lateral cephalometric radiographs were taken before treatment and again after the expansion appliances were removed. The results of this study suggest that the downward and anterior displacement of the maxilla often associated with the banded rapid palatal expansion appliance may be negated or minimized with the more versatile bonded appliance.

A comparison of two rapid palatal expansion appliances and their effect on the palatal cross-sectional area

A comparison of two rapid palatal expansion appliances and their effect on the palatal cross-sectional area

A microfluorescent and scanning electron microscope study of the effects of acrylic reinforced and rapid palatal expansion appliances on the mid-palatal suture in Macaca mulatta

The use of acrylic-free and acrylic-reinforced appliances in cases of maxillary constriction has been reported extensively, but no controlled investigation has evaluated these two appliances by means of microfluorescence and the scanning electron microscope. In three groups of dentally matched Mncaca ntulatta female pairs, each received either an acrylic-reinforced or an acrylic-free appliance. A seventh animal served as a control. Weekly intravenous injections of oxytetracycline labeled new bone formation. In addition to the microfluorescent evaluation of the suture, the soft-tissue palate was critically dried, coated with gold and carbon, and examined under the scanning electron microscope. Preliminary results indicate that little difference is evident in the midpalatal suture between the acrylic-free and the acrylic-reinforced appliances. The scanning electron microscope indicated that acrylic-reinforced appliances are more likely to cause tissue irritation and sloughing.

A comparative microfluorescent study of the effects of acrylic-reinforced and acrylic-free rapid palatal expansion appliances on the alveolus and palatal shelves

Seven rhesus monkeys were used, with matched pairs having the same or different appliances. There was one control animal. Previous to and at regular intervals throughout treatment the monkeys were given intravenous injections of oxytetracycline to label new cellular activity in the bone. Sections of the maxillae were taken and analyzed by means of microfluorescence for changes in the bone and soft tissue. Evidence indicates that the two appliances are equally effective in widening the maxillary palates. Differences included both a wider maintained palatal vault with the acrylic-free appliances, and more softand hard-tissue necrosis with the acrylic-reinforced appliances. Both appliances tipped the teeth to the same degree in the early stages of activation, and the teeth became equally uprighted with either appliance. The retention and maintenance of the increased arch width were the same with both appliances, as also were the rate and degree of relapse. Both appliances proved to be very effective in achieving increased arch width, although the acrylic-free (Hyrax) appliance permitted healthier soft tissue and a wider vault maintenance.

Extraoral high-pull forces with rapid palatal expansion in the Macaca mulatta

On the basis of the cephalometric and histologic findings, the following conclusions were made: Over-all evaluation of this study indicates that orthopedic forces brought about changes in sutural, endochondral, and appositional growth systems of the dentofacial complex. None of the changes produced was pathologic. Combining orthopedic forces and appliances in the form used in this study produces increased cellular activity in sutures while still maintaining cellular and sutural integrity. These forces decrease endochondral activity and apposition while maintaining cellular integrity. Squamous sutures are not as responsive to orthopedic forces as serrated sutures. Root resorption was a result of lateral and distal orthopedic movement. Discontinuation of orthopedic therapy allows resorption lacunae to return to normal by filling with cementum. The changes observed are a combination of slight tooth movement and much sutural adaptation. Observation of the procion dye indicates that the headgear traction decreases lateral apposition in facial bones. Occipital headgear traction force as applied in this study can alter the position of the maxilla. With proper management, the combination of the rapid palatal expansion appliances and the occipital-pull headgear may have implications in Class II, Division 1 and open-bite therapy. The exact mechanism of sutural movement found in this study is not understood. Superimposition of the zygomaticomaxillary implants indicates that sutural area and geometry of the face may be factors in determining changes resulting from orthopedic force. Orthopedic changes, like orthodontic changes, require retention. Specific attention to technique in fabrication of headgear for monkeys would aid in the study of orthopedic forces in animals. Future combination of orthopedic forces should be studied to determine the amount, duration, and application necessary to bring about desired skeletal changes.

The effects of digital and dummy sucking on arch widths, overbite, and overjet: A longitudinal study: By B. D. Bowden. Australian D. J. 11: 396–404, December, 1966

A tandem-loop nickel titanium temperature-activated palatal expansion appliance was developed that produces light, continuous pressure on the midpalatal suture and requires little patient cooperation or laboratory work. The purpose of this study was to compare the effectiveness of the nickel titanium palatal expansion appliance with that of a rapid palatal expansion appliance. The study sample comprised 25 patients who required palatal expansion as part of their orthodontic treatment. The sample was divided into 2 groups, with 13 patients in the nickel titanium group and 12 patients in the rapid palatal expansion group. Study models were taken before treatment and at the end of the retention period after expansion. Intermolar width, palatal width, palatal depth, alveolar tipping, molar tipping, and molar rotation were analyzed. In addition, occlusal radiographs were obtained before and 2 weeks after expansion to evaluate for sutural separation by the appliances. Results showed significant increases in midpalatal sutural separation, tipping of the alveolus, and tipping of the molars after expansion in both groups. However, greater midpalatal sutural separation was found in the rapid palatal expansion group and greater molar rotation was found in the nickel titanium group. Stepwise multiple regression analysis showed that alveolar tipping, palatal width change, and molar tipping are the best predictors of intermolar width change in the rapid palatal expansion group. Radiographic evidence of midpalatal sutural separation was less obvious in the nickel titanium group. These results suggest that both the nickel titanium and the rapid palatal expansion appliances are capable of expanding the maxillary dentition and alveolar process and are equally capable of correcting posterior crossbites. In the current study, the rapid palatal expander widened the palate more reliably, whereas the nickel titanium expander tipped the molars buccally to a greater extent and caused more distal molar rotation. The clinician's choice of expander will depend on his or her initial diagnosis and treatment goals. (Am J Orthod Dentofacial Orthop 2001;119:11-20)