• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.40-49
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• 2010

The Purpose of this paper is to weld a rapid palatal expander using a continuous wave Nd:YAG laser. The rapid palatal expander has become a useful treatment method for severe maxillary transverse deficiencies and posterior crossbites. Rapid maxillary expansion is a well-established method to correct transverse maxillary deficiency and arch length discrepancy. The major process parameters studied in the present laser welding experiment were the positions of focus, laser power and travel speed of laser beam. We measured the fusion zone size and its shape using an optical microscope for the observation of cross-sectional area and tension stress of a rapid palatal expander welded. Through the experimental investigation, the optimum speeds and power of laser without deficiencies of weld cross-sectional area were obtained.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.153-162
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• 1996

Rapid maxillary expansion is widely used for the correction of anteroposterior discrepancies, constriction of the maxillary arch, etc. This experiment was undertaken to examine the serial changes in the osteogenesis as well as the collagen fiber bundles in the intermaxillary suture during the rapid maxillary expansion treatment. Four young female dogs aged 6 to 8 months old and not showing menarche yet were used for the experiment. The maxillary impression of dogs were taken, expansion device cast and Hyrax screw soldered at the midline in the 1st premolar area. RME device was delivered to the dogs and the activation of 0.25 mm per quarter-turn was done 2 times per day for 10 days until 5 mm separation was made. Separation of the maxilla was confirmed by X-ray. The animals were sacrificed on 0, 15, 30, 60 days from the finish of maxillary separation and preparations for light microscopy and surface electron microscopy were made. The sutures were cut into frontal serial sections for examination of the histological reactions. The following results were obtained and the conclusions made. 1. The edges of the two palatal plates bordering the midpalatal suture which at the beginning of the retention period were mainly composed of compact bone, underwent extensive resorption followed by new bone formation and gradually became spongy bone rich in bone marrow which in the 60 day retention animal became the compact bone with short intermaxillary suture space. During this transformation, newly formed trabecular bone tissues were added to the original margin. 2. Throughout the expansion period, the collagen fibers underwent successive changes such as stretching, loss of polarity, and finally fibrillogenesis. Towards the end of the expansion procedure, sharpey's fiber formation in newly formed bones were observed. 3. Bony spicules were found in the initial stage of retention on occlusal topographic X-rays, which later were confirmed to have ossified. 4. Judging from the histological changes occuring during the experimental expansion, excessive expansion will cause an excessive bleeding, and retard the remodeling of intermaxillary suture. According to the above results, the bone remodeling after rapid maxillary expansion was preceded by the migration of migratory cells into the intermaxillary suture area. The bone remodeling phenomena were on-going during the 2 months retention sample.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.391-399
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• 1997

Rapid palatal expansion(RPE) is a method of inducing the new bone formation in the palate by separation of the midpalatal suture, which can be done conveniently by placing heavy force across the maxillary dental arch. This experiment was undertaken to examine the histologic changes after RPE and during retention period. Four young adult dogs(a control dog, three experimental dogs) aged 4 to 6 months old were used for this experiment. Expansion screw($Hyrax^{\circledR}$, Dentarum Inc.) was delevered to the palate and fumed 180 degrees every morning and evening for 8 days, giving a total expansion of 7.2mm. A control dog was sacrified at the starting point of this study without any treatment and three experimental dogs were sacrified after RPE, 14-day retention, and 28-day retention in each. Thereafter, those samples were observed with hematoxylin-eosin(H-E) stain, ground section(Villanueva stain), alkaline phosphatase(ALP) stain, tartrate-resistant acid phosphatase(TRA) stain. The results were as followings: 1. After RPE, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts were flattened-inactive state and also, a little osteoid tissues was observed. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 2. After 14-day retention, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts which had ALP-positive activity in their cytoplasm were seen. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 3. After 28-day retention, collagen fiber bundles were arranged like those of control dog and osteoblasts which showed a lot of immature bone formation were cuboidal shape and exhibited ALP-positive activity in their cytoplasm. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. According to the above results, the new bone formation after rapid palatal expansion was examined after 14-day retention and significantly increased after 28-day retention.

• The korean journal of orthodontics
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• v.30 no.5 s.82
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• pp.553-563
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• 2000

Horseshoe Expander is one of Slow Maxillary Expansion(SME) which aims to accommodate the contra- lateral expansion and midpalatal suture expansion or the palate. The appliance consists of skeleton type strew embedded in split Horseshoe appliance. It is the objectives of the presentation to manifest the changes in dental & craniofacial components subsequent to the application of Horseshoe Expander. The subjects for this study consisted of 32 patients (mean age : 12.7). frontal, lateral cephalometric headfilm were taken and study casts were fabricated before and after expansion. 24 items were measured, compared preexpansion with postexpansion. Especially, palatal volume was measured by means of 'Hydro-measurement method'. Tooth axis measurement on the dental casts were made with Universal bevel protractor, and Horseshoe Expander group were compared with RME group. This study of changes to maxillary expansion with Horseshoe Expander revealed the following significant results. 1. Triangular-shaped expansion pattern appeared in frontal cephalometric headfilm. 2. Palatal plane, occlusal plane, mandibular plane and upper incisor to FH increased in lateral cephalometrir headfilm. 3. Palatal volume increased significantly. A slight bite opening, reduction of occlusal contact points showed in dental casts. 4. A 2.2:1 ratio of the amount of intermolar width in maxilla(orthodontic movement) to maxillary width (orthopedic movement) was determined. 5. Horseshoe Expander group has less buccal tipping tendency than RME group, by taking high correlation coefficients in the upper second premolar and first molar. It was suggested that Horseshoe Expander showed less orthodontic changes, less buccal tipping tendency. In addition, it was effective in maxillary expansion.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.402-413
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• 2022

The aim of this study was to identify factors that affect the treatment duration and to predict the duration of forced eruption in impacted maxillary canines using panoramic radiographs and cone-beam computed tomography. This retrospective study was performed by reviewing medical records and radiographs of 73 patients (93 impacted maxillary canines) from the age of 8 to 18 years who were treated with surgical and orthodontic interventions on impacted maxillary canines from January 2012 to December 2020 in Ajou University Dental Hospital. Stepwise multiple regression analysis showed that the distance between the canine cusp tip and the occlusal plane, mesio-distal location, bucco-palatal location, patient's age, and use of rapid palatal expansion are significant factors with regard to the duration of forced eruption. There was a statistically significant correlation of the treatment duration with the angulation between the axis of the canine and the occlusal plane and unilateral or bilateral impaction. It can be concluded that the duration of forced eruption in impacted maxillary canines could be shorter when the impacted canine is closer to the occlusal plane and located in the lateral incisor or canine area, buccal or middle, the patient is younger and uses rapid palatal expansion.

• Korean Journal of Cleft Lip And Palate
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• v.15 no.2
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• pp.51-60
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• 2012

Craniofacial sutures absorb the stress transferred to skull. It was reported the cells of craniofacial sutures respond to exogenetic factors to be involved in growth control mechanism. In this study, we constructed a finite element model composed of cortical bone, cancellous bone, suture, PDL, and teeth by using CT images of a growing patient, simulating maxillary expansion to evaluate the effects of the thickness of sutures and type of maxillary expansion appliance on stress distribution in circummaxillary sutures.

• The korean journal of orthodontics
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• v.39 no.4
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• pp.257-272
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• 2009

This case report describes the treatment of an adult patient with a Class I canine and molar relationship but a convex profile with a retrognathic mandible and marked lip protrusion, as well as an excessive lower anterior facial height and reduced transverse width on both arches due to a nasal airway obstruction. The constricted arches were expanded by surgically-assisted rapid palatal expansion and the application of a Schwarz appliance to the maxilla and mandible. Acceptable facial balance was obtained using contemporary directional force technology with microimplant anchorage (MIA), which provided horizontal and vertical anchorage in the maxillary and mandibular posterior teeth, as well as intrusion and torque control in the maxillary anterior teeth, resulting in a favorable counterclockwise mandibular response. The total treatment period was 29 months and the results were acceptable for 13 months after debonding.