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ABSTRACT: OBJECTIVES: The three-dimensional (3D) asymmetric structure of the mandible makes it necessary to analyze both its size and angle. Currently the developing 3D analysis techniques are not able to perform the simultaneous linear and angular measurements. Our aim was to evaluate mandibular asymmetry using a vector-based system by constructing 3D vectors for the mandibular functional units. MATERIAL AND METHODS: We analyzed the 3D computed tomography images of normal control (N = 27) and asymmetric mandibles (N = 40). We created 3D vectors for the condylar, coronoid, body, gonial, and symphyseal functional units and compared the corresponding pairs of 3D vectors by calculating vector operations. RESULTS: The vector difference and other vector components represented the individual 3D architectural pattern and severity of the asymmetric mandible. The body unit contributed most to mandibular asymmetry followed by the condylar unit. CONCLUSIONS: The results indicate that 3D vector analysis can improve our understanding of the 3D architecture of asymmetric mandibles. This type of 3D vector analysis can be a useful tool for the comprehensive evaluation of its asymmetric mandibular structure.
Journal of cranio-maxillo-facial surgery: official publication of the European Association for Cranio-Maxillo-Facial Surgery 01/2013; · 1.25 Impact Factor
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ABSTRACT: The aim of this study was to present our clinical experience regarding the production and accuracy of digitally printed wafers for maxillary movement during the bimaxillary orthognathic surgery.
Fifty-five consecutive patients requiring maxillary orthognathic surgery were included in this study. The plan for digital model surgery (DMS) was dictated by the surgical plans for each clinical case. We carried out digital model mounting, DMS, wafer printing, and confirmation of the accuracy of the procedure.
Moving the reference points to the target position in DMS involved a mean error of 0.00-0.09 mm. The mean errors confirmed by the model remounting procedure with the printed wafer by DMS were 0.18-0.40 mm (for successful cases; n = 42) and 0.03-1.04 mm (for poor cases; n = 3).
The accuracies of the wafers by DMS were similar to those for wafers produced by manual model surgery, although they were less accurate than those produced by DMS alone. The rapid-prototyped interocclusal wafer produced with the aid of DMS can be an alternative procedure for maxillary orthognathic surgery.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 03/2011; 111(3):278-85.e1. · 1.50 Impact Factor
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ABSTRACT: INTRODUCTION: Anterior open bite results from the combined influences of skeletal, dental, functional, and habitual factors. The long-term stability of anterior open bite corrected with absolute anchorage has not been thoroughly investigated. The purpose of this study was to examine the long-term stability of anterior open-bite correction with intrusion of the maxillary posterior teeth. METHODS: Nine adults with anterior open bite were treated by intrusion of the maxillary posterior teeth. Lateral cephalographs were taken immediately before and after treatment, 1 year posttreatment, and 3 years posttreatment to evaluate the postintrusion stability of the maxillary posterior teeth. RESULTS: On average, the maxillary first molars were intruded by 2.39 mm (P <0.01) during treatment and erupted by 0.45 mm (P <0.05) at the 3-year follow-up, for a relapse rate of 22.88%. Eighty percent of the total relapse of the intruded maxillary first molars occurred during the first year of retention. Incisal overbite increased by a mean of 5.56 mm (P <0.001) during treatment and decreased by a mean of 1.20 mm (P <0.05) by the end of the 3-year follow-up period, for a relapse rate of 17.00%. Incisal overbite significantly relapsed during the first year of retention (P <0.05) but did not exhibit significant recurrence between the 1-year and 3-year follow-ups. CONCLUSIONS: Most relapse occurred during the first year of retention. Thus, it is reasonable to conclude that the application of an appropriate retention method during this period clearly enhances the long-term stability of the treatment.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 10/2010; 138(4):396-8. · 1.33 Impact Factor
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ABSTRACT: Neurologic changes owing to damage to the inferior alveolar nerve (IAN) are the most serious complication of lower third molar (M3) extraction because of their close spatial relationship. We adopted the concept of regional orthodontic treatment and extrusion, using skeletal anchorage with an orthodontic mini implant. Two malformed M3s that were closely apposed to the IAN were extruded with the aid of 3 or 4 orthodontic brackets and a mini implant. Both of the M3s were extruded successfully. The patients experienced little discomfort with the orthodontic appliances and there was neither permanent neurologic damage nor fracture of the root fragments following subsequent M3 extraction. Orthodontic treatment using a miniscrew to separate the IAN and M3, or luxation of the M3 may be a good alternative treatment option for extrusion of a vertically impacted lower M3 with fragile roots.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 10/2010; 110(4):e1-6. · 1.50 Impact Factor
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ABSTRACT: Anterior open bite results from the combined influences of skeletal, dental, functional, and habitual factors. The long-term stability of anterior open bite corrected with absolute anchorage has not been thoroughly investigated. The purpose of this study was to examine the long-term stability of anterior open-bite correction with intrusion of the maxillary posterior teeth.
Nine adults with anterior open bite were treated by intrusion of the maxillary posterior teeth. Lateral cephalographs were taken immediately before and after treatment, 1 year posttreatment, and 3 years posttreatment to evaluate the postintrusion stability of the maxillary posterior teeth.
On average, the maxillary first molars were intruded by 2.39 mm (P<0.01) during treatment and erupted by 0.45 mm (P<0.05) at the 3-year follow-up, for a relapse rate of 22.88%. Eighty percent of the total relapse of the intruded maxillary first molars occurred during the first year of retention. Incisal overbite increased by a mean of 5.56 mm (P<0.001) during treatment and decreased by a mean of 1.20 mm (P<0.05) by the end of the 3-year follow-up period, for a relapse rate of 17.00%. Incisal overbite significantly relapsed during the first year of retention (P<0.05) but did not exhibit significant recurrence between the 1-year and 3-year follow-ups.
Most relapse occurred during the first year of retention. Thus, it is reasonable to conclude that the application of an appropriate retention method during this period clearly enhances the long-term stability of the treatment.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 10/2010; 138(4):396.e1-9; discussion 396-8. · 1.33 Impact Factor
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ABSTRACT: The 3D architecture of the mandible contributes to the functional and morphological characteristics of the lower one third of craniofacial region. The mandible has six distinct functional units, and its architecture is the sum of balanced growth of each functional unit and surrounding matrix. A dentofacial deformity (DFD) with malocclusion can be interpreted as their unbalanced growth. In order to characterize the mandibular 3D architecture, we analyzed the 3D reconstructed computed tomography (CT) images in terms of functional units. We evaluated both sides of 30 datasets of 3D CT scans of normal controls (N = 6) and patients with prognathic (N = 17) or retrognathic (N = 7) mandibles. We first identified and evaluated reference points to define mandibular functional units and compared their linear and angular measurements of DFD with normal group. The condylar and body length, the ratio of condyle/coronoid length, and the condylar head axis angle showed the statistically significant differences between groups. From these results, we could define the 3D reference points for functional units and identify the 3D architectural characteristics of DFD mandibles. These models may help us improve diagnosis and treatment planning to let them return to the normal and balanced architecture for DFD.
Clinical Oral Investigations 10/2009; 14(6):691-8. · 2.36 Impact Factor
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ABSTRACT: Ankylosis of a tooth is a pathologic condition commonly manifested by infraocclusion and vertical alveolar bone defect of the involved tooth. Extraction is often indicated in patients with severe tipping of adjacent teeth and serious infraocclusion, rather than attempting orthodontic repositioning. However, the residual alveolar bone defect after extraction must be restored adequately to establish sound dentition with a healthy periodontium. The bone-forming potential of sound periodontal ligament cells of the adjacent teeth can be used to restore the bone defect, through precisely controlled mesial movement of the root of the tilted molar. In this case report, a successful mesial root movement of the mandibular second molar is shown by the combined use of a conventional uprighting spring and orthodontic miniscrew implants in the mandibular premolar area. Adequate occlusion and periodontal health were restored in a 15-year-old girl with the typical sequela of an ankylosed molar.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 10/2009; 136(3):440-9. · 1.33 Impact Factor
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ABSTRACT: When monocortical orthodontic miniscrews are placed in interdental alveolar bone, the safe position of the miniscrew tip should be ensured. This study was designed to quantify the periradicular space in the tooth-bearing area to provide practical guidelines for miniscrew placement.
Computerized tomographs of 30 maxillae and mandibles were taken from nonorthodontic adults with normal occlusion. Both mesiodistal interradicular distance and bone thickness over the narrowest interradicular space (safety depth) were measured at 2, 4, 6, and 8 mm from the cementoenamel junction.
Mesiodistal space greater than 3 mm was available at the 8-mm level in the maxillary anterior region, between the premolars, and between the second premolar and the first molar at 4 mm. In the mandible, sufficient mesiodistal space was found between the premolars, between the molars, and between the second premolar and the first molar at the 4-mm level. Safety depth greater than 4 mm was found in the maxillary and mandibular intermolar regions, and between the second premolar and the first molar in both arches.
Subapical placement is advocated in the anterior segment. Premolar areas appear reliable in both arches. Angulated placement in the intermolar area is suggested to use the sufficient safety depth in this area.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 05/2009; 135(4):486-94. · 1.33 Impact Factor
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Journal of clinical orthodontics: JCO 09/2006; 40(8):472-6.
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ABSTRACT: Three-dimensional (3D) analysis is essential for making a precise diagnosis of craniofacial morphology. Two-dimensional (2D) x-ray films are used to understand 3D structures. However, 2D images have several limitations. This article proposes a new type of cephalometric analysis by using 3D computed tomography.
Axial images of 30 subjects (16 men; mean age, 19.2 years; 14 women, mean age, 20.5 years) were reconstructed into 3D models by using Vworks 4.0 (Cybermed, Seoul, Korea). The 3D models were measured with Vsurgery (Cybermed). The zygoma, maxilla, mandible, and facial convexity were analyzed.
The measurements were compared with Korean normal averages, and no statistically significant differences were found. Landmark identification was reproducible.
Three-dimensional computed tomography can provide information for use in diagnosis and treatment planning.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 06/2006; 129(5):600.e23-34. · 1.33 Impact Factor
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ABSTRACT: The purpose of this study was to evaluate the effects of a light continuous force and an interrupted force with weekly reactivation on interleukin-1beta (IL-1beta) and prostaglandin E(2) (PGE(2)); possible interactions between these 2 potent mediators of the bone resorption process were assessed in vivo. Ten healthy young adults (mean age 20.6 years, 2 men, 8 women) with 4 premolars extracted were assessed. In each subject, 1 maxillary canine (E1) received continuous force with a nickel-titanium coil spring. The opposite canine (E2) received an interrupted force with a screw-attached retractor; the force was reactivated weekly by 2 turns of the screw. An antagonistic canine was used as a control. Gingival crevicular fluid was collected from the distal side of each tooth, 10 times in 3 weeks, and IL-1beta and PGE(2) levels were measured. For E1, the IL-1beta level showed a significant elevation at 24 hours and then decreased and maintained an insignificant but high mean concentration, compared with the control site. The PGE(2) level showed a significant elevation at 24 hours and then decreased. For E2, a significant elevation of IL-1beta level was observed at 24 hours and a greater significant elevation at 24 hours after the first reactivation, compared with the control sites. The PGE(2) level increased significantly at 24 hours and remained high for 1 week. The synergistic up-regulation of PGE(2) by appliance reactivation and secreted IL-1beta was not evident with either type of force after 1 week. Both experimental sites showed significant tooth movement compared with the control sites at 3 weeks; however, there was no significant difference between the 2 experimental sites. A well-controlled mechanical stress with timely reactivation can effectively upregulate IL-1beta secretion, but there might be limitations in increasing the mediator levels, because of the feedback mechanisms in vivo. In addition, the analysis of crevicular fluid is a useful method for assessing cellular response to orthodontic force in vivo.
American Journal of Orthodontics and Dentofacial Orthopedics 03/2004; 125(2):168-77. · 1.38 Impact Factor
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ABSTRACT: Because adults dislike the visibility of orthodontic appliances, the use of the lingual orthodontic technique has increased over time. But few studies compare tooth movement of the lingual technique with that of the labial technique. In this study, human mandibular left teeth were aligned, and a 3-dimensional finite element model was made (consisting of 19382 nodes and 12150 elements). To compare the effect of compensating curves on canine retraction between the lingual and the labial orthodontic techniques, the compensating curve was increased on the.016-in stainless steel labial or lingual archwire, and a 150-g force was applied distally on the canine. The relative direction and the amount of tooth displacement of the finite element model were compared on a schematic displacement graph (magnified 10,000 times), and the compressive stress distributed on the root surface was observed. The pattern of tooth movement (with or without a compensating curve) was different between the labial and the lingual techniques. As the amount of compensating curve increased (0, 2, and 4 mm) in the archwire, the rotation and the distal tipping of the canine was reduced. The antitip and antirotation action of compensating curve on the canine retraction was greater in the labial archwire than in the lingual archwire.
American Journal of Orthodontics and Dentofacial Orthopedics 05/2003; 123(4):441-50. · 1.38 Impact Factor
