Hsin-Fu Chang

National Taiwan University, Taipei, Taipei, Taiwan

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Publications (5)5.01 Total impact

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    ABSTRACT: The intrusion of an overerupted maxillary molar using traditional orthodontic treatment is a real challenge. The aim of this study was to investigate the envelope of intrusive movements of a maxillary molar in cases using mini-implants as anchorage with partial or full-mouth fixed edgewise appliances. The cusp tips of the pretreatment and postintrusion dental casts were recorded by a three-dimensional (3D) digitizer. The 3D data of the serial dental casts were analyzed to distinguish the direction and magnitude of individual tooth movement. The mean intrusive movement of the maxillary first molars was three to four mm, with a maximum of over eight mm. For the adjacent maxillary second molars and second premolars, the amount of intrusion was two mm and 1-2 mm, respectively. This study demonstrated that significant true intrusion of maxillary molars could be obtained in a well-controlled manner by using fixed appliances with titanium mini-implants as bony anchorage.
    The Angle Orthodontist 10/2005; 75(5):754-60. · 1.18 Impact Factor
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    ABSTRACT: Treatment modalities for Class II Division 2 malocclusion include growth modification, dental compensation, and surgical-orthodontic therapy; which treatment is chosen depends on the patient's age and growth potential. Deep overbite can be corrected by intrusion of anterior teeth, extrusion of posterior teeth, or a combination of both. Treatment considerations include the patient's facial profile, skeletal pattern, growth potential, and severity of dental malocclusion. Here, we present the nonsurgical orthodontic treatment of an adult patient with deep overbite and underlying skeletal Class II discrepancy. He had a hypodivergent facial pattern, Class II Division 2 malocclusion, and traumatic deep overbite due to supereruption of the mandibular anterior teeth. He refused orthognathic surgery but would accept orthodontic treatment alone, with the understanding that the treatment results could be compromised. We corrected the deep overbite by proclining the mandibular incisors; this helped to level the exaggerated curve of Spee. The posttreatment occlusion was significantly improved, both functionally and esthetically, with stable interincisal contacts. However, the improvement in occlusion and esthetics was achieved at the expense of reduced periodontal support for the mandibular anterior teeth.
    American Journal of Orthodontics and Dentofacial Orthopedics 10/2004; 126(3):371-8. · 1.46 Impact Factor
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    ABSTRACT: The computer-assisted digital cephalometric analysis system (CADCAS) may reduce the time required for cephalometric analysis, especially for taking measurements. Aimed at estimating the time saved by using CADCAS, we measured the time needed by a clinician to perform the analysis in a traditional manner. We also sought to verify the accuracy achieved by traditional cephalometric analysis by exploring the disagreement between manual measurements and those generated by CADCAS. Our results revealed that, on average, even an experienced clinician needed more than 25 minutes to perform an entire cephalometric analysis using a traditional method, with more than 15 minutes of this needed just for taking measurements. Disagreements between measurements by traditional method and those by CADCAS were most frequently noted in the measurement value of cephalometric items reflecting the severity of a jaw discrepancy by the "sign" reflecting the anteroposterior relationship. After excluding the measurements with obvious error, the measurement differences between traditional method and CADCAS were not statistically significant in 23 of a total of 26 cephalometric items. In conclusion, the CADCAS can reduce the time needed for cephalometric analysis and can help reduce the human errors introduced during the manual-measuring procedure in the traditional cephalometric analysis.
    The Angle Orthodontist 09/2004; 74(4):501-7. · 1.18 Impact Factor
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    ABSTRACT: The aim of this study was to explore the effects of differences in landmark identification on the values of cephalometric measurements on digitized cephalograms in comparison with those obtained from original radiographs. Ten cephalometric radiographs were randomly selected from orthodontic patients' records. Seven orthodontic residents identified 19 cephalometric landmarks on the original radiographs and digitized images. Twenty-seven cephalometric measurements were computed with a customized computer-aided program. To assess the concordance between cephalometric measurements derived from landmarks identified on the original radiographs and those from digitized counterparts, the values of 27 cephalometric measurements were compared to quantify the absolute value of measurement difference and the interobserver errors between these two methods. We found that the differences of all cephalometric measurements between original radiographs and their digitized counterparts were statistically significant. The differences in 21 of the 27 cephalometric items were less than two units of measurement (mm or degree), which is generally within one standard deviation of norm values in conventional cephalometric analysis. Moreover, statistically significant differences of interobserver errors between the two methods were noted only for seven of the 27 cephalometric items. In conclusion, the measurement differences between the original cephalograms and the digitized images are statistically significant but clinically acceptable. The interobserver errors for cephalometric measurements on our digitized cephalometric images are generally comparable with those on the original radiographs. The results of our study substantiated the benefits of digital cephalometry in terms of the reliability of cephalometric analysis.
    The Angle Orthodontist 05/2004; 74(2):155-61. · 1.18 Impact Factor
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    ABSTRACT: Treatment modalities for Class II Division 2 malocclusion include growth modification, dental compensation, and surgical-orthodontic therapy; which treatment is chosen depends on the patient's age and growth potential. Deep overbite can be corrected by intrusion of anterior teeth, extrusion of posterior teeth, or a combination of both. Treatment considerations include the patient's facial profile, skeletal pattern, growth potential, and severity of dental malocclusion. Here, we present the nonsurgical orthodontic treatment of an adult patient with deep overbite and underlying skeletal Class II discrepancy. He had a hypodivergent facial pattern, Class II Division 2 malocclusion, and traumatic deep overbite due to supereruption of the mandibular anterior teeth. He refused orthognathic surgery but would accept orthodontic treatment alone, with the understanding that the treatment results could be compromised. We corrected the deep overbite by proclining the mandibular incisors; this helped to level the exaggerated curve of Spee. The posttreatment occlusion was significantly improved, both functionally and esthetically, with stable interincisal contacts. However, the improvement in occlusion and esthetics was achieved at the expense of reduced periodontal support for the mandibular anterior teeth.
    American Journal of Orthodontics and Dentofacial Orthopedics. 01/2004;