Biomedical subjects

Ellen Wen-Ching Ko

Publications and source records attributed to Ellen Wen-Ching Ko.

5 recordsLinked to original sources

PubMed2006

The inter-relationship between mandibular autorotation and maxillary LeFort I impaction osteotomies.

The purposes of the present investigation were to: 1)locate the instantaneous rotation center of mandible autorotation during maxillary surgical impaction; 2) identify the discrepancies between the resultant mandibular position following by maxillary surgical impaction and presurgical predictions, which use the radiographic condylar center as the rotation center for mandibular autorotation; and 3)find the interrelation between the magnitude of maxillary surgical impaction and the sagittal change of mandible. Ten patients underwent maxillary LeFort I impaction without concomitant major mandibular ramus split osteotomies were included. The preoperative (T0) and postoperative (T1) lateral cephalograms were used to evaluate the surgical changes and locate the center of rotation of mandibular autorotation with Reuleaux method. Prediction errors were measured by comparing the predicted (Tp) and postoperative (T1) cephalometric tracings. The magnitude of the maxillary surgical impaction was compared to the positional changes of mandible after mandibular autorotation with correlation and regression analysis. The results demonstrated that the centers of mandibular autorotation located 2.5 mm behind and 19.6 mm below the radiographic condylar center of the mandible in average with large individual variations. By using the radiographic condylar center of the mandible to predict the mandibular autorotation would overestimate the horizontal position of chin by 2 mm and underestimate the vertical position of chin by 1.3 mm following an average of 5 mm surgical maxillary impaction. The magnitude of maxillary impaction was highly and positively correlated to the horizontal displacement of chin position. The rotation centers of mandibular autorotation following by maxillary LeFort I impaction osteotomies might not usually locate at the radiographic condylar center of the mandible also with large individual variations in their positions. Surgeons and orthodontists should be aware of the horizontal and vertical discrepancies of chin positions while planning a two-jaw surgery by using the radiographic center of mandibular condyle as the rotation center in mandibular autorotation.

Adolescent↗

PubMed2005

Symmetry of the nose after presurgical nasoalveolar molding in infants with unilateral cleft lip and palate: a preliminary study.

OBJECTIVE: To assess nostril symmetry and alveolar cleft width in infants with unilateral cleft lip and palate following presurgical nasoalveolar molding (NAM). SAMPLE AND METHODS: Fifty-seven newborn patients underwent presurgical nasoalveolar molding. Magnified basal view facial photos were taken at four different times: initial visit (T1), before cheiloplasty (T2), 1 month after cheiloplasty (T3), and 1 year of age (T4). Direct measurements from the photos included: (1) nostril width on the affected and nonaffected side; (2) nostril height on the affected and nonaffected side; (3) columella-nasal base angle; and (4) width of the alveolar cleft. Nostril width and height data were used to calculate a ratio of affected to nonaffected side. RESULTS: Effects of nasal symmetry after presurgical nasoalveolar molding were compared between the affected and nonaffected side. The nostril width ratio was 1.7, 1.2, 1.0, and 1.2 for T1 to T4. The nostril height ratio was 0.5, 0.8, 1.0, and 0.9 for T1 to T4. The angle of the columella was 53.3 degrees , 69.9 degrees , 91.2 degrees , and 86.9 degrees for T1 to T4. The average alveolar cleft width was 8.2 mm at T1 and closed down to 2.4 mm before cheiloplasty (T2) in cases with complete cleft. CONCLUSIONS: Infants with presurgical nasoalveolar molding improved symmetry of the nose in width, height, and columella angle, as compared to their presurgical status. There was some relapse of nostril shape in width (10%), height (20%), and angle of columella (4.7%) at 1 year of age.

Alveolar Process↗

PubMed2005

Cephalometric craniofacial characteristics in patients with temporomandibular joint ankylosis.

BACKGROUND: The sequelae of temporomanibular joint (TMJ) ankylosis include limitation of jaw movement, interference of oral function and affects on the craniofacial growth. Analysis of the craniofacial form of TMJ ankylosis offers guidelines for managing this disease. METHODS: Forty-five patients with intraarticular TMJ ankylosis were collected from the files at the Chang Gung Craniofacial Center. There were 21 male and 24 female patients, aged 3 to 47 years. Thirty-seven patients were unilaterally affected and eight had bilateral involvement. Patients were grouped according to gender and age. Both the medical history and onset of the disease were investigated in all patients. The pretreatment lateral cephalograms were used for analysis. The variables were compared with the Chinese norms with corresponding sex and age groups. RESULTS: The etiology included 48.9% facial trauma history, 17.8% traumatic delivery or birth injury, 15.6% middle ear or dental infection, 2.2% chronic arthritis and 15.6% unknown causes. The onset of mouth opening limitation was under 16 years of age. The average total mandibular length was less than the norm by 30 mm. Each patient presented with a mandible that had backward rotation with chin recession. Accentuated antegonial notch and inferiorly located condyle were observed on the affected side. The maxilla was shorter and the ANB was larger than the norm by 10 degrees but the overbite and overjet were within normal ranges. CONCLUSIONS: The facial growth was severely disturbed in terms of dimension, morphology and direction of growth in patients with TMJ ankylosis. Better management of mandibular fractures, good infection control and early treatment intervention are ways to reduce the influence on craniofacial growth.

Adolescent↗

PubMed2003

The accuracy of video imaging prediction in soft tissue outcome after bimaxillary orthognathic surgery.

PURPOSE: The purpose of the present study was to evaluate the accuracy of the outcome in soft tissue prediction through use of a computer imaging system after bimaxillary orthognathic surgery. MATERIALS AND METHODS: The study sample consisted of 30 adults who had undergone orthognathic surgery that included the Wassmund and Köle procedures and optional genioplasty to correct bimaxillary protrusion. All the patients had lateral cephalometric radiographs and profile photographs taken within 6 months before surgery and at least 6 months after surgery. The computer-generated soft tissue image and the actual postsurgical profile were compared. The accuracy of this computer-generated profile image was evaluated. RESULTS: The results indicated that the nasal tip, soft tissue A point, and upper lip presented the least predicted errors in sagittal plane. While the nasal tip presented higher reliability. Lower lip prediction was found to be the least accurate region and it tended to be located anterior to the actual position. In the vertical plane, most of the predictions revealed higher accuracy than those in the sagittal plane. There were no statistically significant differences between the predictions of the groups with and those without genioplasty. CONCLUSIONS: Computer-generated image prediction was suitable for patient education and communication. However, efforts are still needed to improve the accuracy and reliability of the prediction program and to include the consideration of changes in soft tissue tension and muscle strain. The accuracy of this system in soft tissue prediction should be carefully interpreted.

Adult↗

PubMed2003

Palatal surface area measurement: comparisons among different cleft types.

The purpose of this study was to use three-dimensional imaging methods to measure the palatal surface of unrepaired cleft patients. The surface area of the palate was defined and measured on three-dimensional computed tomography images of dental plaster models in four different groups of cleft patients at 3 months of age. There were 30 unilateral complete cleft lips and palates (UCLP), 27 bilateral complete cleft lips and palates (BCLP), 23 isolated cleft palates of incomplete form (CP), and 19 unilateral cleft lips without cleft palates (UCL). These patients were nonsyndromic, unoperated, and without other major deformities. The dental casts were scanned, and the computed tomography data were transferred to an imaging laboratory for processing and reconstruction of three-dimensional images. Surface area of the palate was delineated, which was defined as within the alveolar crest and the line connecting both tuberosities. In UCLP and BCLP, the edge of cleft formed the medial boundary of the area for each palatal shelf, and the palatal surface area was the combination of both palatal shelves and the premaxillary area in BCLP group. The surface area was measured. Repeated definition and measurement tasks were performed for calculation of errors. The imaging data management and measurement were performed using the Analyze program (Biomedical Imaging Resource, Mayo Foundation, MN). In addition, linear distances were measured between the canine points on the alveolar crest (line C) and the tuberosity points (line T). The measurements were compared among the different groups. Analysis of variance and multiple comparisons were used for statistical analyses. The results showed that the mean error between repeated area definitions and measurements in this study was 1.86%. The bilateral complete cleft lip and palate (BCLP) and unilateral complete cleft lip and palate (UCLP) groups had significantly smaller palatal surface area than the unilateral cleft lip without cleft palate (UCL) and isolated cleft palate of incomplete form (CP) groups. There was no significant difference between the BCLP and UCLP groups. Line C and line T distances were significantly longer in BCLP and UCLP groups than in UCL and CP groups. The findings suggest that compared with UCL and CP patients, there is an intrinsic tissue deficiency in the palate/maxilla of BCLP and UCLP patients.

Cleft Lip↗