Biomedical subjects

James Xia

Publications and source records attributed to James Xia.

4 recordsLinked to original sources

PubMed2003

The precision of computer-generated surgical splints.

PURPOSE: The purpose of this study was to assess the precision of stereolithographic surgical splints generated by the authors' computer-aided design and manufacturing (CAD/CAM) technique by comparing them with the conventional acrylic splints. MATERIALS AND METHODS: Seven volunteers were used. A pair of surgical splints, stereolithographic and conventional acrylic splints, was fabricated for each subject. A novel method was developed to quantify the airspace between the teeth and the splint. Conventional acrylic surgical splints served as a control group. The airspaces were recorded by impression materials and sliced cross-sectionally. Corresponding areas of the cross-sectional airspaces between stereolithographic and acrylic splints were measured and compared. Pearson's correlation coefficient and linear regression tests were performed. RESULTS: Seven pairs of surgical splints were created. The areas of 98 pairs of cross-sectional airspaces were measured. The average difference between the conventional and the STL splints was 0.24 +/- 0.23 mm(2). The correlation coefficient (r) of the airspace areas between the stereolithographic and conventional acrylic splints was 1.00, and the regression coefficient (beta) was 1.03 (P <.01). CONCLUSIONS: The results indicated that the stereolithographic splints, generated by the authors' CAD/CAM technique, had a high degree of accuracy. The fit of the STL splints was the same as the conventional surgical splints. In the future, traditional plaster dental model surgery will be replaced by computer-assisted surgical planning. The surgical splints will be made in the computer and the treatment plan will be directly transferred to the patient.

Acrylic Resins↗

PubMed2003

A new technique for the creation of a computerized composite skull model.

PURPOSE: The goals of this study were to develop a technique for creating a computerized composite skull model and to test its accuracy. The computerized composite skull model is the combination of a 3-dimensional (3D) computed tomography (CT) bone model with digital dental models. MATERIALS AND METHODS: A dry skull with intact dentition was used in development of the technique. The creation of the computerized composite skull model was divided into 3 steps. The first step was to create digital dental models. The second step was to create a 3D CT bone model of the craniomaxillofacial skeleton. The last step was to incorporate the digital dental models into the 3D CT skull model, creating a computerized composite skull model. The accuracy of the computerized composite skull model was assessed. Bone-to-bone, tooth-to-tooth, and bone-to-tooth measurements were made on the computerized composite skull model and the dry skull. Pearson correlation coefficient and linear regression tests were performed. RESULTS: A technique to create a computerized composite skull model was developed. This computerized model not only represented bony structures from CT data but also reproduced dentition from digital dental models. For the bone-to-bone measurements, the mean difference between the computerized composite skull model and the dry skull was 0.5 +/- 0.6 mm. For the tooth-to-tooth measurements, the mean difference was 0.1 +/- 0.2 mm. For the bone-to-tooth measurements, the mean difference was 0.2 +/- 0.3 mm. CONCLUSIONS: This study showed the feasibility of creating a computerized composite skull model as well as its accuracy.

Cephalometry↗

PubMed2002

Deformational posterior plagiocephaly: diagnosis and treatment.

OBJECTIVE: This study was designed to evaluate the effectiveness of helmet therapy (DOC band) in the correction of patients with moderate to severe posterior deformational plagiocephaly. DESIGN: In this prospective study, the infants were evaluated using 18 anthropometric measurements. PATIENTS: The charts of 248 patients seen between August 1, 1995, and July 31, 1999, were reviewed, and 125 met the criteria for inclusion in the study. All the patients had posterior deformational plagiocephaly with no other craniofacial deformities or medical conditions. Treatment was instituted prior to 1 year of age, and all patients were compliant with DOC band usage and had complete anthropometric measurements. RESULTS: The study recorded a 41.56% (p < .001) reduction in cranial vault asymmetry and a 40.23% (p <.001) reduction in cranial base asymmetry. Orbitotragial asymmetry was improved 18.72% (p = .0738). The age at which treatment was begun was not a significant factor in predicting treatment outcomes.

Age Factors↗

PubMed2002

Cephalometric study of the upper airway in surgically corrected class III skeletal deformity.

Changes in the upper airway after surgical correction of Class III skeletal dentofacial deformity were investigated by measurement of the cephalometric radiographs of 70 Class III subjects before surgery and 6 months after surgery. Comparison of the results with those of a normal group of 74 subjects without deformity or surgery was also carried out. Gender dimorphism in measurements and type of surgery performed were taken into account. Results showed that postoperatively the soft palate and hyoid bone were posteriorly displaced in men, the oropharyngeal, hypopharyngeal, and minimal airway depth were reduced, but in women, the minimal depth was not reduced. In the mandibular setback group, men showed posterior movement of the tongue base, with decrease in minimal airway depth. In the maxillary advancement group, nasopharyngeal depth increased in both genders. In the bimaxillary surgery group, the soft palate moved posteriorly and the tongue occupied a larger proportion of the airway in both genders. The hyoid was displaced backwards in women, while men showed a decrease in both oropharyngeal and minimal airway depth. In comparison with normal subjects, postoperative measurements indicated that the soft palate was reduced in length, thickness, and area, and the base of the tongue was more posterior. Minimal pharyngeal depth was reduced in both genders. After mandibular setback, the tongue base was more posterior and the hypopharyngeal depth was reduced. The bimaxillary surgery group also demonstrated a more posterior tongue base but without reduction of the hypopharyngeal depth. The mandibular setback group should be most at risk of obstructive sleep apnea, but compensatory changes in soft palate morphology may explain the low occurrence in practice.

Adolescent↗