Biomedical subjects

Xianglong Zeng

Publications and source records attributed to Xianglong Zeng.

5 recordsLinked to original sources

PubMed2007

Microscrew anchorage in skeletal anterior open-bite treatment.

OBJECTIVE: To evaluate the effectiveness of miniscrew anchorage for intrusion of the posterior dentoalveolar region to correct skeletal open bite. MATERIALS AND METHODS: The study was comprised of 12 patients (aged 14.3 to 27.2 years; mean 18.7 years) with anterior open bites. All the patients presented a Class II skeletal pattern and excessive posterior growth. Self-drilling miniscrew implants were inserted into the posterior midpalatal area and the buccal alveolar bone between the lower molars. A transpalatal and a lingual arch were used to maintain the molars on each side in order to avoid overrotation during intrusion. A force of 150 g was applied to the microscrews on each side to intrude the posterior teeth. Lateral cephalograms of all 12 patients were taken preintrusion and immediately after completion of the intrusion. The cephalometric films were measured and compared. RESULTS: The results showed that the anterior open bites in 12 patients were all corrected in a mean of 6.8 months. Overbite increased by a mean of 4.2 mm (P < .001), from -2.2 mm in preintrusion to 2.0 mm in postintrusion. The maxillary and mandibular first molars were intruded for an average of 1.8 mm (P < .001) and 1.2 mm (P < .001), respectively. The mandibular plane angle was reduced by 2.3 degrees (P < .001), which led to a counterclockwise rotation of the mandible with a significant decrease in the anterior facial heights (mean of 1.8 mm; P < .001). CONCLUSION: Miniscrew anchorage has the advantages of being a simpler procedure, being minimally invasive, and requiring minimal patient cooperation.

Adolescent↗

PubMed2005

Root resorption after orthodontic intrusion and extrusion: an intraindividual study.

The aim of this investigation was to compare root resorption in the same individual after application of continuous intrusive and extrusive forces. In nine patients (mean age 15.3 years), the maxillary first premolars were randomly intruded or extruded with a continuous force of 100 cN for eight weeks. Eleven maxillary first premolars from six randomly selected orthodontic patients served as controls. Root resorption was determined using scanning electron microscopy. Quantitative assessment of the percentage of resorbed area of the total root surface was performed on composite micrographs. The severity of root resorption was also assessed by visual scoring of the roots. Root resorption mainly occurred at the apical part of the roots in both experimental groups. A significant difference in root resorption was found between the intruded and the control teeth (P = .006) but not between the extruded and the control teeth. However, the mesial and distal root surfaces showed resorption on 5.78 +/- 3.86% of the root surface of the intruded teeth and 1.28 +/- 1.24% of the root surface of the extruded teeth, and this difference was significant (P = .004). In addition, a large individual variation was found. From this study, it can be concluded that intrusion of teeth causes about four times more root resorption than extrusion. Because the amount of root resorption due to intrusion or extrusion in the same patient is correlated, every clinician should be aware that the extrusion of teeth might also cause root resorption in susceptible patients.

Adolescent↗

PubMed2003

[Changes of upper airway morphology induced by mandibular advancement in patients with obstructive sleep apnea syndrome].

OBJECTIVE: To determine the changes of upper airway morphology induced by mandible position from central relation to advancement position in patients with obstructive sleep apnea syndrome. METHODS: Nineteen patients (17 males and 2 females) suffering from obstructive sleep apnea syndrome were confirmed with polysomnography. Occlusal wax record was made with mandible in advancement position. Helical computed tomography was performed on each patient in central relation and mandibular advancement position with wax record in situ respectively. On each slice, anteroposterior and transverse diameters were obtained. Airway shape was expressed as the anteroposterior/transverse (AP/T) diameter ratio. Paired-samples t test was employed to compare the measurements. RESULTS: With mandibular advancement, average and minimal diameters of glossopharynx and hypopharynx were increased significantly. Compared with it, the change of transverse diameter was more prominent. All segments of upper airway were increased significantly except hypopharynx laterally. Moreover, the change of velopharynx shape was observed on axial planes. Ellipse with transversal long axis became more compressed. CONCLUSION: Upper airway morphology of all segments was influenced by mandibular advancement whether in the sagittal or transverse plane of space, or airway shape. Not only anatomic connection but also regulation of the nerve system and other still unknown mechanism make contribution to the changes of upper airway morphology in patients with obstructive sleep apnea syndrome. The changes of upper airway morphology above mentioned constitute the rationale of treatment of obstructive sleep apnea syndrome with oral appliances.

Adult↗

PubMed2002

A study on the difference of craniofacial morphology between oral and nasal breathing children.

OBJECTIVE: The purpose of this study was to compare the difference of craniofacial morphology between oral and nasal breathing children, and discover the relationship between respiratory mode and craniofacial morphology. METHODS: Using the system for the simultaneous measurement of oral and nasal respiration, 34 oral breathing children and 34 nasal breathing children aged from 11 to 14 years were selected. RESULTS: Compared with the nasal-breathing children, the oral-breathing children showed apparently vertical growth pattern. The mandibuler plane Angle of oral breathing children is 39.3, which is significant greater than that of nasal breathing children (P < 0.01). The jans, the oral-breathing children had shorter mandibular body, larger gonion angle, retrusive chin and face (P < 0.05). On the other hand, in the sagittal direction, the oral breathing children may display all kinds of skeletal facial types. There is no significant difference between the two groups. CONCLUSIONS: Oral breathing is one of the factors related to the vertical over-development.

Adolescent↗

PubMed2002

[Anterior open bite: surgically or orthodontically treated].

OBJECTIVE: To study the boundary between orthodontic and surgical treatment in correction of anterior open bite. METHODS: 70 cases (18.0 ages in average) treated orthodontically and 14 cases (25.1 ages in average) treated surgically were chosen. 154 hard and soft tissue measurements were analyzed by statistical software. RESULTS: A diagnostic index, L1MP, was gained with simple factorial analysis. L1MP </= 89.5 was bound to be treated with surgery. A discriminate function, Z = -0.80188 L1MP + 0.91401 Age + 0.671111 Antigonial notch-MP + 0.599992 SNPg, was produced by multiple factorial discriminate analysis. Z < O is an indication of orthodontic treatment. CONCLUSION: The diagnostic index and discriminate function were both useful in determining which method to be chosen in treatment of anterior open bite. The discriminate function was tested to be more efficient than the diagnostic index.

Adolescent↗