Camouflage treatment of skeletal Class III malocclusion with multiloop edgewise arch wire and modified Class III elastics by maxillary mini-implant anchorage.

OBJECTIVE: To evaluate the effect of the multiloop edgewise arch wire (MEAW) technique with maxillary mini-implants in the camouflage treatment of skeletal Class III malocclusion. MATERIALS AND METHODS: Twenty patients were treated with the MEAW technique and modified Class III elastics from the maxillary mini-implants. Twenty-four patients were treated with MEAW and long Class III elastics from the upper second molars as control. Lateral cephalometric radiographs were obtained and analyzed before and after treatment, and 1 year after retention. RESULTS: Satisfactory occlusion was established in both groups. Through principal component analysis, it could be concluded the anterior-posterior dental position, skeletal sagittal and vertical position, and upper molar vertical position changed within groups and between groups; vertical lower teeth position and Wits distance changed in the experimental group and between groups. In the experimental group, the lower incisors tipped lingually 2.7 mm and extruded 2.4 mm. The lingual inclination of the lower incisors increased 3.5°. The mandibular first molars tipped distally 9.1° and intruded 0.4 mm. Their cusps moved 3.4 mm distally. In the control group, the upper incisors proclined 3°, and the upper first molar extruded 2 mm. SN-MP increased 1.6° and S-Go/N-ME decreased 1. CONCLUSIONS: The MEAW technique combined with modified Class III elastics by maxillary mini-implants can effectively tip the mandibular molars distally without any extrusion and tip the lower incisors lingually with extrusion to camouflage skeletal Class III malocclusions. Clockwise rotation of the mandible and further proclination of upper incisors can be avoided. The MEAW technique and modified Class III elastics provided an appropriate treatment strategy especially for patients with high angle and open bite tendency.

Application of magnetic resonance T2 mapping in the temporomandibular joints.

OBJECTIVES: The objective of this study was to apply magnetic resonance (MR) T2 mapping to the normal temporomandibular joint (TMJ) disk and to determine its T2 character. STUDY DESIGN: Fourteen volunteers with 28 healthy TMJs were selected for this study. MR T2 maps of all of the disks were acquired. The global disk area and 6 zonal regions of interest (ROIs) of superior, inner, and inferior layers and anterior, middle, and posterior bands were defined for each disk. T2 values of the global disk and each zonal ROI were calculated. Comparisons of the T2 values among the 3 layers and among the 3 bands were performed using the general linear model. RESULTS: The T2 value for the whole disk was 40.21 ± 2.95. The T2 values of the superior (39.42 ± 3.73) and inferior layers (40.11 ± 3.29) were significantly higher than the inner layer (37.28 ± 3.54) (P < .05). The T2 values of the anterior (36.96 ± 3.43) and posterior bands (36.01 ± 3.72) were significantly lower than the middle band (41.04 ± 5.51) (P < .05). CONCLUSIONS: Preliminary determinations of T2 values for the bands and layers of normal TMJ disks were calculated.

Validity assessment and determination of the cutoff value for the Index of Complexity, Outcome and Need among 12-13 year-olds in Southern Chinese.

To validate the use of the Index of Complexity, Outcome and Need (ICON) in assessing orthodontic treatment need among 12-13 year-olds in southern China, we determined the threshold value of ICON based on Chinese orthodontists' judgments. The samples consisted of 335 students in grade 7 from 16 randomly selected middle schools in Chengdu, China. Three associate professors provided ICON scores for each participant and the results were compared with the gold standard judgments from 25 experts on treatment needs. Based on the gold standard, 195 casts belonged to the treatment category, while the rest 140 belonged to the no-treatment category. With the international cutoff point of 43, the sensitivity and specificity of the ICON score were 0.29 and 0.98.The best compromise between sensitivity and specificity in Chengdu, compared with the gold standard, was found at a cutoff point of 29, and the sensitivity and specificity were 0.88 and 0.83. When used to evaluate the treatment need of 12-13 year-olds in southern China, the international ICON cutoff value did not correspond well with Chinese orthodontists' judgments; a lower cutoff value of 29 offered a greater sensitivity and specificity with respect to expert orthodontists' perception of treatment need.

Craniofacial morphology characteristics of operated unilateral complete cleft lip and palate patients in mixed dentition.

OBJECTIVE: The objective of this study was to analyze craniofacial morphologic characteristics at the stage of mixed dentition in Chinese children who had received surgery for unilateral complete cleft lip and palate (UCCLP) compared with the healthy population. MATERIAL AND METHODS: Lateral cephalometric radiographs were taken for 2 groups of individuals: (1) 48 UCCLP patients who had been operated on before 2 years of age, and (2) 60 noncleft peers as controls. RESULTS: The operated UCCLP groups differed from the control group as follows: reduced cranial base length, less maxillary length, more retrognathic maxilla, retusion of the entire maxilla, more incongruous intermaxillary relation, more concave skeletal profile, and more lingually inclined maxillary and mandibular incisors. CONCLUSIONS: The operated UCCLP children at the mixed dentition stage showed serious craniofacial deformities and the craniofacial growth was influenced (especially in maxilla).

Nonsurgical treatment of an adult patient with bilateral posterior crossbite.

A woman with an Angle Class III malocclusion and bilateral posterior crossbites complaining of difficulty in chewing was treated orthodontically without surgery. The treatment comprised asymmetric extractions, a removable mandibular lingual arch constriction appliance to narrow the mandibular arch, and a standard edgewise appliance to align the teeth. Pretreatment, posttreatment, and 1-year follow-up records are shown. With this treatment strategy of constricting the mandibular arch by using a combination of removable and fixed orthodontic appliances, we achieved a good result with optimal occlusion.

Soft-tissue characteristics of operated unilateral complete cleft lip and palate patients in mixed dentition.

PURPOSE: The purpose of the study was to provide quantitative information about the facial soft-tissue characteristics of operated unilateral complete cleft lip and palate (UCCLP) children compared with healthy children during mixed dentition. METHODS: Lateral cephalometric radiographs of 48 children with UCCLP who had been operated on before the age of 2 years were analyzed and compared with those of a control group of 60 healthy children with the same age, sex, and ethnic characteristics. RESULTS: The children with operated UCCLP differed from the control group by having a more concave profile, flatter nasal tip, more retrognathic basis nasi, shorter upper lip, thicker upper and lower lip, reduced upper-lip projection, and increased lower-lip projection. CONCLUSIONS: The facial soft-tissue morphology in operated UCCLP patients differed from normal controls of the same age, sex, and ethnic group. It may be necessary for children with UCCLP operated before 2 years of age to have some preventive treatment.

Angular photogrammetric comparison of the soft-tissue facial profile of Kenyans and Chinese.

The purpose of this study was to determine the average angular dimensions that define the normal soft-tissue facial profiles of black Kenyans and Chinese and compare them with each other and with values proposed for whites. Standardized facial profile photographs, taken in natural head position, of 177 black Kenyans and 156 Chinese with normal occlusion and well-balanced faces were analyzed for 12 angular parameters. Two-sample t-tests were used to determine sex and racial differences. Kenyan and Chinese averages were compared with proposed white values using 1-sample t-tests. Eight parameters in Kenyans and 7 in Chinese showed sex differences. All angles, except for facial convexity, nasal dorsum, and inferior facial height, were different between Kenyans and Chinese. Kenyan and Chinese averages for all parameters were different from proposed white average, except for facial convexity. Nasolabial and mentolabial angles showed large individual variability and racial differences. The study demonstrated many differences in average angular measurements of the facial profiles of black Kenyans, Chinese, and white standards. Orthodontists, maxillofacial and plastic surgeons, and other clinicians working in the craniofacial region should bear these in mind when setting aesthetic treatment goals for patients of different races. Mean values from this study can be used for comparison with similar records of subjects with same ethnicity.

[The centric relation-maximum intercuspation discrepancy in adult angle's class II pretreatment patients].

OBJECTIVE: This study investigates the differences in condylar position between centric relation (CR) and maximum intercuspation (MI) in Angle's Class II orthodontic patients before treatment. METHODS: 80 cases, who were Angle's Class II pretreatment patients, and 50 cases, who were normal(ideal) occlusion were accepted. Dental casts were mounted on Panadent articulator with CR bite record, taken by bilateral manipulation and load testing. The differences in condylar position between CR and MI in all three spatial planes were measured using the Panadent condylar position indication (CPI). RESULTS: (1) The positive rate of CR-MI discrepancy was 92.50%(74 cases) in the group of Angle's Class II malocclusion and 10.00% (5 cases) in the group of normal occlusion(P< 0.001). 2)74.32% (55 cases) CR-MI discrepancy in 74 cases in the group of Angle's Class II pretreatment patients were coincidence discrepancy. (3)91.25% patients in the group of Angle's Class 11 malocclusion and 66.00% in the group of normal occlusion present occlusion interferences which located at the posterior teeth. CONCLUSION: The results suggested that orthodontists should be aware of a high incidence of condylar displacement in Angle's Class ii pretreatment patients, and measure condylar displacement before the start of comprehensive orthodontic treatment to unmask real jaw relationships and avoid possible misdiagnoses.

Correlation between centric relation–maximum intercuspation discrepancy and temporomandibular joint dysfunction.

OBJECTIVE: To investigate the relationship between centric relation-maximum intercuspation (CR-MI) discrepancy and temporomandibular joint dysfunction (TMD) in pre-treated orthodontic patients. MATERIAL AND METHODS: The study involved an experimental group of 107 pre-treated orthodontic patients with signs and symptoms of TMD aged 18-32 years, and a control group of 70 students with no signs and symptoms of TMD aged 20-30 years. The psychological condition of subjects was evaluated using two standard questionnaires, and a clinical examination performed to assess masticatory musculature and temporomandibular joint (TMJ) function, and to establish the presence or absence of TMD. Helkimo indices, the anamnestic dysfunction index (Ai) and the clinical dysfunction index (Di), were determined. Dental casts were mounted on a semi-adjustable articulator in CR using a CR bite record taken by bilateral manipulation and verified by load testing and face bow records. Differences in condylar position between CR and MI in the three planes of space were determined using the condyle position indicator. RESULTS: A positive CR-MI discrepancy, defined as a discrepancy exceeding 1 mm in the vertical or horizontal planes or 0.5 mm in the transverse plane, was found in 72.9% of the experimental and 11.4% of the control group. Comparison of the groups showed a significant difference (χ² = 22.67, P < 0.001). CR-MI discrepancy was significantly correlated with Di and Ai in all subjects (P < 0.01). CONCLUSIONS: There was CR-MI discrepancy in most of the pre-treated patients with signs and symptoms of TMD. This discrepancy may be a contributory factor to the development of TMD in these patients.

Trigeminal expression of N-methyl-D-aspartate receptor subunit 1 and behavior responses to experimental tooth movement in rats.

OBJECTIVE: To test the hypothesis that peripheral N-methyl-D-aspartate (NMDA) receptors play a role in pain induced by experimental tooth movement. MATERIALS AND METHODS: Male Sprague-Dawley rats weighing between 200 g and 300 g were used in this study. Expression of NMDA receptors subunit 1 (NMDAR1) in the mandibular portion of the trigeminal ganglion (TG) was determined by Western blotting 4 hours and 1, 2, 3, 5, 7, and 14 days after tooth movement. Changes in the time taken by the rats on nocifensive behavior then effects of NMDA receptor antagonist MK-801 and force magnitude on these changes in behavior and NMDAR1 expression were evaluated. RESULTS: Experimental tooth movement led to a statistically significant increase in NMDAR1 expression at protein level from day 1 to 7 after force application initiating tooth movement. Time spent on nocifensive behavior dramatically increased from day 1 to 7. The rhythm in NMDAR1 expression in the TG and behavioral activities correlated well with the initial orthodontic pain responses. The magnitude of the nocifensive behavior and NMDAR1 expression were both force magnitude dependent and could be reduced by peripheral NMDA receptor antagonist MK-801. CONCLUSIONS: The hypothesis is accepted. Peripheral NMDA receptors are modulated by experimental tooth movement and involved in the development of tooth movement pain.

Development of a behavior model of pain induced by experimental tooth movement in rats.

The mechanism of orthodontic pain and discomfort is poorly understood partly because of the limited number of animal behavioral models for pain assessment. This study aimed to develop a behavioral model for assessment of tooth-movement pain in rats using directed face-grooming activity. Male Sprague-Dawley rats weighing 200-300 g were used. They were videotaped on days 1, 3, 5, 7, and 14 after experimental tooth movement and their directed face-grooming behavior was evaluated. In addition, we also evaluated behavioral responses to the application of a progressively higher magnitude force and to multiple applications of an equal magnitude force. Finally, the effects of peripherally and systemically administered morphine and of the N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801, on the behavioral responses were evaluated. The results indicated that time spent on directed face-grooming activity increased dramatically after initiating experimental tooth movement. The change concurred with the initial orthodontic pain response. This behavioral change was reproducible and was related to force magnitude. Application of both systemic and peripheral morphine and MK-801 could exert an analgesic effect on this pain model. These results suggest that directed face-grooming behavior can be a reliable measure for tooth-movement pain in rats, which could be widely used in investigating the orthodontic pain mechanism.