Changes in the faces and smiles of patients with dentofacial deformities

In recent years, new materials and more versatile techniques have made it possible for increasingly complex dentofacial deformities to be treated by multidisciplinary teams, with maxillofacial surgeons and orthodontists as the core team members. This lecture will demonstrate the treatment of these challenging cases. Through teamwork, maxillofacial surgeons and orthodontists can bring back smiles to these patients.postprin

PTHrP and Cbfal expression in condylar cartilage during pubertal growth

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Orthodontic treatment need and quality of life

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Assessment of orthopedic treatment of class III malocclusion Using P.A.R. index

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Comprehensive cephalometric analyses of 10 to 14-year old southern Chinese

Aims: (Part 1) To review the orthodontic literature and assess which cephalometric methods were the most frequently used, and (Part 2) provide comprehensive cephalometric reference values for 10 to 14-year old southern Chinese. Materials and Methods: (Part 1) The cephalometric methods used in the orthodontic literature over a ten-year period (1999-2008) were investigated. (Part 2) The material comprised lateral cephalometric radiographs of a random sample of 200 males and 205 females 12-year old southern Chinese in Hong Kong. The radiographs were digitized twice with the Computer Assisted Simulation System for Orthognathic Surgery (CASSOS) program. Referenced values for 10-, 11-, 13- and 14-year old were obtained by extrapolation of data from measurements of templates of longitudinal sample of Swedish. Results: (Part 1) The four most frequently used cephalometric methods were those devised by Björk, Jacobson, Pancherz and McNamara. (Part 2) Reference population values for those four methods of 12-year old southern Chinese children were collected from three of our previous publications, and for the McNamara analysis expanded to include 10 to 14-year old children. At the age of 12-year there were statistically-significant gender differences for the majority of the cephalometric variables based on linear measurements, varying from -0.4 to +0.8 standard deviation (SD)-scores, and about half of the angular measurements, varying from -0.4 to +0.4 SD-scores. Conclusion: Four cephalometric methods presented over a 10-year period were more commonly used than the other cephalometric methods. The use of specific cephalometric standards of those four methods for southern Chinese, separate for gender, seem to be justified.published_or_final_versio

Modified Bjork analysis of lateral head radiographs of southern Chinese

Aim: To establish cephalometric norms for the modified Björk’s cephalometric analysis in southern Chinese children, and compare them to those of a matched Caucasian sample. Materials and Methods: The material comprised lateral cephalometric radiographs of a random sample of 200 males and 205 females 12-year-old southern Chinese, and an additional sample of 43 males and 43 females 12-year-old British Caucasian children in Hong Kong. The radiographs were digitized twice with the Computer-Assisted Simulation System for Orthognathic Surgery (CASSOS) program. Results: The results showed that there were statistically significant ethnic differences for 15 out of the 17 cephalometric variables (P<0.05-0.001). There were statistically significant ethnic differences for 11 variables in males (P<0.05-0.001) and 15 variables in females (P<0.05-0.001). The size of the statistically significant gender differences varied from -0.4 to 0.8 (P<0.05-0.001) in SD scores for Chinese and from 0.5 to 0.6 (P<0.01) for Caucasian. The size of the observed statistically significant ethnic differences varied from -1.7 to 1.3 (P<0.05-0.001) in SD scores for female and from -1.6 to 1.0 (P<0.05-0.001) for male. Conclusion: Cephalometric norms for the modified Björk’s cephalometric analysis in southern Chinese children were established. The use of specific standards for Chinese and separate for gender, for the modified Björk’ cephalometric analysis seems to be justified.published_or_final_versio

Masticatory muscle pain before, during, and after treatment with orthopedic protraction headgear: A pilot study

Protraction headgear has been used in conjunction with a palatal expansion appliance to correct Class III malocclusion with maxillary deficiency and/or mandibular prognathism. In general, 800 gm of orthopedic force is used to protract the maxilla, and 75% of this force is transmitted to the temporomandibular joint (TMJ) area via the mandible. The effect of this heavy intermittent force on the TMJ has not been reported in the literature. The objectives of this study were to determine the level of masticatory muscle pain and EMG activity in patients treated with maxillary protraction headgear. Ten patients with skeletal Class III malocclusion whose treatment plan called for maxillary protraction headgear treatment participated in this study. Nocturnal masticatory muscle activity was determined using a portable electromyographic (EMG) recording device. Subjects wore the EMG device 14 nights before treatment, 14 nights during treatment, and 14 nights 1 month after active treatment. Masticatory muscle pain level was determined by muscle palpation, scored on a scale of 0 to 3 each period, according to the method of Gross and Gale. The examiner followed a sequence outlined by Burch to examine the masticatory muscles. Results showed no significant differences for masticatory muscle activities before, during, and after treatment. Only a few patients experienced level 1 masticatory pain during treatment. None of the patients experienced masticatory muscle pain 1 month after treatment. These results demonstrate no significant increase in masticatory muscle activity or muscle pain associated with orthopedic treatment using maxillary protraction headgear.published_or_final_versio

Cephalometric comparisons of Chinese and Caucasian surgical class III patients

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Effective age for application of orthopedic maxillary protraction

Abstract no. 1374published_or_final_versio

Cephalometric norms for the upper airway of 12-year-old Chinese children

OBJECTIVE: To establish cephalometric norms for the upper airway of 12-year-old Chinese children, and to assess these norms with regard to gender, age, ethnicity and other craniofacial structures. METHODS: Lateral cephalograms were obtained from a random sample of 425 12-year-old Chinese children (224 boys and 201 girls) to establish the Chinese norms, and from a matched group of 108 12-year-old Caucasian children (61 boys and 47 girls) as an ethnic comparison. Published data on the upper airway norms of Chinese adults were used to make age comparisons. Nine upper airway and 14 craniofacial variables were measured. RESULTS: Chinese boys tended to have a thicker soft palate (P = 0.008), and less depth in the retropalatal (P = 0.011), retroglossal (P = 0.034) and hypopharyngeal (P < 0.001) pharynx than Chinese girls, whereas no gender dimorphism was found in Caucasian children. Ethnic differences were found in the depth of the retroglossal oropharynx in both genders and the position of the hyoid bone in boys. Compared with Chinese adults, the overall size of the upper airway in Chinese children was smaller. The mandibular body length and the craniocervical inclination were found to be statistically significantly, albeit weakly correlated with upper airway variables. CONCLUSIONS: Cephalometric norms for the upper airway of Chinese 12-year-old children were established, indicating gender-specific differences, and some ethnic differences were found in comparison with those of 12-year-old Caucasian children. An association between the mandibular body length and the craniocervical inclination with upper airway variables was also noticeable.published_or_final_versio