3D vs. 2D cephalometric analysis comparisons with repeated measurements from 20 Thai males and 20 Thai females

This paper presented 3D cephalometric analysis on DICOM data from I-CAT CT cone-beam machine consisted of averages and standard deviations from 20 Thai males from 19 to 70 year (average 33.53 ± 14.08 year) and 20 Thai females from 16 to 70 year (average 32.60 ± 15.37 year). The angular measurements consisted of 49 lateral angular measurements and 9 frontal angular measurements while linear measurements consisted of 29 lateral linear measurements, 3 frontal linear measurements, and 8 perpendicular measurements. Results in 3D were compared with the corresponding 2D results showing that most midline-to-midline linear measurements and some midline-to-midline angular measurements were not different, while other types of measurements were significantly different. The 3D results will be used in the clinical Ceph3D services as requested by those with interests on cephalometric analysis and anthropology with focus on Thai subjects while the 2D results will be used for comparison with cephalometric analyses from other orthodontists.ts reserved

A prospective study of twin-block appliance therapy assessed by magnetic resonance imaging

Forty children displaying Class II Division 1 malocclusion were involved in a prospective magnetic resonance image investigation to evaluate the effects of Twin-block functional appliances on the temporomandibular joints. None of these children had clinical signs or symptoms of temporomandibular disorders. Nineteen children were treated with a Clark Twin-block appliance for 6 months; the other 21 children received no treatment and served as controls. Comparison between control and Clark Twin-block groups suggested that reduction of the condylar axial angle represents a feature of untreated Class II growth patterns, whereas axial angle stability with Clark Twin-block therapy may suggest alteration of condylar growth direction. Condyles that were positioned at the crest of the articular eminence by the Clark Twin-block at the beginning of treatment had reseated back into the glenoid fossa after 6 months. However, 75% of the condyles were more anteriorly positioned in successfully treated Clark Twin-block cases. There was no clear evidence of remodeling of the glenoid fossa at the eminence as a result of Clark Twin-block treatment. The initial prevalence of disk displacements for the combined groups was 7.5% anterior, 5% medial, and 12.5% for lateral disk displacement. Clark Twin-block therapy had neither positive nor negative effects on disk position, and there was no convincing evidence that the disk was recaptured

Effects of twin-block therapy on protrusive muscle functions

Protrusive mandibular function, including maximum protrusive force and fatigue time, was investigated in 66 children displaying Class II Division 1 malocclusion. Thirty-two children were treated with the Clark Twin-block appliance and the other 34 children served as untreated controls. The observation period was 6 months. Cross-sectional data based on pretreatment records showed that maximum protrusive force ranged from 18.5 N to 160 N, with a mean of 80.3 +/- 30.7 N. Maximum protrusive force was significantly higher in males than in females (P <.001). The correlation between maximum protrusive force and chronologic age was low (r = 0.20) and did not reach significance. Maximum protrusive force in the group of children with disk displacement was not significantly different from that of the group without disk displacement. Comparison of pretreatment and 6-month records in the untreated control group revealed a significant increase in maximum protrusive force (P <.01) as a result of normal growth, while the measured change in the Twin-block-treated children did not reach significance. Fatiguing the protrusive muscles did not alter mandibular position in the Twin-block group after 6 months of treatment. The present study does not support the lateral pterygoid hypothesis, as there was no evidence of an increase in mandibular protrusive function after treatment with the Twin-block functional appliance

A method for protrusive mandibular force measurement in children

With this new method, protrusive mandibular force was studied in a homogeneous group of 69 children with similar occlusions. Maximum protrusive force ranged from 18.5 to 160 N (mean +/- SD = 81.3+/-31.6 N). Maximum protrusive force was significantly higher in males (90.7+/-30.2 N) than females (66.6+/-28.6 N) while fatigue time was not significantly different between the two groups (70.6+/-38.5 s for males and 65.1+/-33.6 s for females). Although protrusive force was stable in each session, it varied considerably between different experimental days within the same individual. No statistically significant correlation was found between maximum protrusive force and age, skeletal maturity, height, weight, overjet, maxillomandibular relation, facial height, facial widths or facial proportions

Analysis of the Preserved Amino Acid Bias in Peptide Profiles of Iron Age Teeth from a Tropical Environment Enable Sexing of Individuals Using Amelogenin MRM

The first dental proteomic profile of Iron Age individuals (ca. 2000–1000 years B.P.), collected from the site of Long Long Rak rock shelter in northwest Thailand is described. A bias toward the preservation of the positively charged aromatic, and polar amino acids is observed. It is evident that the 212 proteins identified (2 peptide, FDR <1%) comprise a palimpsest of alterations that occurred both ante-mortem and post-mortem. Conservation of amino acids within the taphonomically resistant crystalline matrix enabled the identification of both X and Y chromosome linked amelogenin peptides. A novel multiple reaction monitoring method using the sex specific amelogenin protein isoforms is described and indicate the teeth are of male origin. Functional analysis shows an enrichment of pathways associated with metabolic disorders and shows a capacity for harboring these conditions prior to death. Stable isotope analysis using carbon isotopes highlights the strongly C 3 based (≈80%) diet of the Long Long Rak cemetery people, which probably comprised rice combined with protein from freshwater fish among other food items. The combination of proteomics and stable isotope analysis provides a complementary strategy for assessing the demography, diet, lifestyle, and possible diseases experienced by ancient populations