Craniofacial Characteristics Of Growth In Chinese Class Ⅲ Subjects

Class III malocclusion has a relatively higher prevalence in Chinese people.Characteristics of craniofacial growth in different types of malocclusion couldprovide indications to estimate the growth potential of malocclusion patient andhelp orthodontic clinicians to get proper treatment time, effective treatmentplanning and stable treatment outcomes. Two main ways can be used toinvestigate human growth and development in Class III patient: longitudinaldata and cross-sectional data. Longitudinal study obtained hardly and fewreports were found, but cross-sectional study was focused by many authores.However, none of these previous studies had analyzed growth trends of Class IIImalocclusion by using CVM method in Chinese people.Objective:A cross-sectional study was designed to investigate the craniofacial growthtrends in Chinese untreated Class III subjects.Material and Methods: The samples came from 899 patients with untreated Class III malocclusioninclude males (401)and females(498) in Fourth Military Medical University,School of Stomatology, China.Male and female subjects were divided to sixconsecutive developmental periods(from CS1 to CS6 according to cervicalvertebral maturation method). Their cephalograms were measured and analyzed.Results:For male subjects, the height of mandibular ramus (Co‐Go) exhibitedstatistically significant increases in the transitions from CS2 to CS5. Both thetransition from CS1 to CS2 and from CS3 to CS4 showed statistically significantincreases in lower anterior facial height (L1‐MP).In female samples, the height of mandibular ramus (Co‐Go) revealedsignificant increases in the transitions from CS1 to CS4. Total mandibular length(Co‐Gn) demonstrated statistically significant increases from CS3 to CS4. As long,significant increases were also found for total mandibular length (Co‐Gn),dentoalveolar height at the lower incisor (L1‐MP) from CS5 to CS6.No matter males or females, no significant differences occurred in maxillarygrowth between stages. In addition, no significant changes were fonud formandibular plane angle(MPA) and gonial angle in both sexes.Conclusion:1.Growth peak of mandible appeared in interval CS1‐CS2 in both Male(8.3mm) and Female( 7.2mm),and most increases in mandible came from thegrowth of mandibular ramus.2.Compared with females, the male subjects had a higher increase inCS3‐CS4 interval, then the growth of mandible decreased gradually and almoststopped in CS5‐CS6 interval; for female samples, the mandibular growthcontinued until period of early adulthood. 3.With the worsening of the Class III disharmony, Mandibular plane angletand gonial angle did change.Thathe growth direction of mandible held the linein untreated patients.