Study Of Chin Morpholojy In Class â…¡Subjects With Different Vertical Skeletal Craniofacial Pattern

Facial esthetics is greatly increasing attention in orthodontics, improving facial aesthetics is one of the aims of orthodontic treatment. Many orthodontists advocated that profile analysis should be an important consideration in orthodontic treatment planning. An important aspect of orthodontic diagnosis and treatment depends on achieving maximum soft tissue esthetics. Chin is the main part of the lower 1/3 of the face, it plays an important role in the facial esthetics. A key aspect of orthodontic diagnosis and treatment planning is the of chin evaluation, which includes the assessment of chin soft and hard tissues-profile esthetics.Throughout the history of orthodontics, clinicians have been faced with the challenge of correcting skeletal Class II malocclusions. It has been reported that approximately 15% to 30% of American children have Class II malocclusions, comprising about 20% to 30% of all orthodontic patients. Compared with normal persons, they typically have retrusive chin positions, and different chin morphologies. So evaluating the chin morphology in subjects with Class II malocclusion is very important to achieve successful orthodontic diagnosis, treatment planning and maximum facial aesthetics. The purpose of this article was to evaluate the shape of the chin hard and soft tissues of adolescences with Class II malocclusion by using morphometric methods, to establish whether there is difference with regard to chin morphology in Class II subjects with different vertical skeletal craniofacial pattern and the relationship among them, and it may provide some proofs for diagnose and treatment of Class II malocclusion.Part 1 Chin Morphology in Subjects with normal Skeletal Craniofacial PatternObjective: to investigate the chin morphology in subjects with normal skeletal craniofacial pattern using the cephalogram before orthodontic treatment. Methods: The samples consisted of 60 cases(male 30 and female 30) with normal skeletal craniofacial pattern, aged from 13 to 17 years old, no history of orthodontic treatment.Cephalograms were analyzed for all subjects. 23 measurements of the chin soft and hard tissues were selected and analyzed to study the chin morphology in subjects with normal skeletal craniofacial pattern. Results: Chin height(20.28±2.34)mm, chin angle(76.86±6.68)°, chin concavity(3.01±0.59) mm,chin curvatura(63.45±4.35)mm, distance between chin and lip(3.61±3.42) mm,sulcus mentolabialis(5.60±0.73) mm,soft tissue chin angle:(62.27±2.54) mm。Conclusions: The present findings will help orthodontists to make reasonable diagnosis and treatment planning.Part 2 Chin hard-tissue morphology in Class II subjects with different vertical skeletal craniofacial patternsObjective: To evaluate whether there is difference with regard to chin hard-tissue morphology in Class II subjects with different vertical skeletal craniofacial patterns and the relationship among them. Methods: The samples were composed of 120 cases of adolescents who denied orthodontic treatment history and presented Class II skeletal pattern. They were divided into three groups according to mandibular plane angle: high angle group (21 cases, FH/MP> or = 32 degrees), average angle group(43 cases, 22 degrees or = 32 degrees), average angle group(43 cases, 22 degrees