Craniomaxillofacial Characteristics Of Adult Skeletal Class â…¡ Patients And Discriminant Analysis Of Surgical And Non-surgical Treatment

Skeletal class Ⅱ malocclusion accompanying with intricate mechanism of facialand skeletal inharmony is clinically common, which usually compromises facial eastheticsand oral function of patients seriously,as well as it‘s hard to correct this kind ofmalocclusion. Treatment of adults who have missed the chance of growth modificationlimits to orthodontic camouflage or combined surgical-orthodontic treatment.Compensatory protocols apply to patients with mild to moderate deformity who haveacceptable profile, while for patients whose class Ⅱ problems are so severe thatsurgery,the only possible treatment, must be adapted to balance the occlusal and skeletalrelationship, achieve nice facial shape and keep the health of stomatognathic system.This study which is a retrospective study, based on computer aided measurementtechnology, analysed the cephalometric lateral headfilm of untreated patients from sagittaland vertical-direction overall. The objective of the study is to know the craniofacial typesand soft-hard tissue‘s characteristics of adults patients with skeletal class Ⅱmalocclusion from sagittal and vertical-direction,and attempts to make clear theindication of surgery and non-surgery.Experiment One: Craniomaxillo facial type composition analysis of skeletal classⅡadult patients in Xi’an Objective: To analyze the craniofacial morphology in sagittal, vertical and both crossconstitute of adult patients with skeletal class Ⅱin Xi’an area. Methods: Together247cases met the inclusion criteria and sagittally divided into six groups (G1-G6group): G1maxillary growth over while the mandible normal; G2maxillary developing normally butlower jaw underdevelopment; G3maxillary overgrown and mandibularunderdevelopment; G4maxillary and mandibular both overgrown; G5maxillary jawwere developing normally (but relatively dislocated); G6maxillary and mandibular bothunderdevelopment. Vertically divided into3groups (V1-V3): V1high angle group; V2normal angle group; V3low-angle group (respectively as packet the SN-MP angle and theFH-MPangle indicators). Results: sagittal constitutes results displayed G2group theproportion was the highest, accounting for47.8%(in male and female patients accountedfor51.9%and45.8%, respectively), followed G5was26.7%; vertical composition, boththe grouping criteria are displayed the V2group accounts for about half; Cross analysisshows that G2V2combination had the highest percentage. Conclusion: keletal class Ⅱadult patients in Xi’an region sagittal mainly to the lack of jaw development, about50%ofpatients vertical dysplasia, High angular type with the vast majority of mandibularretraction, and the most common cranial and maxillofacial morphology is mandibularretraction with normal angle type. In both angle and low-angle type jaw after shrinkingmay be true mandibular body hypoplasia, and high-angle Class II causes may beaccompanied by the clockwise rotation of the lower jaw, recommended correction forkeletal class Ⅱpatients with growth potential, should be more on the jaw promotingdevelopment rather than the containment of the maxillary, at the same time pay attentionto the effects of vertical growth for correction; Adult patients with skeletal class II,understanding of the craniofacial types can be speculated the pathogenesis, help to bettertreatment options.Experiment Two: Soft-hard tissue’s characteristics of adult skeletal class Ⅱ patientsin Xi’an with different vertical skeletal typeObjective: To analyze whether the craniofacial hard and soft tissue characteristicsare differences between the different vertical facial types about adult skeletal class Ⅱpatients in Xi’an. Methods: SN-MP angle and the FH-MPangle as the double groupingcriteria,200adult patients met the inclusion criteria and were divided into three groups, atotal of36soft-hard tissue indicators were Selected, which wre commonly used and can basically reflect the characteristics of the cranial and maxillofacial,. use one-way ANOVAanalysis through the SPSS16. Results:30indicators have statistically significantdifference among the three groups. High-angle patients have thicker base of the lower lipat the bottom of soft tissue and chin soft tissue, and soft tissue surface angle (GL’-Sn-Me ’)more sudden but nasolabial angle (Cotg-Sn-Ls) relatively dayton; patients with low-anglemaxillary protrusion obvious (Pn-A value) while chin retrusion was mild (Pn-Pog is small),the hard tissue of patients with high-angle show more retrusive of the chin, and therelationship of anterior skull base plane, frankfort plane, palatal plane, occlusal plane andmandibular plane manifest an"open" trend; low-angle have serious incisorcompensatory,and the angle between upper and lower incisors is smaller. Conclusion:Compensation is prevalence between each of craniomaxillofacial structures, the soft-hardtissues had certain degree of compensatory for sagittal skeletal problems in the skeletalclass Ⅱ patients, however, different vertical type will influence the phenotype anddegree, high angle had a convex surface of hard and soft tissues, surface under a third softtissue thickness increases, palate plane and occlusal plane are steeper; Well-developedchin in low-angle patients can mask Class II facial type. Understanding differencesbetween hard and soft tissue features caused by vertical type, making a clear definition ofthe degree of compensatory and the potential of further compensation, are beneficial to thecorrect diagnosis and treatment of these patients in clinical.Experiment There：Discriminant analysis of surgical and nonsurgical therapy inadult skeletal classⅡ patientsObjective：Based on cephalometrics analysis, explore the discriminant basis toclassify adults with skeletal classⅡinto2groups: those who require surgery treatmentand those who only need orthodontic therapy, guiding clinical practice. Methods：Retrospective study, a total of247adults with skeletal classⅡwere collected (185receivedorthodontic therapy and62treated with surgery), use nonparametric significance test toassecss the differences between80cephalometric variables of both groups, furtherstepwise discriminant analysis was performed to identify the variables that best separatethe2group. Results：Mann-Whitney u test shows that53of80cephalometric variableshave statistically difference between2groups (p<0.05),6sensitive index were screened bystepwise discriminant analysis, discriminant equation was formedasthefollowing:Y=-21.796-0.54*Pn-Pog-0.262*Sn-HLine+0.117*Gl‘-Sn-Pog‘+0.070*Hol dwayRatio-0.173*NA-APog+0.026*GoMe， prediction discriminant accuracy rate is71.66%tested by Jackknife method. Conclusions：The important roles in determingsurgical or non-surgical treatment for skeletal classⅡadults patients are the length of themandibular body, the position of mentum,the relationship between nose、lips and soft chin,the compensatory degree of lower incisors‘relatived to the position of chin, the convex ofthe maxillary. these factors should be comprehensive analysised in clinical, as well as paymuch attention to patients‘subjective desire.