The Reference Indexes Of Clinical Diagnosis Preparation With The Skeletal Class Ⅲ Malocclusion In Prepubertal Growth Periods In Dalian

Objectives:To search for sensitive indexes of the skeletal ClassⅢmalocclusion in prepubertal growth periods in X-ray cephalometric Study, in order to diagnose clinical cases and make plans, and even expect problems occurred in and after progresses.Methods:50 cases respectively in the skeletal ClassⅠand ClassⅢmalocclusion in prepubertal growth periods(boy 25,girl 25),29 soft tissue indexes and 53 hard tissue indexes were examined in cephalometry. Apply General Linear Model to analyse respectively the group and the sex differences between ClassⅠand ClassⅢ. Apply independent-samples t-test to examine statistical significance. Apply variation to search the sensitive indexes.Results:General Linear Model analysis show 45 indexes with group difference and no sex difference, only Go-CF (mm) and Xi-PM(mm) show group and sex difference. There are more shorter posterior face height and longer mandibular body length in the skeletal ClassⅢ. Compared with the skeletal ClassⅠ,32 indexes were statistically significant with independent-samples t-test in the skeletal ClassⅢmalocclusion group(P<0.01). Meanwhile, boys have longer posterior face height than girls in ClassⅠ, but no significance in ClassⅢ(p>0.05); boys have longer mandibular body length in ClassⅢ, but no significance in ClassⅠ(p>0.05). Apply variation to search NA-PA,AB-NP,Wits,Po-Np(mm),A-NPo(mm),ODI,APDI 7 sensitive hard tissue indexes; andZ角,H角,N'NsPog',Sn:sto/sto:Me'4 sensitive soft tissue indexes.Conclusion:Clinical characters in skeletal Class III:maxillary retrusion and development discrepancy; mandibular protrusion and development beyond the extend; intermaxillary relationships show apparently ClassⅢskeletal type and openbite; the whole face shows counterclockwise growth, short vertical distance; concave profile; upper 1/3 with high rates,but lower 1/3 with low rates; upper lip retrusion, lower lip protrusion.Sensitive indexes:NA-PA,AB-NP,Wits,Po-Np(mm). A-NPo(mm),ODI,APDI (7 hard tissue); Z angle,H angle,N'NsPog',Sn:sto/sto:Me' (4 soft tissue).Combined the upper clinical characters,sensitive indexes and clinical manisfestations, were efficiently better to clinical diagnosis of the skeletal ClassⅢmalocclusion. We can find the problems with cases in time. It's good to analyse the dilemma that clinical manisfestations in no consistent with indexes, solve questions more precisely, make plans efficiently, and expect possible situation.