The Screening Study Of Prognosis Indicators In The Treatment With Class â…¢ Malocclusion In Mixed Dentition By Using Ricketts Analysis

Objective: We want to filter the prognosis indicators of the mesiocclusion inmixed dentition by using Ricketts analysis method, which may also help us tounderstand the mechanism of the mesiocclusion and improve the success rate in themesiocclusion treatment. In contrast to other analysis methods, Ricketts analysis hasits unique advantages, such as growth forecast and prognosis judgement. There aretwo kinds of indicators(one is the decisive factor in malocclusion, the other is thefactor which can show the skull internal structure) which can help the orthodonticdoctors understand the pathogenesis of mesiocclusion, predict the treatment efficacyand formulate reasonable treatment plan eventually.Method: We choose28cases(13male cases;15female cases; their mean age is8.8years old) from the the orthodontic clinic in the stomatological hospital whichbelongs to Jilin University. The treatment plan we choose for the Angle Class IIIpatients whose maxillary development are insufficient is maxillary expansion traction.After this treatment, these patients’ upper and lower front teeth relationship hasreached to normal overbite and overjet. After1.5~2years follow-up, we divide thesepatients into three groups on the basis of the upper and lower teeth relationship:successful treatment group(upper and lower teeth has normal overjet and overbite；11cases), failure treatment group(upper and lower teeth relationship turns to reverseoverbite and overjet;12cases), no effect group(upper and lower teeth relationship ison the blade or shallow cover;5cases). We use18measuring indicators of Rickettsanalysis to measure and analyse all28cases and our statistical analysis method isvariance analysis and rank test.Result: In18measurements, after comparing the three groups, we find that thelength of the mandible，the facial slope and BaNaA angle has significant differencesin the statistical analysis. We can also see that the skewness of the skull base havecertain statistical significance in the comparison：the successful treatment group andthe combined group of other two.The length of the mandible has significant difference(P<0.05) in the varianceanalysis of three groups: the successful treatment group(80.86±6.64), the failuretreatment group(90.86±3.15), no effect group(88.27±8.19). It suggests that the shorterthe length of the mandible is, the better prognosis we will get. We find that the threegroups have significant statistical differences(P<0.05) through pairwise comparison. BaNaA angle has significant difference(P<0.05) in the variance analysis of threegroups: the successful treatment group(56.64±2.11), the failure treatmentgroup(60.04±3.69), no effect group(58.98±2.52). It suggests that the smaller theBaNaA angle is, the better prognosis we will get. We find that the successfultreatment group and the failure treatment group have significant statisticaldifferences(P<0.05) through pairwise comparison.The facial slope has significant difference(P<0.05) in the variance analysis ofthree groups: the successful treatment group(65.24±3.72), the failure treatmentgroup(61.19±3.64), no effect group(64.72±3.38). However, we find that the threegroups have no significant statistical differences through pairwise comparison.Patients in the failure treatment group and no effect group may have some oralbad habits, genetic factors and environmental factors, so we combine the two groups’data and name it combined group. Then we take statistical analysis to analyse themeasurements in the successful treatment group and the combined group. The lengthof the mandible and BaNaA angle still have statistical differences(P<0.05). Themeasurement of the skewness of the skull base also has statistical difference(P=0/05):the successful treatment group(27.59±4.06), the combined group(30.45±2.70).However, the facial slope has no significant difference.Conclusion: The length of the mandible and BaNaA angle in Ricketts analysiscan be used as prognosis indicators in the treatment of mesiocclusion in mixeddentition. The shorter the length of the mandible and the smaller BaNaA angle thepatient have, the better prognosis we will get. Likewise, the longer the length of themandible and the bigger BaNaA angle the patient have, the worse prognosis we willget. The facisl slope and the skewness of the skull base can be used as referenceindexes.