The Clinical Significance Of The Angle Between Anterior And Posterior Occlusal Plane(AOP-POP)

Objective:To study clinical significance of the angle between anterior and posterior occlusal plane (AOP-POP).Materials and Methods:The experiment was based on 127 study cast and head positioning lateral X-ray of firstly diagnosed patients. We measured gingival inward angle between anterior and posterior occlusal plane in maxillary, occlusal inward angle between anterior and posterior occlusal plane in mandible, with universal protractor.We made self matching T test for the left and right side in the same jaw, multiple comparisons and coefficients with variation source of age, angle of MP/SN and MP/FH, inclination of incisors, Angle's classification, overbite and overjet.At last, we made the coefficient between spee's curve and AOP-POP in mandible, to discuss the correlation of AOP-POP and overbite, the degree of overbite by the normal mind isl, deep overbite I was 2, deep overbite II was 3, open bite I was-1, open biteⅡwas-2, open bite III was-3, we did the analysis of correlation between overbite and spee's curve, upper AOP-POP, lower AOP-POP, difference of upper and lower AOP-POP; to exclude the interference of factors with each other, we made linear regression in which the dependent was overbite, the independents were spee's curve, upper AOP-POP, lower AOP-POP and difference of upper and lower AOP-POP, with progressive method(step wise), with p<0.05 as the base into the regression equation, p> 0.1 for the baseline variables removed, to establish the best regression equation.Results:1. Self matching T tests reveal that there is no significant difference in left and right side(p>0.05), the correlation coefficient of left AOP-POP and right AOP-POP in maxillary was 0.654(p<0.01), the correlation coefficient of left AOP-POP and right AOP-POP in mandible was 0.703(p<0.01).2.Multiple comparisons reveal that there are significant differences in different ranks of over bite in maxillary and mandible (p<0.01); and there are significant differences in different ranks of age in maxillary (p<0.01).3.Comparisons of the mean with each other illustrate that there are significant difference between 12-16 years and dentition period, more than 16 years old at AOP-POP in maxillary and mandible;AOP-POP in maxillary in open bite patients is smaller than other groups(p<0.01),but there is no significant difference in groups of deep over biteⅠ,Ⅱ,Ⅲand normal(p>0.05), the group of open bite is165.40±1.64°,normal is 172.29±1.94°, deep overbite Iis 169.36±1.23°, deep overbite His 170.99±1.00°, deep overbiteⅢis 170.35±1.39°;AOP-POP in mandible in open bite patients is larger than other groups(p<0.01), there are significant differences in different ranks of overbite, the group of open bite is 171.91±1.61°, normal is 167.29±2.09°, deep overbite I is 169.16±1.30°, deep overbite II is 166.89±1.03°, deep overbiteⅢis 163.40±1.54°,and the tendency is the deeper over bite, the smaller AOP-POP in mandible;AOP-POP in mandible with low angle of MP/SN or MP/FH is smaller than the high and mean angle(p<0.05),the group of lower angle is 165.89±1.53°,mean is 168.01±0.94°, higher angle is 169.31±0.94°,and the tendency is the lower angle, the smaller AOP- POP in mandible;There is significant difference in different ranks of overjet (p<0.05), but there is no indeed tendency.4.Coefficient analysis reveal that there are negative correlation between the inclination of incisors (P<0.01),MP/FH(P<0.05) and AOP-POP in maxillary, there is negative correlation between over bite(P＜0.01) and AOP-POP in mandible, and positive correlation between MP/FH and AOP-POP in mandible(P<0.05).5. It's significant correlation between spee's curve and AOP-POP in mandible. Correlation analysis reveals that it's positive correlation between overbite and lower AOP-POP, spee's curve, difference of upper AOP-POP and lower AOP-POP. Linear regression equation is y=1.703+0.149x,the independent x is difference of upper AOP-POP and lower AOP-POP. R square of equation is 0.348, which means change of difference of upper and lower AOP-POP induces 34.8%change of overbite.Conclusions:1.There is a high degree of consistency between spee's curve and AOP-POP in mandible; AOP-POP fully reflects the occlusion curvature; in 3 factors of lower AOP-POP, spee's curve, difference of upper and lower AOP-POP,the last one is the most significant factor influencing overbite.2. There is negative correlation between AOP-POP and inclination of incisor in maxillary. AOP-POP in maxillary correlates with MP/FH negatively; it's negative correlation between overbite and AOP-POP in mandible, it's positive correlation between MP/FH and AOP-POP in mandible.3. Little AOP-POP in mandible is related with anterior and upper trend in mandible, and little AOP-POP in maxillary is related with posterior and inferior trend in mandible; patients with little AOP-POP in maxillary and large inclination of incisor in maxillary are prone to open bite.4. Using AOP-POP for the curvature of occlusion in certain open bite patients, will quantify the degree of jaw uncoordinated.Overall, AOP-POP will be useful for clinical guiding.