Study On The Effect Of Adenoid Hypertrophy On The Morphological Development Of Mandible In Adolescents With Different Vertical Facial Types Of Class Ⅱ Malocclusion

Objective:Three-dimensional reconstruction of CBCT data was performed by using Mimics21.0in this study,and three-dimensional measurements of mandibular angles,linear and chin morphology and other related indexes were performed by using Invivo5.0 software to investigate the effect of adenoid hypertrophy on the development of mandibular morphology in adolescents with different vertical facial types of Class II malocclusion,and to provide clinical treatment for patients with different vertical facial types of adenoid hypertrophy theoretical basis.Methods:104 experimental subjects were collected.CBCT data were selected for three-dimensional reconstruction of the experimental subject models of 52 Class II malocclusion adolescents with adenoid hypertrophy and 52 Class II malocclusion adolescents without adenoid hypertrophy at the time of consultation,correcting the head position and determining the three-dimensional reference planes of the Frankfort horizontal plane,middle sagittal plane,and coronal plane.104 subjects were divided into different vertical bone facial type groups according to FH-MP angle and whether the adenoids were hypertrophic or not: adenoid hypertrophy homogeneous angle group(28),adenoid hypertrophy high angle group(24),non-adenoid hypertrophy homogeneous angle group(26)and non-adenoid hypertrophy high angle group(26).Twenty-three relevant indices such as mandibular angle,linear and chin morphology were measured based on Invivo5.0three-dimensional model and all data were statistically analyzed.Results:1.Adenoid hypertrophy had a significant effect on mandibular morphogenesis in Class II malocclusion high angle adolescents(P<0.05)and a lesser effect on mandibular morphogenesis in Class II malocclusion homogeneous adolescents(P>0.05).2.The differences in the horizontal,coronal and vertical openness of the mandible in relation to the skull,such as ∠Go R-Pog-Go L,∠Go R-N-Go L,∠Co-Go-Me and ∠Co L-Co R-Go R/ ∠ Co R-Co L-Go L,were statistically significant(P<0.05)in the hypertrophic hypergoniacal cases compared to the non-hypertrophic Class II malocclusion hypergoniacal cases.Suggesting that it would increase the opening of the mandible relative to the skull in hypertrophy of adenoids in hyperangular cases accompanied by adenoid hypertrophy.While mandibular angle width Go R-Go L,mandibular volume length Co-Pog,mandibular body length L-a and mandibular branch length L-b,which differences were statistically significant(P<0.05),indicating that the trend of mandibular growth and development was that mandibular angle width,mandibular body length and mandibular volume length became larger and mandibular ascending branch length became smaller in the adenoid hypertrophy high angle group patients.The difference in chin height B-Me and chin thickness C-C′ were statistically significant(P<0.05),indicating an increase in chin height,which is a decrease in chin thickness and mainly posterior chin thickness compared to non-adenoidal hypertrophy in hyperangular cases in adenoidal hypertrophy.3.The differences in the development of mandibular opening relative to the cranium,mandibular length and width,and mandibular ascending length and width were not statistically significant(P>0.05)compared with non-adenoidal hypertrophy in Class II malocclusion homogeneous cases,indicating that adenoidal hypertrophy had less effect on the development of the vertical direction of the mandible and the development of the length and width of the mandible itself in homogeneous cases;The difference in chin thickness C-C′ chin morphology was statistically significant(P<0.05),indicating that a reduction in chin thickness occurred.Conclusion:1.The trend of adenoid hypertrophy on the development of the mandible in adolescent Class II malocclusion high angle cases is: the vertical opening of the mandible becomes larger,the mandibular ascending branch becomes shorter,the length and width of the mandibular body becomes larger,the mandible undergoes clockwise rotation,the height of the chin increases in the chin morphology,and the thickness of the chin decreases which is produced to compensate for the changes in the growth of the mandible.Therefore,early need to lift the cause as soon as possible,strict control of the vertical to the height in the later treatment,to control the lower anterior teeth torque because of the reduction in chin thickness occurs in the movement of teeth,to avoid the emergence of bone open window or bone cracking due to improper control when the clinical treatment of adenoid hypertrophy of the Class II malocclusion high angle cases.2.Adenoid hypertrophy has less effect on the vertical development of the mandible for Class II malocclusion homogeneous angle cases,there is no significant effect on the development of the mandibular body or the mandibular ascending branch,but a certain degree of reduction in chin thickness still occurs,and these suggest that the growth and development should be regularly monitored in the clinic for such patients,attention should also be paid to the root torque movement of the teeth.3.Adenoid hypertrophy is closely related to the development of the mandible in adolescents with different vertical facial types of Class II malocclusion.Therefore,in addition to the tendency to consider the effects of adenoid hypertrophy in clinical practice,it is also necessary to consider the patient’s actual situation in a comprehensive manner.The reason is that mandibular growth is also affected by muscles,condyles growth and bad habits.