The Effect Of Tooth Agenesis On Craniofacial Structure

In clinical work, it's very common to meet young patients with teeth absence. With the evolution of human being, the proportion of people with tooth agenesis is becoming more and more larger. Now, the effect of teeth agenesis on development of craniofacial structure and counter effect have not come to a conclusion. This research got a quantitive knowledge of the development condition in patients with teeth agenesis through cephalometric analysis and plaster model measurement of normal people and teeth agenesis patients from north-west of China. Based on the result of cephalometric analysis and plaster model measurement of teeth agenesis patients, patients were distributed to three groups (mild, moderate and severe). To make a reference for clinical work Statistic analysis were carried out to make an analysis of characterizes and parameters.Part one: The effect of tooth agenesis on craniofacial structure and soft tissueIn order to investigate the effect of tooth agenesis on craniofacial structure development, we analyzed the cephalometric data of persons with tooth agenesis. 60 patients with tooth agenesis in the Department of Orthodontics were chosen and were madecephalometric analysis. The results were showen as followed:1. In the patients with mild tooth agenesis, the main hard and soft tissue parameters were showen below: SNA 82.6+3.9° (contraty to 82.8 + 4.0° in normal); SNB 80.0 + 3.2° (contraty to 80.1 ±3.9° in normal); ANB 2.6 +1.8° (contraty to 2.7±2.0° in normal); Y-axis angle 65.8 + 6.59° contraty to 66.3 + 7.1° in normal); ANS-Ptm 51.8 + 2.4mm(contraty to 52.1+2.8° in normal); L1-MP 为 90.9 + 5.5° (contraty to 93.9±6.2° in normal); U1-L1 为 128.3±6.5° (contratyto 124.2 + 8.2° in normal); UL—H 为 0.1 ±2.2mm(contraty to 0mm in normal). That was to say the changes of hard and soft tissue parameters were limited with few numbers of tooth absence (P>0.05).2.In the patients with moderate tooth agenesis, the changes of main hard and soft tissue parameters were showen below: SNA, ANB, Y axis angle, ANS-Ptm, L1-MP, U1-L1, UL-H were 80.1 ±3.6 ° , 1.8±2.0° , 63.8±6.9° , 51.7±3.1mm, 89.6±6.1° , 131.1± 7.2° , —0.5±2.1 mm, respectively, which showed significant difference (P<0.05).3.In the patients with severe tooth agenesis, the changes of main hard and soft tissue parameters were showen below: SNA, ANB, Y axis angle, ANS-Ptm, L1-MP, U1-L1, UL-H were 74.2±7.8° , 0.4 ±3.0° , 60.1 ±7.8° , 46.8±3.0mm, 86.3±7.9° , 136.5±8.7° , -2.8±2.2mm, respectively, which showed great significant differenceIn conclusion, tooth agenesis would affect the development of maxillary bones, while had little effect on development of mandibular bone which might have little anticlockwise rotation.Part two: plaster model analysis of the effect of tooth agenesis on occlusion developmentCongenitally teeth missing can directly cause a series of occlusion deformities, such as asymmetry of dental arch, abnormal gaps between teeth, malocclusion and crowding of opposite denture. Because of it's complexity in clinic, beside consideration of the harmonious number of teeth on both arches, it should be take more care of the rebuild of normal relationship of occlusion. The correct treatment to tooth agenesis is one of the most important works in clinics, as a satisfactory result can be approved by it. In this study, 60 patients' plaster models were surveyed by arch length, arch width, over bite, over jet, depth of palate. All parameters were analyzed by statistics method. The results were showen as followed:1. In the patients with mild tooth agenesis, parameters were showen below: WUA in front 35.4+1.8mm(contraty to 35.9 + 1.6mm); WUA in mediume 38.2±2.1mm(contraty to 38.8 ±1.9mm in normal); depth of palat 17.6 ± 1.7mm(contraty to 18.1 ± 1.6mm in normal); overbite 2.3 ± 1.1mm(contraty to 2.1 +0.8mm in normal); overjet 2.4+ 1.0mm(contraty to 1.9 + 0.9mm in normal). That was to say the changes of occlusion, the width and length of maxillary arch, overjet and overbite were not obvious.2. In the patients with moderate tooth agenesis, except that WUA in medium (35.8 ± 2.2mm) showed significant difference to normal number(P<0.05), WUA in front(35.0±2.1 mm), depth of palat(17.0± 1.3mm), overbite(2.6±1.3mm), overjet(2.5±1.2mm)had little diffence to mormal.