An Imitated Experimental Study Of The Effect Of Tooth Size Discrepancy On Occlusion

[Objection]The clinical orthodontic treatment is in order to obtain an excellent occlusion .It is claimed to be difficult to be obtain an excellent occlusion if the maxillary tooth size discrepancy (TSD) .In 1958 Bolton introduced overall and anterior tooth size ratios ,which were supposed to be helpful in diagnosis and treatment to express the coordinator of the mesiodistal tooth size of the maxillary and manidibular arch. Determined tooth size ratios may predict the excellent occlusion; may predict the functional and esthetic outcome of the case. TSD is general in orthodontic cases according to the Bolton ratios.The purposes of this experimental study are the following: to study the effect of TSD on occlusion, (l)Whether TSD always affect the final orthodontic treatment outcome, (2)Whether the change of the inclination and angulation of the teeth beyond normal can solute the question cased by TSD, (3) To test and verify the feasibility of resolving TSD issue in orthodontic clinic in order to offering the basis for the patient bevy with TSD for better plan of cure. (Material and Methods]1.The orthogonal experimental design and analysis of variance are used to study the effect of multiplex element on PAR.2.An attempt has been made to establish ideal setup situations. In cases with TSD can be made to compensate for the discrepancy. We have chosen to establish ideal occlusions in the buccal segment (Class I) > better anterior occlusion and compromise on the inclination and angulation of teeth.3. According to overall and anterior tooth size ratios in Shanghai, they are 90.99% + 1.70% and78.36%?.18%. The PAR index (Peer Assement Rating) was used to score the occlusion on setup. To study the effect of artificially created TSD on occlusion in setup, two part of the study were carried on. [Results]1. It is showed that the PAR ranking did not coincide with the TSD values as a result of the effect of TSD on PAR values; F005(2]18) =3.55, the analysis of statistically means no statisticallysignificant difference beaten overall > anterior tooth size ratios > overbitex the relationship of molar and occlusion (P^O.05) .2. It is showed that the PAR ranking did not coincide with the TSD values as a result of the effect of TSD on PAR scores after ; F005(2i4) =6.94, the analysis of statistically indicates statistically significant difference beaten overall -, anterior tooth size ratios > overbite^ the relationship of molar and occlusion (P^O.05) .3.The analysis of statistically means that the patient bevy whose overall tooth size ratios inside 2SD and overall tooth size ratios beyond 2SD with anterior tooth ratios inside 2SD can obtain less PAR score through compensation of tooth axes .[Conclusion]1. Only considering the effective of TSD on occlusion will be TSD the outcome of the final occlusion, it will affect on occlusion.2. On the occasion of compensation of tooth axes, the effect of TSD on occlusion appears to be limited. The differential TSD patient bevy whose overall tooth size ratios inside 2SD and overall tooth size ratios beyond 2SD but anterior tooth ratios inside 2SD can obtain better effective with selecting the compensation of tooth axes.3. The offering of academic basis for better treatment for the differential TSD patient bevy whose ratios beyond ideal, it ishelpful to advance the clinical orthodontic treatment, and plays a practical role in clinical orthodontic treatment.