The Biomechanical Research Of Tip Back Bend Arch Wire And Richtts Arch Correcting Deep Overbite

Deep Overbite which often takes place in dentistry is often seen in clinic. Overbite means that maxilla and mandible in the vertical direction is malocclusion when teeth are in the central bite and uncentral bite. It is the relatively complex symptom in orthodontics clinic, and will seriously affect sufferer's jaw system, particularly chews and the language function will be seriously damaged; It also gives sufferer's body and mind the grave effect. But this malocclusion is more difficult in clinic, and its means is comparatively more unitary, more limited, longer time treatment ,which makes partly sufferer be forced to abandon treating and ceases to treat halfway. In the recent years, Multiloop Edgewise Arch Wire that is for short MEAW has been used in the clinical work which makes obvious progress all over the world since Doctor Kim deviced and succeeds in treating malocclusion with MEAW, and in recent years many orthodontic doctor also report different type of successful case of sufferer by application MEAW. MEAW has acquired obvious effect in over-bite.At present, tip back bend wire and Richtts arch wire are often used in correcting deep over-bite. The tip back bend includes terminal tip back bend and tip back bend which aimed to extrude molars and intrude incisor and prevent the inclination of the anchorage molar. So it used in correcting deep over-bite and the case that the anterior teeth should be put back. When the terminal tip back bend insert the buccial tube of the first lower molar, the wire is at the gingival direction of the premolar too. So it lead to no occlusion at theareas of the premolar. But some orthodontist are not aware of the problems. To verity the difference of the two situations the test is designed two conditions, conditionl: the premolars have brackets and the tip back bend wire is in the slots. conditon2: the premolars have no-brackets, it is the purpose to compare the difference of the two conditions.Richtts arch is often used in correcting deep over-bite, especially in correcting deep over-bite of adolescent early permanent dentition, another purpose of the test is to compare to the different forces produced by tip back bend arch wire and Richtts arch.Method is to put the tip back bend arch wire and Richtts arch wire on the standard model and measure the value of the force at the left lower incisor and the left lower molar in order to find the difference of the two arch wires.This dissertation emphasizes on the biomechanical research of tip back bend arch wire and Richtts arch in correcting anterior deep over bite. It consist of two part of substances .The first part is test stress analysis of tip back bend arch wire and Richtts arch in correcting anterior deep over deep bite; The second part is finite element imitation of tip back bend arch wire and Richtts arch in correcting anterior deep over bite. This two section separately depict the means of oral-mechanics research: test stress analysis and theory stress analysis that is finite element method.The first section applies electrical logging. It studies the stress distribution of deep over-bite sufferer's teeth and periodontal membrance which are on the function of tip back bend arch wire and Richtts arch, and compares to MEAW. The test tries to find the optimum, in the same time, Toverify whether it is eflfective to treat deep over-bite case with tip back bend arch wire and Richtts arch, the three-dimensional finite element(TDFE)models of the lower left central incisor and first molar and theirs periodontal ligament and alveolar bone were set up by means of CT. by comparing the stress distribution in root periodontal ligament and alveolar bone, and the tendency of the incisor and the molar movement under different orthodontic forces to find the difference of the tip back bend and the Richtts arch wire.Test Snd:(l) The molar model revealed that the tensile stress concentration is at the mesial root cervix and the compressive stress are at the distal root cervix. It get extruding force, buccal force and tend to tip distsally mesio-buccally. (2)The incisor model shows that the tensile stress was concentrated at the lingual cervix and the compressive stress concentration are at the apical tip .The arch wire exerted intruding force, lingual force and the incisor tend to lingual movement and intruding movement, so tip back bend arch wire and Richtts arch produced a complicated force system which contain many direction forces and movements.From the result of the test, conclusion can be drawn:1 the tip back bend arch wire which does not bonded the bracket of the premolar produced the force is similar to the multi-loop edgewise arch wire. It exert bigger force than the arch wire bonded the bracket of the premolar on incisor. It can intrude the incisor effectively, the tip back bend arch wire bonded the bracket .of the premolar has bigger force than the arch wire which does not bonded the bracket of the premolar on molar. It can extrude the molar effectively. But the angle must be controlled for fear that anchorage lost.2 Richtts arch wire produced the force is similar to the multi-loop edgewise arch wire. It can be used in correcting the deep over bite.3 The system of stress distribution ofroot > periodontal ligament and alveolar bone is complicated when applied by tip back bend arch wire and Richtts arch wire and the tensile stress and the compressive stress exist alternationally.4 When tip back bend arch wire bonded the bracket of the premolar, the mesial root of molar has the tendency of extrusion and the distal root of molar has the tendency of intrusion; when tip back bend arch wire does not bonded the bracket of the premolar, the mesio-distal root has the tendency of intrusion.5 The value of force of the molar and its periodontal tissue applied tip back bend arch wire which bonded the bracket of the premolar is bigger than the value of force of the molar and its periodontal tissue applied tip back bend arch wire which do not bonded the bracket of the premolar; however, The value of force of the incisor and its periodontal tissue applied tip back bend arch wire which bonded the bracket of the premolar is smaller than the value of force of the incisor and its periodontal tissue applied tip back bend arch wire which do not bonded the bracket of the premolar, except for the value of the alveolar bone.6 No matter whether tip back bend arch wire bonded the bracket of the premolar, the molar has the tendency of movement of mesio-buccial and disto-lingual rotaion and distal tipping movement the incisor has the tendency of intrusion and lingual tipping movement.7 The value and the distribution of stress of molar and incisor applied Richtts arch wire is similar to the value and the distribution of stress of molar...