Background: Orthodontic tooth movement occurs due to bone resorption and apposition on the pressure and tension side of the PDL. The transcription factors associated with osteoclast differentiation are NFATc1 while osteoblast differentiation is associated with RUNX2. The optimum force of orthodontic tooth movement can move the teeth to the desired position, without causing discomfort and tissue damage to the patient. Objective: This study aims to analyse the effect of gradually increasing force on orthodontic tooth movement (by evaluating the NFATc1 and RUNX2 expression) in rats. Methods: This research is an in vivo experimental study with a post-test control group design. Twenty-eight healthy male adult Wistar rats (Rattus novergicus) aged 4-5 months with body weights 200-250 g rats were divided into seven study groups. Treatment groups in this study are given the force (by applying a closed coil spring between the maxillary central incisor and the maxillary first molar) of 5 g, 5-10 g, 10 g, and 10-20 g with the duration of treatment in 14 and 28 days. After the treatment day was finished, the alveolar bone tissue was isolated and investigated by immunohistochemical methods. Results: Indicate a significant difference between the control and all treatment groups of NFATc1 (p=0.003; p=0.000; p:0.010; p=0.001; p=0.001; p=0.000) and RUNX2 with groups of 10 g/14 days, 10 g/28 days, 5 g/28 days, 10 g/14 days,10-20 g/28 days (p=0.001; p=0.000; p=0.000; p=0.017; p=0.014; p=0.000) values. Conclusion Gradually increasing force affects orthodontic tooth movement by inducing bone resorption (high expression of NFATc1) in the pressure area and bone apposition (high expression of RUNX2) in the tension area. Applying heavy force by initially applying light force could inhibit hyalinization.
Orthodontic Tooth Movement ; Tooth Movement Techniques

It is important to understand the operating mechanism and force system of fixed appliance that most effective for individual tooth movement in various orthodontic appliances. The arch wire system of fixed appliance is devided into 3 types, which is continuous arch, segmented arch and sectional arch. The last two types have longer interbracket distance and simple force operating points, so it is easy to control force system by operator. But the continuous arch has shorter interbracket distance and various bracket geometry, so it is hard to control and anaylze the force system. The purpose of this study was three dimentional force and moment analysis of continuous arch system by finite element method, which is similar situation to three dimentional elastic beam in structural engineering. Several sample form of various bracket geometry and artificial lower crowding typodont made by author were constructed, analyzed and compared each other. The results were as follows: 1. The force magnitude is linear proportional to the degree of displacement or tilting of the bracket. 2. The force magnitude is inversely non-linear proportional to the interbracket distance. 3. In three dimensional typodont model, while the force can be compared with that of the sample form in the area where adjacent bracket geometry is simple, the force is much more than the expected value in the area where adjacent bracket geometry is complex.
Crowding ; Orthodontic Appliances ; Tooth Movement

Patients who have a moderate periodontitis with pathologic tooth migration of maxillary incisors, it is necessary not only periodontal treatment for reduce periodontal inflammation, but also orthodontic treatment to teeth repositioning. For orthodontic treatment, it is necessary to apply less force and careful considerations of the center of resistance of the tooth and optimal force of tooth movement. At this time, the segmental arch applied only to the target teeth, is more effective and predictable, because applied force and direction can be controlled. In addition, to design the orthodontic appliance that can prevent the unwanted tooth movement that used as an anchorage is important. In recent years, various types of skeletal anchorage system have been used for preventing loss of the anchorage. We reported the patient who had extruded maxillary central incisor due to pathologic tooth migration, treated by a successful periodontal-orthodontic multidisciplinary treatment using an orthodontic appliance designed to apply less traumatic force and reduce an anchorage loss.
Humans ; Incisor ; Inflammation ; Orthodontic Appliance Design ; Orthodontic Appliances ; Orthodontic Wires ; Periodontitis ; Tooth ; Tooth Migration ; Tooth Movement

The bracketless invisible aligner technique has been considered as a new developed orthodontic technique since its appearance during the period of late 1990s. It is characterized with the advantages of more aesthetic, comfortable, simple, high-efficient and predictable compared with current traditional orthodontic techniques depending on brackets and wires for orthodontic tooth movements. There have been many opportunities for further development and clinical application for the technique with the developments of material sciences, computer software and hardware technology, rapid prototyping techniques, et al. Nevertheless, kinds of difficulties and challenges have been and should be met either at present or in the future for this relatively new technique which just occurred around 10 years ago. The histories, developments with opportunities and challenges and prospects of the technique will be reviewed and discussed in this paper.
Humans ; Orthodontic Appliances ; Tooth Movement Techniques

It is to address torquing an individual tooth using a gate spring. The gate spring is made of a rectangular stainless steal wire, in the shape of a gate, which is incorporated to the archwire by spot welding. Torque is generated by the combined effects of the gate spring and the archwire. After 2-3 months, the gate spring can obviously torque individual tooth.
Orthodontic Appliance Design ; Orthodontic Brackets ; Orthodontic Wires ; Tooth ; Tooth Movement Techniques ; Torque

Guiding a tooth along an arch wire results in a counteracting frictional force among arch wires, bracket and ligature. This frictional forces should be eliminated or minimized when orthodontic tooth movement is being planned. The purpose of this study was to evaluate the changes of width, cross-sectional forms and surface morphologies of stainless steel wire and Elgiloy(R)wire after electropolising. Experimental variables included in this experiment were arch wire materials, current, electrolyte temperature and polishing time. Wire widths were measured by micrometer and cross-sectional forms and surface morphologies were examined with optical microscope and scanning electron microscope. The results were as follows: 1. The mean and standard deviation of widths of stainless steel wire and Elgiloy(R) wire varying polishing time with condition of 249A/dm2 and 20degreesC, 249A/dm2 and 25degreesC, 332A/dm2 and 20degreesC and 332A/dm2 and 25degreesC were obtained. 2. With increasing polishing time, the widths of stainless steel wire and Elgiloy(R) wire became decreased proportionally. 3. The changes of widths of stainless steel wire and Elgiloy(R) wire were statistically insignificant between 20degreesC group and 25degreesC group. but significant between 249A/dm2 group and 332A/dm2 group. 4. The cross-sectional forms of wire after electropolishing were not changed in stainless steel wire, and while it were changed to rounded corners in Elgiloy(R) wire. 5. The surface morphologies of wire after electropolishing were scratch-absent and more smoothened both in stainless steel wire and Flgiloy(R) wire.
Friction ; Ligation ; Orthodontic Wires* ; Stainless Steel ; Tooth ; Tooth Movement

Despite orthodontic treatment(tooth moving) is dynamic act, many orthodontists have used mainly static evaluation method for evaluating effectiveness of the orthodontic appliances. They want to find which is better appliance, especially in the treatment results and treatment period, when they chose one appliance from sugessted appliances for obtaining same treatment goal. The author and colleagues invented and manufactured new machine for getting information about the relative effectiveness from many suggested orthodontic appliances and we named it Calorific machine. We used this Calorific machine to find the relative differences about tooth moving mechanism and tooth moving time between the Burstone's PLA(single force mechanism) and Molar-up's PLA(couple mechanism) for correcting the posterior cross bite. We measured the distance of tooth moving on the occlusal X-ray film and recorded the moving time of the anchored(control elct o-thermal tooth) and lingually tipped lower second molars(experimental electro-thermal tooth) and then processed paired t-est by SAS program The results were as follows. 1. Molar-up's PLA showed more extrusive and horizontal movement than Burstone's PLA at the lingually tipped molar(p=0.0000). 2. There is no finding of tooth movement by Molar-up's PLA at the uprighted molar(p=o.3475) but Burstone's PLA showed a little change(02 mm) at the same molar(p=O.0001). 3. Burstone's PLA took 17.8 minutes for tooth moving but Molar-up's PLA took only 3.8 minutes(p=0.0001)
Malocclusion ; Orthodontic Appliances ; Tooth Movement ; Tooth* ; X-Ray Film

Dr. Youn-Sic Chun and coworkers invented the new machine for getting information about the relative effectiveness of the orthodontic appliances and we named it Calorific machine. The author and colleagues used this machine to compare with tooth moving mechanism by 3 types of the insertion method of precision-TPA for derotating the posterior teeth. We measured the distance of tooth movement and found out the rotational center on the occlusal X-ray film and the tooth movement on the occlusogram and then processed paired t-test by SAS program. The results were as follow : 1. In the intermolar width, the mesial insertion method showed the loss of distance, and the other methods(-distal insertion method, mesial expansion method-) showed the increase of distance. 2. In the arch length, the distal insertion method was exhibited as most recommandable way for increasing the arch length. 3. The rotation center of the mesial insertion method for derotating the molar, was located between mesial pit and central pit of the lower 2nd molar. and, in the distal insertion method, it was located between distal pit and distolingual cusp, and in the mesial expansion method was located at distal pit.
Molar ; Orthodontic Appliances ; Tooth Movement ; Tooth* ; X-Ray Film

OBJECTIVETo investigate the movement tendency of lower teeth using multiloop edgewise archwire (MEAW) with vertical elastics in anterior teeth area by three-dimensions photoelastic analysis.

METHODSThe photoelastical model of full teeth as human body on physical parameter and dimension was established and loaded by MEAW with vertical elastics in anterior teeth area similar with clinic. Every freezing model-tooth was bladed by anteroposterior axes and vertical axes, the stress of every point of alveolar bone was calculated by three-dimensions shear-equation method. The stress distribution regularity of per-tooth was analyzed to describe their move tendency.

RESULTSThe lower second molar was intrused and rotated to distal and inclined as negative torque. The lower first molar moved and rotated to distal, the mesial rotate to buccally and the distal rotate to lingually. The lower second pre-molar was extruded and inclined as crown to mesial and root to distal, inclined as negative torque. The lower canine was intrused slightly and inclined as positive torque. The lower lateral incisor was extruded and moved and inclined as positive torque.

CONCLUSIONUsing MEAW with several "L" loop can control the movement of every tooth in three dimension.

Tooth movement would be impeded by frictional force arised between archwire and tube, bracket or elastics in the fixed orthodontic appliances, which could be changed variably by such several factors as the contact area, normal (perpendicular) force and the condition of contact surface. There were many literatures about frictional force in the orthodontic region, but different results were obtained from little controlled research so that was very difficult in clinical application. Therefore we have reviewed comprehensively previous literatures about frictional force and thus several results were obtained as follows: 1. For use species of the orthodontic wire, frictional force was influenced mainly by surface roughness of wire in the absence of binding, while that was influenced mainly by normal force in high binding angulation. 2. For the cross-section and diameter of the wire, the contact area influenced mainly on frictional force in the absence of binding, while wire stiffness influenced mainly on frictional force in high binding angulation. 3. The greater the bracket width, the greater frictional force, and frictional force of the plastic bracket was larger than that of the metal bracket. 4. For ligation type, frictional force of the stainless steel ligation was larger than that of the elastic ligation, and frictional force was directly proportional to ligation force. 5. Variable frictional force were occured from the saliva combined with such another factors as normal force and mode of surface oxide et al.
Friction* ; Ligation ; Orthodontic Appliances* ; Orthodontic Wires ; Plastics ; Saliva ; Stainless Steel ; Tooth Movement* ; Tooth*