A study on the effect of the magnitude of the gable bends on the tooth movement pattern during en-masse space closure in the maxillary dentition / 대한치과교정학회지

The purpose of this experimental study was to determine appropriate magnitude of the Gable bends to produce maximum retraction of the anterior teeth. The Calorific Machine was used to illustrate the tooth movement in three dimension. The experimental teeth except the first premolar were embedded in the artificial alveolar bone part. In a series of experiments, the extraction space was closed using arch wires with bull loops into which the gable bends of 10degrees, 20degrees, 30degrees degrees were incorporated. The experiments were repeated three times for each degree of the gable bend. Before and after the space closure, radiographs were taken in the sagittal and occlusal directions using occlusal films. Analysis of variance and Scheffe post hoc test were used to determine significant differences among the three groups. The following results were obtained. 1. As magnitudes of the gable bends increased, more bodily anterior tooth movement was seen and the distance of retraction also increased. 2. As magnitudes of the gable bends increase, the amount of posterior tooth protraction decreased while intrusive and buccal movement increased. 3. The arch was coordinated by distal-in rotation of the canine and mesial-in rotation of the second premolar adjacent to the extraction space.

Spatial changes of the maxillary molar following unilateral derotation with the precision TPA / 대한치과교정학회지

The purpose of this study was to evaluate the spatial changes of mesial-in rotated maxillary molar and opposite anchor tooth during derotation by the precision transpalatal arch (TPA) with the use of a new typodont simulation system, the Calorific machine system, which was designed to observe the whole process of tooth movement. The maxillary right first molar was used for the anchor tooth and the maxillary left first molar was used for the mesial-in rotated tooth, and the angle of rotation was increased to 20, 40, and 60. A passive precision TPA was fabricated and then activated by bending the left arm to 20, 40, and 60. Each experiment was repeated five times under the same conditions and analyzed by ANOVA and Tucky's Studentized Range (HSD) test. In the occlusal plane, when the bending angle of precision TPA was increased, the mesiobuccal cusp of the rotated molar moved more buccally (p<0.001) and less distally (p<0.001) while the distolingual cusp moved in the mesiopalatal direction. In the sagittal plane, the palatal roots of the derotated molar moved mesially (p<0.001). In the traverse plane, the derotated molar showed slight extrusion (p<0.001). The upper right first molar, which was used as an anchor tooth, showed clinically insignificant movement across all three planes.

An experimental study on the dynamic tooth movement of two molar uprighting spring by calorific machine / 대한치과교정학회지

The aim of this investigation was to evaluate the differences of two canti-lever springs by using a new simulation system. This was done using a Calorific machine that compared crown uprighting spring and root uprighting spring. The Calorific machine was designed to allow observation of the whole process of tooth moving, and it composed of three parts(a temperature regulation system, electro-thermodynamic teeth, and an artificial alveolar bone component). The obtained results wee as follows. 1. Distal and buccal movement of the anchor teeth were observed greater in the root uprighting spring than the crown uprighting spring. 2. Crown uprighting spring showed distal movement of the crown of lower second molar for 3.29mm but root uprighting spring showed only 1.68mm. 3. Crown uprighting spring exhibited forward movement of mesial and distal root of the lower second molar for 3.91mm, 3.60mm but the root uprighting spring showed 6.76mm, 6.26 mm.

An experimental study on the dynamic teeth movement of 3 types of the insertion method of Precision-TPA for derotating the posterior teeth / 대한치과교정학회지

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.

A comparative study of roughness of enamel surface to various interdental enamel stripping methods in vitro / 대한치과교정학회지

Interdental enamel stripping is an usual method for correction of abnormal tooth shape and tooth size discrepancy which is one of the etiologic factors of malocclusion. Clinically it is useful to correct the minor crowding in anterior teeth and posterior occlusion during finishing stage of orthodontic treatment. But this procedure has risks such as irreversible tooth reduction and remaining roughness of enamel surface can accumulate plaque which can evoke periodontal problem. Even if various methods were introduced to minimize the enamel surface roughness, their evaluation was limited in morphologic differences by scanning electronic microscope(SEM). The purpose of this study was to compare the various interdental enamel stripping method by SEM and to quantify the difference of surface roughness by use of Surfcorder SEF-30D(Kosaka Lab. Ltd.) which can measure the roughness of surface. The stripping methods were divided into mechanical and mechanical-chemical method. Air-rotor stripping and separating strip were used for mechanical stripping and 37% phosphoric acid was used for chemical stripping. The enamel surface roughness after mechanical or mechanical-chemical stripping of interproximal surfaces of premolars which were extracted for orthodontic purpose were measured and compared by means of SEM and Surfcorder(R), the results were as follows. 1. Enamel surface of primary treated by coarse diamond bur and separating strip groups showed highest value of roughness. 2. To compare the primary treated groups between mechanical and mechanical-chemical method, the latter group showed lower value of roughness remarkably. 3. Mechanical stripping groups which were treated both coarse and fine instrument showed lower value of roughness as much as non treated group. 4. The use of pumice for final polishing did not show significantly smoothening the stripped enamel surface any more.

A clinical study on anchorage control of molar anchoring spring(MAS) during retraction of the maxillary canine / 대한치과교정학회지

In maxillary canine retraction by means of sliding mechanics, we designed MAS(molar anchoring spring) to prevent anchorage loss and uncontrolled tipping of tooth movement and have applied it in clinical cases. The anchorage control of the maxillary first molar and type of tooth movement of the maxillary canine were studied in 31 subjects. The measurements were made on cephalograms, orthopantomograms and dental casts. The obtained results were as follows. 1. In case of the maxillary first molar, there was a little sagittal anchorage loss, but there was no vertical & transverse anchorage loss. 2. In case of the maxillary canine, there was distal tipping movement and also there was a little intrusion tendency.

An experimental study on the dynamic tooth moving effects of two precision lingual archs(PLA) for correction of posterior scissor bite by the calorific machine / 대한치과교정학회지

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)

Mitogenic effects of nicotine to human periodontal ligament(PDL) cells in vitro / 대한치과교정학회지

Nicotine is one of the major components of cigafette smoking which causes various systemic and local diseases to human body. Mitrogenic effects of nicotine to systemic disease are interesting factors in the results of cellular proliferation especially to vascular and pulminary tissus or cells. The study of local effects concerns with destruction of tissue and delayed healing rate after various surgicla treatment. Platelet-Derived Growth factor(PDGF) and Insulin-like growth factor(IGF) are known as major mitogens to human PDL cells. The purpose of this studywas to investgate the mitogenic effects of nicotine to human PDL cells. We studied the expression of PDGF-alpha receptor, PDGF-betareceptor, and IGF-1 receptor mRNA form the nicotine treated human PDL cells by northern analysis. The experimental groups were divided into different serum(1%, 10%) and nicotine(100ng/ml, 1000ng/ml) condentrations and each group was studied by time course. The results of this study showed upregulation of PDGF-alpha, beta receptor and IGF-1 receptor mRNA at 100ng/ml nicotine concentration and 10% serum group to the time course. These results suggest that physiologically attainable nicotine concentrations may stimulate mitogenic gene synthesis to human PDL cells in vitro.

Growth change in the lips of the adolescence (from 8 to 16 years old) / 대한치과교정학회지

This study was undertaken to assess the effect of growth on the lips. Not only does lip growth influence the stability of such orthodontic treatment: it also directly influence facial profile, in which the lips have an important part. An understanding of the growth of lips is thus central to a consideration of profile change in orthodontics. By analyzing the serial lateral cephalograms of 15 male and 15 female of 8 years old to 16 years old who have normal occlusion. The result of this study were summerized as follows; 1. The largest growth increments in the length of the lips was occured age of 14 in both sexes. 2. The thickness of lips showed lager value for the male than that of the female in the most age group. The largest growth increments at A point was occured age of 14, while Ls, Li, B point decreased after the age of 10-11. 3. The largest increase in the interval between crest of lower lip and edge of upper incisors was occured between ages 9 and 11 in males. The interval decreased slightly from 8 to 16 years in females. 4. The nasolabial angle decreased slightly from 8 to 16 years in both sexes. 5. The mentolabial angle showed large variation.

Three dimentional force analysis of force system in continuous archwire by finite element method / 대한치과교정학회지

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.

Shear bond strength of ceramic and resin brackets used with visible light-cured adhesives / 대한치과교정학회지

The purpose of this study was to compare the shear bond strength obtained from ceramic and plastic brackets bonded with various light-cured adhesives and to evaluate their debonded failure sites. Plastic brackets, Transcend 6000, Signature and Starfire TMB brackets were bonded with Orthobond, Light Bond and Transbond on one hundred forty extracted human premolar teeth as manufacturer's descriptions. After thermocycling the brackets were debonded with an Instron universal testing machine and the debonded bracket base surfaces were inspected under stereoscope to evaluate the failure sites. Also the shear bond strength and failure patterns with different curing time and with two different source of light were compared. The results were as follows. 1. There were no statistically significant differences among the mean shear bond strength of Orthobond, Light Bond and Transbond in a same bracket group except Plastic bracket group(p<0.05). 2. The mean shear bond strength of each adhesive with different bracket groups showed statistically significant differences. Starfire TMB showed the highest shear bond strength among the brackets in this study, but there was no statistically significant difference with Transcend 6000 while there was statistically significant difference with Signature.(p<0.05) 3. The various bonding failure patterns were occurred among different bracket groups but most of failure sites were bracket base-adhesive interfaces. 4. There were no statistically significant differences in shear bond strength between the groups with curing time of 10 second and 20 second, and between the groups with two different sources of light as long as sufficient light intensity(above 400mW/cm2) were provided(p<0.05). According to the result, it should be considered in clinical use of ceramic bracket with light-cured adhesives that the shear strengths of ceramic brackets were influenced by the retention from of bracket base as well as the composition of bracket and there was no difference in the shear bond strength among various light-cured adhesives used in this study.