A study on titanium miniscrew as orthodontic anchorage: An experimental investigation in dogs / 대한치과교정학회지

Titanium miniscrews are being used increasingly as an anchorage for tooth movement, because they are easy to place and to remove, increase the number of sites available, give minimum strain to patients regarding surgical procedures, and offer uneventful healing after removal. The use of titanium miniscrews as an orthodontic anchorage has been reported in clinical case reports, but clinicians have experienced screw loosening when using such screws. To our knowledge, there are no published reports evaluating the stability of miniscrews. Information about the length of miniscrews used in relation to the location is of some importance, as stability will vary depending on bone quality. The purpose of this study was to evaluate a variety of lengths of miniscrews (diameter: 2mm) which were inserted in maxilla or mandible and to demonstrate in a dog model which miniscrew provides fundamental stability in the jaws. 10 mm long miniscrews in the maxilla and 8mm long miniscrews in the mandible showed no clinical mobility and retained their position throughout an 8 weeks force (200g) application. The mucosal condition around the screws was healthy in cases in which miniscrews were inserted in the alveolar bone between the roots and the head of the screws emerged into the attached gingiva. When the force application was terminated, radiographic analysis revealed neither root resorption nor periodontal pathology around the miniscrews that remained stable during the entire treatment period. This study suggests that if titanium miniscrews with adequate length are properly used depending on the location, they provide sufficient stability for orthodontic anchorage.

A study on frictional resistance force of orthodontic resin bracket / 대한치과교정학회지

As increasing number of adult patients, the esthetic orthodontic appliances are needed. They are tooth-colored or translucent ceramic and resin brackets. Although ceramic and resin bracket have good esthetics, there are some disadvantage such as frictions. Recently, metal-reinforced resin bracket(MRRB) were introduced. The purpose of this study is to find frictional force of MRRB, ceramic bracket and resin brackets. There is few study in frictional force about metal reinforced resin bracket(MRRB). This study used 4 orthodontic wire(.016S-S, .016TMA(R), .017X.025 TMA(R))and 5 brackets(one metal bracket, one ceramic bracket, one resin bracket, two MRRB). the following result is obtained using metal bracket(Ormco.Co., U.S.A), ceramic brackets(Crystalline(R), resin bracket(Clear Medium Siamase(R)). Following conclusions are obtained. 1. Ceramic and resin bracket have significantly more frictional forces than metal reinforced resin bracket and metal bracket. 2. There is no significant difference in frictional force according to the slot types of metal-reinforced resin brackets. 3. There is no significant difference in frictional force between metal reinforced resin bracket and metal bracket. 4. Frictional force is decreased in S-S wire than TMA wire.

A study on the accuracy of profile change prediction by video imaging (Power Ceph (R)Ver 3.3) in Class III two jaw surgery patients / 대한치과교정학회지

There is are d for more accurate prediction in surgical orthodontic treatment. Video imaging is an important technology in planning orthognathic surgery and educating Patients about the esthetic results after treatment. Preoperative and postoperative lateral cephalogram of 30 patients who had one piece Le Fort I osteotomy advancement and mandibular set back by bilateral intraoral vertical ramal osteotomy with or without genioplasty were used in this study. The computer generated soft tissue line drawing prediction were compared with the actual postoperative cephalograms. The results are as follows. 1. 14 variables showed Statistically significant differences from 24 variables between computer predicted profile and post operative profile 2. Most of the differences were found in the maxilla-related soft tissue landmarks. 3. The predicted results were more accurate in the groups who had small amount of mandibular set back. 4. The predicted results were more accurate in the groups who had no genioplasty. Most of these differences were within 2mm ranges. Therefore profile change prediction by video imaging could be considered clinically acceptable.

A morphometric study of teeth on the Korean normal occlusion / 대한치과교정학회지

The objects of this study were to analyze the crown angulation, crown inclination, molar offset angle, and crown in and out of the Korean adults having normal occlusion. 14 subjects (7 male, 7 female) were chosen in the 80 subjects who had ideal occlusion and beautiful profile we thought. The casts were obtained from the subjects, and then they were scanned with 3-dimensional scanner machine. We analyzed them with computer program based upon Andrews methods and the following results were obtained. 1. We got the norm of the crown angulation, crown inclination, molar offset angle, and crown in and out in the Korean adults. 2. The analysis using 3 dimensional scanner and computer program was more fast and accurate than the manual methods.

Stress distribution in esthetic orthodontic brackets: An analysis using the finite element method / 대한치과교정학회지

The aim of this study were to measure and compare the stress level on three type brackets and each other material (stainless steel, ceramic) with tipping and torquing forces by using the finite element analysis and to design bioniechanically favorable brackets. For this study, three kinds of brackets were selected(A:Transcend-RMO, B:Signature-Unitek, C:PAW plain archwire appliance-applied for a patent in Yonsei University). The slot size of bracket was 0.022inch and the size of archwire was 0.0175x0.025inch and taper shaped archwire was used in PAW. Loading force in tipping was 4.27N and torquing force was 32.858N applied by archwire torsion with 19.7degree and 113 degree in C type bracket. The conclusions were that (1) The finite element method proved to be a useful tool in the stress analysis of orthodontic bracket subjected to various forces. (2) With tipping, the stresses were concentrated at the gingival wall of the wire slot where it meets the mesial bracket surface and the incisal wall of the wire slot where it meets the distal bracket surface and with torquing, the stresses were concentrated at the junction of the gingival or incisal wall and base of the slot. (3) The maximum stress value was higher in torquing force than tipping force and therefore it is desirable to design on the basis of torquing force. (4) It was considered that the change in material might be affect on the diminish of stress value in the place of stess concentration. (5) The maximum stress value was highest on PAW bracket when the tipping and torquing force was applied and therefore it would be desirable to use mechanically favorable material on PAW bracket.

Lower incisor extraction for dental camouflage / 대한치과교정학회지

There is a variation in the range of normal occlusion, and we must fit our treatment to the needs of each patient. If the upper or lower incisors are congenitally missing, malformed, or crowded, the extraction of the incisor has some advantages over the extraction of premolars and nonextractions. The advantages are l) simple mechanics, 2) reduced treatment time, 3) less relapse tendency, and 4) fewer facial profile changes. In order to decide which incisor should be extracted, we must consider certain factors: l) discrepancies in anterior arch length, 2) anterior tooth ratio, 3) periodontal and tooth health condition, and 4) the relationship between the upper and lower midline. Diagnostic set-up can be helpful to plan the treatment and show us the post treatment result.

Knowledge of orthodontics and malocclusion / 대한치과교정학회지

Orthodontists want why the patients want orthodontic treatment. Demand and need for orthodontics is very important factors of cooperation and management. Chief complaint would be different according to the race and culture. Our results show that in the control group, Korean female adolescents[chief complaint is cowding(30.6%), spacing(26.5%), upper anterior protrusion(18.4%), anterior cross bite(8.2%) in order. Korean female adolescents considered anterior cross bite is more nonacceptable than spacing and anterior protrusion. The purpose of orthodontics seemed to enhance esthetic, dental health, and to improve oral function.

Effect of maxillary expansion appliance using magnetic attraction force / 대한치과교정학회지

To study the possibility of attraction magnetic forces to expand maxillary arch, we used 2 big adult dogs, 2 small puppies, 1 small adult dog as experiments, and 1 small adult dog as a control. We measured the intercanine width and intermolar width and histologically observed in the suture and cervical and apex region of teeth and took occlusal X-rays to observe separation of suture line in the maxilla. The results were as follows: 1. Expansion velocities of intercanine (0.25mm/day) and intermolar widths (0.23mm/day) in puppies were faster than those (0.135mm/day, 0.09mm/day) in adults. 2. In all experiments in adults (0.135mm/day) and puppies (0.25mm/day), expansion velocity of intercanine widths were faster than those (0.09mm/day, 0.23mm/day) of intermolar width. 3. In all experiments ectatic changes were observed and cellularities of fibroblast increased in the suture line. Only in adults dogs the separations of palatal suture were observed in the occlusal X-ray view. 4. In the puppies bony deposition was particularly observed in the suture line and micro-bony fragments were often observed. 5. In the all experiments no root resorption was observed in the cervical and root area, but normal root resorption due to eruption of permanent teeth was observed in the puppies.

Comparisons of dental arches and crowdings between musical wind-instrument players groups and non-wind instrument players group / 대한치과교정학회지

For the comparisons of dental archs and crowdings between musical wind instrument players groups and non-wind instrument players groups, 64 male wind instrument players and 31 non-wind instrument players group were selected. The results of the measurements were as follow. 1. Upper intercanine widths, upper basal arch widths, lower basal arch widths were statistically significant between musical wind instrument players groups (Class A, Class B) and non-wind musical instrument players group. 2. The mean value of upper intercanine width m Class A (37.3 +/- 2.3mm) was greater than in Class B (36.2 +/- 1.7mm) and non-wind musical instrument players group(36.0 +/- 1.6mm) 3. The mean value of lower basal arch width m Class B (42.2 +/- 2.5mm) was greater than that in non-wind instrument players group (39.5 +/- 2.8mm). 4. The differences m the mean values of crowdings between Class A and Class Band non-wind instrument players group were not statistically significant.

Cephalometric analysis of maxillofacial normals in Korean adults / 대한치과교정학회지

This study was performed to aid for the case analysis and diagnosis of the maxillofacial deformities. A cephalometric analysis was made form 101 subjects over 18 years old, that consisted of 46 males and 55 females with normal occlusion, acceptable profile. The results of this study were obtained as follows: 1. The tables of normals in adult male and female were made. 2. The angles of SNO were 65.5degrees in male and 65.3degrees in female and the horizontal linear measureaments from 0 to NA(O-NA) were 9.0mm in male and 8.9mm in female. 3. The cranial base angles (SN-FH) were 8.2degrees in male and 10.3degrees in female and the mandibular plane angles (OP-HP) were 28.1degrees in male and 26.2 in female. 4. The correlation of (O-NA) to S-O/S-A and S-O/S-N were higher than SNO, and the correlation of (N-A) to SNA and (N-B) were high.