STATEMENT OF PROBLEM: The adjustable dental impression trays were made for being adjusted their width automatically along the width of dental arch. PURPOSE: The purpose of this study was to investigate the best retentive form of adjustable dental impression tray, and so to make it a more satisfactory product. MATERIALS AND METHODS: The eight pairs of adjustable trays were made of ABS(acrylonitrile butadiene styrene) with different distribution of holes and with or without the rim on the border area of them. The experiment was done with the horse-shoe shaped metal plate to pull out the set impression body from the tray, and the tray jig which was made for holding the tray on a lower part of Universal Testing achine(UTM, Zwick Z020, Zwick Co., Germany). After the impression in the tray was allowed to set four minutes, a tensile force was applied at right angles to the tray which had been previously seated on the jig. The force was applied to measure a maximum retentive force by use of a UTM at a constant strain rate of 100mm per minute. A 2-factor analysis of variance (p<.05) was used to determine whether differences existed among distribution of retentive holes and between rim existing and not. RESULTS: 1. The retentive force of the upper and lower resin tray with 2mm holes on the tray border was highest(25.83/24.98kg).(p<.05) 2. As the tray had more retentive holes, it was less retentive. 3. There was no significant difference in the retentive force of the varied hole intervals in the case of distributing all the area.(p>.05) 4. The rimless trays were more retentive generally, than the rimmed trays except 2 case: upper tray group-all area / 2 mm. intervals and lower tray group-margin only / 2 mm. intervals.(p<.05) 5. Most of the adjustable trays were showed higher retentive force than perforated metal tray except the lower group that perforated on the all area at intervals of 2 mm.
Dental Arch

This study was designed to get the Knowledges of the dental arch shapes of Koreans. The subjects consisted of 101 individuals with normal occlusion. The results were as follows, 1. Author found the ideal arch shape of normal occlusion 2. The regression curve and equations of normal occlusion were obtained from SPSS. 3. Ideal arch form and superimposition form were obtained by Versa-cad.
Dental Arch*

No abstract available.
Dental Arch* ; Humans

No abstract available.
Dental Arch* ; Incisor*

This study was designed to get the knowledge of the structual characteristics of the lingual dental arch shaper of Koreans. The subjects consisted of 107 nirmal occulsions. The lingual structure which was divided into two groups, anterior and posterior part, was measured and analyzed. 22 pairs of the 107 samples were usde to test the derived results. The findings of this study were as follows; 1. The mathmatical functions of the we curces which showed good fitting to the upper and lower anterior lingual arch were derived and drawed to the same acale using the computer graphics. 2. The results of the test showed a reasonable degree of accuracy to all of the 33 randm samples. 3. The average degrees of posterior flexions were obtained and could be used as a initial guide at the wire-bending.
Computer Graphics ; Dental Arch*

Human dental arches are very various in their sizes and dimensions as well as forms, so, it is very difficult to describe the shape of human dental arches as a criterion, and, further, to construct the preformed arch wires fit to them. In this study for solving these problems, the shape of elghty Korean normal lower dental arches were studied, and nine theoretical two-parameter catenary curves were derived, which were representative of all of the sample. Test were conducted which demonstrated that these nine cattenary curves would correspond with reasonable degree of accuracy to all of the dental arches, lower and upper.
Dental Arch* ; Humans

The author has selected 70 non-extraction and extraction cases. The linear measurements were made in the maxillary dental cast at pre-and post-treatment. The purpose of this study was to detect out the changes occured during orthodontic treatment. On the basis of findings of this study, the following results are made: 1. In extraction cases: 1) The maxillary intercanine width increased. 2) The maxillary dental arch width decreased. 3) The maxillary inter first molar width decreased. 4) The maxillary dental arch length decreased. 5) The maxillary dental arch length (I-3) increased. 2. In non-extraction cases, the maxillary intercanine width decreased in Angle's class III.
Dental Arch* ; Molar

The purpose of this study was to investigate and evaluate what proportion is the characteristics in Korean dental arches with normal occlusion. Many others have already indicated Golden proportion in normal dental arches, but have not considered any racial and sociocultural differences. So the author postulated (radical2)n relations in Koreans. The materials were consisted of 134 dental casts with normal occlusion, which have never undergone orthodontic and prosthodontic procedures. Measurements were made on the arch dimensions using sliding caliper and data were computerized. The findings were as follows: 1. The width between the distal surfaces of the upper centrals, had (radical2)3 relation with the width between the buccal surfaces of the upper 1st premolars in Koreans. 2. The width between the distal surfaces of the lower laterals had (radical2) relation with the width between the distal surfaces of the lower canines, and had (radical2)2 relation with the distal surfaces of the upper centrals. 3. The width between the distal surfaces of the lower centrals had (radical2)2 relation with the width between the distal surfaces of the lower laterals, and had (radical2)3 relation with the width between the distal surfaces of the upper centrals.
Bicuspid ; Dental Arch* ; Prosthodontics

The purpose of this study was to verify the class I molar relationship in skeletal class II and class II molar relationship in skeletal class I malocclusion with unilateral class II, division 1 malocclusion. The sample consisted of lateral cephalometric radiographs and upper and lower dental casts of 30 unilateral class II, division 1 malocclusion. The results of this study were as follows: 1. Skeletal class I malocclusion was 43%, and skeletal class II malocclusion was 57% in 30 cases of unilateral class II, division 1 malocclusion. 2. In the skeletal class II with unilateral class II, division 1 malocclusion, mandibular first molar on the class I side showed more mesial migration than the opposite side. 3. In the skeletal class I with unilateral class II, division 1 malocclusion, maxillary first molar on the class II side showed more mesial migration than the opposite side. 4. Midline deviation of upper or lower dental arch was 90% in 30 cases of unilateral class II, division 1 malocclusion.
Dental Arch ; Malocclusion* ; Molar

OBJECTIVE: This study aimed to evaluate the accuracy and precision of polyurethane (PUT) dental arch models fabricated using a three-dimensional (3D) subtractive rapid prototyping (RP) method with an intraoral scanning technique by comparing linear measurements obtained from PUT models and conventional plaster models. METHODS: Ten plaster models were duplicated using a selected standard master model and conventional impression, and 10 PUT models were duplicated using the 3D subtractive RP technique with an oral scanner. Six linear measurements were evaluated in terms of x, y, and z-axes using a non-contact white light scanner. Accuracy was assessed using mean differences between two measurements, and precision was examined using four quantitative methods and the Bland-Altman graphical method. Repeatability was evaluated in terms of intra-examiner variability, and reproducibility was assessed in terms of inter-examiner and inter-method variability. RESULTS: The mean difference between plaster models and PUT models ranged from 0.07 mm to 0.33 mm. Relative measurement errors ranged from 2.2% to 7.6% and intraclass correlation coefficients ranged from 0.93 to 0.96, when comparing plaster models and PUT models. The Bland-Altman plot showed good agreement. CONCLUSIONS: The accuracy and precision of PUT dental models for evaluating the performance of oral scanner and subtractive RP technology was acceptable. Because of the recent improvements in block material and computerized numeric control milling machines, the subtractive RP method may be a good choice for dental arch models.
Dental Arch* ; Dental Models ; Polyurethanes*