• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.209-223
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• 2001

At intrusion of upper anterior teeth in patient with periodontal defect, the use of three-piece base arch appliance for pure intrusion is required. To investigate the change of the center of resistance and of the distal traction force according to alveolar bone height at intrusion of upper anterior teeth using this appliance, three-dimensional finite element models of upper six anterior teeth, periodontal ligament and alveolar bone were constructed. At intrusion of upper anterior teeth by three-piece base arch appliance, the following conclusions were drawn to the locations of the center of resistance according to the number of teeth, the change of distal traction force for pure intrusion and the correlation to the change of vertical, horizontal location of the center of resistance according to alveolar bone loss. 1. When the axial inclination and alveolar bone height were normal, the anteroposterior locations of center of resistance of upper anterior teeth according to the number of teeth contained were as follows : 1) In 2 anterior teeth group, the center of located in the mesial 1/3 area of lateral incisor bracket. 2) In 4 anterior teeth group. the center of resistance was located in the distal 2/3 of the distance between the bracket of lateral incisor and canine. 3) In 6 anterior teeth group, the center of resistance was located in the central area of first premolar bracket .4) As the number of teeth contained in anterior teeth group increased, the center of resistance shifted to the distal side. 2. When the alveolar bone height was normal, the anteroposterior position of the point of application of the intrusive force was the same position or a bit forward position of the center of resistance at application of distal traction force for pure intrusion. 3. When intrusion force and the point of application of the intrusive force were fixed, the changes of distal traction force for pure intrusion according to alveolar bon loss were as follows :1) Regardless of the alveolar bone loss, the distal traction force of 2, 4 anterior teeth groups were lower than that of 6 anterior teeth group. 2) As the alveolar bone loss increased, the distal traction forces of each teeth group were increased. 4. The correlations of the vertical, horizontal locations of the center of resistance according to maxillary anterior teeth groups and the alveolar bone height were as follows : 1) In 2 anterior teeth group, the horizontal position displacement to the vortical position displacement of the center of resistance according to the alveolar bone loss was the largest. As the number of teeth increased, the horizontal position displacement to the vertical position displacement of the center of resistance according to the alveolar bone loss showed a tendency to decrease. 2) As the alveolar bone loss increased, the horizontal position displacement to the vertical position displacement of the center of resistance regardless of the number of teeth was increased.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.291-297
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• 2016

Patients with $Sj{\ddot{o}}gren^{\prime}s$ syndrome usually suffer from teeth discoloration and attrition due to xerostomia. If the anterior teeth are badly worn, problems such as loss of anterior guidance, occlusal disharmony, and limited space for restoration may occur. However, ideal occlusion is obtained in both centric and eccentric relation by regaining the disocclusion of the posterior teeth through the anterior and lateral guidance using twin-stage method. In this case, rehabilitation was performed for a $Sj{\ddot{o}}gren^{\prime}s$ syndrome patient with maxillary and mandibular incisor's severe attrition and teeth discoloration by using twin-stage method.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.127-134
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• 1993

The purpose of this study was to observe the control effect of hypersensitivity after periodontal treatment in the 19% microcrystalline hydroxyapatite containing toothpaste for the subject of 85 persons of both sexes, who complained hypersensitivity. At 2 weeks and 4 weeks after periodontal treatment, comparison of control effect was performed between the 19% microcrystalline hydroxyapatite containing toothpaste group and control group. The result were as follows, 1. The main causes of dentin hypersensitivity are the root exposure with gingival recession and cervical abrasion. 2. The occurance rate of hypersensitive tooth in the upper jaw was higher than that of the lower jaw, and more or less, the molar area showed more occlurance of hypersensitivity than the premolar and incisor area in both jaw. 3. Patients showed very sensitive response to the thermal stimulus, especially cold stimulus. 4. Exellent control effect of hypersensitivity in 19% microcrystalline hydroxyapatite containing toothpaste group showed 83.02% at 2weeks, 92.45% at 4weeks and these values were higher than the control group. In conclusion, we find that 19% microcrystalline hydroxyapatite containing toothpaste have the control effect of hypersensitivity and the proper toothbrushing method is the key in attaining more effectiveness of the toothpaste.

• The korean journal of orthodontics
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• v.18 no.2
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• pp.459-474
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• 1988

A study was made of a method of rational assessment on the roentgeno-cephalogram in orthodontic practice. Fifty eight measurements were analyzed on the roentgeno-cephalograms of 50 male and 50 female Korean adults with the acceptable profile and the normal occlusion. The means and standard deviations of measurements were studied in male and female groups by various analytic methods, and the sex difference was examined statistically. The obtained data were compared with those of the Japanese and American standards by useing a Japanese adults standard polygon chart reported by lizuka and Ishikawa. Amongs of 58 measurements, 14 have been selected as statistically significant and clinically useful, and used to make a Korean adult standard polygon chart. The results obtained were as follows: 1. Standards for cphalometric analysis in Korean adults were obtained, and the polygon chart and cephalometric profilogram were also made by using the standards in order to apply to a clinical diagnosis. 2. The sex difference was recognized in linear measurements, but not in angular measurments. 3. In comparison with the American standards from Downs and Graber, the Korean showed significant differences in angle of convexity, mandibular plane angle, Y-axis angle, interincisal angle and lower incisor to mandibular plane angle. Thus, the Korean showed a more retruded chin position, convex facial type, than white people. 4. In comparison with the Japanese standards from Iizuka and Ishikawa, the Korean showed a significant similarity with the Japanese, especially in females. 5. Upper incisor to Huxely line angle, established as a new measurement, proved to be paralell to X-Y axis angle.

• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.563-573
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• 1999

The purpose of this study was to evaluate the availability of computer system for the measurement of tooth size in the model analysis through the comparison of two measurements: One was to use a computer; and the other was to use vernier calipers. Twenty sets of casts were used, which showed a moderate degree of crowding and full eruption of all teeth. The mesio-distal width of 12 teeth from the left central incisor to the left first molar at each set of the casts were measured twice with vernier calipers and a computer respectively. This measurement was repeated two weeks later. First, for the reproducibility analysis, the two computer measurements were compared then the vernier calipers measurements were compared. Second, all the teeth were sepapated into the region of mesiodistal contact points and its width was measured by a micrometer to obtain standard measurements. For the accuracy analysis, these standard measurements were compared with the measurements from the dental casts using two methods. The difference between them was defined as the measurement error. To investigate the cause of measurement error, an examination was made for the presence and degree of contact point deviation on each tooth from the upper and lower occlusograms, and the mesio-distal angulation of each tooth was measured with TARG. Following results were obtained through statistical analysis. 1. In the analysis for reproducibility; the measurements with vernier calipers showed significant differences in three out of twelve teeth while the computer measurements showed significant differences in one out of twelve teeth. 2. In the analysis for accuracy; compared with the standard measurements, the measurements with vernier calipers showed significant differences in three out of twelve teeth while the computer measurements showed significant differences in two out of twelve teeth. 3. Compared with the standard measurements, the measurements with vernier calipers were apt to be larger at the upper first molar, and smaller at the lower first molar The computer measurements, however, were apt to be larger at both upper and lower first molars. 4. The measurements with vernier calipers showed the largest error at the lower first molar and the degree of error was variable according to the tooth while the difference of error was small in the computer measurements. 5. In the analysis for the correlation of the degree of measurement errors with the contact point deviation index and the mesio-distal crown angulation of each tooth, the measurements with vernier calipers did not show significant correlation while the measurements with computer showed slight Positive correlations. The results of this study indicate that a computer system may be useful for the measurement of tooth size in the model analysis.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.1-13
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• 2001

The extraction lot orthodontic treatment can be adopted for aligning crowded dentition, improving facial esthetics and solving a skeletal discrepancy as alternative for a surgical option. Mandibular second premolar extraction was often selected as treatment plan when there we very little or no space shortage in lower arch or limited retraction of the lower incisors was required. The primary object of this study was evaluate a pretreatment condition and examine the amount of tooth movement ior a mandibular second premolar extraction in growing patients. Pretreatment and posttreatment lateral cephalograms of 14 cases that had their four first premolar extracted (4/4 group), 15 cases with upper first and lower second premolar extraction (4/5 group) were selected. Structural method superimposition was conducted to evaluate a difference of dental change between 4/4 and 4/5 group. The results were as follows, 1. Pretreatment factor for 4/4 extraction or 4/5 extraction choice included maxillary incisor axis to occlusal plane, Class II molar relationship, IMPA and interincisal angle. 2. The amount of molar anterior movement in 4/5 group was greater than that of 4/4 group(p<0.05). 3. There was no significant difference between 4/4 group and 4/5 group in aspects of maxillary tooth movement(p<0.05).

• The korean journal of orthodontics
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• v.25 no.4
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• pp.375-401
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• 1995

Cause of skeletal Class III malocclusion in growing patients can be classified into maxillary deficiency, mandibular overgrowth, and combination of the two. Use of Protraction Head Gear(P.H.G.) has been recommended for treatment of growing Class III malocclusion patients, for it results in forward & downward movement of maxilla and backward & downward rotation of mandible. Numerous animal experiments were performed and clinical study data have been reported ; nevertheless, studies on soft tissue profile change and comparison of treatment effects among the patients who had undergone treatment are considered to be somewhat insufficient. The author selected 93 patients, who had been diagnosed as skeletal Class III malocclusion with maxillary deficiency and then treated with P.H.G. ; the sample group was divided according to sex, treatment beginning age, palatal suture opening(intraoral appliance), and facial growth pattern. For each group, changing patterns of hard and soft tissue profile observed, and comparision with 20 normal group(Angle's Class I) patients of statistical significance in amount of growth and treatment of hard and soft tissue was done. The following results were obtained. 1. Skeletal, dental, and soft tissue measurements indicated that more growth changes was induced in the sample group that used P.H.G. compared to the growth amount of normal group. 2. No statistical significance was observed in the amounts of maxillary forward movement and mandibular backward & downward rotation depending on treatment beginning age in both sex group. 3. R.P.E. showed more significant maxillary forward movement and less protrusion of upper incisor than La-Li. 4. There was no statistical significance in the amount of maxillary forward movement depending on facial growth pattern. On the other hand, measurements indicating mandibular downward & backward rotation indicated greater change in counterclockwise growth pattern group than the clockwise. 5. Changes in upper and lower lip thicknesses showed a close relationship with positional changes in underlying bone tissue and upper and lower teeth, and upper lip height and nasolabial angle increased and mentolabial angle decreased.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.249-257
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• 2012

Purpose: This study was designed to help to provide the criteria of the esthetic smile in oromaxillary region on twenties, fifties and sixties. Materials and methods: The facial straight photographs of 33 adults (male 15, female 18, mean age 27.2 years old) and 20 seniors (male 7, female 13, mean age 55.6 years old) in resting and smile position were taken. The measurements and proportion of lip-teeth relation during smile were statistically analyzed, and survey of freshmen and seniors who belong to School of Dentistry, Chonnam National University were taken to select the best esthetic smile among the photographs. Results: In the relationship between the upper lip and the teeth, average smile was the most frequent, and mean of smile line ratio was 1.090 in young group and 0.90 in old group. The correlation between the buccal corridor ratio and exposed teeth count was inversed. At smile, most frequently exposed tooth was the second premolar (63.64%) in young gourp and the first premolar (35.00%) in old group. The correlation between the upper lip change ratio and exposed clinical crown length of maxillary central incisor was inverse, but there was no correlation between the lower lip change ratio and exposed clinical crown length of maxillarycentral incisor. Conclusion: In the result of survey, the students selected the case exposed to the first premolar as the most esthetic smile. The most esthetic smile between full facial photograph and the lip only photograph by the freshmen was different, but that by seniors was identical.

• The korean journal of orthodontics
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• v.25 no.1 s.48
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• pp.19-29
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• 1995

This study was performed to compare the size of soft palate, tongue and airway according to the types of the malocclusion and evaluate the correlation between the size of soft palate, tongue, airway and dentofacial skeleton respectively. The sample of this study was 98 malocclusion female patients between the ages 12 and 17 years. The lateral cephalometric radiographs were taken and the distance, angle, ratio and area of the dentofacial skeleton, soft palate, tongue and airway were measured and evaluated statistically. The results obtained were as follows: 1. There was significant difference in SNB, ANB, facial angle, facial convexity, A-B plane angel, Y axis to FH, SN-MP, Wits appraisal, ODI and APDI according to the types of malocclusion. 2. The hyoid bone was more posteriorly positioned in Class II malocclusion group than other two groups and superio-inferior position of the hyoid bone was not different according to the malocclusion types. 3. The nasopharyngeal area of Class II and Class III malocclusion group was smaller than that of Class I malocclusion group, and the pharyngeal area of Class II malocclusion group was smaller than that of Class I and Class III maocclusion group. There was no difference of the area of the soft palate, tongue, oropharynx and hypopharynx according to malocclusion types. 4. The ramal height and mandibular body length(Go-Me) showed positive correlation with the area of tongue, nasopharynx, oropharynx, and pharynx. SNA did not correlated with the area of tongue and airway but SNB showed positive correlation with the area of hypopharynx and pharynx. The anterior, posterior facial height, upper and lower central incisor position to facial plane showed positive correlation with tongue area.

• Journal of Yeungnam Medical Science
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• v.18 no.1
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• pp.112-122
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• 2001

Background: Cleft lip and palate deformity have unknown patterns of maxillofacial growth and development. The maxillofacial growth can be affected either by congenital or environmental factors such as infection and trauma. Surgical repair of cleft lip and palate may interfere the subsequent growth and development of maxillofacial region. The purpose of this study is to evaluate the characteristics of maxillofacial growth patterns in adult cleft lip and palate patients. Materials and Methods: The material for this study consisted of 17 adult male patients with cleft lip and palate. Cephalometric tracing and measurements were done by one investigator. The relationship between 17 cleft lip and palate patients and Korean norms were evaluated statistically. Results: There were statistically differences in Na. perpendicular to point A, SNA angle, effective maxillary length, maxillofacial differencial. Wit's appraisal and upper incisor to point A(p < 0.01). Pogonion to Na. perpendicular also statistically differed(p < 0.05). Other measurements didn't statistically differ. Conclusion: It was evident that in adult cleft lip and palate patients, maxilla was retruded and short. Careful cleft lip and palate repair and treatment are recommended for facilitating normal growth of maxilla.