• The korean journal of orthodontics
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• v.52 no.2
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• pp.150-160
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• 2022

Objective: To provide reliable prediction models based on dentoskeletal and soft tissue variables for customizing maxillary incisor positions and to optimize digitalized orthodontic treatment planning. Methods: This study included 244 Chinese women (age, 18-40 years old) with esthetic profiles after orthodontic treatment with fixed appliances (133 in group I: 1° ≤ The angle between the nasion [N]-A point [A] plane and the N-B point [B] plane [ANB] ≤ 4°; 111 in group II: 4° < ANB ≤ 7°). Dental, skeletal, and soft tissue measurements were performed on lateral cephalograms of the participants. Correlation and multiple linear regression analyses were used to determine the influence of dentoskeletal and soft tissue variables on maxillary incisor position. Results: The ideal anteroposterior position of the maxillary incisor varied between sagittal skeletal patterns. The position of the maxillary incisor correlated with the sagittal discrepancy between the maxilla and the mandible (ANB), protrusion of the midface, nasal tip projection, development of the chin, and inclination of both the maxillary and mandibular incisors. Distance from the maxillary central incisor to nasion-pogonion plane predicted using multiple linear regression analysis was accurate and could be a practical measurement in orthodontic treatment planning. Conclusions: Instead of using an average value or norm, orthodontists should customize a patient's ideal maxillary incisor position using dentoskeletal and soft tissue evaluations.

• The korean journal of orthodontics
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• v.30 no.2 s.79
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• pp.159-174
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• 2000

Many treatment approaches of Cl III malocclusion have been introduced and the choice of treatment should be a function of the individual problem, not of the clinician(personal preference, experience and success rate of the operator). Therefore a function of the individual problem should be analysed exactly Much has been written in the orthodontic literature concerning the nature of Cl III malocclusion. It has been reported by many investigators that a Cl III malocclusion occurs in a variety of skeletal and dental configurations by differences of race and age. Lateral cephalometric radiographs of 125 individuals were studied for the presence and distibution of four horizontal components and one vortical component in a manner similar to McNamara. The results were as follows : 1. Cl III malocclusion is not a single clinical entity. It can result from numerous combinations of skeletal and dental components. 2. Maxillary skeletal retrusion was the most common single charateristic of the Cl III sample. 3. Only a small percentage of the cases in this study exhibited maxillary dentoalveolar protrusion. 4. Only a small percentage of the cases in this study exhibited mandibular dentoalveolar retrusion. 5. Mandible was usually well-positioned, but a wide variation was observed. 6. A large percentage of the cases in this study exhibited excessive vertical development. Thus, it appears that in designing the ideal treatment regime, those approaches which might restrict vertical development and promote maxillary horizontal growth could be more appropriate in many cases.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.1-11
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• 2004

Predicting the arch length discrepancy by simply comparing the available arch perimeter with tooth materials is merely a 2-dimensional analysis of the teeth movement. However, the real teeth movement takes place 3-dimensionally and is affected by various factors such as, the arch fen the curve of Spee and the axis of the incisors. The purpose of this study is to clarify the relationship between the decrease in the arch perimeter and the horizontal positional change of the incisors after extraction of the 1st bicuspids, for more analytic evaluation of the arch length discrepancy at pre-treatment model analysis stage. In addition to that to evaluate the effect of the curve of Spee, teeth axis to the basal plane, and the incisional crowding to the treatment outcome. All patients were treated at the department of orthodontics, dental hospital, Yonsei university. Inclusion criteria for patients selection were as follows. $\cdot$ Angle classification I malocclusion with bialveolar protrusion $\cdot$ Extraction of 4 1st bicuspids $\cdot$ No tooth anomaly or prosthesis $\cdot$ No abnormal attrition $\cdot$ No ectopically erupted teeth $\cdot$ Angle classification I canine and molar relationship $\cdot$ Less than 3mm of crowding Model analysis of the above patients was performed and the following conclusions were obtained. 1. When the intercanine distance was maintained, the available space for the distal movement of the mandibular incisors after the extraction of the 4 1st bicuspids was larger than the space provided by the extraction of the 4 1st bicuspids. However the difference was less than 1mm. The more tapered the anterior arch form, the larger the difference. 2. Compared to the situation in which the intercanine distance was maintained, when the intercanine distance was expanded to meet the width of the Posterior teeth, the incisors could move about 3mm more distally. 3. The positional difference of the incisal tip was insignificant whether the central incisors were moved by tipping or bodily movement. 4. When the anterior crowding was solved without changing the intercanine distance, the larger the anterior arch length was, the more the anterior movement of the incisors. 5. When the curve of Spee was levelled, the increase in the arch perimeter was less than half of the deepest curve of Spee.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.1
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• pp.29-35
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• 2012

Purpose: The purpose of this study was to analyze temperature change along the implant-bone interface induced by grinding the occlusal surface of implant gold prosthesis and to compare the temperature generated by grinding of prosthesis with different cooling methods. Materials and methods: The experimental gold prostheses were fabricated with dental gold alloy and castable abutment. The prostheses had 3 cylindrical protrusions on the occlusal surface with 1mm in height. Temperature was measured using 16 thermocouple wires attached to the implant fixture surface and the fixture was embedded in an acrylic resin block inside the $37^{\circ}C$ water bath. Cylinders were grinded for a period of 30 second with a low-speed handpiece with green stone point. One cylindrical protrusion was grinded without cooling, the second one was grinded with air blow, and the third one was grinded with water-spray. Results: The mean maximum temperature was measured more than $47^{\circ}C$ of the implant and the maximum temperature was measured at the cervical portion of the implant in the group without cooling. There was statistically significant difference between the group without cooling and the groups with cooling (P<.05). However, there was no significant difference at all portion of implant in the groups with cooling (P>.05). Conclusion: The results of this study support that the grinding of implant gold prosthesis without cooling may damage the peri-implant tissue. The continuous use of air blow and water-spray adjacent to prosthesis during the grinding of implant gold prosthesis may prove to be beneficial for cooling of the implant.

• 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.