• The korean journal of orthodontics
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• v.26 no.6
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• pp.657-666
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• 1996

Orthopantomogram is commonly used to evaluate root parallelism. "Good parallelism" between roots is widely accepted as one of the guidelines of a successful orthodontic treatment. In case there was a large angle between crown axis and root axis, and if we valued only the position of crown in establishing occlusal relationship without considering of the situation of root, the problem of root arrangement between adjacent teeth would be occurred. The estimate of root parallelism in mesiodistal direction before and after orthodontic treatment must be emphasized. The intent of this study was to determine the clinical importance and correlation of the angle between crown axis and root axis. Orthopantomograms of 105 orthodontic patients being treated in Yonsei university were used in this study. Twenty-eight teeth in both maxilla and mandible were selected and analyzed quantitively to evaluate the angle between crown axis and root axis, and obtain the correlationship among the individual teeth. The results are as follows: 1. Among the teeth presenting normal distribution, the maxillary right canine showed the largest mean value( $5.73{\pm}4.42^{\circ}$), which was composed of the crown-root angles, and the mandibular left lateral incisor showed the smallest mean value( $0.60{\pm}3.76^{\circ}$). 2. The crown-root angles of the maxillary incisors and the first molars, and the mandibular central incisors and the first molars didn't show normal distribution and the ranges of these angles were dispersed. 3. Significant differences were present between the crown axis and the root axis except for lower first premolars. (p<0.05) 4. No significant difference was present for the crown-root angle between right and left side, (p<0.05) 5. No significant difference was present for the crown-root angle between male and female except for lower left first premolar. (p<0.05) 6. In the upper right quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor, lateral incisor and canine. In the upper left quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor. In the lower right quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor, first molar and second molar. In the lower left quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor, lateral incisor and canine, first molar and second molar. (p<0.05)

• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.497-505
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• 2004

The purpose of this study was to evaluate the post-retention stability of the lower incisor axis in Class II division 2 malocclusions. The dental casts and lateral cephalograms from before (T1) and after (T2) orthodontic treatment and long-term post-retention (T3) in 62 Class II division 2 malocclusion cases were included in this study. After several linear and angular measurements at each time were taken, the significance in the amount of change of the lower incisor axis for each gender and extraction versus non-extraction was evaluated. The results showed that the lower incisors that inclined labially during treatment were unstable and relapsed to the original lingual position in Class II division 2 malocclusions (p<0.001). There was no significant difference between extraction and non-extraction groups for the amount of lingual relapse of the lower incisors (p>0.05). There was no significant difference between male and female groups for the axial change of the lower incisors (p>0.05). As a result of multiple regression analysis, the cephalometric measurement best predicting the lower incisor position to the A-Pog line post-retention was pre-treatment L1-Apog(mm) and pre-treatment SNGoMe$(^{\circ})$. Because of the instability of labially inclined lower incisors after orthodontic treatment, the treatment goal should be the pre-treatment incisor axial position.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.95-102
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• 2003

The purpose of this study was to show occlusion on the simple hinge articulator optionally mounted. Modelling of upper-lower jaw and simple hinge articulator were developed. This modelling of upper-lower jaw inserting wax bite was mounted imaginary on the modelling of simple hinge articulator by use of the computer simulation. From changes of THA(transverse horizontal axis)-incisor distance, Balkwill angle and THA deviation, eight types were mounted respectively. After removal of wax bite, upper-lower jaw position changing were compared with centric jaw relation. The results were as follows: 1. The change of THA-incisor distance had influence on mostly a vertical shift of upper jaw. 2. The change of Balkwill angle had influence on mostly a horizontal shift of upper jaw. 3. Inferior type in the THA deviations was the least shift of upper jaw. The above results suggest that the simple hinge articulator optionally mounted effect a shift of upper jaw.

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.287-297
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• 1995

This study was performed to establish the cephalometric standards and growth changes necessary to create the Growth Forecast without Treatment at adolescence. The data from biennial serial cephalometric radiographs of 25 male and 21 female subjects aged from 8 to 16 years of Normal Koreans were used for this study. The following results were obtained. 1. There were no significant value changes of facial axis angle, fn to palatal plane angle, BA-NA-A angle, lower facial height and lower incisor protrusion as the age increased. 2. From continuous increasing measurements(anterior and posterior cranial babe length, facial axis length, condyle axis length, corpus axis length), the annual growth changes, average annual growth changes and changes for 8 years were obtained. 3. From continuous increasing measurements, significant differences were observed between male and female subjects in most annual growth changes after age of 12 years, average annual growth changes and changes for 8 years (p<0.05). 4. All linear and angular measurements were plotted by using X-Y plotter and personal computer. The visual norms for both sexes were obtained. There was considerable growth, for male, for each period especially the most remarkable growth from the age of 12 to 14. For female, the upmost growth was showed from the age of 10 to 12, and gradually decreased since then.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.4
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• pp.552-560
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• 2000

Purpose : The purpose of this study was to determine proper position and angulation of an implant for immediate implantation. Materials and Method : From the years 1997 to 2000. 52 Denta $scan^R$ views, 22 upper and 32 lower jaw with an average age of 43 and 40 respectively, were investigated, which comprise intact upper and lower 6 anterior teeth and premolars. On the Denta $scan^R$, the optimal placement for the immediated implantation was simulated. The measuring methods included 1) Angulation difference between tooth long axis and alveolar bone process. 2) Angulation difference of long axis between tooth and installing fixture 3) Distance between center of tooth at cervical area and center of fixture. 4) Distance from root apex to the bone limit of vital structure. One sample t-test was used for statistical analysis. Result : The results were as follows. 1) At the maxillary central incisor and lateral incisor, angulation difference of long axis between tooth and installing fixture was respectively 0.5 and 3.2 degrees with the fixture center's palatally positioned 2mm apart from tooth center. 2) At the lower anterior 6 teeth, that was about $-2.8^{\circ}\;to\;-4.6^{\circ}$ with the fixture center's lingually positioned 1mm apart from tooth center. 3) At the maxillary canine and premolar, that was respectively $11.8^{\circ}\;and \;7.2^{\circ}$ with the fixture center palatally positioned $2\sim2.4mm$ apart from tooth center. 4) At the lower premolar area, that was about $0^{\circ}\;to\;2^{\circ}$ with the fixture center's lingually positioned $0.5{\sim}1mm$ apart from tooth center. 5) Distance from root apex to the bone limit of vital structure, at the maxillary anterior and premolars. was the range of 10 to 12mm, and at the mandibular anterior teeth and the 1st premolar, that was the range of 18 to 20mm. Conclusion : The proper implant position of maxillary anterior and premolar teeth is as paralleled as or more buccally angulated than long axis of tooth with the fixture center's palatally positioned. In mandiblular anterior region, long axis of implants is lingully angulated compared with long axis of tooth and in premolar, almost parelleled with long axis of tooth and alveolar process.

• The korean journal of orthodontics
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• v.44 no.2
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• pp.77-87
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• 2014

Objectives: This study was designed to define the Korean norm values for the Ricketts analysis. Methods: In this longitudinal study, lateral cephalograms of 31 subjects with normal occlusion were taken biennially from ages 9-19 years. Cephalometric measurements were performed. Parameters for which the 10-year change did not exceed one standard deviation were defined as unchanged. The means and standard deviations for the measured parameters were determined for each age group. Results: No significant changes in growth were observed in the molar relationship, incisor overjet, incisor overbite, mandibular incisor extrusion, interincisor angle, lower incisor tip (B1) to A point-Pogonion (A-PO) plane, upper incisor tip (A1) to A-PO plane, B1 inclination to A-PO, A1 inclination to A-PO, B1 inclination to Frankfurt plane (FH), convexity, lower facial height, facial axis, maxillary depth, maxillary height, palatal plane to FH, cranial deflection, ramus Xi position, or porion location. Continual changes over the 10 years of growth were observed in the maxillary first molar distal position to pterygoid true vertical plane, facial depth, mandibular plane to FH, anterior cranial length, mandibular arc, and corpus length. Conclusions: Clinicians can apply the Korean norms at age 9 as determined in this study when using the Ricketts analysis. The patient's age at the beginning of treatment and their sex should be taken into consideration when drawing visual treatment objectives.

• The korean journal of orthodontics
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• v.52 no.1
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• pp.42-52
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• 2022

Objective: This study compared soft tissue changes after extraction of the four premolars followed by maximum retraction of the anterior teeth according to the type of anterior teeth movement: tipping and translation. Methods: Patients who had undergone orthodontic treatment involving the extraction of four premolars were retrospectively selected and divided into either the tipping (n = 27) or translation (n = 26) groups based on the retraction of the incisor root apex and the axis changes of the incisors during the treatment period. Lateral pre- and post-treatment cephalograms were analyzed. Results: There were no significant differences between the tipping and translation groups before treatment. The retraction amounts of the root apex of the upper and lower incisors in the tipping group were 0.33 and 0.26 mm, respectively, and 5.02 and 5.31 mm, respectively, in the translation group (p < 0.001). The posterior movements of soft tissue points A and B in the tipping group were 0.61 and 1.25 mm, respectively, and 1.10 and 3.25 mm, respectively, in the translation group (p < 0.01). The mentolabial sulcus angle increased by 5.89° in the tipping group, whereas it decreased by 8.13° in the translation group (p < 0.001). Conclusions: An increased amount of retraction of the incisor root apex led to the increased posterior movement of soft tissue points A and B, and this appeared more distinct in cases involving the lower incisor and lower lip.

• The korean journal of orthodontics
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• v.22 no.4 s.39
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• pp.869-880
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• 1992

The purpose of this study was to evaluate the difference and relationship between the slope of articular eminence and the inclination of upper and lower incisor teeth, which are related to the functional stability of occlusion in mandibular protrusion, according to Ricketts' facial types, by the use of lateral cephalogram and SAM2 articulator in 68-adult normal occlusion without tooth missing, orthodontic treatment and occlusal equilibration. The results of this study were as follows : 1 . The angle of articular eminence slope to occlusal plane in brachyfacial type was steeper than that in dolichofacial type, but the angle of articular eminence slope to SN plane and FH plane was not different between facial types. 2. The upper incisor axis in dolichofacial type was steeper than that in brachyfacial type, but lingual surface slope of upper incisor was not different between facial types. 3. In all samples there was a positive correlation between the angle of articular eminence slope and the lingual surface slope of upper incisor to SN plane and FH plane, and in mesofacial type there was a positive correlation between the angle of articular eminence slope and the lingual surface slope of upper incisor to SN plane, FH plane and occlusal plane, and in brachyfacial type there was a positive correlation between the angle of articular eminence slope and the lingual surface slope of upper incisor to occlusal plane. 4. In all samples there was a positive correlation between the angle of articular eminence slope and the angle of Dc-Gn to SN plane, and in mesofacial type there was a positive correlation between the angle of articular eminence slope and the angle of Dc-Gn to occlusal plane, and in brachyfacial type there was a positive correlation between the angle of articular eminence slope and the angle of Dc-Gn to SN plane and FH plane. 5. In all samples there was a positive correlation between the angle of Dc-Gn and the lingual surface slope of upper incisor to SN plane and FH plane, and in mesofacial type there was a positive correlation between the angle of Dc-Gn and the lingual surface slope of upper incisor to SN plane. 6. In all samples and facial types there was a negative correlation between MP to 1 axis and condylar incisal angle.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.65-78
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• 1988

The development of good arch form, the orientation of the dentition with relation to the craniofacial skeleton and the establishment of correct relationship of axial inclination of upper and lower teeth are required in normal occlusion, but different teeth present different degrees of axial inclination. The purpose of this study was to investigate the axial inclination of upper and lower teeth by analyzing $45^{\circ}$ oblique and $90^{\circ}$ cephalometric roentgenograms of 35 Korean males and 34 females with normal occlusion. The obtained results were as follows: 1. Mean and standard deviation of mesiodistal axial inclination of upper and lower teeth related to palatal plane and occlusal plane were obtained. 2. Mesiodistal axial inclination of upper first premolar was nearly perpendicular to palatal plane, and the axis of lower first premolar was nearly perpendicular to occlusal plane. 3. There was no difference in the mesiodistal axial inclination of anteriorly positioned teeth between the three groups: third molar eruption into good alignment (Group 1), third molar impaction or partial eruption (Group 2), third molar agenesis (Group 3). 4. There were low correlationships only between the axial inclination of central incisor and the mesiodistal axial inclination of canine and first premolar, but no correlationships between central incisor and posterior teeth behind first premolar.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.430-440
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• 1998

This study was performed to establish the cephalometric standards and to compare measurement of Korean children in the Field I, II, III, IV, V, VI to Japanese and Caucasians by the Ricketts' analysis. Lateral cephalograms of 24 males and 27 females with normal occlusion and acceptable profile 9 years of age were obtained and statistically analyzed. 1. Norms of Korean males, females and both sexes at 9 years old were established. 2. Significant differences between male and female exist in incisor overjet, maxillary incisor protrusion, mandibular incisor inclination, cranial deflection, corpus length. Maxillary incisor of male was more protrude and overjet was larger than female 3. Korean was similar to Japanese but different from Caucasian. Compare with facial axis and facial depth, chin was retruded dolichofacial pattern and due to large mandibular plane angle and small corpus length, mandibular plane was inclined and mandible body was short. Compare with porion location, ramus position and posterior facial height, ramus was long and located posterior. Compare with maxillary depth and maxillary height, maxilla was located posterior and inferior. The distance between the upper molar and PTV was short, the amount of distalization is limited. Maxillary and mandibular incisor were more protruded and also lower lip was more protruded to esthetic line 4. In comparison between 9 and 11 years old, growth changes of facial depth, mandibular plane angle, corpus length and upper molar position were larger than that of Japanese and Caucasians.