• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.772-781
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• 2016

This study is to set the objective criteria on maxillary incisors shade selection by using the colorimetric Shade-Eye NCC as measuring in CIE $L^*$, $a^*$, $b^*$ values, and look into the meaning by analyzing its values. We explain the purpose of this study and gotten their agreement from patients visiting the dentist, 111 people's (men 50, women 61) three teeth, the maxillary central incisor, maxillary lateral incisor, maxillary canines, total of 333 teeth colorimetry. As a result of comparing the differences in colors between cervical margin and incisal edge, ${\Delta}E^*$ of canine is shown as low as $5.81({\pm}2.98)$, followed by lateral incisor of maxilla as $6.51({\pm}3.23)$ and central incisor of maxilla $7.51({\pm}3.04)$. Females show higher luminosity(L*) than males do in all teeth- central incisor, lateral incisor and canine; in yello chroma(b*) males' central incisor is slightly higher than that of females (p<0.05). Age significantly influences the luminosity and red (a*) and yellow chroma (b*) of central incisor(L*); the luminosity(L*), and yellow chroma(b*) of lateral incisor and canine (p<0.05). Smoking doesn't significantly influence the color of natural teeth. Drinking reduces the luminosity of central incisor as well as red chroma of lateral incisor(p<0.05). A chronic illness is likely to reduce the luminosity of central incisor and lateral incisor(p<0.05).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.185-193
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• 1992

The purpose of this study was to evaluate the prevalence and distribution of tooth number anomaly by means of the analysis of panoramic radiographs in 6,531 patients visited the Dental Infirmary of Kyungpook National University Hospital from January 1983 to May 1992. The results were as follows: 1. The prevalence of congenitally missing teeth except third molar was revealed to be 10.8%, and there was a hihger prevalence in females(44.6%) than in males(55.4%). Mandibular 2nd premolars(23.2 %) were absent most frequently, followed by maxillary lateral incisors(18.4 %), mandibular lateral incisors(18.3%), and maxillary second premolars(15.4 %) in descending order of frequency. As to the number of congenitally missing teeth, the percentage of missing one tooth was 48%, missing two teeth was 35.4 %, missing three teeth was 6.6%. 2. he prevalence of congenitally missing third molars was revealed to be 39.7%. There was a higher prevalence n the maxilla(60.3%) than in the mandible(39.7%). Maxillary right 3rd molars(30.6%) were absent most frequently, followed by maxillary left 3rd molar(29.7%), mandibular right 3rd molar(202%), mandibular left 3rd molar(19.5%) in descending order of frequency. 3. The prevalence of supernumerary teeth was revealed to be 4.2%, and there was a higher prevalence in males(65.7%) than in females(34.3 ). They were ound most frequently in maxillary central incisor area(64.8%), followed by maxillary lateral incisor area(132%), posterior area of maxillary third molar(8.7%) in descending order of frequency. As to the number of supernumerary teeth; The percentage of one supernumerary tooth was 79.9%, two supernumerary teeth was 8.9%, three supernumerary teeth was 1.2 %.

• The korean journal of orthodontics
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• v.32 no.4 s.93
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• pp.275-291
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• 2002

Of various factors indicated for effective use of straight wire appliances, there was a great lack of studies both domestic and international about the curvatures of tooth crowns. This study was performed to investigate the labio/buccal clinical crown curvatures of Korean permanent teeth. For this study, three-dimensional laser scanning was performed on 36 dental casts with normal anatomic structures. Andrews plane and Facial axis of clinical crown (FACC) were designated as horizontal and vertical reference planes respectively. 2 or 3 lines, 1mm apart, were drawn superior, inferior, left and right of these reference planes. A three-dimensional coordinate table was made for points formed by crossing these lines, and averages of each coordinate point on the 36 dental casts were obtained. The curvature equation was made using three-dimensional coordinate points (x,y,z) and by this curvature equation, the curve ratio of each tooth was obtained. Curve ratio changes of each section of teeth were calculated by curve ratios of simplified curves. These two dimensional curves were simplified horizontally and vertically Conclusions for this study are as follows. 1. The basic data of labial and buccal clinical crown curvatures were obtained about Korean permanent teeth. 2. No significant difference was found between male and females. 3. Individual tooth characteristics 1) In maxillary central incisors, the difference in the curve ratio between the gingival and incisal sides was greater than for the other teeth. And the gingival side showed a greater curve ratio. 2) Maxillary canines showed more curvatures in the mesio-occlusal surface than the other surfaces. 3) In maxillary $1^{st}$ premolars, more curvatures were found in mesio-occlusal and disto-gingival surface, thus showing a twisted crown surface, but in maxillary $2^{nd}$ premolars, the crown curvatures of mesial and distal ends became parallel to each other. 4) No significant difference in crown curvatures was found between mandibular central and lateral incisors. 5) Occluso-gingival curvatures of mandibular$2^{nd}$ premolar turned out to be more rounded than mandibular $1^{st}$ premolars or maxillary $2^{nd}$ premolars. From the above conclusions, it can be deduced that the same bracket bases can be used for mandibular central and lateral incisors. But for maxillary $1^{st}\;and\;2^{nd}$ premolars and for mandibular $1^{st}\;and\;2^{nd}$ premolars, because crown curvatures showed significant differences, when making bracket bases there is ample reason to make bracket base curves differently for each type of tooth.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.315-320
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• 2017

PURPOSE. The aim of this investigation was to analyze the dimensions of clinical crowns and to classify the crown and the gingival type in the anterior teeth in Korean young adults. MATERIALS AND METHODS. Casts were obtained from 50 subjects ranging in age from 24 to 32. Measurements of length and width were made on the casts using a pair of digital calipers on the entire dentition. Crown thickness and papilla height were also measured and MDW/CL (mesiodistal width to clinical length) and CW/CL (cervical width to clinical length) ratios of the maxillary anterior teeth were calculated. The K-clustering method was used for CW/CL to classify the anterior tooth shape into three groups (tapered, ovoid, and square), and one-way analysis of variance and Duncan's post-hoc comparison were used to evaluate statistical significance between the groups. Pearson's correlation analysis was performed between tooth shape and papillary height (PH) to demonstrate the correlation between tooth shape and gingival morphological characteristics. RESULTS. The average length of the maxillary central incisors was 9.89 mm; the mesio-distal width was 8.54 mm; and the ratio of width/length was 0.86 in Korean young adults. The average bucco-palatal thickness of the central incisor was 3.14 mm at the incisal 1/3 aspect. Ovoid type was the most common tooth shape (48%), followed by square type (29%) and taper type (23%) in the central incisors of Korean young adults. Tooth shape and gingival type were correlated with each other. CONCLUSION. New reference data were established for tooth size in Korean young adults and the data show several patterns of tooth shape and gingival type. Clinicians should diagnose and treat based on these characteristics for better results in the Korean population.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.4
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• pp.310-317
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• 2015

Purpose: The purpose of this study was to evaluate the validity of reference points for edentulous patient by examining the correlation of teeth and face, and intraoral anatomic landmarks. Materials and methods: We examined a facial outline, length, bizygomatic width, nasion - gnathion length, glabella - nasion distance in 270 men and 280 women satisfied with inclusion criteria from Seoul National School of Dentistry. The shape of maxillary central incisor, mesiodistal crown width and length of maxillary 6 incisors, distance from incisive papilla to labial surface of maxillary central incisor, and perpendicular distance from incisive papilla to intercanine line were measured in the stone model. We analyzed the ratio and relevant relation statistically. Results: The probability on having the same shape of face and the relative same shape maxillary incisor was 55.56% and 46.43% for men and women. The facial length proved to be a more valuable measurement in women in the tooth selection. The ratio of bizygomatic width to mesiodistal width of maxillary central incisor, and the ratio of bizygomatic width to width of maxillary 6 incisors were 16.8 : 1 and 3.0 : 1 and were positively correlated with each other. The distance of the canines from the maxillary incisal papilla was $1.33{\pm}1.28mm$. The distance between the center of the incisal papilla and the labial surface of their maxillary central incisor was $9.23{\pm}1.20mm$. Conclusion: It was showed that anatomical reference points in tooth selection and arrangement for edentulous patient are useful and have validity in our limited study.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.1
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• pp.46-53
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• 2001

The prevalence of supernumerary teeth is between $1{\sim}3%$. Of these, $90{\sim}98%$ occur in the maxilla with particular predilection for the premaxilla, preceded by mandibular third premolars, mandibular forth molars and maxillary paramolars. The most common ones occur in the maxillary anterior region, they may occur singly between the central incisors(mesiodens), or they may be double(mesiodentes). Maxillary anterior supernumeraries may erupt into the oral cavity or remain unerupted. It is found that approximately 25% are erupted, while the rest are unerupted. They are usually a small tooth with a cone-shaped crown and a short root. They may cause delayed eruption, median diastema, bodily displacement or rotation of the adjacent permanent teeth. Occasionally they may lead to the developement of dentigerous cyst or primordial cyst, or eruption into nasal cavity. In this study, 109 supernumeraries surgically extracted from premaxilla in 84 patients are analysed. The results are as follows : 1. Sex distribution of male and female is 2.2 : 1. 2. Almost cases are in pediatric age from 5 to 12 years old (87%). 3. Problems with supernumeraries are tooth malpositon, diastema, delayed eruption, eruption to nasal cavity and cyst formation. 4. Of 109 supernumeraries, 16(15%) are erupted into oral cavity, 92(84%) are impacted, and 1(1%) is erupted into nasal cavity. 5. Of 84 patients, 59(70%) have one supernumeray while 25(30%) have two supernumeraries. 6. Of 109 supernumeraries, 96(88%) are found within the region of the central incisors. 7. Of 109 supernumeraries, 94(86%) are vertically impacted, 11(10%) are horizontally impacted, 3(3%) are labiopalatally impacted and 1(1%) is impacted in nasal cavity. 8. Of 84 patients, we used palatal flap in 67(80%), labial flap in 6(7%), both flaps in 4(5%) and no flap in 7(8%). And incisive nerve was cut in 33(49%) of 67 palatal flaps. 9. Extration with ostectomy was done in 72 supernumeraries(66%), without ostectomy in 37 teeth(34%). 10. Extraction with tooth sectioning was done in 21 supernumeraries(19%), without tooth sectioning was done in 88 teeth(81%). 11. We used local anesthesia in 70 patients(83%) and general anesthesia in 14 ones(17%).

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.4
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• pp.464-473
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• 2018

The purpose of this study was to investigate the distribution of eruption disturbance and to analyze its causes, treatment methods, and duration of orthodontic traction, based on 703 patients with eruption disturbance who were treated in the pediatric dental clinic of Seoul National University Dental Hospital between July 2011 and June 2016. Eruption disturbance in pediatric patients was most prevalent in the maxillary canine, followed by the maxillary central incisor and maxillary first molar. Eruption disorder of the maxillary canine was more common in females (p < 0.001), whereas the maxillary central incisor (p = 0.009), maxillary first molar (p < 0.001) and mandibular first molar (p = 0.028) were more common in males than females. The most common causes of eruption disturbance were abnormality of the eruption pathway and the presence of obstacles in the pathway. Orthodontic traction was the most prevalent treatment choice for eruption disorder, mostly done for the maxillary central incisors. The duration of orthodontic traction was shorter with younger age (p < 0.001) and lower crown position (p < 0.001). It is important for pediatric patients to detect eruption disorders early through regular checkup, and it is necessary to initiate treatment at an appropriate time with an accurate diagnosis and treatment plan.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.1
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• pp.77-82
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• 2011

A long-term follow-up study of a case of impacted teeth associated with a large dentigerous cyst in the left maxilla is presented. The patient was a 30-year-old man who had a large dentigerous cyst in the premaxilla and left posterior maxilla, which impacted the canine and supernumerary tooth. This is one of the most prevalent types of odontogenic cysts associated with an erupted or developing tooth, particularly the mandibular third molars. The other teeth commonly affected in order of frequency are the maxillary canines, maxillary third molars and rarely, the central incisor. Radiographically, the cyst appears as huge ovoid well-demarcated unilocular radiolucency with a sclerotic border and causes ectopic displacement of the inferior border of the maxillary sinus without destruction. Dentigerous cysts may grow unnoticed to such extensive sizes as to occupy a considerable portion of the maxillary sinus. These cysts appear to be associated with a supernumerary tooth in the maxillary anterior incisors region called the mesiodens and impacted canine. The present case report describes the surgical enucleation of a dentigerous cyst involving the permanent maxillary left canine and mesioden. After surgery, left maxillary sinus recovered their normal size and apposition of bone was observed around the apex of the posterior teeth. During the subsequent years, there was no recurrence of the cystic lesion but the inflammation was evoked in the anterior maxilla after 42 months. This complication appeared to have correlated with bony healing in the enucleation site of the cyst. We report the healing status of a huge dentigerous cyst in the maxilla for 5 years with a review of the relevant literature.

• 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)

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.2
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• pp.128-139
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• 2020

The purpose of this study was to examine the prevalence of developmental anomalies of permanent lateral incisor and eruption disturbances and analyze the association between two components. Panoramic radiographs of 3984 patients (aged 5 to 13 years) who visited the Department of Pediatric Dentistry of Seoul National University Dental Hospital between November 2016 and October 2017 were screened. The prevalence of developmental anomalies of permanent lateral incisors was 10.2%. The most common developmental anomalies were congenitally missing teeth(66.1%), followed by peg lateralis(33.5%). The prevalence of eruption disturbances was 16.5%. Among the patient with developmental anomalies of permanent lateral incisors, associated eruption disturbances were appeared on 31.1% of patients. Peg lateralis(p < 0.001), underdeveloped lateral incisors(p < 0.001) and dens invaginatus(p = 0.004) were associated significantly with eruption disturbance of permanent teeth. Eruption disturbance in patients with peg lateralis and dens invaginatus was most prevalent in maxillary canine. For patients with underdeveloped lateral incisor, eruption disturbance of maxillary central incisor was most frequent. It is important for patients with developmental anomalies of lateral incisors to detect associated eruption disturbance early through regular checkup. Diagnosis and treatment plan in view of such relationships is important in order to treat appropriately at the optimal time.