• The Journal of Korean Academy of Prosthodontics
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• v.47 no.4
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• pp.457-462
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• 2009

Purpose: The objective of this systematic review was to obtain the comprehensive survival rates of short implants. Then it was examined that whether treatment using short implants has favorable results. Methods: A MEDLINE search was performed, the data obtained from many articles about length, diameter, site of placement, surface treatment and prosthetic design were analyzed. Results and discussion: The data obtained from many articles were analyzed, and it was found that the survival rate of short implants was 95.87%, short implants has similar outcomes to those reported for standard implants. On the other hand, in the comparison the survival rate of 3 groups divided by the diameter of implants under 4 mm, 4-5 mm, and above 5 mm, a statistically significant difference was detected in under 4mm group. In implant group with 6-7 mm length, a group with 5-6 mm diameter has survival rate of 97.01%, groups with 3.1-4.8 mm diameter has survival rate of 92.96%, which was statistically significantly different. In the result of surface feature, the roughed surface groups of short implant showed a higher survival rate by approximately 6.3% than machined surface group. In the result of prosthetic design, survival rate of short implant was considerably lower for the single implant crown group (94.3%) than splinting group (99.4%).

• 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 academy of Pediatric Dentistry
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• v.42 no.2
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• pp.172-179
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• 2015

The developmental mechanism of root formation is a complex process. Hereditary and environmental factors may affect the morphology of the developing root. A total of 12 cases was presented with permanent first molars with abberant root morphology. Clinically, these teeth appeared as a normal crown. However, radiographically, the root was slender, twisted and characterized by irregular lengths. In addition, root trunk length was shorter and pulp chamber was obliterated. In these cases, periapical radiolucency and loss of lamina dura were often observed. In 6 cases, an abnormal root of the primary second molars were also present, as well as root malformation of permanent first molars. In 3 cases, permanent central incisors also had a dysmorphic crown. These cases almost all had medical history, such as premature birth, brain infection or congenital heart disease in infants. The present paper describes cases of permanent first molars with an abnormal root that are rarely reported in literature. This case may intensify the variation in the permanent first molar and is intended to reinforce the clinician's awareness of rare morphology of the roots.

• Journal of dental hygiene science
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• v.7 no.3
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• pp.201-205
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• 2007

This study was designed to compare the perception of dental hygiene students and general public with respect to minor variations in maxillary anterior tooth size, alignment and their relation to the surrounding soft tissues. Maxillary anterior teeth were intentionally diagrammed in varying degree of deviation with respect to one of three common anterior esthetic discrepancies including variations in crown length, shape of gingival margin, and length of interproximal contact. Seventeen images were generated to be preferentially selected by 2 groups consisting of dental hygiene students and lay people in Busan(total of 216). The obtained results were as follows; 1. Both group preferred gingival margin of lateral incisor to be 0.5mm lower than that of central incisor. 2. Both group preferred the gingival margin shape of central incisor has 1/9 horizontal component of the crown width. 3. Both group preferred length of the interproximal contact has 1/2 of the crown length. The results of this study may be considered to influence the decision making process by dental professionals with respect to designing the anterior esthetic gingival line.

• The korean journal of orthodontics
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• v.29 no.6 s.77
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• pp.689-698
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• 1999

Although the purpose of orthodontic treatment is to increase the function and aesthetics of the jaws as well as to increase stability, there are side effects from the treatment itself such as root resorption and alveolar bone resorption. Such resoiption of the apical root is unpredictable and may even proceed into the dentin layer. Once the process has begun, it is irreversible. By evaluating the effects of different oral habits, especially that ef nail biting, and their correlation with the root and the periodontal tissues, the appropriate biomechanics for orthodontic treatment can be taken into consideration. The possibility of root resorption and alveolar bone loss during orthodontic treatment can also be considered. Also, any legal problems that might occur may be pondered as well. Among the male md female patients of the ages 10~15, 63 were chosen as the test group with known nail biting habits at time of examination and within the same age range those without nail biting habits as the control group. The test group was composed of 30 males and 33 females. The control group had 31 males and 32 females. The result from this study were as follows : 1. Of the 63 patients of both the test and control groups, the male-to-female-ratio was 1:1, and had no statistically significant difference in male and female root resorption. 2. In comparing crown length of the test and control groups, no significant difference existed, but in root length, maxillary and mandibular right and left central incisors and mandibular right lateral incisors had a smaller value. (p<0.001) 3. Average crown-to-root ratio of the test group on the periapical view show a noticeably high value for the maxillary and mandibular right and left central incisors and mandibular right and left lateral incisors. (p<0.01) 4. In comparing and evaluating the alveolar bone loss measured from the cemento-enamel junction to the alveolar bone crest, mesial surfaces of the maxillary and mandibular right and left central incisors and distal surface of maxillary right central incisor of the test group showed greater loss of crestal bone than the control. (p<0.05)

• 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 Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.40-49
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• 2018

It is reported that the causes of unaesthetic proportion of anterior teeth vary widely. Especially, when the unaesthetic tooth proportion of the mandibular incisors arises due to the wear of the anterior teeth accompanied by the compensation of the alveolar bone, it may cause serious functional and aesthetic problems. In such case, it should be considered that the evaluation of vertical dimension and tooth proportion as well as smile line, soft tissue and hard tissue morphology. And, increase of vertical dimension or clinical crown lengthening followed by prosthodontic restorations is needed to improve the interdental mesial/distal, width/length ratio considering the anterior guidance. This case report demonstrates functional and aesthetic improvements through systematic diagnosis and treatment procedures in a 48-year-old male patient with unaesthetic anterior teeth proportion because of tooth wear accompanied by the compensation of alveolar bone and defect of several central incisors due to chronic periodontitis.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.4
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• pp.425-442
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• 2004

Statement of problem: A difficulty in achieving a passive-fitting prosthesis can be overcome by individual crown restoation of multiple implants. But individualized crown has another difficulty in control of contact tightness and stress distribution. Purpose: This in vitro study is to evaluate the stress distribution and the magnitude in the supporting tissues around Endopore implants with different crown lengths, interproximal contact tightness, and the splinting effects. Material & methods: Three Endopore implants($4.1{\times}9mm$) were placed in the mandibular posterior edentulous area distal to the canine and photoelastic model was made with PL-2 resin(Measurements Group, Raleigh, USA). Restorations were fabricated in two crown lengths: 9, 13 mm. For non-splinted restorations, individual crowns were fabricated on three custom-milled titanium abutments. After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal($8{\mu}m$ shim stock drags without tearing), medium($40{\mu}m$), and heavy($80{\mu}m$). For splinted restorations, 3-unit fixed partial dentures were fabricated. This study was examined under simulated non-loaded and loaded conditions(6.8 kg). Photoelastic stress analysis was carried out to measure the fringe order around the implant supporting structure. Results: 1. When restorations were not splinted, the more interproximal contact tightness was increased among the three implants, the more stress was shown in the cervical region of each implant. When crown length was increased, stresses tended to increase in the apex of implants but there were little differences in stress fringes. 2. When nonsplinted restorations were loaded on the first or third implant, stresses were increased in the apex and cervical region of loaded implant. Regardless of interproximal contact tightness level, stresses were not distributed among the three implants. But with tighter interproximal contact, stresses were increased in the cervical region of loaded first or third implant. 3. When the nonsplinted restorations were not loaded, there were little stresses on the supporting structure of implants, but low level stresses were shown in the splinted restorations even after sectioning and soldering. 4. With splinted restorations, there were little differences in stresses between different crown lengths. When splinted restorations were loaded, stresses were increased slightly on the loaded implant, but relatively even stress distribution occurred among the three implants. Conclusions: Splinting the crowns of adjacent implants is recommended for Endopore implants under the overloading situation.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.2
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• pp.176-186
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• 2016

This study was performed to compare the shape and dimension of anterior zirconia crowns to other pediatric crowns using a three-dimensional scanner to investigate adequate amount of tooth preparation. Primary central and lateral anterior zirconia crowns, stainless steel crowns and celluloid strip crowns were scanned by a three-dimensional scanner. Outer and inner surfaces of zirconia and stainless steel crowns, and outer surface of celluloid strip crowns were analyzed. In outer scanned images, all sizes of central and lateral size 1 zirconia crown had the largest labiolingual diameter among the three crowns. In inner scanned images, zirconia crown's mesiodistal diameter was 0.7-1.0 mm smaller and crown length was approximately 1 mm shorter than those of stainless steel crowns. Zirconia crown's labiolingual diameter was larger in central crowns whereas it was smaller in lateral crowns than that of stainless steel crowns. Recommended preparation required for zirconia crown is incisal 2.5-3.0 mm, mesiodistal 1.5-2.0 mm, labial 0.5-1.0 mm. Cingulum should be trimmed parallel to the long axis. No more lingual reduction is needed in central incisors whereas additional 0.5 mm reduction is suggested in lateral incisors.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.537-548
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• 2005

1. 목적 이 연구의 목적은 기존의 평가기준에 따라 관찰자에 의해 주관적으로 판단된 치은형과 실제 치은두께와의 상관관계를 규명하고 임상검사 시에 측정할 수 있는 변수들과 치은두께의 연관성을 평가하는 것이다. 2 방법 211명의 치과대학생(22-43세, 평균 24.7세)을 연구대상으로 하여 상악중절치부위에서 국소마취하에 근관 치료용 파일을 치은에 삽입하여 두께를 측정하고 임상검사를 통해 치주낭깊이, 치태지수, 치은지수, 치은퇴축, 체형 및 비만도, 피부형, 치경부의 형태, 관측자가 임의로 판단한 치은형을 기록하였다. 임상사진으로 치관의 폭경과 길이의 비율, 치은외형의 만곡정도를 조사하고 평행촬영법을 이용한 방사선사진으로 치아의 장평비율 및 치아의 치관 폭경과 치경부 폭경의 비율을 조사하였다. 전체 대상을 치은의 두께를 기준으로 평균두께보다 얇은 군과 두꺼운 군의 두 개의 군으로 분류하여 임상검사 사에 측정한 변수들이 각 군 간에 유의할 만한 차이를 보이는지와 임의로 판단한 치은형이 실제 치은두께와 연관이 있는지를 알아보았다. 통계처리는 Student t-test를 이용하였다. 3. 결과 치주낭 깊이, 치은지수, 체형 및 비만도, 피부형, 치아의 형태, 치경부의 형태, 치아의 장평비율의 경우 실제 측정하여 얻은 치은의 두께와의 상관관계는 통계적으로 유의성이 없었다. 치은의 형태는 치은의 두께와 상관성은 보이고 있으나 통계적으로 유의하지 않았다. 관측자가 임의로 평가한 치은형과 실제 측정치도 유의할만한 일치를 보이지 않고 있다. 4. 결론 치은의 형태는 치은의 두께를 예상하는데 약간의 도움이 될 수 있으나 실제 치은의 두께는 임상적으로 간단히 측정할 수 있는 겸사지수들과 직접적인 상관관계를 보이지 않았다. 따라서 치료결과의 예측에 있어서 치은형을 분류하여 예상하는 것은 큰 도움이 되지 않는다고 할 수 있다.