• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.33.1-33.7
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• 2019

Background: The concept of the ideal morphology for the alveolar bone form is an important element to reconstruct or restore the in maximizing esthetic profile and functional alveolar bone restoration. The purpose of this preliminary study is to evaluate the normal alveolar bone structure to provide the standard reference and guide template for use in diagnosing for implant placement, determining the correct amount of bone augmentation in actual clinical practice and producing prostheses based on three-dimensional imaging assessment of alveolar bone. Methods: This study was included 11 men and 11 women (average age, 22.6 and 24.5 years, respectively) selected from among 127 patients. The horizontal widths of alveolar bone of maxilla and mandible were measured at the crestal, mid-root, and root apex level on MDCT (multi-detector computed tomography) images reconstructed by medical imaging software. In addition, tooth dimensions of the central incisors, canines, second premolars, and first molars of maxilla and mandible, including the horizontal width of the interdental alveolar bone crest, were also measured and statistically analyzed. Results: The horizontal alveolar bone width of the palatal side of maxilla showed a distinct increment from the alveolar bone crest to the apical region in both anterior and posterior areas. The average widths of the maxillary alveolar ridge were as follows: central incisor, 7.43 mm; canine, 8.91 mm; second premolar, 9.57 mm; and first molar, 12.38 mm. The average widths of the mandibular alveolar ridge were as follows: central incisor, 6.21 mm; canine, 8.55 mm; second premolar, 8.45 mm; and first molar, 10.02 mm. In the buccal side, the alveolar bone width was not increased from the crest to the apical region. The horizontal alveolar bone width of an apical and mandibular border region was thinner than at the mid-root level. Conclusions: The results of the preliminary study are useful as a clinical guideline when determining dental implant diameter and position. And also, these measurements can also be useful during the production of prefabricated membranes and customized alveolar bone scaffolds.

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.139-146
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• 2012

Purpose: An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement. Materials and Methods: A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated. Results: The deviation of the entry point and angulation of the central axis in the reference plane were $0.47{\pm}0.27$ mm, $0.57{\pm}0.23$ mm, and $0.64{\pm}0.16^{\circ}$, $0.57{\pm}0.15^{\circ}$, respectively. However, for the two different angulations in each group, the $20^{\circ}$ angulation showed a greater error in the deviation of the entry point than did the $10^{\circ}$ angulation. Conclusion: The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.

• Journal of Korean Dental Science
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• v.15 no.1
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• pp.1-8
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• 2022

Purpose: Intraoral scanners, desktop scanners, and cone-beam computed tomography (CBCT) are being used in a complementary way for diagnosis and treatment planning. Limited patient-based results are available about dimensional reproducibility among different three-dimensional imaging systems. This study aimed to evaluate dimensional reproducibility among patient-derived digital models created from an intraoral scanner, desktop scanner, and two CBCT systems. Materials and Methods: Twenty-nine arches from sixteen patients who were candidates for implant treatments were enrolled. Different types of CBCT systems (KCT and VCT) were used before and after the surgery. Polyvinylsiloxane impressions were taken on the enrolled arches after the healing period. Gypsum casts were fabricated and scanned with an intraoral scanner (CIOS) and desktop scanner (MDS). Four test groups of digital models, each from CIOS, MDS, KCT, and VCT, respectively, were compared to the reference gypsum cast group. For comparison of linear measurements, intercanine and intermolar widths and left and right canine to molar lengths were measured on individual gypsum cast and digital models. All measurements were triplicated, and the averages were used for statistics. Bland-Altman plots were drawn to assess the degree of agreement between each test group with the reference gypsum cast group. A linear mixed model was used to analyze the fixed effect of the test groups compared to the reference group (α=0.05). Result: The Bland-Altman plots showed that the bias of each test group was -0.07 mm for CIOS, -0.07 mm for MDS, -0.21 mm for VCT, and -0.25 mm for KCT. The linear mixed model did not show significant differences between the test and reference groups (P>0.05). Conclusion: The linear distances measured on the digital models created from CIOS, MDS, and two CBCT systems showed slightly larger than the references but clinically acceptable reproducibility for diagnosis and treatment planning.

• Journal of Periodontal and Implant Science
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• v.39 no.sup2
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• pp.269-278
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• 2009

Purpose: The aim of this study was to investigate matrix metalloproteinase 1 (MMP-1) gene polymorphism (1G/2G at -1607 and A/G at -519) in Korean subject and to assess the association between polymorphism and periodontal status. Methods: Forty nine generalized aggressive periodontitis (GAP) patients and 57 periodontally healthy children were recruited and genomic DNA was extracted from buccal swab. The polymorphisms of MMP-1 promoter genes were determined by polymerase chain reaction and restriction fragment length product (PCR-RFLP) method. The distribution of genotype and allele frequency was compared between 2 groups by ${\chi}^2$ test. Results: There was a significant difference in the distribution of genotypes and frequency of alleles between the GAP and reference groups at the position - 519 of MMP-1 gene promoter (P<0.05). Allele G carrier rate was significantly lower in GAP group than that of the reference group (P< 0.001). At the position -1607 of MMP-1 gene promoter, genotype distribution and allele frequency showed no statistically significant difference between the groups. However, in the female group, a significant difference was observed between the groups for the genotype distribution, allele frequency and allele 1G carrier rate (P< 0.05). Conclusions: The DNA polymorphism at the MMP-1 gene promoter might be associated with GAP in Korean.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.595-604
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• 1993

Since $Gr{\"{o}}nadhl$ et al introduced a digital subtraction radiography into periodontal dignosis in 1983, many reports using this system has aimed to assess the peroiodontal disease activity and the alveolar bone changes after periodontal treatment. The present study was performed to evaluate the usefulness of digital subtraction radiography for asessing an alveolar bone changes in 3 months after periodontal flap surgery. Serial intraral raiographs were taken from 5 normal subjects and 6 periodontally diseased patients using customized bite blocks attached to film holder in fxation device and digitized by image processing system(consisting of IBM 386, digital frame grabber, CCD camera, Image-pro II software). And the reference parameters were measured by pixel unit and compared with respective radiographs. The serial radiographs showed a little and statistically insignificant difference in reference paramenters. The conventional intraoral radiographs, the subtraction images and the clor enhanced subtraction images were reviewed by 4 examiners and the examiner's agreement rates were compared. The subtraction images and its color enhanced images showed higher examiner's agreement rate than the conventional radiographs. And the propotions of sites diagnosed with bone loss or gain after periodontal surgery were highter in the subtraction images and its color enhanced images than in the conventional radiographs. Especially, in color enhanced images, the unber of bone agin sites tended to increase according to post-surgery periods. These results indicate that projection geometry could be standardized with the divice used in this study, and the subtraction radiography may be useful to assess an alveolar bone changes after periodntal flap surgery.

• The Journal of Advanced Prosthodontics
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• v.14 no.6
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• pp.379-387
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• 2022

PURPOSE. The aim of this study is to compare the casts obtained by using conventional techniques and liquid crystal display (LCD) three-dimensional (3D) print techniques in the All-on-4 treatment concept of the edentulous mandibular jaw. MATERIALS AND METHODS. In this study, a completely edentulous mandibular acrylic cast (typodont) with bone-level implants placed with the Allon-4 technique served as a reference cast. In this typodont, impressions were taken with the conventional technique and dental stone casts were obtained. In addition, after scanning the acrylic cast in a dental laboratory scanner and obtaining the Standard Tessellation Language (STL) data, 3D printed casts were manufactured with a 3D printing device based on the design. The stone and 3D printed casts were scanned in the laboratory scanner and STL data were obtained, and then the interimplant distances were measured using Geomagic Control X v2020 (3D Systems, Rock Hill, SC, USA) analysis software (n = 60). The obtained data were statistically evaluated with one-way analysis of variance (ANOVA) and Tukey's pairwise comparison tests. RESULTS. As a result of the one-way ANOVA test, it was determined that the stone casts, 3D printed casts, and reference cast values in all distance intervals conformed to the normal distribution and these values had a significant difference among them in all distance intervals. In Tukey pairwise comparison test, significant differences were found between casts at all distance intervals. In all analyses, the level of significance was determined as .05. CONCLUSION. 3D printed casts obtained with a 3D LCD printing device can be an alternative to stone casts when implants are placed in edentulous jaws. [J Adv Prosthodont 2022;14:379-87]

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.3
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• pp.70-80
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• 2010

This study proposes the algorithm to automate image alignment and detect marginal bone destructions, based on subtraction radiography for dental radiographic images necessary for dental PACS, which hasn't been covered by related literatures. The proposed algorithm enables a quick and precise detection of marginal bone destructions around teeth including implant through the knowlege-based multi-template matching in reference to ROI(Region Of Interest) obtained from applicable teeth using information about their geometric forms to solve problems single-template matching is exposed to. Actually, the test showed that it was possible not only to quickly and precisely detect marginal bone destructions around teeth, but also to get more objective and quantitative results through the algorithm.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.679-693
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• 1995

The present study has been performed to see the intrafamilial transmission of periodontopathic organism Actinobacillus actinomycetemcomitans in Koreans having various froms of periodontal diseases. 17 clinical isolates from 8 periodontal patients and 20m clinical isolates from their 8 family members were grown anaerobically for the serotyping and the extraction of genomic DNA. The DNA was digested with restriction endonucleases (EcoRI+HindIII) and plasmid pAA 2097(kindly provided by Dr. DiRienzo, Univ. of Pennsylvania) including 4.7kb-size randlomly clone probe for restriction length pleomorphism analysis(RFLP). RFLP patterns of reference serotypes a, b, c, d, and e were used as the genotypes A, B, C, D, and E, respectively for comparison of genotypes of clinical isolates. 28 out of total 37 clinical isoltes belonged to either one of 5 basic gentotypes and 9 remaining isolats did not fall into any types, and hence were designate as non-type(NT). Genotype C were the most frequently found one(35.1%) and genotype B has not isolated. Intrafamilial transmission of bacteria between spouses, brothers and sisters, and parents and their offsprings, resepctively could well be demonstrated by comparing RFLP patterns. There were not any specific genotypes which showed predominance over others in terms of transmission.

• Journal of Korean society of Dental Hygiene
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• v.9 no.3
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• pp.294-305
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• 2009

Objectives : The purpose of this study was to conduct a survey on the senses of employment so that it could provide a basic reference required for good human resources specializing in oral health with responsibility as professional. Methods : To meet these goals, a self-administrated questionnaire survey was conducted to dental hygiene college students in Gwang-ju. Results : 1. It was found that 30.7% respondents wanted to be employed as government officials of oral health. Most respondents 37.4% answered that faithfulness is the highest value as prerequisite for employment in hospital. 2. It was found that interpersonal relationships among employees had most significant effects 4.58 score on selection of employment, which was followed by in-house welfare benefit (hospital size, rest room, ect; 4.31). 3. The survey on respondents' occupational sense was represented by hospital/clinic management and dental management support 25.2%, oral health education 22.7%, oral disease prevention 19.7% respectively. Conclusion : For future social awareness about dental hygienists as occupation, desirable training courses as a part of qualification for professional dental hygienists were represented by case management (services, manners, ect; 25.0%), implant (22.8%), esthetics 14.7% and so on. As for working years, it was noted that 13.2% respondents would keep working as dental hygienists as long as they could.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.27-35
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• 2021

Purpose: The purpose of this study is to compare the accuracy of digital scans of implants according to different shapes of scanbodies, and to compare the accuracy of library merging according to different oral exposure height. Materials and methods: A master model with a single tooth edentulous site was prepared. For the first experiment, three types of intraoral scanbodies were prepared, divided into three groups, and the following experiments were conducted for each group: An internal hex implant was placed. The master model with the scanbody connected was scanned with a model scanner, and a master reference file (control group) was created. 10 files (experimental group) were created by performing 10 consecutive scans with an intraoral scanner. After superimposing the control and experimental groups, the following values were calculated: 1) Distance deviation of a designated point on the scanbody 2) Angle deviation of the major axis of the scanbody. For the second experiment, the scanbody scan data were prepared in 6 different heights. Library files were merged with each of the scan data. The distance and angular deviation were calculated using the 7 mm scan data as control group. Results: In the first experiment, there were no significant differences between A and B (P=.278), B and C (P=.568), and C and A (P=.711) in the distance deviations. There were no significant differences between A and B (P=.568), B and C (P=.546), and C and A (P=.112) in the angular deviations. Also, the scanbody showed significantly higher library merging accuracy in the groups with high oral exposure height (P<.5). Conclusion: There were no significant differences in scan accuracy according to the different shapes of scanbodies, and the accuracy of library merging increased according to exposure height of the scanbody in the oral cavity.