• Journal of dental hygiene science
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• v.13 no.4
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• pp.461-470
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• 2013

In order to examine the anticariogenic effect after fluoride varnish was applied to sound enamel and artificial caries enamel, anterior teeth of healthy cattle were used and divided into four groups such as group 1 (sound enamel), group 2 (application of fluoride varnish to sound enamel), group 3 (artificial caries enamel) and group 4 (application of fluoride varnish to artificial caries enamel). Remineralization on the surface of enamel and changes of crystalline structure after demineralization were observed by using a field emission scanning electron microscope (FE-SEM). Quantitative analysis of Ca and P was measured by using the energy dispersive X-ray spectrophotometer (EDS). The following conclusions were obtained: 1)Surface pattern of enamel was the roughest in group 3 due to the defects caused by porosity and microcracks. Group 4, group 1 and group 2 were followed in order; 2) It was found that pattern of crystalline structures in a group of application of fluoride varnish and a group of no application showed bigger change in artificial caries enamel than that in sound enamel. In other words, groups 4 and 1 showed a similar pattern; 3) The contents of Ca and P were higher in groups of application of fluoride varnish (group 2 and group 4) than in groups of no application of fluoride varnish (group 1 and group 3). Taken results of this study together, in the case of application of fluoride varnish, crystalline structure was changed by remineralization even in the sound enamel. In particular, porous structures showed a smooth and uniform pattern due to the recalcification in the artificial caries enamel. In addition, according to results of EDS analysis, the contents of Ca and P were increased and it had great anticariogenic effects which inhibit decalcification of sound enamel and artificial caries enamel.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.1
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• pp.85-94
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• 1994

The purposes of this study were clinical comparison and evaluation between digital radiography and conventional radiography for the detection of artificial interproximal caries. Four freshly extracted, unrestored posterior teeth were obtained and caries was simulated by drilling semicircled defects with variable size at the interproximal surface of each tooth. The experiments were performed with IBM-PC/32 bit-DX compatible, video camera(VM-S8200, Hitachi Co., Japan), and color monitor(Multisync 3D, NEC, Japan). Sylvia Image Capture Board for the ADC(analog to digital converter) was used, and spatial resolution was 512 × 480 with 256 gray levels. The obtained results were as follows: 1. At the condition of under exposure, the radiographs were superior to the digital images in readability. Also, as the size of the artificial lesion was increased, readability of the radiographs was elevated. 2. The digital images were superior to the radiographs in readability especially under over exsposure. 3. As the exposure time and size of lesion was increased, the gray level of region of interest of the digital image was decreased proportionally. 4. As the F-value of average gray level of region of interest at individual exposure time and size of lesion, gray level of the all lesion sizes was decreased in comparison with that of the normal enamel.

• The Journal of the Korean dental association
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• v.55 no.10
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• pp.688-694
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• 2017

Objectives: This preliminary study compared the effects of glide path establishing instruments prior to substantial root canal preparation. Materials and Methods: Glide path was established by enlargement of the 2nd mesiobuccal root canal of Dentalike by using three kinds of glide path preparation nickel-titanium file; PathFile, One G and ProGlider. The pre- and post-instrumented Dentalikes were weighed in the resolution of 1 / 10mg. In addition, after glide path preparation, torque generated during shaping using the WavoOne file was measured. The data were analyzed by one-way ANOVA and Tukey post-hoc test at a significance level of 95%. Results: The ProGlider had the significantly larger amount of reduced weight than other instrument groups (p < 0.05). There was no significant difference between group of glide path preparation with ProGlider and without glide path preparation in maximum torque and total stress generation during the shaping with WaveOne. Conclusions: Glide path preparation instruments may have different efficiency according to their geometries. The Dentalike artificial teeth were revealed to have discrepancies in the size of root canals by microCT examination. It is impossible to make a meaningful judgment of the results due to the reliability or resolution problem of the root canal size of the artificial tooth selected as the standardized tooth.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.374-382
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• 2006

Purpose: This study was designed to investigate the present conditions of illumination techniques in dental clinics in order to contribute improvement of operating environment. This study also aimed exploring qualitative and quantitative luminous intensity required for color temperature in dental clinic illumination, which was a critical part of esthetic dentistry. Materials and methods: A total of forty-eight local dental clinics were selected for sampling a) luminous intensity, and b) color temperature. The author measured the luminous intensity and the color temperature with lux meter and color meter respectively between 12pm and 2pm. The dental unit chair placed in the general operation positions were kept the distance 60 cm then all dental units were measured three times and averaged. The author measured the luminous intensity and color temperature with both common dental operating light and then without operating light in different office environments. The study was conducted under three conditions: 1 artificial illumination in clear day light 2. artificial illumination in cloudy day light, and 3. artificial illumination alone. Results : The results obtained were as follows. 1. The average luminous intensity in dental clinic lighting was 425 lux which was not sufficient to produce the optimal shade of the patient's teeth. Furthermore, the average luminous intensity even in full operating lighting was 9532 lux which fell short of the required level of 10,000 lux. 2. The average color temperature of all dental clinics surveyed was 5169 K which met the optimal range. However, only 33.3% fell in the correct region between 5,000-5,500 K as 25% were over 5,500 K and 41.6% were below 5,000 K. As a result, 66.7% were under insufficient color temperature conditions. 3. The dental unit chair placed next to a window, hence exposure to natural lighting, had significantly higher luminous intensity and color temperature compared to the dental unit chair which didn't have a window or natural lighting. 4. The data analysis revealed that only 6.3% of the dental clinic were met the standard of the average luminous intensity and color temperature.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.250-259
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• 2001

Since the late 1930s, acrylic resins have been the materials of choice for the fabrication of complete denture bases. It has excellent esthetic properties, adequate strength, low water sorption, and low solubility. But acrylic resin has disadvantage of processing shrinkage that reduces denture retention and accuracy of denture occlusion. Metals also have been used in denture base material. Metals used in denture bases display excellent strength and dimensional stability. The major disadvantages associated with metal denture bases include increased cost, difficulty in fabrication, compromised esthetic qualities, and inability to re-base. The purpose of this study is to compare the artificial tooth movements of complete dentures with resin bases and metal bases after curing, deflasking, polishing immersion in water for 1 week and 4 weeks. Twenty-four maxillary complete resin denture bases with artificial teeth were fabricated. Twelve of them were resin based and other twelve of them were metal based. Fine crosses were marked on the incisal edges of right central incisors and distobuccal cusps of be second molars. Measurements were done for the changes of distances of reference points at the time of wax denture, after deflasking after decasting after polishing after immersion in water for 1 week and 4 weeks Meaurements were done to the accuracy of 0.001mm with a measuring microscope. The results were as follows : 1. Metal base showed significantly less tooth movement than resin base after curing and decasting (p<0.01). 2. Metal base showed significantly less tooth movement than resin base after polishing (p<0.01). 3. After immersion in water for 1 week and 4 weeks, metal base showed less movement than resin base. Difference was significant for anterior-posterior distances (p<0.01), but not significant for molar-to-molar distance (p>0.01). 4. 1 week and 4 weeks of immersion failed to compensate the initial processing shrinkage of metal and resin bases (p>0.01).

• The korean journal of orthodontics
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• v.52 no.4
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• pp.268-277
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• 2022

Objective: Poor experience with Invisalign treatment affects patient compliance and, thus, treatment outcome. Knowing the potential discomfort level in advance can help orthodontists better prepare the patient to overcome the difficult stage. This study aimed to construct artificial neural networks (ANNs) to predict patient experience in the early stages of Invisalign treatment. Methods: In total, 196 patients were enrolled. Data collection included questionnaires on pain, anxiety, and quality of life (QoL). A four-layer fully connected multilayer perception with three backpropagations was constructed to predict patient experience of the treatment. The input data comprised 17 clinical features. The partial derivative method was used to calculate the relative contributions of each input in the ANNs. Results: The predictive success rates for pain, anxiety, and QoL were 87.7%, 93.4%, and 92.4%, respectively. ANNs for predicting pain, anxiety, and QoL yielded areas under the curve of 0.963, 0.992, and 0.982, respectively. The number of teeth with lingual attachments was the most important factor affecting the outcome of negative experience, followed by the number of lingual buttons and upper incisors with attachments. Conclusions: The constructed ANNs in this preliminary study show good accuracy in predicting patient experience (i.e., pain, anxiety, and QoL) of Invisalign treatment. Artificial intelligence system developed for predicting patient comfort has potential for clinical application to enhance patient compliance.

• Imaging Science in Dentistry
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• v.39 no.1
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• pp.35-39
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• 2009

Purpose: The purpose of the experiment was to evaluating the diagnostic ability of dental caries detection using digital subtraction in the artificial caries activity model. Materials and Methods: Digital radiographies of five teeth with 8 proximal surfaces were obtained by CCD sensor (Kodak RVG 6100 using a size #2). The digital radiographic images and subtraction images from artificial proximal caries were examined and interpreted. In this study, we proposed novel caries detection method which could diagnose the dental proximal caries from single digital radiographic image. Results: In artificial caries activity model, the range of lesional depth was $572-1,374{\mu}m$ and the range of lesional area was $36.95-138.52mm^2$. The lesional depth and the area were significantly increased with demineralization time (p<0.001). Furthermore, the proximal caries detection using digital subtraction radiography showed high detection rate compared to the proximal caries examination using simple digital radiograph. Conclusion: The results demonstrated that the digital subtraction radiography from single radiographic image of artificial caries was highly efficient in the detection of dental caries compared to the data from simple digital radiograph.

• Journal of dental hygiene science
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• v.5 no.1
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• pp.13-17
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• 2005

This research was conducted in order to collect and arrange an oral health information needed the school oral hygiene as a part of a long term local community oral hygiene development to promote the oral health of the residents in Sung-Nam. After gathering the information of oral hygiene of 12-year old schoolchildren in Sung-Nam, these conclusions are reached: (1) The experience of dental caries in permanent teeth of 12-year old schoolchildren in Sung-Nam was revealed 74.7%, proportion of children with one or more caries in permanent teeth was 36.2%, and DMFT index was 2.75. (2) DT rate was 28.4% in total and regional difference has been revealed. In Sujung-Gu, DT rate was 36,8% and this was nearly as twice as 19.8% in Bundang-Gu. (3) For permanent teeth, fillings requirements for one surface were 26.6%, more that two surfaces were 13.3%. In addition, artificial crown treatment requirements were 1.8%, dental pulp treatment was 5.3%, and extraction requirement was 2.2%. In contrast, holders of pit and fissure sealant were only 27.1%. (4) In Sung-Nam, oral hygiene education campaign for 12-year old schoolchildren needs to be continued. Simultaneously, early stage examination and preventive approaches for decayed teeth such as pit and fissure sealant need to be considered for schoolchildren who have high tendency of dental caries and who are in areas which show high percentage of dental caries occurrence.

• The KIPS Transactions:PartA
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• v.12A no.6 s.96
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• pp.515-522
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• 2005

This paper presents a method for effectively modeling inlay/onlay prostheses restoring a tooth that are partially destroyed. An inlay/onlay is composed of internal surface adhering to an abutment, and external surface revealed to the outside sight. Internal surfaces are modeled using Minkowski sum expanding the grinded surface parts of abutments so that the internal surfaces can adhere to the abutments with closer contact. In modeling external surfaces, we exploit 3D mesh deformation techniques: DMFFD(direct manipulation free-form deformation)[19] and MWD(multiple wires deformation)[17] with three kinds of informations: standard teeth models, mesh data obtained by scanning a plaster cast of a patient's tooth, FGP(functionally guided plane) measuring the occlusion of the patients's teeth. The standard teeth models are used for building up the basic shapes of external surfaces, while the plaster fast and FGP data are used for reflecting the unique properties of adjacent md occlusal surfaces of the patients's teeth, which are slightly different to each other but very important for correct functioning. With these informations as input data, the adjacent and occlusal surfaces are automatically generated as mesh data using the techniques of DMFFD and m, respectively. Our method was implemented so that inlay/onlay prostheses fan be designed more accurately by visualizing the generated mesh models with requirements by dentists.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.9 no.1
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• pp.20-36
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• 2000

The movements of oral surrounding muscles, lips, and tongue play a very important role while masticating, swallowing, and speaking. In case of the edentulous patient wearing dentures as well, every movement of the tongue can be seen almost the same as that of the dentulous jaw. The crushed food during mastication is swallowed and sent to pharynx. At this course, the contact of the posterior portion of tongue with dentures affects the stabilization of denture. The retention and stability of the complete dentures are related with buccinator muscles of buccal parts, lips in front, and tongue of the lingual sides. Strack(1946) insisted that the arrangement of artificial teeth in the same place as that of the natural dentition is the best way to maintain the stability of denture. In this report, I would like to introduce the several advantages of a new impression method taken simultaneously, and its procedures and clinical cases.