• 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).

• Journal of Technologic Dentistry
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• v.41 no.2
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• pp.93-100
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• 2019

Purpose: This study is making a dog dental prosthesis using digital dental technology. The mechanical strength of the prosthetic material was observed in terms of compressive strength and fracture pattern. Methods: The experiment was performed using dog mandibular molars. The teeth were scanned and modeled. The specimens were made of zirconia, PMMA and Ni-Cr. The specimens were subjected to a vertical compression test with an artificial cancellous bone in UTM tester. Vertical compressive strength and fracture behavior of specimen were observed. Results: The result of observing the compressive load between specimen and artificial bone were $184.8{\pm}5.7N$ in the zirconia specimen, $185.6{\pm}8.9N$ in the PMMA specimen, and $184.4{\pm}4.0N$ in the Ni-Cr alloy specimen. Compression marks of artificial bones were observed. The fracture strength of specimen was observed. The fracture strength of the zirconia specimen was an average of 1,381.4N. The fracture strength of the PMMA specimen was an average of 572.2N. Conclusion: The crown made of three kinds(zirconia, PMMA, Ni-Cr alloy) of materials has the strength to chew about the artificial bone. zirconia and PMMA have vertical compressive strength applicable to medium dog dental prosthetic materials.

• Tribology and Lubricants
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• v.38 no.6
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• pp.255-260
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• 2022

This research presents tetrahedral amorphous (ta-C) coating on the artificial tooth for improving the durability and functionality (esthtics, foreign body of tooth) by filtered cathodic vacuum arc (FCVA). A differentiated coating method is required for a ta-C coating on polymer owing to the low melting point of the polymer, inter-facial adhesion, low friction, and non-conductivity. Herein, ta-C coating is applied below 50℃, and the potential difference of the carbon plasma drawn to the substrate was controlled by applying a positive duct bias voltage without using a substrate bias voltage. Consequently, the ta-C coating with a thickness of 70nm using the duct bias condition of 20V with the highest plasma intensity satisfies the esthetics of the artificial tooth and had a 5B level of inter-facial adhesion. In addition, the composite hardness of ta-C/polymer is 380 MPa, and correlations with esthetics, sp³ bonding, and mechanical properties. The friction coefficient (CoF) of the ta-C coating in a water-lubricated environment is 0.07, showing a six-fold reduction in CoF compared with that of a polymer.

• Journal of Technologic Dentistry
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• v.43 no.2
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• pp.48-55
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• 2021

Purpose: This study aimed to analyze deformation according to post-curing of complete arch artificial teeth for temporary dentures printed with a digital light processing (DLP) printer. Methods: An edentulous model was prepared and an occlusal rim was produced. The edentulous model and occlusal rim were scanned using a model scanner. A complete denture was designed using a dental computer-aided design, and the denture base and artificial tooth were separated. Ten complete arch artificial teeth were printed using a 3D printer (DLP). Complete arch artificial teeth was classified into the following three groups: a group no post-curing (NC), a group with 10 minutes post-curing (10M), and a group with 20 minutes post-curing (20M). Specimens were scanned using a model scanner. The scanned data were overlapped with the reference data. Statistical analysis was performed using one-way ANOVA analysis of variance, Kruskal-Wallis test, and Mann-Whitney U test (α=0.05). Results: Regarding the overall deviation of complete arch artificial teeth, the NC group showed the lowest mean deviation of 111.13 ㎛ and the 20M group showed the highest mean deviation of 131.03 ㎛. There were statistically significant differences among the three groups (p<0.05). Conclusion: The complete arch artificial tooth showed deformation due to post-curing. In addition, the largest shrinkage deformation was observed at 10 minutes of post-curing, whereas the least deformation was observed at 20 minutes.

• Journal of Korean society of Dental Hygiene
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• v.11 no.4
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• pp.465-474
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• 2011

Objectives : The removal of most reliable mechanical dental plaque that is to say tooth brushing was generalized to control of dental plaque, many oral health goods have also developed due to the effect differences followed by individual habit. The electric toothbrush have studied and developed widely as major field of study that electric toothbrush having various moving phase was sold and developed at the market. Methods : Accordingly author studied about selling electric toothbrushes shape (vibration type, ultra-sonic minuteness vibration type, semi rotation type) to raise the efficiency after comparing to the moving them that total 8 groups classified by poor tooth models for example normal set of tooth, crowding tooth, bracket attached tooth, prosthetic status etc. and executed plaque removal effect on the tooth through comparing experiment. Results : The removal rate of artificial plaque on the tooth was improved in proportion to the increase of tooth brushing time(p<0.05). The ultra-sonic minuteness vibration and semi rotation type was superior to toothbrush of vibration type comparing to the removal rate of plaque on the tooth(p<0.05). Conclusions : The electric toothbrush of supersonic minuteness vibration and semi rotation type can be recommended most of tooth types regardless of oral tooth setting status for example, normal set of tooth, crowding tooth, bracket attached tooth, porcelain tooth.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.5
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• pp.438-443
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• 2004

Objectives : The proper development of the facial structures relies upon a sequence of tightly regulated signaling interactions between the ectoderm and mesoderm involving the participation of several families of signaling molecules. Among these, bone morphogenetic proteins (BMPs) have been suggested to be a key signal that regulates the development of the mandible and the initiation and morphogenesis of the teeth. The aim of this study was to examine the artificial development of the mandibular structures and to examine the role of BMPs on tooth morphogenesis and differentiation using an organ culture system. Materials and Methods : The tooth germs from Ed 11.5, 13.5 mice were dissected, and transplanted into the diastema of the mandible primordia. The mandibles containing the transplanted tooth germs were cultured in vitro. During this period, beads soaked with BMP4 were implanted around the transplanted tooth germs. In addition, a diastema block containing the transplanted tooth germ was dissected, then transferred to an adult mouse kidney. After the organ culture, the developing mandibular explant was removed from the kidney and prepared for the tissue specimens. Odontogeneis of the transplanted tooth germs was examined after Hematoxylin-eosin, Masson-trichrome staining. Results : Proliferation and differentiation of the tooth germs cultured in the diastema was observed. In the BMP4-treated tooth germs, the formation of the first and second molars was noted. The crown of the developing tooth showed the formation of a mature cusp with the deposition of enamel and dentin matrix. In conclusion, it was confirmed that BMP4 is involved in the formation of a dental crown and the differentiation of ameloblasts and odontoblasts of the molar tooth during the development of the transplanted tooth germs.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.373-376
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• 2021

Tested the flexural strength and maximum load of two types of dental 3 D printed temporary tooth materials of the DLP method. The average flexural strength was 206.98 MPa in the test group and 139.77 MPa in the control group. The average flexural strength of the experimental group was 67.21 MPa higher than that of the control group. In the maximum load experiment, an average of 44.16N in the experimental group and 37.31N in the control group were measured. The average value of 6.85N was higher in the experimental group, and the durability of the artificial tooth restoration was improved.

• Journal of Biomedical Engineering Research
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• v.11 no.2
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• pp.295-304
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• 1990

In order to use for artificial dental tooth (dental crowens) , new glass-ceramics material has been studied. Its basic composition and the condition of heat treatment for crystalization, mechanical and chemical properties were investigated. Adding of the LAS system composition in the basic glass, time and temperature for crystalization were shortened. Fracture toughness (kic)of samples heat treated at 90$0^{\circ}C$ for 2 hours is 2.5-2.6MN/m3/2, the optimum condition of heat treatment for artificial tooth is A and B samples heating to 75$0^{\circ}C$ for 2 hours, raising to 90$0^{\circ}C$ and maintaining at 90$0^{\circ}C$ for 2 hours and C sample heating to 75$0^{\circ}C$ maintaining at 75$0^{\circ}C$ for 2 hours. In acid and'alkali solution, chemical durability is excellent.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.413-439
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• 1995

The purpose of this study was to evaluate the stress distribution developed in the supporting structures by mandibular distal extension removable partial dentures with 2 different direct retainer designs and with or without indirect retainer and abutment splinting. The examined direct retainers on the second bicuspid abutment tooth were Akers clasp and RPA clasp, the indirect retainer was located on the mesial fossa of the first bicuspid, and the first and second bicuspid were splinted in case of tooth splinting. Total 8 cases were compared and analyzed with 3-dimensional finite element method. 150N were applied vertically on the artificial teeth of the removable partial denture, and then stress distribution patterns were analyzed and compared. The results were as follows : 1. The forces transmitted to the abutment tooth were primarily from the occlusal rests. 2. The abutment tooth was displaced distally when the force was applied. The compressive stress was observed at the distal root surface of the abutment tooth and the tensile stress, at the mesial root surface. 3. The denture base was displaced posteriorly and inferiorly when the force was applied. At the more distal portion of the denture base, the greater displacement was observed.And the anterior portion of the major connector was displaced superiorly. 4. The occlusal rest placed on the distal part of the abutment tooth tended to tip the tooth more posteriorly than did one on the mesial part of that tooth. 5. Severe superior displacement was observed at the anterior portion of the major connector in case of removable partial dentures without indirect retainer. 6. In case of tooth-splinting, the stress was distributed through all the root surface of both abuments. In case of no tooth-splinting, the stress was concentrated on the distal root surface of the primary abutment.

• 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.