A precise fit of the implant prosthesis is one of the most important factors in preventing mechanical complications. To analyze the degree of the misfit of implant prosthesis, a modal testing experiment was accomplished. And to interpret the modal testing analysis mathematically, three-dimensional finite element models were established. In the experimental modal testing analysis, with a laser displacement meter, FFT analyzer, impact hammer, etc., natural frequencies of the models with various degree of prosthesis fit were determined after the frequency response function were calculated. In the finite element analysis, the natural frequencies and mode shapes of the models which simulated those of experimental modal testing were computed. The results were as follows : 1. Natural frequencies of the prosthesis-abutment were related to the contact state between components. 2. In the modal testing experiment, the natural frequencies increased from 50micrometer to 200micrometer gap and reached a plateau. 3. In the finite element analysis, the natural frequencies decreased gradually according to the increase of the gap size. 4. In the finite element analysis, the mode shapes of model 1 with misfitting prosthesis showed different patterns from those without misfitting prosthesis. 5. The devices including a laser displacement meter used in this study were useful for measuring the natural frequencies of an implant prosthesis which had various degrees of fit.
Finite Element Analysis ; Prostheses and Implants*

STATEMENT of THE PROBLEM: Recently an innovative method of fabricating indirect restorations by gold electroforming has been developed. But the bond quality and strength of the gold coping to the porcelain is uncertain. PURPOSE of STUDY: The purpose of this study is to analyze and evaluate the electroformed gold surface for mechanical bonding between the gold and the ceramic veneering. METHODS and MATERIAL: Electroformed disks were made using electroforming technique. And the surface of the electroformed coping was analyzed after sandblasting, heat-treatment, bonding agent application, opaque porcelain firing with scanning electron microscopy and energy dispersive x-ray analysis. Results. In the analysis with SEM, Sandblasting made the sharp edges and undercuts on the electroformed surface, and after bonding agent application, net-like structure were created on the electroformed surface. In the energy dispersive x-ray analysis it is confirmed that electroformed surface contains some impurities. CONCLUSION: With the use of sandblasting and bonding agent, electroformed surface seems to be enough to bond with veneering porcelain.
Ceramics* ; Dental Porcelain ; Fires ; Microscopy, Electron, Scanning

A case of papillary eccrine adenoma on the right hand of a 84-year-old woman is reported. The tumor was 1 cm in diameter, occupying the whole thickness of the dermis. Histologically, the tumor was composed of dilated tubules of various sizes with intraluminal papillary projections, and was surrounded by a fibrous stroma. An immunohistochemical study revealed that the proliferating tubules were composed of the outermost layer of alpha-smooth muscle actin-positive and the inner layer of keratin 14-negative cells. This antigen expression pattern was comparable to that of the normal eccrine secretory coil, which indicates that the tumor differentiated toward the secretory coil of an eccrine sweat gland.
Adenoma* ; Aged, 80 and over ; Dermis ; Female ; Hand ; Humans ; Sweat Glands

PURPOSE: The purpose of this study was to compare men with women in terms of speech intelligibility, to investigate the validity of objective acoustic parameters related with speech intelligibility, and to try to set up the standard data for the future study in various field in prosthodontics. MATERIAL AND METHODS: Twenty men and women were served as subjects in the present study. After recording of sample sounds, speech intelligibility tests by three speech pathologists and acoustic analyses were performed. Comparison of the speech intelligibility test scores and acoustic parameters such as fundamental frequency, fundamental frequency range, formant frequency, formant ranges, vowel working space area, and vowel dispersion were done between men and women. In addition, the correlations between the speech intelligibility values and acoustic variables were analyzed. RESULTS: Women showed significantly higher speech intelligibility scores than men and there were significant difference between men and women in most of acoustic parameters used in the present study. However, the correlations between the speech intelligibility scores and acoustic parameters were low. CONCLUSION: Speech intelligibility test and acoustic parameters used in the present study were effective in differentiating male voice from female voice and their values might be used in the future studies related patients involved with maxillofacial prosthodontics. However, further studies are needed on the correlation between speech intelligibility tests and objective acoustic parameters.
Acoustics ; Female ; Humans ; Male ; Phonetics ; Prosthodontics ; Speech Intelligibility ; Voice

PURPOSE: The purpose of this study was to compare the functional abilities of the low bulb obturators with those of high bulb obturators in terms of patients' evaluation. MATERIAL AND METHODS: This study included 11 maxillectomy patients who underwent postoperative prosthodontic rehabilitations. Two obturators of the same design except for different bulb heights, were fabricated for each of the maxillectomy patient. After two months of alternate use, the functions of the obturators were measured by investigating the patients' subjective evaluations in terms of convenience, speech, nasality, leakage, and mastication and identifying their preferred prostheses. Wilcoxon signed rank test was used as a statistical method (P < .05). RESULTS: There were no significant differences in patient evaluations of low and high bulb obturators (P >.05). And patients' preferences varied. CONCLUSION: In extreme situation such as in mouth opening limitation, the use of low bulb obturators can be recommended and result in comparable speech function to that of obturators with high lateral walls.
Humans ; Mastication ; Mouth ; Prostheses and Implants ; Prosthodontics

The digital facebow device records the trajectory of the mandibular movement where it is then reflected on the computer-aided design software, leading to an improvement on treatment outcomes of prosthetic restorations. In this clinical case, using a digital technology, an implant placement and prosthetic restoration were done in a patient who has lost maxillary and mandibular molars. Following an intraoral scan, a surgical stent for implant surgery was fabricated based on digital diagnostic wax-up, and implants were installed. After six months of sufficient osseointegration, customized abutments and the first temporary prostheses were delivered. Then two months later, at an abutment level, an intraoral scan and digital facebow transfer device were used to mount the intraoral scan data on a virtual articulator, and record the mandibular movements. Once the second temporary prostheses were fabricated and delivered on a basis of the mandibular movement, the definitive zirconia prostheses were designed and delivered based on a stabilized occlusion that was duplicated via double scan technique.

PURPOSE: The purpose of this study was to compare stress distributions of implant-supported crown placed in fibula bone model with those in intact mandible model using three-dimensional finite element analysis. MATERIALS AND METHODS: Two three-dimensional finite element models were created to analyze biomechanical behaviors of implant-supported crowns placed in intact mandible and fibula model. The finite element models were generated from patient's computed tomography data. The model for grafted fibula was composed of fibula block, dental implant system, and implant-supported crown. In the mandible model, same components with identical geometries with the fibula model were used except that the mandible replaced the fibula. Vertical and oblique loadings were applied on the crowns. The highest von Mises stresses were investigated and stress distributions of the two models were analyzed. RESULTS: Overall stress distributions in the two models were similar. The highest von Mises stress values were higher in the mandible model than in the fibula model. In the individual prosthodontic components there was no prominent difference between models. The stress concentrations occurred in cortical bones in both models and the effect of bicortical anchorage could be found in the fibula model. CONCLUSION: Using finite element analysis it was shown that the implant-supported crown placed in free fibula graft might function successfully in terms of biomechanical behavior.
Crowns ; Dental Implants ; Fibula ; Finite Element Analysis ; Mandible ; Mandibular Osteotomy ; Mandibular Reconstruction ; Prosthodontics ; Transplants

PURPOSE: The purpose of this study was to analyze the influence of the platform switching concept on an implant system and peri-implant bone using three-dimensional finite element analysis. MATERIALS AND METHODS: Two three-dimensional finite element models for wide platform and platform switching were created. In the wide platform model, a wide platform abutment was connected to a wide platform implant. In the platform switching model, the wide platform abutment of the wide platform model was replaced by a regular platform abutment. A contact condition was set between the implant components. A vertical load of 300 N was applied to the crown. The maximum von Mises stress values and displacements of the two models were compared to analyze the biomechanical behavior of the models. RESULTS: In the two models, the stress was mainly concentrated at the bottom of the abutment and the top surface of the implant in both models. However, the von Mises stress values were much higher in the platform switching model in most of the components, except for the bone. The highest von Mises values and stress distribution pattern of the bone were similar in the two models. The components of the platform switching model showed greater displacement than those of the wide platform model. CONCLUSION: Due to the stress concentration generated in the implant and the prosthodontic components of the platform switched implant, the mechanical complications might occur when platform switching concept is used.
Crowns ; Dental Implant-Abutment Design ; Dental Implants ; Finite Element Analysis*

This study evaluated the effect of two different calcium hydroxide (Ca(OH)2) paste removal techniques on the apical leakage of canals obturated with gutta percha cones and sealer after removing a Ca(OH)2 dressing using an electrochemical method. Seventy extracted single-rooted teeth were instrumented on with Profile rotary files under NaOCl irrigation. Fifty-eight canals were filled with calcium hydroxide paste, which was then removed using one of the following two techniques. In group A, calcium hydroxide was removed using only NaOCl irrigation, and in group B, the canals were re-prepared with a Profile rotary files-one size larger than the previous instrument and were irrigated with NaOCl. In both groups, the root surfaces were coated twice with nail varnish from CEJ to an area 4 mm away from the apex after canal obturation. Apical leakage was measured using an electrochemical method for 24 days. All the specimens showed leakage that increased markedly in the first three days. There was no significant difference between the two groups (p > 0.05). The effect of two calcium hydroxide paste removal techniques on the apical leakage was not different during a short period.
Bandages ; Calcium Hydroxide* ; Calcium* ; Gutta-Percha ; Paint ; Tooth ; Tooth Cervix

OBJECTIVE: To estimate the burden of cardiovascular disease attributable to the total suspended particulates (TSP) and sulfur dioxide (SO2) in Korea using the YLD (years lived with disability) measurement. METHODS: Congestive heart failure(CHF) and myocardial infarction (MI) were chosen as the main cardiovascular diseases whose causes are attributable to the TSP and SO2 levels. In order to calculate the YLD (years lived with a disability), the following parameters in the formula were estimated. : the incidence rate, the case fatality rate, The expected duration of a disability and the average age of onset were estimated. The expected duration of a disability and the average age of onset were calculated using the DISMOD method, as developed by the GBD researchers. The burden of cardiovascular disease due to TSP and SO2 was estimated using the number of years that the patient lived with a disability. RESULTS: The YLD of the CHF due to the TSP and SO2 was attributed to the TSP (94.4 person-year) and SO2 levels (35.0 person-year). The YLD of the MI due to the TSP and SO2 was attributed to the TSP (148.4 person-year) and SO2 levels(27.6 person-year). CONCLUSION: The YLD method employed in this study was appropriate for quantifying the burden of cardiovascular disease. Therefore, it would provide a rational basis for planning a national health policy regarding the disease burden of the risk factors in Korea.
Age of Onset ; Air Pollution ; Cardiovascular Diseases* ; Estrogens, Conjugated (USP) ; Health Policy ; Heart ; Humans ; Incidence ; Korea ; Mortality ; Myocardial Infarction ; Risk Factors ; Sulfur Dioxide* ; Sulfur*