This study was designed to compare the effect of polishing on surface roughness of composite resin. We used Z100(3M) composite resin and placed the composite resin in the hole (4mm thick and 4mm in diameter) of vinyl plate and polymerized it under manufacturer's instructions. Samples were divided into 5 groups by polishing methods. Group 1 was control: resin was polymerized under glass plate, Group 2: resin was polymerized without any polishing procedure, Group 3: resin was polymerized with a polishing procedure of abrasive disc, Group 4: bonding agent was applyed in thin layer an polymerized on the polished polymerized resin surface, Group 5: resin was polymerized under transparent celluloid strip. The surface roughness of each specimen was measured with Sufacoder SEF-30D (Kosaka lab. Ltd) under 0.08mm cut off, 0.05mm/s stylus speed, x40 horizontal magnification, x5000 vertical magnification. The results were as follows : 1. Group 1 showed the most smooth surface in this study. 2. Group 3 showed more rough surface than Group 2. Considering the surface roughness, it would be better to make the shape completely before polymerize the resin. To finish and polish after the polymerization of resin makes less smooth surface. 3. When we use the transparent celluloid strip, minimum finishing procedures are recommended. Any polishing procedure could not recover the smooth resin surface of celluloid strip. 4. Application and polymerization of the thin layer of bonding agent on the polished surface showed the minimum surface smoothing effect.
Glass ; Polymerization ; Polymers

Three linear strain gauges (KFR-02N-120-C1-23, Kyowa, Japan) were placed around the abutment of implant fixture and the maximum axial loads on the mandibular implants supporting overdentures were registered in experimental model when the overdenture was removed. The overdenture attachments used in this study wee Round bar, Hader bar, Dolder bar with and without spacer. The retention of bar attachment was measured using universal testing machine while being controlled by Activating set and Deactivator except in case of the Hader bar. Simultaneously strains were recorded with the strain smart program in strain P-6000 series (Measurement group, Raleigh, USA). The maximum axial load was calculated and compared with each other. The results were as follows: 1. The amount and the timing of the maximum axial loads were different between the right and left implant in all attachment systems. 2. The retention of bar attachment except Hader bar could be adjusted but the controllability was different among the attachment systems. 3. The more the axial load, the higher the retention with Hader bar and Dolder bar without spacer. but the tendency of increase was not shown with round bar and Dolder bar with spacer.
Denture, Overlay* ; Models, Theoretical

The purpose of this study was to compare the corrosion characteristics between implant fixture and two types of abutment screw; gold screw, titanium screw. The anodic polarization behavior, the galvanic corrosion behavior, and the crevice corrosion behavior of prepared samples were investigated using potentiostat and scanning electron microscope. The results were as follows : 1. Anodic polarization behavior of samples: The primary passivation potential of implant fixture was -420mV, implant abutment was -560mV, titanium screw was -370mV and gold screw was -230mV. All samples were shown to have a high corrosion potential and good formation of passive film. The critical passive current density of gold screw was higher than of other samples and the sample of gold screw showed a unstable passive film formation at passive region. 2. Galvanic corrosion behavior of samples: Contact current density between implant fixture and titanium screw showed 8.023x 10-5C/cm2. Contact current density between implant fixture and gold screw showed 5.142x 10-5C/cm2. 3. Crevice corrosion behavior of samples : The crevice corrosion resistance of sample using titanium screw was higher than that of sample using gold screw, and a severe corrosion morphologies were observed at the fixture-screw interface by the scanning electron microscope.
Corrosion* ; Titanium

Dental porcelain should have adequate strength and similar esthetics as natural teeth. Recently esthetics has become a high priority in clinical dentistry. Thus the evaluation of color stability of dental porcelain has become an important part in dental research. The purpose of this study was to evaluate the difference in color stability of 3 types of porcelain (Vintage, VMK 95, CERAMCO II). The porcelain were divided into groups by 2 types of treatment (Glazing or non-glazing and thermocycling or non-thermocycling). The porcelain wee dyed with methylene blue and distilled water, and then the color stability was evaluated with a spectrophotometer. The results were as follow ; 1. The color change of porcelain increased in the order of VMK 95, Vintage, CERAMCO II. But there was no significant difference. 2. The color change decreased in the glazing group compared to the non-glazing group(p<0.05). 3. The color change increased after thermocycling But there was no significant difference. 4. The color change according to dye method was significantly larger with methylene blue copared to distilled water(P<0.05).
Crowns* ; Dental Porcelain* ; Dental Research ; Dentistry ; Esthetics ; Methylene Blue ; Tooth ; Water

This study was performed to investigate the effects of tooth mobility and design of the direct retainer on the stress of supporting tissues in distal extension removable partial denture. Tooth mobility was simulated and four different types of direct retainer such as Akers clasp, I-bar clasp, wrought wire, and Dalbo attachment were designed and stress o the supporting tissues were measured and analyzed with straingauge method. The following conclusions were drawn from this study. 1. The stress revealed at the lingual side of alveolar bone of the abutment tooth in edentulous area was the largest. 2. The stress at the lingual side of alveolar bone of the abutment tooth in edentulous area was increased according to the increases of tooth mobility in I-bar clasp and Dalbo attachment. 3. The stress at the residual ridge crest was the great in Dalbo attachment on mobility 0, in I-bar clasp on mobility 1, and in wrought wire clasp on mobility 2. 4. There was little changes of stress according to the increase of tooth mobility at buccal and lingual side of the residual ridge crest and around the abutment teeth in dentulous area.
Denture, Partial, Removable* ; Tooth Mobility* ; Tooth*

The purpose of this study was to investigate the causes of food impaction and to explore solutions as well. For this study, 39 patients with food impaction wee selected. 77 contact areas in these patients were investigated mobility, tightness of contact area, gingival index, plaque index, attachment loss, alveolar bone loss, proximal caries, marginal ridge distance and occlusal relationships. The results were as follows ; 1. Teeth without distal support were found to be the most frequent site of food impaction (41.6%). Food impaction was found to be more frequent in the upper teeth (66.2%) than the lower teeth (33.8%). 2. Food impaction was found in tight contact cases (71.4%). Alveolar bone loss was not found in the early stage of food impaction (83.1%) 3. The distance between the marginal ridges of food impaction sites (mean=0.48mm) was shorter than that of the control group. (mean=0.77mm) (p<0.001) 4. In 18.2% of t he cases, proximal carries were found at the food impaction site. 5. Food impaction affected patient's occlusion with the following frequencies ; cusp to marginal ridge relationship (72.7%), cusp to fossa relationship (3.9%) and stepped relationship (23.4%).
Alveolar Bone Loss ; Humans ; Periodontal Index ; Tooth

Cleft lip and palate is congenital deformity in oral and maxillofacial area. Normal soft palate has velopharyngeal closure action by connecting oral cavity and nasal cavity at rest and moving upward at swallowing and specific pronunciation. Cleft palate patients with velopharyngeal insufficiency have difficulty in mastication, swallowing and pronunciation because velopharyngeal closure is incomplete. At this time, a prosthetic device used to cover palate defects is called a palatal obturator. A palatal obturator separates oral cavity and nasal cavity and recovers pronunciation, mastication, swallowing and esthetic function. The purpose of this case study is to report the results because it reaches a satisfactory result in functional and esthetic aspects through functional impression procedures using modeling compound and tissue conditioner for restoration of a cleft palate patient with velopharyngeal insufficiency.
Cleft Lip ; Cleft Palate* ; Congenital Abnormalities ; Deglutition ; Humans ; Mastication ; Mouth ; Nasal Cavity ; Palatal Obturators* ; Palate ; Palate, Soft ; Velopharyngeal Insufficiency*

Malignant tumours of the oral cavity that require resection of the tongue result in severe deficiencies in speech and deglutition. In such patients, improvements in mastication, swallowing, and speech may be reasonable goals for treatment. The viability of a prosthodontic approach to treatment depends on the type and extent of surgery. In a total glossectomy, a mandibular tongue prosthesis is the treatment of choice. Mandibular tongue prosthesis occupies the space in the floor of the oral cavity. It provides the patients with a platform for directing food into the esophagus and aids in speaking. This type of prosthesis can achieve that protection of the underlying fragile tissue and improvement in appearance and psychosocial adjustment. This case report describes the technical steps involved in prosthetic rehabilitation for a glossectomy patient.
Deglutition ; Esophagus ; Glossectomy* ; Humans ; Mastication ; Mouth ; Prostheses and Implants ; Prosthodontics ; Tongue

In case of missing of permanent teeth by trauma or innate defect, the decision of treatment modalities and application timing have an important effect on the prognosis of oral rehabilitation. In this case report, interdisciplinary approach between the orthodontic and prosthodontic treatment, the way to re-establish the collapsed occlusal vertical dimension, and implant prosthetic considerations will be discussed. Proper diagnosis on teeth and craniofacial skeleton was made prior to treatment and provisional restorations were used in regard of growth patterns of the patient. Finally, the edentulous areas were restored with fixed implant prostheses. Diagnosis, treatment rationale and prognosis will be discussed thoroughly.
Adolescent* ; Growth and Development ; Humans ; Prognosis ; Prostheses and Implants ; Prosthodontics ; Tooth* ; Vertical Dimension

STATEMENT OF PROBLEM: Several domestic dental implants have been developed since dental treatment being implants are increasing and popularized. However, they have not been used in domestic market like imported goods. MATERIAL AND METHODS: This study was carried out to compare domestic and imported implants in aspect of fitness, dental implant fixture and abutment screw using scanning electron microscope. All experiments were performed under dry condition. RESULTS: 1. Only in aspect of relation of dental implant fixture and abutment screw, except only one group with point contact, good fitness was existed. 2. Home products must presevere in their efforts, so as excellent to fit.
Dental Implants