• The Journal of Advanced Prosthodontics
• /
• v.6 no.2
• /
• pp.126-132
• /
• 2014

PURPOSE. This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS. Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (${\alpha}$=0.05). RESULTS. The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION. The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.

• The Journal of Advanced Prosthodontics
• /
• v.6 no.2
• /
• pp.109-114
• /
• 2014

PURPOSE. The purpose of this study was to analyze the effect of denture cleansers on Candida albicans biofilm formation over resilient liners and to evaluate compatibility between resilient liners and denture cleansers. MATERIALS AND METHODS. Acrylic resin (Lucitone 199$^{(R)}$) and 3 resilient liners (COE-SOFT$^{TM}$, GC RELINE$^{TM}$ and SOFRELINER TOUGH TOUGH$^{(R)}$) were incubated in denture cleansers (Polident$^{(R)}$ and Cleadent$^{(R)}$) for 8 hours a day and in unstimulated saliva for 16 hours a day (n=25/gp) for 60 days. Two-way and three-way repeated measures ANOVA were performed to compare the surface roughness (Ra), pH and C. albicans binding level by radioisotope (${\alpha}$=0.05). The statistical significance of the relation between Ra and adhesion was evaluated by correlation analysis. RESULTS. The degree of Ra was significantly decreased in the following order: COE-SOFT$^{TM}$, acrylic resin, GC RELINE$^{TM}$ and SOFRELINER TOUGH$^{(R)}$. The immersion in denture cleansers significantly increased Ra of resilient liners, except for SOFRELINER TOUGH$^{(R)}$ in Cleadent$^{(R)}$. No significant differences in pH curves were observed among groups immersed in distilled water and denture cleansers. The binding levels of C. albicans were significantly decreased in the following order: COE-SOFT$^{TM}$, GC RELINE$^{TM}$, SOFRELINER TOUGH$^{(R)}$, and acrylic resin. The immersion in Cleadent$^{(R)}$ seemed to decrease C. albicans binding level on GC RELINE$^{TM}$ and SOFRELINER TOUGH$^{(R)}$. CONCLUSION. Based on the C. albicans binding levels results, it is not recommended to immerse COE-SOFT$^{TM}$ in denture cleansers, and GC RELINE$^{TM}$ and SOFRELINER TOUGH$^{(R)}$ should be immersed in Cleadent$^{(R)}$.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.28 no.1
• /
• pp.180-184
• /
• 2001

Cleidocranial Dysplasia(CCD) is an autosomal dominant human bone disease characterized by abnormal clavicles, patent sutures and fontanelles, and dental anomalies. Among dental anomalies, it is characterized that permanent dentition is severly disturbed due to multiple supernumerary teeth and abnormalities of tooth morphology. A eight-year-old female patient diagnosed as cleidocranial dysplasia visited in our hospital. Upon clinical oral exam, retained deciduous teeth, constriction of dental arch, anterior cross bite, and multiple dental caries were observed. In the dental panoramic radiograph, retained deciduous teeth and multiple supernumerary teeth in the maxilla and the mandible were found. In the cephalometric radiograph, open sutures and wormian bones were seen. In the chest P-A view absence of clavicles was observed. The cleidocranial dysplasia patients have eruption problems in permanent dentition both in regions with and without supernumerary teeth. The severely delayed or arrested eruption of permanent teeth has been ascribed to various factors : 1) The presence of multiple supernumerary teeth, 2) malformed roots with lack of cellular cementum, 3) the jaw bone being too dense, and 4) abnormal resorption of bone and primary teeth. Formation and maturation of primary teeth in cleidocranial dysplasia are normal, whereas the permanent dentition has various anomalies. Therefore, dentists should understand the development of dentition in cleidocranial dysplasia, and treat them in proper time.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.43 no.2
• /
• pp.145-150
• /
• 2016

Special Health Care Needs (SHCN) patients need regular follow-up because of high incidence and severity of oral disease. The aim of this study was to evaluate the dental treatment outcomes of SHCN patients according to follow-up patterns. SHCN patients who were treated under general anesthesia (GA) at Kyung Hee University Dental Hospital from 2006 to 2014 were included in this study. The final samples comprised of 53 patients that were divided into regular (33 patients) and irregular (20 patients) follow-up groups according to their follow-up patterns. The type of dental treatment after GA during the follow-up periods were compared. In the irregular group, aggressive treatment including endodontic, prosthetic treatment, and extraction were predominant, compared with the regular group (p < 0.05). In addition, all patients who had dental treatment under GA in follow-up periods were in the irregular group (p < 0.05). In conclusion, the results of this study provide the importance of regular follow-ups with SHCN patients and emphasize responsibilities of dentists for educating patients and their guardians.

• Journal of Technologic Dentistry
• /
• v.34 no.2
• /
• pp.83-93
• /
• 2012

Purpose: The objective of this study is to find out physical properties and the flexural strength changed by the low temperature degradation of the block which is needed to make bio-prosthetic dentistry which is better than feldspar affiliated ceramic made by building up ceramic powder and also to apply this to the clinical use of zirconia monolithic all-ceramic crown. Methods: Flexural strength of each sample was evaluated before and after the Low Temperature Degradation, and physical properties of the Tetra Zirconia Block containing 3mol % was evaluated as well. The average and standard deviation of each experimental group were came out of the evaluation. Statistical package for social science 18.0 was used for statistics. Results: The average density of the monolithic all-ceramic crown was $6.0280{\pm}0.0147g/cm$, the relative density was 99.01 %. When the sample was sintered at $1480^{\circ}C$ the diameter of average particle was $396.62{\pm}33.71nm$. All the samples had no monolithic peak after XRD evaluation but only had tetragonal peak. There were statistically significant differences in the result of flexural strength of the samples evaluated after and before the low temperature degradation, the flexural strength before the low temperature degradation was $1747.40{\ss}{\acute{A}}$, at the temperature of $130^{\circ}C$ the flexural strength after the low temperature degradation was 1063.99MPa (p<0.001). There was statistically significant difference in the result of strength of 1020.07MPa after the low temperature degradation at the temperature of $200^{\circ}C$ (p<0.001). Conclusion: The block which was made for this evaluation possesses such an excellent strength among dental restorative materials that it is thought to have no problems to use for tetragonal zirconia polycrystal.

• Journal of dental hygiene science
• /
• v.17 no.4
• /
• pp.358-367
• /
• 2017

The purpose of this study was to evaluate the influence of water infiltration and flexural strength changes in dental porcelain with glazing treatment. The block specimens were prepared as experimental materials, using feldspar type commercial dental porcelain; then, these were fired at $940^{\circ}C$ for 1 minute. The fired specimens were polished with a dimension of $40{\times}5.5{\times}5mm$. The specimens were distributed to two experimental groups: with and without glazing treatment specimens (n=5), and they were immersed in a solution of pH 7 for 3, 7, and 20 days at $40^{\circ}C$ after fabrication. To evaluate the flexural strength changes with water infiltration treatment in specimens with and without glazing, the 3-point flexural test was performed, using a universal testing machine until failure occurred. Starting powder and fired specimens consisted of amorphous and leucite crystalline phase. The Vickers hardness of fired specimens was more than 1.6 times higher than that of the enamel of natural teeth. According to porosimeter results, the specimens without glazing treatment exhibited a porosity of about 14.7%, whereas the glazed specimens exhibited the lowest porosity at about 1.1%. The average flexural strength of glazed specimens was higher than the flexural strength of specimens without glazing treatment (p<0.05). The flexural strength of all specimens with and without glazing treatment deteriorated with accelerated aging in the solution. In addition, significant differences between these two treatment groups were observed in all of the specimens treated at various water infiltration periods (p<0.05). The exposure of internal pores and micro-cracks in the surface due to polishing of the fired specimens influenced mechanical behaviors. Especially, the flexural strength in specimens without glazing treatment has shown significant degradation with the infiltration of water. Therefore, this study suggests that glazing processes can improve mechanical properties of dental porcelain.

• Journal of Technologic Dentistry
• /
• v.33 no.4
• /
• pp.349-357
• /
• 2011

Purpose: In this study, for the reasons of observing the changes when using bonding agent with Ni-Cr alloy and Co-Cr alloy and using VM13 and Vintage MP ceramic which have the disparity in coefficient of thermal expansion, it is carried out to evaluate the characteristics of the bonding agent through the analysis of the interface between metal and ceramic and the analysis of bond strength by variable. Methods: The surface treatment was performed on the two kinds of alloy(Ni-Cr alloy and Co-Cr alloy) specimens, which were sandblasted and were treated with bonder application. The metal-ceramic interfaces were analyzed with EPMA in order to ionic diffusion, and the shear test was performed. Results: As a result of observation of metal-ceramic interfacial properties, it was observed that Cr atoms were spread from the alloy body to the ceramic floor in the specimen of Group B. It was also seen that Cr, W atoms were spread from the alloy body to the ceramic floor in the specimen of Group S. In consequence of observing Shear bond strength, it was calculated that the specimen of BSV was 27.75(${\pm}11.21$)MPa, BSM was 27.02(${\pm}5.23$)MPa, BCV was 30.20(${\pm}5.99$)MPa, BCM was 27.94(${\pm}10.76$)MPa, SSV was 20.83(${\pm}2.58$)MPa, SSM was 23.98(${\pm}3.94$)MPa, SCV was 32.32(${\pm}4.68$)MPa, and SCM was 34.54(${\pm}10.63$)MPa. Conclusion: In the metal-ceramic interface of Bellabond plus sample group, diffusion of Cr atoms was incurred and diffusion of C Cr atoms and W atoms in the sample group of $Starloy{(R)}\;C$ was observed. Using bonding agent showed the higher bond strength than using the sand blasting treatment. In the Bellabond plus alloys, the specimen group with the use of binding materials showed higher shear bond strength, but didn't show statistically significant differences (p>0.05). In the $Starloy{(R)}\;C$ alloys, the specimen group with the use of binding materials showed higher shear bond strength and statistically significant differences(p<0.05). In terms of VM13 ceramic, it was in the Bellabond plus alloys that the high shear bond strength was showed, but there's no statistically significant differences(p>0.05). In terms of Vintage MP ceramic, it was in the $Starloy{(R)}\;C$ alloys that the high shear bond strength was showed and statistically significant differences(p<0.05). Metal-ceramic to fracture of the shear strength measurements and an analysis of all aspects of military usage fracture of the composite, respectively.

• Journal of Technologic Dentistry
• /
• v.33 no.4
• /
• pp.299-306
• /
• 2011

Purpose: This study aimed to investigate the shear bond strength by manufacturing the veneering porcelain on the IPS e.max $ZirCAD^{(R)}$ zirconia core, using the layering technique and heat-pressing technique, and to evaluate the clinical stability by comparing to the conventional metal ceramic system. Methods: The Schmitz-Schulmeyer test method was used to evaluate the core-veneer shear bond strength of zirconia core ceramic(IPS e.max $ZirCAD^{(R)}$) and their manufacture recommended two veneering ceramic systems(IPS e.max $ceram^{(R)}$, IPS e. max $ZirPress^{(R)}$). A metal ceramic system(Bellabond $plus^{(R)}$, VITA $VM13^{(R)}$) was used as a control group for the two all ceramic system test groups. The maximum loading and shear bond strength was measured. The average shear strength(MPa) was analyzed with the one-way ANOVA and the Tukey's test(${\alpha}$=.05). The fracture specimens were examined using Microscope to determine the failure pattern. Results: The mean shear bond strengths(SD) in MPa were MBSB control 43.62(2.13); ZBSB 18.65(1.76); ZPSB 18.89(1.54). The shear strengths of the zirconia cores were not significantly different(P>.05). Microscope examination showed that zirconia specimens presented mixed failure, and base metal alloy specimens showed adhesive failure. Conclusion: There was no siginificant different between the layering technique and the heat pressing technique in the veneering methods on the zirconia cores. None of the zirconia core and veneering ceramics could attain the high bond strength values of the metal ceramic combination.

• Journal of Technologic Dentistry
• /
• v.33 no.4
• /
• pp.369-378
• /
• 2011

Purpose: This study was carried out for the purpose of obtaining basic data necessary for developing the future oral health promotion program of the elderly by surveying the actual condition of managing dental prosthesis in the elderly. Methods: It collected materials targeting 346 elderly brackets in over 65 years old who dwell in Seoul and Gyeonggi-do Province for about 10 months from September 2010 to June 2011, analyzed 312 copies except 34 copies, which are inappropriate for data processing due to being insufficient in response among these things, and obtained the following results. Results: In the actual condition of missing tooth, a case of missing tooth was indicated to be 78.8%. In case of missing tooth, the number of missing teeth was indicated to be 75.6% for under 5 pieces and 19.1% for over 21 pieces. In the actual condition of managing prosthesis, a case with dental prosthesis treatment was indicated to be 77.6%. A kind of prosthesis was indicated to be the highest in fixed partial dentures with 36.5%. In a method of rinsing dentures, 47.7% of the elderly responded as saying of washing it out with water. The appearance of removing dentures at night was indicated to be the highest in doing so with 63.1%. Satisfaction with prosthesis of being mounted now was indicated to be moderate with 50.4%. As for the appearance of having experience of education on how to manage prosthesis, it was indicated to be high with 50.4% in having none. In a kind of prosthesis depending on averagely monthly income, the ratio of total dentures was high when averagely monthly income is low. On the other hand, a case with high income was indicated to have high ratio in implants. The satisfaction with prosthesis was low when averagely monthly income is low. Also, in the experience of education on how to manage prosthesis, the ratio of responses as saying of having no experience of education on how to manage prosthesis was indicated to be high when averagely monthly income is low. Conclusion: Examining the above results, a developmental plan is considered to be necessary such as developing continuous and systematic oral health promotion program for managing elderly people's managing dental prothesis.

• The Journal of Advanced Prosthodontics
• /
• v.7 no.4
• /
• pp.271-277
• /
• 2015

PURPOSE. This study was to evaluate the marginal fit of two CAD-CAM anatomic contour zirconia crown systems compared to lithium disilicate glass-ceramic crowns. MATERIALS AND METHODS. Shoulder and deep chamfer margin were formed on each acrylic resin tooth model of a maxillary first premolar. Two CAD-CAM systems (Prettau$^{(R)}$Zirconia and ZENOSTAR$^{(R)}$ZR translucent) and lithium disilicate glass ceramic (IPS e.max$^{(R)}$press) crowns were made (n=16). Each crown was bonded to stone dies with resin cement (Rely X Unicem). Marginal gap and absolute marginal discrepancy of crowns were measured using a light microscope equipped with a digital camera (Leica DFC295) magnified by a factor of 100. Two-way analysis of variance (ANOVA) and post-hoc Tukey's HSD test were conducted to analyze the significance of crown marginal fit regarding the finish line configuration and the fabrication system. RESULTS. The mean marginal gap of lithium disilicate glass ceramic crowns (IPS e.max$^{(R)}$press) was significantly lower than that of the CAD-CAM anatomic contour zirconia crown system (Prettau$^{(R)}$Zirconia) (P<.05). Both fabrication systems and finish line configurations significantly influenced the absolute marginal discrepancy (P<.05). CONCLUSION. The lithium disilicate glass ceramic crown (IPS e.max$^{(R)}$press) had significantly smaller marginal gap than the CAD-CAM anatomic contour zirconia crown system (Prettau$^{(R)}$Zirconia). In terms of absolute marginal discrepancy, the CAD-CAM anatomic contour zirconia crown system (ZENOSTAR$^{(R)}$ZR translucent) had under-extended margin, whereas the CAD-CAM anatomic contour zirconia crown system (Prettau$^{(R)}$Zirconia) and lithium disilicate glass ceramic crowns (IPS e.max$^{(R)}$press) had overextended margins.