Influence of preparation depths on the fracture load of customized zirconia abutments with titanium insert

Kwi-Dug Yun,Min-Kyung Ji,Hyun-Pil Lim,Hyun-Seung Kim,Sang-Won Park,Hong-So Yang,Han-Sung Joo 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.3

PURPOSE This study evaluated the fracture load of customized zirconia abutments with titanium insert according to preparation depths, with or without 5-year artificial aging. MATERIALS AND METHODS Thirty-six identical lithium disilicate crowns (IPS e.max press) were fabricated to replace a maxillary right central incisor and cemented to the customized zirconia abutment with titanium insert on a 4.5×10 mm titanium fixture. Abutments were fabricated with 3 preparation depths (0.5 mm, 0.7 mm, and 0.9 mm). Half of the samples were then processed using thermocycling (temperature: 5-55℃, dwelling time: 120s) and chewing simulation (1,200,000 cycles, 49 N load). All specimens were classified into 6 groups depending on the preparation depth and artificial aging (non-artificial aging groups: N5, N7, N9; artificial aging groups: A5, A7, A9). Static load was applied at 135 degrees to the implant axis in a universal testing machine. Statistical analyses of the results were performed using 1-way ANOVA, 2-way ANOVA, independent t-test and multiple linear regression. RESULTS The fracture loads were 539.28 ± 63.11 N (N5), 406.56 ± 28.94 N (N7), 366.66 ± 30.19 N (N9), 392.61 ± 50.57 N (A5), 317.94 ± 30.05 N (A7), and 292.74 ± 37.15 N (A9). The fracture load of group N5 was significantly higher than those of group N7 and N9 (P<.017). Consequently, the fracture load of group A5 was also significantly higher than those of group A7 and A9 (P<.05). After artificial aging, the fracture load was significantly decreased in all groups with various preparation depths (P<.05). CONCLUSION The fracture load of a single anterior implant restored with lithium disilicate crown on zirconia abutment with titanium insert differed depending on the preparation depths. After 5-year artificial aging, the fracture loads of all preparation groups decreased significantly.

Evaluation of antibacterial activity and osteoblast-like cell viability of TiN, ZrN and (Ti1-xZrx)N coating on titanium

Kwi-Dug Yun,Hyun-Seung Kim,Hyun-Pil Lim,In-Chol Kang,Kwangmin Lee,Sang-Won Park,Min-Kyung Ji 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.2

PURPOSE The aim of this study was to evaluate antibacterial activity and osteoblast-like cell viability according to the ratio of titanium nitride and zirconium nitride coating on commercially pure titanium using an arc ion plating system. MATERIALS AND METHODS Polished titanium surfaces were used as controls. Surface topography was observed by scanning electron microscopy, and surface roughness was measured using a two-dimensional contact stylus profilometer. Antibacterial activity was evaluated against Streptococcus mutans and Porphyromonas gingivalis with the colony-forming unit assay. Cell compatibility, mRNA expression, and morphology related to human osteoblast-like cells (MG-63) on the coated specimens were determined by the XTT assay and reverse transcriptase-polymerase chain reaction. RESULTS The number of S. mutans colonies on the TiN, ZrN and (Ti1-xZrx)N coated surface decreased significantly compared to those on the non-coated titanium surface (P<0.05). CONCLUSION The number of P. gingivalis colonies on all surfaces showed no significant differences. TiN, ZrN and (Ti1-xZrx)N coated titanium showed antibacterial activity against S. mutans related to initial biofilm formation but not P. gingivalis associated with advanced periimplantitis, and did not influence osteoblast-like cell viability.

WETTABILITY AND DRUG DELIVERY OF FUNCTIONALLY GRADED NANO-MICRO POROUS TITANIUM SURFACE

Yun, Kwi-Dug,Vang, Mong-Sook,Yang, Hong-So,Park, Sang-Won,Park, Ha-Ok,Lim, Hyun-Pil The Korean Academy of Prosthodonitics 2008 대한치과보철학회지 Vol.46 No.3

STATEMENT OF PROBLEM: It is known that an anodic oxidation technique, one of the methods for the implant surface treatment, remarkably increased surface area, enhanced wettability and accelerated the initial bone healing. Purpose: This study was performed to evaluate the wettability of anodized titanium surface which has a nanotubular structure, to assess osseointegration after the placement of implant with nano-size tubes on tibia of rats and to analyze quantitatively transferable rhBMP-2 on each surface. MATERIAL AND METHOD: Four different kinds of surface-treated titanium discs (polished (machined surface) group, micro (blasting surface) group, nano (anodizedmachined surface) group, and nano-micro (anodized-blasting surface) group) were fabricated (n=10). Three different media were chosen to measure the surface contact angles; distilled water, plasma and rhBMP-2 solution. After a single drop (0.025 $m{\ell}$) of solution, the picture was taken with the image camera, and contact angle was measured by using image analysis system. For the test of osseointegration, 2 kinds of anodized surface (anodized-machined surface, anodized-blasting surface) implants having 2.0 mm in diameter and 5.0 mm in length inserted into the tibia of Wistar rats. After 3 weeks, tibia were harvested and the specimens were stained with hematoxylin and eosin for histological analysis. To test the possibility of drug delivery, after soaking sample groups in the concentration of 250 ng/$m{\ell}$l of rhBMP-2 for 48 hours, the excess solution of rhBMP-2 were removed. After that, they were lyophilized for 24 hours, and then the rhBMP-2 on the surface of titanium was resolved for 72 hours in PBS. All the extracted solution was analyzed by ELISA. One-way analysis of variance (ANOVA) was performed on the data. RESULTS: The wettability is improved by anodic oxidation. The best wettability was shown on the nano-micro group, and it was followed by nano group, micro group, and polished group. In the histological findings, all implants showed good healing and the new bone formation were observed along the implant surface. After 3 days, nano-micro group delivered the most amount of rhBMP-2, followed by nano group, micro group, and polished group. CONCLUSION: It indicated that anodic oxidation on blasting surface produce functionally graded nano-micro porous structure and enhance hydrophilicity of the surface and osseointegration. The findings suggest that the nano-micro porous structure could be a useful carrier of osteogenic molecules like rhBMP-2.

Effect of nanotubular-micro-roughened titanium surface on cell response <i>in vitro</i> and osseointegration <i>in vivo</i>

Yun, Kwi-Dug,Yang, Yunzhi,Lim, Hyun-Pil,Oh, Gye-Jeong,Koh, Jeong-Tae,Bae, In-Ho,Kim, Jaehyung,Lee, Kwang-Min,Park, Sang-Won Elsevier 2010 Materials science & engineering. C, Materials for Vol.30 No.1

<P><B>Abstract</B></P><P>This study was to evaluate wettability, cell response, and osseointegration of nanotubular titanium (Ti) surface by anodic oxidation. Commercially pure Ti discs were treated by polishing, sandblasting, and anodizing. These surfaces were characterized by scanning electron microscopy and contact angle measurement. MC3T3-E1 osteoblast cell was used to evaluate cell response <I>in vitro</I>. The cell morphology, cell viability, and alkaline phosphatase (ALP) specific activity were assessed. The Ti implants of 2.0mm diameter and 5.0mm long treated by anodizing and sandblasting/anodizing were inserted into the tibia of rats. After 3weeks, the histology of the Ti–bone interface was examined. SEM observations showed that the anodizing and sandblasting/anodizing created the nanotubular surface and graded nanotubular-micro-roughened surfaces, respectively. The anodizing and sandblasting/anodizing significantly improved the hydrophilicity of Ti. The significant greatest cell spreading and ALP specific activity were observed on the graded nanotubular-micro-roughened surfaces treated by sandblasting/anodizing. The <I>in vivo</I> study shows that newly formed bone was intimately in contact with the nanotubular surfaces without adverse immune response. This study has suggested that the graded nanotubular-micro-roughened surface of Ti treated with sandblasting/anodizing is very promising in implantology due to improved hydrophilicity, favorable cell response, and excellent osseointegration.</P>

Corrosion Behavior of As-Cast and Hot Rolled Pure Magnesium in Simulated Physiological Media

Ahmad Zakiyuddin,Kwi-Dug Yun,Kwangmin Lee 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.6

Magnesium is a biodegradable metal that has significant potential advantages as an implant material. However,the fast degradation rate in the biological environment has limits the application. In this article, corrosionbehaviors of as-cast and hot rolled pure magnesium in 0.9% NaCl, Ringer’s, and Tas-SBF solutionswere studied. Potentiodynamic polarization and hydrogen evolution test were employed to assess the corrosionbehaviors. The magnesium specimens were characterized using field emission scanning electron microscopyequipped with energy-dispersive X-ray analysis and X-ray diffraction. The as-cast specimens in 0.9%NaCl and Ringer’s solutions had lower corrosion potentials and corrosion rates than the hot rolled specimens. However, the as-cast specimen in the Tas-SBF solution had a higher corrosion potential and a lowercorrosion rate than the hot rolled specimen. Only the specimens in the Tas-SBF solution showed passivationbehavior due to the presence of ions. The hot rolled specimen could form apatite more easily on its surfacethan the as-cast specimen in Tas-SBF.

Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming

Gye-Jeong Oh,Kwi-Dug Yun,Kwang-Min Lee,Hyun-Pil Lim,Sang-Won Park 대한치과보철학회 2010 The Journal of Advanced Prosthodontics Vol.2 No.3

PURPOSE. The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIALS AND METHODS. Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest(R). ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. RESULTS. Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. CONCLUSION. Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block.

A morphometric analysis of maxillary central incisor on the basis of facial appearance in Korea

Ji-Eun Ku,Hong-So Yang,Kwi-Dug Yun 대한치과보철학회 2012 The Journal of Advanced Prosthodontics Vol.4 No.1

PURPOSE: We aimed to identify a more esthetic width-to-length ratio by analyzing maxillary central incisor of Korean adult population. Information regarding tooth ratio in the Korean population may be useful to clinicians when restoring anterior teeth. MATERIALS AND METHODS: A total of 40 men and 40 women were included in this study. The NON-MEDIA group included 40 non-celebrities, who were healthy and 25 to 39 years old, with normal dentofacial appearance. The MEDIA group consisted of 40 celebrities selected only on the basis of their soft-tissue facial appearance. The facial photographs of 40 celebrities were collected from the Internet websites. The width and length of the maxillary central incisor were measured using Adobe Photoshop® 7.0, a software for analysis, measurement and edition of photographs. Data were analyzed statistically using the Independent t-test at 5% statistical significance level. RESULTS: The mean ratio for the MEDIA group was 0.77, whereas that of the NON-MEDIA group was 0.88. The difference between the two groups was statistically significant. No significant gender differences were found in the width-to-length ratio in MEDIA group. In NON-MEDIA group, however, there were significant differences between female and male. CONCLUSION: After analyzing maxillary anterior teeth of Korean adults, our results were in accordance with the general Western standards of esthetics. A dentist restoring the natural look and beauty of teeth will have to consider those standards.

Effect of fluoride release on the polished surface after polishing with a bur containing fluoride

( In-sun Jeong ),( Hong-won Kang ),( Kwi-dug Yun ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2020 Oral Biology Research (Oral Biol Res) Vol.44 No.3

This study aimed to evaluate the fluoride release amount on the polished surface after polishing with a bur containing fluoride. The point-shape dental burs and disk-shape specimens containing 1,450 ppm fluoride were fabricated. The fluoride released on the dental bur was measured after 1, 3, 7, and 9 days from the disk-shaped specimens (n=5). The point shape dental bur polished the conventional composite resin surface 5 times during 5 seconds at 3,000 rpm. The polished composite resin surface was measured the fluoride release amount after 1, 3, 7, and 9 days. IBM SPSS Statistics ver. 25.0 (IBM Corp., Armonk, NY, USA) was used for statistical analysis. The dental bur containing fluoride were released at 71.68±3.82 ppm fluoride after 1 day, 75.52±2.19 ppm after 3 days, 77.5±1.86 ppm after 7 days, and 77.58±1.30 ppm after 9 days. The polished surface with the point shape dental bur containing fluoride was released at 7.98±0.62 ppm fluoride after 1 day, 8.48±0.65 ppm after 3 day, 8.80±0.41 ppm after 7 days, and 8.75±0.35 ppm after 9 days. The application of dental bur containing 1,450 ppm fluoride showed the possibility of preventing dental caries and exerting an antimicrobial effect.

Effect of Metal Chloride Solutions on Coloration and Biaxial Flexural Strength of Yttria-Stabilized Zirconia

오계정,Kwangmin Lee,이도재,Hyun-Pil Lim,Kwi-Dug Yun,Jae-Sam Ban,Kyung-Ku Lee,존피셔,박상원 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.5

The effect of three kinds of transition metal dopants on the color and biaxial flexural strength of zirconia ceramics for dental applications was evaluated. Presintered zirconia discs were colored through immersion in aqueous chromium, molybdenum and vanadium chloride solutions and then sintered at 1450 °C. The color of the doped specimens was measured using a digital spectrophotometer. For biaxial flexural strength measurements, specimens infiltrated with 0.3 wt% of each aqueous chloride solution were used. Uncolored discs were used as a control. Zirconia specimens infiltrated with chromium, molybdenum and vanadium chloride solutions were dark brown, light yellow and dark yellow, respectively. CIE L*,a*, and b* values of all the chromium-doped specimens and the specimens infiltrated with 0.1 wt% molybdenum chloride solution were in the range of values for natural teeth. The biaxial flexural strengths of the three kinds of metal chloride groups were similar to the uncolored group. These results suggest that chromium and molybdenum dopants can be used as colorants to fabricate tooth colored zirconia ceramic restorations.

Effect of Viscosities on the Surface Morphology and Crystallographic Properties of Hydroxyapatite Coated Titanium Dioxide Nanotubes.

Kang, Kyungho,Lim, Hyunpil,Yun, Kwi-Dug,Park, Sangwon,Jeong, Cheolwoong,Lee, Kwangmin American Scientific Publishers 2015 Journal of nanoscience and nanotechnology Vol.15 No.7

<P>Hydroxyapatite (HA) coating on biomaterials is crucial for bone growth. TiO2 naotubes having a larger specific area can also improve an osseointegration. In this study, anodized TiO2 nanotubes were coated with HA using sol-gel method with different viscosities of solution. Morphological characterization and crystal structures of the coated specimens were measured via field emission scanning electron microscope, transmission electron microscope, X-ray diffractometer, and fourier transforrm infrared spectroscopy. Nanosized hydroxyapatite particles were observed with sol viscosities at 1.95 cP and 0.94 cP inside the TiO2 nanotubes. When coated with the lower viscosity of solution, the TiO2 nanotubes were clearly observed. The crystallinity of HA increased as the temperature of heat treatment increased. The HA phase on the specimen was identified by PO4(3-) and OH-ion peaks in FT-IR spectra.</P>