• The Journal of Korean Academy of Prosthodontics
• /
• v.51 no.1
• /
• pp.20-26
• /
• 2013

Purpose: The purpose of this study was to evaluate the bond strengths between the latest CAD/CAM ceramic inlay and various resin cements which are used primarily for esthetic restoration. Materials and methods: Cylindrical ceramic blocks(Height: 5 mm, diameter: 3 mm) were fabricated by using Cerec3 and bonded on the dentin of the ninety extracted caries-free molars using three different kinds of resin cement(Unicem$^{(R)}$, Biscem$^{(R)}$, and Variolink II$^{(R)}$) according to the manufacturer's instructions. Ninety specimens were divided into 3 groups according to three different kinds of resin cement. Half of each group were conducted thermocycling under the conditions of the $5-55^{\circ}C$, 5,000 cycle but the other half of them weren't. All specimens were kept in normal saline $37^{\circ}C$, for 24 hours before measuring the bond strength. The shear bond strength was measured by Universal testing machine with a cross head speed of 0.5 mm/min. The results were analyzed statistically by t-test and one-way ANOVA. Results: Unicem$^{(R)}$ group showed the highest shear bond strength despite a slight decline by thermocycling. The shear bond strength of Unicem$^{(R)}$ group and ValiolinkII$^{(R)}$ group were significantly influenced by thermocycling, whereas Biscem$^{(R)}$ group was not influenced (P<.05). There were no significant differences in the bond strength between the three groups without thermocycling, but there was significant differences between Unicem$^{(R)}$ group and Valiolink II$^{(R)}$ group with thermocycling(P<.05). Conclusion: It has been shown to be clinically effective when the self-adhesive resin cements Unicem$^{(R)}$ and Biscem$^{(R)}$ were used instead of the etch-and-rinse resin cement Valiolink II$^{(R)}$ during the bonding of CAD/CAM ceramic inlay restorations with teeth.

• The Journal of Korean Academy of Prosthodontics
• /
• v.55 no.3
• /
• pp.279-285
• /
• 2017

Defects due to mandibulectomy often cause hard and soft tissue loss and result in esthetic problems and functional disorders such as mastication, swallowing, and pronunciation. After the mandibular reconstruction, several complications including loss of alveolar bone can cause limitations in maintenance or supporting of removable prosthesis. For these patients, implant-supported fixed restorations have been an appropriate prosthetic restorative method. In this case report, we report the patient who underwent mandibulectomy and mandibular reconstruction owing to oral cancer, and then restored the current dentition functionally and aesthetically by applying zirconia frameworks and monolithic zirconia crowns by computer-aided design and computer-aided manufacturing.

• Restorative Dentistry and Endodontics
• /
• v.41 no.3
• /
• pp.167-175
• /
• 2016

Objectives: Endodontically treated teeth with insufficient tooth structure are often restored with esthetic restorations. This study evaluated the cytotoxicity and biological effects of yttria partially stabilized zirconia (Y-TZP) blocks in combination with several dental cements. Materials and Methods: Pairs of zirconia cylinders with medium alone or cemented with three types of dental cement including RelyX U200 (3M ESPE), FujiCEM 2 (GC), and Panavia F 2.0 (Kuraray) were incubated in medium for 14 days. The cytotoxicity of each supernatant was determined using 3-(4,5-dimethylthiazole- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays on L929 fibroblasts and MC3T3-E1 osteoblasts. The levels of interleukin-6 (IL-6) mRNA were evaluated by reverse transcription polymerase chain reaction (RT-PCR), and IL-6 protein was evaluated by enzyme-linked immunosorbent assays (ELISA). The data were analyzed using one-way ANOVA and Tukey post-hoc tests. A p < 0.05 was considered statistically significant. Results: The MTT assays showed that MC3T3-E1 osteoblasts were more susceptible to dental cements than L929 fibroblasts. The resin based dental cements increased IL-6 expression in L929 cells, but reduced IL-6 expression in MC3T3-E1 cells. Conclusions: Zirconia alone or blocks cemented with dental cement showed acceptable biocompatibilities. The results showed resin-modified glass-ionomer based cement less produced inflammatory cytokines than other self-adhesive resin-based cements. Furthermore, osteoblasts were more susceptible than fibroblasts to the biological effects of dental cement.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.26 no.1
• /
• pp.103-108
• /
• 1999

Restoration of severly carious, malformed or traumatically fractured primary incisors is one of the most difficult challenges in restorative dental care for preschoolers. In restoring primary anterior teeth, four types of complete coverage crowns have been attempted over the years. Stainless steel crowns, open-faced stainless steel crowns, acid-etched crowns(strip crowns), and preformed polycarbonate crowns have been the choices. While these restorations have been acceptable for many patients, they all have very distinct limitations. The ideal full coronal restoration for a primary incisor requires durability, retention, and esthetics. This paper reported veneered stainless steel crown restoration of primary anterior teeth by silicoater technique. Veneered stainless steel crown restoration by silicoater technique is considered to be a durable, retentive, and esthetic restoration.

• The Journal of Korean Academy of Prosthodontics
• /
• v.56 no.1
• /
• pp.70-76
• /
• 2018

Excessive tooth wear can lead to decrease in occlusal vertical dimension and can cause pathological changes in the oral environment and masticatory system. When recovering occlusal vertical dimension and occlusion, accurate diagnosis and analysis are essential. This clinical case describes a 75-year-old woman with severely worn dentition due to loss of the posterior support. Full mouth rehabilitation with occlusal vertical dimension increment was planned. Clinical and radiographic examinations, occlusal vertical dimension evaluation, and diagnostic wax-up were performed and patient adaptability was evaluated using provisional restorations. As for definitive restoration, considering economic condition of the patient, removable partial denture was fabricated and solitary implants were placed in the mandibular left and right posterior region to increase support and retention of the removable partial denture. During one year of follow-up, functional and esthetic outcomes were observed satisfactory.

• The Journal of Korean Academy of Prosthodontics
• /
• v.46 no.3
• /
• pp.227-237
• /
• 2008

STATEMENT OF PROBLEM: Zirconium oxide can be a substitute to titanium as implant materials to solve the esthetic problems of dark color in the gingival portion of implant restorations. PURPOSE: This study was performed to define attachment and growth behavior of osteoblast- like cells cultured on grooved surfaces of zirconium oxide and evaluate the genetic effect of zirconium oxide surfaces using the reverse transcriptase-polymerase chain reaction (RT-PCR). MATERIAL AND METHODS: MC3T3-E1 cells were cultured on (1) commercially pure titanium discs with smooth surface (T group), (2) yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) with machined surface (ZS group), and (3) Y-TZP with $100{\mu}m$ grooves (ZG group). Cell proliferation activity was evaluated through MTT assay and cell morphology was examined by SEM. The mRNA expression of Runx2, alkaline phosphatase, osteocalcin, TGF-${\beta}1$, IGF-1, G3PDH in E1 cells were evaluated by RT-PCR. RESULTS: From the MTT assay, after 48 hours of adhesion of MC3T3-E1 cells, the mean optical density value of T group and ZG group significantly increased compared to the ZS group. SEM images of osteoblast-like cells showed that significantly more cells were observed to attach to the grooves and appeared to follow the direction of the grooves. After 24 hours of cell adhesion, more spreading and flattening of cells with active filopodia formation occurred. Results of RT-PCR suggest that T group, ZS group, and ZG group showed comparable osteoblast-specific gene expression after 24 hours of cell incubation. CONCLUSION: Surface topography and material of implants can play an important role in expression of osteoblast phenotype markers. Zirconia ceramic showed comparable biological responses of osteoblast-like cells with titanium during a short-time cell culture period. Also, grooves influence cell spreading and guide the cells to be aligned within surface grooves.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.25 no.4
• /
• pp.704-709
• /
• 1998

Amelogenesis imperfecta represents a group of hereditary conditions that manifest enamel defects without evidence of generalized or systemic disorders. These enamel disorders are apparently heterogeneous in the basic chemical structure, resulting in a diverse presentation of clinical characteristics. The reported prevalence of amelogenesis imperfecta varies from 1 in 14,000-16,000 to 1.4 in 1,000 depending on specific population studied with the autosomal dominant hypocalcification type of amelogenesis imperfecta believed to be the least prevalent. The most widely accepted current classification system for delineating the amelogenesis imperfecta types considers the mode of inheritance and clinical manifestations. Three major groups are recognized; hypoplastic, hypocalcified, and hypomaturation types. Delineating specific types of amelogenesis imperfecta can be confusing due to the phenotypical similarity of many forms and that the most recent classification lists 14 different types. A 12 year-old female patient came to our pediatric dentistry clinic complaining of the ugly shape and color of her teeth, especially the upper front area. Although the goal of the treatment was mainly focused on the improvement of patient's esthetics, longevity of the restorations was also considered in selecting the appropriate restorative system, resin jacket crown, which can satisfy the both aspects.

• The Journal of Korean Academy of Prosthodontics
• /
• v.36 no.6
• /
• pp.888-899
• /
• 1998

In-Ceram system is one of contemporary esthetic all ceramic restorations and has relatively high flexural strength. The purpose of this study was to evaluate the marginal fidelity according to type of resin cement and measuring position, and to evaluate fracture strength according to type of resin cement. In this study, twenty seven In-Ceram crowns were fabricated on the metal master die of prepared maxillary right central incisor and devided into three groups. All specimens were cemented with Panavia 21 (group PV), Super-bond (group SB) and Lute-it (group LI) on the metal master die. After cementation, specimens were measured marginal gap between the margin of the In-Ceram crown and the finishing line of metal master die by using a stereomicroscope (SZ-ST, Olympus, Japan). Marginal gaps were recorded at the labial, lingual, mesial and distal measuring points on the metal master die. For the mesurement of fracture strength, lingual surfaces of cemented specimens were loaded at a distance of 1mm from incisal edge by using the Autograph S-2000 (Shimadzu, Japan). The results of marginal fidelity and fracture strength were statistically analyzed with the SPSS version 8.0 programs. The results of this study were as follows: 1. In comparison of marginal fidelity according to the measuring points, there was no significant difference. 2. The marginal fidelity according to the type of resin cement was decreased in order of group $LI\;(63.75{\mu}m),\;SB\;(77.78{\mu}m),\;PV\;(86.53{\mu}m)$, and there was significant difference between group LI and PV (p<0.05). 3. The fracture strength according to the type of resin cement was showed descending order of group $LI\;(60.00kg/cm^2),\;SB\;(56.80kg/cm^2),\;PV\;(56.11kg/m^2)$, but there was no significant difference.

• The Journal of Korean Academy of Prosthodontics
• /
• v.41 no.1
• /
• pp.71-80
• /
• 2003

Development of new ceramic and esthetic need of patient increased the use of ceramic restorations. The purpose of this study was to confirm the possibility of recycling for IPS Empress2 which has a lot of advantages in esthetics. 1st, 2nd and 3rd pressed disc-shaped($10{\times}1.5mm$) IPS Empress 2 specimens were made with IPS Empress ingot(shade 200, Ivoclar, Liechtenstein) and pressing furnace(IPS Empress EP 500, Ivoclar, Liechtenstein). Flexure strength was measured with universal testing machine(Zwick 145641, Zwick, Germany), and color change and staining resistance of specimens were evaluated with colorimeter (Model TC-6FX, Tokyo Denshoku Co., Japan). The followings were drawn from this study : 1. Flexure strength of the 1st, the 2nd, and the 3rd pressed specimens showed 236.78 MPa. 247.16MPa, and 220.72MPa, respectively. Flexure strength of the 2nd pressed specimens was higher than others, but there's no statistical difference between them. 2. The color difference between the 1st and the 2nd pressed specimens was 3.25, and that between the 1st and the 3rd pressed specimens was 3.63(P<0.05). 3. The color change after staining of the 1st, the 2nd. and the 3rd pressed specimens were 1.43, 2.64, and 1.45, respectively. In this study, reused IPS Empress 2 specimens showed insignificant change of flexure strength and stain resistance, but they showed some color change according to reuse. From this results, the limited possibility of reuse for IPS Empress 2 could be considered.

• Journal of Technologic Dentistry
• /
• v.30 no.2
• /
• pp.31-37
• /
• 2008

A variety of the porcelain fused to gold(PFG) have been developed to which porcelain can be fused. PFG alloys developed for this purposed have a high melting point and do not discolor when combined with porcelain. The design of the compositions of PFG is very important to esthetic restorative materials applying to porcelain. The purpose of this study is on the change of physical and mechanical characteristics in PFG 18K alloy by the small additional elements. Principal results are as follows. The high Au alloy containing 18Karat gold contents is respectively Au(75%), Pd(10%), Pt(4%), Ag(4%), In(2%), Sn(2%), Cu(2%), Ti(1%). These alloys are composed mainly of gold, platinum, silver and palladium with a few percent of the additional elements. By the addition of small amounts of elements such as In, Sn, Ti, the fine grain castings are produced in gold alloy and the small addition of platinum is very effective in increasing of hardness and strength. These gold alloys are representative of the changes to be expected as a result of heat treatment. These changes in strength and hardness values are sufficient to demonstrate a significant difference in performance between a as-casted and a heat-treated. These alloys have mechanical properties characteristics of Type and Type gold alloys. These alloys are useful to porcelain-metal restorations and dental laboratory. Also the porcelain fused to metal(PFM) alloys containing gold are commonly use for dental purposes in dental laboratory.