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The aim of this study was to determine the stability of computer-aided design and manufacturing (CAD/CAM) and prefabricated abutment by measuring removal torque before and after cyclic loading.Three types of fixture and 2 types of abutments were used. Removable torque was measured after cyclic loading for 5000 cycles between 25 and 250 N for each group. The same procedure was performed twice.First, removal torque values (Newton centimeter) were measured for stock versus custom abutments as follows: group 1: 27.17 versus 26.67, group 2: 26.27 versus 26.33, and group 3: 37.33 versus 36.67. Second removal torque values (Newton centimeter) were also measured: group 1: 23 versus 23.5, group 2: 22.5 versus 22.33, and group 3: 32.67 versus 32.5. There was no significant difference between the stock and custom abutments in either the first or second removal torque values and also no significant difference among initial tightening torque, first or second removal torque (P0.05).With precise control of CAD/CAM abutments, good screw joint stability can be achieved.

Gold nanoparticles (GNPs) are quite attractive materials for use as osteogenic agents due to their potential effects on the stimulation of osteoblast differentiation. In this study, an osseo-integrated titanium (Ti) implant surface coated with GNPs was used for promotion of bone regeneration. We prepared a silanized Ti surface by chemical treatment of (3-Mercaptopropyl) trimethoxysilane (MPTMS) and immobilized the GNP layer (Ti-GNP) on their surfaces via Au-S bonding. The GNP layer is uniformly immobilized on the surface and the layer covers the titanium oxide surface well, as confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The Ti-GNP was used to investigate the effectiveness of this system both in vitro and in vivo. The in vitro results showed that the Ti-GNP significantly enhances the osteogenic differentiation with increased mRNA expression of osteogenic differentiation specific genes in human adipose-derived stem cells (ADSCs). Furthermore, the in vivo results showed that Ti-GNP had a significant influence on the osseous interface formation. Through these in vitro and vivo tests, we found that Ti-GNP can be useful as osseo-integration inducing dental implants for formation of an osseous interface and maintenance of nascent bone formation.

Novel porous poly(L-lactide) (PLLA) scaffolds with surface-immobilized nano-hydroxyapatite (N-HAp) were synthesized for effective bone regeneration. N-Hap-bearing surface phosphate functionalities were immobilized chemically on the pore surface of amine-treated PLLA scaffolds. Thermogravimetric analysis (TGA) showed that 24 wt% of N-HAp had been immobilized on the scaffold pore surface. Field-emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) confirmed that N-HAp was exposed markedly on the pore surfaces of scaffolds compared to the conventional scaffold fabricated by a bulk-mixing process of PLLA and N-HAp. The PLLA scaffold with surface-immobilized N-HAp had a higher surface Ca atomic ratio (4.6%) than that on the pore surface of the bulk-mixed PLLA/N-HAp scaffold (Ca = 0.4%). The porous PLLA scaffolds with surface-immobilized N-HAp provided favorable environments for enhanced in vivo bone tissue growth, which was estimated by hematoxylin and eosin (H&E) staining for organic bone tissues and alizarin red S staining for inorganic bone minerals. These results suggest that the N-HAp immobilization approach may produce many useful scaffolds with pore surfaces featuring excellent bone tissue-regenerative properties.

가철성 국소의치의 금속구조물을 제작하는 방법은 왁스 패턴을 제작하여 주조하는 lost wax technique이 주로 사용되어 왔으나, 디지털 기술의 발달로 서베잉과 금속구조물을 CAD (Computer aided design)로 디자인하여 제작할 수 있게 되었다. 여러 증례에서 CAD를 이용한 pattern의 프린팅 방식으로 얻은 레진 패턴이 구...

목적: 이 연구의 목적은 coloring agent의 종류와 적용 횟수가 지르코니아의 색조에 미치는 영향을 알아보는 것이다. 재료 및 방법: 단일구조 지르코니아( $15.7mm{\times}15.7mm{\times}2.0mm$ )를 준비하여 완성된 시편은 11개 실험군 그룹으로 coloring agent의 종류와 적용 횟수에 따라 a1-a5와 w1-w5로 나누었다. 색...

Implant has been an effective treatment option for the patients with oligodontia. However, it still remains unclear when the implant should be placed. Skeletal growth that can appear even after the growth period can lead to infraocclusion of the implant which can cause functional or esthetic complications. In order to minimize these problems, definitive restorations should be placed after the functional and esthetic rehabilitation is achieved through the use of provisional restorations. Definitive restorations made with monolithic zirconia were created by replicating provisional restorations by using the latest CAD/CAM technology. These definitive restorations were delivered to the patient and clinical observation after the treatment showed satisfactory result. (J Korean Acad Prosthodont 2016;54:28-34)

In removable dental prostheses, it is important to minimize impairment of residual tissue caused by wearing dentures. There are two factors that harm residual tissue. The first is functional load bearing of remaining teeth and alveolar ridges and the second is the effect of poor oral hygiene. Double crown retained removable dental prostheses provide rigid support, and it may reduce impairment caused by load bearing of alveolar ridges. Also, dental plaque and oral deposits, which are attached to outer crowns and dentures, can be easily managed extra-orally. In addition, it is beneficial to the health of the marginal gingiva because inner crowns have easy access for oral hygiene. In this case, double crown retained removable dental prostheses were used for the partially edentulous patient with severe residual alveolar bone resorption and poor oral hygiene, and the result was clinically satisfactory in terms of functional, esthetical, and oral hygiene aspects. (J Korean Acad Prosthodont 2016;54:21-7)

The purpose of this study was to investigate the cellular activities of MG63 osteoblast-like cells on modified titanium surfaces.MG63 osteoblast-like cells were cultured on titanium disks (n = 20 in each group) with turned, resorbable blast media (RBM)-treated, or anodized surfaces. The surfaces of commercially available implants of Osstem (Osstem Implant) were reproduced for the titanium disks. The morphology of cells cultured on these disks was examined using scanning electron microscopy. X-ray photoelectron spectroscopy (XPS) was employed for the analysis of surface chemistry. Specimens were also evaluated with an initial cell adhesion assay to compare initial adhesion, with a methyl tetrazol sulfate (MTS) assay to compare the proliferation ability, and with an alkaline phosphatase (ALP) assay to compare the differentiation ability. Statistical significance of the differences was determined using the Kruskal-Wallis test for the cell adhesion assay and analysis of variance for the MTS and ALP assays.Attached cells with more defined lamellopodia and flattened morphology were observed on the anodized and RBM surfaces than on the turned surfaces. The titanium surfaces were all oxidized as titanium oxide and polluted by carbon determinants, as determined by XPS. Anodized titanium surfaces exhibited calcium and phosphorus peaks. Initial cell attachment activity, cell proliferation activity, and ALP activity were higher on the anodized surfaces than on the other surfaces. Cell differentiation on the anodized surfaces at culture day 10 was significantly higher (P.05) than on the other surfaces.Surface treatment by anodization may improve initial attachment of cells, proliferation ability, and differentiation activity, which play important roles in providing better osseointegration of implants. More rapid and stronger osseointegration of implants may make it possible to offer the best anchorage and shorten the healing time required prior to functional loading.

The attachment, growth behaviour and the genetic effect of human gingival fibroblasts (HGF) cultured on titanium and different zirconia surfaces were investigated. HGF cells were cultured on (1) titanium discs with a machined surface, (2) yttrium-stabilized tetragonal zirconia polycrystals (Y-TZP) with a smooth surface and (3) Y-TZP with 100 microm grooves. The cell proliferation activity was evaluated through a MTT assay at 24 h and 48 h, and the cell morphology was examined by SEM. The mRNA expression of integrin-beta1, type I and III collagen, laminin and fibronectin in HGF were evaluated by RT-PCR after 24 h. From the MTT assay, the mean optical density values for the titanium and grooved zirconia surfaces after 48 h of HGF adhesion were greater than the values obtained for the smooth zirconia surfaces. SEM images showed that more cells were attached to the grooves, and the cells appeared to follow the direction of the grooves. The results of RT-PCR suggest that all groups showed comparable fibroblast-specific gene expression. A zirconia ceramic surface with grooves showed biological responses that were comparable to those obtained with HGF on a titanium surface.

Purpose: This study will evaluate the effectiveness of various pretreatments when fiber-reinforced composite (FRC) post is bonded to endodontically treated tooth with resin cement. Materials and methods: Canal shaping of FRC post (DT Light post, Size 3, Bisco Inc., Schaumburg, IL, USA) was performed on endodontically treated premolars at 1.5 cm from CEJ. Samples were divided into 6 groups of surface treatment after conventional washing and drying to the canal. Total of 24 FRC posts were randomly divided into 6 groups of surface treatment as follows: Group C: control - no surface treatment, Group A: airborne-particle abrasion (Cojet sand, 3M ESPE), Group S: silanization (Bis-silane, Bisco Inc.), Group M: universal primer (Monobond-plus primer, Ivoclar Vivadent Inc.), Group AS: silanization after airborne-particle abrasion, Group AM: universal primer treatment after airborne-particle abrasion. Pretreated fiber posts were cemented with resin-based luting material and photo-polymerized and cut to the thickness of 1 mm. Push-out test using a universal testing machine was performed. Bonding failure strength of post dislodgement was measured and the type of bonding failure was classified. Data were analyzed with Kruskal-Wallis test and multiple comparison groups were performed using Tukey HSD value of rank test (α =0.05). Results: Group AS showed significantly highest bonding strength. Group S, group AM, group A, and group M showed lower bonding strength in order. The control group showed the lowest bonding strength. Conclusion: Surface treatment with silane showed to be the most effective of the surface pretreatment methods for cementation of FRC post. Surface treatment with universal primer showed no significant difference compared with no surface treatment group as for bonding strength. (J Korean Acad Prosthodont 2014;52:113-20)

PURPOSE. This study was performed to characterize the effects of zirconia coated with calcium phosphate and hydroxyapatite compared to smooth zirconia after bone marrow-derived osteoblast culture. MATERIALS AND METHODS. Bone marrow-derived osteoblasts were cultured on (1) smooth zirconia, (2) zirconia coated with calcium phosphate (CaP), and (3) zirconia coated with hydroxyapatite (HA). The tetrazolium-based colorimetric assay (MTT test) was used for cell proliferation evaluation. Scanning electron microscopy (SEM) and alkaline phosphatase (ALP) activity was measured to evaluate the cellular morphology and differentiation rate. X-ray photoelectron spectroscopy (XPS) was employed for the analysis of surface chemistry. The genetic expression of the osteoblasts and dissolution behavior of the coatings were observed. Assessment of the significance level of the differences between the groups was done with analysis of variance (ANOVA). RESULTS. From the MTT assay, no significant difference between smooth and surface coated zirconia was found (P>.05). From the SEM image, cells on all three groups of discs were sporadically triangular or spread out in shape with formation of filopodia. From the ALP activity assay, the optical density of osteoblasts on smooth zirconia discs was higher than that on surface treated zirconia discs (P>.05). Most of the genes related to cell adhesion showed similar expression level between smooth and surface treated zirconia. The dissolution rate was higher with CaP than HA coating. CONCLUSION. The attachment and growth behavior of bone-marrow-derived osteoblasts cultured on smooth surface coated zirconia showed comparable results. However, the HA coating showed more time-dependent stability compared to the CaP coating. [J Adv Prosthodont 2014;6:96-102]

Purpose: The importance of occlusal contacts of the natural dentition for durability of teeth, mandibular stabilization, and restorative dentistry is well known. The purpose of this study is to analyze the occlusal contact and guidance pattern of Koreans by evaluating the static occlusion on maximal intercuspal position and measuring dynamic occlusion during straight protrusion. Materials and methods: The occlusal contacts at maximal interincisal position and the occlusal guidance pattern during straight protrusion of 29 subjects were recorded with shimstock foil (Whaledent, Langenau, Germany), T-Scan III (Tekscan Inc., Boston, MA, USA), polyvinylsiloxane registration material (Genie Bite, Sultan Healthcare, Hackensack, NJ, USA) and compared. Occlusal registration procedures were repeated 3 times. The position was fixed to an upright position and the head position was fixed with the Frankfurt horizontal plane paralleling the horizontal plane. Fisher's Exact Test (R-General Public License, ver. 2.14.1) and Pearson's Test were used to assess the significance level of the differences between the experimental groups (α=.05). Results: When using shimstock foil, T-Scan III system, and polyvinylsiloxane registration material, most of the patients showed contact on anterior, premolar, and molar teeth during maximal intercuspal position. Approximately 51% of maximal intercuspal position showed anterior contact using shimstock foil. When examining the protrusive movement using shimstock foil and T-Scan III system, guidance pattern with the central incisor was the most common. Conclusion: During maximal intercuspal position, there were cases in which not all of the teeth showed occlusal contact. During mandibular protrusive movements, one or more maxillary central incisors frequently joined in straight protrusion and the posterior teeth were disoccluded. Therefore, the anterior teeth protect the posterior teeth, and vice versa. Thus, mutually protected occlusion should be applied when reconstructing occlusion. (J Korean Acad Prosthodont 2013;51:199207)

성공적인 보철 치료를 위해서는 정확한 진단이 근거가 되어야 한다. 즉, 처음 환자가 내원하였을 때, 환자의 주소를 바탕으로 한 문제점을 찾고, 그 원인을 분석하여 이에 입각한 치료 계획을 세웠을 때, 만족스러운 결과를 기대할 수 있을 것이다. 본 증례의 환자는 77세 여성으로, 저작 시 상 하악 좌측 소구치 부위의 통증 및 기존 보철물의 비심미성을 주소로 내원하였다. 임상적, 방사선학적 검사 및 모형 분석을 통해 문제점을 파악하였고, 여러 문헌에 근거하여 지대치 평가, 보철물의 여러 가지 디자인에 따른 예후 및 최종 보철물의 장착 시 유지 관리의 용이성 등을 고려하여 치료 계획을 수립하기로 하였다. 심미적 문제, 보철을 위한 악간 공간의 부족을 해소하고자 최소한의 수직 고경 증가를 동반한 전악 수복을 시행하기로 결정하였다. 기능, 심미성 및 교합의 안정을 통한 환자의 적응도를 평가하여 치료 계획의 적절성 여부를 판단할 수 있었다. 따라서, 최종적인 고정성 국소 의치를 제작하고 장착하여 만족스러운 결과를 얻었기에 이를 보고하는 바이다. 【Data collection including checking the problem list and analyzing the etiology cannot be overemphasized in full mouth rehabilitation cases. It is well reported that favorable prognosis of prosthodontic treatment depends on accurate diagnosis. Seventy seven year old female patient presented with chief complaints of chewing pain on maxillary and mandibular left premolars and unesthetic existing prosthesis. Clinical evaluation, radiographic examination and cast analysis were performed to gather comprehensive data and problem lists. Treatment planning was based on collected data and related articles. Abutment evaluation, prognosis depending on various types of prosthesis, and maintenance were considered as well. Occlusal vertical dimension was increased to solve esthetic dissatisfaction and insufficient interocclusal space. Patient adaptation was verified with provisional restorations followed by diagnostic wax up. Function, esthetics and occlusal stability were verified during 8 week follow-up period. Prosthodontic reconstruction based on systemic analysis, diagnosis, and treatment plan led to satisfactory result after delivery of definitive prosthesis.】

PURPOSE. This study was performed to define attachment and growth behavior of osteoblast-like cells and evaluate the gene expression on zirconia compared to titanium. MATERIALS AND METHODS. MC3T3-E1 cells were cultured on (1) titanium and (2) zirconia discs. The tetrazolium-based colorimetric assay (MTT test) was used for examining the attachment of cells. Cellular morphology was examined by scanning electron microscopy (SEM) and alkaline phosphatase (ALP) activity was measured to evaluate the cell differentiation rate. MannWhitney test was used to assess the significance level of the differences between the experimental groups. cDNA microarray was used for comparing the 20215 gene expressions on titanium and zirconia. RESULTS. From the MTT assay, there was no significant difference between titanium and zirconia (P>.05). From the SEM image, after 4 hours of culture, cells on both discs were triangular or elongated in shape with formation of filopodia. After 24 hours of culture, cells on both discs were more flattened and well spread compared to 4 hours of culture. From the ALP activity assay, the optical density of E1 cells on titanium was slightly higher than that of E1 cells on zirconia but there was no significant difference (P>.05). Most of the genes related to cell adhesion showed similar expression level between titanium and zirconia. CONCLUSION. Zirconia showed comparable biological responses of osteoblast-like cells to titanium for a short time during cell culture period. Most of the genes related to cell adhesion and signal showed similar expression level between titanium and zirconia.

With the introduction of dental implants, restoration of missing teeth with conventional fixed or removable partial dentures is being replaced with implants. Especially, with young patients, not only longevity but also esthetic factors need to be considered. Implant restorations provide long-term success functionally but, esthetic complications such as, marginal exposure due to gingival recession, loss of the papilla and dark color of metal abutments may occur. Recently, zirconia restorations with CAD/CAM technology provide functional, biocompatible and esthetic restorations possible. All-ceramic restorations using the pressed ceramic technique show better fracture toughness values than those of the conventional porcelain veneering technique. Pressed ceramic technique creates the veneer design in wax and the lost wax technique is used to create the restoration. The final contour of the restoration may be controlled during wax-up. A 22-year old female patient was restored with dental implants and zirconia restorations using the pressed ceramic technique presenting short-term but optimistic prognosis. (J Korean Acad Prosthodont 2013;51:47-51)

The loss of posterior support may cause attrition of anterior teeth, and loss of occlusal vertical dimension (OVD). The collapse of the posterior support will eventually cause the pathologic change of the TMJ and masticatory muscles, unesthetic facial appearance and decreased masticatory function. Patients with destroyed dentition need extensive prosthetic treatments. Proper diagnosis and treatment planning are necessary for the stability of the neuromuscular system and the TMJ, and esthetic and functional definitive restorations. In this case, 63 year-old male presented with decreased masticatory force and esthetic problems due to pathologic destruction of teeth structure on entire dentition. Based on assessment of OVD including intraoral findings, radiographic examination and diagnostic cast, full-mouth rehabilitation with increase of OVD was planned using fixed partial denture and removable partial denture. Diagnostic wax-up was done after 4 mm increase of OVD determined by assessment of OVD. The OVD was maintained with the overlay type removable interim prostheses for 12 weeks to ascertain his comfort and adaptation to the new OVD. After the adaptation period, second interim prostheses with tooth preparation maintaining the established OVD was delivered. After 4 weeks, final prostheses were fabricated and delivered. After 7 month follow-up period, occlusal stability is maintained. Through this procedure, satisfactory outcomes were achieved both in functional and esthetic aspects. (J Korean Acad Prosthodont 2013;51:39-46)