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1.  Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming 
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.
Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest® 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.
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.
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.
PMCID: PMC2994699  PMID: 21165274
Zirconia block; Mechanical properties; Sintering behavior; Linear sintering shrinkage
2.  Shear bond strength of composite resin to titanium according to various surface treatments 
When veneering composite resin-metal restoration is prepared, the fact that bond strength between Ti and composite resin is relatively weak should be considered.
The purpose of this study is to evaluate the shear bond strength between the veneering composite resin and commercial pure (CP) Ti / Ti-6Al-4V alloy according to the method of surface treatment.
The disks were cast by two types of metal. Their surfaces were treated by sandblasting, metal conditioner, TiN coating and silicoating respectively. After surface treatment, the disks were veneered by composite resin (Tescera™, Bisco, USA) which is 5 mm in diameter and 3 mm in thickness. The specimens were stored in water at 25℃ for 24 hours, and then evaluated for their shear bond strength by universal testing machine (STM-5®, United Calibration, USA). These values were statistically analyzed.
1. All methods of surface treatment were used in this study satisfied the requirements of ISO 10477 which is the standard of polymer-based crown and bridge materials. 2. The metal conditioner treated group showed the highest value in shear bond strength of CP Ti, silicoated group, TiN coated group, sandblasted group, in following order. 3. The silicoated group showed the highest value in shear bond strength of Ti-6Al-4V alloy, metal conditioner treated group, sandblasted group, TiN coated group, in following order.
Within the limitations of this study, all methods of surface treatment used in this study are clinically available.
PMCID: PMC2994681  PMID: 21165258
Shear bond strength; Surface treatment
3.  Histologic evaluation and removal torque analysis of nano- and microtreated titanium implants in the dogs 
A number of studies about the nano-treated surfaces of implants have been conducting along with micro-treated surfaces of implants.
The purpose of this study was to get information for the clinical use of nano-treated surfaces compared with micro-treated surfaces by measuring removal torque and analyzing histological characteristics after the placement of various surface-treated implants on femurs of dogs.
Machined surface implants were used as a control group. 4 nano-treated surface implants and 3 micro-treated surface implants [resorbable blast media surface (RBM), sandblast and acid-etched surface (SAE), anodized RBM surface] were used as experimental groups. Removal torque values of implants were measured respectively and the histological analyses were conducted on both 4weeks and 8weeks after implant surgery. The surfaces of removed implants after measuring removal torque values were observed by scanning electron microscopy (SEM) at 8 weeks.
1. Removal torque values of the nano-treated groups were lower than those of micro-treated groups. 2. Removal torque values were similar in the anodized RBM surface groups. 3. On the histological views, there was much of bone formation at 8 weeks, but there was no difference between 4 and 8 weeks, and between the types of implant surfaces as well.
It is suggested that implant topography is more effective in removal torque test than surface chemistry. To get better clinical result, further studies should be fulfilled on the combined effect of surface topography and chemistry for the implant surface treatments.
PMCID: PMC2994682  PMID: 21165259
removal torque; implant; surfaces characteristics; dog; histology; SEM
4.  Effect of adhesive primers on bonding strength of heat cure denture base resin to cast titanium and cobalt-chromium alloy 
The poor chemical bonding of a denture base resin to cast titanium framework often introduces adhesive failure and increases microleakage.
This study evaluated the shear bond strengths of a heat cure denture base resin to commercially pure titanium, Ti-6Al-4V alloy and a cobalt-chromium alloy using two adhesive primers.
Disks of commercially pure titanium, Ti-6Al-4V alloy and a cobalt-chromium alloy were cast. Specimens without the primer were also prepared and used as the controls. The shear bond strengths were measured on a screw-driven universal testing machine.
The primers significantly (P < .05) improved the shear bond strengths of the heat cure resin to all metals. However, the specimens primed with the Alloy primer® (MDP monomer) showed higher bond strength than those primed with the MR bond® (MAC-10 monomer) on titanium. Only adhesive failure was observed at the metal-resin interface in the non-primed specimens, while the primed specimens showed mixed failure of adhesive and cohesive failure.
The use of appropriate adhesive metal primers makes it possible not only to eliminate the need for surface preparation of the metal framework before applying the heat cure resins, but also reduce the need for retentive devices on the metal substructure. In particular, the Alloy primer®, which contains the phosphoric acid monomer, MDP, might be clinically more acceptable for bonding a heat cure resin to titanium than a MR bond®, which contains the carboxylic acid monomer, MAC-10.
PMCID: PMC2994673  PMID: 21165254
Heat cure denture base resin; Adhesive primers
5.  Comparion of stability in titanium implants with different surface topographies in dogs 
A few of studies which compared and continuously measured the stability of various surface treated implants in the same individual had been performed.
We aim to find the clinical significance of surface treatments by observing the differences in the stabilization stages of implant stability.
Eight different surface topographies of dental implants were especially designed for the present study. Machined surface implants were used as a control group. 4 nano-treated surface implants (20 nm TiO2 coating surface, heat-treated 80 nm TiO2 coating surface, CaP coating surface, heat treated CaP coating surface) and 3 micro-treated surface implants [resorbable blast media (RBM) surface, sandblast and acid-etched (SAE) surface, anodized RBM surface] were used as experiment groups. All 24 implants were placed in 3 adult dogs. Periotest® & ISQ values measured for 8 weeks and all animals were sacrificed at 8 weeks after surgery. Then the histological analyses were done.
In PTV, all implants were stabilized except 1 failed implants. In ISQ values, The lowest stability was observed at different times for each individual. The ISQ values were showed increased tendency after 5 weeks in every groups. After 4 to 5 weeks, the values were stabilized. There was no statistical correlation between the ISQ values and PTV. In the histological findings, the bone formation was observed to be adequate in general and no differences among the 8 surface treated implants.
In this study, the difference in the stability of the implants was determined not by the differences in the surface treatment but by the individual specificity.
PMCID: PMC2994674  PMID: 21165255
Implant stability quotient (ISQ); Periotest value (PTV); Stability; Surface treatment; Titanium implant
6.  Cell response to a newly developed Ti-10Ta-10Nb alloy and its sputtered nanoscale coating 
The success of titanium implants is due to osseointegration or the direct contact of the implant surface and bone without a fibrous connective tissue interface.
The purpose of this study was to evaluate the osteoblast precursor response to titanium - 10 tantalum - 10 niobium (Ti-Ta-Nb) alloy and its sputtered coating.
Ti-Ta-Nb coatings were sputtered onto the Ti-Ta-Nb disks. Ti6-Al-4V alloy disks were used as controls. An osteoblast precursor cell line, were used to evaluate the cell responses to the 3 groups. Cell attachment was measured using coulter counter and the cell morphology during attachment period was observed using fluorescent microscopy. Cell culture was performed at 4, 8, 12 and 16 days.
The sputtered Ti-Ta-Nb coatings consisted of dense nanoscale grains in the range of 30 to 100 nm with alpha-Ti crystal structure. The Ti-Ta-Nb disks and its sputtered nanoscale coatings exhibited greater hydrophilicity and rougher surfaces compared to the Ti-6Al-4V disks. The sputtered nanoscale Ti-Ta-Nb coatings exhibited significantly greater cell attachment compared to Ti-6Al-4V and Ti-Ta-Nb disks. Nanoscale Ti-Ta-Nb coatings exhibited significantly greater ALP specific activity and total protein production compared to the other 2 groups.
It was concluded that nanoscale Ti-Ta-Nb coatings enhance cell adhesion. In addition, Ti-Ta-Nb alloy and its nanoscale coatings enhanced osteoblast differentiation, but did not support osteoblast precursor proliferation compared to Ti-6Al-4V. These results indicate that the new developed Ti-Ta-Nb alloy and its nanoscale Ti-Ta-Nb coatings may be useful as an implant material.
PMCID: PMC2994675  PMID: 21165256
Implant; Ti-Ta-Nb; Cell response; Sputter; Nanoscale; Osteoblast
7.  Oral rehabilitation for a patient with oligodontia and maxillary hypoplasia 
An 18 year old female with oligodontia and maxillary hypoplasia was treated using an interdisciplinary team approach involving orthodontists, maxillofacial surgeons and prosthodontists. Full mouth one-piece fixed partial dentures were the final restoration. The fixed partial dentures fabricated for the maxilla and mandible using the concept of a shortened dental arch resulted in improved esthetics and the masticatory function. This paper describes the treatment procedures for an oligodontia patient with alveolar bone hypoplasia.
PMCID: PMC2994676  PMID: 21165248
Rehabilitation; Oligodontia; Interdisciplinary; Shortend dental arch; Esthetics

Results 1-7 (7)