It is popular in these days to use a CT simulation data to determine the bone graft volume in dental implant cases with bone defect and the precise implant placement position. However there has been no report on converting the simulation data three-dimensionally to fabricate bone augmentation materials. In this study a HA bone graft was fabricated from a sintered HA block using a CAD/CAM technique based on the bone augmentation volume data determined by the simulation data. The HA graft was evaluated by comparing with a resin graft model fabricated by a three dimensional printing (3DP) method based on the same simulation data. The HA bone graft by CAD/CAM and the resin bone graft by 3DP was well consistent each other in the shape , size, and adaptability.

View full abstract

Hydroxyapatite (HA) is chemically active in solution and adsorbs protein, lipid, sugar and metal ions. In 1978 the tooth paste containing HA was invented by Hideki Aoki of Japan. Afterwards, the clinical test was carried out for five years at the Tokyo Medical and Dental University and School of Dentistry, Asahi University. The clinical results showed that the HA is very effective to prevent generation of caries. Then, it was found that the HA toothpastes have been commercially sold well in Japan. However, there has been little information about details of HA toothpastes to dentists and consumer public. In this paper, seven commercial HA toothpastes were crystallochemically investigated using an X-ray diffractometry (XRD). The abrasive materials were obtained by filtering the suspension of 500ml water and 3g of each tooth paste. The abrasives were analyzed by XRD to determine the crystal phases and crystallite size. The XRD patterns of non-heated abrasives revealed that the abrasives in the HA toothpaste included HA[Ca10(PO4)6(OH)2], monetite (CaHPO4; DCPA), brushite (CaHPO4・2H2O; DCPD), and calcite (CaCO3). The crystallite size of HA in the toothpaste varied from 30 to 70 nm. The HA content also ranged from 7.1 to 32.8 wt%, and the HA content was lower than detection limits of XRD in some HA toothpaste. These results indicated that the commercial HA toothpastes have various crystallinities and concentration of HA.

View full abstract

Magnesium substituted hydroxyapatite (Mg-HA) thin films were coated on a titanium substrate using a rfmagnetron sputtering method in Ar gas. HA/MgO mixture powder was used as the target. The molar ratio of Mg to Ca in the mixture target was varied in the ratio of 0:10, 2:8, 4:6, 6:4 and 8:2. The sputtered Mg-HA films were subjected to a hydrothermal treatment. The crystallinity of the Mg-HA films were observed by X-ray diffractometer (XRD). The solubility of the Mg-HA films were measured by an ICP analysis after immersion test in deionized water and phosphate buffered saline (PBS). The XRD patterns revealed that the hydrothermally crystallized HA (Mg:Ca=0:10) film and Mg-HA (Mg:Ca=2:8, 4:6) films were mainly an HA diffraction pattern, on the other hand, the Mg-HA (Mg:Ca=8:2) film was MgO. From the immersion test, the solubility of the HA and Mg-HA films decreased after the hydrothermal treatment. The HA and Mg-HA (Mg:Ca=2:8) films were more soluble in deionized water than PBS. However, the Mg-HA (Mg:Ca=4:6, 6:4, 8:2) films were soluble in PBS than deionized water.

View full abstract

In the therapy for hypersensitivity of tooth, it is well-known that potassium (K) compounds, such as potassium nitrate and potassium bromide, are often added in toothpastes because it is believed that neurotransmission is blocked by potassium ions. Recently, we have been proposing the attachment therapy of a hydroxyapatite (HAp) sheet on dentin for hyperesthesia. It is thought that addition of K ions in HAp sheet is more effective for relieve pain of tooth hypersensitivity. In this study, we prepared a K-containing HAp (K-HAp) thin film by pulsed laser deposition and evaluated the material properties, such as solubility, crystallization and atomic composition. X-ray diffraction results showed that a-axis of K-HAp was shorter than that of the conventional HAp. Energy dispersive X-ray diffraction results indicated that K ions were contained in the thin film. From the results of Fourier transform infrared spectroscopy, the hydroxy group peaks decreased in tha inclusion of K. Inductively coupled plasma-mass spectrometry results showed that the sustained release of K ions from the crystalized K-HAp was observed. Thus, the K-HAp sheet is expected to be more effective for therapy of hyperesthesia compared with the original HAp sheet.

View full abstract

Carbon felt is composed of carbon fibers and, when calcined at high temperatures in the vicinity of 2000 °C or above, exhibits specific properties, including a large specific area, low electrical resistance and high microwave absorptivity. Recently, it was found that irradiation of a pair of disc-like carbon felts arranged in parallel with a ceramic ring spacer by 2.45 GHz microwaves (MW) under atmosphere air generates a thermal discharge plasma, termed a carbon felt atmospheric pressure microwave plasma (CAMP), at the gap between the felts. The temperature of the gap increases rapidly to reach thermal equilibrium at 1200 °C or higher in approximately 20 seconds, although the temperature at the circumference of felts can be as low as 200 °C 1). In the present study, the surface nitriding and oxynitridation of titanium by CAMP under atmospheric pressure nitrogen were successfully performed using carbon felts as a MW absorbing material. In addition, the formation of hydroxyapatite (HAp) by surface contact with a simulated body fluid (SBF) was assessed. The resulting surfaces of the titanium substrates were analyzed by X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy.

View full abstract

Objective: To optimize the concentration of contrast media and to compare the ability of cone beam CT (CBCT) and multidetector CT (MDCT) in detecting the adhesion of the TMJ disk by CT- arthrography. Materials and Method: The square shape phantom made by nylon thread, which was simulated for adhesive change in TMJ space was used. The eight types of threads (diameter: 0.128, 0.148, 0.165, 0.205, 0.235, 0.330, 0.405, and 0.500 mm) were joined inside the phantom in parallel at 1 mm interval. The contrast media (Omnipaque 350mg I /ml) was diluted with water, and seven types of the media with diff erent concentration, 5%, 10%, 20%, 30%, 40%, 50%, and 100%, were examined. A thread phantom was kept in the rubber balloon, which fi lled with contrast media and then placed in the TMJ space of the cadaver, so that all of the threads paralleled the F-H plane as possible. The phantom in the TMJ space was investigated using cone beam CT (CBCT) and multi-detector CT (MDCT). The voxel size was approximately 0.125×0.125×0.125 mm and 0.1×0.1×0.6 mm, respectively. Four observers independently assessed, whether the defect of contrast media by thread was present or not in 12 consecutive slices in the middle of the thread. MDCT images were examined by printed on fi lm and CBCT in computer display. Results: The detected threads in the TMJ disk space in the contrast media that CBCT was superior to MDCT. Statistically signifi cant diff erences (p　0.01) were found almost all detected threads. Conclusion: MDCT and CBCT are similar detectability, when adequate concentration of contrast media is used. However, CBCT can be used for the arthrography of TMJ with less concentration of contrast media, low radiation dose, lowest price and narrow space than MDCT.

View full abstract

This study evaluated the effects of different implant surface roughness and implant materials on bacterial attachment and biofilm formation. The 4 different surface-treated titanium plates (17.0 mm × 10.0 mm × 1.0 mm) were used including MS: Machined surface, SBA: Sandblasted-acid etched surface, RA1.5: HA sputter-coated surface and RA3.0: HA sputter-coated surface (rougher surface than RA1.5). Thirty samples were fabricated for experiments on each of the different surfaces. Two bacterial species were used in this study: Streptococcus mutans and Porphyromonas gingivalis. S. mutans was cultured in BHI agar or broth mediums containing 1% of sucrose. P. gingivalis was cultured in horse blood agar mediums containing hemin and menadione and BHI broth coutaing them under an anaerobic condition at 37°C. Evaluation Method: The mean value of the colony forming unit (CFU) attached to each sample was calculated from data obtained and compared to that of different implant materials. Regarding S. mutans, there was no difference between SBA and MS. However, when compared with SBA, the values of CFU of RA1.5 and RA3.0 were 2.4 times and 2.9 times larger, respectively. There were no significant differences in P. gingivalis. These results suggest that the bacterial attachment might be affected by the difference of implant surface characteristics and surface roughness.

View full abstract

Objective : To evaluate quantitatively the metal artifacts on 3DX Accuitomo images using the titanium cylinders in relation to various exposure protocols. Materials and method : For the evaluation of artifacts, titanium cylinders were fabricated. The titanium cylinders of 2.99 and 3.49 mm were installed in anterior and posterior segments of the plastic model of the mandible. Cylinders with heights of 15.07 mm for 2.99 mm and 15.06 mm for 3.49 mm diameter were prepared from a titanium rod. The cylinders were placed 10 mm from each other, and their positions were in two central incisors for anterior and molar regions for the posterior segment. CBCT examinations were performed with 3DX Accuitomo, FPD type (Morita Corp., Kyoto, Japan). The titanium cylinders were imaged at the same position at tube voltages of 60 and 90 kV, a tube current of 4 mA, and an exposure time of 17 seconds. The voxel size was 0.125 mm. The heights of the cylinders were measured in coronal and sagittal images. Diameter measurement was performed at the center of the cylinder. The anteroposterior (AP) and mediolateral (ML) diameters of cylinders were measured in axial images. All data were evaluated with the Image J and OsiriX image analysis software. Results : In the measurement of the heights of the titanium cylinders, the mean heights deviated from 100.85% to 101.46%, and 100.59% to 101.12 % for a single cylinder for 60 and 90 kV, respectively. For double cylinders, the mean heights were from 101.39% to 101.72%, and 101.12% to 101.12% for 60 and 90 kV, respectively. The mean diameters anteroposteriorly and mediolaterally were (102.86% to 104.01%, and 102.29% to 102.67%; and 102.00% to 103.01%, and 101.67% to 101.71%) for a single cylinder for 60 and 90 kV, respectively. For double cylinders, the mean diameters anteroposteriorly and mediolaterally were (102.86% to 104.86%, and 100.28% to 104.01%; and 102.86% to 104.01%, and 102.00% to 102.67%) for 60 and 90 kV, respectively. Conclusion : CBCT is used as an alternative to conventional CT for dental diagnosis. Artifacts can degrade the quality of images, sometimes causing instability in the diagnosis. There are some factors that may cause artifacts, such as patient positioning and the presence of metallic materials. However, for determining the bone quality of the mandible, it is necessary to evaluate preoperatively metal artifacts for successful implant installation.

View full abstract

The aim of this study was to evaluate the thicknesses of cancellous and cortical bones, and to identify and measure variation in the presence and extent of the anterior loop of the mandibular canal and canal itself in the anterior and posterior regions. A total of 79 patients (52 males and 27 females; age range: 19-77 years; mean age: 49 years) were scanned by computed tomography and the data were analyzed. The means and SD of the cancellous (CAB) and cortical (COB) thicknesses ranged from 5.5 ± 1.2 mm to 11.1 ± 2.2 mm and from 4.5 ± 1.0 mm to 5.3 ± 0.9 mm for males, respectively. For females, the cancellous and cortical thicknesses ranged from 4.8 ± 1.3 mm to 10.3 ± 1.5 mm and from 3.8 ± 1.0 mm to 5.3 ± 1.2 mm, respectively. The morphology of the mandible was classified into three types: type B (62%-72%), was the most common in the anterior region for males, followed by type C (56%-58%) in the posterior region. For females, type C (25%-31%) in the posterior region and type B (18%-30%) in the anterior region were the most common types. For implant placement on the mandible, careful evaluation and full knowledge of the thicknesses of the cancellous and cortical thickness are necessary; these results can help surgeons in terms of appropriate implant operation.

View full abstract

The aim of this study is to histologically compare the osseointegration of 2 types of hydroxyapatite (HA)- coated implants, a JHA implant (Kyocera Medical Ltd, Japan) and a KHA implant (Zimmer Ltd, USA), with the new　bone forming in the space under the lifted membrane (SULM) in a long-term animal experiment of one stage sinus floor elevation (SFE), without bone substitutes and mechanical loading, using canine frontal sinuses. Sixteen implants, 8 JHA and 8 KHA were placed in 4 postmenopausal beagles for 3 and 6 months. Histological observations and histomorphometric measurements were carried out with light-microscopy using hematoxylin and eosin stained undecalcified specimens. Statistical significant differences were evaluated by one-way ANOVA. The new bone formation was observed on a large area of the sinus wall and the implant surface in the SULM at 3 and 6 months in both groups. Bone implant contact rate with new bone in the SULM was 88.8±10.5% at 3 months and 77.0±7.9% at 6 months in JHA group, and 85.3±7.6 and 87.3±17.9% in KHA group, respectively. There was no statistical significant difference between the groups. It was concluded that both types of HA-coated implants have similar properties to promote a superior osseointegration with the new bone forming in the SULM. Furthermore, the new bone which osseointegrated with the HA-coated implants has a possibility to remain for a long time.

View full abstract

The aim of this study is to evaluate the clinical outcomes of transcrestal sinus floor elevation (TSFE) procedure using HA-coated implants without bone grafts. Using TSFE procedure without bone grafts or bone substitutes, 175 HA-coated implants were placed in the elevated sinus of 107 cases. The survey was performed on the cases with prosthesis restoration completed over a time period of 130 months from March 2004 to December 2014. All implants except one gained osseointegration. Five implant failures occurred in 4 cases after addition of occlusal force. Four implants were replaced in 3 failed cases, and all 4 implants gained osseointegration. In all 107 cases, no postoperative complication such as sinusitis, nasal bleeding or rhinorrhea was experienced. TSFE procedure using HA-coated implants without bone graft is highly reliable, predictable and less invasive. There is no risk of maxillary sinusitis induced by grafted bone’s migration into sinus cavity or infection by an unknown virus derived from the use of xenograft and allograft. After performing TSFE even on cases with small vertical bone height, replacement of failed implants is possible.

View full abstract