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The aim of this study was to investigate the characteristic gene expression profile and localization of peri‐implant connective tissue (PICT) compared with those of periodontal connective tissue (PCT) and oral mucosal connective tissue (OMCT). Upper first molar of 5‐week‐old rats were extracted and titanium implant were placed for PICT group. PCT and OMCT were used as control. Laser microdissected connective tissue at 4 weeks used for microarray analysis. The expression and localization of selected genes were confirmed by quantitative real‐time PCR (qRT‐PCR) and immunohistochemistry. Approximately, 1000 genes of upregulated and downregulated in PICT compared with PCT and OMCT were recognized. Based on the results of microarray analysis and qRT‐PCR were demonstrated lipopolysaccharide binding protein (Lbp) as a specific upregulated gene and superoxide dismutase 3 (Sod3) as a specific downregulated gene in PICT. Immunoreaction of LBP and F4/80 as macrophage marker localized to subepithelial and implant facing connective tissue in PICT. SOD3 expression was not observed in PICT, reactive oxygen species, a target of superoxide dismutase, was strongly and locally expressed in all three tissues. Our data suggested that the upregulation of Lbp and downregulation of Sod3 are as characteristic gene expression pattern in PICT. [ABSTRACT FROM AUTHOR]

The importance of considering bone quality during oral implant treatment is increasingly being recognized. Assessment of bone quality in response to changes in the jaw bone is extremely important when planning treatment. The present study analyzed biological apatite (BAp) crystallites, a bone quality factor, in order to investigate crystallographic anisotropy in dentate and edentulous human mandibles. Using mandibular samples from Japanese adult cadavers, a region of interest was established comprising cortical bone in the central incisors. Samples were classified into five morphological categories based on the extent of bone resorption. Bone mineral density (BMD) was measured and diffraction intensity ratios were calculated using a microbeam X‐ray diffraction system. While no differences were observed in BMD, differences were observed in BAp crystallite alignment between the measurement points. In the alveolar region, samples with residual alveolar bone showed strong alignment in the occlusal direction, while samples with marked alveolar bone resorption had preferential alignment in the mesiodistal direction. The present findings suggest that tooth loss and the extent of alveolar bone resorption affects bone quality in the mandible. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B: 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 838–846, 2019. [ABSTRACT FROM AUTHOR]

Objectives The peri-implant epithelium ( PIE) plays an important role in the prevention against initial stage of inflammation. To minimize the risk of peri-implantitis, it is necessary to understand the biological characteristics of the PIE. The aim of this study was to investigate the characteristic gene expression profile of PIE as compared to junctional epithelium ( JE) using laser microdissection and microarray analysis. Methods Left upper first molars of 4-week-old rat were extracted, and titanium alloy implants were placed. Four weeks after surgery, samples were harvested by laser microdissection, and total RNA samples were isolated. Comprehensive analyses of genes expressed in the JE and PIE were performed using microarray analysis. Confirmation of the differential expression of selected genes was performed by quantitative real-time polymerase chain reaction and immunohistochemistry. Results The microarray analysis showed that 712 genes were more than twofold change upregulated in the PIE compared with the JE. Genes Scgb1a1 were significantly upregulated more than 19.1-fold, Lpo more than 19.0-fold, and Gbp2 more than 8.9-fold, in the PIE ( P < 0.01). Immunohistochemical localization of SCGB1 A1, LPO, and GBP2 was observed in PIE. Conclusion The present results suggested that genes Scgb1a1, Lpo, and Gbp2 are characteristically expressed in the PIE. [ABSTRACT FROM AUTHOR]

DNA coating on dental titanium (Ti) implants is attracting attention due to its osteogenic properties. The aim of the present study was to evaluate in vitro and in vivo bioactivities of a multilayered DNA/protamine (D/P) coating on Ti implant by simulated body fluid (SBF) immersion experiments and implantation experiments into extracted sockets of rat molars. Two types of DNA, 300 base pair (bp) and 7000 bp fragments, were used. Protamine was initially immobilized onto Ti implants using a tresyl chloride-activated method and DNA and protamine were then alternatively deposited after the immobilization of protamine by a layer-by-layer technique. A multilayered D/P-coating was confirmed by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy measurements. The deposition of apatite progressed more on the surfaces of multilayered D/P-coated Ti implants than on those of nontreated Ti implants in SBF immersion experiments. Animal implantation experiments showed that multilayered D/P-coated Ti implants provided a significantly higher bone-to-implant (BIC) contact ratio 3 weeks after implantation. No significant difference was observed in the BIC ratio 9 weeks after implantation. The results of the present study demonstrated that a multilayered D/P-coating promoted new bone formation at the early stages of the bone healing process. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1500-1509, 2016. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop and evaluate a dental implant surgery simulator that allows learners to experience the drilling forces necessary to perform an osteotomy in the posterior mandibular bone. The simulator contains a force-sensing device that receives input and counteracts this force, which is felt as resistance by the user. The device consists of an actuator, a load cell, and a control unit. A mandibular bone model was fabricated in which the predicted forces necessary to drill the cortical and trabecular bone were determined via micro CT image-based 3D finite element analysis. The simulator was evaluated by five dentists from the Department of Implantology at Tokyo Dental College. The ability of the evaluators to distinguish the drilling resistance through different regions of the mandibular bone was investigated. Of the five dentists, four sensed the change in resistance when the drill perforated the upper cortical bone. All five dentists were able to detect when the drill made contact with lingual cortical bone and when the lingual bone was perforated. This project successfully developed a dental implant surgery simulator that allows users to experience the forces necessary to drill through types of bone encountered during osteotomy. Furthermore, the researchers were able to build a device by which excessive drilling simulates a situation in which the lingual cortical bone is perforated--a situation that could lead to negative repercussions in a clinical setting. The simulator was found to be useful to train users to recognize the differences in resistance when drilling through the mandibular bone. [ABSTRACT FROM AUTHOR]

Surface modification technologies are available for tetragonal zirconia polycrystal (TZP) to enhance its bioactivity and osseointegration capability. The surface wettability of an implant material is one of the important factors in the process of osseointegration, possibly regulating protein adsorption, and subsequent cell behavior. The aim of this study was to clarify the effect of topographical or physicochemical modification of TZP ceramics on wettability to determine the potential of such treatment in application to implants. Several types of surface topography were produced by alumina blasting and acid etching with hydrofluoric acid; surface physicochemistry was modified with oxygen (O2) plasma, ultraviolet (UV) light, or hydrogen peroxide treatment. The obtained specimens were also subjected to storage under various conditions to evaluate their potential to maintain superhydrophilicity. The results showed that surface modification of surface topography or physicochemistry, especially of blast/acid etching as well as O2 plasma and UV treatment, greatly increased the surface wettability, resulting in superhydrophilicity. X-ray photoelectron spectroscopy revealed that a remarkable decrease in carbon content and the introduction of hydroxyl groups were responsible for the observed superhydrophilicity. Furthermore, superhydrophilicity was maintained, even after immersion in an aqueous solution, an important consideration in the clinical application of this technology. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the influence of mechanical treatment, namely, nanometer smoothing (Ra: approximately 2.0 nm) and sandblasting (Ra: approximately 1.0 μm), as well as biochemical treatment, namely, fibronectin immobilization, of a titanium surface on osteoblast-like cell behavior. Cell proliferation was monitored by measurements of DNA content and ALP activity; osteocalcin production and mineralization behavior were also evaluated, in addition to morphological observation of attached cells. Fibronectin could be immobilized by the tresyl chloride-activation method. A sandblasted surface resulted in significantly more DNA than a nanometer-smooth surface, but fibronectin immobilization did not result in a significant increase of DNA at 52 days of cell culture. The nanometer-smooth surface showed highest ALP activity and osteocalcin production. FN immobilization decreased ALP activity for the nanometer-smooth surface, but increased it for the sandblasted surface. The nanometer-smooth surface also showed the highest osteocalcin production. Scanning electron microscopy showed interesting phenomena of the attached cells. Attached cell area was more rapidly increased on the nanometer-smooth surface than on the sandblasted surface. It was suggested that cultured cells on the nanometer-smooth surface began to spread earlier and that the proportion of spreading cells among total attached cells increased sooner on the nanometer-smooth surface than on the sandblasted rough surface. It appeared that FN immobilization influenced the arrangement of attached cells. In conclusion, the nanometer-smooth surface employed in the present study was beneficial for the differentiation of MC3T3-E1 cells. FN immobilization influenced the morphologies of attached cells. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2012. [ABSTRACT FROM AUTHOR]

The present study was aimed to evaluate the viability and total protein contents of osteoblast-like cells on the titanium surface with different surface mechanical treatment, namely, nanometer smoothing (Ra: approximately 2.0 nm) and sandblasting (Ra: approximately 1.0 μm), and biochemical treatment, namely, with or without fibronectin immobilization. Fibronectin could be easily immobilized by tresyl chloride-activation technique. MC3T3-E1 cells were seeded on the different titanium surfaces. Cell viability was determined by MTT assay. At 1 day of cell culture, there were no significant differences in cell viability among four different titanium surfaces. At 11 days, sandblasted titanium surface with fibronectin immobilization showed the significantly highest cell viability than other titanium surface. No significant differences existed for total protein contents among four different titanium surfaces at 11 days of cell culture. Scanning electron microscopy observation revealed that smoothness of titanium surface produced more spread cell morphologies, but that fibronectin immobilization did not cause any changes of the morphologies of attached cells. Fibronectin immobilization provided greater amount of the number of attached cells and better arrangement of attached cells. In conclusion, the combination of sandblasting and fibronectin immobilization enhanced the cell viability and fibronectin immobilization providing better arrangements of attached cells. [ABSTRACT FROM AUTHOR]

Although fluoride induces corrosion in titanium in an oral environment, the influence of protein on this corrosion remains to be clarified. The objective of this study was to investigate suppression of fluoride‐induced corrosion of titanium where albumin was either present in a solution or where albumin was preadsorbed on titanium. Titanium dissolution in titanium specimens and surface characterization of each specimen were determined. Dissolution in a saline solution containing both albumin and fluoride was less than that in only fluoride‐containing saline solution. The titanium specimen was covered in an albumin film. The morphology of the titanium in the fluoride‐containing saline solution revealed jagged edges, whereas titanium immersed in the saline solution containing albumin and fluoride showed a round and plate‐like morphology. When albumin‐adsorbed titanium was immersed in a fluoride‐containing solution, dissolution within 6 h was less than that in non albumin‐adsorbed titanium. Dissolution increased with desorption of adsorbed‐albumin from the titanium surface. The results suggest that albumin in a solution suppresses dissolution of titanium compounds, thus influencing their morphology. Albumin adsorbed on titanium reduces fluoride attack and suppresses dissolution. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

Surface wettability is an important physicochemical property of biomaterials, and it would be more helpful for understanding this property if a wide range of wettability are employed. This study focused on the effect of surface wettability on fibroblast adhesion over a wide range of wettability using a single material without changing surface topography. Plasma polymerization with hexamethyldisiloxane followed by oxygen (O2)‐plasma treatment was employed to modify the surfaces. The water contact angle of sample surfaces varied from 106° (hydrophobicity) to almost 0° (super‐hydrophilicity). O2 functional groups were introduced on polymer surfaces during O2‐plasma treatment. The cell attachment study confirmed that the more hydrophilic the surface, the more fibroblasts adhered in the initial stage that includes super‐hydrophilic surfaces. Cells spread much more widely on the hydrophilic surfaces than on the hydrophobic surfaces. There was no significant difference in fibroblast proliferation, but cell spreading was much greater on the hydrophilic surfaces. The fibronectin adsorbed much more on a hydrophilic surface while albumin dominated on a hydrophobic surface in a competing mode. These findings suggest the importance of the surface wettability of biomaterials on initial cell attachment and spreading. The degree of wettability should be taken into account when a new biomaterial is to be employed. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [ABSTRACT FROM AUTHOR]

Background: The seal between an implant and the oral epithelium is an important factor for successful implant therapy. The purpose of this study was to evaluate the initial attachment and subsequent behavior of rat oral epithelial (OE) cells on pure titanium (Ti) used for dental implants. Methods: OE cells derived from 4-day-old rats were cultured on Ti, polystyrene culture dishes, and glass coverslips. The number of attached cells, cell areas, number of colonies, and proliferation rates were measured. Additionally, immunostaining of vinculin and laminin-5 (LN5) was performed, and LN5-immunoreactive areas were measured. Results: After 24 hours of culture, there were fewer cells attached to the Ti than to the polystyrene dishes or glass coverslips, and the area of cells was greater on the polystyrene than on the Ti or glass. OE cells reached their maximum proliferation rate after 45 hours of culture on the polystyrene and glass, and after 72 hours on Ti. LN5 was deposited behind cells as they migrated, and the LN5-immunoreactive area was smaller on Ti than on polystyrene after 96 hours of culture. Conclusions: The initial attachment of OE cells to Ti was inferior to that on polystyrene or glass, and the OE cell migration area indicated by the deposition of LN5 was smaller on Ti than on the other materials. Therefore, this study suggests that further improvement of Ti surface properties is needed for rapid attachment and spreading of oral epithelium to dental implants. [ABSTRACT FROM AUTHOR]

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The influence of surface roughness and calcium phosphate (Ca-P) coating on the bone response of titanium implants was investigated. Four types of titanium implants, i.e. as-machined, grit blasted, as-machined with Ca-P sputter coating, and grit blasted with Ca-P sputter coating, were prepared. The Ca-P sputter-coating, produced by using the RF magnetron sputter technique, was rapid heat-treated with infrared radiation at 600°C. These implants were inserted into the left and right femoral condyles and the left and right tibial diaphyses of the rabbits. After implantation periods of 2 and 12 weeks, the bone–implant interface was evaluated histologically and histomorphometrically. Histological evaluation revealed no new bone formation around different implant materials after 2 weeks of implantation. After 12 weeks, bone healing was almost completed. For both tibial and femoral implants, Ca-P coated implants always showed a higher amount of bone contact than either of the non-coated implants. On the other hand, surface roughness improved only the response to implants inserted into the tibial diaphysis. On the basis of these findings, we concluded that 1) deposition of a sputtered Ca-P coating on an implant has a beneficial effect on the bone response to this implant during the healing phase, and 2) besides implant surface conditions the bone response is also determined by local implant site conditions. [ABSTRACT FROM AUTHOR]

Background: The role played by the internal basal lamina (IBL} and hemidesmosomes between an implant and the peri-implant epithelium (PIE) in the adherence of the epithelium to the implant is controversial. This study used rat maxilla implantation models to clarify the ultrastructure of the PIE-implant interface. Methods: Ti-6AI-4V implants were inserted either immediately or 2 weeks after the extraction of the upper left first molar of 6- or 4-week-old rats, respectively. The junctional epithelium (JE) of the upper right molars in the same animals was used as a control. Four weeks after implantation, the animals are sacrificed to prepare specimens for light and immunoelectron microscopy. Results: Under light microscopy, the PIE appeared to attach to the implant surface. Ultrastructurally, IBL, consisting of the lamina densa and lamina lucida, and hemidesmosomes were formed only in the lower region, and rarely in the middle region, of the PIE-implant interface. In control teeth, the IBL and hemidesmosomes formed throughout the dento-JE interface. Laminin-1 was found in the IBL and also in the vesicles and vacuoles of the PIE and JE cells. Statistical analysis showed that there was also a significant difference in the amount of IBL between the PIE-implant and dento-JE interfaces. Conclusions: PIE attached to the implant via hemidesmosomes and IBL in the lower region of the PIE-implant interface. Although PIE cells may secrete laminin-1, which contributes to epidermal cell adhesion, the PIE which attaches to implants only in the lower region of the interface is considered to be the poorly adhered epithelium. [ABSTRACT FROM AUTHOR]