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The purpose of this review is to search for complications of dental implant superstructures and consider the issues involved. This narrative review was performed by searching through PubMed databases and review articles that were published after 1990. Misfitting of the superstructure can result in loosening of screws, reduced preload, and in some cases, significant stress around the implant. External connection modalities and single implant prostheses have been reported to have more loose or broken abutment screws. In addition, when zirconia abutment was used for platform shifting, the rate of fracture of the abutment was considered to be high. Additionally, it was reported that men were significantly at an increased risk of abutment fracture. As for the retention mechanism of implant overdenture, stud attachment (Locator type) should receive more attention to wear and damage of retention parts than other attachments. The causes of the complications of implant superstructures have not been clarified in some cases, and further verification is required. Verification of complications is considered important to obtain a long-term prognosis for superstructures of implants. It will be necessary to further verify complications of implants in the future.

Abstract A DNA hybridization-based differential peptide display (DPD) was developed for the screening of phage peptide library to find osteogenic peptides intended to bind to epigenetically induced osteogenic receptors on NIH/3T3 (3T3) cell surface. In the presence of DNA methylation inhibitor of 5-azacytidine (5AZC), an osteoblastic receptor of bone morphogenetic protein (BMP) receptor 1A (BMPR1A) was induced on the cell surface of NIH/3T3 fibroblasts. Cyclic heptamer-displaying phage library was screened against vehicle and 5AZC treated (Tx) 3T3 cells. Antisense oligo against library against library peptide coding DNA of control 3T3 cell bound phages were synthesized to subtract common binders from that of 5AZC-Tx 3T3 cell-bound phages that included 5AZC-induced receptor binders. The library peptide coding regions of conformational receptor binder-subtracted DPD were PCR-amplified and cloned into a plasmid vector specifically designed for short peptide expression. No unique binder was identified when 96 clones were randomly picked from the third round of panning against 5AZC-treated 3T3 cells, suggesting miscellaneous bindings to cell surface proteins. Unique binders showing homology to known function proteins were successfully identified when constitutive receptor binders were subtracted from 5AZC-induced protein binders. Some of identified peptides significantly increased alkaline phosphatase activity in 5AZC-Tx 3T3 cells. DPD can be a useful tool to screen functional peptide bindings to cell surface receptors. Graphic Abstract

Collagenous biomaterials that are clinically applied in dentistry have dermis-type and membrane-type, both of which are materials for promoting bone and soft tissue formation. The properties of materials supplied with different types could affect their biodegradation periods. The purpose of this study was to characterize five of these products by four different methods: scanning electron microscopy (SEM) observation, thermogravimetry-differential thermal analysis (TG-DTA), 0.01 wt% collagenase dissolution test, and subcutaneous implantation test in vivo. SEM micrographs revealed that both dermis and membranous materials were fibrous and porous. The membranous materials had higher specific derivative thermal gravimetry (DTG) peak temperatures in TG-DTA at around 320 °C, longer collagenase dissolution time ranging from about 300 to 500 min, and more longevity in mice exceeding 9 weeks than the dermis materials. There existed a correlation between the peak temperature in TG-DTA and the collagenase dissolution time. It was considered that higher cross-link degree among collagen fibrils of the membrane-type collagenous materials might account for these phenomena. The experimental protocol and numerical results obtained could be helpful for selection and future development of fibrous collagenous biomaterials in clinical use.

When the sinus is enlarged, it may be necessary to elevate the floor of the maxillary sinus using the crestal or lateral approach. This report presents a case where sinus floor elevation was performed using tricalcium phosphate (TCP) plates supported by implant bodies, and only the blood clot was present around the implant bodies. Cone-beam computed tomography images, taken one year after the lateral approach, revealed the presence of a TCP-like radio-opacity, which almost disappeared after two years. About seven years after the surgery, the patient's superstructure and occlusion were stable. Furthermore, the grafted TCP was completely absorbed, and the implant body appeared to be in good condition, with no signs of bone resorption around the implant.

This narrative review aims to provide an overview of recent studies and case reports on three-dimensional (3D) printing, and to verify the applicability of 3D printers in the field of dental prostheses. This review was performed by conducting a search of PubMed. The clinical application of fabricating a prosthesis made with cobalt-chromium is considered possible depending on the material and hardware of the 3D printer. However, it is currently difficult to assess the clinical use of 3D-printed zirconia crowns. Further research is required, such as verification of materials used, margin morphology, and hardware. Clinically acceptable results have been reported for patterns using 3D printers. Interim restorations made using a 3D printer have been reported with good results that are considered clinically usable. Dentures made with 3D printers need further verification in terms of strength and deformation. Custom trays made with 3D printers are clinically useful, however, issues remain with design time and effort. Although several studies have reported the usefulness of 3D printers, further verification is required since 3D printers are still considered new technology.

Purpose To determine the effects of titanium nanoparticles, that may have been scattered after dental implant placement, on gene and promoter expression, and gingival tissue. Methods Ca9-22 cell lines were used as gingival epithelial cells to assess the effects of titanium dioxide nanomaterials as titanium nanoparticles. Cells were cocultured with or without titanium dioxide nanomaterials prior to gene and promoter expression analysis. Expression of interleukin-13α2 receptor was investigated using real-time quantitative reverse-transcription polymerase chain reaction and immunofluorescence staining. Additionally, the enhanced messenger ribonucleic acid (mRNA) expression of transforming growth factor β1 was analyzed using the same method. Results Titanium dioxide nanomaterials affected gene and promoter expression in Ca9-22 cells: among the 160 upregulated genes, the upregulation of IL13RA2, which encodes interleukin-13α2 receptor, was the highest (8.625 log2 fold change). Immunofluorescence staining confirmed the increased expression of interleukin-13α2 receptor, which enhanced transforming growth factor β1 expression by stimulation with interleukin-13. Conclusion Titanium dioxide nanomaterials applied on the gingival epithelium around the dental implant may increase interleukin-13α2 receptor expression. In turn, this can enhance the secretion of transforming growth factor β1, which is known to promote the differentiation of osteoclasts involved in bone resorption, and potentially affect gingival tissue.

Purpose The digitization of the dental field has been vigorously promoted in recent years. An impression using an intraoral scanner is considered to significantly change future dental treatment. The purpose of this review is to evaluate accuracy and practicality of various intraoral scanners and verification method of intraoral scanners. Study selection This review was based on articles searched through the MEDLINE and PubMed databases. The main keywords that were employed during the search were “Oral Scanner, Intraoral Scanners, Desktop Scanner, and Digital Impression”. Result It was reported that illuminance and color temperature affected trueness and precision of intraoral scanners. The repeatability of intraoral scanners indicated the possibility of producing fixed prostheses within the range of being partially edentulous. It is considered difficult to use intraoral scanners in fabricating cross-arch fixed prostheses. However, with intraoral scanners, it may be considered possible to fabricate mouth guards and dentures equivalent to those of desktop scanners. Current intraoral scanner scans are considered more comfortable than traditional impressions that use irreversible hydrocolloid and elastomeric impression materials. Conclusion Since the intraoral scanner is an evolving device, further improvement in accuracy is expected in the future. In addition, verification of the accuracy of intraoral scanners must be conducted accordingly.

Natural teeth are supported by connective tissue collagen fibers that insert perpendicularly in the tooth cementum. Perpendicular insertion plays an important role in the maintenance of the junction between the oral epithelium and the periodontal connective tissue. Most titanium dental implant surfaces have no micro or macro structure to support perpendicularly oriented collagen attachment. Without this tight biologic seal to resist bacterial invasion and epithelial downgrowth, progressive bone loss in peri-implantitis is seen around dental implants. The purpose of this study was to establish the perpendicularly oriented collagen attachment to titanium oxide nanotube (TNT), and to assess its binding stability. TNT was prepared on the titanium-surface by anodization. Scanning electron microscopy (SEM) showed a regularly aligned TNT with an average 67 nm-diameter when anodized at 30 V for 3 h. Subsequently, collagen type I (CoI) was electrophoretically fused to anodic TNT in native polyacrylamide gel system where negatively charged CoI-C term was perpendicularly navigated to TNT. SEM and atomic force microscopy (AFM) were used to analyze CoI on the TiO2 and TNT surface. Several tens of nanometers of CoI protrusion were recorded by AFM. These protrusions may be long enough to be priming sites for cell-secreted CoI. CoI laid parallel to the titanium surface when fused by a chemical linker. Binding resistance of CoI against drastic ultrasonication was measured by Fourier-transform infrared spectroscopy attenuated total reflection (FTIR-ATR). The electrophoretically fused CoI in the titanium nanotube (TNT–CoIEPF) showed the significantly greatest binding resistance than the other groups (P

Although the effects of neprilysin (NEP), also called CD10, on the clearance of Alzheimer's disease (AD)-associated amyloid-β (Aβ) have been reported, NEP is not made in the brain, and the mechanism for the transport of NEP to the brain has not been investigated. Our hypothesis is that muscle packages NEP in exosomes in response to a neuromuscular signal and sends it to the brain via retrograde axonal transport. The masseter muscle (MM) and the trigeminal nerve (TGN) are good candidates for this mechanism by virtue of their proximity to the brain. The aim of this study was to trace the NEP protein from the MM, through the TGN, and to the hippocampus (HPC) in muscle contraction models in vitro and in vivo. NEP expression in mouse tissue lysates was analyzed by RT-PCR and Western blot. Four-week-old mice were perfused to remove blood NEP contamination. The MM expressed substantial levels of NEP protein and mRNA. On the other hand, a remarkably high level of NEP protein was measured in the TGN in the absence of mRNA. NEP protein, without the corresponding mRNA, was also detected in the HPC. These results suggested that the MM derived NEP was taken up by the TGN, which in turn permitted NEP access to the central nervous system and within it the HPC. When the MM was induced to contract by electric stimulation in freshly euthanized mice, NEP protein decreased in the MM in a stimulus time-dependent manner, while that in the TGN and the HPC increased sequentially. Furthermore, NIR-labeled exosomes tracked along the same route. Finally, carbachol induced secretion of exosomal NEP in C2C12-derived myotube cells. These results support our hypothesis that MM-derived NEP is transported along the TGN to reach the HPC following electrical or cholinergic stimulation.

OBJECTIVES: The purpose of this study was to assess the diagnostic property of intraoral bitewing radiographs (BTW) for early stage interproximal caries, and to compare them with periapical radiographs (PA) at different levels of caries progression. METHODS: A total of 241 interproximal surfaces of BTW and corresponding PAs were used. Seven teaching faculty consisting of three oral and maxillofacial radiologists, two operative faculty, and two prosthodontists evaluated the images. The observers graded images as either “intact”, “enamel caries 1/2 width”, or “caries into dentin”. The gold-standard was established by consensus of two experienced faculty with 35 years and 27 years of experience. Specificity, sensitivity, positive-predictive value, and negative-predictive value were calculated for the different level of caries progression. Furthermore, receiver operating curves) of BTW and PAs of each evaluator were made and the area under the curve of BTW and PAs were compared. RESULTS: There was no significant difference in the specificity of BTW and PAs. BTW showed significantly higher sensitivity than PAs in all levels of caries progression (p

Epithelial attachment via the basal lamina on the tooth surface provides an important structural defence mechanism against bacterial invasion in combating periodontal disease. However, when considering dental implants, strong epithelial attachment does not exist throughout the titanium-soft tissue interface, making soft tissues more susceptible to peri-implant disease. This study introduced a novel synthetic peptide (A10) to enhance epithelial attachment. A10 was identified from a bacterial peptide display library and synthesized. A10 and protease-activated receptor 4-activating peptide (PAR4-AP, positive control) were immobilized on commercially pure titanium. The peptide-treated titanium showed high epithelial cell migration ability during incubation in platelet-rich plasma. We confirmed the development of dense and expanded BL (stained by Ln5) with pericellular junctions (stained by ZO1) on the peptide-treated titanium surface. In an adhesion assay of epithelial cells on A10-treated titanium, PAR4-AP-treated titanium, bovine root and non-treated titanium, A10-treated titanium and PAR4-AP-treated titanium showed significantly stronger adhesion than non-treated titanium. PAR4-AP-treated titanium showed significantly higher inflammatory cytokine release than non-treated titanium. There was no significant difference in inflammatory cytokine release between A10-treated and non-treated titanium. These results indicated that A10 could induce the adhesion and migration of epithelial cells with low inflammatory cytokine release. This novel peptide has a potentially useful application that could improve clinical outcomes with titanium implants and abutments by reducing or preventing peri-implant disease.

The development of new osteoconductive bone substitute materials is expected in medicine. In this study, we attempted to produce new hydroxylapatite (HAP)/collagen (Col) composites using two HAP particles of different sizes and porcine type I collagen. The two HAP particles were either nano-sized (40 nm in average diameter; n-HAP) or had macro-pore sizes of 0.5–1.0 mm in length with fully interconnected pores (m-HAP). The aim of this study was to investigate the effects of apatite particle size in two HAP/Col composites on the osteogenic differentiation profile in osteoblast-like cells (SaOS-2). We created a collagen control sponge (Col) and two HAP/Col composite sponges (n-HAP/Col and m-HAP/Col) using freeze-drying and dehydrothermal cross-linking techniques, and then punched out samples of 6 mm in diameter and 1 mm in height. The SaOS-2 cells were cultured on three test materials for 1, 2, 3 and 4 weeks. Total RNA was extracted from the cultured cells and the expression of osteogenic differentiation-related genes was evaluated by reverse transcription PCR (RT-PCR) using primer sets of alkaline phosphatase (ALP), type 1 collagen (COL1), bone sialoprotein (BSP) and osteocalcin precursor [bone gamma-carboxyglutamate (gla) protein (BGLAP)] genes, as well as the β-actin gene. The cells were also cultured on Col, n-HAP/Col and m-HAP/Col specimens for 1 and 4 weeks, and were then observed under a scanning electron microscope (SEM). The experimental results were as follows: RT-PCR indicated that osteogenic differentiation, particularly the gene expression of BSP, was most accelerated when the cells were cultured on n-HAP/Col specimens, followed by m-HAP/Col, whilst the weakest accelaeration was observed when the cells were cultured on Col specimens. As shown by the SEM images, the SaOS-2 cells were fibroblastic when cultured on Col specimens for up to 4 weeks; they were fibroblastic when cultured on n-HAP/Col specimens for 1 week, but appeared as spheroids, while actively phagocytizing n-HAP particles at 4 weeks; however, they appeared as deformed fibroblasts when cultured on m-HAP/Col specimens, detached from the particles. Despite limited experimental results, our study suggests that n-HAP/Col may be employed as a new osteoconductive bone substitute material.