Construction of functional surfaces for dental implants to enhance osseointegration.

Dental implants have been extensively used in patients with defects or loss of dentition. However, the loss or failure of dental implants is still a critical problem in clinic. Therefore, many methods have been designed to enhance the osseointegration between the implants and native bone. Herein, the challenge and healing process of dental implant operation will be briefly introduced. Then, various surface modification methods and emerging biomaterials used to tune the properties of dental implants will be summarized comprehensively.

Managing the Gate Assignment Problem in the Hub Airport with Satellite Halls: A Transfer Demand-Oriented Approach.

This study focuses on managing the gate assignment in the hub airport with both main terminal and satellite halls. We first formulate the gate assignment problem (GAP) as a binary linear programming model with multi-objective functions, where the practical constraints, e.g., gate time conflict and gate compatibility, are considered. Then, we incorporate the impact of gate assignment on transfer passengers and formulate the transfer demand-oriented gate assignment problem (TGAP) as a nonlinear model. A linearization approach and a heuristic approach are designed to solve the TGAP model. A case study is conducted based on the practical data of the Shanghai Pudong International Airport, where a comparison between the results of GAP and TGAP by the two proposed approaches is demonstrated. It shows that the proposed TGAP model and solution approaches can not only enhance the service for transfer passengers but also improve the gate utilization efficiency in the hub airport.

Settling effect of abutment and torque loss in different types of abutment after cyclic loading.

OBJECTIVES: This study aimed to evaluate and compare the settling effect of implant-abutment assembly and the torque loss before and after cyclic loading in three types of abutments. METHODS: Thirty internal hexagon fixtures were randomly divided into three groups (n=10). Group A used original abutments, group B used pre-machined cast abutments, and group C used compatible abutments. In addition, the abutment morse taper angle was measured using an image measuring instrument. Removal torque values (RTVs) were recorded using a digital torque meter before and after cyclic loading. All samples were tested in a universal testing machine with a vertical load between 0 and 250 N for 100 000 cycles of 10 Hz. The settling effect was measured after cyclic loading. Paired t test was performed for intragroup analysis of removal torque loss before and after cycling and one-way ANOVA. Subsequently, Tukey's honestly significant difference test was used for intergroup comparison (α=0.05). RESULTS: The paired t-test showed signi⁃ficant differences in the intragroup RTVs before and after cycling (P<0.001). ANOVA showed significant differences in the mean of removal torque loss after cycling (P=0.009), the abutment morse taper angle (P<0.001), and the settling values (P=0.01) among different groups. However, no significant difference was found between compatible abutments and pre-machined cast abutments. CONCLUSIONS: The screw removal torque was significantly reduced for all groups in this study after cyclic loading. Differences could be found in the internal accuracy of implant-abutment assembly among different groups. Within the limitations of this study, the results showed the original abutments exhibited lower percentages of torque reduction after cyclic loading than the casting abutments and the compatible abutments.

Silver Nanoparticles Coated Poly(L-Lactide) Electrospun Membrane for Implant Associated Infections Prevention.

Bacterial infection has been a critic problem for implant infections. Poly(L-lactide) (PLLA) membrane has great potential for Guided bone regeneration (GBR), however, PLLA lack antibacterial property and thus may face bacterial infections. In this work, a mussel inspired method was used to treat PLLA membrane with dopamine and formed polydopamine (PDA) coated PLLA (PLLA@PDA), and then silver Nanoparticles (AgNPs) was immobilized on the surface of PLLA via the reduction effect of PDA. The XPS results showed that the silver element contents may be tuned from 1.6% to 15.4%. The AgNPs coated PLLA (PLLA@Ag) showed good antibacterial property (98.3% bactericidal efficiency may be obtained) and good biocompatibility, implying that the PLLA@Ag membrane have potential application as antibacterial GBR membrane, which may enhance the application of PLLA.

Antibacterial Properties of Bilayer Biomimetic Nano-ZnO for Dental Implants.

Dental implant surgery has a relatively high incidence of peri-implantitis. In this research, ZnO nanorods and ZnO nanospheres were synthesized by a hydrothermal method. ZnO nanorods first covered the surface of Ti or Ti-Zr, and ZnO nanospheres were then modified as the outermost layer. By these means a dual antibacterial effect could be realized by the rapid release of ZnO nanospheres and the sustained release of ZnO nanorods. Subsequent studies implied that this ZnO nanorods-nanospheres hierarchical structure (NRS) could be stably loaded on the surface of roughened Ti and Ti-Zr slices. The modified materials not only showed excellent antibacterial activities against both Escherichia coli and Staphylococcus aureus but also showed low cellular cytotoxicity. This ZnO NRS structure is thus expected to be used as a general antimicrobial coating on the surface of Ti (Ti-Zr) in dental implant surgery.

L-cysteine modified ZnO: Small change while great progress.

ZnO as an important nanomaterial have been widely used in biomedical fields, however, ZnO has noticeable damage to the organs such as lung and liver, from the long run, its biosafety still needs improvements. In this work, we proposed a simple method to modify the surface of ZnO with l-cysteine. The basic characterizations showed that the surface modification can greatly affect its self-assembly and optical properties. Furthermore, the surface modification can greatly improve its biocompatibility and without change of its bulk antibacterial properties. Moreover, compared with ZnO, the l-cysteine modified ZnO showed much better biosafety in the in vivo test, demonstrating that the modified ZnO may have perspective applications in biomedical fields.

Construction of Antibacterial Surface Via Layer-by-Layer Method.

Construction of antibacterial surfaces or films is of great interest in various fields including biomedicine, food, agriculture and so on. So far, a number of antibacterial agents have been used to construct antibacterial surfaces. Layer-by-Layer (LbL) assembly is a simple and versatile deposition process for fabricating multilayer thin films with great advantages to control the architecture and composition of the films. In this review, we give a brief introduction of LbL, and different materials used to fabricate antibacterial surfaces with LbL assembly approach are described as well as their drawbacks. Much attention is also paid to the recent development of multifunctional and intelligent antibacterial surfaces. Moreover, the advantages and limitations of these different types of antibacterial materials are summarized and subsequently directions for future development are proposed.

[Assessment research on the inter-proximal mesial papilla height of single implant-supported maxillary central incisor].

OBJECTIVE: This prospective study was to observe the correlation between the mesial papilla's height of single implant-supported maxillary central incisor and the distance from the base of the contact point to the alveolar bone crest. METHODS: 56 patients involved in single implant-supported maxillary central incisor were included in this study. The distances from the base of the contact point to the alveolar bone crest in the digital periapical film of maxillary central incisor were measured using the software Planmeca Dimaxis Version 3.3.2. The time of measurements were as follows: The pre-surgical and post-surgical periods, before and after the crown installation, the follow-up examination of more than 0.5 year. To analyze the factor of influencing distance, and the correlation between the distance and the height of gingival papilla during the whole restored period. Correlation analysis between the distance and the height of gingival papilla during the whole restoration was done by the statistical software SPSS 12.0. RESULTS: The results demonstrated that the ratio of esthetic papilla can achieve 54.5% at the crown installation and 95.5% at the follow-up examination when the distance was between 3 mm and 5 mm. When the distance was between 5 mm and 6 mm, they dropped to 30.0% and 75.0%, respectively. However, when the distance increased to above 7 mm, the papilla could hardly be in an esthetic outcome. There was a significant change of the distance was found during the periods from the post-surgery to pre-restoration, and the scope of the changes was between -0.13 mm and 0.46 mm. A negative correlation was found between the distance and the index of papilla. The correlation coefficient r was -0.715 (P < 0.01). CONCLUSION: It is proposed that the pre-surgery distance of maxillary central incisor from the base of the contact point to the alveolar bone crest can be used as one of the important reference indexes to assess and predict the height conditions of gingival papilla.