A Theoretical Iteration for Predicting the Feasibility for Immediate Functional Dental Implant Loading.

When planning an implant-supported restoration, the dentist is faced with surgical and prosthetic technical issues as well as the patient's expectations. Many patients wish an immediate solution to an edentulous condition. This may be especially true in the esthetic zone, and that zone is determined by the patient. The dentist may consider when it is feasible to load the supporting implants with definitive or provisional prosthetics. In this work, many parameters were theoretically assessed for inclusion: bone density, cortical thickness, insertion torque, parafunction, bite load capacity, number of implants under load, implant/crown ratio, implant diameter, and length. After assessment, the most influential parameters were selected. An iteration, using patient age, implant diameter, bite load capacity, and cortical thickness, is now presented to aid the implant dentist in determining the feasibility for immediate functional loading of a just-placed dental implant in a healed site. Extensive testing is required to develop this concept. According to this iteration, most immediate functional loaded implants would fail. A future refined and definitive formula may enable the clinician to safely and immediately functionally load an implant with a definitive prosthesis. For access to the applet, please go to https://implantloading.shinyapps.io/shiny_app/.

Polymer stiffness governs template mediated self-assembly of liposome-like nanoparticles: simulation, theory and experiment.

This study suggests that the self-assembly of a template-mediated liposome (TML) can be utilized as a general method to produce liposomes with controlled sizes. A polymer tethered core is used here as a starting configuration of a TML. Lipids anchored to the free ends of the tethered polymers direct the self-assembly of surrounding free lipid molecules to form liposome-like nanoparticles. Characterizing the flexibility of polymers by their persistence lengths, we performed large scale molecular simulations to investigate the self-assembly process of TMLs with tethered polymers of different stiffness values. The stiffness of tethered polymer is found to play a crucial role in the self-assembly process of TMLs. The flexible and rigid-like polymers can accelerate and delay the self-assembly of TMLs, respectively. In addition, the critical grafting of tethered polymers and required lipid concentrations to from perfectly encapsulated TMLs are found to increase with the flexibility of tethered polymers. To scrutinize these simulation-based findings, we synthesized DNA-polyethylene glycol (PEG) TMLs and performed corresponding experiments. To this end we incorporate increasing concentrations of DNA as a proxy for increasing the rigidity of the tethered polymers. We find that the resulting structures are indeed consistent with the simulated ones. Finally, a theory is developed that allows one to estimate the required free lipid number (or lipid concentration) and grafting density analytically for polymers of a given persistence length. Through these combined computational, experimental, and theoretical studies, we present a predictive model for determining the effect of polymer stiffness on the self-assembly of TMLs, which can be used as a general approach for obtaining perfectly encapsulated TMLs as potential drug delivery vehicles.