Osseointegration is a good indication of the clinical success of titanium implants referring to the direct anchorage of such implants to the surrounding host bone. Despite the high success rate of endosseous dental implants, they do fail. A lack of primary stability, surgical trauma, and infection seem to be the most important causes of early implant failure. Early signs of infection may be an indication of a much more critical result than if the same complications occur later, because of disturbance of the primary bone healing process. Occlusal overload and periimplantitis seem to be the most important factors associated with late failure. Suboptimal implant design and improper prosthetic constructions are among those risk factors responsible for implant complications and failure. This concise review highlights the main causes associated with early and late implant failure, as thorough knowledge of this unavoidable clinical fact is essential in the field of oral implantology.

INTRODUCTIONThe early 1990s hallmarked the use of composite materials in dentistry. The initial composites were usually quartz-filled with large filler particles, making restorations rough and difficult to polish. With polish ability being a major aesthetic concern, a variety of newer materials have emerged in response to the ever growing needs expressed by dental practitioners. Composite resins derive their physical properties/handling characteristics from the reinforcing filler particles and viscosity from the resin matrix. A majority of direct restorative composite resins fall into one of the following categories: hybrid, nano-filled, microfill, packable and flowable composites [1].The purpose of increasing the filler load is to improve the resistance to functional wear and physical properties. Viscosity increases with increase in filler loading. Most direct restorative composite have a putty like consistency which is desirable for clinical situations but there is a need to have a less viscous composite resin for better adaptability with the cavity wall. For this reason, a new class of "flowable composite resins" was introduced in late 1996 [2].Flowable resin-based composites are conventional composites with the filler loading reduced to 37%-53% (volume) compared to 50%-70% (volume) for conventional minifilled hybrids. This altered filler loading modifies the viscosity of these materials. Most manufacturers package flowable composites in small syringes that allow for easy dispensing with very small gauge needles. This makes them ideal for use in small preparations that would be difficult to fill otherwise [3].Most literature discusses conventional composite materials at large, giving minimal emphasis to flowables in particular. The sole objective of this paper was to exclusively review the most salient features of flowable composite materials and to give clinicians a detailed insight to the advantages, drawbacks, indications and contraindications based on composition and physical/mechanical properties. Clinicians are able to correlate this knowledge during case selection, manipulation and placement for better longevity of restorations.

Purpose. The aim of this review is to summarize and evaluate the relevant literature regarding the different ways how polyetheretherketone (PEEK) can be modified to overcome its limited bioactivity, and thereby making it suitable as a dental implant material. Study Selection. An electronic literature search was conducted via the PubMed and Google Scholar databases using the keywords “PEEK dental implants,” “nano,” “osseointegration,” “surface treatment,” and “modification.” A total of 16 in vivo and in vitro studies were found suitable to be included in this review. Results. There are many viable methods to increase the bioactivity of PEEK. Most methods focus on increasing the surface roughness, increasing the hydrophilicity and coating osseoconductive materials. Conclusion. There are many ways in which PEEK can be modified at a nanometer level to overcome its limited bioactivity. Melt-blending with bioactive nanoparticles can be used to produce bioactive nanocomposites, while spin-coating, gas plasma etching, electron beam, and plasma-ion immersion implantation can be used to modify the surface of PEEK implants in order to make them more bioactive. However, more animal studies are needed before these implants can be deemed suitable to be used as dental implants.

Flowable resin-composites vary widely in shrinkage-strain magnitude and the inverse relationship between filler percent and shrinkage-strain is explained by the corresponding decrease in volume fraction of monomers present to undergo polymerisation.