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During the last five decades, the capability to engineer or repair new functional tissues by using porous and monolithic ceramics has been a very effective approach to improve the quality of life of patients. Although the use of natural and synthetic materials in body reconstruction and repair goes back to pre-historic times their use have been accelerated considerable during the last few decades in both scientific research and clinical applications. Over the years, many questions concerning their interactions with both hard and soft tissues have been answered with multidisciplinary teams of surgeons, scientists, and engineers. Since 1970s monolithic ceramics such as alumina and partially stabilized zirconia, silicon nitride and sialon ceramics have been used and investigated clinically. Ceramics can be both inert and modified to be bioactive, they have good wettability hence ideal for lubrication under articulating conditions and they have high wear resistance. Although pure zirconia or PSZ is not currently used commercially, alumina and mixtures and their composites with zirconia have been clinically applied widely. In addition a number of clinical glasses such as Bioglass® and other similar compositions are being also used for bone augmentation and restoration in orthopedic, dental and maxillofacial surgery. They have proved to be efficient and effective and in some instances even much better than current metal prostheses. Calcium phosphates, although arguably most important bioceramic in most cases, is used in porous form and it is not covered in this article which was aimed to be on monolithic bioceramics. It is our aim in this article to present the development of these important monolithic bioceramics focusing on the history, synthesis, properties and the current development in clinical applications.

This paper revisits two conventional beliefs of environmental nonmarket valuation and examines their weaknesses and a new opportunity. The two beliefs are that willingness to pay (WTP) is an appropriate measure of non-market behaviour and that exogenous variables are relevant predictors of WTP whilst endogenous variables are not. The contemporary literature in psychology and economics is reviewed to demonstrate departures from these two beliefs.