its appearance, which can help the patient accept the final profile. Provisional restorations are designed to be used for a few weeks to months, they can be fabricated directly (by chair side), or indirectly ( in the dental laboratory). It is usually tried in a few times to check if it fits properly and if its margins are well adapting on the teeth surface and gingiva, it may need relining or a few adjustments. Provisional bridges can either be made of acrylic resins or metal. The resins are the most commonly used, they are either made of cellulose acetate, polycarbonate or poly-methyl methacrylate. Other chemically activated resins include poly-R methacrylates: these are methacrylates with ethyl or isobutyl substances added to increase the strength of material. Also, commonly used resins include the BisGMA based dimethacrylate, and the visible light urethane di-methylacrylate. Dimethacrylate-based materials were found to be better than monomethacrylates for temporary restorations in terms of flexural strength and hardness. Types of bridges according to material Metal based, noble based metals such as gold, or base metal alloys such as nickel chromium. Non-metal based. They can be either resin veneered, fibre-reinforced composite, porcelain fused to metal, or ceramics which are either silica, alumina, or zirconia. Acrylic resin and porcelain fused to metal (PFM) Acrylic resin was the first veneering material used to help restore the aesthetics of crown and bridges, the aim was to maintain a similar colour to natural teeth by attaching it on the labial surface of metal crown / bridges, however, resin veneered dental prosthetics lacked stability and abrasion resistance. Porcelain fused to metal (PFM) was then introduced; the porcelain is composed of two layers (one opaque to cover the metal substructure and another translucent to provide an enamel illusion). Still several researchers consider PFM the gold standard as it has been reported to have 95% success over a 10-year period, a reason why newer types of all-ceramic restorations are usually compared to PFM crowns / bridges to assess its success and durability. However, PFM restorations may show a grey colour at the cervical margins of the tooth showing the metal substructure. IPs Emax IPs Emax ceramics offer high aesthetic properties, that's why its use has been increasingly popular, however, there's insufficient evidence to determine the longevity of Emax in bridges; some reports found fair short-term survival, but unfavorable medium-term survival. Failures of restorations were most reported in