of bleeding and gingival inflammation at the time of fitting definitive restoration; Maintain occlusal and approximal contacts therefore preventing over-eruption, rotation and closing of spaces; Aesthetic reasons; Temporary crowns can also play a diagnostic role in treatment planning where there is a need for occlusal, aesthetic or periodontal changes. Types of temporary crowns Temporary crowns can be described by: The expected or planned duration of temporisation: Short term Medium term Long term The way or the place the temporary restoration is made: Direct or chair-side Indirect or laboratory-made The aesthetics or look of the material of construction Metal Cast Preformed Tooth coloured Plastic pre-formed (e.g. polycarboxylate and acrylic) Resin composites Duration of temporisation Temporary crowns can be described as short-term, if used for a few days, medium-term, if their planned use for several weeks and long-term if their planned use is for several months. The choice in length of temporisation often relates to the complexity of restorative work planned. Short-term temporary crowns are generally appropriate for simple restorative cases whilst complex cases involving more than one tooth often require long-term temporary crowns. Direct vs. indirect restorations Temporary crowns can either be direct, if constructed by the dentist in the clinic, or indirect if they are made off-site, usually in a dental laboratory. Generally direct temporary crowns tend to be for short-term use. Where medium-term or long-term temporisation is required, the use of indirect temporary crowns should be considered. Temporary crown materials There are several materials that can be used to construct temporary crowns. Direct temporary crowns are either made using metal or plastic pre-formed crowns, chemically-cured or light-cured resins or resin composites. Indirect restorations are either made of chemically-cured acrylic, heat-cured acrylic or cast in metal. Cementation of temporary crowns The purpose of temporary luting agents is to fill the space between the crown preparation and the temporary restoration. Unlike cementation of definitive crowns, temporary crowns should be relatively easy to remove. Adhesive cements should not be used and softer cements are preferred to allow for the easy removal of both temporary cements and crowns. This is crucial as remnants of temporary cement left on the tooth surface can compromise gingival health and interfere with accurate seating of the final restoration and permanent cement attachment. Provisional cements should also be strong enough to avoid being deformed or fractured during the provisional period. Zinc Oxide Eugenol (ZOE) temporary luting cements These