damage to the nerve supply of a vital tooth. The tooth has not fully erupted and continued active and passive eruption can cause unfavourable margins when the tooth is fully through as the patient is still undergoing skeletal development. Young children may be unable to cope with invasive dental treatment and long procedures, therefore it is advantageous to wait until they are fully cooperative. Unable to tolerate impression taking Patients need to be able to cope with dental impressions as these are required for the fabrication of the indirect restoration. Development of digital impression systems including Lava Chairside oral scanner by 3M, Sirona's CEREC and Cadent iTero System could help patients receive treatment if the contraindication is being unable to withstand conventional impressions. Digital impressions enable production of highly accurate models whilst eliminating patient discomfort. However, these systems are not widely available in dental practices, as of 2018. Alternatives If a tooth has extensive caries or tooth surface loss which would provide difficulty bonding an inlay or onlay then it might be more appropriate to consider a full coverage extra coronal restoration. This can protect remaining tooth structure. Direct restorations, for example composite may be beneficial when restorations are small. Inlays require elimination of undercuts, therefore direct restorations may preserve tooth structure whilst also avoiding unwanted laboratory costs. Preparation for inlays and onlays The preparation of inlays and onlays mainly follows the same basic concepts of indirect restorations. The aim of tooth preparation is to preserve more tooth tissue compared to a crown preparation, while giving an adequate amount of protection to the tooth. The preparation of opposing cavity walls should be cut in a way to avoid undercuts in order to gain optimum retention from the cavity shape for the indirect restoration. For inlay and onlay preparations that are going to be completed with all-ceramic then these cavity shapes can be slightly over-tapered as most of the retention is gained from the cement lute. However, for indirect restorations using gold then the preparation shape must have parallel walls as most of the retention is gained from the cavity shape. The process of preparation and cementation of an inlay or onlay is usually carried out over two appointments, with the preparation being carried out during the first appointment and cementation at the second. After the tooth has been prepared at the first visit a putty and wash impression should be