The decision to apply a certain therapy is the outcome of a process in which the advantages and disadvantages of this therapy are weighed and compared to alternative therapies. Key words in this process are effectiveness and efficiency. Comparison of inlays and onlays with direct resin composite restorations in terms of effectiveness and efficiency suggests that inlays and onlays are more effective (more durable) than direct resin composite restorations. In contrast, resin composite restorations require fewer resources and thus may be more efficient. However the value of a therapy is not only determined by quantitative measures. It is suggested that appropriateness and adequacy of a therapy should be considered as well. If restorative treatment using cast partial restorations is compared with a treatment using direct resin composite restorations, the latter is considered more appropriate because of its conservative approach. Both types of restorations are considered adequate in terms of protecting the tooth and restoring its function.