The overall aim of this thesis was to study the following aspects ofdirect and indirect coronal restoration, primarily of root-filled teeth, withspecial reference to:• periapical health• the natural course of root-filled teeth, particularly furtherclinical intervention• the dentist´s decision-making process for root-filled teeth.The aims of coronal restoration are to restore the function and aestheticsof the tooth, with a tight marginal seal as protection from microbialleakage. A coronal restoration may be either direct, i.e. a direct chairsidecomposite or amalgam filling, or indirect, whereby the restoration,ceramic or a combination of metal and ceramic, is fabricated in alaboratory and then permanently cemented. For the root-filled tooth, acoronal restoration of adequate quality is an important factor for asuccessful outcome of the endodontic treatment, in terms of periapicalstatus. While indirect restoration is often advocated as the treatment of choice for a root-filled tooth, the procedure is nevertheless more timeconsumingand 3 – 4 times more expensive than a direct restoration. InSweden, composite is the predominant material for direct restorationand the majority of root-filled teeth are directly restored. However,some reports suggest an association between composite restoration andan increased risk of periapical disease. In terms of tooth survival, thereare also reports of less favorable endodontic treatment outcomes forteeth with direct restorations than for those with indirect restorations.In Studies I and II clinical and radiographic examinations wereundertaken in a random sample of 440 subjects, living in the county of Skåne, Sweden. No association was disclosed between apicalperiodontitis (AP) and direct composite restorations. In non root-filledteeth, a relationship was found between the type of restoration and AP.Those restored with direct restoration by both composite and amalgamcombined, and indirect restoration were associated with increased riskof AP, indicating that the extent of tooth substance removal rather thanthe type or material of the restoration, was an important factor ofinfluence on periapical status. For root-filled teeth, however, the qualityof the restoration and of the root-filling was more important toperiapical health than the type or material used for the coronalrestoration. In Study III, data from the Swedish Social InsuranceAgency on dental treatments were analyzed. Only minor differences inthe frequency of additional endodontic treatment for root-filled teethrestored with direct versus indirect restoration was disclosed. Theindirectly restored teeth also had a more favorable natural course duringthe 5-year follow-up period. In comparison, teeth restored with directrestorations required further clinical intervention (nonsurgical retreatment, extraction and additional restorations) significantly morefrequently.In Study IV, in-depth semi-structured interviews were conducted withgeneral dental practitioners. Data from 14 interviews were analyzed byQualitative Content Analysis. Study IV revealed that dentists´ decisionmakingprocess underlying the choice of coronal restoration for a rootfilledtooth, was based not only on clinical factors; contextual factorsand patient´s views, if in conflict, were decisive. Thus, despite theindications for an indirect restoration, a direct restoration wasoccasionally chosen. Accordingly, the context in which the dentistmakes decisions may be a factor influencing the fate of the root-filledtooth.It is concluded that concerns that composite restoration poses a riskfor periapical disease are not supported clinically, i.e. the use ofcomposite seems to be safe. While in non root-filled teeth, AP tended tobe associated with extensive restorations, in root-filled teeth the type ofrestoration was not an important factor of periapical health. For teethdirectly restored after root canal treatment, further clinical interventionsmay be expected, especially for restorative failures. This may beattributable in part to the dentist´s decision-making process with respectto the choice of coronal restoration.