Introduction
Endodontic access cavity preparation is one of the most important phases of nonsurgical root canal treatment that facilitates all subsequent phases making it the key to successful treatment (1). The principles of endodontic access cavity preparation were outlined by Ingle, based on the principles of cavity preparation established by G.V. Black (2). Inadvertently, endodontic access cavity preparation may results in weakening of the remaining tooth structure as a result of loss of strategic internal architecture of the tooth at the marginal ridges and the center of teeth due to de-roofing of the pulp chamber. Also, may results in cuspal deflection at the tooth cervix during occlusal function (3 - 4,5).
The choice of an optimal restorative method for endodontically treated teeth is still a major challenge. Different treatment modalities for such teeth ranges from a relatively direct restoration with or without intraradicular post to more complex indirect restorations, including inlay and onlay up to full coverage crowns (6).
With the advancement of new technology such as dental operating microscope (DOM), Cone beam computed tomography (CBCT) and ultrasonics in endodontics, several trials have been done to achieve smaller and more conservative access cavities (7 -,8,9).
With regard to conservation of tooth structure, different conservative endodontic access cavity designs such as contracted, truss and ninja access cavity preparation were described. These cavity designs aimed to minimize tooth structure removal and to improve fracture resistance of endodontically treated teeth by preservation of the pulp chamber roof and pericervical dentin (10,11).

Moreover, an artificial truss restoration was described as an alternative treatment modalities by pinning a horizontal glass fiber post within the coronal tooth structure in bucco-lingual direction (12).
Till now, very little research have been done to evaluate the fracture resistance of restored endodontically treated teeth with either truss access or artificial truss restorations.