Technological advancements have made our lives more convenient and efficient. Digital dentistry has been and continues to improve the way dental treatment procedures are being conducted. Fabricating post-and-core is among the routine treatment procedures in the dental office. Formally, digitizing this procedure has been limited to scanning the traditional impressions, or the stone models obtained from them, which would transfer the traditional impression shortcomings to the resulted posts.[13-16] Scanning the post space directly would eliminate the fabrication of the resin pattern in the conventional technique and improve the accuracy of the post, conserve time, be more cost-effective, and overcome the disadvantages of casting. Fortunately, intraoral scanners have improved their capability to directly scan post space within the tooth. This enabled the full digitization of the custom post fabrication workflow as reported in recent studies.[10, 11, 17-20] Till now, however, the use of the hybrid ceramic for the fabrication of one-piece post-and-core in full digital workflow has not been reported.
The ideal material for posts has for a long time been gold due to its low modulus of elasticity among other properties.[21] However, gold is expensive and not esthetic which limited its use. Fiberglass-reinforced post rapidly became widely used even though, however, they do not fit as good as the custom-made posts and have an additional adhesive interface between the dissimilar post and core materials[13]. Custom one-piece lithium disilicate or zirconium dioxide ceramic posts is gaining popularity, despite the clear ceramic limitation of being too stiff.[22, 23]
The recent introduction of the hybrid ceramic Enamic®, which combines the benefits of both glass ceramic and composite resin, resulted in a ceramic with lower modulus of elasticity[24, 25]. This made Enamic a very promising ceramic material of choice to be used for the posts application which requires somewhat flexible material to be compatible with the natural tooth elasticity[26, 27]. This hybrid ceramic can only be fabricated with CAD/CAM. Thus, utilizing the intraoral scanner and the Enamic ceramic can result in fabricating a preferable custom ceramic one-piece post in a full digital workflow using a material that better suites the post application.
Even though the intraoral scanner is set up to be able to scan post spaces, no guidelines is available for such a process. Thus, we had to examine the limitations of the scanner. Not surprisingly, the limitations found in this study were very close to those found in recent studies which used different scanners for similar applications in regard to the limited depth of 10 mm which the scanner can reach[11]. Another obstacle has been faced with the CAD software, which is not set up to design post-and-core. This was worked around with manually manipulating the design (Fig. 3).
This study has also analyzed the cost effectiveness of fabricating the custom ceramic posts using two different techniques. The fully digital technique clearly saved time by reducing the laboratory support for pouring the impressions and waxing up the pattern and then casting it and the cost associated with this. Further, the digital technique does not require lots of clinical and laboratory consumable materials, such as the impression materials.
Finally, the visual analysis of the fitting of the post made with the fully digital technique clearly showed almost identical results to the conventionally made one (Fig. 4), proving the safety and effectiveness of the full digital workflow. Combining the full digital method with the use of Enamic which is more suited to fabricate a custom one-piece ceramic post, opens up possibility to advance custom ceramic post fabrication with the latest technology and materials.