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**Accuracy and Feasibility of a Zero-Setup Implant Guide System Made of a Light-Cured Composite Resin with Simultaneous Flapless Sinus Augmentation: A Pilot Study**  
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To compensate for this, various surgical templates have been developed and widely used, which are prefabricated according to a virtual plan devised from computer software using the superimposed data of cone-beam computed tomography (CBCT) and intraoral scanning [5]. These surgical templates can be conveniently fabricated using a 3D printer. The clinical use of the fully-guided surgical templates has many benefits. Apart from the obvious accuracy of implant placement [6], dangerous anatomical structures can be evaded, and an immediate provisional restoration can be delivered [7; 8]. Furthermore, a previous study has revealed that the use of a fully-guided surgical template can improve the patient-reported outcome measurements and allow less experienced surgeons to place implants accurately [9; 10]. However, there is still room for improvement for the existing guide systems. For instance, the guide fabrication process can be time-consuming due to the transfer of data between facilities, and the various steps in the process may create an amplification of errors that may become significant [6].  
Recently, a novel, fully-guided surgical template has been proposed, namely the VARO Guide(r). A unique intraoral device called the \"pre-guide\" is used to create the VARO guide, which is a preliminary version of the surgical template. The pre-guide looks like a single-sextant bite impression tray and contains light-curable composite resin. The impression of the edentulous sextant is taken with the pre-guide by the curing of the resin, and then CBCT is taken with the pre-guide in situ. The drilling hole locations within the pre-guide are virtually planned on the CBCT imaging. This data is sent to a milling machine that fabricates the fully-guided surgical template from the pre-guide. In summary, the current system can be made inside a single facility (in-house), does not involve a model, be it conventional or digital (model-free), and requires just a milling machine and no laboratory work or a 3D printer (zero-setup). In our previous in vitro study using the VARO guide, a similar placement accuracy was shown compared to a conventional 3D-printed surgical guide; however, the preparation time was much shorter [11]. Now, there is a need to verify the feasibility and accuracy of the VARO guide clinically. In addition, there are only a few studies that have evaluated the accuracy of fully-guided implant placement in the atrophic alveolar ridge [6]. The VARO guide is compatible with a crestal sinus grafting kit that utilizes hydraulic pressure to lift the sinus membrane, which can help to reduce surgical difficulty.  
The aim of the present pilot study was to evaluate the accuracy and feasibility of implant placement in the vertically atrophic posterior maxilla using the VARO guide, performed simultaneously with flapless crestal sinus augmentation.