The purpose of this report is to evaluate the applicability of a novel Print and Try technique in the presence of aberrant endodontic anatomies and to achieve a predictable treatment with improved outcome. According to guidelines, cone beam computed tomography (CBCT) is recommended in the presence of complex anatomies. The volumes were utilized to produce a stereo lithographic (STL) file, from which a 3D-plastic tooth model including a hollow root canal system was obtained. The 3D-patient-specific model facilitates the treatment planning and the trial of therapeutic approaches. Using a transparent material, all the treatment steps could be directly visualized. Subsequently, endodontic therapy could be performed in vivo with reduced operating time and with a better overview. Clinicians benefit from the Print and Try technique when facing a complicated root canal system with reduced stress and higher chances of success. In aberrant endodontic anatomies, the use of a transparent 3D plastic model, derived from the CBCT dicom, provides an exact preview of clinical challenges that will be met intra-operatively. A patient centered tailored approach to shaping, cleaning, and filling strategies can be applied.

BACKGROUND: There is currently no consensus on the optimal post system to provide effective long-term results. We used an engineering approach to investigate the mechanical properties of a sandwich hollow carbon fiber post in synergy with a new bonding technique. METHODS: We studied two systems-a sandwich fiber hollow post (Techole ® , Isasan, Como, Italy) composed of carbon fiber incorporated in a Dpp-MOR resin mix and a traditional non-hollow post (Tech 2000 ® , Isasan, Como, Italy). A bi-component composite (Clearfil Core ® , Kuraray, New York, NY, USA) (2.2 gcm 3 , 12.3 GPa) and a dual cure composite with lower density and modulus of elasticity (Clearfil DC Core ® , Kuraray, New York, NY, USA) (2.0 gcm 3 , 10.0 GPa) were also used into hollow posts. Results from three-point bending test (N.=81), compression test (N.=78) and cut test (N.=81) were achieved. RESULTS: In the three-point bending test there were significant differences in flexibility/bending when sandwich fiber hollow posts were filled with composite of different modulus of elasticity. Hollow sandwich posts showed also significant (P=0.000) better resistance to compression and cutting than solid posts, independently of the type of composite. Moreover, hollow posts filled plus composite with a modulus of elasticity of 12.3 GPa showed significant (P=0.000) improved resistance parameters rather than hollow posts filled with a composite of 10.0 GPa. CONCLUSIONS: The study confirms the favorable mechanical properties of the hollow sandwich fiber post system (Techole ®) and the synergistic efficacy when used in combination with the composite Clearfil DC Core ® (10.0 GPa) and, especially, Clearfil Core ® (12.3 GPa).

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