Intraradicular diameter, remnant dentin thickness, and endodontic post-to-dentin distanc: An investigation using CBCT and microscopy

The objective of this work was to measure the tooth root canals’ diameter, remnant dentin thickness, and the endodontic post-to-dentin distance after three types of root canal preparation. Thirty extracted human premolars were endodontically treated and groups of specimens were divided according to the cementation with two different endodontic post as follow: A) Fibio Fiberglass Post™, Anthogyr, France; B) multi-filament GFRC (Rebilda GT™, VOCO, Germany). Cone beam computed tomography (CBCT) and conventional x-ray analyses were performed before and after the endodontic post cementation. After cementation, specimens were cross-sectioned and inspected by optical microscopy and scanning electron microscopy at magnification from x30 up to x2000. The shape variation of the root canal preparation caused a decrease in the thickness of the remnant tooth tissues. CBCT and microscopic analyses also revealed a clear variation of resin-matrix cement around all the endodontic GFRC posts. A multi-filament GFRC post provided a distribution of filaments although the resin-matrix cement revealed a high volume among the filaments. An increase in thickness and volume of resin-matrix cement was noticed at the coronal third since the fitting was compromised due to anatomic variations and root canal preparation. Defects such macro-scale pores, cracks, and voids were also detected by microscopic analyses. The root canal preparation can promote a decrease in the thickness of the remnant tooth tissues that can increase the risks of clinical failures by fracture. The thickness and volume of resin-matrix cement varied around both GFRC posts. Additionally, that increased from the apex up to the coronal third due to the lack of fitting. Clinical significance The root canal preparation of teeth is the first step the fitting of glass fiber-reinforced composite (GFRC) post. However, the tooth tissues must be preserved to maintain the mechanical integrity of the restored tooth. An adequate fitting of the GFRC post along the intracanal regions can promote a well-distribution of the resin-matrix cement volume that decreases the risks of defects such as voids and cracks.