Progress and Issues Related to Designing and 3D Printing of Endodontic Guide

Abstract

In the case of calcified pulp canal, a customized guide is used for the formation of access cavity to remove the infected pulp from pulp chamber; this guided approach of treatment is known as guided endodontic. The accuracy of guided endodontic treatment depends on design and fabrication of the guide. Guide path and support structure are the two essential part of the endodontic guide. The guide path is a hole of specific orientation and diameter, responsible for the orientation of file to follow the pre-decided drilling path during treatment while the support structure of guide will provide grip and placement on the teeth. If there is some deviation between the reference point of guide and teeth, then it will be the cause of the surgical error. So the intent is to fabricate optimally oriented guide path with the detailed negative impression of the tooth crown on the guide, which will be able to perfectly grip and place on the teeth. Cone beam computed tomography (CBCT) of the patient face is used to get anatomical details of the tooth to decide the orientation of guide path. Similarly, the architectural details of teeth captured by intraoral surface scan (SS) data are used to design support structure of guide. CBCT and intraoral SS data are merged to get the combined detail of teeth anatomy and architecture. This combined dataset exported from computational software (CAD software package) to design the endodontic guide. After that the STL model of the designed guide will send for fabrication on additive manufacturing (AM) machine. The endodontic guide comprises of freeform surfaces, negative impression of teeth, and guide path, so it is utterly essential to retain these features after fabrication. However, AM is the prevalent technology for fabrication of customized parts, but due to induced volumetric error, feature loss will occur which may lead drill path deviation and treatment failure. If guide designs for additive manufacturing by keeping some factors (triangulation, slicing, build orientation, nozzle/laser velocity) in mind, then feature loss can easily be controlled. The design and fabrication issues for additive manufacturing of endodontic guide along with the recent developments in guided endodontic discussed in this article.