ABSTRACT
@#Conservative endodontic access cavity (CEC) is the first step of minimally invasive endodontics. After that operation, teeth retain the dental hard tissue, such as crest and peri-cervical dentin, to a large extent. It is of great significance to reduce the tissue excision and achieve a favorable prognosis. There are a variety of approaches and corresponding cavities in CEC. The methods to determine the medullary approach include X-ray localization, micro CT/cone beam CT localization and digital guide plate localization. Among them, X-ray film and micro CT/cone beam CT are simple and commonly used in the clinic. For more complex root canal systems, the use of a digital guide plate can establish a more accurate pulp opening pathway and reduce the unnecessary loss of tooth hard tissue. However, the positioning price of a digital guide plate is high, and it has not been widely used in the clinic. The hole types of CEC include minimally invasive medullary hole type, super conservative minimally invasive medullary hole type, "Truss" hole type and cutting end hole type. The stress analysis of CEC and traditional endodontic access (TEC) cavity are mainly based on the loading of teeth by a universal mechanical testing machine in vitro, finite element analysis and clinical observation. Most scholars’ studies have shown that minimally invasive endodontics can improve the fracture resistance of teeth, but the differential capacities of CEC and TEC remain controversial. How does on balance the purpose of pulp treatment and the maximum retention of tooth tissue? Further exploration is still needed.
ABSTRACT
@#Minimally invasive endodontics (MIE) can preserve dental tissue to a greater extent and improve the success rate of endodontics and has thus attracted increasing attention. 3D printing is a technology that is based on a digital model and uses powdered metal, plastic and other materials to construct objects by printing layer by layer. This article reviews the application of 3D printing technology in minimally invasive endodontics to provide a reference for the application of 3D printing technology in clinical minimally invasive endodontics in the future. In recent years, 3D printing technology has been widely used in various professional fields of stomatology, such as maxillofacial surgery, prosthodontics, and orthodontics. Using cone beam computed tomography (CBCT) and oral scanners to obtain accurate data on the internal and external structures of teeth combined with 3D printing to construct a tooth diagnostic model and pulp opening guide plate, we can accurately locate the position of the root canal and provide a new method for minimally invasive endodontics. At present, 3D printing technology is mainly used to guide the pulp opening pathway, assist in the minimally invasive treatment of malformed teeth and calcified root canals, and assist with apical surgery in the field of minimally invasive endodontics. However, its accuracy and clinical prognosis still need to be verified with a large number of clinical cases.
ABSTRACT
OBJECTIVE@#This study evaluates the effects of different endodontic access methods and full-ceramic crown on the stress distribution in the maxillary central incisor by using three-dimensional finite element analysis.@*METHODS@#Computed tomography scans of the maxillary central incisor were used to construct a three-dimensional finite element model of the maxillary central incisor. According to the different methods of endodontic and the prosthetic treatments, four models were established, namely, group A (traditional access cavity preparation with resin filling), group B (traditional access cavity preparation restored full-ceramic crown), group C (minimally invasive endodontics with resin filling) and group D (minimally invasive endodontics restored full-ceramic crown). A static force of 100 N and a direction of 45° was applied to the long axis of the tooth at the junction of the incisal section one-third and middle section one-third. The maximum principal stress, the von Mises stress and the modified von Mises stress of the tooth tissue were analyzed using the finite-element analysis software.@*RESULTS@#1) Stress peaks: the stress peaks of the maximum principal stress, the von Mises stress and the modified von Mises in group A were the largest, except that the stress peak of von Mises stress in group D was slightly lower than that in group C. The stress peaks of the maximum principal stress and the modified von Mises in group C were the lowest. The stress peaks of the maximum principal stress and the modi-fied von Mises stress in group D were lower than those in groups A and B. 2) Stress distribution: compared with group A, the stress distribution of cervical dentin and the area of stress concentration in group C was lower and smaller. In the root dentin, the stress distribution in group C was more uniform than that in group A, and the stress was dispersed to several areas of the root apex. After crown restoration, no significant difference was observed in stress distribution between groups B and D in the root region. The stress distribution state of group B was not significantly different from that of group A. No significant difference was observed in the stress distribution state between groups D and C.@*CONCLUSIONS@#1) From the perspective of biomechanics, the minimally invasive access was adopted for the maxillary central incisor. 2) Full crown restoration is recommended after traditional access cavity preparation. No obvious advantage is observed in stress analysis for minimally invasive endodontics-restored full-ceramic crown.
Subject(s)
Crowns , Dental Stress Analysis , Dentin , Finite Element Analysis , Incisor , Post and Core Technique , Stress, Mechanical , Tooth CrownABSTRACT
@#Dental operating microscope is recommended to complicated root canal therapy, for it could provide increased lighting and superior magnification, so that the survival rate of tooth is highly increased. More refined access of cavity preparation, canal cleaning, shaping and obturating are realized under microscope. This article combined literature reviews with the writers’ clinical experience, and it aims at helping clinicians to improve their ability to more accurately performance and minimally invasive endodontic procedures, such as locating hidden canals obstructed by calcifications, canals reduced in size, removing materials, reducing ledge formation, apical transportation, and repairing perforations.