Does Low-Taper Root Canal Shaping Decrease the Risk of Root Fracture? A Systematic Review

Abstract

Minimal root-canal preparation has been suggested to reduce the risk of root fracture, but as a result, satisfactory cleaning and shaping do not take place. Large-scale taper instrumentation can contribute to removing infected tissue; however, it may weaken the tooth structure. The aim of this systematic review is to evaluate whether root-canal shaping with low-taper instruments decreases the risk of root fracture, compared to high-conicity shaping. A search was performed on Ovid MEDLINE, PubMed, and the Web of Science. The inclusion criteria were: studies comparing the root fracture resistance of endodontically treated teeth, shaped with low- and high-conicity taper instruments, in human trials, and via in vitro study. The review includes all types of endodontically treated teeth, with various instrument tapers. The scientific search engines produced 328 results. Only 20 of the results were evaluated after screening. Based on the articles analyzed, it is not clear whether a taper difference can determine differences in root fracture resistance. No randomized controlled trial (RCTs) with long follow-ups have been published to date. It must also be taken into account that the in vitro studies do not consider the numerous differences that there are between in vitro and clinical evaluation. The review was registered on the PROSPERO website, with the protocol number CRD42020151451.

Middle mesial canal in mandibular first molar: A narrative review

“…The crown-down instrumentation technique is preferred for cleaning and shaping these accessory canals, and care must be taken during instrumentation ( Puleio et al, 2022 ). A careful brushing motion is employed away from the furcation area and toward the mesial side of the root.…”

In Vitro Resistance of Natural Molars vs. Additive-Manufactured Simulators Treated with Pulpotomy and Endocrown

“…Studies have shown that reciprocating motion induces lower tensile and compressive stress in the flexed region of the instrument, thus providing greater fatigue resistance compared with continuous rotative movement [ 28 , 29 ]. High-taper instruments, such as the WaveOne Primary (25/0.08), can contribute to deeper infected-tissue removal, achieving the appropriate irrigant penetration level [ 30 ], and a recent systematic review concluded that it is not clear whether a difference in taper angle can determine differences in root fracture resistance; therefore, it is not possible to provide clinical recommendations regarding the use of endodontic instruments with a high (≥6%) or a low (<6%) taper [ 31 ].…”

Vertical root fracture resistance and crack formation of root filled teeth treated with or without minimally invasive endodontic shaping

“…Potential preparation-related root weakening could be reinforced by adhesive resin-based obturation [17][18][19], but long-term studies have shown signi cantly lower success rates compared to obturation with GP and sealer [20,21]. To reduce the risks of crack formation and root fracture, authors instead recommended MIE shaping with le sizes between #20 to #40 and 0.04 to 0.06 tapers, canal morphology dependent [9,10,22]. On the other hand, insu cient canal debridement could lead to treatment failure, particularly in teeth with infected and necrotic pulp.…”