Fracture Resistance of Simulated Immature Teeth after Different Intra-radicular Treatments

Abstract

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

Physicochemical Properties and Dentin Bond Strength of a Tricalcium Silicate-Based Retrograde Material

“…Ideally, a retrograde filling material should not only to provide a tight seal of the apical third of roots submitted to apicectomy and root-end preparations. However, it should adhere to dentin and resist to dislodgment to assure apical sealing stability, taking into consideration that calcium silicate-based cements are also used to perform apical barriers in traumatized teeth that usually require prosthetic rehabilitation and intracanal reinforcement to increase their resistance to fracture (21). Therefore, these materials should resist to dislodgement when occlusal forces are indirectly applied.…”

Effect of apexification on occlusal resistance of immature teeth

“…To date, no study has comprehensively determined changes in occlusal resistance in immature teeth, although some studies have estimated the strength of immature teeth, typically using ultimate fracture strength [13][14][15][16]. Load-to-failure testing is a simple way to estimate the ultimate strength of a specimen, but the test setting (e.g., cross-head speed or load angle) varies widely, and testing assemblies exclude the physiological environment (such as PDL space).…”

Long-Term Fracture Resistance of Simulated Immature Teeth Filled with Various Calcium Silicate-Based Materials

“…It is well established that as the dentin wall thickness decreases, the resistance to fracture decreases as well, and therefore it becomes more important to select a material that has potential to reinforce the root structure [ 5 , 14 ]. A number of studies have focused on increasing fracture resistance of immature teeth using various techniques [ 15 – 19 ]. MTA has been a revolutionary material in endodontics because of its high biocompatibility and sealing ability.…”