Recent biomechanical studies have focused on studying the response of teeth before and after different treatments under functional and parafunctional loads. These studies often involve experimental and/or finite element analysis (FEA). Current loading and boundary conditions may not entirely represent the real condition of the tooth in clinical situations. The importance of homogenizing both sample characterization and boundary conditions definition for future dental biomechanical studies is highlighted. The mechanical properties of dental structural tissues are presented, along with the effect of functional and parafunctional loads and other environmental and biological parameters that may influence tooth survival. A range of values for Young’s modulus, Poisson ratio, compressive strength, threshold stress intensity factor and fracture toughness are provided for enamel and dentin; as well as Young’s modulus and Poisson ratio for the PDL, trabecular and cortical bone. Angles, loading magnitude and frequency are provided for functional and parafunctional loads. The environmental and physiological conditions (age, gender, tooth, humidity, etc.), that may influence tooth survival are also discussed. Oversimplifications of biomechanical models could end up in results that divert from the natural behavior of teeth. Experimental validation models with close-to-reality boundary conditions should be developed to compare the validity of simplified models.

This paper aims to study the removal of a vapor lock located in the apical ramification of an oval distal root of a human mandibular molar, simulating different needles and irrigation depths with computational fluid dynamic. A geometric reconstruction of the micro‐CT of the molar shaped up to a WaveOne Gold Medium instrument was used. A vapor lock located in the apical 2 mm was incorporated. Geometries with positive pressure needles (side‐vented [SV], flat or front‐vented [FV] and notched [N]) and the EndoVac microcannula (MiC) were created to run the simulations. Irrigation key parameters (flow pattern, irrigant velocity, apical pressure, wall shear stress) and vapor lock removal were compared among the different simulations. Each needle behaved differently that is, FV removed the vapor lock from one ramification and had the highest apical pressure and shear stress values; SV removed the vapor lock in the main root canal but not in the ramification and reached the lowest apical pressure from the positive pressure needles; N was not able to completely remove the vapor lock and showed low apical pressure and shear stress; MiC removed the vapor lock from one ramification, had negative apical pressure and the lowest maximum shear stress. The main conclusion is that none of the needles showed complete removal of vapor lock. MiC, N, and FV were able to partially remove the vapor lock from one out of the three ramifications. However, SV needle was the only simulation that showed high shear stress with low apical pressure.

Objectives: To compare the mechanical responses of a mandibular molar under functional loads using antagonist teeth and different loading applications and configurations. Methods: A cone-beam computed tomography of a human mandible and maxilla was used to build 16 different three-dimensional models, including four mandibular configurations [single-tooth model (first mandibular molar-M), and inclusion of mesial (mM), distal (Md) or both proximal contacts (mMd)] and occlusal load applications either with antagonist teeth or alternative Finite Element (FE) models [point load (PL), distributed surface load (SL) and rigid metal sphere (MS)]. FE analysis was performed. Equivalent von Mises (VM) stress was calculated along the entire dentin and periodontal ligament of the first mandibular molar. Maximum VM stresses were compared among the different mandibular configurations and loading applications. Results: The highest and lowest VM stress at 50 and 100 N corresponded respectively to the single-tooth SL model (5.78 and 11.5 MPa) and to occlusal load application with antagonist teeth and proximal contacts (2.08 and 3.58 MPa). Maximum VM stresses were consistently located at the cervical area of the mesial root and decreased when adjacent teeth were present. Conclusions: Highest stresses are located in the cervical area of the mesial root of mandibular molars, but the biomechanical behavior depends on the presence of proximal contacts and the loading methodologies used. Single-tooth models represent the worst structural scenario. Clinical relevance: Incorporating antagonist teeth and proximal contacts into FE models enhances the biofidelity of dental biomechanics simulations, enabling more accurate extrapolation to clinical conditions.

Correction to: Structural response of mandibular first molars in the presence of proximal contacts: finite element analysis with antagonist