Mechanical failure of posterior teeth due to caries and occlusal wear- A modelling study.

Objectives: The purpose of the present work is to explore the effect of occlusal wear and different types and degrees of caries on the mechanical performance and structural integrity of posterior teeth.

Methods: Three-dimensional (3D) computational models with different combinations of caries parameters (caries location, caries size and caries induced pulp shrinkage) and occlusal wear factors (enamel thickness, marginal ridge height and cuspal slope) were developed and analyzed using the extended finite element method (XFEM) to identify the stress distribution, crack initiation load and ultimate fracture load values. The effect of a non-drilling conservative treatment using resin infiltration on the recovery of mechanical properties of carious molar teeth was also investigated.

Monolithic crowns fracture analysis: The effect of material properties, cusp angle and crown thickness.

Objectives: This study aimed to investigate the collective influence of material properties and design parameters on the fracture behavior of monolithic dental crowns.

Methods: Three-dimensional (3D) models (N=90) with different combinations of design parameters (thickness, cusp angle and occlusal notch geometry) and material type (lithium disilicate, feldspar ceramic, zirconia, hybrid resin ceramic and hybrid polymer-infiltrated ceramic) were developed for the failure analysis using extended finite element method (XFEM) to identify the stress distribution, crack initiation load, fracture surface area and fracture pattern. Analytical formulation, in vitro fracture tests and fractographic analysis of dedicated models were also performed to validate the findings of the XFEM simulation.

Modelling of stress distribution and fracture in dental occlusal fissures.

The aim of this study was to investigate the fracture behaviour of fissural dental enamel under simulated occlusal load in relation to various interacting factors including fissure morphology, cuspal angle and the underlying material properties of enamel. Extended finite element method (XFEM) was adopted here to analyse the fracture load and crack length in tooth models with different cusp angles (ranging from 50° to 70° in 2.5° intervals), fissural morphologies (namely U shape, V shape, IK shape, I shape and Inverted-Y shape) and enamel material properties (constant versus graded).

Microstructural and Mechanical Characterization of CAD/CAM Materials for Monolithic Dental Restorations.

Purpose: To determine and compare the microstructure, flexural strength, flexural modulus, fracture strength, and microhardness of four types of computer-aided design/computer-aided manufacturing (CAD/CAM) materials for monolithic dental restorations.

Materials And Methods: A lithium disilicate (LD; IPS e.max CAD), a zirconia-reinforced lithium silicate (ZLS; VITA Suprinity), a hybrid high-performance polymer (HPP) composite resin (GC Cerasmart), and a hybrid polymer-infiltrated ceramic network (PICN) material (VITA Enamic) were used to manufacture monolithic ceramic posterior crowns (n = 10) that were adhesively cemented on resin-based composite dies and loaded until fracture.

Missing Surface Estimation Based on Modified Tikhonov Regularization: Application for Destructed Dental Tissue.

Estimation of missing digital information is mostly addressed by one or two-dimensional signal processing methods; however, this problem can emerge in multi-dimensional data including 3D images. Examples of 3D images dealing with missing edge information are often found using dental micro-CT, where the natural contours of dental enamel and dentine are partially dissolved or lost by caries. In this paper, we present a novel sequential approach to estimate the missing surface of an object.

Efficacy of Fluoride Varnishes with Added Calcium Phosphate in the Protection of the Structural and Mechanical Properties of Enamel.

The aim of this study was to investigate the efficacy of various fluoride varnishes in the protection of the structural and nanomechanical properties of dental enamel. Demineralized enamel specimens were imaged using a high-resolution micro-CT system and lesion parameters including mineral density and lesion depth were extracted from mineral density profiles. Nanoindentation elastic modulus and hardness were calculated as a function of penetration depth from the load-displacement curves.

Micro-CT analysis of naturally arrested brown spot enamel lesions.

Objectives: The aim of this study was to characterize the mineral density parameters through natural enamel brown spot lesions (BSLs) and to visualize and map their mineral distribution pattern in comparison to enamel whitespot lesions (WSLs).

Methods: Study specimens included seventeen proximal WSLs (ICDAS 1, 2), seventeen proximal BSLs and seventeen sound proximal specimens (ICDAS 0) collected from The Oral Surgery Department at Sydney Dental Hospital, Sydney, Australia. Imaging was undertaken using a high resolution, desktop micro-computed tomography system.

Quantitative characterization and micro-CT mineral mapping of natural fissural enamel lesions.

Objectives: The aim of this study was to characterize the mineral distribution pattern of natural fissural enamel lesions and to quantify structural parameters and mineral density of these lesions in comparison to proximal white spot enamel lesions.

Methods: Imaging was undertaken using a high-resolution desktop micro-computed tomography system. A calibration equation was used to transform the grey level values of images into true mineral density values.

A comparative study of new and current methods for dental micro-CT image denoising.

Objectives: The aim of the current study was to evaluate the application of two advanced noise-reduction algorithms for dental micro-CT images and to implement a comparative analysis of the performance of new and current denoising algorithms.

Methods: Denoising was performed using gaussian and median filters as the current filtering approaches and the block-matching and three-dimensional (BM3D) method and total variation method as the proposed new filtering techniques. The performance of the denoising methods was evaluated quantitatively using contrast-to-noise ratio (CNR), edge preserving index (EPI) and blurring indexes, as well as qualitatively using the double-stimulus continuous quality scale procedure.

Concentrated growth factor increases Schwann cell proliferation and neurotrophic factor secretion and promotes functional nerve recovery in vivo.

Concentrated growth factor (CGF) is a newly generated complex that comprises a fibrin matrix incorporating growth factors and plasmatic and leukocyte cytokines. It has been widely used in bone regenerative medicine. However, the effect of CGF on peripheral nerve regeneration had not been previously investigated.

Developing a new dental implant design and comparing its biomechanical features with four designs.

Background: As various implant geometries present different biomechanical behaviors, the purpose of this work was to study stress distribution around tapered and cylindrical threaded implant geometries using three-dimensional finite element stress analysis.

Methods: Seven implant models were constructed using Computer Assisted Designing system. After digitized models of mandibular section, the crowns were created.

Human papilloma virus as a possible factor in the pathogenesis of oral lichen planus.

Background: Oral lichen planus (OLP) is a common chronic inflammatory mucocutaneous disease. Clinical diagnosis of OLP requires clinical work-up and histologic examination to rule out possible dysplasia and carcinoma. It is possible that oral mucosal viral infections including HPV infection may have a causative role in OLP pathogenesis.