Longitudinal craze line propagation in human root dentin after instrumentation with NiTi rotary files of different instrument tapers after long-term chewing simulation.

Objectives: The aim of this study was to investigate whether file design and taper significantly influence microcrack initiation during machine preparation.

Materials And Methods: Sixty extracted teeth with straight single canals were selected. The teeth were randomly assigned to four groups based on their root canal anatomy and the corresponding NiTi rotary file system (I, Mtwo; II, ProTaper Universal; III, F6 SkyTaper; control, no preparation and filling).

Effects of various chair-side surface treatment methods on dental restorative materials with respect to contact angles and surface roughness.

Available chair-side surface treatment methods may adversely affect prosthetic materials and promote plaque accumulation. This study investigated the effects of treatment procedures on three resin restorative materials, zirconium-dioxide and polyetheretherketone in terms of surface roughness and hydrophobicity. Treatments were grinding with silicon carbide paper or white Arkansas stone, blasting with prophylaxis powder and polishing with diamond paste.

Comparison of design and torque measurements of various manual wrenches.

Purpose: Accurate torque application and determination of the applied torque during surgical and prosthetic treatment is important to reduce complications. A study was performed to determine and compare the accuracy of manual wrenches, which are available in different designs with a large range of preset torques.

Materials And Methods: Thirteen different wrench systems with a variety of preset torques ranging from 10 to 75 Ncm were evaluated.