Analysis of factors related to needle-stick and sharps injuries at a dental specialty university hospital and possible prevention methods.

Needle-stick and sharps injuries (NSIs) can happen even when dental health care workers (DHCWs) act in compliance with standard precautions to prevent transmitting blood-borne infections. The objective of this study was to investigate causes of NSIs that had occurred at a dental specialty university hospital during the past 12 academic years. A total of 215 NSIs were reported during the investigation period, and NSIs ascribed to female DHCWs (n = 148; 68.

Irrigation effectiveness of continuous ultrasonic irrigation system: An ex vivo study.

This study evaluated the irrigation extrusion and smear layer (SL) removal of continuous ultrasonic irrigation (CUI). Forty root canals were shaped, embedded in warm sterile saline agar colored with 1% acid red, and distributed into four groups; three groups had the final irrigation sequence of sodium hypochlorite and EDTA solutions performed by using syringe irrigation (SI), EndoVac (EV), and CUI, respectively. Group 4 had the canals ultrasonically irrigated with saline (CUIS).

Shaping ability of ProTaper NEXT, ProTaper Universal and iRace files in simulated S-shaped canals.

The aim of this study was to determine the shaping ability of three nickel-titanium endodontic file systems by comparing three parameters: canal deviation, apical foramen position and instrumentation time. A glide path was established in 30 simulated S-shaped canal blocks that were randomly assigned into three groups (n = 10): ProTaper Universal, ProTaper NEXT and iRace. Each group was instrumented per its manufacturer's directions.

Effect of nickel titanium file design on the root surface strain and apical microcracks.

The aim of this study was to determine the effect of nickel titanium file design on the root surface strain generated and apical microcracks caused during canal shaping. Thirty-three mandibular incisors were distributed into LightSpeed X, FlexMaster and a control group. A strain gauge was fixed apically on the proximal root surface to determine the maximum strain during canal shaping.

Performance of NiTi endodontic instrument under different temperatures.

The purpose of this study was to test nickel titanium (NiTi) instrument performance under different surrounding temperatures. Twenty-four superelastic NiTi instruments with a conical shape comprising a 0.30-mm-diameter tip and 0.

A comparison between two negative pressure irrigation techniques in simulated immature tooth: an ex vivo study.

Objectives: This ex vivo study evaluated the irrigation efficacy of a new apical negative pressure system (ANP) in canals with simulated immature teeth, by comparing it to EndoVac (EV) system in terms of smear layer (SL) removal and irrigation extrusion.

Materials And Methods: Three millimetres of the root end of 40 single canalled lower incisors were resected and decoronated to standardize root canal length. After instrumentation, the specimens were embedded in warm normal saline agar coloured with 1 % acid red and randomly divided into four groups; one control group and three experimental groups.

Sympathetic Regulation of Tertiary Dentinogenesis via Beta-2 Adrenergic Receptor on Rat Odontoblasts.

Introduction: Beta-2 adrenergic receptor has been found within the osteoblast membrane meditating bone remodeling. Propranolol is a sympatholytic beta antagonist commonly used as long-term medication for the management of many common diseases such as hypertension. This study was performed to verify the presence of this receptor on odontoblasts in rats and, if present, to investigate its possible association with tertiary dentinogenesis.

Detection of a second mesiobuccal canal in maxillary molars by swept-source optical coherence tomography.

Introduction: The purpose of this study was to investigate the ability of swept-source optical coherence tomographic (SS-OCT) imaging to detect a second mesiobuccal canal (MB2) in maxillary molars compared with visual inspection (VI) and dental operating microscopy (DOM).

Methods: Forty extracted human maxillary molars were examined. After the removal of half the crown and access cavity preparation, the existence of MB2 canals was confirmed based on cross-sectional images of each tooth obtained by micro-computed tomographic scanning as the reference standard.

Down-regulation of inflammatory mediator synthesis and infiltration of inflammatory cells by MMP-3 in experimentally induced rat pulpitis.

Introduction: Matrix metalloproteinase (MMP)-3 is a member of the MMP family that degrades the extracellular matrix. Application of MMP-3 to injured pulp tissue induces angiogenesis and wound healing, but its anti-inflammatory effects are still unclear. Here, we evaluated the anti-inflammatory functions of MMP-3 in vitro and in vivo.

Correlation between cyclic fatigue and the bending properties of nickel titanium endodontic instruments.

The effects of cyclic fatigue on bending properties of NiTi endodontic instruments were investigated. Sixteen Profiles(®) were divided into two groups (A, and B). The sequence of cantilever bending test and cyclic fatigue test was alternated repeatedly until file separation occurred.

Application of optical coherence tomography to identify pulp exposure during access cavity preparation using an Er:YAG laser.

Objective: The study aimed to evaluate the ability of optical coherence tomography (OCT) to guide and identify pulp exposure using an erbium: yttrium-aluminum-garnet (Er:YAG) laser.

Background Data: The Er:YAG laser has been proven to be effective in ablating dental hard tissue and offers advantages, as there is none of the vibration and noise you get with conventional methods, but it has limitations in relation to the tactile feedback that would aid in identification of entry into the pulp chamber. Based on depth-resolved optical reflectivity, OCT technology has been developed to provide high-resolution, cross-sectional images of the internal structure of biological tissues.

Periostin is a negative regulator of mineralization in the dental pulp tissue.

The dental pulp tissue is encased in hard tissue and surrounded by hard tissue-forming cells, but remains in a non-mineralized state itself, suggesting the presence of regulatory mechanisms precluding pulp mineralization. This study aimed to reveal the regulatory function of periostin (Postn), which is essential for osteoblast differentiation, for odontoblast differentiation/mineralization. We evaluated the effects of Postn overexpression and RNAi-mediated suppression in mouse dental papilla cells (MDPs) on the expression of odontoblastic markers and Notch signaling molecules, and on the formation of mineralized nodules.

Endodontic instruments after torsional failure: nanoindentation test.

This study aimed to evaluate effects of torsional loading on the mechanical properties of endodontic instruments using the nanoindentation technique. ProFile (PF; size 30, taper 04; Dentsply Maillefer, Switzerland) and stainless steel (SS; size 30, taper 02; Mani, Japan) instruments were subjected to torsional test. Nanoindentation was then performed adjacent to the edge of fracture (edge) and at the cutting part beside the shank (shank).

Three-dimensional spheroid culture promotes odonto/osteoblastic differentiation of dental pulp cells.

Objective: Three-dimensional (3D) spheroid culture is a method for creating 3D aggregations of cells and their extracellular matrix without a scaffold mimicking the actual tissues. The aim of this study was to evaluate the effects of 3D spheroid culture on the phenotype of immortalized mouse dental papilla cells (MDPs) that have the ability to differentiate into odontoblasts.

Methods: We cultured MDPs for 1, 3, 7, and 14 days in 96-well low-attachment culture plates for 3D spheroid culture or flat-bottomed plates for two-dimensional (2D) monolayer culture.

The influence of heat treatment on the mechanical properties of Ni-Ti file materials.

The purpose of this study was to investigate the influence of heat treatment on the mechanical properties of Ni-Ti file materials. Ni-Ti wire (1.00 mm ø) was processed into a conical shape with 0.

Kinetics of Th17-related cytokine expression in experimentally induced rat periapical lesions.

Th17-related cytokines are essential factors in various pathological states, including inflammatory bone destruction. This study investigated the contribution of Th17-related cytokines to the progress of experimentally induced rat periapical lesions. Periapical pathoses were induced by unsealed exposure of the pulp chamber of the lower first molars.

Comparison of the time required to create secondary fracture of separated file fragments by using ultrasonic vibration under various canal conditions.

Introduction: Nickel-titanium files often separate because of mechanical fatigue. The purpose of this study was to determine safe preparation techniques for separated file removal by using ultrasonics.

Methods: Fifty nickel-titanium file fragments were divided into 5 groups.

Joint haemorrhage partly accelerated immobilization-induced synovial adhesions and capsular shortening in rats.

Purpose: To elucidate the effects of intra-articular haemorrhage on the joint capsule of immobilized knees in rats.

Methods: The unilateral knee joints were immobilized using a plastic plate and screws. Sham operated rats had only screws inserted.

Wnt11 expression in rat dental pulp and promotional effects of Wnt signaling on odontoblast differentiation.

Congenital anomalies of wingless-type mouse mammary tumor virus (MMTV) integration site family (Wnt) are frequently accompanied with tooth and dentin abnormality. The aim of this study was to investigate the effects of Wnt signaling on odontoblast differentiation of mouse dental papilla cells (MDPs). Mouse dental papilla cells were cultured in α-modified minimum essential medium containing 10% fetal bovine serum and antibiotics.

Determination of the functional space for fluid movement in the rat dentinal tubules using fluorescent microsphere.

Objectives: The size of the functional space available for hydrodynamic fluid movement between cellular components and the walls of dentinal tubules has not yet been investigated. We attempted to measure the space using small diameter fluorescent microspheres.

Methods: The coronal enamel of 144 rat molars was removed to expose the dentine, which was acid-etched.

Up-regulation of p38 mitogen-activated protein kinase during pulp injury-induced glial cell/neuronal interaction in the rat thalamus.

Introduction: We have recently reported that the signal of pulp injury induces both neuronal and glial cell activation in the contralateral thalamus in rats, although the mechanisms of the glial cell/neuronal interaction remain unclear. This study was undertaken to test our hypothesis that p38 mitogen-activated protein kinase (MAPK) signaling pathways are involved in the pulp injury-induced glial cell/neuronal interaction in the thalamus.

Methods: A local anesthetic (lidocaine with epinephrine) or saline (control) was injected into the tissue surrounding the left mandibular first molar of Wistar rats.

Joint immobilization induced hypoxic and inflammatory conditions in rat knee joints.

The purpose of this study was to examine the hypoxic and inflammatory conditions after immobilization in the joint capsule of rat knees. The unilateral knee joints of adult male rats were immobilized with an internal fixator (Im group) for 1 day, 3 days, and 1, 2, 4, 8, and 16 weeks. Sham-operated animals had holes drilled in the femur and tibia and screws inserted without a plate (control group).

Evaluation of coronal leakage and pathway of dye leakage after obturation with various materials for open apical foramina.

The aim of this study was to investigate coronal leakage after obturation with mineral trioxide aggregate (MTA), resin-based sealer, and silicon-based sealer for open apical foramina and to evaluate pathway of leakage. Twenty-eight maxillary premolars were used, and instrumented to ISO size #80. Teeth were randomly divided into four groups as follows: Group A filled with MTA, Group B with gutta-percha and resin-based sealer, Group C with polymer-based material and resin-based sealer, and Group D with gutta-percha and silicon-based sealer.

Detection of root surface fractures with swept-source optical coherence tomography (SS-OCT).

Objective: The purpose of this study was to compare optical coherence tomography (OCT) with the existing technologies, to assess its accuracy and utility in detecting vertical root fractures of extracted human teeth.

Background Data: The detection of root fractures in teeth that have undergone root canal treatment is challenging because of the great difficulty in differentiating these fractures from morphologic or radiographic anomalies. OCT methods are based on depth-resolved optical reflectivity and have been developed to reduce the invasiveness and radiation exposure inherent to other techniques.

Facilitatory effect of AC-iontophoresis of lidocaine hydrochloride on the permeability of human enamel and dentine in extracted teeth.

Objectives: The objectives of the present study were to quantitatively evaluate chemical permeability through human enamel/dentine using conductometry and to clarify if alternating current (AC) iontophoresis facilitates such permeability.

Materials And Methods: Electrical impedance of different concentrations of lidocaine hydrochloride was measured using a bipolar platinum impedance probe. A quadratic curve closely fitted to the response functions between conductance and lidocaine hydrochloride.