Nuran Ulusoy

Time-based Elution of TEGDMA and BisGMA from Resin Composite Cured with LED, QTH and High-intensity QTH Lights

This study measured the elution of TEGDMA and BisGMA monomers from hybrid, micro-filled resin composites over 72 hours at different time intervals after polymerization with standard quartz-tungsten-halogen (QTH), high-intensity fast-curing QTH and standard blue light emitting diode (LED) light units. Samples were polymerized from the top and bottom surfaces, then immersed in methanol. High performance liquid chromatography (HPLC) was used to measure the amount of monomers released from the samples at various time intervals, ranging from 0 to 72 hours (0, 3, 6, 9, 12, 24, 48 and 72 hours). Data was analyzed using two-way ANOVA and Duncan tests with a significance level of 0.05. No significant differences were observed among curing groups in the elution of TEGDMA monomers at 0, 9, 12, 24, 48 and 72 hours; whereas, significant differences were observed among curing groups at 3 and 6 hours. BisGMA elution in samples immersed for longer periods (9-72 hours) were significantly higher than samples immersed for shorter time periods (0-6 hours); however, 72 hours appeared to be too short a period for the total elution of BisGMA into methanol.

Fracture durability of restored functional cusps on maxillary nonvital premolar teeth

Palatal cusps of nonvital maxillary premolar teeth were restored with a coronal-radicular restoration of posterior composite resin (Occlusin), amalgam (Tytin), or cermet (Chelon-Silver). Mean fracture strength values were: 370 lb for intact premolar teeth, 266 lb for amalgam, 215 lb for posterior composite resin, and 132 lb for cermet. From this in vitro study it can be suggested that for selected endodontically treated maxillary premolar teeth, the dentist can use acid-etch-retained posterior composite resin or pin-retained high copper amalgam material for a definitive coronal-radicular restoration. The use of cermet for this purpose is contraindicated.

Thermal response to multiple use of a twist drill

The objective of the present investigation was to determine whether injurious thermal changes occur in the pulp chamber if a twist drill is used 10 times, and to find whether there is a correlation between temperature rise and distance between a drilled channel and the pulp chamber. Twenty caries-free, human, premolar teeth were randomly distributed to two dentists. With a new 2 mm twist drill, each dentist prepared 10 pinholes (one hole per tooth). Intrapulpal temperature change during the drilling procedure was recorded. The data were statistically analyzed by the Spearman rank order correlation coefficient. The results showed that twist drills should not be used for more than five pinholes (p less than 0.001). The distance between the pin channel and the pulp chamber does not influence heat generation in the pulp chamber.

The effect of home bleaching agents on the surface roughness of five different composite resins: A SEM evaluation.

The aim of this study was to investigate the effect of hydrogen peroxide (HP) and carbamide peroxide (CP) on the surface roughness of five different composite resins using profilometer and scanning electron microscope (SEM). Thirty-six specimens (1 mm thick, 10 mm in diameter) of five composite resins were fabricated. Each composite group was equally divided into three subgroups as control, CP and HP. In control group, specimens were stored in daily refreshed distilled water during the 14-day testing period. In other groups, 10% HP (Opalescence Treswhite) and 10% CP (Opalescence PF) were applied and surface roughness values (Ra) of each specimen were measured with a profilometer at the end of 14 days. Additionally, SEM analysis was performed to evaluate the surface deformations of composite resins. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Ra values of composite groups exposed to bleaching agents were statistically higher than control group (p < 0.05). There was no significant difference between Ra values after HP and CP application within each composite group while SEM micrographs showed higher surface alterations at HP group compared to CP. Among the composite resins tested, Ceram-X Mono revealed the lowest Ra values after CP and HP applications as seen at SEM images. Home bleaching agents increased the surface roughness of all composites. Except CP applied Ceram-X mono specimens, Ra values of all composite resins evaluated in this study exceeded the critical limit of 0.2 μm. Ceram-X mono was the least affected composite material after bleaching application. SCANNING 38:277-283, 2016.

Solvent type influences bond strength to air or blot-dried dentin.

BackgroundAir-drying of etched and rinsed dentin surface may force the exposed collagen fibrils to collapse. Blot-drying is an alternative method to wipe the excess water from the dentin surface without compromising the monomer penetration. Contemporary total etch adhesives contain ethanol/water or acetone as solvent in which resin monomers are dissolved. Solvent type of the adhesive system has an important role in bonding to dentin. An adhesive containing tertiary butanol as an alternative solvent has been in the market. Purpose of this study is to determine the shear bond strengths of three total-etch adhesives with different solvents (acetone, ethanol or tertiary butanol) applied to air or blot dried moist dentin.MethodsSixty extracted non-carious human third molars were divided into three main groups according to solvent content of the adhesives [acetone based - One Step (OS, Bisco, IL, USA); ethanol/water based - Optibond Solo Plus (OB, Kerr, CA, USA); and tertiary butanol based - XP Bond (XP, Caulk/Dentsply, DE, USA)]. Each main group was divided into two groups according to drying methods (blot or air) (n = 10). Shear bond strengths (SBS) were measured. Data were analyzed by Student’s t test and Tukey HSD test (p < 0,05).ResultsXP showed highest SBS values in both drying methods applied (p < 0.05). Drying method did not influence the SBS in OS and OB (p > 0.05). XP-blot produced significantly higher SBS than XP-air (p < 0.05).ConclusionsTertiary butanol based adhesive showed higher bond strength values than ethanol or acetone based adhesives. Blot drying of dentin improved the bond strength values of tertiary butanol based adhesive. Further research is necessary to determine in vivo and in vitro performance of tertiary butanol based adhesives.

Basics of dentin-pulp tissue engineering

Regeneration is reconstruction of a tissue with the shape and function of the original tissue including vascularization and innervations. Highly degradation of dentin-pulp complex can not be reversed by its own repair mechanisms. For decades, endodontic treatments including pulpectomy and preparation of root canals have been the first choice for these cases. However, root canal treatment method has some unsatisfying consequences like; esthetic problems as a conclusion of discoloration caused by endodontic filling materials, undermined integrity of tooth structure, postoperative fractures, coronal leakage or periapical microleakage, lost sense of environmental changes which can make the recurrent caries or apical infection unnoticeable for patient and shortened lifetime in comparison with vital teeth. Currently regeneration of dentin-pulp complex by tissue engineering approach is thought to be a more appropriate choice instead of root canal treatment according to these outcomes. In this review, we will discuss basic components as stem cells, signaling molecules and scaffolds and also methods used for dentin-pulp tissue engineering.

Effect of Endocrown Restorations with Different CAD/CAM Materials: 3D Finite Element and Weibull Analyses

The aim of this study was to evaluate the effects of two endocrown designs and computer aided design/manufacturing (CAD/CAM) materials on stress distribution and failure probability of restorations applied to severely damaged endodontically treated maxillary first premolar tooth (MFP). Two types of designs without and with 3 mm intraradicular extensions, endocrown (E) and modified endocrown (ME), were modeled on a 3D Finite element (FE) model of the MFP. Vitablocks Mark II (VMII), Vita Enamic (VE), and Lava Ultimate (LU) CAD/CAM materials were used for each type of design. von Mises and maximum principle values were evaluated and the Weibull function was incorporated with FE analysis to calculate the long term failure probability. Regarding the stresses that occurred in enamel, for each group of material, ME restoration design transmitted less stress than endocrown. During normal occlusal function, the overall failure probability was minimum for ME with VMII. ME restoration design with VE was the best restorative option for premolar teeth with extensive loss of coronal structure under high occlusal loads. Therefore, ME design could be a favorable treatment option for MFPs with missing palatal cusp. Among the CAD/CAM materials tested, VMII and VE were found to be more tooth-friendly than LU.

DENTİN AŞIRI HASSASİYETİ: TANI VE TEDAVİ YÖNTEMLERİ

Dentin hypersensitivity has been defined as the short, sharp and severe pain arising from exposed dentin in response to thermal, evaporative, tactile, electrical, chemical or osmotic stimuli. Various theories about pain mechanism of dentin hypersensitivity have been reported but none of the pain mechanisms has not been proved yet. The epidemiological research reported hypersensitivity and day after day it is increasing. The aetiology of dentin hypersensitivity is multifactorial. Diagnosis is difficult. Different materials and methods have been used for the treatment of dentin hypersensitivity but a gold standart for treatment has not been found yet. The definition, theories about pain mechanisms, aetiology and risk factors, diagnosis and treatment of dentin hypersensitivity will be discussed in this review