Effect of Different Polymerization Methods on the Cytotoxicity of Dental Composites

Objectives: The aim of this study was to compare the cytotoxic effects of various dental composites polymerized with two different curing units. Methods: Disc-shaped test samples of composites Filtek Z250, Filtek A110, Filtek P60, Filtek Supreme, and SDI Rok were polymerized using one quartz tungsten halogen (QTH) and one light emitting diode (LED) light curing unit (LCU), namely Optilux 501 (QTH) and Elipar Freelight 2 (LED). L-929 mouse fibroblast cultures (3x104 cells/ml) were incubated with the samples in 96 well culture plates for evaluation after 8, 24, 48, 72 h. At the end of each period, the cells were counted and examined under a light microscope, and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay was performed. The degree of cytotoxicity for each sample was determined according to the reference value represented by the cells in a control group (a culture without sample). Results: A significant 3 factor interaction occurred among LCUs, composites, and time factors (P<.005). In general, the test materials cured with the LED LCU demonstrated higher cell survival rates when compared with those cured with halogen LCUs. Conclusions: This study shows that polymerization of dental composites with a light emitting diode LCU positively influences the L-929 mouse fibroblast cell viability.PubMe

Do Resin Cements Alter Action Potentials of Isolated Rat Sciatic Nerve?

Objectives: The purpose of this study was to explore the effects dual-cure resin cements on nerve conduction. Methods: Panavia F, RelyX ARC, and Variolink II polymerized either by light-emitting diode (LED) or quartz tungsten halogen (QTH) were used in the study (n=10). The conductance of sciatic nerves of 50 rats were measured before and after contact with the specimens for 1 h. Results: The time-dependent change in nerve conductance and the comparison of LED versus QTH showed that differences between groups are significant (P<.05). For both polymerization techniques, pair-wise comparisons of resin cements showed that the nerve conductance between groups is different (P<.05). RelyX ARC elicited irreversible inhibition of compound action potentials (more than 50% change) and Panavia F and Variolink II polymerized by LED and QTH did not alter nerve conduction beyond physiologic limits. Conclusions: Resin cements may alter nerve conductance and even lead to neurotoxic effects.PubMe

Correlation Between Clinical And Magnetic Resonance Imaging Findings In The Treatment Of Anterior Disc Displacement

Purpose: This study aimed to compare the agreement of clinical examination and magnetic resonance imaging (MRI) results before and after the treatment of nonreduction temporomandibular joint (TMJ) disc displacement. Materials and Methods: The study group consisted of 22 patients, each with anterior disc displacement without reduction in at least one TMJ. Diagnosis was performed clinically and with MRI prior to treatment. All patients received the same treatment protocol, consisting of occlusal appliance therapy and exercise for a period of 24 weeks. By the end of treatment, clinical and imaging examinations were repeated and the results subjected to statistical analysis. Results: Before treatment, MRI and clinical examinations matched in 35 of 44 joints (79.5%). On the basis of the kappa index, the agreement between clinical and imaging examinations was moderate (mean kappa index = 0.59, P = .0001). After treatment, these examinations matched in only 16 of 44 cases (36%) and the agreement was poor. Conclusion: Clinical criteria do not necessarily correlate with MRI findings in the postoperative period in patients treated for TMJ anterior disc displacement. Int J Prosthodont 2013;26:138-142. doi: 10.11607/ijp.2692WoSScopu

Effects Of Different Luting Cements And Light Curing Units On The Sealing Ability And Bond Strength Of Fiber Posts

This study evaluated the sealing ability and push-out bond strength of two luting cements cured with two different types of light curing units (LCU): light-emitting diode (LED) versus quartz tungsten halogen (QTH). Forty teeth were divided into four groups (n=10/group). Quartz fiber posts (D.T. Light-Post) were luted to coronal or apical section of root canals using two types of resin cements (Panavia F or RelyX) cured with either LED LCU (Elipar FreeLight II) or QTH LCU (Optilux 501). Highest push-out bond strength was exhibited by QTH-cured RelyX, which was not significantly different from LED-cured RelyX but was higher than QTH-cured Panavia F. The push-out bond strength of Panavia F did not differ with LCU type (p>0.05), but exhibited lower values than both QTH- and LED-cured RelyX. Fluid filtration test revealed that sealing ability was not influenced by luting cement type, but was significantly influenced by LCU type in favor of QTH light source: QTH-cured specimens displayed better seal than LED-cured ones (p<0.05).WoSScopu