Analysis of the nano and microstructures of the cervical cementum and saliva in periodontitis: A pilot study.

OBJECTIVES: During the progression of periodontitis, the structures of the cementum and saliva are altered due to pathological changes in the environment. This study aimed to analyze the nanostructures of the cervical cementum and saliva in patients with periodontitis. METHODS: Patients with periodontitis (n = 10) and periodontally healthy controls (n = 8) were included. Single-rooted teeth with indications for extraction were obtained from individuals. The cervical-thirds of the roots were sectioned transversely to obtain 1 mm thick sections. Unstimulated whole saliva samples were collected from each individual. The nanostructures of the cementum and saliva were analyzed using small and wide-angle X-ray scattering methods. RESULTS: The mean radius and distance values of the cementum nanoparticles in the periodontitis and control groups were 368 Å and 1152 Å, and 377 Å and 1186 Å, respectively. The mean radius and distance values of the saliva nanoparticles in the periodontitis and control groups were 425 Å and 1359 Å, and 468 Å and 1452 Å, respectively. More wide-angle X-ray scattering profile peaks were observed in the cementum of the controls. Similarities were observed between the 3D profiles of the cementum and the saliva nanoparticles. CONCLUSIONS: According to the results of the present study, (i) the cementum and saliva nanoparticles were of similar size in periodontitis and healthy controls, (ii) the cementum was more crystalline according to the (002) crystallographic plane in controls, and (iii) the similarities in the 3D-profile of the cementum and saliva nanoparticles suggest some interactions between them in the sulcus/periodontal pocket at the nanolevel.

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.

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).

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.

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 (3x10(4) 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.

Vascular smooth muscle contraction/relaxation of rat carotid artery is not altered by bone grafting substitutes in vitro.

PURPOSE: The aim of this study was to explore the effects of various bone grafting substitutes (Osteosponge, Perioglas, Tutoplast, and Surgibone) on vascular smooth muscle tonus. METHODS: Bilateral carotid arteries were removed from rats and contraction/relaxation of isolated vessel rings were measured before and after contact with the biomaterials and then, for dose-dependent epinephrine and papaverin administrations, by a force displacement transducer. The data of each biomaterial group were collected by a computerized system and corresponding software at a sample rate of 1,000 kHz and were converted to contraction force. RESULTS: Vascular contraction forces were influenced in response to biomaterials tested except for Osteosponge (P < 0.05), although the differences between groups were insignificant (P > 0.05). There was a dose-dependent vascular response to epinephrine and papaverine administration upon biomaterial contact (P < 0.05). The dose-dependent vascular responses to epinephrine and papaverine administration were almost similar for all biomaterials tested (P < 0.05), suggesting that the biomaterials led to reversible effects on vascular contraction/relaxation behavior, which resulted in recovery. CONCLUSIONS: Osteosponge, Perioglas, Tutoplast, and Surgibone do not alter vascular smooth muscle tonus and vitality and therefore would, presumably, not jeopardize the angiogenesis of fresh blood vessels and full vascularization during tissue healing.

Surface topography of zirconia implants does not alter action potentials of isolated rat sciatic nerves.

The purpose of this study was to explore the effects of airborne-particle abrasion and selective infiltration etching of a yttrium-partially stabilized tetragonal zirconia polycrystal (Y-TZP) implant surfaces on nerve conduction. Particle-abraded Y-TZP (P/Y-TZP), selective infiltration etched Y-TZP (SIE/Y-TZP), and commercially pure titanium (CP-Ti) were used in the study (n = 5).The compound action potentials of the right and left sciatic nerves of eight sacrificed rats were quantified at the in vitro level. The implants were brought into intimate contact with the nerves and the time required for initiation of compound action potentials (TcAP), depolarization (Dp), repolarization (Rp), and amplitude of evoked compound action potentials (cAPs) were recorded before and after contact with the implants. The difference in cAPs between the basal response and after contact with CP-Ti implant was significant (p < 0.05). Time-dependent changes in cAPs of P/Y-TZP and SIE/Y-TZP groups and their basal nerve responses were similar (p > 0.05). Within- and between-subject comparisons revealed that TcAP, Dp, and Rp values for all groups were similar (p > 0.05). Particle-abraded and selective infiltration-etched zirconia implant surfaces do not alter nerve conduction beyond physiologic limits.