Microtensile bond strength of universal adhesives to flat versus Class I cavity dentin with pulpal pressure simulation.

OBJECTIVES: The aim of this study was to test long-term microtensile bond strength (µTBS) of 2 universal adhesives applied to dentin following "total-etch" (TE) or "self-etch" (SE) protocols and aged by direct or indirect water exposure using simulated pulpal pressure. MATERIALS AND METHODS: Single Bond Universal (SBU, 3M ESPE) or Ipera Bond (IP, Itena) were applied to mid-coronal dentin ("flat dentin") or Class I cavity ("cavity dentin") following TE or SE protocols in 112 extracted human third molars. Sixteen groups (n = 7 per group) were prepared, 8 groups for µTBS measurements after 24 hours, and further 8 groups for measurements after 6 months storage. "Cavity dentin" groups were subjected to simulated hydrostatic pulpal pressure of 15 cm H2 O using a custom-made device before cutting 1 × 1 mm sticks while "flat dentin" groups were cut into sticks and directly exposed to deionized water. RESULTS: Generally, the TE protocol resulted in highest µTBS values on flat dentin initially for both adhesives (general linear model, P < .05). Long-term storage resulted in significantly lower µTBS values for the TE protocol (P < .05) while the SE protocol showed comparable values after 6 months (P > .05). "Cavity dentin" with simulated pulpal pressure resulted in lower µTBS than "flat dentin" (P < .05). For both adhesives, µTBS was in the range of 19-42 MPa initially and 16-36 MPa after 6 months storage. CONCLUSIONS: µTBS to dentin of universal adhesives is more stable in the long term following the SE than TE protocol. Simulated pulpal pressure and cavity-type sample preparation may be recommended for µTBS testing as a more clinically relevant strategy. CLINICAL SIGNIFICANCE: Microtensile bond strength to dentin of universal adhesives appears more stable following the "self-etch" than "total-etch" protocol after long-term degradation. More clinically relevant data may be obtained using simulated pulpal pressure and cavity-type sample preparation in the study design.

Real-time multispectral transmission of hard tooth tissues and dental composites with their heating.

The objective of the study was to investigate the real-time transmission of Violet, Blue, Red and Near Infra-Red (NIR) irradiation through 2 or 4 mm thick dental composites and tooth tissue samples at varying positions of Light Curing Unit (LCU) with polymerization temperature monitoring. METHODS: The composites tested were: Filtek Universal Restorative (FUR), Filtek One Bulk Fill (FBF), Tetric EvoCeram (TEC), Tetric Bulk Fill (TBF) and Tetric PowerFill (TPF). The new LCU Pinkwave (a four-wavelength source manufactured by Vista Apex, USA) was placed either centrally or eccentrically for 3 mm above the sample. A Fiber spectrometer detected irradiation and Infrared Thermal camera polymerization temperatures. RESULTS: All eccentric LCU positions significantly weaken transmitted spectra for all composites in both thickness, jeopardizing Blue light. The LCU position did not affect transmitted irradiation for tooth tissues. The reduction in wavelength intensity when penetrating through thicker compared to thinner composite samples was 62%, 50% and 31% for Blue, NIR and Red, respectively, and 90%, 50% and 35% for tooth tissue samples, respectively. The temperature of bulk fill composites with additional photoinitiators rises faster. Eccentric LCU positions cause a significant decrease in both speed and the maximal value of temperature rise. Red and NIR irradiations contribute to the polymerization temperature. SIGNIFICANCE: Tested LCU source cause considerable inhomogeneity in the emitted and transmitted spectra. Tooth tissues homogenize irradiation, but drastically attenuates it. Red light has better potential than Blue light concerning penetration and could be further investigated as the wavelength for activation of an adjusted photoinitiator.

Assesment of radiotherapy effects on the blood flow in gingiva and dental pulp - a laser Doppler flowmetry study.

OBJECTIVE: This study aims to determine and compare the dental pulp and gingival blood flow in patients referred for oropharyngeal radiotherapy (RT) at three different time points: before the start, immediately after, and six months following the completion of RT. The aim is also to evaluate the dependence of the pulp and gingival blood flow on the radiation dose. METHODOLOGY: A prospective study included 10 patients referred for intensity-modulated RT (IMRT) in the oropharyngeal region, with at least one intact tooth surrounded by a healthy gingiva. The dose received by each selected tooth and adjacent gingiva was determined according to the map of treatment planning and computer systems. The blood flow measurements were performed using the laser Doppler flowmetry (LDF) method. RESULTS: Comparing vascular flows at three different time points, the median blood flow in the dental pulp showed no statistically significant difference (p=0.325), contrary to gingiva (p=0.011). Immediately after RT completion, the gingival flow significantly increased compared to its starting point (p=0.012). The pulp flow correlated negatively with the radiation dose, whereas a strong correlation was noted 6 months following the RT completion. CONCLUSIONS: RT caused a significant acute gingival blood flow increase, followed by a long-term (over six months) tendency to return to the starting levels. The dental pulp blood flow is differently affected by higher radiation doses (over 50Gy) in comparison to lower doses (below 50Gy). During RT planning, considering the possibility of protecting the teeth localized near the Gross Tumor Volume as a sensitive organ is recommended.

Immediate and Long-Term Porosity of Calcium Silicate-Based Sealers.

INTRODUCTION: Open pores between endodontic sealer and root canal walls present potential niches for bacterial growth and migration pathways. The aim was to assess the internal and external porosity of calcium silicate-based sealers and to ascertain the long-term effect of storage in simulated body fluid on sealer porosity. METHODS: Sixteen single-rooted teeth were filled with gutta-percha and 1 of 4 root canal sealers: BioRoot RCS, EndoSequence BC, MTA Fillapex, or AH Plus. Obturated roots, stored in Hank's balanced salt solution, were scanned after 7 days and after 6 months by using micro-computed tomography at an isotropic resolution of 9.9 µm. Total, open, and closed porosity were calculated in the coronal, middle, and apical thirds. Data were statistically analyzed by using general linear model and paired t test (α = 0.05). RESULTS: Significantly higher percentage of open than closed porosity was found in all groups. Initially, significantly greater open and total porosity were found for MTA Fillapex than for AH Plus. After 6 months, the percentage of open and total porosity increased in BioRoot RCS and MTA Fillapex and decreased in AH Plus and EndoSequence BC. Both initially and after storage, coronal region of all sealers had significantly greater total porosity than middle and apical regions, which were comparable. CONCLUSIONS: None of the root fillings were void-free, with predominant open porosity persisting after long-term storage.

Effect of Aging and Carotid Atherosclerosis on Multifractality of Dental Pulp Blood Flow Oscillations.

INTRODUCTION: Age-related changes of dental pulp tissue and atherosclerosis of carotid arteries as its feeding arteries could influence the functionality of pulpal circulation. The objective of our study was to evaluate the effect of aging (physiological process) and carotid bifurcation atherosclerosis (pathologic process) on the pulpal microcirculatory system using multifractal analysis of the laser Doppler flowmetry signal. METHODS: Three groups of 10 subjects were enrolled in the study: the young group (healthy subjects, 20-25 years), the middle-aged group (healthy subjects, 50-60 years), and the clinical group (subjects with carotid bifurcation atherosclerosis, 50-60 years). Pulpal blood flow (PBF) signals recorded by laser Doppler flowmetry were assessed by multifractal analysis that estimates Hölder exponents of the signal. PBF levels, the average mean values, and the range of Hölder exponents were obtained. RESULTS: PBF levels were significantly higher in the young group compared with the middle-aged and clinical groups, and the difference between the middle-aged and clinical groups was not statistically significant. The range of the Hölder exponents was narrower in the middle-aged and clinical groups than in the young group and narrower in the clinical group than in the middle-aged group. The average mean value of Hölder exponents was significantly higher in the young group than in the middle-aged and clinical groups, whereas there was no significant difference between the middle-aged and clinical groups. CONCLUSIONS: Our study investigating the multifractality of the PBF signal showed that the aging process and carotid atherosclerosis could affect the complex structure of PBF oscillations and contribute to a better understanding of pulpal hemodynamics.

Temperature changes in silorane-, ormocer-, and dimethacrylate-based composites and pulp chamber roof during light-curing.

STATEMENT OF THE PROBLEM: Light-curing of resin-based composites (RBCs) is associated with temperature increase in the pulp chamber, which may have a detrimental effect on the vital pulp. PURPOSE: The purpose of the study was to evaluate temperature changes of silorane-, ormocer-, and dimethacrylate-based RBCs at the bottom surface of the RBC and in the pulp chamber roof dentin (PCRD) during curing. MATERIALS AND METHODS: In part A, temperatures were measured for Filtek LS (3M ESPE, St. Paul, MN, USA), Admira (Voco GmbH, Cuxhaven, Germany), and Herculite XRV (Kerr Corp., Orange, CA, USA) with a high-power light-emitting diode (LED) unit by placing thermocouples in contact with the bottom surface of the material in standardized acrylic molds. In part B, temperature changes in PCRD were measured in extracted molars during light-curing of adhesives and RBCs in 2-mm-deep cavities with a remaining dentin thickness (RDT) of 1 mm. RESULTS: Filtek LS showed a different temperature curve compared with Admira and Herculite XRV. Significantly higher temperatures were recorded for Filtek LS (p < 0.001) than for Admira and Herculite XRV in acrylic molds. Temperature rises recorded in PCRD for adhesives and RBCs were between 4.1 and 6.4 degrees C. No significant differences in PCRD temperatures were found between the three groups during adhesive curing and RBC curing (p > 0.05). CONCLUSIONS: Filtek LS showed a different heat-generation pattern from and significantly higher temperatures than Admira and Herculite XRV when the materials were tested in acrylic molds. Similar temperatures were recorded in the PCRD during curing of adhesives and RBCs. CLINICAL SIGNIFICANCE: Although a substantial temperature rise in the bulk material occurred during light-curing of the three resin-based composites, a remaining dentin thickness of 1 mm caused a significant reduction in pulp chamber roof dentin temperatures. Temperatures measured in the pulp chamber roof dentin corresponding to the zone occupied by the postmitotic odontoblast layer were not statistically different for the three types of resin-based composites.

Assesment of radiotherapy effects on the blood flow in gingiva and dental pulp - a laser Doppler flowmetry study

Abstract Objective This study aims to determine and compare the dental pulp and gingival blood flow in patients referred for oropharyngeal radiotherapy (RT) at three different time points: before the start, immediately after, and six months following the completion of RT. The aim is also to evaluate the dependence of the pulp and gingival blood flow on the radiation dose. Methodology A prospective study included 10 patients referred for intensity-modulated RT (IMRT) in the oropharyngeal region, with at least one intact tooth surrounded by a healthy gingiva. The dose received by each selected tooth and adjacent gingiva was determined according to the map of treatment planning and computer systems. The blood flow measurements were performed using the laser Doppler flowmetry (LDF) method. Results Comparing vascular flows at three different time points, the median blood flow in the dental pulp showed no statistically significant difference (p=0.325), contrary to gingiva (p=0.011). Immediately after RT completion, the gingival flow significantly increased compared to its starting point (p=0.012). The pulp flow correlated negatively with the radiation dose, whereas a strong correlation was noted 6 months following the RT completion. Conclusions RT caused a significant acute gingival blood flow increase, followed by a long-term (over six months) tendency to return to the starting levels. The dental pulp blood flow is differently affected by higher radiation doses (over 50Gy) in comparison to lower doses (below 50Gy). During RT planning, considering the possibility of protecting the teeth localized near the Gross Tumor Volume as a sensitive organ is recommended.

Prostaglandin E2 in apical tissue fluid and postoperative pain in intact and teeth with large restorations in two endodontic treatment visits.

INTRODUCTION: Acute periapical inflammation is the most common cause of postoperative pain developing as a result of mechanical, chemical and/or microbial injury of periapical tissue. The major inflammatory event responsible for periapical pain is increased vasodilatation and vascular permeability, partly caused by prostaglandin E2, with consequent edema, which leads to the compression of nerve fibers. OBJECTIVE: The aim of this study was to determine the concentrations of prostaglandin E2 in apical tissue fluid after endodontic treatment of intact and teeth with large restorations and to compare it with the occurrence and intensity of postoperative pain. METHODS: Single-rooted teeth of 24 patients, selected for this study, were distributed into two groups: intact (group 1, n = 27) and asymptomatic teeth with large restorations (group 2, n = 20). Clinical examination of the involved teeth included the electric pulp test, recording pain on percussion, spontaneous pain, and a radiographic examination. Samples of apical tissues fluid were obtained from root canals at two treatment visits, and prostaglandin E2 concentrations were measured using radioimmunoassay. Pain intensity was assessed by visual analogue scale. RESULTS: Prostaglandin E2 concentrations at the second visit, in teeth with large restorations, was significantly higher (36%) than at the first treatment visit (Wilcoxon signed rank test, p < 0.05). Occurrence and intensity of spontaneous pain after the first visit were significantly higher in group 2 (p < 0.05) than in group 1. CONCLUSION: These results suggest that the increased prostaglandin E2 concentration, caused by endodontic treatment of teeth with large restorations, is well correlated with the intensity of postoperative pain.

Dental pulp blood flow and its oscillations in women with different estrogen status.

INTRODUCTION: The skin microcirculation is significantly affected by serum estrogen levels. The objective of this study was to investigate the effects of estrogen serum level changes associated with the menstrual cycle and postmenopause on dental pulp blood flow (PBF) as well as its dynamics. METHODS: Young women at the menstrual phase (low serum estrogen levels) and in the mid-cycle phase of the menstrual cycle (high serum estrogen levels) and postmenopausal women were enrolled in the study. PBF and its oscillations were measured by laser Doppler flowmetry and analyzed by using wavelet transform. Serum levels of estradiol-17ß were measured by immunoassay. RESULTS: PBFs of young women in the menstrual phase and postmenopausal women were mutually similar and significantly lower than those of young women in the mid-cycle period. With respect to the mid-cycle phase, relative amplitude and power were significantly increased in the interval 0.0095-0.02 Hz and decreased in the intervals 0.02-0.06 and 0.06-0.2 Hz in the menstrual phase. A significant decrease in 0.0095-0.02 Hz and increase in 0.02-0.06, 0.06-0.2, 0.2-0.6, and 0.6-1.6 Hz intervals were observed in postmenopause. CONCLUSIONS: The study has shown that the menstrual phase of the menstrual cycle and postmenopause have similar PBF decrease, but PBF oscillations are differently affected in the mid-cycle phase.

Water uptake and solubility of Acroseal sealer in comparison with Apexit and AH Plus sealers in Hank's solution.

INTRODUCTION: The function of root canal fillings is to seal the root canal system. The important physical property necessary for sealers to achieve this is low solubility. However, any therapeutic effect of calcium hydroxide-based sealers is dependent on the calcium hydroxide being in ionized form, which implies that the material must be at least partly soluble. OBJECTIVE: The objective of our study was to compare weight changes of Acroseal and Apexit, conventional calcium hydroxide-based sealer and AH Plus, epoxy-amine resin sealer in Hank's solution at different exposure times. METHODS: The standardized samples of each material were weighed and immersed in the Hank's solution for 1 h, 24 h, 96 h, 14 days and 28 days. After these exposure times, they were removed, dried, and weighed again. Mean weight changes were determined and the differences between sealers were-analysed statistically using a one-way ANOVA. RESULTS: The highest differences in mass were observed in Apexit, 1.52%, and were significantly different from Acroseal, 0.93% (p<0.05) and AH Plus, 0.45% (p<0.05). There were no significant differences between Acroseal and AH Plus, except for 96 h period. CONCLUSION: Under the conditions of our study, it may be concluded that the Acroseal sealer presented the behaviour more like epoxy-based material, AH Plus, than calcium hydroxide sealer, Apexit.