In vivo Dentin Remineralization by Calcium-Phosphate Cement

Minimally invasive caries-removal procedures remove only caries-infected dentin and preserve caries-affected dentin that becomes remineralized. Dental cements containing calcium phosphate promote remineralization. This study evaluated the in vivo remineralization capacity of resin-based calcium-phosphate cement (Ca-P) used for indirect pulp-capping. Carious and sound teeth indicated for extraction were randomly restored with the Ca-P base or without base (control), followed by adhesive restoration. Study teeth were extracted after three months, followed by elemental analysis of the cavity floor. Mineral content of affected or sound dentin at the cavity floor was quantified by electron probe micro-analysis to 100-mu m depth. After three months, caries-affected dentin underneath the Ca-P base showed significantly increased calcium and phosphorus content to a depth of 30 mu m. Mineral content of treated caries-affected dentin was in the range of healthy dentin, revealing the capacity of Ca-P base to promote remineralization of caries-affected dentin.

Evaluation of the radiopacity of some commercial and experimental root-end filling materials

Objective. The aim of the present study was to evaluate the radiopacity of 5 root end filling materials (white MTA Angelus, MTA Bio, light-cured MTA, Sealepox RP, and Portland cement clinker with bismuth oxide and calcium sulfate). Method. Five specimens, 10 mm in diameter and 1 mm in thickness according to specification ISO 6876: 2001 were fabricated from each material and radiographed using Insigth occlusal films close to a graduated aluminum step-wedge (2 to 16 mm in thickness). Radiographs were digitized and compared to the aluminum step-wedge. The radiographic density data were converted into millimeters of aluminum (mm Al), using the Digora 1.51 software. Results were evaluated statistically using the analysis of variance (ANOVA) followed by Tukey test. The level of significance was set at 5% (P<.05%). Results. Radiopacity values ranged from 1.21 mm Al (light-cured MTA) to 6.45 mm Al (MTA Angelus). Comparison between materials showed significant difference (P<.05) between MTA Angelus and all other materials, between Sealepox RP and MTA Bio, and between light-cured MTA and Portland cement clinker. Light-cured MTA was significantly less radiopaque than all other materials. No significant difference (P>.05) was found between MTA Bio and Portland cement clinker. Conclusions. All retrograde filling materials evaluated showed greater radiopacity than dentin. All the materials, except light-cured MTA met the minimum radiopacity standards of 3 mm Al recognized by the ISO 6876: 2001 and ADA n.57. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: e35-e38)

The effectiveness of mineral trioxide aggregate, calcium hydroxide and formocresol for pulpotomies in primary teeth

Aim To compare the effectiveness of mineral trioxide aggregate (MTA), calcium hydroxide (CH) and formocresol (FC) as pulp dressing agents in carious primary teeth. Methodology Forty-five primary mandibular molars with dental caries in 23 children [AUTHOR QUERY: How many children?] between 5 and 9 years old were treated by a conventional pulpotomy technique. The teeth were randomly assigned to the experimental ( CH or MTA) or control ( FC) groups. After coronal pulp removal and haemostasis, remaining pulp tissue was covered with MTA paste or CH powder in the experimental groups. In the control group, diluted FC was placed with a cotton pellet over the pulp tissue for 5 min and removed; the pulp tissue was then covered with zinc oxide-eugenol (ZOE) paste. All teeth were restored with reinforced ZOE base and resin modified glass-ionomer cement. Clinical and radiographic successes and failures were recorded at 3, 6, 12, 18 and 24 month follow-up. Results Forty-three teeth were available for follow-up. In the FC and MTA groups, 100% of the available teeth were clinically and radiographically successful at all follow-up appointments; dentine bridge formation could be detected in 29% of the teeth treated with MTA. In the CH group, 64% of the teeth presented clinical and radiographic failures detected throughout the follow-up period, and internal resorption was a frequent radiographic finding. Conclusions Mineral trioxide aggregate was superior to CH and equally as effective as FC as a pulpotomy dressing in primary mandibular molars. Internal resorption was the most common radiographic finding up to 24 month after pulpotomies performed with CH.

Effect of laser phototherapy on the release of fibroblast growth factors by human gingival fibroblasts

The effects of laser phototherapy on the release of growth factors by human gingival fibroblasts were studied in vitro. Cells from a primary culture were irradiated twice (6 h interval), with continuous diode laser [gallium-aluminum-arsenium (GaAlAs), 780 nm, or indium-gallium-aluminum-phosphide (InGaAlP),_660 nm] in punctual and contact mode, 40 mW, spot size 0.042 cm(2), 3 J/cm(2) and 5 J/cm(2) (3 s and 5 s, respectively). Positive [10% fetal bovine serum (FBS)] and negative (1%FBS) controls were not irradiated. Production of keratinocyte growth factor (KGF) and basic fibroblast growth factor (bFGF) was quantified by enzyme-linked immunosorbent assay (ELISA). The data were statistically compared by analysis of variance (ANOVA) followed by Tukey`s test (P a parts per thousand currency signaEuro parts per thousand 0.05). The characterization of the cell line indicated a mesenchymal nature. KGF release was similar in all groups, while that of bFGF was significantly greater (1.49-times) in groups treated with infra-red laser. It was concluded that increased production of bFGF could be one of the mechanisms by which infra-red laser stimulates wound healing.

gamma-Radiation induces apoptosis via sarcoplasmatic reticulum in guinea pig ileum smooth muscle cells

We investigated the effects of gamma-radiation on cells isolated from the longitudinal smooth muscle layer of the guinea pig ileum, a relatively radioresistant tissue. Single doses (up to 50 Gy) reduced the amount of sarcoplasmatic reticulum and condensed the myofibrils, as shown by electron microscopy 3 days post-irradiation. After that, contractility of smooth muscle strips was reduced. Ca(2+) handling was altered after irradiation, as shown in fura-2 loaded cells, with elevated basal intracellular Ca(2+), reduced amount of intrareticular Ca(2+), and reduced capacitive Ca(2+) entry. Radiation also induced apoptosis, judged from flow cytometry of cells loaded with proprium iodide. Electron microscopy showed that radiation caused condensation of chromatin in dense masses around the nuclear envelope, the presence of apoptotic bodies, fragmentation of the nucleus, detachment of cells from their neighbors, and reductions in cell volume. Radiation also caused activation of caspase 12. Apoptosis was reduced by the administration of the caspase inhibitor Z-Val-Ala-Asp-fluoromethyl-ketone methyl ester (Z-VAD-FIVIK) during the 3 day period after irradiation, and by the chelator of intracellular Ca(2+), 1,2-bis(o-aminophenoxy)ethane-N,N,N`,N`-tetraacetic acid (BAPTA), from 1 h before until 2 h after irradiation. BAPTA also reduced the effects of radiation on contractility, basal intracellular Ca(2+), amount of intrareticular Ca(2+), capacitative Ca(2+) entry, and apoptosis. In conclusion, the effects of gamma radiation on contractility, Ca(2+) handling, and apoptosis appear due to a toxic action of intracellular Ca(2+). Ca(2+)-induced damage to the sarcoplasmatic reticulum seems a key event in impaired Ca(2+) handling and apoptosis induced by gamma-radiation. (c) 2008 Elsevier B.V. All rights reserved.

Cytotoxic effects and pulpal response caused by a mineral trioxide aggregate formulation and calcium hydroxide

Purpose: To evaluate: the in vivo pulpal response after pulpotomy with different capping agents. In addition, the in vitro cytotoxic effects of both materials were assessed by applying them on culture of pulp cells. Methods: For the in vivo test, the coronal pulp of 28 teeth of dogs was mechanically removed and the root pulps were capped with the following dental materials: Group 1: Pro-Root NITA (PRMTA); and Group 2 (control): calcium hydroxide saline paste (CH). After 60 days, the animals were sacrificed and the teeth processed for histological analysis. In the in vitro test, experimental extracts obtained from both capping agents were applied on the cultured MDPC-23 odontoblast-like cells. Results: In the root pulps capped with PRMTA or CH, coagulation necrosis partially replaced by dystrophic calcification as well as tubular dentin matrix laid down by elongated pulp cells was observed. None or mild inflammatory response occurred beneath the capped pulpal wound. Regarding the pulpal response, PRMTA and CH presented no statistical difference. However, the teeth capped CH presented greater healthy pulp loss which resulted in convex shape of the hard barrier than PRMTA. When applied on the cultured cells, it was demonstrated that PRMTA and CH solutions decreased the cell metabolic activity by 9.9% and 29.4%, respectively. CH caused higher cytotoxic effects to the MDPC-23 cells as well as deeper healthy pulp tissue loss than PRMTA. However, similar sequence of healing occurred after pulpotomy with both dental materials.

Protective effect of different tetrafluorides on erosion of pellicle-free and pellicle-covered enamel and dentine

The aim was to analyze the protective effects of titanium, zirconium and hafnium tetrafluorides on erosion of pellicle-free and pellicle-covered enamel and dentine in vitro. Eight groups of 20 specimens each of bovine enamel and bovine dentine were prepared. Half the specimens in each group were immersed in human saliva for 2 h for pellicle formation. Specimens were then left untreated (controls) or were treated for 120 s with TiF(4), ZrF(4) or HfF(4) solutions (0.4 or 1%) or 1.25% AmF/NaF gel. All specimens were eroded by exposure to hydrochloric acid, pH 2.6, for 25 min. Cumulative calcium release into the acid was monitored in consecutive 30-second intervals for 5 min, then at 2-min intervals up to a total erosion time of 25 min using the Arsenazo III procedure. Data were analyzed by ANOVA. 1% TiF(4) solution offered the best protective effect, especially in dentine (reduction of calcium loss about 50% at 25 min). 1% ZrF 4, 1% HfF 4 and 0.4% TiF(4) also reduced calcium loss, but to a lesser extent. Long-term effects were limited to dentine, while reduction of enamel erosion (about 25%) was restricted to 1-min erosion. The fluoride gel had a protective effect only in dentine. The efficacy of the tetrafluorides was influenced by the presence of the pellicle layer, in that the protection against dentine erosion by TiF(4) and ZrF(4) was greater on pellicle-covered specimens. Tetrafluoride solutions, especially 1% TiF(4), could decrease dental erosion, but were more effective on dentine than on enamel. Copyright (C) 2008 S. Karger AG, Basel.

Kisspeptin Regulates Prolactin Release through Hypothalamic Dopaminergic Neurons

Prolactin (PRL) is tonically inhibited by dopamine (DA) released from neurons in the arcuate and periventricular nuclei. Kisspeptin plays a pivotal role in LH regulation. In rodents, kisspeptin neurons are found mostly in the anteroventral periventricular and arcuate nuclei, but the physiology of arcuate kisspeptin neurons is not completely understood. We investigated the role of kisspeptin in the control of hypothalamic DA and pituitary PRL secretion in adult rats. Intracerebroventricular kisspeptin-10 (Kp-10) elicited PRL release in a dose-dependent manner in estradiol (E2)-treated ovariectomized rats (OVX+E2), whereas no effect was found in oil-treated ovariectomized rats (OVX). Kp-10 increased PRL release in males and proestrous but not diestrous females. Associated with the increase in PRL release, intracerebroventricular Kp-10 reduced Fos-related antigen expression in tyrosine hydroxylase-immunoreactive (ir) neurons of arcuate and periventricular nuclei in OVX+E2 rats, with no effect in OVX rats. Kp-10 also decreased 3,4-dihydroxyphenylacetic acid concentration and 3,4-dihydroxyphenylacetic acid-DA ratio in the median eminence but not striatum in OVX+E2 rats. Double-label immunofluorescence combined with confocal microscopy revealed kisspeptin-ir fibers in close apposition to and in contact with tyrosine hydroxylase-ir perikarya in the arcuate. In addition, Kp-10 was not found to alter PRL release from anterior pituitary cell cultures regardless of E2 treatment. We provide herein evidence that kisspeptin regulates PRL release through inhibition of hypothalamic dopaminergic neurons, and that this mechanism is E2 dependent in females. These findings suggest a new role for central kisspeptin with possible implications for reproductive physiology. (Endocrinology 151: 3247-3257, 2010)

X-ray fluorescence with synchrotron radiation to elemental analysis of lead and calcium content of primary teeth

Primary teeth were analyzed by micro-SRXRF. The aim of this study was to determine the elemental distribution of lead and calcium in different regions of primary incisor of children living in a notoriously contaminated area (Santo Amaro da Purificacao, Bahia State, Brazil). The measurements were performed in standard geometry of 45 incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). (C) 2009 Elsevier Ltd. All rights reserved.

Treatment With a Growth Factor-Protein Mixture Inhibits Formation of Mineralized Nodules in Osteogenic Cell Cultures Grown on Titanium

Despite wide clinical application, the efficacy of platelet-rich plasma (PRP) for repairing bone defects and enhancing osseointegration of metal implants is still subject of debate. This study aimed to evaluate the effects of a well-defined PRP-like mixture containing platelet-derived growth factor-BB, transforming growth factor (TGF)-beta 1, TGF-beta 2, albumin, fibronectin, and thrombospondin [growth factors (GFs) + proteins] on the development of the osteogenic phenotype on titanium (Ti) in vitro. Human alveolar bone-derived osteoblastic cells were subcultured on Ti discs and exposed during the first 7 days to osteogenic medium supplemented with GFs + proteins and to osteogenic medium alone thereafter up to 14 days. Control cultures were exposed to only osteogenic medium. Dose-response experiments were carried out using rat primary calvarial cells exposed to GFs + proteins and 1:10 or 1:100 dilutions of the mixture. Treated human-derived cell cultures exhibited a significantly higher number of cycling cells at days 1 and 4 and of total cells at days 4 and 7, significantly reduced alkaline phosphatase (ALP) activity at days 4, 7, and 10, and no Alizarin red-stained areas (calcium deposits) at day 14, indicating an impairment in osteoblast differentiation. Although the 1:10 and 1:100 dilutions of the mixture restored the proliferative activity of rat-derived osteogenic cells to control levels and promoted a significant increase in ALP activity at day 10 compared with GFs + proteins, mineralized nodule formation was only observed with the 1:100 dilution (similar to 50% of the control). These results showed that a PRP-like protein mixture inhibits development of the osteogenic phenotype in both human and rat osteoblastic cell cultures grown on Ti. (J Histochem Cytochem 57:265-276, 2009)

Determination of para-Chloroaniline and Reactive Oxygen Species in Chlorhexidine and Chlorhexidine Associated with Calcium Hydroxide

The aim of this study was to determine whether para-chloroaniline (PCA) and/or reactive oxygen species (ROS) are generated by chlorhexidine (CHX) alone or after CHX is mixed with calcium hydroxide at different time points. Mass spectrometry was performed to detect PCA in samples of 0.2% CHX and Ca(OH)2 mixed with 0.2% CHX. High-performance liquid chromatography was used to confirm the presence of CHX in the mixture with Ca(OH)2. The samples were analyzed immediately after mixing and after 7 and 14 days. During the intervals of the experiment, the samples were maintained at 36.5 degrees C and 95% relative humidity. PCA was detected in the 0.2% CHX solution after 14 days. The mixture of CHX with Ca(CH)2 liberated ROS at all time points, but no traces of CHX were present in the mixture as a result of immediate degradation of the CHX. (J Endod 2008;34:1508-1514)

Radiopacity Evaluation of Calcium Aluminate Cement Containing Different Radiopacifying Agents

Introduction: The aim of this study was to evaluate the radiopacity of calcium aluminate cement (Endo Binder) with 3 different radiopacifiers (bismuth oxide, zinc oxide, or zirconium oxide) in comparison with gray mineral trioxide aggregate (GMTA), white MTA, and dental structures (enamel and dentin). Methods: Eighteen test specimens of each cement with thicknesses of 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm (n = 3) were made by using a stainless steel matrix and were adapted to a standardizing device (8 x 7 cm) with a graduated aluminum stepwedge varying from 2.0-16.0 mm in thickness. To compare the radiopacity of the cements with that of dental structures, slices of first molars with a thickness increasing from 0.5-3.0 mm were obtained and placed on the standardizing device. One occlusal radiograph for each tested cement was taken, with exposure time of 0.1 seconds and focus-film distance of 20 cm. Films were processed in an automatic device, and the mean radiopacity values were obtained by using a photodensitometer. Results: Mean values showed that the thicker the specimen was, the greater was its radiopacity. Only EndoBinder + bismuth oxide (EBBO) and GMTA demonstrated radiopacity values greater than 3.0 mm of the aluminum scale for all thicknesses. When zinc oxide was used as radiopacifier agent, EndoBinder only reached the desired radiopacity with a thickness of 2.0 mm, and with zirconium oxide it was 2.5 mm. Conclusions: Bismuth oxide was the most efficient radiopacifier for EndoBinder, providing adequate radiopacity in all studied thicknesses, as recommended by ISO 6876, being similar to GMTA. (J Endod 2011;37: 67-71)

Localization of neurotransmitters and calcium binding proteins to neurons of salamander and mudpuppy retinas

We wished to identify the different types of retinal neurons on the basis of their content of neuroactive substances in both larval tiger salamander and mudpuppy retinas, favored species for electrophysiological investigation. Sections and wholemounts of retinas were labeled by immunocytochemical methods to demonstrate three calcium binding protein species and the common neurotransmitters, glycine, GABA and acetylcholine. Double immunostained sections and single labeled wholemount retinas were examined by confocal microscopy. Immunostaining patterns appeared to be the same in salamander and mudpuppy. Double and single cones, horizontal cells, some amacrine cells and ganglion cells were strongly calbindin-immunoreactive (IR). Calbindin-IR horizontal cells colocalized GABA. Many bipolar cells, horizontal cells, some amacrine cells and ganglion cells were strongly calretinin-IR. One type of horizontal cell and an infrequently occurring amacrine cell were parvalbumin-IR. Acetylcholine as visualized by ChAT-immunoreactivity was seen in a mirror-symmetric pair of amacrine cells that colocalized GABA and glycine. Glycine and GABA colocalized with calretinin, calbindin and occasionally with parvalbumin in amacrine cells. (C) 2001 Elsevier Science Ltd. All rights reserved.