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Aim: To investigate pulp responses after pulpotomy and EDTA conditioning of pulp chamber dentinal walls with or without the placement of a collagenous scaffold in the experimental model of miniature swine teeth. Methodology: Forty‐two fully developed permanent premolars and molars of healthy miniature swines were used. After preparation of pulp exposures through Class I cavities, the tissue of the pulp chamber was completely removed. The haemorrhage was controlled, and the root pulp was protected using a polyurethane film. The circumpulpal pulp chamber dentine was treated for 3 min with normal saline (group 1), or 17% EDTA solution (groups 2 and 3). The film was removed, and the pulp chamber cavities were left empty (groups 1 and 2), or filled with swine collagenous sponge (group 3). The access cavities were restored with a Teflon disc and glass ionomer. Teeth were evaluated histo‐morphologically after 10 weeks. Data were compared using the nonparametric Fisher's exact test. Results: Teeth after treatment of dentine with saline (group 1) were associated with no or only traces of hard tissue formation along the root canal walls. Atubular tertiary dentine deposition in the form of matrix deposition along root canal walls, or dentine bridge formation at the orifice of root canals or complete pulp canal obliteration, was found after treatment of dentine with EDTA in both experiments (groups 2 and 3). Significantly different types of mineralization in the root canals of groups 2 and 3 were seen (P = 0.001). Tissue changes in the pulp cavity, characterized by soft tissue growth and osteodentine or atubular tertiary dentine formation, were only seen after EDTA conditioning of dentine, in 6.2% of the teeth without scaffold and 64.7% of the teeth with scaffold application. Newly deposited mineralized matrix in the pulp chamber was always in continuation with hard tissue deposited in the root canals. Conclusions: The EDTA conditioning of pulp cavity dentinal walls after pulpotomy induced dentinogenic events in the root pulp. Application of collagenous scaffold in the pulp chamber enhanced soft tissue growth and mineralized tissue formation along the treated circumpulpal dentine. [ABSTRACT FROM AUTHOR]

Kalyva M, Papadimitriou S, Tziafas D. Transdentinal stimulation of tertiary dentine formation and intratubular mineralization by growth factors. International Endodontic Journal, 43, 382–392, 2010. Aim To evaluate the effects of recombinant growth factors on tertiary dentine formation and intratubular mineralization after their application on deep dentinal cavities in dog’s teeth. Methodology Treatment included dentinal etching (37% phosphoric acid) and applications of bioactive molecules (1 μg mL−1 TGF-β1, 10 μg mL−1 IGF-1, 10 μg mL−1 bFGF, 10 μg mL−1 OP-1 or 1 μg mL−1 monoclonal anti-human TGF-β1 in phosphate buffered saline, PBS) at the dentinal base of buccal Class V cavities. Control groups were treated with 0.1% dog serum albumin (DSA) in PBS omitting the growth factors. This was performed both with and without dentinal etching. The dentinal responses regarding tertiary dentine formation and intratubular mineralization were assessed after 3 and 8 weeks, respectively, using light and scanning electron microscopy. Some specimens were also subjected to dentine permeability testing. Results The group treated with transforming growth factor-beta1 (TGF-β1) and, to a lesser extent, the one treated with osteogenic protein-1 (OP-1) showed significantly greater ( P < 0.05) tertiary dentine formation and intratubular mineralization over an 8-week period when compared with the control and the other experimental groups. There were no significant differences between groups in reduction in dentine permeability after treatment. Conclusion Treatment of exposed dentinal tubules with biologically active molecules might induce intratubular mineralization and tertiary dentine formation. Further research is needed to substantiate any clinical benefits as opposed to traditional treatments of exposed dentine so as to provide a scientific base for the clinical regulation of dentine reactions. [ABSTRACT FROM AUTHOR]

Aim To evaluate the effects of a self-etching/priming adhesive system, containing the antibacterial monomer 12-methacryloyloxy-dodecylpyridinium bromide (MDPB), on the repair capacity of the pulp-dentine complex in infected cavities in dog's teeth. Methodology Class V cavities with a residual dentine thickness ranging from 0.3–0.8 mm were prepared on the buccal surface of permanent teeth in four dogs. Pulpal exposures were performed in half of the cavities. Millipore filters that had been incubated for 3 h in a 105 milky suspension of a-streptococci were placed in the cavities, which were then filled temporarily. After 24 h, the filters were removed and both the exposed and non-exposed cavities were washed with sterile saline and assigned to four groups which were treated with either the experimental antibacterial adhesive system, or Clearfil SE bond, Dycal and Teflon discs. Stereotype connective tissue reactions (inflammatory cell response and/or tissue necrosis) and pulp-specific reparative tissue responses (reduction of odontoblasts and tertiary dentine formation) were assessed at post-operative periods of 4 and 8 weeks. Results Neither severe inflammation nor tissue necrosis was observed, either in the dentinal cavities or pulpal exposures treated with the self-etch adhesive containing MDPB. Rates of tertiary dentine formation in infected dentinal cavities treated with this system were comparable with those observed after dentine treatment with the Ca(OH)2-based material. Dentinal bridging was not seen in pulpal exposures treated with the experimental adhesive. Conclusions The new antibacterial adhesive system maintained pulp vitality and primary odontoblastic function in infected nonexposed and exposed cavities but interfered with reparative dentine formation in infected pulpal exposures. [ABSTRACT FROM AUTHOR]

The spatial and seasonal variation in the concentration and stable isotopic composition of carbon and nitrogen was studied in Zostera marina (eelgrass) meadows in Roskilde Fjord and Øresund, Denmark. Organic carbon (Corg) and nitrogen (Norg) concentrations in new tissues (leaf, rhizome, roots) ranged from 11 to 40 mmol g-1 C and 0.4 to 3.6 mmol g-1 N, whereas their stable isotopic composition in new leaf ranged from -22‰ to -8‰ (δ13Cleaf) and +7‰ to +20‰ (δ15Nleaf). The δ13Cleaf correlated weakly (r² ∼ 0.3) with the δ13C of total dissolved inorganic carbon (DIC) in the surface waters (δ13CDIC range: -5.4‰ to -0.3‰). The temporal change was more pronounced than the spatial change for Norg, the atomic C:N ratio, and δ13Cleaf but was much smaller for Corg and δ15N;leaf. Eelgrass plants had higher Norg concentrations, lower C:N ratios, and more depleted δ13Cleaf in winter than summer, reflecting the temporal imbalance between inorganic nutrient supply and plant demand imposed by seasonality in the growth rate. The apparent carbon isotope enrichment factor of new leaf relative to external DIC (εeelgrass-DIC range: -12.1‰ to -5.3‰) indicated that eelgrass must be reliant on direct HCO3- uptake, especially during the period of high growth rate (May to September). The steep spatial gradient of δ15N;leaf reflected changes in the isotopic composition of the source of assimilated inorganic nitrogen. The strongly positive δ15N;leaf values measured inside the fjord indicated an anthropogenic origin for inorganic nitrogen, which comes from riverine input (riverine δ15N - NO3- = +11.8‰ ± 1.1‰). [ABSTRACT FROM AUTHOR]

Abstract Aim The objective of the present experiment was to study the early pulpal cell response and the onset of reparative dentine formation after capping application of MTA in mechanically exposed pulps. Methodology Thirty-three teeth from three dogs, 12–18 months of age were mechanically exposed via class V cavities. Light pressure was applied to control haemorrhage. ProRoot MTA (Dentsply Simfra, Paris) was placed at the exposure site and light pressure was applied with a wet cotton pellet. The cavities were restored with amalgam and the pulpal tissue reactions were assessed by light and electron microscopy (transmission and scanning) after healing intervals of 1, 2 or 3 weeks. Results A homogenous zone of crystalline structures was initially found along the pulp–MTA interface, whilst pulpal cells showing changes in their cytological and functional state were arranged in close proximity to the crystals. Deposition of hard tissue of osteotypic form was found in all teeth in direct contact with the capping material and the associated crystalline structures. Formation of reparative dentine (tubular matrix formation in a polar predentine-like pattern by elongated polarized cells) was consistently related to a firm osteodentinal zone. Conclusions The present experiments indicate that MTA is an effective pulp-capping material, able to stimulate reparative dentine formation by the stereotypic defensive mechanism of early pulpal wound healing. [ABSTRACT FROM AUTHOR]

Sea ice brines were collected from a single floe composed of different ice types in the western Weddell Sea in December 2004. The chemical composition of the brines (temperature: 23.4°C to 22.1°C; salinity: 40-63) was examined on seven occasions over 25 days with measurements of dissolved oxygen, dissolved inorganic macronutrients (nitrate plus nitrite, ammonium, phosphorus [DIP], and silicic acid), pH, total alkalinity (AT), dissolved organic carbon (DOC) and nitrogen (DON), total dissolved inorganic carbon (CT), and the stable isotopic composition of CT (d13CT). The in situ pH ranged from 8.41-8.82 on the seawater scale, dissolved oxygen from 212-604 µmol kg-1, nitrate from 0.1-3.1 µmol kg-1, ammonium 0.1-2.4 µmol kg-1, DIP 0.4- 2.0 µmol kg-1, silicic acid 4-80 µmol kg-1, AT 2,690-4,620 µeq kg-1, DOC 115-359 µmol kg-1, DON 8-26 µmol kg-1, CT 2,090-3,550 µmol kg-1, and δ13CT +2.9‰ - +6.4‰. Compared with the chemical composition of surface oceanic water (salinity of 34), the brines had elevated pH, reduced concentrations of dissolved inorganic macronutrients (including carbon), especially dissolved inorganic nitrogen, and were mostly supersaturated with dissolved oxygen with respect to equilibrium with air, whereas the CT was considerably enriched in 13C. The chemical composition of the brines was consistent with internal biological productivity, but there was a lack of a distinctive and uniform relationship among the major dissolved inorganic nutrients typically used for describing biological activity. This was interpreted as the result of varying stoichiometry of biological activity within a very small spatial scale. Modification by abiotic processes was a potential contributing factor, such as degassing acting on the dissolved oxygen concentration. Carbonate mineral formation, acting on AT and CT, was not evident in brines from first-year ice but was apparent in brine from second-year ice. [ABSTRACT FROM AUTHOR]

This study was designed to investigate in vivo i) the role of TGF-beta as an active component of the dentin matrix during induction of reparative dentinogenesis; and ii) the ability of TGF-beta1 isoform to induce dentinogenic events. Dental pulps of dog molars and canines were mechanically exposed, and the following implants were placed intrapulpally for 42 d: i) Demineralized or native autogenous dentin matrix preincubated with a TGF-beta-neutralizing antibody; ii) Millipore filters soaked with solution containing 100 ng/ml of TGF-beta1 from human platelets; iii) biomatrices and filters soaked in control solutions. After incubation of biomatrices with the TGF-beta-neutralizing antibody, demineralized dentin completely lost its inductive activity, while native dentin was only able to stimulate formation of fibrodentin. Millipore filters soaked with TGF-beta1 were consistently surrounded by a thick zone of tubular matrix lined with high columnar polarized cells. The data provide evidence that pulp cells can express their dentinogenic potential in response to an appropriate surface containing exogenous TGF-beta1, and that the dentinogenic activity of dentin matrix may at least partly be ascribed to TGF-beta molecule(s).