transforming-growth-factor-beta and Dental-Pulp-Exposure

This review summarizes the in vivo experiments carried out by our group after implantation of bioactive molecules (matricellular molecules) into the exposed pulp of the first maxillary molar of the rat or the mandibular incisor of rats and mice. We describe the cascade of recruitment, proliferation and terminal differentiation of cells involved in the formation of reparative dentin. Cloned immortalized odontoblast progenitors were also implanted in the incisors and in vitro studies aimed at revealing the signaling pathways leading from undifferentiated progenitors to fully differentiated polarized cells. Together, these experimental approaches pave the way for controlled dentin regenerative processes and repair.

Topics: Amelogenin; Animals; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Cell Differentiation; Cell Movement; Cell Proliferation; Cells, Cultured; Clone Cells; Dental Pulp Exposure; Dentin; Dentin, Secondary; Extracellular Matrix; Integrin-Binding Sialoprotein; Mice; Odontoblasts; Peptide Fragments; Rats; Regeneration; Sialoglycoproteins; Signal Transduction; Stem Cells; Transforming Growth Factor beta; Wound Healing

The purpose of this study was to identify the hard tissue formed early in experimental pulp exposures capped with mineral trioxide aggregate (MTA) or bone morphogenetic protein (BMP)-7 using dentin sialoprotein (DSP) as a marker. The pulps of 35 maxillary first, second, and third molar teeth from 10 male rats were experimentally exposed. The pulps were capped with MTA alone as a pulp-capping agent and final restoration or with BMP-7 followed by restoration with MTA. Five teeth with class I occlusal preparations, no exposure, and no restoration served as positive controls. Five teeth that received pulp exposures and no restoration served as negative controls. Five untreated third molars served as additional controls. The animals were killed at 2 weeks. The specimens were prepared and evaluated histologically and with immunohistochemistry using polyclonal antibodies raised against rat DSP. Pulps capped with MTA formed hard tissue that demonstrated significantly more immunostaining for DSP compared with BMP-7 (p = 0.0031). MTA-capped pulps also showed significantly more complete bridge formation compared with BMP-7 (p = 0.0008). Pulps capped with BMP-7 demonstrated a hard tissue that was bone-like in appearance and devoid of DSP staining.

Topics: Aluminum Compounds; Animals; Biomarkers; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Calcium Compounds; Dental Pulp Capping; Dental Pulp Exposure; Dentin, Secondary; Drug Combinations; Extracellular Matrix Proteins; Immunohistochemistry; Male; Oxides; Phosphoproteins; Protein Precursors; Rats; Rats, Sprague-Dawley; Root Canal Filling Materials; Sialoglycoproteins; Silicates; Transforming Growth Factor beta

Bone morphogenetic protein 7 (BMP 7), also termed osteogenic protein 1, a member of the transforming growth-factor superfamily, was examined for its efficacy in inducing reparative dentinogenesis in the exposed pulps of rat molars. To determine if the reaction was dose-dependent, collagen pellets containing 1, 3 or 10 microgram of recombinant BMP 7 were inserted in intentionally perforated pulps (10-12 pulps per group) in the deepest part of half-moon class V-like cavities cut in the mesial aspect of upper first molars. As controls, the collagen carrier (CC group) alone and calcium hydroxide (Ca group) were used as capping agents. All cavities were then restored with a glass-ionomer cement. Half of the animals were killed after 8 days and the other half after 28 days, by intracardiac perfusion of fixative. The molars were processed for histological evaluation by light microscopy. No difference in effect could be detected between the three concentrations of BMP 7 groups at either time interval. After 8 days, all groups showed varying inflammation, from mild of severe, and the Ca group demonstrated early formation of a reparative dentine bridge. At 28 days the CC group displayed irregular osteodentine formation, leaving some unmineralized areas at the exposure site and interglobular unmineralized areas containing pulp remnants. In the Ca-treated pulps, the initial formation of thick reparative osteodentine bridges that sealed more or less completely the pulp perforation was followed, in the deeper part, by irregular tubular dentine. In most BMP 7-treated specimens, the initial inflammation has resolved at 8 days and at 28 days heterogeneous mineralization or osteodentine filled the mesial coronal pulp. They also had complete filling of the radicular pulp by homogenous mineralization in the mesial root; this reaction was found in 11 teeth in the BMP 7 group, one tooth in the CC group an none of the Ca group. These results emphasize the biological differences the coronal and radicular parts of the pulp, and the potential of bioactive molecules such as BMP 7 to provide an a alternative conventional endodontic treatments.

Topics: Animals; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Calcium Hydroxide; Collagen; Dental Pulp; Dental Pulp Capping; Dental Pulp Exposure; Dentin, Secondary; Dose-Response Relationship, Drug; Humans; Models, Animal; Molar; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Stimulation, Chemical; Tooth Crown; Tooth Root; Transforming Growth Factor beta

The nature and specificity of the mechanisms by which the amputated dentin-pulp interface is therapeutically healed determine the properties of the barrier at this site and play a critical role in the outcome of vital pulp therapy. Healing of the dentin-pulp complex proceeds either by natural repair-which results in defensive hard-tissue formation, or therapeutically regulated dentin regeneration, which aims to reconstitute the normal tissue architecture at the pulp periphery. Progress in biomedical research opens new directions for the design of biologically effective pulp therapies. Application of biocompatible and biodegradable carrier vehicles for local delivery of signaling molecules in pulp-capping situations showed induction of fibrodentin/reparative dentin formation, but often at the expense of underlying pulp tissue. An alternative pre-clinical model aiming to reconstitute normal tissue architecture directly at the dentin-pulp interface should be designed on the basis of the direct induction of odontoblast-like cell differentiation and reparative dentin formation at the pulp-capping material interface. Experimental data clearly showed that pulpal cells can differentiate directly into odontoblast-like cells in association with specific extracellular matrices (dentinal or fibrodentinal matrix) or TGF beta 1-containing artificial substrates. Dentin-induced dentinogenesis can be used as a master plan for the achievement of new therapeutic opportunities. In the present study, several short-term experimental studies on dog teeth for potential direct induction of odontoblast-like cell differentiation at the surface of rhTGF beta 1-containing artificial substrates (Millipore filters, hydroxyapatite granules, calcium hydroxide, pure titanium) failed to induce any specific reparative dentinogenic effects.

Topics: Animals; Biocompatible Materials; Calcium Hydroxide; Cell Differentiation; Dental Pulp; Dental Pulp Capping; Dental Pulp Exposure; Dentin; Dentin, Secondary; Dentinogenesis; Dogs; Drug Carriers; Drug Delivery Systems; Durapatite; Extracellular Matrix; Membranes, Artificial; Micropore Filters; Odontoblasts; Regeneration; Surface Properties; Titanium; Transforming Growth Factor beta; Transforming Growth Factor beta1; Wound Healing

To evaluate the effects of bioactive molecules in pulpal wound healing, we carried out experiments using the rat upper molars as an in vivo model. Cavities were prepared on the mesial aspect, and pulp perforation was accomplished by the application of pressure with the tip of a steel probe. After the pulp-capping procedure, the cavities were filled with a glass-ionomer cement. Comparison was made between and among: (1) sham-operated controls with dentin and predentin fragments implanted in the pulp during perforation after 8, 14, and 28 days; (2) carrier without bioactive substance; (3) calcium hydroxide; (4) Bone Sialoprotein (BSP); (5) different concentrations of Bone Morphogenetic Protein-7 (BMP-7), also termed Osteogenic Protein-1 (OP-1); and (6) N-Acetyl Cysteine (NAC), an anti-oxidant agent preventing glutathione depletion. Histologic and morphometric comparison, carried out among the first 4 groups on demineralized tissue sections, indicated that, at 28 days after implantation, BSP was the most efficient bioactive molecule, inducing homogeneous and well-mineralized reparative dentin. BMP-7 gave reparative dentin of the osteodentin type in the coronal part of the pulp, and generated the formation of a homogeneous mineralized structure in the root canal. These findings indicate that the crown and radicular parts of the pulp bear their own specificity. Both BSP and BMP-7 were superior to calcium hydroxide in their mineralization-inducing properties, and displayed larger areas of mineralization containing fewer pulp tissue inclusions. The overall mineralization process to these molecules appeared to proceed by mechanisms that involved the recruitment of cells which differentiate into osteoblast-like cells, producing a mineralizing extracellular matrix. We also provide preliminary evidence that NAC induces reparative dentin formation in the rat molar model. Pulp-capping with bioactive molecules provides new prospects for dental therapy.

Topics: Acetylcysteine; Animals; Antioxidants; Biocompatible Materials; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Calcium Hydroxide; Dental Pulp; Dental Pulp Capping; Dental Pulp Cavity; Dental Pulp Exposure; Dental Restoration, Permanent; Dentin; Dentin, Secondary; Dentinogenesis; Free Radical Scavengers; Glass Ionomer Cements; Integrin-Binding Sialoprotein; Male; Pharmaceutical Vehicles; Rats; Rats, Sprague-Dawley; Sialoglycoproteins; Time Factors; Transforming Growth Factor beta; Wound Healing

The effects of recombinant basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF)-II and transforming growth factor (TGF)-beta 1 on dental pulp cells were investigated by light and transmission electron microscopy after their implantation for 1 and 3 weeks at central sites of mechanically exposed pulps in dog molar and canine teeth. The implants were Millipore filters that have been soaked with solutions containing 100 or 500 ng/ml of bFGF or IGF-II or 100 ng/ml of TGF-beta 1. Control filters were soaked with dog albumin. No changes in cell organization or matrix synthesis were seen after implantation of control filters. Groups of columnar, polarized cells with numerous mitochondria and Golgi elements or elongated cells unassociated with any matrix deposition were demonstrated after 1 or 3 weeks, respectively, in close proximity to the filters that had been soaked with bFGF solution; at a distance from these implants enhanced formation of an osteotypic matrix was seen beneath the exposure site. No particular response was found in close proximity to the filters that had been soaked with IGF-II solution after 1 or 3 weeks implantation but thick zones of osteodentine were found beneath the exposure site and at adjacent circumferential dentine sites. Numerous elongated, polarized cells with long cytoplasmic extensions invading the filter pores were consistently seen after 1 week in close proximity to the filters that had been soaked with TGF-beta 1 solution. After 3 weeks implantation of these filters, deposition of a tubular matrix surrounding the implants was seen in association with the highly elongated odontoblast-like cells, while enhancement of circumferential dentine formation was also found at adjacent peripheral sites. These experiments demonstrate that TGF-beta 1 when implanted for short term periods at central pulp sites exerted dentine-specific effects, inducing differentiation of odontoblast-like cells and stimulating primary odontoblasts. Implantation of bFGF and IGF-II did not result in reparative dentine formation, but did stimulate osteotypical matrix deposition at a distance from the implants.

Topics: Animals; Cell Differentiation; Cell Polarity; Dental Pulp; Dental Pulp Exposure; Dentinogenesis; Dogs; Extracellular Matrix; Fibroblast Growth Factor 2; Humans; Insulin-Like Growth Factor II; Micropore Filters; Odontoblasts; Recombinant Proteins; Transforming Growth Factor beta