Dog Pulp Research Articles

Induction of dentine in amputated pulp of dogs by recombinant human bone morphogenetic proteins-2 and -4 with collagen matrix

Recombinant human bone morphogenetic protein (BMP)-2, BMP-4 and transforming growth factor (TGF)- β 1 combined with collagen matrix as a carrier were examined for their effects on pulp regeneration and dentine formation. Seventy days after implantation of 2 μg of BMP-2, mineralized osteodentine-like tissue containing embedded osteodentinocytes was seen in the cavity. Unmineralized fibrous tissue and pulp-like loose connective tissue were also found in the same cavity. In teeth implanted with 660 ng of BMP-2 only unmineralized fibrous and pulp tissues were seen. In teeth with 220 ng of BMP-2 or collagen alone, pulp tissue was seen. It is therefore likely that the cavity fills with pulp tissue and that spindle-shaped cells elaborate extracellular matrix that mineralizes to be osteodentine in a dose-dependent manner. Similar osteodentine was seen in teeth implanted with 4 μg of BMP-4 and collagen. No distinct tubular dentine was formed, unlike an earlier experiment in which BMP-2 or -4 was implanted with enriched, inactivated dentine matrix. These findings suggest that both BMP-2 and -4 induce osteodentine formation if combined with collagen matrix; some other matrix component present in inactivated dentine matrix might be essential for further differentiation into odontoblasts. In teeth implanted with TGF- β 1, the carrier collagen remained in the cavity and little pulp tissue proliferation was seen, suggesting a possible inhibitory effect of TGF- β 1 in pulp regeneration. It is likely that the response to growth and differentiation factors is dependent on the state of differentiation of pulp cells.

Copper-zinc superoxide dismutase in human and animal dental pulp

The activity of the enzyme superoxide dismutase, scavenger of the superoxide anion (O 2 dot − ), was assayed in the normal dental pulp of man, dog, rabbit and pig. Very low levels of Cu-Zn-containing superoxide dismutase found in the pulpal tissue investigated support the hypothesis of a relationship between the reactivity of the dental pulp to inflammatory processes and a low protection against oxy-radicals.

Enamel surface roughness and dental pulp response to coaxial carbon dioxideneodymium: YAG laser irradiation

The purpose of this study was to evaluate the effect of a coaxial carbon dioxide/neodymium : yttrium aluminium garnet laser beam on enamel surface roughness and the dental pulps of mongrel dogs. In four dogs, four maxillary left posterior teeth were irradiated at 16 cm source-tooth distances. Two teeth were irradiated with 16 W CO 2,/16 W Nd : YAG and the remaining two with 16 W CO 2,/40 W Nd : YAG. Two maxillary right teeth were untreated controls. In addition, mandibular premolars were irradiated at the same distance and power levels, extracted, and analysed for surface roughness. Significant differences in surface roughness were found between control samples and either power level, but not between enamel surfaces at the two power levels. Maxillary teeth were removed at 10 days postoperatively, sectioned and stained (H > E). The reaction of pulpal cells to irradiation was scored. Data analysis revealed statistically significant differences between the control and lower power Nd : YAG groups and between the control and higher power Nd : YAG groups. The difference in pulpal response between both laser groups approached significance.

Dentin induction by implants of autolyzed antigen-extracted allogeneic dentin on amputated pulps of dogs.

Implantation of autolyzed antigen-extracted allogeneic (AAA) dentin matrix gelatin powder caused homeoinduction on amputated dental pulps. This event began with migration of spindle-shaped mesenchymal cells into the cavity on the amputated pulp. This was followed by proliferation of undifferentiated large cells concomitantly with vascular invasion and attachment of spindle-shaped cells and large cells to the AAA dentin. The adhering cells differentiated into osteodentinoblasts and/or preodontoblasts to form osteodentin matrix and predentin respectively. Osteodentinocytes and odontoblasts, then, formed osteodentin and tubular dentin. The healing of pulp dressed with inactivated AAA dentin using guanidine HCl was delayed. These results suggested that AAA dentin matrix powder may have chemotactic and mitogenic activity for undifferentiated mesenchymal cells and may provide a suitable scaffolding for fixation of these cells. Compartments of microenvironment formed by AAA dentin and the enveloping hard substances may play some role in differentiation into odontoblasts.

Antibody formation to dog pulp tissue altered by a paste containing paraformaldehyde.

Pulpotomy treatment was performed weekly on the teeth of four dogs for 5 weeks. Antibody formation to pulp tissue altered by paraformaldehyde paste within the pulp cavity was measured by enzyme linked immunosorbent assays (ELISA). The results indicated that the reaction between antigen and antibody did occur when pretreatment or post-treatment serum reacted with the antigen of either the pulp tissue incubated with saline or that incubated with paraformaldehyde paste. No evidence was found to prove that antibody formation was related to the pulpotomy treatment with paraformaldehyde paste.

Dental pulp exposed to the CO2 laser beam.

Traumatic inflammation due to application of CO2 laser beam on teeth (dentin and pulp) of Beagle dogs and Macaca Monkeys, stimulate in dentino-pulpal tissue morphological phenomena studied after 5 days, 1, and 3 months by microscopy and microradiography. After a dentin exposure to a density of energy from 2 X 10(3) J/cm2, the first cell layers of the pulp tissue show a rarefaction and a cellular degeneration, followed by a neoformation of calcified dentin, of about 300 microns thick in 3 months, due to the excitation of odontoblasts or produced by pulpal cells functioning before. A density of energy of 10(3) J/cm2 order applied to the pulp beads to its partial necrosis, to various inflammatory aspects and to a quasi-constant regeneration by a neo-dentin bridge of 200 microns at 1 month. The analysis of cell activity seems able to be investigated from this method.

Arachidonic acid metabolism in canine tooth pulps and the effects of nonsteroidal anti-inflammatory drugs

Dental pulps of mongrel dogs were irritated by removal of the enamel and dentin without use of any coolants. After 48 h, the pulps were extirpated, frozen in liquid nitrogen, and the concentrations of arachidonic acid metabolites were determined by thin-layer chromatography and radioimmunoassay. The untreated pulps of contralateral teeth served as control tissue specimens. In addition, treated and control pulps were incubated with six nonsteroidal anti-inflammatory drugs and the concentrations of arachidonic acid metabolites were determined using the same techniques. The results show significant increases in the endogenous levels and rates of biosynthesis of arachidonic acid metabolites in treated as contrasted with control tissue samples. Furthermore, significant inhibition of the synthesis of arachidonic acid metabolites was observed when nonsteroidal anti-inflammatory drugs were added to pulp homogenates. Dental pulps of mongrel dogs were irritated by removal of the enamel and dentin without use of any coolants. After 48 h, the pulps were extirpated, frozen in liquid nitrogen, and the concentrations of arachidonic acid metabolites were determined by thin-layer chromatography and radioimmunoassay. The untreated pulps of contralateral teeth served as control tissue specimens. In addition, treated and control pulps were incubated with six nonsteroidal anti-inflammatory drugs and the concentrations of arachidonic acid metabolites were determined using the same techniques. The results show significant increases in the endogenous levels and rates of biosynthesis of arachidonic acid metabolites in treated as contrasted with control tissue samples. Furthermore, significant inhibition of the synthesis of arachidonic acid metabolites was observed when nonsteroidal anti-inflammatory drugs were added to pulp homogenates.

The excitability of dog pulp nerves in relation to the condition of dentine surface

Sixteen intradental A-fiber units (cv 24.5±4.8 (SD)m/s) were identified with monopolar electrical stimulation of the dog's canine tooth. All of the units were activated by drilling and probing of dentine, 15 units by air blasts. Scanning electron microscopy of epoxy resin replicas and specimens of dentine showed that after acid etching of dentine, the apertures of dentinal tubules were open. Accordingly, nerve responses to probing and air blasts could be easily evoked. After drilling and resin or potassium oxalate impregnation, the apertures were partly or completely blocked and nerve responses were weak or totally absent. The results indicate that intradental A-fibers are responsible for dentine sensitivity. The responsiveness of these fibers can be affected by obstructing and opening the dentinal tubules.

Histological investigation of the effect of a controlled-released anti-inflammatory drug on exposed inflamed dog pulps

The effect of controlled release of the antipholgistic benzydamine hydrochloride (Tantum®), from two carriers, Cavit W and Durelon, on inflammtory and necrotic tissue changes was investigated on intentionally inflamed pulps of dogs. Statistical tests to detect differences in biocompatibility between Cavit and Durelon, both without drug, led to the conclusion of a similar biocompatibility as determined after 2 and 7 days. Benzydamine hydrochloride appeared to reduce necrosis during the period from 2–7 days slightly with Cavit as carrier and substantially with Durelon as carrier. However, in the latter case necrosis was enhanced after 2 days. During the same period inflammatory reaction was decreased at 10% level of significance by Durelon containing benzydamine hydrochloride. It was decreased significantly after 2 days with Cavit as carrier. Controlled release of benzydamine hydrochloride from Cavit or Durelon which was placed on an exposed inflamed pulp was effective in reducing inflammatory reaction and necrosis.

Measurement of blood flow in the dental pulp of dogs with the 133xenon washout method

Following rapid injection of 133Xe into the maxillary artery, the radioactivity from a dog canine tooth was monitored with a specially-designed scintillation probe connected to a multichannel analyser. With a PDP 11 10 municomputer, the semilogarithmic radioactivity-time curve was resolved into a fast component and a slow component using best fit least-square lines and the exponential rate constant ( k) was determined for each component. The blood flow per unit of pulp mass ( Q, in ml/min per 100g) was obtained using the equation: Q = k · λ tb′ , where λ tb is the tissue-blood partition coefficient of 133Xe in the pulp determined for the haematocrit value of the individual experiments. The fast-component blood flow was 53.12 ± 3.12 and the slow-component blood flow was 8.86 ± 0.53 ml/min per 100 g (mean ± SEM, n = 21). Although the exact anatomical areas for the fast and slow components are yet to be determined, the results show heterogeneity of blood flow in the pulp. The study showed that pulp blood flow in an intact tooth can be measured with the 133Xe washout method; the method enables study of circulatory physiology of the pulp in health and disease.

Effects of electrosurgery on dog pulps under cervical metallic restorations

Fifty-four Class V amalgam restorations were placed in nine beagle dogs to determine whether electrosurgical effects on pulp tissue could be altered by the presence of metallic restorations. An electrosurgical technique was performed, simulating clinical procedures for tissue removal while traversing the restorations. Time and power-use measurements were recorded for each operation. All operations that were performed within a time range imitating clinical procedures failed to produce changes in pulpal histology. When electrosurgical exposures were extended beyond 0.4 second contact with restorations, pulpal alterations occurred in the majority of specimens.

Comparison of calcium hydroxide and zinc oxide and eugenol pulpectomies in primary teeth of dogs

The purpose of this investigation was to compare calcium hydroxide with zinc oxide and eugenol (ZOE) as root canal obturants in the pulpectomy procedure for irreversibly inflamed primary pulps of dogs. Clinical, radiographic, and histologic comparisons of calcium hydroxide and ZOE root canal filling materials were made in forty-two primary premolars of seven mongrel puppies. When the animals were 6 weeks of age, the pulps of all sample teeth were extirpated and the canals left open to the oral environment. The root canals were assigned to calcium hydroxide, ZOE, and control groups, instrumented, and filled 2 weeks later. The animals were killed 1 day, 1 week, 4 weeks, and 12 weeks after filling. Statistical analysis of all categories for comparison at 4 weeks indicated that calcium hydroxide gave significantly more favorable results than ZOE. Canals treated with calcium hydroxide exhibited less inflammation, less resorption, and more hard-tissue apposition than ZOE-treated and control groups.

Cell-mediated immune response to dog pulp tissue altered by Proco-Sol via the root canal

Pulp tissue from three experimental dogs was tested for its antigenicity before and after incubation with Proco-Sol sealer (PS). Cell-mediated skin test reactions showed an increased response to pulp that had been incubated in Proco-Sol, washed, and then injected, as compared with pulp or PS alone. In vitro analysis of cell-mediated immune response (lymphocyte proliferation) showed a marked increase when pulp tissue was incubated in PS and washed, as compared to saline-treated pulp. Comparison of the saline-incubated pulp to the PS-altered pulp indicated that the increase in radioactivity was statistically significant at p < 0.0001. Thus, Proco-Sol sealer altered dog pulp tissue and rendered it antigenically active, and a specific cell-mediated lymphocyte response was produced.

Antibody formation and cell-mediated immunity to dog pulp tissue altered by eight endodontic sealers via the root canal.

The authors wish to thank Dr James Wolf, Daniel Green, Mr Buddy Hudson, and the entire staff of the Animal Surgical Research Laboratory, McGuire VA Hospital, Richmond, Virginia. This project was supported by Animal Surgical Research Funds, McGuire Veterans Hospital, Richmond, Virginia.

A scanning electron microscope study of the blood vessels of dog pulp using corrosion resin casts

<h2>Summary</h2> Vascular casts of dog pulps using a low-viscosity synthetic resin were examined stereoscopically under the SEM. The corrosive resin cast method provides a way to view the detailed network arrangement of pulpal microvascular beds. The anatomical heterogeneity of the vascular network within the pulp, for instance, the coronal vs the apical and the peripheral vs the central pulps, is clearly shown. The study also shows numerous apical foramens with each foramen occupied by only one type of vessel, either an arteriole or a venule. The presence of the arteriovenous anastomosis, the venous-venous anastomosis, and the U shaped arterioles may be features unique to the pulpal vascular network.

Migration of materials and microorganisms in the dental pulp of dogs and rats

Data from a wide range of studies on pulp response to materials in rats and dogs and a series of gnotobiotic experiments designed to investigate pulp response to caries have been reviewed for evidence of migration of materials and bacteria within the pulp. Migration of materials after direct pulp capping was unusual in the rat molar pulp. In the dog, by contrast, migration of materials from direct pulp capping sites was frequently observed. When material particles were contained within phagocytic cells, there was little evidence of any pulp response; free material within the tissues was frequently associated with inflammation or necrosis. In the gnotobiotic studies, phagocytosis of strains of Streptococcus mutans by the pulp in carious teeth was seen.

Dentin hydraulic conductance: changes produced by red blood cells.

Red blood cells were forced into dentinal tubules in vitro under known hydrostatic pressures. This resulted in a 1 7-fold fall in the hydraulic conductance of dentin. The histologic appearance of red blood cells forced into dentin in vitro was very similar to that found in dog pulps following full crown preparations without adequate cooling in vivo.

Antibody formation to dog pulp tissue altered by camphor paramonochlorophenol via the root canal

Pulp tissue from three experimental dogs was tested for its antigenicity before and after incubation with CMCP. Reaction to Arthus skin tests showed an increased response to pulp that had been incubated in CMCP, washed, then injected, as compared with pulp or CMCP alone. Hemagglutinating antibody titers (1:360 to 1:450 dilutions) were obtained from pulp tissue altered by CMCP. Inhibition tests showed the specificity of the antibody to be at a dilution titer of 1:350. Therefore, CMCP altered dog pulp tissue and rendered it antigenically active, and a specific humoral response was produced.

Pulp capping: influence of the exposure site on pulp healing-histologic and radiographic study in dogs' pulp

Pulps of dogs' teeth were exposed buccally and occlusally and capped with calcium hydroxide powder. On the 22nd and 120th postoperative days the teeth were examined histologically and radiographically. Calcium hydroxide powder stimulated pulp healing and calcified bridge formation as early as 22 days for both exposure groups. Results were equally favorable after the 120th day with both buccal and occlusal cappings. Pulps of dogs' teeth were exposed buccally and occlusally and capped with calcium hydroxide powder. On the 22nd and 120th postoperative days the teeth were examined histologically and radiographically. Calcium hydroxide powder stimulated pulp healing and calcified bridge formation as early as 22 days for both exposure groups. Results were equally favorable after the 120th day with both buccal and occlusal cappings.

Effect of calcium hydroxide in powder or in paste form on pulp-capping procedures: Histopathologic and radiographic analysis in dog's pulp

The pulps of seventy dog teeth were evaluated histopathologically and radiographically following intentional exposure and treatment with either a calcium hydroxide powder or a calcium hydroxide paste prepared with distilled water. The results were recorded after periods of 2, 30, 70, and 120 days. No differences were detected in the pulpal responses to direct pulp capping achieved with a calcium hydroxide paste and with a calcium hydroxide powder.