piR-368 promotes odontoblastic differentiation of dental papilla cells via the Smad1/5 signaling pathway by targeting Smurf1

PURPOSE

The important role of non-coding RNAs in odontoblastic differentiation of dental tissue-derived stem cells has been widely demonstrated; however, whether piRNA (a subclass of non-coding RNA) involved in the course of odontoblastic differentiation is not yet available. This study aimed to investigate the expression profile of piRNA during odontogenic differentiation of mDPCs and the potential molecular mechanism in vitro.

MATERIALS AND METHODS

The primary mouse dental papilla cells (mDPCs) were isolated from the first molars of 1-day postnatal Kunming mice. Then, they were cultured in odontogenic medium for 9 days. The expression profile of piRNA was detected by Small RNA sequencing. RT-qPCR was used to verify the elevation of piR-368. The mRNA and protein levels of mineralization markers were examined by qRT-PCR and Western blot analysis. Alkaline phosphatase (ALP) activity and alizarin red S staining were conducted to assess the odontoblastic differentiation ability.

RESULTS

We validated piR-368 was significantly upregulated and interference with piR-368 markedly inhibited the odontogenic differentiation of mDPCs. In addition, the relationship between Smad1/5 signaling pathway and piR-368-induced odontoblastic differentiation has been discovered. Finally, we demonstrated Smurf1 as a target gene of piR-368 using dual-luciferase assays.

CONCLUSION

This study was the first to illustrate the participation of piRNA in odontoblastic differentiation. We proved that piR-368 promoted odontoblastic differentiation of mouse dental papilla cells via the Smad1/5 signaling pathway by targeting Smurf1.

Comparative evaluation of different human dental tissues and alveolar bone for DNA quantity and quality for forensic investigation

In this study, the efficacy of dental tissues (cementum, dentine and pulp) and alveolar bone as a potential source of DNA was tested in terms of the quality and quantity using nuclear and mitochondrial markers for forensic investigation.This study found dentine as the best source of DNA with only 5.36% imbalanced (PHR<0.7) heterozygous loci. Pulp showed the highest quantity of DNA but exhibited 22.3% imbalanced (PHR<0.7) heterozygous loci. Cementum with highest (46.67%) heterozygote imbalance proved to be the last choice as a source of DNA. Alveolar bone exhibited the second-highest total yield of DNA/mg of tissue. All Global Filer™ STR loci were amplified in 70% samples of fresh alveolar bone whereas for 30% samples, only partial profile was generated along with successful sex determination. All the dental tissues and alveolar bone samples amplified non STR markers (D-loop, Cytochrome Oxidase I, SRY, AMEL). Of the alveolar bones from archival samples, one sample exhibited full STR profile whereas other alveolar bone samples gave partial profiles. This study substantiates alveolar bone as an alternate source of nuclear and mitochondrial DNA.

Evaluation of Resin-Based Material Containing Copaiba Oleoresin (Copaifera Reticulata Ducke): Biological Effects on the Human Dental Pulp Stem Cells

The purpose of this study was to analyze in vitro the biological effects on human dental pulp stem cells triggered in response to substances leached or dissolved from two experimental cements for dental pulp capping. The experimental materials, based on extracts from Copaifera reticulata Ducke (COP), were compared to calcium hydroxide [Ca(OH)₂] and mineral trioxide aggregate (MTA), materials commonly used for direct dental pulp capping in restorative dentistry. For this, human dental pulp stem cells were exposed to COP associated or not with Ca(OH)₂ or MTA. Cell cytocompatibility, migration, and differentiation (mineralized nodule formation (Alizarin red assay) and gene expression (RT-qPCR) of OCN, DSPP, and HSP-27 (genes regulated in biomineralization events)) were evaluated. The results showed that the association of COP reduced the cytotoxicity of Ca(OH)₂. Upregulations of the OCN, DSPP, and HSP-27 genes were observed in response to the association of COP to MTA, and the DSPP and HSP-27 genes were upregulated in the Ca(OH)₂ + COP group. In up to 24 h, cell migration was significantly enhanced in the MTA + COP and Ca(OH)₂ + COP groups. In conclusion, the combination of COP with the currently used materials for dental pulp capping [Ca(OH₎₂ and MTA] improved the cell activities related to pulp repair (i.e., cytocompatibility, differentiation, mineralization, and migration) including a protective effect against the cytotoxicity of Ca(OH)₂.

Pulp Inflammation Diagnosis from Clinical to Inflammatory Mediators: A Systematic Review

INTRODUCTION

Similar to other tissues, the dental pulp mounts an inflammatory reaction as a way to eliminate pathogens and stimulate repair. Pulp inflammation is prerequisite for dentin pulp complex repair and regeneration; otherwise, chronic disease or pulp necrosis occurs. Evaluation of pulp inflammation severity is necessary to predict the clinical success of maintaining pulp vitality. Clinical limitations to evaluating in situ inflammatory status are well-described. A molecular approach that aids clinical distinction between reversible and irreversible pulpitis could improve the success rate of vital pulp therapy. The aim of this article is to review inflammatory mediator expression in the context of clinical diagnosis.

METHODS

We searched PubMed and Cochrane databases for articles published between 1970 and December 2016. Only published studies of inflammatory mediator expression related to clinical diagnosis were eligible for inclusion and analysis.

RESULTS

Thirty-two articles were analyzed. Two molecular approaches were described by study methods, protein expression analysis and gene expression analysis. Our review indicates that interleukin-8, matrix metalloproteinase 9, tumor necrosis factor-α, and receptor for advanced glycation end products expression increase at both the gene and protein levels during inflammation.

CONCLUSIONS

Clinical irreversible pulpitis is related to specific levels of inflammatory mediator expression. The difference in expression between reversible and irreversible disease is both quantitative and qualitative. On the basis of our analysis, in situ quantification of inflammatory mediators may aid in the clinical distinction between reversible and irreversible pulpitis.

Dental pulp as a source of low-contaminated DNA

The in-laboratory contamination of the ancient samples hinders the result interpretation of the investigations in the field of paleomicrobiology. We had promoted the dental pulp as a sample that limits the risks of in-laboratory contamination of the ancient material. In this work, we measured the contamination of the dental pulp manipulated according to paleomicrobiology protocol, used as a source of a total DNA for metagenomics. First, total DNA extracted from two dog canines was sequenced using next generation sequencing. This yielded a total of 487,828 trimmed reads with a length of 227 ± 35 bp. Sequence analysis of the final dataset using Blast algorithm search and stringent thresholds for sequence identity and coverage against a database including both Canis lupus familiaris and Homo sapiens complete genomes showed that 95% of reads were assigned to C. familiaris whereas 0.03% was assigned to H. sapiens. In a second step, two teeth collected from two 12th century mammals were manipulated following the same protocol. A total of 13,890 trimmed reads with a 157 ± 67 bp length yielded 0-0.35% reads assigned to H. sapiens. This study indicates that the dental pulp is a useful for detecting the significant nucleic sequences in both modern and ancient samples.

Morphological aspects and physical properties of enamel and dentine of Sus domesticus: A tooth model in laboratory research

This study aims to describe and analyze morphological and physical properties of deciduous teeth of Sus domesticus. Ultrastructural analysis, mineral composition and microhardness of enamel and dentine tissues were performed on 10 skulls of S. domesticus. External anatomic characteristics and the internal anatomy of the teeth were also described. Data regarding microhardness and ultrastructural analysis were subjected to statistical tests. For ultrastructural analysis, we used the analysis of variance (ANOVA) with Tukey's post hoc (p≤0.05) test. In the analysis of microhardness, the difference between the enamel and dentine tissues was analyzed by a Student's t test. Values were expressed as mean with standard error. The results of ultrastructural analysis showed the presence of an enamel prism pattern. A dentinal tubule pattern was also observed, with a larger diameter in the pulp chamber and the cervical third, in comparison to middle and apical thirds. We observed an average microhardness of 259.2kgf/mm(2) for enamel and 55.17kgf/mm(2) for dentine. In porcine enamel and dentine, the chemical elements Ca and P showed the highest concentration. The analysis of internal anatomy revealed the presence of a simple root canal system and the occurrence of main canals in the roots. The observed features are compatible with the functional demand of these animals, following a pattern very similar to that seen in other groups of mammals, which can encourage the development of research using dental elements from the pig as a substitute for human teeth in laboratory research.

Dental pulp in mature replanted human teeth: morphological alterations and metalloproteineses-2 and -9, Annexin-5, BCL-2 and iNOS modulation

Tooth replantation, as a treatment concept, has been subject to controversies regarding the mechanism as well as the various parameters underlying this process. This work aimed to study time-related changes in the pulp of replanted mature human premolars through the changes in the levels of certain factors involved in the underlying mechanisms of pulpal tissue healing after replantation. Eleven experimental mature teeth were extracted, immediately replanted in the original socket and left without any other intervention for 1, 2, 3 and 12 weeks before re-extraction. Three premolars served as control. All specimens were subject to histological analysis and the levels of MMP-2, MMP-9, Annexin V, iNOS and BCL-2 (anti-apoptotic family) were analyzed employing immunohistochemistry. The results showed degradation of the extracellular matrix (ECM), inflammatory cell infiltrate, loss in pulpo-dentine interface and loss of odontoblasts in the dental pulp tissue. This was accompanied by increase over time of MMP-9, Annexin V, iNOS and a decrease of BCL-2 and MMP-2, suggesting that apoptosis increased throughout the experimental period.

Construction and in vitro test of a new electrode for dentin resistance measurement

It is necessary to reduce the tooth substance before treating a tooth with a dental crown. The preparation often requires reduction of the dentin. This results in a dentin wound and a thinner substance over the pulp, increases the risk of inflammation, and could result in necrosis of the pulp. To give the dentist information about the amount of dentin over the pulp during preparation, the Prepometer was developed. The function of this device is based on the measurement of the electric resistance of the tooth substance. The measuring behavior of the first-generation Prepometer is characterized by smaller values of electric resistance before reaching full contact of the measuring head to the dentin surface and the actual value RT. This measuring behavior can mislead inexperienced therapists with inaccurate values that suggest thinner dentin than the reality. In this study, a new electrode based on the technology of active guard drive was constructed to overcome this issue. The results show that improvement in the measuring behavior of the new electrode could be achieved, eliminating the earlier disadvantage of the Prepometer.

Levels and distribution of organochlorine pollutants in primary dental tissues and bone of lamb

This study examined the bioconcentration of selected organochlorine pollutants, tetra- and hexa-chlorobiphenyls with planar (PCB-80, PCB-169) and non-planar (PCB-54, PCB-155) structure, and persistent organochlorine pesticides with planar [hexachlorobenzene (HCB)] and non-planar [1,1-bis (4-chlorophenyl)-2,2-dichloroethene (4,4'-DDE)] structure in primary dental tissues (pulp, dentine, and enamel) and mandibular bone of lactationally exposed lambs, and compared it with the organochlorines distribution pattern in permanent dental tissues and bone. Also, the role of pollutants physicochemical properties and tissue specific characteristics in the bioconcentration was assessed. Residual levels of individual pollutants were analyzed by high-resolution gas chromatography with electron-capture detection. Our results showed that transfer of organochlorines to primary hard dental tissues was higher than to permanent hard dental tissues. Metabolically more stable, planar, and toxic organochlorines (e.g. PCB-169 and HCB) predominated in primary hard dental tissues, where they may represent a potential risk for developmental dental defects.

Utilization of dental pulp DNA as diagnostic molecular marker for fertility detection in men

Recent advances in DNA technology have revolutionized forensic identification procedures. Teeth dentin and pulp are rich sources of DNA material, which can be successfully extracted and it provides us with valuable information on individuals, systemic health including fertility status.

AIM OF STUDY

The aim of this study was to use DNA material extracted from human teeth pulp for detection of fertility status of men.

MATERIALS AND METHODS

Twenty extracted premolar teeth of systemic disease free male Saudi individuals (45 years average age) were collected; eight of them were infertile while others were fertile and were used as control group. This information was concealed until the PCR analysis was performed. The results of recorded patient information was matched with the results of the DNA analysis.

RESULTS

Results showed that the gene (sY83) an important gene of AZFa region in Y chromosome is important for male fertility. It was later evident that the infertile patients suffered from azoospermia, and that information is completely matched with our results.

CONCLUSION

Using DNA extracted from dental pulp can be used successfully in determining fertility status of human which may help in an accurate personal identification specially in extreme circumstances.

Orthodontic stress Bcl-2 modulation and human odontoblast survival

This study assessed the effect of orthodontic traction on Bcl-2 expression and apoptosis in human dental pulp. It also explored, in absence of noxious stimuli the regeneration of odontoblasts during the entire life of the tooth. Twenty young patients, with Class II malocclusion and severe to moderate crowding, were referred for orthodontic assessment. Whole pulps were removed. Half the pulps were fixed, paraffin-embedded and processed for histology and immunohistochemistry using anti Bcl-2, Caspase 9 cleaved and Caspase 9 not cleaved antibodies. The rest of the samples, both orthodontically treated and not treated dental pulps, were immediately frozen at -80ºC after the extraction and quantitative PCR was performed. Histology showed alterations in pulp microanatomy after 8 months of treatment. Immunohistochemistry depicted a decreasing expression of Bcl-2 in dental pulp over time in the non-treated while a very weak to absent Bcl-2 expression was detected in the orthodontically treated tissues. Active and non-active forms of Caspases, were expressed in both groups of dental pulp, however staining for the non active form was stronger than the corresponding cleaved form in all samples. The increased expression was detected mainly at nuclear level. Real time qPCR results correlated with those of immunohistochemistry and exhibited a decreasing expression of Bcl-2 in the treated samples. Orthodontic traction may inhibit the expression of Bcl-2, favoring the onset of apoptosis and leading us to conclude that the physical stress in the absence of noxious stimuli might make odontoblasts regeneration less likely.

Human dental pulp cell apoptosis: immunohistochemical study after applying orthodontic traction

The aim of this study was to compare human dental pulp stress and programmed cell death after 3 and 6 months of orthodontic treatments by assessing the degree of apoptosis and related proteins. Human dental pulps were collected from twenty young patients orthodontically treated by Straight Wire technique. Samples were fixed, paraffin-embedded and processed for histology and immunohistochemistry using anti-heat shock protein 60 kDa (Hsp60), -caspase 3, -caspase 9, and -PCNA antibodies, as well as TUNEL reactions. Moreover, we performed immunoprecipitation for Hsp60 and caspase 3, and for Hsp60 and caspase 9, from paraffin extracted tissues. Increased levels of both caspases and Hsp60 occurred in 6-months treated samples; at the same time, we found increased levels of proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase dUTP nick end labeling positive cells. Immunoprecipitation showed that Hsp60 forms a complex with both Pro-caspase 3 and Caspase 3, and this may accelerate Pro-caspase 3 activation, especially in the 6-months treated group. On the contrary, no complex between Hsp60 and Pro-caspase 9 was detected. The orthodontic tractions may be a cause of stress, apoptosis and proliferation in pulp tissue. These results suggest the need of further studies about the effects of long term orthodontic treatments on the dental pulp.

Immunolocalization of RANK and RANKL along the root surface and in the periodontal membrane of human primary and permanent teeth

OBJECTIVE

Root resorption, impaired tooth eruption and early tooth loss have been described in relation to diseases that involve defects in the RANK-RANKL-OPG-expression. The aim of the present immunhistochemical study was to localize and compare the reactions for RANK and membrane-bound RANKL along root surfaces and in the periodontal membrane in close proximity to the root surface of human primary and permanent teeth.

MATERIALS AND METHODS

The material comprised extracted human teeth (11 primary teeth and six permanent teeth) from 10 different patients. Paraffin sections were prepared of each tooth and sections of each tooth were immunohistochemically stained with antibodies specific for membrane-bound RANKL and RANK.

RESULTS

The root surface and the periodontal membrane in close proximity to the root surface did not show immunoreactivity for RANKL. RANKL was only located in odontoblasts and in cells along denticles in one primary tooth. RANK was located in mononuclear cells in the pulp and in multinucleated odontoclasts along resorbed root surfaces and along resorbed dentin surfaces in the pulp in primary teeth and one permanent tooth.

CONCLUSIONS

This study demonstrated RANK positivity in resorption areas in primary and permanent teeth. RANKL was positive in the pulp of one primary tooth. RANK expression in odontoclasts and RANKL expression in the pulp may indicate that RANK/RANKL play a role during resorption.

In vitro effects of ascorbic acid and β-glycerophosphate on human gingival fibroblast cells

Ascorbic acid (AA) and β-glycerophosphate (βG) are considered in vitro osteogenic factors important to the differentiation of osteoblastic progenitor and dental pulp cells into mineralized tissue-forming cells. So, the present study investigated in vitro if these mineralizing inducible factors (AA and βG) could influence differentiation of human gingival fibroblasts when compared with human pulp cells and osteogenic cells derived from rat calvaria cultured. The expression of osteopontin (OPN) and osteoadherin (OSAD) was analyzed by indirect immunofluorescence, immunocytochemistry as well as Western-blotting. In addition, the main ultrastructural aspects were also investigated. No mineralized matrix formation occurred on gingival fibroblasts induced with AA+βG. On these cells, no expression of OPN and OSAD was observed when compared with pulp cells, pulp cells induced with AA+βG as well as osteogenic cells. Ultrastructure analysis additionally showed that gingival fibroblasts exhibited typical fibroblast morphology with no nodule formation. The present findings showed that AA and βG could not promote a mineralized cell differentiation of human gingival fibroblasts and confirm that human dental pulp cells, as the osteogenic cells, are capable to form a mineralized extracellular.

[The influence of tobacco-smoke toxic components on glucosaminoglycans in biologic tissues]

The aim of the work is detailed analysis of glucosaminoglikans and glukuronic acid in chisel tooth and molars of tobacco-smokers and non-smokers. The total number of 140 patients (tobacco-smokers - 60) by acute serous pulpit is investigated. The conducted quantative and qualitative analyzes show that tobacco-smokers tooth contains les glucosaminoglikans (chondroitinsulfats A and C) and more glucuronic acid than non-smokers individuals. The chisel tooth pulp contained considerably more glucuronic acid as compared with molars. These studies support the hypothesis of important role of cigarette smoke toxical components in the tooth support mechanisms. The studies are necessary to be held in different directions.

Measurement of gross alpha and gross beta activity concentrations in human tooth

The gross alpha and gross beta activity concentrations were measured in human tooth taken from 3 to 6 age-groups to 40 and over ones. Accumulated teeth samples are investigated in two groups as under and above 18 years. The gross alpha and beta radioactivity of human tooth samples was measured by using a gas-flow proportional counter (PIC-MPC 9604-alpha/beta counter). In tooth samples, for female age-groups, the obtained results show that the mean gross alpha and gross beta activity concentrations varied between 0.534-0.203 and 0.010-0.453 Bq g(-1) and the same concentrations for male age-groups varied between 0.009-1.168 and 0.071-0.204 Bq g(-1), respectively.

[The effect of toxic components in tobacco smoke on the fatty acid profile of dental pulp]

The aim of the present study was to characterize fatty acid profile of dental pulp in non-smokers' and tobacco-smokers' with acute serous pulpitis. The fatty acid composition in the pulp of molars, pre-molars and chisel tooth in 80 tobacco-smokers and 60 non-smokers were analyzed by Gas-Chromatography with glass capillary colums. Linolic acid was revealed in both - tobacco-smokers and non-smokers; the concentration of linolic acid in tooth pulp of non-smokers was significantly higher. Non-smokers' tooth pulp contained linolic, linolenic and arachidonic acids; tobacco-smokers' - only linolic acid. The linolenic and arachidonic acids in pulp of tobacco-smokers were not discovered.

[Chromatography analysis of tobacco smoke condensate in biology tissue]

Specialized analytical instrumentation for detailed analysis of nicotine, benz(alpha)pyrene, pyridine and benzene in tooth enamel and pulp of inveterate tobacco smokers is created. A Waters PPY-24 liquid chromatograph is equipped with Model M660 solvent programmer and a Model U6K sample injector is used. A Model 440 dual-wavelength detector is used to obtain absorbance ratios on dual-pen recorder. Our data show that concentration of tobacco smoke components in tooth cavity of inveterate tobacco smokers is different. The chisel tooth pulp contained considerably more nicotine and pyridine as compared with molars. The level of benzene does not change analyzed structures. The assumption of linearity between calculation of predicted retention times and concentration has been shown to be valid up to about 8,0% for all studied compounds.

Pulp reactions in human teeth capped with self-etching or total-etching adhesive systems

OBJECTIVE

Restorative procedures of the dentin-pulp complex stimulate damages that, depending on the technique and materials used, may induce pulpal reactions. The purpose of this study was to evaluate immunochemistry, morphologic, and morphometric pulpal alterations of human teeth pulps capped with self-etching or total-etching adhesive systems.

METHOD AND MATERIALS

Thirty human third molars were restored with a resin-based composite and adhesive system, either Clearfil (Kuraray; n = 10) or Scotchbond (3M ESPE; n = 10). After 7, 30, or 60 days, the teeth were extracted and longitudinally sectioned. The pulps were removed for histopathologic and immunochemistry evaluation for interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and inducible nitric oxide synthase (iNOS).

RESULTS

The density of fibrous connective tissue was significantly higher after 30 days in both groups (P < .001). Congestion, hemorrhage, calcification, and swelling of the odontoblasts were similar in both groups. The total capillary area was significantly higher after 7 and 30 days in both groups. Positive immunoreactions for iNOS were found in 1 case (20%) of the 30-day Scotchbond group. Immunoreactions for IFN-gamma were positive in a few cells in 1 case (20%) of the 7-day Clearfil group. There were no positive immunoreactions for TNF-alpha in any case.

CONCLUSION

No inflammatory reactions, necrotic areas, or severe immunoreactions for proinflammatory cytokines were found, suggesting biocompatibility of self-etching or total-etching adhesive systems when placed directly on dentin.

Identification of full-length dentin matrix protein 1 in dentin and bone

Dentin matrix protein 1 (DMP1) has been identified in the extracellular matrix (ECM) of dentin and bone as the processed NH(2)-terminal and COOH-terminal fragment. However, the full-length form of DMP1 has not been identified in these tissues. The focus of this investigation was to search for the intact full-length DMP1 in dentin and bone. We used two types of anti-DMP1 antibodies to identify DMP1: one type specifically recognizes the NH(2)-terminal region and the other type is only reactive to the COOH-terminal region of the DMP1 amino acid sequence. An approximately 105-kDa protein, extracted from the ECM of rat dentin and bone, was recognized by both types of antibodies; and the migration rate of this protein was identical to the recombinant mouse full-length DMP1 made in eukaryotic cells. We concluded that this approximately 105-kDa protein is the full-length form of DMP1, which is considerably less abundant than its processed fragments in the ECM of dentin and bone. We also detected the full-length form of DMP1 and its processed fragments in the extract of dental pulp/odontoblast complex dissected from rat teeth. In addition, immunofluorescence analysis showed that in MC3T3-E1 cells the NH(2)-terminal and COOH-terminal fragments of DMP1 are distributed differently. Our findings indicate that the majority of DMP1 must be cleaved within the cells that synthesize it and that minor amounts of uncleaved DMP1 molecules are secreted into the ECM of dentin and bone.

Protein content in irrigating solutions in contact with pulp tissue

Endodontic irrigating solutions may have different effects, one of which is dissolving pulp tissue. The capacity of different irrigants to dissolve vital and necrotic pulp tissue was evaluated in vitro by means of a quantitative and qualitative study of total soluble pulp protein. Vital pulps and pulps with induced necrosis from young bovine teeth were used. Pulp was cut into smaller pieces, weighed and placed in 1 ml of 1% and 2.5% sodium hypochlorite, 1% and 5% calcium hydroxide, 0.2% chlorhexidine gluconate, 1% tea and distilled water as a control, and kept at 37 degrees. Samples of 20 microl were taken at 30 and 90 minutes and 20 hours. Total protein was dosed using the Lowry method and soluble protein bands were determined by electrophoresis (12% SDS-Page). The results were analyzed using Anova. Chemical analysis of the electrophoretic runs of bovine pulp protein showed that both concentrations of sodium hypochlorite and calcium hydroxide produce denaturation of proteins. No solvent action was found with chlorhexidine, tea or distilled water.

Immunohistochemical localization of metallothionein in dental pulp after cavity preparation of rat molars

OBJECTIVE

Metallothionein (MT) is an intracellular cysteine-rich protein associated with cell proliferation and differentiation. Our objective was to examine immunohistochemically the localization of MT in the rat dental pulp after cavity preparation.

STUDY DESIGN

Cavities were prepared on the upper first molars of 9 rats. Specimens were collected at 1, 3, and 5 days after cavity preparation, and paraffin sections were made. For double-immunohistochemical staining, anti-MT monoclonal antibody (E9) and anti-proliferating cell nuclear antigen (PCNA) monoclonal antibody (PC10) were applied.

RESULTS

At 3 days after cavity preparation, some odontoblasts corresponding to the cavity, many pulp cells, and some endothelial cells in the pulp under the cavity showed both MT- and PCNA-positive immunostainings.

CONCLUSION

Metallothionein was detected in the dental pulp after pulp injury, and it is likely that MT is closely related to the proliferation of newly differentiating odontoblasts and angiogenesis during the healing process.

Hard tissue formation in subcutaneously transplanted rat dental pulp

While dental pulp appears to be able to form mineralized matrices that do not always resemble dentin, the precise characteristics of the hard tissue and the mechanism of its induction remain unknown. Therefore, we evaluated hard tissue induced by transplantation of pulp into subcutaneous tissue. Seven days after transplantation, initial hard tissue was formed at the inner periphery of the pulp. After 14 days, this hard tissue expanded inwardly. Mineralized matrix was immunopositive for osteocalcin, osteopontin, and bone sialoprotein, but negative for dentin sialoprotein. Transplantation of GFP-labeled pulp into wild-type rats showed these formative cells to have been derived from the transplant. TEM observation revealed apatite crystals within necrotic cells and matrix vesicles at the initial stage of calcification. These results indicate that pulp cells possess the ability to form a bone- or cementum-like matrix. Calcification of the matrix may occur in necrotic cells and matrix vesicles, followed by collagenous calcification.

Irreversible but not reversible pulpitis is associated with up-regulation of tumour necrosis factor-alpha gene expression in human pulp

AIM

To analyse the gene expression of tumour necrosis factor-alpha (TNF-alpha) in human dental pulps, under normal and inflammatory conditions and to examine the association between any observed alterations in the expression of this cytokine with the severity of the clinical symptoms.

METHODOLOGY

Eighteen pulpal samples were obtained from single-rooted human teeth. Six of the teeth were normal (group A), six had been diagnosed with reversible pulpitis (group B), and the remaining six were from teeth diagnosed with irreversible pulpitis (group C). TNF-alpha gene expression was semi-quantitatively analysed in each sample with RT-PCR, and the results from each group of teeth were compared with the Kruskal-Wallis and Mann-Whitney tests.

RESULTS

Tumour necrosis factor-alpha was detected in all three groups of dental pulp. Statistical analysis provided evidence of a significant increase of TNF-alpha gene expression associated with irreversible inflammation compared with healthy controls (P = 0.002). No such difference was detected in reversibly inflamed pulp in comparison to healthy teeth (P = 0.699).

CONCLUSION

Tumour necrosis factor-alpha gene expression in inflamed human dental pulp tissue is positively associated with the severity of clinical symptoms.

Effect of composite temperature on in vitro intrapulpal temperature rise

OBJECTIVES

To measure in vitro intrapulpal temperature when placing and restoring with either room-temperature or pre-heated (54 and 60 degrees C) composite.

METHODS

A K-type thermocouple was placed in the pulpal chamber of an extracted, human bifurcated upper premolar which had a Class V preparation (1 mm remaining dentin thickness) on the facial surface. Tooth roots were immersed in a thermostatically controlled water bath and perfused with water at 1.25 microl/min to simulate physiological circulation in the pulp chamber. The thermocouple was connected to an analog-to-digital converter. The preparation was filled using composite either at room-temperature, or pre-heated to 54 or 60 degrees C with a commercial compule heater (Calset), using standard clinical procedures by one person while continuously monitoring intrapulpal temperature (n=5). Temperature rise over baseline values were determined at various stages during the restoration process: composite placement, contouring, prior to light-curing, and immediately after light-curing (20s, Optilux 501). At each measurement interval, intrapulpal temperature values were compared using ANOVA and the Tukey-Kramer post hoc test (alpha=0.05).

RESULTS

Significant differences were found in intrapulpal temperature when comparing pre-heated and room-temperature composite treatments with respect to baseline among the stages of the restorative process. However, the extent of this increase with heated composite was only 0.8 degrees C. A 5 degrees C intrapulpal temperature rise was seen for all groups during photopolymerization.

SIGNIFICANCE

Use of pre-heated composite only mildly increased intrapulpal temperature values when compared to composite delivered at room-temperature in an in vitro test environment. The largest temperature change occurred with application of the curing light.

Adhesive performance of dentin bonding agents appliedin vivo andin vitro. Effect of intrapulpal pressure and dentin depth

The purpose of this study was to evaluate the influence of intrapulpal pressure and dentin depth on bond strengths of an etch-and-rinse and a self-etching bonding agent to dentin in vitro and in vivo. Twenty-four pairs of premolars were randomly divided into four groups (n = 6) according to the dentin bonding agent, Single Bond and Clearfil SE Bond, and intrapulpal pressure, null or positive. Each tooth of the pair was further designated to be treated in vivo or in vitro. The intrapulpal pressure was controlled in vivo by the delivery of local anesthetics containing or not a vasoconstrictor, while in vitro, it was achieved by keeping the teeth under hydrostatic pressure. Class I cavities were prepared and the dentin bonding agents were applied followed by incremental resin restoration. For the teeth treated in vitro, the same restorative procedures were performed after a 6 month-storage period. Beams with 1 mm(2) cross-sectional area were prepared and microtensile tested. Clearfil SE Bond was not influenced by any of the variables of the study, while bond strengths produced in vitro were significantly higher for Single Bond. Overall, lower bond strengths were produced in deep dentin, which reached statistical significance when Single Bond was applied under physiological or simulated intrapulpal pressure. In conclusion, in vitro bonding may overestimate the immediate adhesive performance of more technique-sensitive dentin bonding systems. The impact of intrapulpal pressure on bond strength seems to be more adhesive dependent than dentin morphological characteristics related to depth.

Co-expression of cyclooxygenase-2 and vascular endothelial growth factor in inflamed human pulp: an immunohistochemical study

Recent data from the medical literature indicates that cyclooxygenase-2 (COX-2) plays a key role in the production of vascular endothelial growth factor (VEGF), a glycoprotein that has the ability to increase the permeability of blood vessels and to induce angiogenesis. This study was undertaken to investigate the immunohistological co-expression of COX-2 and VEGF in inflamed human pulp, in conjunction with the expression of CD34, a transmembrane glycoprotein expressed in endothelial cells. Pulp tissue of extracted carious human third molars with a recent history of spontaneous pain were collected and processed for immunostaining of COX-2, VEGF, and CD34 using the biotin-streptoavidin method. Healthy pulp samples served as controls. COX-2 expression was not observed in healthy pulps, whereas all inflamed pulps demonstrated COX-2-expressing cells. Similarly, VEGF was not expressed in normal pulp tissue, but was strongly positive in inflamed pulps. CD34 was expressed in the endothelium of both normal and inflamed pulp tissues. Co-expression of COX-2 and VEGF in all consecutive sections of inflamed pulps could be suggestive of a possible release of VEGF via a COX-2-dependent pathway.

Interleukin-1? and tumor necrosis factor-? expression during the early phases of orthodontic tooth movement in rats

Remodelling of the periodontium after application of mechanical forces constitutes the basis of clinical orthodontics and various immunoregulatory molecules are involved in this process. The aim of this study was to investigate the expression of the cytokines interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) in dental tissues during the early phases of orthodontic tooth movement. Eightteen male Wistar rats were used. All maxillary right first molars were moved orthodontically, with a force of 0.5 N, for 3 h, 1 d, and 3 d. The contralateral sides served as untreated controls. Parasagittal sections of the maxillary molars and the surrounding tissues were subjected to immunohistochemical staining for IL-1alpha or TNF-alpha, and were evaluated with light microscopy. IL-1alpha and TNF-alpha were expressed in the bone and periodontal ligament (PDL) along the roots of the orthodontically moved molars and in the gingiva. Increased expression of both cytokines was observed in the aforementioned areas after 1 and 3 d of tooth movement. The pulp tissue exhibited only minor changes in cytokine expression during tooth movement. The results suggest that mechanical stress results in almost immediate inflammatory reactions in various dental tissues.

DNA examination of ancient dental pulp incriminates typhoid fever as a probable cause of the Plague of Athens

BACKGROUND

Until now, in the absence of direct microbiological evidence, the cause of the Plague of Athens has remained a matter of debate among scientists who have relied exclusively on Thucydides' narrations to introduce several possible diagnoses. A mass burial pit, unearthed in the Kerameikos ancient cemetery of Athens and dated back to the time of the plague outbreak (around 430 BC), has provided the required skeletal material for the investigation of ancient microbial DNA.

OBJECTIVE

To determine the probable cause of the Plague of Athens.

METHOD

Dental pulp was our material of choice, since it has been proved to be an ideal DNA source of ancient septicemic microorganisms through its good vascularization, durability and natural sterility.

RESULTS

Six DNA amplifications targeted at genomic parts of the agents of plague (Yersinia pestis), typhus (Rickettsia prowazekii), anthrax (Bacillus anthracis), tuberculosis (Mycobacterium tuberculosis), cowpox (cowpox virus) and cat-scratch disease (Bartonella henselae) failed to yield any product in 'suicide' reactions of DNA samples isolated from three ancient teeth. On the seventh such attempt, DNA sequences of Salmonella enterica serovar Typhi were identified providing clear evidence for the presence of that microorganism in the dental pulp of teeth recovered from the Kerameikos mass grave.

CONCLUSION

The results of this study clearly implicate typhoid fever as a probable cause of the Plague of Athens.

An immunohistochemical study of the expression of heat-shock protein-25 and cell proliferation in the dental pulp and enamel organ during odontogenesis in rat molars

OBJECTIVES

The aim of this study is to clarify the functional significance of heat-shock protein (HSP)-25 during tooth development.

DESIGN

We compared the expression of HSP-25 in the dental epithelial and mesenchymal cells with their proliferative activity during odontogenesis in rat molars on postnatal days 1-100 by immunohistochemistry using anti-HSP-25 and anti-5-bromo-2'-deoxyuridine (BrdU) for cell proliferation assay.

RESULTS

On day 1, BrdU-immunoreactive cells were densely located in the inner enamel epithelium in the cervical loop and intercusped areas and the dental pulp adjacent to them, whereas HSP-25-immunoractivity (IR) was restricted to the cusped area where odontoblasts and ameloblasts had already differentiated. Subsequently, BrdU-IR shifted in the apical direction to be localized around Hertwig's epithelial root sheath during days 5-30, never overlapping with concomitantly apically-shifted HSP-25-IR. On days 60-100, BrdU-immunoreactive cells were hardly recognizable in the dental pulp, where HSP-25-IR was exclusively localized in the odontoblast layer. Furthermore, the odontoblast- and ameloblast-lineage cells exhibited two steps in the expression of HSP-25 throughout the postnatal stages: first, dental epithelial and pulpal mesenchymal cells showed a weak IR for HSP-25 after the cessation of their proliferative activity, and subsequently odontoblasts and ameloblasts consistently expressed an intense HSP-25-IR.

CONCLUSION

Odontoblast- and ameloblast-lineage cells acquire HSP-25-IR after they complete their cell division, suggesting that this protein acts as a switch between cell proliferation and differentiation during tooth development. The consistent expression of HSP-25-IR in the formative cells may be involved in the maintenance of their functional integrity.

Quantification of neuropeptides (calcitonin gene-related peptide, substance P, neurokinin A, neuropeptide Y and vasoactive intestinal polypeptide) expressed in healthy and inflamed human dental pulp

AIM

To quantify the expression of calcitonin gene-related peptide (CGRP), substance P (SP), neurokinin A (NKA), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) in healthy and inflamed human dental pulp tissue.

METHODOLOGY

Six pulp samples were obtained from teeth having a clinical diagnosis of acute irreversible pulpitis. Another 12 pulp samples were obtained from premolars where extraction was indicated for orthodontic purposes. In six of these premolar teeth inflammation was induced by mechanical pulp exposure prior to sample collection. All samples were processed and 125I-labelled; neuropeptides were quantified by competition assays. ANOVA and Mann-Whitney's (post hoc) tests were used to establish statistically significant differences between the groups.

RESULTS

Expression of five neuropeptides was found in all human pulp samples. Statistical analysis revealed a significantly higher (P < 0.05) expression of CGRP, SP, NKA and NPY in both inflammatory conditions compared with healthy pulp control values. VIP expression remained stable during the inflammatory conditions.

CONCLUSION

Expression of CGRP, SP and NKA released from C-fibres and NPY released from sympathetic fibres is significantly higher in the inflamed human pulp compared with healthy pulp. Expression of VIP released from parasympathetic fibres is not increased during the inflammatory conditions of human dental pulp.

Immunohistochemical localization of components of the insulin-like growth factor system in human permanent teeth

There is growing evidence that the insulin-like growth factor (IGF) system plays an important role in the biology of oro-dento-facial tissues and organs, including the development, homeostasis and regeneration of the periodontium. To obtain basic data on the occurrence and distribution of IGF components in human permanent teeth we immunohistochemically investigated 25 extracted, decalcified and paraffin-embedded teeth using mono and polyclonal antibodies against the ligands IGF-I and -II, the IGF1 receptor (IGF1R) and all six IGF binding proteins (IGFBP-1 to -6). In the extracellular matrix (ECM) of the adhering periodontal ligament (PDL), immunoreactivity for IGF-I, -II and IGFBP-1 and -6 was observed. PDL fibroblasts showed immunostaining for the IGF1R. For the cementum, in the acellular cementum only IGF-II could be detected, while outer cementum layers with inserting Sharpey's fibers reacted with all antibodies applied except for IGFBP-4 and -6. In the pulp, mainly fibrotic areas and areas around denticles were immunoreactive for IGF-I, IGFBP-1, -3, -5 and -6. Predentin and odontoblastic processes were stained for IGF-I and IGFBP-3. The spatially oriented occurrence of components of the IGF system in human permanent teeth indicates that specific functions of the IGFs may be localized in particular tissue compartments. In the cementum, several IGF components were found indicating roles in tissue homeostasis or attachment. The PDL may function as a reservoir for IGFs probably bound to ECM components. PDL fibroblasts could then respond in a paracrine manner. In the pulp, the IGF system may be involved in odontoblast biology, fibrosis and denticle formation.

Histochemical and immunocytochemical study of hard tissue formation in dental pulp during the healing process in rat molars after tooth replantation

Dental pulp is assumed to possess the capacity to elaborate both bone and dentin matrix under the pathological conditions following tooth injury. This study was undertaken to clarify the mechanism inducing bone formation in the dental pulp by investigating the pulpal healing process, after tooth replantation, by micro-computed tomography (mu-CT), immunocytochemistry for heat-shock protein (HSP)-25 and cathepsin K (CK), and histochemistry for both alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP). Under deep anesthesia, the upper right first molar of 4-week-old Wistar rats was extracted and immediately repositioned in the original socket. In control teeth at this age, the periphery of the coronal dental pulp showed intense ALP-positive and HSP-25-positive reactions, whereas there were no TRAP-positive or CK-positive cells. Tooth replantation weakened or terminated ALP-positive and HSP-25-positive reactions in the pulp tissue at the initial stages. At 3-7 days after operation, the ALP-positive region recovered from the root apex to the coronal pulp followed by HSP-25-positive reactions in successful cases showing tertiary dentin formation. In other cases, TRAP-positive and CK-positive cells appeared in the pulp tissue of the replanted tooth at postoperative days 5-10 and remained associated with the bone tissue after 12-60 days. Immunoelectron microscopy clearly demonstrated that CK-positive osteoclast-lineage cells made contact with mesenchymal cells with prominent nucleoli and well-developed cell organelles. These data suggest that the appearance of TRAP-positive and CK-positive cells is involved in the induction of bone tissue formation in dental pulp.

Human dental pulp cell culture and cell transplantation with an alginate scaffold

Many studies on tissue stem cells have been conducted in the field of regenerative medicine, and some studies have indicated that cultured dental pulp mesenchymal cells secrete dentin matrix. In the present study we used alginate as a scaffold to transplant subcultured human dental pulp cells subcutaneously into the backs of nude mice. We found that when beta-glycerophosphate was added to the culture medium, dentin sialophosphoprotein mRNA coding dentin sialoprotein (DSP) was expressed. An increase in alkaline phosphatase, which is an early marker for odontoblast differentiation, was also demonstrated. At 6 weeks after implantation the subcutaneous formation of radio-opaque calcified bodies was observed in situ. Immunohistochemical and fine structure studies identified expression of type I collagen, type III collagen, and DSP in the mineralizing transplants. Isolated odontoblast-like cells initiated dentin-like hard tissue formation and scattered autolyzing apoptotic cells were also observed in the transplants. The study showed that subcultured dental pulp cells actively differentiate into odontoblast-like cells and induce calcification in an alginate scaffold.

The dentin sialoprotein (DSP) expression in rat tooth germs following fluoride treatment: An immunohistochemical study

Fluoride is known to alter expression of dentin matrix proteins and affect their posttranslational modifications.

OBJECTIVE

The objective of our study was to examine dentin sialoprotein (DSP) expression in the early and late bell stages of development of the first molar tooth germs in rats treated with fluoride.

DESIGN AND METHODS

Pregnant dumps were divided into three groups. They were fed a standard diet and from the fifth day of pregnancy, each group received either tap water (with trace amounts of fluoride), tap water with a low concentration of fluoride, or tap water with a high concentration of fluoride. Changes in DSP expression and distribution were visualized by immunohistochemistry.

RESULTS

Immunoreactivity for DSP was detected in the cervical regions of the early bell stage in tooth germs of the 1-day-old animals. The earliest reaction was visible in the control group and the group supplemented with the low fluoride concentration (F(L)) but not in the group supplemented with the high fluoride concentration (F(H)). In early bell stages across all experimental groups, the immunoreactivity to DSP was observed in the cusp tip regions and was localized to preameloblasts, young and mature odontoblasts, dental pulp cells, predentin, and dentin. Generally, more intense positive staining for DSP was detected in animals supplemented with the high fluoride concentration. In the late bell stage found in the 4-day-old control group and the group supplemented with the low fluoride concentration, immunoreactivity for DSP was less intense compared with younger animals. However, immunoreactivity was greater in the group treated with the high dose of fluoride. In this group, the positive immunostaining for DSP, especially in young ameloblasts, was prolonged and relatively strong.

CONCLUSIONS

Fluoride supplementation causes changes in the developmental pattern of DSP expression and its distribution in rat tooth germs.

Hypervariable region structure and polymorphism of mtDNA from dental pulp and a family analysis

Nucleotide sequences of the hypervariable region in the D-loop of mitochondrial DNA (mtDNA) were analyzed using DNA extracted from 140 old dental pulp samples. These sequences were compared with the sequence reported by Anderson et al. Nucleotide substitution in the HV1 region was identified at 77 positions. A C-to-T transition at position 16223 (C16223T) was most frequently detected (77.9%). Fourteen types of C-stretch sequence patterns were detected and the same sequence as Anderson had the highest frequency (57.9%). In the HV2 region, base transitions were identified at 56 positions. A263G was identified in all samples. Seven types of C-stretch were detected, but none had the same sequence as Anderson. In the HV3 region, base transitions were identified at 21 positions. T489C was most frequently identified (64.3%). Five types of C-stretch were detected, and the same sequence as Anderson accounted for 92.9%. The 140 samples were classified into 128 kinds by the sequence patterns of the HV region. Next, using the blood and oral mucosa epithelium from 23 subjects comprising four generations in a family line, the hereditary relationship of mtDNA was examined. All mtDNA types of the first-generation mother were infallibly inherited by the fourth generation.

Effect of simulated pulpal pressure on dentin bond strength of self-etching bonding systems

PURPOSE

To evaluate in vitro the influence of dentin perfusion on dentin bond strengths of etch and rinse and self-etch adhesives.

METHODS

64 extracted human molars were ground flat and resin composite (Brilliant) was bonded using the following bonding systems (each n=16): OptiBond FL including phosphoric acid etching (OFL+), OptiBond FL without phosphoric acid etching (OFL-), Clearfil SE-Bond (CSE) and Prompt L-Pop (LP). In each bonding system, half of the specimens (n=8) were bonded without (PP-) and half with (PP+) simulated intrapulpal pressure. After water storage (37 degrees C, 24 hours), a 1 mm thick slice was cut vertically from the middle of each sample. Microtensile bond strength (microTBS) was determined and the debonded surfaces were investigated in SEM for the mode of failure. Statistical significance was determined by ANOVA, Tukey-test, and t-test (P= 0.05).

RESULTS

Mean microTBS measured were (MPa +/- SD): OFL+/PP- 58.6 (5.8), OFL+/PP+ 38.1 (3.8), OFL-/PP- 37.9 (3.7), OFL-/PP+ 33.3 (3.5), CSE/PP- 41.1 (4.1), CSE/PP+ 39.0 (4.4), LP/PP- 35.8 (6.4), LP/PP+ 29.0 (4.8). The presence of PP resulted in a decrease of microTBS in all bonding systems, which reached significance in OFL+ (P< 0.0001), OFL- (P= 0.023) and LP (P= 0.032). Both, with and without PP, the bonding systems showed significant differences in bond strength (ANOVA: P< 0.0001).

Human beta-defensin (hBD-1, -2) expression in dental pulp

The purpose of this study was to investigate the expression of human beta-defensins (hBD-1, -2) in dental pulps by reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The mRNA transcripts of human beta-defensin-1 and human beta-defensin-2 could be detected by performing RT-PCR. With immunohistochemical staining of pulp tissue using antisera to hBD-1 and -2 it was possible to demonstrate cytoplasmic expression in odontoblasts. The results demonstrate that not only oral keratinocytes at the epithelial surface but also odontoblasts express human beta-defensins. Thus odontoblasts take part in the innate immune system and human beta-defensins may play an important role in the innate host defense of human dental pulp.

Behavioural responses following tooth injury in rats

Early changes in spontaneous behaviour (exploration, grooming, freezing, rearing, jaw motion, yawning) and body weight were measured at two and three days after pulp exposure injury and implantation of Fluorogold (FG) into molar teeth of rats. Rats with FG and injuries to three teeth gained weight less rapidly, explored less frequently and froze more often than sham-operated rats. Yawning was not observed in any rats prior to surgery and it was seen more frequently in tooth-injured rats than in sham-operated rats. These results suggest that careful observation of spontaneous behaviour after tooth injuries can be used to assess dental pain in rats and may provide behavioural markers to correlate with anatomical changes after injury. The dental nerve cell bodies that had accumulated transported FG were medium to large, and they only co-localized calcitonin gene-related peptide (CGRP) in a subset of the medium neurons. Chromatolytic or moribund FG-labelled neurons were also found.

Peroxide penetration into the pulp from whitening strips

It was observed that externally applied bleaching gels may penetrate into the pulp chamber. This study was conducted to evaluate the peroxide diffusion from two whitening strips into the pulp chamber. Twenty-four, human, extracted, maxillary central teeth were separated into three groups (n = 8). All teeth were sectioned 3-mm apical to CEJ, the intracoronal pulp tissue was removed, and the pulp chamber was filled with acetate buffer. Vestibuler crown surfaces of teeth in the experimental groups were subjected to whitening strips; the teeth in the control group were exposed only to distilled water. The acetate buffer solution in each tooth was transferred to the tube. Leuco-crystal violet and enzyme horseradish peroxidase also were added to the tube. The pulpal peroxide was determined spectrophotometrically. The results indicated that the whitening strip containing 14% hydrogen peroxide presented a higher pulpal peroxide penetration than 6.5 % hydrogen peroxide (p < 0.001).

GFAP immunoreactivity and transcription in trigeminal and dental tissues of rats and transgenic GFP/GFAP mice

Sensory mechanisms in teeth are not well understood and may involve pulpal-neural interactions. Tooth cells that proliferate in vitro have polyclonal immunoreactivity (IR) for glial fibrillary acidic protein (GFAP), growth-associated protein (GAP-43), and vimentin, plus glial-like ion channels. Here, we analyzed GFAP-IR patterns in dental and trigeminal tissues of rats, for comparison with green fluorescent protein (GFP) associated with GFAP transcription in transgenic mice, in order to better characterize glial-like cells in dental tissues. Astrocytes, ganglion satellite cells, and epineurial Schwann cells were demonstrated by anti-GFAP antibodies and GFP-GFAP, as expected. Odontoblasts did not stain by any of these methods and cannot be the glial-like cells. Fibroblasts and undifferentiated mesenchymal cells in pulp had polyclonal GFAP-IR and vimentin-IR, while nerve fibers reacted only with polyclonal antibody. Some Schwann cell subtypes in trigeminal nerve and oral mucosa were positive for GFP and for polyclonal anti-GFAP, but not for monoclonal antibody. In pulp almost all Schwann cells were unstained, but many Schwann cells in periodontal ligament had polyclonal GFAP-IR. These results show greater heterogeneity for Schwann cells than expected, and suggest that the glial-like pulp cells are fibroblasts and/or undifferentiated mesenchymal cells or stem cells. We also found that polyclonal GFAP revealed intermediate filaments in preterminal sensory nerve fibers, thereby providing a useful marker for that neural subregion. GFP transcription by some Schwann cell subtypes in oral mucosae and trigeminal nerve, but not trigeminal root was a novel finding that reveals more complexity in peripheral glia than previously recognized.

Vanilloid receptor 1 expression in human tooth pulp in relation to caries and pain

AIMS

To investigate the presence of vanilloid receptor 1 (TRPV1) in human dental pulp and to correlate any expression with caries and pain.

METHODS

Permanent mandibular first molars were collected and categorized as intact or grossly carious. Grossly carious teeth were further categorized as carious asymptomatic or carious painful samples. Coronal pulps were removed and processed for indirect immunofluorescence using antibodies raised against TRPV1 and a neuronal marker, either protein gene product 9.5 or alpha-smooth muscle actin, in conjunction with Ulex europaeus agglutinin 1 lectin to fully label the pulp vasculature.

RESULTS

Analysis revealed that TRPV1 labeling was not confined to pulpal nerve fibers. TRPV1 was also consistently expressed within pulp microvasculature. Expression of neuronal TRPV1 was significantly increased throughout the pulp in grossly carious samples (P < .05). No significant differences were found between carious asymptomatic and carious painful samples. A significant increase in vascular TRPV1 expression was observed in arterioles present in the midcoronal pulp in carious painful compared with carious asymptomatic samples (mean area +/- SEM [%] of TRPV1 to vascular labeling; 6.48% +/- 4.5% for carious asymptomatic teeth, n = 9; 31.21% +/- 9.6% for carious painful teeth, n = 9; P = .02).

CONCLUSION

Expression of TRPV1 in pulpal nerve fibers undergoes marked changes with caries. This may be of relevance in the development of pulpal inflammation, but its relationship to dental pain is still unclear. However, vascular TRPV1 expression does appear to be positively correlated with dental pain, thus providing new insights into symptomatic pulpitis.

Detection of acid diffusion through bovine dentine after adhesive application

AIM

Acidic diffusion through bovine dentine was investigated by measuring pH changes on dentine surfaces after applying three adhesive systems.

METHODOLOGY

Coronal incisor bovine dentine discs, 0.5 mm thick, were prepared from dentine close to the pulp chamber. A single-bottle adhesive system-Single Bond, a self-etching primer system-Clearfil SE Bond and an 'all-in-one' adhesive system-AQ Bond were used. The labial dentine surfaces were conditioned as follows: Single Bond groups: (SB-1) 35% phosphoric acid etchant was applied and left in place; (SB-2) the etchant was applied for 15 s and rinsed off for 10 s; (SB-3) application of adhesive agent and light curing following step SB-2; Clearfil SE Bond groups: (SE-1) SE primer was applied for 20 s and dried; (SE-2) application of adhesive agent and light curing following step SE-1; AQ Bond groups: (AQ-1) AQ Bond adhesive was applied for 20 s and dried, applied for additional 5 s and dried again; (AQ-2) light curing following step AQ-1. The pH change on the pulpal dentine surface was measured using a pH-imaging microscope.

RESULTS

All the Single Bond groups revealed a lower pH on the pulpal surface (pH 6.25, 6.59 and 6.64 for SB-1, SB-2 and SB-3, respectively) compared with intact dentine. Clearfil SE Bond and AQ Bond groups showed no significant deference in pH value from intact dentine.

CONCLUSIONS

Acid diffusion from phosphoric acid etching was observed when placed on 0.5 mm-thick dentine discs; however, there was only limited evidence of acid diffusion from SE primer and AQ Bond.

Application of laser ablation?inductively coupled plasma-mass spectrometry (LA?ICP?MS) to investigate trace metal spatial distributions in human tooth enamel and dentine growth layers and pulp

Human tooth enamel provides a nearly permanent and chronological record of an individual's nutritional status and anthropogenic trace metal exposure during development; it might thus provide an excellent bio archive. We investigated the micro-spatial distribution of trace metals (Cu, Fe, Mg, Sr, Pb, and Zn) in 196 x 339 microm2 raster pattern areas (6.6 x 10(4) microm2) in a deciduous tooth using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Ablated areas include prenatal and postnatal enamel, the neonatal line, the dentine-enamel junction (DEJ), dentine, and the dentine-pulp junction. Topographic variations in the surface elemental distribution of lead, zinc, strontium, and iron intensities in a deciduous tooth revealed heterogeneous distribution within and among regions. 43Ca normalized elemental intensities showed the following order: Sr>Mg>>Zn>Pb>Fe>Cu. Elevated zinc and lead levels were present in the dental pulp region and at the neonatal line. This study demonstrates the ability of LA-ICP-MS to provide unique elemental distribution information in micro spatial areas of dental hard tissues. Elemental distribution plots could be useful in decoding nutrition and pollution information embedded in their bio apatite structure.

The localization of Fos B, a member of transcription factor AP-1 family, in rat odontoblasts and pulpal undifferentiated ectomesenchymal cells

It has been proposed that cellular proliferation and differentiation are accomplished by AP-1 components but different components can be responsible for different functions. The aim of this study was to compare the localization of Fos B, which is a component of AP-1, in postmitotic differentiated and undifferentiated cells via Fos B immunoreactivity. For this purpose, maxillary incisor teeth from 10 Wistar rats were obtained and Fos-B was investigated immunohistochemically in formalin-fixed, paraffin-embedded tooth sections containing odontoblasts, which are postmitotic differentiated cells, and pulpal undifferentiated ectomesenchymal cells. No significant differences in percentage of Fos B-positive cells were observed between the two cell types (p>0.05). These findings suggest that Fos B, a component of AP-1 family, seems to have a negligible effect on differentiation and proliferation in odontoblasts and pulpal undifferentiated ectomesenchymal cells.

Pituitary adenylate cyclase-activating polypeptide-immunoreactive nerve fibers in rat and human tooth pulps

The distribution of pituitary adenylate cyclase-activating polypeptide (PACAP) was examined in the tooth pulp. In rat and human tooth pulps, PACAP-immunoreactive (IR) nerve fibers were observed around blood vessels and in the subodontoblastic and odontoblastic layers. The predentine and dentine were devoid of such nerve fibers. The double immunofluorescence method indicated the co-expression of PACAP with calcitonin gene-related peptide (CGRP) or vasoactive intestinal polypeptide (VIP). Virtually all PACAP-IR nerve fibers co-expressed CGRP-immunoreactivity (IR) in the rat tooth pulp suggesting their sensory function. In addition, a retrograde tracing method indicated that PACAP-IR nerve fibers in the rat tooth pulp originated from the trigeminal ganglion. On the other hand, almost all PACAP-IR nerve fibers in the human tooth pulp co-expressed VIP-IR and, thus, thought to be autonomic in nature.

Sympathectomy causes increased root resorption after orthodontic tooth movement in rats: immunohistochemical study

Accumulating evidence suggests that the sympathetic nervous system modulates inflammatory responses and bone remodeling. We have studied the effects of sympathectomy and orthodontic tooth movement (OTM) on root resorption, immunocompetent cell recruitment, neuropeptide, neurokinin-1 receptor (NK1-R), and interleukin 6 (IL-6) expression. Experimental rats (n=8) had the right superior cervical ganglion surgically removed, whereas control rats (n=6) underwent sham surgery. Three days later, all rats had the right maxillary first molar moved mesially by an orthodontic appliance. The rats were perfused 13 days later, and the right maxillae were processed for immunohistochemistry by using primary antibodies directed against ED1 antigen, CD43, substance P (SP), NK1-R, neuropeptide Y (NPY), and IL-6. Following OTM, sympathectomized (SCGx) rats had significantly more root resorption (P<0.01) and SP-immunoreactive (IR) fibers (P=0.01) in the compressed periodontal ligament (PDL) compared with control rats. There was a significant decrease in recruitment of CD43+ cells in the pulp after OTM in SCGx rats compared with control rats (P=0.02). An upregulation of NK1-R immunoreactivity was observed surrounding the hyalinized tissue, and an increase in the number of NK1-R IR cells and density of SP-IR fibers was present in first molar pulp of all rats. NPY-IR fibers were absent in the compressed PDL of SCGx and control rats. Thus, OTM induces remodeling not only around the periodontal tissues, but also in the dental pulp. The sympathetic nerves have an inhibitory effect on hard tissue resorption and a stimulatory effect on CD43+ cell recruitment after OTM.

The detection of morphine and codeine in human teeth: an aid in the identification and study of human skeletal remains

When studying unidentified putrefied or skeletonised human remains it may be difficult to obtain information on drug habits which may prove important for the construction of a biological profile or lead to hypotheses on the manner of death. The detection of morphine and codeine in teeth from human remains may prove crucial in obtaining such information and thus give forensic odontology and anthropology a further tool for identification. Because teeth can be an important deposit of exogenous substances accumulated both in the pulp and in the calcified tissues, they are an invaluable source of data from a toxicological point of view. The authors therefore tested 3 groups of teeth for morphine and codeine: the first group consisted of artificially aged teeth from individuals known to have died of heroin overdose; the second, of teeth from individuals with no history of drug abuse; the third, of teeth from cases of burnt, putrefied and skeletonised remains found in conditions strongly suggestive of a drug-related death. Results showed that in groups 1 and 3 morphine and codeine could still be identified in the teeth, proving that these tissues may be a reliable source for toxicological information concerning the history of the individual. Further studies are needed to verify whether the substances detected reflect drugs in circulation in an acute phase (and therefore present in blood vessels in the pulp) or whether they represent drugs which have percolated and been stored in dentine and enamel and thus denote a history of drug abuse. Nonetheless this study shows that teeth may be an important source of toxicological information in the forensic scenario.