Dental pulp regeneration via cell homing

The typical treatment for irreversibly inflamed/necrotic pulp tissue is root canal treatment. As an alternative approach, regenerative endodontics aims to regenerate dental pulp-like tissues using two possible strategies: cell transplantation and cell homing. The former requires exogenously transplanted stem cells, complex procedures and high costs; the latter employs the host's endogenous cells to achieve tissue repair/regeneration, which is more clinically translatable. This systematic review examines cell homing for dental pulp regeneration, selecting articles on in vitro experiments, in vivo ectopic transplantation models and in situ pulp revascularization. MEDLINE/PubMed and Scopus databases were electronically searched for articles without limits in publication date. Two reviewers independently screened and included papers according to the predefined selection criteria. The electronic searches identified 46 studies. After title, abstract and full-text examination, 10 articles met the inclusion criteria. In vitro data highlighted that multiple cytokines have the capacity to induce migration, proliferation and differentiation of dental pulp stem/progenitor cells. The majority of the in vivo studies obtained regenerated connective pulp-like tissues with neovascularization. In some cases, the samples showed new innervation and new dentine deposition. The in situ pulp revascularization regenerated intracanal pulp-like tissues with neovascularization, innervation and dentine formation. Cell homing strategies for pulp regeneration need further understanding and improvement if they are to become a reliable and effective approach in endodontics. Nevertheless, cell homing currently represents the most clinically viable pathway for dental pulp regeneration.

Fine-tuning of Th17 Cytokines in Periodontal Disease by IL-10

Periodontitis (PD) is a chronic disease caused by the host inflammatory response to bacteria colonizing the oral cavity. In addition to tolerance to oral microbiome, a fine-tuned balance of IL-10 levels is critical to efficiently mount antimicrobial resistance without causing immunopathology. Clinical and animal studies support that adaptive T-helper (Th) cytokines are involved in the pathogenesis of alveolar bone destruction in PD. However, it remains unclear what type of Th response is related to human PD progression and what role IL-10 has on this process. We addressed the contribution of IL-10 in limiting Th1 and Th17 inflammatory response in murine and human PD. Through a combination of basic and translational approaches involving selected cytokine-deficient mice as well as human genetic epidemiology, our results demonstrate the requirement for IL-10 in fine-tuning the levels of Th17 (IL-17A and IL-17F) cytokines in experimental and human PD. Of novelty, we found that IL-17F correlated with protection in murine and human PD and was positively regulated by IL-10. To our knowledge, this is the first demonstration of the protective role for IL-17F in PD, its positive regulation by IL-10, and the potential differential role for IL-17A and IL-17F in periodontal disease.

Fluoride release from model glass ionomer cements

Glass ionomer cements (GICs) are an important class of biomedical material used extensively for color matched mercury free, dental restorations. GICs can release clinically beneficial amounts of fluoride and have acceptable handling properties which make them suitable as dental restoratives. The fluoride release of model GICs produced from specially synthesized fluoro-alumino-silicate glasses was studied. Nine glasses of varying fluoride content based on 4.5SiO(2)-3Al(2)O(3)-1.5P(2)O(5)-(5-Z)CaO-ZCaF(2) were synthesized and cement disks were prepared from them. The glass transition temperature reduced with increasing fluorine content of the glass. Fluoride ion release was measured into distilled water as a function of time for up to 140 days using a fluoride ion selective electrode. The quantity of fluoride released was found to be proportional to the fluorine content of the glass at all intervals time. The cumulative fluoride release was proportional to square root time. Substituting strontium for calcium in the glass had little influence on the fluoride release behavior of the cements.

N-acetyl-β-d-glucosaminidase activity in urine of dental personnel

BACKGROUND

Dental personnel is exposed to several potential nephrotoxic agents. Urinary N-acetyl-beta-d-glucosaminidase (U-NAG) activity has emerged as a sensitive marker of early nephrotoxicity.

METHODS

U-NAG was evaluated, by fluorimetric assay, in urine from 30 healthy subjects and 30 dental personnels.

RESULTS

The median value of U-NAG activity (133.5 U/mmol urinary creatinine (U-Cr) in urines of dental personnel was not statistically different (P>0.05) from activity (100.7 U/mmol U-Cr) of control urines.

CONCLUSIONS

The results suggest that, for dental personnel, exposure to potential nephrotoxic agents is not usually high enough to increase U-NAG activity.

Dentin dysplasia type I. Report of case and ultrastructural study

Radicular dentin dysplasia (DD-I) is a rare hereditary dental alteration. It is characterized clinically by almost normal looking crowns and severe hypermobility of the teeth. The radiographic analysis, on the other hand, discloses the obliteration of all pulp chambers, the short, malformed roots and plenty of periapical bone radiolucencies on noncarious teeth. A case of radicular dentin dysplasia is presented. In this 43-year-old woman the diagnosis was supported, besides the clinical and radiographic analysis, by the pedigree of the proband, which showed the autosomal dominant pattern of feature transmission. Further-more, the electron microscopic analysis of one extracted molar revealed the atubular structure of the secondary dentin, and its globular organization.

Paediatric endodontics Part 2: Pulp regeneration: current approaches

Dental pulp regeneration: An overview of the current approaches. Regenerative Endodontic Procedures (REPs) are biologically based procedures aimed at restoring the damaged structures and physiological functions of the pulp-dentine complex. Clinically, two strategies have been proposed so far to induce REP: cell transplantation and cell homing. REPs success relies primarily on the clinical and biological conditions of the tooth; therefore, cell homing strategies will not be consistently successful in every condition. Root canal treatment remains the standard of care for mature teeth with necrotic pulps and closed apex.

[Histopathological and therapeutical aspects of cervical lesions]

The term "cervical lesions" definies all the alterations consisting in a loss of hard dental tissues located along the cement-enamel junction, and may be more specifically defined as carious lesions (LCC) and non-carious lesions (NCCL). The non-carious cervical lesions are characterized by the loss of mineralised dental tissue in the absence of a carious process. This definition includes three different lesion categories: abrasion, erosion and the cervical lesions caused by stress (abfractions). In this paper the authors explain the histological, clinical, preventive findings of NCCL and try to give some guidelines to choose the appropriate material to restore different types of non carious cervical lesions.

[Dental pulp diseases. Ultramicroscopic studies]

After the description of the anatomic and histologic aspects of the healthy dental pulp, stress is laid on pulpal pathologies and on the use of ultramicroscopic techniques to analyze the cytologic modifications in normal and pathologic dental pulp tissues. The results obtained are presented.

[A SEM analysis of in vivo adhesive interface between a bonding agent and normal or sclerotic dentin]

AIM

Although dentine is a dynamic sub-stratum of the tooth, it seems correct to say that as far as etching and bonding to the sclerotic dentine is concerned, there are different micro-morphological aspects to be analysed in comparison to those on the healthy dentin.

METHODS

This paper seeks to analysis the interface between the dentin and the adhesive bonding material resulting from in vivo placement of a 5(th) generation dentin bonding system on the base of cavities in 8 teeth. The teeth were removed for periodontal or orthodontic reasons and then examined by scanning electron microscopy.

RESULTS

The results confirm the notable complexity of the dentin-adhesive interface that is developed or formed in-vivo and is due to the different state in which the dentine is found (healthy or sclerotic).

CONCLUSION

It is underlined that the passage from the state of healthy to sclerotic dentin is very fast.

[Fluoride release properties of GRACs. A survey of the literature]

While numerous publications have documented the anticariogenic properties of GPACs through fluoride release measurements and artificial caries studies, considerable debate still exists concerning the fluoride release properties of these materials in terms of dissolution and diffusion mechanisms. This paper will review some of the more important aspects of GPAC fluoride release. Numerous studies have reported on the fluoride release properties of GPACs. The first point to note is that all the studies were performed on commercial materials. This approach has inherent difficulties as the main factor governing fluoride release is the GPAC composition and formulation. Traditional GPACs are two component systems, consisting essentially of a ion leachable fluoroaluminosilicate glass and a polymeric acid, especially a polycarboxylic acid; fluoride ions are of prime importance in this reaction, in that they have a major influence on the structure of the glass, its reactivity, cement formation and bioactivity. GPACs may be viewed as particle reinforced polymeric composites, in which the degraded residual glass particles with their silicious layer reinforce the polysalt matrix, improving mechanical properties.

[Action of etching acid on lining materials]

A review was made of the literature concerning intermediate materials for composite resin fillings and the possibilities of ortho-phosphoric acid infiltration. An experimental study was aimed at evaluating the damages caused by the acid action of the etching material on various type of base materials used. In conclusion, various procedures are suggested for composite resin restoration in order to avoid the risks of lesions of the pulp-dentin organ.