Histomorphometric analysis of odontoblast-like cell numbers and dentine bridge secretory activity following pulp exposure

Efficacy of Mineral Trioxide Aggregate and Photobiomodulation on Pulp Capping of Dogs’ Teeth

AIM: The present study assessed the effect of mineral trioxide aggregate (MTA) and photobiomodulation (PBM) on pulp capping of exposed pulp of dogs’ teeth. METHODS: Forty-eight teeth in three mongrel dogs were randomly divided into two major study groups; Group I where MTA was used as a pulp capping agent and Group II in which both MTA+PBM were used. The groups were equally subdivided according to the observation period following completion of pulp capping into Subgroup (A) 1 week, Subgroup (B) 2, and Subgroup (C) 16 weeks. The teeth were examined for histological inflammatory response as well as dentine bridge formation. RESULTS: With regard to inflammatory response at 1 week significantly, less intense inflammation was observed in MTA+PBM (Group II) compared to the MTA (Group I) for the same time period with no significant difference for between Group I and Group II for other time intervals. As for dentin bridge formation, PBM+MTA groups showed statistically significant thicker dentine bridge formation at 16 weeks than MTA alone group for the same time period with no significant difference for between Group I and Group II for other time intervals. CONCLUSIONS: Under the conditions of this study, PBM appeared to be a beneficial adjunct in dental pulp capping procedures in which MTA was the pulp capping material.

Minimal Intervention in Dentistry: A Literature Review on Biodentine as a Bioactive Pulp Capping Material

Root canal treatment has been the treatment of choice for carious pulp exposures. In the perspective of minimally invasive dentistry and preventive endodontics, a direct pulp capping procedure with a reliable bioactive material may be considered an alternative approach provided that the pulp status is favorable. However, the treatment of pulp exposure by pulp capping is still a controversial issue with no clear literature available on this topic, leaving the concerned practitioner more confused than satisfied. Biodentine is a relatively new bioactive material explored for vital pulp therapy procedures. This article discusses its role in direct pulp capping procedures. A thorough literature search of the database was done using PubMed, Google Scholar, and Scopus using the keywords preventive endodontics, calcium silicate cement, direct pulp capping, Biodentine, and vital pulp therapy. Reference mining of the articles that were identified was used to locate other papers and enrich the findings. No limits were imposed on the year of publication, but only articles in English were considered. This paper is aimed at reviewing the current literature on Biodentine as a direct pulp capping material. The review will provide a better understanding of Biodentine's properties and can aid in the decision-making process for maintaining the vitality of exposed dental pulp with minimal intervention.

Effect of Tricalcium Silicate on Direct Pulp Capping: Experimental Study in Rats

Objectives Conduct a histological comparison of the pulp response to different materials, with a focus on the continuity and morphology of the mineralized barrier after direct pulp capping.

Materials and Methods  One hundred and eight maxillary first molars of 54 Wistar rats were subject to direct pulp capping and divided into three groups according to the materials used: calcium hydroxide (CH), mineral trioxide aggregate (MTA), and Biodentine. All cavities were sealed, and the animals were euthanized at 7, 14, and 21 days. Descriptive histological evaluation of the inflammation and formation of the mineralized barrier was performed.

Statistical Analysis  Statistical analyses were performed using the Kruskal–Wallis test, which was complemented by the Dunn test; differences with p < 0.05 were considered statistically significant.

Results  The results showed that MTA and Biodentine elicited less intense inflammatory reactions than CH. With respect to the formation and quality of the dentin barrier formed, differences were observed at 21 days between the analyzed groups; the best results being obtained following treatment with MTA and Biodentine.

Conclusion  MTA and Biodentine induced formation of a more continuous and uniform mineralized barrier with less intense pulp response than CH.

Clinical and Histological Study on Direct Pulp Capping With CO2 Laser Irradiation in Human Teeth

The study aimed to histologically evaluate wound healing of exposed human pulp on direct pulp capping using super-pulsed CO₂ laser preirradiation. In this single-blind clinical trial, 28 third molar teeth of 17 volunteers were randomly capped with either CO₂ laser irradiation (n=14) or Dycal (calcium hydroxide cement; n=14) and restored using resin composite. The laser was operated in super-pulsed mode (pulse duration, 0.2 ms; interval, 5.8 ms; 0.003 J/pulse). The irradiation conditions were a power output of 0.5 W, an irradiation time of 15 seconds, repeat mode (10-ms irradiation and 10-ms intervals, for a total beam exposure time of 7.5 seconds), total applied energy of 3.75 J, and an activated air-cooling system. Each tooth was extracted at six or 12 months posttreatment and prepared for histological evaluation. We evaluated the parameters of pulp tissue disorganization, inflammatory cell infiltration, reparative dentin formation (RDF), and bacterial penetration. There were no significant differences between groups for all parameters at each postoperative period (Mann-Whitney U-test, p>0.05). CO₂ laser irradiation completely controlled bleeding and exudate from the exposed pulp. The CO₂ laser group had a tendency to delay RDF compared with the Dycal group, but 4 of 7 teeth from the CO₂ laser group showed a complete dentin bridge at 12 months posttreatment.

Efficacy of Enamel Matrix Derivative in Vital Pulp Therapy: A Review of Literature

Introduction:

Vital pulp therapy (VPT) aims to preserve the health and maintain life of the tooth pulp which has been compromised by caries, trauma or restorative procedures. Recently, enamel matrix derivative (EMD) has been introduced as a material for vital pulp therapy. The aim of this review is to critically analyze and summarize the available literature on EMD for VPT.

Methods and Materials:

Online databases (PubMED/MEDLINE, Google Scholar, ISI Web of Science, and Wiley-Online) were searched by using the following keywords in various combinations: Enamel Matrix Derivative, Emdogain, ‘Vital Pulp Therapy, ‘Apexogenisis’, Apexification, Pulp Capping, Endodontics, Dentine and Pulpotomy for studies indexed from January 1949 to April 2016. We used an English-limited search in Google.co.uk for the missing grey literature. All studies fulfilling the selection criteria were carefully reviewed for the focused question: “Does using EMD in VPT, compared with other materials, result in better clinical, radiographic and histological outcomes?”.

Results:

The primary search resulted in 18 articles of which, 14 articles (including 6 animal studies and 6 clinical trials and 2 case reports) met the inclusion criteria for this review and hence were included. The number of teeth tested in the animal studies ranged from 8 to 144 including pigs, rats and dogs teeth. A number of studies used EMD in the experimental group in comparison with calcium hydroxide, propylene glycol alginate (PGA) and MTA as a control. The observation period ranged from 1 to 2 months and 4 out of 6 animal trials reported more favorable outcomes with EMD while two studies reported comparable outcomes.

Conclusion:

Although EMD has potential for various applications in endodontics, studies conducted to date have failed to demonstrate any significant advantage of EMD over conventional VPT materials. Additionally, the 5-year and 10-year survival rate of EMD-treated teeth is not yet known. Hence, studies with a longer follow-up periods are required to deduce the long-term viability of teeth treated with EMD.

Temporospatial localization of dentine matrix protein 1 following direct pulp capping with calcium hydroxide in rat molars

AIM

To examine the temporospatial expression of dentine matrix protein 1 (DMP1; a noncollagenous protein involved in mineralized tissue formation), osteopontin (another noncollagenous protein detected during reparative dentinogenesis) and nestin (a marker of differentiating/differentiated odontoblasts), following direct pulp capping with calcium hydroxide in rat molars.

METHODOLOGY

The maxillary first molars of 8-week-old Wistar rats had their pulps exposed and capped with calcium hydroxide. The pulp-capped teeth were collected from 6 h to 14 days postoperatively and processed for immunohistochemistry for DMP1, osteopontin and nestin. Cell proliferation was monitored using 5-bromo-2'-deoxyuridine (BrdU) labelling.

RESULTS

The capped pulps initially exhibited superficial necrotic changes followed by the formation of new matrix and its mineralization. DMP1 immunoreactivity was observed in the matrix beneath the necrotic layer from 6 h onwards and present in the outer portion of the newly formed mineralized matrix from 7 days onwards. Osteopontin displayed a similar expression pattern, although it occupied a narrower area than DMP1 at 6 and 12 h. Nestin-immunoreactive cells appeared beneath the DMP1-immunoreactive area at 1 day, were distributed beneath the newly formed matrix at 5 days and exhibited odontoblast-like morphology by 14 days. BrdU-positive cells significantly increased at 2 and 3 days (P < 0.05) and then decreased.

CONCLUSIONS

The deposition of DMP1 at exposed pulp sites preceded the appearance of nestin-immunoreactive cells, active cell proliferation and new matrix formation after pulp capping with calcium hydroxide in rat molars, suggesting that DMP1 acts as a trigger of pulp repair. The colocalization of DMP1 and osteopontin suggests that these two proteins play complementary roles.

Is hard tissue formation in the dental pulp after the death of the primary odontoblasts a regenerative or a reparative process?

OBJECTIVES

Conceptually, two types of tertiary dentine may be produced in response to caries and environmental irritations: "reactionary dentine" that is secreted by existing primary odontoblasts and "reparative dentine", formed after the death of the odontoblasts by proliferation and differentiation of progenitor cells into odontoblast-like cells. Because histologic evidence for tubular dentine generated by newly differentiated odontoblast-like cells is lacking in human teeth, the present study examined pulpal cellular changes associated with caries/restorations, in the presence or absence of pulpal exposures.

METHODS

Ninety-six extracted human teeth were histologically processed and serial sectioned for light microscopy: 65 contained untreated enamel/dentine caries; 20 were heavily restored and 11 had carious exposures managed by direct pulp-capping.

RESULTS

Sparsely distributed, irregularly arranged dentinal tubules were identified from the tertiary dentine formed in teeth with unexposed medium/deep caries and in restored teeth; those tubules were continuous with the tubules of secondary dentine; in some cases, tubules were absent. The palisade odontoblast layer was reduced to a single layer of flattened cells. In direct pulp-capping of pulp exposures, the defects were repaired by the deposition of an amorphous dystrophic calcified tissue that resembled pulp stones more than dentine, sometimes entrapping pulpal remnants. This atubular hard tissue was lined by fibroblasts and collagen fibrils.

CONCLUSIONS

Histological evidence from the present study indicates that reparative dentinogenesis cannot be considered as a regenerative process since the so-formed hard tissue lacks tubular features characteristic of genuine dentine. Rather, this process represents a repair response that produces calcified scar tissues by pulpal fibroblasts.

CLINICAL SIGNIFICANCE

Formation of hard tissue in the dental pulp after the death of the primary odontoblasts has often been regarded by clinicians as regeneration of dentine. If the objective of the clinical procedures involved is to induce healing, reduce dentine hypersensitivity, or minimise future bacteria exposure, such procedures may be regarded as clinical success. However, current clinical treatment procedures are not adept at regenerating physiological dentne because the tissues formed in the dental pulp are more likely the result of repair responses via the formation of calcified scar tissues.

Photoactivation of endogenous latent transforming growth factor-β1 directs dental stem cell differentiation for regeneration

Rapid advancements in the field of stem cell biology have led to many current efforts to exploit stem cells as therapeutic agents in regenerative medicine. However, current ex vivo cell manipulations common to most regenerative approaches create a variety of technical and regulatory hurdles to their clinical translation, and even simpler approaches that use exogenous factors to differentiate tissue-resident stem cells carry significant off-target side effects. We show that non-ionizing, low-power laser (LPL) treatment can instead be used as a minimally invasive tool to activate an endogenous latent growth factor complex, transforming growth factor-β1 (TGF-β1), that subsequently differentiates host stem cells to promote tissue regeneration. LPL treatment induced reactive oxygen species (ROS) in a dose-dependent manner, which, in turn, activated latent TGF-β1 (LTGF-β1) via a specific methionine residue (at position 253 on LAP). Laser-activated TGF-β1 was capable of differentiating human dental stem cells in vitro. Further, an in vivo pulp capping model in rat teeth demonstrated significant increase in dentin regeneration after LPL treatment. These in vivo effects were abrogated in TGF-β receptor II (TGF-βRII) conditional knockout (DSPP(Cre)TGF-βRII(fl/fl)) mice or when wild-type mice were given a TGF-βRI inhibitor. These findings indicate a pivotal role for TGF-β in mediating LPL-induced dental tissue regeneration. More broadly, this work outlines a mechanistic basis for harnessing resident stem cells with a light-activated endogenous cue for clinical regenerative applications.

Efficacy of the enamel matrix derivative in direct pulp capping procedures: a systematic review

The aim was to review the efficacy of the enamel matrix derivative (EMD) in direct pulp capping (DPC) procedures. Databases were explored using the following keywords: 'dental', 'dentine', 'enamel matrix derivative', 'pulp capping' and 'treatment'. The inclusion criteria were: (i) original studies; (ii) human and animal studies; (iii) reference list of potentially relevant original and review articles; (iv) intervention: effect of EMD on pulp-capping procedures; and (v) articles published only in English. Eight studies (four human and four animal) were included. Among the human studies, two studies reported that EMD is a more efficient DPC procedure compared with calcium hydroxide (Ca(OH)2 ). One study reported Ca(OH)2 to be more efficient for DPC than EMD. One study reported no difference in the efficacies between EMD and Ca(OH)2 for DPC. All animal studies reported EMD to be more effective in reparative dentine formation in comparison with Ca(OH)2 . EMD can provide favourable results in DPC procedures.

Revisiting traumatic pulpal exposure: materials, management principles, and techniques

This article presents current concepts of managing teeth with traumatic pulp exposures. The article includes a description of the traumatology of crown fractures, discussion of treatment considerations, a summary of materials for vital pulp therapy, and an outline of techniques for treating pulp exposures.

Efficacy of EMD versus calcium hydroxide in direct pulp capping of primary molars: a randomized controlled clinical trial

OBJECTIVE

The aim was to compare the clinical and radiographic efficacy of enamel matrix derivative and self-hardening calcium hydroxide as direct pulp capping materials on decayed primary molars, with observation periods of 1, 6, and 12 months.

STUDY DESIGN

A clinical, randomized, controlled trial was performed, following the "split-mouth" design. A total of 90 primary molars were treated. Assignation of materials and operative initial side were selected in a randomized manner. Five outcome variables were considered: internal dentin resorption, pain, gingival sinus tract, root external resorption, and pathologic mobility. The appearance of any of these signs or symptoms was considered to be a failure of treatment.

RESULTS

Significant statistical or clinical differences were not found between the study groups. Two treatments were judged as failures, 1 per study group; both occurred during the first postoperative month.

CONCLUSIONS

The technique used for direct pulp capping on primary molars in this study is recommended on the basis of the obtained clinical and radiographic results.

Histological evaluation of platelet rich plasma and hydroxiapatite in apexogenesis: Study on experimental animals

Background/Aim. There are very few data about the effects of endogenous growth factors in vital pulp therapy, and still they are often controversial. The aim of the study was to evaluate the effects of platelet rich plasma (PRP) in conjugation with hydroxyapatite (HAP), as pulp capping materials, to root and periodontium formation. Methods. Eight young monkeys (Cercopithecus Aethiops) with permanent dentition and incomplete root formation were involved in this study. After pulpotomy, the pulp lesion was capped with calcium hydroxide (control), hydroxyapatite (experimental group I) or hydroxyapatite in conjugation with PRP (experimental group II). Six months later, the animals were sacrificed, the tissue was removed en block, and prepared for the histological analysis in a routine way. Results. The results of the histological analysis revealed that healing process was characterised by dentin bridge formation, maintained morphological and functional integrity of dental pulp and complete formation of dental root and surrounding periodontium. The inflammatory reaction was scored as mild to moderate, in almost all the samples in all groups, suggesting the biocompatibility of the used materials. Conclusion. Materials used in this study are convenient as capping agents, contributing maintaining the integrity of the pulp tissue and facilitating root and periodontium formation. According to histological data it could be suggested that hydroxyapatite in conjugation with endogenous growth factors, represents superior alternative to other materials used in this study.

Regenerative endodontics: a review of current status and a call for action

Millions of teeth are saved each year by root canal therapy. Although current treatment modalities offer high levels of success for many conditions, an ideal form of therapy might consist of regenerative approaches in which diseased or necrotic pulp tissues are removed and replaced with healthy pulp tissue to revitalize teeth. Researchers are working toward this objective. Regenerative endodontics is the creation and delivery of tissues to replace diseased, missing, and traumatized pulp. This review provides an overview of regenerative endodontics and its goals, and describes possible techniques that will allow regenerative endodontics to become a reality. These potential approaches include root-canal revascularization, postnatal (adult) stem cell therapy, pulp implant, scaffold implant, three-dimensional cell printing, injectable scaffolds, and gene therapy. These regenerative endodontic techniques will possibly involve some combination of disinfection or debridement of infected root canal systems with apical enlargement to permit revascularization and use of adult stem cells, scaffolds, and growth factors. Although the challenges of introducing endodontic tissue engineering therapies are substantial, the potential benefits to patients and the profession are equally ground breaking. Patient demand is staggering both in scope and cost, because tissue engineering therapy offers the possibility of restoring natural function instead of surgical placement of an artificial prosthesis. By providing an overview of the methodological issues required to develop potential regenerative endodontic therapies, we hope to present a call for action to develop these therapies for clinical use.