Analysis of pulp histological response to pulpotomy performed with white mineral trioxide aggregate mixed with 2.25% sodium hypochlorite gel in humans: a randomized controlled clinical trial

This study aimed to evaluate the histological success of pulpotomy in primary molars using white mineral trioxide aggregate (WMTA) mixed with 2.25% sodium hypochlorite (NaOCl) gel and to evaluate in vitro its physical and chemical properties. The study had a clinical stage and an in-vitro stage. The clinical study was conducted with 24 patients aged 8-10 years. It was a randomized controlled trial to perform a histologic evaluation of pulp response following pulpotomy. Primary first molars were randomly assigned in split mouth model to control group-WMTA + distilled water (DW) or experimental group - WMTA + NaOCl gel. Teeth were extracted after 7, 30 or 90 days and submitted to histological analysis. The second stage was an in-vitro study to evaluate the physical and chemical properties of the two materials tested. SEM and EDX analyses and pH level evaluations were performed after 24 h and 28 days. The histological findings revealed that while WMTA + NaOCl gel group showed better odontoblastic integrity (P < 0.05), WMTA + DW group had more favorable outcomes in dentin bridge formation and pulp calcification (P < 0.05). Pulp tissue hemorrhage and pulp fibrosis were similar between them (P > 0.05). Regarding materials' in vitro evaluation, the pH level indicated a higher initial pH for the WMTA + NaOCl gel group, which equalized after 28 days. SEM analysis initially showed a less homogeneous surface for WMTA + NaOCl gel, but it became similar after 28 days. EDX analysis indicated higher calcium and silicon percentages in the WMTA + NaOCl gel group initially, which increased in both groups after 28 days. Adding 2.25% NaOCl gel to WMTA enhanced odontoblastic integrity in both the short and medium term. In addition, it had a similar chemical composition, surface morphology, and alkalinity when compared to WMTA + DW mixture.

Guidance for evaluating biomaterials' properties and biological potential for dental pulp tissue engineering and regeneration research

BACKGROUND

Dental pulp regeneration is a complex and advancing field that requires biomaterials capable of supporting the pulp's diverse functions, including immune defense, sensory perception, vascularization, and reparative dentinogenesis. Regeneration involves orchestrating the formation of soft connective tissues, neurons, blood vessels, and mineralized structures, necessitating materials with tailored biological and mechanical properties. Numerous biomaterials have entered clinical practice, while others are being developed for tissue engineering applications. The composition and a broad range of material properties, such as surface characteristics, degradation rate, and mechanical strength, significantly influence cellular behavior and tissue outcomes. This underscores the importance of employing robust evaluation methods and ensuring precise and comprehensive reporting of findings to advance research and clinical translation.

AIMS

This article aims to present the biological foundations of dental pulp tissue engineering alongside potential testing methodologies and their advantages and limitations. It provides guidance for developing research protocols to evaluate the properties of biomaterials and their influences on cell and tissue behavior, supporting progress toward effective dental pulp regeneration strategies.

Comparing effectiveness of mineral trioxide aggregate, bioceramic putty and tannic acid in maintaining pulp vitality after experimental pulpotomy in rats

This study aimed to evaluate and compare the effectiveness of mineral trioxide aggregate (MTA), bioceramic putty (BP) and tannic acid (TA) for experimental pulpotomy. Our in-vivo experimental study involved sample of 45 rats that were randomly divided into 4 groups: Group 1 (subdivided into negative (1-A) and positive (1-B) subgroups), Group 2 (MTA treated), Group 3 (BP treated) and Group 4 (TA treated). 4 weeks post pulpotomy, specimens were analyzed histologically, immunohistochemically using dentin sialoprotein marker, and histomorphometrically by assessing the thickness of newly formed dentin bridge. Group 1-B showed pulp necrosis without hard tissue formation. Group 2 showed moderate dentin formation while group 3 presented a thick layer of calcific barrier. Group 4 showed dentin bridge formation, however, irregular pulp calcifications and radicular pulp necrosis were seen. The thickness of newly formed dentin bridge showed a significant difference between group 1-B and group 2, 3 &4. Significant difference was found between group 2&3 and group 3&4. Dentin sialoprotein immunohistochemical expression was negative in group 1-B, mild in group 2, strong in group 3 and moderate in group 4. MTA and BP proved to be effective pulpotomy agents with BP being superior. For TA, further studies are required to explain the recorded unfavorable effects in some specimens.

Poly(Aspartic Acid) Promotes Odontoblast-like Cell Differentiation in Rat Molars with Exposed Pulp

In recent years, alternative pulpal therapies targeting dentinogenesis signaling pathways using different peptides have been investigated. The aim of this study was to verify the effectiveness of poly(aspartic acid), pAsp, in dentin regeneration using an animal model.

METHODS

Mechanical pulp exposure was performed in the upper molars of 56 Wistar rats, randomly divided as follows (n = 14): control (no treatment); MTA group-pulp capping with mineral trioxide aggregate (MTA Angelus); pAsp group-application of 20 μL of pAsp solution (25 mg·mL-1); MTA+pAsp group-application of MTA mixed with pAsp (5:1 by mass). Animals were euthanized after 7 or 21 days. Histological sections were submitted to hematoxylin-eosin and Brown and Brenn staining and immunohistochemical analysis for osteopontin (OPN) and dentin matrix protein 1 (DMP 1).

RESULTS

At 7 days, an acute inflammatory infiltrate and the presence of disorganized mineralized tissue were observed in all groups. At 21 days, the quality and thickness of the reparative dentin in treated groups were superior to the control, and bacterial contamination was observed in two MTA-pAsp specimens. While all treated groups showed intense immunostaining for OPN at 21 days, only the pAsp group expressed DMP 1, indicating the presence of fully differentiated odontoblast-like cells.

CONCLUSION

Poly(aspartic) acid promoted dentin regeneration in rat molars in the absence of an additional calcium source and may be an alternative to MTA as a pulp-capping agent.

Inflammatory response and odontogenic differentiation of inflamed dental pulp treated with different pulp capping materials: An in vivo study

AIM

Previous studies have evaluated the pulpal responses to calcium silicate cements (CSCs) on normal dental pulp, but investigations on the effects of CSCs on inflamed pulp are limited. This study aimed to test the inflammatory response and odontogenic differentiation of inflamed rat dental pulp after direct pulp capping with CSCs.

METHODOLOGY

Wistar rat molars pulps were exposed for 48 h to induce inflammation and then capped with ProRoot MTA (Dentsply), Biodentine (Septodont), RetroMTA (Bio MTA) and Dycal (Dentsply Caulk). The degree of pulpal inflammation and hard tissue formation was evaluated by histological analysis. Immunofluorescence staining for interleukin (IL)-6, osteocalcin (OCN) and runt-related transcription factor 2 (RUNX2) was also performed.

RESULTS

After 4 weeks, complete recovery from inflammation was evident in 22%, 37.5%, 10% and none of the ProRoot MTA, Biodentine, RetroMTA and Dycal samples, respectively. Heavy hard tissue deposition as a continuous hard tissue bridge was observed in 77.8%, 75%, 70% and 60% of the ProRoot MTA, Biodentine, RetroMTA and Dycal samples, respectively. IL-6, OCN and RUNX2 were detected in all materials, mainly adjacent to areas of inflammation and reparative dentine formation. At one, two and 4 weeks, significant differences were not observed between the inflammation and hard tissue formation scores of the four material groups (p > .05).

CONCLUSIONS

In this study, pulpal inflammation was still present in most specimens at 4 weeks after pulp capping and a significant number of samples showed incomplete and discontinuous dentine bridge formation. The results of this study suggest that initial inflammatory conditions of the pulp may risk the prognosis of teeth treated with CSCs.

Vitronectin-Derived Peptide Promotes Reparative Dentin Formation

Exposed dental pulp can maintain its vitality through a pulp-capping procedure with biocompatible materials, followed by reparative dentin formation. Our previous study demonstrated that a vitronectin-derived peptide (VnP-16) promotes osteoblast differentiation and concomitantly restrains osteoclast differentiation and resorptive function. In this study, we aimed to demonstrate that VnP-16 promotes odontoblast differentiation, mineralization, and reparative dentin formation in a pulp exposure model using a rat tooth. VnP-16 showed no cytotoxicity and promoted cellular behavior in human dental pulp cells, enhancing their differentiation into odontoblast-like cells and mineralization, effects that are comparable to those obtained with vitronectin. In a rat pulp exposure model, VnP-16 showed mild inflammatory responses at 2 and 4 wk or none. Mineral trioxide aggregate (MTA) demonstrated a tendency of early formation of reparative dentin at 2 wk when compared with recombinant human bone morphogenetic protein 2 (rhBMP-2) and VnP-16. However, VnP-16 induced reparative dentin formation similar to MTA and rhBMP-2 without inflammation at 4 wk. In addition, VnP-16 showed a thicker and homogeneous reparative dentin formation versus MTA and rhBMP-2. Collectively, these results suggest that VnP-16 can be a useful, direct pulp-capping agent for highly qualified reparative dentin formation by promoting cell behavior and odontoblastic differentiation of human dental pulp cells.

Effect of different intracanal medicaments on the fracture resistance of the human root

Background:

The effect of different intracanal medicaments on root fracture resistance has not been thoroughly investigated in the short and long term. To assess the effect of calcium hydroxide (CH), CH combined with Chlorhexidine (CHX), double antibiotic paste (DAP), and simvastatin as intracanal medicaments on the fracture resistance of the human root. One hundred and twenty single-rooted mandibular premolars which were extracted for periodontal reasons were collected for this in vitro study.

Materials and Methods:

This was an in vitro study. All teeth were decoronated. Root canals were prepared by the Pro taper system, and %2.5 NaOCl was used for irrigation. The smear layer was removed using %5.25 NaOCl and 17% ethylenediaminetetraacetic acid each for 3 min. The samples were randomly divided into five groups based on the medicament: (1) CH (2) CH + CHX (3) Simvastatin (4) DAP (5) Control group. All specimens in each group were incubated for 1 week (Subgroup A) and 1 month (Subgroup B). Then, medicaments were removed and filled with gutta-percha and AH26 sealer. All samples were tested for fracture resistance. The data were statistically evaluated with the SPSS software 17. ANOVA and Mann–Whitney U and Wilcoxon tests were used for the analysis of the data. P = 0.05 was considered statistically significant.

Results:

Although CH and CH + CHX increased the fracture resistance in a 1-week period, there was no significant difference between the groups after 1 month.

Conclusion:

Under the limitations of this study, CH and CH + CHX, DAP and simvastatin do not have a negative effect on root fracture resistance when used as intracanal medicaments for <1 month.

Influence of Pregnancy on the Inflammatory Process Following Direct Pulp Capping: a Preliminary Study in Rats

The purpose of this study was to evaluate the inflammatory process following direct pulp capping during pregnancy. This experimental study involved 48 maxillary first molars of female Wistar rats. The procedures were performed in pregnant and non-pregnant animals (n =20 each). Direct pulp capping with mineral trioxide aggregate (MTA) and restoration with a light-cured resin composite was performed in half of exposed pulp specimens. In the other half of specimens, light-cured composite was placed directly on the exposed pulp. In the control groups (n=4 each), no intervention was performed. Animals were euthanized at 3 and 7 days. All sections (three per slide) were viewed under an optical microscope. One previously calibrated pathologist performed descriptive analysis and assigned scores for inflammatory response and tissue organization adjacent to the pulp exposure. The Kappa value for intra-examiner variability was 0.91. At 3 days, in animals treated with MTA, inflammatory infiltrate was absent in non-pregnant animals while mild inflammatory infiltrate was observed in some pregnant animals. The inflammatory response ranged from mild to severe in both groups treated with composite alone. At 7 days, the inflammatory response was more intense in pregnant than in non-pregnant animals treated with MTA; while this difference were not evident in animals treated with composite alone. In conclusion, pregnancy may not influence the inflammatory process following direct pulp capping with light-cured resin composite, which was always harmful to the pulp; while the tissue response after the direct pulp with MTA were more favorable in non-pregnant animals.