The effects of hyaluronic acid, calcium hydroxide, and dentin adhesive on rat odontoblasts and fibroblasts

Histological evaluation of different concentrations of hyaluronic-acid-added zinc oxide eugenol on rat molar pulp

Hyaluronic acid (HA), known for diverse properties, was investigated for its potential in dental pulp therapy. This study investigated the potential of HA in dental pulp therapy by examining the physical properties and effects of zinc oxide eugenol (ZOE) pulpotomy materials containing varying HA concentrations on rat molar teeth. In vitro tests assessed compressive strength and hardness of ZOE materials blended with HA (0.5%, 1%, 3%) and HA gels (0.54%, 0.8%). 120 samples, encompassing the control group, underwent compressive strength testing, while 60 samples were designated for hardness assessment. In vivo experiments on rat molars studied histological effects of HA-containing ZOE on dental pulp over 1 week and 1 month. Gels with HA concentrations of 0.5%, 1%, and 0.54% were used in pulpotomy on 22 rats. Each rat underwent the procedure on four teeth, with one tooth serving as a control, totaling 88 teeth subjected to the intervention. In the analyses, SPSS 22.0 was used and the significance level was set at P = 0.05. Findings showed that HA at 0.5% maintained compressive strength, but higher concentrations decreased mechanical properties significantly (P = 0.001). Histological assessments indicated better outcomes with lower HA concentrations in terms of odontoblast layer continuity (P = 0.005 at 1 month) and pulp vitality (P = 0.001 at 1 week and P = 0.018 at 1 month). The study suggests HA holds promise for pulpotomy and regenerative endodontic treatments, but further research is needed to understand long-term clinical implications.

Different pulp capping agents and their effect on pulp inflammatory response: A narrative review

Several factors can directly damage dental pulp. Pulp healing requires controlled inflammation, which can be directed through specialized medical materials to eliminate infection and promote pulp repair. This review aimed to categorise these materials and identify their histological and molecular effects on pulp tissue or isolated cells in culture. In addition, we sought to identify which of these materials could trigger a favourable inflammatory pathway that could direct the pulpal response toward healing and regeneration. A single database (PubMed) was used, and the search strategy was based on MeSH terms. The search was conducted for articles published in English between January 2010 and December 2023, including those with histological and molecular findings. Only 33 articles met our inclusion criteria. Several conventional pulp capping agents have been shown to induce pulp healing and repair through dentine bridge formation. These materials show varying degrees of inflammation, ranging from moderate to mild, which may diminish over time. Other experimentally developed materials were also studied, either alone or in combination with conventional products; these materials demonstrated promising potential to reduce inflammation and superficial necrosis associated with conventional products. However, they still do not meet all the criteria for ideal pulp-capping materials and need further development for commercialisation. Several inflammatory pathways were also addressed in this review, along with favourable tissue responses to induce pulp regeneration. The immunomodulatory role of M2 phenotype macrophages is currently the most accepted, though the lack of standardised experimental procedures across studies hinder precise decision-making.

Hyaluronic acid as a pulpotomy material in primary molars: an up to 30 months retrospective study

BACKGROUND

The aim of this retrospective study was to determine the long-term clinical and radiographic success of our previous randomized clinical trial and to compare the success of hyaluronic acid, with the widely used formocresol and ferric sulphate agents.

METHODS

This retrospective study is the extension of the 1-year survey of our randomized clinical trial that had compared the effectiveness of a hyaluronic acid pulpotomy over formocresol and ferric sulphate pulpotomies and included clinical and radiographic evaluations with a follow-up period of over 24 months for 44 children who applied to our clinic between May 2019 and September 2019. Long-term clinical and radiographic data were obtained from the periodic files of our department, wherein each tooth's file was examined to identify any clinical and radiographic findings. Descriptive statistics and Pearson's chi-square tests were used to evaluate the data. Statistical significance was considered as p < 0.05.

RESULTS

The clinical and radiographic success rates of the hyaluronic acid, formocresol, and ferric sulphate groups were not statistically different at > 24 months. None of the teeth in the hyaluronic acid group showed any clinical findings at > 24 months.

CONCLUSIONS

Hyaluronic acid pulpotomies exhibited comparable success rates to formocresol and ferric sulphate materials spanning over 24 months examinations. Because of convenient accessibility and applicability of hyaluronic acid, it may be recommended as a promising alternative medicament for pulpotomy treatments of primary molars. However, further long-term follow-up human studies are needed to better understand the effect of hyaluronic acid on the dental pulp of human primary molars.

Immunohistochemical study of mixing mineral trioxide aggregate with hyaluronic acid as a pulp-capping agent in dog teeth

Objective

The purpose of this study was to evaluate the immunohistochemical effect of hyaluronic acid (HA) on the mineralization rate of the reparative dentin when it is used as a mixing medium with mineral trioxide aggregate (MTA).

Materials and Methods

Direct pulp capping (DPC) was performed on 90 teeth from 10 dogs that had been experimentally exposed. The exposed pulps were divided into three groups according to the mixing medium with MTA: Group I: MTA + distilled water (control group), Group II: MTA + hybrid cooperative complex HA (HCC-HA), Group III: MTA + high molecular weight HA (HMW-HA). After pulp capping, all cavities were restored with final restoration. The dogs were divided randomly into five groups (two dogs each) according to the evaluation periods (7, 14, 21, 30, and 60) days. At the end of the study, the dogs were euthanized, and the sampled teeth were processed for immunohistochemical investigation.

Results

Both types of HA (HCC-HA, HMW-HA) showed an increase in the expression of alkaline phosphatase (ALP) at a higher rate than using distilled water with MTA.

Conclusions

Within the limitations of this study, HA proved to be an effective additive to MTA for DPC.

Chemical analysis of mineral trioxide agregate mixed with hyaluronic acids as an accelerant

MATERIALS AND METHOD

Mineral trioxide aggregate (MTA) has many clinical applications in dentistry; the main drawback is the long setting. The main objective is to investigate and compare the chemical effect of using two commercially available hyaluronic acid hydrogels (HA) instead of distilled water for mixing MTA as an accelerant of setting time. Test materials were divided into three groups; Group 1: (control) mixing MTA with distilled water supplied by the manufacturer; Group 2: mixing MTA with a hybrid cooperative complex of high and low molecular weight HA (Profhilo®); Group 3: mixing MTA with High molecular weight / non-cross-linked HA (Jalupro®). Mixing time, and setting time (initial and final) were determined, Fourier-transform infrared spectroscopy, Energy-dispersive X-ray spectroscopy, Field emission Scanning Electron Microscopy, and X-ray diffraction were performed.

RESULTS

mixing time, initial, and final setting time for (MTA + HA) groups were significantly different and lower in comparison to the control group (p < 0.05). This study revealed higher expression of calcium silicate hydrate and calcium hydroxide expression with higher Ca release in the MTA + HA group than the control group.

CONCLUSION

commercially available HA demonstrated better chemical properties when used as a mixing medium for MTA. The Mixing and setting time for MTA + HA group were significantly shorter than those of the control group were. Thus, commercially available HA can be used as a mixing medium for MTA.

A randomized clinical trial of hyaluronic acid gel pulpotomy in primary molars with 1 year follow-up

OBJECTIVE

This randomized clinical study aimed to evaluate the success of hyaluronic acid (HA) as a pulpotomy medicament of human primary molars and to compare it with formocresol (FC) and ferric sulphate (FS) pulpotomy treatments up to 12 months.

MATERIALS AND METHODS

The study was conducted with 130 primary molars of 44 children. The ethical approval and registration to clinical trials (No: NCT04115358) were completed. After the removal of all the coronal pulp tissue, a 0.5% HA gel, or a FC, or a 20% FS solution were applied randomly to the radicular pulp tissues of the primary molars. Then, the pulp chambers were filled with a zinc oxide eugenol cement and restored either with a composite filling material or with a stainless-steel crown. The treatment success rates of the 3 groups were followed and compared clinically and radiographically at 1st-, 3rd-, 6th- and 12th-months.

RESULTS

Primary molars treated with FC, FS and HA dressings were clinically successful 77.5%, 86.8% and 87.5% respectively after 12th-month follow-up (p > .05). Radiographic successes of FC, FS and HA groups were lower than clinical successes (57.6%, 68.8%, 57.9% respectively at the 12th-month) but the difference between the groups was not statistically significant (p > .05). Equivalence analysis assuming not more than 10% difference between the materials suggested that HA was not inferior to FC or FS.

CONCLUSIONS

Within the limitations of this study, our randomized clinical trial shows that HA is a promising pulpotomy medicament in primary molars. However, further studies are justified to further improve the HA material success.

Cryogel composites based on hyaluronic acid and halloysite nanotubes as scaffold for tissue engineering

We present here preparation of mechanically strong and biocompatible cryogel composites based on hyaluronic acid (HA) and halloysite nanotubes (HNTs) of various compositions, and their applications as scaffold for different cell growing media. Uniaxial compression tests reveal that the incorporation of HNTs into HA cryogels leads to a ~2.5-fold increase in their Young moduli, e.g., from 38 ± 1 to 99 ± 4 kPa at a HA:HNTs weight ratio of 1:2. Although HA:HNTs based cryogels were found to be blood compatible with 1.37 ± 0.11% hemolysis ratio at a HA:HNTs weight ratio of 1:2, they trigger thrombogenic activity with a blood clotting index of 17.3 ± 4.8. Remarkably, HA:HNTs cryogel composites were found to be excellent scaffold materials in the proliferation of rat mesenchymal stem cells (MSC), human cervical carcinoma cells (HeLa), and human colon cancer cells (HCT116). The cell studies revealed that an increased amount of HNT embedding into HA cryogels leads to an increase of MSC proliferation.

Modifying Adhesive Materials to Improve the Longevity of Resinous Restorations

Dental caries is a common disease on a global scale. Resin composites are the most popular materials to restore caries by bonding to tooth tissues via adhesives. However, multiple factors, such as microleakage and recurrent caries, impair the durability of resinous restorations. Various innovative methods have been applied to develop adhesives with particular functions to tackle these problems, such as incorporating matrix metalloproteinase inhibitors, antibacterial or remineralizing agents into bonding systems, as well as improving the mechanical/chemical properties of adhesives, even combining these methods. This review will sum up the latest achievements in this field.

Activity of two hyaluronan preparations on primary human oral fibroblasts

Background and Objective

The potential benefit of using hyaluronan (HA) in reconstructive periodontal surgery is still a matter of debate. The aim of the present study was to evaluate the effects of two HA formulations on human oral fibroblasts involved in soft tissue wound healing/regeneration.

Material and Methods

Metabolic, proliferative and migratory abilities of primary human palatal and gingival fibroblasts were examined upon HA treatment. To uncover the mechanisms whereby HA influences cellular behavior, wound healing‐related gene expression and activation of signaling kinases were analyzed by qRT‐PCR and immunoblotting, respectively.

Results

The investigated HA formulations maintained the viability of oral fibroblasts and increased their proliferative and migratory abilities. They enhanced expression of genes encoding type III collagen and transforming growth factor‐β3, characteristic of scarless wound healing. The HAs upregulated the expression of genes encoding pro‐proliferative, pro‐migratory, and pro‐inflammatory factors, with only a moderate effect on the latter in gingival fibroblasts. In palatal but not gingival fibroblasts, an indirect effect of HA on the expression of matrix metalloproteinases 2 and 3 was detected, potentially exerted through induction of pro‐inflammatory cytokines. Finally, our data pointed on Akt, Erk1/2 and p38 as the signaling molecules whereby the HAs exert their effects on oral fibroblasts.

Conclusion

Both investigated HA formulations are biocompatible and enhance the proliferative, migratory and wound healing properties of cell types involved in soft tissue wound healing following regenerative periodontal surgery. Our data further suggest that in gingival tissues, the HAs are not likely to impair the healing process by prolonging inflammation or causing excessive MMP expression at the repair site.

A hyaluronan-based scaffold for the in vitro construction of dental pulp-like tissue

Dental pulp tissue supports the vitality of the tooth, but it is particularly vulnerable to external insults, such as mechanical trauma, chemical irritation or microbial invasion, which can lead to tissue necrosis. In the present work, we present an endodontic regeneration method based on the use of a tridimensional (3D) hyaluronan scaffold and human dental pulp stem cells (DPSCs) to produce a functional dental pulp-like tissue in vitro. An enriched population of DPSCs was seeded onto hyaluronan-based non-woven meshes in the presence of differentiation factors to induce the commitment of stem cells to neuronal, glial, endothelial and osteogenic phenotypes. In vitro experiments, among which were gene expression profiling and immunofluorescence (IF) staining, proved the commitment of DPSCs to the main components of dental pulp tissue. In particular, the hyaluronan-DPSCs construct showed a dental pulp-like morphology consisting of several specialized cells growing inside the hyaluronan fibers. Furthermore, these constructs were implanted into rat calvarial critical-size defects. Histological analyses and gene expression profiling performed on hyaluronan-DPSCs grafts showed the regeneration of osteodentin-like tissue. Altogether, these data suggest the regenerative potential of the hyaluronan-DPSC engineered tissue.

Direct and transdentinal (indirect) antibacterial activity of commercially available dental gel formulations against Streptococcus mutans

OBJECTIVE

To evaluate the direct and transdentinal (indirect) agar diffusion antibacterial activity of different commercially available antibacterial dental gel formulations against Streptococcus mutans.

MATERIALS AND METHODS

The commercially available dental gel formulations were Corsodyl® (COG, 1% chlorhexidine), Cervitec® (CEG, 0.2% chlorhexidine + 0.2% sodium fluoride), Forever Bright® (FOB, aloe vera), Gengigel® (GEG, 0.2% hyaluronic acid), 35% phosphoric acid gel and distilled water (control). Direct agar diffusion was performed by isolating three wells from brain-heart infusion agar plates using sterile glass pipettes attached to a vacuum pump and adding 0.1 ml of the gels to each well. Transdentinal (indirect) agar diffusion was performed by applying gel to 0.2- and 0.5-mm-thick human dentin discs previously etched with phosphoric acid and rinsed with distilled water. Zones formed around the wells and the dentin discs were measured and analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni correction (p < 0.01).

RESULTS

Direct agar diffusion tests showed significant differences among all gel formulations (p < 0.01) except for COG and CEG (p > 0.01). COG and CEG exhibited higher antibacterial effects compared to FOB and GEG (p < 0.01) in both direct and transdentinal (indirect) testing procedures. GEG did not show any antimicrobial activity in transdentinal (indirect) testing.

CONCLUSION

Commercially available dental gels inhibited S. mutans, which may indicate their potential as cavity disinfectants.