In vivo study of the pulp reaction to Fuji IX, a glass ionomer cement

Assessing the impact of dental restorative materials on fibroblast cells: an immunohistochemical and ELISA analysis

In this study, our aim was to investigate the effects of restorative materials such as composite, compomer and high viscosity glass ionomer, which are frequently used in dentistry, on L929 fibroblast cells by evaluating the oxidative stress parameters, pro- and anti-inflammatory cytokines, and apoptosis markers. L929 fibroblast cells were cultured, and dental filling materials were applied in two doses (50 and 100 µl). Immunohistochemical staining was performed for experimental groups with Anti-Bax and Anti-Caspase 9 antibodies. Then, ELISA technique was used to detect the level of TNF-alpha, TGF-beta, IL-1-beta, IL-6, IL-10, LPO and CAT. In the light of the data, the examined dental filling materials were effective on increasing the TGF-beta, IL-10, LPO and CAT levels, and decreasing the TNF-alpha, IL-1-beta, and IL-6 levels. The histological micrographs were also support the issues. When the levels of H-score in Caspase 9 labeled micrographs were evaluated, the mean of the control group was lower than the mean of the experimental groups. Biocompatibility varies according to the content of the material, the amount of residual monomer, and its solubility. Although all the experimental groups have cytotoxic effects, the least effect is seen in the Omnichroma group.

Cytotoxicity of dental cement on soft tissue associated with dental implants at different time intervals

Background: To investigate and compare the effect of four commercially used dental cement at 24 hours, 48 hours,72 hours (h) and 6 days on the cellular response of human gingival fibroblast (HGF). Methods: 3 cement pellet samples were made for each 4-test cement (n=12). The cement used for this study were zinc phosphate (ZP), zinc oxide non-eugenol (ZOE), RelyX U200 (RU200), and glass ionomer cement (GIC). The cytotoxicity of peri-implant tissues was investigated using one commercial cell line. All processing was done following International Organization for Standardization (ISO) methods 10993-5 and 10993-12 (MTT assay Test). Cell cultures without dental cement were considered as control. Standard laboratory procedures were followed to permit cell growth and confluence over 48 hrs after sub-cultivation. Before being subjected to analysis, the cells were kept in direct contact with the cement samples for the suggested time period. To validate the results the specimens were tested three times each. Cell death and inhibition of cell growth were measured quantitatively. Results were analyzed using 1-way ANOVA (a=0.05) followed by Tukey B post hoc test. Results: The study showed the dental cement test material was cytotoxic. ZOE, ZP, GIC, and RU200 were cytotoxic in decreasing order, respectively, significantly reducing cell viability after exposure to HGF (p <0.001). Conclusions: Within the limitations of this in-vitro cellular study, results indicated that HGF were vulnerable to the test the dental cement. The highest cytotoxicity was observed in ZOE, followed by ZP, GIC, and RU200.

Sol-Gel Technologies to Obtain Advanced Bioceramics for Dental Therapeutics

The aim of this work is to review the application of bioceramic materials in the context of current regenerative dentistry therapies, focusing on the latest advances in the synthesis of advanced materials using the sol-gel methodology. Chemical synthesis, processing and therapeutic possibilities are discussed in a structured way, according to the three main types of ceramic materials used in regenerative dentistry: bioactive glasses and glass ceramics, calcium phosphates and calcium silicates. The morphology and chemical composition of these bioceramics play a crucial role in their biological properties and effectiveness in dental therapeutics. The goal is to understand their chemical, surface, mechanical and biological properties better and develop strategies to control their pore structure, shape, size and compositions. Over the past decades, bioceramic materials have provided excellent results in a wide variety of clinical applications related to hard tissue repair and regeneration. Characteristics, such as their similarity to the chemical composition of the mineral phase of bones and teeth, as well as the possibilities offered by the advances in nanotechnology, are driving the development of new biomimetic materials that are required in regenerative dentistry. The sol-gel technique is a method for producing synthetic bioceramics with high purity and homogeneity at the molecular scale and to control the surfaces, interfaces and porosity at the nanometric scale. The intrinsic nanoporosity of materials produced by the sol-gel technique correlates with the high specific surface area, reactivity and bioactivity of advanced bioceramics.

A Comparative Evaluation of Postoperative Sensitivity Between Cention-N and Resin-Modified Glass Ionomer Cement in Class V Cavity: An In Vivo Study

Aim This research aimed to assess and compare the postoperative sensitivity in class V cavity when restored with Cention-N and resin-modified glass ionomer cement (RMGIC). This study used the Schiff scale to assess sensitivity in the class V cavity. Materials and methods This was an in vivo study performed in the Department of Conservative Dentistry and Endodontics, Sharad Pawar Dental College and Hospital, Sawangi Meghe, Maharashtra. Patients included in this study were randomly selected from regular outpatient departments diagnosed with class V cavities and referred for restorative treatment. These patients were segregated into Group A and Group B. Demographic information, detailed history of any medical condition, dental history, any allergy related to resins, and another group of drugs were recorded. The in vivo study involved 36 patients, 18 in each group, who presented at Sharad Pawar Dental College and Hospital. Inform consent was taken from all patients. The subjects' responses were evaluated using a Schiff analog scale to assess postoperative sensitivity to an air blast stimulus. Results The study included all 36 patients aged between 18 and 40 years. All 36 patients were segregated into two distinct groups. Two groups of 18 patients in each group were restored with Cention-N and RMGIC in groups A and B, respectively. It was determined that RMGIC exhibits a relatively higher incidence of postoperative sensitivity than Cention-N. It was determined that the difference was statistically relevant. Conclusion Considering the limitations of this study, it can be concluded that RMGIC shows more postoperative sensitivity than other groups on the first, second, and seventh days. Thus, it is concluded that Cention-N can be a superior alternative to RMGIC.

Biological properties of lithium-containing surface pre-reacted glass fillers as direct pulp-capping cements

OBJECTIVE

Surface pre-reacted glass fillers (S-PRG) can release different types of ions and in our previous study, we modified these fillers with lithium chloride (S-PRG/Li-100 mM) to induce reparative dentin formation by activating the Wnt/β-catenin signaling pathway. Here, we assessed the biological performance of S-PRG/Li-100 mM and compared it with that of mineral trioxide aggregate (MTA) and S-PRG without additives.

METHODS

In vivo studies were conducted on male Wistar rats using Masson's trichrome staining in pulp-capped molars. The test materials were implanted subcutaneously to evaluate their capacity for vascularization and biocompatibility. The ability of the test materials to form apatite was tested by immersing them in simulated body fluid. Rhodamine-B staining was conducted to assess their sealing ability in bovine teeth, while their antibacterial activity was evaluated against Streptococcus mutans and Lactobacillus casei in terms of colony-forming units and by live/dead staining.

RESULTS

Masson's trichrome staining and tissue-implantation tests confirmed the biocompatibility of S-PRG/Li-100 mM and it was similar to that of MTA and S-PRG; inflammation regression was observed 14 days after operation in the subcutaneous tissues. S-PRG/Li-100 mM promoted the formation of apatite on its surface. Both the S-PRG groups showed higher sealing capability and bactericidal/bacteriostatic activity against oral bacterial biofilms than MTA.

SIGNIFICANCE

Lithium-containing surface pre-reacted glass cements exhibit better antibacterial and sealing capabilities than MTA, suggesting their potential as high-performance direct pulp-capping materials.

Evaluation of Fracture Toughness, Color Stability, and Sorption Solubility of a Fabricated Novel Glass Ionomer Nano Zirconia-Silica-Hydroxyapatite Hybrid Composite Material

The aim of this study was to investigate the effects of adding a nano zirconia-silica-hydroxyapatite (nanoZrO2-SiO2-HA) composite synthesized using a one-pot sol-gel technique to a conventional glass ionomer cement (GIC), which was then characterized using X-ray diffraction (XRD). Following the characterization studies, further investigations were carried out after the addition of nanoZrO2-SiO2-HA to cGIC (GIC nanoZrO2-SiO2-HA) at various percentages (~5% to 9%) to compare their fracture toughness, color stability, and sorption- solubility in relation to cGIC (Fuji IX). The XRD diffractogram indicated the presence of peaks for ZrO2, SiO2, and HA. The fracture toughness of GIC 5%nanoZrO2-SiO2-HA was statistically higher than that of other percentages of GIC nanoZrO2-SiO2-HA and cGIC. The highest values recorded were fracture toughness ( $1.35\pm 0.15\text{MPa}.{\text{m}}^{1/2}$ ), leading to an increase of ∼57%, as compared to cGIC. Overall, the color change ( $\Delta E$ ) values for GIC 5% nano Zr-Si-HA group were lower than those of cGIC over a one-month period and were between slight and perceptible. In addition, GIC 5%nanoZrO2-SiO2-HA recorded lower sorption values ( $23.64\pm 2.3\mu \text{gm}{\text{m}}^{-3}$ ) as compared to cGIC ( $36.28\pm 2.6\mu \text{gm}{\text{m}}^{-3}$ ) and higher solubility ( $66.46\pm 2.4\mu \text{gm}{\text{m}}^{-3}$ ) as compared to cGIC ( $56.76\pm 1.6\mu \text{gm}{\text{m}}^{-3}$ ). The addition of nanoZrO2-SiO2-HA to cGIC significantly enhanced its physicomechanical properties. Based on the results of our study, GIC nanoZrO2-SiO2-HA has the potential to be suggested as a restorative dental material with diverse applications ranging from cavity restoration, core build-up, and as a luting material.

In vitro cytotoxic evaluation of novel fast-setting calcium silicate cement compositions and dental materials using colorimetric methyl-thiazolyl-tetrazolium assay

A novel fast-setting calcium silicate cement with fluoride (CSC) has been developed for potential application in tooth crowns. This study compared the cytotoxicity of CSC compositions and a variety of dental materials. We tested CSC compositions (Protooth), MTA, Biodentine, Ketac Molar, Fuji II LC, Vitrebond, DeTrey Zinc, Dycal, and IRM, DMEM (negative control) and 1% NaOCl (positive control). After setting of cements for 24 h, specimens were immersed in DMEM for 24 h to obtain material elutes. The elutes were serially diluted in serum-free DMEM to obtain three dilutions. L929 mouse fibroblast cells (1 × 10⁴ cells per well) were treated for 24 h with elute dilutions (n = 3). Cytotoxicity was determined using methyl-thiazolyl-tetrazolium assay in triplicate. CSC compositions, MTA, and Biodentine showed no significant reduction in cell viability compared to DMEM. There was no significant difference in cell viability, at any of three dilutions, between CSC compositions and either MTA or Biodentine. Cytotoxicity was significantly lower for CSC compositions than for Vitrebond, DeTrey Zinc, Dycal, IRM, and 1% NaOCl, at all three dilutions, and undiluted Fuji II LC elute. In contrast to resin-modified glass ionomers, zinc phosphate cements, Dycal, and IRM, the CSC compositions showed no cytotoxic potential.

Cytotoxic and biological effects of bulk fill composites on rat cortical neuron cells

The aim of this study was to investigate potential cellular responses and biological effects of new generation dental composites on cortical neuron cells in two different exposure times. The study group included five different bulk-fill flow able composites; Surefil SDR Flow, X-tra Base Flow, Venus Bulk Flow, Filtek Bulk Flow and Tetric-Evo Flow. They were filled in Teflon molds (Height: 4 mm, Width: 6 mm) and irradiated for 20 s. Cortical neuron cells were inoculated into 24-well plates. After 80% of the wells were coated, the 3 µm membrane was inserted and dental filling materials were added. The experiment was continued for 24 and 72 h. Cell viability measured by MTT assay test, total antioxidant and total oxidant status were examined using real assay diagnostic kits. The patterns of cell death (apoptosis) were analyzed using annexin V-FITC staining with flow cytometry. Β-defensins were quantitatively assessed by RT-PCR. IL-6, IL-8 and IL-10 cytokines were measured from the supernatants. All composites significantly affected analyses parameters during the exposure durations. Our data provide evidence that all dental materials tested are cytotoxic in acute phase and these effects are induced cellular death after different exposure periods. Significant cytotoxicity was detected in TE, XB, SS, FBF and VBF groups at 24 and 72 h, respectively.

Long-term treatment outcomes in immature permanent teeth by revascularisation using MTA and GIC as canal-sealing materials: a retrospective study

BACKGROUND

Pulp revascularisation with MTA sealing has been accepted as an alternative treatment for non-vital immature permanent teeth. Successful revascularisation cases with GIC sealing were also reported, but lack of long-term researches.

AIM

To evaluate long-term outcomes of revascularisation using MTA and GIC as canal-sealing materials in non-vital immature permanent teeth.

DESIGN

Clinical and radiographic data of 60 non-vital immature permanent teeth treated with revascularisation (36.8 ± 12.4 months of follow-up) were reviewed. Of these, 28 teeth were sealed with MTA, and 32 with GIC. Tooth survival, success rate, and increases in root length and dentine wall thickness were evaluated.

RESULTS

Teeth in MTA group showed a similar survival rate (96%) to GIC group (100%). The success rate in MTA group (93%) was greater than that in GIC group (59%). Eight of fourteen failed teeth due to recurrent apical disease (seven teeth in GIC group and one in MTA group) achieved complete root development. There was no statistically significant difference in root length or dentine wall thickness increase between the groups.

CONCLUSIONS

Long-term outcome of revascularisation in non-vital immature permanent teeth sealed with GIC was not as good as that with MTA. Although more recurrent apical disease developed, results on root development were acceptable in GIC sealed cases.

The effect of restorative materials on cytokines in gingival crevicular fluid

OBJECTIVE

Composition of the restorative materials may cause inflammatory responses by monocyte activation and changes in the levels of cytokine released from different cells. Interleukin-6 (IL-6), interleukin-8 (IL-8) and Tumor necrosis factor alpha (TNF-α) are important cytokine for evaluating of the inflammatory process. The aim of this study was to evaluate the different restorative materials used in class V cavities effect on gingival crevicular fluid inflammatory cytokine levels.

DESIGN

60 individuals having Class V carious cavities participated in the study. Cavities were restored with FiltekZ250, DyractXP, Fuji IX, Cavex avalloy restorative materials. Changes in clinical and biochemical parameters were evaluated before restorations, seven and 21days after restorations. Contralateral tooth intact enamel surface was determined as control side. Periotron8000 device was used for detection of GCF volume. Cytokine level of GCF was evaluated by Human ELISA kits. Data were analyzed using Mann-Whitney U test and Wilcoxon signed ranks test. The correlations between clinical parameters and biochemical parameters were examined by Spearman's rank correlation analysis.

RESULTS

After restorative treatments PI and GI scores were decreased compared with baseline evaluations. There was a significant difference in GCF levels between experimental and control sites in all groups. GCF IL-6 levels in all groups except Filtek Z250, GCF IL-8 levels in all groups except Fuji IX, GCF TNF-α level in only Fuji IX showed significant differences between experimental and control sites.

CONCLUSIONS

The obtained data supported that all of the tested materials caused changes in GCF cytokine levels.

Influence of Porous Spherical-Shaped Hydroxyapatite on Mechanical Strength and Bioactive Function of Conventional Glass Ionomer Cement

Glass-ionomer-cement (GIC) is helpful in Minimal Intervention Dentistry because it releases fluoride ions and is highly biocompatible. The aim of this study is to investigate the mechanisms by which hydroxyapatite (HAp) improves the mechanical strength and bioactive functioning of GIC when these materials are combined to make apatite ionomer cement (AIC). A conventional GIC powder was mixed with porous, spherical-HAp particles (HApS), crystalline HAp (HAp200) or one of two types of cellulose. The micro-compressive strengths of the additive particles were measured, and various specimens were evaluated with regard to their compressive strengths (CS), fluoride release concentrations (fluoride electrode) and multi-element release concentrations. The AIC was found to release higher concentrations of fluoride (1.2 times) and strontium ions (1.5 times) compared to the control GIC. It was detected the more release of calcium originated from HApS than HAp200 in AIC. The CS of the AIC incorporating an optimum level of HAp was also significantly higher than that of the GIC. These results suggest that adding HAp can increase the release concentration of ions required for remineralization while maintaining the CS of the GIC. This effect does not result from a physical phenomenon, but rather from chemical reactions between the HAp and polyacrylic acid of GIC.

The role of poly(acrylic acid) in conventional glass polyalkenoate cements

Glass polyalkenoate cements (GPCs) have been used in dentistry for over 40 years. These novel bioactive materials are the result of a reaction between a finely ground glass (base) and a polymer (acid), usually poly(acrylic acid) (PAA), in the presence of water. This article reviews the types of PAA used as reagents (including how they vary by molar mass, molecular weight, concentration, polydispersity and content) and the way that they control the properties of the conventional GPCs (CGPCs) formulated from them. The article also considers the effect of PAA on the clinical performance of CGPCs, including biocompatibility, rheological and mechanical properties, adhesion, ion release, acid erosion and clinical durability. The review has critically evaluated the literature and clarified the role that the polyacid component of CGPCs plays in setting and maturation. This review will lead to an improved understanding of the chemistry and properties of the PAA phase which will lead to further innovation in the glass-based cements field.

Modification of resin modified glass ionomer cement by addition of bioactive glass nanoparticles

In the present study, sol-gel derived nanoparticle calcium silicate bioactive glass was added to the resin-modified light cure glass-ionomer cement to assess the influence of additional bioactive glass nanoparticles on the mechanical and biological properties of resin-modified glass-ionomer cement. The fabricated bioactive glass nanoparticles added resin-modified glass-ionomer cements (GICs) were immersed in the phosphate buffer solution for 28 days to mimic real condition for the mechanical properties. Resin-modified GICs containing 3, 5 and 10 % bioactive glass nanoparticles improved the flexural strength compared to the resin-modified glass-ionomer cement and the samples containing 15 and 20 % bioactive glass nanoparticles before and after immersing in the phosphate buffer solution. Characterization of the samples successfully expressed the cause of the critical condition for mechanical properties. Cell study clarified that resin-modified glass-ionomer cement with high concentrations of bioactive glass nanoparticles has higher cell viability and better cell morphology compare to control groups. The results for mechanical properties and toxicity approved that the considering in selection of an optimum condition would have been a more satisfying conclusion for this study.

Pulp response to high fluoride releasing glass ionomer, silver diamine fluoride, and calcium hydroxide used for indirect pulp treatment: An in-vivo comparative study

Aims and Objectives:

The study aims at determining pulp response of two high fluoride releasing materials silver diamine fluoride (SDF) and Type VII glass ionomer cement (GIC) when used as indirect pulp treatment (IPT) materials.

Materials and Methods:

Deep Class V cavities were made on four first premolars indicated for extraction for orthodontic reasons. SDF, Type VII GIC, and calcium hydroxide base are given in three premolars, and one is kept control. Premolars were extracted 6 weeks after the procedure and subjected to histopathological examination to determine the pulp response. The results were analyzed using Chi-square test.

Results:

No inflammatory changes were observed in any of the groups. Significantly more number of specimens in SDF and Type VII GIC groups showed tertiary dentin deposition (TDD) when compared to control group. No significant difference was seen in TDD when intergroup comparison was made. Odontoblasts were seen as short cuboidal cells with dense basophilic nucleus in SDF and Type VII GIC group.

Conclusion:

The study demonstrated TDD inducing ability of SDF and Type VII GIC and also established the biocompatibility when used as IPT materials.

Clinical and radiographic assessment of the efficacy of calcium silicate indirect pulp capping: a randomized controlled clinical trial

The aims of this study were to assess the effectiveness of calcium silicate cement (Biodentine) versus glass ionomer cement (GIC; control group) as indirect pulp capping materials in patients with reversible pulpitis and to compare the effectiveness of cone beam computed tomography (CBCT) versus periapical (PA) radiographs in detecting PA changes at baseline (T0) and at 12 mo (T12) postoperatively. Seventy-two restorations (36 Biodentine, 36 Fuji IX) were placed randomly in 53 patients. CBCT/PA radiographs were taken at T0 and T12. Two calibrated examiners assessed the presence/absence and increase/decrease in the size of existing PA radiolucencies under standardized conditions. The Kappa coefficient evaluated statistically the effectiveness of CBCT versus PA radiographs in detecting PA changes. Chi-square/Mann-Whitney tests were used to evaluate the association between PA changes in CBCT with various clinical measures. Significance was predetermined at α = 0.05. Clinical success rates for Biodentine and Fuji IX GIC were 83.3%. CBCT was significantly more effective in detecting PA radiolucencies compared with radiographs (P = 0.0069). Of the teeth, 65.4% and 90.4% were deemed healthy using CBCT and PA radiographs, respectively, at T12. Healing/healed rates were 17.3%/0%, while new/progressed radiolucency were 30.8%/9.6% with CBCT/PA radiographs, respectively. Seventy-one percent of healed lesions had received Biodentine; 88% of new/progressed lesions received Fuji IX GIC. Teeth presenting with an initial CBCT PA lesion had a failure rate of 63%, whereas teeth with no initial lesion had a failure rate of 16%. Although no statistically significant difference was detected in the clinical efficacy of Biodentine/Fuji IX when used as indirect pulp capping materials in patients with reversible pulpitis, CBCT showed a significant difference in that most healed CBCT lesions had received Biodentine while most that did not heal received Fuji IX. Longer-term follow-up is needed to establish their effect on the healing dynamics of PA tissues (ClinicalTrials.gov NCT02201641).

Changes in cell density and morphology of selected cells of the ageing human dental pulp

OBJECTIVES

The aim of this study was to determine the changes in cell density and morphology of selected cells of the ageing human dental pulp.

BACKGROUND

Changes in cell density and morphology of dental pulp cells over time may affect their capability to respond to tooth injury.

MATERIALS AND METHODS

One hundred thirty-one extracted teeth were obtained from individuals between the ages of 6 and 80 years. The apical 1/3 of the root region was removed from all teeth prior to routine processing for producing histological slides. The histology slides were used to study the changes in cell density and morphology of selected pulp cells; odontoblasts, subodontoblasts and fibroblasts in the crown and root regions of the dental pulp. Student's t-test and one-way anova were used for statistical analyses.

RESULTS

In all age groups, the cell density for all types of cells was found to be higher in the crown than in the root (p < 0.05). In general, the pulp cell density was found to decrease with age in both the crown and root regions. However, it was noted that the reduction of coronal odontoblasts occurred later in life (40-49 years) when compared to that of subodontoblasts or fibroblasts (30-39 years).

CONCLUSIONS

The density of the coronal pulp cells reduces and these cells undergo morphological changes with ageing of individuals and this may affect the pulp's ability to resist tooth injury.

Evaluation of antibacterial and remineralizing nanocomposite and adhesive in rat tooth cavity model

Antibacterial and remineralizing dental composites and adhesives were recently developed to inhibit biofilm acids and combat secondary caries. It is not clear what effect these materials will have on dental pulps in vivo. The objectives of this study were to investigate the antibacterial and remineralizing restorations in a rat tooth cavity model, and determine pulpal inflammatory response and tertiary dentin formation. Nanoparticles of amorphous calcium phosphate (NACP) and antibacterial dimethylaminododecyl methacrylate (DMADDM) were synthesized and incorporated into a composite and an adhesive. Occlusal cavities were prepared in the first molars of rats and restored with four types of restoration: control composite and adhesive; control plus DMADDM; control plus NACP; and control plus both DMADDM and NACP. At 8 or 30days, rat molars were harvested for histological analysis. For inflammatory cell response, regardless of time periods, the NACP group and the DMADDM+NACP group showed lower scores (better biocompatibility) than the control group (p=0.014 for 8days, p=0.018 for 30days). For tissue disorganization, NACP and DMADDM+NACP had better scores than the control (p=0.027) at 30days. At 8days, restorations containing NACP had a tertiary dentin thickness (TDT) that was five- to six-fold that of the control. At 30days, restorations containing NACP had a TDT that was four- to six-fold that of the control. In conclusion, novel antibacterial and remineralizing restorations were tested in rat teeth in vivo for the first time. Composite and adhesive containing NACP and DMADDM exhibited milder pulpal inflammation and much greater tertiary dentin formation than the control adhesive and composite. Therefore, the novel composite and adhesive containing NACP and DMADDM are promising as a new therapeutic restorative system to not only combat oral pathogens and biofilm acids as shown previously, but also facilitate the healing of the dentin-pulp complex.

Discrimination between intact and decayed pulp regions in carious teeth by ADC mapping

The aim of this study was to evaluate an advanced magnetic resonance imaging (MRI) method, apparent diffusion coefficient (ADC) mapping, in the functional assessment of carious teeth. 38 extracted human teeth with scores of 0, 3 and 6 according to International Caries Detection and Assessment System (ICDAS) criteria were screened and subsequently analyzed by MRI at 2.35 T. Histology sectioning of teeth was used for the gold standard by analyzing two extreme cases (intact and severely decayed). ADC maps of the same teeth were calculated from corresponding diffusion-weighted images and used to obtain ADC distributions along dental pulp as functions of the relative pulp length measured from the occlusal pulp side. The measured distributions were analyzed for the best fit by a four-parameter three-segment linear regression model for ADC distribution along the pulp. MRI results were in good agreement with findings in histological sections of identical teeth. The best fit model parameters, relative decayed region depth, relative transition region width and ADC values of intact and decayed pulp tissue, showed statistically significant differences between the ADC values of intact and decayed pulp tissue (1.0 × 10(-9) m(2)/s vs. 0.74-0.89 × 10(-9) m(2)/s) and the relative decayed region depth progressing with ICDAS score (3 vs. 46% with ICDAS 3 vs. ICDAS 6). The results of this feasibility study confirmed relevance of ADC mapping for the discrimination and localization of intact and decayed regions in dental pulps of carious teeth.

The bacterial adhesion on and the cytotoxicity of various dental cements used for implant-supported fixed restorations

OBJECTIVE

Bacterial adhesion on and cytotoxicity of eight luting agents used for implant-supported restorations were investigated.

MATERIALS AND METHOD

Surface roughness (Ra), surface free energy (SFE) values and three-dimensional images by atomic-force microscopy of circular specimens were determined. Bacterial suspensions of Streptococcus sanguinis and Streptococcus epidermidis were incubated at 37°C for 2 h. Adhering bacteria were examined with fluorescence dye CytoX-Violet, stained with 4',6-diamidino-2-phenylindole (DAPI) and visualized by fluorescence-microscopy. Cytotoxicity-testing was done with WST-1-tests (water soluble tetrazolium). No significant differences, neither with regard to Ra nor regarding SFE were determined.

RESULTS

Adherence of S. sanguinis was less on titanium, TempBondNE and TempBond. TempBond, TempBondNE, RelyX Unicem and Implantlink Semi Classic presented low amounts of S. epidermidis. WST-testing showed high cytotoxic potential of Harvard, Aqualox, TempBondNE and TempBond. No combination of low adherent bacteria with low cytotoxicity was found.

CONCLUSION

From a biological in-vitro perspective, none of the cements may be recommended for implant-supported restorations.

Cytotoxicity evaluation of a new fast set highly viscous conventional glass ionomer cement with L929 fibroblast cell line

Aim:

This study aims to evaluate the cytotoxicity of a new fast set highly viscous conventional glass ionomer cement (GIC) with L929 fibroblasts.

Materials and Methods:

The cement capsule was mixed and introduced into a paraffin wax mould. After setting, the cement was incubated in Dulbecco's Modified Eagle's Medium. Six replicates of the material extract were added to the culture medium in 96-well plates. L929 mouse fibroblast cells were added into the wells and then incubated for 48 h. Dimethylthiazol diphenyltetrazolium bromide test was performed for cytotoxicity evaluation.

Results:

The results showed that this GIC brand did not yield a half-maximal inhibitory concentration value, IC50, as the cell viability was above 50% at all concentrations. Cell viability over 90% was observed at the concentrations of 3.125 and 1.5625 mg/ml. Maximum concentration of the material showed cell viability of 59.4%.

Conclusions:

This new fast set highly viscous conventional GIC showed low cytotoxicity to mouse fibroblast cells, and it can be suggested as a substitute for dental cements exhibiting a long setting time.

Can interaction of materials with the dentin-pulp complex contribute to dentin regeneration?

Understanding outcomes of the interaction between a dental material and tooth tissue is important in terms not only of biocompatibility but also of the potential for the material to modulate the response of the tissue. This interaction is influenced by many factors, including the chemistry of the material and any of its eluted components or degradation products, and the manner in which the tissue responds to these agents. Past studies of this interaction have primarily been aimed at identifying cytotoxic effects. More recently, investigations have focused on specific cellular responses, and in particular, on understanding how the materials themselves actually may contribute to regenerative processes in the tooth. Recent work has demonstrated the solubilization of proteins from dentin exposed to certain materials, such as calcium hydroxide, mineral trioxide aggregate, and acidic solutions that relate to those used in dentin bonding agents, with the subsequent modulation by these proteins of gene expression in odontoblast-like cells. This work suggests that dentin bridge formation under such materials may be stimulated through this process. Thus, there is much merit in examining both how new dental materials can be developed and how more traditional ones can be modified to preferentially stimulate regenerative processes when preferred. This review summarizes current knowledge about the potential beneficial effects derived from the interaction of dental materials with the dentin-pulp complex, as well as potential future developments in this exciting field.

Matricellular molecules and odontoblast progenitors as tools for dentin repair and regeneration

This review summarizes the in vivo experiments carried out by our group after implantation of bioactive molecules (matricellular molecules) into the exposed pulp of the first maxillary molar of the rat or the mandibular incisor of rats and mice. We describe the cascade of recruitment, proliferation and terminal differentiation of cells involved in the formation of reparative dentin. Cloned immortalized odontoblast progenitors were also implanted in the incisors and in vitro studies aimed at revealing the signaling pathways leading from undifferentiated progenitors to fully differentiated polarized cells. Together, these experimental approaches pave the way for controlled dentin regenerative processes and repair.

In vitro and in vivo studies on the toxicity of dental resin components: a review. Clin Oral Investig. 2008;12:1-8. [PMID: 18040729 DOI: 10.1007/s00784-007-0162-8]

In vitro and in vivo studies have clearly identified that some components of restorative composite resins, adhesives, and resin-modified glass ionomer cements are toxic. The mechanisms of cytotoxicity are related firstly to the short-term release of free monomers occurring during the monomer-polymer conversion. Secondly, long-term release of leachable substances is generated by erosion and degradation over time. In addition, ion release and proliferation of bacteria located at the interface between the restorative material and dental tissues are also implicated in the tissue response. Molecular mechanisms involve glutathione depletion and reactive oxygen species (ROS) production as key factors leading to pulp or gingival cell apoptosis. Experimental animal approaches substantiate the occurrence of allergic reactions. There is a large gap between the results published by research laboratories and clinical reports.

The ‘new” operative dentistry

During the past few decades, life expectancy has increased significantly. As a result, mature patients often have receding gingival tissues, physical and mental debilitation, less energy and motivation, and the resultant Class V carious lesions. In this article, I suggest the use of high-level fluoride in toothpastes, remineralizing pastes and high-level fluoride gels for topical application in trays to reduce the progression of caries. To accompany fluoride therapy, high-fluoride-releasing restorative materials are indicated for Class V carious lesions. Adequate caries-preventive and restorative concepts for mature patients require planning, patient education and close patient supervision.

The impact of bioactive molecules to stimulate tooth repair and regeneration as part of restorative dentistry

After implantation in the exposed pulp, some molecules of the den-tin extracellular matrix induce the formation of a reparative dentinal bridge in the coronal pulp. In some cases, total occlusion of the root canal also is observed. This is the case for bone sialoprotein, bone morphogenetic protein-7, Dentonin (a fragment from matrix extracellular phosphoglycoprotein), and two small amelogenin gene splice products (A+4 and A-4). Cells implicated in the reparative process are recruited, proliferate, and differentiate into osteoblast-like and odontoblast-like cells. The same results may be obtained by direct implantation of odontoblast progenitor cell into the pulp.

Microhardness of dentine underlying ART restorations in primary molars: an in vivo pilot study

OBJECTIVE

To evaluate the microhardness of dentine underlying glass ionomer restorations made with Atraumatic Restorative Treatment.

DESIGN

An experimental single-centre study.

SETTING

University Department, Brazil, 2001.

MATERIALS AND METHODS

Sixteen children were selected showing primary molars containing carious cavities (n = 29), which were restored using Fugi IX. Subsequently, some teeth were extracted respecting Nolla stage 7 or 8 of the permanent successor, and categorised according to the post-restoration time in the mouth: G1 (baseline, immediate extraction), G2 (30 days), G3 (90 days) and G4 (180 days). Four teeth were excluded because they were not in time of normal exfoliation. The 25 extracted teeth were resin embedded, sectioned mesiodistally and prepared metallographically. Knoop microhardness analysis (Micromet 2003; 10g for 1.5 sec.) produced identations in three areas of dentine: Zone 1 (just below the restoration), Zone 3 (as close as possible to the pulp) and Zone 2 (intermediate region between 1 and 3). Non-parametric statistical tests were done--at a significance level of 5%.

RESULTS

Four teeth were excluded. No significant difference was noted among the zones, inside the groups. Zones 1 and 2 showed a considerable increase of microhardness according to the time, except for Group 3 (p > 0.05).

CONCLUSION

Although microhardness had increased, it was not sufficiently equal to the microhardness of the healthy dentine, regardless of the depth evaluated.

Octacalcium phosphate–based cement as a pulp-capping agent in rats

OBJECTIVE

The purpose of this study was to evaluate the pulpal response to an octacalcium phosphate (OCP)-based cement used as a pulp-capping material.

STUDY DESIGN

The pulps of 60 maxillary first molars of male Sprague-Dawley rats were exposed and then capped directly by using either OCP-based cement or a calcium hydroxide slurry (control). Histologic examinations were performed at 1, 2, and 5 weeks after the surgical procedure, and the results were analyzed statistically by using the Mann-Whitney U test (P<.05).

RESULTS

One week after pulp capping, the initial formation of reparative dentin in the exposed areas was more notable in the calcium hydroxide group than in the OCP-based cement group. At 2 weeks, reparative dentin covered by a layer of odontoblast-like cells was observed in both groups. However, at 5 weeks, reparative dentin consisting of regular dentinal tubules was observed more frequently in the OCP-based cement group.

CONCLUSION

OCP-based cement allowed favorable healing processes to occur in the dental pulp.

Biocompatibility of resin-based materials used as pulp-capping agents

AIM

To evaluate and compare the response of pulps of rats capped with resin-modified glass-ionomer cement (RMGIC) or self-etching adhesive system.

METHODOLOGY

Class I cavities were prepared on the occlusal surface of 54 maxillary first molars of 27 rats. Pulp exposure was performed on the cavity floor. The following resin-based materials were applied as pulp-capping agents: G1, Clearfil Liner Bond 2V (CLB 2V; Kuraray Co., Japan); G2, Vitrebond (VIT; 3M/ESPE, USA). In group 3 (control group), a calcium hydroxide/saline paste (CH; Labsynth, Brazil) was used. The cavities were restored with amalgam. After 7, 30 and 60 days, the animals were sacrificed and the jaws were processed for microscopic evaluation.

RESULTS

Despite the inflammatory response caused by the experimental and the control materials at 7 days, pulpal healing associated with calcified barrier formation was observed at 60 days following the pulp therapy. Both resin-based materials promoted a large zone of cell-rich fibrodentine matrix deposition on the pulp horn related to the pulp exposure site, which was larger to VIT than to CLB 2V specimens. Tertiary dentine underneath the fibrodentine matrix was deposited by a layer of elongated pulpal cells. The remaining pulpal tissue exhibited normal histological characteristics. In the control group, healing and dentine-bridge formation was observed at 30 days. Pulpal breakdown occurred only when bacterial infection occurred.

CONCLUSION

Both experimental pulp-capping agents allowed pulpal healing characterized by cell-rich fibrodentine and tertiary dentine deposition as well as calcified barrier formation.

CELLS AND EXTRACELLULAR MATRICES OF DENTIN AND PULP: A BIOLOGICAL BASIS FOR REPAIR AND TISSUE ENGINEERING

Odontoblasts produce most of the extracellular matrix (ECM) components found in dentin and implicated in dentin mineralization. Major differences in the pulp ECM explain why pulp is normally a non-mineralized tissue. In vitro or in vivo, some dentin ECM molecules act as crystal nucleators and contribute to crystal growth, whereas others are mineralization inhibitors. After treatment of caries lesions of moderate progression, odontoblasts and cells from the sub-odontoblastic Höhl's layer are implicated in the formation of reactionary dentin. Healing of deeper lesions in contact with the pulp results in the formation of reparative dentin by pulp cells. The response to direct pulp-capping with materials such as calcium hydroxide is the formation of a dentinal bridge, resulting from the recruitment and proliferation of undifferentiated cells, which may be either stem cells or dedifferentiated and transdifferentiated mature cells. Once differentiated, the cells synthesize a matrix that undergoes mineralization. Animal models have been used to test the capacity of potentially bioactive molecules to promote pulp repair following their implantation into the pulp. ECM molecules induce either the formation of dentinal bridges or large areas of mineralization in the coronal pulp. They may also stimulate the total closure of the pulp in the root canal. In conclusion, some molecules found in dentin extracellular matrix may have potential in dental therapy as bioactive agents for pulp repair or tissue engineering.

In vitro cytotoxicity of five glass-ionomer cements

To evaluate the cytotoxic effects of five glass-ionomer cements (GICs) on an odontoblast cell line (MDPC-23), disks of every material were prepared and divided into Group 1: Vitrebond, Group 2: Vitremer, Group 3: Fuji II LC, Group 4: Fuji IX GP, Group 5: Ketac-Molar, Group 6: Z-100 (positive control). In Group 7, phosphate-buffered saline solution (negative control) was applied on filter paper. After placing the samples in the bottom of wells, the cells (30,000cells/cm(2)) were plated and incubated for 72h. The cell number was counted, the cell morphology was assessed by scanning electron microscopy and the cell metabolism was evaluated using methyltetrazolium assay. The statistical analysis of Kruskal-Wallis was used to determine if the scores obtained for the cell metabolism and number of cells were different at the 95% confidence level. In groups 1, 2, 3, 4, 5, and 6 the materials decreased the cell number by 74.5%, 75.5%, 45.5%, 29.5%, 32.5%, and 88.5%, respectively. In groups 1, 2, 3, 4, and 5, the experimental GICs reduced the cell metabolism by 79%, 84%, 54%, 40%, and 42.5%, respectively. Despite the fact that all experimental materials were cytotoxic to the MDPC-23 cells, the GICs were the least cytotoxic. On the other hand, the RMGICs caused the highest cytophatic effects.

Toughness, bonding and fluoride-release properties of hydroxyapatite-added glass ionomer cement

Improving the mechanical strength of glass ionomer cement while preserving its favorable clinical properties such as fluoride release, bonding to tooth structure and biocompatibility is desirable. In this study, hydroxyapatite was incorporated into chemically setting glass ionomer cement and its effect on the fracture toughness, bonding to dentin and fluoride release was identified. Commercial glass ionomer cement (Fuji IX GP((R)) ) was the control and base material. Eight weight percent of hydroxyapatite was added into the glass ionomer powder. Specimens were fabricated and the fracture toughness, shear bond strength and eluted fluoride ion concentration were measured. Adding hydroxyapatite into the glass ionomer cement led to significantly higher fracture toughness after 15min and 24h from mixing. The hydroxyapatite-added cement also exhibited bond strength to dentin similar to that of the control from 15min to 56 days and consistent fluoride release for 13 weeks. SEM findings showed a cohesive type of fracture in the material for all specimens in both groups. These results indicate that hydroxyapatite-added glass ionomer cement has a potential as a reliable restorative material with improved fracture toughness, long-term bonding to dentin and unimpeded ability of sustained fluoride release.

[Mineralization of the dental pulp: contributions of tissue engineering to tomorrow's therapeutics in odontology]

When bioactive molecules such as bone sialoprotein (BSP), bone morphogenetic protein-7 (BMP-7, also termed OP-1) and chondrogenic Inducing Agents (CIA, A+4 and A-4) were implanted in the pulp of the first upper molars, mineralizations were induced. They were either limited to the formation of a reparative dentinal bridge closing the pulpal wound (CIA A+4), or filled the mesial part of the coronal pulp (BSP), or filled totally the pulp located in the root canal (BMP-7 and CIA A-4). Consequently, these molecules may change in the next future the every day practice in dentistry.

Differential repair responses in the coronal and radicular areas of the exposed rat molar pulp induced by recombinant human bone morphogenetic protein 7 (osteogenic protein 1)

Bone morphogenetic protein 7 (BMP 7), also termed osteogenic protein 1, a member of the transforming growth-factor superfamily, was examined for its efficacy in inducing reparative dentinogenesis in the exposed pulps of rat molars. To determine if the reaction was dose-dependent, collagen pellets containing 1, 3 or 10 microgram of recombinant BMP 7 were inserted in intentionally perforated pulps (10-12 pulps per group) in the deepest part of half-moon class V-like cavities cut in the mesial aspect of upper first molars. As controls, the collagen carrier (CC group) alone and calcium hydroxide (Ca group) were used as capping agents. All cavities were then restored with a glass-ionomer cement. Half of the animals were killed after 8 days and the other half after 28 days, by intracardiac perfusion of fixative. The molars were processed for histological evaluation by light microscopy. No difference in effect could be detected between the three concentrations of BMP 7 groups at either time interval. After 8 days, all groups showed varying inflammation, from mild of severe, and the Ca group demonstrated early formation of a reparative dentine bridge. At 28 days the CC group displayed irregular osteodentine formation, leaving some unmineralized areas at the exposure site and interglobular unmineralized areas containing pulp remnants. In the Ca-treated pulps, the initial formation of thick reparative osteodentine bridges that sealed more or less completely the pulp perforation was followed, in the deeper part, by irregular tubular dentine. In most BMP 7-treated specimens, the initial inflammation has resolved at 8 days and at 28 days heterogeneous mineralization or osteodentine filled the mesial coronal pulp. They also had complete filling of the radicular pulp by homogenous mineralization in the mesial root; this reaction was found in 11 teeth in the BMP 7 group, one tooth in the CC group an none of the Ca group. These results emphasize the biological differences the coronal and radicular parts of the pulp, and the potential of bioactive molecules such as BMP 7 to provide an a alternative conventional endodontic treatments.

Application of bioactive molecules in pulp-capping situations

To evaluate the effects of bioactive molecules in pulpal wound healing, we carried out experiments using the rat upper molars as an in vivo model. Cavities were prepared on the mesial aspect, and pulp perforation was accomplished by the application of pressure with the tip of a steel probe. After the pulp-capping procedure, the cavities were filled with a glass-ionomer cement. Comparison was made between and among: (1) sham-operated controls with dentin and predentin fragments implanted in the pulp during perforation after 8, 14, and 28 days; (2) carrier without bioactive substance; (3) calcium hydroxide; (4) Bone Sialoprotein (BSP); (5) different concentrations of Bone Morphogenetic Protein-7 (BMP-7), also termed Osteogenic Protein-1 (OP-1); and (6) N-Acetyl Cysteine (NAC), an anti-oxidant agent preventing glutathione depletion. Histologic and morphometric comparison, carried out among the first 4 groups on demineralized tissue sections, indicated that, at 28 days after implantation, BSP was the most efficient bioactive molecule, inducing homogeneous and well-mineralized reparative dentin. BMP-7 gave reparative dentin of the osteodentin type in the coronal part of the pulp, and generated the formation of a homogeneous mineralized structure in the root canal. These findings indicate that the crown and radicular parts of the pulp bear their own specificity. Both BSP and BMP-7 were superior to calcium hydroxide in their mineralization-inducing properties, and displayed larger areas of mineralization containing fewer pulp tissue inclusions. The overall mineralization process to these molecules appeared to proceed by mechanisms that involved the recruitment of cells which differentiate into osteoblast-like cells, producing a mineralizing extracellular matrix. We also provide preliminary evidence that NAC induces reparative dentin formation in the rat molar model. Pulp-capping with bioactive molecules provides new prospects for dental therapy.