Flexural Strength, Elastic Modulus and Remineralizing Abilities of Bioactive Resin-Based Dental Sealants

The demineralization resistance and mechanical assessments of different bioactive restorative materials for primary and permanent teeth: an in vitro study

OBJECTIVES

This article examines the efficacy of two bioactive dental composites in preventing demineralization while preserving their mechanical and physical properties.

MATERIALS AND METHODS

The study compares Beautifil Kids and Predicta® Bioactive Bulk-Fill (Predicta) composites with conventional dental composite. Flexural strength and elastic modulus were evaluated using a universal testing machine. A pH-cycling model assessed the composites' ability to prevent dentin demineralization. Color stability and surface roughness were measured using a spectrophotometer and non-contact profilometer, respectively, before and after pH-cycling, brushing simulation, and thermocycling aging.

RESULTS

Beautifil Kids exhibited the highest flexural strength and elastic modulus among the materials (p < 0.05). Predicta demonstrated the highest increase in dentin surface microhardness following the pH-cycling model (p < 0.05). All groups showed clinically significant color changes after pH-cycling, with no significant differences between them (p > 0.05). Predicta exhibited greater color change after brushing and increased surface roughness after thermocycling aging (p < 0.05). While Beautifil Kids had higher surface roughness after pH-cycling (p < 0.05).

DISCUSSION/CONCLUSION

Bioactive restorative materials with ion-releasing properties demonstrate excellent resistance to demineralization while maintaining mechanical and physical properties comparable to the control group.

Evaluation of flexural strength, degree of conversion, and demineralization-prevention properties in adjacent tooth structures of an experimental fissure sealant containing nano-calcium-phosphate compounds

BACKGROUND

The present study aimed to evaluate the flexural strength, degree of conversion, and demineralization-prevention ability of an experimental fissure sealant containing nano-calcium-phosphate compounds.

METHODS

An experimental sealant was formulated using silica and nano hydroxyapatite filler particles. The control group consisted of the DENU Seal (n = 10, each group). The flexural bond strength was evaluated by UTM. DC was evaluated by FTIR. To evaluate the demineralization-prevention ability, Cl V cavities in 10 third molar teeth restored with two sealant products, followed by an acid challenge then the Vickers microhardness test was carried out.

RESULTS

The mean flexural strength in the commercial group was higher than the experimental group. However, the mean flexural modulus was not significantly different between the two groups. In the experimental group, DC was significantly higher than the commercial group. Adjacent to the interface, the decrease in microhardness in the experimental group was significantly less than the commercial group. However, on the tooth surface, there were no significant differences between the two groups. In the experimental group, the decrease in microhardness at the interface was less than at the tooth surface, however the situation was opposite in the commercial group.

CONCLUSIONS

Incorporating hydroxyapatite into the sealant structure might prevent demineralization, without adverse effects on flexural modulus and degree of conversion.

The Effect of Salbutamol and Budesonide Pediatric Doses on Dental Enamel and Packable and Flowable Composites: Microhardness, Surface Roughness and Color

OBJECTIVE

To assess and compare the effects of two pediatric anti-asthmatic medication doses on the microhardness of enamel and microhardness, surface roughness and color of restorative materials.

METHODS

Human enamel samples and packable and flowable composite restorations were used. The samples were exposed to Salbutamol (0.6 mL/6 mL saline) and Budesonide (2 mL/2 mL saline) via a custom-made chamber connected to a nebulizer. Medication administration was conducted for 10 days. The samples were brushed with an electronic brush in a continuous and circular mode for 10 s after 10 min of medication administration. Assessments of microhardness, surface roughness and color were carried out at three different time intervals: baseline (T0), 5 days (T1) and 10 days (T2). One-way analysis of variance (ANOVA), a two-sample t-test and a Bonferroni multiple comparison test were used to analyze the data and compare between the groups.

RESULTS

Both medications significantly (p < 0.05) decreased the microhardness of the enamel and composite samples after 10 days. Both medications lowered the surface roughness of both types of composite with a greater effect observed after 10 days of Budesonide administration (p < 0.05). Both medications had comparable detectable color change on both types of composite with a greater effect observed after 10 days of Budesonide administration (p < 0.05).

CONCLUSION

Salbutamol and Budesonide significantly decreased microhardness in the enamel samples. Both medications affected the properties of packable and flowable composites. The packable composite showed more resistance to microhardness changes. Both medications showed a clinically detectable change in the color of packable and flowable composites.

Comparison between Different Bulk-Fill and Incremental Composite Materials Used for Class II Restorations in Primary and Permanent Teeth: In Vitro Assessments

INTRODUCTION

Several advantages, including improved aesthetics and conservative cavity preparation, made resin-based composite (RBC) a popular restorative material. However, several limitations come with RBC restorations such as the necessity for proper isolation of the tooth and an incremental layering for the material due to the limitations of the depth of cure. Despite these advantages and limitations, the usage of these restorative materials is increasingly being expanded due to the advancement made since their introduction. To overcome some of the limitations, several types of RBC restorations were developed.

MATERIALS AND METHODS

Four different RBC materials used for class II restorations in primary and permanent teeth were compared: Z350 XT Filtek™ Universal Restorative (ZXT), Filtek™ Bulk Fill Flowable Restorative (FBF), Beautifil-Bulk Flowable (BBF) and Tetric™ N-Flow (TNF). Flexure strength, elastic modulus, surface roughness, microhardness and microleakage were assessed using standard methods or previously published protocols. The data and differences between the groups were analyzed using One-way analysis of variance (ANOVA), Tukey's multiple comparisons, Kruskal-Wallis and Wilcoxon rank-sum (Mann-Whitney) tests.

RESULTS

The study found that BBF (86.24 ± 7.41 MPa) and ZXT (64.45 ± 11.52 MPa) had higher flexural strength than FBF (50.89 ± 8.44 MPa) and TNF (50.67 ± 9.40 MPa), while both exhibited the highest values of surface roughness. Elastic modulus was the highest with BBF, which was not statistically significant from FBF or ZXT (p > 0.05). ZXT (109.7 ± 7.83 VH) exhibited the highest value of microhardness, which was statistically significant from the other three materials (p < 0.0001). Microleakage was assessed after thermocycling for 20,000 cycles to simulate two years in the mouth. FBF (70%) exhibited the most resistance to microleakage.

CONCLUSIONS

Different types of RBC restorations exhibit different characteristics. The clinician needs to choose the most appropriate restorative material based on different clinical scenarios.

The stress distribution of different types of restorative materials in primary molar

The aim of this finite element analysis study is to evaluate the stress distributions of different types of restorative materials at Class I cavity in the primary molar. The non-cracked caries-free primary mandibular second molar that is extracted for orthodontic reasons is used to create a three-dimensional model. Two models were prepared as Model 1: the tooth model without restoration (control group) and Model 2: the tooth model with Class I restoration. Five different types of restorative materials were tested in Model 2 (resin modified glass ionomer [Fuji II LC], compomer [Dyract AP], giomer [Beautiful II], glass carbomer [GPC Glass Fill] and ionic resin material with bioactive properties [Activa Kids Bioactive]). A force of 197 N was applied in the vertical and oblique directions in the ANSYS program (Ansys Workbench 19.0, Canonsburg, PA). The maximum Von Mises stress values were compared in the models. The vertical or oblique loading created different stresses in enamel, dentin and restorative materials. The stresses in the enamel tissue were higher than that in the dentin tissue. The stresses in vertical loading were higher than in the oblique loading for restorative materials. The different restorative materials exhibited similar stress distribution patterns, except Activa Kids Bioactive (vertical and oblique loading 446.16 and 8.57, respectively).

Microtensile Bond Strength of Bioactive Pit and Fissure Sealants Bonded to Primary and Permanent Teeth

Background: Sealing occlusal pits and fissures is an effective preventive measure against dental caries. Pit and fissure sealants (PFS) should be strongly bonded to the teeth to prevent partial or complete loss of the sealant, which may limit its preventive effect. Objective: The objective of the study was to compare the microtensile bond strength (μTBS) of bioactive resin-based sealants (Bio-RBS) and resin-based sealants (RBS), with and without the use of a bonding agent, to the enamel of primary and permanent teeth. Methods: One hundred and twenty caries-free primary molar specimens and 120 permanent molar specimens were divided to eight groups (30 specimens per group), both primary and permanent teeth were sealed with a Bio-RBS BioCoat^TM (Premier^®, Plymouth Meeting, PA, USA) or with a RBS Clinpro^TM (3M ESPE, Saint Paul, MN, USA), with or without the use of a bonding agent (Prime & Bond NT; Dentsply, Inc., Charlotte, NC, USA). Half the specimens were aged with 5000 thermal cycles, and all specimens were tested for the μTBS and failure mode. Results: The mean μTBS of aged Bio-RBS was higher in permanent teeth than primary teeth, and the aging process reduced the μTBS of RBS more than that of Bio-RBS. Moreover, the addition of a bonding agent improved the μTBS of aged RBS in permanent teeth. Conclusion: We concluded that Bio-RBS exhibit superior μTBS than RBS when applied to permanent teeth.