Effects of a 445 nm diode laser and silver diamine fluoride in preventing enamel demineralisation and inhibiting cariogenic bacteria

Advanced Lasers and Their Applications in Dentistry

The development of laser technology has revolutionized dentistry, offering complementary and alternative approaches to traditional techniques. Lasers have been successfully integrated into various dental procedures, enhancing treatment outcomes and patient care. Several types of lasers can increase the acid resistance of enamel, thus preventing caries. Laser fluorescence has been utilized for the pre-operative diagnosis of dental caries, enabling early detection and effective treatment planning. The therapeutic application of lasers in caries treatment aligns with the contemporary philosophy of minimally invasive procedures. Clinicians can use laser Doppler flowmetry as a supplementary tool for pulp vitality testing by detecting pulpal blood flow. Lasers are also employed in various pulp-related interventions, such as managing dentine hypersensitivity and performing root canal therapy. These procedures benefit from the precision and reduced invasiveness provided by laser technology. Furthermore, laser fluorescence serves as an additional tool for subgingival calculus detection. High-power and low-power lasers are used in both nonsurgical and surgical therapies to treat periodontal and peri-implant diseases, oral mucosa conditions, and even cancer based on their specific properties. Lasers are also utilized to accelerate bone regeneration, promote adhesive strength, and remove ceramic brackets. In summary, laser technology has significantly impacted contemporary dentistry by facilitating early diagnosis, minimally invasive treatments, and precise operative procedures, ultimately improving patient outcomes and expanding the scope of dental practice.

Remineralising enamel caries with a novel peptide: An in vitro study

OBJECTIVE

To evaluate the antibacterial and remineralising effects of GAPI peptide on artificial enamel caries.

METHODS

Human enamel blocks were exposed to Streptococcus mutans biofilm to create artificial carious lesions. The blocks were randomly assigned to either the GAPI treatment group or the deionised water control group, treated twice daily for 21 days. The viability, growth kinetics, and morphology of S. mutans biofilms were assessed using confocal laser scanning microscopy (CLSM), colony-forming unit (CFU) counting, and scanning electron microscopy (SEM). Lesion depth, mineral loss, calcium-to-phosphorus ratio, Knoop hardness, enamel surface morphology, and crystal characteristics of enamel lesions were determined using micro-computed tomography (Micro-CT), SEM-energy dispersive spectroscopy (EDS), a microhardness tester, SEM, and X-ray diffraction (XRD).

RESULTS

CLSM showed that the dead-to-live ratio of S. mutans was 0.8 ± 0.1 in the GAPI group and 0.4 ± 0.1 in the control group (p < 0.001). The Log CFUs were 6.9 ± 0.7 in the GAPI group and 8.1 ± 0.5 in the control group (p = 0.002). SEM revealed confluent growth of S. mutans in the control group but not in the GAPI group, which also exhibited cell damage. Micro-CT showed that the lesion depth (µm) was 142 ± 11 in the GAPI group and 178 ± 20 in the control group (p < 0.001), with mineral loss (gcm⁻³) of 1.1 ± 0.1 and 1.5 ± 0.1, respectively (p < 0.001). SEM-EDS indicated that the calcium-to-phosphorus ratio was 1.71 ± 0.02 in the GAPI group and 1.67 ± 0.03 in the control group (p = 0.006). Additionally, Knoop hardness was 302 ± 22 in the GAPI group and 242 ± 17 in the control group (p < 0.001). SEM revealed an orderly pattern of enamel rods in the GAPI group, and XRD showed better crystallisation of hydroxyapatite in the GAPI group compared to the control group.

CONCLUSION

GAPI exhibits antibacterial and remineralising properties against artificial enamel caries.

CLINICAL SIGNIFICANCE

If the anti-caries properties of GAPI are confirmed in clinical studies, it could be used for caries prevention.

The use of silver diamine fluoride to prevent/treat enamel carious lesions: a narrative review

This comprehensive literature review examines the use of silver diamine fluoride (SDF) for the prevention and treatment of enamel carious lesions. SDF has been approved by different international drug associations as a caries-preventing agent to be used on deep carious lesions (dentin). However, SDF can cause staining of exposed tooth structures. Furthermore, the effect of SDF on the bond of adhesives to the tooth structure is still being determined. This review explores various studies on the use of SDF to treat enamel carious lesions, highlighting its effectiveness and preventive action. The literature suggests that SDF inhibits bacterial growth, promotes remineralization, and does not negatively affect adhesive retentions. Potassium iodide (KI) or glutathione (GSH) can reduce staining and discoloration. However, the reviewed studies have limitations. Further research, including well-designed clinical trials, is necessary to validate the findings and evaluate the long-term implications of SDF treatment. Conclusion: Despite the above-mentioned limitations, SDF shows potential as a therapy for enamel caries prevention, remineralization, and use as an adjuvant to other dental treatments, warranting further investigation and the refinement of application methods.

Copper Materials for Caries Management: A Scoping Review

This study comprehensively reviewed the types, properties and potential applications of copper materials for caries management. Two researchers independently searched English publications using PubMed, Scopus and Web of Science. They screened the titles and abstracts of publications presenting original studies for review. They included 34 publications on copper materials, which were categorized as copper and copper alloy materials (13/34, 38%), copper salt materials (13/34, 38%) and copper oxide materials (8/34, 24%). All reported copper materials inhibited the growth of cariogenic bacteria such as Streptococcus mutans and Candida albicans. The materials could be doped into topical agents, restorative fillers, dental adhesives, drinking water, dental implants, orthodontic appliances, mouthwash and sugar. Most publications (29/34, 83%) were laboratory studies, five (5/34, 14%) were animal studies and only one paper (1/34, 3%) was clinical research. In conclusion, copper and copper alloy materials, copper salt materials and copper oxide materials have an antimicrobial property that inhibits cariogenic bacteria and Candida albicans. These copper materials may be incorporated into dental materials and even drinking water and sugar for caries prevention. Most publications are laboratory studies. Further clinical studies are essential to validate the effectiveness of copper materials in caries prevention.

The preventive/therapeutic effect of CO2 laser and MI Paste Plus® on intact and demineralized enamel against Streptococcus mutans (In Vitro Study)

Background

To evaluate the preventive and therapeutic effects of CO2 laser and MI paste plus on intact and demineralized enamel surfaces and their impact on bacterial adhesion. Methods: 160 enamel slabs were prepared and randomly allocated into two main groups; sound and demineralized enamel (n = 80 per group), in which specimens were immersed in a demineralizing solution (50 mM acetic acid, pH 4.5) for 72 h at 37 °C. Each group was further divided into four subgroups (n = 20); the control (un treated surfaces), surfaces treated by CO2 laser, MI paste plus (Recaldent™, GC corporation/Germany), and those received a combination of CO2 and MI paste plus. Streptococcus Mutans biofilm was isolated, quantified, and then applied on treated enamel surfaces and incubated anaerobically for 24 h and then quantified by colony-forming unit (CFU). Meanwhile, surface changes were assessed by Vickers microhardness and Scanning Electron Microscope combined with Energy-Dispersive X-Ray Spectroscopy (SEM-EDX). Results: The combined use of CO2 laser followed by MI paste plus significantly (p < 0.000) enhanced surface microhardness of sound and demineralized enamel with a significant reduction in bacterial counts. However, each technique alone was beneficial as they exhibited higher microhardness with lower bacterial viability in comparison to the control. The treatment of demineralized enamel surfaces with MI paste significantly reduced the number of bacterial colonies with the presence of dispersed mineral deposits over the surface.

Conclusions

The combined use of CO2 laser and MI paste plus was effective as a preventive and/or therapeutic measures in enhancing surface properties of enamel and reducing the bacterial viability.

Nano-CT characterization of dentinal tubule occlusion in SDF-treated dentin

Dentin hypersensitivity is an oral health concern affecting a large percentage of the world's adult population. Occlusion of the exposed dentinal tubules is among the treatment options available, and silver diammine fluoride (SDF) is an occluding agent used for interrupting or dampening the stimulus of the dental pulp nerves that produce pain. In addition to dentin permeability testing, the evaluation of desensitizing agents occluding dentinal tubules strongly relies on microscopic techniques, such as scanning electron microscopy (SEM). Limitations of SEM are that it provides only surface images that lack detailed information on the depth of penetration and amount of material present within the treated specimen, and it is prone to sample preparation artifacts. Here, we present high-resolution X-ray computed tomography (nano-CT) as a potential method for investigating dentin specimens with occluded tubules. We studied human dentin treated with SDF as an exemplary dentinal occlusion treatment option. We evaluated the silver deposits formed on the dentin surface region near the dentinal tubules and in the tubular regions using cross-section SEM, Energy Dispersive X-ray (EDX) analysis, and nano-CT. The resulting images obtained by SEM and nano-CT had comparable resolutions, and both techniques produced images of the tubules' occlusion. Nano-CT provided three-dimensional images adequate to quantitate tubule size and orientation in space. Moreover, it enabled clear visualization of dentinal tubules in any virtual plane and estimation of the amount and depth of occluding material. Thus, nano-CT has the potential to be a valuable technique for evaluating the occluding effects of virtually any material applied to dentinal tubules, supporting deciding between the best occluding treatment options.

Using Femtosecond Laser Light-Activated Materials: The Biomimetic Dentin Remineralization Was Monitored by Laser-Induced Breakdown Spectroscopy

Introduction: The purpose of this study is to investigate and compare the effects of the antimicrobial agents Moringa oleifera and bioactive glass nanoparticles activated by femtosecond laser light on the biomimetic dentin remineralization using teeth having carious dentin ICDAS code 3. Methods and Materials: A total of 27 dentin surface samples were divided into three groups: the first group was treated with a Moringa oleifera extract, while the second group was treated with bioactive glass nanoparticles, and as for the control group, the third group received no additional agent. All groups were subjected to femtosecond laser light at three different wavelengths: 390 nm, 445 nm, and 780 nm. The photoactivation of each sample was achieved using the femtosecond laser light for 5 min with an average power rating of 300 mW, a pulse duration of 100 fs, and a pulse repetition rate of 80 Hz. The mineral content of the samples was obtained and analyzed using the laser-induced breakdown spectroscopy (LIBS). The LIBS analysis was conducted with the following laser light parameters: average power of ~215 mW, wavelength of 532 nm, pulse duration of 10 ns, and a pulse repetition rate of 10 Hz. Results: Most studied samples exhibited a relative increase in the mineral content that may enhance biomimetic remineralization. Moringa oleifera photoactivated by femtosecond laser light at 445 nm achieved a significant increase in mineral content. Conclusion: Using the femtosecond laser light to activate the relatively cheap and commercially available antimicrobial agent Moringa oleifera supports the strategy of minimal invasive approaches for the treatment and biomimetic remineralization of carious dentin ICDAS code 3.