Influence of cavity preparation with Er,Cr:YSGG laser and restorative materials on in situ secondary caries development

Surface and Mineral Changes of Primary Enamel after Laser Diode Irradiation and Application of Remineralization Agents: A Comparative In Vitro Study

OBJECTIVES

The purpose of this study is to evaluate the remineralization potential of primary teeth enamel after being exposed to different laser diode therapies.

METHODS

Ninety-six vestibular primary teeth enamel samples were divided into eight groups (n = 12) with varying treatments: control (G1), CPP-ACP-fluoride varnish (G2), diode lasers at 980 nm (G3), 808 nm (G4), 450 nm (G5), 980 nm + CPP-ACP-fluoride varnish (G6), 808 nm + CPP-ACP-fluoride varnish (G7), and 450 nm + CPP-ACP-fluoride varnish (G8). Each sample was assessed using a DIAGNOdent® (KaVo Dental, Biberach, Germany), at baseline, post-treatment, and post-pH cycle remineralization. SEM imaging was performed before and after treatment and following the pH cycle.

RESULTS

The results indicated that the 980 nm and 808 nm diode lasers, both alone and in combination with CPP-ACP-fluoride varnish, either maintained or increased the calcium (Ca) weight percentage (Wt%) in the enamel. The 980 nm diode laser combined with CPP-ACP-fluoride varnish (G6) showed a significant increase in Ca Wt%, suggesting a strong remineralization effect. Similarly, the 808 nm diode laser alone (G4) also promoted a substantial increase in Ca Wt%. In contrast, the 450 nm diode laser, whether applied alone or in combination with CPP-ACP-fluoride varnish, resulted in a lower Ca Wt% and an increase in phosphorus (P) Wt%. Most groups, except for the CPP-ACP-fluoride varnish alone (G2), demonstrated an increase in P Wt%, indicating a complex interaction between laser therapy and enamel remineralization.

CONCLUSIONS

The combined use of laser therapy with CPP-ACP-fluoride varnish significantly enhanced the remineralization of temporary teeth enamel. The 980 nm diode laser + CPP-ACP-fluoride varnish showed the most pronounced improvement in remineralization, while the 808 nm diode laser alone also effectively increased calcium solubility. These findings suggest that higher-wavelength diode lasers, particularly when combined with remineralizing agents, can effectively enhance the mineral content of primary teeth and promote enamel remineralization.

Efficacy of Nano Silver Fluoride and/or Diode Laser In Enhancing Enamel Anticariogenicity around orthodontic brackets

PURPOSE

This in vitro study aimed to compare the anticariogenic effect of using diode laser irradiation and/or nano silver fluoride varnish around orthodontic brackets.

MATERIALS AND METHODS

60 caries-free and intact premolars were randomly divided into 3 experimental groups as follow: (1) Group I (nano silver fluoride treated group, n = 20), (2) Group II (diode laser treated group, n = 20) and (3) Group III (combined nano silver fluoride and diode laser treated group, n = 20). Anticariogenicity was assessed using polarized light, scanning electron microscope, elemental and shear bond strength analyses.

RESULTS

PLM and SEM showed presence of few demineralized areas in group I. Group II revealed a dramatic increased demineralization. Group III disclosed almost typical homogenous surface enamel. elemental analysis showed a highly significant difference between Group III and II and a significant difference between Group III and I. Shear bond strength analysis revealed a significant difference between group I and II and between group III and II. The difference between group III and I was non-significant.

CONCLUSION

Both diode laser and nano silver fluoride positively affected dental enamel with the most superior enhancement in enamel criteria was achieved by surface pretreatment by combined nano silver fluoride varnish and diode laser irradiation.

Remineralization effects of Er,Cr:YSGG and/or bioactive glass on human enamel after radiotherapy-an in vitro study

The aim was to evaluate the effects of Er,Cr:YSGG and/or bioactive glass 45S5 (BG) on the chemical and physical properties of enamel after radiotherapy. Third molar crowns were cut in half (buccal-lingually), and the mid part of the labial/oral surface was subjected to different protocols. All samples were treated with standard 70 Gy. After radiotherapy, enamel was treated with either Er,Cr:YSGG (2780 nm; pulse 60 μs) and BG or only BG, and control samples were kept in deionized water. Vickers microhardness, scanning electron microscopy (SEM), and characteristic X-ray spectroscopy (EDS) were performed before, after radiotherapy, and after treatment. Analysis of variance (ANOVA) was used. A significant drop in enamel microhardness was observed after radiotherapy (p < 0.001). After Er,Cr:YSGG and BG or BG alone, there was a significant increase in microhardness (p < 0.001), which was on average significantly higher compared to the initial measurements for Er,Cr:YSGG with BG (p < 0.001), but not observed in BG alone (p = 0.331). After radiotherapy, SEM showed increased surface roughness with eroded prisms. Er,Cr:YSGG and BG or BG alone both showed disorderly packed glass particles on the enamel surface. Radiotherapy noticeably reduced the concentrations of calcium and phosphorus. Er,Cr:YSGG and BG treatment increased the concentrations of calcium, sodium, phosphorus, and silicate. BG treatment alone increased the concetration of calcium and phosphorus. Directly induced radiotherapy led to potential damage of enamel, but afterwards treatment with Er,Cr:YSGG laser and BG resulted in a higher increase of enamel microhardness compared to BG alone, reflecting in a possible better remineralization effect.

Comparative Evaluation of Influence of Nd:YAG Laser (1064 nm) and 980 nm Diode Laser on Enamel around Orthodontic Brackets: An In Vitro Study

(1) Background: The prevention of demineralizing lesions at the enamel structure level continues to represent a challenge in daily dental practice. When bacteria influence the pH level, this will decrease below the threshold for remineralization and the dissociation of hydroxyapatite will occur with a high percentage of phosphate and calcium loss. These elements continue to be studied by many authors in order to obtain a working protocol that will lead to their stabilization at the level of the enamel structure, thus preventing the demineralization process. The aim of this study is to evaluate and compare the influence of two types of laser wavelengths on the surface morphology and mineral components of the enamel through an examination with scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). (2) Methods: Thirty permanent human incisors extracted for periodontal reasons from patients aged 25−40 years old were selected for this study. Metallic brackets (SS Standard 022 Slot, OC Orthodontics, McMinnville, OR, 97128, USA) were bonded onto each tooth. The buccal surface was randomly assigned three sections: Section A—negative control (no treatment), section B—treated with 980 nm Gallium−Aluminum−Arsenide diode laser (a 300 µm optic fiber was used with 0.8 W output power, energy density of 5.33 J/mm2, in continuous mode, for 30 s, oriented perpendicularly to the enamel surface in contact mode) (KaVo GENTLEray 980 Diode Laser, Kaltenbach & Voigt GmbH, Biberach, Germany), and section C—treated with Nd:YAG laser (a 300 µm fiber was carried out at a 1 mm distance from the enamel surface with 0.75 W power, 75 mJ pulse energy, pulse repetition rate of 10 Hz, 5 J/mm2 fluency, average exposure time of 30 s, and water cooling assisted) (LIGHTWALKER AT S, M021-5AF/1 S, Fotona d.o.o, Ljubljana, Slovenia). The elements evaluated in this study were calcium (Ca), phosphate (P), oxygen (O), and carbon (C). A one-way analysis of variance, paired t-tests, and independent t-tests were carried out to evaluate the results using the SPSS 19 IBM Statistical package software for Microsoft. (3) Results: The evaluation of the data indicated that both wavelengths produced an increase in Ca wt% (for diode laser the mean of Ca wt% before irradiation was 21.06, while that after treatment reached 28.24; and for Nd:YAG laser, the mean of Ca wt% before irradiation was 21.31, while that after treatment reached 33.88); as well, the 980 nm diode laser decreased P wt% (from 17.20 before irradiation to 16.92 after irradiation) and the Nd:YAG laser increased P wt% (from 17.46 before irradiation to 18.28 after irradiation). These results showed a statistically significant difference at the p < 0.05 level. (4) Conclusions: It can be concluded that the best improvement of enamel chemical composition was obtained with Nd:YAG irradiation.

The effects of combining erbium, chromium: Yttrium-scandium-gallium-garnet laser irradiation with fluoride application in controlling the progression of enamel erosion

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Fluoride alone increased the microhardness of the enamel surface.

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Fluoride alone halted the progression of enamel erosion.

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Laser irradiation before fluoride-induced similar effects as fluoride alone.

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Laser irradiation alone did not prevent the progression of enamel erosion.

Objective

Increasing enamel resistance to acid may be useful for preventing cavitation and could reduce changes in the enamel’s microhardness. Topical fluoride application and laser irradiation promote acid resistance of dental substrates. The aim of the study was to assess the efficacy of erbium, chromium: yttrium-scandium-gallium-garnet laser irradiation in combination with fluoride application to control enamel erosion.

Design

Sixty human premolar specimens were prepared (N = 60) and were randomly assigned to 5 groups, twelve specimens in each group (n = 12/group) according to surface treatment. The groups were as follows: group 1 (C): control with no treatment; group 2 (F): application of 1.23% acidulated phosphate fluoride gel alone; group 3 (L): laser irradiation alone; group 4 (F+L): acidulated phosphate fluoride gel followed by laser irradiation; group 5 (L+F): laser irradiation followed by acidulated phosphate fluoride gel. All the specimens were eroded 10 min in citric acid. Baseline measurements were performed using a Vickers microhardness tester before surface treatment. Subsequently, all specimens were subjected to a 60 min erosion-remineralization cycle for five days followed by measurements of the final surface microhardness. Statistical comparisons were performed by a one-way analysis of variance and Tukey’s post hoc analysis.

Results

The control, laser, and fluoride + laser groups showed a statistically significant decrease in microhardness values between baseline and post-erosion measurements (P < 0.05), indicating that these treatments could not prevent erosion progression. However, the fluoride and laser + fluoride groups showed a significant increase in microhardness values compared to baseline.

Conclusions

Our results suggest that compared to that of the control group, acidulated phosphate fluoride application as well as laser irradiation prior to fluoride application increased enamel surface microhardness and prevented the progression of enamel erosion.

Laser-assisted prevention of enamel caries: a 10-year review of the literature

Since the invention of lasers in dentistry, investigations in caries prevention by the use of laser radiation have been proposed. There are several mechanisms stated for this purpose such as photothermal and/or photochemical interaction processes with the enamel. Alone or in conjugation with topical fluoride application, this treatment modality may improve enamel acid resistance in high-caries-risk populations. Data collection was done by searching the keywords caries, prevention, and laser in PubMed, Embase, Web of Science, Cochrane Library, and Google Scholar. Lasing protocols of the collected literature and their effectiveness as well as examination methods used to verify treatment outcomes have been evaluated. One hundred eighteen publications were found for the last 10 years. The wavelengths investigated for caries prevention are mainly located in the near and the mid-infrared spectral range. In the evaluated period of time, investigations using CO₂; Er:YAG; Er,Cr:YSGG; Er:YLF; fundamental, second, and third harmonic generations of Nd:YAG; diodes; and argon ion lasers were found in the databases. Accounting for 39% of the literature, CO₂ laser was the most examined system for this purpose. Reviewing the literature in this narrative review showed that all laser systems presented a positive effect in varying degrees. Laser irradiation could be an alternative or synergistic to topical fluoridation for enamel caries prevention with longer lasting effect. Further research should be focused on selecting proper laser settings to avoid damage to enamel and developing effective evidence-based clinical protocols.

Influence of Er, Cr: YSGG (2780 nm) and Nanosecond Nd: YAG Laser (1064 nm) Irradiation on Enamel Acid Resistance: Morphological and Elemental Analysis

BACKGROUND

Enamel demineralisation is an initial step of the serious dental problem including dental caries, white spot lesions and dental erosion.

AIM

Compare the effect of Er, Cr: YSGG (λ = 2780 nm) and nanosecond Nd: YAG (λ = 1064 nm) laser on enamel acid resistance.

MATERIAL AND METHODS

Thirty non-carious human premolars, extracted for orthodontic reasons, were used. The experimental groups (n = 10 each group) were: Group I, untreated (control); Group II, Er, Cr: YSGG laser irradiation (0.75 W, 20 Hz, 140 μs, 10 s); Group III, nanosecond pulsed Nd: YAG laser irradiation (0.8 W, 10 Hz, 7 ns, 10 s). Scanning electron microscope and Energy Dispersive X-ray Spectroscopy (EDX) were used to assess acquired enamel resistance to PH cycling.

RESULTS

After subjecting the three experimental groups to PH cycling, scanning electron microscopic examination revealed irregular porous dissoluted enamel surface in group I. However, groups II and III demonstrated partially dissoluted enamel surface. EDX analysis demonstrated the lowest mean percentage decrease in calcium and phosphorus content in group II followed by group III, then the highest mean percentage decrease was observed in untreated group I. One-way ANOVA revealed significant differences (p < 0.0001) between the tested groups.

CONCLUSIONS

Both Er, Cr: YSSG and nanosecond Nd: YAG laser irradiation were able to improve the acid resistance of enamel. However, enamel surface treated with Er, Cr: YSSG laser showed the lowest mean percentage decrease of calcium and phosphorus (highest acid resistance).

Er,Cr:YSGG Laser Energy Delivery: Pulse and Power Effects on Enamel Surface and Erosive Resistance

BACKGROUND

High power lasers have been suggested as a useful tool for dental caries and erosion prevention due to the increase of enamel acid resistance.

OBJECTIVE

to evaluate the effect of Er,Cr:YSGG (erbium,chromium:yttrium, scandium, gallium, garnet) laser irradiation pulse frequency and power on enamel surface and acid erosion resistance.

METHODS

By combining pulse frequency (5-75 Hz) and power settings (0.10-1.00 W), 20 irradiated groups and one nonirradiated control group were tested. A total of 63 bovine enamel blocks (n = 3/group) were prepared for surface hardness and roughness evaluation, performed in three phases: baseline, after irradiation, and after erosive challenge. Enamel blocks were irradiated with Er,Cr:YSGG laser with MZ8 tip (iPlus; Waterlase, Biolase, CA) for 30 sec according to experimental group and submitted. Erosive challenge consisted of four cycles alternating immersion in 0.01 M HCl (5 mL/mm²; 2 min; at 37°C) and immersion in artificial saliva for 3 h. Analysis of variance (three-way ANOVA), Tukey's test, and Pearson correlation were performed for the statistical analysis (p < 0.05).

RESULTS

After irradiation, groups irradiated with pulse frequency of 10 and 15 Hz showed a decrease in surface hardness. After erosive challenge, 5 and 75 W groups showed increase in surface hardness; 0.25, 0.5, 0.75, and 1 W groups showed minor alterations in surface roughness.

CONCLUSIONS

the irradiation of Er,Cr:YSGG laser with different parameters of power and pulse frequency settings may alter enamel surface and erosive resistance differently. Pulse frequency of 30 Hz and power of 0.50 W was considered the best parameter to prevent enamel acid erosion.

Secondary Caries in situ Models: A Systematic Review

In situ caries research serves as a bridge between clinical research and laboratory studies. In this kind of research, volunteers wear a removable intraoral splint or prosthesis containing research samples. Many different in situ models exist to investigate secondary caries. This systematic review compared currently existing secondary caries models and their lesion progression per day values.

MATERIALS AND METHODS

Three databases (Medline, Embase, and Cochrane) were searched for relevant literature. Bias risk was assessed and model parameters and caries-related outcomes were extracted by 2 independent researchers. Where possible, caries-related outcomes were normalized by estimating lesion progression per day by dividing lesion depth extracted from microradiographic or microhardness data by the number of days the study lasted.

RESULTS

The literature search identified 335 articles. After eliminating duplicates and selection, 31 articles were included. The models differed greatly on factors such as sample location, presence of fluoride in the model, and analysis methods. Three main groups could be identified by sample placement; 68% of models placed samples palatally in the upper jaw, and the lower jaw model could be divided into the buccal (26%) and approximal (6%) areas. Average lesion progression in enamel next to composite was 4.3 ± 2.8 µm (range1.1-8.8 µm/day).

DISCUSSION

Studies conducted with palatal models showed caries progression rates 2-5 times higher than the estimated clinical progression rates. Lesion progression per day could be a useful tool for future comparison of models and establishing a standardized model.

Screening the Drug Resistance Property Among Aerobic Pathogenic Microorganisms of Dental Caries in North-Western Indian Population: A Preliminary Study

AIMS AND OBJECTIVES

To evaluate the emerging drug resistance among the caries pathogens isolated from carious dentine microbiologically.

MATERIALS AND METHODS

Specimens from dental caries were collected from 75 patients referred to Department of Conservative Dentistry and Endodontics, Vyas Dental College. Microbiological processing of all the samples was done within three hours to isolate the caries pathogens. The samples were inoculated on agar medium (Nutrient agar, Mac-conkey's agar) at 370C for 48 hours aerobically. The identification of strains was done by observing colony morphology and gram's staining. The predominant isolates were subjected to antimicrobial sensitivity test (Kirby Bauer's method). Statistical analysis of the isolates was done using paired t-test.

RESULTS

Out of 75 patients more common isolates were Staphylococcus aureus, Klebsiella, Pseudomonas aeruginosa, Yeast. The predominant were Staphylococcus and Pseudomonas species. Newer antibiotics were proved to be effective against these predominant strains after evaluating antibiotic sensitivity tests.

CONCLUSION

Although Streptococcus mutans (S.mutans) is the most prevalent microorganism seen in dental caries, the role of other microorganisms like Staphylococcus, Pseudomonas in initiation and progression of caries is evident from this study. Further extensive and large scale studies need to be conducted for better understanding the role of these microorganisms in dental caries.