Dentinal tubules sealing by means of diode lasers (810 and 980 nm): a preliminary in vitro study

In vitro study of the effects of diode laser on dentin hypersensitivity and evaluation of intra-pulpal temperature variation

To evaluate the efficacy and safety of different wavelengths of high-power diode lasers for the treatment of dentin hypersensitivity by analyzing morphological changes and temperature variation. Human third molars were irradiated with five different commercially available lasers at wavelengths of 808 nm, 940 nm, 976 nm, and 980 nm, both with and without the use of a photoinitiator (activated charcoal). Temperature variations were monitored using thermocouples, and morphological changes were assessed through scanning electron microscopy. Lasers with wavelengths of 940 nm, 976 nm, and 980 nm, used without a photoinitiator, promoted dentinal tubule obliteration without causing thermal damage. Lasers with wavelengths of 808 nm, 940 nm, 976 nm, and 980 nm, when combined with a photoinitiator, resulted in even lower temperature variation compared to the non-photoinitiator groups, although no regular fused surface was observed. Diode laser parameters, except Group 1(808 nm without photoinitiator), are potentially safe for dentinal tubule obliteration. The use of a photoinitiator continues to be an effective strategy for minimizing temperature variations during irradiation.

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.

Evaluation of riboflavin, nanocurcumin, and hydrogen peroxide under light conditions: Reduction of mature dental biofilms and enamel mineral loss

BACKGROUND

Biofilms are a potential harbor for many microorganisms. The aim of this study was to test the efficacy of riboflavin (Rib), nano-micelle curcumin (NC), and hydrogen peroxide (HP), alone and in combination with the respective light (light-emitting diode (LED) or 980 nm diode laser) on the reduction of Streptococcus mutans and Lactobacillus acidophilus dual-species biofilms and their effect on the enamel mineral loss.

MATERIALS AND METHODS

The biofilms were formed on saliva-coated enamel slabs. Then, the biofilms were treated with antimicrobial photodynamic therapy (PDT) based on LED, Rib, and NC photosensitizers and with HP also based on a 980 nm diode laser (n = 8 per group). A crystal violet assay was performed to determine the reduction of the dual-species biofilms. The enamel slabs were analyzed for calcium and phosphorus content by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX).

RESULTS

While HP-PDT showed a reduction of 37% (p < 0.001), PDT with NC resulted in an even greater reduction of dual-species biofilms (40%, p < 0.001) than HP- and Rib-mediated PDT. In the EDX test, no significant difference was found between the control group and the treatment groups.

CONCLUSIONS

The use of natural photosensitizers such as NC in PDT has an effect that may be potentially important in reducing caries-causing bacteria.

The effect of lasers in occlusion of dentinal tubules and reducing dentinal hypersensitivity, a scoping review

BACKGROUND

Dentinal hypersensitivity (DH) is a painful condition that can affect a person's quality of life. Laser therapy is a valid treatment option for this problem, which leads to immediate and long-term pain relief. This study aims to comprehensively review the effects of different laser treatments on DH.

METHODS

The search was performed in electronic databases, including PubMed, Web of Science, Embase, Google Scholar, and Scopus, published in English from January 2012 to October 2024. The following keywords were searched: Laser, Dentine hypersensitivity, Dental pain. Relevant laboratory and clinical studies were included.

RESULTS

Based on the electronic search, 988 articles were identified. Based on the search strategy and removal of duplicate articles, 47 articles remained. Finally, with the addition of 7 supplementary articles from a manual search, 16 in-vitro and 38 clinical studies were included. Application of high power diode laser at 980 nm and 2 W and Er;Cr:YSGG at a power of 0.5 W in a single session has been found to be a practical therapeutic approach in alleviating DH. The utilization of Nd:YAG was found to be inferior in high-power settings.

CONCLUSION

Both high/medium and low power lasers have the ability to relieve DH when used with appropriate output settings. These treatments demonstrate an instant pain-relieving effect upon application and also provide long-lasting advantages. Additionally, the simultaneous use of surface desensitizers, such as Gluma and substances that contain potassium nitrate with lasers, can be a practical approach for treating DH, especially when utilizing a low-power laser.

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.

Influence of diode laser irradiation on microtensile bond strength of etch-and-rinse adhesive to dentin using two different etchants: An in vitro study

Aim

The aim of this study was to evaluate the influence of 970 nm diode laser (DL) irradiation on the microtensile bond strength (µTBS) of etch-and-rinse adhesive (ERA) to dentin using phosphoric acid (PA) or alpha-hydroxy glycolic acid (GA) as etchants.

Materials and Methods

A total of 32 human third molars were selected and assigned randomly among two different groups and four subgroups based on etching protocols and DL irradiation: PA, PA-DL, GA, and GA-DL. After tooth preparation and subsequent incremental composite build-up, the samples were stored in distilled water for 24 h at 37°C. µTBS values were obtained using the universal testing machine. The failure modes observed in dentin were categorized as adhesive, cohesive within dentin/resin, or mixed.

Statistical Analysis

The data were analyzed using one-way analysis of variance, followed by Tukey's post hoc test (P ≤ 0.001).

Results

GA showed better or similar bond strength values to PA. Furthermore, irradiation of DL increased the µTBS to dentin when both PA or GA are used as etchants.

Conclusion

GA can be used as an alternative etchant to PA. DL irradiation stands as a promising approach for elevating the performance of ERA adhesive systems to dentin.

EFFECT OF LOW-LEVEL DIODE LASER ON DENTIN TOPOGRAPHY AND SYMPTOMATIC NONCARIOUS CERVICAL LESIONS PRIOR TO COMPOSITE RESTORATIONS: A SPLIT-MOUTH RANDOMIZED CONTROLLED TRIAL

OBJECTIVES

This study assessed alterations in sensitivity among symptomatic noncarious cervical lesions (NCCLs) following the application of 3 low-level diode laser wavelengths before composite restoration. It analyzed the changes in dentin topography using a scanning electron microscope (SEM).

MATERIALS AND METHODS

Nine patients with 36 NCCLs were randomly assigned intra-individually to 4 groups based on the laser wavelength: laser simulation, 445 nm, 660 nm, and 970 nm. Cavity preparation, irradiation, and composite restoration were performed for each lesion. Sensitivity to cold stimuli was recorded using a visual analog scale (VAS) before the intervention (baseline) and at 1 day, 14 days, 1-, 3-, and 6-month. Pulp sensibility was recorded using an electrical pulp tester (EPT) at baseline, before treatment, and at 3- and 6-month. Additionally, an in vitro examination was performed on 12 extracted human molars to yield 12 dentin discs. Each disc was randomly divided into 4 quadrants to receive the same laser wavelengths to determine the diameters of the tubules using SEM. Results were analyzed statistically for clinical studies by the Friedman test, while ANOVA (RM-ANOVA) was conducted in-vitro, followed by the Bonferroni test in the case of significance (P < .05).

RESULTS

VAS readings decreased across all groups, with a significant decrease observed for 660 nm and 970 nm from 14 days to 6-month, while at 445 nm there was a significant decrease at 6-month compared to the control (P < .05). EPT showed a significant decrease in pain threshold levels at 660 nm and 970 nm at 3- and 6-month, while 445 nm showed a significant decrease at 6-month compared to the control (P < .05). The mean tubular diameter at 445 nm decreased, with no significant difference from the control, whereas a significant decrease was found at 660 nm and 970 nm compared to the control (P < .05).

CONCLUSIONS

Prior to composite restoration in symptomatic NCCLs, diode lasers with a wavelength of 660 nm showed the highest reduction in sensitivity, followed by 970 nm, whereas 445 nm diode lasers showed the least reduction. Additionally, diode lasers with wavelengths of 660 and 970 nm reduced the width of the dentinal tubules (DT) without inducing melting, as viewed under SEM.

The Efficacy of Different Laser Applications on Dentin Sealing in Preventing Discoloration Induced by Mineral Trioxide Aggregate

The aim of this in vitro study was to evaluate the effect of the pre-application of a dentin-bonding agent and the application of different lasers on the prevention of tooth discoloration caused by mineral trioxide aggregate (MTA) in the presence of blood. Sixty extracted human anterior teeth were selected, with root lengths standardized to 10 mm and root canals shaped using Gates-Glidden drills #3 to #5. The samples were divided into six groups (n = 10): Group 1 with no surface treatment and Groups 2 to 6 with Optibond universal adhesive and Neodymium yttrium aluminum garnet (Nd:YAG), Erbium yttrium aluminum garnet (Er:YAG), Erbium-chromium-yttrium-scandium-gallium-garnet (Er:Cr:YSGG), and diode laser applications, respectively. Root canals were filled with fresh human blood, and ProRoot MTA and a collagen barrier were then placed. Color changes were measured with a spectrophotometer at 0, 7, 30, 90, and 180 days post MTA placement. Color differences (∆E) were analyzed using a two-factor mixed-design ANOVA with the Sidak method (p = 0.05). All treatment groups exhibited discoloration above the acceptability threshold. Although all treatment approaches exhibited less color change compared to the control group (p < 0.05), there was no significant difference among them in terms of preventing color change (p > 0.05). It was determined that none of the methods could guarantee 100% prevention of discoloration caused by MTA-blood contact.

Canal disinfection using photo-chemically activated micro-bubble emulsion, Emblica officinalis, and Nd: YAP laser on smear layer and push-out bond strength of resin-based root canal sealer to the radicular dentin

AIMS

Evaluation of the effects of the latest root canal disinfectants i.e., Micro-bubble emulsion (MBE), Neodymium-doped yttrium aluminum perovskite (Nd: YAP), Emblica officinalis (E. officinalis) on the removal of smear layer (SL) and push out bond strength (PBS) of resin-based root canal sealer to the radicular dentin.

METHODS

The coronal portion of sixty single-rooted human mandibular premolar teeth was precisely sectioned at the cementoenamel junction. The canals were prepared to utilize ProTaper universal rotary files till F3. All the study specimens were divided into four groups based on the disinfection regime (n = 15) Group 1: 5.25% NaOCl, Group 2: MBE, Group 3: Nd: YAP laser and Group 4: E. officinalis extract. All the canals were then finally irrigated using 17% EDTA solution as a final disinfecting agent. SL removal assessment was performed on five samples from each group using a scanning electron microscope (SEM). Ten samples from each group were then filled with root canal filling material and the roots were sectioned. Push-out test and failure mode analysis were performed using the universal testing machine (UTM) and stereomicroscope respectively. The mean scores of PBS and SL removal were compared using a one-way analysis of variance (ANOVA) and Post Hoc Tukey's HSD test p = 0.05.

RESULTS

Group-2 (MBE + EDTA) coronal section (1.50 ± 0.23) exhibited the most effective eradication of SL from the canal space. The apical third of Group-1 (NaOCl+EDTA) (2.68 ± 0.82) samples demonstrated the least effective removal of SL from the radicular canal. The maximum score of PBS of AH plus sealer to the canal dentin was exhibited by the coronal section of Group-2 (MBE + EDTA) (9.55 ± 0.45 MPa) samples. However, the apical third of Group-1 (NaOCl+ EDTA) specimens (5.16 ± 0.32 MPa) demonstrated the minimum EBS.

CONCLUSION

MBE+ EDTA displayed better smear layer removal and bond integrity of AH plus sealer to the root canal dentin. Nd: YAP+ EDTA laser and E.officinalis displayed comparable outcomes to that of control NaOCl+ EDTA.

Evaluation of dentinal tubule occlusion and pulp tissue response after using 980-nm diode laser for dentin hypersensitivity treatment

OBJECTIVES

To evaluate the effectiveness of the 980-nm diode laser for dentinal tubule occlusion, measure the intrapulpal temperature, and investigate the dental pulp response.

MATERIALS AND METHODS

The dentinal samples were randomly divided into G1-G7 groups: control; 980-nm laser irradiation (0.5 W, 10 s; 0.5 W, 10 s × 2; 0.8 W, 10 s; 0.8 W, 10 s × 2; 1.0 W, 10 s; 1.0 W, 10 s × 2). The dentin discs were applied for laser irradiation and analyzed by scanning electron microscopy (SEM). The intrapulpal temperature was measured on the 1.0-mm and 2.0-mm thickness samples, and then divided into G2-G7 groups according to laser irradiation. Moreover, forty Sprague Dawley rats were randomly divided into the laser-irradiated group (euthanized at 1, 7, and 14 days after irradiation) and the control group (non-irradiated). qRT-PCR, histomorphology, and immunohistochemistry analysis were employed to evaluate the response of dental pulp.

RESULTS

SEM indicated the occluding ratio of dentinal tubules in the G5 (0.8 W, 10 s × 2) and G7 (1.0 W, 10 s × 2) were significantly higher than the other groups (p < 0.05). The maximum intrapulpal temperature rises in the G5 were lower than the standard line (5.5 ℃). qRT-PCR showed that the mRNA expression level of TNF-α and HSP-70 upregulated significantly at 1 day (p < 0.05). Histomorphology and immunohistochemistry analysis showed that, compared with the control group, the inflammatory reaction was slightly higher at the 1 and 7 days (p < 0.05) and decreased to the normal levels at 14 days (p > 0.05).

CONCLUSIONS

A 980-nm laser at a power of 0.8 W with 10 s × 2 defines the best treatment for dentin hypersensitivity in terms of compromise between the efficacy of the treatment and the safety of the pulp.

CLINICAL RELEVANCE

The 980-nm laser is an effective option for treating dentin sensitivity. However, we need to ensure the safety of the pulp during laser irradiation.

Comparative evaluation of diode laser alone and in combination with desensitizing toothpaste in occlusion of dentinal tubules - A SEM study

Background

In regular dental practice, dentinal hypersensitivity is a common oral condition affecting the adult population. Although a variety of treatment procedures are available, there is no single method that proved to be potent in eliminating dentine hypersensitivity and providing patients with complete relief. Hence the present study performed to estimate the occlusion of dentinal tubules using a diode laser alone and in combination with various desensitizing toothpaste, using the scanning electron microscope.

Materials and methods

This in-vitro study consisted of five groups wherein cervical cavities were prepared on the extracted teeth followed by the application of 17% EDTA. The cavities were then treated with Novamin toothpaste, pro-arginine toothpaste, diode laser, and in combinations respectively. Then SEM analysis was done and the results obtained were statistically analyzed using tukey's multiple post hoc analysis for intra and inter group comparisons.

Results

The groups which were treated with a combination of diode laser and the desensitizing agent showed statistically significant (P < 0.05) better dentinal tubule occlusion than other groups.

Conclusion

The use of a diode laser has an added benefit in treating dentinal tubule occlusion when compared to desensitizing kinds of toothpaste.

An in vitro study on the efficacy of hydrogen peroxide mediated high-power photodynamic therapy affecting Enterococcus faecalis biofilm formation and dispersal

OBJECTIVE

Biofilms are involved in failure of root canal treatment due to their high resistance to antimicrobial agents, which make their removal as a big challenge. The present study aims at utilizing hydrogen peroxide (HP) plus high frequency laser reinforced antimicrobial photodynamic therapy (a-PDT) as a complementary therapy against Enterococcus faecalis (E. faecalis) at planktonic and biofilm stages.

MATERIALS AND METHODS

E. faecalis at planktonic and biofilm stages was treated with the photosensitizer HP, followed by no irradiation or irradiation with a power of 2.5 W (ʎ = 980 nm). The cell viability, anti-biofilm, anti-metabolic potential, and temperature changes were evaluated.

RESULTS

The combination of HP and 980 nm diode laser intensely boosted antibacterial and anti-biofilm efficacy compared with either component alone, affirming HP reinforcement as a bacteriostatic agent. The maximum effect on biofilm occurs in 5.25% sodium hypochlorite (NaOCl) group. During laser irradiations, the mean of temperature changes remains below 5.6 °C.

CONCLUSIONS

It could be concluded that the HP could improve anti-biofilm efficacy as a photosensitizer in a-PDT.

Efficacy of 810 nm and 650 nm Diode Laser Alone and in Combination With Sodium Fluoride Gel in Treating Dentin Hypersensitivity: A Split-Mouth Randomized Clinical Study

Introduction Dentin hypersensitivity has been defined as a short, sharp pain caused by exposing naked dentin to external stimuli such as evaporation, heat, cold, osmotic liquids, and tactile effects. None of the available treatments has been considered the gold standard in treating dentin hypersensitivity. The use of laser has recently become more popular, and it is a promising treatment method in this field. The study aimed to compare the effectiveness of both 810 nm and 650 nm diode lasers in treating dentin hypersensitivity. Materials and methods This study was conducted on six patients who were referred to the Department of Oral Medicine, Faculty of Dental Medicine, Damascus University (4 females and 2 males) with 108 teeth suffering from generalized dentin hypersensitivity and were randomly divided into two groups. Group 1 consisted of three patients with 50 teeth treated with an 810 nm diode laser; it was divided by the split-mouth design into two subgroups. The first subgroup was treated by the application of the laser alone toward the target area with 1-watt power, continuous mode, and a total application time of 90 seconds, and the second subgroup was treated by applying sodium fluoride gel for one minute, then the laser was applied with the same settings as the first subgroup. Group 2 consisted of three patients with 58 teeth treated with a 650 nm diode laser; it was divided by the split-mouth design into two subgroups. The first subgroup was treated by the application of the laser alone toward the target area with 200 m watt power, continuous mode, and a total application time of 120 seconds, and the second subgroup was treated by applying sodium fluoride gel for one minute and then applying the laser with the same settings as the first subgroup. The pain was evaluated using a numeric rating scale (NRS) of 100 degrees before and immediately after treatment, and then after three to six and nine months by applying an air stream from a dental chair syringe at a distance of 0.5 cm from the target area. Results This study showed that both types of lasers were effective in treating pain caused by dentinal hypersensitivity. The average values ​​of pain reduction on the NRS showed the superiority of the 810 nm diode laser over the 650 nm after treatment and at all time points of pain assessment. No statistically significant differences were detected between applying laser alone and applying it combined with sodium fluoride gel in pain reduction values. Conclusions The application of an 810 nm diode laser either alone or in combination with sodium fluoride gel in treating dentin hypersensitivity is effective and better than the application of a 650 nm diode laser either alone or in combination with sodium fluoride gel. In addition, applying a 650 nm diode laser either alone or in combination with sodium fluoride gel has slight effectiveness in treating dentine hypersensitivity, and it is believed that a single treatment session with a 650 nm diode laser was not enough to obtain the required pain reduction.

Effect of Ultrasonic and Diode Laser Irrigation Activation on Post-operative Pain and Microbial Reduction in Single Visit Endodontic Treatment of Necrotic Mandibular Molars

Aim: To clinically evaluate the effect of continuous ultrasonic and diode laser 810 wave length irrigation activation techniques on postoperative pain and bacterial reduction in single visit endodontic treatment of mandibular molars. Material and methods: Forty patients requiring root canal treatment therapy for necrotic mandibular molars teeth were included in this study with age ranges between 20 and 45 years. In all cases, single visit endodontic treatment was carried out using Revo-S rotary file system in crown down sequence. NaOCl 2.5% irrigation solution was used during treatment. Patients were randomly and equally assigned into two groups according to irrigation technique. Group (1): conventional syringe irrigation and group (2): continuous ultrasonic irrigation. Each group was subdivided into two sub groups (n = 10); subgroup 1A (conventional syringe irrigation with no laser), subgroup 1B (conventional syringe irrigation with diode laser), subgroup 2A (continuous ultrasonic irrigation with no laser) and subgroup 2B (continuous ultrasonic irrigation with diode laser). Postoperative pain evaluation was done using Visual Analogue Scale (VAS) at 6, 12, 24, 36, 48 hours and 7 days postoperatively. Microbiological detection of bacterial reduction was done by taking Samples (S1 and S2) for bacterial cultures. S1 after finishing access cavity and before mechanical preparation and S2 after finishing mechanical preparation and irrigation activation and before obturation. Samples were cultured on blood agar and determined as colony forming units (CFU/mL). Microbiological bacterial reduction was calculated accordingly.  Statistical analyses were analyzed using the Mann-Whitney U test.  The significance level was set at p < 0.05. Results: In all sub groups, postoperative pain decreased by time in all time intervals but pain was significantly lower in subgroup (2B) (continuous ultrasonic irrigation with diode laser) than subgroup (1A) (conventional syringe irrigation with no laser) in all time interval. Microbiological results showed the highest bacterial reduction was in subgroup (2B) (continuous ultrasonic irrigation with diode laser) and least bacterial reduction was in subgroup (1A) (conventional syringe irrigation with no laser). Conclusion: Using diode laser and continuous ultrasonic irrigation activation techniques as adjunctive methods showed improvement in postoperative pain records and enhanced bacterial reduction in root canal therapy. Keywords: Continuous ultrasonic irrigation, diode laser 810, post-operative pain, bacterial reduction, single visit endodontic treatment.

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.

Parameters Used With Diode Lasers (808-980 nm) in Dentin Hypersensitivity Management: A Systematic Review

Introduction: The present study aimed to describe parameters used with 808- to 980-nm wavelength diode lasers for managing dentin hypersensitivity and analyze their results. Methods: The inclusion criteria were based on randomized controlled clinical trials using diode lasers at an 808-980 nm wavelength range in patients with dentine hypersensitivity with a minimum of 1-month follow-up. An electronic search for articles on Medline, PubMed and Cochrane databases was performed. The risk of bias was assessed with the Cochrane collaboration tool. Results: Our electronic search resulted in 130 papers, of which 11 articles met the inclusion criteria. A majority of the studies assessed dentine hypersensitivity using the Visual Analogue Scale, which ranged between 2.3 and 8.8 before treatment and significantly reduced to a mean value of 0.45-3.7 after diode laser application. The power settings ranged between 1.5 mW and 3 W with an emission mode of continuous wave, except for 2 authors who used chopped mode. The energy density varied from 2.5 to 128 J/cm2, and the exposure time was between 10 and 120 seconds. The authors applied a minimum of 1 to 4 treatment sessions with a 2-day to 1-week interval between them. Most of the studies mentioned the tooth surface as the treatment site but without describing the specific irradiation points. Conclusion: Despite the heterogeneity of the analyzed variables, a statistically significant improvement in all laser groups was described. However, they cannot be compared homogenously.

Comparative Efficacy of Diode, Nd:YAG and Er:YAG Lasers Accompanied by Fluoride in Dentinal Tubule Obstruction

Introduction: Recently, the management of dentin hypersensitivity by lasers has gained special attention. This study aimed to assess and compare the efficacy of the 980 nm diode, Nd:YAG and Er:YAG lasers accompanied by fluoride in dentinal tubule obstruction. Methods: Twenty sound single-rooted human teeth were used for this invitro study. Forty dentinal discs were prepared of the roots and etched with 6% citric acid. One layer of fluoride varnish was applied over their surface. The sections were randomly allocated into 4 groups. The control group received no laser irradiation. Group 2 underwent 980 nm diode laser irradiation with 0.5 W power. Group 3 underwent Nd:YAG laser irradiation with 0.5 W power and group 4 underwent Er:YAG laser irradiation with 0.5 W power. All samples were then inspected under a scanning electron microscope, and the number of obstructed dentinal tubules and the diameter of open dentinal tubules in the field were determined. One-way ANOVA and Tukey's test were used for data analysis at a significance level of 0.05. Results: All three laser types decreased the number of open dentinal tubules significantly compared to the control group (P<0.05). No significant difference was noted in dentinal tubule obstruction between the three laser groups (P>0.05). The diameter of open tubules in the three laser groups did not show a significant difference from that in the control group. Conclusion: All three types of lasers evaluated in this study can effectively obstruct the dentinal tubules.

Influence of Diode Laser for the Treatment of Dentin Hypersensitivity on Microleakage of Cervical Restorations

Noncarious cervical lesions (NCCLs) are a common clinical finding often linked with dentin hypersensitivity (DH). Aim. The aim of the study was to evaluate the influence of diode laser for the treatment of DH on microleakage of subsequent NCCL restorations. Materials and Methods. Forty-eight extracted human premolars were collected. All teeth received standardized cervical preparation on both the buccal and palatal surfaces and were randomly divided into three groups (n = 16) according to the restorative material used: nanohybrid composite resin (CR), resin-modified glass ionomer (RMGI), and conventional glass ionomer (GIC). The prepared cavities on the palatal surfaces were treated by diode laser using SIROlaser Blue (Sirona Dental Systems, Bensheim, Germany) prior to restoration, while preparations on the buccal surfaces were directly restored. After thermocycling, the teeth were immersed in methylene blue dye for microleakage evaluation under 40x magnification at both occlusal and cervical margins. The Kruskal-Wallis test followed by the Bonferroni tests was conducted to determine inter- and intragroup differences (P < 0.05). Results. All restorative materials tested showed some degree of microleakage with no statistically significantly different scores with or without the use of laser desensitization prior to restorative treatment. Group CR showed the least microleakage, followed by group RMGI, while group GIC showed the highest. Cervical margins showed greater microleakage than the occlusal margins where the difference was statistically significant in the RMGI group without laser pretreatment (P = 0.006) and in both groups CR (P = 0.02) and RMGI (P = 0.006) with the laser pretreatment. Conclusion. Application of diode laser for the treatment of DH prior to the restoration of teeth with NCCL did not affect the microleakage of all the restorative materials tested. All the materials showed some degree of microleakage, which was higher in gingival margins compared to occlusal margins. The resin composite shows the least microleakage among all the tested materials.

Low level laser therapy, Er,Cr:YSGG laser and fluoride varnish for treatment of dentin hypersensitivity after periodontal surgery: A randomized clinical trial

This clinical trial aimed to compare the effects of low-level laser therapy (LLLT), Er,Cr;YSGG laser, and fluoride varnish, as compared to the placebo laser on decreasing dentin hypersensitivity (DH). This randomized, double-blinded clinical trial included 60 jaw quadrants in 24 patients who underwent periodontal surgery. The quadrants were randomly assigned to 4 groups and received treatments as follows. Group 1: LLLT with a combination of red and infrared wavelengths, group 2: Er,Cr:YSGG laser (0.25 W and 0.5 W), group 3: fluoride varnish, and group 4: placebo laser. The sensitivity response to the cold spray was recorded using visual analogue scale (VAS) at baseline, immediately, and 1 week post-treatment. The data were analyzed by repeated measures analysis at the significance level of P<0.05. There was a significant reduction in DH after treatment by low-level lasers, Er,Cr:YSGG laser, or fluoride varnish compared to the baseline data (P<0.05), but the placebo group displayed no significant alteration in DH (P=0.069). At 1 week, the VAS score in the Er,Cr:YSGG laser group was significantly lower than that of the LLLT (P= 0.043) and placebo (P<0.001) groups. Furthermore, the subjects who received fluoride varnish exhibited significantly lower DH compared with the placebo group (P = 0.023). Er,Cr:YSGG laser was the most effective strategy in dealing with DH, as it caused the greatest pain reduction over the study period and showed a significant superiority over LLLT and placebo groups. Alternatively, the application of fluoride varnish could be recommended for attenuating DH following periodontal surgery.

Evaluation of diode laser along with 1.23% acidulated phosphate fluoride gel on dentinal tubule occlusion: An in vitro study

Context

Several studies have recommended the use of lasers in treatment of dentinal hypersensitivity. These materials have been used alone or in combination with an active desensitizing agent.

Aims

The present study aimed to evaluate the use of 1.23% acidulated phosphate fluoride (APF) gel and 810 nm diode laser when used alone and when used together on exposed dentinal tubules.

Settings and Design

Sixty-one extracted teeth were sectioned with a diamond saw and dentin slices were prepared. They were then treated with 37% orthophosphoric acid to remove the smear layer.

Materials and Methods

One of the 61 sections was left as an untreated control, whereas the remaining sixty sections were divided into three groups of twenty sections each. The first set of sections (Group 1) was treated with laser alone, whereas the second set (Group 2) was treated with APF alone. A third set of sections (Group 3) was treated with a combination of laser and APF. The sectioned teeth were then evaluated using field emission scanning electron microscopy, and the percentage of dentinal tubule occlusion was observed.

Statistical Analysis

The Shapiro-Wilk normality test was performed to check for the normal distribution of data, whereas the Kruskal-Wallis test was used to compare the mean percentage of dentinal tubule occlusion between the three groups. The Chi-square test was used to compare the number of images with complete tubular occlusion between the three groups.

Results

A total of 96 images were processed from the sixty sectioned samples. It was seen that the sections in Group 3 showed the highest percentage of dentinal tubule occlusion. Group 3 also showed the highest number of samples with complete dentinal tubule occlusion. Significantly lesser levels of dentinal tubule occlusion were seen in Groups 1 and 2.

Conclusions

Diode lasers were effective in occluding dentinal tubules. The addition of 1.23% APF significantly increased the efficacy and thoroughness of dentinal tubule occlusion. Significantly lesser levels of dentinal tubule occlusion were seen in the sections treated with laser alone and APF alone.

Influence of an 810-nm Diode Laser on the Temperature Changes of the External Root Surface: An In Vitro Study

Background and Aims:

Rising effects of temperature due to laser use during root canal disinfection may harm periodontium and alveolar bone. Therefore, the aim of this study was to estimate the surface root temperature of lower incisors throughout the application of different power levels and times of an 810-nm diode laser.

Materials and Methods:

Sixty single-rooted extracted human lower incisor teeth were selected and chemomechanical preparation was performed. Specimens were irradiated using 810-nm diode laser at 1.05, 1.5, and 1.95 W power settings and two periods of time 20 and 60s, in a continuous wave (CW) mode, without water spray. Specimens were divided into three main groups (n = 20). Each group was subdivided into two subgroups (n = 10). Then, the peak temperatures at the middle and apical regions of the root surface were registered using a thermocouple.

Results:

Temperature rise of root surface at all the selected output powers was below 7°C. The highest temperature value was obtained in the apical region at 60s when the root canal irradiated at 1.95 W output power.

Conclusion:

Diode laser is safe for use as a root canal disinfectant. Time of exposure to laser irradiation has an effect on the temperature difference at different output powers.

Evaluation of the Effects of 810 nm Diode Laser Alone and in Combination With Gluma© and Chromophore on Dentinal Tubule Occlusion: A Scanning Electron Microscopic Analysis

Introduction: Tooth hypersensitivity is among the most common patient complaints caused by the response of exposed dentin to external stimuli. No definite treatment has been suggested so far for dentin hypersensitivity (DH). This study aimed to compare the efficacy of the diode laser alone and in combination with Gluma and chromophore in occluding opened dentine tubules and the treatment of DH. Methods: This in vitro study was conducted on 30 extracted human third molars kept in 0.1% thymol solution. The teeth were mounted in transparent acrylic resin and the buccal enamel was cut to expose the outer third of dentin. The samples were then divided into 6 groups of negative control (no smear layer removal), positive control (smear layer removal with 6% citric acid application), 810 nm diode laser irradiation (energy density 55.55 J/cm2 , 1 W for 20 seconds in a continuous mode), chromophore (1 mg/mL indocyanine green, ICG) plus diode laser irradiation (1 W, 20 seconds), Gluma plus diode laser irradiation, and Gluma + chromophore + diode laser. Dentinal tubules were evaluated under a scanning electron microscope at x2000 magnification. The mean percentage of the obstruction of dentinal tubules was reported as mean and standard deviation. Considering the normal distribution of the data, two-way ANOVA was applied to compare the efficacy of treatments, and an independent-samples t test was used for pairwise comparisons at P<0.05 level of significance. Results: The highest mean percentage of the obstruction of dentinal tubules was noted in the diode laser/chromophore/Gluma group (65.68±12.31%) while the lowest value was noted in the diode laser/Gluma group (24.33±5.90%). Pairwise comparisons revealed significant differences between all groups (P <0.05) except for the difference between the laser/Gluma/chromophore and laser/ chromophore groups (P =0.20). Conclusion: It seems that chromophore increases the efficacy of the diode laser for the obstruction of dentinal tubules.

Combination effects of diode laser and resin-modified tricalcium silicate on direct pulp capping treatment of caries exposures in permanent teeth: a randomized clinical trial

OBJECTIVE

The purpose of this randomized clinical trial was to evaluate efficiency of diode 808-nm (Picasso-AMD, USA) laser using power 1.5 W, continuous wave (CW), fiber diameter of 400 μm, non-initiated and in contact mode, tip angle set at 90°, beam divergence 16°, 2 s per an area with 1-mm diameter, power density 190.98 W/cm², energy density 381.97 J/cm², vertical and horizontal scanning movement on the exposure site, and laser irradiation combined with a resin-based tricalcium silicate material (TheraCal LC, Bisco, USA) in direct pulp capping in caries exposures of permanent teeth over a period of 6 months.

MATERIAL AND METHODS

In this randomized clinical trial, a total of 20 anterior and posterior vital teeth without symptoms and radiographic changes of 14 patients between the age group of 15-35 years, of which randomly 10 teeth were considered, each for TheraCal LC, the exposed area was sealed with TheraCal paste and TheraCal combined with diode laser; the treated area was sealed with TheraCal paste after diode 808-nm laser irradiation. At the 1-, 3-, and 6-month recall examinations, the loss of vitality, spontaneous pain, reactions to thermal stimuli and percussion, and radiographic changes were considered failure. The samples were randomly divided using runs test. Measurements on the digitized radiograph were performed at the recalls. The data were analyzed by repeated measurements ANOVA using SPSS 25.

RESULTS

Analysis had indicated that at the end of follow-ups, a statistically significant increase in dentin thickness with both groups (p value < 0.001) was found. Clinically, diode laser group has shown better results (p value < 0.001); however, radiographically, no significant difference was observed between groups (p value = 0.56). In both groups, the highest thickness of dentin formed was at the first month; 0.40 mm ± 0.19 mm (p value < 0.001).

CONCLUSION

Diode laser 808 nm under proper parameters combined with TheraCal LC can be recommended for direct pulp therapy in caries exposure of permanent teeth.

CLINICAL TRIAL REGISTRATION

This research was approved by Esfahan Medical University, Dental School, Azad Branch (KHUISF)) Esfahan, Iran [IR.IAU.KHUISF.REC.1397.261].

Q-Switch Nd:YAG Laser-Assisted Decontamination of Implant Surface

Peri-implantitis (PI) is an inflammatory disease of peri-implant tissues, it represents the most frequent complication of dental implants. Evidence revealed that microorganisms play the chief role in causing PI. The purpose of our study is to evaluate the cleaning of contaminated dental implant surfaces by means of the Q-switch Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser and an increase in temperature at lased implant surfaces during the cleaning process. Seventy-eight implants (titanium grade 4) were used (Euroteknika, Sallanches, France). Thirty-six sterile implants and forty-two contaminated implants were collected from failed clinical implants for different reasons, independent from the study. Thirty-six contaminated implants were partially irradiated by Q-switch Nd:YAG laser (1064 nm). Six other contaminated implants were used for temperature rise evaluation. All laser irradiations were calibrated by means of a powermetter in order to evaluate the effective delivered energy. The irradiation conditions delivered per pulse on the target were effectively: energy density per pulse of 0.597 J/cm², pick powers density of 56 mW/cm², 270 mW per pulse with a spot diameter of 2.4 mm, and with repetition rate of 10 Hz for pulse duration of 6 ns. Irradiation was performed during a total time of 2 s in a non-contact mode at a distance of 0.5 mm from implant surfaces. The parameters were chosen according to the results of a theoretical modeling calculation of the Nd:YAG laser fluency on implant surface. Evaluation of contaminants removal showed that the cleaning of the irradiated implant surfaces was statistically similar to those of sterile implants (p-value ≤ 0.05). SEM analysis confirmed that our parameters did not alter the lased surfaces. The increase in temperature generated at lased implant surfaces during cleaning was below 1 °C. According to our findings, Q-switch Nd:YAG laser with short pulse duration in nanoseconds is able to significantly clean contaminated implant surfaces. Irradiation parameters used in our study can be considered safe for periodontal tissue.

Dentinal Hypersensitivity Treatment Using Diode Laser 980 nm: In Vivo Study

The discomfort of patients due to dentinal hypersensitivity (DH) is one of the main challenges that dentists face in daily practice. Difficulties in DH treatment gave rise to many protocols which are currently used. The aim of this clinical study is to evaluate the effectiveness of a new protocol on the reduction of dentinal hypersensitivity with diode laser 980 nm and the application of a graphite paste. 184 patients enrolled in the study, the degree of pain was evaluated by visual analog scale (VAS), graphite paste was applied on the exposed dentine before irradiation, the application of diode laser 980 nm with continuous mode, backward motion, tangential incidence of the beam in non-contact mode and a delivery output of 1 W. Fiber’s diameter was 320 μm and total exposure time depended on the time necessary to remove the graphite paste from the teeth. Statistical analyses were performed with Prism 5^® software. Pain in post-operative significantly decreased immediately after the treatment. Mean values stayed stable until a 6-month follow-up. The application is considered to be safe with long-term effectiveness.

Effect of photobiomodulation with low-level laser therapy combined with potassium nitrate on controlling post-bleaching tooth sensitivity: clinical, randomized, controlled, double-blind, and split-mouth study

OBJECTIVES

To evaluate the effect of photobiomodulation with low-level laser therapy (PBM-LLLT) combined with 5% potassium nitrate (KNO₃) on controlling tooth sensitivity (TS) after in-office tooth bleaching.

MATERIALS AND METHODS

Fifty volunteers were selected based on the inclusion and exclusion criteria and were randomly allocated into four groups: G1 (control): placebo gel application, 35% hydrogen peroxide bleaching (HP35) and mock PBM-LLLT without light emission; G2: placebo gel application, bleaching with HP35 and PBM-LLLT; G3: application of KNO₃, bleaching with HP35 and mock PBM-LLLT; and G4: application of KNO₃, bleaching with HP35 and PBM-LLLT. A pain assessment questionnaire was used to evaluate TS during the 21 days of treatment. The Friedman test was used for intragroup analysis, and the Wilcoxon and Mann-Whitney tests were used for intergroup comparisons.

RESULTS

The intragroup evaluation showed significant differences among the evaluation times in all groups (p ≤ 0.05). The highest pain sensitivity levels were recorded on the 1st, 8th, and 15th days. In G1, TS manifested for up to 3 days after each bleaching session, while G2, G3, and G4 presented TS only on the days of the bleaching sessions. Intergroup analysis showed that TS manifestation differed significantly between G1 and the other groups (p ≤ 0.05) but did not differ significantly among G2, G3, and G4 (p ≥ 0.05).

CONCLUSION

PBM-LLLT and KNO₃ are effective at reducing pain sensitivity after tooth bleaching, but no synergistic effect between these treatments was observed for the different evaluation periods.

CLINICAL RELEVANCE

The effect of PBM-LLLT combined with KNO₃ on post-bleaching tooth sensitivity is similar to their individual use alone.

Effect of 830 nm Diode Laser Irradiation of Root Canal on Bond Strength of Metal and Fiber Post

OBJECTIVE AND BACKGROUND

The correct selections of the cementing agent, the endodontic post material and placement protocol are critical to provide an increased longevity of the teeth that went through endodontic treatment. The irradiation with diode laser before post cementation, can promote an antimicrobial effect. However, there is a lack of information about the effect of 830 nm diode laser on the post bond strength. This study analyzed the effect of dentin root canal irradiation with high-intensity diode laser, at 830 nm, operating in continuous or pulsed mode, on the retention of metal or fiber posts, cemented with self-etching resinous composite (Panavia F) and zinc phosphate cement (ZnPO₄).

MATERIALS AND METHODS

Human roots were irradiated with diode laser (continuous and pulsed mode). The fiber posts were luted with Panavia F and the metal posts with Panavia F or ZnPO₄ cement. Specimens were sectioned into three sections (cervical, middle, and apical). The bond strength was measured by a push-out mechanical analysis. For the statistical analysis, a three-way ANOVA test was applied following a Tukey's pairwise comparison with a significance level of p = 0.05.

RESULTS

The irradiated groups presented higher bond strength compared with nonirradiated group (p < 0.05), and the cervical and middle thirds presented higher on bond strength than the apical. The association of metal post and Panavia F presented higher bond strength when irradiated on continuous mode (p < 0.05). Fiber post and Panavia F presented higher bond strength associated to pulsed mode. The mode seems not to make a significant difference.

CONCLUSIONS

These results corroborate the importance of the post bond to dentin and root canal debris removal to increase the tooth longevity. It was shown that the dentin to post bond strength were enhanced by the diode laser irradiation either on continuous or pulsed modes.

Effect of combined application of high- and low-intensity lasers on dentin hypersensitivity: A randomized clinical trial

Background. Diode lasers (DLs) have demonstrated equal or better desensitizing effects than fluoride varnish, 10% potas-sium nitrate (NK) gel and Gluma. The current study evaluated the desensitizing effect of combined application of DLs with two different output powers and compared it with single DL therapy. Methods. Sixty-two hypersensitive teeth were allocated randomly into two groups: the single group was treated with 3-W DL beam once and in the combined group, the teeth were irradiated three times (the first time with 0.2-W and then with 3-W and the second and third times, 48 and 96 hours after the baseline visit, with 0.2-W DL beams). The amount of dentin hyper-sensitivity (DH) was evaluated, immediately before and after each visit, and 1 week and 1 and 3 months after the first visit. Data analysis was performed using chi-squared test, repeated measurement of ANOVA and Mann-Whitney U test. P<0.05 was considered statistically significant. Results. Statistically significant changes were observed in the means of VAS indices between all the measurement intervals and pretreatment measures, in both experimental groups (P<0.001). The difference in VAS reduction among the groups was not significant when the hypersensitive teeth were stimulated by a periodontal probe and a jet of air (P=0.63 and P=0.12). Conclusion. The results of the present study showed that using both high-intensity and combined DL beams gives rise to significant reductions in DH. There was no significant difference between combined and single laser therapies in the treatment of tooth hypersensitivity.

Efficacy of different strategies to treat root dentin eroded by liquid or gaseous hydrochloric acid associated with brushing abrasion

OBJECTIVE

This study aims to evaluate how casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) associated with Nd:YAG or Diode laser affects dentin exposed to hydrochloric acid (HCl) with or without tooth brushing.

DESIGN

One hundred and sixty human root dentin blocks were selected after they were initially eroded with liquid HCl (pH 1.2) 3x for one day. The blocks were divided into the following groups: G1- liquid HCl (HCl-l), G2- HCl-l + brushing, G3- gaseous HCl (HCl-g), and G4- HCl-g + brushing. Each group was randomly assigned to the following treatments (n = 10): A) Control (no treatment), B) CPP-ACP, C) CPP-ACP associated with Nd:YAG laser (λ = 1064 nm) (40 mJ, 10 Hz, 0.4 W, 15 s), and D) CPP-ACP associated with Diode laser (λ = 980 nm) (0.5 W, 200 μs, 15 s). The treatment with CPP-ACP (G2, G3 and G4) was applied on the dentine surface for 5 min. Erosion (6x/day/20 s) and erosion (6x/day/20 s) with abrasion (2x/10 s) were performed for five days. Dentin volume loss was determined by 3D confocal laser microscopy. Data were analyzed with two-way ANOVA and Tukey's tests.

RESULTS

G1 - CPP-ACP (10.77 ± 1.66) and CPP-ACP associated with Diode laser (9.98 ± 0.89) showed lower volume loss in relation Control group (12.86 ± 0.63) (p < 0.05). G2 - CPP-ACP associated with Diode laser (12.41 ± 1.08) elicited lower volume loss as compared to the Control (14.42 ± 1.24) (p < 0.05). As for G3 and G4, all treatments showed similar volume loss.

CONCLUSION

CPP-ACP and CPP-ACP associated with Diode laser could control dental tissue loss in dentin eroded by liquid HCl. Moreover, CPP-ACP associated with Diode laser could effectively decrease dental tissue loss in dentin exposed to liquid HCl and brushing.

Surface roughness and bacterial adhesion on root dentin treated with diode laser and conventional desensitizing agents

The treatments for dentin hypersensitivity (DH) may change the surface roughness of the root dentin, which can lead to biofilm accumulation, increasing the risk of root caries. The aim was to compare the surface roughness of root dentin after different treatments of DH and the biofilm formation on those surfaces. After initial surface roughness (Sa) assessment, 50 bovine root fragments received the following treatments (n = 10): G 1-no treatment; G2-5% sodium fluoride varnish; G3-professional application of a desensitizing dentifrice; G4-toothbrushing with a desensitizing dentifrice; and G5-diode laser application (908 nm; 1.5 W, 20 s). The Sa was reevaluated after treatments. Afterward, all samples were incubated in a suspension of Streptococcus mutans at 37 °C for 24 h. The colony-forming units (CFU) were counted using a stereoscope, and the results were expressed in CFU/mL. The one-way ANOVA and the Tukey's tests compared the roughness data and the results obtained on the bacterial adhesion test (α = 5%). G2 (2.3 ± 1.67%) showed similar Sa variation than G1 (0.25 ± 0.41%) and G5 (5.69 ± 0.99%), but different from group G3 (9.05 ± 2.39%). Group 4 showed the highest Sa variation (30.02 ± 3.83%; p < 0.05). Bacterial adhesion was higher in G4 (2208 ± 211.9), suggesting that bacterial growth is greater on rougher surfaces. The diode laser and the conventional treatments for DH may change the surface roughness of the root dentin, but only brushing with desensitizing dentifrice induced a higher bacteria accumulation on root dentin surface.

Comparative Evaluation of Efficacy of Iontophoresis with 0.33% Sodium Fluoride Gel and Diode Laser Alone on Occlusion of Dentinal Tubules

INTRODUCTION

Dentinal Hypersensitivity (DH) is one of the most commonly encountered clinical problems. Literature reveals no specific therapy to satisfactorily eliminate dentinal hypersensitivity.

AIM

The aim of this study was to assess and compare the efficacy of iontophoresis with 0.33% Sodium Fluoride (NaF) gel and diode laser alone in dentinal tubule occlusion.

MATERIALS AND METHODS

This in vitro study included 20 teeth with intact root surfaces unaltered by extraction procedure for specimen preparation. Each tooth was cleaned, air dried and cut into three sections. Total 60 sections were prepared (30 longitudinal and 30 transverse sections), which were acid etched. In control group, no treatment was carried. In iontophoresis treatment group, samples were inserted into a foam tray containing 0.33 % NaF Gel and subjected to 1.5 mA output current for three minutes. In laser treatment group, specimens were lased with 980 nm diode laser at 0.5 W/PW (62.2J /cm²) in a noncontact mode for 30 seconds. Specimens were evaluated under Scanning Electron Microscope (SEM) at 10KV to 20KV under x 2000, x5000 magnification for surface characteristics and patency of dentinal tubules. Total number of tubules visible, open, completely and partially occluded were recorded in each microphotograph and compared.

RESULTS

On comparison, laser group showed the least number of open tubules i.e., 130 (31.1%) followed by iontophoresis group, 155 (51.32%) and control group 417 (100%).

CONCLUSION

Diode laser application provided better results as compared to iontophoresis on occlusion of dentinal tubules. Hence, it can be used to treat the patients with DH.

Effects of different desensitizing treatments on root dentin permeability

The objective of this study was to evaluate the effects of diode laser and a desensitizing dentifrice on dentin permeability. Fifty-two root dentin fragments were obtained (5 × 5mm) and treated with 24% EDTA gel. The samples were divided into 4 groups (n = 13): G1, control (no treatment); G2, diode laser (λ = 908 nm, 1.5 W, continuous mode, 20s); G3, application of abrasive dentifrice for 1 minute (Elmex Sensitive Professional (International Gaba); and G4, application of abrasive dentifrice for 1 minute followed by irradiation with diode laser. Ten samples per group were immersed in 2% methylene blue solution for 4h. The specimens were washed, longitudinally sectioned, observed under optical microscopy, photographed and assessed based on the degree of dye leakage. The remaining samples were observed under scanning electron microscopy (SEM). The leakage data were subjected to ANOVA test, followed by Tukey's t-test (α = 5%). Groups 2, 3 and 4 showed less dye penetration than the control group (p < 0.05), but were similar among each other. SEM images showed that dentinal tubules were open in G1, and fused and occluded in G2. Group 3 showed dentinal tubules that were occluded by the metal ions from the toothpaste. G4 presented similar characteristics to G3, and the presence of fused dentin. The diode laser and the dentifrice were effective in reducing dentinal permeability, and the combination of the two treatments did not show better results than either one used alone.

A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT): Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization

Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT): such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980 nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy) combined with hydrogen peroxide, comparing a pulsed diode laser (LI) activity to a high-frequency superpulsed diode laser (LII). Materials and Methods. Primary fibroblasts and keratinocytes cell lines, isolated from human dermis, were irradiated every 48 h for 10 days using LI and LII combined with SiOxyL(+) ™ Solution (hydrogen peroxide (HP) stabilized with a glycerol phosphate complex). Two days after the last irradiation, the treated cultures were analyzed by flow cytofluorometry (FACS) and western blotting to quantify keratin 5 and keratin 8 with monoclonal antibodies reactive to cytokeratin 5 and cytokeratin 8. Antimicrobial activity was also evaluated. Results. Both experimental models show the superiority of LII against LI. In parallel, stabilized HP provided better results in the regeneration test in respect to common HP, while the biocidal activity remains comparable. Conclusion. The use of high-frequency lasers combined with stabilized hydrogen peroxide can provide optimal results for a substantial decrease of bacterial count combined with a maximal biostimulation induction of soft tissues and osteogenesis.

Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

BACKGROUND

The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching.

MATERIAL AND METHODS

The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05).

RESULTS

A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching.

CONCLUSIONS

The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material.

KEY WORDS

Laser, diode, dentin, tubule, diameter.

Comparative Morphologic Evaluation and Occluding Effectiveness of Nd: YAG, CO2 and Diode Lasers on Exposed Human Dentinal Tubules: An Invitro SEM Study

INTRODUCTION

Dentinal hypersensitivity is one of the most common problem, encountered in dental practice but has least predictable treatment outcome. The advent of lasers in dentistry has provided an additional therapeutic option for treating dentinal hypersensitivity. Although various lasers have been tried over a period of time to treat dentinal hypersensitivity, but still the doubt persist as to which laser leads to maximum dentinal tubular occlusion and is most suitable with minimal hazardous effects.

AIM

To compare the effects of Nd: YAG, CO2 and 810-nm diode lasers on width of exposed dentinal tubule orifices and to evaluate the morphologic changes on dentinal surface of human tooth after laser irradiation by scanning electron microscope (SEM).

MATERIALS AND METHODS

Forty root specimens were obtained from ten freshly extracted human premolars, which were randomly divided into four groups of ten each. Group I: control group treated with only saline, Group II: Nd:YAG laser, Group III: CO2 laser and Group IV: 810-nm diode laser. The specimens were examined using SEM. After calculating mean tubular diameter for each group, the values were compared statistically using parametric one-way ANOVA test and Turkey's post hoc multiple comparison test.

RESULTS

All the three lased groups showed a highly statistical significant result with p-value of <0.001 as compared to non-lased group. On intergroup comparison within the lased groups, all the three groups showed statistically significant difference in the reduction of dentinal tubular diameter (p-value < 0.001).

CONCLUSION

Nd: YAG laser was found to be most effective, followed by the CO2 laser and 810-nm diode laser was found to be least effective. The morphologic changes like craters, cracks and charring effect of the dentine were seen maximum by the use of CO2 laser.

Safety Irradiation Parameters of Nd:YAP Laser Beam for Endodontic Treatments: An In Vitro Study

Objective. Nd:YAP laser has several potentialities of clinical applications in endodontics. The aim of our study is to determine the safety range of irradiation parameters during endodontic application of Nd:YAP laser that can be used without damaging and overheating the periodontal tissue. Material and Methods. Twenty-seven caries-free single-rooted extracted human teeth were used. Crowns were sectioned to obtain 11 mm root canal length. Temperature increases at root surfaces were measured by a thermocouple during Nd:YAP laser irradiation of root canals at different energy densities. Canal irradiation was accomplished with a circular and retrograde movement from the apex until the cervical part of the canal during 10 seconds with an axial speed of 1 mm/s. Each irradiation was done in a canal irrigated continuously with 2.25% NaOCl solution. Results. Periodontal temperature increase depends on the value of energy density. Means and standard deviations of temperature increases at root surfaces were below 10°C (safe threshold level) when the average energy densities delivered per second were equal to or below 4981 J/cm² and 9554 J/cm², respectively, for irradiations using a fiber diameter of 320 μm and 200 μm. Conclusions. Within the limitations of this study and under specific irradiation conditions, Nd:YAP laser beam may be considered harmless for periodontal tissues during endodontic applications.

Laser-assisted treatment of dentinal hypersensitivity: a literature review

The purpose of this literature review was to evaluate the effectiveness of the laser-assisted treatment of dentinal hypersensitivity. A review with inclusion and exclusion criteria was performed from January 2009 to December 2014 with electronic data-bases: MedLine via PubMed, Science Direct and Cochrane Library. Research of paper magazines by hand was not considered. Forty-three articles were selected between literature reviews, in vitro studies, clinical trials, pilot and preliminary studies. The items were divided into laser-used groups for an accurate description, and then the reading of results into various typologies. Laser-assisted treatment reduces dentinal hypersensitivity-related pain, but also a psychosomatic component must be considered, so further studies and more suitable follow-ups are necessary.

In Vitro Evaluation of Dentin Hydraulic Conductance After 980 nm Diode Laser Irradiation

BACKGROUND

Dentin hypersensitivity treatments are based on the physical obliteration of the dentinal tubules to reduce hydraulic conductance. The aim of the present study is to evaluate the hydraulic conductance of bovine root dentin after irradiation with a 980-nm diode laser, with or without associated fluoride varnish.

METHODS

Sixty bovine root dentin specimens were divided into six groups (n = 10 in each group): G1, G3, and G5 (0.5 W, 0.7 W, and 1 W diode laser, respectively); G2, G4, and G6 (fluoride varnish application + 0.5 W, 0.7 W, and 1 W diode laser, respectively). The dentin hydraulic conductance was evaluated at four time periods with a fluxmeter: 1) with smear layer, 2) after 37% phosphoric acid etching, 3) after the treatments, and 4) after 6% citric acid challenge. After the dentinal fluid flow measurements, specimens were also evaluated for mineral composition using energy dispersive X-ray spectroscopy (EDS).

RESULTS

Analysis demonstrated a better result with increased irradiation power (P < 0.001), especially if the diode laser irradiation was associated with the application of fluoride varnish (P < 0.001), ensuring a greater reduction in permeability. Considering the groups treated only with laser irradiation, the 1 W group was superior when compared with the 0.5 W and 0.7 W irradiated groups immediately after treatment (P < 0.001). After citric acid testing, all groups showed similar results, except when comparing the 1 W groups with the 0.5 W groups (P = 0.04). EDS results of the irradiated groups showed an increase in the proportion of calcium and phosphorus ions, which demonstrates a superficial composition modification after laser treatments.

CONCLUSION

Laser irradiation of exposed dentin promoted significant reduction in the dentin hydraulic conductance, mainly with higher energy densities and association with fluoride varnish.

Treatment of dentinal hypersensitivity by means of Nd:YAP Laser: a preliminary in vitro study

Objective. The aim of this study is to evaluate the effectiveness of Nd:YAP laser to seal dentinal tubules at different parameters. Material and Methods. 24 caries-free human wisdom impacted molars were used. The crowns were sectioned transversally in order to totally expose the dentin. The smear layer was removed by a 1 min application of EDTA. Each surface was divided into four quadrants, but only three quadrants were irradiated at a different output power setting (irradiation speed: 1 mm/sec; optical fiber diameter: 320 µm; tangential incidence of beam and in noncontact mode). Samples were smeared with a graphite paste prior to laser irradiation. All specimens were sent for SEM analysis. Pulp temperature increases in additional twenty teeth were measured by a thermocouple. Results. Morphological changes in dentin surfaces depend on the value of used energy density. Higher energy densities (2 W–4 W; 200–400 mJ; pulse duration: 100 m sec.; and 10 Hz) induce higher dentin modifications. Our results confirmed that Nd:YAP laser irradiations can lead to total or partial occlusion of dentin tubules without provoking fissures or cracks. Measurements of pulp temperature increases showed that Nd:YAP laser beam can be considered as harmless for pulp vitality for following irradiation conditions: 2 W (200 mJ) to 4 W (400 mJ) with an irradiation speed of 1 mm/sec; fiber diameter: 320 micrometers; 10 Hz; pulse duration: 100 m sec; noncontact mode and in tangential incidence to exposed dentin. The perpendicular incidence of the laser beam on exposed dentin may injure pulp vitality even at low output power of 3 W. Conclusions. Nd:YAP laser beam was able to seal the dentin tubules without damaging dentinal surfaces and without harming pulp vitality. Nd:YAP laser is effective and may be safely used for future in vivo treatments of dentinal hypersensitivity under certain conditions.