A novel blue light laser system for surgical applications in dentistry: evaluation of specific laser-tissue interactions in monolayer cultures

Thermal Effects on Dental Pulp during Laser-Assisted Bleaching Procedures with Diode Lasers in a Clinical Study

Background In the current cosmetics industry, bleaching is often associated with lasers. However, such treatment also harbors risks. Tooth death is observed at pulpal temperature increases ≥5.6 °C. Therefore, it seems important to investigate the effects of using different lasers. The aim of this study was to determine pulpal temperature increases at different laser parameters during bleaching by modeling a realistic environment and to compare the temperature recording using a thermocouple and thermal camera. The authors assumed that there are laser settings for the lasers used at which the pulpal temperature increases are <5.6 °C and that the temperature recordings with thermocouples and thermal cameras differ only minimally. Methods Human teeth were used, which were extracted for dental reasons. During experiment, teeth were bleached conventionally and by laser activation at 940 nm, 445 nm, and 970 nm. The temperature in the pulp was recorded using thermocouples. In a second setup, longitudinally halved teeth were bleached, while the temperature in the pulp was recorded with a thermocouple and thermal camera. Descriptive statistics were used. The significance level is 0.05. Results In addition to conventional bleaching, temperature increases <5.6 °C were observed for bleaching at 940 nm 1.5 W, at 445 nm 0.3 W, and at 970 nm 0.5 W. For bleaching procedures using 940 nm 7 W, 940 nm 2 W, 445 nm 0.5 W, and 970 nm 1 W, the temperature increase was ≥5.6 °C. Significant differences (p < 0.05) were found in the maximum temperature increases (°C) between all groups. Temperature recordings using a thermocouple and thermal camera differed by about 2.3 °C. The working hypotheses were confirmed. Conclusion With laser bleaching, attention must be paid to the type of laser, its power, and the time in order to avoid excessive overheating of the dental pulp.

Diode Laser Frenectomy: A Torch of Freedom for Ankyloglossia

Ankyloglossia, also known as tongue-tie, is a rare congenital anomaly of the oral cavity that not only causes difficulties in breastfeeding and teeth cleaning but also causes difficulty in speech articulation. Our patient faced difficulty in freely moving his tongue because of the short lingual frenulum wherein laser lingual frenectomy was indicated. The patient was treated successfully with a soft tissue diode laser having a wavelength of 445 nanometers. The use of a low-wavelength diode laser becomes relatively complimentary to standard scalpel surgery because of patient consolation, offers a blood-free area, reduces inflammation and edema, and is less damaging to thermal tissues.

Conventional vs. diode laser stapedotomy: audiological outcomes and clinical safety

PURPOSE

To compare the hearing results and clinical safety of patients undergoing stapes surgery with conventional technique and diode laser.

METHODS

Retrospective observational study, which included patients treated with primary stapes surgery performed between January 2009 and January 2020. Three audiometric measurements (PTA, GAP and SDS) were evaluated as main results, evaluated by analysis of covariance (controlling the preoperative value). Intraoperative and postoperative complications were also analyzed. Outcomes were measured 6 months (± 1 month) after surgery.

RESULTS

153 cases were included, 97 operated with conventional technique and 56 with laser technique. Postoperative GAP ≤ 10 dB was obtained in 85.6% of the total sample, 82.5% in the conventional technique and 91.1% in the laser technique. Analysis of covariance showed no significant differences in the three surgery outcomes between the two groups (PTA, p = 0.277; GAP, p = 0.509 and SDS, p = 0.530). Regarding surgical complications, sensorineural damage was higher in the conventional technique group (p = 0.05). On the other hand, there were four cases of facial paresis, all in the laser group, three of them with the 980 nm laser.

CONCLUSIONS

Stapedotomy offered a high percentage of hearing success in the two groups studied. There were no significant differences in audiometric result, but there was a differential presentation of complications, being more frequent sensorineural hearing loss in the conventional technique group and facial paresis in the laser group.

Wound healing after therapy of oral potentially malignant disorders with a 445-nm semiconductor laser: a randomized clinical trial

OBJECTIVES

Oral potentially malignant disorders (OPMDs) are the most clinically relevant precursor lesions of the oral squamous cell carcinoma (OSCC). OSCC is one of the 15 most common cancers worldwide. OSCC is with its high rate of mortality an important cause of death worldwide. The diagnosis and therapy of clinically relevant precursor lesions of the OSCC is one of the main parts of prevention of this malignant disease. Targeted therapy is one of the main challenges concerning an oncologically safe tissue removal without overwhelming functional and aesthetic impairment.

MATERIALS AND METHODS

In this randomized controlled trial, a newly introduced intraoral 445-nm semiconductor laser (2W; cw-mode; SIROLaser Blue, Dentsply Sirona, Bensheim, Germany) was used in the therapy of OPMDs. Duration and course of wound healing, pain, and scar tissue formation were compared to classical cold blade removal with primary suture by measuring remaining wound area, tissue colorimetry, and visual analogue scale. The study includes 40 patients randomized using a random spreadsheet sequence in two groups (n1 = 20; n2 = 20).

RESULTS

This comparative analysis revealed a significantly reduced remaining wound area after 1, 2, and 4 weeks in the laser group compared to the cold blade group (p < 0.05). In the laser group, a significantly reduced postoperative pain after 1 week was measured (p < 0.05).

CONCLUSION

Laser coagulation of OPMDs with the investigated 445-nm semiconductor laser is a safe, gentle, and predictable surgical procedure with beneficial wound healing and reduced postoperative discomfort.

CLINICAL RELEVANCE

Compared to the more invasive and bloody cold blade removal with scalpel, the 445-nm semiconductor laser could be a new functional less traumatic tool in the therapy of OPMDs. The method should be further investigated with regard to the identification of further possible indications.

TRAIL REGISTRATION

German Clinical Trials Register No: DRKS00032626.

The Safety and Efficacy of the 445-nm Blue Laser for Operative Management of Benign Nonvascular Laryngeal Lesions

The 445-nm blue laser combines the features of photocoagulative vascular lasers and cutting lasers in one device. The purpose of the present study was to evaluate the safety and efficacy of the 445-nm blue laser for the treatment of benign laryngeal pathologies, other than vascular lesions. Outcomes were compared to those when already-established therapies were used.

METHODS

Adult voice center patients who underwent surgical intervention for vocal fold (VF) mass, VF scar, laryngeal stenosis, laryngeal web, or Reinke's edema were included in this retrospective study. Outcomes were compared to those achieved when traditional treatment modalities were used, including cold steel, CO2 laser, potassium-titanyl-phosphate (KTP) laser, and coblator. Strobovideolaryngoscopy footage was evaluated using a previously described model at four time points: postoperative visit #1: 1-14 days, postoperative visit #2: 30-60 days, postoperative visit #3: 61-365 days, postoperative visit #4: >365 days.

RESULTS

Eighty cases using the blue laser and 153 controls (n = 78 cold steel, n = 51 KTP laser, n = 22 CO2 laser, n = 2 coblator) were included in this study. Procedures performed using blue laser included VF mass excision (n = 45), VF scar reduction (n = 16), laryngeal stenosis resection/repair (n = 25), laryngeal web excision (n = 7), and reduction of Reinke's edema (n = 1). On postoperative strobovideolaryngoscopy examination, the surgical objective score did not differ significantly between the blue laser cohort and all controls at any postoperative visit. VF edema did not differ significantly between the blue laser cohort and all controls at any postoperative visit. VF hemorrhage scores were significantly lower in the blue laser cohort compared to all controls at the first postoperative visit, but hemorrhage had resolved almost entirely by the second postoperative visit in all groups. Postoperative VF stiffness was worse in the blue laser group at the third postoperative visit compared to controls, but both groups had improved to similar levels by the fourth postoperative visit. The rate of lesion recurrence (24.29% versus 17.19%) did not differ significantly between the blue laser cohort and controls on multivariate analysis (Odds ratio [OR] = 1.081 [0.461-2.536]). The complication rate (12.50% versus 10.46%) did not differ significantly between the blue laser cohort and all controls on multivariate analysis (OR = 0.992 [0.375-2.624]). The blue laser was associated with a lower rate of revision surgery (30.00% versus 34.64%) on multivariate analysis (OR = 0.380 [0.168-0.859]).

CONCLUSION

The 445-nm blue laser is safe and effective for the management of benign laryngeal lesions. It has efficacy and safety similar to those of traditional treatment modalities (including cold steel, CO2 laser, and KTP laser). Use of the blue laser may lead to lower rates of early postoperative hemorrhage and revision surgery. No adverse effects attributed directly to the use of the blue laser were observed in this study. Further research is encouraged to confirm or refute these findings.

Temperature changes in the pulp chamber and bleaching gel during tooth bleaching assisted by diode laser (445 nm) using different power settings

The aim of this in vitro study was to investigate the safety of using blue diode laser (445 nm) for tooth bleaching with regard to intrapulpal temperature increase operating at different average power and time settings. Fifty human mandibular incisors (n = 10) were used for evaluating temperature rise inside the pulp chamber and in the bleaching gel during laser-assisted tooth bleaching. The change in temperature was recorded using K thermocouples for the five experimental groups (without laser, 0.5, 1, 1.5 and 2 W) at each point of time (0, 10, 20, 30, 40, 50 and 60 s). As the average power of the diode laser increases, the temperature inside the pulp chamber also increases and that of the bleaching gel was significantly higher in all the experimental groups (p < 0.05). However, the intrapulpal temperature rise was below the threshold for irreversible thermal damage of the pulp (5.6 °C). Average power of a diode laser (445 nm) ranging between 0.5-2 W and irradiation time between 10-60 s should be considered safe regarding the pulp health when a red-colored bleaching gel is used. Clinical studies should confirm the safety and effectiveness of such tooth bleaching treatments. The outcomes of the present study could be a useful guide for dental clinicians, who utilize diode lasers (445 nm) for in-office tooth bleaching treatments in order to select appropriate power parameters and duration of laser irradiation without jeopardizing the safety of the pulp.

Un-sedated Office-Based Application of Blue Laser in Vocal Fold Lesions

INTRODUCTION

Office-based laser procedures in laryngology have gained a lot of popularity in the last decade with the use of the KTP, PDL and Thulium lasers. Preliminary investigations currently report on the use of the 445 nm wavelength Blue laser for the treatment of various laryngeal pathologies, given its dual photoangiolytic and cutting properties.

OBJECTIVE

We aim to investigate the safety and efficacy of the Blue laser for the treatment of vocal fold lesions.

METHODS

This is a retrospective chart review of eleven patients with a variety of vocal fold lesions (polyps, Reinke's edema, papilloma, and leukoplakia), that underwent un-sedated office-based treatment using the 445 nm blue laser. The primary outcome was to compare preoperative to postoperative Voice Handicap Index (VHI-10) score and self-reported voice improvement using a visual analog scale (VAS). We also compared fiberoptic laryngeal examination before and after treatment.

RESULTS

Eleven un-sedated office-based procedures using the blue laser were performed. There was improvement in the mean VHI-10 score (n = 8) with a decrease from 15.13 ± 8.77 to 3.50 ± 3.46 (P= 0.015). Similarly, the mean VAS score (n = 7) decreased from 6.14 ± 1.21 to 1.71 ± 1.60 (P< 0.003). All patients had a complete or partial regression of the vocal fold lesions on fiberoptic laryngeal examination. None of the patients had complications after the procedure.

CONCLUSION

Blue laser therapy can be suggested as a safe and effective alternative treatment modality in office-based laryngology procedures for a variety of vocal fold lesions. A larger series is needed to better validate the efficacy of this laser as a new treatment modality.

Thermal Effects of 445-nm Diode Laser Irradiation on Titanium and Ceramic Implants

This study aimed to evaluate temperature changes in titanium and ceramic implants after using a 445-nm diode laser under different in vitro conditions. Titanium (Ti) and ceramic (Zr) dental implants were placed into a bone analog, and an intrabony defect was created at each implant. A 445-nm diode laser was used to irradiate the defects for 30 seconds, noncontact, at 2 W in continuous wave (c.w.) and pulsed mode. The experiment was done at room temperature (21.0 ± 1°C) and in a water bath (37.0 ± 1°C). Two thermocouple probes were used to record real-time temperature changes (°C) at the coronal part of the implant (Tc) and the apex (Ta). The temperature was recorded at time 0 (To) and after 30 seconds of irradiation (Tf). The average temperature change was calculated, and a descriptive analysis was conducted (P < .05). The Ti implant resulted in the highest ΔT values coronally (29.6°C) and apically (6.7°C) using continuous wave at 21°C. The Zr implant increased to 26.4°C coronally and 5.2°C apically. In the water bath, the coronal portion of the Ti and Zr implants rose to 14.2°C and 14.01°C, respectively, using continuous waves. The ΔT values for Ti were 11.9°C coronally and 1.7°C apically when placed in a water bath using pulsed mode. The lowest ΔT occurred on the Zr implant with ΔTc and ΔTa of 4.8°C and 0.78°C, respectively. Under in vitro conditions, the 445-nm diode laser in pulsed mode seems to be safe for use on ceramic implants and should be used with caution on titanium implants.

SEM Evaluation of Thermal Effects Produced by a 445 nm Laser on Implant Surfaces

The aim of this in vitro study was to evaluate thermal effects on implant surfaces using a 445 nm diode laser (Eltech K-Laser Srl, Treviso, Italy) with different power settings and irradiation modalities. Fifteen new implants (Straumann, Basel, Switzerland) were irradiated to evaluate surface alteration. Each implant was divided into two zones: the anterior and posterior areas. The anterior coronal areas were irradiated with a distance of 1 mm between the optical fiber and the implant; the anterior apical ones were irradiated with the fiber in contact with the implant. Instead, the posterior surfaces of all of the implants were not irradiated and used as control surfaces. The protocol comprised two cycles of laser irradiation, lasting 30 s each, with a one-minute pause between them. Different power settings were tested: a 0.5 W pulsed beam (T-on 25 ms; T-off 25 ms), a 2 W continuous beam and a 3 W continuous beam. Lastly, through a scanning electron microscopy (SEM) analysis, dental implants' surfaces were evaluated to investigate surface alterations. No surface alterations were detected using a 0.5 W laser beam with a pulsed mode at a distance of 1 mm. Using powers of irradiation of 2 W and 3 W with a continuous mode at 1 mm from the implant caused damage on the titanium surfaces. After the irradiation protocol was changed to using the fiber in contact with the implant, the surface alterations increased highly compared to the non-contact irradiation modality. The SEM results suggest that a power of irradiation of 0.5 W with a pulsed laser light emission mode, using an inactivated optical fiber placed 1 mm away from the implant, could be used in the treatment of peri-implantitis, since no implant surface alterations were detected.

Use of lasers in gastrointestinal endoscopy: a review of the literature

Lasers emit highly directional light with consistent wavelengths, and recent studies have demonstrated their successful applications in gastrointestinal endoscopic therapy. Although argon plasma coagulators (APC) became the preferred treatment option due to improved safety profile and lower costs, advancements in laser and optic fiber manufacturing have reignited interest in laser treatment. Different laser wavelengths have distinct features and applications based on their tissue absorption coefficient. Lasers with shorter wavelengths are effectively absorbed by hemoglobin, resulting in a good coagulation effect. Near-infrared lasers have ability to ablate solid tumors, while far-infrared lasers can make precise mucosal incisions without causing peripheral thermal damage. Lasers have proven to be highly applicable to endoscopy devices such as endoscopes, endoscopic ultrasound (EUS), double-balloon enteroscopes (DBE), and endoscopic retrograde cholangiopancreatography (ERCP), making them a potent tool to enhance the effectiveness of endoscopic treatments with minimal adverse events. This review aims to help readers understand the applications and effectiveness of lasers in gastrointestinal endoscopy, with the potential to promote the development and application of laser technology in the medical field.

Treatment of Gingival Growth Due to Amlodipine Use With a 445-nm Diode Laser: A Case Report

Amlodipine is a widely used calcium channel blocker associated with gingival enlargement. The effects of amlodipine on gingival enlargement vary depending on the duration of drug use and the dose of the active substance. This report presents a 56-year-old male hypertensive patient who had been using amlodipine (5 mg/day orally, single dose) for the last two years. He presented with diffuse gingival enlargement, complaining of gingival swelling and bleeding. This case report demonstrates the treatment of gingival enlargement with a novel 445-nanometer (nm) blue light diode laser after drug change and oral hygiene, which resulted in permanent and satisfactory clinical results.

Surgical Outcome of Low-Power-Density Blue Laser for Vascular Lesions of the Vocal Fold

Photoangiolytic lasers such as the 532-nm potassium-titanyl-phosphate (KTP) and the novel 445-nm blue laser (introduced into the United States in 2020) are absorbed selectively by hemoglobin, permitting targeted ablation of vascular structures such as vascular malformations of the vocal fold (VF). Previously, we reported the high rate of success of KTP laser photocoagulation for VF vascular lesions. Compared with other photoangiolytic lasers, blue laser has the highest absorption in hemoglobin, and therefore it can be operated at lower power densities to minimize thermal injury to adjacent tissue.

OBJECTIVE

The purpose of this study was to determine the efficacy and safety of blue laser for treatment of VF vascular lesions using low power densities, and to compare outcomes of blue laser with those of KTP laser.

METHODS

Adult voice patients who underwent blue laser treatment of VF vascular lesions in the operating room at the lowest power densities that appeared clinically to cause the effect desired were included in this retrospective study. Baseline lesion characteristics and postoperative outcomes were assessed with a model that we had described previously. Postoperative outcomes were compared to those of previously reported KTP laser.

RESULTS

Thirty-one subjects (54 VFs treated) underwent blue laser vaporization of VF vascular lesions (average age was 40.63 ± 17.51). Data were compared to those of 66 subjects (100 VFs) who had undergone KTP laser vaporization of VF vascular lesions. There were no significant differences in subject demographics, past medical or surgical history, or preoperative location or severity of vascular lesions. Surgical success for blue laser at the low power densities used was 3.74 ± 0.50, 3.55 ± 0.94, 3.90 ± 0.94, and 3.70 ± 1.11 (out of 5) at postoperative visits 1-4, respectively. Surgical objective score was significantly greater following KTP laser at every postoperative visit. Treatment with KTP laser resulted in significantly greater generalized postoperative edema, and blue laser resulted in significantly greater localized edema at postoperative visits one and two. At visit three and four, there are no significant differences. VF stiffness following blue laser was 2.41 ± 0.67, 1.91 ± 0.69, 1.33 ± 0.47, and 1.10 ± 0.18 (out of 4) at postoperative visits 1-4, respectively. Postoperative VF stiffness did not differ significantly from KTP laser. Postoperative hemorrhage severity after blue laser was 1.79 ± 0.54, 1.59 ± 0.48, 1.15 ± 0.25, and 1.14 ± 0.26 (out of 4) at postoperative visits 1-4, respectively. Blue laser resulted in significantly less VF hemorrhage than KTP laser at the first (1.79 ± 0.54 versus 2.26 ± 0.83) and second (1.59 ± 0.48 versus 1.98 ± 0.72) postoperative visits. Vascular lesions treated with low-power-density blue laser were significantly more likely to recur than those treated with KTP laser (40.74% versus 10.00%). New vascular malformations were significantly more likely to form after blue laser than KTP (24.07% versus 6.00%). Subjects treated with low-power-density blue laser were significantly more likely to undergo repeat surgery than those treated with KTP (31.48% versus 14.00%). Significant predictors for the need for repeat blue laser included lesion recurrence, a lower surgical objective score at the third or fourth postoperative visit and a higher baseline lesion severity grade.

CONCLUSION

Blue laser is an effective tool for the surgical management of VF vascular lesions. Although overall surgical success ratings were inferior to KTP laser at the power densities used, the severity of postoperative edema and VF hemorrhage were significantly less with blue laser. Re-evaluation of blue laser using higher power densities is in progress.

Quantitative investigation of laser ablation based on real-time temperature variations and OCT images for laser treatment applications

BACKGROUND AND OBJECTIVE

Lasers are widely employed in clinical applications. In vivo monitoring of real-time information about different-wavelength laser surgeries would provide important surgical feedback for surgeons or clinical therapy instruments. However, the quantitative effect of laser ablation or vaporization still needs to be further explored and investigated. Here, we investigate and quantitatively evaluate the ablation variations and morphological changes of two laser ablation models: point- and sweeping-based models.

METHODS

An infrared thermal imager was used to monitor the temperature variations, and curve fitting was used to build the relationship between the laser radiation duration/sweeping speed and quantitative parameters of the ablated areas. Optical coherence tomography (OCT) images were used to visualize the inner structure and evaluate the depth of the ablated craters. Optical attenuation coefficients (OACs) were computed to characterize the normal and ablated tissues.

RESULTS

The results demonstrated that there was a good linear relationship between radiation duration and temperature variation. Similarly, a linear relationship was observed between the sweeping speed and quantitative parameters of craters or scratches (width and depth). The mean OAC of normal tissues was significantly distinguished from the mean OACs of the ablated craters or scratches.

CONCLUSION

Laser ablation was investigated based on a quantitative parameter analysis, thermal detection, and OCT imaging, and the results successfully demonstrated that there is a linear relationship between the laser parameters and quantitative parameters of the ablated tissues under the current settings. Such technology could be used to provide quantitative solutions for exploring the laser-tissue biological effect and improve the performance of medical image-guided laser ablation in the future.

Use of Blue and Blue-Violet Lasers in Dentistry: A Narrative Review

Introduction: Blue and blue-violet diode lasers (450 and 405 nm) seem to represent an interesting approach for several clinical treatments today. The aim of this narrative review is to describe and comment on the literature regarding the utilization of blue and blue-violet lasers in dentistry. Methods: A search for "blue laser AND dentistry" was conducted using the PubMed database, and all the papers referring to this topic, ranging from 1990 to April 2020, were analyzed in the review. All the original in vivo and in vitro studies using 450 nm or 405 nm lasers were included in this study. All the articles on the LED light, laser wavelengths other than 405 and 450 nm and using lasers in specialties other than dentistry, as well as case reports, guideline papers and reviews were excluded. Results: From a total of 519 results, 47 articles met the inclusion criteria and were divided into 8 groups based on their fields of application: disinfection (10), photobiomodulation (PBM) (4), bleaching (1), resin curing (20), surgery (7), periodontics (1), endodontics (1) and orthodontics (3). Conclusion: Blue and blue-violet diode lasers may represent new and effective devices to be used in a large number of applications in dentistry, even if further studies will be necessary to fully clarify the potentialities of these laser wavelengths.

Assessment of the Photobiomodulation Effect of a Blue Diode Laser on the Proliferation and Migration of Cultured Human Gingival Fibroblast Cells: A Preliminary In Vitro Study

Introduction: Photobiomodulation therapy (PBM) is emerging as an effective strategy for the management of wound healing. The application of red and near infra-red light sources in laser therapy has been the subject of most researches in recent literature. Considering the lack of sufficient evidence in assessing the blue light in PBM, we aimed to investigate the photobiomodulation effect of a blue diode laser on the proliferation and migration of cultured human gingival fibroblast cells as a preliminary in vitro study. Methods: Human gingival fibroblast cells were irradiated with a blue diode laser at a 445 nm wavelength. Irradiation was done using three different powers of 200 mW (irradiation times of 5, 10,15, and 20 seconds); 300 mW (irradiation times of 5, 10, and 15 seconds); and 400 mW (irradiation times of 5 and 10 seconds). The fibroblast cells without laser exposure were considered as control. After 24 hours of incubation, the MTT assay and the wound scratch test were performed on the cells to investigate the biomodulation effect of the blue laser on the proliferation and migration of the cells respectively. The results were analyzed by one-way ANOVA and a post-hoc Tukey test with a P value <0.05 as a statistical significance level. Results: PBM with blue diode laser at power densities of 400 mW/cm² with irradiation times of 10 and 15 seconds corresponding to energy densities of 4 and 6 J/cm² exerted the statistically significant positive effect on both proliferation and migration of gingival fibroblast cells. Conclusion: Considering the encouraging findings of this study, PBM with blue diode laser can promote proliferation and migration of human gingival fibroblasts, the key cells involved in the process of oral wound healing.

[Photoangiolytic Lasers in Laryngology]

With photoangiolytic lasers like KTP (Potassium-Titanyl-Phosphate, 532 nm) lasers or the new "blue" laser (445 nm), even the smallest vessels and capillaries within the vocal fold can be treated without destroying the covering epithelium. This enables effective treatment of benign and malignant sub- and intraepithelial lesions of the vocal folds such as papilloma, edema, polyps, leukoplakia, dysplasia and capillary vessels while preserving the vibratory properties of the different layers of the lamina propria. Because photoangiolytic laser light can be routed through tiny glass fibers, office-based surgery with channelled flexible endoscopes are feasible as well as phonomicrosurgical operations under general anesthesia. Furthermore, the so called "blue" laser can cut tissues and thus broadens the technical armamentarium of the phonosurgeon.

A Single Case Report of Granular Cell Tumor of the Tongue Successfully Treated through 445 nm Diode Laser

Oral granular cell tumor (GCT) is a relatively rare, benign lesion that can easily be misdiagnosed. Particularly, the presence of pseudoepitheliomatous hyperplasia might, in some cases, lead to the hypothesis of squamous cell carcinoma. Surgical excision is the treatment of choice. Recurrence has been reported in up to 15% of cases treated with conventional surgery. Here, we reported a case of GCT of the tongue in a young female patient, which was successfully treated through 445 nm diode laser excision. Laser surgery might reduce bleeding and postoperative pain and may be associated with more rapid healing. Particularly, the vaporization effect on remnant tissues could eliminate GCT cells on the surgical bed, thus hypothetically leading to a lower rate of recurrence. In the present case, complete healing occurred in 1 week, and no recurrence was observed after 6 months. Laser surgery also allows the possibility to obtain second intention healing. Possible laser-induced histopathological artifacts should be carefully considered.

Histological Effects of an Innovative 445 Nm Blue Laser During Oral Soft Tissue Biopsy

Continuously evolving laser devices can be used in various fields; they are an alternative to the traditional cold blade surgery to perform biopsies of oral soft tissues. The aspect focused on in this paper is the possibility to use the 445 nm diode laser (Eltech K-Laser srl, Treviso, Italy) in complete safety, by evaluating its thermal effects during microscopy. A histological evaluation of the alteration of the peri-incisional edges on 10 samples was realized. All excisional biopsies were related to clinically unsuspected lesions and performed by the same expert operator. The surgical procedure was performed with the same laser parameters and the same pathologist evaluated the thermal effect on the samples. An average value of the detected tissue alteration was calculated; the average damage of the epithelium was 650.93 μm, while in the connective tissue it was 468.07 μm. In all the cases a clear diagnosis was possible, and no clinical complications were observed; so, the 445 nm diode laser proved to be a device that can be safely used for biopsies of clinically unsuspicious lesions. Due to the small number of cases, this in vivo preliminary experience needs to be extended.

Comparison of the effect of photodynamic therapy with curcumin and methylene Blue on streptococcus mutans bacterial colonies

BACKGROUND AND AIM

Streptococcus mutans (S. mutans) is a bacterium that colonizes in the mouth and is a common cause of dental caries and periodontal diseases. This bacterium comprises 70% of the bacteria in the dental plaque. Although tooth decay is a multifactorial complication, S. mutans biofilms are the main cause of cavitated carious lesions. Considering the importance of this microorganism, we aimed at investigating the effect of photodynamic therapy (PDT) using curcumin (CUR) and methylene blue (MB) photosensitizers on S. mutans.

MATERIALS AND METHODS

In this in-vitro experimental study, first, samples of S. mutans were prepared in 110 test tubes and were randomly assigned to 11 groups after colony counting: 1) Positive control group, 2) Negative control group, 3) CUR extract group, 4) 460-nm laser group, 5) 460-nm continuous laser + CUR group, 6) 460-nm discontinues 50% duty cycle (DC) laser + CUR group, 7) 660-nm laser group, 8) 660-nm laser + MB group, 9) MB group, 10) dental light-curing group, and 11) chlorhexidine (CHX) group. After the intervention, cultivation was performed again in blood agar medium, and the bacterial colony-forming units per milliliter (CFU/ml) were counted again. Data were analyzed using analysis of variance (ANOVA) and Tukey's test.

RESULTS

CHX and 460-nm low-level continuous laser + CUR had the highest and most significant effect on inhibiting the growth of S. mutans bacterial colonies and showed significant differences with other groups (P < 0.001).

CONCLUSION

According to the results, MB- and CUR-mediated PDT can significantly eradicate S. mutans colonies.

The Impacts of Low-Level Laser Therapy - A Complementary Treatment in the Management of Side Effects After Implant Surgery

Introduction: One of the most important medical applications of laser is low-level laser therapy (LLLT). In this method, laser radiation penetrates easily into the target tissue. The aim of this study was to investigate whether LLLT can reduce the side effects of advanced implant surgery. Methods: In this triple-blind clinical trial, 30 patients aged 25 to 65 years were selected for implant insertion and divided into two groups. In the laser group, immediately after the surgery, 72 hours and 1 week after the surgery, the surgical site was irradiated with an 830 nm laser. The dose required for the laser therapy was 5 J/cm² . The degree of pain, facial swelling and wound healing were analyzed using statistical methods. Results: Our results showed that at 12, 24, 48, and 72 hours after the surgery, the pain level was reduced in the laser group compared with the placebo group (P<0.05). Swelling of the face was also significantly reduced 7 days after surgery in the laser group (P<0.05). The investigation on the recovery conditions of the surgical site showed that on the 3rd, 7th and 14th days after the surgery, higher levels of wound healing have been achieved (P<0.05). Conclusion: Our results suggest that laser, as a complementary therapy; can be used to reduce the severity and duration of pain. Also, laser can reduce facial swelling and accelerate wound healing.

Effectiveness of photopolymerization in composite resins using a novel 445-nm diode laser in comparison to LED and halogen bulb technology

Challenges especially in the minimal invasive restorative treatment of teeth require further developments of composite polymerization techniques. These include, among others, the securing of a complete polymerization with moderate thermal stress for the pulp. The aim of this study is to compare current light curing sources with a blue diode laser regarding curing depth and heat generation during the polymerization process. A diode laser (445 nm), a LED, and a halogen lamp were used for polymerizing composite resins. The curing depth was determined according to the norm ISO 4049. Laser output powers of 0.1, 0.5, 1, and 2 W were chosen. The laser beam diameter was adapted to the glass rod of the LED and the halogen lamp (8 mm). The irradiation time was fixed at 40 s. To ascertain ΔT values, the surface and ground area temperatures of the cavities were simultaneously determined during the curing via a thermography camera and a thermocouple. The curing depths for the LED (3.3 mm), halogen lamp (3.1 mm) and laser_{(0.5/1 W)} (3/3.3 mm) showed no significant differences (p < 0.05). The values of ΔT_surface as well as ΔT_ground also showed no significant differences among LED, halogen lamp, and laser_{(1 W)}. The ΔT_surface values were 4.1_LED, 4.3_{halogen lamp}, and 4.5 °C for the laser while the ΔT_ground values were 2.7_LED, 2.6_{halogen lamp}, and 2.9 °C for the laser. The results indicate that the blue diode laser (445 nm) is a feasible alternative for photopolymerization of complex composite resin restorations in dentistry by the use of selected laser parameters.

Effect of radiant heat on conventional glass ionomer cements during setting by using a blue light diode laser system (445 nm)

The aim of this in vitro study was to evaluate the effect of radiant heat on surface hardness of three conventional glass ionomer cements (GICs) by using a blue diode laser system (445 nm) and a light-emitting diode (LED) unit. Additionally, the safety of the laser treatment was evaluated. Thirty disk-shaped specimens were prepared of each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: group 1 was the control group of the study; in group 2, the specimens were irradiated for 60 s at the top surface using a LED light-curing unit; and in group 3, the specimens were irradiated for 60 s at the top surface using a blue light diode laser system (445 nm). Statistical analysis was performed using one-way ANOVA and Tukey post-hoc tests at a level of significance of a = 0.05. Radiant heat treatments, with both laser and LED devices, increased surface hardness (p < 0.05) but in different extent. Blue diode laser treatment was seemed to be more effective compared to LED treatment. There were no alterations in surface morphology or chemical composition after laser treatment. The tested radiant heat treatment with a blue diode laser may be advantageous for the longevity of GIC restorations. The safety of the use of blue diode laser for this application was confirmed.