Investigation of Er:YAG laser-activated irrigation for the removal of biofilm and observations of laser-induced cavitation behavior

Background We investigated the biofilm removal effects of LAI using a pig model, focusing on the impact of the fiber tip position, and used a high-speed camera to observe the occurrence and positioning of the cavitation associated with laser irradiation. Methods A total of 16 roots of deciduous mandibular second premolars from 4 pigs were used. After a pulpectomy, the canals were left open for two weeks and sealed for 4 weeks to induce intraradicular biofilm. Then, root canal irrigation was performed with Er:YAG laser activation. The fiber tip was inserted at two different positions, i.e., into the root canal in the intracanal LAI group and into the pulp chamber in the coronal LAI group. Intracanal needle irrigation with saline or 5% NaOCl was utilized in the positive control and CNI groups. SEM and qPCR were carried out to evaluate treatment efficacy. For qPCR, ANOVA and a Tukey-Kramer post hoc test were performed with α = 0.05. A high-speed camera was used to observe the generation of cavitation bubbles and the movement of the induced bubbles after laser irradiation. Results The intracanal and coronal LAI groups showed significantly lower amounts of bacteria than either the positive control or CNI groups. There was no significant difference found between the intracanal and coronal LAI groups. SEM images revealed opened dentinal tubules with the destruction of biofilm in both LAI groups. High-speed camera images demonstrated cavitation bubble production inside the root canal after a single pulse irradiation pulse. The generated bubbles moved throughout the entire internal multi-rooted tooth space. Conclusions Coronal LAI can generate cavitation in the root canal with a simply placed fiber inside the pulp chamber, leading to effective biofilm removal. This method could thus contribute to the future development of endodontic treatments for refractory apical periodontitis caused by intraradicular biofilm.

A Comparative Clinical Study of Er:YAG Laser and Hand Instruments in the Treatment of Moderate Chronic Periodontitis

Introduction: Moderate chronic periodontitis is the most common periodontal disease. The treatment of this condition should aim at achieving a biocompatible root surface and decontamination of the pocket, thereby restoring the health status. Aim: In the present study, the aim was to examine the clinical effectiveness of fibreless Er:YAG laser used for scaling and root planing and to compare it with a conventional treatment with Gracey curettes. Materials and methods: The study included 909 periodontal pockets which were treated in a split-mouth design with either Gracey curettes or with Er:YAG laser (1.5 W). Probing pocket depth (PPD), gingival recession (GR), clinical attachment level (CAL), bleeding on probing (BoP), and plaque index were recorded. Results: There was a considerable decrease of PPD, CAL, BoP, and plaque presence values at 1 and 3 months after therapy in both treatment groups. Sites treated with Er:YAG laser demonstrated mean CAL gain of about 1.00 mm and 0.44 mm at the first and third month, respectively. In the control group, there was also significant gain of CAL of about 1.33 mm at the first and 0.30 mm at the third month. Significant difference was observed in all parameters between both groups in favour of the laser treatment. Conclusions: The results of the present study suggest that the Er:YAG laser shows clinical effectiveness in the treatment of moderate chronic periodontitis. It can be used as a single treatment modality for subgingival scaling and root planing resulting in greater improvements in all recorded data in contrast to conventional treatment.

Gingival Depigmentation Using Diode 980 nm and Erbium-YAG 2940 nm Lasers: A Split-Mouth Clinical Comparative Study

Aim of the Study. This study aimed to compare the effectiveness of diode laser (980 nm) and erbium-YAG laser (2940 nm) for gum depigmentation. Background. Gingival hyperpigmentation, “black gum,” refers to black discrete single or multiple pigments on the gingiva. Several factors may play a role in gingival hyperpigmentation ranging from physiologic pigmentation to manifestations of systemic diseases. Several techniques have been used for gingival depigmentation to lighten its color. Methods. Fifteen patients exhibiting nonsmoking melanin hyperpigmentation, with the mean age of 28.6 ± 7.8 years, were recruited. The facial gingiva of the anterior teeth and premolars of each jaw was divided into two halves. The right or left side of each jaw quadrant randomly received either diode laser operating at 980 nm wavelength or erbium-YAG laser at 2940 nm. Parameters such as degree of gingival depigmentation, bleeding, pain, patient satisfaction, and wound healing were assessed and compared between the two techniques. The subjects were followed up to six months for melanin pigmentation recurrence. Results. Both techniques were efficient for gingival depigmentation. Nevertheless, bleeding during surgery was statistically higher for Er:YAG laser technique as compared to diode laser. Wound healing showed statistically nonsignificant differences between the two lasers, although Er:YAG seems to give better outcomes than the diode. The patients were satisfied with both laser techniques during and after gingival depigmentation. However, the pain score was higher for Er:YAG laser than for diode laser. Conclusion. This study demonstrated that both lasers’ techniques are efficient for gingival depigmentation. However, diode laser seems to show less painful experience and relatively better bleeding control.

Comparative ex vivo Investigations on the Cutting Quality of the CO2 Laser and the Diode Pumped Er:YAG Laser

Objectives: A sufficient histological evaluation is a key pillar in oncological treatment, especially in situations of cancer of unknown primary. CO2 laser technology is used in clinical routine of soft tissue surgery because of its cutting quality and availability. Diode pumped solid state Er(bium):YAG laser systems promise a higher cutting efficiency and minor thermal damages. The aim of this study was to compare both laser systems with respect to their suitability for cutting soft tissue.Methods: A setup was realized which enables comparable experiments with the clinical CO2 laser (AcuPulse 40ST DUO, Lumenis) and the Er:YAG laser system (DPM 40, Pantec Biosolutions AG). Fresh mucosal samples of porcine tongues were used to determine the influence of laser power and sample velocity on cutting depth and thermal damage width for both lasers. In addition, for the Er:YAG laser, the influence of the pulse repetition rate was examined additionally. For analysis, images of histological sections were taken.Results: In all experiments, the Er:YAG laser shows a significantly higher cutting depth (P < 0.0001) and less thermal damage width (P < 0.0001) than the CO2 laser. For example, at an average power of 7.7 W and a sample velocity of 5 mm/s the Er:YAG laser shows a mean cutting depth of 1.1 mm compared to the CO2 laser with 500 μm. While the Er:YAG laser shows a mean thermal damage width of 70 μm compared to 120 μm. Furthermore, the Er:YAG enables the adjustment of the cutting depth and thermal damage width by varying the irradiation parameters. A decrease of the repetition rate leads to a reduction of thermal damage. For example, a repetition rate of 100 Hz results in a thermal damage width of 46 μm compared to 87 μm at 800 Hz at an average power of 7.7 W and a cutting velocity = 5 mm/s while a homogenous cutting quality can be achieved.Conclusions: In conclusion, the results of these ex vivo experiments demonstrate significant advantages of the diode pumped Er:YAG laser system for soft tissue ablation compared to the CO2 laser, in particular regarding cutting efficiency and thermal damage width.

Study of the effectiveness of post-burn scars correction using Er:YAG laser

The purpose of this study was to investigate the effectiveness of post-burn scars laser correction using an Er:YAG laser (2936 nm) with an SMA module (6mm). 112 women aged 16–50 years were monitored on an outpatient basis. All patients were diagnosed with post-burn scars of the face and body. The main inclusion criteria were post-burn scars; non-inclusion criteria were other types of scars, previously performed procedures for the correction of scars by physiotherapy, general contraindications to laser therapy. During the study, high efficacy and safety of this method was demonstrated in 112 patients. The dynamics of changes were evaluated according to the Dermatology Life Quality Index (DLQI), Dermatological Symptom Scale Index and special research methods (ultrasound scanning, photographing). The follow-up period ranged from 3 to 7 months. Patients underwent from 2 to 6 laser procedures on the face and body with an interval of 1 month. The study is prospective and is planned to be continued. At the moment, a cross-section of the results is presented. During the course of laser procedures, 13 patients dropped out, 99 continue treatment.

Efficacy of Er:YAG laser irradiation for decontamination and its effect on biocompatibility of different titanium surfaces

Background Erbium yttrium–aluminum–garnet (Er:YAG) laser have been shown to be suitable for decontamination of titanium surfaces at a wide range of energy settings, however, high intensity of laser irradiation destroy titanium surface and low intensity cannot remove enough microbial biofilm. The aim of this study was to investigate the optimal energy setting of Er:YAG laser for decontamination of sandblasted/acid-etched (SLA) and hydroxyapatite (HA) titanium surfaces. Material and methods After supragingival biofilm construction in vivo, SLA and HA titanium discs were divided into three groups: blank control (BC, clean discs), experimental control (EC, contaminated discs) and experimental groups (EP, contaminated discs irradiated by Er:YAG laser at 40, 70, and 100 mJ/pulse). Scanning electron microscopy (SEM), live/dead bacterial fluorescent detection, and colony counting assay were used to detect the efficacy of laser decontamination. To investigate the effect of laser decontamination on titanium surface biocompatibility, MC3T3-E1 cell adhesion and proliferation activity were examined by SEM and CCK-8 assay. Results Er:YAG laser irradiation at 100 mJ/pulse removed 84.1% of bacteria from SLA titanium surface; laser irradiation at 70 and 100 mJ/pulse removed 76.4% and 77.85% of bacteria from HA titanium surface respectively. Laser irradiation improved MC3T3-E1 cell adhesion on both titanium surfaces. For SLA titanium discs, 100 mJ/pulse group displayed excellent cellular proliferation activity higher than that in BC group (P < 0.01). For HA titanium discs, 70 mJ/pulse group showed the highest activity comparable to BC group (P > 0.05). Conclusions With regards to efficient microbial biofilm decontamination and biocompatibility maintenance, Er:YAG laser at 100 mJ/pulse and 70 mJ/pulse are considered as the optimal energy settings for SLA titanium and HA titanium surface respectively. This study provides theoretical basis for the clinical application of Er:YAG laser in the treatment of peri-implantitis.

Er:YAG laser irradiation enhances bacterial and lipopolysaccharide clearance and human gingival fibroblast adhesion on titanium discs

To investigate the effect of Er:YAG laser treatment on lipopolysaccharide (LPS) clearance and fibroblast adhesion on titanium disks. Grade IV titanium discs (n = 216) were used and allocated to 6 groups. Group 1 was the negative control without Porphyromonas gingivalis inoculation. Discs in Groups 2–6 were incubated with P. gingivalis to form a biofilm. Group 3 received 0.12% chlorhexidine irrigation and Group 4 received titanium curettage to remove the biofilm. Group 5 was treated with Er:YAG laser irradiation and Group 6 was treated with titanium curettage plus Er:YAG laser irradiation. The contact angle and surface roughness were measured after the various treatments. The surface microstructure and residual bacteria were examined using scanning electron microscopy and confocal laser scanning microscopy, respectively. Residual LPS was examined using a limulus amoebocyte lysate assay and human gingival fibroblast adhesion was quantified using fluorescent microscopy. Curettage plus Er:YAG laser irradiation was the most effective method for removing bacteria and LPS. No significant difference in the amount of fibroblast adhesion was found between the control and Group 6. Combined use of Er:YAG laser irradiation and curettage optimizes LPS clearance and fibroblast adhesion on titanium discs.

Efficacy and safety comparison between 1927 nm thulium laser and 2940 nm Er:YAG laser in the treatment of facial atrophic acne scarring: a prospective, simultaneous spilt-face clinical trial

Acne scarring is a common disfiguring complication of acne, and fractional lasers are widely applied in improving it. This study is to compare the efficacy and safety of fractional non-ablative 1927 nm thulium laser (FTL) and fractional ablative 2940 nm Er:YAG laser (FEL) in the treatment of acne scarring. Subjects with moderate or severe atrophic facial acne scarring received 3 sessions of FTL on the left side of face and FEL on the right side of face at an average interval of 4–6 weeks. Major assessments included Goodman&Baron quantitative global scarring grading system (GBS), self-rated improvement and satisfaction score. Twenty-seven subjects completed the study; for FTL side, average GBS decreased from 11.15 ± 5.04 at baseline to 7.07 ± 4.87 with an improvement percent of 36.54%; for FEL side, average GBS decreased from 10.81 ± 4.46 to 7.00 ± 4.07 with an improvement percent of 35.27%. Adverse effects include transient pain, erythema, edema, and increase of acne. No significant difference was found between two lasers. Both FTL and FEL improved atrophic acne scarring and were well-tolerated. Increase of acne during laser treatment may have a negative impact on efficacy. Trial registration number was NCT04813419 and date of registration was 19th, March, 2021, retrospectively registered.