High-energy Er Research Articles

Laser-assisted Root Canal Filling Removal of Lower Incisors - A Micro-CT Study.

To compare the efficiency of root canal filling removal from oval-shaped root canals with high-energy Er:YAG laser and additional instrumentation with a rotary Ni-Ti XP-Endo Finisher R system. The in vitro study was accomplished on 12 freshly extracted single-rooted mandibular incisors with one straight oval-shaped root canal, shaped with XP-Endo Shaper 30/.04 and obturated by using the warm vertical condensation technique subjected to further endodontic orthograde retreatment. Group 1: the first retreatment was carried out using a high-energy Er:YAG laser (n = 12). Group 2: the additional retreatment of the same specimens was performed with the XP-Endo Finisher-R system (n = 12). The effectiveness of the retreatment techniques was evaluated by a threefold micro-CT examination. The amount of the remaining root canal filling material was analyzed by Mann-Whitney U test and Friedman tests. A significant decrease in the quantity of the root canal filling was found following the first and after the second retreatment, compared to the initial values in all examined sections (P < 0.001). Within groups, additional application of the Ni-Ti system resulted in no significant removal of the filling materials (P > 0.05). None of the systems resulted in complete root canal filling removal. Despite the improved results after the application of the supplementary retreatment protocol, none of the root canal walls were completely clean in the apical area. The high-energy Er:YAG laser and XP-Endo Finisher R rotary system can be successfully used in endodontic orthograde retreatment under relevant operating parameters.

Effects of an Erbium:Yttrium‐Aluminum‐Garnet Laser and Ultrasonic Scaler on Titanium Dioxide‐Coated Titanium Surfaces Contaminated With Subgingival Plaque: An In Vitro Study to Assess Post‐Treatment Biocompatibility With Osteogenic Cells

Effects of conventional ultrasonic scaler versus an erbium:yttrium-aluminum-garnet (Er:YAG) laser on titanium surfaces contaminated with subgingival plaque from patients with peri-implantitis are evaluated in terms of: 1) plaque and biocorroded titanium oxide coating removal; 2) surface change induction; and 3) residual biocompatibility toward osteoblasts. Subgingival plaque-coated titanium disks with a moderately rough surface were fixed with ethanol and treated with an ultrasonic scaler (metal tip) or Er:YAG laser (20.3 or 38.2 J/cm2) in non-contact mode. Fluorescent detection of residual plaque was performed. Disk surface morphology was evaluated by scanning electron microscopy. Viability, attachment, proliferation, and differentiation of Saos-2 osteoblasts on new and treated disks were assayed by propidium iodide/DNA stain assay and confocal microscopic analysis of cytoskeleton, Ki67, expression of osteopontin and alkaline phosphatase, and formation of mineralized nodules. Both methods resulted in effective debridement of treated surfaces, the plaque area being reduced to 11.7% with the ultrasonic scaler and ≤0.03% with the Er:YAG laser (38.2 J/cm2). Ultrasound-treated disks showed marked surface changes, incomplete removal of the titanium dioxide (TiO2) layer, and scanty plaque aggregates, whereas the Er:YAG laser (38.2 J/cm2) completely stripped away the plaque and TiO2 layer, leaving a micropitted surface. Both treatments maintained a good biocompatibility of surfaces to Saos-2 osteoblasts. Air-water cooling kept disk temperature below the critical threshold of 47°C. This study shows that an ultrasonic scaler with metal tip is less efficient than high-energy Er:YAG irradiation to remove the plaque and TiO2 layer on anodized disks, although both procedures appear capable of restoring an adequate osseoconductivity of treated surfaces.

Stable high-energy Q-switched resonantly diode-pumped Er:YAG laser at 1645 nm

We demonstrate the generation of a stable high-energy Q-switched resonantly diode-pumped Er:YAG laser at 1645nm in passive and active operation modes. For the passively Q-switched Er:YAG laser, the bi-layer graphene saturable absorber (SA), which was transferred onto the highly reflective cavity mirror by an improved method, was applied to deliver a stable pulse train with per-pulse energy of about 0.1mJ. While in the active operation mode, the voltage-ON-type rubidium titanyl phosphate (RTP) Pockels cell as an electro-optic (EO) Q-switcher allows for the generation of a stable Q-switched pulse with per-pulse energy of up to 7.5mJ. Our work may provide a basis for the development of a high-energy Er:YAG laser at 1645nm to fulfill specific applications.

High peak power Q-switched Er:YAG laser with two polarizers and its ablation performance for hard dental tissues.

An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser.

Silica hollow core microstructured fibres for mid-infrared surgical applications

In this paper two silica hollow core microstructured fibres (Negative Curvature Fibre and Photonic Bandgap Fibre) are presented with attenuations of 0.06dB/m and 1.1dB/m at 2.94μm wavelengths, respectively. This is an important regime for medical applications, specifically surgery due to the existence of a strong absorption peak for water around 3μm. The guidance of high energy pulses of the order of 195mJ and 14.4mJ respectively has been demonstrated. These energies are sufficient to ablate soft and hard biological tissues. As verification porcine bone was ablated in air and submerged in water to simulate practical application of a surgical device. These fibres open the way to a new and fully flexible delivery system for high energy Er:YAG laser radiation.

Delivery of high energy Er:YAG pulsed laser light at 294µm through a silica hollow core photonic crystal fibre

In this paper the delivery of high power Er:YAG laser pulses through a silica hollow core photonic crystal fibre is demonstrated. The Er:YAG wavelength of 2.94 µm is well beyond the normal transmittance of bulk silica but the unique hollow core guidance allows silica to guide in this regime. We have demonstrated for the first time the ability to deliver high energy pulses through an all-silica fibre at 2.94 µm. These silica fibres are mechanically and chemically robust, biocompatible and have low sensitivity to bending. A maximum pulse energy of 14 mJ at 2.94 µm was delivered through the fibre. This, to our knowledge, is the first time a silica hollow core photonic crystal fibre has been shown to transmit 2.94 μm laser light at a fluence exceeding the thresholds required for modification (e.g. cutting and drilling) of hard biological tissue. Consequently, laser delivery systems based on these fibres have the potential for the realization of novel, minimally-invasive surgical procedures.

Pulse shaping fiber laser at 15 μm

In this paper we present, for the first time to our knowledge, a new pulse shaping technology (modulation schemes for seed laser) used to mitigate pulse narrowing effect and SBS effect in a high energy Er:Yb codoped fiber master oscillator power amplifier system at 1.5 μm to obtain longer pulse duration and higher energy. An average power of over 1.3 W and a pulse energy of over 0.13 mJ were obtained at 10 kHz repetition rate with a pulse duration of 200 ns and near-diffraction-limited beam quality (M(2)<1.2).

Skin Resurfacing Improved with a New Dual Wavelength Er:YAG/CO2 Laser System: A Comparative Study

The efficacy of a new dual wavelength Er:YAG and CO2 laser system was tested for skin resurfacing results on rabbits' ears and human facial skin. The dual wavelength laser delivers simultaneous pulses of low-energy CO2 and high-energy Er:YAG energies. Theoretically, combining the strengths of both laser types in one console should lead to improved clinical outcome. The use of the laser for skin resurfacing and remodeling has dramatically increased over the past few years. The CO2 laser was the first laser to be used in this field, followed more recently by the E:YAG laser. Both lasers offer unique advantages and disadvantages. The present study consists of an ear chamber experiment, conducted on eight rabbits, to examine vascular network formation, after laser resurfacing with a standard CO2 laser and the Er:YAG/CO2 laser. Resurfacing was also performed on human patients with the Er:YAG/CO2 laser and the results were compared with previously published results of CO2 laser resurfacing. Significant advantages, including an attenuation in the degree of edema and erythema and a shorter reepithelialization time compared to results with conventional CO2 systems, were observed with the Er:YAG/CO2 system. Improved tissue reorganization and good clinical results in nine of the ten patients (six ratings of "very good" and three "good") were observed. The clinical outcome of the remaining patient was rated as "fair." Minimal side effects were reported and observed in only three patients. The learning curve required to maximize the efficiency of the system is steep, however, requiring a thorough understanding of the different laser/tissue interactions associated with the two wavelengths. It is the authors' opinion that the dual wavelength Er:YAG/CO2 laser system offers a particularly efficient and flexible system to perform standard CO2 procedures for skin resurfacing with an improved clinical outcome, as well as other applications with the CO2 or Er:YAG energy delivered separately.

High Energy Er:YAG Laser Resurfacing

The Er:YAG laser was developed in an effort to resurface skin reliably and effectively with greater safety, fewer side effects, and faster healing than

High energy erbium laser end-pumped by a laser diode bar array coupled to a Nonimaging Optic Concentrator

A high energy Er 3+, Yb 3+:glass laser end pumped by a laser diode array emitting at 980 nm coupled to a Nonimaging Optic Concentrator (NOC) is demonstrated. Energy up to 100 mJ and a 16% slope efficiency are achieved in a plano-plano laser cavity. The energy transfer coefficient from Yb 3+ to Er 3+ is estimated by a new method.

Room temperature light emitting silicon diodes fabricated by erbium ion implantation

In this work we report the fabrication and characteristics of light emitting erbium-doped Si diodes operating at room temperature (RT). These devices were prepared by multiple high energy Er implantation in the active region of a p +-n + Si diode. Oxygen or fluorine implantation in the Er-doped region was also performed in order to properly modify the Er 3+ chemical surrounding. Electroluminescence (EL) at 1.54 μm and at RT has been observed under both forward and reverse bias conditions with the maximum intensity under reverse bias. The temperature dependence of the luminescence revealed that forward-bias EL decreases by about a factor of 30 on going from 100 K to 300 K. An identical temperature dependence is observed in photoluminescence (PL) suggesting that similar excitation mechanisms are responsible for PL and forward-bias EL. In contrast, reverse-bias EL presents a very weak temperature dependence, with a decrease by only a factor of 4 from 100 K to 300 K. These data are reported and possible excitation mechanisms are discussed.