Laser treatment has become a popular method for resolving peri-implantitis, but the full range of its effects on implant surfaces is unknown. The purpose of the present investigation was to analyze the influence of different clinically applicable erbium:yttrium-aluminum-garnet (Er:YAG), carbon dioxide (CO2), and diode laser parameters on titanium surfaces that were either polished or sandblasted, large-grit, acid-etched (SLA).Six polished and six SLA titanium disks were irradiated at nine different power settings (n = 54 polished, 54 SLA) with Er:YAG, CO2, or diode lasers. The CO2 and diode lasers were used in continuous wave mode, and the Er:YAG laser was used in a pulsed manner. The surface of each disk was analyzed by scanning electron microscopy and confocal white light microscopy. Each disk was irradiated on six circular areas of 5 mm in diameter with the same specific laser setting for 10 seconds.Within the chosen parameters, the CO2 and diode laser did not cause any visible surface alterations on either the polished or SLA disks. In contrast, both polished and SLA disks showed surface alterations when irradiated with the pulsed Er:YAG laser. The SLA surfaces showed alteration after 10 seconds of irradiation with Er:YAG laser at 300 mJ/10 Hz. The surfaces of the polished disks did not show alteration with the Er:YAG laser until they were irradiated at the higher energy of 500 mJ/10 Hz for 10 seconds. The results of confocal white light microscopy were in agreement with scanning electron micrographs.In contrast to continuous-wave diode and CO2 laser irradiation, pulsed Er:YAG laser irradiation caused distinct alterations with power settings beyond 300 mJ/10 Hz on the SLA surface and 500 mJ/10 Hz on the polished surface. Thus, it is only safe to use the Er:YAG laser for implant surface irradiation with settings no higher than 300 or 500 mJ/10 Hz.
Lewis antigens and the Thomsen-Friedenreich (TF) antigen are complex glycan structures that modulate processes such as cell adhesion and proliferation and tumor metastasis. The aim of our study was to analyze the expression of sialyl Lewis A (sLeA), sialyl Lewis X (sLeX), Lewis Y (LeY), TF, galectin-1 (Gal-1) and galectin-3 (Gal-3) in human osteoblasts in vitro.The expression of the tumor markers sLeA, sLeX, LeY, TF, Gal-1 and Gal-3 was studied by means of immunohistochemistry on cells grown on chamber slides (2D) and on paraffin sections three-dimensional scaffold-free cultures (3D). The results of the stainings were evaluated semiquantitatively with the immunoreactive scoring system (IRS).Analysis of sLeA expression in both types of culture, 2D and 3D showed no detectable staining. After 5 days, in the 2D culture, expression of sLeX was weak, but the 3D culture (after 56 weeks) displayed a strong expression. LeY was expressed very slightly in the 2D culture, however LeY was not detectable in the 3D culture. The TF epitope was identified in the 2D cell culture model. In the 3D model, however, TF was completely lacking. Gal-1 was expressed very strongly in 2D culture, but in the 3D culture was not detectable. In contrast, Gal-3 was expressed in 3D culture but not in 2D.Within this study, we present a systematic analysis of the expression of sLeA, sLeX, LeY, TF, Gal-1 and Gal-3 in human osteoblasts grown in 2D and in 3D scaffold-free cultures. Summarizing the results of our study, we suggest that Lewis antigens and Gal-1 and -3 might play an important role in cell-cell and cell-matrix interactions of osteoblastic cells.
<i>Background:</i> The purpose of this retrospective study was to evaluate the surgical performance, clinical usability and outcome of a new variable square pulsed (VSP) Er:YAG laser for bone cutting in oral and maxillofacial surgery. <i>Materials and Methods:</i> In 40 patients an Er:YAG laser with pulse energy of 1,000 mJ, pulse duration of 300 μs and a frequency of 12 Hz was used for different intraoral osteotomies. The spot size was 0.9 mm, and the handpiece was kept at a distance of 10 mm from the bone surface. Additionally, histological analyses of the fresh osteotomy rims of lasered bone were performed. <i>Results:</i> Er:YAG laser osteotomy revealed a remarkable cutting efficiency without any visible, negative, thermal side effects. There was no damage of adjacent soft tissue structures. However, depth control was limited to visual inspection. Histologically, a 5- to 10-μm-wide zone of a characteristic laser fingerprint appeared on the cut edges. However, there was no sign of thermal tissue damage to the underlying bone structures. <i>Conclusions:</i> VSP Er:YAG laser osteotomy is clinically practicable without any signs of charred tissue and wound healing disturbances. However, the lack of depth control and the necessity for careful handling are still technical limitations to be overcome.
Diamond-like carbon (DLC) has been established as a very favourable coating for joint prosthetics due to its low friction, high corrosion resistance and biocompatibility. The addition of dopants allows for the modification of several physical properties of DLC, whose relations to biocompatibility have not yet been thoroughly investigated. We studied the properties of a-C:H layers deposited on TiAl6V4 by the plasma immersion ion implantation and deposition (PIII&D) technique. Physical analysis performed comprises the range of attainable compositions [obtained by Rutherford backscattering spectroscopy (RBS) and elastic recoil detection analysis (ERDA)] and structures [by Raman Spectroscopy and energy filtered transmission electron microscopy (EFTEM)] for the cases of the dopants N, Si and TiOx. The biocompatibility assessments were performed in vitro, utilizing human osteoblasts. Cellular proliferation was measured by means of DNA quantification. Osteogenic differentiation was investigated by screening alkaline phosphatase activity and mineralization of cultures. The results demonstrate that highly biocompatible and wear-resistant coatings on complex formed implant surfaces can be efficiently fabricated utilizing PIII&D.
This preliminary report describes a new laser-assisted treatment option for the emerging complication of bisphosphonate related osteonecrosis (BON) of the jaw.In eight tumour patients (three women, five men) ten bony lesions in the maxilla and mandible in the course of intravenous bisphosphonate therapy were treated with a variable square pulsed (VSP) Er:YAG laser. For the treatment, the Er:YAG laser was applied with a pulse energy of 1,000 mJ, a pulse duration of 300 microseconds, and a frequency of 12 Hz (energy density 157 J/cm(2)). The spot size was 0.9 mm and the handpiece was kept at a distance of about 10 mm from the bone surface. The diseased bone was ablated exclusively with the Er:YAG laser by subsequently sweeping the bone surface in a well directed scanning mode.The surgical procedure and postoperative wound healing were without any complications and a complete soft tissue recovering was achieved within 4 weeks. During follow-up examinations over 12 months soft tissue conditions were stable. The pulsed laser ablation caused a characteristic microstructured and craggy bone surface without a condensation or a smear layer on the laser rims.The bone ablation technique using a VSP Er:YAG laser yielded promising clinical results without impairment of wound healing. A further analyse of the chemical, physical and pharmacological aspects of laser assisted treatment of BON lesions is necessary to get a safe and reliable treatment protocol for bisphosphonate-related osteonecrosis of the jaw.
For an optimal implementation of materials, such as, e.g. medical implants in living environments, a thorough characterization of cell adhesion, kinetics and strength is required, as well as a prerequisite e.g. for bone integration. Here we present a miniaturized (~100 μl) lab-on-a-chip implant hybrid system which allows quantification of cell adhesion under dynamic conditions mimicking those of physiological relevance. Surface acoustic waves are excited and used on optical transparent chips to induce micro acoustic streaming and to create a microfluidic shear spectrum ranging from 0 to ~35 s(-1). We demonstrate its potential for a time-efficient, dynamic screening test of new implant materials using a model of an osseointegration with SAOS-2 cells. The upside-down orientation also allows utilization of the micro reactor on non-transparent materials like titanium and diamond-like-carbon (DLC).
Recently the importance of the third dimension in cell biology has been better understood, resulting in a re-orientation towards three-dimensional (3D) cultivation. Yet adequate tools for their morphological characterization have to be established. Synchrotron radiation-based micro computed tomography (SRμCT) allows visualizing such biological systems with almost isotropic micrometer resolution, non-destructively. We have applied SRμCT for studying the internal morphology of human osteoblast-derived, scaffold-free 3D cultures, termed histoids. Primary human osteoblasts, isolated from femoral neck spongy bone, were grown as 2D culture in non-mineralizing osteogenic medium until a rather thick, multi-cellular membrane was formed. This delicate system was intentionally released to randomly fold itself. The folded cell cultures were grown to histoids of cubic milli- or centimeter size in various combinations of mineralizing and non-mineralizing osteogenic medium for a total period of minimum 56 weeks. The SRμCT-measurements were performed in the absorption contrast mode at the beamlines BW 2 and W 2 (HASYLAB at DESY, Hamburg, Germany), operated by the GKSS-Research Center. To investigate the entire volume of interest several scans were performed under identical conditions and registered to obtain one single dataset of each sample. The histoids grown under different conditions exhibit similar external morphology of globular or ovoid shape. The SRμCT-examination revealed the distinctly different morphological structures inside the histoids. One obtains details of the histoids that permit to identify and select the most promising slices for subsequent histological characterization.
Objective: To evaluate the usability of a variable square pulse (VSP) erbium-doped yttrium aluminium garnet (Er:YAG) laser for a lateral access osteotomy to the maxillary sinus in the course of a sinus elevation procedure. Materials and Methods: In six formalin-fixed human heads and six fresh sheep heads, a VSP Er:YAG laser was used to perform a bilateral maxillary access osteotomy. For the osteotomies, the Er:YAG laser was applied with a pulse energy of 1000 mJ, a pulse duration of 300 μs, and a frequency of 12 Hz. The spot size was 0.9 mm, and the handpiece was kept approximately 10 mm from the bone surface. Results: In all 24 sites investigated, the Er:YAG laser osteotomy was possible without any visible carbonization or thermal damage. The average time required for laser osteotomy for 12 standardized rectangular lateral windows in human cadavers was 39 s. No anatomical structures limited laser osteotomy, yet a critical evaluation of any membrane perforations was not possible because the postmortem fixation method caused partial detachment and fractional destruction. Laser-access osteotomy in six fresh sheep heads (12 sites) revealed major disruptions and perforations (<8 mm) of the sinus membrane (100%). Conclusion: Even though VSP Er:YAG laser osteotomy showed convincing results for efficient bone cutting without thermal damage, applied laser parameters do not seem to be practicable for any clinical sinus elevation procedure. Missing depth control resulted in uncontrollable severe damage of the underlying membrane.
