Er:YAG laser osteotomy: preliminary clinical and histological results of a new technique for contact-free bone surgery.

BACKGROUND: 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. MATERIALS AND METHODS: In 40 patients an Er:YAG laser with pulse energy of 1,000 mJ, pulse duration of 300 mus 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. RESULTS: 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-microm-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. CONCLUSIONS: 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.

Maxillary sinus grafting with a nano-structured biomaterial: preliminary clinical and histological results.

BACKGROUND: In this study the potential of a new and entirely synthetic, nano-structured hydroxyapatite-based biomaterial for sinus floor augmentation is evaluated. METHODS: 20 sinus floor elevations were carried out in a total of 20 patients. After a healing period of 6 months, in 10 cases cylinder-shaped bone biopsies were taken from the augmented maxillary region using trephine burs. RESULTS: The healing period progressed without any complications. General and specific histological analysis of the bone biopsies showed a high osteoclast activity at the margin of the biomaterial which was well integrated into the newly formed bone. CONCLUSION: This study demonstrates that new trabecular bone is formed after grafting with the nanocrystalline bone substitute after 6 months. Ongoing histomorphological studies are necessary to quantify the biomaterial-bone ratio and the exact amount of newly built bone in the augmented cavity after 6 months.

Optimized protocol for whole organ decellularization.

BACKGROUND: The idea of tissue decellularization to gain matrices for tissue engineering is promising. The aim of the present study is to establish a safe and reproducible protocol for solid tissue decellularization that prevents the architecture of the matrix with the inherent vascular network. METHODS: The study was performed in rat kidneys which were decellularized by a SDS-based perfusion protocol. Perfusion time and SDS concentration were systematically changed to obtain the shortest and most gentle protocol that leads to complete decellularization. RESULTS: We investigated kinetics of protein elution, decellularization success, and remaining cell toxicity. This resulted in a reproducible protocol, leading to safe decellularization with prevention of the inherent vascular network, without remaining detectable cell toxicity. The established protocol leads to solid tissue decellularization in only 7 h, which is by far shorter than the previously published methods. CONCLUSION: The established technique has the potential to become a relevant platform technology for tissue engineering of solid tissues. It provides a solution for the yet-unsolved problem of vascularization.

Expression of the tumor markers sialyl Lewis A, sialyl Lewis X, Lewis Y, Thomsen-Friedenreich antigen, galectin-1 and galectin-3 in human osteoblasts in vitro.

AIM: 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. MATERIALS AND METHODS: 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). RESULTS: 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. CONCLUSION: 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.

Palatal piezosurgical window osteotomy for maxillary sinus augmentation.

This technical note describes a new surgical technique for a palatal approach to the maxillary sinus for a vertical augmentation prior to dental implant placement. In 12 fully or partially edentulous patients (seven women, five men), 16 palatal sinus elevations were performed. After elevation of palatal full-thickness flap a rectangular access window was cut with a piezosurgical device. The raised sinus cavity was augmented with a synthetic nano-structured hydroxyapatite-based graft material. No harm occurred to the greater palatine artery or the sinus membrane. The vestibular and periimplant gingiva were preserved and there was no disharmonious soft tissue distortion or massive scar formation. Swelling and bleeding were minimal. Primary stability was achieved for all but one implant. This technique may be an alternative to other sinus augmentation approaches in cases where enough transversal width of the posterior alveolar crest is available.