Osteonecrosis as term represents the death of bone tissue in the body and causes of necrosis can be different. Medication-related osteonecrosis of the jaws (MRONJ) is nowadays known as an inability of the alveolar bone to respond to a local trauma and it can result in severe local and systemic complications. In the etiology of medication-related osteonecrosis there are antiangiogenic and antiresorptive agents which have great effect on alveolar bone, producing an imbalance between resorption (osteoclastic activity) and deposition (osteoblastic activity). The exact mechanisms of development are not todays completely resolved. It is thought that it is a result from combination of medication interactions, microbiological contamination of the area and local tissue trauma. Typical signs and symptoms are painful mucosal lesions, swelling, exposed necrotic bone in the jaws, discomfort and dysesthesias. There is currently no gold standard or clearly defined treatment protocol for the disease itself. Process of treatment is demanding and main goal is to eliminate pain, control infection of soft and hard tissue and minimize progression of osteonecrosis. Besides the conventional surgical treatment, photodynamic therapy can be a viable supportive tool of initial and advanced stages of osteonecrosis and may contribute to improvements of patient′s quality of life.

Background : Bone healing processes following osteotomy may vary according to the type of selected surgical procedures. Frictional heat caused by traditional bur osteotomies may result in thermal osteonecrosis if the temperature arises above the critical temperature of 47º C. Therefore, less invasive and precise tools for bone tissue surgery with reduced collateral tissue thermal trauma, force and friction are developed: laser-assisted bone surgery and piezoelectric surgery. Aim/Hypothesis : The purpose of the present in vivo experimental study was to determine the thermal changes of the bone tissue following osteotomies performed by piezoelectric surgery, surgical drill and Er:YAG laser-assisted ablation used in contact and NO-contact modes using infrared thermographic camera. Materials and Methods : A total number of 24 Wistar rats were randomly divided into 4 groups, each consisting of 6 rats (I-sacrificed immediately after surgery; II-7 days after surgery; III-14 days after surgery; IV-21 days after surgery). Osteotomies on both rat ' s tibiae were performed under general anesthesia and always in the same sequence: digitally controlled NO-contact Er:YAG laser (7.5 W, 750 mJ, 10 Hz, QSP mode), piezosurgery (round diamond tip, 1.2 mm diameter, average pressure 15 N), low-speed surgical drill (1200 rpm, round steel surgical bur 2 mm diameter) and contact Er:YAG laser (H-14N handpiece, fiber of core diameter of 940 μm, 7.5 W, 375 mJ, 20 Hz, MSP mode). The osteotomies were 5 mm away from each other and ~2 mm deep, with a diameter ranging between 1.5-2.0 mm. Temperature measurements during each osteotomy were done using an infrared thermographic camera with a detection range of-20º to + 650º C, a thermal sensitivity of < 50 mK, and IR resolution of 320x240 pixels. Results : For each osteotomy a thermal camera movie was recorded and movie frames were extracted as thermal camera images, and the position of the osteotomy was determined by visual inspection. Temperature readout was performed for this point in all recorded movie frames, providing the information on the temperature at the position of osteotomy while osteotomy was performed. Time evolution of the bone temperature at the point of osteotomy was measured. For each measurement, baseline temperature (Tbase), and maximum temperature measured during the osteotomy (Tmax) were determined. ΔT=Tmax-Tbase was then calculated for each measurement. Mean baseline temperature for each group of osteotomies was 29.96°C for non-contact laser, 27.98°C for contact laser, 28.34°C for surgical drill and 29.39°C for piezosurgery. Mean Tmax for contact laser was 29.92 °C (ΔT=1.94 °C), for non-contact laser was 79.11°C (ΔT=49.15 °C), for surgical drill was 27.36°C and 29.15 °C (ΔT=-0.24 °C) for piezosurgery. Conclusions and Clinical Implications : The results of the present study showed beneficial effects of the piezosurgery and Er:YAG laser used in contact mode of working on heat generation of bone tissue during osteotomy, reducing potential overheating of the bone as registered ...

Background : Peri-implantitis is an disease affecting the soft and hard tissue around implants, resulting in the loss of supporting bone. With the increasing popularity of zirconia dental implants, the need for effective and predictable decontamination protocols of the implant surfaces is becoming more and more important.Aim/Hypothesis : The aim of this study was to evaluate the effect of antimicrobial photodynamic therapy and light-activated disinfection on contaminated zirconia dental implants and investigate if the PDT and LAD cause implant surface alterations Materials and Methods : Seventy-two zirconia dental implants were contaminated with a bacterial suspension prepared from three different bacteria. After contamination, the implants were randomly divided into four test groups ( n = 12) according to the decontamination protocol-Group 1 (PDT1)-PDT (660 nm, 100 mW) with toluidine blue; Group 2 (PDT2)-PDT (660 nm, 100 mW) with phenothiazine chloride dye; Group 3 (LAD)-light emitting diode (LED) with toluidine blue; Group 4 (TB)-toluidine blue without the application of light. In addition two control groups were used-the positive control (PC) group were treated with a 0.2% chlorhexidine-based solution, and implants assigned to the negative control (NC) group, did not receive any treatment.. The implants were analyzed using scanning electron microscope (SEM) to evaluate the possible surface alterations due to the PDT or the LAD protocols.Results : All study groups reduced the number of CFUs significantly compared with the NC ( P < 0.05) with more than 99% bacterial reduction. PDT1, the PDT2 and the LAD groups had the largest bacterial reduction, and were more efficient compared with the TB group ( P < 0.05). SEM analysis did not reveal any alterations of the implant surface after the treatment procedures. Conclusion and ClinicalImplications : Both PDT protocols and the LAD showed high and equal effectiveness in decontamination of zirconia dental implants. Further clinical studies are needed in order to establish a clear and effective decontamination protocol of the zirconia implant surfaces using PDT or LAD.