# Examination of the Quality of Particulate and Filtered
## 1 Introduction  
A sufficient vertical and transversal bone level is necessary for long-term success of endosseous dental implants [1]. Autologous bone graft is the preferred material for reconstructing jawbone defects as it contains osteoinductive and -conductive properties and does not evoke immunological reactions as must be expected from allogeneic material [2,3]. Next to natural occurring materials, artificial substances can be used for guided bone tissue engineering [4,5]. However, among other problems, their osteoinductive and -conductive properties are poor. Bone particles are commonly obtained from intra-oral sources such as the mandibular symphysis or the retromolar region and can be applied for the grafting procedure. Compared to extra-oral donor sites (e.g., the iliac crest, the tibia, or the skull), these donor site materials are reported to entail a reduced operating and hospitalization time as well as a better incorporation into alveolar defects with less resorption [6, 7, 8]. These bone chips and their respective cells can also be used together with spacers in guided bone regeneration. The collection of particulate bone chips during oral surgical treatment can be performed without additional donor site morbidity [9, 10], as the material can be easilyobtained by bone collection traps integrated in the dental suction pipe or with special bone scrapers [11]. The osteogenic capacity of different stem cell sources is well established (Figure 1). Several stem cell types e.g., bone marrow-derived stem cells (BMSC) or umbilical vein stem cells (UVMSC) display osteogenic capacity and can be obtained in banking ready to use [12]. But also dental pulp stem cells (DPSC), periodontal ligament stem cells, and dental follicle stem cells (DFSC) can differentiate towards osteoblasts in vitro and are reported to be superior for treatment of bone defects in vivo than bone marrow-derived stem cells (BMSC) or adipose tissue-derived stem cells (ADSC) [13; 14; 15; 16], because the cellular origin plays an important role in their osteogenic capacity. Cells isolated from the head region e.g., mandibular stem cells differentiate towards osteoblasts in vitro and contribute to wound healing in animal models more efficiently than cells from other body regions e.g., tibia or femur [17; 18; 19; 20; 21; 22]. Cells from hard tissues, especially from the head region, seem to be already pre-committed towards the osteogenic lineage, displaying less unwanted differentiation effects. However, the quality of bone grafting materials form the oral cavity is insufficiently investigated and has been evaluated inconsistently in the literature. Especially microbial contamination of the collected bone tissue is a matter of concern, since it might lead to postoperative complications or failure of the implantation process [23; 24]. Pre-surgical antibiotic treatment and chlorhexiidine rinse seems to significantly decreases the bacterial load [25; 26; 27; 28]. Nevertheless, it is still unclear whether antibiotic prophylaxis is beneficial and which antibiotic is most effective [29; 30; 31; 32; 33]. Conflicting data also exists regarding the viability of the collected bone particles. Several studies identified an osteogenic differentiation potential of cells growing out of bone chips [34; 35; 36; 37]. Where as bone debris was identified as not ideal grafting material, since its viability could not be demonstrated consistently in another study [38]. The aim of this study was to systematically investigate in more detail the quality of particulate and filtered bone particles and their potential use as bone grafts in regenerative dentistry with and without antibiotic pretreatment. The outgrowth probability of stem  
Figure 1: Osteogenic capacity of different stem cell types. Different stem cell types have been shown to be pre-committed towards the osteogenic lineage depending on their origin. Cells isolated from hard tissues e.g., teeth and bone show a higher osteogenic capacity than cells isolated from adipose tissue.