Purpose: Current methods for the evaluation of alveolar bone quality and dental implant stability have been shown to provide inconsistent results. The aim of this investigation was to validate a novel diagnostic device (BoneProbe) for the objective classification of alveolar bone during dental implant surgery. Materials and Methods: A metal cylinder (diameter, 3.5 mm) split into six segments was used as a sensor that could be positioned in implant sockets and expanded while the force needed to expand the site was recorded. Simulating all surgical steps, implants were placed into polyurethane foam materials (n = 100 implants) and human cadaver bone (n = 110 implants). Bone quality (cortical bone thickness, trabecular bone density, drilling resistance, implant insertion torque, compressive testing) and primary implant stability (Osstell, Periotest) were evaluated as reference data. Results: In polyurethane foam, significant correlations between all parameters (Pearson correlation coefficients) and a significant influence of the different polyurethane foam materials on all measurement results (multiple analysis of variance with Pillai trace) were found. In general, in human cadaver bone, weaker correlations between the different measurement techniques were seen (Pearson product-moment correlation). With the exception of compressive testing and radiographic assessment of trabecular bone density, all methods were able to differentiate between mandibular and maxillary bone. Conclusions: Based on these in vitro results, it appears that intraoperative testing of alveolar bone allows for a reproducible classification of bone quality. Because the proposed system is independent of any specific implant design, this device could be used for establishing a universally valid bone classification system. Keywords: bone density, bone quality, compressive testing, implant stability