Validation and Diagnostic Performance of Jaw Bone Densitometry

The assessment of jaw bone quality has a broad field of potential applic ations, such as preoperative planning of implant placement or the follow -up of bone changes as a result of progression of disease or therapy. Cl inical tools for objective quantification of jaw bone quality are sparse , and often not validated. Therefore, the overall aim of this thesis was to develop and validate an objective, clinically applicable tool for ja w bone quality evaluation. Initially, panoramic radiographs were used for assessing jaw bone qualit y and its predictive value for the degree of marginal bone loss (Chapter 2). Bone quality was assessed by radiographic density and a bone qualit y index. Although radiographic density of alveolar bone was associated w ith periodontal bone level to some extent, we were confronted with some methodological constraints of the use of panoramic radiographs, such as geometrical distortion and spatial resolution. The search for a bone density evaluation tool was continued using intra- oral radiographs. For objective quantification, an aluminium stepwedge w as chosen as a reference on the radiographs. This had practical conseque nces for the planned clinical studies which is why, in Chapter 3, the be nefit of using such a stepwedge was explored and confirmed. Densitometri c assessment showed good reproducibility for the analyses with and witho ut aluminium wedge correction, but the assessment was far more accurate when the wedge was included. After this initial justification, the tool was further developed and val idated in Chapter 4. Accuracy and precision were determined in an in vit ro study. The minimal detection threshold was also determined. The tool showed potential for bone density evaluation to monitor minute bone chan ges and was subsequently applied in an in vivo study. Chapter 5 describes this clinical study, which was set up to identify pe rsons with osteoporosis using the tool for jaw bone densitometry on intr a-oral radiographs. A fair diagnostic accuracy for osteoporosis in the h ip or spine was obtained. Based on the same population, in Chapter 6, th e influence of one specific lifestyle factor on the jaw bone, was explor ed: alcohol consumption. We found a reduced density and mandibular corti cal thickness in persons with increased alcohol consumption, as well as in older individuals. For another in vivo application of the tool (Chapter 7), we evaluated th e impact of replacement therapy by monitoring bone density changes and a lveolar bone level in periodontal pockets in a dog model. Although in a small sample, we could appreciate the value of the densitometric tool as a follow-up instrument for detecting small changes in bone density. The densitometric tool for jaw bone has proven its use in the objective assessment of bone. It must be added that it might be necessary to obtai n more specific information on the structural properties of bone to corr ectly interpret certain clinical situations. With a look into the future , we performed a study in Chapter 8 to obtain an idea on how the density on radiographs was correlated to the bone structure on microscopy. The density derived from periapical radiographs showed good correlation with bone structural characteristics, such as bone area and cortical width.status: publishe