Quantification of edentulous jaw bones using cone-beam computed tomography images

Objectives: Determination of anatomic dimensions and bone quality is an important part for preoperative planning of dental implant treatment. Currently, the quality of jaw bones is subjectively categorized by clinicians using various imaging methods. The purpose of this study was to quantitatively evaluate jaw bone quality by CBCT images. 

Methods: 20 completely edentulous patients were selected for this study. CBCT scans (Hitachi Inc. Japan) were performed using the following technical parameters: 120 KV, 15 MA, 240 mm field of view, and 0.292 voxel of 512x512 pixels for each slice. CBCT images were reconstructed to a three-dimensional model of each mandible and maxilla. Six sites of each patient were studied: upper incisor (UI), upper premolar (UP), upper molar (UM), lower incisor (LI), lower premolar (LP), lower molar (LM).  For each site, cortical bone thickness (CBT) and bone mineral density using Hounsfield unit (HU) were measured at 6 locations; 0, 45, 90, 135, 180, 270 degree of  each cross section of  alveolar bones. Trabecular bone (TB) width, height, and Hu were also measured. Non-parametric statistical tests were applied using Friedman rank-sum test and Kruskal-wallis one-way ANOVA at p< 0.05.

Results:  

Summary of averaged measurements as follows:

	UI	UP	UM	LI	LP	LM
CBHU	305+111	96+61	151+105	643+101	588+143	583+130
CBT (mm)	1.25+0.28	1.16+0.28	1.07+0..16	2.01+0.68	1.91+0.72	1.95+0.62
TBHU	5.48+1.82	3.34+1.42	3.82+0.86	7.90+2.88	6.72+2.75	7.14+2.35

Conclusions: Statistical analyses conclude there were significant differences across 6 sites regarding CBHU, CBT, and TBHU. The rankings are:  LI>LM>LP>UI>UP>UM for CBHU; LM>LP>LI>UI>UP>UM for CBT; and LI>LM>LP>UI>UM>UP for TBHU. Supported by CWRU Summer Research Fellowship Program.