Inter-rater Agreement of Digital Measurement on Cross-sectional CBCT Images

Objectives: Errors in surgical guide fabrication based on digital measures contribute to deviations in planned vs. actual dental implant placement. The goals of this project were to evaluate the alveolar bone dimension at the maxillary 2nd bicuspid site for placement of a standard 4x10mm implant and to evaluate the impact of a clinician’s judgement in choosing structural borders on measurement error in digital dentistry.
Methods: Sixty-six CBCT scans from an anonymized library were evaluated with Invivo 6.0 Anatomage Software. Standardized sagittal and axial slices were used to orient each data set. A reference line was drawn between two points located at the mesial-distal midpoint of the root on the buccal and palatal bone margins. Anatomic measures were made buccal-palatal (BP) along this line and along subsequent parallel lines drawn at 2mm vertical intervals. In addition to total alveolar width, subdivisions were measured: the buccal bone dimension, the tooth dimension and the palatal bone dimension. Descriptive statistics were derived and measures of interrater reliability were calculated using interclass correlation.
Results: The overall mean BP alveolar width at the maxillary 2^nd bicuspid site was 10.77±1.69mm. The mean buccal bone dimension, BP tooth dimension and palatal bone dimension were 1.54±0.94mm, 6.03±1.77mm and 3.2±2.18mm respectively. Inter-rater agreement was calculated at the 95% CI for BP alveolar dimension at site #4(0.88) and at #13(0.85), buccal bone dimension at #4(0.78) and #13(0.78), BP tooth dimension at #4(0.88) and #13(0.83) and palatal bone dimension at #4(0.85) and #13(0.88).
Conclusions: The results suggest that total BP alveolar bone dimension at this site allows for placement of a standard 4x10mm dental implant with its requisite 1mm bone sleeve and that digital measurement error on CBCT images was influenced by the relative thickness of the structure measured.