Fotogrametría de modelos dentales de yeso

El presente estudio busca definir los parámetros de la cámara fotográfica y encuadre de la imagen para generar fotografías estandarizadas a modelos dentales de yeso que permitan realizar mediciones intermaxilares a través de fotogrametría, y que estas distancias sean tan confiables y válidas como el registro físico. Se realizó medición directa de los modelos con compás de Korkhaus y medición indirecta a través de fotogrametría digital, evaluando si existía diferencia estadística entre ambas mediciones. Como resultado, no se observaron diferencias significativas entre el protocolo digital con un objetivo 100 mm y magnificación 1:4 en comparación con las mediciones directas, por lo que se concluye que con los parámetros seleccionados se logra una adecuada precisión en la fotogrametría respecto a la medición directa.

This study aims to compare the different parameters of the photographic camera with the digital image framing to standardize dental model photography, in order to take intermaxillary measurements through photogrammetry, and so that these distances are as reliable and valid as the physical record. Direct measurement of the models was made with a Korkhaus compass, and indirect measurement through digital photogrammetry, evaluating whether there was a statistical difference between both measurements. As a result, no significant differences were observed between the digital protocol with a 100 mm objective and 1:4 magnification and the direct measurements. It is concluded that with the selected parameters, adequate precision is achieved in photogrammetry, when compared to the direct measurement.

Comparison of model analysis measurements among plaster model, laser scan digital model, and cone beam CT image / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate the possibility of using a digital model and cone beam computed tomograph (CBCT) image for model analysis. METHODS: Model analyses of CBCT images, plaster models, and digital models of 20 orthodontic patients with a permanent dentition with no proximal metal restorations, were compared. RESULTS: The average differences of tooth size measurements were 0.01 to 0.20 mm, and the average difference of arch length discrepancy measurements were 0.41 mm in the maxilla and 0.82 mm in the mandible. The difference in Bolton discrepancy measurements was 0.17 mm for the anterior region and 0.44 mm overall but with no statistically significant difference. When comparing CBCT images with plaster models, the average differences in tooth size measurements were -0.22 to 0.01 mm, and the average differences in arch length discrepancy measurements were 0.43 mm in the maxilla and 0.32 mm in the mandible. Difference in Bolton discrepancy measurements were 0.35 mm in the anterior region and 1.25 mm overall. CBCT images showed significantly smaller overall Bolton discrepancy measurements. CONCLUSIONS: Although there were statistically significant differences in some model analysis measurements, the ranges of measurement errors of the digital model and CBCT images were clinically acceptable. Therefore, a digital model and CBCT image can be used for model analysis.