Root surface area measured by the benzene adsorption method

Effects of the cone-beam computed tomography protocol on the accuracy and image quality of root surface area measurements: An in vitro study

Purpose

The objective of this study was to evaluate and compare the accuracy and image quality of root surface area (RSA) measurements obtained with various cone-beam computed tomography (CBCT) protocols, relative to the gold standard of micro-computed tomography (CT), in an in vitro setting.

Materials and Methods

Four dry human skulls were scanned using 8 different protocols, with voxel sizes of 0.15 mm, 0.3 mm, and 0.4 mm. Three-dimensional models of the selected teeth were constructed using CBCT and micro-CT protocols, and the RSA was automatically measured by the image-processing software. The absolute difference in the percentage of the RSA (%ΔRSA) was calculated and compared across the 8 CBCT protocols using repeated-measures analysis of variance. Finally, image quality scores of the RSA measurements were computed and reported in terms of percent distribution.

Results

No significant differences were observed in the %ΔRSA across the 8 protocols (P>0.05). The deviation in %ΔRSA ranged from 1.51% to 4.30%, with an increase corresponding to voxel size. As the voxel size increased, the image quality deteriorated. This decline in quality was particularly noticeable at the apical level of the root, where the distribution of poorer scores was most concentrated.

Conclusion

Relative to CBCT protocols with voxel sizes of 0.15 mm and 0.3 mm, the protocols with a voxel size of 0.4 mm demonstrated inferior image quality at the apical levels. In spite of this, no significant discrepancies were observed in RSA measurements across the different CBCT protocols.

Comparison of 2 root surface area measurement methods: 3-dimensional laser scanning and cone-beam computed tomography

Purpose

The aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement.

Materials and Methods

Thirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient (ICC) was used to assess intraobserver reliability.

Results

The root surface area measurements (230.11±41.97 mm²) obtained using CBCT were slightly greater than those (229.31±42.46 mm²) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT.

Conclusion

This study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth.

Accuracy of supported root ratio estimation from projected length and area using digital radiographs

BACKGROUND

The purpose of this study was to evaluate the accuracy of supported single-root surface ratio estimated from the length and projected area of the tooth, using digital dental radiographs.

METHODS

Eight extracted, single-root teeth were three-dimensionally digitized using a contact technique for surface area measurement. The data were then processed using engineering application software and length, projection area, and true surface area of the root at a designated length were obtained. Based on these three measurements, the accuracy of the supported surface area ratio measurement at different lengths of the root was evaluated.

RESULTS

The largest mean errors from linear and area estimation were 9.58% and -1.16%, respectively. The 95% confidence intervals were all positive, indicating that linear measurements overestimated supported ratio. T tests showed that linear estimations resulted in significant differences in all eight teeth and area estimations in five teeth. When analyzing the supported ratio of the alveolar bone receding from the cemento-enamel junction (CEJ) toward the apex of the root at each mm, linear estimation showed significant differences down to 8 mm, while area estimation showed significant differences only up to 2 mm.

CONCLUSIONS

The results of this study indicate that a reliable estimate of the ratio of root surface area supported by alveolar bone cannot be determined from linear or area data. However, when the marginal bone destruction exceeds 2 mm from the CEJ, area estimation does not show a significant difference in the supported region. As demonstrated in this study, root surface ratio estimation function could be an advantage of digital dental x-ray systems in which projected root area is readily observed.

A meta-analysis of normal ranges for root surface areas of the permanent dentition

The typical values and normal ranges of the permanent dentition root surface areas were estimated based on a meta-analysis of 4730 root surface area measurements collected from 22 published studies between 1950 and 1992. A typical dentition root surface area, excluding 3rd molars, was 75 cm2, and 95% of the dentitions had a total root surface area somewhere between 65 cm2 and 86 cm2. The prognostic significance of particular values of root surface areas for dental treatment outcomes requires further investigation.

Periodontal attachment loss assessed by linear and area measurements in vitro

The aim of the present study was to investigate the relationship between linear and area measurements of periodontal attachment loss, and to determine the root surface area on different tooth-types. Extracted permanent teeth were collected in a national survey including a systematic random sample of 500 Norwegian dentists. The response rate was 70%. Altogether 329 teeth were received, 81 of them (excluding 3rd molars) were subjected to both linear and area measurements of attachment loss. Using a dissecting microscope (10 x), 4 to 8 duplicate linear measurements were recorded per tooth. The areas of both lost and remaining periodontal attachment were measured by a method based on controlled release of Cu and Co metal ions from coatings applied to the root surface. Linear loss of attachment for single-rooted teeth (n = 63) was mean = 44.0% and the area loss mean = 49.2%. The corresponding measurements for multi-rooted teeth (n = 18) were mean = 30.3% and mean = 35.1%, respectively. The correlation between linear and area loss was r = 0.78 for single-rooted and r = 0.75 for multi-rooted teeth (p < 0.01). The lower correlation in multi-rooted teeth is probably due to the more complex root anatomy. It is concluded that there is a strong correlation between linear loss of attachment and area of periodontal support lost for teeth with early to moderate loss of attachment, and that linear measurements tend to underestimate the remaining periodontal attachment.

Root surface measurements of mandibular molars using stereophotogrammetry

Ten mandibular first molars were hemisected and the root surface of each root was measured using stereophotogrammetry and computer analysis. In each tooth the mesial root was determined to have a greater surface area than the distal root. This difference was statistically significant. The fact that the mesial root has the larger surface area must be a consideration when hemisection is planned.