Three-dimensional analysis of the pulp cavity on surface models of molar teeth, using X-ray micro-computed tomography

Quantitative and qualitative comparisons of pulp cavity volumes produced by cone beam computed tomography and micro-computed tomography through semiautomatic segmentation: An ex vivo investigation

OBJECTIVE

The aim of this study was to measure the volume and visually assess 3-dimensional (3D) virtual models of pulp cavities obtained through semiautomatic segmentation on images from 6 cone beam computed tomography (CBCT) units compared with the reference standard of micro-CT.

STUDY DESIGN

Fifteen mandibular premolar teeth were scanned with 6 CBCT units: Prexion 3D Elite, i-CAT Next Generation, NewTom 5G, Cranex 3D, 3Shape X1, and Orthophos SL 3D, using the smallest available field of view and highest resolution settings. Pulp cavity volumes were quantitatively assessed by 2 calibrated examiners. The volumes from each CBCT unit were compared with micro-CT. Qualitative assessment of the 3D reconstructions was also performed. Repeated-measures analysis of variance and the Friedman test compared the CBCT reconstructions to micro-CT. Intra- and interexaminer agreements were calculated with the intraclass correlation coefficient and kappa statistic.

RESULTS

The CBCT-based volumes were all significantly larger than micro-CT (P ≤ .0061). Prexion, X1, and Orthophos provided the segmentations that most closely resembled the reference standard. Intra- and interexaminer agreements ranged from good to excellent for quantitative measurements. Interexaminer agreement for qualitative evaluation was substantial.

CONCLUSIONS

Semiautomatic segmentation of CBCT images is a feasible method to produce virtual 3D models of the pulp cavity. Prexion, X1, and Orthophos were the CBCT units that resulted in 3D reconstructions most similar to the reference standard.

Micro-CT assessment of radicular pulp calcifications in extracted maxillary first molar teeth

OBJECTIVES

The present study aimed to evaluate the frequency, position, and length of radicular pulp calcifications in three-rooted maxillary first molars using micro-computed tomography.

MATERIALS AND METHODS

Two hundred three-rooted maxillary first molars were scanned at a pixel size of 10 µm and reconstructed using similar parameters. Three-dimensional models of the mesiobuccal (MB1, MB2, MB3), distobuccal (DB), and palatal (P) canals were qualitatively evaluated for discontinuity in the canal path. Transaxial and sagittal cross-sectional images of the roots were further screened, and the complete obliteration of the canal lumen by pulp calcification was identified when the canal had similar radiodensity to the surrounding dentine. Then, the number, position, and length of the calcifications were recorded for each root. Intra-observer agreement was performed using Cohen's kappa test, while one-way ANOVA and Duncan tests compared the lengths of calcifications among the canals, with α = 5%.

RESULTS

Intra-observer agreement was perfect for identification of pulp calcifications (ĸ = 1.0; p = 0.000). MB2 and MB3 canals accounted for the highest percentage frequency of calcifications distributed throughout the canal path. In the MB1, DB, and P canals, they occurred mainly at the apical third. Lengths of calcifications were greater in the MB3 (0.89 ± 0.81 mm) and MB2 (0.82 ± 0.93 mm) canals than in the MB1 (0.39 ± 0.32 mm), DB (0.34 ± 0.22 mm), and P (0.28 ± 0.22 mm) canals (p < 0.05).

CONCLUSION

MB2 and MB3 canals accounted for the highest frequency and length of radicular pulp calcifications. In the MB1, DB, and P canals, calcifications occurred mostly at the apical third, while in the MB2 and MB3, most of calcifications were observed at the orifice level and along the canal path.

CLINICAL RELEVANCE

In maxillary first molars, radicular pulp calcifications are mainly located at the apical third of the MB1, DB, and P canals, while in the MB2 and MB3 canals, most of them are at the orifice level or along the canal path.

Removal of calcifications from distal canals of mandibular molars by a non-instrumentational cleaning system: A micro-CT study

Pulpal calcifications can present problems in endodontic treatment. This micro-CT study examined the removal of calcifications by a multisonic cleaning system in uninstrumented mandibular molar distal canals. The teeth were accessed and distal canals located and their patency ensured. Micro-CT images were obtained, and 15 teeth with distal canal calcifications were selected. The volume of distal canals and calcifications were calculated from the micro-CT images before and after cleaning with the GentleWave system. Calcifications were observed in all thirds of the canals. Attached and free calcification were detected. Root canal volumes were slightly increased after GentleWave treatment, whereas the calcifications were completely or partially removed in all canals. Mean reduction percentage of calcification was 86.4 ± 3.9%, in individual canals from 60% to 100%. Calcifications in the distal canals of mandibular molars could be partially or completely removed by the multisonic cleaning system without instrumentation.

In-vitro analysis of maxillary first molars morphology using three dimensional Micro-CT imaging: considerations for restorative dentistry

PURPOSE

The aim of this study was to determine the differences between the positional relationship of the crown contour and the pulp chamber of left and right maxillary first molars, as well as their morphological characteristics by using micro-CT system with reconstruction from a volumetric rendering software.

MATERIALS AND METHODS

In total, 21 extracted maxillary first molars, including 11 left and 10 right teeth, were used. The positional relationship between the crown contour, pulp chamber and morphology of the teeth were investigated three-dimensionally by means of micro-CT imaging.

RESULTS

Closest distance of mesio-buccal pulp horn to enamel surface in mm was calculated as 2.5±0.20 mm for right and 2.29±0.17 mm for left teeth. This difference was statistically significant (p=0.017). The means of closest distance of disto-buccal pulp horn to enamel surface were also significantly different between left and right teeth (p=0.001). The mean pulp volumes of right side and left side teeth were, respectively, 32.94±3.19 mm³ and 33.71±2.82 mm³ but this difference was not statistically significant.

CONCLUSION

These results suggest that right and left maxillary first molars should be treated differently during preparation of cavities. Further studies must be done with larger samples as well as for other molar teeth in different populations to reveal the morphology of the molar for further considerations in restorative dentistry.