ABSTRACT
OBJECTIVES: This study was designed to evaluate the reliability of a semi-automatic segmentation tool for dento-maxillary osteolytic image analysis compared with manually defined segmentation in CBCT scans. METHODS: Five CBCT scans were selected from patients for whom periapical radiolucency images were available. All images were obtained using a ProMax® 3D Mid Planmeca (Planmeca Oy, Helsinki, Finland) and were acquired with 200-µm voxel size. Two clinicians performed the manual segmentations. Four operators applied three different semi-automatic procedures. The volumes of the lesions were measured. An analysis of dispersion was made for each procedure and each case. An ANOVA was used to evaluate the operator effect. Non-paired t-tests were used to compare semi-automatic procedures with the manual procedure. Statistical significance was set at α = 0.01. RESULTS: The coefficients of variation for the manual procedure were 2.5-3.5% on average. There was no statistical difference between the two operators. The results of manual procedures can be used as a reference. For the semi-automatic procedures, the dispersion around the mean can be elevated depending on the operator and case. ANOVA revealed significant differences between the operators for the three techniques according to cases. CONCLUSIONS: Region-based segmentation was only comparable with the manual procedure for delineating a circumscribed osteolytic dento-maxillary lesion. The semi-automatic segmentations tested are interesting but are limited to complex surface structures. A methodology that combines the strengths of both methods could be of interest and should be tested. The improvement in the image analysis that is possible through the segmentation procedure and CBCT image quality could be of value.
Subject(s)
Cone-Beam Computed Tomography/statistics & numerical data , Image Processing, Computer-Assisted/statistics & numerical data , Imaging, Three-Dimensional/statistics & numerical data , Osteolysis/diagnostic imaging , Periapical Diseases/diagnostic imaging , Cone-Beam Computed Tomography/methods , Humans , Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Pilot Projects , Reproducibility of Results , SoftwareABSTRACT
UNLABELLED: The Nickel-titanium (Ni-Ti) instruments superelasticity does not does not allow to anticipate rupture. AIM: This study evaluates the effect of electropolishing time on the rupture resistance in flexion fatigue of the endodontics Ni-Ti instruments. METHODS: 48 HeroShapers 6% 25/100 are divided into 4 groups of surface treatment (without electropolishing, with electropolishing of 70, 80 or 90 seconds). The surface of the instruments is observed under a scanning electron microscope. Each instrument is driving by an inGet control motor at 275 rpm and put on a fatigue bench (stainless steel pipe angled at 60 degrees with r = 10 mm). The number of turn before rupture is recorded by a specific meter. Data were analysed by analysis of variance and a Fischer probable least-square difference test (PLSD) at a significance level of 0.05. RESULTS: The mean number of rotation to failure in each group of instrument decreases (407 to 355 tours) with the increase of the electropolishing time. There were no statistically significant difference (p = 0, 3508) between the different groups. CONCLUSION: Electropolishing from 70 till 90 seconds improves the surface state without modifying the rupture resistance in flexion fatigue of triple helix endodontic instruments with 6% taper.
