Effect of voxel size and partial volume effect on accuracy of tooth volumetric measurements with cone beam CT

Cemental and alveolar bone defects after chronic exposure to amoxicillin in rats (histopathologic and radiographic study)

OBJECTIVES

This study aimed to shed new light on the potential detrimental effects on cementum and adjacent alveolar bone after chronic exposure to amoxicillin.

METHODS

Six pregnant adult Albino rats were equally divided into two groups. Saline solution and amoxicillin (100 mg/Kg) were given to rats of control and amoxicillin group, respectively from the 13th to the 21st day of pregnancy. The same treatment was given to the pups till the 42nd day. The cementum of the first molar teeth and the surrounding alveolar bone were examined qualitatively by histopathological and scanning electron microscope, and quantitatively by energy dispersive X-ray spectroscopy and cone beam computed tomography.

RESULTS

Amoxicillin group depicted cemental and alveolar bone defects along with resorption lacunae. Statistically significant decreases in calcium and calcium/phosphorus ratio in cementum and in calcium only in alveolar bone were evident (p ≤ 0.05). Overall cementum and alveolar bone densities also showed statistically significant decreases (p ≤ 0.05).

CONCLUSION

Chronic amoxicillin administration displayed destructive effects on cementum and the surrounding alveolar bone which may disturb tooth attachment integrity. Therefore, it is recommended to minimize its haphazard usage during pregnancy and early childhood.

Effects of Exposure Parameters and Voxel Size for Cone-Beam Computed Tomography on the Image Matching Accuracy with an Optical Dental Scan Image: An In Vitro Study

This study is aimed at assessing the effects of exposure parameters and voxel size for cone-beam computed tomography (CBCT) on the image matching accuracy with an optical dental scan image. CBCT and optical scan images of a dry human mandible were obtained. Different CBCT settings were used: tube voltage, 60, 80, and 100 kVp; tube current, 6 and 8 mA; and voxel size, 100, 200, and 300 μm. Image matching between the CBCT and optical scan images was performed using implant planning software by dental professionals (n = 18). The image matching accuracy in each combination of CBCT settings was evaluated by assessing the linear discrepancy between the three-dimensionally reconstructed radiological image and the registered optical scan image using an image analysis software program. The Kruskal-Wallis test and a post hoc Mann–Whitney U test with Bonferroni correction were used to compare the accuracy of image registration between the groups (α = 0.05). Overall, the image matching accuracy was not significantly different between tube voltage and current settings; however, significantly higher image registration errors were found at the combination of 100 kVp tube voltage/8 mA tube current (F = 8.44, P < 0.001). Changes in voxel sizes did not significantly interfere with the image registration results. No interaction was found among voltage, current, and voxel size in terms of image registration accuracy (F = 2.022, P = 0.091). Different exposure parameter settings in tube voltage and tube current did not significantly influence the image matching accuracy between CBCT and optical dental scan images; however, a high radiation dose could be inappropriate. The image matching accuracy was not significantly affected by changing the voxel sizes of CBCT.

Volumetric measurements of mandibular incisor root resorption following Forsus FRD EZ2 and Bionator appliance treatment using cone-beam computed tomography: A preliminary study

Objectives:

Root resorption is one of the frequently encountered problems in orthodontic treatments. The effects of functional appliances on root resorption have not been clearly demonstrated. The aim of this study was to compare volumetric root resorption of mandibular incisors after Bionator and Forsus appliance treatment using cone-beam computed tomography (CBCT).

Materials and Methods:

The study sample (n = 30) was selected from Class II div. 1 mandibular retrognathia patients treated with the Bionator and Forsus appliances. The first CBCT scans were taken before Bionator use and after 6 months. In the Forsus group, the first CBCT scans were taken before Forsus appliance use and after an overcorrected Class I relationship was obtained. The mean treatment time with the Forsus appliance was 5 ± 1.2 months. Mimics software was used for segmentation and volumetric measurements of mandibular incisor teeth root resorption.

Results:

In the Bionator group, statistically significant root volume loss was not found. In the Forsus group, the differences between before and after the treatment were not statistically significant for teeth 41, 31, and 32 (P > 0.05), whereas the difference was statistically significant for the lower right second incisor (P < 0.002). The percentage of volume loss (%) and root volume loss (mm3) was not statistically significant between groups.

Conclusions:

Following functional treatment with the Bionator and Forsus, statistically significant difference was not found between groups for mandibular incisor root resorption.

Evaluation and comparison of root resorption between tooth-borne and tooth-tissue borne rapid maxillary expansion appliances: A CBCT study

OBJECTIVE

To compare volumetric root resorption after rapid maxillary expansion (RME) between tooth-borne and tissue-borne appliances using CBCT. Repair in resorption cavities after 6 months of fixed retention was also compared.

MATERIALS AND METHODS

A sample of 33 subjects were randomly divided into two groups: Hyrax (n  = 16) and Haas (n = 17). CBCT scans were taken 6 months before expansion, immediately after expansion, and 6 months after fixed retention. Mimics Innovation V 16.0 software was used for segmentation and volumetric measurement of 198 teeth. Bland-Altman plots, independent samples t test, repeated measures analysis of variance, and the Friedman test were used for statistical analysis.

RESULTS

Differences in root resorption after RME and repair after retention were not significant between the hyrax and Haas appliances or between male and female. Significant differences were found between preexpansion and postexpansion root volumes in the first premolars and molars--even in unattached second premolars. When the percentage of root volume loss is considered, no significant difference was found between the first premolar, second premolar, and first molar. Volumetric changes after 6 months of retention were not statistically significant.

CONCLUSIONS

More resorption was observed in the Hyrax expander group. But it was not statistically significant. Repair was observed after 6 months of retention. Heavy RME forces affected premolars and molar similarly.