Abstract
PurposeVolumetric quantitative analyses of bone micromorphometry changes following orthodontic tooth movements are hardly standardizable. The present study aimed at validating and applying a novel microcomputed tomography (CT)-based approach that enables the segmentation of teeth and definition of a standardized volume of interest (VOI) around the roots to assess local bone micromorphometry.MethodsThe jaws of 3 untreated and 14 orthodontically treated mice (protraction of the upper right molar for 11 days with 0.5 N; untreated left upper molar) were scanned with a micro-CT. The first molars and the alveolar bone were segmented, and a standardized VOI was defined around the teeth. The bone volume per total volume (BV/TV) was assessed within the VOI, and BV/TV values were compared between contralateral sites in both untreated (method validation) and treated animals (method application).ResultsThe intraclass correlation coefficient of 0.99 revealed high reliability of the method. In the untreated animals, Bland–Altman analysis confirmed comparable BV/TV fractions (mean difference: −1.93, critical difference: 1.91, Wilcoxon: p = 0.03). In the orthodontically treated animals, BV/TV values were significantly lower at the test compared to the control site (test: 33.23% ± 5.74%, control: 41.33% ± 4.91%, Wilcoxon: p < 0.001).ConclusionWithin the limits of the study, the novel approach demonstrated the applicability to evaluate bone micromorphometry around teeth subjected to orthodontic treatment.
Highlights
Bone regeneration around teeth is a consequence of complex bone remodeling which involves a balance of resorption of mineralized bone and formation of new bone matrix [1,2,3]
Bland–Altman analyses confirmed high comparability of bone volume per total volume (BV/TV) around the left and right upper, and lower molars (Fig. 4). This finding is in line with the Wilcoxon signed rank test which did not reveal any significant difference in BV/TV values between the contralateral sites
The overall BV/TV values at the protracted upper right molars amounted to 33.23% ± 5.74%, whereas significantly higher values were identified at the untreated left side, i.e., 41.33% ± 4.91% (p = 0.001; Fig. 5)
Summary
The jaws of 3 untreated and 14 orthodontically treated mice (protraction of the upper right molar for 11 days with 0.5 N; untreated left upper molar) were scanned with a micro-CT. The bone volume per total volume (BV/TV) was assessed within the VOI, and BV/TV values were compared between contralateral sites in both untreated (method validation) and treated animals (method application). Methoden Die Kiefer von 3 unbehandelten und 14 kieferorthopädisch behandelten Mäusen (Protraktion des oberen rechten Molaren für 11 Tage mit 0,5 N; unbehandelter linker oberer Molar) wurden mit einem Mikro-CT gescannt. Bei den kieferorthopädisch behandelten Tieren waren die BV/TV-Werte in der Test- im Vergleich zur Kontrollgruppe signifikant niedriger (Test: 33,23 % ± 5,74 %, Kontrolle: 41,33 % ± 4,91 %, Wilcoxon-Test: p < 0,001). Schlussfolgerung Im Rahmen der Studie zeigte der neuartige Ansatz die Anwendbarkeit zur Bewertung der Knochenmikrostruktur um Zahnwurzeln von Molaren, die einer kieferorthopädischen Behandlung unterzogen wurden.
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