Relative cortical bone density at the infrazygomatic crest area in adolescents: a CBCT-based analysis of correlation with cervical vertebral maturation

Abstract

In orthodontic treatment, microimplants provide critical anchorage, with cortical bone density being essential for implant stability. The infrazygomatic crest (IZC) is a widely used implantation site, but adolescents exhibit substantial variability in bone density due to individual growth differences. Cervical vertebral maturation (CVM) is a reliable indicator of skeletal growth, yet its correlation with infrazygomatic crest cortical bone density remains underexplored. This study aimed to evaluate relative cortical bone density at the IZC area in adolescents and assess its correlation with CVM to provide imaging-based references for clinical site selection of microimplants. Retrospective cone beam computed tomography data from 80 adolescents (20 subjects per Cvs stage: Cvs3–Cvs6) were enrolled for analysis. Three-dimensional reconstruction aligned the maxillary occlusal plane horizontally; the baseline was set at the mesiobuccal cusp tip of the left maxillary first molar. Relative cortical bone density was measured on the buccal cortex at heights of 13 mm, 15 mm, and 17 mm above baseline, across six mesiodistal layers from the second premolar to the second molar region. Relative cortical bone density ranged from 656 ± 136 rHU (relative HU, CBCT-derived grayscale values without phantom calibration) to 1244 ± 134 rHU. A marked difference in relative cortical bone density was observed between the Cvs4 and Cvs5 groups (rHU range shifted from 656 to 1000 in Cvs4 to 796–1172 in Cvs5; p < 0.01). Relative cortical bone density, which is positively correlated with CVM advancement, generally decreased distally and increased apically across most sites and stages. Layers 5–6 could not be measured in all Cvs3 and 4 Cvs4 patients due to incomplete maxillary second molar eruption. Two separate datasets were analyzed without missing data imputation: Layers 1–4 (full cohort, n = 20 per CVM group, total 80); Layers 5–6 (reduced cohort, 16 Cvs4, 20 Cvs5, 20 Cvs6, total 56). ANOVA and correlation analyses were conducted independently for each dataset. Exploratory site-specific Spearman analyses showed positive correlations between relative cortical bone density at all measurable sites and CVM advancement (correlation coefficients r = 0.555–0.731; p < 0.001). In this exploratory analysis, relative cortical bone density at the adolescent IZC was positively associated with CVM advancement, with a notable inter-cohort difference observed between the Cvs4 and Cvs5 stages. These rHU imaging data offer stage-matched radiographic references for the adolescent IZC area. Nevertheless, uncalibrated grayscale signals cannot reflect actual bone mechanical performance, and comprehensive anatomical assessment of additional indicators (cortical thickness, root proximity, maxillary sinus morphology, etc.) remains essential for microimplant site selection.

The authors' abstract, as published at the source. BMC Oral Health, 2026 · DOI ↗