Lamina dura thickening in patients on antiresorptive therapy as a radiographic risk indicator of MRONJ: a retrospective longitudinal cohort study.

AIMS: This study investigated whether antiresorptive drug (ARD) therapy is associated with lamina dura (LD) thickening, defined as a radiographic increase in the thickness of the normally thin, radiopaque cortical line surrounding the tooth root. It further evaluated whether LD thickening serves as a radiographic marker and risk indicator for medication-related osteonecrosis of the jaw (MRONJ).

METHODS

Panoramic radiographs from 65 ARD-treated patients (University Hospital Leuven) and 65 age- and sex-matched controls were analysed. Inclusion criteria were prior oncological diagnosis, high-dose intravenous ARD, and radiographs before and after therapy. Three blinded oral and maxillofacial radiologists categorised LD appearance into four grades: (0) not/barely visible, (1) normal, (2) mild thickening, (3) marked thickening. Group differences and longitudinal changes were evaluated using appropriate non-parametric and time-to-event analyses.

RESULTS

Among 130 participants, LD-thickness remained stable in controls but increased in ARD-treated patients (p < 0.001). Within the ARD group, LD thickening changed over time (p < 0.001): 30.6% showed no change, 55.4% developed mild thickening, and 13.8% marked thickening. Controls showed minimal change (p = 0.011), with 9.2% developing mild thickening. Kaplan-Meier analysis estimated a median time to LD thickening of 27 months, with a higher thickening probability in ARD-treated patients than controls (p < 0.001). LD thickening was not directly associated with MRONJ (p = 0.39).

CONCLUSION

LD thickening is strongly associated with long-term ARD exposure and shows progressive changes. Although not directly associated with MRONJ in this cohort, it may still represent a potential risk indicator; warranting confirmation in further studies.