Long-term analysis of calvarial growth in rabbits.

Knowledge of normal suture development is vital to the understanding of aberrant suture growth. The purpose of the present investigation was to comprehensively analyze the complete growth period of the calvarium in rabbits, thus including increment beyond maturity (20 weeks). 5 male New Zealand white rabbits were studied from age 14 d until cessation of cranial growth using roentgen stereophotogrammetry. Growth at the coronal and sagittal sutures seemed completed at 8 months of age, while the frontonasal suture still exhibited minute expansion at the end of the observation period (13 months). Coronal suture growth decelerated linearly relative to the frontonasal suture. Bone separation at the sagittal suture varied less with age as compared to that of the transverse sutures. A brief period of growth reduction, pertaining to all cranial vault sutures, during the second interval (d 35-42) corresponded well with cessation of weaning. Balanced growth fluctuations were frequent. Spatial alterations correlated well with longitudinal increments as to growth arrest. Changes of rotational direction during active growth as well as, in some cases, widespread variations between individuals demonstrated the flexibility of angular calvarial development. In conclusion, the registered growth activity beyond maturity craves consideration during the evaluation of experimental changes of sutural growth so as not to disregard compensatory adjustments.