The Effect of Single Dose Bisphosphonate on Tooth Eruption

Objectives: Bisphosphonates (BPs) are anti-resorptive agents known to increase bone volume by inhibiting osteoclastic activity. Although BPs have historically been used extensively to treat adults with various bone disorders, there has been a dramatic increase over the past decade in their use in children with osteogenesis imperfecta (OI). Still, the effect of BPs on the developing dentition is not well understood. In this study, we evaluated the effect of zoledronic acid (ZA), a potent BP, on the formation and eruption of molars in newborn rats.
Methods: 40 seven-day old Sprague Dawley rats were given a single injection of either 0.1mg/kg ZA or saline as control, and the eruption timing and sequence of three molars was observed clinically. This low-dose single injection is equivalent to the dose used in the treatment of OI patients. Groups of rats were sacrificed at regular intervals and both maxillae and mandibles underwent MicroCT analysis.
Results: 1^st, 2^nd, and 3^rd molars in ZA-treated rats erupted at or around days 62, 41, and 35 respectively. The controls had molars that erupted normally at days 18, 22, and 35 respectively. Note that in ZA-treated rats, molars erupted in reverse order, with the 3^rd molar erupting on time, and 1^st and 2^nd molars significantly delayed. MicroCT analysis showed that the 1^st and 2^nd molars had already begun the eruption process at the time of ZA administration, while the 3^rd molar tooth bud had not yet completed formation.
Conclusions: BP administration in children may result in a significant delay in tooth eruption. This inhibiting effect appears to be dependent on the developmental stage of the dentition, with an increased effect on teeth that are undergoing active eruption. Thus, the timing of BP administration in children needs to be carefully considered with the ongoing dental development of the patient.