Date of Completion


Embargo Period



Drs. Ivo Kalajzic and Bina Katechia

Field of Study

Dental Science


Master of Dental Science

Open Access

Campus Access


Identification of the mesenchymal stem cell (MSC) population capable of giving rise to odontoblasts during growth-repair is critical for the advances in pulp therapy and bioengineering. Despite significant progress in the identification of MSCs within the mouse incisors in vivo, little is known about MSCs in molars. Murine molars, unlike incisors, are similar to human dentition (lacks continuous growth). The goal of the present study was to examine the roles of the Gli1, a downstream effector of the sonic hedgehog signaling in reparative dentinogenesis. Using lineage-tracing and Gli1-CreERT2;Ai9 reporter mice and experimental pulp exposure in molars, we examined the contribution of Gli1-tdTomato+ cells to second generation of odontoblasts for reparative dentinogenesis.

Four-week-old Gli1CreERT2;Ai9 mice were injected intraperitoneally with oil/vehicle (VH) or Tamoxifen (TM) twice at 24h interval. Experimental pulp exposures were created in maxillary first molars and animals were sacrificed at various timepoints. Frozen sections from maxillary arches were processed for various analyses to examine the contribution of Gli1-tdTomato+ cells to reparative dentinogenesis. The uninjured/injured molars from VH-injected mice served as controls for spontaneous Cre-activation. Pulp exposure resulted in increased percent area of Gli1-tdTomato+ cells in the pulp as early as 4d as compared to controls. Newly mineralized calcified bridge was formed at 4w after injury. Gli1-tdTomato+ and Col2.3-GFP+ cells were detected lining the calcified bridge. Very few cells co-expressing both transgenes were seen lining the dentinal bridge. These results indicated a modest, if any, contribution of Gli1-tdTomato+ cells to second generation of odontoblasts/osteoblasts expressing Col2.3-GFP+ and secreting reparative dentin.

Major Advisor

Dr. Mina Mina

Available for download on Friday, June 23, 2028