Background 
Insufficient bone volume is one of the major challenges encountered by dentists after dental implant placement. Recently, there are
many studies on going about three-dimensional bone grafts materials. Three-dimensional bone graft material can overcome the
weakness of conventional particulate bone grafting materials. Customized three-dimensional polycaprolactone (3D PCL) scaffold
implant fabricated with a 3D bio-printing system to facilitate rapid alveolar bone regeneration.

Aim/Hypothesis
This study aimed to evaluate a customized polycaprolactone (PCL) scaffold and PCL/b-tricalcium phosphate (b-TCP)
scaffold with human bone morphogenetic protein-2 (rhBMP-2) fabricated using a three-dimensional (3D) bioprinting system for
alveolar bone reconstruction in large animal model.

Materials and Methods (1000 characters maximum)
Scaffold characteristics : The PCL scaffolds were designed by CAD/CAM and manufactured using a 3D bioprinting system. Four
types of scaffolds were produced ; PCL alone (PCL), PCL and &#946;-TCP blend (PCL/TCP), PCL with rhBMP-2 (PCL/BMP), and
PCL and b-TCP blend with rhBMP-2 (PCL/TCP/BMP).
Animal experiments : Four adult, male beagle dogs were used. Both the mandibular second and third premolars were extracted and a
three month healing period was allowed. A standardized rectangular bone defect, 10.0 × 5.0 × 5.0mm size was created on the
alveolar ridge using a surgical bur. After surgery, the animals were examined by computed tomography (CT) under general
anesthesia.
After 2 weeks, surgical re-entry was performed to implant the 3D fabricated scaffolds. The 3D scaffolds were fixed with a fixation
screw and all defect sites were covered with a resorbable membrane. 12 weeks later, beagles were sacrificed and micro CT
examination and Histology & histomorphometric analysis were performed.

Resultats 
Histologically, There was no noticeable new bone formation inside of scaffold. Instead little new bone formation was observed in the
space between the scaffold and alveolar bone.
Histomorphometrically, the new bone area of PCL/BMP/TCP group was significantly higher than that of PCL/BMP group(p<0.05). And
BMP groups were higher than non-BMP groups in new bone ratio and bone volume, but there was no significant difference.
Interestingly, Micro-CT analysis revealed that remained scaffold ratio of TCP groups were lower than non-TCP groups. It showed TCP
groups have higher absorptive tendency than non - TCP groups although there was no significant difference.

Conclusions and Clinical Implications 
PCL is easy to manipulate for fabrication of customized scaffolds and it also has excellent mechanical strength. The PCL/TCP
composite scaffolds combined with rhBMP-2 were suitable to allow new bone formation. It can be concluded that TCP has ability to
continually release rhBMP-2 as a reservoir. And rhBMP-2 can accelerate and promote new bone formation.
For general use of PCL scaffold as bone graft materials, strategies for the direct bone contact to PCL is needed in further study.

Alveolar bone reconstruction using a 3D bioprinting PCL beta-TCP scaffold with rhBMP-2