Developing and evaluating 3D Printed Resorbable PLLA Scaffold for Bone Regeneration – Divakar Karanth, David Puleo, Dolph Dawson, Lina Sharab

• This selection was significantly associated with provider type, with orthodontists using 0.5mm as their threshold at a higher rate than general dentists (67% vs 39%, p-value=0.0305), as well as with the number of Invisalign patients treated in the past 12 months (p-value=0.0316).

• Those who reported having treated greater than 100 patients considered 0.5 mm as their threshold more often than those who had treated 100 or fewer patients.

• When planning for this movement, general dentists were significantly more likely to select an optimized attachment (p-value=0.0001), whereas orthodontists were significantly more likely to select a gingivally beveled horizontal rectangular attachment (p-value<0.0001).

There was no clear agreement between clinicians on the percentage of patients for whom they experienced tracking issues when extruding maxillary lateral incisors.

• 63% of respondents indicated intervention by taking a refinement scan

• 19% indicated intervention via the bootstrap technique.

When asked about the timing of taking a refinement scan, orthodontists were more likely to indicate waiting until the end of the series while general dentists tended towards immediate refinement.

Thank you, SAO for honoring my work. It is truly a blessing to be able to join this amazing specialty, and I am excited to work alongside you as we strive to love, serve, empower, mentor, and impact our patients, colleagues, and others in our communities.

Mason

Developing and evaluating 3D Printed Resorbable PLLA Scaffold for Bone Regeneration.

Divakar Karanth1 David Puleo2 Dolph Dawson3

1, 4 Department of Oral Health Science, University of Kentucky, Division of Orthodontics, Lexington, United States 2 Department of Biomedical Engineering, University of Mississippi, Oxford, United States 3 Department of Oral Health Practice, University of Kentucky, Division of Periodontics, Lexington,

Lina Sharab4

The primary objectives of this research was to develop a 3D-printed scaffold for bone regeneration with poly (L-lactic acid) (PLLA), a biodegradable polymer that has piezoelectric properties and to evaluate critical characteristics essential for biologic use, such as the architecture of the 3D-printed scaffolds and their effects on cellular infiltration, attachment, and proliferation. The research was funded by an NIH pilot study grant.

PLLA scaffolds can be 3D printed using fused deposition modeling technology with an interconnected, porous microstructure. The surface morphology and microarchitecture were analyzed with scanning electron microscopy (SEM) and microCT, respectively. Crystallographic characterization was done by X-ray diffraction. Compressive modulus was determined with an electromechanical testing system. The piezoelectric potential generated upon mechanical distortion was characterized with the use of an oscilloscope. Hydrolytic degradation was measured as weight loss at 4, 8, and 12 weeks. MG63 osteoblastic cell proliferation on the scaffold was quantified with Cell Counting Kit-8 assay (CCK8) at 3, 7, 10, and 14 days. The cell coverage on the scaffolds was qualitatively evaluated with SEM and multiphoton microscopy (MPM). The morphology of the MG63 cells and their cytoskeletal architecture was assessed from the images obtained from the MPM.

The porosity of the scaffolds was 73%, with an average pore size of 450 µm and an average scaffold fiber thickness of 130 µm. The average compressive modulus was 244 MPa. The scaffolds generated an electric potential of 25 mV upon cyclic/repeated loading. X-ray diffraction revealed that during the 3D printing process the crystallinity of the as-supplied PLLA fiber was reduced from 27.5% to 13.9% by melting and extrusion. The PLLA scaffolds showed minimal hydrolytic degradation during the 3-month study period. The CCK8 assay revealed that the number of MG63 cells proliferating on the scaffolds increased rapidly until day 10. SEM and MPM images showed cell attachment and proliferation on and in the scaffolds with complete coverage by day 14. The PLLA scaffolds were successfully designed and printed. These successes validate the feasibility of using PLLA as a scaffold material and 3D printing as a method of fabricating scaffolds. The mechanical and piezoelectric properties of these PLLA scaffolds were satisfactory. The elastic modulus was comparable to that of trabecular bone, and the piezoelectric properties of the PLLA were retained after 3D printing. These scaffolds showed a very slow rate of degradation. The scaffolds were cyto-compatible; the osteoblastic cells adhered to the scaffolds and proliferated to form multiple layers. 3D-printed PLLA scaffolds showed promising properties akin to natural bone. The technique is worth investigating further for bone regeneration capabilities. Additional experiments are necessary in order to answer all questions thoroughly, such as in vivo animal experiments to study the host response to PLLA scaffold, the scaffold’s ability to regenerate bone, and biodegradability.