Research Spotlight

Awad, A. N., S. H. Cho, M. J. Kesterke and J. H. Chen (2021). “Comparison of tensile bond strength of denture reline materials on denture bases fabricated with CAD-CAM technology.” J Prosthet Dent.

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STATEMENT OF PROBLEM: Studies that have analyzed the bond strength of resilient denture liners to milled denture bases are sparse, and the authors are unaware of research that has investigated the tensile bond strength of denture relining materials to 3D-printed denture bases. PURPOSE: The purpose of this in vitro study was to evaluate the tensile bond strength of both hard and soft denture reline materials on denture bases fabricated by 3D printing and computer-aided design and computer-aided manufacture (CAD-CAM) milling technology. MATERIAL AND METHODS: Injected, milled, and printed denture base specimens were fabricated (n=30) and bonded to 5 different denture reline materials: soft chairside reline (Coe Soft and PermaSoft), hard chairside reline (Tokuyama Rebase ii and Kooliner), and hard laboratory reline (ProBase Cold). Specimens of each reline material were divided into 5 groups (n=10) and were placed in distilled water for 24 hours before tensile testing. Maximum tensile stress values before failure were recorded, and the failure mode was also determined. The type of failure was analyzed by a scanning electron microscope. Statistics were analyzed with 2-way ANOVA and multiple comparison tests (α=.05). RESULTS: Overall, no statistically significant difference in tensile bond strength was found in the injected, milled, and printed denture groups. However, the printed denture base group demonstrated significantly lower values of tensile bond strength (P<.05) with PermaSoft, Tokuyama Rebase ii, and ProBase Cold groups than other denture base groups (milled and injected). The milled denture bases had the highest mean value of tensile bond strength with 4 of the 5 denture relining materials tested (Coe Soft, PermaSoft, Tokuyama Rebase ii, and Kooliner). No statistically significant difference (P>.05) was found among the injected, milled, and printed denture bases when relined with Kooliner. When comparing the denture reline type, the lowest values were seen with the soft chairside relining materials, and highest values with the hard laboratory reline material. Among the modes of failure, adhesive failures were observed predominantly with the printed denture base materials relined with soft chairside relining materials, while cohesive and mixed modes of failure were found in the milled and injected denture base groups. CONCLUSIONS: The printed denture bases had significantly lower tensile bond strength values than the injection and milled denture bases with the PermaSoft, Tokuyama Rebase ii, and ProBase Cold denture relines, while milled denture bases demonstrated the highest values of tensile bond strength for all chairside relining groups. In addition, the soft chairside relining materials showed the lowest tensile bond strength values regardless of the denture processing method with respect to the denture base type (injected, printed, and milled) compared with the hard relining materials.

Ma, W., H. Lyu, M. Pandya, G. Gopinathan, X. Luan and T. G. H. Diekwisch (2021). “Successful Application of a Galanin-Coated Scaffold for Periodontal Regeneration.” J Dent Res 100(10): 1144-1152.

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The nervous system exerts finely tuned control over all aspects of the life of an organism, including pain, sensation, growth, and development. Recent developments in tissue regeneration research have increasingly turned to small molecule peptides to tailor and augment the biological response following tissue loss or injury. In the present study, we have introduced the small molecule peptide galanin (GAL) as a novel scaffold-coating agent for the healing and regeneration of craniofacial tissues. Using immunohistochemistry, we detected GAL and GAL receptors in healthy periodontal tissues and in the proximity of blood vessels, while exposure to our periodontal disease regimen resulted in a downregulation of GAL. In a 3-dimensional bioreactor culture, GAL coating of collagen scaffolds promoted cell proliferation and matrix synthesis. Following subcutaneous implantation, GAL-coated scaffolds were associated with mineralized bone-like tissue deposits, which reacted positively for alizarin red and von Kossa, and demonstrated increased expression and protein levels of RUNX2, OCN, OSX, and iBSP. In contrast, the GAL receptor antagonist galantide blocked the effect of GAL on Runx2 expression and inhibited mineralization in our subcutaneous implantation model. Moreover, GAL coating promoted periodontal regeneration and a rescue of the periodontal defect generated in our periodontitis model mice. Together, these data demonstrate the efficacy of the neuropeptide GAL as a coating material for tissue regeneration. They are also suggestive of a novel role for neurogenic signaling pathways in craniofacial and periodontal regeneration.

Aminoshariae, A., A. Azarpazhooh, A. R. Diogenes, A. F. Fouad, G. N. Glickman, A. Kishen, A. M. Letra, L. Levin, R. S. Roda, F. C. Setzer, F. R. Tay and K. M. Hargreaves (2021). “Insights into the August 2021 Issue of the JOE.” J Endod 47(8): 1195-1197.

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Welcome to the August 2021 issue of the JOE. Here we share some of our favorite articles that are published in this issue of the Journal. We hope you look forward to reading these and other articles in the JOE.

Aminoshariae, A., A. Azarpazhooh, A. R. Diogenes, A. F. Fouad, G. N. Glickman, A. Kishen, A. M. Letra, L. Levin, R. S. Roda, F. C. Setzer, F. R. Tay and K. M. Hargreaves (2021). “Insights into the September 2021 Issue of the JOE.” J Endod 47(9): 1337-1339.

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Welcome to the September 2021 issue of the JOE. Here, we share some of our favorite articles that are published in this issue of the Journal. We hope you look forward to reading these and other articles in the JOE.

Chang, B., C. Ma, J. Feng, K. K. H. Svoboda and X. Liu (2021). “Dental Pulp Stem Cell Polarization: Effects of Biophysical Factors.” J Dent Res 100(10): 1153-1160.

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Dental pulp stem cells (DPSCs) have the potential to polarize, differentiate, and form tubular dentin under certain conditions. However, the factors that initiate and regulate DPSC polarization and its underlying mechanism remain unclear. Identification of the factors that control DPSC polarization is a prerequisite for tubular dentin regeneration. We recently developed a unique bioinspired 3-dimensional platform that is capable of deciphering the factors that initiate and modulate cell polarization. The bioinspired platform has a simple background and confines a single cell on each microisland of the platform; therefore, it is an effective tool to study DPSC polarization at the single-cell level. In this work, we explored the effects of biophysical factors (surface topography, microisland area, geometry, tubular size, and gravity) on single DPSC polarization. Our results demonstrated that nanofibrous architecture, microisland area, tubular size, and gravity participated in regulating DPSC polarization by influencing the formation of the DPSC process and relocation of the Golgi apparatus. Among these factors, nanofibrous architecture, tubular size, and appropriate microisland area were indispensable for initiating DPSC polarization, whereas gravity served as an auxiliary factor to the process of DPSC polarization. Meanwhile, microisland geometry had a limited effect on DPSC polarization. Collectively, this work provides information on DPSC polarization and paves the way for the development of new biomaterials for tubular dentin regeneration.