Effects of nanofiber scaffolds coated with nanoparticulate and micro-particulate FDBA on the morphology, adhesion and proliferation of human mesenchymal stem cells.

Background: Freeze dried bone allograft nanoparticles on a nanofiber membrane may serve as an ideal scaffold for bone regeneration. This study aimed to assess the biological behavior of human mesenchymal stem cells (MSCs) in terms of proliferation and adhesion to nanoparticulate and microparticulate freeze dried bone allograft (FDBA) scaffolds on poly-L-lactic acid (PLLA) nanofiber membrane. Methods: In this experimental study, PLLA nanofiber scaffolds were synthesized by the electrospinning method. The FDBA nanoparticles were synthesized mechanically. The FDBA nanoparticles and microparticles were loaded on the surface of PLLA nanofiber membrane. A total of 64 scaffold samples in four groups of n-FDBA/PLLA, FDBA/PLLA, PLLA and control were placed in 24-well polystyrene tissue culture plates; 16 wells were allocated to each group. Data were analyzed using one-way ANOVA and Bonferroni test. Results: The proliferation rate of MSCs was significantly higher in the nanoparticulate group compared to the microparticulate group at five days (p = 0.034). Assessment of cell morphology at 24 hours revealed spindle-shaped cells with a higher number of appendages in the nanoparticulate group compared to other groups. Conclusion: MSCs on n-FDBA/PLLA scaffold were morphologically more active and flatter with a higher number of cellular appendages, as compared to FDBA/PLLA. It seems that the nanoparticulate scaffold is superior to the microparticulate scaffold in terms of proliferation, attachment, and morphology of MSCs in vitro.

Sustained Release of Risedronate from PLGA Microparticles Embedded in Alginate Hydrogel for Treatment of Bony Lesions

Background: Inflammatory bone resorption in periodontitis can lead to tooth loss. Systemic administration of bisphosphonates such as risedronate for preventing bone resorption can cause adverse effects. Alginate hydrogel (ALG) and poly (lactic acid-co-glycolic acid) (PLGA) microparticles have been studied as drug delivery systems for sustained release of drugs. Therefore, the release pattern of risedronate from PLGA microparticles embedded with ALG was studied as a drug delivery system for sustained release of the drug, which can be used in local administrations. Methods: Risedronate-containing PLGA microparticles were fabricated using double emulsion solvent evaporation technique. Ionic cross-linking method was used to fabricate risedronate-loaded ALG. Risedronate-containing PLGA microparticles were then coated with ALG. The calibration curve of risedronate was traced to measure encapsulation efficiency (EE) and study the release pattern. Scanning electron microscope (SEM) imaging was carried out, and cell toxicity was examined using MTT assay. Statistical analysis of data was carried out using SPSS ver. 20 software, via one-way ANOVA and Tukey's tests. Results: SEM imaging showed open porosities on ALGs. The mean EE of PLGA microparticles for risedronate was 57.14 ± 3.70%. Risedronate released completely after 72 h from ALG, and the cumulative release was significantly higher (p = 0.000) compared to PLGA microspheres coated with ALG, which demonstrated sustained released of risedronate until day 28. Risedronate-loaded ALG showed a significant decrease in gingival fibroblasts cell viability (p < 0.05). Conclusion: Alginate-coated PLGA microspheres could release risedronate in a sustained and controlled way and also did not show cell toxicity. Therefore, they seem to be an appropriate system for risedronate delivery in local applications.

Evaluation of indocyanine-mediated photodynamic therapy cytotoxicity in human osteoblast-like cells: an in vitro study.

INTRODUCTION: Antimicrobial photodynamic therapy (aPDT) is an adjunctive non-invasive procedure for the management of periodontal tissue infection and deep periodontal pocket decontamination. However, the effects of this procedure on periodontal cells like osteoblasts that play a role in periodontal tissue repair and regeneration is not yet clear.

Histomorphometric Effects of 2% Risedronate Gel on Calvarial Bone Defects in Rabbits.

STATEMENT OF THE PROBLEM: Alveolar bone resorption associated with periodontal disease is a common finding and generally irreversible. It impairs mastication and causes esthetic problems for patients. Bisphosphonates are the most commonly used antiresorptive agents for bone diseases. PURPOSE: Considering the risk of bisphosphonate-related osteonecrosis of the jaw, this study aimed to assess the effect of 2% risedronate gel on calvarial bone defects in rabbits. MATERIALS AND METHOD: In this animal study, critical-size defects of 8mm were created in the calvaria of 20 New Zealand white rabbits. In group 1 (n=10), 2% risedronate gel was applied into the right side defect while the left side defect remained empty and served as control. In group 2 (n=10), placebo gel was applied into the right side defect, while the left side defect remained empty and served as control. Five rabbits in each group were sacrificed at 1month and the remaining five at 2 month, post-operatively, and tissue samples were collected for histomorphometric analysis. Histomorphometric assessments included bone fill, degree of inflammation, number of osteoblasts, number of osteoclasts, and foreign body reaction at the site. Data were statistically analysed using SPSS version 25 via the Dunn test and Kruskal-Wallis test. RESULTS: No bone remodeling was noted in any group at 1 month. The risedronate group showed significantly higher bone fill than the other groups after 2 months (p= 0.016). At 2 months, the number of osteoblasts was significantly higher in the risedronate group (p< 0.05). The groups were not significantly different in terms of inflammation score at 1 (p= 0.31) or 2 (p=0.69) months. Foreign body reaction was not observed in any group at any time point. No osteoclast was detected in any group at any time point. CONCLUSION: Risedronate gel showed superior efficacy with regard to regeneration of rabbit calvarial bone defects compared to the placebo and control groups.

Comparative Efficacy of Diode, Nd:YAG and Er:YAG Lasers Accompanied by Fluoride in Dentinal Tubule Obstruction.

Introduction: Recently, the management of dentin hypersensitivity by lasers has gained special attention. This study aimed to assess and compare the efficacy of the 980 nm diode, Nd:YAG and Er:YAG lasers accompanied by fluoride in dentinal tubule obstruction. Methods: Twenty sound single-rooted human teeth were used for this invitro study. Forty dentinal discs were prepared of the roots and etched with 6% citric acid. One layer of fluoride varnish was applied over their surface. The sections were randomly allocated into 4 groups. The control group received no laser irradiation. Group 2 underwent 980 nm diode laser irradiation with 0.5 W power. Group 3 underwent Nd:YAG laser irradiation with 0.5 W power and group 4 underwent Er:YAG laser irradiation with 0.5 W power. All samples were then inspected under a scanning electron microscope, and the number of obstructed dentinal tubules and the diameter of open dentinal tubules in the field were determined. One-way ANOVA and Tukey's test were used for data analysis at a significance level of 0.05. Results: All three laser types decreased the number of open dentinal tubules significantly compared to the control group (P<0.05). No significant difference was noted in dentinal tubule obstruction between the three laser groups (P>0.05). The diameter of open tubules in the three laser groups did not show a significant difference from that in the control group. Conclusion: All three types of lasers evaluated in this study can effectively obstruct the dentinal tubules.

Clinical and histological evaluation of increase in the residual ridge width using mineralized corticocancellous block allografts: A pilot study.

Background. Lateral ridge augmentation is conventionally accomplished by means of autogenous bone grafts. However, due to its complications, the application of autogenous bone graft substitutes, e.g. mineralized corticocancellous allograft, is ecommended. Methods. In the present study, twelve patients were included, with insufficient alveolar ridge widths in the designated sites for dental implant placement. During the primary surgery, mineralized corticocancellous block allografts were fixed in deficient sites with titanium screws and resorbable collagen membranes were used to cover the blocks. After a period of six months, a flap was raised and variations in ridge width values was measured. Finally, a micro-biopsy was obtained from the sites for histologic investigation prior to preparing them for subsequent implant placement. Results. All the applied blocks were incorporated into the underlying bone except for one. A statistically significant difference was seen between the average ridge widths before placing the allografts compared with that of implant placement stage (2.62±1.02 mm vs. 7.75±1.63 mm, respectively). Vital bone tissue was detected in all the histological specimens obtained from the interface of blocks and the underlying bone. Conclusion. The results suggest that mineralized corticocancellous block allografts might be used as scaffolds for bone growth and ridge width augmentation.

In Vitro Effect of Zingiber officinale Extract on Growth of Streptococcus mutans and Streptococcus sanguinis.

Background and Objectives. Tooth decay is an infectious disease of microbial origin. Considering the increasing prevalence of antibiotic resistance due to their overuse and also their side effects, medicinal plants are now considered for use against bacterial infections. This study aimed to assess the effects of different concentrations of Zingiber officinale extract on proliferation of Streptococcus mutans and Streptococcus sanguinis in vitro. Materials and Methods. In this experimental study, serial dilutions of the extract were prepared in two sets of 10 test tubes for each bacterium (total of 20). Standard amounts of bacterial suspension were added; 100ƛ of each tube was cultured on prepared solid agar plates and incubated at 37°C for 24 hours. Serial dilutions of the extract were prepared in another 20 tubes and 100ƛ of each tube was added to blood agar culture medium while being prepared. The mixture was transferred to the plates. The bacteria were inoculated on plates and incubated as described. Results. The minimum inhibitory concentration (MIC) was 0.02 mg/mL for S. mutans and 0.3 mg/mL for S. sanguinis. The minimum bactericidal concentration (MBC) was 0.04 mg for S. mutans and 0.6 mg for S. sanguinis. Conclusion. Zingiber officinale extract has significant antibacterial activity against S. mutans and S. sanguinis cariogenic microorganisms.