Regeneration of periodontal tissues: combinations of barrier membranes and grafting materials - biological foundation and preclinical evidence: A systematic review

Osteocytes and WNT: the Mechanical Control of Bone Formation

Mechanical loading is of pivotal importance in the maintenance of skeletal homeostasis, but the players involved in the transduction of mechanical stimuli to promote bone maintenance have long remained elusive. Osteocytes, the most abundant cells in bone, possess mechanosensing appendices stretching through a system of bone canaliculi. Mechanical stimulation plays an important role in osteocyte survival and hence in the preservation of bone mechanical properties, through the maintenance of bone hydratation. Osteocytes can also control the osteoblastic differentiation of mesenchymal precursors in response to mechanical loading by modulating WNT signaling pathways, essential regulators of cell fate and commitment, through the protein sclerostin. Mutations of Sost, the sclerostin-encoding gene, have dramatic effects on the skeleton, indicating that osteocytes may act as master regulators of bone formation and localized bone remodeling. Moreover, the development of sclerostin inhibitors is opening new possibilities for bone regeneration in orthopedics and the dental field.

Effect of platelet-rich plasma on the healing of intrabony defects treated with an anorganic bovine bone mineral: a pilot study

BACKGROUND

Periodontal therapy using the combination of platelet-rich plasma (PRP) and different grafting materials has been suggested as a modality to enhance the outcome of regenerative surgery. In most clinical studies, a barrier membrane was used to cover the defects, and thus, the effects of PRP may have been masked by the effects of the barrier. The data from controlled clinical studies evaluating the effect of regenerative therapy using various grafting materials with or without PRP are still limited. The purpose of this study was to clinically compare the healing of intrabony defects treated with either a combination of an anorganic bovine bone mineral (ABBM) and PRP to those obtained with ABBM alone.

METHODS

Thirty patients with advanced chronic periodontal disease and displaying one intrabony defect were randomly treated with PRP + ABBM or ABBM alone. The following clinical parameters were evaluated at baseline and 1 year after treatment: plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR), and clinical attachment level (CAL). The primary outcome variable was CAL.

RESULTS

No statistical significant differences in any of the investigated parameters between the two groups were observed at baseline. Healing was uneventful in all patients. In the PRP + ABBM group, mean PD decreased from 8.6 +/- 1.8 mm to 3.4 +/- 1.4 mm (P <0.001) and mean CAL changed from 9.9 +/- 1.7 mm to 5.3 +/- 1.8 mm (P <0.001). In the ABBM group, mean PD decreased from 8.5 +/- 2.0 mm to 3.2 +/- 1.3 mm (P <0.001) and mean CAL changed from 9.6 +/- 1.9 mm to 4.9 +/- 1.5 mm (P <0.001). CAL gains >or=3 mm were measured in 80% (12 of 15 defects) of cases treated with PRP + ABBM and in 87% (13 of 15 defects) of cases treated with ABBM alone. No statistically significant differences in any of the investigated parameters were observed between the two groups at the 1-year reevaluation.

CONCLUSIONS

Within the limits of the present study, it can be concluded that 1) at 1 year after regenerative surgery with PRP + ABBM and ABBM alone, significant PD reductions and CAL gains were found, and 2) the use of PRP failed to improve the results obtained with ABBM alone.

In vitro cellular responses to scaffolds containing two microencapulated growth factors

Growth factors play an important role in the complex cascade of tissue events in periodontal regeneration, although optimal methods of delivery remain to be identified. We hypothesize that multiple delivery of growth factors, particularly via a microparticle-containing scaffold, will enhance cellular events leading to periodontal regeneration. In this study, cellular responses of periodontal ligament fibroblasts (PDLFs) in scaffolds containing microparticles (MPs) loaded with either bone morphogenetic protein (BMP)-2, insulin-like growth factor (IGF)-1, or a mixture of both MPs were evaluated, and the dual-MP-containing scaffold exhibited the release of different proteins in a sustained and independent fashion. When PDLF-seeded scaffolds were cultured in a flow perfusion bioreactor, cell metabolism and proliferation of PDLFs were significantly increased within 3 days in all IGF-1-containing scaffolds compared with those in groups lacking IGF-1 and particulate delivery enhanced these effects between 3 and 7 days. The dual-MP-containing group showed the most positive results. Both the BMP-2-in-MP and IGF-1-in-MP groups showed greater effects of alkaline phosphatase activity, more osteocalcin and osteopontin production, and more calcium deposition compared with matched GF-adsorbed groups. All osteoblastic markers were at their highest in the dual-MP-containing group at all detected time points. The combined results suggest that our dual-MP-containing scaffold can be used as a cell vehicle to positively affect cell behavior, thus exhibiting the potential to be a candidate scaffold for future periodontal tissue engineering.