Repair of Class II Furcation Defects After a Reparative Tissue Graft Obtained From Extraction Sockets Treated With Growth Factors: A Histologic and Histometric Study in Dogs

The fusion of keratinized epithelium, an indication of early implant placement in the aesthetic area: an animal study

BACKGROUND

In the period of the early implant placement, the socket is mainly occupied by provisional matrix (PM). Keratinized epithelium (KE) is critical for primary wound closure. Although both KE and PM are important, the detailed relationship among migrating KE, PM formation and indication of the early implant placement is still unclear.

OBJECTIVE

This research aimed to locate a healing stage of KE with highest osteogenic PM formation after tooth extraction, which could be treated as the optimal time point for early implant placement.

MATERIAL AND METHODS

Mice were sacrificed on days 1, 2, 3, 4 and 6 after incisor extraction. Clinical, histological, and immunohistochemical evaluations of the extraction sockets were performed, and statistical analyses were conducted. We then inserted implants into the PM with the greatest bioactivity and observed its osseointegration pattern for 3, 10, 17 and 30 days.

RESULT

When KE fusion was reached, sockets were dominated by PM with the greatest expression of osteocalcin (OC, P < 0.05) and high levels of CD34 and Runx2. OC and Runx2 expression were positively correlated with KE coverage (P < 0.05). When the implant was inserted at 4 days' healing, the PM maintained its osteogenic ability, and osseointegration proceeded perfectly.

CONCLUSION

The migration of KE was correlated with the formation of highly osteogenic and angiogenic PM. And the fusion of KE could be treated as an indication for early implant placement.

Local Concentrations of TGF-β1 and IGF-1 Appear Determinant in Regulating Bone Regeneration in Human Postextraction Tooth Sockets

Healing after tooth extraction involves a series of reparative processes affecting both alveolar bone and soft tissues. The aim of the present study was to investigate whether activation of molecular signals during the healing process confers a regenerative advantage to the extraction socket soft tissue (ESsT) at 8 weeks of healing. Compared to subepithelial connective tissue graft (CTG), qRT-PCR analyses revealed a dramatic enrichment of the ESsT in osteogenic differentiation markers. However, ESsT and CTG shared characteristics of nonspecialized soft connective tissue by expressing comparable levels of genes encoding abundant extracellular matrix (ECM) proteins. Genes encoding the transforming growth factor-β1 (TGF-β1) and its receptors were strongly enriched in the CTG, whereas the transcript for the insulin-like growth factor-1 (IGF-1) showed significantly high and comparable expression in both tissues. Mechanical stimulation, by the means of cyclic strain or matrix stiffness applied to primary ESsT cells (ESsT-C) and CTG fibroblasts (CTG-F) extracted from the tissue samples, revealed that stress-induced TGF-β1 not exceeding 2.3 ng/mL, as measured by ELISA, in combination with IGF-1 up to 2.5 ng/mL was able to induce the osteogenic potential of ESsT-Cs. However, stiff matrices (50 kPa), upregulating the TGF-β1 expression up to 6.6 ng/mL, caused downregulation of osteogenic gene expression in the ESsT-Cs. In CTG-Fs, endogenous or stress-induced TGF-β1 ≥ 4.6 ng/mL was likely responsible for the complete lack of osteogenesis. Treatment of ESsT-Cs with TGF-β1 and IGF-1 proved that, at specific concentrations, the two growth factors exhibited either an inductive-synergistic or a suppressive activity, thus determining the osteogenic and mineralization potential of ESsT-Cs. Taken together, our data strongly warrant the clinical exploration of ESsT as a graft in augmentative procedures during dental implant placement surgeries.

The Role of GH/IGF Axis in Dento-Alveolar Complex from Development to Aging and Therapeutics: A Narrative Review

The GH/IGF axis is a major regulator of bone formation and resorption and is essential to the achievement of normal skeleton growth and homeostasis. Beyond its key role in bone physiology, the GH/IGF axis has also major pleiotropic endocrine and autocrine/paracrine effects on mineralized tissues throughout life. This article aims to review the literature on GH, IGFs, IGF binding proteins, and their respective receptors in dental tissues, both epithelium (enamel) and mesenchyme (dentin, pulp, and tooth-supporting periodontium). The present review re-examines and refines the expression of the elements of the GH/IGF axis in oral tissues and their in vivo and in vitro mechanisms of action in different mineralizing cell types of the dento-alveolar complex including ameloblasts, odontoblasts, pulp cells, cementoblasts, periodontal ligament cells, and jaw osteoblasts focusing on cell-specific activities. Together, these data emphasize the determinant role of the GH/IGF axis in physiological and pathological development, morphometry, and aging of the teeth, the periodontium, and oral bones in humans, rodents, and other vertebrates. These advancements in oral biology have elicited an enormous interest among investigators to translate the fundamental discoveries on the GH/IGF axis into innovative strategies for targeted oral tissue therapies with local treatments, associated or not with materials, for orthodontics and the repair and regeneration of the dento-alveolar complex and oral bones.

Platelet-rich fibrin in combination with decalcified freeze-dried bone allograft for the management of mandibular degree II furcation defect: A randomised controlled clinical trial

Background: Treatment of furcation involvement of molars with periodontal disease remains challenging and unpredictable. Platelet-rich fibrin (PRF) has received the attention of researchers due to its pleiotropic properties essential for periodontal wound healing. The osteoinductive property of demineralized freeze-dried bone allograft (DFDBA) has been successfully used in periodontal regeneration. Aim: The present study aimed to explore the effectiveness of PRF alone and with DFDBA in the treatment of mandibular degree II furcation defects in subjects with chronic periodontitis. Material and Methods: Patients treated were from the Department of Periodontology and Implantology, Institute of Dental Sciences, Bareilly. A total of 60 mandibular molars were treated with either open flap debridement (OFD) alone, [Formula: see text] combination or [Formula: see text] combination. The soft and hard tissue parameters such as vertical probing depth (VPD), vertical clinical attachment level (VCAL), gingival marginal level (GML), horizontal probing depth (HPD), vertical bone fill (VBF), horizontal bone fill (HBF) and furcation width (FW) were determined at baseline and 9 months postoperatively. A paired [Formula: see text]-test was conducted to assess the statistical significance between time period within each group for clinical and radiographic parameters. ANOVA and post-hoc Tukey's tests were also conducted for intergroup comparison of soft and hard tissue parameters. Statistical significance was set at [Formula: see text]. Results and Discussion: After 9 months, all treatment groups showed significant ([Formula: see text]) improvement in soft and hard tissue parameters, except GML in all the three groups and HBF and FW in the OFD group as compared to baseline. The mean VBF change was highest in the [Formula: see text] group ([Formula: see text]) mm, followed by that in the [Formula: see text] and OFD groups ([Formula: see text] and [Formula: see text][Formula: see text]mm, respectively). Conclusions: It was shown that both [Formula: see text] and [Formula: see text] combinations were significantly advantageous for the management of mandibular degree II furcation defects. However, the [Formula: see text] combination has significantly greater benefits than [Formula: see text] combination in terms of VBF.

Experimental and clinical studies on regenerative periodontal therapy

The recognition of a periodontal therapy as a regenerative procedure requires the demonstration of new cementum, periodontal ligament, and bone coronal to the base of the defect. A diversity of regenerative strategies has been evaluated, including root surface conditioning, bone grafts and bone substitute materials, guided tissue regeneration, enamel matrix proteins, growth/differentiation factors, combined therapies and, more recently, tissue-engineering approaches. The aim of this chapter of Periodontology 2000 is to review the research carried out in Latin America in the field of periodontal regeneration, focusing mainly on studies using preclinical models (animal models) and randomized controlled clinical trials. This review may help clinicians and researchers to evaluate the current status of the therapies available and to discuss the challenges that must be faced in order to achieve predictable periodontal regeneration in clinical practice.

Demineralized Dentin as a Semi-Rigid Barrier for Guiding Periodontal Tissue Regeneration

BACKGROUND

Guided tissue regeneration (GTR) is an accepted approach in the correction of periodontal bone loss. Nonetheless, the deficiencies of commonly applied absorbable membrane, such as flexibility and limited osteoconductive and osteoinductive capability, still leave much room for improvement. Thus, the feasibility of applying demineralized dentin tissue to improve the therapeutic effect of GTR in periodontal regeneration was explored.

METHODS

Demineralized dentin was harvested after acid treatment, and its physiochemical properties were assessed in terms of mineralization density, contact angle, three-point test, and cell attachment. Because of its similar characteristics with bone tissue, dentin that had been acid-treated for 6 hours was chosen to repair a periodontal defect using an induced-periodontitis canine model. Histologic measurements were taken to compare its therapeutic effects to an absorbable membrane group and an untreated group.

RESULTS

The demineralized dentin displayed continually decreased hardness and density as the acid etching time was prolonged. Enhanced attachment and spreading of bone marrow mesenchymal stem cells were observed on the 6-hour processed dentin. Furthermore, in the demineralized dentin group, more periodontal tissues were newly formed compared with the biomembrane and untreated groups.

CONCLUSION

Acid etching represents an easy and promising approach to obtain demineralized dentin with desirable properties, similar to bone, for clinical application to promote periodontal tissue regeneration.

Comparison of mesenchymal stem cells and autogenous cortical bone graft in the treatment of class II furcation defects in dogs

The purpose of this study was to compare the effectiveness of mesenchymal stem cells (MSCs) with platelet-rich plasma (PRP) as scaffold and autogenous cortical bone (ACB) graft with and without PRP in the regenerative treatment of class II furcation defects in dogs. The mandibular second, third, and fourth premolars (P2, P3, P4) and maxillary P3 and P4 of both sides in three dogs were selected for experimentation. Class II furcation defects (5 mm in height and 2 mm in depth) were surgically created. Five weeks after the first operation, scaling + root planning (group 1), PRP (group 2), ACB (group 3), combination of ACB/PRP (group 4), and combination of MSCs/PRP (group 5) treatments were performed during open flap debridement. The percentage of cementum and alveolar bone formation was evaluated by histomorphometric analysis after a healing period of 8 weeks. There was new cementum along with periodontal ligament and coronal growth of alveolar bone in all groups. Cementum formation was significantly higher in groups 3, 4, and 5 compared to the control group (P < 0.05) with no significant difference between groups 2, 3, 4, and 5. Alveolar bone formation was similar in all groups (P > 0.05). It can be concluded that periodontal regeneration with complete filling of class II furcation defects with cementum, alveolar bone, and periodontal ligament is obtained 8 weeks after ACB, ACB/PRP, and MSCs/PRP treatments; however, efficacy of none is higher than another.

Periodontal tissue engineering and regeneration: current approaches and expanding opportunities

The management of periodontal tissue defects that result from periodontitis represents a medical and socioeconomic challenge. Concerted efforts have been and still are being made to accelerate and augment periodontal tissue and bone regeneration, including a range of regenerative surgical procedures, the development of a variety of grafting materials, and the use of recombinant growth factors. More recently, tissue-engineering strategies, including new cell- and/or matrix-based dimensions, are also being developed, analyzed, and employed for periodontal regenerative therapies. Tissue engineering in periodontology applies the principles of engineering and life sciences toward the development of biological techniques that can restore lost alveolar bone, periodontal ligament, and root cementum. It is based on an understanding of the role of periodontal formation and aims to grow new functional tissues rather than to build new replacements of periodontium. Although tissue engineering has merged to create more opportunities for predictable and optimal periodontal tissue regeneration, the technique and design for preclinical and clinical studies remain in their early stages. To date, the reconstruction of small- to moderate-sized periodontal bone defects using engineered cell-scaffold constructs is technically feasible, and some of the currently developed concepts may represent alternatives for certain ideal clinical scenarios. However, the predictable reconstruction of the normal structure and functionality of a tooth-supporting apparatus remains challenging. This review summarizes current regenerative procedures for periodontal healing and regeneration and explores their progress and difficulties in clinical practice, with particular emphasis placed upon current challenges and future possibilities associated with tissue-engineering strategies in periodontal regenerative medicine.

Role of growth factors on periodontal repair

Regeneration of periodontal structures lost during periodontal diseases constitutes a complex biological process regulated among others by interactions between cells and growth factors. Growth factors are biologically active polypeptides affecting the proliferation, chemotaxis and differentiation of cells from epithelium, bone and connective tissue. They express their action by binding to specific cell-surface receptors present on various target cells including osteoblasts, cementoblasts and periodontal ligament fibroblasts. The observation that growth factors participate in all cell functions led to exogenous application during periodontal tissue repair aiming to their use as an alternative therapeutic approach to periodontal therapy. Cell types and cultures conditions, dose, carrier materials, application requirements are of critical importance in the outcome of periodontal repair. The purpose of this article is to review the literature with respect to the biological actions of PDGF, TGF, FGF, IGF and EGF on periodontal cells and tissues, which are involved in periodontal regeneration.