Rh-PDGF vs EMD for Treatment of Intra-bony Defects

Alveolar bone crest is considered normal when it is found at a distance of 0.4- 1.97mm from the cementoenamel junction (CEJ) of the tooth. Chronic inflammation resulting from periodontal disease (PD) may lead to change in this architecture and formation of osseous defects. The variation in the form of these defects may be influenced by the occlusal stresses that the tooth is subjected to or the original form of the alveolar process in a localized area.

While Glickman chose to classify the osseous defects into "Osseous craters, intra-bony defects, bulbous osseous contours, hemi-septa, inconsistent margins and ledges"; Pritchard classified them as "interproximal craters, inconsistent margins, hemi-septa, furca invasions, intra-bony defects and a combination of these defects". Identifying the type of defect is of utmost importance. Intra-bony defects found in the interproximal areas can be one-wall, two-walls, or three-walls defects, depending on how many walls are remaining. On the other hand, when the inter-radicular bone is lost, its commonly classified as grade I, grade II, or grade III furcation.

Successful regeneration of the intra-bony defects will be accompanied by clinical attachment gain, decreased pocket depth, radiographic bone height gain, and improved periodontal health, to reach this goal, several types of bone grafts, membranes, biologics and/or combinations, have been investigated for potential application and, they proved success over short- and long-term.

Flemming et al. 1998, tested the bone gain following open flap debridement (OFD) versus allogeneic bone graft. The group that received allogenic bone graft had higher bone gain compared to the OFD group at 6 months (2.2mm vs 1.2mm) and 3 years (2.3mm vs 1.1mm) (P \<0.05). Comparable results were found when A. Sculean et al 2004, tested CAL gain when enamel matrix proteins (EMD) was used versus OFD; having 1.3mm of CAL gain at 5 years when the latter was used versus 2.9mm when the former was used (p\<0.001). Eickholz et al. 2004, tested the use of bioabsorbable membrane for the treatment of intra-bony defects with guided tissue regeneration. Attachment height gain was stable at 12- and 60-months follow up (3.5mm and 2.2mm). In a case series, Kim et al. compared the clinical attachment gain in 12 pairs of intra-bony defects in 12 subjects. One side was randomly assigned to receive GTR with a bioabsorbable membrane (Polyglactin) (control), while the contralateral received non-resorbable membrane (e-PTFE) (test). Both groups yielded significant clinical attachment gain at 6 (C6 and T6) and 60 months (C60 and T60), (C6: 2.6 ± 1.4 mm; C60: 1.6 ± 1.5 mm; T6: 3.0 ± 1.7 mm; T60: 3.0 ± 0.7 mm).

Emdogain is a biologic material that consists of hydrophobic enamel matrix proteins extracted from developing embryogenic enamel of porcine origin. It was first tested on monkeys for ability to regenerate buccal dehiscence defects and resulted in complete regeneration of the defect. It was later used in conjunction with Modified Widman Flap (MWF) and compared to MWF with placebo, for the regeneration of intra-bony defects in human subjects. At 36 months, the EMD group yielded significantly higher bone gain (2.2 mm vs 1.7 mm), respectively.

Platelet derived growth factors (PDGF) is a human serum polypeptide growth factor, it is a potent mitogen for cells of mesenchymal origin (e.g., fibroblasts), it stimulates collagen synthesis, chemotaxis of fibroblasts and production of insulin-like growth factors (IGF). It has been tested both in vitro and in vivo, it has proved potential for promoting soft tissue wound repair, and when used in periodontal defects, it stimulated healing with new bone and cementum formation, and a deposition of a continuous layer of osteoblasts was noticed lining the newly formed bone.

Based on the above evidence, it is now clear that different techniques and biomaterials can be used for periodontal regeneration. It is the purpose of the current study, to investigate the effect of rh-PDGF (test) in its commercial form (GEM21) and enamel matrix derivatives in its commercial form (EMD) (control) in combination with allografts for the treatment of periodontal defects in one-wall and two-walls intra-bony defects in human subjects.