Effects of Periodontal Cell Grafts and Enamel Matrix Proteins on the Implant–Connective Tissue Interface: A Pilot Study in the Minipig

Abstract

We have developed an experimental model to help identify and characterize factors necessary for periodontal connective tissue attachment formation on dental implants. In this pilot study, we report the effect of autogenous periodontal cell grafts, with and without the a pplication of enamel matrix derivative (EMD), on the implant-connective tissue interface. Periodontal ligament (PDL) and gingival connective tissue (GCT) cultures were established from an adult minipig. Implants were placed in osteotomies prepared with exaggerated countersinks that served as recipient sites for autogenous cell grafts in bilateral edentulated posterior mandibular sextants. In addition, 1 side received an application of EMD before placement of the autogenous cell grafts. A bioabsorbable membrane covering the coronal portion of the implants was placed before closure. After 8 weeks, quantitative histomorphometric and qualitative light microscopic analyses revealed that the implants that received gelatin vehicle alone were surrounded by bone, whereas the implants that received GCT cell grafts were mostly surrounded by fibrous connective tissue. In contrast, implants that received PDL cells without the application of EMD demonstrated good bone contact, but strands of epithelium were observed in the implant-connective tissue interface. Implants that received PDL cells and EMD also had good bone contact but without evidence of epithelium. A cementum-like interface was not observed in any of the groups. Results of this pilot study suggest that EMD and the type of cell populations present in the implant wound-healing environment may alter the implant-connective tissue interface.

Experimental Animal Models in Periodontology: A Review

“…Five studies have reported mini-pigs for research, mainly related to dental implant surgery and periodontal regeneration by enamel matrix derivatives [113, 114], as well as the effects of dental lasers on periodontal healing [115]. …”

Biological mediators and periodontal regeneration: a review of enamel matrix proteins at the cellular and molecular levels

“…In contrast, healing periods of 6 weeks did not demonstrate any beneficial effects of EMD treatment on bone formation around titanium implants placed in femurs and tibia of rats (Franke‐Stenport & Johansson 2003). Craig et al (2006) reported that transplantation of porcine PDL cells with EMD before insertion of metal implants into the mandible of minipigs led to good bone‐to‐implant contact, whereas omitting the EMD resulted in good bone‐to‐implant contact with strands of epithelial cells in the implant–connective tissue interface.…”

Soft Tissue Attachment to Titanium Implants Coated with Growth Factors

“…5 Similarly, coating titanium alloy with laminin-5 has been found to enhance gingival epithelial cell attachment and hemidesmosome assembly. 36 Two recent in vivo studies provide evidence that microtexturing of implant surfaces can influence the soft tissue response of peri-implant tissues around implants with a machined surface, acid-etched surface, or an oxidized and microporous TiO 2 layer. 8,9 In the present study, coating of the TiUnite surface of titanium implants with Emdogain® or rhPDGF coating did not affect the orientation of the fibroblasts or collagen fibers in the encapsulating connective tissue layer.…”