Root-end Filling Materials Alter Fibroblast Differentiation

/Home/Dental Care and Treatment/Root Canal (Endodontics)/Root Canal (Endodontics) Articles

Root-end Filling Materials Alter Fibroblast Differentiation
2004
S. Bonson1, B.G. Jeansonne1, and T.E. Lallier2,*
Journal of Dental Research

© 2004 International and American Associations for Dental Research

1 Department of Endodontics, Center of Excellence in Oral and Craniofacial Biology, Louisiana State University Health Science Center, School of Dentistry; and
2 Department of Cell Biology and Anatomy, Center of Excellence in Oral and Craniofacial Biology, Box 128, Louisiana State University Health Science Center, School of Dentistry, 1100 Florida Avenue, New Orleans, LA 70119;

* corresponding author, tlalli@lsuhsc.edu

ABSTRACT

Root-end filling materials are commonly used following endodontic surgical procedures; however, their effect on adjacent soft tissues is poorly understood. We predict that, due to the differences in their chemical composition, these materials will have profoundly different effects on the survival and differentiation of fibroblasts. Many of the root-end filling materials examined were initially cytotoxic to both PDL and gingival fibroblasts in co-culture experiments; however, this was reduced after the materials were washed in either mineral trioxide aggregate (MTA) or hybrid ionomere composite resin (HICR) for 2 wks. Additionally, PDL fibroblasts displayed enhanced proliferation on MTA and survival on amalgam when compared with gingival fibroblasts. MTA preferentially induced alkaline phosphatase expression and activity in both PDL and gingival fibroblasts. In contrast, HICR inhibited alkaline phosphatase expression and activity. In addition, MTA and HICR repressed pleiotrophin in PDL fibroblasts, while HICR repressed periostin in both fibroblasts. Thus, root-end filling materials differentially affect periodontal fibroblast differentiation. Abbreviations: mineral trioxide aggregate (MTA), zinc-oxide eugenol cement (ZOEC), hybrid ionomer composite resin (HICR), reverse-transcriptase polymerase chain-reaction (RT-PCR).


KEY WORDS: periodontal ligament Ô gingival fibroblast Ô cementogenesis Ô endodontics

INTRODUCTION

Surgical endodontic therapy is performed to prevent egress of irritants from the root canal system into the periradicular tissues (Torabinejad et al., 1995c). This is accomplished through surgical exposure of the root, resection of the apical portion, and placement of a root-end filling material to seal the canal system. An ideal material to seal the root-end cavity should prevent leakage (Gartner and Dorn, 1992). It should have dimensional stability, adherence to the walls of the cavity, resistance to resorption, and moisture resistance (Torabinejad et al., 1995a); it should also be non-toxic and biocompatible to promote healing (Torabinejad et al., 1995c).

For many years, amalgam was accepted as the material of choice for endodontic surgery, but its use came into question when SEM studies showed gaps between the amalgam and the root canal wall, and when concerns about mercury toxicity developed (Dorn and Gartner, 1990). Zinc-oxide eugenol cements (ZOEC) have been suggested as alternate root-end filling materials (Torabinejad and Pitt Ford, 1996). ZOEC offers a better seal than amalgam and is not resorbable. It has high compressive and torsional strength, low solubility, is radiopaque, and has a neutral pH (Oynick and Oynick, 1978), and, in clinical examinations, the success rate was 75% for amalgam and 95% for ZOEC cement (Dorn and Gartner, 1990). A hybrid ionomer composite resin (HICR) (Geristore?, DenMat, Santa Maria, CA, USA) has been shown in clinical trials to be effective in restoring subgingival areas (Shuman, 1999). It is well-tolerated when used for perforation repairs, and evidence of tissue attachment has been demonstrated histologically (Dragoo, 1997).

A more recently developed material, mineral trioxide aggregate (MTA), has also been advocated for use as a root-end filling material. The principle components of MTA are tricalcium silicate, tricalcium aluminate, tricalcium oxide, and silicate oxide (Torabinejad et al., 1995c). The sealing ability of MTA is superior to that of amalgam and ZOEC, and its seal was not adversely affected by blood contamination (Torabinejad et al., 1993, 1994, 1995b). It was also less cytotoxic than amalgam, ZOEC, and IRM (Torabinejad et al., 1995b). MTA has also been demonstrated to support cementum deposition (Torabinejad et al., 1995d) with reduced inflammation (Koh et al., 1998; Torabinejad et al., 1998).

Fibroblasts are the predominant resident cell type of the periodontal connective tissue (Bartold et al., 2000). Gingival fibroblasts maintain the integrity of gingival connective tissue, while periodontal ligament (PDL) fibroblasts with specialized functions are responsible for the formation and maintenance of periodontal ligament fiber attachments as well as repair, remodeling, and regeneration of the adjacent alveolar bone and cementum (Boyko et al., 1981). Cementogenesis is similar to osteogenesis, requiring the regulated action of specialized cells (cementoblasts and osteoblasts) and potentially fibroblasts (Saygin et al., 2000). While PDL-derived cells and osteoprogenitors are possible precursors for cementoblasts, their origins, formation, and orientation are not well-understood (Pitaru et al., 1994).

The purpose of the present study is to assess the effects of these root-end filling materials on the survival of and osteogenic gene expression in PDL and gingival fibroblasts. We also examined the effects of these materials on cellular alkaline phosphatase activity as a potential indicator of cementogenesis.

Complete article may be viewed online.