Root surface etching at neutral pH promotes periodontal healing

Abstract

The purpose of the present investigation was to examine whether an etching agent operating at neutral pH (EDTA) can enhance healing compared to a low pH etching agent (citric acid) in an animal model. Maxillary molars and premolars, in total 32 teeth, in 4 monkeys were divided between test (EDTA or citric acid treatment) and matched control groups. Periodontal surgery on both palatal and buccal roots using the dehiscence model was performed with or without root surface etching. Healing results were evaluated histomorphometrically after 8 weeks. The statistically significant differences between EDTA treated surfaces (n=15) and control surfaces (n=11) were approximately 10% less failure (gingival recession and periodontal pocket), 10 to 15% more total histological attachment (long epithelial junction, connective tissue and reparative cementum), approximately 20% less long epithelial junction and approximately 20% more connective tissue in roots etched with EDTA. The statistically significant differences between citric-acid-treated surfaces (n=14) and control surfaces (n=11) were approximately 10% more connective tissue and 15% less long epithelial junction in the citric acid etched roots. Thus, etching with EDTA appeared to improve healing, avoiding the superficial necrotizing effect on exposed periodontal tissues by citric acid documented in previous studies. Although etching at present is not routinely applied in conventional periodontal therapy, future potential applications of etching at neutral pH may include exposure of the collagenous matrix of dentin for retention of biologically active substances, such as growth factors. Such treatment may be argued to produce a biocompatible surface more conducive to periodontal membrane cell colonization after removal of root-surface- associated smear without compromising the vitality of the surrounding periodontium.

Histological analysis of effects of 24% EDTA gel for nonsurgical treatment of periodontal tissues

“…In some cases, irrespective of treatment and period before sacrifice, cracks between the tissue and the root surface were observed, although these were probably artifacts of histological preparation (23). Therefore, it can be concluded that the vitality of the surrounding periodontal tissue is not altered by application of EDTA gel, in accordance with earlier studies (5,7,10,11,13,14).…”

“…Therefore, chemical treatment of the root surface after scaling and root planing has been introduced as a promising procedure for removing the smear layer (3,12,16,) and hypermineralized areas of the root surface, in order to expose collagen fibers and render the root surface biocompatible with periodontal cells (11,29). Furthermore, acid etching may also facilitate the attachment of connective tissue (3,8,11). However, etching of root surfaces at low pH has been shown to impair periodontal healing (2) in comparison with etching at neutral pH (10), since the use of low-pH biomodification agents may have necrotizing effects (7,15).…”

“…However, one of these studies presented only clinical scores (13) and the other merely observed the root surface after nonsurgical treatment (7) without histological analysis of the soft tissues. In addition, some earlier studies using surgical treatment to evaluate the effects of different etching modalities on periodontal healing also concluded that EDTA gel does not promote necrotization (5,10,11,14). In the present study, histological analysis of samples removed after 4 days showed necrosis of some cells in the superficial layer of the epithelium in all of the treatment groups, indicating that etching with EDTA gel at neutral pH did not induce additional cell necrosis.…”

“…Some studies have investigated the capacity of EDTA gel to enhance the healing of periodontal tissue (11,13). Blomlöf et al (11), using histological analysis, concluded that such treatment may increase total histological attachment (long epithelial junctions, connective tissue and reparative cementum).…”

“…One of the most widely used agents for this purpose is citric acid (9). However, other agents such as tetracycline (10)(11)(12) and ethylenediaminetetraacetic acid (EDTA) (6,13,14) have also been employed.…”