Periodontal Wound Healing

10.1055/b-0034-56516

Periodontal Wound Healing

Repair → Reattachment → “New Attachment” → Regeneration → Prevention

Periodontal wound healing follows the well-acknowledged biological principles (Clark 1996, Fig. 447), but it is also the “most complex healing process” in the human body (McCulloch 1993): The cells of five or more tissue types—epithelium, gingival and periodontal connective tissue, bone, root cementum—are essentially asked to create a new connection to the nonvascular and nonvital hard tissue of the root surface. Healing of the periodontal wound is also rendered more complex because it must occur in an open system, permanently contaminated and under a significant “bacterial load.” It is therefore not surprising that the healing results following all types of periodontal pocket therapy can be quite variable.

In contrast, the osseointegration of a titanium implant (p. 319) is, biologically speaking, child’s play, involving only ankylotic connection to the bone. In the case of periodontal healing, ankylosis represents a failure (root resorption)!

The most basic requirement for successful periodontal treatment is a clean, biofilm-free, decontaminated root surface. In most cases, this leads to connective tissue repair, a long junctional epithelium and usually residual pockets.

Ever-more successful regenerative treatment methods must be developed to insure optimal healing results.

447 Principal Stages of Wound Healing The three overlapping stages will be described. Because their temporal course is influenced by a diversity of factors, each of these stages may vary considerably in length: • Stage of inflammation Short duration (orange) • Stage of proliferation Medium duration (beige) • Stage of maturation Long duration (blue) Adapted from R. Clark 1996

Regeneration of the Periodontal Defect

In addition to elimination of the tissue-destroying inflammation, true regeneration of lost tissues is one of the most important future topics in periodontology. Bony defects are filled today using autogenous or bone replacement materials; biomechanical substances (barrier membranes; GTR) prevent the downgrowth of epithelial tissue.

Thereafter, signal molecules (differentiation factors, growth factors etc.) steer migration and differentiation of pluripotent stem cells, guided by artificial or natural structures (“tissue engineering”), matrix formation and the formation of new tissue (Lynch et al. 1999).

Great progress has been made in tissue augmentation and defect filling, soon to become a standard procedure, but the more difficult task is to achieve “Regeneratio ad integrum,” namely a completely functional connection between the augmented soft tissues and especially the alveolar bone to the once infected and morphologically altered root surface (new periodontal ligament).

In all experiments to date, the formation of new cementum was only rarely identified histologically as acellular, extrinsic-fiber cementum, but more often as cellular cementum. Many authors have referred to this material as “bone-like,” which does not provide a stable connection to the root dentin.

Wound Healing and Regeneration—Possibilities

The paradigms of periodontitis therapy have changed markedly in the past two decades, due primarily to a veritable flood of new knowledge from medical specialties (McCulloch 1993, McGuire 1996, TenCate 1997, Wikesjö & Selvig 1999, Cho & Garant 2000).

New insights into the guidance and feedback mechanisms of cellular function now permit us to influence the healing processes (Bartold & Narayanan 1998, Christgau 2001, Hägewald 2002). As a result of advances in cell biology, we can better interpret the behavior of the tissues (Amar & Chung 1994, Selvig & Wikesjö 1999). For example:

  • The bone-inducing capacity of demineralized bone matrix (proteins such as BMP; Jepsen 1996, Jepsen & Terheyden 2000).

  • Concepts of conditioning the nonvascular root surface (acids, Emdogain; Selvig et al. 1988, Trombelli et al. 1995, Hammarström 1997, Blomlöf et al. 2000)

  • The “bioacceptability” of a formerly LPS-saturated root surface following detoxification

  • The concept of tissue “compartments”; this lead to the GTR technique, because cells colonize the surface according to the principle of “first come—first served” (Fig. 448 B)

  • The systemically-modulated, complex and overall active local network of growth factors and differentiation factors, signal molecules and adhesion molecules (Marx et al. 1998, Anitua 2001, Kübler & Würzler 2002)

  • The existence of pluripotent stem and precursor cells within the blood stream and in the perivascular tissues.

Despite these enticing new developments and theories, periodontitis therapy today is guided by a strict anti-infectious, anti-microbial concept (Slots et al. 1999), with protocols for the individual treatment techniques. But still lacking are guidelines for the immediate postoperative period, that is during the first phase of healing, for wound care, immobilization and pharmacomechanical plaque control of the healing wound. Stabilization, especially the stabilization of the coagulum, is one of the most important measures. Stabilization mechanisms (adhesins etc.; Somerman et al. 1987, MacNeil & Somerman 1999, Somerman 2001) on the conditioned root surface prevent the downgrowth of epithelium and enhance the secure stabilization of the fibrin matrix. This serves as a natural guidance mechanism for the immigration of factor-guided future tissue cells during the second phase of wound healing.

448 Possibilities for Periodontal Wound Healing Depicted are diagnosis (A), treatment (B) and possible therapeutic results (C—G; post-therapeutic healing) for the periodontal intraalveolar defect on the tooth shown on the left side of each illustration Note: The periodontal tissues of the tooth on the right side of the illustration are healthy. A Diagnosis: Interdental Bony Pocket The periodontal probe penetrates the inflamed and infiltrated loose tissue until it contacts the bone adjacent to the diseased tooth, below the most coronal niveau of the interdental alveolar ridge (= “bony pocket”). B Treatment: Closed or Surgical Therapy, Root Planing The “race among the tissues” now begins (cf. GTR, p. 301). 1 Oral gingival epithelium 2 Gingival connective tissue 3 Periodontal ligament connective tissue 4 Bone C Healing after Debridement, via a Long Junctional Epithelium Typical healing pattern, from apical towards coronal: • Little reattachment (blue) • Little new attachment (blue hatched) • Long junctional epithelium (pink) with new collagen fibers parallel to it • Residual pocket

Periodontal Wound Healing—Definitions

Histologic studies of wound healing have clarified whether and to what extent healing of the gingival and periodontal attachment apparatus is possible in the form of re-attachment or regeneration (Schroeder 1983, Polson 1986, Karring 1988). One differentiates among:

• Epithelium

re-attachment?

• Epithelial regeneration

“new attachment”

• Connective tissue

re-attachment

• Connective tissue regeneration

“new attachment”

Histologic Terminology

Regeneration—Restitutio ad integrum

Complete regeneration of form and function: Gingiva with junctional epithelium and gingival connective tissue; periodontium with cementum, periodontal ligament, bone.

Repair

Restoration of the continuity in the wound or defect area, without regeneration of the originally intact tissues’ form and function: e.g., long junctional epithelial attachment.

“New Attachment”

New connection of connective tissue with the formerly pathologically exposed root surface, i.e., formation of new cementum with inserted periodontal ligament fibers (also, formation of new bone with Sharpey’s fibers embedded).

Re-attachment

Re-attachment is the re-establishment of the bond between connective tissue and the remaining vital tissue components on the root surface, e.g., cementum and remnants of the periodontal ligament (usually in the deepest areas of the pocket; “dark blue” in Fig. 447/448 C–G).

Note: Epithelial re-attachment does not occur. Epithelium is always established by new cells from the basal cell layer.

Alveolar Bone—“Bone Fill”

Filling a periodontal osseous defect does not provide evidence for complete periodontal regeneration (including newly formed cementum). This can only be demonstrated histologically (Listgarten 1986).

Clinical Terminology

For precise definitions of probing depth, clinical attachment level etc., see “Diagnosis” (p. 165).

448 Further Possibilities for Healing, D–G D Healing after Regeneration Surgery • Somewhat elongated junctional epithelium • Collagen adhesion with some reattachment • Osseous regeneration; regeneration occurs primarily in the apical regions, more coronally one finds a long junctional epithelium = repair; residual pocket = good “partial success” E Unfavorable Healing with Root Resorption Connective tissue repair leads to connective tissue filling the defect Resorption of the root surface (“external granuloma”) Failure of protection by the junctional epithelium? F Unfavorable Healing with Ankylosis Bone regeneration with root resorption Aggressively regenerating bone resorbs and fills segments of the root dentin; filled earlier by means of transplantation of illiac crest bone as a “filler.” G Total Regeneration: Future Goal? Utopia? De novo formation of: • Cementum (green) • Periodontal ligament • Bone All tissues regenerate in proper amounts, in the correct temporal sequence, restoring tissue homeostasis (“Restitutio ad integrum”)
Only gold members can continue reading. Log In or Register to continue

Jul 2, 2020 | Posted by in Dental Hygiene | Comments Off on Periodontal Wound Healing
Premium Wordpress Themes by UFO Themes