Marwa Mahmoud Bedier

Regeneration and Repair of apical tissues

                     Marwa Bedier
      Ass. Lecturer in Endodontic Dep.

                   Supervised by

                  Dr. Nehal Ezzat
        Ass. Prof. in Endodontic Dep.

Periodontal Tissue Destruction in Periodontal
Disease and in Apical Periodontitis

The etiology and pathogenesis of

     periodontal disease and apical

     periodontitis are similar.

 Both diseases are caused by bacterial

     biofilm infection and show periodontal tissue destruction; gingival tissue, PDL, cementum, and alveolar and the last 3 tissues as well as dentin in apical periodontitis

Regeneration

The replacement of destroyed tissue with new tissue formed by the cells of the same origin.

In periapical surgery, the resected root -end can’t be regenerated.

Biology of Periapical Wound Healing After
Periapical Surgery

The tissue wounded in periradicular surgery are the oral mucoperiosteal tissues, periradicular (Bone +P.L) and radicular tissues (Dentin+Cementum).

Type of surgical wound include,

   incisional , blunt dissection and excisional.

 

Healing Phases:

Phase I: Clotting and Inflammation.

Phase II: Epithelial healing.

 Phase III : Connective tissue healing.

Phase IV: Maturation and Remodeling.

 Soft tissue healing

Phase II: Epithelial healing

Epithelium:

      contact guidance then stop by contact 

     inhibition of cells in opposite wound edge.

   
Phase III : Connective tissue healing

Fibroplasia:

     Fibroblast migrate by the third day  to the wound site, stimulated by cytokines (FGF, IGF-1, PDGF)  produced by platelets, macrophages and lymphocytes.

     As macrophages decline and fibroblast increase the tissue in the wound transfer from Granulomatous to granulation tissue.

     By the third day Collage type II is produced, then  as collagen type I is  produced as the wound mature.

Phase IV: Maturation and 
           Remodeling

       Begin 5-7 days after injury

    Suffficient collagen produced   

    reduction in fibroblast

    replacement of granulation   

        tissue by young fibrous

        connective tissue.

DISSECTIONAL WOUNDS

derived from one wound edge only (mucoperiostesl )

    and necrosis of surface lamella under the

    cortical bone

Excisional wound
Apical dentoalveolar healing

II)  Osteogenesis  by à osteprogenitor cells

                                  à preosteoblasts

                                  à osteoblasts

   Bone formation by:

     

                          Tissue engineering

          3 main approaches :

     (1) isolated cells or cell substitutes

     (2) acellular biomaterials (scaffolds) capable of inducing   

          tissue regeneration.

     (3) combination of cells and biomaterials Griffth and Naughton   

            2002.

Guided tissue regeneration (GTR)

used to regenerate lost attachment apparatus through differential tissue response.

Regeneration of periapical tissues after periapical surgery requires

Indications of GTR and  Bone augmentation in endodontic surgery

1. Large periapical   

       lesions.

2. Through and through   

        lesions

 3. Furcation involvment as a  

       result of perforation

 4. Periapical lesion communicating  

       with the alveolar crest

 5. Root perforation with bone loss 

       to alveolar crest 

ADVANTAGES OF GTR IN ENDODONTIC
MICROSURGERY

DISADVANTAGES OF GTR IN ENDODONTIC
MICROSURGERY

Membrane Barriers

The application of a membrane barrier in periodontal regenerative therapy :

      and  connective tissue cells onto root surface

      surface with PDL progenitor/ stem cells to    

      differentiate into PDL  cells and cementoblasts

   

 

       

           Membrane barrier placed over a bony 

    defect beneath a full-thickness mucoperiosteal 

                  flap during periapical surgery.

 used in large periapical lesions or through-and through bony defects

     prevent proliferation of

     cells, which  are capable of differentiating into fibroblasts

Types of GTR membranes

Non-Resorbable

    ePTFE (expanded polytetrafluoroethylene)

   The first commercially available barrier membrane was an called Gore- Tex.

Bio-absorbable

CALCIUM SULFATE AS AN ALTERNATIVE TO THE
USE OF BARRIER MEMBRANES IN GUIDED TISSUE
REGENERATION

    Calcium sulfate has been demonstrated to perform better as a barrier than membranes.  Pecora et al 1994

    advantages :

Inexpensive.

Ease of application.

No inflammatory reaction.

Absence of postoperative complications.

Stabilization of blood clot.

Adhesion to root surface.

Biocompatible.

Complete absorption.

In cases with through-and-through lesions, calcium sulfate has proven to be a better option than  membranes.

Some points to remember while
using barrier membranes are:

1. The membranes should extend at least 2 to 3 mm beyond the margins of the bone cavity.

2. A space must be created underneath the membrane to allow the growth of new tissue

3. The membrane should be totally submerged because exposed membrane increases the risk of infection.

Some points to remember while
using barrier membranes are:

4.The membrane must be stable and immovable.

5. The membrane must act as a selective barrier for at least 6 to 8 weeks.

6. Mobile teeth must be splinted.

7. A strict oral hygiene regimen must be followed with gentle brushing.

Bone Grafts in Periapical Surgery

The principles of successful bone grafts include:

enamel matrix derivatives enhance the osteoinduction of demineralized freeze dried bone allograft (DFDBA)

Grafting materials according to source

Autograft:

   transplant of viable cortical or cancellous bone from one location to another within the same patient.eg. Ramus, tuberosity

   Advantages :  

osteogenic

prevent disease transmission

 low cost.

    However, they require a second surgical site at the donor site.

Allograft

   A bone allograft refers to a graft between genetically dissimilar members of same species

Ex: Decalcified Freezed Dried Human Bone,

      Freeze-  dried bone allograft (FDBA)

      Freezed  Dried Human Dermis.

     Advantages :

Osteoconductive or osteoinductive

No additional surgical procedure required

     Disadvantages:

 foreign body immune response, cost, and

     contamination of the graft during processing.

Allograft
Decalcifying the bone allograft exposes BMPs, which have osteoinductive properties

However, decalcifying the bone graft also causes the graft to resorb much faster and act as a less effective scaffold than FDBA.

Xenograft :

      cross-species transplantation of tissue such as anorganic bovine bone or porcine collagen

 osteoconductive

resorb very slowly and might sequester or undergo fibrous encapsulation

antigenicity

Alloplasts

      implantation of sythetic material , such as HA or

       TCP , bioactive glass , non-ceramic polymer

 osteoconductive

Growth Factors/Cytokines/Host Modulating Agents Used to Promote
Periodontal Regeneration

Platelet Rich Plasma (PRP)

    is a highly concentrated suspension of autologous platelets, secrete bioactive growth factors on activation.

They help to enhance key stages of wound healing and regenerative processes including chemotaxis, proliferation, differentiation, and angiogenesis

Platelet-rich Plasma and Guided
Tissue Regeneration Membrane in the Healing
of Apicomarginal Defects

     Treatment of Periapical Inflammatory Lesion with the Combination of Platelet-Rich   
         Plasma and Tricalcium Phosphate

    contains  PDGFs that promote regeneration.

     involved in wound healing ,stimulates the regenerative potential of periodontal tissues including bone, cementum, and periodontal ligament

     stimulates osteoblasts to express Tgf-1, which may accelerate repair of bone defects created during periradicular or dental implant surgeries

     stimulation of osteoblastic differentiation in human periodontal ligament cells .

EMD

     deposited onto the dentin root surface and provide the initial step in the formation of acellular cementum.

 EMD was used successfully to treat a large periradicular lesion involving an adjacent implant , Lin and Mayer 2007

Taschieri 2007, reported 78% of periapical defects healed successfully, using anorganic bovine bone and resorbable collagen membrane after1 year,

    although there were no differences in outcomes between GTR and no treatment of the residual periapical lesion.

 

    In contrast, using anorganic bovine bone in combination with a bioabsorbable  collagen membrane to treat through-and-through endodontic lesions showed a success rate of 88% in the treatment group compared with 57% in the  control group (no bone graft or membrane). Taschieri 2008