COMPARATIVE EVALUATION OF NATURAL AND ARTIFICIAL SCAFFOLDS IN REGENERATIVE ENDODONTICS

COMPARATIVE EVALUATION OF NATURAL AND ARTIFICIAL SCAFFOLDS IN REGENERATIVE ENDODONTICSB.SARAVANA PRATHAPCRI.

Regenerative endodonticsRevascularizationScaffoldCase studyConclusion

REGENERATIVE ENDODONTICSThe American Association of Endodontics defines regenerative endodontics as biologically based procedures designed to physiologically replace damaged tooth structures, including dentin and root structures as well as cells of the pulp-dentin complex.

RECOMMENDATIONS FOR REGENERATIVE ENDODONTICSType of tooth injuryFracture typePresence of necrosis or infectionPeriodontal statusPresence of periapical lesionsStage of tooth developmentVitality statusPatient age and health status

STEPS TO ACCOMPLISH REGENERATIVE ENDODONTIC TREATMENT

COMPONENTS OF REGENERATIVE ENDODONTICSThe three key elements for tissue regeneration are : 1) Stem cells (hard tissue formation) 2) Growth factors (cellular stimulation,proliferation,differentiation) 3) Scaffold (support cell growth and differentiation)

RECOMMENDATIONS FOR REVASCULARIZATIONThe traumatized tooth must be non vital and not suitable for apexogenesis,apexification,partial pulpotomy.The tooth must be permanent and immature with a wide open apex and exposed pulpAnesthetic without a vasoconstrictor should be used Endodontic sealer is not biocompatible for regeneration and cannot be used.A thin layer of MTA or calcium hydroxide should be placed above the blood clot since the restorative materials (amalgam,GIC,composite) are not biocompatible to the exposed pulp tissuesThe tooth should be restored with a resin modified glass ionomer to prevent microleakage

PHASES OF PULP REVASCULARIZATION PROCEDURESFirst phase of treatment : consists of debridement and antibacterial medication

Interim phase : consist of interim medication replacement

Final phase : completion of regenerative treatment in an immature permanent tooth with a necrotic pulp. It does not include final restoration.

SCAFFOLDS:Scaffold provides the framework for cell growth and differentiation at a local site.

A scaffold should be porous,biocompatible with the host tissues , the correct shape and form to allow for replacement of the lost tissues and biodegradable.

TYPES OF SCAFFOLDS :It includes two types. They are

1) Natural Scaffold Blood clot PRF 2) Artificial Scaffold Collagen poly glycolic acid (PGA) polylactic acid (PLA) poly lactic co glycolic acid (PLGA)

Natural scaffolds - Good biocompatibility and bioactivity. - Can cause discomfort to the patient due to intentional periapical filling to induce blood clotArtificial scaffolds - Control over degradation rate and mechanical properties. - Allows for replacement with natural tissues after undergoing degradation.

CASE STUDY : Aim : To evaluate and compare the regenerative potential of natural autologous scaffolds (blood clot and PRF) with artificial scaffolds (collagen and poly-lactic-co-glycolic acid ( PLGA ) polymer) . Materials and Methods : - Necrotic immature permanent maxillary incisors (with or without radiographic evidence of periapical lesion)

REVASCULARISATION :

It is a new treatment method for immature necrotic permanent teeth. It stimulates the apical development and root maturation of immature permanent teeth. It is an alternative treatment method for the apexification.

Steps in revascularization :

under rubber dam isolation , access opening was done in teeth with #2 round diamond bur.Axial wall extensions were done with safe tip fissure carbide bur.Minimal canal instrumentation was done with k-files to remove the necrotic tissueCanals were copiously irrigated with 2.5% sodium hypochlorite solution using a syringe and side vented needle.

Triple antibiotic paste (400 mg metronidazole(bactericidal),250 mg ciprofloxacilin(bactericidal), 50 mg minocycline) was used as the medicament for 4 weeks and the access cavity was sealed with temporary restorative material. Disadvantage includes the discoloration of tooth due to the use of minocycline. The discoloration can be prevented by the use of cefuroxime or by the application of bonding agent in the coronal dentin to seal the dentinal tubules.The alternative for the antibiotics includes the calcium hydroxide insertion . But the calcium hydroxide insertion should be limited to the cervical third of the root canal since there are increased incidences of root fracture due to disruption of the link between hydroxyapatite crystals and the collagenous network in dentin.

After 4 weeks : - Teeth were re-accessed under rubber dam isolation - Triple antibiotic paste was washed out of the canal using copious amount of 2.5% sodium hypochlorite solution - Canals were dried and further revascularization procedure was carried out only if the tooth was asymptomatic with no drainage from the canal.

16 cases selected for the study divided into four groups with each group containing four cases.

GROUPIBlood clotIIPRFIIIcollagenIVPLGA

GROUP I

(BLOOD CLOT)GROUP II

(PRF)GROUP III

(COLLAGEN)GROUP IV (PLGA) Under local anesthesia without adrenaline, a sterile 23 gauge needle was passed beyond the working length and bleeding was induced in the canal. A tight cotton pellet was inserted in the coronal portion of the canal and pulp chamber for 7-10 min to induce clot formation in the apical two third of the canal. Access cavity was sealed with GIC. PRF was prepared by drawing 5 ml of venous blood from the patient in a dried glass test tube and immediately centrifuging at 3000 rpm for 10 min. Base layer of RBCTop layer of acellular plasmaPRF clot in the middle The clot was then pressed between two gauge pieces to form a membrane. PRF was carried to the apical part of the canal using the endodontic pluggers. Access cavity was sealed with GIC. Blood clot was induced in the root canal as done in group I . Sterile collagen sponge was inserted into the root canal with the endodontic pluggers. Access cavity was sealed with GIC. Blood clot was induced in the root canal as done in group I . Sterile PLGA crystals was inserted into the root canal with the endodontic pluggers. Access cavity was sealed with GIC.

SCORING CRITERIA :SCORERADIOGRAPHIC HEALING0No healing / improvement from baseline1Fair healing / improvement from baseline2Good healing / improvement from baseline3Excellent healing / improvement from baseline

*Pre-operative intra oral periapical radiograph was taken as baseline record.

RESULTS :

The evaluations were done at 6 and 12 months after the procedure and compared with baseline records.

Clinical evaluation : - Patients were completely asymptomatic throughout the study period with no tenderness to palpation and percussion.

- Swelling and sinus had resolved completely and did not reappear.

Radiographic evaluation :

All 16 cases showed improvement in terms of periapical healing,periapical closure, root lengthening, dentinal wall thickening.

GROUP I BLOOD CLOT Teeth No. 11,21 Pre-Operative After 6 months After 12 months

GROUP II - PRFTooth No. 21 Pre-Operative After 6 months After 12 months

GROUP III - COLLAGENTooth No.21 Pre- operative After 6 months After 12 months

GROUP IV PLGA Tooth No. 21 Pre operative After 12 months

COMPARATIVE EVALUATION OF PERIAPICAL HEALING :GROUPSFAIR (%)GOOD (%)EXCELLENT (%)I (Blood clot)255025II (PRF)-2575III (Collagen)-7525IV (PLGA)7525-

COMPARATIVE EVALUATION OF APICAL CLOSURE :GROUPSFAIR (%)GOOD (%)EXCELLENT (%)I (Blood clot)2575-II (PRF)-5050III (Collagen)252550IV (PLGA)5050-

COMPARATIVE EVALUATION OF ROOT LENGTHENING :GROUPSFAIR (%)GOOD (%)EXCELLENT (%)I (Blood clot)2575-II (PRF)100--III (Collagen)7525-IV (PLGA)5050-

COMPARATIVE EVALUATION OF DENTINAL WALL THICKENING :GROUPSFAIR (%)GOOD (%)EXCELLENT (%)I (Blood clot)5050-II (PRF)2575-III (Collagen)255025IV (PLGA)7525-

GROUPPRFRich quantities of growth factors required for cellular proliferation,differentiation and angiogenesis.COLLAGENFormation of mineralized tissues in teeth with incomplete root development and apical periodontitis. It also helps in stem cell adhesion,proliferation and differentiation.BLOOD CLOTIt serves as a source of stem cells from granulation tissue, PDL , apical papilla.Collagen along with blood clot gives better results due to the risk for the blood clot disintegrationPLGA Stimulates bone growth . Acts as a suitable matrix to support dental stem cells and their differentiation to form an organized dentin/pulp like tissue. The osteoblast will reproduce on the scaffold. Differentiation will take place subsequently, forming the required bone as the scaffold degrades. It breaks down into lactic acid and glycolic acid, which are metabolised in the body and excreted as carbon dioxide and water. This process typically occurs over a time frame of two to six months.

CONCLUSION : Revascularisation procedure is more effective and conservative over apexification in the management of necrotic immature permanent teeth.PRF and Collagen are better scaffolds than blood clot and PLGA for inducing apexogenesis in immature necrotic permanent teeth.

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