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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 11  »  Comparison of Diaket and MTA when used as root-end filling materials to support regeneration of the periradicular tissues
Comparison of Diaket and MTA when used as root-end filling materials to support regeneration of the periradicular tissues
Introduction - Materials and methods.



J. D. Regan, J. L. Gutmann & D. E.Witherspoon
Department of Restorative Sciences, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX, USA.
Private Practice Limited to Endodontics, Dallas, TX, USA.


Introduction.
A significant number of research and clinical studies have attempted to identify the ideal root-end filling material (Gutmann & Harrison 1994). These studies focused primarily on the physical properties and materials usage in the surgical site and the radiographic assessment of their periradicular tissue responses.
Andreasen et al. (1993) addressed the biological parameters necessary for the ideal root-end filling materials and concluded that regeneration should be added to the list of desirable properties. Regeneration has been defined as the replacement of tissue components in their appropriate location, amounts and relationship to each other (Aukhil 1991). This implies the reformation of the bone in the surgical site, adjacent to a fully reconstituted periodontal ligament (cells and fibres),which is attached to newly formed cementum over the resected root end and the root-ending filling material. The occurrence of this type of tissue regeneration has not been demonstrated when amalgam, gutta-percha, glass ionomers, intermediate restorative material (IRM) or ethoxy benzoic acid cement (EBA) have been used as root-end filling materials, as none of these materials have exhibited a cemental regrowth over their surfaces. In an animal histological study, Andreasen et al. (1989) identified the regeneration of cementum over a bonded composite root-end filling material (Retroplast). This was subsequently confirmed in a number of human histology cases (Andreasen et al.1993) and in multiple radiographic studies (Rud et al.1996a,b;1997, Rud & Rud1998).
Inherent in the tissue response to the root-end filling is the potential for the material or its constituents to influence the extracellular matrix (ECM) (Craig et al. 1997). This influence will ultimately determine specific cellular induction and matrix formation characteristics of the phenotypic expression of osteoblasts, fibroblasts and cementoblasts. Recent histological studies have demonstrated the strong possibility of cemental regeneration over the root-end filling when either mineral trioxide aggregate (MTA) (Dentsply/Tulsa Dental, Tulsa, OK, USA) (Torabinejad et al. 1995a,b,c) or Diaket (ESPE, Seefeld, Germany) (SnyderWilliams & Gutmann 1996a) were used. Whilst neither study specifically characterized immunologically the nature of this covering material, total tissue regeneration in the surgical site appeared most promising, when either material was used.
The purpose of this study was to evaluate further, on a comparative basis, the potential for MTA and Diaket to promote periradicular tissue regeneration when used as surgical root-end filling materials.

Materials and methods.
Ethical approval for this study was sought and received from the Institutional Animal Care and Use Committee, Baylor College of Dentistry, Texas A&M University Health Science Centre. Seven dogs weighing between 15 and 25 kg were quarantined for 10 days before commencement of the experiment procedures. The animals were anesthetized by intramuscular injection of 1mg kg_1 of rompun (Mowbay Corporation, Shawnee, KS, USA) and 20 mg kg_1 of ketamine (Mowbay Corporation). Intraoral anaesthesia was achieved with a mandibular nerve block injection of 1.8 mL of 2% lidocaine containing 1:100 000 epinephrine (Astra Pharmaceutical Products, Westborough, MA, USA).
Following preoperative radiographic assessment of the third and fourth mandibular premolar region, the teeth were isolated with surgical gauze. The pulp chambers were accessed, pulpectomies were performed and the root-canal systems were cleaned and shaped chemomechanically using Gates Glidden drills (Brasseler, Savannah, GA, USA) and Flexofiles (Dentsply/Maillefer, Ballaigues, Switzerland). Copious amounts of sodium hypochlorite (5.25% NaOCI) (The Excelex Corporation, Dallas, TX, USA) were used for irrigation. The canals were dried with paper points and obturated with a thickmixture of Diaket (Tetsch1986, Snyder Williams & Gutmann 1996a). The coronal access cavities were restored with IRM (Caulk Dentsply, Milford, DE, USA). Following completion of the nonsurgical phase and immediately prior to the surgical phase of treatment, a local infiltration of 1.8 mL of 2% lidocaine containing 1 : 50 000 epinephrine (Astra Pharmaceutical Products) was used to enhance haemostasis in the surgical sites (Buckley et al. 1984, Gutmann 1993). A full thickness mucoperiosteal flap was reflected and an osteotomy was performed exposing the apical third of the experimental tooth roots. The root ends were resected using a Lindeman bone-cutting bur (Brasseler, Savannah, GA, USA). Root-end cavity preparations, approximately 1.0- 1.5 mm in diameter and1.5-2.0 mm deep, were prepared using ultrasonically energized tips held in a Spartan ultrasonic device (Excellence in Endodontics, Orange, CA, USA). Collaplug (Colla-Tec Inc., Plainsboro, NJ, USA) was placed in the bone crypt to enhance the local haemostasis and increase visibility during the root-end preparation and filling. A solution of 1% methylene blue (Excellence in Endodontics) was applied to the resected root face to outline the periodontal ligament (Cambruzzi &Marshall1983).The resected root faces were burnished with a sponge applicator soaked in10% solution of citric acid (pH 1) for 2 min (Register 1975, Polson & Proye 1982, Craig & Harrison 1993) and washed with sterile saline.
The root-end filling materials Diaket (ESPE) or MTA (Dentsply/Tulsa Dental) were prepared and allocated randomly for placement in the root-end preparation. The rejected tissues were repositioned and compressed with moist gauze for 5 min and sutured with 4-0 vicryl suture. The animals were placed on a soft diet and approximately 7.5 mg kg_1 ibuprofen twice daily for 2 days.
Sixty days postsurgery, the animals were killed after sedation and anaesthesia with intramuscular injections of 1mg kg_1 of rompun and 20 mg kg_1 of ketamine. The head and neck were perfused with 1.5 L of 10% phosphate-buffered formalin maintained at a pressure of between 110 and 140 mm Hg. The mandible was dissected free and block sections of each of the third and fourth premolar roots were formed and placed in 10% formalin for further fixation.
Theresectedblocksweregentlydemineralizedin0.5 m ethylene diamine tetraacetic acid (EDTA), embedded in paraffin and 6-mmserial sections were made in a buccolingual longitudinal orientation using a Leitz 1512 rotary microtome (Ernst Leitz Wetlzar, Rockleigh, NJ, USA).The sections were stained alternatively with either haematoxylin and eosin stain (Man & Marshallbeck 1995) or Gomori’s one step trichome (Masson’s trichome method) stain.
The tissue sections were evaluated by two calibrated examiners using a light microscope (CHS Biological Microscope, Olympus America Inc., Melville, NY, USA). Specific parameters of evaluation and grading are indicated in Table 1and described in a previous study (Regan et al. 1999).When a discrepancy between grading was noted, a second evaluation was performed jointly until agreement was reached. The raw data was accumulated, tabulated and entered into a spreadsheet for statistical analysis using the SAS programme (SAS Institute Inc., Cary, NC, USA). A one-way analysis of variance (anova) was applied to each group of data after adjusting for the animal block effect. A statistical model was created and the sum of the squares partitioned to take into account the difference between the animals whilst adjusting for correlation within animal. Analysis of the data indicated that the use of anova could be applied to the data even though the data were ordinal. This was because the sample size was relatively large and that two independent examiners evaluated each of the sections.

Table 1. Quantitative and qualitative scoring criteria.

Quantitative and qualitative scoring criteria