Margınal ıntegrıty of fıve dıfferent root sealers ın retrograde fıllıng followıng apıcoectomy: An ın vıtro analysıs wıth scannıng electron mıcroscope and mıcro-radıography CURRENT STATUS: POSTED

Objective The aim was to clarify the physical properties of five different root canal sealers used as retrograde filling materials on the resected root apex following apicoectomies. Materials and Methods Apical resection was performed on 100 canals of 50 maxillary premolars in slaughtered pigs. The root end of 24 canals were retrogradely filled with Diaket ™, 37 root canals with Super-EBA ™ including 18 with Super-EBA ™ Regular and 19 with Super-EBA ™ fast, 20 canals with ProRoot® MTA and 19 canals with AH-Plus ™. For quantitative examination, scanning electron microscope (SEM) analysis and for qualitative examination microradiography was performed. Results Diaket ™ achieved the best results with an overall average of 4.872 microns gap value. The mean values of marginal gap widths of AH - Plus ™ and Super - EBA ™ were almost the same magnitude 8.044 microns and 9.951 microns respectively, followed by Super - EBA ™ Regular with 11,560 microns. Highest marginal gap value was detected in ProRoot® MTA with 18.343 microns (p < 0.001) . Conclusion According to the limited knowledge of the current in vitro study Diaket ™ achieved the best results compared to the other materials. Additional clinical studies with long term follow up period might help to determine the most appropriate root-end filling material.Clinical Relevance Among five different root canal sealers used as retrograde filling materials, in terms of its marginal integrity and material properties, Diaket ™ can be referred as the most suitable material for retrograde obturation.

the treatment of persistent contamination of the apical region, when traditional endodontic therapy has failed 2 . The aim of this procedure is to resect the apical root end with lateral accessory canals, remove the adjacent granulation tissues and to obtain well sealed apical region with a biocompatible root-end filling material. 3 The quality and sealing ability of the retrograde filling material plays an important role of the success of the treatment and good prognosis. neutral, organic material which shows a high adhesive strength to dentin. It is radiopaque and dimensionally stable. It solves fats and other organic substances and absorbs remaining moisture on the canal wall during its setting. 8 It is characterized by a high adherence to intracanal walls and it also acts as a disinfectant. 9,10 Diaket ™ is the most evaluated material in the dental literature.
AH -Plus ™ ( Dentsply DeTrey GmbH, D -78467 Konstanz) is a two component epoxyamine polymer based material. It shows minimal shrinkage during curing, and shows an outstanding long-term dimensional stability. 11,12 Unlike its predecessor, the AH26, there is no free formaldehyde leakage into the adjacent structures. 13 Super-EBA ™ (Bosworth Company, 7227 North Hamlin Avenue, Skokie, Illinois 60076, USA) is a zincoxide-eugenol (ZOE) based root filling material. It is pH-neutral, radiopaque and has hydrophilic properties 14 . It shows satisfactory long term results regarding marginal leakage. 14,15 It has two different types according to the curing time. The "Fast Set" type can be used for easily accessible operational areas due to its shorter curing time.
Retrograde root tips are usually difficult to access, so this material can be used only on a few easily accessible root tips. The "Regular Set" has a wider range of application due to its longer setting time; as it is also suitable for areas that are difficult to access.
ProRoot® MTA ( Dentsply Tulsa Dental, 608 Rolling Hills Drive, Johnson City, TN 37604, USA) is mineral trioxide aggregate based, constant form, radiopaque root filling material. 16 The enclosed package contains distilled water and a powder, which forms a colloidal gel after mixing. According to Apaydin et al 17 , the material could stimulate hard tissue formation in the adjacent periapical structures. Similar to Diaket TM, the properties of ProRoot ® MTA were tested in numerous studies and suggested to be one of the most appropriate material for root-and root-end fillings. [18][19][20] Due to its high biocompatibility, and regenerative properties ProRoot ® MTA resin is proclaimed to be suitable for retrograde root sealing following apicoectomy or intentional replantation. 21,22 The success of the endodontic treatment depends on the presence of a well sealed apical region to prevent bacterial invasion from the root canal to the surrounding tissues.
However, it is not yet possible to define one of the above mentioned materials as "ideal".
The aim of this study was to evaluate the marginal adaptation of five different sealers (Diaket™, AH-Plus™, Super-EBA™ regular, Super-EBA™ fast und ProRoot ® MTA) following apicoectomy via scanning electron microscope (SEM) and microradiography in vitro.

Experimental subjects
The study was performed on 25 fresh cadaveric porcine mandibles of male and female pigs that were obtained from the slaughterhouse in Kiel-Wellsee-Germany. Animals were between seven and nine months old at the time of slaughter. The heads were stored frozen after decapitation at -21°C and then thawed in the refrigerator at 4°C for 48 hours before the root resection and root canal filling was performed.
Apicoectomy and root-end filling procedure Apical resection was performed on 100 canals of 50 maxillary premolars. 48 hours before the operation, frozen pork jaw halves were thawed in the refrigerator at 4°C. They were

SEM analysis
The replica models were placed on the alluminum specimen stubs (Agar Scientific Ltd., To evaluate the samples obtained from the apical portion of the root tips, 60, 190, 320 and 600 fold magnification options were required on the screen of the SEM. To determine the marginal gap value, two points were determined in the area of greatest expansion and the distance was measured in microns.

Preparation of the samples for Microradiography
After completion of the root-end fillings, teeth were osteotomised with hammer and chisel en bloque from the bone segment and stored in 4% formalin. With a band saw (Metabo, D-78822 Nürtingen Germany), the teeth were initially cut in half in vestibulo-oral direction, so that two root canals could be obtained seperately. The preparations were then placed over a period of two days in an embedder (PSI, CH-5232 Villingen) containing an alcohol series (20%, 40%, 60%, 80%, 90%, 2 times 100% for each 45 -60 minutes and finally 100% for 6 -dehydrated 8 hours) and then were soaked in methacrylate. The samples were placed in a methacrylate solution for another two weeks before they were placed in glasses capped with methacrylate and polymerized with fresh methacrylate solution in water bath at 38°C. The composition of the embedding medium is given in Table 3.
The polymerized samples were first cut with the band saw and the surfaces of the blocks were polished to 4000 with a Siliconcarbitpaper with a grain size of 400, before the cutting plane for the actual recovery preparations was determined. Each sample was cut along its sectional plane with the band saw again, surface was polished, glued to a microscope slide and reduced with a precision hole saw (Leica GmbH, D-64625 Bensheim) to 100-200 micron thickness. Since the comparisons template more than two independent, not normally distributed random samples, the H-test was used by Kruskal and Wallis. A p-value <0.05 was taken as statistically significant for all statistical tests. In the graphs, which were also created using SPSS, error bars were used to illustrate the mean values. The sealing ability of Harvard-Cement and gold foil was lower than amalgam and it was concluded that retrograde fillings with Ketac-Endo or Diaket can be considered as alternatives for amalgam.

SEM
In the literature, it has been proclaimed that microleakage is not completely inhibited with amalgam, zinc oxide eugenol cement or glass-ionomer cement. [5][6][7] Based on the results of the clinical and histological studies, it has been widely reported that ProRoot ® MTA stands out as the gold standard retrofilling material for apical seal 27 due to its superior charactheristics such as biocompatibility, non-toxicity, osteoinduction and cementogenesis 28 It has been suggested that, MTA provides a very good seal, has excellent marginal adaptation, maintains a high pH for a long period of time, and appears to induce a favorable tissue response. 29 In addition, Maltezos et al 30 have compared the sealing properties of Resilon, ProRoot ® MTA, and Super-EBA as root-end filling material and stated that ProRoot ® MTA presents significantly less leakage than that with amalgam, gutta-percha and zinc oxide eugenol in a dye leakage test and showed significantly less leakage than reinforced zinc oxide eugenol cement when evaluated using a bacterial leakage system. Similarly, Tanaka et al. 31 have reported that dye leakage of root-ends sealed without cavity preparation using 4-META/MMA-TBB resin was significantly less than that of root-end fillings using reinforced zinc oxide eugenol cement.      Figure 1 After completion of the root-end fillings, teeth were osteotomised with hammer and chisel en bloque from the bone segment    a AH -Plus ™ , which was viewed at 60x magnification on transversal plane. The root canal is almost completely obturated . The artifacts are created during processing and not due to the material . b AH -Plus ™ , which was viewed at 320 x magnification .The barely discernible edge gap proves despite inhomogeneity of the filler an excellent adhesion to dentin .      ProRoot® MTA at 320x magnification . A good connection of the coarse-structured material was observed .

Figure 12
Comparison of the marginal gap values of five different root-end filling materials Figure 13 Microradiographic evaluation of the root canal filling with Diaket ™ at 18x magnification. A "cracking" has formed in the filler during the preparation of the for the microradiography analysis. It has no effect on the marginal integration.

Figure 14
Microradiographic evaluation of the root canal filling with AH -Plus ™ at 18x magnification. The root canal could not be completely filled ; during processing emerged two large air pockets .

Figure 15
Microradiographic evaluation of the root canal filling with Super -EBA ™ Regular at 18x magnification. In addition to the artefacts in the root canal , the marginal gaps are clearly visible.

Figure 16
Microradiographic evaluation of the root canal filling with Super -EBA ™ fast at 18x magnification. The coarsely porous material adheres well to the dentin . The filling material is very rich in contrast.

Figure 17
Microradiographic evaluation of the root canal filling with ProRoot® MTA at 18x magnification. The retrograde preparation was sealed by the material . The inhomogeneous structure of the ProRoot® MTA is remarkable.