ENDODONTOLOGY. An in-vitro evaluation of apical sealing of three epoxy resin based commercial preparations INTRODUCTION MATERIALS AND METHODS ABSTRACT

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1 An in-vitro evaluation of apical sealing of three epoxy resin based commercial preparations Vishal A. Mahajan * Kamra A. I. ** ABSTRACT The aim of the present in vitro study was to evaluate and compare the apical microleakage observed in teeth obturated with gutta purcha and three different epoxy resin based root canal sealer using lateral condensation method. In this study 40 freshly extracted maxillary central incisors with straight. Root canals were used. Teeth were prepared using gates glidden drill and stainless -steel.hand K files. After preparation teeth were divided into three different groups for obturation according to sealers used, Group A - AH 26. Group. B - AH Plus. Group C - RC Seal. The obturated specimens were then stored in 5% Methylene blue dye (ph 7.0) at 3 o c for seven days. The amount of leakage was measured under a stereomicroscope. It was seen that Group C had shown higher microleakage than Group A and Group B. Key words: apical microleakage, epoxy resin based sealers, stereomicroscope. INTRODUCTION Three-dimensional sealing of the root canal is the final phase of endodontic treatment and is essential for preventing reinfection of the canal and for preserving the health of the periapical tissues, thereby ensuring success of root canal treatment. 4 The filling techniques which are most often applied involve the use of gutta purcha cones and an endodontic sealer. 1 The sealer performs various functions during the obturation of root canal system: viz., it lubricates the root canal and aids the sealing of the master gutta purcha cone, acts as a binding agent between the gutta purcha and the canal wall and fills anatomical spaces the primary filling material has failed to reach. 5 A great variety of endodontic sealers are available commercially, and they are divided into groups according to their chemical composition. They are based on zinc oxide and eugenol, epoxy resin, calcium hydroxide and glass ionomer. 4 Root canal sealers leak to some extent and most leakage occurs between root canal walls and the sealer therefore the ability of sealer cement to bond to tooth structure is considered important.1 o Epoxy resin based resin sealers are glue like materials and are known for their adhesive property to root canal wall. 2 Therefore, this study is aimed to compare the apical microleakage of three commonly used epoxy resin based root canal sealer cements. MATERIALS AND METHODS Table 1 and 2 represents list of materials and armamentarium used for this study. In this study 40 *Postgraduate student. ** Professor and Head. Dept of Conservative Dentistry, Government Dental College & Hospital, Aurangabad Maharashtra. 7

2 AN IN VITRO EVALUATION OF APICAL SEALING OF THREE EPOXY RESIN BASED COMMERCIAL PREPARATIONS freshly extracted maxillary central incisors with straight root canals were used. After extraction the teeth were stored in 10% formalin. 10 Before preparation all teeth were mechanically cleaned with hand scaler to remove surface soft tissue and calculus. Routine access openings were prepared. A size 15 file was inserted into the root canal until the tip became visible at the apical foramen; this distance minus 1 mm was taken as the working length. 10 The coronal portion of the canals were preflared using Gates Glidden drills and apical portion of canals were prepared to, a size 45 file, alternately irrigating after each file with 5 ml of 3% sodium hypochlorite and isotonic saline. EDTA was used during instrumentation to remove the smear layer. The canals were finally dried with paper points and the patency of the apical foramen confirmed with a size 10 K-File. Specimens were randomly divided into three main groups, of 10 teeth each. All teeth were obturated to the working length by lateral condensation of gutta-percha cones and sealer. In the first group, AH26 was used as the sealer; AH Plus sealer was used in the second group and RC Seal is used in third group. Each material was prepared and used according to the manufacturer s instructions. Radiographs were taken from the buccal aspects of each tooth to assess the quality of the root canal filling. Five teeth are taken in group of positive control and five teeth are taken in group of negative control. Teeth showing evidence of questionable obturation were refilled. The access openings were sealed with Composite resin and specimens stored for 24 hours in 100% relative humidity at 37 o C to allow the sealers to set. For evaluation of apical leakage, the root surfaces of all specimens were coated with three layers of nail varnish and sticky wax leaving only the apical 2 mm exposed. The obturated specimens were then stored in 5% Methylene blue dye (ph 7.0) at 37 o C for seven days. After removal from the dye, the specimens were washed with distilled water, dried and the nail varnish removed with a scalpel. The root of each tooth was grooved longitudinally on both sides, using a rotating diamond disc under constant cooling with distilled water, without disturbing the gutta-percha filling. The root was then carefully sectioned, and each half examined under a stereomicroscope. The amount of leakage was measured in each half of each tooth, from the working length to the most coronal part of the root canal to which the dye had penetrated. 10 Two independent measurements were made for each tooth, using a calibrated ocular micrometer and the mean recorded. To determine any statistical difference the data were subjected to unpaired t- test. RESULTS AND OBSERVATIONS Table 3 (Graph 1) represents dye penetration for all three groups. All the three groups demonstrated leakage. AH26 is showing the least leakage followed by AH Plus while RC Seal is exhibited highest leakage among the three groups tested. Table 4 is depicts the statistical analysis. The difference between AH 26 and AH Plus was not statistically significant while there was statistically significant difference between AH 26 and RC Seal and AH Plus and RC Seal (P< 0.05).The negative controls demonstrated dye penetration in all or much of the root canal; in contrast, no leakage was seen in the positive controls. 8

3 Vishal A. Mahajan, A. I. Kamra Table 1 LIST OF ARMAMENTARIUM SR.NO. ARMAMENTARIUM SR.NO. ARMAMENTARIUM 1. Contra angle micromotor handpiece 6. Mini Endo block (NSK, Japan) (Mailleffer- Dentsply. France) 2. Air-roter handpiece (WnH) 7. Diamond disc 3. Gates Glidden Drills (Dentsly, Switzerland) 8. Cotton pliers, gloves, cement spatula, ball burnisher, spirit lamp 4. K- Files (ISO 10-40, Mani, Japan) 9. Nail varnish 5. Finger spreaders and pluggers 10. Stereomicroscope (ISO 15-40, Mani, Japan) (Olympus SZ 4045) SR. NO MATERIAL USED 15% EDTA gel Epoxy resin- based sealer 3% sodium hypochlorite solution Gutta- percha points. Absorbent points Composite Resin Normal saline Table 2 LIST OF MATERIALS TRADE NAME AND MANUFACTURER Glyde File Prep- Mailleffet- Dentsply, France. AH 26- De Trey/Dentsply, Germany. AH Plus- De Trey/Dentsply, Germany. RC Seal- Prime dental products,lndia. Vishal Dentocare Pvt. Ltd., India. Standardized ISO 15-40, Tanari, Brazil. ISO 15-40, Mailleffer- Dentsply, France. Solare- GC Corp. Japan Claris Lifesciences Ltd., India. Table 3 MICROLEAKAGE IN ALL GROUPS Group A AH 26 Group B AH Plus Group C RC Seal PC NC Mean No leakage Complete. leakage SD Table 4 STATISTICAL ANALYSIS Unpaired - t Test Group A vs Group B Group A vs Group C Group B vs Group C P > 0.05 P< P < Not Significant Significant Significant Significance level - P <

4 AN IN VITRO EVALUATION OF APICAL SEALING OF THREE EPOXY RESIN BASED COMMERCIAL PREPARATIONS DISCUSSION There is a wide variation in the sealing capacity of different endodontic materials and achieving an adequate apical seal is an important goal in endodontics. When evaluating root-canal filling material, analysis of its sealing ability is therefore very important. 10 Epoxy resin based sealers are glue like materials and known for their, adhesive properties. 2 Epoxy resin based sealers chosen for our study were AH 26, AH Plus and RC Seal. The AH26 sealer contains bisphenol A epoxy base and catalyst is hexamethylene - tetramine. It is has advantages like high radiopacity, low solubility, slight shrinkage and tissue compatibility. However, it has disadvantages like formaldehyde release and extended setting time. Manufacturers of AH Plus claim that they have not only retained the epoxy resin glue of AH 26 and the mechanical properties, but have overcome the disadvantages of AH26 like extended setting time and formaldehyde release. RC Seal is also an Epoxy resin based sealer having properties comparable to AH26. Under the conditions of our study, none of the materials produced an effective apical seal, and most leakage occurred between the wall of the root canal and the sealer. It is often stated that leakage may be influenced by the ability of a root-canal sealer to bond to the dentinal wall or at least to maintain permanent contact with the wall. 10 In this respect we found that RC Seal demonstrated maximum leakage and AH26 exhibited the least. In the present study, AH Plus was found to show more leakage as compared to AH26, but the difference was not statistically significant. The finding of the present study are in agreement with those of 1 Miletic et al 7 who suggested that AH plus demonstrates greater microleakage than AH26 but the result was not statistically significant. Zmener 10 also found that there was statistically significant difference between leakage obtained by AH26 and AH Plus. When compared with AH26, the faster setting of AH Plus and its more pronounced shrinkage stresses may account for possible earlier debonding of the sealer from dentine walls and the greater leakage detected after immersion periods. The sealing ability of AH Plus may also be affected by other factors; for example, AH Plus contains silicone oils and other ingredients. As all specimens were kept in 100% humidity one can speculate that oilbased materials such as AH Plus could prevent complete wetting of the root-canal wall and adhere poorly to humid dentine. This may result in poor adaptation of the material to the root-canal wall, as well as formation of voids that enhance dye penetration. 1O However our study does not support the findings by AL-Khatar who suggested. that AH Plus demonstrates significantly less microleakage than AH 26. Another study done at Hamboldt University, Berlin also demonstrated that AH Plus exhibited significantly less microleakage than AH Currently no literature is available regarding microleakage of RC Seal. The composition of RC Seal is similar to that of AH 26 but the difference in microleakage is observed may be due to poor initial adaptation, solubility and disintegration, 3 improper blending of filler particles, filler particle size or film thickness 5. 10

5 Vishal A. Mahajan, A. I. Kamra SUMMARY AND CONCLUSION Within limitations of our study RC Seal is showing the highest microleakage while AH 26 is showing the least. Results of the present study should be interpreted with caution, and need to be investigated further. References: 1. Cohen S. Pathways of the pulp 8th Ed. Mosby publication, Ingle I J. Endodontic therapy 5th Ed. B.C. Decker Elsevier Lacey S et al, A study of rheological properties of endodontic sealers International Endodontic Journal, 38, , Lucena- martin C. et al, A comparative study of apical leakage of endomethasone, topseal and roekoseal cement. J Endodon 26(6), june Mc Michen F.R.S.et al, A comparative study of selected properties of five root canal sealers. International Endodontic Journal,30, , Miletic I et al, Apical microleakage of five root canal sealers after one year stoarage. J Endodon 26(6),june Miletic I et al, Leakage of five root canal sealers, International Endodontic Journal, 32, , RC Seal product information Zmener O. et al, Sealing properties of a new epoxy resin based root canal sealer, International Endodontic Journal 1997, 30,