ENDODONTOLOGY. A comparative study of vertical fracture of roots obturated with new obturating systems - An in vitro study.

Transcription

1 Original Research A comparative study of vertical fracture of roots obturated with new obturating systems - An in vitro study Vimmi Singh # Neeta Shetty ## Kundabala M. ## ABSTRACT Introduction : The purpose of this invitro study was to evaluate the post obturation fracture resistance of endodontically treated teeth obturated with new obturating systems such as Realseal system, GuttaFlow obturation system, conventional lateral compaction technique and Microseal obturation system. Materials and Methods : Fifty extracted single rooted teeth were selected and sectioned at the CEJ. The root canals were instrumented using EasyRace files. The teeth were randomly divided into 5 groups of 10 teeth each. Group I served as negative control and was instrumented and not obturated. The other groups were obturated with new obturating systems. The specimens were evaluated for vertical fracture resistance using Instron universal testing machine. Results : According to the study it was found that the Resilon with Realseal displayed higher mean fracture load in comparison to other experimental groups. Conclusion : Obturation of roots with a resin based obturation material increased the fracture resistance of root canal filled tooth to vertical fracture. Key words : Vertical fracture, obturation, monoblock, Resilon, GuttaFlow, Microseal Introduction The objectives of root canal treatment are removal of diseased pulp, shaping and cleaning of the root canal and three dimensional obturation with an inert material to obtain a fluid tight seal to prevent re-infection. 1, 2, 3 Vertical root fractures are complications that are mostly seen in root canal obturated teeth and often lead to extractions. 4 Schilder 5 suggested that the ideal root canal obturating material should be well adapted along the entire length of the root canal walls and produce a homogenous mass. Currently with the application of adhesive dentistry in endodontics, the present concept of obturation of the root canal is not just the three dimensional filling of root canal and accessory canals, but also the reinforcement of the root. The ability of gutta percha to reinforce an endodontically treated root is still controversial. 6 It is suggested that bonding of endodontic adhesive sealers to root dentin and also to the obturating material may enhance the fracture resistance of root filled teeth, so their use has been suggested to reinforce the root canal walls. 7 The concept of sealing and tooth strengthening by using adhesive root canal obturating materials is known as monoblock effect. 8,9 To achieve this monoblock effect,an obturation system was introduced in 2004, known as Epiphany (Pentron clinical Technologies.LLC Wallingford CT.USA) which contained Resilon cones and resin based sealer. Resilon cones are thermoplastic synthetic polymer based root canal filling materials and polymers of polyester. GuttaFlow (Coltène/ Whaledent Inc. 235 Ascot Parkway Cuyahoga Falls, # Conservative Dentistry and Endodontics, Nepal, ## Dept. of Conservative Dentistry and Endodontics, Manipal University, Manipal College of Dental Sciences, Mangalore 85

2 VIMMI SINGH, NEETA SHETTY, KUNDABALA M. Ohio / USA) is a cold flowable root canal filling paste system. It is said to offer excellent flow, good adaptability to root canal walls, ease of use, low setting time within 10 minutes and slight expansion on setting (0.2%). 10 The Microseal system (Analytic Endodontics,Glendora,CA 91740) is a thermomechanical filling technique that uses a laterally compacted master gutta-percha cone and placement of gutta-percha to backfill the canal. Microseal is a recent obturating system for which the resistance to vertical fracture is not known. Hence this study was conducted to evaluate and compare the effect of different obturation systems on the fracture resistance of endodontically treated tooth, such as RealSeal obturating system (SybronEndo,Orange,CA) GuttaFlow system, conventional lateral compaction technique and Microseal system. Materials and Methods : Preparation of the specimens Fifty freshly extracted single rooted human teeth were selected & stored in saline solution. The teeth were sectioned at the cementoenamel junction with a diamond wheel saw (Mani,Japan) The sectioned teeth were randomly divided into 5 groups consisting of 10 teeth each.access cavities were prepared using an airotor hand piece and endoaccess bur. (Dentsply Maillefer CH-1338 Ballaigues). The working length was determined by according to Ingle s working length technique. 11 The roots were prepared by using #.04 taper EasyRaCe nickel-titanium rotary files.(fgk Dentaire Swiss dental products) according to manufacturers instructions along with the use of 1ml of 2.5% sodium hypochlorite (Novo dental products Ptv.Ltd,India) and normal saline (Goa Formulation Ltd, India) as irrigants, and were finally flushed with 17% EDTA (B.N laboratories,india) and dried with paper points ( DentsplyMaillifer. CH-1338 Ballaigues) Obturation of the root canals: Groups I - Served as negative control group. Roots were not instrumented and not obturated. Groups II (Realseal obturation system) A size 40, #.04 taper Resilon cone was inserted to the working length with tug-back. The primer and sealer were applied according to manufacturer s instructions. Then, the master Resilon cone of was gently seated into the canal and obturated with lateral compaction method. Coronal aspect of material was light cured for 40 seconds. Group III- (GuttaFlow obturation system) A master GuttaFlow gutta percha point of size 40,#.04 taper is selected and obturated using lateral compaction method, following manufacturers instruction for manipulating GuttaFlow. Excess obturating material was removed with a heated hand instrument. 12 Group IV (Conventional lateral compaction technique.) Canals were obturated using lateral compaction technique with master gutta percha cone (SureDent Corporation, Korea) of size 40, #.04 taper is selected and coated with the zinc oxide eugenol sealer (Deepti, Vishal Dental products, India). Group V-( Microseal obturation system) A Microseal master gutta percha cone of size 40,#.04 taper is selected and obturated using lateral compaction method, following manufacturers instruction for manipulating Microseal compactor. 13 The access cavity was sealed with glass ionomer restorative cement (GC Corporation Tokyo,Japan).All the specimens were kept at 37 c 86

3 A COMPARATIVE STUDY OF VERTICAL FRACTURE OF ROOTS OBTURATED WITH NEW OBTURATING SYSTEMS - AN IN VITRO STUDY with 100% humidity for at least 72 hours to allow the sealers to set completely.the roots were fitted into tight-fitting rubber tubing to simulate the periodontal ligament Epoxy resin was mixed to a thin consistency and poured into plastic blocks in which the roots were vertically placed. Instron universal testing machine (Model no.3366 U.K). A special device/jig (fig 1) was fabricated with stainless steel to hold the finger spreader with frictional grip latch, which was attached to the unit of the universal testing machine with the help of screw.the access cavity restoration was removed and then the blocks with embedded roots were mounted onto the Instron universal testing machine. A size 40, length 25mm 0.02% taper hand stainless steel spreader is placed on the universal testing machine fixture and placed directly above the root canal orifice,to penetrate through the obturatng material. The machine was calibrated to vertically drive the spreader into the root canal at a speed of 10mm/min. Force was applied to the root until it fractured. The force applied to fracture the tooth vertically was recorded and data from all experimental groups were collected and statistiscally analysed using Kruskal-Wallis test and intergroup comparison was done by Mann-Whitney U test. Results : Compressive load at max compressive extension is shown in table 1. Due to unusual distribution of the data, nonparametric tests were applied to check the statistical significance between the groups. According to the results (graph 1), group II showed the maximum resistance to fracture (median value ) and group IVshowed the minimum resistance to fracture (median value ).The root canals obturated with Resilon and RealSeal sealer resulted in significant increase in the resistance ( p value-0.000) to fracture compared to other groups. Inter group comparison between group I and group II is significant with Z value is and (P value is significant). Inter group comparison between group II and group III, group IV and group V is significant with Z value and respectively. The other groups were not significantly different from each other. Compressive Load at Max Compressive Extension COMPARISON Z P GI vs. GII GI vs. GIII GI vs. GIV GI vs. GV GII vs. GIII GII vs. GIV GII vs. GV GIII vs. GIV GIII3 vs. GV GIV vs. GV Table1- Inter group comparison performed by Mann- Whitney U test. (Z) Graph 1- Compressive load at maximum compressive extension for all the experimental groups. 87

4 ENDODONTOLOGY VIMMI SINGH, NEETA SHETTY, KUNDABALA M. Fig 1: Special jig fabricated to hold speraders Fig 2: Specimen mounted on universal testing machine Discussion : forces of the spreader driven into the canal without resistance could be the reason for the highly The present study found that the resistance to significant values.14 fracture of the obturated teeth was better in case of teeth obturated with the adhesive obturating system Resilon obturating material - Epiphany as the RealSeal. The traditional obturating material gutta bonding agent (sealer) attaches the resin core to the percha does not provide chemical bonding to the dentinal wall, thus forms monoblock.9 All the other root canal wall, so recent research in obturation materials in the present study created mechanical materials is focused on the introduction of resins bond between the sealer and dentinal wall. The into the cones and the sealer.inter group adhesion and mechanical interlocking between the comparison between group I (instrumented and material and the root canal dentin prevents unobturated root canals) and group II is significant microleakage and reduce the risk of fracture. The with Z value is and (P value is results regarding Resilon in our study were in significant),which shows the importance of accordance with some previous studies.14,15 Sagsen obturating the canals after disinfection.root canal et.al7, in their study concluded that root canals instrumentation is an unavoidable step in obturated with Resilon cones and epiphany sealer endodontic treatment,dentin is removed during this were able to reinforce the prepared root canals. phase,thus a weaking effect on the root is inevitable.14 Also clinically one never leaves an The bondability of Resilon to methacrylate root canal unfilled,so group I was considered as a resin based root canal sealers is supposed to be negative control group and showed least resistance derived from the inclusion of the urethane when compared with the other groups.the wedging dimethacrylate resin. It contains two interface one 88

5 A COMPARATIVE STUDY OF VERTICAL FRACTURE OF ROOTS OBTURATED WITH NEW OBTURATING SYSTEMS - AN IN VITRO STUDY between the sealer and primed dentin, another between the sealer and Resilon, hence may be classified as a secondary type monoblock. 9 So this property of Resilon could be the reason for the positive result in our study and the nonadhesive obturating materials showed poorer result compared to it. Contrary, Ulusoy etal 16 in their study found that the use of AH 26 and gutta.grande NM etal 17 concluded that the currently available endodontic-filling materials and their recommended adhesive procedures are not able to influence the mechanical properties of root canal dentin and that the flexural properties of Resilon and gutta-percha are too low to reinforce roots. According to studies by Tay FR etal Resilon seems to be biodegradable under the attack of hydrolytic ester bond cleaving enzymes or as extracellular enzymes from endodontically relevant pathogens.resilon is also susceptible to alkaline hydrolysis, therefore long term studies are necessary. 18,19 The reason for poor resistance to vertical fracture of the GuttaFlow system compared to Resilon could be that there is no chemical union between the discrete gutta filler particles and the gutta percha master cone. 15,20 Thus the use of a primer to promote a chemical bond between the trans1,4-polyisoprene component of the sealer should be considered. The Microseal system utilizes alpha form guttaprecha which has lower melting point, lower viscosity and higher flow when compared to the beta form gutta-percha. 11 Although recent advances in adhesive obturating materials have stimulated interest, there are few studies supporting its ability to reinforce the endodontically treated tooth and resist vertical fracture. To reconfirm the result of the present study further studies have to be undertaken with more number of samples, under ultrastructural scanning microscope and also other required properties have to be confirmed. Conclusions : The present study concluded- 1. Resilon with RealSeal sealer is the best material among the experimental groups to resist the post obturation vertical fracture. 2. Gutta Flow, Microseal and Gutta percha with zinc oxide sealer cannot resist vertical fracture as well as Resilon. References : 1.Walton RE, Torabinejad M. Principal and practice of endodontics.3 rd ed. Philadelphaia;Saunders, Schilder H. Cleaning and Shaping the root canal. Dent Clin North Am 1974;18: Cohen S,Burns R.Pathways of the pulp.8 th ed.st Louis:Mosby, Fuss Z,Lustig J,Katz A,Tamse A.An Evaluation of Endodontically Treated Vertical Root Fractured Teeth: Impact of Operative Procedures.J Endod 2001;27: Schilder H. Filling root canals in three dimensions. J Endod 2006;32: Schäfer E, Zandbiglari T, Schäfer J. Influence of resin-based adhesive root canal fillings on the resistance to fracture of endodontically treated roots: an in vitro preliminary study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007; 103: Sagsen B, Er O, Kahraman Y, Akdogan G. Resistance to fracture of roots filled with three different techniques.int Endod J;2007; I40: Karapinar Kazandag M, Sunay H, Tanalp J, Bayirli G. Karapinar Kazandag M, Sunay H, Tanalp J, Bayirli G. Fracture Resistance of Roots using Different Canal Filling Systems. Int Endod J 2009; 42: Tay FR,Pashley DH. Monoblocks in root canals:a hypothetical or a Tangible Goal. J Endod 2007; 33: ; 10. Herbert J, Bruder M, Braunsteiner J, Altenburger MJ, Wrbas K. Apical quality and adaptation of Resilon, Endorez, and 89

6 VIMMI SINGH, NEETA SHETTY, KUNDABALA M. Guttaflow root canal fillings in combination with a noncompaction Technique. J Endod 2009, 35: Ingle JE,Bakland LK.Endodontics, 5 th ed. Hamilton, Ontario,Canada:BC Decker Inc, Guttaflow instruction for use.coltene /Whaledent Inc,Cuyahoga Falls,OH.February Microseal instruction for use.sybronendo-1332 S Lone Hill Ave-Glendora,CA Teixeira FB,Teixeira EC,Thompson JY,Trope M..Fracture resistance of roots endodontically treated with a new resin filling material. J Am Dent Assoc May 2004;135: Hammad M,Qualtrough A,Silikas N.Effect of New obturating Materials on vertical root fracture resistance of endodontically treated teeth. J Endod 2007;33: Ulusoy ÖÏA,Genc Ö,Alacam T,Görgül G.Fracture reistance of roots obturated with three different materials.oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104: Grande NM, Plotino G,,Lavorgna L,Ioppolo P,Bedini R,Pameijer CH,Somma F. Influence of Different Root Canal Filling Materials on the Mechanical Properties of Root Canal Dentin.J Endod 2007 ;33: Tay FR,Pashley DH,Yiu CKY,Yau JYY,Yiu-fai M,Loushine RJ,et al.susceptibility of a polycaprolactone-based root canal filing material to degradation.ii.gravimetric evaluation of enzymatic hydrolysis.j Endod 2005;31: Tay FR,Pashley DH,William MC,Raina R,Loushine RJ,Weller RN,et al.susceptibility of a polycaprolactone-based root canal filing material to degradation.i. Alkaline hydrolysis.j Endod 2005;31: Monticelli F, Sword J, Martin RL, Schuster GS, Weller RN, Ferrari M, Pashley DH, Tay F R. Sealing properties of two contemporary single-cone obturation systems. International Endodontic Journal 2007; 40: