Clinical and radiological evaluation of cast metal and quartz fibre posts in endodontically restored teeth

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1 Original Research Clinical and radiological evaluation of cast metal and quartz fibre posts in endodontically restored teeth SHASHIKALA K * # SONALI SHARMA ** ## ABSTRACT Forty one maxillary anterior teeth indicated for post and core and patients of either sex between the age group of 8-25 years who fulfilled the selected criteria were involved in this study. All the selected teeth were endodontically treated and the post space preparations were performed by rotary instruments. Patients were randomly divided into two groups: Cast Metal Posts [MP] group which served as control and Quartz Fibre Post [FP] the test group. After cementation of the posts in both groups as per standard procedure, ceramic restorations were placed. Periodic evaluation was carried out at 3, 6 and 9 months. The clinical parameters assessed were debonding at post-core and tooth interfaces, core fracture, crown fracture, periodontal status and aesthetics. The radiological parameters assessed were root fracture, post fracture, periapical status and post adaptation in the root canal. The data was tabulated and statistically analyzed. Survival analysis by Kaplan Meier and median survival time methods were compared using Wilcoxon Test. Results suggest Fibre post and core group showed only one failure whereas cast metal group exhibited three failures. However, there was no statistical significant difference between the groups. Key words: Quartz fibre posts; Cast metal post, Pre fabricated post. INTRODUCTION The most important reason for the emergence of endodontics to the forefront of clinical dentistry is a perfect balance between the understanding of the basic scientific principles and evolving technologies. The restoration of endodontically treated teeth is an important aspect of dental practice that involves a range of treatment options of varying complexities. The successful restoration of an endodontically treated teeth is an ongoing challenge for a restorative dentist. 2 Present day clinicians are well aware that The naturally retained root is the ultimate dental implant. The endodontically treated teeth with extensive loss of tooth substance have numerous problems due to significant reduction in the capability to resist a myriad of functional forces. 3 Successful restoration of root filled teeth requires an effective coronal seal, protection of remaining tooth, restoration of function and acceptable esthetics. 3 The final restoration will include a combination of dowel/post and core and coronal restoration. 4 Endodontic posts have been classified in various ways, the preformed and custom cast, metallic and non-metallic, stiff and flexible, aesthetic and non aesthetic. 4 Posts are required for supporting a core foundation when there is insufficient clinical crown remaining. The choice of dowel /post design should be in * Prof &Head, ** Senior Lecturer, Dept of Conservative Dentistry& Endodontics, # R.V. Dental College & Hospital, Bangalore, ## A.C.D.S, Secunderabad. 37

2 SHASHIKALA K, SONALI SHARMA accordance with the biomechanical requirements of the remaining tooth structure. 3 Various methods of restoring pulp less teeth have been reported for more than 2 years. In 747, Pierre Fauchard described the process by which roots of maxillary anterior teeth were used for restoration of single teeth and the replacement of multiple teeth. Posts were fabricated of gold or silver and held in the root canal space with a heat softened adhesive called mastic. 5 In 99 Duret et al described a non metallic material for the fabrication of posts based on carbon reinforcement principle. Carbon fibres posts are black in colour and do not lend themselves to aesthetic restorations with all ceramic units. This led to the introduction of the silica fibre posts which are translucent and more tooth coloured. These posts are also called glass fibre and quartz fibre posts. 6 One of the functions of a post and core is to improve resistance to laterally directed forces by distributing them over as large an area as possible. 7 when two or more components are placed in contact with one another, the components and interfaces created will be subjected to considerable clinical and functional demands. Components with higher elastic-modulus (cast post/core) will transfer functional stresses to the lower elastic-modulus components (dentin) and ultimately result in endodontic or restorative failure. When all components have similar elastic-moduli there is a uniform stress distribution and lowered interfacial stress and failure. This phenomenon has been coined monobloc. Monobloc requires that all components of a tooth restoration have similar elastic moduli to dentin to allow the components 38 to move, flex, and stresses one assembly. This phenomenon is incorporated in fibre posts. 8 Accumulation of metallic corrosion byproducts also weakens the dentin and the interface between the post and the canal. The newer fibre-reinforced post systems preserve tooth structure, are non corroding, and have a similar elastic modulus compared to dentin making them more compatible than their metal counterparts. 8 The retention of metal posts can be affected by shape, post-surface area, and type of cement used. Parallel posts need too much tooth structure to be removed. Tapered, cemented posts need retentive characteristics (grooves, threads) for sufficient retention. The newer post systems (fibrereinforced) use bonding instead of cementing for increased retention. With a bonded post, it is unnecessary for retention to come mainly from its design or surface features. 8 Fibre posts are ready to use whereas construction of a cast metal post and core is more time consuming and demands extra clinic and laboratory time. One of the major clinical advantages of fibre-reinforced post is the ability to remove them expediently and without trauma. Fibre posts are not retrieved in one piece like a cast or prefabricated post, but are removed from the canal by drilling down directly through them. Metal post systems have a much higher potential for causing allergic reactions and other adverse biologic effects. Carbon fibre/quartz-glass fibre posts have a lower allergenic potential and are generally considered to be more biocompatible. 8 Research on biomechanics of post and cores over the past decade has replaced many of our traditional ideas with data as to how and when to

3 CLINICAL AND RADIOLOGICAL EVALUATION OF CAST METAL AND QUARTZ FIBRE POSTS IN ENDODONTICALLY RESTORED TEETH best restore these teeth. Success can only be achieved when the technique choice best meets the needs of the individual, specifically the needs of the individual diseased tooth and the clinical use for which it is intended. 9 MATERIALS AND METHODS METHOD OF COLLECTION OF DATA Forty one maxillary anterior teeth, indicated for post and core were selected for the study. The patients of either sex between the age group of 8-25 years and who fulfilled the selection criteria referred to Department of Endodontics, were included in the study. After approval from Ethical Committee Board, the written informed consent were obtained from all the individual participants involved in the study. INCLUSION CRITERIA Non vital, discolored, single rooted maxillary anterior teeth with cervical and middle third crown fracture were included. Teeth with healthy periodontal status and occlusion with sufficient over jet and over bite were included. Teeth with complete root formation and without any anatomic variation were taken in to consideration. Endodontically treated teeth, Patients willing to give written informed consent and agreeing for regular follow up were selected. EXCLUSION CRITERIA Non-vital multirooted teeth, Patient aged less than eighteen years, Teeth with poor periodontal status / with large persistent periapical lesion. Malocclusion with deep bite, edge-to-edge bite and cross bite. PROCEDURE After clinical and radiological examination and confirmation of eligibility criteria the selected cases were randomly divided into two groups; Cast Metal Post [MP] Group served as control and Quartz Fibre Post [FP] Group as the test group. MP Group - Twenty anterior root treated teeth were restored with the conventional custom-made cast metal posts prepared by direct wax pattern technique, invested and casting procedure were carried with nickel chrome alloy using induction casting machine. FP Group - Twenty one anterior root treated teeth were restored with the prefabricated quartz fibre posts. Endodontic treatment was completed for all the involved teeth as per standard procedure using gutta-percha/zinc oxide sealer as obturating material/lateral compaction technique. After no less than 48 hours from the endodontic treatment, the involved teeth were prepared for receiving the posts. Leaving 4 millimetres of gutta percha in the apical third of root canal, the remaining gutta percha was removed by hand instruments. The direct wax pattern was taken in group MP and invested. Casting procedure was carried out in induction casting machine [Bego-Germany]. The custom made post and core was then cemented in the root canal using glass ionomer luting cement [GC]. Later, the ceramic crowns [Cera Bond] were fabricated and cemented. In cases of group FP, after selection of appropriate drill size provided with the prefabricated post kit, the root canal space was prepared leaving at least 4 mm of gutta percha apically. The prefabricated posts Mirafit White [Kuraray America] were tried in the canal as per the manufacturer s instructions. All the root canals 39

4 SHASHIKALA K, SONALI SHARMA were treated with the bonding system ED primer (Kuraray America) supplied with the kit. The fibre posts were then cemented with dual- cure adhesive resin cement Panavia F 2. ( Kuraray America). The core was built up with photo core build up material, clearfil photo core (Kuraray America), provided by the manufacturer. The ceramic crowns were fabricated later and cemented [figure ]. All the treated cases were recalled at an interval of 3, 6 and 9 months for clinical and radiological evaluation. The clinical parameters of evaluation were debonding at the post / core and the tooth inter phase, mobility of the tooth, crown fracture, periodontal status and aesthetics. The Radiological evaluation parameters were root fracture, crown fracture, periapical status, and adaptation of the posts in the root canal. METHODS OF STATISTICAL ANALYSIS The Exceland SPSS (SPSS Inc, Chicago) software packages were used for data entry and Analysis, the unit of analysis was the tooth and teeth were referred to as cases. Statistical analysis was done by Kaplan Meier analysis for survival analysis, Wilcoxon test was done for evaluating median survival time and Chi square test of significance was done for proportion analysis. At the bivariate levels, the following independent variables were assessed: patient s sex and age, post type, tooth type and their location. Variables were created for tooth type, event status (i.e., post failure vs. nonfailure), and time to event, and were assigned numerical values. Time-to-event was defined as the time, in months, between the date of insertion of the post and the date of failure of the restoration. Censored observations were cases for which failure did not occur during the observation period. However, censored observations contributed time to the analysis. A B C D E Figure: Clinical steps in Fibre post placement in tooth and 2; A) Preoperative photograph. B) Fibre- post placement. C) Application of oxygaurd to offset oxygen inhibition. D) Core build-up. E) Cementation of ceramic crowns. 4

5 CLINICAL AND RADIOLOGICAL EVALUATION OF CAST METAL AND QUARTZ FIBRE POSTS IN ENDODONTICALLY RESTORED TEETH Figure 2: Distribution of failures by post type NATURAL TOOTH CAST METAL POST FIBRE POST Figure3. Stress pattern generated on application of inclined load of 7 N. 4

6 SHASHIKALA K, SONALI SHARMA TABLE II : LIFE TABLE OF CAST METAL POST Interval Start Time Entering this Interval Withdrawn during interval Exposed to Risk of Terminal Events Terminating Surviving Cumulative Surviving at End Hazard Rate ** The median survival time for these data is 27. TABLE III : LIFE TABLE OF FIBER POST Entering this Interval Withdrawn during interval Exposed to Risk of Terminal Events Terminating Surviving Cumulative Surviving at End Hazard Rate ** The median survival time for these data is 27. Comparison of survival experience using the Wilcoxon (Gehan) statistic statistic df. Prob

7 CLINICAL AND RADIOLOGICAL EVALUATION OF CAST METAL AND QUARTZ FIBRE POSTS IN ENDODONTICALLY RESTORED TEETH RESULTS In this in vivo study the clinical and radiological performance of quartz fiber post [FP Group] was compared to cast metal post [MP Group] at a time interval of 3, 6 and 9 months. Both the groups were equally distributed in the study. It was observed that the mean age group in this study was 37.7 years. The final outcome of the study was not affected by age or gender nor tooth type specific. The failure rate of FP Group was 4.8 % as compared to 5 % in MP Group. In FP Group there was only one failure, due to debonding of the post at post tooth interface. In MP Group three failures were seen, one biological that resulted in periapical breakdown, one crown fracture and one failure in post adaptation in the canal [figure2]. The probability of survival of MP Group was 85 % and that of FP Group was 95 %. The median time of survival in each group was 27 days (Tables II and III). Though FP Group performed better than MP Group, the results, however were not statistically significant. DISCUSSION Endodontic treatment has progressed significantly over the last two decades leading to greater knowledge, clinical success and concomitant cost of endodontic treatment. Failure in teeth that have been root canal treated is more likely to be the result of failure of the restoration that has been placed, rather than the endodontic treatment itself. Many retrospective studies on the clinical performance of fibre posts have been published. However, most of them were unable to ensure an adequate control of all variables that might come into play under clinical conditions. On the other hand, in a prospective study design many of the variables possibly involved are already controlled at the stage of case selection, and experimental groups can be made homogenous in all but the variable under study. Thus, the variables under study which are the different materials used for post and core restoration, became the factors most crucially responsible for the variability in the clinical performance of the teeth over time. The cast metal post and core has been the traditional and time honoured method of restoring endodontically treated teeth. However, there are some disadvantages associated with conventional post and core systems such as poor retention of the post, greater incidence of root fracture, and risk of corrosion when different metals are used in the system. 2 Fabrication of cast metal post and cores can be time consuming and involves additional laboratory cost. The laboratory procedure itself may introduce errors within casting and thus increase risk of failures. This drawback of cast metal alloy post system has also been observed and experienced in this study. A growing interest in aesthetic dental restorations and adhesive dentistry has led to development of innovative post materials and techniques for restoration of endodontically treated teeth. These newer systems, like quartz fibre post have focused on physical properties, such as modulus of elasticity, that are closely matched to dentin to decrease stress concentration within the root canal and reduce the incidence of fracture. Most of the fibre posts can be removed from a root canal with ease and predictability when necessary, without compromising core retention in cases of endodontic retreatment. 3 In the present study there 43

8 SHASHIKALA K, SONALI SHARMA were no failures necessitating re-treatment in fibre group. Impact of the periodontal status on the survival of endodontically treated teeth was discussed by Naumann et al. 4 Periodontal failures of endodontically treated teeth were the second most frequent cause of failure [32 %] after crown fractures [6 %]. Increased reduction of the bone support lead to a marked decrease of the load capability of a post -retained post -endodontic restoration. 4 In the present study the exclusion criteria have been very stringent, the periodontal status as well as periapical status has been assessed preoperatively. Thus cases with doubtful periodontal status, which might affect the prognosis, have not been included in the study and probably in this study no cases with any deterioration in periodontal status were reported. Recent studies by Tait et al have demonstrated that placement of a post can create stresses that lead to root fracture during post placement or function and that the strength of endodontically treated tooth was directly related to remaining internal tooth structure. 5 In the present study, no fracture of the root or abutment was seen and no crown debonding or decementation occurred in both the groups. In FP Group, the post was bonded in the canal in the same sitting as that of post preparation, hence it could have reduced chances of root fracture as compared to MP Group, wherein the post was cemented in the subsequent appointment. The adhesive post-placement preparation might reduce the negative side effects of post placement preparation by stabilizing the root in terms of inner splinting. In a study by Tait et al it was found that post adaptation to the canal walls also represents an important element in biomechanical performance of the restoration. In MP Group there was one failure with respect to post adaptation. The failure was statistically censored on the day of post insertion. But for academic interest the case was evaluated for a total of 9 months. It was observed that with respect to treated tooth, the patient developed a discharging sinus indicating a biological failure. Biological failure is defined as the presence of any pathology due to caries or periodontal disease or endodontic failure. Mechanical failure was debonding of any part of the tooth -post- core- crown complex or presence of fracture. 6 In an in vivo study it was observed that more biological failures occur in premolars than anterior owing to complex root anatomy. 6 In the present study true biological failure was observed in one case in MP Group, which showed a periapical lesion at end of the study. The FP Group did not show any case of periapical breakdown [figure 2]. In a retrospective study by Ferrari et al, it was observed that the main cause of failure in fibre post system was due to debonding. 7 This is usually the result of an adhesive failure at the interface between dentin and resin cement. In the present study in fibre post Group the failure consisted of only one post debonding, which was ascribed to a loss of integrity at the adhesive interface between dentin, adhesive, resin cement, and post. The debonding failure could be retreated as there was sufficient coronal tooth structure remaining. Over the years, the first-generation carbon fibre posts have been replaced by quartz-coated carbon fibres and glass fibres that are amenable to silane 44

9 CLINICAL AND RADIOLOGICAL EVALUATION OF CAST METAL AND QUARTZ FIBRE POSTS IN ENDODONTICALLY RESTORED TEETH coupling. The epoxy resin embedding matrix in older generations of fibre posts is also replaced with highly cross-linked, oxygen inhibition layer free methacrylate resin matrices that, theoretically, have the potential to bond to methacrylate-based resin cements. Different modalities of surface treatments of posts are also available to render these newer generations of fibre posts more conducive to bonding to methacrylate-based resins. Although the use of these newer generations of fibre posts has not yet attained the scientific rigor of an ideal monobloc, they are reported to have performed well in vivo. This is probably due to the similarity in the modulus of elasticity between fiber posts and root dentin. 8 To improve adhesion Zakereyya S et al contended that luting posts with Panavia 2 or Calibra after etching the dentin with phosphoric acid for 5 seconds produced significantly higher retention values than treating dentin for 3 seconds or with ED Primer, only. 9 The conventional non adhesive post cementation is less reliable to withstand simulated functional forces compared to adhesive approaches. 2 Light curing resins are not recommended for fibre posts cementation because of inadequate depth of cure in the apical portions of the root, even if translucent posts are used. Therefore, dualcured and self-cured resin cements have been advised for fibre post cementation. It was reported that in the absence of light some dual-cured cements may not reach an adequate degree of conversion. Therefore, light curing was recommended for dual-cured resin cements. 2 In a finite element analysis study on post systems by the authors, [figures 3], it was seen that rigid Cast metal post - core produced highest internal stresses as compared to fiber post 22. This is in conformation with results obtained in a classical study by Pegrotti. 23 In an in vivo study by Ibrahim et al 24 it was found the average survival rate of cast metal post was 7.7 years and failure rate was.2 %. The most common complication was loss of retention of post and core. 24 The restoration was deemed successful if the complete crown was still cemented to the underlying tooth-core complex at follow up. In the present study MP Group showed one crown fracture at the end of nine months follow up. In a clinical study it was observed that the survival rate of fibre post was 96 %. 7 In this study the probability of survival of fibre post Group is 95 % and failure percentage is 4.8 % as compared to 85 % and 5% respectively of cast metal post Group [Table]. There was no statistically significant difference [p value >.5] in the clinical performance of both the groups. In a recent systematic review analysis and evaluation by Charles J. Good acre suggested that fibre posts may be more successful than cast metal posts, but there were not enough random clinical trials to warrant a definitive recommendation. 25 However, in this study the fibre post showed a lesser failure rate than cast metal post. The probability of survival of fibre post was more than that of cast metal post and this did not depend on the tooth type, nor age or gender specific. Cast metal post and core fabricated using standardized technique is still considered as traditional time honoured method of restoring endodontically treated teeth. Fibre post and core technique offers the advantage of reducing chair side time, and 45

10 SHASHIKALA K, SONALI SHARMA obviates the need of arduous time-consuming, error prone laboratory procedures and expensive equipment. They possess inherent flexibility as of natural dentin, allowing the post to absorb stress and prevent root fracture. Other advantages of fibre post, like aesthetics, corrosion resistance, biocompatibility, modulus of elasticity being similar to that of dentin, could not be embraced in this study. In the light of the limitations of this study design, fibre post and core system show promising results and appears to be a better alternative to the rigid cast metal post in clinical practice. However, long-term clinical evaluation is required to authenticate this conclusion. References:. Pereira JR, Fabio de Ornelas, Rodrigues Conti PC. Effects of a crown ferrule on the fracture resistance of endodontically treated teeth restored with prefabricated posts. J Prosthet Dent 26; 95: Ertugrul ZH, Ismail YH. An in vitro comparison of cast metal dowel retention using various luting agents and tensile loading. J Prosthet Dent 25; 93: Yalcin E, Cehreli MC, Canay S. Fracture resistance of cast metal and ceramic dowel and core restorations: A pilot study. J Prosthet Dent 25; 4(2): Cohen S, Burns RC. Pathways of the pulp.8th ed. St Louis (MO): Mosby Inc; Ingle JI, Bakland LK. 5th ed. Hamilton: B C. Decker Inc; Bateman G, Ricketts DNJ, Saunders WP. Fibre-based post systems: a review. Br Dent Jour 23; 95: Rosensteil SF, Land MF, Fujimoto J. Contemporary fixed Prosthodontics. 3rd ed. St Louis: Mosby Inc; 2 8. Pitel ML, Hicks NL Evolving technology in endodontic posts.compendium23; 24(): Weine FS. Endodontic therapy. 6th ed. St Louis: Mosby Inc; 24. Tait CM, Ricketts DNJ, Higgins AJ. Weakened anterior roots- intra radicular rehabilitation. B Dental Journal 25; 98:69-7. Monticelli F, Grandini S, Goracci C, and Ferrari M. Clinical Behaviour of Translucent -Fibre Posts: A 2 -Year Prospective Study. Int J Prosthodont 23; 6: Fredriksson M, Astback J, Pamenius M, Arvidson K. Retrospective study of236 patients with teeth restored by carbon fibre reinforced epoxy resin posts. J Prosthet Dent 998; 8(2): Miguel A, Puig I, Cabornero AA. Fibre reinforced post and core adapted to a previous metal ceramic crown. J Prosthet Dent 2; 9: Naumann M, Rosentritt M, Preuss A, Dietrich T. The effect of alveolar bone loss on the load capability of restored endodontically treated teeth: A comparative in vitro study. J Dent 26; 3(33). 5. Lu ZY, Zhang YX. Effects of post-core design and ferrule on fracture resistance of endodontically treated maxillary central incisors. J Prosthet Dent 23; 89: Glazer B. Restoration of Endodontically Treated Teeth with Carbon Fibre Posts: A Prospective Study. J Can Dent Assoc 2; 66: Ferrari M, Vichi A, Mannocci F, Mason NP. Retrospective Study of the clinical performance of fiber post. Am J Dent 2; 3: Tay F R, Pashley D H. Monoblocks in Root Canals: A Hypothetical or a Tangible Goal. J Endod 27; 33: Zakereyya S. M. Albashaireh,,Muhamad Ghazal, Kern M.Effect of dentin conditioning on retention of airborne-particle-abraded, adhesively luted glass fibre-reinforced resin posts J Prosthet Dent 28;: Naumann M, Sterzenbach G, Rosentritt M, Beuer F, Frankenberger R. Is Adhesive Cementation of Endodontic Posts Necessary? J Endod 28; 34:6. 2. Radovic I, Corciolani G, Magnib E, Krstanovic G, Pavlovic V,. Vulicevic Z R, Ferrari M.Light transmission through fiber post: The effect on adhesion, elastic modulus and hardness of dual-cure resin cement. Dent materials 29; Sharma S, Shashikala K.Cast metal post versus fiber post- A 3 dimensional finite element analysis. RGUHS-Journal of Dental Sciences Jan 28; (2): Pegoretti A, Fambri L, Zappini G, Bianchetti M. Finite element analysis of a glass fiber reinforced composite endodontic post. Biomaterials 22; 23: Ibrahim H, El- Mowafy Omar, Brown J W. Radio opacity of non metallic root canal posts. Int Prosthodont 26; 9:-2 25.Charles J. Goodacre.Review analysis and evaluation - Carbon Fibre Posts may Have Fewer Failures than Metal Posts. J Evid Base Dent Pract 2; :