Dr Sapna Rani et al / IJRID Volume 6 Issue 3 May-Jun 2016 Available online at www.ordoneardentistrylibrary.org

ISSN 2249-488X

Case - report

INTERNATIONAL JOURNAL OF RESEARCH IN DENTISTRY INNOVATIVE APPROACH OF REHABILITATION OF FRACTURED ANTERIOR TOOTH WITH COPY MILLED ZIRCONIA POST AND CORE Dr Sapna Rani*1, Dr Jyoti Devi2, Dr Sakshi Gupta1 1. Dept of Prosthodontics , Sudha Rustagi College of Dental Sciences and Research, Faridabad, Haryana 2. Dept of Prosthodontics, MAIDS, New Delhi Received: 22 Apr 2016; Revised: 27 May. 2016; Accepted: 15 Jun. 2016; Print date: 5 Jul. 2016

ABSTRACT

The extraction of fractured tooth with very less tooth structure remaining has now become an obsolete treatment modality. With advances in the field of dentistry, teeth formerly considered for extraction are now being saved. It has been made possible with approach of post and core combined with the advantages of the adhesive technique. The patient’s desire to achieve an esthetic result, and to have no metal used in the restoration of the tooth, are some of the challenges of restoring damaged teeth in the esthetic zone. This case report describes the step-by step procedure of rehabilitation of endodontically treated and fractured anterior tooth with copy milled one-piece zirconia post -core supported by all-ceramic crown. Endodontically treated fractured anterior tooth was restored with zirconia post - core which was fabricated by using CERCON all ceramic system. Keywords: Copy milling, Esthetic zone, Zirconia post and core

Introduction: Endodontically treated teeth often need a post and core as foundation for the final restoration [1]. The restoration of anterior nonvital teeth with metal posts and cores and all-ceramic restorations may lead to compromised esthetics because of the semitranslucence of ceramics and the opacious metal substructure of the underlying post and core [2]. Therefore increased esthetic demands as well as possible problems resulting from corrosion of posts made from non noble alloys led to the development of tooth-colored post systems. Post systems based on fiber-reinforced composite resin (FRC) have been introduced as a possible alternative and increasingly popular [3].

[3]

became

. But these post systems showed reduced fracture resistance as compared to metal posts

Due to favorable optical and mechanical properties, endodontic posts made of partially stabilized zirconia

ceramic have been described to be a promising alternative to those made of metal [4]. Prefabricated zirconia ceramic posts can be combined with different types of core materials, but in addition to compromised fracture strength, bond strength and durability between zirconia ceramic posts and overlying core material might be of concern [5]. The use of copy-milling systems for high-strength ceramics allows for the fabrication of core to be combined with prefabricated post but, in addition, completely milled posts and cores have been described in the literature [6]. This case report describes the fabrication of

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Dr Sapna Rani et al / IJRID Volume 6 Issue 3 May-Jun 2016 copy milled one-piece zirconia post- core in the esthetic zone using CERCON system that utilizes CAD/CAM (Computer-aided designed and machined) technology. Case Report A patient reported in the department of prosthodontics for rehabilitation of left central and lateral incisor. On intraoral examination, patient was found to have increased overjet and overbite and group occlusion. Central and lateral incisor on the left side was fractured due to trauma after endodontic treatment. Lateral incisor was horizontally fractured so that crown was not possible until retention from root canal was obtained. Treatment options available for the patient were metal post and core supported by porcelain fused to metal crown, all ceramic post with core build up and all ceramic crown and completely milled all ceramic post -core as one unit supported by all ceramic crown. After consent from the patient, rehabilitation of central incisor was planned with all ceramic crown and lateral incisor using copy milled zirconia post and core using CERCON CAD/CAM system supported by zirconia based all ceramic restorations. Procedure 1. Post space was prepared in the conventional manner

[7]

, assuring that the pulpal axial line angle was

rounded and not sharp. 2. Small diameter autopolymerizing acrylic resin (DPI RR cold cure, Dental Products India) dowel was fabricated to make impression of post space. Vaseline was applied in the post space with paper points so that dowel could be relined with pattern resin (GC corpor., Tokyo, Japan) and core build up was done with same pattern resin. Pattern was assessed so that there were no sharp angles internally or externally. 3. The pattern was attached with sprue wax (Cercon wax) to the respective holder [Figure 1] and sprayed with scan spray (Cercon, Dentsply, Germany) for scanning for copy milling [Figure 2]. 4. After milling, Zirconia post and core was separated from blank with straight fissure bur and sintered in cercon furnace at 1350˚C for 6 hours (Cercon heat, Dentsply, Germany). 5. Fit of post and core was checked with occlusal spray (Okklean, DFS) and seated completely in the canal space. 6. Post-core was cemented with adhesive cement (RelyX Unicem; 3M ESPE, St. Paul, Minn) after sandblasting with 40µm alumina then dry with alcohol, margins of the preparation were refined for both central and lateral incisor as necessary for

all-ceramic restorations (Cercon, Dentsply, Germany)

[Figure 3A]. 7. A two step putty wash polyvinylsiloxane impression of the prepared teeth was made and poured in type IV gypsum. The die was scanned in cercon eye and zirconia copings were milled from Y-TZP machinable zirconia block and sintered for 6 hours. 8. The milled units were then veneered on the labial, incisal and palatal surfaces with ceramic to give a life like appearance. 53

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Dr Sapna Rani et al / IJRID Volume 6 Issue 3 May-Jun 2016 9. Zirconia all-ceramic full coverage restorations (Cercon, Dentsply) were cemented with adhesive cement (RelyX Unicem; 3M ESPE, St. Paul, Minn) [Figure 3B]. Extra cement was removed with scalpel and all exposed margins were finished. Final restorations were evaluated clinically and radiographically and appeared to give good esthetic and functional value. 10. IOPA (Intraoral periapical radiograph) was taken after 12 months for follow-up which revealed properly adapted post -core [Figure 4]. Discussion The choice of an appropriate restoration for fractured anterior tooth

is guided by strength and esthetics.

Multiple factors must be considered when selecting a post and core e.g remaining tooth structure and tooth morphology, functional demands, arch position, periodontal status, and esthetics [8]. The cast gold post and core has been considered the gold standard because of its excellent success rate, favorable long-term prognosis, and ease of fabrication. With several translucent ceramic crown systems, there is concern regarding how the shade of the abutment affects the definitive shade of the restoration [8,9], so the developments were made for metal free post and core. [8]

Use of zirconia as a post and core material began in 1993 when introduced by Meyenberg et al

but

unification of post-core was done later on by different CAD/CAM softwares. Beck N et al [7] conducted a study to compare the fracture resistance of prefabricated posts made from zirconia ceramic and fiber-reinforced composite resin with the fracture resistance of copy-milled zirconia posts. They concluded that though less fracture resistant than prefabricated zirconia ceramic posts, copy-milled zirconia ceramic posts and cores may, from a mechanical point of view, be a viable alternative to prefabricated posts made from fiber-reinforced composite resin. Nurit Bittner et al

[9]

compared the shear strength of zirconia one-piece post and core with

other post-and-core systems and concluded that one-piece milled zirconia post and core showed sufficient mean load to failure values for anterior restorations. Zirconia ceramics has excellent fracture toughness, high flexural strength and modulus of elasticity

[10]

. High

elastic modulus makes them less likely to fail adhesively during mastication and permits a more conservative root canal preparation, decreasing the chances of root fracture

[11, 12]

. Cast metal post and core and all ceramic

crown requires ideal overjet and overbite in order to reduce the chances of fracture of restoration under functional stresses [13]. Copy milling of post and core was chosen for the patient as the treatment because of the high esthetic demand, less incisal clearance and aforementioned advantages of zirconia. In copy milling, post and core is combined together so that chances of failure are decreased

[14]

. Further to decrease the chances of

fracture of restoration clearance was given in centric relation. More commonly CEREC system was used in the literature for this purpose but CERCON system was used in presented case report to assess the feasibility and limitations of this technique by this system. CAD/CAM technology reduces treatment time but it also requires technical skills. Problems encountered in the fabrication 54

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Dr Sapna Rani et al / IJRID Volume 6 Issue 3 May-Jun 2016 of post and core was attachment of sprue to the wax pattern and nonpassive fit of the one-piece milled zirconia post and cores. Non passive fit was due to zirconia particles attached to dowel part as scan spray powder particles are also scanned along with the post and core wax pattern and milled from block which requires trimming of post and core to fit in canal space. Summary An impetus for the rapid development of ceramic technology is the contribution to metal-free prostbodontic restorations, which provide increased esthetics and improved material strength. Thus one-piece milled zirconia post- core is a viable option when a custom post and core is necessary to restore an anterior tooth. References 1. Albers HF. Core build-ups and posts, ADEPT Report1993;4:25-35. 2. Pissis P. Fabrication of a metal-free ceramic restoration utilizing the monobloc teehnique . Pract Periodont Aesthet Dent 1995;7(5):83-94, 3. Bitter K, Kielbassa AM. Post-endodontic restorations with adhesively luted fiber reinforced composite post systems: a review. Am J Dent 2007;20:353-60. 4. Edelhoff D, Sorensen JA. Retention of selected core materials to zirconia posts. Oper Dent 2002;27:45561. 5. Akgungor G, Sen D, Aydin M. Influence of different surface treatments on the short term bond strength and durability between a zirconia post and a composite resin core material. J Prosthet Dent 2008;99:38899. 6. Friedel W, Kern M. Fracture strength of teeth restored with all-ceramic posts and cores. Quintessence Int 2006;37:289-95. 7. Rosenstiel SF, Fujimoto J, Land MF. Contemporary fixed prosthodontics. 4th ed. St. Louis: Elsevier; 2006. p. 336-74. 8. Meyenberg KH, Luthy H, Scharer P. Zirconia posts: a new all-ceramic concept for nonvital abutment teeth. J Esthet Dent 1995;7:73-80. 9. Dilmener FT, Sipahi C, Dalkiz M. Resistance of three new esthetic post-and-core systems to compressive loading. J Prosthet Dent 2006;95:130-6. 10. Kosmac T, Oblac C, Jevnikar P, Funduk N, Marion L. The effect of surface grinding and sandblasting on flexural strength and reliability of Y-TZP zirconia ceramic. Dent Mater 1999;15:426-33. 11. Freedman G, Glassman G, Serota K. Endo-aesthetics. Part I. Intra-radicular rehabilitation. Ont Dent 1992;69:28-31. 12. Trushkowsky RD. Coronoradicular rehabilitation with a carbon-fiber post. Compend Contin Educ Dent Suppl 1996;20:S74-9.

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Dr Sapna Rani et al / IJRID Volume 6 Issue 3 May-Jun 2016 13. Fernandes AS, Dessai GS. Factors affecting the fracture resistance of post-core reconstructed teeth: A review. Int J Prosthodont 2001;14:355-63. 14. Carossa S, Lombardo S, Pera P, Corsalini M, Rastello ML, Preti PG. Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation. Int J Prosthodont 2001;14:9-14.

Figure Legends Figure 1- Post and core pattern attached to holder for scanning

Figure 2- Framework attached to milling machine for scanning

Figure 3A- Cemented zirconia post and core to lateral incisor

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Dr Sapna Rani et al / IJRID Volume 6 Issue 3 May-Jun 2016 Figure 3B- Post operative intraoral photograph after cementation of all-ceramic full coverage restorations

Figure 4- IOPA revealing properly adapted zirconia post and core

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