|Year : 2016 | Volume
| Issue : 1 | Page : 50-53
Modified technique to retrofit the crown on fractured core
Pravinkumar G Patil1, Kangjie Tay2
1 Division of Clinical Dentistry, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia
2 Klinic Pergigian Kamunting Taiping, Ministry of Health (MOH), Malaysia
|Date of Web Publication||10-Aug-2016|
Pravinkumar G Patil
Division of Clinical Dentistry, School of Dentistry, International Medical University, Kuala Lumpur
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Post and core followed by crown is a common treatment option to restore the form, function, and esthetics of an endodontically treated tooth. Although uncommon, it is possible that patients may present with fractured core during the crown cementation appointment due to various reasons, including trauma and composite debonding. Depending on the extent and severity of the fracture, retrofitting the crown on a fractured core can be a preferred option. This technique describes the fabrication of vacuum-formed thermoplastic template adapted on an elastomeric putty index obtained from the inner aspect of the crown to build back the composite resin core in original shape. This technique is simple to perform, and the additional time and cost of preparing new crown can be avoided.
Clinical Relevance to Interdisciplinary Dentistry
This technique demonstrated the preparation of a vacuum-formed thermoplastic template adapted to the polyvinyl siloxane putty index obtained from the inner aspect of the crown. The technique facilitated chairside repair of the fractured core, thus the additional time and cost of preparing a new crown can be avoided. The effect of the temperature onto the flexible putty during the adaptation of the thermoforming sheet needs to be carefully evaluated.
Keywords: Fixed dental prosthesis, indirect restorations, post and core, retrofitting
|How to cite this article:|
Patil PG, Tay K. Modified technique to retrofit the crown on fractured core. J Interdiscip Dentistry 2016;6:50-3
| Introduction|| |
A post and core followed by a crown is a common treatment option to restore the form, function, and esthetics of an endodontically treated tooth.  Although uncommon, it is possible that patients may present with a fractured core during the crown cementation appointment due to various reasons, including trauma and composite debonding. Rebuilding the core followed by making an impression for a new crown fabrication may be an option, but it is time-consuming and financially demanding. Depending on the extent and severity of the fracture, retrofitting the crown on a fractured core may be a preferred option. Various authors have suggested different approaches to retrofit the crown. ,,, Jahangiri and Feng  used the original die or its replica and a vinyl polysiloxane matrix preparing the autopolymerizing resin pattern to repeat casting of the postcore. Chan adapted a polytetrafluoroethylene sheet as a separating medium onto the inner aspect of the crown.  With this technique, partially set core material may get distorted and it also leaves additional cement space between the crown and the core. Sabbak  used a clear polyvinyl siloxane (PVS) impression material as a matrix. The intensity of light to cure the underlying composite resin may get reduced through bulky PVS. Berksun  used manually fabricated plastic foil as a template for rebuilding the core, but there is a chance of distortion of the foil adapted manually. This technique is a modification of the technique described by Berksun.  This technique describes the fabrication of vacuum-formed thermoplastic template adapted on an elastomeric putty index obtained from the inner aspect of the crown to build back the composite resin core in original shape.
| Procedure|| |
- When a patient presents with the dislodged temporary crown and fractured composite resin core, examine both the core as well as the temporary restoration carefully [Figure 1]
- Remove all the remnants of the temporary luting cement left on the fractured composite core by using an ultrasonic scaler
- Ensure that the shoulder and chamfer margins of the prepared tooth remain intact, and try to place the crown onto the remaining core to verify the marginal adaptation
- Clean and dry the fitted surface of the crown and apply a thin layer of petroleum jelly (Vaseline; Chesebrough-Ponds, Greenwich, London, England) onto it
- Mix an adequate amount of putty PVS impression material (Prestige Putty; Vannini, Bagno a Ripoli, Italy) and adapt it into the fitted surface of crown to obtain a silicone replica of the previously built-up core [Figure 2]
|Figure 2: Recording inner surface of metal ceramic crown with putty elastomer|
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- Cut the excess putty by leaving 4-5 mm distance from all the margins to make a horizontal base to allow seating of the putty replica onto the vacuum former machine [Figure 3]
- Adapt a 1.0 mm thermoforming sheet (Erkodent; Glidewell Laboratory, Newport Beach, Canada) onto the coronal portion of the putty [Figure 4]. Follow the manufacturer's instructions when using the dental vacuum former machine. Avoid using more than 1.0 mm thick thermoforming sheet to avoid undue compression on the putty index
- Detach the silicone replica from the thermoplastic foil after hardening of the sheet. Trim away the excess using a pair of scissors. Finish and polish the margins and try in the template onto the fractured core to examine its adaptation and stability
- Clean the fractured core again with water and air dry followed by the application of acid etch. After 15 s, rinse and air dry. Apply bonding agent to the tooth surface and cure for 10 s
- Fill the inner surface of the thermoplastic template with light-cured composite and seat it over the fractured core using light finger pressure [Figure 5]. Make sure it is adapted well
|Figure 5: Thermoplastic index used to carry light polymerized composite resin|
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- After light curing for 5 s, remove the excess composite gently with a probe. Light cure for another 40 s followed by removal of the thermoplastic template. Note that the light curing should be done from all possible sides to ensure a complete set of the material
- Remove the excess and finish the margins gently with a fine grit diamond point [Figure 6]. Try to fit the crown onto the newly build composite core and check for adaptation and marginal fitting
- Cement the crown using luting cement (RelyX Capsule, 3M, St. Paul, MN, USA) [Figure 7].
| Discussion|| |
This technique demonstrated the preparation of a vacuum-formed thermoplastic template adapted to the PVS putty index obtained from the inner aspect of the crown. The technique facilitated chairside repair of the fractured core, thus the additional time and cost of preparing a new crown can be avoided. The effect of temperature onto the flexible putty during the adaptation of the thermoforming sheet needs to be carefully evaluated. Corso et al.  and Kambhampati et al.  studied the effect of temperature changes (ranged from 4°C to 40°C  and 25°C, 37°C, and 42°C,  respectively) on the dimensional stability of PVS impression materials and found that though the changes in storage temperature had a statistically significant effect on the dimensional stability, the overall dimensional changes were extremely small. , There was no clinically significant change observed in the shape and the texture of the putty index. Alternately, 0.5 mm or 1 mm thick and flexible thermoforming sheet material can be used to avoid undue compression onto the putty index. Accuracy of the thermoforming template onto the prepared tooth in the mouth can be carefully evaluated before filling it with the repair composite resin. Ozawa et al.  studied the possibility of crown restoration retrofitting to the existing clasps using CAD/CAM and concluded that when a crown restoration must be remade to retrofit an existing clasp, CAD/CAM fabrication can be recommended so that both appropriate fitness and retentive force can be obtained.  Chairside repair of the fractured core and retrofitting of the already prepared crown appear to be possible with the help of a vacuum-formed thermoplastic template adapted onto the PVS putty index obtained from the inner aspect of the crown.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Jahangiri L, Feng J. A simple technique for retrofitting a post and core to a crown. J Prosthet Dent 2002;88:234-5.
Chan DC. Technique for repair of multiple abutment teeth under preexisting crowns. J Prosthet Dent 2003;89:91-2.
Sabbak SA. Simplified technique for refabrication of cast posts and cores. J Prosthet Dent 2000;83:686-7.
Berksun S. Rebuilding core foundations for existing crowns using a custom-made template. J Prosthet Dent 2005;93:201-3.
Corso M, Abanomy A, Di Canzio J, Zurakowski D, Morgano SM. The effect of temperature changes on the dimensional stability of polyvinyl siloxane and polyether impression materials. J Prosthet Dent 1998;79:626-31.
Kambhampati S, Subhash V, Vijay C, Das A. Effect of temperature changes on the dimensional stability of elastomeric impression materials. J Int Oral Health 2014;6:12-9.
Ozawa D, Suzuki Y, Kawamura N, Ohkubo C. Fabrication of crown restoration retrofitting to existing clasps using CAD/CAM: Fitness accuracy and retentive force. J Prosthodont Res 2015;59:136-43.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]