|Year : 2017 | Volume
| Issue : 2 | Page : 91-95
Fabrication of cast post and core by a modified indirect procedure and postcementation using a novel technique
Adiba Shaikh, Lalitagauri Mandke, Leena Padhye
Department of Conservative Dentistry and Endodontics, D.Y. Patil University, School of Dentistry, Nerul, Navi Mumbai, Maharashtra, India
|Date of Web Publication||25-Jan-2018|
Dr. Adiba Shaikh
Department of Conservative Dentistry and Endodontics, DY Patil University School of Dentistry, Nerul, Navi Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
The restoration of endodontically treated pulpless teeth is a challenging dental procedure. Post and core is indicated in cases of extensive coronal tooth destruction where additional retention is required. The post is used to retain a core that can be used to retain definitive prosthesis. The choice between using a cast post and a prefabricated post depends on multiple factors such as canal configuration and remaining tooth structure. It has been said that if a canal requires extensive preparation, a well-adapted cast post and core will be more retentive than a prefabricated post that does not match the canal configuration. The cast post and core is fitted to the prepared root canal space and designed to resist torsional forces. However, one drawback of cast post is its tedious and time-consuming wax pattern technique. In this case report, we have used a time saving modified indirect technique for fabricating cast post and core, without the use of any reinforcement, no wax, no pattern resin but only rubber base impression material along with a novel technique of cementation, which utilizes a modified syringe with needle to facilitate even distribution of luting cement within the canal.
Keywords: Cast post, cementation, modified indirect technique
|How to cite this article:|
Shaikh A, Mandke L, Padhye L. Fabrication of cast post and core by a modified indirect procedure and postcementation using a novel technique. Indian J Oral Health Res 2017;3:91-5
|How to cite this URL:|
Shaikh A, Mandke L, Padhye L. Fabrication of cast post and core by a modified indirect procedure and postcementation using a novel technique. Indian J Oral Health Res [serial online] 2017 [cited 2019 Sep 23];3:91-5. Available from: http://www.ijohr.org/text.asp?2017/3/2/91/223933
| Introduction|| |
The longevity of endodontically treated teeth has been greatly enhanced by continuing advancements made in endodontic therapy and restorative procedures. It has been reported that a large number of endodontically treated teeth are restored to their original function with the use of intraradicular and post-endodontic restorations. These intraradicular restorations vary from a conventional custom-made cast post and core to the commercially available prefabricated post systems. A custom made cast post can either be cast from a direct pattern or an indirect pattern. In case of the direct technique, the pattern can either be made using inlay wax (GC Inlay wax medium) or it can be made using pattern resin. In case of conventional indirect technique, an elastomeric impression material along with some kind of reinforcement is used. The reinforcement could be a paper clip, orthodontic wire, plastic posts, toothpicks, etc.
The drawback of the conventional indirect technique is that if the selected reinforcement, i.e., the wire or plastic post is too tight, then the impression material strips away from it when the impression is removed. Furthermore, placing of the reinforcement into the canal is an additional time-consuming procedure. In addition, seating the reinforcement onto the orifices of the root canals may be difficult or impractical in cases with difficult clinical access or in cases where multiple teeth are involved.,
Taking these disadvantages into consideration, this case report describes a simple and effective method of taking an impression in indirect pattern procedure. This modified technique, which does not use any reinforcement, but uses only rubber base impression material to fabricate cast post and core was used by Al-Rashed and Al-Rashed in 2015. It results in an impression with perfect elasticity, which implies less deformation of the impression at the time of removal., An innovative alternative technique for post cementation, as described by Gaikwad and Badgujar, was also used in this case report.
| Case Report|| |
A 41-year-old male patient reported to the Department of Conservative Dentistry and Endodontics with a chief complaint of pain in the lower right back region. On examination, tooth # 45 was grossly carious with fractured lingual cusp. A clinical pulp exposure was seen [Figure 1]. Tooth was tender on vertical percussion. Vitality tests gave a negative response. Radiograph revealed caries involving enamel and dentin with concomitant pulpal involvement. Provisional diagnosis was deep occlusal caries with pulp necrosis along with apical periodontitis. Root canal treatment was proposed to the patient, followed by custom-made cast post which would later be followed by prosthetic rehabilitation.
Access opening was done in tooth # 45, using access opening bur (Dentsply endo access bur). Working length was determined using Root ZX MINI apex locator (J. Morita, Japan) and confirmed on radiovisiography using 20 no K file (Mani). A single canal was present in tooth # 45. Cleaning and shaping were done using rotary file system (Protaper universal, dentsply). Canal enlargement was done till F2. Saline (Infutec, NS.0.9%W/V) was used for irrigation, along with a lubricant (Prime Dental, RC Help) for canal preparation. Upon verification of master cone radiograph, root canal was obturated with gutta-percha (Dentsply, India) and AH Plus sealer (Dentsply, India) using cold lateral compaction technique [Figure 2]. A single visit root canal treatment was performed. The tooth was then temporized with CAVIT (3M ESPE).
|Figure 2: (a) Working length, (b) master cone, (c and d) post-obturation|
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Seven days after the obturation, gutta-percha removal and postspace preparation was done. Mechanical means of gutta-percha removal was used. Pesso reamer number 2 (Mani) was used for postspace preparation, leaving apical 5 mm of gutta-percha to maintain the apical seal  [Figure 3].
After post space preparation, the tooth was roughly prepared for a crown, using a chamfer bur (Mani.DIA-Burs.TR-24). A chamfer margin was placed at the gingival level.
Modified indirect custom cast post and core procedure:,,,,,
- The first step for this procedure was the selection of the lentulospiral also called as mechanical cement carrier. It was selected on the basis of the largest lentulospiral (Mani) that fit into the postspace and reached the desired length
- This was followed by selection of impression tray depending on the arch and the arch size
- The elastomeric impression material that was used in this case was silicone, light (Affinis, Zhermack) and putty consistency (Aquasil, soft putty regular set, Densply)
The light body that is available in syringe form was used. One end of the syringe was attached to the gun whereas the other end was attached to the mixing tip. The impression material was filled all around the prepared tooth. A part of the light body was placed on the glass slab also
- The selected lentulospiral was attached to the micromotor handpiece (NSK) and was then loaded with impression material. While loading the lentulospiral, the lentulospiral should not be kept rotating. However, while carrying the impression material in the postspace, the lentulospiral was kept initially at low rotational speed; the speed was then gradually increased as it reached the apical portion of the post space. The speed was again reduced while withdrawing the lentulospiral
This procedure of carrying the impression material into the post space was repeated until the entire canal got filled with impression material. While performing this procedure, care was taken that each time the lentulospiral was withdrawn from the canal, it was kept rotating to get a void-free impression
- After this, the heavy body impression material was mixed, i.e., base and catalyst and was loaded onto the impression tray. The impression was taken using putty wash one-step technique, i.e., the heavy body was placed on to the light body that was filled all around the prepared tooth. Since the heavy body picks up the light body, such impressions are also called pick up impressions
- The impression was removed and later evaluated [Figure 4].
After making the impression the access cavity was sealed by a temporary restoration (Cavit, 3M, ESPE).
The impression was then sent to the dental laboratory for its fabrication. The cast post and core was made in Nickel-Chromium-based dental alloy-Duracast V (Neocast V, USA) [Figure 5].
For cementation, a 2 ml syringe (Dispo Van) with a 24-gauge needle (BD Precision Glide Needle) was used. The syringe was cut at 0.8 ml mark [Figure 6]. The needle was bent and inserted into the prepared postspace ensuring the tip was in contact with the remaining gutta-percha while allowing easy access to the site of delivery. The root canal was dried, and isolation of the site was done using cotton rolls. The needle was attached to the syringe, and the plunger was removed from the modified syringe. Glass ionomer luting cement (GC Fuji I Glass Ionomer Luting Cement GC Corporation, Tokyo, Japan) was mixed as per the manufacturer's instructions and loaded into the syringe. After loading, the plunger was replaced back. The needle was inserted into the root canal just to re-ensure that the tip was contacting base of the prepared postspace.
To dispense the luting cement, the pressure was applied to the plunger at the same time the needle was moved coronally. The cast post and core was moved up and down with a pumping action in the canal, and excess luting cement was then wiped off. The cast post and core were again inserted into the prepared root canal and held with the help of finger pressure for a couple of minutes. Excess luting cement was removed using an explorer. This method ensured complete filling of the prepared postspace and uniform coating of the walls , [Figure 7].
After cementation of the post and core, the tooth preparation was completed [Figure 8]. The patient was referred for prosthetic rehabilitation with porcelain fused to metal crown followed by fabrication of the removable partial denture for the remaining missing teeth.
|Figure 8: (a) Lingual view after final tooth preparation, (b) labial view after final tooth preparation|
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| Discussion|| |
The custom-made cast post and core has a long history of success. They provide excellent service for root canal treated tooth with moderate-to-severe damage. A 6-year retrospective study of 96 root canal treated teeth with extensive loss of tooth structure and restored with custom cast post indicated a 90.6% of success rate. The advantages of custom posts include superior adaptation to the root canal, associated with little or no stress with installation, and high strength in comparison to the prefabricated post. They are also the restoration of choice in oval-shaped canals, or when the angulation of post needs to be different from that of the core. In cast post and core, the post and core are fabricated together to form one single unit, thus reducing the number of interfaces.
Cast post can also be done if a large core is being placed in a high-stress situation. In such cases, resin composite may not be the material of choice due to the fact that it tends to deform under a load., In such circumstances, the post and core can be cast in metal. In this case, custom cast post and core was chosen because #45 was to serve as abutment for removable partial denture and hence heavy forces were anticipated on it.
The success of the modified indirect technique of fabricating cast post and core depends on the accuracy of the impression replicating the internal surface of the prepared root canal. The advantage of indirect technique is that it conserves chair side time by delegating the pattern for the post and core to dental laboratory. In addition, in this indirect technique of using elastomeric impression material without reinforcement, it relies on the property of tear resistance of the material, which is around 3000 g/cm for condensation silicone. The highest tear resistance among the elastomeric impression materials is for polysulfide (4000 g/cm), but it is not advocated because of its numerous disadvantages such as unpleasant odor, staining due to lead oxide, its moderately high shrinkage and fairly high permanent deformation.
There are five main groups of cements used for post cementation, namely, zinc phosphate, glass ionomer cement (GIC), polycarboxylate, resin-modified glass ionomers, and composite resins. GIC is more frequently used among them. GIC adheres to dentin through chemical retention. The setting reaction of GIC has two main steps, the first occurring when the water present in their original chemical composition is consumed and the second is from the water present in the dentinal tubules. During the setting reaction, the initial contraction was observed, followed by an increase in volume which takes because of the hygroscopic expansion resulting in an improved interaction between the GIC and dentin, thereby increasing post retention.
The modified method of cementation using glass ionomer was used in this case to ensure complete filling of the post space with no voids and an even coating of the canal walls. The technique requires a quick handling, as the luting cement needs to be manipulated, loaded into the syringe, dispensed in the post space followed by the post and core placement. If the consistency of the luting cement is thick, it will prevent proper flow through the needle when the plunger is pressed and may lead to deficient material or failure to fill the post space. The cast post and core was inserted with a pumping action into the canal. This allows adequate venting of the luting cement coronally, preventing the hydraulic pressure build up.
| Conclusion|| |
For many years, the cast metal post and core has been the traditional method for fabricating the foundation restoration of a prosthetic crown. One advantage of the cast post and core system is that the core is an integral extension of the post. However, its biggest disadvantage is the time spent to make a pattern for cast post and core. Hence, this modified technique results in an impression with perfect accuracy and most importantly saves time. An alternative method for cementation has also been used to provide better clinical performance of the restoration.
Various procedures are available for the cementation of post and core. Depending on the operator's choice and evidence provided, the best method should be implicated to improve the clinical results not only for the fabrication of the cast post and core but also its cementation.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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