Rehabilitation of Fractured Maxillary Anterior Teeth Using Custom Cast Post and Core: A Case Series

Introduction

Endodontic treatment is the regular procedure for treating the teeth in which pulp tissue is irreversibly inflamed or necrotic due to carious process or dental trauma. The remaining tooth structure is the key factor for determining the long term prognosis of endodontically treated teeth.¹ As a result, such tooth may require a post for rehabilitation.² Rehabilitation of a root filled teeth is related to several factors such as location, remaining amount of dentin walls, post cementation length, post system, final restoration and presence of the ferrule.³ In anterior teeth with more than 50% tooth structure loss, post and core followed by full coverage restorations are mandatory.⁴

The foundation restoration for a mutilated tooth is a custom-made post and core. The primary objective of this procedure is providing retention for the core restoration, which replaces lost coronal structure. Post and core can be a one-piece custom-made post or prefabricated post with composite build-up.⁵

Cast metal posts have a high elastic modulus and have been used for several decades in restorative dentistry for restoring mutilated, endodontically treated teeth.⁶ The custom-made post and core is indicated in various circumstances such as, when there is a gross loss of tooth structure, deep bite, in teeth with large canals and when a change in angulation is anticipated for improving aesthetics.⁷

This article reports three cases of mutilated upper anterior teeth which were endodontically treated and rehabilitated using custom made cast post and core, followed by full coverage crowns.

Case Presentation

Case 1

A 35-year-old male patient came to the Department of Conservative Dentistry and Endodontics, with the main complaint of fractured prosthesis in the upper incisor region. Patient had a history of root canal treatment two years back in relation to 12 and 21. On intra oral examination, Porcelain fused to metal (PFM) fixed prosthesis in relation to 11, 12 and 21 were present (Figure 1A). Radiograph showed incomplete obturation and a lesion in periapical area in relation to 12 and 21 (Figure 1B). 11 was missing. On thorough clinical and radiographic examination, a diagnosis of insufficient root canal treatment with apical periodontitis was made. Treatment, which was minimally invasive, cost effective and aesthetically sound was planned. Information regarding the treatment plan, along with complications was given to patient. The treatment planned was retreatment in relation to 12 and 21, followed by custom cast post and rehabilitation with full ceramic prosthesis.

Under rubber dam isolation, retreatment was initiated. Access opening was re-entered with endo access bur #2 (Densply, Mallifer, Switzerland). The gutta-percha in the coronal third was removed with Gates Glidden (GG) drills #2 (Mani, Tochigi, Japan), while in the middle and apical third, gutta-percha was first softened with chloroform solvent, then removed with size #25 Hedstrom file (Mani, Tochigi, Japan). Working length was established. Biomechanical preparation was performed with hand instrumentation (passive step-back technique) (Mani, Tochigi, Japan) up to master apical size #70 and step back done up to three size larger file (#90) and the root canal spaces were irrigated with 15 mL of 3% sodium hypochlorite (Percan, Septodont, India) and 17% EDTA, alternatively. Teeth were then filled with triple antibiotic paste (combination of ciprofloxacin, metronidazole, and minocycline). The access opening was sealed with temporary filling material Cavit (3M-ESPE, MN, NY).

The patient was recalled two weeks later. Tooth was asymptomatic. Intracanal medicament was removed from the canals by irrigation with 10 mL of 3% sodium hypochlorite and H-file #60. Saline was used to flush out the NaOCl remnants. 2% chlorhexidine (Asep-RC, Anabond, India) was used for final irrigation. Obturation was done with gutta-percha #60 (Maillefer Densply,Switzerland) and AH plus sealer (Dentsply, Konstanz, German) using lateral compaction technique (Figure 1C).

Crown lengthening procedure was done around both the teeth. On the next appointment, using peeso reamer up to #4 (1.3mm) (Mani, Tochigi, Japan) leaving 5 mm of gutta-percha at apical end of root canal to maintain a good seal, post space preparation was done. Tooth preparation was made with shoulder finish line on the labial and palatal sides in relation to 12, 13, 21, 22, 23. Wax pattern was fabricated using inlay wax (GC Corp, Tokyo, Japan). A temporary crown was cemented before dismissing the patient. The casting laboratory converted the direct wax pattern into metal post.

Custom made cast post and core was cemented using glass ionomer cement (GC Gold Label 1, GC Corp, Japan) (Figure 1D) (Figure 1E). Elastomeric impression with heavy body (putty material) and light body (Flexceed, GC Corp, Japan) was made. The shade selection for full ceramic crown was done. Fixed partial denture was made for tooth number 11, 12, 13 and 21, 22, 23 and cemented using resin cement (Veriolink II, Ivoclar North America, NY) (Figure 1F).

Case 2

A 32-year-old patient visited the Department of Conservative Dentistry and Endodontics, with the complaint of fractured upper front teeth. A history of self-fall one year back was informed. Intra oral examination revealed Ellis and Davey’s Class III fracture on tooth 11 and 21 (Figure 2A). Vitality test done with electric pulp tester and cold test did not show any response suggestive of pulpal necrosis (Figure 2B). After endodontic treatment by custom cast post, core and full coverage crown was planned.

Under the rubber dam isolation, access cavity was prepared with endo access bur #2 (Densply, Mallifer, Switzerland). Working length was determined using an apex locator (Canal pro, Coltene, USA) and reconfirmed with radiographs. Biomechanical preparation of the canals were performed with hand instrumentation (Mani, Tochigi Ken, Japan) up to file size #50 and step back was done up to #70. Irrigation was carried out with 15 mL of 3% sodium hypochlorite (Percan, Septodont, India) and 17% EDTA, intermittently. Calcium hydroxide paste (Metapex, Metabiomed, S Korea) was used as an inter-appointment medicament and the access cavity was temporized with Zinc Oxide Eugenol (ZnOE) cement.

Patient was asked to visit after 10 days. Intracanal medicament was removed. Final irrigation was carried out with 2% chlorhexidine (Asep-RC, Anabond, India). Obturation was completed with gutta-percha (Densply, Maillefer Switzerland) and AH plus sealer (Dentsply, Konstanz, German) using the lateral compaction technique (Figure 2C).

Leaving 5 mm of gutta-percha at apical end of root canal to maintain a good seal, post space preparation was done with peeso reamer #3 (1.1 mm). Post space was evaluated using a digitalized intraoral radiograph. Following this, ferrule preparation was done. Tooth was prepared with shoulder finish line on the labial side and chamfer on the palatal side in 12 and 21. Direct wax pattern using inlay wax was made, which was then casted.

In the next visit, custom made cast post and core was cemented (GC Gold Label 1, GC Corp, Japan) (Figure 2D) (Figure 2E). Elastomeric impression was made with heavy body and light body. In natural daylight, the shade selection for PFM crown was done. PFM crowns were made for 12 and 21 and cemented with type 1 glass ionomer cement (GC Gold Label 1, GC Corp, Japan) (Figure 2F).

Case 3

A 30-year-old male patient came to the department, with a complaint of fractured upper front tooth. Patient gave of history of accident six months back. On intra oral examination, fractured crown was noted in relation to 12 (Figure 3A). Vitality test done with electric pulp tester and cold test did not show any response. On thorough clinical and radiographic examination, a diagnosis of asymptomatic apical periodontitis in relation to 12 was made (Figure 3B). Endodontic treatment followed by custom cast post and core and full coverage restoration was planned.

Topical anesthetic was applied and was followed by nerve block for achieving adequate anesthesia (2% lignocaine 1 mL). Access cavity was prepared with endo access bur #2 (Densply, Mallifer, Switzerland). Working length was determined using an apex locator (Canal pro, Coltene, USA) and reconfirmed with radiographs. Biomechanical preparation of the canal was performed with hand files (passive step-back technique) (Mani, Tochigi, Japan) up to size 45 and step back up to #60. Irrigation was done with 15 mL of 3% sodium hypochlorite (Percan , Septodont, India) and 17% EDTA, intermittently. The tooth was filled with triple antibiotic paste (combination of ciprofloxacin, metronidazole, and minocycline) and temporized (Cavit, 3M-ESPE, MN, USA).

The patient was recalled after two weeks. On the next visit, intracanal medicament was removed. Final irrigation was done with 2% chlorhexidine (Asep-RC, Anabond, India). Obturation was done with gutta-percha (Densply, Maillefer, Switzerland) and AH plus sealer (Dentsply, Konstanz, German) using lateral compaction (Figure 3C).

Post space preparation was done with peeso reamer size #3 in the next appointment. Wax pattern was fabricated using inlay wax (GC Corp., Tokyo, Japan). The wax pattern was then casted into metal post and core. The remaining tooth structure was prepared with shoulder finish line on labial and palatal sides in 12 and a temporary crown was cemented before dismissing the patient. In the next visit, cast post and core was cemented (Figure 3D, 3E). Elastomeric impression was made. The shade selection was done in natural daylight. Zirconia crown was made for 12 and cemented with resin cement (Veriolink II, Ivoclar North America, NY) (Figure 3F).

Discussion

The prognosis after endodontic treatment greatly depends on the post-treatment restoration than the treatment itself. Together with good endodontic treatment and good restoration, success rates are seen to be as much as 91.4%.⁸

Endodontically treated anterior teeth have thin coronal structure due to access cavity and crown preparations. The post aids in the retention of core in a tooth with reduced coronal tooth structure.^9,10 This post and dowel helps to retain definitive restoration. When the anterior tooth loss is minimal, it can be conservatively restored with bonded restorative materials. In such cases, the post is of not much benefit as the tooth structure is sound.^11-13

Posts can be generally classified as custom cast post or prefabricated post and dowel to retain the definitive restoration. Custom cast post reproduces the internal morphology of the canal preparation by using wax or auto polymerizing resin, which is then casted in either precious or non-precious metal alloy.⁷ In this case series, we presented three case reports of restoration of maxillary anteriors with custom cast post and core and full coverage crowns.

Cast posts are indicated when there is minimal residual coronal structure of the tooth. They have been the standard for tooth reinforcement for decades. They reproduce the morphology of prepared canal and thus are advantageous in oval or elliptical canal configurations. When there is a requirement of change of angulation for the final restoration to match the adjacent tooth, as in cases of mild proclination, custom cast post and core can be given.⁶ According to Gomez Polo et al.,¹⁴ cast metal posts have shown higher survival rates over 10 years. Another advantage of cast posts is that they can easily be retrieved if the tooth requires endodontic re-treatment.

Due to the need for additional appointments, temporization and laboratory fee, and with the advent of aesthetic glass fiber posts, the use of custom made cast post and core has reduced over the years.

A 2 mm ferrule can increase the resistance of the endodontically treated anterior teeth to fracture.¹⁵ Sorensen and Engelman¹⁶ suggested that this “ferrule effect” be defined as a 360-degree metal crown collar surrounding parallel walls of dentine and extending coronal to the shoulder of the preparation. Libman and Nicholls¹⁷ defined it as a metal band or ring used to fit the root or crown of a tooth. The crown restoration braces the tooth around this ferrule to enhance the integrity and longevity, providing resistance and retention form on the root canal treated tooth. It helps to transfer the occlusal forces vertically to the periodontium as the artificial crown and root act as one unit.

A retrospective analysis by Readal M et al.,¹⁸ stated that custom cast post and core treated teeth demonstrate an acceptable survival time. Long-term survival rates of 83% after 10 years,¹⁴ 90% after 9 years,¹⁹ and 89% after 7 years,²⁰ have been reported. These studies show that certain factors influence the survival rates of cast post and core. These factors include the metal alloy used, the type of restoration done, and the kind of prosthetic restoration.²¹

Fiber post placement requires less time and the evidence from the laboratory and clinical experience of technicians and dental professionals, respectively emphasizes on the use of glass fiber posts.

Conclusion

A large diversity of post systems is available today and a thorough knowledge about the advantages, disadvantages, indications and contraindications of each post system must be acquired to make a wise choice. The selection of a post system mainly depends on the remaining sound tooth structure. When the tooth structure is less than 50%, a custom cast post is recommended. While considering the restoration of an anterior tooth, esthetics is of prime concern rather than function.

Source of funding

None

Conflict of interest

None