CASE REPORT


https://doi.org/10.5005/jp-journals-10019-1259
International Journal of Prosthodontics and Restorative Dentistry
Volume 10 | Issue 2 | Year 2020

Retrofitting of a Fixed Dental Prosthesis after Fracture of an Abutment during Final Cementation


Wan Yi Lim1, Pravinkumar G Patil2

1International Medical University, Kuala Lumpur, Malaysia
2Department of Prosthodontics, Division of Clinical Dentistry, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia

Corresponding Author: Pravinkumar G Patil, Department of Prosthodontics, Division of Clinical Dentistry, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia, Phone: +60 1135022042, e-mail: pravinandsmita@yahoo.co.in

How to cite this article Lim WY, Patil PG. Retrofitting of a Fixed Dental Prosthesis after Fracture of an Abutment during Final Cementation. Int J Prosthodont Restor Dent 2020;10(2):83–86.

Source of support: Nil

Conflict of interest: None

ABSTRACT

The success of the endodontically treated tooth is highly dependent on the quality of the coronal restoration. The placement of a post is recommended if the total amount of the residual tooth structure is not sufficient to support a core made of a plastic material. Even though uncommon, there might be possibility that patients came with a fractured core during the session of bridge cementation. Retrofitting the crown or bridge on a fractured core might be a better option, and various practitioners had performed this method successfully. This technique explains the production of vacuum-formed thermoplastic template adapted on a die stone master cast to make up the composite resin core of fractured tooth in the original shape.

Keywords: Fixed prosthodontics, Prosthodontic management, Retrofit dowel..

BACKGROUND

The success of the endodontically treated tooth is highly dependent on the quality of coronal restoration. The restoration might be composite, onlay, or crown depending on the tooth location and the remaining tooth structure available. The placement of a post is recommended if the total amount of the residual tooth structure is not sufficient to support a core made of a plastic material.1 Even though uncommon, there might be possibility that patients came with a fractured core during the session of bridge cementation. This might be due to several causes, including debonding of composite and trauma. An option of refabricate the core with a new impression and a new crown fabrication is available. However, this method is financially demanding and time-consuming. Retrofitting the crown or bridge on a fractured core might be a better option, and various practitioners had performed this method successfully.2 This technique explains the production of vacuum-formed thermoplastic template adapted on a die stone master cast to make up the composite resin core of fractured tooth in the original shape.

CASE DESCRIPTION

A 24-year-old healthy Chinese male patient presented with fractured temporary bridge and tooth one day prior to appointment of bridge issue (Fig. 1). The patient is worried and hope to save the tooth. Patient had no medical history, and there is no symptom for teeth 11 and 13 after root canal treatment. On examination, teeth 11 and 13 are not mobile, probing shows no pocket and no tender to percussion nor palpation. However, there is slight gingival hypertrophy at the proximal face of teeth 11 and 13. Tooth 11 was fractured with sound dentin height of around 3 mm from the margin of tooth preparation. Before giving treatment options, some investigations were carried out to exclude any root fracture, caries, and contravention of the biologic width due to trauma or damage to the supporting tissues.

Treatment Options and Rationale

The patient was given few options as indicated in Table 1. The patient chooses to have the fiber post placement on tooth maxillary right central incisor and core buildup using retrofitting technique due to his willingness to save the tooth, cost needed for new bridge fabrication, and duration of other treatment plans.

Intraoral Examination

The core and temporary bridge of both teeth 11 and 13 are inspected. Then, all the remaining cements left on the tooth structure were removed with ultrasonic scaler. The tooth was inspected to make sure there is enough ferrule effect for the placement of a post. In order to identify the adaptation of margins for both 11 and 13, the bridge was fitted onto the remaining core. After that, the fractured crown length was measured. After a periapical radiograph was taken, any periapical lesion or periodontal widening are identified. The length of gutta-percha (GP) from canal needed to be removed was then measured with computer. For this case, 13 mm of GP was removed from canal and 5 mm of GP was left at apical third for apical seal.

Fig. 1: Fractured abutment with tooth upper right central incisor just before final cementation

Table 1: Proposed treatment options and rationale
Treatment proposedRationale
1. Fiber post (RelyX Fiber Post; 3M) insertion on tooth 11 and core buildup using retrofitting technique
  • Due to lack of coronal tooth structure, core buildup is indicated. Post is needed to enable the retention of core material.
  • Fiber post is chosen due to its flexibility (modulus of elasticity similar to dentin) which will prevent unnecessary forces exerted onto root dentin, thus preventing vertical root fracture of tooth 11.
  • Core buildup using composite resin will be done using thermoplastic material as a template which is shown in section “Materials and method.”
2. Fiber post (RelyX Fiber Post; 3M) insertion on tooth 11 and core buildup, followed by new prosthesis
  • Free-hand composite core buildup will be done after placement of core and secondary impression will be taken again.
  • New bridge will be issued during another appointment.
3. Extraction of tooth 11 followed by implant or new prosthesis
  • Though more invasive, this may be one of the treatment options due to lack of ferrule effect and deep horizontal fracture.

Fig. 2: Final cast

Fig. 3: Vacuum-formed sheet used to fabricate a template to copy prepared tooth surface form on final cast and tried in mouth for fit accuracy

Fig. 4: Fiber post cemented

Fabrication and Fitting of the Thermoplastic Template

In the meanwhile, the master case was sent to lab to fabricate vacuum-formed thermoplastic template (Fig. 2). A 1.0 mm thermoforming sheet (Erkodent; Glidewell Laboratory) was adapted onto patient’s master cast. The manufacturer’s instruction is followed when using the dental vacuum former machine. After the thermoplastic foil was hardened, the master cast was detached from the sheet. The excess was trimmed away by using a pair of scissors and the margins are finished and polished with diamond bur. The thermoplastic template was then sent back to clinic for try-in purpose. Thermoplastic template of tooth 11 was fitted onto fractured abutment tooth 11 (Fig. 3). Gutta-percha was removed using Peeso reamer and universal drill. Canal space was prepared using post drill (blue) corresponding to fiber post (RelyX™ Fiber Post; 3M™) blue, tip size 0.9 mm, taper 10%. Post was fitted and periapical radiograph was taken. A periapical radiograph was taken to make sure the complete removal of GP on the coronal 2/3 of the root canal and proper fitting of post. Excess length of fiber post was removed, followed by try-in of thermoplastic template (Fig. 4).

Fig. 5: Vacuum-formed template used to shape composite core-build material up on the post

Fig. 6: Vacuum-formed template removed after polymerization

Fig. 7: Final core-build material automatically shaped as per previous form

Rebuild the Core with Thermoplastic Template

Fractured tooth 11 was cleaned with water and air-dried followed by the application of 15 seconds of 37% phosphoric acid etch (SDS Kerr™ Gel Etchant 3-Pack). Bonding agent (3M™ Single Bond Universal Adhesive) is applied to the tooth surface and cured for 10 seconds. Then, the inner surface of the thermoplastic template is filled with light-cured composite, and it is seated over tooth 11 using light finger pressure. After light curing for 5 seconds, the excess composite is removed gently with a sharp probe (Fig. 5). The composite is light cured for another 40 seconds followed by removal of the thermoplastic template (Fig. 6). The light curing process was performed from all possible sides to ensure a complete set of the material. Excess composite was removed and margins were finished gently with a fine grit diamond point (Fig. 7).

Fitting the Bridge

Bridge is fitted on newly build composite core 11 and tooth 13. Retention, resistance, stability, fitting, occlusion, and marginal adaptation are checked before cemented with resin cement (RelyX Capsule; 3M). Excess cements were removed with plastic instrument, sharp probe, and floss after tag curing of 2 seconds. The cement is cured for 40 seconds from all the surfaces. Patient is recalled after 3 weeks. Retention, resistance, stability, fitting, occlusion, and marginal adaptation were checked again. The examination shows the healing of free gingiva margin and the formation of scalloping borders of gingiva across tooth 13, pontic 12, and tooth 11 as compared previously (Fig. 8).

DISCUSSION

Bridge is one of the treatment options to replace missing tooth by using adjacent abutment teeth as support. Tooth fracture of an endodontically treated tooth might occur due to coronal loss of tooth structure from dental procedures or secondary caries, reduction of mechanical properties, and increase brittleness of dentin that caused by decrease in dentin moisture.3 In this case, a post and core followed by bridge will be needed in order to restore the function and esthetic of fractured tooth. A fiber post has been chosen because fiber post has similar modulus of elastic as dentin when compared with metal post. Fiber post has better force distribution and lower fracture rate when using fiber post compared with metal post.4 Many authors have proposed different approaches to retrofit a crown or bridge. Saafi J repaired a fractured abutment by using resin Duralay buildup and retrofitting the existing crown.5 With this method, additional time and cost will be needed for lab procedures. Deebbabi I used refabricate Duralay post and core to the retrofit the bridge.6 Antonio S used a technique for recreating the internal contours of a preexisting crown that does not depend on the existing of the die of the original preparation or any replica.7 The author used self-cured resin (Clearfil Core, Kuraray) as core; however, when self-cured resin has lower hardness value when compared with light-cured composite. Besides that, self-cured composite resin may co-operate more air bubbles and lack homogeneous when using hand mixing technique.8 Kennedy M has reproduced the core acrylic copings to fabricate a composite core foundation in the same location as the previous core.1 This technique is similar to the technique used in this article with an additional step of taking impression of inner surface of the bridge and pour a new cast rather than using the master cast for plastic template fabrication. This article describes a procedure of retrofitting a bridge on a fracture and root canal-treated abutment. This technique demonstrated the preparation of a vacuum-formed thermoplastic template adapted to the master cast. According to the manufacturer, the basic principles of thermoforming include using models that consist of hard plaster (class 3) and the hard plaster must be permeable to air.9 This is because hard plaster such as gypsum types 3 and 4 has enough strength to withstand casting or pressure. A fiber post is placed before rebuilding the core because the tooth structure left is less than one third of the crown, which is not enough to sustain a crown or bridge. A fiber post is chosen because preparation of fiber post is more conservative.10 It is possible to have chairside repair fractured core and retrofitting bridge by using vacuum-formed thermoplastic template adapted to master cast.

Figs 8A and B: (A) Frontal view of cemented bridge at the same appointment; (B) Occlusal view indicating accurate fitting of bridge

REFERENCES

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