Management of a traumatized and luxated maxillary incisor with customized computed-aided design and computer-aided manufacturing zirconia post–core and crown

Vijetha Vishwanath; Hanumanth Murali Rao

doi:10.4103/jioh.jioh_35_19

CASE REPORT

Year : 2019 | Volume : 11 | Issue : 5 | Page : 318-322

Management of a traumatized and luxated maxillary incisor with customized computed-aided design and computer-aided manufacturing zirconia post–core and crown

Vijetha Vishwanath, Hanumanth Murali Rao
Department of Conservative Dentistry and Endodontics, D A Pandu Memorial RV Dental College and Hospital, Bengaluru, Karnataka, India

Date of Web Publication

24-Sep-2019

Correspondence Address:
Dr. Hanumanth Murali Rao
Department of Conservative Dentistry and Endodontics, D A Pandu Memorial RV Dental College and Hospital, Bengaluru, Karnataka.
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jioh.jioh_35_19

Abstract

The incidence of maxillary anteriors being injured during any assault to the facial region is nearly 37% owing to its position in the arch. Treatment planning always depends on the clinical scenario. Coronal fracture of teeth involving the pulp may need conventional endodontic treatment and aesthetic reconstruction. When there is not enough tooth structure to retain a crown, it may often need post–core to retain final post endodontic restoration. Various types and advancements of post-and-core systems have been documented in the literature over the years, with an excellent long-term prognosis. Although the traditional custom cast post-and-core system has been considered to be cumbersome and time-consuming, it has an added advantage of allowing modification in the angle of insertion and the position of the core to obtain optimal aesthetics. This case report presents the successful management with aesthetic rehabilitation of a fractured maxillary central incisor with customized computer-aided design–computer-aided manufacturing zirconia post–core and crown

Keywords: Computer-aided design–computer-aided manufacturing post and core, luxation, trauma, zirconia

How to cite this article:
Vishwanath V, Rao HM. Management of a traumatized and luxated maxillary incisor with customized computed-aided design and computer-aided manufacturing zirconia post–core and crown. J Int Oral Health 2019;11:318-22

How to cite this URL:
Vishwanath V, Rao HM. Management of a traumatized and luxated maxillary incisor with customized computed-aided design and computer-aided manufacturing zirconia post–core and crown. J Int Oral Health [serial online] 2019 [cited 2023 Jun 7];11:318-22. Available from: https://www.jioh.org/text.asp?2019/11/5/318/267712

Introduction

Traumatic injuries to the teeth and the supporting structures constitute a true dental emergency. Although dental trauma may not be seen as serious in comparison to other bodily injury, anterior tooth trauma leads to discomfort. The accompanying psychological, aesthetic, functional, and phonetic problems affect patient’s morale. Rational therapy based on accurate diagnosis must be instituted as teeth have the lowest potential of returning to the normal healthy state after an injury.^[1] The successful treatment of teeth with substantial damage not only depends on good endodontic treatment but also on aesthetic and functional rehabilitation in the form of post-endodontic restoration of the tooth. The post-endodontic restoration using post-and-core systems provides the dental practitioner a large array of materials, techniques, and designs.^[2] Custom cast post–core has been the gold standard, especially in situations of inadequate tooth material, which will not provide satisfactory retention, is also considered as the best choice for teeth with varied canal morphologies to provide optimum adaptability to the canal walls and resist rotation.^[3] With the advent of accurate digital imaging and precise fabrication technology, the growing demands of aesthetics among patients can be met with negligible errors in clinical and laboratory procedures. In this aspect, customized zirconia post and cores provide a viable and predictable alternative to conventional alloys.^[4] This case report gives an account of rehabilitation of a traumatized maxillary incisor along with change in spatial orientation for acceptable aesthetics.

Case Report

A 22-year-old man reported to the Department of Conservative Dentistry and Endodontics, with a complex crown fracture of his maxillary left central incisor because of road traffic accident. His medical history was noncontributory. The patient gave a history of severe pain in upper front tooth region and no immediate medical or dental consultation had been sought till then.

Intraoral examination revealed laceration of the lips, deep overbite, crossbite in relation to 22 and 32, severe crowding of lower anteriors, gingival inflammation, and grade one gingival recession in relation to 11. The maxillary left central incisor showed complex fracture with labial luxation [Figure 1]. Radiographic examination revealed complete root end development of the tooth. Considering the clinical situation, it was planned to institute endodontic treatment of maxillary left central incisor followed by orthodontic treatment before placement of permanent crown. The patient was not keen for orthodontic procedure on account of cost and time constraints, but needed the treatment to be completed at the earliest, which would restore the aesthetics. Hence, endodontic treatment and custom post–core were planned to achieve the altered angulation of final crown in the arch in harmony with neighboring teeth for improved aesthetics. He was thoroughly explained about the treatment plan, and an informed consent was obtained.

Figure 1: Complex fracture of crown with luxation, inflamed gingiva of 21

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Local anesthesia (2% lignocaine, 1.5mL) was administered and the fractured portion of the crown attached to the soft tissue was removed atraumatically. Access opening was performed under rubber dam isolation and the intracanal contents were removed. The canal was cleaned and shaped after working length was determined. Copious irrigation was carried out with sodium hypochlorite (2.5%) and normal saline alternatively. The canal was dried using paper points, obturated by cold lateral condensation, and temporized with an interim material [Figure 2]. Although the patient was asymptomatic, it was planned to proceed with post-and-core fabrication after a week to allow soft tissue healing. Once the inflammation had reduced considerably, crown lengthening was performed around the tooth to increase the clinical crown height [Figure 3].

Figure 2: Completed endodontic treatment of 21

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Figure 3: Anterior view showing labial displacement of 21 in comparison to the adjacent teeth

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In the following appointment, post space preparation was carried out using peeso reamer leaving the 5mm of apical gutta percha seal intact. The tooth was prepared and an 18-gauge SS orthodontic wire was used as a dowel pin, which could be bent and oriented in alignment with neighboring teeth to result in similar axial inclination of the final crown.

The extent of dowel pin into the canal was measured by placing a notch on the dowel and the thickness was adjusted with rotary bur until it reached the marking. Petroleum jelly was mildly coated on the canal walls, the other tooth surface, and the gingival tissue to prevent sticking of the acrylic resin. Polymer and monomer of pattern resin (GC America Inc) were dispensed in small rubber cups. Monomer was first applied on the dowel with a fine brush. The tip of the brush was moistened with the liquid and a small amount of polymer was picked up and the mixture was deposited on the dowel. The dowel was progressively built up, placed into the canal, and allowed to set for a few seconds. It was gently removed and placed back into the canal few times to avoid sticking inside the canal. This process was repeated till the post had a snug fit. Core was fabricated with a slight palatal inclination keeping the adjacent central incisor as a guide [Figure 4]. If the angulation of the core would not have been changed, the crown would follow the long axis of the root that would have resulted in unaesthetic proclination.

Figure 4: Post-and-core pattern fabricated using pattern resin

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The pattern was sent to the laboratory where a digital impression of the same was made and zirconia post–core was milled using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. The fabricated zirconia post–core was verified for its fit and occlusal clearance. Slight modifications were completed with porcelain trimming points. Bonding of the post–core was carried out under rubber dam isolation with dual cure resin cement (ParaCore; Coltene, Switzerland) by following manufacturer’s guidelines [Figure 5]. Gingival retraction was performed with number 00 size cord (Ultradent, South Jordan, Utah), impressions were made with polyvinyl siloxane material (Provil; Kulzer, Hanau, Germany). Shade selection was carried out and was communicated to the laboratory along with patient’s photographs.

Figure 5: Lateral profile after bonding of zirconia-reinforced post–core showing the change in angulation of 21 in comparison to the adjacent teeth

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The completed zirconia-reinforced all-ceramic crown of prescribed shade was received from the laboratory. After try-in for any discrepancies and premature contact in function, the crown was bonded with appropriate shade of dual-cure resin cement [Figure 6].

Figure 6: Photograph of zirconia-reinforced all-ceramic crown in place showing the altered angulation of 21, resulting in improved aesthetic profile

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The patient was recalled after 3 days for initial review and was found comfortable. Maintenance instructions were given. He was followed up with 6-month and 1-year recall. The clinical outcome was found to be satisfactory without any signs and symptoms.

Discussion

Grossly destructed teeth cause a restorative challenge for the practitioner. Post-and-core restorations are considered to be a boon for managing such teeth.^[5] Baba^[6] stated that a custom cast post–core is needed in clinical situations where it is necessary to alter the angle of the core in relation to the tooth.^[7] Customized post–core is conventionally fabricated using precious or base metal alloys. Precious alloys result in a better outcome compared to base metal alloys in terms of fit and finishing because of better malleability. However, the availability and the cost factor are the major constraints for these alloys^[8] and base metal alloys do not result in satisfactory outcome because of high melting range and casting shrinkage. Also, the chair-side modifications of a base metal alloy post–core are relatively difficult during try-in stage. Moreover, as this case presented a different alignment of the core, it would have been difficult to fabricate and finish if base metal alloy had been used.

Aesthetic posts are needed as traditional metallic posts with all-ceramic crowns fail to achieve satisfactory aesthetic result as they alter the restoration color, inhibit light transmission, and promote a rather thick, grayish line on the marginal gingiva.^[9],[10] With the increasing demand for aesthetics and development of CAD-CAM technology, a zirconia post–core has been used as an alternative to a cast post–core in the aesthetic zone.^[11],[12] In 1989, Kwiatkowski and Geller^[13] introduced the cast glass ceramic post–core to retain the color and translucency of pulpless teeth.

Zirconia-reinforced porcelain has been used widely with predictable success to fabricate restorations since the early 1990s and is considered to be the strongest and toughest ceramic material.^[14] They contain zirconium oxide (94.9%) and yttrium oxide (5.1%) and are referred to as yttrium-stabilized tetragonal zirconia polycrystals (Y-TZP). Under stress, the tetragonal crystal phase of Y-TZP transforms to a monoclinic phase, with an associated volumetric expansion of 3%–5%, which produces an internal stress that opposes the propagation of cracks that commonly lead to the fracture of traditional ceramics.^[11],[15] These all-ceramic restorations have much better fit, are biocompatible, physically soft tissue friendly with advantage of good dimensional stability, radiopacity, optimum hardness, modulus, and flexural strength (900MPa, similar to that of metal post).^{[16],[17],[18],[19],[20]}

On the basis of clinical situation and specific aesthetic requirements of the patient, customized CAD-CAM post–core with zirconia-reinforced porcelain was planned. The final crown was also fabricated using CAD-CAM procedure after minimal preparation of the core. This enabled to preserve the remaining tooth material, which had been compromised earlier because of trauma. The crown was bonded with resin cement, which provided better fit and retention, resulting in a more stable post-core-crown complex. The recall appointments were uneventful and did not show any change in form or function of the aforementioned restoration.

The literature search did not show many case reports using CAD-CAM post-and-core fabrication with zirconia though some information was available from previous in vitro studies.^[21] As the manual errors are minimized, this technique is a viable alternative to methods using conventional materials.

The long-term treatment outcome is primarily dependent on the appropriate case selection owing to the clinical complexity. Further due to relative high cost and poor retrievability of ceramic posts, these restorations are indicated in cases with aesthetic requirements and favorable occlusion.^[11]

Conclusion

The functional and aesthetic restoration of severely compromised anterior teeth has always posed a challenge to clinicians. The use of metal substructures for post–cores and copings, often make it difficult to achieve optimum duplication of the optical characteristics of an intact tooth. Posts, cores, and copings fabricated in ceramic materials offer a promising alternative to metals in the restoration of severely compromised anterior teeth.

Clinical relevance statement

The precise fabrication of post–core by CAD-CAM procedure using zirconia provides considerable advantage over other materials and methods of fabrication.

Acknowledgement

We gratefully acknowledge the lab support of M/s Rao Dental Lab, Bengaluru, Karnataka, India, for fabrication of zirconia post.

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

Nil.

Conflicts of interest

There are no conflicts of interest.

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