Restoration of a Structurally Compromised Maxillary Canine with a Cast Post and Crown Lengthening: A Case Report

Restoration of a Structurally Compromised Maxillary Canine with a Cast Post and Crown Lengthening: A Case Report
Arshad Hasan1 , Muhammad Ali2
(Pages 52 - 57)

1. Associate professor Department of Operaitve Dentistry Dow Dental College, DUHS.
2. Department of operative dentistry. Fatima Jinnah Dental College Hospital Karachi.

Corresponding author: Dr Arshad Hasan” arshad.hasan@duhs.edu.pk

How to CITE:

Hasan A, Ali M. Restoration of A Structurally Compromised Maxillary Canine with A Cast Post and Crown Lengthening: A Case Report. J Pak Dent Assoc 2015; 24(1):52-57.



Abstract
Structurally compromised endodontically treated teeth can be rehabilitated using a multi disciplinary approach. The treatment plan may involve all areas of dentistry. The treating clinician may find himself in unknown territory if the required plan involves procedures outside his set of skills. This might lead to presentation of more invasive plan to treat such teeth. Present report is about such a case where a canine with a history of repeated failures of post retained crowns was restored again with a custom cast post and core and an improved ferrule.

Introduction

The restoration of endodontically treated tooth with a post retained crown is a time tested treatment modality with a fair amount of clinical success1-3. A post and core restoration with adequate ferrule can salvage teeth that might otherwise be replaced by other more expensive and invasive treatment options, e.g. an endosseous implant4-6. Literature is however, replete with comparisons of longevity of both single endodontically treated tooth and single implant restorations7-11. It is important that each case be diagnosed and planned individually without been overly influenced by the implant survival studies12. However, with improved outcomes of peri-implant soft tissues and immediate implant provisionalizations on implants placed in fresh extraction sockets, there might be a tendency to favor extraction and subsequent implant placement in borderline cases13-15. Such borderline cases must be assessed individually and treatment must be instituted in the best interest of patient. The present case report is about such a borderline case where we provided the patient with a post and core retained crown to rehabilitate a badly damaged maxillary canine.

Case Report

A 63 year old healthy male presented in the dental office with a dislodged crown of left maxillary canine (FDI no 23).(fig 1, 2 & 3) The crown was placed about a year ago. Patient also reported that this was the second

dislodgement of the crown. The first time this crown was dislodged, the tooth received a tooth colored post. Patient reported no other associated symptom. Clinically, the patient had a completely restored dentition. In the left upper quadrant, there was a crown on central incisor, an implant retained restoration replacing the lateral incisor, canine had a dislodged crown and a fixed prosthesis from first premolar to first molar. Right upper quadrant was similarly restored with fixed prosthesis. The opposing arch was restored with a cast partial denture retained via precision attachments on a fixed partial denture from canine to canine. Soft tissues appeared healthy.

On a close intra-oral radiographic inspection, it was found that the tooth was previously restored with a custom metallic post and core retained crown.(fig 2)

The post had fractured leading to the subsequent dislodgement of crown and core in one piece. The fractured part of the post was retained inside the root canal space. The tooth was otherwise asymptomatic and responded negatively

to palpation and percussion. The remaining tooth structure of the tooth was less than 1 mm.(fig 1) There was adequate keratinized gingiva around the tooth with absence of inflammation and the biotype was thick. Periodontal probing depths around the tooth were within normal limits. Since there was an implant in adjacent tooth (No. 22) and a fixed partial denture (from 24 to 26) the treatment options were limited. Following options were presented to the patient.

1. Extraction of the tooth followed by an implant supported restoration
2. Restoring the tooth with a new cast post and core retained crown, provided the broken fragment of post is removed.

The patient opted to retain his tooth and it to be restored. The patient was presented following treatment plan.

1. Removal of broken fragment of post with ultrasonic vibration.
2. Surgical crown lengthening of the tooth to improve the ferrule
3. Impression of the canal space for a new custom cast post and core
4. Final impression of the tooth once the gingival architecture has healed and matured after the surgery
5. Delivery of the final crown. A consent was obtained from the patient for the treatment plan and to obtain necessary clinical photographs. In order to remove the retained post, an ultrasonic tip (start x #3 Dentsply Maillefer, Ballaigues, Switzerland) in an ultrasonic (U/S) hand piece (Maco, China) was used at medium power. In order to enhance vision, a 4x dental loupe (TAO’s Jiangsu, China (Mainland)) and a light source (TAO’s Jiangsu, China

(Mainland)) was used.(fig 4) The U/S tip was used intermittently with and without water to prevent the buildup of excessive heat. The tip was used in circular motion and was never kept at one spot for longer than a few seconds. The tip helped in breaking the cement seal and the post fragment was removed. Since the tooth was asymptomatic and the quality of endodontic treatment was satisfactory, it was not re-treated. The access cavity was sealed with a temporary restorative material (Cavit, 3M, Germany)

Surgical crown lengthening was the next step. The probing depth measured was 3mm (mesio-buccal), 3mm (mid-buccal and mid-palatal) and 3 mm (disto-buccal). Since there was an adequate band of thick keratinized attached gingiva devoid of inflammation and adequate sulcus depth, a gingivoplasty was performed with a 15 no BP blade. It helped to gain an additional ferrule of 1.5mm. After a healing period of 2 weeks, a ferrule of 2mm was achieved.

On a subsequent visit, the temporary restorative material was removed with a U/S tip (Dmetec Co. Ltd., Korea). The canal space was enlarged with gates glidden drills (Dentsply Maillefer, Ballaigues, Switzerland) in a slow speed hand piece (NSK, Nakanishi, Japan). A short tapered diamond bur (Crosstech, Thailand) in a highspeed handpiece (Alegra, W&H, Austria) to refine the preparation and place an anti-rotation groove.(fig 5) An

addition silicon polyvinyl siloxane impression material consisting of a light body and a putty in a single step was used to make an impression of the canal space. (fig 6) The impression was send to lab for fabrication of

a cast metal post. The post was received from the lab after a week.(fig 7 & 8) Fit of the post inside the canal space was checked with a radiograph.(fig 9) After radiographic confirmation, new post was luted with a



self-adhesive resin luting cement (relyx u200, 3M, Germany). Patient’s old crown was internally relieved and relined with a Bis-Acryl temporary crown and bridge material (Tempron, GC Japan) luted with a eugenol free temporary luting cement (Freegenol, GC, Japan)and patient was dismissed to allow complete healing of gingiva.(fig 10).


Four weeks after gingivoplasty, patient returned for final impression. The gingival architecture appeared healed and healthy. The temporary crown was removed and tooth structure was cleaned and dried. A braided metal reinforced retraction cord (No. 2 Roeko Stayput, Coltène/Whaledent AG Switzerland) was packed into the gingival sulcus with a cord packing instrument (Roeko retraction cord packers, , Coltène/Whaledent AG Switzerland) in order to push gingiva apically to allow impression of root surface beyond tooth preparation. (fig 11) The preparation margin was further refined with a round ended tapered diamond bur (GC4L, Crosstech, Thailand). Final impression of the preparation was taken with an addition silicon polyvinyl siloxane consisting of a light body and putty in a single step. The light body was expressed onto tooth surface and gentle stream of air was blown. Another increment of light body was expressed onto the preparation and putty was simultaneously loaded into a stock impression tray and inserted over the preparation. After setting of impression material it was removed from mouth, disinfected and sent to the laboratory for final crown fabrication.(fig 12).

Porcelain fused to metal crown was received from the laboratory after 10 days. Its marginal fit, proximal and occlusal contacts and overall aesthetics were assessed and adjusted accordingly. The resultant occlusion on the left side was group function. The crown was subsequently luted permanently with a self-adhesive resin luting cement (relyx u200, 3M, Germany).(fig 13) Patient returned for

a regular followup after 2 years and the crown was assessed to be functioning adequately.

Discussion

Present report highlights the use of a multi-disciplinary approach to treat a badly broken tooth. Patient was explained about all the possible treatment options and their consequences before formulating a treatment plan. The options were limited due to implant supported restoration and a fixed partial denture in adjacent teeth. Connecting a natural tooth to an implant has been proposed in literature16-18. However, this option is associated with intrusion of natural tooth. Use of a metal coping is advocated to counteract the negative effects of intrusion19,20. We decided not to connect the existing fixed partial denture to the implant since the resultant span would have increased the flexion in the restoration and chances of fracture of veneering porcelain would have increased21.

Extraction of canine and its subsequent replacement with an implant supported restoration was not approved by the patient. Research has shown a favorable outcome of immediate implant provisionalization of implants placed in fresh extraction sockets13-15. This option also has the benefit of restoring the esthetics in a single visit. More importantly, it allows the maintenance of soft tissue levels especially the interdental papilla14.

Most crucial factor deciding the fate of the tooth was removal of the broken fragment of the post. The post was removed with an U/S tip. Ultrasonics have been used widely in clinical dentistry for a variety of indications and have a proven safety record. Other techniques to remove posts include trephine burs, Roto-pro bur and various extractors22. U/S tips were used due to intra- radicular location of the fragment. The use of ultrasonics for removal of post may result in dentine crack formation and buildup of excessive heat with subsequent damage to the periodontal ligament23-25. In order to prevent these mishaps, the U/S tip was moved constantly in a circumferential manner. This helped to loosen the luting cement and facilitated a safe removal26,27. Vision was enhanced with the use of a loupe and an external light source. Enhanced vision has been reported to improve the changes of successful post removal28. Although an operating microscope would have been an ideal tool in this scenario, it was not available to the authors.

We used a custom cast post for this case. This decision was based on the fact that tooth had received a fiber post in past which failed. The currently failed post was also a cast post but its dimensions were inadequate, which might have resulted in the ‘favorable’ fracture pattern of the post. Cast posts have been reported to result in root fractures while the fiber posts fail more favorably owing to similarity in modulus of elasticity with dentin29. The addition of atleast 2mm of ferrule may result in improved survival of teeth restored with cast posts.5,6,30. Therefore, we performed a crown lengthening of the residual root to improve its outcome. Also, to prevent future failures a group function occlusal scheme was used. A group function occlusion allows to share the occlusal load with adjacent teeth as the mandible goes into a lateral excursion31. A canine guided occlusion may worsen the outcome in our case due to presence of a post and a history of failure32.

Conclusions

Restoration of an endodontically treated maxillary canine with a custom cast post, an adequate ferrule and a favorable occlusion pattern resulted in a successful outcome of our case at 2 year followup.

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