Saudi Endodontic Journal

: 2014  |  Volume : 4  |  Issue : 1  |  Page : 32--35

Crown discoloration due to the use of triple antibiotic paste as an endodontic intra-canal medicament

Manuel Sebastian Thomas 
 Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka, India

Correspondence Address:
Manuel Sebastian Thomas
Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Light House Hill Road, Mangalore - 575 001, Karnataka


The use of triple antibiotic paste (TAP) (mixture of ciprofloxacin, metronidazole and minocycline) as an intra-canal medicament have shown very encouraging results particularly in non-vital immature teeth associated with periradicular lesions. Hence, before opting for a surgical approach, a non-surgical approach can be thought of with extended use of TAP as intra-canal medicament, especially in patients who are phobic to invasive procedures. On the flip side, the use of TAP has few side-effects, of which one is the discoloration it can cause due to the presence of minocycline in the mix. The purpose of this article is to presents a case of coronal discoloration due to the use of TAP as an endodontic intra-canal medicament.

How to cite this article:
Thomas MS. Crown discoloration due to the use of triple antibiotic paste as an endodontic intra-canal medicament.Saudi Endod J 2014;4:32-35

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Thomas MS. Crown discoloration due to the use of triple antibiotic paste as an endodontic intra-canal medicament. Saudi Endod J [serial online] 2014 [cited 2021 May 6 ];4:32-35
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Periradicular lesions associated with a non-vital tooth can be generally grouped as periapical abscess, granuloma or cyst. [ 1 ] Zain et al. reported that the presence of large size of periapical radiolucency is more likely to be a periradicular cyst. [2] Since the primary cause for these periradicular lesions are the microorganisms, utmost importance needs to be given to the sterilization of the root canal system. [3] Various treatment approaches to manage a large periapical lesion can be broadly classified as either surgical or non-surgical endodontic therapy. As surgical approaches have many shortcomings, it is advisable to treat initially all periradicular lesions conservatively by a non-surgical root canal therapy with the use of an antimicrobial intra-canal medicament. [4]

Although calcium hydroxide is the most commonly used intra-canal medicament, it has limited effectiveness in the complete elimination of microorganisms from the root canal system. [5] Hence for effectively removing the complex microbial flora from the root canal, combinations of antibiotics have been suggested. [6] Triple antibiotic paste (TAP) "combination of metronidazole, ciprofloxacin and minocycline" is one such combination of antibiotics, which has shown positive outcome. [7] Even though, this antibiotic combination has shown promising results, it is shown to cause discoloration of the coronal tooth structure. [8] This article presents a case of crown discoloration due to the use of TAP as an endodontic intra-canal medicament.

 Case Report

A 19-year-old female patient reported to the Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Mangalore with a chief complain of fractured restoration in the upper front teeth. She gave a history of mild intermittent pain in the upper front teeth region. On further history taking it was revealed that the patient had a blow to her front teeth that resulted in the fracture of incisal edges of her upper central incisor, when she was 10-year-old. After some palliative treatment, the teeth were immediately restored with composite resin restorations.

On intraoral examination, it was seen that the mesial incisal angle of both maxillary central incisors had fractured composite resin restorations. Patient had mild discomfort on vertical percussion with respect to maxillary lateral right (#12) and left (#22) incisors. Patient also complained of discomfort while palpating the mucobuccal fold corresponding to the upper central incisors. Intraoral periapical radiograph showed the presence of large periapical radiolucency with irregular outline corresponding to the upper incisors [Figure 1]a. Pulp sensibility tests (thermal and electric pulp tests) were then performed to determine the teeth responsible. As per the tests, it was concluded that only the maxillary central right (#11) and left (#21) incisors were the culprit.{Figure 1}

Patient was reluctant for any sort of surgical procedure as she described an intense fear for any surgical intervention. Therefore, a non-surgical approach was chosen to treat this case of asymptomatic apical periodontitis associated with necrotic pulp. Access opening was carried out under proper aseptic condition for both the upper central incisors. The working length was determined and canals were shaped with K-files (Dentsply-Maillefer, Ballaigues, Switzerland) to an apical preparation of ISO size #80. During the preparation, the canals were irrigated with 2.5% NaOCl (Novo Dental Products Pvt. Ltd., Mumbai, India), 17% ethylenediaminetetraacetic acid (B.N. Laboratories, Mangalore, India) and 0.2% chlorhexidine (Vishal Dentocare Pvt. Ltd., Ahmedabad, India) with in between saline flush to remove the necrotic debris from the pulp space. The access cavity was sealed with zinc oxide eugenol temporary restoration (Dental Products of India, Mumbai, India). The next day patient returned with severe pain with respect to both teeth. On examination, it was seen that both #11 and #21 were severely tender to percussion. It was concluded that it was a case of mid-treatment flare-up. The canals were opened again. Pus discharge was allowed to drain. Canals were dried and closed dressing was followed. Patient was put on systemic antibiotics (Amoxicillin; Amox 500 mg 3 times daily 5 days) and analgesics (Ibuprofen; Brufen 400 mg twice daily for 3 days).

On the recall visit after 4 days, it was seen that the patient still had mild tenderness and that the canals were still weeping on the removal of the temporary restoration. The canals were once again irrigated with chlorhexidine and an intra-canal medicament, TAP, was placed. The TAP was prepared as described by Takushige et al., [9] using commercially available tablets of Ciprofloxacin (Cifran 500 mg, Ranbaxy Laboratories Ltd., India), Metronidazole (Metrogyl 400 mg, J.B. Chemicals and Pharmaceuticals Ltd., India) and Minocycline (Minoz 50 mg, Ranbaxy Laboratories Ltd., India). Following the removal of the enteric coating of the tablets, the contents were pulverized using a mortar and pestle and mixed with propylene glycol to obtain paste form. The paste was packed into the canal using hand plugger and the access was sealed with zinc oxide eugenol temporary restoration (Dental Products of India, Mumbai, India). Patient was then recalled after 2 weeks, the canals were now free of any exudate. The TAP was again placed as an intra-canal medicament. On her next visit after 2 weeks, slight greenish tinge was noticed in the upper central incisors, which were not very significant [Figure 1]b.

Since both the teeth were asymptomatic, antibiotic paste was removed and the canals were obturated with gutta percha (Dentsply-Maillefer, Ballaigues, Switzerland) and AH plus sealer (Dentsply, De Trey, Konstanz, Germany) using the lateral compaction technique. Interim glass ionomer restoration was then placed. Patient was asked to get the core build up and full coverage crowns from the place where she was going to continue her further studies. As she could not find time, she came back to the institution for the completion of the treatment during her vacation. On examination, the teeth were asymptomatic and post-obturation radiograph taken after 10 and 18 months showed an increase in periradicular bone density suggestive of progressive healing [Figure 1]c and d. Unfortunately, the teeth had a very evident greenish intrinsic staining [Figure 2]a and b. It was concluded that the TAP had resulted in discoloration. The access cavity was restored and coronal reinforcement was carried out using composite resin restoration (Filtek Z350, 3M ESPE, St. Paul, Minnesota, USA). Later, full coverage ceramic crowns (IPS e.max Press, Ivoclar Vivadent AG, Schaan, Liechtenstein) with subgingival margins were placed to mask the discoloration [Figure 2]c.{Figure 2}


The initiation and propagation of a periapical lesion of endodontic origin is mainly associated with microorganisms within the root canal system. The lesion associated with the necrotic teeth in the present case was thought to be a periradicular cyst as it had a diameter greater than 10 mm and since there was drainage of exudate through the canal after access opening. Such large periapical lesions can be treated either by surgical or non-surgical methods. [7] In the present case, a non-surgical approach to treat the large periapical lesion was opted because of the extreme fear of the patient for any surgical procedure (tomophobia) and also because of the proximity of the lesion to the adjacent vital lateral incisors and to the floor of the nasal cavity. [10]

TAP was used as the medicament of choice for the non-surgical endodontic therapy in the present case as previous studies have shown its effectiveness in the elimination of the microorganism from the root canal system. [6],[9],[11] Hoshino et al. [11] in their in-vitro study on the antibacterial efficacy of metronidazole, ciprofloxacin and minocycline alone and in combination against the bacteria of infected dentin, infected pulps and periapical lesions showed that they are incapable of complete elimination of bacteria, when used alone. However, in combination, these drugs were able to consistently sterilize all samples. Hence the concept of lesion sterilization and tissue repair; therapy, i.e., the combination of the above mentioned drugs can be employed in infected teeth with large periapical lesions were diverse microflora can be encountered. In accordance with the previous study, the present case reports also demonstrated favorable healing of the large periapical lesion with non-surgical endodontic therapy using TAP. [7],[12]

Calcium hydroxide, which is the commonly used intra-canal medicament, have shown limited effectiveness in disinfecting the root canal system because of the dentinal protein buffering and its inability to eliminate certain microorganism especially within biofilms. [5] Long-term calcium hydroxide placement has shown to result in higher incidence of root fracture either due to the disruption of the link between the hydroxyapatite crystals and the collagenous network in dentin or because of the reduced organic support due to denaturation and hydrolysis. [13] Hence, the use of TAP can overcome these disadvantages of calcium hydroxide. TAP is also biocompatible as evident from its use in regenerative endodontics. [14]

In-vitro studies on TAP have demonstrated that 24-48 h application is sufficient for effective disinfection of infected root dentin. [6],[11] None the less, TAP has to be used judiciously as it comes with few disadvantages.

Discoloration of the coronal tooth structure can be one major problem as demonstrated in the present case report. The reason for the discoloration is said to be the minocycline present in the antibiotic mix. [8] It is thought to bind with the calcium of dentin forming insoluble complexes, resulting in discoloration. The reason for extensive discoloration in the present case could be because of the extended use of the TAP (4 weeks) in the root canal. [8] Removal of the smear layer before intra-canal medicament placement and contact of the TAP in the coronal area during its placement could have also added to the severity of discoloration. [15]

In the present case, the discoloration was managed using all ceramic crowns. The margin of the tooth preparations were placed subgingival. Double cord retraction technique was used to record the finish line details. During tooth preparation, a labial reduction of 2 mm was performed to provide space for ceramic layering over opaque core. Masking ability of leucite reinforced ceramic was shown to be adequate. [16]

Some of the methods proposed to eliminate the occurrence of discoloration with TAP have been mentioned below. Minocycline in the TAP can be substituted with non-discoloring medicaments, for example cefuroxime or Arestin. [17] If at all these medicaments are to be used, they should be confined to the root canal, apical to the gingival margin. The clinician should remove residual paste from the pulp chamber and wipe clean it with cotton pellets soaked in absolute alcohol. [15] Sealing of the coronal dentin with a bonding agent and use of different delivery systems for placement of the medicaments into the root canal without contacting the coronal pulp chamber have also been attempted to reduce the incidence of medicament related tooth discoloration. [15]

Dentist should also be vigilant when giving local or systemic drugs. Even though, the local application of antibiotics within the root canal system is an effective mode for delivering the drug and the volume of the drugs used during this treatment is small, care should be taken if patients are sensitive these antibiotics. [7]


TAP as an intra-canal medicament can promote healing of large periapical lesion. Despite the biological success, antibiotic medicaments containing minocycline should be used with extra caution especially in teeth present in the esthetic zone. The effectiveness of various minocycline substitutes and techniques to limit the placement of intra-canal medicaments in the root canal without contacting the coronal dentin needs to be evaluated.


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