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Table of Contents   
CASE REPORT  
Year : 2020  |  Volume : 31  |  Issue : 1  |  Page : 160-163
Cone beam computed tomography aided endodontic and aesthetic management of fused mandibular incisors with communicating canals


1 Department of Conserative Dentistry and Endodontics, Raghav Dental Clinic, Chennai, Tamil Nadu, India
2 Department of Conservative Dentistry and Endodontics, GDCRI, Bengaluru, Karnataka, India

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Date of Submission31-Oct-2018
Date of Decision12-Dec-2018
Date of Acceptance03-May-2019
Date of Web Publication02-Apr-2020
 

   Abstract 


Endodontic treatment of fused teeth needs special care and attention due to its complex anatomy. The aim of this article is to highlight the problems encountered and the strategy in treating such cases. We report a case of unilateral fusion of the left mandibular central incisor and lateral incisor, with a single pulp chamber. The single pulp chamber separates into two root canals and a large communication exists at the apical third of the root canals. This is the first time fused teeth with a large communication is reported. CBCT analysis was effective in confirming the morphological aberrations and aided in accurate planning and treatment. Chemomechanical preparation with manual dynamic irrigation coupled with passive ultrasonic activation of the irrigant and obturation with thermoplasticised gutta percha helped in successful outcome of the case.

Keywords: Communication, cone beam computed tomography, fused, gutta percha, ultrasonics

How to cite this article:
Karumaran CS, Kumar AR, Neelakantappa KK, Sundaran RM, Venkatesan R, Naik SB. Cone beam computed tomography aided endodontic and aesthetic management of fused mandibular incisors with communicating canals. Indian J Dent Res 2020;31:160-3

How to cite this URL:
Karumaran CS, Kumar AR, Neelakantappa KK, Sundaran RM, Venkatesan R, Naik SB. Cone beam computed tomography aided endodontic and aesthetic management of fused mandibular incisors with communicating canals. Indian J Dent Res [serial online] 2020 [cited 2021 May 11];31:160-3. Available from: https://www.ijdr.in/text.asp?2020/31/1/160/281822



   Introduction Top


Developmental dental anomalies are marked deviations in the permanent or deciduous tooth from the usual anatomical and structural form.[1] Anomalies occur during the proliferation, morphodifferentiation, eruption or post eruption phases of tooth development. The severity depends on the formation stage of the involved teeth.[2]

Fusion (Synodontia or False Gemination) is defined as the union of dentin and enamel of two separately developing teeth germs to form a single tooth with a bifid crown.[3] Various terms used in literature for fused tooth are: Double tooth (Brooke and Winter, 1970); Double or Connated tooth (Soames and Neville, 1999) and Dental twinning (Killian and Croll, 1990).[3],[4] Depending on the developmental stage at the time or moment of union, it may be either partial or complete.[4] When the fusion is complete, a single tooth is formed and this leads to a reduced number of teeth in the dental arch. Partial fusion clinically have a single crown with separate roots and a common pulp chamber.[4] The spectrum of fusion could be an attempt to divide completely or partially between two normal teeth or a normal and a supernumerary tooth which is usually present with a single pulp chamber when observed radiographically.[5]

Tooth fusion is more prevalent in the primary dentition (0.5% to 2.5%) than in permanent dentition (0.1%).[3],[5] Fusion cases are frequently reported in the incisors and rarely in the posterior dentition. Etiology of fused teeth is not clear but pressure or physical force (trauma, genetic and environmental) producing close contact between two developing tooth buds. Fused teeth are also observed as a part of various syndromes such as achondrodysplasia, chondroectodermal dysplasia, focal dermal hypoplasia, and osteopetrosis.[6]

Clinically, fused teeth have an unaesthetic, irregular morphology and can cause complications like caries in the groove between the fused crowns with pulpal involvement necessitating to endodontic treatment. An accurate clinical and radiographic examination combined with knowledge about the morphologic features is necessary to perform the diagnosis. Although periapical radiographs are routinely used to evaluate root anatomy, they might be inconclusive in some situations due to their inherent limitations.

This paper highlights management of a unilateral fusion of left mandibular central incisor and lateral incisor. The IOPA revealed fused teeth having a single pulp chamber separating into two canals.

Cone Beam Computed Tomography was helpful in identifying large communication existing between the canals in the apical third. This is the first case report revealing the presence of such a communication between the canals in the endodontic literature. A combined chemomechanical preparation and obturation with thermoplasticised gutta percha helped in successful outcome of the case. It also emphasizes the role of operating microscope in managing such cases.


   Case Report Top


A 34-year-old male patient was referred to a private clinic with intermittent pain as the chief complaint in the lower front tooth region for the past two months. The patient's medical history was non contributory.

Intra oral clinical examination revealed gingival inflammation with absence of periodontal pocket associated with the fused teeth. There was no swelling or sinus tract. Hard tissue examination revealed the presence of an abnormally large mandibular anterior teeth [Figure 1]a and [Figure 1]b. There was a groove present between the fused central and lateral incisors on the buccal and lingual surface. Dental floss (Colgate, India) was used to confirm the fusion as the floss could not pass between the teeth. The tooth exhibited moderate sensitivity and pain to percussion. Intraoral radiographic examination revealed mild periapical radiolucency associated with the teeth. It also revealed the presence of single pulpal chamber dividing into two canals and a common exit. The mesiodistal width of the tooth was more than the normal. A CBCT scan was suggested to understand the tooth morphology and the root canal system. The CBCT revealed a single pulp chamber with two separate root canals and a communication in the apical third of the canal (2.9 mm coronal to the apex) with two separate apical exits [Figure 2].
Figure 1: (a) Labial view of the fused tooth #32 and #31; (b) lingual view of the fused tooth; (c) lower magnification view of the access opening with common pulp chamber; (d) lower magnification view of the pulp chamber floor with canal orifices obturated

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Figure 2: Cone beam computed tomography images (a) coronal view of the fused tooth #32 and #31 with a single pulp chamber, separate root canals and an communication in the apical third; Axial view showing (b) a single pulp chamber; (c and d) two separate root canals; (e) communication in the apical third (appro × 2.9 mm from apex); (f) two separate apical exits

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Pulp vitality test was performed using thermal (cold test) and electric testing method and it elicited a negative response. After the clinical, radiographic and CBCT scan evidence, it was diagnosed as fused tooth #31 and #32 with symptomatic periapical periodontitis. The advised treatment plan was root canal treatment followed by esthetic restoration.

Local anaesthesia was achieved with 2% Lidocaine with 1:1,00,000 epinephrine (Lignospan special, Septodont, France) and the tooth were isolated with a rubber dam [Figure 1]c and [Figure 1]d. The coronal access cavity was prepared on the lingual aspect. The tooth had two separate root canal orifices and the canals were negotiated using stainless steel 10 K files (Mani, Japan) [Figure 3]a and [Figure 3]b. The root canals were cleaned using 3% sodium hypochlorite (Parcan, septodont, India) as irrigant with manual dynamic irrigation and ultrasonic activation of the irrigant using Ultrasonic tips (Satelec) and stainless steel K files (Mani, Japan). The canals were prepared using crown down technique. The canals were dried with paper points (Dentsply, Maillefer), coated with calcium hydroxide (RC Cal, Prime Dental products, Mumbai, India) and dry sterile cotton pellets were inserted followed by a temporary seal with IRM (Dentsply) [Figure 3]c.
Figure 3: Intra Oral Peri Apical Radiograph images showing (a) preoperative image; (b) working length determination with h and k file; (c) master apical gutta percha cones; (d) apical sectional obturation and remaining canal filled with injectable thermoplasticised gutta percha; (e) follow up after 6 months; (f) follow up after 3 years

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At the second visit after two weeks, calcium hydroxide was removed, root canals were sectionally obturated at the apical third with resin sealer (AH plus, Dentsply) and 2% gutta percha (Dentsply) followed by injection of thermoplasticised gutta percha (Obtura II Spartan) for its excellent flow properties into the various canal aberrations like the communication. Obturation was completed and the access cavity was restored with Light Cure Composite material (3M Filtek Z 150 Universal) [Figure 3]d. Patient was advised to report after 3 weeks and the recall examination showed that the tooth was functional and asymptomatic.

Esthetic management was initiated with veneer preparation, which consisted of 2 mm reduction of the incisal and the labial portion of the tooth [Figure 4]a. Impression of the prepared tooth was taken with Condensation silicone (Aquasil Soft putty, Dentsply).
Figure 4: (a) Veneer preparation; (b) Veneers luted; (c) follow up after 6 months; (d) follow up after 3 years

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On the subsequent appointment, the fabricated veneers lithium disilicate (IPS e-max Ivoclar Vivadent Inc) were luted using resin cement. (Variolink II Ivoclar Vivadent Inc.) The resin was applied to the veneers that were gently seated with finger pressure. Excess cement was removed with an explorer and a microbrush. Restorations were checked for any occlusal interference. The final restorative phase was achieved by polishing the marginal areas [Figure 4]b. The patient was followed up for 3 years and showed good esthetical and functional results [Figures 4]c, [Figure 4]d and [Figure 3]e, [Figure 3]f.


   Discussion Top


The morphology of a fused tooth has to be differentiated from similar developmental anomaly like gemination for successful endodontic and esthetic management. Geminated teeth arise from a single tooth germ that attempts to divide by an invagination and the result is two completely or incompletely separate crowns with a single root and common root canal system.[2] While in the case of a fused tooth, separate pulp chambers and root canals are typically observed. In the present case, two definite and separate root canal systems with a common pulp chamber was seen in the radiographs. Examinaion of the access openings also clarified the presence of two separate root canals orifices. The fused teeth generally show differences in two halves of the joined crown i.e. they are not of the same dimensions or mirror images as seen in this case.[2]

While performing endodontic treatment, radiographs are an integral part of treatment for identifying the number, pattern and curvature of root canals, they offer limited information as they are two-dimensional representations of three-dimensional structures.[7] CBCT helps in diagnosis and locating the root canals in cases of complex and varied morphology like lateral canals, accessory canals, communications, fins and also various apical ramifications.[7] In the present case, CBCT was suggested to have a more detailed view of the complex root canal system morphology, since CBCT enables three dimensional image reconstruction. The CBCT revealed a single pulp chamber with two separate root canals indicating a case of complete fusion. It also revealed a large root canal communication located in the apical third which was not identified in the routine radiograph.

Successful root canal treatment depends on thorough cleaning, shaping, and complete obturation of the root canals. When the root canal morphology is complex, it is difficult for endodontists at times to identify the exact canal location and configuration, thus leading to inadequate instrumentation, difficulty in establishing apical stop and a dense homogenous gutta percha root canal filling.[8] In the present case, mechanical debridement of the root canals connecting via a large communication in apical third of the root was challenging.

The combination of chemomechanical instrumentation which includes ultrasonic activation and the use of calcium hydroxide as an intracanal medicament were helpful in cleaning and disinfecting the canal space. The sodium hypochlorite irrigant was activated using ultrasonics without simultaneous instrumentation (passive ultrasonic irrigation) of the canals. The capacity of irrigating solutions with good wetting ability to dissolve tissue can be improved, if the pulp tissue debris and,/or the smear layer are thoroughly moistened by the solution and it is subjected to ultrasonic agitation.[9] Mechanical preparations of the canal were done by crown down technique, which is advantageous over other techniques as it prevents the apical lodgement of debris, thereby allowing better access to the canal communication (). The use of calcium hydroxide as an intracanal medicament further enhances the process of disinfection. As calcium hydroxide has been reported to dissolve pulp tissue remaining on the root canal wall successfully, it was decided to treat the root canals with this medicament before obturating the root canal with gutta-percha.[10] The use of a thermoplasticised gutta-percha technique helped to obturate the mid third of the root canal system, as it was possible to compact the softened material with good flow property into the major irregularities like communication within the root canal system.[11] The effectiveness of a Microscope helps in better detection and removal of any residual pulp tissue in the canals after cleaning and shaping. Viewing the canal under a high level of magnification helped the operator to the see clearly during obturation.

Ceramic laminate veneers are indicated, when there is anterior dental wear and enough remaining sound dental structure.[12] This treatment option has been used due to ceramic's color stability, biocompatibility, mechanical properties and esthetic outcome. The idea of minimally invasive dental restorations is essential for successful restorations.[12] Thus, ceramic laminate veneers with minimum thickness have been increasingly indicated. The tooth preparation design and the amount of remaining dental structure have significant effect on the failure of ceramic veneers.[12] In the present case, ceramic veneer was chosen as the post endodontic treatment option.


   Conclusion Top


Successful endodontic treatment of a fused mandibular anterior tooth has been presented in this case report. There were two separate orifices with a single pulp chamber which was divided into two separate root canals. Root canal communication was identified in the apical third. This is the first reported case of fused teeth with such an apical communication. Thus, endodontic treatment was performed based on the anatomical evidences provided by a CBCT scan. Strict adherence to biomechanical principles of root canal preparation and use of advanced diagnostic aids like CBCT provided predictable successful treatment of teeth with this unusual anatomy.

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.



 
   References Top

1.
Shafer S. Textbook of Oral Pathology. 6th ed. Imprint: Elsevier India; 2009.  Back to cited text no. 1
    
2.
Sharma D, Bansal H, Sandhu S, Bhullar R, Bhandari R, Kakkar T. Fusion: A case report and review of literature. J Cranio Maxillary Dis 2012;1:114-8.  Back to cited text no. 2
    
3.
Pindborg JJ. Pathology of the dental hard tissues. Philadelphia: W. B. Saunders Co. 1970. p. 47-55.   Back to cited text no. 3
    
4.
Chunawalla Y, Zingade S, Ahmed B. Pulp therapy in maxillary fused primary central and lateral incisor: A case report. Int J Contemp Dent 2011;2:21-4.  Back to cited text no. 4
    
5.
Sunny J, Kedilaya V, Pai R, Rai D, Rao M. Fusion of teeth – A rare developmental anomaly. Brunei Int Med J 2013;9:52-5.  Back to cited text no. 5
    
6.
Rama K, Hariharavel VP, Annamalai S, Samuel AV. Bilateral fusion of permanent mandibular incisors with talon's cusp. SRM J Res Dent Sci 2017;8:144-7.  Back to cited text no. 6
    
7.
Sharma S, Sharma V, Grover S, Mittal M. CBCT diagnosis and endodontic management of a maxillary first molar with unusual anatomy of two palatal canals: A case report. J Conserv Dent 2014;17:396-9.  Back to cited text no. 7
[PUBMED]  [Full text]  
8.
Budd CS, Reid DE, Kulild JC, Weller RN. Endodontic treatment of an unusual case of fusion. J Endod 1992;18:133-7.  Back to cited text no. 8
    
9.
Mozo S, Llena C, Forner L. Review of ultrasonic irrigation in endodontics: Increasing action of irrigating solutions. Med Oral Patol Oral Cir Bucal 2012;17:e512-6.  Back to cited text no. 9
    
10.
Wadachi R, Araki K, Suda H. Effect of calcium hydroxide on the dissolution of soft tissue on the root canal wall. J Endod 1998;24:326-30.  Back to cited text no. 10
    
11.
Marlin J, Krakow AA, Desilets RP Jr, Gron P. Clinical use of injection-molded thermoplasticized gutta-percha for obturation of the root canal system: A preliminary report. J Endod 1981;7:277-81.  Back to cited text no. 11
    
12.
da Cunha LF, Reis R, Santana L, Romanini JC, Carvalho RM, Furuse AY, et al. Ceramic veneers with minimum preparation. Eur J Dent 2013;7:492-6.  Back to cited text no. 12
    

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Correspondence Address:
Chellaswamy Savrimalai Karumaran
Raghav Dental Clinic, No 9, North Gopalapuram, Second Street, Chennai - 600 086, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdr.IJDR_811_18

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