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199Journal of Conservative Dentistry | Apr-Jun 2011 | Vol 14 | Issue 2

Address for correspondence:Dr. Smitha Reddy, Department of Conservative Dentistry andEndodontics, Sri Sai Dental College and Hospital,Vikarabad, Ranga Reddy, Andhra Pradesh, India.E-mail: [email protected]

Date of submission: 15.09.2010Review completed: 05.11.2010Date of acceptance: 15.12.2010

Case Report

Tailor-made endodontic obturator for themanagement of Blunderbuss canalSmitha Reddy, VG Sukumaran1, Narasimha Bharadwaj2

Department of Conservative Dentistry and Endodontics, Sri Sai Dental College and Hospital, Vikarabad, Ranga Reddy District, AndhraPradesh, 1Sree Balaji Dental College and Hospital, Velachery Main Road, Narayanapuram, Pallikarnai, 2Sathyabama University DentalCollege and Hospital, Chennai, Tamil Nadu, India

A b s t r a c t

The complex anatomy of the blunderbuss root canal often poses a major challenge to accomplish adequate obturation fora biological seal. Moreover, the roll-cone, Gutta-percha obturation technique, which is routinely practiced, also results in amismatch and failure to configure to the canal volume in the absence of an apical barrier. Hence, an attempt has been madeto tailor-make a heat polymerized polymethyl methacrylate resin as an endodontic obturator, to match the canal volume, whichhas been ascertained by Spiral computed tomography and mathematical integration. A one-year follow-up examination hasrevealed that the tooth is asymptomatic, with the repair of the lesion evident radiographically.

Keywords: Blunderbuss; computed tomography; obturator; polymethyl methacrylate; ultrasound

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Website:www.jcd.org.in

DOI:10.4103/0972-0707.82606

INTRODUCTION

Despite every effort being taken to stimulate the genetically

programmed formation of root barrier that remains open

following early pulp death, apexification is not always

achieved. This may be attributed to factors where there

is a non-conducive response of the Hertwigs epithelial

root sheath in the formation of a biological barrier.[1,2]

Apexification also generally fails in cases where there is a

defective access seal, inadequate cleaning and sanitizing

of the wide open canals, and environmental contamination

during the procedure, which are exaggerated in non-

compliant patients. The failure to achieve the desiredoutcome can often be asserted if closure is yet to occur

even after two years.[1]

The blunderbuss anatomy of the canal often poses an array

of difficulties to achieve adequate obturation for successful

endodontic therapy. Customization of the gutta-percha to

mold to the shape of the canal has been attempted, but

often results in apical extrusion and subsequent trauma

to the periodontal tissues, in the absence of an apical

barrier.[3] Furthermore, the presence of a thin fragile

dentinal wall enhances their susceptibility to fracture

during instrumentation and compaction.[9] In a quest to

overcome some of these existing pitfalls, the present eraof modernization, technology, and availability of various

biomaterials have augmented our desire to tailor-make a

heat polymerized polymethyl methacrylate (PMMA) resin

as an obturating material. This case report highlights the

endodontic obturator, which has been equated precisely to

the volume of the canal in all dimensions using Spiral CT

and the Mathematical segmental integration technique.

CASE REPORT

A 16-year-old male patient reported to our hospital, and

presented with pain and discharge in relation to the right

maxillary incisor. On elaborating the history of present

illness, pain was found to be intermittent in nature, withrecurrent sinus tract formation, specific to the right

maxillary central incisor (tooth #11). His past dental

history reveals apexification being attempted for two years

in the same institution, but in vain, due to the patients

incompliance to adhere to the clinical protocol. On

intraoral examination, a sinus opening with discharge was

located on the mucolabial fold, distal to the apical region

of tooth #11. Thermal and electric pulp tests showed that

the right maxillary central incisor did not respond to the

vitality tests, whereas, all the adjacent teeth displayed a

normal response, which suggested that tooth #11 was

non-vital. Furthermore, the intraoral periapical radiographs

demonstrated an incompletely formed root, with a

blunderbuss apex, surrounded by periradicular rarefaction

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Reddy, et al.: Tailormade endodontic obturator

in relation to tooth #11. Also, the radicular dentin was thin

and fragile with apically divergent canals, as is evident in

Figure 1a.

In order to assess the exact nature of the periapical

tissues, with the patients consent, an ultrasound was

performed with a modified transrectal probe. A hypoechoic

lesion measuring 6.5 5.6 mm, with posterior acousticenhancement, consistent with fluid collection, was seen

near the root tip of the right maxillary central incisor

[Figure 2a]. This loculation was associated with a focal

erosion of the anterior wall of the alveolar socket, confirming

the features of a chronic periapical abscess. From the

above-mentioned findings, it was decided not to pursue

with apexification, and hence, an alternative method of

treatment was instituted, which involved the fabrication of

a tailor-made endodontic obturator for adequate obturation,

to precisely match the root canal volume and defect with

the aid of Spiral CT and Endometrics.

The treatment was divided into three phasesPreparatory phase: The access cavity was modified and the

coronal third of the canal was prepared to obtain parallelism,

with minimal alteration of the effective radicular dentin

thickness. A wax pattern of the canal was taken using a

110-size file as a sprue pin, in a manner similar to that of

a custom-cast post. The wax pattern was heat processed

following the steps of flasking, dewaxing, and acrylization,

to obtain a heat polymerized acrylic resin obturator

[Figures 3a and b]. The patient was then subjected to spiral

CT, which clearly demonstrated the defect in relation to

tooth #11 [Figure 2b]. From the spiral CT images, the

volume of the canal space was precisely calculated, which

was found to be 152.296 cu mm. The volume of the resin

obturator was also calibrated using the mathematical

segmental integration technique, wherein, the specimens

were divided into different segments of 3 mm length, and

the width of these segments was measured. Each segment

could be considered as a truncated pyramid and the volume

was calibrated using the formula:

Volume = H / 3 (A2 + B2 + AB)

where H was the thickness of specimen, A was the area of

the cross-section at the top portion, and B was the area of

cross-section at the bottom portion.

The total volume of the entire specimen was computed

by integrating the individual segments, which was found

to be 149.625 cu mm. The apical 3 mm of the obturator

was sectioned with a diamond disk to accommodate for

Mineral Trioxide Aggregate (MTA) as a root-end filling

material.

Surgical phase: A mucoperiosteal flap was raised in the

maxillary anterior region and the bony defect located.

Following thorough debridement and curettage of the

periapical lesion, the palatal cementum was retained and

MTA was placed as a retrograde material and condensed

against the resin obturator within the canal, which acted as a

template. The resin obturator was then removed and a moist

cotton pellet placed in contact with the MTA for 24 hours,

to ensure its complete set as suggested by earlier studies.

Obturation phase: After 24 hours the moist cotton pellet was carefully retrieved and obturation was completed

by luting the endodontic obturator with dual cure resin

cement. The access cavity was sealed with a light activated

hybrid composite, as was evident from the postoperative

radiograph [Figure 1b]. Six- and twelve-month follow-

up radiographs demonstrated a significant reduction of

periapical radioluscency, with no symptoms [Figures 4a

and b].

Figure 1: Intraoral periapical radiographs in relation to tooth# 11. (a) Preoperative radiograph showing the blunderbusscanal with periradicular lesion, (b) Immediate postoperativeradiograph showing apical 3 mm of MTA and Endodonticobturator in place

a

b

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201Journal of Conservative Dentistry | Apr-Jun 2011 | Vol 14 | Issue 2


DISCUSSION

The failure of apexification could be attributed to the

probable destruction of the Hertwigs epithelial root

sheath and the non-conducive environment in relation

to the periapical region of tooth 11, which was evident

from the hypoechoic images obtained with the ultrasound.

Ultrasonography depicts the true nature of the lesion within

the bone in three dimensions, and their content in terms

of fluids, tissue, and vascularity, with the precise measure

of the diameters of the lesion.[5,6] Roll-cone Gutta-percha

obturation with lateral compaction is not the technique of

choice, due to lack of resistance of the thin fragile dentinal

walls to lateral pressure, as greater bulk of Gutta-percha

requires a greater force for compaction.[4] Henceforth,

customization of an obturator to match the canal volume

without lateral compaction will be attempted using PMMA,

which is extensively used in the field of medicine for fixation

of orthopedic implants, test kits, diagnostics, and so on,

and this demonstrates its excellent biocompatibility with

tissues. [7] Also, heat polymerization of PMMA markedly

increases the degree of conversion, reducing the

availability of free monomers. Furthermore, the inherent

ability of these acrylic resins to be custom formulated

has enabled us to tailor-make a heat polymerized acrylic

resin, as an endodontic obturating material.

Computed Tomography (Spiral CT) was employed to

precisely calibrate the volume of the canal in cubic

millimeter, and furthermore, the CT images obtained

also confirmed the nature of the periapical tissues. [5] The

volume of the heat polymerized endodontic obturator

was calculated by mathematical integration, in order to

precisely equate the canal volume using endometrics.

The palatal cementum of the root end was retained for

the specific reason that the cementum thickness on the

palatal aspect was usually found to be thicker comparedto the buccal portion, which facilitated the healing

process.[8,9] MTA was used as a root end filling material,

which was placed in two steps, as the two-step retrograde

placement technique exhibited less leakage compared to

one-step placement. Furthermore, Gray MTA was used in

a 3 mm thick barrier in preference to white MTA, because

Tetra calcium aluminoferrite was absent in the white

formulation, which could be responsible for its altered

properties. As both materials appeared clinically set and

showed no difference in hardness, it was hypothesized

that slight volumetric shrinkage occurred with the white

product, which accounted for the increased leakage

between MTA and the root dentin, and this substantiated

the preference of Gray MTA.[10,11] Dual cure resin cement

was used for luting the endodontic obturator into the

canal, which might compensate for the 1.7% volumetric

linear shrinkage exhibited by the resin obturator during

fabrication by heat polymerization. Furthermore, the

resin cement showed enhanced resistance to shear

stress, and the access cavity was sealed with a hybrid

light cure composite resin, to ensure an adequate coronal

seal.[12,13] One of the drawbacks of PMMA was, it was less

Figure 2a: Ultrasound showing hypoechoic images withdisruption of the anterior wall of the alveolar socket of thetooth involved

Figure 2b: Computed Tomographic image demonstrating

enhanced canal volume and defect

Figure 3: (a) Wax pattern of the canal with 110-size file usedas a sprue pin, (b) Heat polymerized PMMA resin obturator

a b

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Journal of Conservative Dentistry | Apr-Jun 2011 | Vol 14 | Issue 2202


How to cite this article: Reddy S, Sukumaran VG, Bharadwaj N.

Tailor-made endodontic obturator for the management of Blunderbuss

canal. J Conserv Dent 2011;14:199-202.

Source of Support: Nil, Conflict of Interest: None declared.

radio opaque. In future, few radio opaque materials

like Barium Sulfate could be added to the endodontic

obturator. Retrievability in case of re-treatment, couldbe accomplished by progressively drilling through the

middle of the post like the Fiber Reinforced Composite

post.[14]

Despite the potential residual infection and the serious

damage caused, MTA at the apical 3 mm, effectively

promoted regeneration of the apical tissues, producing

a desirable apical barrier, which was evident from the

follow-up radiograph after a one-year period.

ACKNOWLEDGMENT

Prof. Dr. PRABAKARAN, Professor and Head, Department ofStructural Engineering, Jerusalem College of Engineering,

Pallikarnai, Chennai-601 302, India

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2. Weine FS. Alternatives to Routine Endodontic Treatment. EndodonticTherapy. 6th ed. United States: Mosby Inc.; 2004. p. 513-44.

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Obturation of the Radicular Space. In: Ingle JI, Bakland LK, editors.Endodontics. 5th ed. India: Harcourt India Pvt Ltd; 2002. p. 571-668.

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Study of White and Gray Mineral Trioxide Aggregate (MTA) Simulating

a One- or Two-Step Apical Barrier Technique. J Endod 2004;30:876-9.11. Goto Y, Nicholls JI, Phillips KM, Junge T. Fatigue resistance of

endodontically treated teeth restored with three dowel- and- core

systems. J Prosthet Dent 2005;93:45-50.12. Hemamalathi S, Nagendrababu V, Kandaswamy D. A single step

apexification and intra radicular rehabilitation of fractured tooth- a

case report. J Conserv Dent 2007;10:48-52.13. De Rijk WG. Removal of fiber posts from endodontically treated teeth.

Am J Dent 2001;13:198-218.

14. Hayashi M, Shimizu A, Ebisu S. MTA for Obturation of MandibularCentral Incisors with Open Apices: Case Report. J Endod

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Figure 4: Follow-up periapical radiographs in relation totooth # 11. (a) six-month follow-up radiograph showingreduction in periapical radioluscency, (b) one-year follow-up radiograph with marked reduction in periapicalradioluscency

b

a

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