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Endodontic treatment of a maxillary right canine with necrotic pulp, periradicular lesion, and type III dens invaginatus.
Educational aims and objectivesThis clinical article aims to report the 3-year follow-up of a maxillary right canine with dens invaginatus type III and radiolucency adjacent to the root.Expected outcomesCorrectly answering the questions following this article, worth 2 hours of CE credit, will demonstrate you can describe dens invaginatus, a rare malformation of teeth, probably resulting from an infolding of the dental papilla during tooth development. Click here to recieve CE credits and to take the Vieyra CE Quiz.
Dens invaginatus is a rare malformation of teeth with a broad spectrum of morphological variations. The affected teeth present with an unfolding of enamel and dentin, which may extend into the pulp cavity, into the root, and sometimes to the root apex (Hulsmann, 1997).
This pathology is a dental developmental abnormality in which the enamel organ is disorganized, leading to an invagination in the tooth crown before the calcification phase (Chen et al, 1998; De Sousa, Bramante, 1998).
Dens invaginatus occurs most frequently in maxillary teeth, lateral incisors, canines, and less frequently in central incisors (Benenati, 1994; Gound, Maixner, 2004; Nallapati, 2004; Steffen, Splieth, 2005; Stamfelj et al, 2007; Lichota D et al, 2008, Duckmanton, 1995). When the malformation occurs in maxillary lateral incisors, bilateral appearance is not uncommon (Hosey, Bedi, 1996). However, dens invaginatus in mandibular teeth (Er K et al, 2007; Conklin, 1978; Khabbaz et al, 1995; Muppararu, Singer, 2004), and specifically in mandibular lateral incisors, appears to be a rare condition.
However, the classification described by Schulze (1972) is more detailed, illustrating a total of 12 different cases of this anomaly. This classification reports two variations (A4, B4) in which the invagination starts laterally and near the incisal edge, and continues attached to the external outline of the affected tooth mesially or distally.
Several theories have been proposed for this phenomenon, but the etiology of dens invaginatus remains unclear.
Kronfeld (1934) proposed that dens invaginatus is caused by a focal failure of growth of the internal enamel epithelium, leading to proliferation of the surrounding normal epithelium with eventual engulfment of the static area.
Oehlers (1957) proposed that distortion of the enamel organ occurs during tooth development and results in protrusion of a part of the enamel organ. Oehlers (1957) classified these malformations into three types:
Of particular interest in his classification is type III, in which an enamel- and/or cementum-lined dens forms tracks through the root and perforates in the apical area to form a second foramen but has no direct communication with the pulp. Other theories include infection (Fischer, Zur Frage, 1936), trauma (Gustaffson, Sundberg, 1950), and genetics (Hosey, Bedi, 1996) as possible contributing factors.
Because of its unusual radiographic appearance, this particular variant has been frequently interpreted incorrectly as a double root (Hasselgren, Olsson, Cvek, 1988), a radicular invagination or an odontome (Oehlers, 1957; Grahen, Lindhl, Omnell, 1959), or a tooth twin (Hosey, Bedi, 1996). The histomorphological characteristics of the anomaly were basically explained by Rushton (1937), but since then, there have been no further histological descriptions. An understanding of the variable and complex internal anatomy of invaginated teeth is essential for radiographic identification and adequate treatment of the anomaly (Hulsmann, 1997).
The purpose of this article is to discuss the clinical management of this particular variant of the dens invaginatus form.Case reportA healthy 23-year-old man was referred to the authors’ private practice with the chief complaint of a gum boil above the upper right front tooth. The patient had no significant medical history. Clinical examination revealed an intraoral sinus tract in the labial gingiva adjacent to the maxillary right lateral incisor.
Clinical tests revealed the maxillary right canine to be within normal limits to percussion and slightly tender to palpation, with a normal response to cold. The vitality of the pulp was later confirmed with a test cavity.
Radiographic examination revealed a malformation of the root with 1-2 cm radiolucency adjacent to the mesial and distal aspect of the apex of the maxillary right canine.
The sinus tract was traced with a gutta-percha point to the lesion. Radiographs revealed an enamel-lined tract, mesial to and separate from the main root canal system, that tracked to the apical radiolucency and appeared to be wide open at the portal of exit.There was a separate root canal system distal to the dens that appeared to be closed apically (Figures 1A and 1B).
A diagnosis was made of normal pulp with chronic apical periodontitis associated with the type III dens invaginatus. A treatment plan was formulated that included nonsurgical endodontic treatment of the dens tract over several appointments, including placement of a calcium hydroxide dressing (Figures 2 and 3).
The tooth was symptom-free. The clinical crown was larger, compared with the canine on the left side, especially the mesiodistal diameter.
Ethical approval for the study and an informed consent to participate was signed by the patient. Surgical intervention was considered a strong possibility. After a test cavity, which confirmed the vitality of the pulp, the tooth was anesthetized, and nonsurgical endodontic treatment was initiated.
After local anesthesia, rubber dam isolation and access cavity preparation were performed. Of particular interest was the atypical presentation of the lingual surface of the tooth. A rubber dam was placed, and access was made in the mesiolingual aspect of the tooth. Upon access into the dens, there was a serosanguinous discharge, which was allowed to drain.
The two canals were cleaned and shaped initially with a long, tapered diamond bur to improve access to the apical defect. Working length (WL) was established by using an apex locator Root Zx® (J. Morita Mfg Corporation).
The dens was debrided as well as possible, the primary canal was prepared to WL by step-back technique to a size 55 (MAF) and to a size 80 (final file); the canal was then flared by using Gates Glidden drills, sizes 1-4.
Because the canal was lined with enamel, irrigation was performed with 5.25% sodium hypochlorite, 17% liquid EDTA. Calcium hydroxide (UltraCal®, Ultradent) was placed in the dens tract between appointments.
The access cavity was sealed with Cavit™ (ESPE™, Premier) and IRM® (Dentsply Caulk) between visits to prevent contamination of the dens canal system. At the second appointment, 7 days later, the sinus tract was healed. However, there was more serous discharge followed by bleeding through the access cavity after removal of calcium hydroxide paste.
After further irrigation, more calcium hydroxide was placed in the canal, and the patient was asked to return 2 weeks later for completion of nonsurgical endodontic treatment.
At the third appointment, a rubber dam was placed back on the tooth, the main canal and the remainder of the dens tract were filled orthograde with warm gutta percha using an Obtura Gun (Obtura II) and Sealapex™ sealer (SybronEndo). The access opening was sealed with a light-cured composite, and a postoperative radiograph was taken (Figure 4).
Radiography showed an overfill of the dens tract caused by lack of anatomic stop at the apical third of the canal (Figure 5).
The patient was asked to return 1 week later for endodontic surgery, and a full-thickness flap was reflected to expose the lesion, the window into the lesion was enlarged, and the soft tissue contents were removed.
Care was exercised not to impinge on the apical area where the root canal system exited. With the help of an air-driven surgical handpiece (Impact Air 45®, Palisade Dental), the apical defect was carefully beveled to improve access to the dens.
A large amount of necrotic tissue was found in the apical third of the dens tract. A custom-bent ultrasonic tip (http://eie2.com) was used with a Satelec® ultrasonic unit to remove the tissue from the apical portion of the dens tract. Bendable and flexible surgical mirrors were used for clear vision into the apical defect.
With a high vacuum placed at the root end, the dens canal was flushed repeatedly with saline and chlorhexidine gluconate 0.12% (PerioGard®) through the coronal access to clean and disinfect the canal system.
After the canal was devoid of any residual tissue and filled material, it was dried with a Stropko™ irrigator (Vista Dental, Racine) in preparation for the root-end filling and obturation of the remainder of the dens tract. The root end was etched with 37% phosphoric acid for 10 seconds. A coat of primer (Kerr Corporation) was applied for 10 seconds and air-dried for 10 seconds.
A drop of dual-cure activator was mixed with one unit dose of dual cure paste (OptiBond™, Kerr Corporation), and the mix was teased into the apical defect and light-polymerized. Because the lesion was quite large, an absorbable collagen membrane (BioMend® Extend, Zimmer Dental) and augmentation mineral (Puros® Allograft, Zimmer Dental) were placed into the crypt to aid bone healing. The flap was repositioned and secured with 5-0 Tevdek® sutures (Figures 6 and 7).
The patient returned 48 hours later for suture removal and was seen at 1-, 3-, and 6-month recall periods for 3 years.
Complete resolution of the sinus tract was observed, and the tooth was within normal limits to percussion and palpation at each recall appointment. Radiographs showed rapid healing of the bony defect (Figures 8 and 9).
DiscussionRoot canal treatment of teeth with dens invaginatus can be difficult because of the unpredictable shape of the internal anatomy and the fact that the dens tract is lined with enamel (Hulsmann, 1997; Alani, Bishop, 2008).
The large and irregular volume of the root canal system makes proper shaping and cleaning difficult. Calcium hydroxide is helpful as an inter-appointment dressing because of its antimicrobial and tissue-dissolving properties (Hasselgren, Olsson, Cvek, 1988).
Several changes are sometimes necessary to get adequate tissue debridement. Ferguson, Friedman and Frazzetto (1980) also described the use of calcium hydroxide in teeth with dens tracts for apexification. Irrigation supported by ultrasonics has been recommended as another method to enhance disinfection (Cunningham, Martin, Pelleu, 1982; John, 2008).
Khabbaz (1995) described treatment of the dens tract as a separate canal. A warm gutta-percha obturation technique as recommended by Rottstein et al (1987) was used in this case as an effective method to fill the irregular root canal space.
Nonsurgical treatment sometimes fails because it is difficult to gain access to all parts of the root canal system (De Smit, Demaut, 1982; Paredes Vieyra, 2004; Keles A, Cakici F, 2010).
In many teeth with dens tracts, such as this one, surgery and use of a barrier for guided tissue regeneration may become necessary for a successful outcome (Sottosanti, 1992).
Depending on the degree of malformation and on the clinical symptoms, there are different methods of therapy, as preventive and restorative treatment, root canal treatment, surgical treatment, intentional reimplantation, or extraction in teeth with severe anatomic irregularities that cannot be treated nonsurgically or by apical surgery (Lichota et al, 2008).ConclusionWith the complications presented in this case of dens invaginatus type III, including an open apex and acute periapical abscess, a combination of conservative and surgical treatments preserved a functional and esthetic tooth during a 3-year follow-up.AcknowledgementsThe authors would like to thank Dr. E. Steve Senia and Dr. Michael Hülsmann for their valuable assistance in reviewing this manuscript.
Dr. Jorge Paredes Vieyra is a lecturer at the School of Dentistry, Universidad Autónoma de Baja California, Baja California, México. He is also in private practice dedicated to endodontics.Dr. Julieta Acosta Guardado is in private practice dedicated to endodontics.Dr. Francisco Javier Jiménez Enriquez is an oral surgeon.Dr. Jose Manuel Mondaca is professor of prosthetic dentistry and oral rehabilitation at the Universidad Autonoma de Baja California in Tijuana México.
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