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Oral Surgery

Authors : Dr.Parag Kerkar, Dr.Rashu Mittal, Dr.Payal Katakwar.

Abstract :

Nasopalatine duct cyst is one of the very rare developmental cysts. The case repot presents a similar such case associated with and odontome and the surgical approach to treat it.

Introduction :

Nasopalatine duct cysts (NPDCs) are developmental, epithelial, nonneoplastic cysts that are considered to be the most common (32.8-73.2%) of the nonodontogenic cysts.4 Nasopalatine duct cyst is one of many pathologic processes that may occur within the jawbones, but it is unique in that it develops in only a single location, which is the midline anterior maxilla. Nasopalatine duct cysts usually present as unilateral pathology, but they may also occur bilaterally (approximately 0.25% of all cases).

Pathophysiology :

The development of the face and the oral cavity takes place between the fourth and eighth weeks of intrauterine life. The secondary palate is formed during the eighth and 12th weeks. In the midline between the primary and secondary palates, 2 channels (the incisive canals) persist. The palatine processes probably partly overgrow the primary palate on either side of the nasal septum.1 Thus, the incisive canals represent passageways in the hard palate, which extend downward and forward from the nasal cavity. Just before exiting the bony surface of the hard palate (incisive foramen or incisive fossa), the paired incisive canals usually fuse to form a common canal in a Y shape. Nasopalatine canal evaluated by cone-beam CT scanning can be classified into 3 groups: type I (a single canal), type II (2 parallel canals), and type III (Y-type canal).

The fusion of facial processes in the embryologic development of the maxilla results in the formation of a pair of epithelial strands (the nasopalatine ducts) that traverse the incisive canals downward and forward, connecting the nasal and oral cavities.3 The nasopalatine duct leads from the incisive fossa in the oral cavity to the nasal floor, in which it ends in the nasopalatine infundibulum.

The types of epithelia that line the nasopalatine duct are highly variable, depending on the relative proximity of the nasal and oral cavities. The most superior part of the ducts is characterized by a respiratory-type epithelial lining. Moving downward, the lining changes to cuboidal epithelium. In the most inferior portion closest to the oral cavity, squamous epithelium is the usual type. In addition to the nasopalatine ducts, branches of the descending palatine and sphenopalatine arteries, the nasopalatine nerve, and mucus-secreting glands are present within the incisive canalsIn some vertebrates (eg, snakes), the nasopalatine duct plays a role in the reception of odorants.5

The nasopalatine ducts ordinarily undergo progressive degeneration; however, the persistence of epithelial remnants may later become the source of epithelia that gives rise to a nasopalatine duct cyst, from either spontaneous proliferation or proliferation following trauma (eg, removable dentures, dental implant treatment), bacterial infection, or mucus retention.

Genetic factors have also been suggested.

The mucous glands present among the proliferating epithelium can contribute to secondary cyst formation by secreting mucin within the enclosed structureNasopalatine duct cysts can form within the incisive canal, which is located in the palatine bone and behind the alveolar process of the maxillary central incisors, or in the soft tissue of the palate that overlies the foramen, called the cyst of the incisive papilla.

Case report :

A 25 year old patient came with a history of pain and swelling in relation to the nasopalatine region since the past couple of month’s .there was no history of pus discharge or salty taste in relation to the nasopalatine region. On intra oral examination there was a small noticeable swelling in relation to the nasopalatine papillae .measuring about 7mm by 7 mm. palpation revealed a compressible swelling. Aspiration was surprisingly negative. A provisional diagnosis of nasopalatine duct cyst was arrived. The patient was taken up for an IOPA which revealed a calcified odontome like mass surrounded by a circumscribed radiolucency.Final diagnosis of nasopalatine duct cyst was confirmed and surgical treatment to enucleate the cyst and remove the associated odontome was taken.

Surgical procedure :

After the routine investigations the patient was injected with lignocain with 1; 80000 adrenaline palatally around the lesion and bucally between the central incisors .a palatal mucoperiosteal flap was raised after crevicular incisions in relation to the upper incisors extending up to the 1st premolars .with a small periosteal elevator the cyst lining is separated from the bony wall and excised id toto.the calcified odontome was also removed at the same time. the palatal flap was closed back with black silk sutures
inta oral photograph showing the palatal swelling Occlusal radiograph showing the cyst and the odontome
Iopa showing the cyst and odontome Surgical exposure showing the cyst enucleated
Cystic lining and the odontome Palatal flap raised

Discussion :

Nasopalatine duct cysts (NPDCs), also known as incisive canal cysts, are the most common non-odontogenic cyst of the gnathic bones. The cyst is so common, in fact, that it will affect approximately one out of every one hundred persons 1. A developmental cyst, the nasopalatine duct cyst is believed to arise from epithelial remnants of the nasopalatine duct, the communication between the nasal cavity and anterior maxilla in the developing fetus. As fetal development continues, this connection gradually narrows as the bones of the anterior palate fuse. The result is the formation of the incisive canals that carry nerves and vessels, as well as epithelial rest from the degenerated nasopalatine ducts.

Nasopalatine duct cysts affect a wide age range, however, most present in the fourth through sixth decades of life. There is a slight male predilection. Patients may be asymptomatic, with the lesion being detected on routine radiographs, however, many will present with one or more symptoms. Complaints are often found to be associated with an infection of a previously asymptomatic nasopalatine duct cysts and consist primarily of swelling, drainage, and pain 2, 3. The vitality of nearby teeth should not be affected; however, it is not uncommon to see evidence of endodontic therapy because the nasopalatine duct cyst was previously clinically misdiagnosed as a periapical cyst or granuloma.

Radiographically, nasopalatine ducts cysts are usually well-circumscribed radiolucencies of the anterior maxilla. The cysts are apical to the roots of the maxillary incisors and rarely cause root resorption. Cysts are round, ovoid or heart shaped due to the superimposition of the nasal spine. Cysts range in size, with an average diameter of approximately 1.5 cm 1. The incisive foreman, by convention, is not expected to exceed 6 mm in diameter, making the detection of a small nasoplatine duct cyst difficult.

Histologically, the nasopalatine duct cyst is lined by stratified squamous epithelium alone or in combination with: pseudostratified columnar epithelium (with or with out cilia and/or goblet cells), simple columnar epithelium, and simple cuboidal epithelium 3. The fibrous wall generally contains nerves, arteries and veins. Additionally, minor salivary gland tissue and small islands of cartilage may be found. Finally, if the cyst was infected, acute and chronic inflammatory cells will be seen through out the specimen.

Treatment for a nasoplatine duct cyst is complete removal of the lesion, generally by palatal approach. Frequently the biopsy procedure results in adequate treatment. Recurrence is rare 1.

References :
  1. Meyer A.W.: A unique supernumerary paranasal sinus directly above the superior incisors. J. Anat. 1914, 48, 118–129.
  2. Terry B.R., Bolanos O.R.: A diagnostic case involving an incisive canal cyst. J. Endod. 1989, 11, 559–562.
  3. Francoli J.E., Marques N.A., Aytes L.B., Escoda C.G.: Nasopalatine duct cyst: Report of 22 cases and review of literature. Med. Oral Patol. Oral Cir. Bucal. 2008, 13, 438–443.
  4. Hegde R.J., Shetty R.: Nasopalatine duct cyst. J. Indian Soc. Pedod. Prev. Dent. 2006, 24, 31–32.
  5. Cicciu M., Grossi G.B., Borgonovo A., Santoro G., Pallotti F., Maiorana C.: Rare bilateral nasopalatine duct cysts: A Case Report. Open Dent. J. 2010, 4, 8–12.
  6. Panaś M.: Torbiele. In: Chirurgia szczękowo-twarzowa. Eds.: Bartkowski S.B., Collegium Medicum UJ Ages, Kraków 1996, 155–168,
More references are availabe on request.