Clinical context and differential diagnosis

In the face of unilateral maxillary sinusitis refractory to conventional antibiotic therapies, an odontogenic etiology must imperatively be explored. This case report presents a 24-year-old patient suffering from purulent rhinorrhea and recurrent facial edema for two years, symptoms initially attributed to chronic infectious rhinosinusitis. The clinical absence of the right maxillary third molar constitutes a major warning sign here, often overlooked in the initial care pathway, leading to a prolonged diagnostic delay.

Objectives and clinical hypothesis

The objective of this study is to document the comprehensive management of an ectopic tooth impacted within the maxillary sinus, associated with a voluminous cystic lesion. The authors illustrate the decisive contribution of Cone Beam Computed Tomography (CBCT) in precisely locating the dental organ in three dimensions and planning the surgical excision via an intra-oral approach. The diagnostic hypothesis was based on an odontogenic origin — dentigerous cyst or keratocyst — suspected due to an intrasinus dental opacity identified on panoramic examination. This case highlights the necessity of early radiographic evaluation in the presence of eruption disorders to effectively prevent or treat these chronic sinus complications.

Clinical case methodology

This case report describes the management of a 24-year-old female patient presenting with symptoms of persistent unilateral chronic sinusitis for two years (purulent rhinorrhea and recurrent facial edema), refractory to conventional antibiotic therapies.

• Diagnostic evaluation: The clinical absence of the right maxillary third molar prompted an initial radiographic exploration via dental panoramic X-ray. The diagnosis was refined by Cone Beam Computed Tomography (CBCT) to assess in three dimensions the position of the ectopic tooth relative to the sinus walls and the extent of the cystic lesion.
• Surgical protocol: The procedure was performed under general anesthesia with nasotracheal intubation. Surgical access consisted of a mucoperiosteal flap via a vestibular incision from the first premolar to the molar area. A rectangular bone window was created on the anterior sinus wall using a piezo-surgery insert.
• Treatment and analysis: The cystic lesion was enucleated, followed by the avulsion of the ectopic tooth. Given the intraoperative suspicion of an odontogenic keratocyst (presence of keratinized debris), chemical cauterization of the residual cavity was performed using Carnoy's solution. The excised tissues were submitted for histopathological examination for diagnostic confirmation.
• Follow-up: Healing and sinus pneumatization were monitored by CBCT at 3 months and 6 months postoperatively.

Clinical results and observations

The diagnosis and management of this 24-year-old patient, suffering from unilateral purulent rhinorrhea and recurrent facial edema for 2 years, identified a complex odontogenic pathology within the right maxillary sinus.

Parameter	Clinical Observations and Imaging
Clinical examination	Absence of the right maxillary third molar (18); sensitivity to palpation.
Imaging (CBCT)	Fully formed ectopic third molar in the sinus; roots close to the medial wall; cystic lesion occupying the floor and the anterior/posterior walls.
Intraoperative findings	Presence of white keratinized debris and inflammatory secretions.
3-month follow-up (CBCT)	Complete aeration of the right maxillary sinus; absence of cystic recurrence or dental residue.

Histopathological analysis

The histopathological examination was decisive in ruling out the initial hypothesis of an inflammatory dentigerous cyst in favour of an odontogenic keratocyst (OKC). The histological sections revealed:

• A keratinized stratified squamous epithelium lining the cystic wall.
• A basal cell layer composed of columnar cells with a characteristic palisade arrangement.
• The absence of signs of malignancy, confirming the benign but aggressive nature of the lesion.

Surgical outcome and follow-up

Complete intra-oral excision, assisted by piezosurgery for the creation of the bone window and supplemented by chemical cauterization (Carnoy's solution), led to total symptomatic resolution. At 6 months postoperatively, the CBCT confirms normal sinus pneumatization. The patient reports complete eradication of symptoms and a significant improvement in her quality of life, with no neurological or infectious complications noted after the procedure.

A two-year diagnostic odyssey: the trap of unilateral sinusitis

This clinical case reports the history of a 24-year-old female patient suffering from purulent rhinorrhea and recurrent facial swelling on the right side for two years. Despite multiple courses of antibiotic therapy, symptoms persisted, illustrating the frequent risk of confusion between inflammatory sinus pathology and an odontogenic origin. Clinical examination revealed a key clue: the absence of the right maxillary third molar (18), finally directing towards a targeted radiographic investigation.

CBCT: the essential tool for surgical planning

If the panoramic radiograph suggested a tooth-density shadow within the sinus, Cone Beam Computed Tomography (CBCT) was decisive. It confirmed the presence of a fully formed tooth 18, with its crown projecting into the sinus cavity while the roots bordered the medial sinus wall. Imaging also revealed an expansive cystic lesion occupying the sinus floor and walls. According to the authors, this anatomical precision is essential for differentiating classic dentigerous cysts from more aggressive odontogenic keratocysts (OKC).

Surgical approach and histopathological diagnosis

L'intervention, menée sous anesthésie générale par voie intra-orale, a utilisé la piézochirurgie pour créer une fenêtre osseuse sur la paroi antérieure du sinus. L'énucléation complète du kyste et l'extraction de la dent ectopique ont été réalisées. En raison de la suspicion peropératoire de KCO (présence de débris kératinisés blanchâtres), une cautérisation chimique à l'aide de la solution de Carnoy a été appliquée dans la cavité. L'examen histopathologique a confirmé le diagnostic de kératocyste odontogène, caractérisé par un épithélium malpighien kératinisé avec une couche basale palissadique.

Analysis of results and limitations

At 6 months postoperatively, the patient showed complete resolution of symptoms and good pneumatization of the maxillary sinus confirmed by CBCT. This study demonstrates the effectiveness of a purely intra-oral approach, unlike other techniques combining endoscopy and open surgery cited in the literature. However, the 6-month follow-up constitutes the major limitation of this case report, as the odontogenic keratocyst is known for its potential for late recurrence, normally requiring follow-up over several years.

Summary of results

This clinical case reports the intra-oral surgical excision of an ectopic third molar associated with an odontogenic keratocyst in a 24-year-old female patient. After two years of unilateral sinus symptoms refractory to antibiotics, the intervention — including piezoelectric osteotomy and the application of Carnoy's solution — resulted in complete clinical resolution and normal sinus pneumatization confirmed by CBCT at 6 months.

In concrete terms, for the practitioner:

• Diagnostic reflex: Faced with chronic unilateral sinusitis resistant to medical treatments, systematically check the dental formula; the absence of a tooth on the arch should lead to suspicion of sinus ectopia.
• Imaging Precision: Prioritize CBCT over panoramic radiography to precisely locate the tooth, evaluate its relationship with the sinus walls, and differentiate the tissue characteristics of the associated cystic lesion.
• Management of recurrence risk: In case of suspected odontogenic keratocyst during enucleation, the use of chemical adjuvants (Carnoy's solution) is recommended to reduce the high recurrence rate specific to this pathology.

Unilateral sinusitis that resists conventional treatments for two years must imperatively alert the clinician to a possible odontogenic etiology. This documented clinical case highlights the journey of a 24-year-old patient whose symptoms, masked by apparent infectious rhinosinusitis, actually concealed an ectopic third molar associated with an odontogenic keratocyst.

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