Calcareous bodies found within maxillary sinus are considered as antral rhinoliths, antral stones and antral calculi, and the term ‘maxillary antrolith’. Bowerman stated the term of The maxillary antrolith to classify and explain from nasal stones in 1969. Antroliths consisted of mineral salt depositions around a central nidus in the maxillary sinus defined as pathological calcifications^1,2).

Antroliths are not a quite common occurrence and usually asymptomatic but, Rarely, clinical symptoms occur such as discharge and pain. However, most maxillary antroliths are discovered incidentally on radiographic examinations^3,4). Antroliths are frequently found in the inferior nasal meatus or between the inferior turbinate and the nasal septum^5,6).

The occurrence of antroliths in maxillary sinus is rare, ranging from 0.15% to 3.2%⁷⁾. As for treatment choices, the maxillary antroliths are usually left in the sinus or regular follow-ups are advised for the first choice of treatment²⁾. When the symptoms of irritation and sinus inflammation are accompanied, surgical removal can be involved for the treatment, especially if the implantation treatment is planned with sinus lift or sinus graft⁸⁾. Surgical operation of maxillary antroliths removal is endoscopic sinus surgery (ESS), Caldwell-Luc or a combination of both^1,5).

If the amount of bone in the maxillary posterior is insufficient for implantation treatment, sinus graft is usually performed. Although sinus graft is considered as an invasive surgery, a low incidence of surgical complications has been reported. Perforation of the maxillary sinus membrane is the most common surgical complication^9,10). Perforation occurs in 7 to 10% of the surgery, but has been reported to occur in as many as 35% of surgery^10,11). Many surgical techniques have been used to reduce complications during sinus graft surgery. Barone et al. reported the surgical access to osteotomy, and sinus membrane elevation by comparing using a piezoelectric device and conventional instruments during the maxillary sinus augmentation procedure. No significant differences were analyzed between two surgical techniques in any of the recorded clinical parameters¹²⁾.

In this case report, we report one successful sinus graft case of removing antrolith which was misdiagnosed as a tooth by approaching lateral window with a piezoelectric device. This paper was written under the approval of the Kyung Hee University Dental Hospital institutional Review Board.

A female patient was referred to department of Oral and Maxillofacial Surgery in Kyung Hee University Dental Hospital for the evaluation removal of tooth-like mass located in the left maxillary sinus before implantation treatment. Upon her arrival to our department without complaining any symptoms, the panoramic radiograph, periapical radiograph and cone beam computed tomography (CBCT) was performed to further evaluate the mass and confirmed 0.7×0.4 cm sized mass located in the posterior area of left maxillary sinus (Fig. 1∼3). With presumptive diagnosis as antrolith, it was decided that surgical removal and sinus graft under general anesthesia were the most appropriated treatment considering the pain management during the surgery.

Figure 1. Panoramic radiograph showing radiopaque lesion in the posterior area of left maxillary sinus.

Figure 2. Periapical radiograph showing foreign body within the left maxillary sinus approximating the distal root of the upper left molar.

Figure 3. Coronal view of patient’s Cone Beam Computed Tomo-graphy (CBCT) showing a well-defined radiopacity in maxillary sinus.

A horizontal vestibular incision was made on the left posterior area of the maxilla. The flap was fully elevated and the rectangular shaped bony window cut was performed using piezo-electric device. Right after the cortical bony window was removed, the maxillary sinus wall was detected. A hole of membrane was made on the sinus wall using the blade, the surgical exploration inside the sinus was begun and the antrolith was identified at the posterior part of the left sinus. Using Kelly and mosquito, the antrolith was carefully removed from the sinus and the size was 0.7×0.6×0.4 cm (Fig. 4).

Figure 4. The antrolith was removed from the sinus and the size was 0.7×0.6×0.4 cm.

With sinus elevation instruments, the sinus membrane was elevated and the deproteinized bovine bone mineral (Bio-Oss 0.25 g, Geistlich Pharma AG, Wolhusen, Switzerland) mixed with two Concentrated Growth Factor (CGF) was grafted. For repairing of sinus membrane perforation, a fibrin sealant (Tisseel 2 ml, Baxter Healthcare Corp, Deerfield, IL, USA) was applied on the perforation area. The removed bony window wall was put back, and the suture was performed with 4-0 dafilon to close up the incised mucosa of left maxilla (Fig. 5). The removed antrolith was sent for biopsy and the patient was recovered without complications. After six months postoperatively, a dental implant was successfully placed in the left second molar area (Fig. 6).

Figure 5. Post-operative Panoramic radiograph showing that the antrolith was removed and sinus graft in the posterior area of left maxillary sinus.

Figure 6. 6-month follow-up panoramic radiograph image showing successful dental implant placement and sinus graft.

The surgically excised specimen was measured 0.7×0.6×0.4 cm in size. The decalcified cut surface revealed pale gray hard fragment. the final diagnosis was mature trabecular bony tissue (Fig. 7).

Figure 7. Histopathologically, the lesion consists of Haversian Canals and osteocytes (hematoxylin-eosin stain; magnification ×200).

Postoperatively, any complications, including sinus infection, sensory disturbance and wound dehiscence were not noted. Recurrence was not observed during six months of follow-up. The bone level was well maintained at the graft site, and the implant was placed successfully six months after the operation.

Anatomic variations and lesions of the maxillary sinus were usually discovering in CBCT interpretations of the maxilla for dental implantation treatment. As some of theses conditions can modify dental implant treatment planning and must require specialized treatment practice.

The anatomic variations of the maxillary sinus were 83.2% of pneumatization, 44.4% of antral septa, and 2.6% of exostosis. The discovered lesions of the maxillary sinus were 54.8%∼62.6% of mucosal thickening, 3.8% of polypoid lesions bone thickening of the maxillary sinus wall, 3.2% of antroliths, 1.8% of sinus opacification, and 1.6% of foreign body¹³⁾.

Differential diagnosis of anthroliths should be considered with septa in the maxillary sinuses, the antral exostoses, foreign bodies and tooth. Foreign bodies and anthroliths located in the maxillary sinuses usually show a radiolucent border between the maxillary sinus floors. Septa located in the sinus floor are bony outgrowths, which are connecting with the sinus wall. Antral exostoses are shown by single or multiple small nodular masses of increased density within the maxillary sinus bound to the wall. Due to these characteristics, sinus wall with exostoses tends to have an appearance of diffuse, smooth remodeling and thickening on CBCT¹⁴⁾. Another common misdiagnosis of antrolith is a impacted tooth or tooth fragment. Impacted teeth or tooth fragments in the maxillary sinus are revealed on CBCT as a complex structure with multiple layers of enamel, dentin and pulp. So differential diagnosis of them can be performed easily with a existence of enamel on the high resolution radiographs such as CBCT¹⁵⁾.

When approaching the maxillary sinus, the lateral approach is more useful for securing the field of view than the crestal approach. Therefore, if the lateral approach is used, the damage to the surrounding structures will be less when removing foreign body and grafting bone in the maxillary sinus.

Approaching the maxillary sinus through lateral window opening procedure by using a piezoelectric device is less invasive without severe bone damage of the cortical wall of the sinus. Also, The window block bone remaining after piezosurgery can be reused. Vercellotti et al. reported the benefit of piezosurgery as being the ability to cut the cortical bone window opening with reducing the risk of membrane perforation. Moreover, piezoelectric elevators can then be used to lift the sinus membrane with avoiding risk of perforation^16,17). Therefore, the use of piezoelectric surgical technology can reduce the perforation rate of the membrane.

It is necessary to perforate the sinus membrane to remove antrolith because it is located inside the maxillary sinus membrane. There are several sinus membrane repair methods depending on the degree of membrane perforation. Fibrin sealant is useful when the size of membrane perforation is small. Sullivan et al. reported that the perforation membrane was successfully repaired using fibrin glue¹⁸⁾.

CGF has growth factors for bone healing. Kim et al. reported that CGF enables new bone formation during the early stage of bone graft healing¹⁹⁾. Therefore, the grafting with mixing bone materials and CGF is useful for bone formation.

Examining both radiopaque lesion and anatomic variation through CBCT and understanding both instruments operation and graft materials are crucial for a dental surgeon to perform successful operation of implant treatment.