Surgical Treatment of Odontogenic Maxillary Sinusitis

For many decades, the problem of odontogenic maxillary sinusitis (OMS) has been actively discussed among otolaryngologists, dentists, and maxillofacial surgeons. This is explained by the high prevalence of OMS: some authors believe that inflammation in the maxillary sinus (MS) has an odontogenic nature in 14-24% of cases (V.M.Uvarov, 1962; A.G.Shargorodsky, 1985). In recent years, a wealth of clinical experience has been accumulated, our knowledge of the normal and pathological physiology of the nose and paranasal sinuses (PNS) has significantly expanded, many treatment methods for this disease have been proposed, but the number of patients with OMS is not decreasing, and the treatment outcomes leave much to be desired.

When analyzing the causes of the prevalence of this pathology, the first reason mentioned is the unsatisfactory organization of dental care for the population and, as a consequence, the catastrophic increase in the number of cases of complicated forms of caries (A.G.Balabantsev et al., 2000). The second reason is the pneumatic type of structure (MS), which occurs in about 40% of people, where the roots of the upper jaw teeth are separated from the sinus cavity by a very thin bony wall or only by mucous membrane. Often, infection is introduced into the MS as a result of rough medical manipulations (S.M.Kompanee ts, 1949; G.A.Vasiliev, 1963; A.G.Shargorodsky, 1985; T.G.Robustova, 2000).

Unsatisfactory results are primarily due to the lack of a unified concept in the treatment of this disease. The question of the extent of intervention in maxillary sinusitis (MSS) today raises the main discussions, and the range of applied methods varies from the mandatory "radical" surgery on the maxillary sinus to a complete denial of the need for surgical intervention. Nevertheless, most surgeons believe that the necessary extent of surgery for MSS is wide opening of the affected sinus, removal of all mucous membrane, and creation of an anastomosis with the inferior nasal meatus.

To some extent, modern knowledge in the pathomorphology and pathophysiology of odontogenic inflammatory processes allows us to answer the question about the optimal extent of surgical intervention. Descriptions of changes in the maxillary sinus after the formation of its communication with the oral cavity can be found in publications from the early 20th century. Later, their nature was described in detail by V.A. Kozlov and co-authors (1982). The authors experimentally proved that in the presence of a perforation of the floor of the maxillary sinus, a reactive inflammatory process develops in the mucous membrane and surrounding bony structures, and they identified three phases of this process – alterative, productive, and fibrous. Like any experiment, these studies could not fully imitate the clinical picture, as the oroantral fistula (OAF) was created with healthy teeth and the absence of an inflammatory process in the maxillary sinus.

In real life, OAF often occurs against the background of an already existing OVC, as teeth are removed due to exacerbation of chronic or, less commonly, acute periodontal inflammation. This process is accompanied by the destruction of the thin bony wall that separates the apex of the root from the cavity of the maxillary sinus, which may be completely absent in cases of pronounced sinus pneumatization. This process is often local in nature, affecting the sinus only in the area of the alveolar recess, progresses sluggishly and asymptomatically, and therefore is not always diagnosed (A.V. Buskina, V.Kh. Gerber, 2000; A.M. Shevchenko et al., 2000; A.G. Balabantsev et al., 2000).

Less commonly, situations arise where a tooth must be removed due to pushing through the canal under the mucosa of the maxillary sinus or directly into its cavity a root filling material, a fragment of an endodontic instrument, etc. In all these cases, after perforation occurs, not acute but primarily chronic sinusitis develops, and it often has a fungal etiology (A.S. Lopatkin, 1999; H. Stammberger, 1991).

The presence of an inflammatory process in the maxillofacial region at the time of perforation sometimes leads to its late detection, as polyps and swollen mucous membranes can obstruct the canal from the sinus side, erasing clinical signs; in this case, the diagnosis is established only after the formation of a fistula. Experience shows that perforative maxillary sinusitis is not characterized by an acute course due to good drainage of exudate into the oral cavity, and sometimes into the nasal cavity (V.V. Luzina, O.E. Manuilov, 1995; N.D. Tsepilova et al., 1998; A.G. Balabantsev et al., 2000; T.G. Robustova, 2000; F.A. Tyshko et al., 2000). The perforative opening gradually narrows due to the growth of granulation tissue, its walls become epithelialized, and a fistula is formed, through which liquid and food enter the sinus, maintaining chronic inflammation of the mucous membrane.

The process is more active in the presence of a foreign body in the maxillofacial region (tooth root, filling material, tampon, etc.). Such patients are troubled by constant purulent discharge from the fistula and one side of the nose, with periodic exacerbations showing a clear clinical picture of sinusitis. Changes in the sinus are more diffuse in nature, with a predominance of proliferative or destructive components, i.e., the development of polypous changes or necrosis of the mucous membrane and destruction of the underlying bone.

Another important factor influencing the clinical manifestations of OAC is the size and patency of the natural ostium of the maxillary sinus. Modern concepts place this factor at the forefront of the pathogenesis of sinusitis. With normal drainage of the sinus contents and adequate aeration, the inflammatory process (including odontogenic) proceeds significantly more easily and has a greater tendency for healing.

Thus, from the perspectives of pathomorphology and pathophysiology, the optimal treatment strategy for OAC, whether perforated or non-perforated, should involve the removal of pathological contents from the affected sinus (polyps, granulations, fungal masses, foreign bodies) and the restoration of its normal drainage and aeration through the natural opening in the middle nasal meatus. In the presence of OAF, it should be closed plastically in a single stage, and the oroantral communication should be eliminated in the absence of an active inflammatory process: in the case of perforation of the floor of an intact sinus - within 1-2 days or 1-2 weeks after its formation, and in the case of perforation against the background of chronic sinusitis - during remission, after a course of anti-inflammatory treatment.
In the literature, one can find almost three dozen original methods for closing OAF. Essentially, they can be divided into 4 groups: isolation of the perforation from the oral cavity in the hope of spontaneous healing, plastic surgery with artificial materials, plastic surgery with soft tissue flaps, and a combination of flap operations with filling using artificial materials. Proponents of the first method (V.I. Lukyanenko, 1976; Yu.I. Bernadsky, 2000) believe that the isolation method is indicated for acute perforation (up to 48 hours). For this purpose, a iodoform tampon is used, fixed with ligatures to adjacent teeth, or a plastic protective plate. This measure prevents the evacuation of the blood clot from the socket, promotes its organization, and replacement with connective tissue.

Plastic surgery with artificial materials is used to close both acute perforations and OAF (A.I. Bogatov, 1991 et al.). For this purpose, oxicellulose, hemostatic sponge, collagen-based preparations, hydroxyapatite, demineralized bone matrix, etc. have been used. The appealing advantage of the method is its simplicity, but the long-term results of such treatment and the fate of the implanted materials remain unstudied. Data from experimental studies on the transplantation of these materials into bone or soft tissues, which are the main argument of the method's proponents, cannot be directly transferred to real life, as in actual clinical conditions the material is not fully immersed in the tissues, but interacts with the environment of the oral cavity and the maxillofacial region.

The main method for closing OAF today remains the movement of tissue flaps. Local tissues are considered the optimal material for plastic surgery. Most often, a sliding mucoperiosteal flap from the vestibular surface of the alveolar ridge and cheek is used. It is viable and convenient from a technical point of view. The only serious drawback is the scar deformation of the vestibule of the oral cavity, which, in particular, creates problems for subsequent dental prosthetics.

The palatal flap also differs in good viability (V.A. Sukachev et al., 1996; M.Yu. Petropavlovskaya, 1999), but it bleeds profusely, rotates poorly due to its rigidity, and requires dissection of the feeding vessels, while the donor wound heals by secondary intention. Due to these drawbacks, clinicians rarely and reluctantly use palatal flaps. Overall, the percentage of successful outcomes in the plastic closure of OAF undoubtedly depends on the surgeon's experience and the method used, and according to several foreign authors, it does not exceed 60-70% (H.R. Haanaes, K.W. Pedersen, 1974; W.Y. Yih et al., 1988; J.L. Gluckman, 1995).

Among the methods of surgical sanitation of the maxillofacial region in OVC today, the so-called "radical" operation, developed more than a century ago, remains the most widely used method, although its traumatic nature, non-physiological aspects, and undesirable consequences are well known, and the complication rate, which includes mentions of recurrences of sinusitis, anesthesia of the upper lip, gums, and teeth, trigeminal neuralgia, loosening of teeth, scarring deformation of the tissues in the infraorbital area, tearing, and even osteomyelitis of the maxilla and zygomatic bone, reaches 80% (M.M. Solovyev et al., 1974; V.V. Luzina, O.E. Manuilov, 1995; V.A. Sukachev et al., 1996). The extensive bone defect formed in the anterior wall of the sinus, the formation of an unnatural communication with the inferior nasal meatus with complete disregard for the condition of the natural opening, frequent trauma to the nasolacrimal duct and infraorbital nerve – these are not all, but the main drawbacks of the classical Caldwell-Luc operation. Various modifications of this operation, which reduce its traumatic nature and complication rate, such as the technique by V.A. Nikitin (1950), are traditionally used only for the treatment of rhinogenic, but not odontogenic inflammation of the maxillofacial region.

Another possible approach to the sanitation of the maxillary sinus in cases of acute maxillary sinusitis is access through the oral antral fistula, if present. Historically, access through the tooth socket is the oldest method; it was first proposed in the mid-17th century (J.Wright, 1989) and was widely used, particularly by domestic surgeons (S.F.von Stein, 1903). This method is less traumatic compared to the classical "radical" surgery, but it has not gained widespread acceptance due to the inability to visually control the procedure and the inconvenience of manipulations in the sinus. Attempts have been made to sanitize the maxillary sinus without visual control by performing apodactyl curettage of the alveolar cavity and extracting foreign bodies with gauze and tampons with glue (A.I.Bogatov, 1991; V.V.Luzina, O.E.Manuilov, 1995, et al.). To improve visual control, it was suggested to enlarge the existing perforation (G.V.Kruchinsky, V.V.Filippenko, 1994), but even with a diameter of 1.5-2 cm, the sinus is not fully accessible for observation, and increasing the bone defect to such sizes significantly reduces the likelihood of successful plastic closure.
All of this has sparked interest in the use of endoscopic techniques, which could elevate the surgery on the maxillary sinus to a fundamentally new level, allowing for an objective determination of the necessary volume of intervention without additional trauma and enabling a revision of the sinus. The first reports of the use of bronchoscopy and cystoscopy in the treatment of acute maxillary sinusitis appeared in the literature (A.I.Bogatov, 1991), but the imperfection of the equipment and instruments used largely negated the advantages of the method.

Endoscopic surgery of the upper respiratory tract has gained widespread popularity with the advent of rigid endoscopes. Optics with viewing angles of 0(, 30(, and 70( have made it possible to examine all sections of the upper respiratory tract, restore the patency of its natural openings, and remove polyps and cysts without resorting to sinus opening through the anterior wall (D.W.Kennedy, 1985; H.Stammberger, 1991). The method, based on the concept of W.Messerklinger, which asserts that any sinusitis, even those with initially odontogenic or traumatic etiology, can be cured through minimally invasive interventions that restore normal aeration and drainage of the affected sinus, has rapidly gained immense popularity worldwide. However, there are only a few publications dedicated to the application of this surgical concept in the treatment of chronic rhinosinusitis (T.Romo III, J.Goldberg, 1991). The use of endoscopic technologies allows for the simultaneous use of two accesses (through perforation and the middle nasal passage), which opens up enormous new possibilities in the surgical treatment of chronic rhinosinusitis. The study of the effectiveness of this new method became the goal of the present research.

Materials and Methods

Endoscopic surgical intervention methods were used on 70 patients with perforated and non-perforated forms of maxillary sinusitis aged from 16 to 62 years, who were treated in our departments from 1997 to 2000. To establish the diagnosis and clarify the nature of the disease, in addition to standard methods of examining the oral and nasal cavities, radiography in the naso-mental projection, panoramic tomography, computed tomography, and endoscopic examination of the nasal cavity were used. An oroantral fistula was identified in 36 patients, with the most common localization of the fistula (26 cases) being the socket of the first molar. In 21 patients, foreign bodies were found in the maxillary sinus, with 11 of them having tooth roots, 7 having pieces of filling material, and 3 having gauze tampons. An odontogenic cyst was diagnosed in 10 patients, fungal infection of the maxillary sinus in 6, and 7 patients had previously undergone surgery on the maxillary sinus using the Caldwell-Luc technique.
In this group of patients, gentle surgical techniques on the maxillary sinus were used, which were performed under intubation anesthesia. The intervention began with endoscopic revision of the natural opening of the maxillary sinus in the middle nasal meatus. For this, careful luxation of the middle nasal concha was performed medially under the control of a rigid endoscope, followed by retrograde resection of the lower parts of the uncinate process, opening and removing the walls of the ethmoid bulla, and visualizing the natural ostium of the sinus, which was maximally expanded posteriorly. After that, the sinus lumen was examined with 30º and 70º endoscopes. Pathological contents of the sinus were removed with a suction tip, and polyps from the upper and medial parts of the sinus were removed with 80º curved Binner forceps and an aggressive straight or 20º curved tip of the "Hummer 2" microdebrider from "Stryker" (USA), which were introduced through the expanded natural opening of the sinus. It should be noted that in all cases we managed to remove foreign bodies located in the sinus lumen – pieces of filling material and tampons – through the endonasal approach.

In the presence of OAF, there is a need for a thorough revision of the alveolar cavity, which is usually poorly accessible for manipulation through the middle nasal passage. In this case, we used access through the fistula opening (if present), passing the microdebrider tip through it and removing polyps from the alveolar cavity under visual control through an endoscope inserted into the enlarged natural opening of the sinus. At the same time, the microdebrider was used to remove the epithelial lining of the fistula, preparing it for subsequent plastic closure. With a significantly developed, protruding and medial alveolar cavity, controlling the thoroughness of its revision without opening the sinus through the anterior wall is considerably more difficult; however, the use of 30º and 70º endoscopes inserted through the enlarged ostium in the middle nasal passage still allowed this to be done under visual control.

We always performed the sanitation of the maxillary sinus and the elimination of the oroantral communication simultaneously. The fistula was closed in two layers: first, a circumferential incision was made around the fistula, and the small de-epithelialized flaps formed at its edges were sutured together, and then a typical mucoperiosteal flap from the vestibular surface of the alveolar ridge (31) was used for the plastic closure, less frequently a palatal flap (in 5 patients).

In the postoperative period, antibacterial therapy was conducted, and patients were discharged from the department on the 4th-5th day under observation at the clinic. Subsequently, they independently performed rinses of the nasal cavity with warm saline solution and gargled the oral cavity with antiseptic solutions.

Results and Discussion

The use of a combined approach allowed for a revision of the maxillary sinus with minimal trauma, creating conditions for a smoother postoperative period. Swelling of the soft tissues of the cheek caused by the transfer of the mucoperiosteal flap, difficulty in nasal breathing, and pain sensations were significantly less pronounced than after the Caldwell-Luc operation and resolved more quickly.

In the overwhelming majority of cases, we managed to achieve sanitation of the sinus and healing of the OAF. With observation periods ranging from 1 year to 3 years, a recurrence of OAF was noted in 3 operated patients, 2 of whom had previously undergone surgery using the classical method. Another patient developed a recurrence of the inflammatory process in the maxillary sinus, which was caused by stenosis of the created ostium and required reoperation. Thus, the overall recurrence rate in this series was 5.7%. None of the operated patients in this group experienced neuralgia of the branches of the trigeminal nerve during the observation period.

Only in one case did we have to resort to wide opening of the maxillary sinus through the anterior wall and removal of the entire mucous membrane in a patient with a large odontogenic cyst, which had dense ossified walls and partially destroyed the bony walls of the sinus. However, even in this case, we managed without creating an anastomosis with the inferior nasal meatus, expanding the natural opening of the sinus to the necessary size.

The most serious problems arose when treating patients who had previously undergone radical surgery. Anti-inflammatory therapy in the preoperative period was not very effective for them, and it was not always possible to achieve even a temporary cessation of purulent discharge. During the operation, the sinus was filled with pus, granulations, and polyps, the normal mucous membrane was absent, and the lumen of the sinus was reduced due to scar-hyperplastic changes in the mucous membrane, sometimes down to 1.5 cm³. The natural ostium of the maxillary sinus was usually deformed, ectopic, and covered with polyps, while the ostium with the inferior nasal meatus was completely closed by a scar membrane. Surgeries in this group of patients were usually accompanied by increased tissue bleeding. All of this created maximum difficulties for endoscopic surgery.
Difficulties also arose when eliminating the oroantral fistula after previous unsuccessful surgeries, when there was a severe scar deformation of the tissues in the vestibule of the oral cavity. It was in such cases that we resorted to palatal flap plastic surgery.

The results we obtained clearly demonstrated the advantages of the endoscopic method. After radical surgery, there was a prolonged swelling of the tissues in the infraorbital area, pain, serous-hemorrhagic discharge from the sinus, anesthesia of the upper lip, teeth, gums on the side of the operation, etc. Subsequent monitoring of the patients showed that complete recovery of sensitivity does not occur, and there are periodic pains or other unpleasant sensations in the area of the operated jaw, discharge from the nose, and swelling of the tissues in the infraorbital area. A recurrence of the oroantral fistula is observed in 30-40% of patients.

Completely different results were observed after endoscopic surgical treatment. The postoperative swelling caused by the transfer of the mucoperiosteal flap was mild and quickly resolved. In patients who underwent the procedure only through the oroantral communication, signs of surgical trauma were practically absent, while in patients who also underwent endonasal intervention, episodic nasal bleeding and nasal congestion were observed in the first 2-6 days. A recurrence of the oroantral fistula was recorded in 3 patients, 2 of whom were from the group previously operated on by the radical method. This group of patients deserves more detailed attention.
As already mentioned, endoscopic interventions in these patients face significant technical difficulties, and the very principles of endoscopic surgery are not applicable. In such cases, it is more appropriate to proceed with radical reoperation, and its purpose should not only be the removal of polyps and granulations, the elimination of oroantral communication, and the restoration of the antrochoanal communication, but also the re-epithelialization of the sinus. It is precisely re-epithelialization that will help avoid sinusitis. Steps are already being taken in this direction, and some authors propose specific methods for restoring the epithelial lining of the sinus (A.P. Loboty, 1998). Furthermore, this group of patients clearly demonstrates the shortcomings of radical sinus surgery and indirectly indicates the need for primary endoscopic sinus surgery.

The length of stay for patients in the hospital after endoscopic surgery did not exceed 5 days. Further treatment was conducted in an outpatient clinic and took about another week.

Thus, our clinical experience fully confirms the correctness of the principles of functional surgery of the maxillary sinus. The prospects of this direction are beyond doubt, and it will be fundamental in the treatment of sinusitis in the near future. Today, there is also a clear need for further development of the technological basis, namely endoscopic techniques and specialized instruments. Nevertheless, even today, physiological endoscopic surgery should receive greater clinical dissemination, displacing outdated traumatic technologies.

The results we obtained clearly demonstrated the advantages of the endoscopic method.

The postoperative period in patients treated with the endoscopic method was significantly easier than after radical surgeries. The swelling caused by the transfer of the mucoperiosteal flap was mild and quickly resolved. In patients where the intervention was performed only through the oroantral fistula, signs of surgical trauma were practically absent, while in patients who also underwent endonasal intervention, episodic nasal bleeding and nasal congestion were observed in the first 2-6 days. No patient experienced sensory disturbances, tearing, prolonged swelling and exudation, pain, or other negative consequences typical of radical surgeries; moreover, the percentage of recurrences of oroantral fistula significantly decreased (5.7%). Complications were mainly observed in the treatment of patients previously operated on by radical methods.

List of References.

1. Balabantsev A.G., Bogdanov V.V., Goncharuk V.P., Krasnikov V.A., Logosyuk A.V. Differentiated approach to the treatment of patients with odontogenic maxillary sinusitis // Journal of Ear, Nose, and Throat Diseases. – 2000. - No.2. – P.121-124.
2. Bernadsky Yu.I. Fundamentals of maxillofacial surgery and surgical dentistry. Vitebsk: Belmedkniga, 1998. - 416 p.
3. Bogatov A.I. New methods of diagnosis, treatment, and rehabilitation of patients with perforations and foreign bodies of the maxillary sinuses // Author's abstract of the dissertation ... candidate of medical sciences. – Samara. – 1991 – 18 p.
4. Buskina A.V., Gerber V.H. On the clinical classification of chronic odontogenic maxillary sinusitis // Bulletin of Otorhinolaryngology. – 2000. - No.2. – P.20-22.
5. Vasiliev G.A. Surgery of teeth and oral cavity. M.: Medgiz. – 1963. – 427 p.
6. Kozlov V.A., Troshkova G.B., Kochubey N.M., Nekachalov V.V. Dynamics of morphological changes in the tissues of the maxillary sinus in experimental perforative sinusitis // Dentistry. – 1982. - No. 2. – P. 49 – 52.
7. Kruchinsky G.V., Filippenko V.I. Plastic surgery of the anterior wall of the maxillary sinus after sinusotomy with a complex autotransplant // Dentistry. – 1994. - No.2. – P.88 – 89.
8. Kompanee ts S.M. Diseases of the nose and paranasal sinuses. Kyiv.: Gosmedizdat. – 1949. – 452 p.
9. Lobaty A.P. New technologies for surgical treatment of zygomatic complex injuries: Author's abstract of the dissertation ... candidate of medical sciences. – Novosibirsk. – 1998 – 21 p.
10. Lopat in A.S. Fungal diseases of the paranasal sinuses // Russian Rhinology. – 1999. - No. 1. – P. 46 – 48.
11. Luzina V.V., Manuilov O.E. Analysis of long-term results of treatment of patients with odontogenic perforative maxillary sinusitis // Dentistry. – 1995. - No. 1. – P.41 – 42.
12. Lukyanenko V.I. Emergency dental care. M., 1976. – 144 p.
13. Nikitin V.A. Our variant of surgery on the maxillary sinus. – Dissertation ... candidate of medical sciences. – Dagestan, 1950. – 283 p.
14. Petropavlovskaya M.Yu. Use of a mucoperiosteal palatal flap on a vascular pedicle for eliminating oroantral communication and compensating for defects after tumor removal // Author's abstract of the dissertation candidate of medical sciences. – St. Petersburg – 1999. – 18 p.
15. Robustova T.G. Odontogenic inflammation of the maxillary sinus // Guide to surgical dentistry and maxillofacial surgery: ed. Bezrukov V.M., Robustova T.G.: in 2 volumes. – Vol.1. M.: Medicine. – 2000. - P.312-326.
16. Solovyev M.M., Shimchenko P.Ya., Yakovleva N.A. Long-term results of surgical treatment of odontogenic maxillary sinusitis // Dentistry. - 1974. - No.2. - P.75.
17. Sukachev V.A., Kozlov Yu.I., Kulakov A.A. Treatment of perforations and fistulas of the maxillary sinus // Methodical recommendations. Strategic missile forces. - 1996. – 36 p.
18. Tishko F.A., Dyadchenko O.P., Tishko D.F., Khrypalo A.V. Surgical treatment of orosinomaxillary fistulas complicated by odontogenic maxillary sinusitis // Journal of Ear, Nose, and Throat Diseases. – 2000. - No.2. – P.124-125.
19. Uvarov V.M. Odontogenic maxillary sinusitis. L.: Medicine. – 1962. – 461 p.
20. Tsypilova N.D., Fazlynurova D.M., Baymukhametova D.V. Choice of treatment tactics for odontogenic maxillary sinusitis // Materials of the first congress of maxillofacial surgeons of the Republic of Bashkortostan "Theoretical and clinical issues of maxillofacial surgery", dedicated to the 25th anniversary of the maxillofacial surgery department and the republican maxillofacial center. – Ufa. – 1998. – P.48 – 49.
21. Shargorodsky A.G. Inflammatory diseases of the maxillofacial region and neck. M.: Medicine. – 1985. – 352 p.
22. Shevchenko A.M., Goldfarb G.L., Shevchenko S.A. Some aspects of inflammatory maxillary sinusitis of odontogenic genesis // Journal of Ear, Nose, and Throat Diseases. – 2000. - No.2. – P.64-65.
23. von Stein S.F. On the technique of opening the maxillary sinus // Proceedings of the clinic of diseases of the ear, throat, and nose of the Imperial Moscow University named after Yu.I. Bazanova. - M., 1903. - P.457-482.
24. Gluckman J.L. Oroantral fistula // The sinuses / Ed. P.J. Donald, J.L. Gluckman, H.L. Rice. – NY: Raven Press, 1995. – P.599-606.
25. Haanaes H.R., Pedersen K.W. Treatment of oroantral communication // Int. J. Oral Surg. – 1974. – Vol.2. – P.124.
26. Kennedy D.W. Functional endoscopic sinus surgery: Technique // Arch. Otolaryngol. Head Neck Surg. – 1985. - Vol.111, N10. - P.643-649.
27. Romo III T., Goldberg J. Functional endoscopic sinus surgery to manage chronic oral antral fistula // Operative Techniques in Otolaryngology - Head and Neck Surgery. - 1991. - Vol.2, N4. - P.247-256.
28. Stammberger H. Functional endoscopic sinus surgery: The Messerklinger technique. – Philadelphia: B.C. Decker. – 1991.
29. Wright J. The nose and throat in medical history. – St. Louis: LS Mattheus & Co, 1898.
30. Yih W.Y., Merril R., Howerton D. Secondary closure of oroantral and oronasal fistulas // J. Oral Maxillofac. Surg. – 1988. – Vol.46. – P.357-364.