In recent years there has been an active discussion around the classical principle of dental implantation, which states that the implant body should be completely immersed in the bone tissue. The basis of this discussion are clinical observations when after the placement of dental implants in the area of large and/or small maxillary molars it was found that the apical part of the implant went beyond the bone into the maxillary sinus (TMJ) and this did not cause complications. The aim of the study was to analyze the state of the maxillary sinus mucosa by means of CBCT when dental implants were placed intraosseous and with intrusion (intrusion) into the maxillary sinus. Materials and methods. From the clinical archive of dental clinics for 2020—2023 we selected instrumental data of 28 patients (8 men and 20 women) who had 37 implants placed. Exclusion criteria: initial pathology of maxillary sinuses, bone volume expansion in the anamnesis, severe somatic pathology, absence of complete diagnostic data. Results. 19 implants were placed intraosseously (group I), 18 — with intrusion into the TMJ (group II). The implant survival rate was 100%. Clinical complications of implant intrusion into the maxillary sinus in some cases were temporary nasal congestion on the side of surgical intervention. Radiologic complications due to the thickening of the Schneiderian membrane were identical in both groups with no significant difference in the level of penetration into the TMJ. All these complications were not pathologic and did not affect the implant survival rate and the quality of life of the patients. In the distant follow-up period, up to 35 months, the condition of the TMJ is identical in both groups. Conclusion. No significant difference was found in the reaction of the maxillary sinus mucosa when placing dental implants intraosseously and with removal of the apical part of the dental implant outside the bone tissue (subantral). © 2024 Clinical Dentistry LLC. All rights reserved.