Dental implant installation in upper posterior region, an accurate diagnosis and a better understanding of bone remodeling at the area may be more valuable for a optimum treatment planning. Currently, Cone-beam Computed Tomography (CBCT) is a common diagnostic tool which support three-dimensional (3D) images and thin detailed sections in order to asses relation between maxillary sinus floor and alveolar bone ridge. Although it reduces the overlapping of anatomical structures and enable a better assesment, still there is lack of studies using CBCT scans to analyze sinüs floor pneumatization in posterior maxilla. Additionally, to obtain correct knowledges of conventional panoramic evaluation is still curical for private clinics at the first stage of many health system of countries which dont use CBCT . The purpose of this study was to determine the amount of sinus pneumatization after extraction of maxillary teeth in the premolar and molar region which was associated with maxillary sinus via evaluation of panoramic views.
In spite of common blief, only a few studies describe the phenomenon of pneumatization of maxillary sinus [2,4,7–10]. Previous studies which were conducted by assesing via panoramic radiographs or repetetive radiographs, the potencial of differences in scales and/or mismatching which might arise from comparing two different panoramic radiographs which had differences associated with the machine, the software, and the patient’s position and posture .
Pachota et al. investigated the bone level changes in the molar region after extraction of premolar and molar teeth. The measurements were evaluated at panoramic views. The lines that pass through the sinus lower border that parallel to the Frankfurt parallel line and passes through the Spina nasalis anterior were taken as reference lines to measure the vertical changes of bone [11–13]. Spina nasalis anterior was also taken as a reference point by Yua-Hoa et al to measure the bone changes at maxillary sinus at panoramic views . Spina nasalis anterior is located at the midline of the maxilla. It is the least affected point with the different head positions and magnification in panoramic views. Spina nasalis anterior was taken as a reference point due to these aforementioned radiographic features.
Sharan et al. also investigated the relationship between teeth extraction and sinus pneumatization. Excessive sinus expansion was seen after the extraction of second molar teeth in their study . Previous studies also showed close proximity between the second molar root ends and maxillary sinus border. Extracting the second molar tooth can cause cortical bone fractures which are placed between root end and maxillary sinus. Thus, the extraction of the second maxillary molar tooth was considered to cause excessive sinus pneumatization [2,15,16]. In the presented study, a larger sinus pneumatization was observed after the first molar extraction. Also, widely sinus expansion was seen after 2nd molar extraction. In a study by Sharan et al., the larger sinus pneumatization was seen after the extraction of the teeth that elevated the sinus floor . These findings are similar to ours. Additionally, larger sinus expansions were seen after removal of the teeth that was related to periapical lesion. No statistical differences were observed with the removal of the teeth that directly associated with the maxillary sinus. These findings are consistent with the studies of Wehrbein and Deidrichs [2,4].Minimally 6 months are needed for the healing of tooth extraction socket. Post-extraction pneumatization occurs in the first 4 to 6 months before bone maturation. After 6 months sinus pneumatization is probably reduced .
Contrarily, our study shows precipitous sinus expansion in the first 6 months. Therefore, preprosthetic treatments like dental implant surgery should be achieved in the first 6 months after extractions at the molar region. Otherwise, additional procedures like sinus lifting and grafting might be needed.
Extensive sinus expansion was occurred in cases of extractions of more than one tooth in the same area. At multiple extraction sites, bone resistance is reduced and severe sinus pneumatization can be occurred . After extraction, adjacent teeth transport the occlusal forces to extraction socket. It was considered that this force transmission to alveolar bone reduces the amount of sinus expansion . This can be the reason why in our study after first upper molar extraction resulted in a larger sinus expansion than the 2nd upper molar extraction.
The immediate grafting of the extraction sockets using particulate bone grafts or bone substitutes with using a barrier membrane or tissue engineering procedures to keep the alveolar bone volume and height via osteoconductive or osteoinductive effect . Therefore, these methods could be prevent maxillary sinus pneumatization related posterior teeth extraction. Levi et al. suggested that sinus pneumatization following maxillary posterior tooth extraction could be reduced by socket preservation procedures . A systematic review by Van der Weijden and colleagues, reported a mean alveolar bone height change of 3–12 months post extraction without socket preservation. Alveolar bone preservation procedures can be effective to significantly decrease the vertical and horizontal alveolar bone dimensional changes .
There are a few limitations of the present study. One of these is the use of panoramic radiographs to measure changes in alveolar ridge and maxillary sinus dimensions. Although reference points were used to certainly superimpose the different radiographs, the use of cone-beam computerized tomography (CBCT) could verify sinus pneumatization changes. Secondly, the pneumatization associated with various factors except for tooth extraction in the maxillary posterior region. We evaluated only the correlation between teeth extraction and pneumatization with small sample size in the population. For the further studies including higher sample size and using CBCT should be conducted simultaneously evaluating different factors in order to confirm these findings.