Alveolar antral artery: cone beam computed tomography study and clinical context

Design

This is an observation study.

Settings

The study protocol was reviewed and approved by the Ethics Committee of the Faculty of Medicine and Dentistry, Palacky University Olomouc Ref. No. 81/22. The informed consent of using radiographs and photos of the patients for scientifical and research purposes is routinely signed in the Institute of Dentistry and Oral Science Palacky University and was provided to the journal Editorial office.

Exclusion criteria:

1. Invalid CBCT scan or CBCT scans which does not include any maxillary sinus.

2. The CBCT scans imaging only one maxillary sinus was included, but excluded from analysis of bilateral presence of intrabony AAA. If one person had multiple CBCT scans the more aimed for sinus maxillaries was chosen.

3. Presence of maxillary sinus pathology such as cyst or pseudocyst which does not allow further measurement.

4. Grafted alveolar sinus.

The 251 CBCT scan was evaluated. 103 CBCT scans was excluded for inadequate imaging (60), artefacts (40), pathology (three), if the sinus was grafted, the preoperative CBCT scans were found and used.

The 148 valid CBCT scans of patients from university hospital databases was examined. The CBCT scans was done for different reasons such as implant therapy planning or advanced diagnostics.

The data of the patients was obtained (gender, age). The quality of CBCT scans was verified. The possibility of bilateral examination of maxillary sinus was ensured. If not, this was noticed. Presence and bilateral presence were examined. The distance between AAA and sinus floor was measured in mm in first premolar (P1), second premolar (P2), first molar (M1) and second molar (M2) region was measured. Figure 10 illustrates the methodology for measuring the distance between the sinus maxillaris and the AAA.

The high and width of bony canal was measured. Width of sinus wall in M1 region was measured to study the relation of sinus wall width and bony canal diameter.

The distance of AAA from the level of hard palate was measured in M1, P2 and P1. (Notice no M2). Missing teeth were noticed.

The sinus type (wide, average, and narrow) was measured. Classification of sinus in width was based on Chan et al. (2014). The sinus width at lower boundary (2.3 mm from sinus floor) was measured. If the sinus width was smaller than 8 mm, the sinus was classified as narrow, the diameter from 8 to 10 mm was classified as average. A sinus wider than 10 mm was classified as wide (Chan et al., 2014; Whyte & Boeddinghaus, 2019). Figure 11 shows the measurement of the cavity type according to Chan et al. (2014).

Bifid and trifid branches of AAA were found in more cases. However, no statistics were kept on the incidence of bifid or trifid AAAs and the most caudal branch, closest to the alveolar process and thus with the greatest significance for sinus lift, was always used for measurement. Figure 12 demonstrates the measurement of the distance of AAA from the plane of the hard palate.

Study design

During the design of the study authors decided use retrospective data and not to use diagnostic methods which are not indicated from another medical reason. This is cost consuming and patient should be avoided of unnecessary ct scanning. Authors decided not to use MRI for study for high presence of artefacts caused by dental materials.

As possibility the authors considered Ct angiography, which is indicated for stroke diagnosis. However, the contrast material applied intra venosus does not shows AAA as the diagnostic method is indicated for brain vessels with higher diameter. Figure 13 demonstrates the low sensitivity of CT angiography in the splanchnocranium.

As dental clinicians use CBCT for routine diagnostics before implant placement, the authors use the same diagnostic method to evaluate presence and characteristics of AAA.

Results

In our study, 0.9 mm was found as average diameter of the AAA. This correlate with other studies. For example, Güncü et al. (2011) found mean diameter of AAA was as 1.3 ± 0.5 mm.

In our study, 57% of the measured CBCT scans contained AAA. We found the bilateral presence in 43%. This is needed in order to compare with other teams work where AAA was present in 88.5% of the assessed maxillary sinuses and bilateral visualization was predominant 77% (P < 0.0001). The mean vertical distance from the most anterior part of the AAA to the sinus floor was 7.9 ± 6 mm in female patients (both sides) and 12 ± 7.22 mm on the right side and 10.9 ± 6.86 mm on the left side in males, where they had maximum. The mean diameter of the AAA was 1.2 ± 0.7 mm on both sides in females. In males, the diameter was significantly (P < 0.05) larger: 1.5 ± 0.62 mm on the right side and 1.4 ± 0.69 on the left side in females (Albuquerque et al., 2021). This agrees with our study, as also confirmed by the higher width of the AAA in male group.

In our study was found higher distance between sinus floor and AAA in edentulous patients p = 0.793 than patients with teeth present p = 0.067. However, the same distance (in both edentulous or non-edentulous patients) was found at the hard palate level. Hypothesis can be done that dental roots or periodontal ligaments are protective for the alveolar ridge and after the tooth loss, the alveolar ridge becomes pneumatized. The significance of this finding contributes to a better understanding of maxillary sinus development. Clinically, after tooth loss (but not necessarily with respect to anatomical variability), maxillary sinus surgery may be more compromised by AAA bleeding than maxillary sinus surgery in a patient with teeth still present.

Presence of the bony canal in the lateral wall of maxillae showed statistical probability depending on age with p = 0.064. This is not statistically significant, but it is very close to the border p = 0.05. In our study was shown strong correlation for older patients to have AAA present in lateral wall of maxilla.

Practical management

The AAA presents danger for operator and for the patient; short time result can be jeopardized by severe bleeding and decreasing visibility, which can result in perforations and mistakes (Taschieri & Rosano, 2010).

First of all, preservation and minimal invasivity is the key approach in dentistry. We know the AAA is 100% present and in 20% it can be in the way of lateral sinus lift. To avoid injury, different techniques can be considered: short implants or transcrestal sinus lift. However, these techniques also have their limitations. When making decisions, it is also important to consider the long-term prognosis of the treatment and not to harm the patient with an inferior treatment outcome (Ella et al., 2008; Sedov et al., 2020).

If the lateral sinus lift is necessary or highly advantageous and AAA is in the way of surgery, careful planning and osteotomy shifting, is advantageous (Cecchetti et al., 2021).

If there is no possibility to shift the osteotomy, the kind of the AAA should be considered. In case of intrasinus AAA, the piezo surgery is possible and avoiding the damage of the artery is possible. In the case of intrabony canal, the double window technique is advantageous. The smaller lateral window osteotomy can be advantageous. Extrabony AAA is raised with flap, the avoiding of damage is important during releasing the flap. The use of scissors is possible (Maridati et al., 2014).

In case of severe bleeding from artery in diameter larger than 3 mm, the preventive ligature can be considered or flap elevation with preparation to ligature of distal aspect, can be considered (Yang & Lee, 2021). Figures 14 and 15 show the result of an alternative surgical approach—an internal sinus lift which is also a very conservative treatment option, albeit with some limitations—was used to elevate the floor of the maxillary sinus by six mm.

If the diameter is smaller than 0.5 mm, no management is possible option (Yang & Lee, 2021).

In case of relatively severe bleeding, the kind of the AAA varies in management. In extrabony component, the electrocautery or ligature is possible. In the case of intrabony, the compression or obstruction of the orifice is possible. The intrabony component can be combined with extrabony or intrasinus, the obstruction may not be effective in incomplete bony canal. Intrasinus is challenging: the electrocautery can lead to damage of Schneiderian membrane, and ligature may not be possible. Finding the intrabony component and its management can be an effective course of action (Maridati et al., 2014; Yang & Lee, 2021).

Figure 16 demonstrates an intact AAA in the lateral sinus lift window osteotomy. Comparison of maxillary sinus floor distances in edentulous and edentulous patients provides insight into maxillary pneumatization, which appears to be inhibited by the presence of tooth roots. Thus, in edentulous patients, the distance of the maxillary sinus floor from the at-risk AAA structure increases. This should be considered, for example, in orthognathic surgery where the bone incision is guided over the teeth. The relationship between the position of the hard palate, which is not subject to resorptions, and AAA has not shown a significantly stable relationship, especially in the P2 and P1 positions, where AAA occurs with considerable variability, thus indicating the need for a thorough examination. However, proximity of the AAA to the alveolar process rather than mesially is common in the M1 region.

There is no direct evidence that limiting maxillary periosteal nutrition by sacrificing AAA could compromise the success of bone grafting. This hypothesis was put forward by Taschieri & Rosano (2010). However, the maxilla is a highly vascularized bone. The very thin maxilla in the lateral section obviously lacks vascular supply from the spongiosa, but it is also nourished by the periosteum on the other side (Taschieri & Rosano, 2010).