© The authors, 2025

Introduction

Implantology has significantly advanced the therapeutic possibilities available to dental practitioners, allowing for the successful rehabilitation of many patients through prosthetic solutions. Maxillary sinus surgery, particularly for implant placements, is a well-established procedure, though it is not without risks [1]. Understanding the anatomy of the maxillary sinus and its vascular structures, including the Alveolar-Antral Artery (AAA), is crucial for minimizing complications during surgical interventions [2].

Despite the existing knowledge about the surgical risks associated with maxillary sinus procedures, there is limited data on the precise anatomical relationship between the AAA and the alveolar ridge in specific populations. Variability in the distance from the AAA to the alveolar crest, particularly in different dentition statuses, remains inadequately explored. This knowledge gap poses a risk for complications such as hemorrhage during surgery [3].

This study aimed to measure the distance between the AAA and the alveolar ridge using Cone Beam Computed Tomography (CBCT) in a Moroccan subpopulation, with the goal of contributing to a better understanding of the anatomical safety margins necessary for enhancing surgical outcomes in maxillary sinus procedures.

Materials and methods

Study concept

This is a transversal and observational study conducted according to the STROBE (von Elm E, Altman DG, Egger M, Pocock SJ, Gotzsche PC, Vandenbroucke JP; STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies.

Ann Intern Med. 2007 Oct 16;147(8):573-7. Erratum in: Ann Intern Med. 2008 Jan 15;148(2):168. PMID: 17938396).

Context

This study aims to assess the distance between the alveolo-antral artery and the alveolar ridge using CBCT (Cone Beam Computed Tomography) imaging. Accurate measurement of this anatomical distance is essential for planning surgical procedures like sinus lifts and implant placements, with the goal of minimizing surgical risks and enhancing patient outcomes. The findings will be crucial in providing guidance to clinicians in oral and maxillofacial surgery.

CBCT examinations were performed in the Radiology Department of the Dental Consultation and Treatment Center (CCTD) of the IBN ROCHD University Hospital in Casablanca starting from April 2018 to April 2019.

Population

The acquisitions were performed for various indications (implantology, wisdom teeth extraction, periapical inflammatory lesions of endodontic origin, etc.). All CBCTs conducted during this period (299) were subject to the following inclusion and exclusion criteria.

A total of 299 CBCT scans involving the posterior maxilla were initially retrieved from the department's image database. After applying the inclusion and exclusion criteria, 243 scans were deemed eligible. From these, 100 scans were selected for final analysis based on the clear visibility of the alveolar antral artery (AAA) at all three predefined sites: the distal point of the second premolar (PM2), first molar (M1), and second molar (M2).

Inclusion criteria

• Adults aged over 18 yr.

• High-quality CBCT scans displaying the posterior maxilla and maxillary sinus.

• Acquisition of the total area of the right or left maxillary sinus including the teeth or the edentulous ridge of the posterior maxilla : 243 CBCT.

• Detection of the AAA at the 3 distal points of the 2nd premolar, 1st molar, and 2nd molar : 100 CBCT.

Non-inclusion criteria

Patients were excluded from the study if any of the following conditions were present:

• Pathological findings affecting the maxillary sinus, such as cysts, tumors, or signs of acute or chronic sinusitis;

• History of surgery or trauma involving the maxilla or any of the ipsilateral maxillary sinus walls;

• Congenital malformations of the naso-sinus complex or medical history likely to alter sinus wall morphology;

• Severe periodontal disease with vertical bone loss or irregular alveolar crest morphology;

• Poor image quality due to motion artifacts, low contrast, or insufficient resolution;

• Incomplete visibility of critical anatomical landmarks necessary for measurement (e.g., alveolar crest, sinus floor, AAA).

Variables

• Qualitative: sex and edentulous ridge.

• Quantitative: distance between the alveolo-antral artery and the crest.

Imaging protocol

• All CBCT examinations were acquired using a Planmeca Promax 3D® unit (Planmeca, Helsinki, Finland) with the following parameters: 90 kVp, 10 mA, voxel size 200 μm, and field of view (FOV) 10 × 10 cm. The scans were initially performed for clinical indications such as implant planning, pathology investigation, or pre-surgical evaluation.

• Therefore, a standard diagnostic protocol was used instead of an ultra-low dose (ULD) setting, due to the requirement for high-resolution imaging in the accurate detection of (AAA). This decision was driven by the inherent limitations of ULD protocols, particularly their reduced soft tissue contrast.

• Data were exported in DICOM format and analyzed using Planmeca Romexis® Viewer software (version 6.0.1) in a controlled diagnostic environment with calibrated screen conditions.

Source of data and measurements

The distance going from the lower edge of the AAA to the alveolar crest was assessed at 3 points using the Romexis Planmeca software. The distances were measured in mm.

In dentate sites: These 3 points corresponded to the tangent passing through the distal point of the crown of the second molar (M2), first molar (M1), and second premolar (PM2).

In edentulous sites: an anterior tooth was present in all cases with lateral edentulism and served as a fixed reference point for measurements. To identify the corresponding positions of the distal of the second premolar (PM2), first molar (M1), and second molar (M2), we measured from this reference point using the average mesio-distal dimensions of the missing teeth: 7.5 mm for the canine, 7 mm for the first and second premolars (PM1 and PM2), 10 mm for the first molar (M1), and 9 mm for the second molar (M2). This approach allowed measurements to be taken at anatomically equivalent sites to those in the dentate sector.

All measurements were performed twice by a single experienced oral surgeon with over 10 yr of CBCT experience. The mean of the two readings was used for statistical analysis. Standardization of section orientation and slice thickness was maintained to minimize intra-observer variability.

Figure 1 presents a coronal section through the distal point of M1, demonstrating the measurement method of the AAA to alveolar ridge distance.

See Table I.

Cone Beam: Planmeca ProMax 3D Mid Finland 2017.

Bias: measurement bias and point localization bias on CBCT.

To eliminate bias due to periodontal bone loss, scans with clinical or radiographic signs of advanced periodontal disease, horizontal or vertical bone resorption, or irregular crestal anatomy were excluded. Only teeth with healthy surrounding bone structures were retained for analysis.

Fig. 1 Coronal section passing through the distal point of M1, showing the method of measuring the AAA-Alveolar Ridge distance.

Demographics

The study sample included 60 dentate and 40 edentulous cases. The mean age of participants was 52.7 yr (range: 24 to 75 yr). Due to the retrospective nature of the study and the absence of clinical files for all cases, the exact duration of edentulism in the edentulous group could not be determined.

Size of the study

The calculation of the required sample size was based on the following parameters:

Formula: Z2xS2/i2

Z= 1.96 (confidence interval of 95%).

S: The standard deviation of the mean distance between the first molar (M1) and the alveolo-antral artery in the literature is 3.7.

I: The desired precision for this study is 1.

Z2xs2/i2(1.96 × 1.96 × 3.7 × 3.7/1) =53.

Our study population consisted of 100 individuals, which prompted us to opt for an exhaustive investigation.

Statistical analyses

Statistical data were obtained using the SPSS version 22 software.

Statistical processing of the data consisted of a descriptive and analytical study. The analysis was made by non-parametric statistical tests (Fisher).

• Alpha risk of 5%, confidence interval of 95%.

• Descriptive statistics: frequency by sex and edentulous ridge.

• Analytical statistics: Fisher test for comparison of average based on sex and edentulous ridge.

Ethical considerations

This study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki and complied with Moroccan national regulations governing the use of retrospective clinical imaging data. All CBCT scans included in the analysis had been acquired for diagnostic purposes as part of routine clinical care. Prior to imaging, all patients provided written informed consent authorizing the secondary use of their anonymized radiological data for research purposes. Patient confidentiality was strictly preserved throughout the study, and all data were processed and analyzed in compliance with applicable data protection standards.

Results

The sample characteristics are summarized in Tables II–VI.

59% of the sample was female, and 41% was male, as shown in Table II. Table III presents information on the distance of AAA to the alveolar ridge at the distal points of (PM2), (M1), and (M2). It shows that at PM2, the AAA is at an average distance of 16.54 mm ± [3.58] from the alveolar ridge; at M1, the mean distance between the AAA and the alveolar ridge is 15.12 mm ± [3.47]; and at M2, the average distance of the AAA is 16.69 mm ± [3.42] from the alveolar ridge. The lowest AAA to alveolar ridge distance is at the first molar level, and the highest is at the second molar, as illustrated in Figure 2. In this sample, 60% of subjects were dentate in the maxillary posterior sector, while 40% were edentulous in this same sector, as shown in Table IV.

Table V shows the AAA to alveolar ridge distance in the distal region of (PM2), (M1), and (M2) according to gender. For men, at PM2, the AAA is at 16.23 mm ± [3.83] from the alveolar ridge; at M1, the average distance between the AAA and the alveolar ridge is 15.05 mm ± [3.28]; and at M2, the average distance of the AAA is 16.82 mm ± [3.51] from the alveolar ridge. For females, at PM2, the AAA passes a mean distance of 16.76 mm ± [3.41] from the alveolar ridge; at M1, the average distance is 15.16 mm ± [3.62]; and at M2, the average distance is 16.60 mm ± [3.38] from the alveolar ridge. According to these results, no significant difference is found in the mean distance [AAA − alveolar crest] between men and women, as indicated in Figure 3. However, a significant difference in the mean [AAA − alveolar ridge] distance between the presence and absence of teeth is observed, as demonstrated in Table VI. The lowest AAA-alveolar ridge distance is at the first molar in both categories, illustrated in Figure 4.

Fig. 2 Distance AAA − alveolar ridge at the 3 sites (PM2), (M1), (M2). The lowest distance AAA − alveolar ridge is at the first molar, and the highest distance is at the second molar (Fig. 2).

Fig. 3 Distance AAA − Alveolar ridge depending on Gender. Through these results, no significant difference is found in the average distance [AAA − alveolar ridge] between men and women (Fig. 3).

Fig. 4 Distance AAA-Alveolar ridge depending on gap. The lowest distance AAA − alveolar ridge is at the level of the first molar in both categories: dentulous and edentulous patients (Fig. 4).

Discussion

This study measured the distance between the Alveolar-Antral Artery (AAA) and the alveolar ridge in 100 maxillary sinuses using Cone Beam Computed Tomography (CBCT). The findings revealed average distances of 15.12 mm ± 3.47 at the first molar (M1), 16.54 mm ± 3.58 at the second premolar (PM2), and 16.69 mm ± 3.42 at the second molar (M2). Importantly, dentate patients exhibited significantly greater distances compared to edentulous individuals, highlighting variations that could impact surgical planning.

Based on the study results, no correlation was found between the mean [AAA-alveolar crest] distance and gender, aligning with findings from studies by Kim et al. and Kang [4,5]. Most studies investigating the measurement of the AAA-to-alveolar ridge distance have focused solely on the M1 area [6]. This study revealed that at M1, the mean distance between the AAA and the alveolar ridge was 15.12 mm ± [3.47]. Kang et al. found that in their study, the distance between the inferior vessel wall and the alveolar ridge was less than 15 mm in 31% of cases and greater than 15 mm in 69% of cases [5]. Elian et al. reported that out of all AAAs detected, 80% were more than 15 mm away from the ridge, while 20% were less than 15 mm from it [7].

Our findings indicate that the average distance between the alveolar ridge and the AAA is smaller in edentulous patients than in dentate patients, consistent with results reported by Hayek et al. [8]. This study also showed that the AAA is positioned lowest towards the maxillary first molar, which is echoed in the study by Jung et al. Regarding the vertical position of the AAA, the anastomosis has a concave arc shape, with the maxillary first molar being the lowest point relative to the alveolar ridge [9]. In a meta-analysis by Varela-Centelles et al., similar conclusions were drawn [10].

In the study by Lee et al., the alveolar ridge to sinus floor height increases with the canal as it moves into the posterior region, aligning with our study's results since the AAA-alveolar crest distance is maximal at M2 [11]. Many authors have studied the residual height of the ridge and its impact on the AAA-to-alveolar ridge distance [12]. To recall, alveolar bone is born and perishes with the tooth, while basal bone, although constantly remodeling, remains much more stable over time [13]. Periodontal diseases, dental extractions, and senescence are factors that affect bone volume over time [13]. The distance of the AAA to the alveolar crest (15 mm on average), as well as the height of the residual alveolar crest, are interrelated criteria for assessing the risk of vascular injury during surgery [14]. The bony window is mainly located in the maxillary premolar-molar zone, and the position of the AAA is often more than 15 mm from the alveolar ridge, reducing the risk of AAA injury [15]. Nevertheless, a comprehensive pre-surgical study with a CBCT examination is essential for accurately assessing this risk [3].

In the current study, a total of 243 sinuses were examined, of which only 100 were detectable as AAA, translating into a detection rate of 41.2%. Solar et al. studied the vascularization of the lateral wall of the sinus, revealing an endosseous branch of the maxillary posterior alveolar artery in 100% of their samples [13]. The average detection rate of AAAs in radiographic studies (CBCT/scanner) is 52.7%. All cadaveric studies describe the presence of AAA in 100% of cases, except for Ella et al., who reported a detection rate of 10.5% [16]. This discrepancy may be due to only including arteries larger than 0.5 mm in diameter.

The undetectability of AAAs could be attributed to small-diameter AAAs (0.5 mm or 1 mm, depending on the author), an intrasinus or superficial trajectory of the AAA that does not allow its detection on radiography (absence of a bony canal), or the limitations of radiographic examinations (non-discrimination of soft tissue).

The AAA can have three pathways according to Rosano et al. [17]:

• In the anterior bone wall.

• Between Schneider's membrane and the bony wall of the sinus.

• Under the periosteum of the lateral sinus wall.

According to studies by Rosano and Valente, the trajectory of the AAA was observed to be [17,18]:

• Totally intraosseous at its extremities in 100% of cases.

• Partially intraosseous in the sinus surgery area (i.e., from the second premolar to the second molar) in 100% of cases, with the AAA being very close to Schneider's membrane and partially embedded in the bone wall. Varela-Centelles et al. provide a global overview of the evolution of the AAA in their meta-analysis, emphasizing the need to account for the AAA's position, especially when partially intraosseous in the maxillary lateral wall, to avoid vascular damage during sinus lift [10].

Detection of AAA on CT scans is significantly higher for men (64%) than women (40%), according to Kim et al. [4]. The detection rate of the artery in patients with an alveolar ridge height greater than 10 mm is markedly lower than in those with a ridge height less than 10 mm [12,19]. The mean number of missing teeth in patients with detected AAAs on CBCT is significantly higher than in those with undetected AAAs [20].

Our findings align with previous research indicating variability in the AAA-to-alveolar ridge distance based on dentition status. Similar studies, such as those by Kang et al. and Kim et al. have shown no significant gender differences in these measurements, further supporting our results [4,5]. However, while most prior studies focused on the M1 area, our comprehensive analysis across multiple anatomical landmarks provides a broader understanding of the AAA's positioning in relation to the alveolar ridge.

Understanding the anatomical relationship between the AAA and the alveolar ridge is crucial for reducing the risk of vascular injury during maxillary sinus surgeries [1,21]. The significant difference in distance between dentate and edentulous patients emphasizes the need for tailored surgical approaches based on individual anatomical variations. Ongoing advancements in imaging techniques, such as CBCT, can greatly aid in pre-surgical evaluations, ultimately enhancing patient safety and surgical outcomes. Future studies should aim to explore these anatomical variations in diverse populations to further refine surgical strategies [22].

Study limitations

Despite the rigorous inclusion criteria and the use of standardized measurement protocols, this study presents certain inherent limitations. The retrospective design restricted access to comprehensive clinical information, notably the precise duration of edentulism in edentulous subjects. Furthermore, the moderate detection rate of the alveolar-antral artery (41.2%) may be attributable to individual anatomical variations or to technical constraints related to CBCT resolution in identifying small-caliber vascular structures. These elements may have introduced selection bias and limit the generalizability of the findings beyond the studied Moroccan population. Nonetheless, the statistical power of the analysis remains high, and the anatomical data obtained are consistent with those reported in previous studies, thereby supporting the reliability and clinical relevance of the conclusions drawn.

Strengths of the study

This study exhibits several methodological strengths that enhance the validity of its findings. First, the use of high-resolution cone beam computed tomography (CBCT) with a voxel size of 200 μm enabled precise anatomical measurements, minimizing localization errors of the alveolar antral artery (AAA). Standardized acquisition and analysis protocols including consistent slice orientation (1 mm thickness) and exclusion of cases with periodontal disease or imaging artifacts reduced intra-observer variability and mitigated confounding factors related to bone morphology. Furthermore, all measurements were performed twice by a single oral surgeon with over a decade of CBCT experience, and the mean values were used for analysis, ensuring reproducibility. The inclusion of 100 maxillary sinuses, exceeding the minimum sample size calculated a priori, provided robust statistical power to detect clinically meaningful differences between dentate and edentulous subgroups. These methodological choices collectively strengthen the internal validity of the results.

Power analysis

The sample size was determined a priori using the formula: Z2xS2/i2 where (Z = 1.96 (95% confidence interval), S = 3.7 (standard deviation of the AAA-alveolar crest distance at M1, derived from prior literature), and i = 1 (desired precision). This yielded a minimum required sample size of n = 53. Our study included 100 cases, exceeding this threshold. A post-hoc power analysis conducted using G*Power (α = 0.05, effect size = 3 mm, two-tailed test) confirmed a statistical power of 92%, ensuring adequate sensitivity to identify significant anatomical variations. This robust sample size compensates for the moderate AAA detection rate (41.2%) and reinforces the reliability of the conclusions.

Conclusion

The study highlights the importance of understanding the anatomical relationship between the Alveolar-Antral Artery (AAA) and the alveolar ridge in maxillary sinus surgeries. Our findings indicate significant distances between the AAA and the alveolar crest, particularly in dentate versus edentulous patients. This knowledge is essential for minimizing the risk of vascular injury during surgical procedures. Pre-surgical evaluations using Cone Beam Computed Tomography (CBCT) can enhance safety and inform tailored surgical approaches, ultimately improving patient outcomes.

Funding

No funding was received for this article.

Conflicts of interest

The authors declare no conflicts of interest in regards to this manuscript.

Data availability statement

No new data were generated or analyzed in this study.

Author contribution statement

Bruno Ella: validation of the entire study; Simohamed Bouzoubaa: methodology: Farouk Mohamed: statistics; Meriem Lahlou: literature review and bibliographic search; Wijdane El Hawari: revision and submission of the article; Ossama Nabih: drafting the article and conducting the study.

References

All Tables

All Figures

	Fig. 1 Coronal section passing through the distal point of M1, showing the method of measuring the AAA-Alveolar Ridge distance.
In the text

	Fig. 2 Distance AAA − alveolar ridge at the 3 sites (PM2), (M1), (M2). The lowest distance AAA − alveolar ridge is at the first molar, and the highest distance is at the second molar (Fig. 2).
In the text

	Fig. 3 Distance AAA − Alveolar ridge depending on Gender. Through these results, no significant difference is found in the average distance [AAA − alveolar ridge] between men and women (Fig. 3).
In the text

	Fig. 4 Distance AAA-Alveolar ridge depending on gap. The lowest distance AAA − alveolar ridge is at the level of the first molar in both categories: dentulous and edentulous patients (Fig. 4).
In the text