It is a common belief that human anatomy has been well-investigated and is fully understood. However, head and neck anatomy has been updated frequently, including as recently as 2024.1
Further, divergent viewpoints exist between general medical and dental contexts regarding certain head and neck anatomical structures, such as the facial artery. This may stem from historical differences in how anatomical knowledge has been developed and disseminated within dentistry, sometimes without the direct collaboration of anatomists. Consequently, this has led to incorrect descriptions of head and neck anatomy in dentistry. For example, in medicine, the course of the buccal nerve differs from what is accepted in dentistry.1
Knowledge of head and neck anatomy plays a critical role in the successful administration of local dental anesthesia. This is particularly evident in endodontic treatment, which requires profound anesthesia for patient comfort. Yet, endodontists often find that even with superior alveolar nerve blocks and buccal infiltrations targeting the superior alveolar nerves, anesthesia for maxillary teeth is insufficient.1
Additionally, one of the postoperative complications of osteotomy is sensory disturbances of the maxillary teeth, though these complications are often not long-term. Could this mean there is an alternate nerve supply for the maxillary teeth? The consensus is that the greater palatine nerve and artery supply the palatal mucosa, gingiva, and glands, but not the bone or tooth adjacent to those tissues. However, there are multiple small foramina visible, when closely observed, on the palatal surface of the alveolar process.1
This begs the question: What is the function of the small foramina on the palate?
A study aimed to investigate “the palatal innervation and blood supply of the maxillary teeth to add anatomic evidence to the anecdotal knowledge on the necessity of supplemental palatal injection for maxillary endodontic treatment and maxillary osteotomy.”1
The Study
The study was completed on eight cadaveric dry maxillae. Of the cadaveric maxillae, three were from male cadavers, and five were from female cadavers. The cadavers ranged in age from 69 to 92 years. Five different methods were used in the study to determine the nerve and blood supply to the maxillary teeth.1
The first method involved injecting colored water into the small foramina on the palate. The teeth were extracted before the colored water was injected to observe the colored water in the sockets easily. Water colored with purple surgical marker dye was injected into the small foramina using a dental anesthetic syringe with a 31-gauge needle until the colored water was observed in the alveolar sockets.1
The second method used involved injecting latex into the sockets. Following the colored water injection, latex was injected into the alveolar sockets from the central incisors to the third molars. The palate was observed during latex injection to determine if any latex had emerged. The latex was then left to solidify for 48 hours. After 48 hours, the palatal cortical plate was removed to trace the pathway of the latex.1
The third method utilized was microcomputed tomography. Contrast dye was injected into the small foramina on the palate, and images were obtained using microcomputed tomography. The images were used to create a two-dimensional image of multiple axial planes of the maxilla. The images were observed to identify areas where the contrast dye was distributed. A board-certified oral and maxillofacial radiologist then performed an image analysis.1
The fourth method used was gross anatomic dissection. A surgical microscope was used for precision during the dissection of the greater palatine nerve and artery, as well as their branches. After dissection, the nerves and arteries were preserved. The medial branches were removed for better observation.1
Lastly, histological observation of the cadaveric specimen was utilized. The molar region of the maxilla was cut into coronal sections at 8 mm intervals. The tissue was then embedded in paraffin, sliced into sections 5 micrometers thick, and stained to identify different tissue components. A light microscope was then used to observe the palate and small foramina.1
The Results
The results showed that the alveolar branches of the greater palatine nerve and artery also supply the maxillary teeth via small foramina in the palate, groove, and even the greater palatine canal.1
The colored water injected into the small foramina became visible in the socket adjacent to the small foramina. This was observed from the incisor to the third molar on all sides. Similarly, the latex injected into the alveolar sockets was observed emerging from the small foramina on the palate.1
These findings suggest communication between the alveolar socket and the small foramina on the palate, indicating that the nasopalatine nerve and the sphenopalatine artery supply the maxillary teeth, most likely the anterior maxillary teeth, while the greater palatine nerve and artery most likely supply the maxillary molars.1
The microcomputed tomography images indicated that the contrast dye injected into the small foramina on the palate traveled to the periodontal region of the palatal aspect of the maxillary process in the incisor, premolar, molars, and greater palatine canal.1
Gross dissection revealed the greater palatine nerve and artery, and their branches travel through the groove on the alveolar process to enter the bone via small foramina. This was true for the greater palatine nerve branch and the greater palatine artery branch, both in some areas.1
Histological observations through coronal sections indicated that the small foramina in the first molar area contain a small nerve and artery.1
Conclusion
The authors conclude that the maxillary teeth, alveolar bone, and periodontal tissue receive blood and nerve supply through what the authors refer to as the palatal alveolar foramina via the greater palatine nerve and artery, as well as the nasopalatine nerve and sphenopalatine artery, in conjunction with the superior alveolar nerves and arteries.1
The findings of this study show there may be a need for palatal infiltration to achieve profound anesthesia on maxillary molars. This is due to the palatal innervation of the greater palatine nerve branches.1
Additionally, the findings indicate that osteotomy might damage the pulp of the maxillary teeth. The blood and nerve supply for the maxillary teeth was believed to be supplied by the superior alveolar nerves and arteries only. However, this study indicates that the nasopalatine nerve and sphenopalatine artery also supply maxillary teeth via small palatal foramina, groove, and the greater palatine canal through the palatal alveolar foramina. These structures are often cut during osteotomy, which could lead to pulpal damage.1
Previous studies have shown degenerative changes in the pulp after osteotomy surgical procedures. An estimated 6% to 43% of teeth became unresponsive to electrical stimulation after osteotomy.1
With this knowledge, the anterior middle superior alveolar (AMSA) block and palatal infiltration were developed using incorrect anatomy. Nonetheless, depending on the tooth, the AMSA block can still be successful between 17% to 66% of the time it is utilized. The authors suggest the success of ASMA blocks is likely due to the infiltration effects of the anesthesia. Further, the authors suggest that based on the results of this study, the AMSA block targets the trunk or branches of the greater palatine nerve, which innervates the maxillary teeth from the palate. The low success rate associated with the ASMA block might be because the superior alveolar nerves are still believed to be the main supply.1
This anatomical knowledge is crucial for dental hygienists, dentists, and oral surgeons when administering local anesthesia for maxillary treatment, especially osteotomy and endodontic treatment. Additionally, the authors of this study suggest that anatomical and dental textbooks should incorporate these findings to enhance the accuracy of the nerve and vascular supply of the maxillary dentition, ultimately improving patient care.1
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Reference
- Iwanaga, J., Takeshita, Y., Anbalagan, M., et al. The Greater Palatine Nerve and Artery both Supply the Maxillary Teeth: An Anatomic and Radiologic Study. J Am Dent Assoc. 2025; 156(2): 151-159.e1. https://jada.ada.org/article/S0002-8177(24)00711-6/fulltext
