Anatomical Study of Pterygoid Implants: Artery and Nerve Passage through Bone Dehiscence of the Greater Palatine Canal

Anatomical Study of Pterygoid Implants: Artery and Nerve Passage through Bone Dehiscence of the Greater Palatine Canal | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Anatomical Study of Pterygoid Implants: Artery and Nerve Passage through Bone Dehiscence of the Greater Palatine Canal Shuichiro Taniguchi, Masahito Yamamoto, Tomohito Tanaka, Tianyi Yang, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4225923/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Purpose Pterygoid implants are an alternative approach to avoid sinus-lifting or other grafting procedures. During pterygoid implant placement, dental surgeons risk damaging the greater palatine canal (GPC). However, they do not have sufficient reasons to avoid GPC injury. This study performed a detailed morphological analysis of the GPC to determine susceptibility to damage during pterygoid implant surgery. Methods To understand the detailed morphology of the GPC, gross anatomical analysis, histological analysis, and bone morphometry via micro-computed tomography were performed. Results We found that the medial wall of the GPC communicated with the nasal cavity through the bone dehiscence. The dehiscence appeared near the inferior nasal concha in 72.4% of the patients. The nerve and artery passed from the GPC to the nasal mucous membrane through the dehiscence. Given that the greater palatine nerve passed medial to the descending palatine artery in the GPC, the descending palatine artery is damaged first rather than the greater palatine nerve during pterygoid implant surgery. Conclusions Dental surgeons who penetrate the GPC using an implant body may extend the bleeding to the nasal mucosa, which seems to spread the inflammation to the nasal cavity. Pterygoid implant Greater palatine canal Bone dehiscence Greater palatine nerve Descending palatine artery Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Background Pterygoid implants, first proposed by Tulasne in 1992 [ 1 ], have been used an alternative approach to avoid sinus-lifting or other grafting procedures during the treatment of the posterior maxilla [ 2 – 8 ]. Pterygoid implants target the anatomical structures of the posterior maxilla, including the maxillary tuberosity, the pyramidal process of the palatine bone, and the pterygoid process of the sphenoid bone [ 9 ]. Given that the pyramidal process and pterygoid process have greater bone quality than do the maxillary alveolar process and tuberosity [ 3 ], the posterior maxillary region has been considered useful for dental implants. Moreover, studies have shown that pterygoid implants have high survival rates, comparable to those observed with conventional implant techniques [ 2 – 8 ]. However, the placement of pterygoid implants is extremely difficult and requires dental surgeons to accumulate a considerable amount of surgical experience [ 6 ]. Moreover, pterygoid implant placement requires surgeons to have thorough knowledge of anatomical structures [ 2 – 9 ], particularly regarding the internal maxillary artery, the maxillary sinus, the greater palatine canal (GPC), the posterior superior alveolar nerve, and pterygoid muscles [ 3 , 9 , 10 ]. Pterygoid implant placement has been associated with the risk of damaging the GPC [ 11 ], a thin passage through which the descending palatine artery, vein, and greater palatine nerves run to supply or innervate the mucosa on the maxillary and palatine bones via the greater palatine foramen (GPF) [ 12 ]. The GPC is formed medially by the perpendicular plate of the palatine, anteriorly by the infratemporal surface of the maxilla, and posteriorly by the pterygoid process of the sphenoid [ 13 ]. Moreover, the GPC runs posteriorly to the maxillary sinus, with the distance from its posterior wall to the GPC being unique for every person [ 7 ]. On the other hand, the nasal cavity is located just medial to the GPC [ 12 ]. During cadaver dissection, the GPC can be identified by removing the mucosa of the posterior part of the nasal cavity [ 12 ]. Interestingly, a radioanatomic study using computed tomography (CT) showed that 38% of patient showed dehiscence in some parts of the medial bony wall of the GPC toward the nasal cavity [ 14 ]. However, dental surgeons do not have sufficient reasons to avoid GPC injury during pterygoid implants. The current study performed a detailed morphological analysis of the GPC to determine susceptibility to damage during pterygoid implant surgery. Methods This study was performed in accordance with the provisions of the Declaration of Helsinki 1995 (as revised in Edinburgh 2000). We used cadavers and skulls donated to Tokyo Dental College for research and education on human anatomy after obtaining approval from the university ethics committee (No. 922-2). In all cases, the cause of death was ischemic heart or brain disease, and no macroscopic pathology was evident in the head, thorax, or abdomen were noted during dissection to obtain the specimens. After removing the brain, the cadaveric head was divided into the left and right halves. Thereafter, we dissected the both adult nasal cavities in five donated cadavers (two males and three females aged 72–88 years at death). To obtain histological sections, we removed the GPC and its surrounding structures in 10 donated cadavers (6 males and 4 females aged 71–92 years at death). After removing the brain, the cadaveric head was divided into the left and right halves. The entire mandible was then removed along with the masseter and medial pterygoid muscles. A horizontal cut was made on the upper side of the maxillary sinus to obtain an almost cubic block of the GPC. The cadavers had been fixed via arterial perfusion of 10% v/v formalin solution and stored in 50% v/v ethanol solution for over 3 months. GPC specimens were decalcified by incubating them in Plank–Rychlo solution (AlCl 2 /6H 2 O, 7.0 w/v%; HCl, 3.6; HCOOH, 4.6) at room temperature for 1–2 weeks. After routine procedures for paraffin embedding [ 15 – 19 ], we prepared large horizontal and frontal sections at 200-µm intervals. All histological images were obtained using a Nikon Eclipse 80. We removed the GPC and its surroundings from 29 cadavers (16 males and 13 females aged 68–92 years at death) following a histological study. Samples were scanned using a micro-CT system (HMX-225 Actis4; Tesco Co., Tokyo, Japan). Imaging conditions included a tube voltage of 100 kV, tube current of 70 µA, magnification of 2.5×, slice width of 5 µm, matrix size of 512 × 512, slice pitch of 50 µm, and voxel size of 140 × 140 × 50 µm. The imaging intensifier was 4 in size and had a 1-inch 16-bit CCD camera with 1024 × 1024 scanning lines. This camera generated 1200 raw images. Based on the obtained data, two-dimensional slice data were prepared using the back-projection method. Images were constructed via the volume-rendering method from slice data using 3D construction software (Imaris, Bitplane, Zürich, Switzerland) [ 20 – 22 ]. The GPC was measured by dividing it into three portions. The inferior portion corresponds to the plane below the inferior nasal concha (INC). The middle portion corresponds to the plane at the same level as the inferior margin of the INC. The superior portion corresponds to the plane at the same level as the connection site between the maxilla and the INC. All images were analyzed using Image-Pro 148 (Media Cybernetics, MD, Unites States). Results Anatomical analysis The GPF or GPC was located anterior to the lesser palatine foramen or lesser palatine canal (LPC) (Fig. 1 a, e), whereas the two canals were adjacent to the nasal cavity and maxillary sinus (Fig. 1 e). The lateral view of the skull showed that the pyramidal process of the palatine bone was located between the maxillary tuberosity and the pterygoid process of the sphenoid bone (Fig. 1 b). The unnamed suture appeared between the lateral pterygoid process and the pyramidal process (Fig. 1 b). The low-magnification view of large histological sections (Fig. 1 c–e) clarified that the greater palatine nerve always passed medial to the descending palatine artery in the GPC (10/10) (Fig. 1 e, f). Gross anatomical analysis indicated that the greater palatine nerve was located lateral to the INC (Fig. 2 a, b). However, the descending palatine artery was not identified after removing the medial wall of the GPC (Fig. 2 c). These results suggest that perforation of the GPC first damages the descending palatine artery rather than the greater palatine nerve. Micro-CT images Micro-CT images also demonstrated that GPC passed between the nasal cavity and maxillary sinus (Fig. 3 ). The distance from the GPF and posterior end of the maxillary tuberosity was 11.44 ± 2.56 mm (Fig. 3 a, e and Table 1). The shortest distance from the GPF and medial surface of the maxillary tuberosity was 4.28 ± 1.19mm (Fig. 3 a, e and Table 1). At the inferior level of the INC, the GPC ran parallel to the LPC (Fig. 3 b, c, f, g). The fused palatine canal was identified at the same level as the connection site between the maxilla and the INC (Fig. 3 d, h). Bone dehiscence on the medial bony wall of the GPC was identified near the INC in 72.4% of the patients (21/29) (Fig. 3 e–h). The medial bony GPC was dehiscent in 69.0% of the patients (20/29) at the inferior portion (Fig. 3 b, f) and 58.6% of the patients (17/29) at the middle portion (Fig. 3 c, g). However, hardly any patient (6.9%, 2/29) showed medial wall dehiscence at the superior portion (Fig. 3 d, h). In some cases (10.3%, 3/29), the lateral bony GPC was dehiscent, and the GPC was adjacent to the maxillary sinus (data not shown). The appearance of bone dehiscence in the GPC is described in Table 2. The bone thickness of the inferior and middle portions of the GPC differed significantly between the medial and lateral wall ( p < 0.001; Fig. 3 i, j). However, the thickness of the superior portion of the GPC (fused palatine canal) did not significantly differ between the medial and lateral wall (Fig. 3 k). The thickness of the GPC wall is described in Table 1. Histological analysis of bone dehiscence in the GPC In 50.0% of the patients (5/10), the GPC communicated with the nasal mucosa, with the artery and nerve passing through this continuation in the medial wall (Fig. 4 d–i and 5 c, d). Alternatively, one case (1/10) showed dehiscence in the lateral wall of the GPC but no passage of the artery and nerve through it (Fig. 5 a, b). Discussion Embedding the dental implant body into the posterior maxilla at an angle of 60° toward the lingual side has been found to increase the risk of damage to the GPC [ 23 ]. Hence, surgeons need to secure a safety space of 2 mm between the GPC and pterygoid implants [ 6 ]. Given the individual variations in the morphological characteristics of the posterior maxilla, pre-surgical assessment should be performed [ 24 ]. The most common complication (i.e., intraoperative bleeding) can probably be attributed to damage of the medial or lateral pterygoid muscles during the placement of a dental implant into the pterygoid process [ 1 ]. However, this bleeding can be stopped easily through local hemostasis measures and implant placement [ 25 ]. The descending palatine artery is thicker than the vessels around the pterygoid muscles. Hence, perforation of the GPC can lead to bleeding that is difficult to manage. Traditional anatomical textbooks have described the nerves innervating the nasal mucous membranes [ 12 , 13 ]. Most of the nasal branches enter the nasal cavity through the sphenopalatine foramen. However, a nasal branch is also given off by the greater palatine nerve. The lateral posterior inferior nasal (LPIN) nerve exits the canal through a small unnamed foramen on the vertical plate of the palatine bone and enters the nasal cavity. In the lateral wall of the nasal cavity, this nerve innervates the posterior inferior mucosa, including the INC. Ogi et al. [ 26 ] describe the anatomy of the pterygopalatine ganglion innervation of the lateral nasal wall. The same authors also mentioned that the greater palatine nerve gives off a branch through a small canal on the vertical plate of the palatine bone. Our results showed that a portion of the medial wall of the GPC opened to the nasal cavity near the INC. In addition, we found that the nerve and artery passed through this small canal. This nerve could possibly be the LPIN nerve, considering previous studies. However, no study has yet described whether the LPIN nerve passes with the artery. The sphenopalatine artery supplies the nasal cavity through the sphenopalatine foramen [ 12 , 13 ], but the small artery did not pass through the foramen. Further studies are therefore needed to investigate this new artery passing through a tiny canal. The GPF is an important structure for block anesthesia of the greater palatine nerve used during the treatment of multiple teeth in the posterior maxilla [ 27 ]. The location of the GPF in humans has been clarified mainly through micro-CT and dry skull studies. The majority of people have a GPF located adjacent to their third maxillary molars, whereas some have a GPF locate distal to the third molars [ 28 , 29 ]. However, studies have shown racial variations in GPF location [ 30 – 37 ]. The length of the GPC is around 31.82 mm and can differ significantly according to sex. In fact, a systematic review and meta-analysis revealed that the mean length of the GPC was 26.97 mm, the angle between the vertical plane and axis of the GPC was 19.09°, and the angle between the transverse plane and the axis of the GPC was 62.63° [ 38 ]. Hence, perforation of the GPC by the pterygoid implants seems to spread the inflammation to the nasal cavity. Considering that previous studies have focused on bone morphometry for block anesthesia of the greater palatine nerve, further studies on pterygoid implants are needed. Conclusions The present study demonstrated that the GPC communicated with the nasal cavity through bone dehiscence, which appeared near the INC in 72.4% of the patients (21/29). The nerve and artery passed from the GPC to the nasal mucous membrane through this dehiscence. Considering that the greater palatine nerve always passes medial to the descending palatine artery in the GPC, the descending palatine artery is first damaged rather than the greater palatine nerve during pterygoid implant surgery. Hence, dental surgeons who penetrate the GPC using an implant body may extend the bleeding to the nasal mucosa, which and the seems to spread the inflammation to the nasal cavity. Abbreviations CT Computed tomography GPC Greater palatine canal GPF Greater palatine foramen INC Inferior nasal concha LPC Lesser palatine canal LPIN Lateral posterior inferior nasal Declarations Ethics approval and consent to participate This study was approved by the Ethics Committee of Tokyo Dental College (approval number 922-2). Consent for publication Not applicable. Availability of data and materials The data sets used and analyzed during the current study are available from the corresponding author on reasonable request. Competing interests Shuichiro Taniguchi, Masahito Yamamoto, Tomohito Tanaka, Tianyi Yang, Genji Watanabe, Yuuki Sugiyama, Takahiro Takagi, Gen Murakami, Shogo Hayashi, and Shinichi Abe declare that they have no competing interests. Funding This study was supported by Tokyo dental college in 2023. Authors’ contributions concept/design: M.Y., G.M., S.A. acquisition of data: S. T., M.Y., T.T., T.Y., G.W., Y.S. data analysis/interpretation: S. T., M.Y., T.T., T.Y., G.W., Y.S., T.T. drafting of the manuscript: M.Y., S.A. critical revision of the manuscript: S.H. approval of the article: S. T., M.Y., T.T., T.Y., G.W., Y.S., T.T., G.M., S.H., S.A. Acknowledgements We sincerely thank the staff of the Department of Anatomy, Tokai University, and Tokyo Dental College for their wholehearted cooperation. Authors’ information (optional) 1 Department of Anatomy, Tokyo Dental College, 2-9-18 Kandamisaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan 2 Department of Anatomy, Division of Basic Medical Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara-shi, Kanagawa 259-1193, Japan 3 Division of Internal Medicine, Iwamizawa Koujinkai Hospital, 297 Shimon-cho, Iwamizawa 068-0833, Japan References Tulasne JF. Osseointegrated fixtures in the pterygoid region. In: Worthington P, Branemark PI, editors. Advanced Osseointegration Surgery: Applications in the Maxillofacial Region. 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Supplementary Files Table1.xlsx Table2.2.xlsx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 02 Sep, 2024 Reviews received at journal 02 Sep, 2024 Reviewers agreed at journal 21 Aug, 2024 Reviews received at journal 19 Apr, 2024 Reviewers agreed at journal 12 Apr, 2024 Reviewers invited by journal 09 Apr, 2024 Editor assigned by journal 09 Apr, 2024 Submission checks completed at journal 09 Apr, 2024 First submitted to journal 06 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4225923","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":289556514,"identity":"e791d23c-736b-4213-ac4b-20020c781f37","order_by":0,"name":"Shuichiro Taniguchi","email":"","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":false,"prefix":"","firstName":"Shuichiro","middleName":"","lastName":"Taniguchi","suffix":""},{"id":289556515,"identity":"c589efdb-3f49-477f-a789-f6461776178c","order_by":1,"name":"Masahito Yamamoto","email":"data:image/png;base64,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","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":true,"prefix":"","firstName":"Masahito","middleName":"","lastName":"Yamamoto","suffix":""},{"id":289556517,"identity":"d17a40d2-6b0a-4b99-ab49-91ff9218c6ef","order_by":2,"name":"Tomohito Tanaka","email":"","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":false,"prefix":"","firstName":"Tomohito","middleName":"","lastName":"Tanaka","suffix":""},{"id":289556519,"identity":"10b0b917-db21-4c63-8c27-aa0a8fc06d21","order_by":3,"name":"Tianyi Yang","email":"","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":false,"prefix":"","firstName":"Tianyi","middleName":"","lastName":"Yang","suffix":""},{"id":289556522,"identity":"d3884f04-2b2d-4dea-9bc8-d44634364707","order_by":4,"name":"Genji Watanabe","email":"","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":false,"prefix":"","firstName":"Genji","middleName":"","lastName":"Watanabe","suffix":""},{"id":289556524,"identity":"4a545847-9b3e-4212-9735-0e4989df89bb","order_by":5,"name":"Yuki Sugiyama","email":"","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":false,"prefix":"","firstName":"Yuki","middleName":"","lastName":"Sugiyama","suffix":""},{"id":289556527,"identity":"545918e5-caa8-43b0-b15a-671e605f7cb0","order_by":6,"name":"Takahiro Takagi","email":"","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":false,"prefix":"","firstName":"Takahiro","middleName":"","lastName":"Takagi","suffix":""},{"id":289556529,"identity":"fa858a6e-225f-4b2b-bcbc-d20282079eb0","order_by":7,"name":"Gen Murakami","email":"","orcid":"","institution":"Iwamizawa Koujinkai Hospital","correspondingAuthor":false,"prefix":"","firstName":"Gen","middleName":"","lastName":"Murakami","suffix":""},{"id":289556530,"identity":"8053c2c3-380b-4135-8480-e58f775d608b","order_by":8,"name":"Shogo Hayashi","email":"","orcid":"","institution":"Tokai University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Shogo","middleName":"","lastName":"Hayashi","suffix":""},{"id":289556533,"identity":"da30ca00-5662-4186-8e1f-269d3ea022c1","order_by":9,"name":"Shinichi Abe","email":"","orcid":"","institution":"Tokyo Dental College","correspondingAuthor":false,"prefix":"","firstName":"Shinichi","middleName":"","lastName":"Abe","suffix":""}],"badges":[],"createdAt":"2024-04-06 06:14:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4225923/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4225923/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":54865328,"identity":"a610dd0f-3cff-4581-930a-0c13abf61ca7","added_by":"auto","created_at":"2024-04-17 20:44:43","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":4724876,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGreater palatine canal and its surrounding structures.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePanel \u003cstrong\u003ea\u003c/strong\u003e: Inferior view of the greater palatine foramen (GPF) and its surrounding structures in a dry skull. Panel \u003cstrong\u003eb\u003c/strong\u003e: Lateral view of the dry skull and simulation of the pterygoid implant. An unnamed suture (pink arrow) was identified between the LPP and PB. Panels \u003cstrong\u003ec–f\u003c/strong\u003e: Histological analysis of the GPF and its surrounding structures. All panels are horizontal sections. Panel \u003cstrong\u003ec\u003c/strong\u003e (\u003cstrong\u003ee\u003c/strong\u003e) shows the most inferior (superior) side. Panel \u003cstrong\u003ef\u003c/strong\u003e is a high-magnification view of panel \u003cstrong\u003ee\u003c/strong\u003e. The descending palatine artery is located lateral to the greater palatine nerve (panels \u003cstrong\u003ee\u003c/strong\u003e, \u003cstrong\u003ef\u003c/strong\u003e). Bu, buccinator muscle; M, medial pterygoid muscle; GPC, greater palatine canal; GPF, greater palatine foramen; H, pterygoid hamulus; MT, maximally tuberosity; LPC, lesser palatine canal; LPF, lesser palatine foramen; LPP, lateral pterygoid process of the sphenoid; PB, pyramidal process of the palatine bone; TVP, tensor veli palatini muscle\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/032ce61c1c2bad101cb8b175.png"},{"id":54866353,"identity":"ad283f0d-05e8-47d4-90f3-7f4e85c201dd","added_by":"auto","created_at":"2024-04-17 20:52:43","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":3803210,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGress anatomical analysis in the greater palatine canal.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePanel \u003cstrong\u003ea\u003c/strong\u003e: Medial view of the nasal cavity before dissection. Panel \u003cstrong\u003eb\u003c/strong\u003e: Medial view of the nasal cavity after cutting the edge of the inferior nasal concha. Panel \u003cstrong\u003ec\u003c/strong\u003e: High-magnification view of panel \u003cstrong\u003eb\u003c/strong\u003e. After removing a portion of the inferior nasal concha, only the greater palatine nerve was identified. The descending palatine artery was not observed. GPN: greater palatine nerve, Mm: middle nasal meatus, MNC: middle nasal concha, Im: inferior nasal meatus, INC: inferior nasal concha, S sinus: sphenoid sinus\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/40f7f0cc8967543757bcf675.png"},{"id":54865326,"identity":"3f1cc53f-8dd5-46d0-8be6-74cb6a83710a","added_by":"auto","created_at":"2024-04-17 20:44:43","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":290686,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMicro-CT images of the greater palatine canal and its surrounding structures.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePanels\u003cstrong\u003e a\u003c/strong\u003e–\u003cstrong\u003ed\u003c/strong\u003e: Bone dehiscence on the medial bony wall of the GPC was not identified near the inferior nasal concha. Panels \u003cstrong\u003ee\u003c/strong\u003e–\u003cstrong\u003eh\u003c/strong\u003e: Bone dehiscence was identified near the inferior nasal concha. Panels \u003cstrong\u003ea\u003c/strong\u003e and \u003cstrong\u003ee\u003c/strong\u003e depict an inferior view of the palate. Panels \u003cstrong\u003eb\u003c/strong\u003e and \u003cstrong\u003ef \u003c/strong\u003ecorrespond to a plane below the inferior nasal concha (INC). Panels \u003cstrong\u003ec \u003c/strong\u003eand \u003cstrong\u003eg\u003c/strong\u003e are planes at the same level as the inferior margin of the INC. Panels \u003cstrong\u003ed\u003c/strong\u003e and \u003cstrong\u003eh\u003c/strong\u003e are planes at the same level of the connection site between the maxilla and the INC. Panels \u003cstrong\u003ef\u003c/strong\u003e and \u003cstrong\u003eg\u003c/strong\u003e show bone dehiscence.\u003c/p\u003e\n\u003cp\u003eAsterisk: greater palatine canal, Circle: lesser palatine canal, Green asterisk: fused palatine canal, INC: inferior nasal concha, N: nasal cavity, S: maxillary sinus.\u003c/p\u003e\n\u003cp\u003ea. GPF: Posterior end of maxillary tuberosity\u003c/p\u003e\n\u003cp\u003eb. GPF:Medial surface of the maxillary tuberosity\u003c/p\u003e\n\u003cp\u003ec. GPC:Anterior margin of the pterygoid hamulus\u003c/p\u003e\n\u003cp\u003ed. The thickness of the lateral bony GPC\u003c/p\u003e\n\u003cp\u003ee. The thickness of the medial wall bony GPC\u003c/p\u003e\n\u003cp\u003ef. The thickness of the lateral bony GPC\u003c/p\u003e\n\u003cp\u003eg. The thickness of the medial wall bony GPC\u003c/p\u003e\n\u003cp\u003eh. The thickness of the lateral bony GPC\u003c/p\u003e\n\u003cp\u003ei. The thickness of the medial wall bony GPC\u003c/p\u003e\n\u003cp\u003ePanels \u003cstrong\u003ei\u003c/strong\u003e–\u003cstrong\u003ek\u003c/strong\u003e: Comparison of the thickness between the medial and lateral walls of the greater palatine canals.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/f5afd8ff8b7d65695d8b64fb.png"},{"id":54865330,"identity":"2ee16538-c752-412a-973b-c13200abb6eb","added_by":"auto","created_at":"2024-04-17 20:44:43","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":6475777,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHistological analysis of bone dehiscence of the medial bony wall in the greater palatine canal.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll panels are frontal sections. Panel \u003cstrong\u003ea\u003c/strong\u003e (\u003cstrong\u003ec\u003c/strong\u003e) shows the most anterior (posterior) side. Panels \u003cstrong\u003ed\u003c/strong\u003e–\u003cstrong\u003ef \u003c/strong\u003eare high-magnification views of panels \u003cstrong\u003ea\u003c/strong\u003e–\u003cstrong\u003ec\u003c/strong\u003e respectively. Panels \u003cstrong\u003eg\u003c/strong\u003e–\u003cstrong\u003ei\u003c/strong\u003e are high-magnification views of panels d-f respectively. The left-hand side corresponds to the lateral side.\u003c/p\u003e\n\u003cp\u003eThe greater palatine canal communicates with the nasal mucosa (panels \u003cstrong\u003ed\u003c/strong\u003e–\u003cstrong\u003ef\u003c/strong\u003e, arrowheads), and the artery and nerve pass through this continuation (panels \u003cstrong\u003eg\u003c/strong\u003e–\u003cstrong\u003ei\u003c/strong\u003e).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/c2e73b46ed7b498b1267eb40.png"},{"id":54865331,"identity":"105af547-cd7d-48dc-8e58-577ecbc13e48","added_by":"auto","created_at":"2024-04-17 20:44:44","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":4096007,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHistological analysis of bone dehiscence of medial and lateral bony walls in greater palatine canal.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll panels are frontal sections. Panels \u003cstrong\u003ea\u003c/strong\u003e and \u003cstrong\u003eb\u003c/strong\u003e show the lateral wall of the greater palatine canal (GPC). Panels \u003cstrong\u003ec\u003c/strong\u003e and\u003cstrong\u003e d\u003c/strong\u003e show the medial wall of the GPC. Panels \u003cstrong\u003ea\u003c/strong\u003e and \u003cstrong\u003ec\u003c/strong\u003e are anterior side compared with panels \u003cstrong\u003eb\u003c/strong\u003e and \u003cstrong\u003ed\u003c/strong\u003e. Panels \u003cstrong\u003ee\u003c/strong\u003e and \u003cstrong\u003ef \u003c/strong\u003eare high-magnification views of panels \u003cstrong\u003ea\u003c/strong\u003e and \u003cstrong\u003eb\u003c/strong\u003e. The medial (panels \u003cstrong\u003ec\u003c/strong\u003e and \u003cstrong\u003ed\u003c/strong\u003e) and lateral (panel \u003cstrong\u003ee\u003c/strong\u003e) wall of the GPC have bone dehiscence. The nerve and artery passed through the bone dehiscence only at the medial wall (panels c and d). The yellow circle in panel \u003cstrong\u003ee\u003c/strong\u003e shows bone dehiscence at the lateral wall. The blue circles in panels \u003cstrong\u003ec\u003c/strong\u003e and \u003cstrong\u003ed\u003c/strong\u003e indicate nerves, whereas the asterisks in panels \u003cstrong\u003ec\u003c/strong\u003e and \u003cstrong\u003ed \u003c/strong\u003eindicate arteries.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/9c09ffa5bd85ccfaa7d54d62.png"},{"id":54866708,"identity":"7e215d73-c1a1-4798-a0f6-69f1292ed8b9","added_by":"auto","created_at":"2024-04-17 21:08:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7059571,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/85b949c8-7fba-49b2-8402-bf9c34c5b627.pdf"},{"id":54865324,"identity":"51da6807-da06-40bb-89e8-24cce6caefec","added_by":"auto","created_at":"2024-04-17 20:44:43","extension":"xlsx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":10950,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/720d1dc6b0d2a8aa75945a40.xlsx"},{"id":54866541,"identity":"627d6895-7b36-4588-98ac-fa21040ebb0b","added_by":"auto","created_at":"2024-04-17 21:00:43","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":11053,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.2.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-4225923/v1/f486a910ac3f92e57b84b259.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Anatomical Study of Pterygoid Implants: Artery and Nerve Passage through Bone Dehiscence of the Greater Palatine Canal","fulltext":[{"header":"Background","content":"\u003cp\u003ePterygoid implants, first proposed by Tulasne in 1992 [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], have been used an alternative approach to avoid sinus-lifting or other grafting procedures during the treatment of the posterior maxilla [\u003cspan additionalcitationids=\"CR3 CR4 CR5 CR6 CR7\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Pterygoid implants target the anatomical structures of the posterior maxilla, including the maxillary tuberosity, the pyramidal process of the palatine bone, and the pterygoid process of the sphenoid bone [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Given that the pyramidal process and pterygoid process have greater bone quality than do the maxillary alveolar process and tuberosity [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], the posterior maxillary region has been considered useful for dental implants. Moreover, studies have shown that pterygoid implants have high survival rates, comparable to those observed with conventional implant techniques [\u003cspan additionalcitationids=\"CR3 CR4 CR5 CR6 CR7\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, the placement of pterygoid implants is extremely difficult and requires dental surgeons to accumulate a considerable amount of surgical experience [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Moreover, pterygoid implant placement requires surgeons to have thorough knowledge of anatomical structures [\u003cspan additionalcitationids=\"CR3 CR4 CR5 CR6 CR7 CR8\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], particularly regarding the internal maxillary artery, the maxillary sinus, the greater palatine canal (GPC), the posterior superior alveolar nerve, and pterygoid muscles [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePterygoid implant placement has been associated with the risk of damaging the GPC [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], a thin passage through which the descending palatine artery, vein, and greater palatine nerves run to supply or innervate the mucosa on the maxillary and palatine bones via the greater palatine foramen (GPF) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The GPC is formed medially by the perpendicular plate of the palatine, anteriorly by the infratemporal surface of the maxilla, and posteriorly by the pterygoid process of the sphenoid [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Moreover, the GPC runs posteriorly to the maxillary sinus, with the distance from its posterior wall to the GPC being unique for every person [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. On the other hand, the nasal cavity is located just medial to the GPC [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. During cadaver dissection, the GPC can be identified by removing the mucosa of the posterior part of the nasal cavity [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Interestingly, a radioanatomic study using computed tomography (CT) showed that 38% of patient showed dehiscence in some parts of the medial bony wall of the GPC toward the nasal cavity [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, dental surgeons do not have sufficient reasons to avoid GPC injury during pterygoid implants. The current study performed a detailed morphological analysis of the GPC to determine susceptibility to damage during pterygoid implant surgery.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis study was performed in accordance with the provisions of the Declaration of Helsinki 1995 (as revised in Edinburgh 2000). We used cadavers and skulls donated to Tokyo Dental College for research and education on human anatomy after obtaining approval from the university ethics committee (No. 922-2). In all cases, the cause of death was ischemic heart or brain disease, and no macroscopic pathology was evident in the head, thorax, or abdomen were noted during dissection to obtain the specimens.\u003c/p\u003e \u003cp\u003eAfter removing the brain, the cadaveric head was divided into the left and right halves. Thereafter, we dissected the both adult nasal cavities in five donated cadavers (two males and three females aged 72\u0026ndash;88 years at death). To obtain histological sections, we removed the GPC and its surrounding structures in 10 donated cadavers (6 males and 4 females aged 71\u0026ndash;92 years at death). After removing the brain, the cadaveric head was divided into the left and right halves. The entire mandible was then removed along with the masseter and medial pterygoid muscles. A horizontal cut was made on the upper side of the maxillary sinus to obtain an almost cubic block of the GPC. The cadavers had been fixed via arterial perfusion of 10% v/v formalin solution and stored in 50% v/v ethanol solution for over 3 months. GPC specimens were decalcified by incubating them in Plank\u0026ndash;Rychlo solution (AlCl\u003csub\u003e2\u003c/sub\u003e/6H\u003csub\u003e2\u003c/sub\u003eO, 7.0 w/v%; HCl, 3.6; HCOOH, 4.6) at room temperature for 1\u0026ndash;2 weeks. After routine procedures for paraffin embedding [\u003cspan additionalcitationids=\"CR16 CR17 CR18\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], we prepared large horizontal and frontal sections at 200-\u0026micro;m intervals. All histological images were obtained using a Nikon Eclipse 80.\u003c/p\u003e \u003cp\u003eWe removed the GPC and its surroundings from 29 cadavers (16 males and 13 females aged 68\u0026ndash;92 years at death) following a histological study. Samples were scanned using a micro-CT system (HMX-225 Actis4; Tesco Co., Tokyo, Japan). Imaging conditions included a tube voltage of 100 kV, tube current of 70 \u0026micro;A, magnification of 2.5\u0026times;, slice width of 5 \u0026micro;m, matrix size of 512 \u0026times; 512, slice pitch of 50 \u0026micro;m, and voxel size of 140 \u0026times; 140 \u0026times; 50 \u0026micro;m. The imaging intensifier was 4 in size and had a 1-inch 16-bit CCD camera with 1024 \u0026times; 1024 scanning lines. This camera generated 1200 raw images. Based on the obtained data, two-dimensional slice data were prepared using the back-projection method. Images were constructed via the volume-rendering method from slice data using 3D construction software (Imaris, Bitplane, Z\u0026uuml;rich, Switzerland) [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The GPC was measured by dividing it into three portions. The inferior portion corresponds to the plane below the inferior nasal concha (INC). The middle portion corresponds to the plane at the same level as the inferior margin of the INC. The superior portion corresponds to the plane at the same level as the connection site between the maxilla and the INC. All images were analyzed using Image-Pro 148 (Media Cybernetics, MD, Unites States).\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eAnatomical analysis\u003c/h2\u003e \u003cp\u003eThe GPF or GPC was located anterior to the lesser palatine foramen or lesser palatine canal (LPC) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, e), whereas the two canals were adjacent to the nasal cavity and maxillary sinus (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee). The lateral view of the skull showed that the pyramidal process of the palatine bone was located between the maxillary tuberosity and the pterygoid process of the sphenoid bone (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). The unnamed suture appeared between the lateral pterygoid process and the pyramidal process (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). The low-magnification view of large histological sections (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec\u0026ndash;e) clarified that the greater palatine nerve always passed medial to the descending palatine artery in the GPC (10/10) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee, f). Gross anatomical analysis indicated that the greater palatine nerve was located lateral to the INC (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, b). However, the descending palatine artery was not identified after removing the medial wall of the GPC (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThese results suggest that perforation of the GPC first damages the descending palatine artery rather than the greater palatine nerve.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eMicro-CT images\u003c/h2\u003e \u003cp\u003eMicro-CT images also demonstrated that GPC passed between the nasal cavity and maxillary sinus (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The distance from the GPF and posterior end of the maxillary tuberosity was 11.44\u0026thinsp;\u0026plusmn;\u0026thinsp;2.56 mm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, e and Table\u0026nbsp;1). The shortest distance from the GPF and medial surface of the maxillary tuberosity was 4.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.19mm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, e and Table\u0026nbsp;1). At the inferior level of the INC, the GPC ran parallel to the LPC (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb, c, f, g). The fused palatine canal was identified at the same level as the connection site between the maxilla and the INC (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, h).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBone dehiscence on the medial bony wall of the GPC was identified near the INC in 72.4% of the patients (21/29) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee\u0026ndash;h). The medial bony GPC was dehiscent in 69.0% of the patients (20/29) at the inferior portion (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb, f) and 58.6% of the patients (17/29) at the middle portion (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, g). However, hardly any patient (6.9%, 2/29) showed medial wall dehiscence at the superior portion (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, h). In some cases (10.3%, 3/29), the lateral bony GPC was dehiscent, and the GPC was adjacent to the maxillary sinus (data not shown). The appearance of bone dehiscence in the GPC is described in Table\u0026nbsp;2.\u003c/p\u003e \u003cp\u003eThe bone thickness of the inferior and middle portions of the GPC differed significantly between the medial and lateral wall (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ei, j). However, the thickness of the superior portion of the GPC (fused palatine canal) did not significantly differ between the medial and lateral wall (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ek). The thickness of the GPC wall is described in Table\u0026nbsp;1.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eHistological analysis of bone dehiscence in the GPC\u003c/h2\u003e \u003cp\u003eIn 50.0% of the patients (5/10), the GPC communicated with the nasal mucosa, with the artery and nerve passing through this continuation in the medial wall (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed\u0026ndash;i and \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec, d). Alternatively, one case (1/10) showed dehiscence in the lateral wall of the GPC but no passage of the artery and nerve through it (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, b).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eEmbedding the dental implant body into the posterior maxilla at an angle of 60\u0026deg; toward the lingual side has been found to increase the risk of damage to the GPC [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Hence, surgeons need to secure a safety space of 2 mm between the GPC and pterygoid implants [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Given the individual variations in the morphological characteristics of the posterior maxilla, pre-surgical assessment should be performed [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The most common complication (i.e., intraoperative bleeding) can probably be attributed to damage of the medial or lateral pterygoid muscles during the placement of a dental implant into the pterygoid process [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, this bleeding can be stopped easily through local hemostasis measures and implant placement [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The descending palatine artery is thicker than the vessels around the pterygoid muscles. Hence, perforation of the GPC can lead to bleeding that is difficult to manage.\u003c/p\u003e \u003cp\u003eTraditional anatomical textbooks have described the nerves innervating the nasal mucous membranes [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Most of the nasal branches enter the nasal cavity through the sphenopalatine foramen. However, a nasal branch is also given off by the greater palatine nerve. The lateral posterior inferior nasal (LPIN) nerve exits the canal through a small unnamed foramen on the vertical plate of the palatine bone and enters the nasal cavity. In the lateral wall of the nasal cavity, this nerve innervates the posterior inferior mucosa, including the INC. Ogi et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] describe the anatomy of the pterygopalatine ganglion innervation of the lateral nasal wall. The same authors also mentioned that the greater palatine nerve gives off a branch through a small canal on the vertical plate of the palatine bone. Our results showed that a portion of the medial wall of the GPC opened to the nasal cavity near the INC. In addition, we found that the nerve and artery passed through this small canal. This nerve could possibly be the LPIN nerve, considering previous studies. However, no study has yet described whether the LPIN nerve passes with the artery. The sphenopalatine artery supplies the nasal cavity through the sphenopalatine foramen [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], but the small artery did not pass through the foramen. Further studies are therefore needed to investigate this new artery passing through a tiny canal.\u003c/p\u003e \u003cp\u003eThe GPF is an important structure for block anesthesia of the greater palatine nerve used during the treatment of multiple teeth in the posterior maxilla [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. The location of the GPF in humans has been clarified mainly through micro-CT and dry skull studies. The majority of people have a GPF located adjacent to their third maxillary molars, whereas some have a GPF locate distal to the third molars [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. However, studies have shown racial variations in GPF location [\u003cspan additionalcitationids=\"CR31 CR32 CR33 CR34 CR35 CR36\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. The length of the GPC is around 31.82 mm and can differ significantly according to sex. In fact, a systematic review and meta-analysis revealed that the mean length of the GPC was 26.97 mm, the angle between the vertical plane and axis of the GPC was 19.09\u0026deg;, and the angle between the transverse plane and the axis of the GPC was 62.63\u0026deg; [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Hence, perforation of the GPC by the pterygoid implants seems to spread the inflammation to the nasal cavity. Considering that previous studies have focused on bone morphometry for block anesthesia of the greater palatine nerve, further studies on pterygoid implants are needed.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe present study demonstrated that the GPC communicated with the nasal cavity through bone dehiscence, which appeared near the INC in 72.4% of the patients (21/29). The nerve and artery passed from the GPC to the nasal mucous membrane through this dehiscence. Considering that the greater palatine nerve always passes medial to the descending palatine artery in the GPC, the descending palatine artery is first damaged rather than the greater palatine nerve during pterygoid implant surgery. Hence, dental surgeons who penetrate the GPC using an implant body may extend the bleeding to the nasal mucosa, which and the seems to spread the inflammation to the nasal cavity.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCT Computed tomography\u003c/p\u003e \u003cp\u003eGPC Greater palatine canal\u003c/p\u003e \u003cp\u003eGPF Greater palatine foramen\u003c/p\u003e \u003cp\u003eINC Inferior nasal concha\u003c/p\u003e \u003cp\u003eLPC Lesser palatine canal\u003c/p\u003e \u003cp\u003eLPIN Lateral posterior inferior nasal\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of Tokyo Dental College (approval number 922-2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data sets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eShuichiro Taniguchi, Masahito Yamamoto, Tomohito Tanaka, Tianyi Yang, Genji Watanabe, Yuuki Sugiyama, Takahiro Takagi, Gen Murakami, Shogo Hayashi, and Shinichi Abe declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by Tokyo dental college in 2023.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003econcept/design: M.Y., G.M., S.A.\u003c/p\u003e\n\u003cp\u003eacquisition of data: S. T., M.Y., T.T., T.Y., G.W., Y.S.\u003c/p\u003e\n\u003cp\u003edata analysis/interpretation: S. T., M.Y., T.T., T.Y., G.W., Y.S., T.T.\u003c/p\u003e\n\u003cp\u003edrafting of the manuscript: M.Y., S.A.\u003c/p\u003e\n\u003cp\u003ecritical revision of the manuscript: S.H.\u003c/p\u003e\n\u003cp\u003eapproval of the article: S. T., M.Y., T.T., T.Y., G.W., Y.S., T.T., G.M., S.H., S.A.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe sincerely thank the staff of the Department of Anatomy, Tokai University, and Tokyo Dental College for their wholehearted cooperation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ information (optional)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eDepartment of Anatomy, Tokyo Dental College, 2-9-18 Kandamisaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan \u003csup\u003e2\u003c/sup\u003eDepartment of Anatomy, Division of Basic Medical Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara-shi, Kanagawa 259-1193, Japan \u003csup\u003e3\u003c/sup\u003eDivision of Internal Medicine, Iwamizawa Koujinkai Hospital, 297 Shimon-cho, Iwamizawa 068-0833, Japan\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eTulasne JF. 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J Oral Sci. 2010;52:109-13. \u003c/li\u003e\n\u003cli\u003eKlosek SK, Rungruang T. Anatomical study of the greater palatine artery and related structures of the palatal vault: considerations for palate as the subepithelial connective tissue graft donor site. Surg Radiol Anat. 2009;31:245-50.\u003c/li\u003e\n\u003cli\u003eTomaszewska IM, Tomaszewski KA, Kmiotek EK, Pena IZ, Urbanik A, Nowakowski M, et al. Anatomical landmarks for the localization of the greater palatine foramen--a study of 1200 head CTs, 150 dry skulls, systematic review of literature and meta-analysis. J Anat. 2014;225:419-35.\u003c/li\u003e\n\u003cli\u003eLangenegger JJ, Lownie JF, Cleaton-Jones PE. The relationship of the greater palatine foramen to the molar teeth and pterygoid hamulus in human skulls. J Dent. 1983;11:249-56.\u003c/li\u003e\n\u003cli\u003eMatsuda Y. Location of the dental foramina in human skulls from statistical observations. IJOO. 1927;13:299-305. \u003c/li\u003e\n\u003cli\u003eAjmani ML. 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Anatomy of the greater palatine foramen and canal and their clinical significance in relation to the greater palatine artery: a systematic review and meta-analysis. Surg Radiol Anat. 2023;45:101-19.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"international-journal-of-implant-dentistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"IJID","sideBox":"Learn more about [International Journal of Implant Dentistry](https://journalimplantdent.springeropen.com/)","snPcode":"40729","submissionUrl":"https://submission.nature.com/new-submission/40729/3","title":"International Journal of Implant Dentistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Pterygoid implant, Greater palatine canal, Bone dehiscence, Greater palatine nerve, Descending palatine artery","lastPublishedDoi":"10.21203/rs.3.rs-4225923/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4225923/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003ePterygoid implants are an alternative approach to avoid sinus-lifting or other grafting procedures. During pterygoid implant placement, dental surgeons risk damaging the greater palatine canal (GPC). However, they do not have sufficient reasons to avoid GPC injury. This study performed a detailed morphological analysis of the GPC to determine susceptibility to damage during pterygoid implant surgery.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eTo understand the detailed morphology of the GPC, gross anatomical analysis, histological analysis, and bone morphometry via micro-computed tomography were performed.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eWe found that the medial wall of the GPC communicated with the nasal cavity through the bone dehiscence. The dehiscence appeared near the inferior nasal concha in 72.4% of the patients. The nerve and artery passed from the GPC to the nasal mucous membrane through the dehiscence. Given that the greater palatine nerve passed medial to the descending palatine artery in the GPC, the descending palatine artery is damaged first rather than the greater palatine nerve during pterygoid implant surgery.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eDental surgeons who penetrate the GPC using an implant body may extend the bleeding to the nasal mucosa, which seems to spread the inflammation to the nasal cavity.\u003c/p\u003e","manuscriptTitle":"Anatomical Study of Pterygoid Implants: Artery and Nerve Passage through Bone Dehiscence of the Greater Palatine Canal","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-17 20:44:38","doi":"10.21203/rs.3.rs-4225923/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-03T03:45:11+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-02T12:58:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"288437126256368045950251877151204584033","date":"2024-08-21T06:19:22+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-04-19T05:56:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"abe3abff-0096-49e2-a28f-c82620fa0fbc","date":"2024-04-12T14:01:06+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-10T02:51:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-10T02:45:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-04-09T11:15:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"International Journal of Implant Dentistry","date":"2024-04-06T06:03:56+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"international-journal-of-implant-dentistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"IJID","sideBox":"Learn more about [International Journal of Implant Dentistry](https://journalimplantdent.springeropen.com/)","snPcode":"40729","submissionUrl":"https://submission.nature.com/new-submission/40729/3","title":"International Journal of Implant Dentistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"05de3786-5591-49b7-b939-394a6edbf58a","owner":[],"postedDate":"April 17th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-10-02T09:38:12+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-17 20:44:38","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4225923","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4225923","identity":"rs-4225923","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}