Minimally invasive surgical extraction of an impacted supernumerary tooth in right maxilla with use of a 3D-printed surgical guide and mixed reality: a case description

Introduction

Impacted supernumerary teeth most frequently occur in the maxillary midline, with a reported incidence of 0.15–1.9% (1). They are often asymptomatic and incidentally detected on radiographs obtained during dental treatment (2). Extraction is recommended in cases where the impacted teeth affect their adjacent anatomical structures (3).

Here, we report a case of an impacted supernumerary tooth adjacent to the maxillary sinus and a pyriform aperture that was extracted in a minimally invasive manner using a combination of a three-dimensional (3D) device and mixed reality (MR) technology. In this article, the authors present a case of a supernumerary tooth impacted between the maxillary sinus and the nasal cavity at the edge of the pyriform aperture on the right side. Surgical extraction was performed minimally invasive with use of a 3D-printed surgical guide and MR. To minimize the postoperative deformity of the pyriform aperture contour, bone repositioning was performed with reference to wedge-shaped bone grafting (4), resulting in favorable bone healing.

Case presentation

A 16-year-old male with an impacted supernumerary tooth in the right anterior maxilla was referred to our hospital (Tokyo Dental College Suidobashi Hospital, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan) in October 2024 for detailed examination and treatment. The patient had no notable medical or family history.

The patient had been receiving dental care at a dental clinic since 2023. A panoramic radiograph obtained during the planning for orthodontic treatment revealed a tooth-like radiopaque structure near the right maxillary lateral incisor, and the patient was referred to our department for detailed examination and treatment. The patient was slender and in a good nutritional condition. All permanent teeth except the third molars had erupted. The patient developed diastema between the maxillary central incisors; other findings were unremarkable. The panoramic radiograph obtained at the initial visit revealed a tooth-like radiopaque structure inverted and impacted near the apices of the central and lateral right maxillary incisors. The crown was located between the maxillary sinus and the pyriform aperture (Figure 1A). Cone-beam computed tomography (CBCT) revealed an inverted impacted supernumerary tooth, inclined slightly posteriorly (Figure 1B,1C). The clinical diagnosis was impacted supernumerary tooth in the right anterior maxilla.

Figure 1 Preoperative imaging at the initial visit. (A) Panoramic radiograph showing a tooth-like radiopaque structure inverted and impacted near the apices of the right maxillary central and lateral incisors; the crown is located between the maxillary sinus and the pyriform aperture. (B) Cone-beam computed tomography (axial and coronal) showing the impacted supernumerary tooth adjacent to the nasal floor and maxillary sinus. (C) Three-dimensional reconstructed image.

Treatment plan

We opined that the impacted supernumerary tooth could potentially interfere with the planned orthodontic treatment, thus, it was decided that surgical extraction would be the best option. Preoperative dental CBCT data were processed using Mimics (Materialise, Leuven, Belgium) to identify the exact position of the impacted supernumerary tooth. A surgical guide was designed using Magics (Materialise) and fabricated using a Objet260 Connex (Stratasys Ltd., Minnesota, USA). The surgical guide allowed precise bone removal along the external contour, so that the crown of the impacted tooth could be exposed with appropriate and minimal osteotomy (Figure 2). The segmented 3D data and surgical guide data were installed on a head-mounted display (Apple Vision Pro, Apple Inc., Cupertino, CA, USA) to enable intraoperative mixed-reality visualization, and the planned incision range and surgical procedure were shared among the surgeons during the preoperative phase.

Figure 2 Preoperative planning and 3D device. (A) Preoperative simulation image. (B) Fabricated 3D device (surgical guide). 3D, three-dimensional.

The extraction was performed in June 2025 under general anesthesia due to the patient’s age and extent of the procedure. The surgical guide was immersed preoperatively in 0.025 w/v% Germitol Water (benzalkonium chloride solution, Maruishi Pharmaceutical Co., Ltd., Osaka, Japan). A horizontal incision was made in the mucolabial fold of the right anterior maxilla and a mucoperiosteal flap was elevated to expose the pyriform aperture rim and anterior wall of the maxillary sinus. With the 3D device held in place using forceps, dissection of the nasal mucosa was limited to the range in which the bone could be safely removed using an ultrasonic cutting instrument. The use of a surgical template resulted in limited damage to the nasal mucosa to the extent necessary to remove a fragment of the outer bone plate using an ultrasonic tool (VarioSurg, NSK-Nakanishi Inc., Tochigi, Japan). After placing the surgical guide and projecting the preoperative simulation image (hologram) onto the surgical field using MR, the position of the impacted tooth and fit of the surgical guide were confirmed. The lateral nasal wall bone was cut using an ultrasonic cutting instrument and removed as a single block. After the crown of the tooth was identified, the tooth was sectioned and removed (Figure 3A-3C). No lacerations of the maxillary sinus mucosa or nasal mucosa, and no injuries to the roots of the maxillary anterior teeth, were observed.

Figure 3 Intraoperative photographs. (A) Positioning of the device. (B) Bone removal. (C) MR projection. (D) Repositioning of the bone segment after extraction. The yellow arrowhead indicates the harvested bone wedge tightly fitted into the gap between the replaced bone segment and the recipient site. MR, mixed reality.

To preserve the postoperative contour of the pyriform aperture rim, when repositioning the bone segment, approximately 1 mm of bone was cut from the posterior nasal side of the segment and harvested, then fitted into the gap between the bone segment removed using the device and the recipient bed (Figure 3D). This method was adapted from the wedge-shaped bone grafting technique described by Güven and modified to be performed using only the harvested bone (4).

Postoperatively, the patient was instructed not to blow his nose to maintain the repositioned bone segment. The patient did not develop postoperative epistaxis, maxillary sinusitis, or other complications. On the panoramic radiograph obtained on postoperative day 1, the osteotomy area was visible. CBCT obtained 3 months postoperatively showed that the osteotomy site was scarcely recognizable, indicating favorable healing (Figure 4A,4B). To evaluate surgical accuracy, preoperative and 3-month postoperative CBCT data were used for image registration. The evaluation was performed using GOM Inspect software (GOM, Braunschweig, Germany). Postoperative CBCT scans were acquired under identical imaging conditions as the preoperative scans. For automated registration, three arbitrary, anatomically stable points that remained unchanged by the surgery were selected. Assessment of the bone surface deviation between the preoperative and 3-month postoperative scans demonstrated that the deviation was less than 1 mm over 100% of the surface area (Figure 5). The patient wished to continue follow-up care at the referring dental clinic, and follow-up at our department was therefore concluded.

Figure 4 Postoperative imaging. (A) Panoramic radiograph on postoperative day 1. (B) Cone-beam computed tomography 3 months postoperatively.

Figure 5 Superimposed preoperative and 3-month postoperative CBCT images used for surgical accuracy assessment. Bone surface deviation analysis revealed a deviation of less than 1 mm over 100% of the surface area. CBCT, cone-beam computed tomography.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient and his guardians for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Impacted supernumerary teeth most frequently occur in the maxillary midline, with a reported incidence of 0.15–1.9% (1). In routine clinical practice, they may be detected incidentally on radiographs obtained for delayed eruptions, positional abnormalities of the permanent teeth, or other dental conditions. Although its etiology remains unclear, several hypotheses have been proposed, including abnormal odontogenesis based on the tooth germ dichotomy theory including hyperactivation of multiple cellular signaling pathways and mutations in the adenomatous polyposis coli (APC) gene (5,6). Most impacted supernumerary teeth are asymptomatic; however, they can occasionally adversely affect the surrounding anatomical structures, including the development of malocclusion (7), root resorption of adjacent teeth (8), and cyst formation (9). Extraction is indicated when the likelihood of such complications is high. Although a unified consensus regarding the optimal timing of extraction is lacking, early removal before 5 years of age may reduce complications and the need for orthodontic treatment (10).

Panoramic and periapical radiographs are commonly used for diagnosis; however, CBCT is useful for understanding the detailed position and orientation of the tooth and its relationship with the adjacent structures, planning the surgical approach, and preventing complications (11,12). In the present case, panoramic radiography alone was insufficient to determine the exact position. CBCT confirmed that the supernumerary tooth was inverted, with the crown directed posteriorly and closely adjacent to the maxillary sinus, pyriform aperture rim, and apex of the right maxillary lateral incisor. Therefore, a labial approach was selected; however, this approach carries the risk of injury to the maxillary sinus mucosa, nasal mucosa, and root of the right maxillary lateral incisor.

Recent evidence indicates that the use of dental CBCT data to fabricate surgical guides via computer-aided design/computer-aided manufacturing (CAD/CAM) and 3D printing can improve surgical precision and safety, and reduce operative time (13-15), and can help with the extraction of impacted supernumerary teeth in the premaxillary region (16). Applying MR to project preoperative simulation images onto the surgical field can enable increased surgical precision (17-19). By combining these technologies, we fabricated a 3 surgical guide limited to the region required to expose the crown of the impacted tooth and projected the simulation data onto the operative field, which helped secure the fit to the bone, while allowing for a smaller incision and more conservative osteotomy.

Güven reported that during articular eminence augmentation for chronic recurrent temporomandibular joint dislocation, oblique osteotomy of the articular eminence followed by insertion of a tightly fitted, wedge-shaped autogenous bone graft resulted in favorable bony union (4). In the present case, we applied this wedge-shaped bone grafting method to the pyriform aperture rim, which enabled early stabilization of the repositioned bone segment and favorable bone healing.

Currently, MR alone may not provide sufficiently reliable registration accuracy in surgery; combined use with CAD/CAM-based guides and/or the development and introduction of new hardware are required to improve registration precision.

In conclusion, the combined use of a surgical guide and MR technology enabled safe and minimally invasive extraction of an impacted supernumerary tooth adjacent to the maxillary sinus and nasal cavity, and wedge-shaped bone grafting helped preserve the contour of the pyriform aperture rim with favorable healing.

Acknowledgments

None.

Footnote

Funding: This work was supported by the Japan Society for the Promotion of Science (No. JP23K16170).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2026-1-0098/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient and his guardians for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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