Precision Extraction of Lingual Mandibular Supernumerary Teeth Using Dynamic Navigation and High-Speed Handpieces: A Case Report

Introduction

The term “supernumerary tooth” refers to teeth in excess of the normal number of teeth and can occur in either the primary or permanent dentition. Seventy-five percent of super-numerary teeth are impacted, while the rest are partially or fully erupted [1]. The embedded type of supernumerary teeth can cause delayed eruption of permanent teeth, dental crowding, tooth root resorption, and even cranial and maxillofacial deformity [2]. Surgical removal is typically necessary for supernumerary teeth, which is one of the most prevalent dental anomalies. Currently, a variety of instruments are available for this purpose, including pneumatic dental handpieces [3], ultrasonic osteotomes [4,5], and dental lasers [6]. The advent of minimally invasive and patient-friendly surgical techniques has led to the gradual incorporation of digital positioning guides [7,8], virtual and simulation technologies [12–14], and intraoperative navigation into tooth extraction procedures [9–13]. Despite these advances, several challenges persist. For instance, pneumatic dental handpieces cannot precisely locate the tooth that needs to be sectioned during surgery, relying heavily on the surgeon’s skill. This presents a significant challenge for novice surgeons, potentially resulting in damage to the inferior alveolar nerve or even necessitating abandonment of the extraction. While ultrasonic osteotomes and lasers can reduce the risk of nerve injury during bone removal or tooth sectioning, their low cutting efficiency prolongs the surgery, thereby increasing patient discomfort and the risk of postoperative infection. However, it is difficult to remove the impacted supernumerary tooth due to unclear surgical vision, small operating space, and surrounding important anatomical structures, such as the maxillary sinus, nasal cavity, inferior alveolar nerve, lingual nerve, mental nerve, and adjacent tooth root. Therefore, precise operations are required to prevent iatrogenic injury to important anatomical structures and improve postoperative healing.

The modern dynamic navigation system (DNS) was first applied in neurosurgery, with three-dimensional visualization, preoperative virtual design, and precise real-time dynamic tracking. It was not until 1995 that DNS was finally used in dental clinics, mainly in craniomaxillofacial fractures and orthognathic surgery and later in root canal treatment and oral implant surgery [14]. This DNS has expanded its application and may become an essential tool for various procedures, enhancing safety and predictability [15]. Guo et al first removed the mandibular third molar under DNS, and then Emery et al performed 25 cases of extraction of complex mandibular third molars under dynamic navigation, improving visualization and localization, and control during osteotomy, decreasing surgical time [13,16]. Wang et al found that DNS can provide higher localization accuracy and reduced bone trauma for extracting supernumerary teeth [17,18]. However, the aforementioned DNS still has certain limitations, as its main function is preoperative surgical design and intraoperative precise positioning, playing a role in surgical exploration and guidance.

In this case, we fully matched and combined the dynamic navigation system and the high-speed contra-angle handpiece to achieve real-time dynamic visualization of the entire surgical process. We found that DNS-assisted extraction of a supernumerary tooth is more accurate, less invasive, requires less surgical time, and is more comfortable for the patient.

Case Report

PATIENT INFORMATION AND DIAGNOSTIC ASSESSMENT:

A 22-year-old female patient visited our department for assessment and management of unerupted third molars. An initial cone beam computed tomography (CBCT, HiRes3D, LARGEV, China) scan was obtained. Radiographic and clinical examinations showed the presence of an impacted supernumerary tooth on the left lingual side between the root of the lower second premolar and the lower first molar and bilateral lower impacted third molars. The patient agreed to have these teeth removed during multiple appointments. Thus, a dynamic surgical navigation system was recommended to extract an impacted supernumerary tooth (Figure 1).

PREOPERATIVE PREPARATION:

The workflow of the dynamic navigation system (DHC-DI2, Dekaier, China) was as follows. 1) A U-shaped tube with radiopaque markers was affixed onto the supernumerary tooth side of the lower jaw using a silicone rubber impression material, followed by a CBCT image acquisition. 2) CBCT image data reconstruction and preoperative surgical planning on DNS were performed using DCARER implant design software. The teeth and jaw bone were reconstructed in 3 dimensions (3D) by importing CBCT image data (Figure 2A), followed by labeling the inferior alveolar nerve, and then we selected virtual implants to label the root and supernumerary tooth positions and axes (Figure 2B, 2C). If the adjacent tooth root is too thick, calibration can be done by adjusting the safe distance of the implant, which can help identify and provide safety suggestions during the surgical operation process (Figure 2D–2H). 3) We performed instrument calibration and spatial registration, calibrating the high-speed contra-angle handpiece (NSK, Japan) and registering the locator based on spatial markers by emitting infrared light to the detection camera [14].

SURGICAL PROTOCOL OF IMPACTED SUPERNUMERARY TOOTH EXTRACTION:

After disinfecting the patient’s oral cavity, local infiltration anesthesia was performed using Primacaine. We designed 33 to 36 lingual gingival triangular flap incisions, and after anesthesia took effect, we opened the flap along the designed incision to thoroughly expose the surgical area (Figure 3A–3C). DNS assisted in the precise localization of supernumerary tooth (Figure 3D, 3E). Due to the supernumerary tooth being located between the roots of the left mandibular second premolar and first molar, the surgeon used a high-speed contra-angle handpiece to gradually and accurately remove the bone overlying the supernumerary tooth to avoid root damage under real-time DNS guidance (Figure 3F–3I). Then, the surgeon extracted the supernumerary tooth using a surgical elevator (Figure 3J). Finally, the tooth extraction socket was cleaned and rinsed with normal saline, and the gingival flap was sutured (Figure 3K, 3L).

FOLLOW-UP AND OUTCOMES:

The entire operation took about 15 minutes. The patient felt good and did not experience discomfort. After the surgery, she was prescribed anti-inflammatory and analgesic drugs and instructed to rinse her mouth 24 hours later.

In the subsequent follow-up 24 hours later, there was mild pain in the surgical area and no obvious redness or swelling at the wound. After 2 days, the pain had disappeared. The sutures were removed 1 week following the operation. Six months after surgery (Figure 4), the wound had healed well without complications such as adjacent teeth or nerve damage.

Discussion

Supernumerary teeth (STs) are defined as extra teeth in the jaw, with a prevalence rate of 0.1% to 1% of the population [19]. STs can appear anywhere in the oral and maxillofacial region, but the incidence of STs is significantly higher in specific regions, with the highest incidence in the maxillary incisor region, followed by the maxillary third molar, and mandibular molar, premolar, canine, and lateral incisor regions. In permanent dentition, the incidence of STs in males is twice that of females, but it is not significantly different by sex in deciduous dentition [20].

The proximity of deeply horizontally impacted teeth to the roots of adjacent teeth and critical anatomical structures presents a significant risk of damage during surgical procedures [21,22]. Preoperative imaging, typically through panoramic radiographs [3] or cone beam computed tomography (CBCT), is essential for determining the position of the impacted tooth. However, these modalities do not facilitate real-time assessment of the relationship between the high-speed dental handpiece and critical anatomical structures during surgery. This limitation poses a considerable challenge, particularly for impacted teeth that are adjacent to or overlapping vital anatomical structures. Consequently, to minimize the risk to these adjacent teeth and structures, surgeons often need to enlarge the surgical flap and increase the extent of bone removal. These measures, while protective, invariably prolong the duration of surgery and exacerbate postoperative complications, including pain, swelling, and bleeding, and lead to extended healing times [23–25]. Currently, virtual and simulation technologies are more commonly applied in clinical teaching to improve the precise repositioning of impacted teeth in 3D, although their practical clinical application still needs further optimization [10,26].

A systematic review and meta-analysis of clinical studies concluded that DNS achieved greater accuracy compared to the freehand approach, while showing comparable accuracies to static guidance in terms of platform deviation, apical deviation, and angular deviations [27].

In some cases, a digital guide plate was used to precisely extract impacted ST in the maxillary anterior region [19]. The use of digital guide plates for extraction of impacted ST is a good strategy, but it still cannot provide real-time dynamic guidance throughout the entire process. In previous reports, DNS-guided extraction of STs provided accurate and dynamic localization, but it still has certain limitations [17,18]. To improve real-time dynamic visual DNS guidance for the extraction of STs, we combined the DNS with a high-speed contra-angle handpiece and matched hardware and software. In this case, precise localization and bone removal were performed under DNS guidance throughout the entire process to avoid injuring the roots of the left mandibular second premolar and first molar. In addition, based on implant design software for preoperative design of STs extraction, the position and axial direction of adjacent teeth and the inferior alveolar nerve were marked, and a safe distance was set for intraoperative safety reminders. Finally, the surgical time was effectively decreased, and the operation was more precise, less invasive, and more comfortable.

Increased surgeon experience and continuous advances in oral surgical instruments synergistically enhance the process of extracting impacted teeth; however, the use of DNS in surgery offers several distinct advantages, particularly for experienced surgeons. DNS enhances confidence during complex procedures by providing 3D visualization of the surgical site, leading to a better understanding of anatomical structures. Compared to traditional methods, DNS significantly reduces the need for repeated X-rays, thereby lowering radiation exposure for both the patient and the surgical team. Additionally, DNS often includes features for recording the procedure, which can be valuable for educational purposes, postoperative analysis, and improvement of future surgical techniques. However, the use of DNS is not without limitations. It involves higher costs and requires additional time for presurgical planning. There is an initial learning curve associated with its use, and the optical array can be interfered with by the surgeon or assistants during surgery.

Conclusions

The dynamic navigation system coupled with high-speed contra-angle handpiece for the extraction of supernumerary teeth is a personalized, digitally-driven, precise, minimally invasive, and efficient treatment approach.