Orthodontic retreatment of a patient with a severe deep bite and low-level horizontal impaction of the right mandibular second molars by using a custom-cast anchorage appliance and clear aligners: a case report

Abstract

Background

A severe deep bite, when combined with an impacted mandibular second molar, presents a complex clinical challenge. Managing this condition requires not only precise control over tooth movements but also careful consideration of the relationship between the impacted tooth and its adjacent teeth. Orthodontists must conduct a thorough assessment of the patient's condition to develop a rational and feasible treatment plan.

Case presentation

This report discusses a case involving a 24-year-old female patient who requested an orthodontic consultation of “anterior deep overbite”, with a history of previous orthodontic treatment. Cone-beam computed tomography scans revealed parallel, low-level horizontal impaction of her right mandibular second and third molars. After extracting the upper right first premolar and the lower right third molar, a comprehensive treatment plan was initiated, combining clear aligners with a custom-cast anchorage appliance to guide the impacted tooth. Ultimately, the patient's deep overbite was corrected, and the impacted right mandibular second molar was successfully uprighted. A two year follow-up demonstrated stable treatment outcomes, with the impacted tooth exhibiting good periodontal health and normal pulp vitality. The bone condition around the second molar (MM2) was also favorable.

Conclusions

This case suggests that for adult patients with low-level horizontal impaction of the mandibular second molar, using a custom traction appliance with the appropriate force magnitude and direction can yield satisfactory clinical outcomes. Additionally, employing mini-implants in the anterior region as an adjunct to clear aligner therapy can correct a severe anterior deep overbite safely and effectively.

Background

The incidence of impacted teeth ranges from 0.9% to 3.0%, with mandibular third molars and maxillary canines being the most commonly affected [1]. Recently, there have been more reports of impacted mandibular second molars, with an incidence in various populations reported between 0.03% and 2.3% [2–6]. Possible etiological factors include insufficient dental arch length, an anomalous first molar failing to guide the eruption of the second molar, an abnormal eruption angle of the second molar, local pathologies such as cysts or tumors, and genetic factors [2, 4, 7–11].

Currently, there is no standardized treatment protocol for impacted mandibular second molars. Common clinical approaches include the following: Extraction of the impacted second molar, with the expectation that the third molar will either erupt into a normal position spontaneously or be guided into place; extraction of the first molar to create space for the second molar's eruption; extraction of the second molar followed by prosthetic restoration; surgical exposure followed by orthodontic traction; surgical uprighting followed by orthodontic alignment [12–16].

The simultaneous impaction of the ipsilateral mandibular second and third molars is an extremely rare occurrence that poses a significant treatment challenge. Orthodontists must conduct a thorough evaluation of various factors, including the clinical presentation, resistance to coronal movement, the relationship with adjacent teeth, treatment efficiency, long-term stability, and periodontal health, to determine the most suitable treatment method. This approach is essential for enhancing the success rate of orthodontic traction for impacted molars.

Simultaneously, correcting a severe anterior deep overbite presents considerable clinical challenges. Due to the biomechanical properties of clear aligners, their efficiency in correcting deep overbites is limited [17]. In this case, by implanting mini-implants in the anterior region to assist clear aligners, the orthodontic retreatment of this patient with a severe deep bite with an impacted mandibular second molar was completed. This strategy offers a safe, effective, and straightforward approach to managing such complex cases.

Case presentation

Diagnosis and etiology

A 24-year-old adult female presented with the chief complaint of a "deep anterior bite". The patient had received orthodontic treatment at another clinic around eight years prior, during which her upper left first premolar was extracted. She denied any relevant past medical history.

The patient's facial profile was straight. No significant asymmetries were observed upon examination. Intraoral examination and model analysis revealed a permanent dentition, with teeth 24, 31, 41, and 47 missing. The patient displayed a severe deep bite and a deep deep overjet. Crowding was noted as 3 mm in the maxilla and 0.5 mm in the mandible. The maxillary midline was deviated 0.5 mm to the left. The molar relationship was a full cusp distal on the left side. In contrast, the right side displayed a neutral molar relationship, with the canine relationship being a full cusp distal on both sides. Caries were observed on teeth 17 and 46. Examination of the temporomandibular joint (TMJ) indicated no abnormalities, and the general physical examination was unremarkable (Figs. 1 and 2).

Fig. 1.

Pretreatment facial and intraoral photographs

Fig. 2.

Scanned model

Cephalometric analysis indicated a Class II skeletal relationship (ANB: 5.65°), an average growth pattern (MP-SN: 35.55°, FH-MP: 25.49°), retroclined maxillary (U1-SN: 93.15°), and mandibular incisors (L1-NB: 17.66°) (Table 1).

Table 1.

Cephalometric analysis at pretreatment

Panoramic and cone-beam computed tomography (CBCT) revealed low-level horizontal impaction of the right mandibular second (MM2) and third (MM3) molars. The second molar was positioned directly beneath the third molar, with its mesial crown point located 5.6 mm below the distal root apex of the first molar (MM1) and 11.59 mm from the inferior border of the mandible. The highest point of the second molar was approximately 5 mm from the alveolar crest. The bone surrounding the impacted teeth was in good condition with no evidence of root resorption in the first molar. Both MM2 and MM3 were bi-rooted; specifically, the mesial root of MM2 was shorter than its distal root, and its root furcation was less pronounced than that of MM3. The apical foramina of both teeth were closed, and the crown-to-root ratio was approximately 1:1 (Figs. 3 and 4). Ultimately, her final diagnoses included dental impaction, deep overbite, and increased overjet.

Fig. 3.

Pre-treatment radiographs: a Panoramic radiograph. b Lateral cephalogram. c CBCT image of the MM2

Fig. 4.

The highest point of the second molar was approximately 5 mm from the alveolar crest

Treatment objectives

The treatment objectives included:

1. To correct the anterior deep overbite.

2. To align and level the maxillary and mandibular arches.

3. To correct the maxillary midline.

4. To apply traction to and upright the impacted right mandibular second molar.

5. To establish a functional occlusion in the right posterior region.

6. To maintain the patient's existing straight facial profile.

Treatment alternatives

3 alternatives are identified base on the treatment objectives.

• Option 1: Extracting the lower-positioned second molar and applying traction to the third molar using the closed-eruption technique.

The rationale for this option was that the third molar was positioned more occlusally, resulting in a shorter traction path. However, there were several disadvantages: The second molar was low-lying with its roots close to the inferior alveolar canal, increasing the risk of nerve injury and significantly complicating surgical extraction. Additionally, the resulting bone defect would be large, potentially compromising wound healing and even risking pathological fracture. Without the support of the second molar, the third molar may subside and become loosened during traction, increasing the difficulty and risk of failure. A large bone defect distal to the first molar could also negatively affect its periodontal health.

• Option 2: Extracting the third molar, located occlusal to the second molar, and applying traction to the second molar using a closed-eruption technique.

The challenge with this option was the difficulty of achieving good clinical moisture control and successfully bonding an attachment to the exposed distal surface of the horizontally low-impacted second molar after surgical extraction of the third molar. If the attachment were to debond during traction, it would increase the complexity and risk associated with a second surgical procedure. Moreover, because of the low position of the second molar, the traction force would need to be directed occlusally, making it difficult to determine the point of force application. This could lead to the tooth tilting buccolingually during eruption, necessitating constant adjustments to the direction of traction. However, compared to Option 1, this approach would have a lesser impact on the inferior alveolar nerve, result in a smaller bone defect, and provide a better periodontal prognosis. The first molar would not impede the traction path of the second molar, and new bone would form around the second molar as it moved, minimizing any impact on the first molar. Additionally, the second molar has more robust roots, and the required sagittal movement after uprighting would be shorter than that of the third molar, thereby reducing the risk of root resorption.

• Option 3: Extracting both impacted molars and perform an autotransplantation of the tooth with the better root condition. The patient will not have to endure the pain of long-term treatment; however, the associated risks are relatively high.

This option would involve a large bone defect, a long recovery period, and risks of pulp necrosis, inferior alveolar nerve damage, and injury to the first molar.

After thoroughly discussing the advantages and disadvantages of each treatment option, the patient chose Option 2.

To address the patient's crowding, deep overbite, and midline discrepancy, we developed a strategy that involved extracting the upper right first premolar and distalizing the left molars to correct the deep overbite and align the maxillary midline. Given the patient's age, residence, occupation, aesthetic preferences, and periodontal health, the patient preferred treatment with clear aligners.

We considered the possibility of placing a mini-implant in the retromolar area or mandibular ramus to facilitate traction of the second molar. However, a mini-implant becomes immobile once placed, which would not allow for necessary adjustments in the direction of traction during treatment. Additionally, a significant post-extraction defect in the third molar would increase the risk of mini-implant loosening in that area. A loose implant in the mandibular ramus could cause considerable distress to patients. Therefore, we decided not to use the mini-implant option and opted for a custom-cast anchorage appliance bonded to the mandible. To enable dynamic control over the eruption path of the second molar, a splint was designed with multiple traction hooks on the buccal and lingual aspects of its right distal cantilever. This design allowed us to adjust the traction direction according to the tooth's eruption path, ensuring that the crown emerged in the correct position. Recognizing that clear aligners require daily removal and periodic replacement, which offers poor control over impacted teeth and maintains the continuous light force needed for traction, we reached a final comprehensive treatment plan with the patient: The maxilla would be treated with full-time clear aligners (Angelalign Technology Inc.), while the mandible would be fitted with a custom-cast anchorage appliance to apply traction to the second molar (The cast appliance was fabricated from Cobalt-Chromiumalloy, and was subsequently bonded to teeth 34–36 and 44–46. The bilateral components were connected by a lingual bar. Furthermore, the appliance featured one rod, approximately 11 mm in length, extending towards the occlusal aspect of MM2 on both the buccal and lingual sides. The superior end of each rod was equipped with two slender projections, forming a hook-like structure for the connection of the force application mechanism.) (Fig. 5A and B). Once successfully uprighted, a clear mandibular aligner would be used for fine-tuning and retention.

Fig. 5.

A Schematic of the custom appliance. B The custom appliance: The red arrow indicates the location of the hook-like structure

Treatment progress

An intraoral scanner (iTero Element, Align Technologies, San Jose, CA, USA) was used to obtain the 3D digital models of the patient's dentition. The system was used for digital tooth setup, attachment design, and treatment staging. Treatment was divided into two main stages: An initial treatment stage (T0) and a first refinement stage (T1). During treatment, the patient attended follow-up appointments every 1–2 months to monitor oral hygiene, ensure proper alignment of the aligners, and assess the progress of maxillary tooth movement.

Concurrently, a plaster model of the mandibular arch was fabricated to create a custom-cast anchorage appliance. The patient's right mandibular third molar was surgically extracted, and the distal surface of the second molar was exposed. After moisture control and etching were achieved, a lingual button with a traction chain was bonded. The custom-cast anchorage appliance was then immediately secured to the mandible (Fig. 6A). A NiTi coil spring (Shinye Orthodontic Products Co.,Ltd) was connected from the distal cantilever of the splint to the traction chain of the lingual button, passing through the extraction socket to apply a traction force of approximately 100–120 g (Fig. 6B). We utilised a dynamometer to measure the extension of the NiTi coil spring extraorally, specifically determining the length at which the force was within the 100 g to 120 g range, which was then used as a reference to determine the required intraoral stretching distance (Fig. 7). Monthly appointments were scheduled to check the stability of the appliance and monitor the progress of tooth eruption, with the direction of traction adjusted according to the eruption path of the tooth.

Fig. 6.

Photos of selected stages during the treatment process

Fig. 7.

upper: unloaded length of the NiTi coil spring(5 mm); lower: length of the NiTi coil spring under a 110 g tensile force(10 mm)

At the 4^th month of treatment, the distobuccal cusp of the second molar was visible intraorally. Due to limited eruption space caused by the distal cantilever of the splint, the buccal portion of the cantilever was ground down with a high-speed turbine to eliminate the obstruction to the eruption of the second molar (Figs. 6C and 8A).

Fig. 8.

a Panoramic radiograph at the 4^th month, b Panoramic radiograph at the 5th month, c Panoramic radiograph at the 8th month

At the 5^th month, compared with the 4^th month, the panoramic radiograph demonstrated that there was almost no movement of MM2 in the fifth month. It was determined that the splint was likely no longer providing an effective traction force. After discussions with the patient, the custom-cast anchorage appliance was removed, and a fixed appliance was bonded to the mandible to facilitate further uprighting, alignment, and leveling of the arch, using an initial 0.014-inch NiTi archwire (Figs. 6D and 8B).

At the 6^th month, the mesial and distal buccal cusps of the second molar were fully exposed, and the archwire was changed to a 0.016 in NiTi wire (Fig. 6E).

At the 8^th month, the second molar completely erupted with good periodontal attachment (Fig. 6F). Radiographic examination indicated no significant alveolar bone resorption, although bone density at the original impaction site was slightly reduced. The mandibular fixed appliance was then removed, and new intraoral scans of both dental arches were taken to fabricate clear aligners for the first refinement stage (T1). This stage aimed to further align and level the arches, close any remaining spaces, and correct the deep overbite (Fig. 8C).

The total duration of the treatment was 30 months. During the forced eruption of the impacted second molar (MM2), owing to the patient's excellent compliance and effective maintenance of oral hygiene, there were no signs of swelling or infection noted in the mucosa at the MM2 site. Following the uprighting of the second molar, the mandible underwent 22 months of fine-tuning and retention using clear aligners. During subsequent follow-up visits, we closely monitored the condition of MM2. A panoramic radiograph taken at the 21^st month of treatment indicated that the alveolar bone level of MM2 was at the cementoenamel junction. The orthodontic traction of the mandibular second molar was highly successful, with no mobility, normal pulp vitality, no crown discoloration, healthy pink gingiva, and a probing depth of 2 mm (Fig. 9).

Fig. 9.

Upper: panoramic radiograph at the 21^th month, lower: Mandibular dentition photo at the 21^th month

Figure 10 illustrates the traction process for MM2. Figure 10A: at the first month of treatment. Figure 10B: between the 1 st and 4th months of treatment (adjusting the NiTi coil springs to the lingual aspect to prevent MM2 from tilting buccolingually). Figure 10C: at the 5th month of treatment (after 1 month of ground down the buccal portion of the cantilever). Figure 10D: removaing custom-cast anchorage appliance and fitting fixed appliances.

Fig. 10.

The traction process for MM2

Furthermore, Table 2 presents the treatment timing milestones relating to the patient’s treatment course.

Table 2.

Treatment timing milestones

Figure 11 shows a schematic illustration of deep overbite treatment using clear aligners and mini-screws. The mini-screws are placed on the labial aspect of the maxillary anterior teeth and are connected to perforations on the palatal side of the upper aligner with 1/4 inch, 3.5 oz elastics. This setup is designed to prevent lingual tipping during anterior retraction.

Fig. 11.

Schematic diagram of the mechanics for correcting anterior deep overbite using clear aligner therapy with mini-implant anchorage

Treatment results

The orthodontic treatment lasted for 30 months, during which the MM2 was successfully uprighted. It exhibited good pulp vitality and normal gingival health. The maxillary dental midline was aligned with the facial midline, indicating a Class I molar relationship on the left side and a Class II molar relationship on the right. The ratio of the total crown width of the maxillary teeth (16–26) to the mandibular teeth (36–46) was 96.03%. Based on this finding, prioritising midline alignment would have resulted in an unstable bilateral distal cusp-to-cusp relationship. Consequently, we sacrificed the mandibular midline alignment in favour of pursuing a stable occlusion, thereby enabling the bilateral maxillary and mandibular teeth to achieve a stable cusp-to-fossa interdigitation (Fig. 12).

Fig. 12.

Left: Posttreatment facial and intraoral photographs. Right: superimposition of pre- and post-treatment lateral cephalogram

Cephalometric analysis indicated that the initially retroclined maxillary incisors were improved (Table 3). Utilizing anterior mini-implant anchorage as an adjunct to clear aligners enhanced the efficacy of the aligners, allowing for better control of anterior tooth torque. Panoramic and CBCT imaging revealed no significant root or alveolar bone resorption, and the alveolar bone level of MM2 was at the cementoenamel junction (Fig. 13).

Table 3.

Cephalometric analysis at pretreatment and posttreatment

Fig. 13.

Post-treatment radiographs: a Panoramic radiograph. b Lateral cephalogram. c CBCT image of the MM2

The patient expressed satisfaction with the treatment outcome. Overall, an efficient and satisfactory result was achieved.

Discussion

The orthodontic treatment of impacted teeth often faces challenges due to the tooth's position, limited oral space, and suboptimal anchorage conditions. To date, a standardized treatment protocol has not been established.

Current traction methods primarily fall into three categories: Surgical exposure followed by traction assisted by mini-implants; surgical exposure followed by orthodontic traction; surgical uprighting followed by orthodontic alignment.

While some studies indicate that surgical uprighting of impacted molars followed by orthodontic treatment can have favorable outcomes [16], this method is uncommon due to its high surgical difficulty and poor positioning accuracy. For a severely low-impacted MM2 as in this case, surgical uprighting would necessitate significant bone removal, which poses a higher risk of damaging the inferior alveolar nerve than orthodontic traction. A significant advantage of orthodontic traction is that the physiological bone remodeling that occurs as the tooth moves through the alveolus helps to maintain periodontal health and stability, thereby enhancing the success rate of the treatment [13, 19]. In this particular case, after eight months of treatment, the mesial and distal alveolar bone height of MM2 was apical to the cementoenamel junction. However, this bone recovered to the level of the cementoenamel junction by the 21 st month, and the bone height remained stable at the 30th month. This evidence suggests that continuous bone remodeling took place during the traction process, restoring the bone level to normal once the tooth reached a stable position. The excellent periodontal condition of MM2 after establishing occlusion indicates that adult patients with fully developed roots can also experience beneficial alveolar bone remodeling following orthodontic traction of an impacted tooth.

Some clinicians have reported successful use of mini-implant anchorage in the retromolar area and mandibular ramus to move mesially-inclined impacted molars [15, 20, 21]. However, the placement of mini-implants is an invasive procedure that can cause anxiety in patients and reduce their compliance. Additionally, mini-implants provide a unidirectional force, and some studies have indicated that the root of an impacted MM2 may move lingually during traction [22]. The finding by Zhou-Xi Ye et al. that the coronal resistance of a low-impacted tooth is greater than its apical resistance might explain this occurrence [22]. A unidirectional force cannot adequately control the direction of the traction or the eruption path of the crown. In cases of an impacted MM2 with an existing lingual root inclination, the risk of the root contacting the cortical plate during traction increases, potentially leading to root resorption or even traction failure. Furthermore, mini-implants carry the risk of loosening and dislodgment, which would require re-implantation, thereby reducing the success rate and increasing patient discomfort. To address these issues, we designed a custom-cast anchorage appliance. This non-invasive device allows for flexible adjustment of the traction force direction. Even if the splint debonds, it can be quickly and non-invasively reattached, avoiding the drawbacks associated with mini-implant traction. This improves the efficiency of traction and patient cooperation.

In terms of surgical exposure techniques, the open-eruption method has advantages, such as reduced coronal resistance, easier monitoring of tooth movement, and re-bonding of attachments. However, its disadvantages include the tendency for plaque accumulation and the potential for inflammation of periodontal tissues. The closed-eruption technique, which does not allow for the direct visualization of tooth movement, causes less damage to periodontal tissues and facilitates better oral hygiene [23, 24]. The choice of technique should depend on the specific clinical situation. In this particular case, the low position of MM2, with the distal aspect of the crown 5 mm below the alveolar crest, made the open-eruption technique highly traumatic and likely to lead to food impaction. Therefore, we opted to use a closed eruption technique. Ultimately, the tooth erupted in the correct position through the attached gingiva, similar to natural eruption. This approach resulted in good post-operative periodontal attachment, no infection, and an excellent final gingival contour and periodontal condition.

For the choice of force-delivery system, studies have revealed that elastomeric chains can lose over 10% of their force within the first hour, reaching 64.8% after four weeks. In contrast, the NiTi springs exhibit a force decay of only approximately 15.2% over four weeks. In comparison, the NiTi coil springs provide a more continuous and gentle traction force [19, 25, 26]. At follow-up appointments, adjusting the force with NiTi coil springs is simpler and more convenient, which streamlines the clinical procedure and reduces patient discomfort. Consequently, we chose to use the NiTi coil springs for traction in this case.

The optimal time for treating an impacted second molar is between 11 and 14 years of age, before the roots are fully developed [18]. A study by Sawicka M et al. also found that younger patients have a higher success rate and better prognosis for the traction of impacted teeth [27, 28]. Although the patient's MM2 roots were fully formed, a successful outcome was still achieved, attributable to her good bone-forming capacity and excellent treatment compliance.

A study by Michele Cassetta et al. on the axial inclination of impacted second molars found that mesial impaction is the most common, with an average angle of + 34.77°, while distal impaction is less frequent and vertical impaction is the rarest [2]. For individuals with a family history of MM2 impaction, closer monitoring of its eruption is recommended. If a mesial inclination of the second molar is detected early, timely intervention to remove potential etiological factors is crucial to ensure its normal eruption or to reduce the difficulty and failure rate of later treatment.

MM2 impaction can cause distal bone defects and root resorption in MM1. D.J. Witter et al. found that individuals with incomplete dentition have a higher risk of developing temporomandibular disorder (TMD) symptoms [13, 29]. The lack of partial occlusion due to impacted MM2 may harm the TMJ. We speculate that this may be due to the supra-eruption of the opposing tooth, which creates occlusal interference and thereby increases the risk of TMD.

Wenli Lai et al. classified the difficulty of clear aligner cases into simple, moderate, and difficult, with a severe deep bite categorized as a difficult case [30]. This is likely because the mechanical properties of the aligner material and individual patient variations can lead to significant discrepancies between the actual and intended tooth movements when controlling anterior tooth torque and correcting a deep overbite. In this case, two mini-implants were placed between the maxillary central and lateral incisors. A vertical force was applied by instructing the patient to replace the elastics connecting the implants to the aligner daily. This strategy enhanced the expression rate of the clear aligner, ultimately achieving effective controlled intrusion of the anterior teeth and successful correction of the deep overbite.

Mampieri G et al. achieved favourable outcomes using a combination of clear aligners and elastic traction to guide bilateral impacted canines into the dental arch and align them [31]. However, this approach was not suitable for the present case, as our patient presented with a distal free-end impacted MM2. If this method were to be employed, the free end of the aligner would undergo significant deformation. Furthermore, the traction force would be interrupted whenever the patient removed the aligner, making it challenging to maintain persistent and stable force delivery. This would subsequently increase the traction duration required for the MM2. The cast framework, conversely, is highly suitable for the traction of such distal free-end impacted teeth.

In this case, the patient presented with maxillary extraction space loss on the left side from her first orthodontic treatment, necessitating the distalisation of the molars to improve the molar relationship. Clear aligner therapy offered distinct advantages over fixed appliances for this approach.In the mandible, the treatment utilised a custom-cast anchorage appliance and NiTi archwire to assist in the forced eruption of the impacted tooth, resulting in the complete uprighting and levelling of the lower right second molar within eight months. This effectively overcame the issue of inadequate control associated with clear aligners during the traction of distal free-end impacted teeth. Furthermore, the patient transitioned to clear aligners for the retention phase, which afforded the additional benefits of aesthetics, comfort, and enhanced oral hygiene maintenance. The successful outcome of this case demonstrates that hybrid mechanics not only provide precise control and highly efficient tooth movement but also elevate the feasibility of successful treatment for complex cases.

To improve the clinical efficiency of impacted teeth treatment, personalized appliance design based on the tooth's position, depth, and required traction direction should be considered. The tooth-supported, distal cantilever, occlusally directed, custom-cast anchorage appliance used in this study, which provides multi-directional and adjustable traction, successfully uprighted the horizontally impacted MM2. By using NiTi coil springs to deliver a continuous and gentle force, the clinical traction was simplified and successfully uprighted the horizontally impacted MM2. This offers an effective treatment option for such cases.

The limitations and areas for improvement in this case are as follows:

1. When designing the custom-cast anchorage appliance, a bracket could have been welded to the buccal aspect of the cast band. Subsequently, it would only be necessary to remove the distal cantilever traction device on tooth 46 and install an archwire to achieve uprighting and occlusion of the second molar. This could avoid the discomfort associated with bonding a fully fixed appliance for the patient, thereby improving the clinical experience.

2. Sagittal target positioning for the maxillary posterior teeth was not sufficiently precise, which increased the number of clear aligner stages and prolonged the overall treatment duration. In future treatment designs, the accuracy of tooth movement targets and stepwise planning should be enhanced to improve clinical treatment efficiency.

Conclusions

1. The custom-cast anchorage appliance employed in this case could be used to safely and efficiently apply traction to severely low-level horizontally impacted mandibular molars.

2. The use of anterior mini-implants as an adjunct to clear aligner therapy can effectively correct severe deep overbites.

3. For complex cases, a thorough assessment of all patient problems and careful selection of an individualized treatment plan are crucial to improve the probability of a successful outcome.

Abbreviations

MM1

Mandibular frist molar

MM2

Mandibular second molar

MM3

Mandibular third molar

TMD

Temporomandibular disorder

Authors’ contributions

Rongqi Xia analyzed and interpreted the patient’s data and and wrote the manuscript. Ting Hu collaborated on the analysis of the data, sorted the pictures and footage and wrote the manuscript. Lingjun Guan performed the major patient clinical operations, provided some of the patient's photos and described them. Liren Chen, Shu Liang and Yingcong Xiong joined the discussion and offered some advice. Fen Yao and Zhengyu Liao proposed and agreed with the patient clinical treatments and performed major patient clinical operations. Both of the two corresponding authors have made equally significant contributions to the work and share equal responsibility for it. All the authors have read and approved the final manuscript.

Funding

This work was funded by the grants from:

1. Jiangxi Province Natural Science Foundation 20232BAB206079.

2. Jiangxi Provincial Health Commission Health Technology Program 202310040.

3. Jiangxi Provincial Research Programme on Teaching Reform in Higher Education JXJG-22-1-19 = -42.

Data availability

Data sharing is not applicable to this article as no datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

The study participant provided written informed consent.

Consent for publication

Written informed consent for the publication of clinical details and clinical images was obtained from the patient prior to the study. All authors have approved the manuscript for submission.

Competing interests

The authors declare no competing interests.