Orthodontic extrusion splint for third molar of lower jaw

Abstract

FIELD: dentistry.SUBSTANCE: intended for use in increasing the distance between the lower third molars and the mandibular canal when they are located close to the inferior alveolar nerve. For orthodontic extrusion of the third molar of the lower jaw, a splint is used, made using a hardware method of three-dimensional visualization of the internal structures of the oral cavity, which produces a digital 3D model of the upper and lower jaws. The central relationship of the jaws is determined using software and a custom 3D model is created, which is printed on a 3D printer, and a custom splint is pressed onto it using a vacuum former using polyurethane or polyethylene terephthalate glycol plates. In this case, on the outer surface of the splint in the area of the third or second molars of the upper jaw, a hook in the form of an orthodontic button with a width of 2–4±1 mm and 3–5±1 mm in height is installed, while the hook has a vestibular, palatal or distal position, determined from the direction of displacement of the lower third molar.EFFECT: use of a splint, by increasing the distance between the third molar of the lower jaw and the mandibular canal, eliminates the risk of injury to the mandibular nerve during classical surgical removal.1 cl, 2 dwg, 2 ex

Description

[0001] The invention relates to medicine, namely to dentistry, and is intended to increase the distance between the lower third molars and the mandibular canal when they are located close to the inferior alveolar nerve.

[0002] Using a 3D hardware visualization of the internal structures of the oral cavity, a digital 3D model of the upper and lower jaws is obtained, and software automatically determines the centric relationship of the jaws. A customized 3D model is then developed using a specialized computer program. The model is then 3D printed, and a custom mouth guard is pressed onto it, precisely replicating the anatomy of the alveolar process of the upper jaw. The mouth guard is manufactured using a vacuum former using rigid polyurethane or polyethylene terephthalate glycol plates. A hook, shaped like an orthodontic button, is simultaneously fabricated on the outer surface of the mouth guard in the area of ​​the upper third molars, or in the area of ​​the upper second molars if these are absent. The hook size varies from 2-4 mm in width and 3-5 mm in height.The position of the hook is designed in advance during digital modeling of the mouthguard, depends on the required direction of displacement of the lower third molar, and can have a vestibular (buccal), palatal and distal (behind the last tooth) position.

[0003] The invention relates to medicine, namely to dentistry, and is intended to increase the distance between the lower third molars and the mandibular canal when they are located close to the inferior alveolar nerve.

[0004] One of the pressing problems in modern dentistry is the need to remove third molars, since the eruption of an impacted third molar of the lower jaw is often unpredictable.

[0005] The removal of mandibular third molars, or wisdom teeth, is one of the most common procedures in dental practice. This is because, if the direction of eruption of the mandibular third molars is incorrect, the force generated during root formation is transmitted to adjacent teeth. This can cause root resorption, rotation, and mesial displacement of the first and second permanent molars

[12] .

[0006] Furthermore, malpositioned wisdom teeth often lead to crowding of adjacent teeth, especially in patients with limited space in the lower jaw. Therefore, wisdom teeth extraction may be necessary to prevent crowding [9].

[0007] Before removing the lower third molars, it is necessary to evaluate the presence of factors such as tooth retention, horizontal position of the tooth, low occlusion of the tooth in relation to the adjacent molar, narrow retromolar space, proximity of the tooth to the inferior alveolar nerve, and its spatial relationship with adjacent tissues.

[0008] Often, tooth extraction surgery leads to complications in the form of postoperative traumatic neuropathy of the inferior alveolar nerve [5, 10, 11].

[0009] In some cases, extraction of the third molar of the lower jaw may be complicated by anatomical features of the structure of the lower jaw, such as proximity to the inferior alveolar nerve.

[0010] Clinicians have proven that in 20-30% of patients, the third molars of the lower jaw are located close to the mandibular canal, which increases the risk of damage to the mandibular nerve when they are removed [1, 2].

[0011] During the process of removing the third lower molars located near the mandibular canal, the following complications may arise:

[0012] 1. Paresthesia is a sensation of numbness or tingling caused by nerve damage. Paresthesia most commonly occurs in the lower lip, chin, and lower teeth [6];

[0013] 2. Hypoesthesia - decreased sensitivity, which may be temporary or permanent depending on the degree of nerve damage [7];

[0014] 3. Anesthesia - complete loss of sensitivity in the area innervated by the mandibular nerve, including the lip, chin, and teeth. This complication may be temporary, but in some cases becomes permanent

[10] ;

[0015] 4. Dysesthesia - painful or unpleasant sensations, such as burning or tingling, in the area of ​​the damaged nerve [3, 4, 8];

[0016] 5. Neuralgia is a severe nerve pain that occurs after nerve damage, which can be very painful and require long-term treatment [3, 8, 11].

[0017] The relevance of this problem is further emphasized by the fact that complications during and after lower molar removal significantly deteriorate patients' quality of life. It has been established that when pain increases to 100%, quality of life decreases by an average of 60% [5].

[0018] Thus, the possibility of excluding injury to the mandibular nerve during the removal of the third molar of the lower jaw is pathogenetically justified.

[0019] Of the known orthodontic methods for displacement of third molars, the most common are the following:

[0020] 1. Mini screws

[13] .

[0021] Disadvantages:

[0022] - installation of a mini-screw may not be possible due to the anatomical features of the body;

[0023] - micro-implants are often factors in traumatizing the oral mucosa;

[0024] - disintegration (rejection of the mini-screw from the jaw bone tissue) of the mini-screw may occur.

[0025] 2. Bracket - system [14, 15, 16].

[0026] Disadvantages:

[0027] - risk of displacement of supporting teeth;

[0028] - violation of aesthetics;

[0029] - risk of enamel demineralization and injury to the oral mucosa.

[0030] 3. Method of traction (extraction from the socket) of the third lower molar using a removable appliance.

[0031] The disadvantages of this method are aesthetic disturbances and labor-intensive manufacturing

[17] .

[0032] Advantages of our method:

[0033] - removable design, which does not affect the diet and does not impair oral hygiene,

[0034] - the entire row of teeth is used for support, which reduces the collateral displacement of the supporting teeth;

[0035] - the mouth guard is transparent and inconspicuous, which makes it more aesthetically pleasing and convenient to use;

[0036] - more functional compared to other methods - the tooth can be moved in different directions simultaneously, due to the installation of several fasteners on the cap;

[0037] - the mouth guard can be used for chronic diseases that prevent the installation of other structures, for example, diabetes.

[0038] - due to its design features, it does not injure the oral mucosa.

[0039] The problem, which is aimed at solving by the application of the proposed method, is to improve the method of moving the third molars of the lower jaw before their removal based on the variable anatomy of the relative position of the roots of impacted teeth and the mandibular canal in order to reduce the risk of injury to the mandibular nerve.

[0040] The solution to the problem is provided by using a treatment method using a cap.

[0041] The result of using the claimed method is an increase in the distance between the third molar of the lower jaw and the mandibular canal in order to eliminate the risk of injury to the mandibular nerve during classical surgical removal.

[0042] The essence is a method of treatment, characterized in that it is carried out in several stages, namely:

[0043] Using a 3D hardware visualization method to visualize the internal structures of the oral cavity, a digital 3D model of the upper and lower jaws is obtained, and software automatically determines the centric relationship of the jaws. A customized 3D model is then developed using a specialized computer program. The model is then 3D printed, and a custom mouth guard is pressed onto it, precisely replicating the anatomy of the alveolar process of the upper jaw. The mouth guard is manufactured using a vacuum former using rigid polyurethane or polyethylene terephthalate glycol plates. A hook, shaped like an orthodontic button, is simultaneously fabricated on the outer surface of the mouth guard in the area of ​​the upper third molars, or in the area of ​​the upper second molars if these are absent. The hook size varies from 2-4 mm in width and 3-5 mm in height.The position of the hook is designed in advance during digital modeling of the mouthguard, depends on the required direction of displacement of the lower third molar, and can have a vestibular (buccal), palatal and distal (behind the last tooth) position.

[0044] A clinical case implemented using a mouth guard.

[0045] A 20-year-old female patient (undergoing treatment from 01 / 19 / 2024 to 05 / 29 / 2024) came to the clinic for a consultation with an orthodontist on the referral of a dental surgeon with the aim of displacing tooth 4.8 from the mandibular nerve.

[0046] Objectively:

[0047] The relationship of the dental arches is Class 1 on the right, Class 2 on the left. Narrowing of the upper and lower dental arches. Tooth 3.6 is missing. Crowding in the anterior group of teeth on the upper and lower jaws.

[0048] Diagnosis: K07.2 Anomaly of the relationship of the dental arches. K07.3 Anomaly of the position of the teeth.

[0049] CBCT (cone beam computed tomography) revealed contact between the mesial-buccal root of tooth 4.8 and the mandibular nerve (Fig. 1).

[0050] Treatment:

[0051] A decision was made to eliminate contact between the tooth root and the nerve.

[0052] First visit: photo protocol, consultation and oral cavity scanning.

[0053] Second visit: On the day of surgical access, an orthodontic button with a hook was placed in the area of ​​tooth 4.8. Attachments were placed on the buccal surfaces of teeth 1.4; 1.5; 1.6; 1.7; 2.6. A mouth guard was issued for the upper jaw. A 5-link chain was attached from the button on tooth 4.8 to the mouth guard attachment on the palatal surface of tooth 1.7.

[0054] The patient was given the following recommendations:

[0055] 1. Wearing the mouth guard for 22 hours.

[0056] 2. Remove the chain and mouth guard while eating and brushing your teeth.

[0057] 3. Every two weeks, the end of the chain must be shortened by one link.

[0058] Third visit: a 5-link chain was replaced from the button on tooth 4.8 to the attachment on the cap in the palatal surface area of ​​tooth 1.7.

[0059] Visit 4: CBCT was performed to evaluate the tooth movement dynamics (Fig. 2).

[0060] A cone-beam computed tomography scan revealed positive dynamics in the displacement of tooth 4.8 relative to the mandibular canal. A decision was made to extract tooth 4.8.

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