RU2840602C1 - Method for positioning mandible - Google Patents

Abstract

FIELD: medical science.

SUBSTANCE: invention refers to medicine, namely to orthopaedic dentistry and orthodontics. Method of mandibular positioning includes the following stages. Therapeutic position of the mandible is determined in a patient, and the found position is recorded with an intraoral scanner. Occlusal onlays are modelled on masticatory surfaces of the first upper and lower molars in the found jaw relation in a computer program for simulating dental structures in such a way that provides a tight fissure-tubercle contact compensating deocclusion. Digital 3D image of the occlusal straps is transformed into a physical one by 3D printing. Structural material used is a photocomposite resin which contains oligourethane methacrylate, oligourethane diaacrylate, 2-hydroxyethyl methacrylate, bisacylphosphine oxide and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, with the following ratio of components, wt.%: oligourethane methacrylate 20-62, oligourethane diacrylate 30-50, hydroxyethyl methacrylate 5-30, bisacylphosphine oxide 1-3, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide 1.98-3, thiophene dibenzoxazole 0.02-0.1. Occlusal onlays are subjected to post-printing treatment, final polymerisation and fixed in the patient’s oral cavity on the light-curable composite dental material.

EFFECT: positioning of the lower jaw at the stages of orthopaedic rehabilitation in the patients with temporomandibular joint diseases and masseter hypertonia is ensured by using the long-wear occlusal onlay with improved mechanical properties.

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Description

Field of technology to which the invention relates

The invention relates to medicine, namely to orthopedic dentistry and orthodontics, and can be used to position the lower jaw in a therapeutic position at the stages of complex orthopedic rehabilitation.

State of the art

Today, complex orthopedic dental rehabilitation of patients includes a number of areas, such as therapeutic sanitation, changing the position of teeth in the dental row by means of orthodontic devices, dental implantation of lost teeth and dental prosthetics. Both at the initial stage of rehabilitation and at the final one, the key biomechanical aspect that must be observed is the correct position of the lower jaw in relation to the upper and the interalveolar height. Quite often, the posterior (distal) position of the lower jaw is noted during diagnostics. Total prosthetics of the patient in the specified position of the jaw leads to the development of diseases of the temporomandibular joint, defects of hard dental tissues and the development of traumatic periodontitis.

The lower jaw can be displaced distally by increased tooth wear, missing or lost teeth, deformations of the dental arches, as well as incorrect previous prosthetics or orthodontic treatment. The lateral pterygoid muscles, at the moment of tight closure of the dental arches in the final phase of the lower jaw movement, take it to a new position, which is called forced (adapted). Over time, the muscles "remember" the new position [Lisitsyna, A. Yu. Efficiency of using an individual mouth guard for muscle deprogramming [Electronic resource] / A. Yu. Lisitsyna // Actual problems of modern medicine and pharmacy - 2017: collection of materials of the LXXI Int. scientific and practical. conf. of students and young scientists, Minsk, April 17-19, 2017 / edited by A. V. Sikorsky, O. K. Doronina. - Minsk: BSMU, 2017. - P. 1041-1044]. For unimpeded movement of teeth in the dental row during orthodontic treatment, a necessary condition is the separation of the dental arches. In order to start the process of bite separation, it is necessary to install a rigid and hard overlay, which prevents the jaw from closing completely and helps the muscles to relax. As a rule, it is made of a composite material that is non-toxic and has hypoallergenic properties. With the help of a filling compound, the overlay is fixed on the lateral teeth and visually looks like a tubercle. Treatment of patients with a forced position of the lower jaw today involves a whole range of measures, the leading place among which is occupied by muscle relaxation therapy and therapy using dental arch separating caps (splints) (Persin L.S., Sharov M.N. “Dentistry and neurostomatology. Dysfunctions of the dental system”, Moscow, “GEOTAR-Media”, 2013, - P. 237-252).

They are understood as a removable orthodontic device fixed to the upper or lower dental row in order to separate the dental rows and set the lower jaw in the correct position. In this case, the kappa can be made using various methods and technologies in accordance with the recommendations of various authors. It should be noted that there are no recommendations for aligning the position of the teeth.

The prior art discloses a method for treating dentoalveolar anomalies in patients with a forced position of the lower jaw using elastomeric positioners, which determines and records the position of the lower jaw by relaxing the masticatory muscles using transcutaneous electrical neurostimulation and confirms the achieved result using electromyography of the masticatory muscles (Patent of the Russian Federation 2700987, published on 24.09.2019). Impressions are taken, a bite-separating splint made of base plastic is manufactured according to the obtained registration, and applied to the lower dentition. The splint is used for 2 months to adapt the masticatory muscles to the new position of the lower jaw. Impressions are taken to manufacture and fix occlusal pads on the molars of the upper and lower jaws with alignment of the occlusal plane. Impressions are taken from the upper and lower jaws to manufacture elastomeric positioners. The upper and lower teeth are aligned using elastopositioners and the premolars are brought into contact. The occlusal pads are ground off the molars and impressions are taken again from the upper and lower jaws to make new elastopositioners. The molars are brought into contact using elastopositioners.

The disadvantages of this method are: low accuracy of jaw positioning, associated with a large number of compression impressions at various stages of treatment; the use of removable orthodontic equipment - an elastic positioner, due to which the rehabilitation period increases; the absence in the technology of the final stage of fixation of the treatment performed using the built-up occlusion of the dental arches, characterized by multiple fissure-tubercle contact.

A method for treating dentoalveolar anomalies in patients with dysfunctions and arthrosis of the temporomandibular joints and parafunctions of the masticatory muscles is known (Patent RU 2561870, published on 10.09.2015). The position of the lower jaw is determined and registered. Based on the obtained registration, a bite-separating mouthguard is made and applied to the lower dentition, which is used for 2 months. The bracket system is fixed to the upper dentition. The mouthguard is ground in accordance with the change in the position of the teeth of the upper jaw. The mouthguard is removed and occlusal pads are installed on the chewing surface of the lateral teeth of the lower jaw, and a partial bracket system is installed on the anterior group of teeth of the lower jaw in order to align their position. The occlusal pads are removed from the chewing surface of the lower premolars after the position of the anterior lower teeth is corrected. A bracket system is installed on the lateral teeth of the lower jaw. Using an orthodontic arch and intermaxillary elastic ligatures, the lower premolars are brought into contact with the upper premolars. The occlusal pads are removed from the chewing surface of the lower molars and brought into contact with the upper molars using intermaxillary ligatures.

The closest to the claimed method is a method for eliminating distal occlusion of the dentition, including conducting instrumental studies of the patient's dentoalveolar system (Patent RU 2825047, published on 19.08.2024). Based on the research results, a virtual spatial relationship of the jaws is formed and dentures are modeled, digital models of the jaws are fixed in a virtual articulator until the incisors contact. Individual occlusal pads are modeled on the chewing surface of the first and second molars of the upper and lower jaws in such a way as to ensure tight fissure-tubercle contact, compensating for disocclusion. Virtual models of occlusal pads are converted into physical ones and fixed in the oral cavity. A fixed bracket system is installed on the teeth of the upper and lower jaws. Orthodontic movement of teeth is performed horizontally and vertically until they are completely closed, taking into account the installed occlusal pads. The dental arches are scanned with the occlusal pads installed and after their removal, after which the obtained images are combined and virtual images of the occlusal pads are obtained using the volumetric subtraction method, which are converted into physical models with subsequent fixation in the oral cavity. Accurate horizontal and vertical movement of teeth is achieved until they are completely closed in the physiological position of the lower jaw, fixed by means of permanent occlusal pads manufactured using digital technologies, as well as movement of the lower jaw from the distal position and restoration of the height of the lower third of the face.

The disadvantage of this method is the impossibility of using additive technologies in the production of occlusal overlays, since the currently known polymers for 3D printing have insufficient physical and mechanical properties, hardness, elasticity and abrasion coefficient, which can lead to the destruction of the overlays during treatment or a change in their geometry with a subsequent change in the position of the lower jaw.

The objective of the present invention is to position the lower jaw in a therapeutic position at the stages of complex orthopedic rehabilitation using digital technologies in patients with diseases of the temporomandibular joint and hypertonicity of the masticatory muscles.

Disclosure of the essence of the invention

The technical result of the invention is the positioning of the lower jaw at the stages of orthopedic rehabilitation in patients with diseases of the temporomandibular joint and hypertonicity of the masticatory muscles using long-term occlusal pads with increased mechanical properties, having a bending strength of 130 MPa, a modulus of elasticity in bending of 2.95 GPa, a fracture deformation in bending of 6%, and a hardness of 99 N/ ^mm2 .

The technical result of the invention is achieved by implementing the following set of essential features:

the patient is assigned a therapeutic position for the lower jaw,

the found position is recorded with an intraoral scanner, in the found relationship of the jaws, in a computer program for modeling dental structures, on the chewing surfaces of the first upper and lower molars, occlusal pads are modeled in such a way as to ensure a tight fissure-tubercle contact, compensating for disocclusion,

convert digital volumetric images of occlusal pads into physical ones using volumetric printing,

as a structural material for the production of occlusal pads, a photocomposite resin is used, containing in its composition: oligourethane methacrylate, oligourethane diacrylate, 2-hydroxyethyl methacrylate, bisacyl phosphine oxide and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, in the following ratio of components, mass %:

oligurethane methacrylate 20-62 oligourethane diacrylate 30-50 hydroxyethyl methacrylate 5-30 bisacylophosphine oxide 1-3 diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide 1.98-3 thiophendibenzoxazole 0.02-0.1,

The resulting occlusal pads are subjected to post-printing processing, final polymerization and fixed in the patient’s oral cavity using light-curing composite dental material.

The photocomposite material in the proposed ratio of components used in additive production of occlusal onlays after polymerization has the necessary mechanical characteristics: bending strength of 130 MPa, modulus of elasticity in bending of 2.95 GPa, deformation of destruction in bending of 6%, hardness of 99 N/mm ² . Which ensures the achievement of high-quality treatment at the orthodontic and orthopedic stages of patients with dysfunction of the temporomandibular joint and hypertonicity of the masticatory muscles.

Oligourethane methacrylate is used in the composition as a high-molecular oligomer, which is a component that determines the properties of the original mixture in liquid form and the finished product obtained as a result of 3D printing. Due to the structure and molecular weight, it provides the necessary physical and mechanical properties of the product obtained as a result of 3D printing.

Oligourethane diacrylate is used in the composition as a high-molecular oligomer, which is a component that determines the properties of the initial mixture in liquid form and the finished product obtained as a result of 3D printing. Due to the structure and molecular weight, it ensures the reactivity and degree of detail of the product obtained as a result of 3D printing.

2-hydroxyethyl methacrylate is used in the composition as an active diluent. Due to the structure and molecular weight, the viscosity and reactivity of the mixture are modified.

Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide and bisacylophosphine oxide in the material act as photoinitiators of polymerization of free-radical photopolymerizable compositions when irradiated with light in the range from 350 nm to 405 nm. This system of photoinitiators is the most suitable for initiating the polymerization of the system when added in a total concentration of 1.98-3%, while ensuring optimal print quality. In the case of using a concentration of less than 1% or more than 3% in the composition, the speed and quality of printing deteriorate.

Thiophene dibenzoxazole is used as a light stabilizer to increase the level of detail while maintaining the transparency of the product obtained as a result of 3D printing. When used in a concentration of more than 0.1%, it has a noticeable inhibitory effect on the polymerization process, which can negatively affect the speed and quality of curing of products.

At the stage of developing the composition of the photopolymerization resin, experiments were conducted to study the physical and mechanical characteristics of the composition containing the proposed composition.

As a result, the following parameters characterizing the quality of manufactured structures were determined: bending strength, bending fracture strain, bending elastic modulus, friction coefficient, abrasion, and hardness. Hardness was determined in accordance with GOST 4670-2015. The samples provided for by the mentioned standard were plates measuring 50×50×4 mm.

A total of 15 samples were manufactured, 5 of each structural material. Hardness tests were performed under a load of 358 N. The measurements were performed using an Instron 5965 universal testing machine (Instron, UK) equipped with a 2580-108 ±5 kN series load cell in the uniaxial compression mode. To study the homogeneity of the printed samples by area, measurements were taken at several points significantly distant from each other. In order to study the effect of water and human body temperature on the hardness of the materials, a series of samples pre-conditioned for 50 hours in distilled water at 37°C were additionally tested.

The mechanical properties of materials for three-point bending were studied using a universal testing machine Instron 5982 (Instron, UK) equipped with a load cell of the 2580-108 ±5 kN series in the three-point bending mode. The samples were made by the above-mentioned method. The sizes of the samples corresponded to GOST 31572-2012 and were parallelepipeds measuring 64×10×3.3 mm.

A total of 15 samples were produced, 5 from each structural material.

The wear resistance of structural materials used in the technology of manufacturing dental structures by the volume printing method was studied using a Thermo Scientific UMT-3 universal device (Thermo Scientific, USA). The samples were cylinders 16 mm high and 6 mm in diameter. As in the previous experiment, a total of 5 samples were made from each material. The tests were carried out in the pin-on-disk mode, the speed was 0.5 m/s, the pressure in the tribocontact zone was 2.5 MPa, which corresponded to a load on the sample of 72 N. A disk with a roughness of Ra = 0.3 and a hardness of HRc = 40 was used as a counterbody. The sample was located at a distance of 25 mm from the center of the disk. Based on the test results, linear wear, volumetric wear and friction coefficient were determined.

As a result, the average values were obtained for a composition containing 55% oligourethane methacrylate and 40% oligourethane diacrylate components of the total mass: bending strength - 89.7 MPa, flexural elastic modulus - 2.10 GPa, bending fracture strain of 10.8%, hardness - 91.6 GPa, friction coefficient - 0.52.

For the proposed composition, the bending strength was 130 MPa, the modulus of elasticity in bending was 2.95 GPa, the deformation at fracture in bending was 6%, the hardness was 99 N/ ^mm2 , and the coefficient of friction was 0.55.

Research has shown that the stated aspects of the technical result are achieved with different quantitative values of the composition used from the stated ranges.

Implementation of the invention

1. Obtain optical impressions of the dental arches using an intraoral scanner.

2. Determine the position of the lower jaw: determination of the degree of distal position of the lower jaw and the optimal interalveolar height within the framework of diagnostics using the regulated thickness of the Kois sheet calibrator was carried out through the cranio-postural kinesiological test.

For deprogramming the masticatory and temporal muscles, for example, the Kois sheet calibrator and the U-Dent Callibri deprogrammer (Neurotech, Russia) can be used.

3. After the muscles have relaxed, the calibrator is removed and, using articulation paper, for example, Bausch (Bausch, Germany), the new position of the lower jaw is determined on the jig and fixed using silicone material.

4. Digital impressions of the dental arches are obtained using an intraoral scanner.

5. Create occlusal pads on teeth using computer modeling, for example, the ExoCad program, achieving tight fissure-tubercle contact, compensating for disocclusion of teeth.

6. The resulting virtual models of occlusal pads are converted into physical ones using the volumetric printing method, manufactured using LCD printing technology. For this purpose, the Phrozen Sonic 4K printer (Phrozen, Taiwan) can be used, for example.

7. To obtain occlusal onlays, a photopolymer resin is used, which contains in its composition: oligourethane methacrylate, oligourethane diacrylate, 2-hydroxyethyl methacrylate, bisacylophosphine oxide and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide in the following ratio of components, mass %: oligourethane methacrylate 20-62, oligourethane diacrylate 30-50, hydroxyethyl methacrylate 5-30, bisacylophosphine oxide 1-3, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide 1.98-3, thiophene dibenzoxazole 0.02-0.1.

8. The resulting occlusal pads are subjected to post-printing processing, final polymerization of the material in a light-curing oven with UV radiation, for example, in a specialized device Phrozen Cure Kit (Phrozen, Taiwan).

9. A permanent brace system is fixed to the teeth of the upper and lower jaws, and orthodontic treatment is carried out by moving the teeth vertically until they close completely in the new spatial relationship found between the jaws of all the teeth.

Clinical example

Patient K, 46 years old, came to the clinic with complaints of grinding his teeth at night, periodic pain in the temporomandibular joint (TMJ) on the right when opening his mouth wide.

On external examination, the submandibular, submental, parotid, and anterior cervical lymph nodes are not enlarged upon palpation, are painless, have a dense, elastic consistency, and are not fused with the underlying tissues. Mouth opening is not limited, lower jaw movements are free and asymmetrical, and clicks are noted in the temporomandibular joint. The masticatory muscles (anterior, middle, and posterior bundles of the temporal muscles and proper masticatory muscles) are slightly painful upon palpation, hypertonicity is observed, the lateral and medial pterygoid muscles are moderately tense and slightly painful upon palpation. Responses to the Hamburg test: 2 positive responses were received.

Examination of the oral cavity reveals full dental arches, deep incisor overlap, distal position of the lower jaw, a decrease in the height of the lower part of the face by 6 mm in relation to the state of physiological rest, and generalized tooth wear. According to the data of computer tomography of the temporomandibular joints, a distal position of the heads and a decrease in the interarticular space are noted.

Based on the results of the studies, the following diagnosis was made: {K07.3} Anomalies of the position of the teeth, {K07.6} Diseases of the temporomandibular joint, {F45.3} Somatoform dysfunction of the autonomic nervous system, {K03.1} Grinding of teeth.

Treatment: Taking optical impressions of the dental arches using an intraoral scanner. Determining the position of the lower jaw: determining the degree of the distal position of the lower jaw and the optimal interalveolar height within the framework of diagnostics using the regulated thickness of the Kois sheet calibrator was carried out through a cranio-postural kinesiological test. The next step, based on the described cranio-postural kinesiological test, was to select the thickness of the Kois sheet calibrator. For deprogramming the masticatory and temporal muscles, the Kois sheet calibrator and the U-Dent Callibri deprogrammer (Neurotech, Russia) were used.

After 10 minutes of muscle relaxation using the functional activity sensor and sheet calibrator, the calibrator was removed, after which, without allowing the patient to close the dental arches, the Lucia jig was fixed on the upper jaw between the central incisors. Then, using Bausch articulation paper (Bausch, Germany), the new position of the lower jaw was determined on the jig and fixed using silicone material. Digital impressions of the dental arches were obtained using an intraoral scanner. Kinesiotests and cone-beam computed tomography of the TMJ were repeated to control and verify the found therapeutic position of the lower jaw.

After determining and monitoring the therapeutic position of the lower jaw, we began the process of creating occlusal pads on teeth 16, 26, 36, 46, using the ExoCad program, achieving a tight fissure-tubercle contact, compensating for the disocclusion of these teeth.

Virtual models of occlusal pads were converted into physical ones using the volumetric printing method, manufactured using LCD printing technology, using the Phrozen Sonic 4K printer (Phrozen, Taiwan).

The structural material used was a photopolymer resin containing the following: oligourethane methacrylate, oligourethane diacrylate, 2-hydroxyethyl methacrylate, bisacylophosphine oxide and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide in the following ratio of components, mass %: oligourethane methacrylate 62, oligourethane diacrylate 30, hydroxyethyl methacrylate 5, bisacylophosphine oxide 1, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide 1.98, thiophene dibenzoxazole 0.02.

The composite resin was obtained by intensive mixing in a dissolver while heating the mixture of oligomer and monomer to at least 60°C with the addition of photoinitiators and a light stabilizer until homogeneity was achieved.

The printing settings corresponded to the parameters: layer height 0.050; number of bottom layers 4; exposure time 15 sec; bottom exposure time 75 sec; switch-off delay 5 sec; bottom switch-off delay 5 sec; platform lift height 6 mm; platform lift speed 50 mm; lower retraction speed 150 mm; retraction speed 150 mm. After printing, the overlays were treated in a solution of 96% ethyl alcohol for three minutes to remove polymer residues in a special Phrozen Wash & Cure Kit (Phrozen, Taiwan). After drying, the overlays were dried for 10 minutes in a cabinet at a temperature of 70 degrees, after which they were immersed in a thin layer of glycerin gel to create an oxygen-free environment and subjected to final polymerization of the material in a light-curing oven with UV radiation in a specialized Phrozen Cure Kit device (Phrozen, Taiwan), polished and fixed on teeth 16, 26, 36, 46 with a flowable light-curing dental composite material.

A repeated CT scan of the TMJ was performed to control the position of the lower jaw. A fixed bracket system was fixed to the teeth of the upper and lower jaws and orthodontic treatment was performed, moving the teeth vertically until they closed completely in the new spatial relationship of the jaws of all teeth, for 8 months.

During the treatment stages, during visual observation of the inlays and changes in their geometry, no splits or de-cementation were registered.

Upon completion of orthodontic treatment, all teeth were prepared for permanent ceramic restorations. Virtual impressions of the dental arches were obtained. The position of the lower jaw and interalveolar height were recorded with an intraoral scanner before tooth preparation. The manufactured ceramic restorations were fixed in the oral cavity using an adhesive protocol.

As a result of the treatment, the patient's oral cavity was characterized by multiple fissure-tubercular contacts of the teeth of the upper and lower jaws, centering of the heads of the lower jaw, and the absence of hypertonicity of the masticatory muscles.

Claims (1)

A method for positioning the lower jaw, including determining the therapeutic position of the lower jaw, recording the found position with an intraoral scanner, in the found relationship of the jaws, in a computer program for modeling dental structures, occlusal pads are modeled on the chewing surfaces of the first upper and lower molars in such a way as to ensure a tight fissure-tubercle contact compensating for disocclusion, a digital volumetric image of the occlusal pads is converted into a physical one using a volumetric printing method, a photocomposite resin is used as a structural material for manufacturing the occlusal pads, containing in its composition: oligourethane methacrylate, oligourethane diacrylate, 2-hydroxyethyl methacrylate, bisacyl phosphine oxide and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide in the following ratio of components, mass. %: oligourethane methacrylate 20-62, oligourethane diacrylate 30-50, hydroxyethyl methacrylate 5-30, bisacyl phosphine oxide 1-3, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide 1,98-3, thiophene dibenzoxazole 0.02-0.1, the resulting occlusal pads are subjected to post-printing treatment, final polymerization and fixed in the patient's oral cavity on a light-curing composite dental material.