Layered silicone rubber composite guide plate indirectly bonded with self-ligating bracket and manufacturing method of layered silicone rubber composite guide plate

Abstract

The invention belongs to the technical field of orthodontics, and discloses a layered silicone rubber composite guide plate indirectly bonded with a self-ligating bracket and a manufacturing method of the layered silicone rubber composite guide plate, and the guide plate is formed by tightly combining an inner transparent middle body layer and an outer heavy body layer; the transparent middle body layer is formed by curing addition type silicone rubber with the light transmittance being greater than or equal to 85% and wraps the bracket and the lip side of the dental crown; the heavy body layer is formed by curing high-hardness silicone rubber with the shore hardness larger than or equal to Shore A 80, covers the middle body layer and extends to the cutting end of the dental crown and the tongue side to form a rigid supporting and three-point positioning structure, the core of the manufacturing method lies in rheological sequential control and hydraulic permeation locking, that is, after the transparent middle body layer enters a thixotropic peak period, the heavy body layer covers the transparent middle body layer and applies vertical pressure, and the rigid supporting and three-point positioning structure is formed. And the middle body material is forced to secondarily flow and compactly fill the undercut of the bracket by using the heavy body layer. According to the invention, commercially available or self-made high-performance silicone rubber is utilized, through a layered structure and a rheological process, the gapless mechanical interlocking of the guide plate and the bracket is realized while the photocuring efficiency is ensured, and the problems of low positioning precision and insufficient retention force of a traditional guide plate are solved.

Description

Technical Field

[0001] This invention relates to the field of orthodontic technology, specifically to a layered silicone rubber composite guide plate indirectly bonded to self-ligating brackets and its manufacturing method. Background Technology

[0002] With the development of orthodontic technology, the bracket bonding technique for fixed orthodontic appliances has evolved from direct bonding to indirect bonding. Indirect bonding involves pre-positioning the bracket precisely on the patient's dental mold, creating a transfer guide containing bracket position information, and then transferring the entire bracket into the patient's mouth. Compared to traditional intraoral direct bonding, this technique allows for more precise control of the bracket's axial tilt, torque angle, and height on the tooth surface, effectively reducing the workload of subsequent archwire bending and adjustment. It also significantly shortens the patient's chair-side mouth-opening time, improving the efficiency and comfort of orthodontic treatment.

[0003] In current clinical practice and dental procedures, the main materials used to fabricate transfer guides include thermoformed films and medical-grade silicone rubber. Silicone rubber, due to its excellent ability to replicate details and its high elastic recovery rate, is widely used for the indirect transfer of self-ligating brackets. The standard procedure typically involves first arranging the brackets on a plaster model, then mixing addition-cured silicone rubber to cover the brackets and dentition. After the material cross-links and cures, the edges are trimmed to form the guide. In clinical application, the dentist applies AB adhesive to the patient's tooth surface and the bracket surface respectively, presses for three minutes to allow the adhesive to bond, and then cuts the silicone rubber to remove the guide, completing the transfer.

[0004] However, existing silicone rubber transfer guides present a dilemma in practical applications, where it's difficult to balance material properties. Firstly, the silicone rubber matrix lacks transparency, often requiring the use of chemically cured adhesives (such as AB glue). However, chemical curing systems are not only difficult to precisely control in terms of operation time, but also incompatible with the light-cured adhesives widely used in orthodontic clinics, increasing the complexity and cost of material management. If the physician wants to use light-cured adhesives for bracket bonding, the main part of the guide material needs to have high light transmittance. However, high-transmittance silicone rubber matrix (silicone rubber core) typically has low hardness and low modulus, making it prone to elastic deformation when peeled from the plaster model or when pressure is applied during placement in the patient's mouth. This insufficient rigidity can cause slight misalignment of the bracket during transfer, affecting final positioning accuracy and even preventing bonding altogether. This trade-off between light-curing efficiency and rigid positioning accuracy is difficult to resolve effectively with a single material system or conventional manufacturing process. Summary of the Invention

[0005] The technical problem solved by this invention is that traditional guide plates are not transparent and cannot use light-curing adhesives, while transparent guide plate materials are not rigid enough, which makes them prone to deformation during the transfer process, ultimately reducing the success rate and efficiency of orthodontic clinical bonding.

[0006] To address the above problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a layered silicone rubber composite guide plate with self-locking brackets and indirect bonding, wherein the composite guide plate is formed by tightly bonding an inner transparent middle layer and an outer heavy layer.

[0008] The transparent intermediate layer is cured from addition-type silicone rubber with a light transmittance of greater than or equal to 85%. The transparent intermediate layer surrounds the bracket body, the bracket base plate and the labial area of ​​the crown. The transparent intermediate layer has medium and low viscosity and thixotropy before curing.

[0009] The heavy body layer is cured from addition-cure silicone rubber with a Shore A hardness greater than or equal to Shore A 80. The heavy body layer tightly covers the outer surface of the transparent middle body layer and extends to cover the incisal edge and lingual region of the crown, forming a rigid support and three-point positioning structure for the transparent middle body layer. The heavy body layer has high viscosity and plasticity before curing. The transparent middle body layer and the heavy body layer are chemically cross-linked at the contact interface to form a whole.

[0010] Furthermore, the average thickness of the transparent intermediate layer is 1.5 mm to 2.5 mm, and the elongation at break after curing is 280% to 350%; the average thickness of the heavy layer is 5 mm to 10 mm, and the linear shrinkage rate after curing is less than 0.2%.

[0011] Furthermore, the transparent intermediate layer is made of silicone rubber material containing vinyl-terminated polydimethylsiloxane and fumed silica filler; the heavy layer is made of silicone rubber material containing high-viscosity polydimethylsiloxane and inorganic mineral filler; both the transparent intermediate layer and the heavy layer are cured by hydrosilylation reaction.

[0012] Secondly, the present invention provides a method for manufacturing a layered silicone rubber composite guide plate indirectly bonded by self-locking brackets, comprising the following steps:

[0013] S1. Model pretreatment: Apply a separating agent to the surface of the dental mold with brackets and then dry it.

[0014] S2, Transparent intermediate layer coating: Select addition-cure silicone rubber with acceptable light transmittance as the intermediate material, mix and coat it onto the surface of the bracket and crown after the pretreatment in step S1;

[0015] S3, Rheological timing control: After the coating is completed in step S2, let it stand and wait until the surface of the transparent intermediate layer loses its gloss and enters the thixotropic peak period. The thixotropic peak period refers to the state in which the intermediate material no longer undergoes gravity flow but still has the ability to plastically deform.

[0016] S4. Hydraulic penetration locking and weight construction: High-hardness addition-curing silicone rubber is selected as the weight material. After mixing, it is covered on the surface of the transparent middle layer, which is in the thixotropic peak period after being treated in step S3. Vertical pressure is applied, and the high viscosity of the weight layer forces the transparent middle layer to undergo secondary flow and fill the bracket undercut. Then the weight layer is shaped and extended to the incisal edge and lingual side of the crown.

[0017] S5. Synchronous curing and separation: After the double-layer structure formed in step S4 has been chemically cross-linked and cured simultaneously, the composite guide plate is removed from the dental mold.

[0018] Furthermore, the settling time in step S3 is 15 to 20 seconds; the settling time is used to ensure that the transparent middle layer establishes a preliminary thixotropic network and to prevent excessive loss of the middle material when pressure is applied in step S4.

[0019] Furthermore, in step S4, the vertical pressure range is 0.05MPa to 0.15MPa, and the pressure duration is 5 seconds to 10 seconds; the hydraulic penetration locking refers to using the heavy body layer as a pressure transmission medium under pressure to force the transparent middle body layer, which is in the thixotropic peak period, to form a gapless mechanical interlock with the bottom plate of the tray and the inverted wing, and to expel interface bubbles.

[0020] This invention provides a self-locking bracket indirect bonding layered silicone rubber composite guide plate and its manufacturing method. It has the following beneficial effects:

[0021] 1. This invention employs a composite structure combining an inner transparent middle layer and an outer heavy layer. The inner layer uses high-transmittance silicone rubber material to ensure that blue light can effectively penetrate and trigger the polymerization reaction of the adhesive under the bracket base, avoiding the drawbacks of using chemical curing agents. At the same time, the outer layer uses high-hardness silicone rubber and extends to cover the incisal edge and lingual area of ​​the crown to form a three-point positioning structure, providing rigid support and preventing elastic deformation of the guide plate during transfer. This achieves the effect of improving the positioning accuracy of bracket transfer while ensuring the efficiency of light curing.

[0022] 2. This invention implements rheological timing control and hydraulic penetration locking steps in the manufacturing process. After the transparent middle layer enters the thixotropic peak period, a heavy layer is covered and vertical pressure is applied. The heavy layer is used as a pressure transmission medium to force the middle material to flow secondary, densely filling the concave area below the bottom of the tray bottom plate and the wings, and expelling interface bubbles. This ensures that a gapless and tightly embedded structure is formed between the middle layer and the tray, achieving the effect of the guide plate having a high-strength mechanical interlocking gripping force on the tray and preventing the tray from falling off.

[0023] 3. This invention employs a synchronous curing process and a universal material system, utilizing the consistent cross-linking mechanism of the two layers to enable the intermediate and heavy layers to undergo a simultaneous chemical reaction at the contact interface and form covalent bonds, thus constructing a tightly bonded overall structure. This completely avoids the risk of delamination of the layered guide plate under stress. At the same time, this method allows for rapid fabrication in the clinic using commercially available conventional silicone rubber materials, eliminating the need for expensive digital equipment. This achieves the effect of significantly improving the fabrication efficiency of indirect bonding guide plates while reducing clinical costs. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0025] Figure 2 This is a cross-sectional view of the layered silicone rubber composite guide plate of the present invention. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example:

[0028] Please see the appendix Figure 1-2 This invention provides a layered silicone rubber composite guide plate with self-locking brackets for indirect bonding and a method for manufacturing the same.

[0029] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0030] Vinyl-terminated polydimethylsiloxane, industrial grade, is available in low-viscosity (2000-5000 mPa·s, for medium-viscosity) and high-viscosity (100000 mPa·s, for heavy-viscosity) types. It is a linear homopolymer with a main chain composed of repeating dimethylsiloxane units and end groups of dimethylvinylsiloxy groups. The vinyl content is 0.04-0.12 mmol / g, and the molecular weight distribution index (PDI) is ≤2.0. Another type is polymethylhydrosiloxane, with a viscosity of 100-300 mPa·s and an active hydrogen content of 0.8-1.2 wt%. Its main chain consists of repeating methylhydrosiloxane and dimethylsiloxane units, with end groups of trimethylsiloxy groups, arranged in a random copolymeric state. The side chains contain hydrogen, with a viscosity of 50-150 mPa·s and a hydrogen content of 1.5-1.6 wt%.

[0031] Hydrophobically modified fumed silica, surface-treated with dimethyldichlorosilane, has a specific surface area of ​​110±20 m² / g. 2 / g, with a primary particle size of approximately 16nm, a carbon content of 0.6-1.2%, crystalline quartz powder, an average particle size D50 of 5-10μm, and a silica content ≥99.5%.

[0032] Octamethylcyclotetrasiloxane, purity ≥99.0%; 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, purity ≥99.0%; 3-methacryloyloxypropyltrimethoxysilane, purity ≥98.0%; platinum-divinyltetramethyldisiloxane complex, platinum content 5000ppm; 1-ethynyl-1-cyclohexanol, purity ≥99.0%.

[0033] Okabete transparent silicone rubber, commercially available dental addition-cure silicone rubber, light transmittance ≥85%, DMGSilagum-Putty, commercially available dental addition-cure silicone rubber heavy body, Shore A hardness 85, 3M Transbond TM XT light-cured orthodontic adhesive, commercially available orthodontic-specific, sodium alginate.

[0034] Preparation example:

[0035] Preparation Example 1:

[0036] This preparation example provides a high-transmittance silicone rubber medium (component A-1), characterized by excellent light transmittance (≥90%) and moderate flowability, comprising the following steps:

[0037] (1) Preparation of matrix component (Base): 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 3000 mPa·s), 30 parts of hydrophobic modified fumed silica and 0.2 parts of platinum-divinyltetramethyldisiloxane complex (platinum content 5000 ppm) were added to a vacuum planetary mixer; the mixture was stirred at low speed at room temperature for 30 minutes, then heated to 120°C and stirred at high speed under vacuum of -0.095 MPa for 2 hours, and then cooled to room temperature to obtain the matrix adhesive;

[0038] (2) Preparation of Catalyst: 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 3000 mPa·s), 30 parts of hydrophobically modified fumed silica, 4 parts of polymethylhydrosiloxane (hydrogen content 1.0 wt%) and 0.03 parts of 1-ethynyl-1-cyclohexanol were added to a vacuum planetary mixer; the mixture was stirred under vacuum for 30 minutes to obtain the catalytic binder.

[0039] (3) Packaging: The matrix adhesive and the catalyst adhesive are respectively loaded into the two chambers of the double-tube syringe, with a volume ratio of 1:1.

[0040] Tests showed that the light transmittance of the solidified medium was 91% (1mm thickness) and the elongation at break was 320%.

[0041] Preparation Example 2:

[0042] This preparation example provides a highly thixotropic transparent silicone rubber matrix (component A-2), characterized by increasing the filler content to improve thixotropy, with a light transmittance close to the lower limit of the claim (85%), comprising the following steps:

[0043] (1) Preparation of matrix components: The process is the same as in Preparation Example 1, except that 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 5000 mPa·s), 40 parts of hydrophobic modified fumed silica and 0.2 parts of platinum catalyst are added;

[0044] (2) Preparation of catalytic components: The process is the same as in Preparation Example 1, except that 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 5000 mPa·s), 40 parts of hydrophobically modified fumed silica, 5 parts of polymethylhydrosiloxane (hydrogen content 1.0 wt%) and 0.05 parts of 1-ethynyl-1-cyclohexanol are added.

[0045] (3) Packaging: Same as preparation example 1.

[0046] Tests showed that the light transmittance of the solidified medium was 86% (1mm thickness), with a high thixotropic index and an elongation at break of 280%.

[0047] Preparation Example 3:

[0048] This preparation example provides a high-flowability transparent silicone rubber matrix (component A-3), characterized by low viscosity and high light transmittance, comprising the following steps:

[0049] (1) Preparation of matrix components: The process is the same as in Preparation Example 1, except that 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 2000 mPa·s), 25 parts of hydrophobic modified fumed silica and 0.2 parts of platinum catalyst are added;

[0050] (2) Preparation of catalytic components: The process is the same as in Preparation Example 1, except that 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 2000 mPa·s), 25 parts of hydrophobically modified fumed silica, 3 parts of polymethylhydrosiloxane (hydrogen content 1.0 wt%) and 0.02 parts of 1-ethynyl-1-cyclohexanol are added.

[0051] (3) Packaging: Same as preparation example 1.

[0052] Tests showed that the light transmittance of the medium after curing was 93% (1mm thickness), it had excellent fluidity, and its elongation at break was 350%.

[0053] Preparation Example 4:

[0054] This preparation example provides a high-hardness silicone rubber mass (component B-1), characterized in that its hardness is the median value of the claim range (Shore A 85), comprising the following steps:

[0055] (1) Pretreatment of filler modification: 400 parts of crystalline quartz powder were placed in a high-speed mixer and heated to 110°C. An ethanol aqueous solution containing 8 parts of 3-methacryloyloxypropyltrimethoxysilane was sprayed in and stirred at high speed for 15 minutes. The mixture was then dried at 120°C for later use.

[0056] (2) Preparation of matrix component (Base): 100 parts of high viscosity vinyl-terminated polydimethylsiloxane (viscosity 100000 mPa·s) and the above modified quartz powder were added to a kneader, heated to 130℃ and vacuum kneaded for 1 hour, and after cooling, 0.3 parts of platinum catalyst were added and mixed evenly.

[0057] (3) Preparation of Catalyst: 100 parts of high viscosity vinyl-terminated polydimethylsiloxane, 6 parts of side-chain hydrogen-containing polysiloxane (hydrogen content 1.5wt%) and 400 parts of the above modified quartz powder were added to a kneader and kneaded evenly under vacuum.

[0058] (4) Packaging: The matrix components and catalytic components are packaged in a mass ratio of 1:1.

[0059] Tests showed that the hardness of the solidified material was Shore A 85, and the linear shrinkage rate was 0.15%.

[0060] Preparation Example 5:

[0061] This preparation example provides a high-hardness silicone rubber mass (component B-2), characterized in that its hardness is the lower limit of the claim (Shore A 80), and includes the following steps:

[0062] (1) Pretreatment of filler modification: Same as preparation example 4, except that the amount of crystalline quartz powder is adjusted to 300 parts and the amount of coupling agent is adjusted to 6 parts;

[0063] (2) Preparation of matrix components: Same as in preparation example 4, except that the amount of filler was adjusted to 300 parts and the amount of platinum catalyst was the same;

[0064] (3) Preparation of catalytic components: Same as in preparation example 4, except that the amount of filler is adjusted to 300 parts and the amount of side-chain hydrogen-containing polysiloxane is adjusted to 5 parts;

[0065] (4) Packaging: Same as preparation example 4.

[0066] Tests showed that the hardness of the solidified material was Shore A 80, and its flexibility was slightly better than that of Preparation Example 4, making it easier to demold.

[0067] Preparation Example 6:

[0068] This preparation example provides an ultra-high hardness silicone rubber mass (component B-3), characterized in that its hardness is the upper limit of the claim range (Shore A 92), and includes the following steps:

[0069] (1) Pretreatment of filler modification: Same as preparation example 4, except that the amount of crystalline quartz powder is adjusted to 500 parts and the amount of coupling agent is adjusted to 10 parts;

[0070] (2) Preparation of matrix components: Same as in preparation example 4, except that the amount of filler was adjusted to 500 parts and the amount of platinum catalyst was the same;

[0071] (3) Preparation of catalytic components: Same as in preparation example 4, except that the amount of filler is adjusted to 500 parts, the amount of side-chain hydrogen-containing polysiloxane is adjusted to 8 parts, and an additional 10 parts of vinyl MQ resin is added (to enhance crosslinking density and improve hardness).

[0072] (4) Packaging: Same as preparation example 4.

[0073] Tests showed that the solidified weight had a Shore A 92 hardness, exhibiting extremely high rigidity and the highest positioning accuracy.

[0074] Example:

[0075] The following are specific embodiments of the guide plate manufacturing method of the present invention. These embodiments cover the lower limit, intermediate value and upper limit of the numerical range summarized in the claims by setting different process parameters (such as rheological waiting time, pressure, material layer thickness, etc.) to fully support the technical solution.

[0076] Example 1:

[0077] This embodiment provides a method for manufacturing a layered silicone rubber composite guide plate with indirect bonding via self-locking brackets. It uses commercially available materials and employs preferred intermediate values ​​for the process parameters, including the following steps:

[0078] (1) Model pretreatment: Apply alginate separating agent evenly to the crown and gingival areas of the ultra-hard plaster model and let it dry; use light-cured temporary adhesive to bond the self-ligating bracket to the preset position of the model and fix it by light curing for 10 seconds;

[0079] (2) Coating of transparent intermediate layer: Okabete transparent silicone rubber is used as the intermediate layer. It is injected into the edge of the bracket base plate and below the wings using a dual-tube automatic mixing gun (the volume ratio of matrix to catalyst component is 1:1) and covers the labial surface of the crown. The average thickness of the intermediate layer is controlled to be about 2.0 mm to ensure that there are no air bubbles.

[0080] (3) Rheological timing control: After coating, the medium is not covered immediately. It is left to stand at room temperature (23°C) for 18 seconds. At this time, the surface of the medium loses its flow gloss and enters the thixotropic peak period (dough state).

[0081] (4) Hydraulic penetration locking and heavy body construction: DMG Silagum-Putty silicone rubber heavy body is taken, and the matrix and catalytic components are taken at a volume ratio of 1:1. After being mixed evenly by hand, it is shaped into a long strip and covered on the middle body layer and the incisal edge of the tooth row. Vertical pressure is applied from the incisal edge to the gingival direction, with a pressure of about 0.10 MPa (equivalent to a finger pressure of about 30N) for 5 seconds. The high viscosity of the heavy body forces the middle body, which is in the thixotropic peak period, to undergo secondary flow and fill into the undercut of the bracket ligature wing. Then the heavy body is extended to the lingual and palatal sides to form a heavy body support frame with a thickness of about 6mm.

[0082] (5) Simultaneous curing and separation: Let the whole thing stand at room temperature for 6 minutes to allow the two layers of material to complete chemical cross-linking and curing simultaneously; then immerse the model in clean water for 10 minutes, and use the layer removal method to remove the guide plate from the model and trim the lip flash.

[0083] Example 2:

[0084] This embodiment provides a method for fabricating a layered silicone rubber composite guide plate with indirect bonding via self-locking brackets. It utilizes Preparation Example A-3 (high-flowability medium-weight) and Preparation Example B-2 (Shore 80A heavy-weight), with process parameters biased towards the lower limit of the range (thin layer, rapid process). The method includes the following steps:

[0085] (1) Model preprocessing: Same as in Example 1;

[0086] (2) Coating of transparent intermediate layer: The high-flow transparent silicone rubber intermediate obtained in preparation example A-3 was mixed at a volume ratio of 1:1 and then covered the bracket and tooth surface, and the average thickness of the intermediate layer was controlled to be about 1.5 mm.

[0087] (3) Rheological timing control: Since the initial viscosity of the medium is low (strong fluidity), after coating, it is left to stand for 15 seconds to allow it to initially establish a thixotropic network and enter the peak period;

[0088] (4) Hydraulic penetration locking and weight construction: Take the silicone rubber weight (hardness Shore 80A) prepared in Preparation Example B-2, mix it evenly at a mass ratio of 1:1 and cover it on the middle body and the dental arch; apply a relatively gentle vertical pressure of about 0.05 MPa for 5 seconds to make the middle body slightly pressed into the undercut; roll the weight to the tongue side to form a support frame with a thickness of about 5 mm;

[0089] (5) Simultaneous curing and separation: Let stand at room temperature for 5 minutes; after immersion in water, use the overall prying removal method to remove the guide plate from the model in one step using the lever principle.

[0090] Example 3:

[0091] This embodiment provides a method for fabricating a layered silicone rubber composite guide plate with indirect bonding via self-locking brackets. It utilizes Preparation Example A-2 (high thixotropic medium-weight) and Preparation Example B-3 (Shore 92A heavy-weight), with process parameters biased towards the upper limit of the range (thick layer, high pressure, high hardness), and includes the following steps:

[0092] (1) Model preprocessing: Same as in Example 1;

[0093] (2) Coating of transparent intermediate layer: The highly thixotropic transparent silicone rubber intermediate obtained in Preparation Example A-2 was mixed at a volume ratio of 1:1 and then covered the bracket and tooth surface, and the average thickness of the intermediate layer was controlled to be about 2.5 mm.

[0094] (3) Rheological timing control: Since the medium has strong initial thixotropy, after coating, it is left to stand for 20 seconds until its surface is completely matte.

[0095] (4) Hydraulic penetration locking and heavy body construction: Take the ultra-high hardness silicone rubber heavy body (hardness Shore 92A) prepared in preparation example B-3, mix it evenly at a mass ratio of 1:1 and cover it; Since the heavy body is relatively hard and the middle body is relatively thick, apply a large vertical pressure, the pressure is about 0.15 MPa, and last for 10 seconds, and use the strong force to force the middle body to penetrate into the deep recess of the bracket; The heavy body layer extends to cover the entire mating surface and tongue side, forming a rigid outer skeleton with a thickness of about 10 mm;

[0096] (5) Simultaneous curing and separation: Let stand at room temperature for 8 minutes to ensure complete curing; after immersion in water, remove the guide plate by layer removal method.

[0097] Example 4:

[0098] This embodiment provides a method for fabricating a layered silicone rubber composite guide plate with indirect bonding via self-locking brackets. Preparation Example A-1 (standard self-made medium-sized body) and Preparation Example B-1 (standard self-made heavy body) are used to verify the process adaptability of the self-made standard formulation. The method includes the following steps:

[0099] (1) Model preprocessing: Same as in Example 1;

[0100] (2) Coating of transparent intermediate layer: The transparent silicone rubber intermediate obtained in preparation example A-1 was mixed at a volume ratio of 1:1 and then covered the bracket and tooth surface, and the average thickness of the intermediate layer was controlled to be about 2.1 mm.

[0101] (3) Rheological timing control: After coating, let stand for 17 seconds;

[0102] (4) Hydraulic penetration locking and weight construction: Take the silicone rubber weight (hardness Shore 85A) prepared in preparation example B-1, mix it evenly at a mass ratio of 1:1 and cover it; apply vertical pressure of about 0.08 MPa for 8 seconds; construct a weight support layer with a thickness of about 8 mm.

[0103] (5) Simultaneous curing and separation: Let stand at room temperature for 7 minutes; after immersion in water, remove the guide plate by layer removal method.

[0104] Comparative example:

[0105] Comparative Example 1:

[0106] Compared with Example 1, the difference lies in the timing of the manufacturing process: after coating the transparent intermediate layer in step (2), let it stand at room temperature for 10 minutes until the intermediate layer is completely cured, and then perform step (4); that is, when the transparent intermediate layer has lost its fluidity and the surface is hardened, coat the mixed heavy layer to cover and apply pressure, and remove it after the heavy layer is cured. The remaining raw materials and steps are the same as in Example 1.

[0107] Comparative Example 2:

[0108] Compared with Example 1, the difference is that only a single layer of material is used to make the guide plate: instead of using a high-hardness silicone rubber weight, Okabet transparent silicone rubber is used to form a single layer of transparent guide plate with a thickness of about 6-8 mm on the model by multiple coatings, and to cover the dental arch and brackets. The other raw materials and steps are the same as in Example 1.

[0109] Comparative Example 3:

[0110] The difference from Example 1 lies in the alteration of the light transmittance of the core material: a commercially available opaque dental silicone core (3M Imprint) was used. TM 4. Light (green) replaces the Okabet transparent silicone rubber medium in Example 1, and the remaining raw materials and steps are the same as in Example 1.

[0111] Comparative Example 4:

[0112] Compared with Example 1, the difference lies in the change of the structure of the heavy body layer: the heavy body layer only covers the labial transparent middle body layer area and does not extend to cover the incisal edge and lingual area of ​​the crown, and does not form a three-point positioning structure. The other materials and steps are the same as in Example 1.

[0113] Comparative Example 5:

[0114] Compared with Example 1, the difference lies in the timing of applying pressure to the heavy body: after coating the transparent intermediate layer in step (2), without waiting (interval less than 3 seconds), the heavy body is immediately covered and pressure is applied, and the remaining raw materials and steps are the same as in Example 1.

[0115] Comparative Example 6:

[0116] This comparative example provides a method for manufacturing a guide plate using a double-layer lamination combined with a chemically cured adhesive. The specific steps are as follows: a soft inner layer film with a thickness of 1.0 mm is hot-pressed onto a plaster model; a bracket is placed at the corresponding position on the film, and the base plate of the bracket is wrapped and bonded to the inner surface of the soft film using a two-component epoxy resin adhesive (AB glue); after the adhesive has cured, a hard outer layer film with a thickness of 1.5 mm is hot-pressed on; after trimming the edges, a transfer guide plate is obtained.

[0117] Test Example: Verification of UV Curing Efficiency and Bond Strength

[0118] This test selected extracted bovine mandibular incisors with smooth surfaces and intact structures as the matrix to verify the light transmission performance and clinical bonding strength of the layered silicone rubber composite guide plate prepared in Example 1. First, a light intensity attenuation test was conducted. A light intensity meter (wavelength response range 420-480nm) was used to measure the light power density of the light curing lamp under different conditions. The control group was set up with the light guide rod directly contacting the probe, and the experimental group was set up with the light guide rod contacting the probe through the transparent intermediate layer (thickness 2.0±0.1mm) prepared in Example 1. Each group was measured 10 times and the values ​​were recorded.

[0119] Subsequently, shear bond strength (SBS) tests were conducted. Forty extracted bovine teeth were randomly divided into four groups of ten each. Composite guide plates were fabricated according to the method in Example 1. Self-locking brackets were positioned and embedded within the guide plates. After cleaning and acid etching of the bovine tooth surfaces, 3M Transbond coating was applied to the bracket base plate. TM XT light-cured adhesive was used. The bracket was positioned onto the tooth surface using a guide plate. An LED light-curing lamp with a calibrated light intensity of 1200 mW / cm² was used to irradiate the transparent layer on the labial side of the guide plate. The irradiation time for the four experimental groups was set to 10 seconds, 20 seconds, 30 seconds, and 40 seconds, respectively. After curing, the samples were stored in a 37°C constant temperature water bath for 24 hours and tested using a universal testing machine. The loading direction was parallel to the enamel surface, and the blade was applied to the connection between the bracket wing and the base plate. The loading speed was set to 1.0 mm / min. The maximum load when the bracket fell off was recorded and converted to megapascals (MPa).

[0120] Table 1: Data Record of Shear Bond Strength and Light Intensity Attenuation of the Bracket under Different Illumination Durations

[0121]

[0122] (Note: Clinically, it is generally believed that the effective threshold for orthodontic bracket bonding strength should be greater than 6-8 MPa.)

[0123] Results Analysis and Conclusions

[0124] Light intensity test data showed that the direct light intensity of the control group was 1185.4 mW / cm². 2 After light penetrates a 2mm thick transparent intermediate layer, the average light intensity remains at 1020 mW / cm². 2 With a light transmittance of over 86%, this data indicates that the vinyl-terminated polydimethylsiloxane combined with modified fumed silica filler system used in this invention reduces light scattering by controlling the particle size and dispersibility of the filler, enabling blue light in the 420-480nm wavelength band to effectively penetrate the middle layer and reach the bottom plate of the bracket, thereby activating the photoinitiator in the adhesive.

[0125] Mechanical performance data show that when the light exposure time is 20 seconds (group 2), the average shear strength has reached 10.15 MPa, which is significantly higher than the clinically effective threshold. This result is related to the composite molding process of the guide plate. During the manufacturing process, the outer high-viscosity heavy body applies vertical pressure to the inner medium body in the uncured state, forcing the medium body material to fit tightly against the bracket base edge and undercut structure. This pressure transmission makes the medium body layer and the bracket form a gapless embedding. When placed in the clinical position, the guide plate can stably press the bracket onto the tooth surface.

[0126] Stable pressing action ensures that the adhesive layer is uniform and thin, reducing polymerization shrinkage stress or bubble defects caused by excessive adhesive layer thickness, thereby improving the overall bonding strength. The strength data of Group 3 (30 seconds) and Group 4 (40 seconds) are not significantly different, indicating that the cross-linking reaction of the adhesive is close to saturation within the 20 to 30-second light exposure range. Combining light intensity and mechanical data, it can be seen that this layered silicone rubber guide plate achieves high-precision fitting and stable bonding of the bracket while ensuring photocuring efficiency and utilizing the rheological properties of the material.

[0127] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A layered silicone rubber composite guide plate indirectly bonded by self-locking brackets, characterized in that, It includes an inner transparent middle layer and an outer heavy layer; The transparent intermediate layer surrounds the bracket body, the bracket base plate, and the labial area of ​​the crown. The transparent intermediate layer is made of addition-cure silicone rubber material with a light transmittance of greater than or equal to 85% after curing. The heavy body layer tightly covers the outer surface of the transparent middle body layer and extends to cover the incisal edge and lingual region of the crown, forming a rigid support and three-point positioning structure for the transparent middle body layer. The heavy body layer is made of addition-cure silicone rubber material with a Shore hardness greater than or equal to Shore A 80 after curing. The transparent intermediate layer and the heavy layer are chemically cross-linked and cured at the contact interface to form a whole.

2. The layered silicone rubber composite guide plate with indirect bonding via self-locking brackets according to claim 1, characterized in that, The average thickness of the transparent intermediate layer is 1.5 mm to 2.5 mm, and the elongation at break after curing is 280% to 350%; the average thickness of the heavy layer is 5 mm to 10 mm, and the linear shrinkage rate after curing is less than 0.2%.

3. The layered silicone rubber composite guide plate with indirect bonding via self-locking brackets according to claim 1, characterized in that, The transparent intermediate layer is made of silicone rubber material containing vinyl-terminated polydimethylsiloxane and fumed silica filler; the heavy layer is made of silicone rubber material containing high-viscosity polydimethylsiloxane and inorganic mineral filler; both the transparent intermediate layer and the heavy layer are cured by hydrosilylation reaction.

4. The layered silicone rubber composite guide plate with indirect bonding via self-locking brackets according to claim 1, characterized in that, The rigid support structure formed by the weighted layer extends to the lingual or palatal side of the dentition and has a continuous overlay at the incisal edge of the crown, utilizing the undercut of the tooth anatomical morphology to provide mechanical retention force when the guide plate is in place.

5. The method for manufacturing a layered silicone rubber composite guide plate indirectly bonded by self-locking brackets according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Model pretreatment: Apply a separating agent to the surface of the dental mold with brackets and then dry it; S2, Transparent intermediate layer coating: After mixing the raw materials of the transparent intermediate layer, the coating is applied to the surface of the bracket and crown after the pretreatment in step S1; S3. Rheological timing control: After the coating is completed in step S2, let it stand and wait until the surface of the transparent intermediate layer loses its gloss and enters the thixotropic peak period. S4. Hydraulic penetration locking and heavy body construction: After mixing the raw materials of the heavy body layer, it is covered on the surface of the transparent middle body layer, which is in the thixotropic peak period after being treated in step S3, and vertical pressure is applied. The high viscosity of the heavy body layer forces the transparent middle body layer to undergo secondary flow and fill the groove indentation. Then the heavy body layer is shaped and extended. S5. Synchronous curing and separation: After the double-layer structure formed in step S4 is allowed to stand and undergo synchronous chemical cross-linking and curing, the cured whole is immersed in water for water bath treatment. After reducing the interfacial resistance by using water film lubrication, the composite guide plate is removed from the dental mold.

6. The self-locking bracket indirect bonding layered silicone rubber composite guide plate and its manufacturing method according to claim 5, characterized in that, The settling time in step S3 is 15 to 20 seconds; the settling time is used to allow the transparent middle layer to establish a preliminary thixotropic network, preventing excessive loss of the middle material when pressure is applied in step S4.

7. The self-locking bracket indirect bonding layered silicone rubber composite guide plate and its manufacturing method according to claim 5, characterized in that, In step S4, the vertical pressure ranges from 0.05 MPa to 0.15 MPa, and the pressure duration is from 5 to 10 seconds. The hydraulic penetration locking refers to using the heavy body layer as a pressure transmission medium under pressure to force the transparent middle body layer, which is in the thixotropic peak period, to form a gapless mechanical interlock with the bottom plate of the tray and the inverted wing, and to expel interface bubbles.

8. The self-locking bracket indirect bonding layered silicone rubber composite guide plate and its manufacturing method according to claim 5, characterized in that, The synchronous curing time in step S5 is 5 to 8 minutes; the curing environment temperature is controlled at 23℃±2℃.

9. The self-locking bracket indirect bonding layered silicone rubber composite guide plate and its manufacturing method according to claim 5, characterized in that, In step S5, the composite guide plate is removed from the dental mold by either a layer-by-layer removal method or a whole-piece prying removal method. The layered removal method involves first separating and removing the heavy body layer, and then removing the transparent intermediate body layer; the overall prying removal method involves using an instrument to pry at the labial side of the crown or the interproximal space, using the tooth surface as a fulcrum, so that the transparent intermediate body layer and the heavy body layer are separated from the dental model as a whole.

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