RU2805832C1 - Method of manufacturing temporary dental crowns by 3d printing method - Google Patents

Abstract

FIELD: medicine; orthopedic dentistry.

SUBSTANCE: method of manufacturing temporary dental crowns by 3D printing includes tooth preparation with the formation of an identical circular subgingival ledge throughout the tooth, gum retraction using a retraction thread, scanning of antagonist teeth, prepared teeth, and scanning of jaw ratio in occlusion using an intraoral scanner. Full virtual 3D models of the working and antagonists jaws in a fixed position are obtained, the retraction thread is removed. Temporary crowns are modeled in full anatomy, taking into account all individual occlusal and proximal contacts, creating an anatomical prototype of a permanent structure on a virtual model. Temporary crowns are made by printing on a 3D printer from a photopolymer material, post-processing of a 3D model and a temporary structure is performed, a temporary prosthesis design is fitted on a 3D prototyped working model. Sandblasting, grinding, polishing and fitting of temporary structures on the supporting tissues of the prosthetic bed in the patient's oral cavity are carried out, followed by occlusal correction and fixation on polycarboxylate cement.

EFFECT: accuracy of manufacturing temporary crowns and bridges is increased due to modeling in a computer program on a three-dimensional image magnified by 12 times, and production by 3D printing, the shrinkage error and expansion coefficient are reduced, the service life of temporary structures is extended, the possibility of manufacturing a structure in one visit of the patient is achieved, the absence of traumatic stress in the process of fitting temporary structures, uniform redistribution over the entire surface under the influence of masticatory pressure are provided.

1 cl, 10 dwg

Description

The invention relates to medicine, in particular to dentistry, and can be used in orthopedic dentistry, for defects in hard dental tissues, and partial absence of teeth.

Currently, the manufacture of structures is a mandatory step in the manufacture of permanent structures. There is a known method for obtaining temporary crowns [See. auto date RU No. 2280421 C2 MPK A61S 13/00]. This method is successfully used in medicine, but has disadvantages, as it requires taking impressions, using a plaster model, the use of additional materials and time at the manufacturing stage. This method is taken as a prototype.

The basis of the invention is the task of creating the most accurate, fast and economical method for manufacturing an orthopedic structure in dentistry.

This problem is solved by the fact that the method proposes the production of temporary crowns using 3D printing.

The inventive method makes it possible to produce the most accurate temporary structure without taking impressions and making plaster models with less time and economic costs.

The method of manufacturing a temporary structure using 3D printing is carried out as follows.

1. The teeth are prepared with the formation of an identical circular subgingival ledge along the entire length of the tooth. Gum retraction is performed using a retraction thread to more accurately scan the edge of the ledge, Fig. 1. After tooth preparation and gum retraction, using an intraoral scanner, the antagonist teeth, prepared teeth are scanned, as well as the jaw relationship in the bite is scanned for 10-15 minutes, which is equivalent in time to taking impressions for the working and auxiliary model and registering the bite. The retraction thread is removed. The use of an intraoral scanner simplifies obtaining a negative image of prepared teeth, since direct visualization of the scanned object occurs.

If biological fluid enters during scanning or taking impressions, the accuracy of the negative image will be distorted, which means the manufactured structure will not be of adequate quality. The advantage of intraoral scanning is the ability to instantly correct a fragment with flaws, but the impression will have to be redone entirely, wasting time and consumables. You immediately receive complete virtual 3D models of the jaws - the working one and the antagonists in a fixed position, illustration in Fig. 2, fig. 3, on a personal computer screen using special software.

With the known method according to the prototype for obtaining temporary crowns, [See. auto date RU No. 2280421 C2 MPK A61S 13/00] the impressions need to be filled with plaster, plaster models are made and plaster is placed in the articulator along the occlusal bites in a fixed position. The time interval spent at this stage is 240-270 minutes, Fig. 4, fig. 5.

2. Modeling of future crowns is performed on the monitor screen 1-2 crowns for 30 minutes, for each subsequent 1-2 units about 10-15 minutes additionally, in full anatomy, taking into account all individual occlusal and proximal contacts, creating an aesthetic prototype of a permanent structure, fig. 6. Changes taking into account the patient’s wishes are made without much additional time. With the method of making temporary crowns taken as a prototype, this stage of 1-2 units (the design of the future temporary fixed prosthesis is modeled on a model from wax) of modeling is from 40 minutes, for each subsequent 1-2 units about 15-20 minutes, remodeling according to aesthetic wishes patient occurs over a slightly shorter time period than the initial simulation. They transfer the modeled model to the clinic, the doctor additionally takes an impression of the model, fills the impression with quick-hardening plastic, places an impression on the dentition, grinding and polishing is done clinically, which is quite labor-intensive, and it is not always possible to achieve a good result. To take an impression from the model and final production of a temporary crown, it is clinically necessary from 10 to 20 minutes. The total time interval from the moment of taking impressions and fixing the temporary structure is from 300 to 345 minutes

3. A working 3D model is made by printing on a 3D printer from a polymer material, illustration in Fig. 7.

4. Temporary crowns are made by printing on a 3D printer from the material “Photopolymer” (“Harzlabs Dental Sand”, registration certificate for a medical product No. RZN 2020/12007. country Russia) Fig. 8.

5. Post-processing of the 3D model and temporary structure. In total, the stage of printing, post-processing, grinding, polishing of the working 3D model and temporary structure ranges from 140-170 minutes.

6. The temporary structure of the prosthesis is adjusted by checking the tight fit of the crown and the circular ledge on the 3D printed working model, the tightness of the proximal contacts, the physiology of the occlusal relationship Fig. 9. There is a known patent (RU 2494698 C1) for optimal positioning of implants in the jaw bones with complete or partial absence of teeth in the jaw; modeling is carried out by prototyping a stereolithographic model of the jaw with sleeves, the position of which corresponds to the placed implants. Used as a surgical template.

7. Laboratory sandblasting to improve the retention of temporary cement.

8. Grinding and polishing of the prosthesis is performed.

9. Temporary structures are tried on and the structure is applied to the abutment teeth with fixation to polycarboxylate cement in the patient’s oral cavity, carrying out occlusal correction if necessary, the time interval is 5-10 minutes, Fig. 10. The total time interval from the moment of scanning and fixation of the temporary structure is from 155 to 195 minutes.

There is a known clinical method for making temporary crowns (RU 2619489 C1). The formed tooth stump is compressed from the vestibular and oral surfaces, tightly pressed to the contact surfaces of adjacent teeth with a 1.8 mm thick base wax plate cut to the size of the defect, preheated over a burner flame. During the closure of the dentition, the occlusal relationships are corrected. In this way, a reproduction of the future crown is obtained. Next, a standard perforated stainless steel impression tray is selected that matches the shape and size of the patient’s jaws. An impression is taken from the dentition using silicone impression mass. The wax from the resulting impression is removed and replaced with the composite material “Stractur 2 SC”. The disadvantages of this method are:

• the difficulty of creating an anatomical artificial tooth in the shape and size of the corresponding functional group, since a prototype of the future structure is formed in the oral cavity with a heated wax plate, which subsequently complicates the process of occlusal relationships, and therefore can lead to umbilical nervous system disorder.

• lack of temporary aesthetic result and lack of consistency in the future permanent orthopedic design (crown length, thickness, inclination, shape).

• during taking an impression with silicone mass for a bridge structure and during closure of the dentition to correct occlusal relationships, the base wax can shift, creating significant inaccuracies in shape and occlusal contacts.

• replaced with the composite material “Structur 2 SC” is accompanied by the formation of pores and a non-homogeneous rough surface with further complaints of bad breath. Fitting into the oral cavity and giving the final shape of the crown with a milling cutter requires a lot of time for the doctor, and most often it is just a cap made of a composite material that has nothing to do with the anatomy and shape of the tooth.

The proposed method for manufacturing temporary crowns has the following advantages in comparison with traditional methods for manufacturing this type of orthopedic dental structures:

1. Less invasiveness of the clinical stage of taking impressions, therefore, the absence of a plaster model stage, the error for shrinkage and expansion coefficient becomes smaller

2. Making temporary crowns using an optical impression reduces labor costs and time for constructing the structure in one patient visit.

3. Increasing the economic efficiency of manufacturing this type of orthopedic dental structures, reducing the amount of basic and auxiliary consumables used in the clinic and dental laboratory. This circumstance together reduces the cost of dental treatment, the intermediate stage of the temporary structure and the entire orthopedic product for consumers, making dental care more accessible to everyone

4. Higher accuracy in the manufacture of temporary crowns and bridge structures due to the fact that the modeling is performed virtually in a computer program on a three-dimensional image, enlarged by 12 times, which allows for increased visual accuracy of the modeling, and the manufacturing of structural elements is carried out using high-precision 3D printing .

5. The best physical and chemical properties of this material, Harzlabs Dental Sand, are stated by the manufacturer to be used for temporary structures for up to 6 months, while standard temporary structures are used for up to 3 months.

6. Lack of traumatic stress during the process of fitting temporary structures. Uniform redistribution over the entire surface under the influence of chewing pressure.

7. Lack of porosity of the main structural materials in comparison with acrylic plastics and dual-curing photopolymers, traditionally used for the manufacture of temporary crowns using the classical method, which increases the hygienic characteristics of dentures and extends their service life.

8. The absence of residual monomer in structural materials, in contrast to those traditionally used for the manufacture of temporary structures made of acrylic plastics, avoids possible pathological reactions of the oral mucosa and prosthetic bed in the form of allergic reactions and toxic denture stomatitis.

9. Reducing the labor costs of the dental technician at the stages of manufacturing temporary structures and eliminating various stages of dental production (making a plaster model, preparing plaster columns, wax modeling, packaging and polymerization of acrylic plastics, etc.), since there is a full cycle of manufacturing temporary crowns using 3D printing , which generally improves the hygienic working conditions of dental technicians, and increases the number of products due to computerization and automation of dental production.

10. Simplifies the stage of taking impressions in patients with an increased gag reflex.

Claims (1)

A method for manufacturing temporary dental crowns using 3D printing, including preparing teeth with the formation of an identical circular subgingival ledge along the entire length of the tooth, retracting the gums using a retraction thread, scanning antagonist teeth, prepared teeth, as well as scanning the relationship of the jaws in the bite using an intraoral scanner, obtaining complete virtual 3D models of jaws - working and antagonists in a fixed position, extraction of a retraction thread, modeling of temporary crowns in full anatomy, taking into account all individual occlusal and proximal contacts, creating an anatomical prototype of a permanent structure on a virtual model, production of temporary crowns by printing on a 3D printer from photopolymer material, post-processing of the 3D model and temporary structure, fitting of the temporary structure of the prosthesis on a 3D prototyped working model, sandblasting, grinding, polishing, fitting of temporary structures onto the supporting tissues of the prosthetic bed in the patient’s oral cavity, followed by occlusal correction and fixation with polycarboxylate cement.