RU114843U1 - DEVICE FOR STRENGTH TESTING OF FILLING MATERIALS AND SEALS OF DEFECTIVE TEETH - Google Patents

Abstract

A device for strength testing of filling materials and fillings of defective teeth, containing a load generation unit, an antagonist tooth, a test tooth, four pressure sensors, an electronic unit for collecting and digitizing measurement information, an ultrasonic sensor for detecting the onset of fracture of a defective tooth filling, characterized in that four strain gages glued in the form of a rectangle to the tooth around the filling or to the controlled area of the sample made of filling material, the strain gauge leads are connected, respectively, to the eight inputs of the strain measurement unit, eight outputs of which are connected to eight inputs of the electronic unit for collecting and digitizing measurement information, to the ninth input of which is connected the output of the resistive sensor for detecting the beginning of the destruction of the seal, and the outputs of the block for optical, acoustic and electrometric control of the seal adherence are connected to the tenth, eleventh and twelfth inputs, respectively.

Description

The utility model relates to dental testing equipment and can be used to select adhesive systems for filling carious cavities, as well as to determine the strength characteristics and fracture kinetics of wide class samples.

A known method for assessing the state and effectiveness of filling hard tissues of a tooth [Patent R.F. No. 2112427 dated 10/06/98, IPC A61B 6/00. Assessment of the state and effectiveness of filling hard tooth tissues / M.T.Alexandrov, S.Yu. Kozma, I.M. Taubinsky and others], including the formation of the cavity of the tested defective tooth, filling it with filling material, polishing the obtained surface, determining the condition and the effectiveness of the filling by the size of the gap (arising from poor-quality filling) between the tooth and the filling by evaluating the fluorescence of the photochrome introduced into the gap (for example, photosens) when recording with an infrared spectrophotometer trazhennogo radiation by the polished surface of the seal helium-neon laser. The disadvantage of this method is that the strength of fillings of defective teeth is judged without forming a load on the defective tooth and only by the quality of the marginal fit of the fill on its external polished surface.

Known installation for testing materials for contact endurance [A. USSR No. 1536264 dated 15.01.90, IPC G01N 3/56. Installation for testing materials for contact endurance / S.G. Kostogryz, V.V. Kovalevsky, V.G. Kaplun and others], comprising a housing, three parallel shafts mounted on supports in one plane, the middle of which is designed for placing a sample of material, and the two extremes for pressure counter samples, a loading device and a pulsator to create a cyclic load on the sample. The disadvantages of the device are the inability to automate the tests due to the lack of a sensor for the onset of sample destruction, the complexity of the installation.

A known method for diagnosing the state of the dentofacial system [RF Patent No. 2138981 from 10.10.99, IPC A61B 5/00. A method for diagnosing the state of the dentofacial system / P.M. Mulyukov, L.M. Bakusov]. A device for implementing this method comprises a dosed shock device, a sensing element (a miniature microphone that picks up tooth vibration and is mechanically connected to the tooth), an information amplification and conversion device, an information analysis and presentation device (which is used as a computer), the analysis is carried out by comparing the amplitude-frequency characteristics of the studied tooth with either a reference (typical for a healthy tooth, taking into account age and diagnosis) or with metric tooth of the same patient (if you know that he is healthy). The disadvantage of this device is the inability to determine the strength characteristics of fillings of defective teeth.

A device for testing the teeth of the wheels [A.S. USSR No. 815559 dated 03.23.81, IPC G01M 13/02. A device for testing the teeth of the wheels / OI Kuzmenkov, OV Berestnev, MP Biryukov]. The device is a unit for generating the load on the test tooth and contains a shaft connected to the drive, a multi-profile cam mounted on it (sections of the working surface of which are identical to the working surface of the tooth mating with the subject), a cam eccentricity regulator relative to the shaft, a static load generating mechanism (directed perpendicular to the axis of the shaft and the contact line of the interacting surfaces), a pulsator (interacting with the shaft in a plane perpendicular to the increase of the static load), in this case, to carry out strength tests, the test tooth is supported by the vertex zone under the cam working surface and loaded with the required load from the static loading mechanism and by setting the corresponding cam eccentricity, then when the cam rotates from the drive shaft, the side profile the test tooth is loaded through the protrusions of the cam with a variable cyclic load, and the oscillatory movement of the cam specified by the pulsator (in the plane axis perpendicular to the plane of application of static load) imitates during testing the process of slipping of the test tooth in the engagement zone. The disadvantages of the device are the use of a non-universal, replaceable (interfaced only with the profile of the tested tooth) cam for tooth testing, the inability to automate testing due to the lack of a tooth decay start sensor, as well as the lack of information about the actual load on various tooth sections during the test, low measurement accuracy .

Closest to the claimed is a device for testing the strength of fillings of defective teeth [RF Patent No. 51861 of 03/10/06, IPC A61C 5/00, G01N 3/08. A device for testing the strength of fillings of defective teeth / T.L. Redinova, T.Yu. Meteleva, Yu.K. Shelkovnikov], containing a load generating unit, a tested tooth, an antagonist tooth attached to the base with the possibility of vertical movement and consisting of four longitudinal segments, while between the segments of the antagonist tooth and the base there are respectively four pressure sensors, the outputs of which are respectively connected to the first, second, third and fourth inputs of the electronic unit for collecting and digitizing the measuring and information, the output of which is connected to the input of the computer, and the fifth input is connected to the output of the ultrasonic sensor for detecting the beginning of the destruction of the fillings of the defective tooth, placed on the fastening block of the defective tooth and in mechanical contact with the seal, while the input of the load forming unit is connected to the output of the computer. The disadvantages of the device are the inability to determine the strength characteristics of fillings of defective teeth and assess the quality of fillings in statics, during operation and when the seal is torn.

The objective of the utility model is to expand the functionality of the device, increase the accuracy and reliability of tests, as well as expand the range of information received.

The problem is solved in that the device comprises a load shaping unit, an antagonist tooth, a test tooth, four pressure sensors, an electronic unit for collecting and digitizing measurement information, an ultrasonic sensor for detecting the start of destruction of a tooth seal for a defective tooth. At the same time, four strain gages are inserted into the device, glued in the form of a rectangle on the tooth around the fillings or on the controlled portion of the sample from the filling material, the terminals of the strain gages are connected respectively to eight inputs of the strain measurement unit, eight outputs of which are connected to eight inputs of the electronic unit for collecting and digitizing measurement information , to the ninth input of which the output of the resistive sensor for detecting the beginning of the destruction of the seal is connected, and to the tenth, eleventh and twelfth inputs outputs respectively connected optical blocks and acoustic control abutment electrometric seal.

The structural diagram of a device for testing the strength of fillings of defective teeth is shown in figure 1.

The device contains a tested defective tooth 1 with a filling 2, a block 3 of its attachment to a device 4 for forming a load on a defective tooth, four segments of an antagonist tooth 5 with pressure sensors 6, an ultrasonic sensor for detecting the beginning of destruction of a filling 7, a resistive sensor 8 for detecting the beginning of a destruction of a filling, block 9 optical, acoustic and electrometric control of the fit of the seal, four strain gauges 10, block 11 strain measurements, electronic block 12 for collecting and digitizing measurement information, computer 13.

The device operates as follows. According to a given program, the computer controls the block 4 of the formation of the load on the defective tooth, which creates a varying pressure on the tooth 1.

The upper antagonist tooth is sawn into four segments 5, each of which has the ability to move in a small range (~ 0-3 mm) in the vertical direction with its subsequent fixation in order to create local pressure in the studied area of the defective tooth. Between segments 5 of the antagonist tooth and the base of the device, 4 pressure measuring sensors are fixed 6. Analog pressure information for each segment 5 is digitized by an analog-to-digital converter of block 8 and fed to the computer 13. The computer can program different loads on the defective tooth 1 and record all measuring information about the load on the filling 2 using four measuring pressure sensors 6, mounted on each of the four segments of the antagonist tooth. To increase the reliability of detection of the beginning of the destruction of the seal 2, two independent sensors are used: ultrasonic 7 and resistive 8. If a crack occurs between the seal 2 and the defective tooth 1 at the beginning of acoustic emission, the ultrasonic sensor 7 [Ultrasound. Little Encyclopedia. Chap. ed. I.P. Golyamin. - M .: Soviet Encyclopedia, 1979. - S.391-393], as well as a resistive sensor 8 [Ivanova G.G. Diagnostic and prognostic assessment of electrometry of hard tissues of teeth during caries: Auth. dis. Cand. honey. sciences. - Omsk, 1984. - 209 pp.] By the change in electrical resistance between the filling and the tooth, the beginning of the destruction of the filling 2 is recorded independently of each other. In this case, the resistive sensor 8 is based on the property of edge permeability at the seal-tooth border: to form depending on the quality of the edge the fit of the seal is a different electric current between the first electrode glued to the seal (or located inside the seal during its manufacture) and the second electrode glued to the defective tooth.

The main reason for the destruction of carious cavity restorations is the stresses arising at the tooth-filling interface, which necessitates studying the ratio of the strength characteristics (Young's modulus, Poisson's ratio, etc.) of the material and the tooth to ensure their reliable and durable connection. To measure the strength characteristics of a defective tooth (or samples from filling materials) around the filling 2 on tooth 1 (or around the test area of the sample from the filling material), four strain gages 10 are glued forming a rectangle, each of which is included in the shoulder of its measuring bridge of the strain measuring unit 11. When changing the working base glued to the tooth 1 of the strain gauges 10, their electrical resistance also changes, accompanied by the imbalance of the corresponding measuring bridges. In this case, the strain gauges are pre-calibrated in units of length by stretching on a calibration machine with registration of balances of the corresponding measuring bridges according to [Pedder V.V., Leontyev V.K., Ivanova G.G. et al. Own stress state of a tooth, possibilities and prospects of its use in dentistry // Scientific Research in Dentistry, No. 65, Institute of Dentistry, 2002]. Then, by the known values of the load and deformation, the desired strength characteristics of the defective tooth (or samples from filling materials) are calculated. In particular, Young's modulus of elasticity E and Poisson's ratio µ are found by the formulas:

and ,

Where is the voltage corresponding to the increment of the force P during loading; F is the cross-sectional area of the working part of the sample; and - respectively, the relative longitudinal and transverse strains; Δl _prod and Δl _pop - respectively, the absolute longitudinal and transverse deformation; l is the length of the strain gauge.

The quality control of the filling is carried out by the unit 9 of optical, acoustic and electrometric control of the fit of the seal, which does not require special preparation of the defective tooth 1 and seal 2 for inspection and allows periodically to register the marginal fit of the seal every every n-load on the tooth with an increase in the number of exposure cycles. A feature of the built-in digital optical microscope of block 9 is two channels (“watching” with different magnifications at one point), which allows you to analyze the control area as a whole, and with a large increase in its information part. Acoustic control using block 9 makes it possible to localize hidden cavities, defects in the thickness of the filling material, delamination at the border of the seal and tooth [Mayev R.G. Acoustic Microscopy - M .: Torus-Press, 2005. - 385 p.]. The electrometric control using block 9 is based on the ability of hard tooth tissues to transmit an electric current depending on the degree of carious damage and allows you to reliably determine the quality of the marginal fit of the filling 2. The assessment of edge permeability at the filling-tooth border is carried out using two electrodes: active with a point contact element in the form of a capillary tube of conductive material and passive silver chloride in the form of a thin flexible plate fixed on an elastic basis [Ivanov and G.G. Diagnostic and prognostic assessment of electrometry of hard tissues of teeth during caries: Auth. dis. Cand. honey. sciences. - Omsk, 1984. - 209 p.]. At the same time, the use of a comprehensive assessment of the quality of the filling based on block 9 of the optical, acoustic, and electrometric control makes it possible to effectively detect not only visual, but also hidden defects, as well as to increase the reliability of the results.

Compared with the prototype of the proposed device has the following advantages. Firstly, the functionality of the device is expanded. The strength characteristics (Young's modulus, Poisson's ratio, etc.) are measured in dynamics and statics for a defective tooth and samples from filling materials necessary for theoretical and experimental studies (in particular, for modeling and calculating the stress-strain state of the tooth and fillings). In this case, the “opening” of the cavity is monitored after the preparation of the tooth and its reduction after filling due to shrinkage of the filling material. Secondly, the reliability of detecting the beginning of the destruction of the seal is increased due to the introduction of an additional resistive sensor for measuring the electrical resistance of the edge fit of the seal. Thirdly, the above parameters are controlled both in statics and in dynamics - during the operation of the tooth and when the fillings are torn off.

Claims (1)

A device for strength testing of filling materials and fillings of defective teeth, comprising a load generating unit, an antagonist tooth, a test tooth, four pressure sensors, an electronic unit for collecting and digitizing measurement information, an ultrasonic sensor for detecting the start of destruction of a defective tooth fill, characterized in that four strain gauges glued in the form of a rectangle on the tooth around the fillings or on a controlled portion of the sample from the filling material, the terminals of the strain gauges are connected to Responsibly to the eight inputs of the strain measurement unit, eight outputs of which are connected to eight inputs of the electronic unit for collecting and digitizing measurement information, the ninth input of which is connected to the output of the resistive sensor for detecting the onset of seal failure, and the outputs of the optical unit are connected to the tenth, eleventh, and twelfth inputs, acoustic and electrometric control of the fit of the seal.