System Having A Laser And An Adhesive For The Securing Of A Dental Restoration Part And Method For Securing A Restoration Part, In Particular A Dental Restoration Part

Abstract

The invention relates to a system consisting of a laser which emits laser radiation with a wavelength of more than 1300 nm, in particular between 2750 nm and 3200 nm, and a dental adhesive for applying a dental restoration part to a pre-treated, in particular cleaned, adhesive base which is formed by hard dental tissue or by denture material. The viscous dental adhesive applied to the adhesive base, which is free of a dental restoration part, can be activated, in particular without blowing or agitation, by applying laser radiation.

Claims

1. A system comprising a laser and a dental adhesive, wherein the laser emits laser radiation with a wavelength of 1300 nm or more, wherein the dental adhesive is suitable for application to a pre-treated adhesive base formed by dental hard tissue, denture material or dental restorative material, wherein the dental adhesive is adapted for treatment by applying laser radiation, and wherein the dental restoration part is secured on the treated dental adhesive.

2. The system according to claim 1, wherein the wavelength is in the range of 2750 nm and 3200 nm, wherein the pre-treated adhesive base is cleaned, wherein the dental adhesive is adapted for treatment by activation without blowing or agitation, wherein the laser radiation is applied while the dental adhesive is free of a dental restoration part, and wherein the dental restoration part is secured on the activated dental adhesive.

3. The system according to claim 1, wherein the laser (16) is designed as a solid-state laser with at least one emission maximum at a wavelength between 2750 nm and 3200 nm, and is designed as a pulsed laser comprising an Er:YAG laser.

4. The system according to claim 1, wherein, during the application of laser radiation to provide a laser treatment, the laser treatment takes place for a time in a range of 0.5 sec to 15 sec or in a range of 2 sec to 8 sec, and emits pulsed laser radiation (20) with a pulse/pause ratio in a range of 1:1 to 1:1000 or in a range of 1:5 to 1:200 or 1:25 or provides a continuously emitting laser radiation.

5. The system according to claim 1, wherein the laser (16) is configured as an unpulsed laser comprising a diode laser.

6. The system according to claim 1, wherein the laser (16) is configured with at least one emission maximum at a wavelength between about 1400 and 1600 nm.

7. The system according to claim 1, wherein the adhesive (14) is applied in a layer thickness of 0.08 or less mm, or 0.03 mm or less and or between 0.01 to 0.02 mm.

8. The system as claimed in claim 1, wherein the laser (16) is used is a bacteria removal laser.

9. The system according to claim 1, wherein the laser (16) emits radiation (20) into a light guide (19), the distal end of which is bent and/or flexible, and wherein the radiation (20) of the laser (16) can be directed through the light guide (19) to the dental adhesive (14) and the adhesive base (10).

10. The system according to claim 1, wherein a sensor (26) is provided which responds to radiation in the wavelength range between 1000 nm and 15000 nm and has a sensitivity maximum above or below the emission maximum of the laser.

11. The system according to claim 10, wherein the sensor (26) is configured as a reflection detection sensor which is attached to a handpiece (24) of the laser (16) or proximate thereto and is movable together therewith.

12. The system according to claim 11, wherein the sensor (26) detects radiation emitted by the laser (16) when directing the radiation of the laser (16) towards the adhesive base (10) and the dental adhesive (14).

13. The system according to claim 10 wherein a target or aiming light source (27) is mounted adjacent to and substantially parallel to the laser (16).

14. The system according to claim 13, wherein the target or aiming light source (27) emits light visible on a focus spot (29).

15. The system according to claim 1, wherein the laser (16) comprises a deflection tip (46) with which outgoing radiation (20) is deflected with respect to an axis (50) of the laser (16).

16. The system according to claim 5, wherein, during the application of laser radiation to provide a laser treatment, the laser treatment takes place for a time in the range of 2 sec to 8 sec, and emits pulsed laser radiation (20) with a pulse/pause ratio in a range of 1:5 to 1:200 or at about 1:25.

17. A method for securing a restoration part comprising a dental restoration part (40) using a dental adhesive (14) to secure the part onto an adhesive base (10), comprising pre-treating the adhesive base (10) wherein pre-treating includes cleaning the adhesive base (10), applying the dental adhesive (14) to the adhesive base (10), treating the dental adhesive (14) applied to the adhesive base (10) with a laser which emits radiation (20) in a wavelength range of 1300 nm or more or 1400 nm or more, and applying the restoration part (40) onto the dental adhesive (14) and adhesive base (10).

18. The method as claimed in claim 17, wherein the laser (16) is designed as a solid-state laser having at least one emission maximum at a wavelength between 2750 nm and 3200 nm, and comprising an Er:YAG laser.

19. The method as claimed in claim 17, wherein the laser (16) is configured with at least one emission relative maximum at a wavelength between about 1400 and 1600 nm, and wherein the laser (16) is configured as a diode laser.

20. The method as claimed in claim 17, wherein, during the laser treatment step, the laser treatment is effected for a time in the range of 0.5 s to 15 s, or 2 s to 8 s, and wherein the laser is configured as a pulsed laser or as a continuously emitting laser, wherein the pulsed laser outputs pulsed laser radiation (20) at a pulse/pause ratio in the range of 1:1 to 1:1000 or of 1:5 to 1:200 or at about 1:25.

21. The method as claimed in claim 17, wherein, in the step of applying the dental adhesive, the dental adhesive (14) is applied in a layer thickness in a range of 0.03 mm to 0.1 mm.

22. The method as claimed in claim 17, wherein, in the step of applying the dental adhesive, the dental adhesive (14) is applied in a layer thickness in a range of 0.01 mm to 0.02 mm.

23. The method as claimed in claim 17, wherein the laser treatment step directly follows the step of applying the dental adhesive (14), without any massaging-in and/or agitation of the dental adhesive (14) into or onto the adhesive base (10), and without any blowing of the dental adhesive (14).

24. The method as claimed in claim 17, wherein the laser (16) comprises a bacteria removal laser.

25. The method as claimed in claim 17, wherein the laser (16) outputs radiation (20) into a light guide (19), the distal end of which is offset and/or flexible, and wherein the radiation (20) of the laser (16) is directed by the light guide (19) to the dental adhesive (14) and the adhesive base (10).

26. The method as claimed in claim 17, wherein, with the pre-treatment step or before or after the pre-treatment step, the adhesive base (10) is irradiated, roughened and/or heated, with the laser (16).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Further advantages, details and features will be apparent from the following description of several embodiments of the invention with reference to the drawings.

[0092] In the drawings:

[0093] FIG. 1 shows a schematic perspective view of a system including a laser and adhesive, in one embodiment of the invention, to explain the system including a laser and an adhesive in accordance with the invention;

[0094] FIG. 2 shows a detail of a further embodiment of an inventive system including a solid-state laser and an adhesive;

[0095] FIG. 3 shows a schematic view of the adhesive curing after application of the dental restoration part to the adhesive;

[0096] FIG. 4 shows a graph to illustrate the shear strength which can be achieved at different irradiation times during the formation of the adhesive base as enamel as well as when using a pulsed laser;

[0097] FIG. 5 shows a graph to illustrate the shear strength which can be achieved at different irradiation times during the formation of the adhesive base as dentin and using a pulsed laser;

[0098] FIG. 6 shows a graph to illustrate the shear strength which can be achieved at different irradiation times during the formation of the adhesive base as enamel and using a non-pulsed laser;

[0099] FIG. 7 shows a graph to illustrate the shear strength which can be achieved at different irradiation times during the formation of the adhesive base as dentin and using a non-pulsed laser;

[0100] FIG. 8a shows a further embodiment of a treatment laser having a tip which is particularly suitable for performing the laser treatment step in deep cavities; and

[0101] FIG. 8b shows a further embodiment of a treatment laser having a tip which is particularly suitable for performing the laser treatment step in deep cavities.

DETAILED DESCRIPTION

[0102] An embodiment of a system in accordance with the invention is described with reference to FIG. 1.

[0103] FIG. 1 shows an adhesive base 10 on or at a tooth 12, in the illustrated exemplified embodiment a molar or a premolar with a cavity in the occlusal surface.

[0104] For pre-treatment purposes, milling, grinding and/or polishing of the tooth hard tissue is performed in a manner known per se until only healthy tissue is present.

[0105] If required, an etchant can be applied in a manner known per se for pre-treatment purposes.

[0106] In a manner likewise known per se, an adhesive 14 is applied to the adhesive base 10.

[0107] By means of a spreading apparatus, such as e.g., by means of a micro brush or another suitable dental applicator, the applied adhesive 14 is distributed to produce a layer of less than 0.03 mm.

[0108] This application constitutes the application step, the second step.

[0109] In a third step, in accordance with the invention, the laser treatment step, a treatment laser 16 is oriented with its radiation-emitting surface 18 on a light guide rod as a possible exemplified embodiment of a light guide 19 such that the exiting laser beam which forms the radiation 20 is directed onto the adhesive layer 14. The laser 16 is switched on and as a result the adhesive layer is subjected to a laser treatment.

[0110] In the embodiment shown, the laser 16 is a solid-state laser, namely an Er:YAG laser. It has an emission maximum at a wavelength of 2940 nm and a mains or power connection 21. Preferably, the Er:YAG laser has an electrical power of between 0.4 watts and 10 watts, preferably between 1 watt and 2 watts and particularly preferably of 1.3 watts.

[0111] In the illustrated exemplified embodiment, the adhesive base 10 consists mostly of tooth enamel and to a lesser extent of dentin. It is important that the adhesive 14 demonstrates good shear strength throughout.

[0112] For example, an irradiation time of 5 seconds is specified by a control device 22, and accordingly the laser 16, which may be designed as a pulsed (tests 1 and 2) or continuous (tests 3 and 4) laser, is switched on for 5 seconds.

[0113] By this laser exposure with the laser radiation 20 in the wavelength range mentioned, the adhesive 14 is conditioned in such a way that it has a high shear strength after application of the dental restoration and after polymerisation of the adhesive, i.e. after completion. This system consisting of treatment laser and adhesive according to the invention is the only way to achieve the desired surprisingly high shear strength in a time-saving manner.

[0114] In the first two embodiment examples (tests 1 and 2), a pulsed laser with a pump current of 300 amperes with a pulse duration of 300 microseconds, a pulse frequency of 150 Hz and an average laser power, i.e. averaged over the pulse sequence, of 1.3 W is used. The beam diameter is 5.4 mm.

[0115] A total of four tests were carried out with embodiments using the system consisting of a laser and an adhesive according to the invention.

[0116] In the first test, bovine tooth enamel was selected as the adhesive base 10. The test was repeated at different irradiation times by the pulsed laser and the following shear strength values were achieved according to table 1 below (pursuant to ISO 29022):

TABLE-US-00001 TABLE 1 (Test 1) Radiation/s 10 7.5 5 2.5 1 0 n/a (Reference according to standard) Number of tests 5 5 20 5 5 4 5 Average shear 18.38 21.75 20.22 21.47 22.94 19.11 22.09 strength value in MPa Standard 2.64 7.69 4.84 2.46 6.57 1.31 2.67 deviation Min 14.93 15.16 11.57 17.8 19.25 17.83 19.64 Max 21.3 32.81 31.45 23.62 34.61 20.71 25.56 Fracture adhesive adhesive adhesive adhesive adhesive adhesive adhesive appearance

[0117] The fracture pattern can be adhesive or cohesive, as shown in the table. An adhesive fracture is a fracture that runs exactly along the phase interface between the surface of the part to be joined and the adhesive. This type of fracture results in a complete separation of the adhesive from the substrate surface(s). The test was repeated with bovine dentin as the adhesive base 10.

[0118] A cohesive fracture means that the adhesion of the adhesive at the phase boundaries is greater than the fracture strength of the adhesive base. The adhesive joint therefore survives the fracture test and the substrate breaks instead.

[0119] The shear strength values shown in table 2 below were achieved (pursuant to ISO 29022):

TABLE-US-00002 TABLE 2 (Test 2) Radiation/s 10 7.5 5 2.5 1 0 n/a (Reference according to standard) Number of 5 5 20 5 5 5 5 tests Average shear 29.27 31.21 34.19 30.80 17.89 18.47 33.08 strength value in MPa Standard 5.18 3.65 7.59 2.07 3.36 1.92 3.89 deviation Min 22.93 26.98 20.46 27.59 13.31 16.18 26.69 Max 36.72 36.15 46.56 32.97 22.10 21.38 37.31 Fracture 3/5 4/5 19/20 cohesive adhesive adhesive cohesive appearance cohesive cohesive cohesive

[0120] Tests 1 and 2 were carried out using pulsed laser radiation and the system consisting of a laser and an adhesive according to the invention.

[0121] Experiments 3 and 4 were also carried out using a continuously operated, i.e. unpulsed, diode laser. The results are shown in the tables below.

[0122] In Test 3, bovine enamel was again chosen as the adhesive base 10. The test was carried out with different irradiation times of the continuously operated diode laser. The data obtained with Er:YAG laser irradiation in pulse mode are also given in Table 3 for reference purposes.

[0123] Furthermore, the values obtained without laser irradiation are also given and, in addition, reference values are also given which are obtained when working according to the standard procedure with blowing and agitation. The following shear strength values were obtained, according to Table 3 below (according to ISO 29022):

TABLE-US-00003 TABLE 3 (Test 3) 5 s 1 W 1 s 5 W with blowing and agitation continuous continuous 5 s 1.3 W without (reference values according Irradiation-parameter diode laser diode laser Er:YAG irradiation to standard) Number of tests 5 5 20 4 5 Average shear 22.60 24.14 20.22 19.11 22.09 strength value in MPa Standard deviation 4.86 2.97 4.84 1.31 2.67 Min 17.6 19.88 11.57 17.83 19.64 Max 28.83 27.21 31.45 20.71 25.56 Fracture appearance adhesive adhesive adhesive adhesive adhesive

[0124] Test 4 was carried out with bovine dentin as the bonding base 10, i.e. as test 2, but using a continuously operated diode laser.

[0125] The shear strength values (according to ISO 29022) were obtained as shown in table 4 below:

TABLE-US-00004 TABLE 4 (Test 4) 5 s 1 W 1 s 5.1 W with fading and agitating continuous continuous 5 s 1.3 W Without (reference values according Irradiation-parameter diode laser diode laser Er:YAG irradiation to standard) Number of attempts 5 4 20 5 5 Mean shear 29.32 28.16 34.19 18.47 33.08 strength in MPa Standard deviation 2.76 6.44 7.59 1.92 3.89 Min 24.99 22.38 20.46 16.18 26.69 Max 31.83 37.04 46.56 21.38 37.31 Fracture appearance cohesive cohesive 19/20 cohesive cohesive cohesive

[0126] Through these two tests using a continuously operated diode laser (tests 3 and 4), it could be shown that the timesaving use of the system of laser and adhesive according to the invention is not limited to the use of pulsed laser radiation and does not come at the expense of shear strength.

[0127] Furthermore, the results of the tests according to the invention with both the continuously operated diode laser and the pulsed laser support the fact that a similarly high or even partly higher shear strength is achieved according to the invention than with the standard procedure by agitation and blowing.

[0128] The effect according to the invention can be explained by the fact that the treatment laser removes the water content and/or highly volatile organic components from the tubules of the dentin or the pores of the enamel. The space created in the tubules or pores now allows the adhesive to penetrate the tubules or diffuse into them more easily. As a result of this penetration of the adhesive, the retention and thus also the shear strength is increased.

[0129] Tooth hard tissue has different reflection properties than an applied adhesive 14. In order to make it easier to orient the hand piece 24 of the laser 16, a sensor 26 is provided on the hand piece 24 adjacent the radiation-emitting surface 18 and detects the reflected radiation 28 and feeds same to the control apparatus 22.

[0130] Preferably, a signal can thus be indicated which signalises the correct orientation of the hand piece 24.

[0131] The hand piece 24 also has a target light source which is designed preferably as a target laser 27 and emits visible light e.g. in the blue, green, yellow or red wavelength range. White or other mixed light is also possible. The target laser 27 is physically connected to the treatment laser 16. It is oriented such that its target beam 31 impinges upon a focus spot 29 of the treatment laser 16. At this location, it generates a visible light point. It is thus oriented axially parallel or substantially axially parallel thereto.

[0132] However, the axis of the target laser 27 can also be inclined slightly with respect to the axis of the treatment laser 16, as illustrated in FIG. 1.

[0133] By means of the target laser 27, the orientation of the treatment laser 16 can be controlled and optionally readjusted. It is switched on preferably before the laser 16 is switched on. The hand piece 24 is oriented to the desired position and then the treatment laser 16 is switched on.

[0134] The target laser can also be integrated in the laser housing 16 and can couple the visible light directly into the optical waveguide 19 of the laser such that no “dedicated” radiation guidance is necessary. This has the advantage that the target light uses the exact same optics and therefore (apart from any chromatic aberration) represents the actually illuminated surface quite effectively—irrespective of the distance to the treatment surface and any trigonometric considerations in different exit openings.

[0135] In this respect, reference is made to the typical design of laser systems with an integrated target laser. However, a laser does not have to be used as the target light source because coherence is not required in this case, only visible illumination. Therefore, in principle every light source which outputs visible light is suitable for generating the target beam.

[0136] FIG. 2 shows a further embodiment of a system in accordance with the invention in an enlarged detail. The radiation 20 output by the laser 16 impinges in the form of the radiation 30 onto the surface of the adhesive 14 which is applied in the cavity 32. The radiation 30 passes through the adhesive layer 14 and also penetrates into the tooth hard tissue 34.

[0137] In order to permit the best possible irradiation, the hand piece 24 is pivoted such that the radiation 30 impinges according to the arrow 36 as perpendicularly as possible onto the surface of the adhesive layer 14. The surface of the adhesive 14 is exposed and is thus freely accessible for the radiation 30 because a dental restoration part 40, see FIG. 3, is not yet applied.

[0138] FIG. 3 shows the state in which a dental restoration part 40 is already introduced into the cavity 32, the dental restoration part 40 has thus been applied to the adhesive layer 14.

[0139] The adhesive 14 is polymerised via a hand-held light curing apparatus 42. The output polymerisation radiation 44 passes for this purpose through the dental restoration part 40 which is permeable to laser radiation 44 in the range of visible light.

[0140] FIG. 4 shows a graph plotted based on the values according to Table 1 and FIG. 5 shows a graph plotted based on the values of Table 2. FIG. 6 shows a diagram plotted based on the values according to Table 3 and FIG. 7 shows a diagram plotted based on the values according to Table 4.

[0141] In a modified embodiment shown in FIG. 8a, the treatment laser 16 is provided with a deflection tip 46. In this embodiment, the deflection tip 46 is fitted onto the distal end 48 of the light guide 19. Alternatively, the deflection tip 46 can also be formed in one piece with the light guide 19, i.e. integrated therein.

[0142] The deflection tip 46 is arranged coaxially with respect to an axis 50 of the light guide 19. It consists of a body 52 made of a material which is transparent for the radiation 20. At its distal end, the deflection tip 46 has an internal cone 54. This has a reflective coating applied thereto or is configured in another suitable manner so that it reflects impinging radiation 20.

[0143] The radiation 20 is thereby deflected from the axis 50 and emerges laterally from the deflection tip 46 as radiation 30. It is intended to strike the adhesive 14 applied to the adhesive base 10 and act there as treatment radiation 30.

[0144] This embodiment is particularly suitable for the treatment of deep cavities which are provided with the adhesive 14. The treatment radiation 30 is scattered and deflected all around such that treatment radiation 30 is applied uniformly even to oblique surfaces of the adhesive (cf. FIG. 2).

[0145] The internal cone 54 is provided with a suitable stopper 56 consisting of a soft material which preferably has a rounded portion 58 formed in this case as an end radius. The rounded portion projects with respect to a sharp circumferential end edge 60 of the body 52 and in this respect covers same. The stopper 56 is adhered in the internal cone 54. The projecting rounded portion 58 prevents damage to the laser 16 and injury to the patient.

[0146] The internal cone 54 can have a cone angle of 90 degrees. Then, the radiation 30 exits the body 52 perpendicularly with respect to the axis 50. In the illustrated embodiment, the cone angle of the internal cone 54 is or is about 65 degrees. Accordingly, the radiation 30 exits the deflection tip 46 slightly obliquely forwards. In the case of this solution, the deflection tip 46 does not have to be introduced so deeply into a deep cavity.

[0147] It is also possible to apply a reflective coating only partially to the internal cone 46 such that some of the radiation, e.g. 50% is reflected and the remainder is allowed to pass through. In the case of this embodiment, the stopper 56 is likewise permeable to the radiation.

[0148] In the case of this solution, the output radiation then impinges not only upon the side walls but also upon the base of the cavity, which is favourable in many cases.

[0149] By virtue of the fact that the deflection tip 46 is detachable, it is also possible to alternate between different emission characteristics.

[0150] In this case, the deflection tip 46 is fitted onto the distal end 48 of the light guide 19. For this purpose, it has an annular groove 62 which is intended to ensure that an annular web 64 of the body 52 engages therein and supports the deflection tip 46 without any clearance on the light guide 19. The body 52 consists of an optionally slightly elastic, radiation-permeable material such that, when the body of the deflection tip 46 is slid onto the light guide 19 the annular web 64 latches elastically into the annular groove.

[0151] Alternatively, it is possible to provide at this location a sleeve fabricated of an elastic synthetic material which engages over both the body 52 and also the end 48 of the light guide 19.

[0152] In the case of these two embodiments, the deflection tip 46 is held captively on the light guide 19 but can be removed with manual force or optionally with the aid of a suitable tool, such as mini-pliers.

[0153] In the case of a cone angle which is below 90 degrees, the body 52 of the deflection tip 46 can also be provided with an external cone 66 at its distal end, as shown in FIG. 8b.

[0154] FIG. 8b shows a section of a detail relating to FIG. 8a. The external cone 66 is adapted in terms of its cone angle to the cone angle of the internal cone 54. The radiation 30 leaves the body 52 through the external cone 66 in a direction perpendicular to the external cone 66 so as to avoid reflection losses.

[0155] The terms “about” and “substantially” are intended to include the degree of error or uncertainty associated with measurement of the particular quantity or shape as one of ordinary skill in the art would understand.