Patent Application
20120208149
1. Technical Field
Present invention is related to a dental composite material and the applications thereof, more particularly related to a dental composite material consisting of a composite resin and an adjuvant and the applications thereof.
2. Description of the Related Art
Root canal treated teeth with insufficient coronal structure generally require radicular posts for crown restoration. Traditionally, cast metal posts and cores covered by porcelain fused to metal crowns are the choice for anterior teeth restoration.
Recently fiber posts which can provide an even stress distribution along the teeth have gradually become accepted to replace cast metal posts, because the esthetic outcomes for anterior teeth are more pleasing and the elastic moduli of these posts are approximate to that of dentin.
Fiber posts commonly consist of a high proportion of reinforcing fibers embedded in epoxy resins with a highly cross-linked structure. The use of adhesive resin cements in luting fiber posts is recommended to improve the retention, reduce micro-leakage, and elevate resistance to tooth fracture. The bonding mechanism of resin cement to root canal dentin is basically micromechanical from hybridization of the demineralized surface and resin tag formation.
However, since the adhesion between resin cement and dentin was considered weaker than the adhesion between resin cement and fiber posts, thus applying resin cement to luting fiber posts with root canal dentin is still not reliable. In addition, the complex environment of the root canal system including the problems of using endodontic sealers, irrigating solutions, and medicaments may further deteriorate the bond strength among resin cement, the fiber post and the root canal dentin. Furthermore, in comparison with coronal dentin, root canal dentin has a limited visibility, irregular structure in the apical region, and a high configuration factor, and these characteristics may make the problem of the bond strength worse during practical dental operations.
Therefore, it is necessary to provide an improved dental composite material and the applications thereof to enhance the reliability of the bond strength among resin cement, the fiber post and the root canal dentin, so as to elevate resistance of the restored tooth.
One aspect of the present invention is to provide a dental composite material, wherein the dental composite material comprises a composite resin and an adjuvant with a concentration of more than 10% by weight of the dental composite material, and the adjuvant comprises more than 20% 1,6-Hexanediol Diacrylate (HDDA) by weight of the adjuvant, more than 20% Tripropylene Glycol Diacrylate (TPGDA) by weight of the adjuvant and a component selected from the group consisting of Ethyl Hexyl Acrylate (EHA), Isobornyl Acrylate (IBOA), 2 Hydroxy 3 Phenoxypropyl Acrylate (DM120) and the arbitrary compositions thereof with a concentration of more than 20% by weight of the adjuvant.
In some embodiments of the present invention, the adjuvant comprises 25% HDDA, 25% TPGDA and 50% IBOA by weight of the adjuvant.
In some embodiments of the present invention, the adjuvant comprises 25% HDDA, 25% TPGDA and 50% DM120 by weight of the adjuvant.
In some embodiments of the present invention, the adjuvant comprises 25% HDDA, 25% TPGDA and 50% EHA by weight of the adjuvant.
In some embodiments of the present invention, the adjuvant comprises 25% HDDA, 25% TPGDA, 25% EHA and 25% IBOA by weight of the adjuvant.
In some embodiments of the present invention, the composite resin comprises 2,2-bis-4-2-hydroxy-3-methacryloxypropoxy-propane and triethylene-glycol-dimethacrylate (TEGDMA).
In some embodiments of the present invention, the dental composite material further comprises photoactives with a concentration of less than 2% by weight of the dental composite material. In some preferred embodiments, the photoactives comprises camphorquinone (CQ), ethyl 4-dimethylaminobenzoate (EDMAB) and Benzoyl peroxide (BPO).
Another aspect of the present invention is to provide a method for restoring tooth after root canal treatment comprising steps as follows: A dental composite material is firstly filled into a root canal, wherein the dental composite material comprises a composite resin and an adjuvant with a concentration of more than 10% by weight of the dental composite material, and the adjuvant comprises more than 20% HDDA by weight of the adjuvant, more than 20% TPGDA by weight of the adjuvant and a component selected from the group consisting of EHA, IBOA, DM120 and the arbitrary compositions thereof with a concentration of more than 20% by weight of the adjuvant. Subsequently, at least one root canal post is disposed in the root canal, and the dental composite material is then cured to fasten the root canal post.
In some embodiments of the present invention, the root canal post is a cast metal post or a fiber post.
In accordance with the aforementioned embodiments, the present invention is to provide a dental composite material having HDDA, TPGDA and a component selected from the group consisting of EHA, IBOA, DM120 and the arbitrary compositions thereof serving as adjuvant of dental cement or dental adhesive for cementation of root canal posts, especially for tooth restoration after root canal treatment, to enhance the reliability of the bond strength among the dental cement, fiber posts and root canal dentin, so as to elevate resistance of the restored tooth.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below. Other objectives, features and advantages of the present invention will be further understood from the further technological features disclosed by the embodiments of the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.
These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:
The object of the present invention is to provide a dental composite material used to enhance the reliability of the bond strength among dental cement, fiber posts and root canal dentin, so as to elevate resistance of the restored tooth. Various inspection or tests including a push-out-bond test and a quantitative-fracture-toughness test are conducted to evaluate the adhesion among the present dental composite material, fiber posts and root canal dentin and to validate whether the dental composite material provided by the present invention can enhance the reliability of the bond strength between fiber posts and root canal dentin and elevate resistance of restored tooth.
In the embodiments of the present invention, the dental composite material at least comprises composite resin and an adjuvant, and preferably further comprises photoactives. In some embodiments of the present invention, the adjuvant has a concentration substantially about 10% by weight of the dental composite material; and the content of the photoreactives is less than 2% by weight of the dental composite material. The material consisting of the composite resin comprises 2,2-bis-4-2-hydroxy-3-methacryloxypropoxy-propane and TEGDMA; and the material consisting of the photoactives comprises CQ, EDMAB and BPO.
The material consisting of the adjuvant comprises HDDA, TPGDA and a component selected from the group consisting of EHA, IBOA, DM120 and the arbitrary compositions thereof, wherein HDDA and TPGDA respectively have more than 20% of the adjuvant by weight, and the component selected from the group consisting of EHA, IBOA, DM120 and the arbitrary combination thereof has a concentration of more than 20% by weight of the adjuvant. To describe the make, use and applications of the present invention, several preferred embodiments with detail contents of the dental composite material are described in detail as following:
A dental composite material consisting of 88.75% composite resin, 10% adjuvant and 1.25% photoactives by weight of the dental composite material is provided. Wherein the composite resin consists of 2,2-bis-4-2-hydroxy-3-methacryloxypropoxy-propane and TEGDMA with a molar ratio substantially about 1:1. The adjuvant consists of 25% HDDA, 25% TPGDA and 50% IBOA by weight of the adjuvant. The photoactives comprises 0.25% CQ, 0.5% EDMAB and 0.5% BPO by weight of the dental composite material.
A dental composite material consisting of 88.75% composite resin, 10% adjuvant and 1.25% photoactives by weight of the dental composite material is provided. Wherein the composite resin consists of 2,2-bis-4-2-hydroxy-3-methacryloxypropoxy-propane and TEGDMA with a molar ratio substantially about 1:1. The adjuvant consists of 25% HDDA, 25% TPGDA and 50% DM120 by weight of the adjuvant. The photoactives comprises 0.25% CQ, 0.5% EDMAB and 0.5% DM120 by weight of the dental composite material.
A dental composite material consisting of 88.75% composite resin, 10% adjuvant and 1.25% photoactives by weight of the dental composite material is provided. Wherein the composite resin consists of 2,2-bis-4-2-hydroxy-3-methacryloxypropoxy-propane and TEGDMA with a molar ratio substantially about 1:1. The adjuvant consists of 25% HDDA, 25% TPGDA and 50% EHA by weight of the adjuvant. The photoactives comprises 0.25% CQ, 0.5% EDMAB and 0.5% DM120 by weight of the dental composite material.
A dental composite material consisting of 88.75% composite resin, 10% adjuvant and 1.25% photoactives by weight of the dental composite material is provided. Wherein the composite resin consists of 2,2-bis-4-2-hydroxy-3-methacryloxypropoxy-propane and TEGDMA with a molar ratio substantially about 1:1. The adjuvant consists of 25% HDDA, 25% TPGDA, 25% EHA and 25% IBOA by weight of the adjuvant. The photoactives comprises 0.25% CQ, 0.5% EDMAB and 0.5% DM120 by weight of the dental composite material.
Subsequently, a push-out-bond test and a quantitative-fracture-toughness test are conducted, and a scanning electron microscopy (SEM), an attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and an X-ray Photoelectron Spectroscopy (XPS) are utilized to investigate and characterize the morphology and the microstructure of the fractured interfaces between the present dental composite material and the root canal dentin, to evaluate the cohesive failure resulted from the quantitative-fracture-toughness test.
(1) Push-Out-Bond test
Groups of dental specimens 1-4 are selected to associated with the 4 kinds of dental composite materials set forth in the embodiments □-□, wherein each of the dental specimens is prepared to form a 1.8 mm-diameter hole at least 1 mm from the edge of specimen and the hole is centrally prepared in each root segment preceding the push-out-bond test.
The 1.8-mm diameter holes in the dental specimens are etched for 15 seconds with an etchant comprising 37.5% phosphoric acid, rinsed thoroughly, and air dried. In some embodiments of the present invention, the etchant preferably is Kerr Gel Etchant provided by Kerr Corporation (CA, USA). In addition, a 1.8-mm diameter hole is prepared and etched in each dental specimen of a 5th group serving as a control.
An etch-and-rinse 2-step adhesive system, such as Optibond Solo Plus provided by Kerr Corporation (CA, USA), is then applied for 15 seconds and the excessive adhesive is removed with absorbent paper points. Subsequently, the top and bottom surfaces of the dental specimens are light-cured for 10 seconds with a light curing machine (Dentsply, provided by SmartLite Corporation, PA, USA) at an intensity of 800 mW/cm2. Then, the canals of the groups 1-4 dental specimens are respectively filled with the 4 kinds of dental composite materials set forth in the embodiments □-□, and are light-cured again for an additional 40 seconds at top and bottom surfaces.
The 5th group control specimens are otherwise filled with PANAVIA F 2.0 (provided by Kuraray Corporation) and treated according to the manufacturer's instructions. For the purpose of clearly describing the following embodiment, the groups 1-4 dental specimens that are respectively filled with the 4 kinds of dental composite materials set forth in the embodiments □-□ and the Panavia F 2.0™ are referred as IBOA ’ DM120’ EHA ’ IBOA+EHA and PANAVIA F 2.0 thereinafter.
Each root segment is serially sectioned into 1 mm-thick root slices using a high-speed diamond wafering blade (e.g. Isomet 2000 Precision High-Speed Saw; Buehler Ltd), and the thickness is verified using an electronic vernier (e.g. CD-I0CX™; Mitutoyo Co Ltd, Tokyo, Japan). Fifty root slices of the groups 1-4 dental specimens are randomly divided into 5 groups with 10 root slices in each group. Next, a cylindrical carbon steel rod 1.7 mm in diameter is used as a plunger, whereby a 1.75 mm-diameter hole and a 1.85 mm-diameter hole are centrally positioned at the upper and lower surfaces of each slices, respectively. The push-out bond strength is calculated using the following equation:
Push-out bond strength(MPa)=Force/(π×Diameter×Thickness)
The testing results are analyzed using two-tailed analysis of variance (ANOVA), with a significance level of 0.05 and follow-up comparison between the groups is made using Fisher's multiple comparison tests.
The push-out bond test revealed that IBOA+EHA specimens exhibit the highest push-out bond strength followed by IBOA specimens, and both of them has higher push-out bond strength than that of the Panavia F 2.0. Even EHA and DM120 specimens with lower bond strengths are not significantly different from that of PANAVIA F 2.0. It demonstrates that the adhesive performance of the dental composite materials set forth in the embodiments □-□ is similar to that of the control PANAVIA F 2.0.
(2) SEM Observation
After the push-out bond test the morphology and microstructure of the fractured dental specimens are observed under SEM observation. Preceding the observation, the dental specimens are immersed in 2.5% cold glutaraldehyde in 0.1 mol/L cacodylate buffer at pH 7.4 for 8 hours. All dental specimens are then serially dehydrated in graded ethanol solutions (50%, 60%, 70%, 80%, 90%, 95%, and 100% ethanol) at 45 minutes intervals, mounted on aluminum stubs, and sputter-coated with carbon. The treated dental specimens are then observed under a Philips 515 (Mohawk Corporation, NJ, US) SEM, wherein the electron beams maintained at 2×10−10 amp are used, X-ray intensities in counts per second are recorded and the accelerating voltage is 15 kV.
(3) Quantitative-Fracture-Toughness Test
Fifty dental specimens from root dentin sized of 1.5 mm×3 mm×25 mm (thickness×width×length) are prepared and allotted in 5 groups. The 4 kinds of dental composite materials set forth in the embodiments I-IV and the control PANAVIA F 2.0 (5th Group) with a size of 1.5 mm×3 mm×25 mm (thickness×width×length) are adhered onto the dental specimens by the etch-and-rinse 2-step adhesive system identical to that used in the push-out bond test. An asymmetric double cantilever beam (ADCB) method is then applied to measure the interfacial fracture toughness (thereinafter referred as “Gc”) between the dental composite materials and the dental specimens.
Where C1=1+0.64h1/a and C2=1+0.64h2/a. “E1” and “E2” are Young's moduli; “a” is the length of the crack; and “h1” and “h2” are the thickness of the root dentin 303 and the dental composite material 302, respectively. The testing results are analyzed using two-tailed analysis of variance (ANOVA), with a significance level of 0.05 and follow-up comparison between the groups is made using Fisher's multiple comparison tests.
(4) SEM-EDX Analysis
After the fracture toughness test, the specimens are separated into two groups (root dentin half and dental composite material half). The root dentin half is examined with SEM-energy dispersive X-ray spectroscopy (SEM-EDX) to determine the atomic ratio of the dentin half. The following table shows the SEM-EDX results for the atomic ratio of the root dentin half.
The root dentin without any treatment having atomic ratios of C (23.6%) and Ca (10.6%) is different from that of the control specimens PANAVIA F 2.0 with the atomic ratios of C and Ca of 46.8% and 1.4%, and also different from that of another control group, of which the root dentin specimens are adhered with the commercial cement, Optibond Solo Plus (thereinafter referred as “Optibond”), with the atomic ratios of C and Ca are 42.5% and 0.5%. Because there still remains a certain amount of PANAVIA F 2.0 or the Optibond residue on the surface of the root dentin after the fracture toughness test is conducted, it reveals that covalent bonds may be formed between the root dentin and the control cements.
In comparison with the present 4 kinds of dental composite materials set forth in the embodiments □-□, the IBOA+EHA shows a C ratio of 56.1% apparently higher than that of root dentin without any treatment. The other specimens IBOA, EHA, DMI20 and Panavia F 2.0 show similar C ratio to Optibond. It reveals that after the fracture toughness test, there still remains a certain amount of the dental composite materials on the surface of the root dentin; and the strength of the covalent bonds formed between the root dentin and the dental composite materials are substantially the same to or even greater than that of the current commercial cements (PANAVIA F 2.0 or the Optibond).
(5) ATR-FTIR Analysis
After the fracture toughness test, the fractured surfaces of the root dentin/the dental composite material samples are studied using an ATR-FTIR (FTIR-4200, provided by Jasco International Co., Ltd., Tokyo, Japan) to determine the molecular structure of the fractured surfaces of the root dentin/the dental composite material, wherein the FTIR spectra are recorded by pressing the samples against a ZnSe ATR crystal with slow scan and a normal slit width and the wave number ranges of 4000-400 cm−1 to evaluate the functional groups. To the purpose of making a reference, pure EHA, IBOA, DM120 and PANAVIA F 2.0 cements are also studied by the ATR-FTIR.
The most intense bands associated with the PO43 vibrations, the anti-symmetric stretching mode ranges at 1100-1000 cm−1, may characterize the presence of dentin; the strong bands due to the interaction of ester C—O stretching vibration with the C—C vibration occurred in the range of 1300-1100 cm−1 which could be observed in the spectra of (b), (c), (f), (g), (j) and (k); The ester C═O stretching vibrations at 1740-1705 cm−1 could be identified in the spectra of (b),(c),(h),(i); the spectra of (a)-(g) exhibit signals of non-conjugated alkenes with a weak C═C stretching absorption band in the range 1680-1620 cm−1.
The ATR-FTIR analyses reveals that the FTIR spectra of the dentin half specimens for the 4 kinds of dental composite materials set forth in the embodiments □-□ and the control specimens PANAVIA F 2.0 are similar to those of pure resin cement. In other words, there remains a certain amount of bonds of C—O, C—C, C═O and C═C formed on the surface of the dentin half specimens after the fracture toughness test is conducted. Accordingly, it can be figured out that the present dental composite materials have the adhesion substantially the same to or even greater than that of the current commercial cements.
(6) XPS Analysis
The fractured surfaces of the root dentin/the dental composite materials samples after fracture toughness test are further studied using XPS (Thermo Scientific, UK). XPS spectra are acquired using K-alpha XPS with monochromatic Aluminum (Al) Kα X-rays (beam energy=1486.6 eV). Survey spectra are collected over the range of 0-1100 eV. The X-ray source is operated at 210 W and the system operating pressure is 5×10−8 Torr. All spectra are referenced to the C is peak of the aliphatic carbon atoms, which is assigned a value of 284.6 eV. To the purpose of making a reference, pure EHA, IBOA, DM120 and PANAVIA F 2.0 cements are also studied by the XPS.
It is found that the XPS spectra of the dentin half specimens are similar to those of the pure resin cements. In addition, the XPS spectra for all samples are significantly different from that of the pure dentin sample. The above results indicate that a cohesive failure of the resin cement occurs on the resin cement near the dentin/resin cement interface. Furthermore, it can be conjectured that each of the dental composite materials set forth in the embodiments □-□ has an adhesion substantially the same to that of the current commercial cements.
In accordance with the aforementioned embodiments, the present invention is to provide a dental composite material having HDDA, TPGDA and a component selected from the group consisting of EHA, IBOA DM120 and the arbitrary compositions thereof serving as a dental cement or a dental adhesive for restoring tooth after root canal treatment to enhance the reliability of the bond strength among the dental cement, fiber posts and root canal dentin, so as to elevate resistance of the restored tooth. Those advantages and objects of the present invention can be verified by the aforementioned push-out-bond test, the quantitative-fracture-toughness test, the SEM Observation, the SEM-EDX analysis, the ATR-FTIR analysis, and the XPS analysis.
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 100104589 | Feb 2011 | TW | national |
