SELECTIVELY SORBENT ARTICLE AND METHOD FOR USE IN DENTAL APPLICATIONS

Abstract: The present specification describes a cleanup article which selectively sorbs hydrophobic dental resins. The article is particularly useful in the removal of excess resin-containing materials from the mouth during dental procedures. The article preferable is of sufficient integral strength to prevent break-up of the article during use.

Description: SELECTIVELY SORBENT ARTICLE AND METHOD FOR USE IN DENTAL APPLICATIONS FTFJ JT) OF INVENTION The present invention relates to an article which aids in the removal of excess resin-containing materials and a method for using such an article. The present invention provides an article and method which are particularly useful in the removal of excess resin containing materials from the mouth during dental procedures. BACKGROUND Materials with an absorbent inner layer and a hydrophobic barrier layer are well known in the art. See, for example, U.S. Pat. No. 4,784,892. Such a material can be used for a variety of purposes, such as for disposable protective clothing, filtration, or disposable wipes for domestic or industrial purposes. The bulk properties of these materials are geared toward absorbency, with the barrier layer the only hydrophobic portion. Materials are well known in the art which preferentially retain a substance to the exclusion of water. U.S. Pat. No. 3,764,527 discloses an oleophilic fibrous web in which the fibers are preferentially wetted by oil in an oil-water mixture, retaining the oil in the internal voids ofthe web while rejecting water. A non-sterile, general use material, NuGauzeO sponge from Johnson & Johnson, absorbs both water and resins. This material is applied by hand or by gripping a piece ofthe material with a cotton pliers. SUMMARY OF THE INVENTION A dental article is provided for use in selectively sorbing substantially hydrophobic dental resins from an environment containing aqueous fluids. The article comprises a material having a Water Repellency Value greater than 1. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further explained with reference to the drawing, wherein: Figure 1 is a plan view of an embodiment ofthe article ofthe invention. Figure 2 represents a cross-sectional view along line 2-2 of Figure 1. Figures 3 A and 3B are prior art representing a partial cross-section respectively ofa seated crown with excess cured resin-containing cement left at the margin, a seated crown with excess cured resin-containing cement chipped away, and a seated crown with excess resin-containing cement wiped away prior to cure by an embodiment ofthe present invention. Figure 4 represents a plan view of an embodiment ofthe invention wherein the pad is attached to a carrier to facilitate use ofthe cleanup pad. Figure 5 is a partial cross-section ofthe invention showing the excess resin- containing cement wiped away. These figures, which are idealized, are not to scale and are intended to be merely illustrative and non-limiting. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS The need exists for an easy, efficient means of removing excess resin- containing materials from a moist environment completely and without smearing. It is desirable to have a cleanup pad capable of preferentially absorbing resin-containing materials without leaving resin on the surface which has been wiped. It is also desirable that the cleanup pad stay in one piece even when saturated. The present invention provides such a cleanup pad. The present invention provides an article and method for the removal of excess resin-containing substances by wiping with a hydrophobic sorbent material. The cleanup pad ofthe invention selectively sorbs hydrophobic resins resulting in a smooth and even wiped surface that is substantially free of residual resin. These wiping pads are useful for removing excess resins during dental procedures either in the mouth or on models in the dental laboratory. The present invention is particularly useful in the removal of excess resin containing materials from the moist environment ofthe mouth during dental procedures, since the pad will preferentially sorb resins. In a preferred embodiment, the article ofthe invention is in the form ofa pad, in a size and shape suitable to be placed into the mouth without excessive bulkiness, but large enough to sorb and thus remove a substantial amount of resin-containing material. The bulk sorbent material is sufficiently hydrophobic such that the material will selectively sorb hydrophobic dental resins. In dental procedures, such as cementing a crown in place, it is important that the clinician have an efficient and easy means of removing the excess cement. During crown seating, uncured cement must be cleaned up because exposure ofthe oral soft tissues to the uncured resin in the cement can result in sensitization problems for some patients. Typically in seating a crown, excess cement is expressed at the margin ofthe crown and is allowed to partially cure. The partially hardened cement is then removed in pieces with a dental instrument. This technique may leave an open or rough margin which may facilitate caries or periodontal disease. Alternatively, the resin-containing cement may be removed immediately after the crown is seated. Such immediate removal is typically performed with a cotton swab, which results in incomplete removal ofthe cement. The cotton absorbs oral cavity fluids, and consequently does not readily absorb the resinous material but instead smears it. An advantage ofthe present invention over materials currently available for wiping away excess resin-containing materials such as dental cement is that the material ofthe present invention results in a smooth, even surface without excess cement or voids which may facilitate recurrent caries. While the size, shape, and thickness ofthe pad is not critical, the clinician needs to be able to handle the pad with the fingers or with an instrument such as a cotton pliers. The pad should be of appropriate size and shape to use easily in the mouth. When using a cotton pliers, the pad is preferably in the form of a disk of about 6 millimeters to 12 millimeters diameter. Preferably, the pad has a thickness of less than about 2 millimeters. When the pad is to be handled by the fingers, it preferably has a square, rectangular or triangular shape having a side measurement of less than about 5 centimeters, or a circular elliptical or oval shape having a diameter or length of less than about 5 centimeters. Other shapes, such as hexagonal, star- shaped, letter shapes, random shapes and the like are also contemplated. Preferably, the article ofthe present invention has a sheet-like configuration having an overall size of less than about 250 cm 2 . More preferably, the article has an overall size of less than about 25 cm 2 . Figure 1 depicts an embodiment ofthe invention 10 where 3 is an individual fiber. The pad is typically conveyed to the mouth with a cotton pliers. Figure 2 is a cross-sectional view of Figure 1 taken along line 2-2 of Fig. 1. Figure 3 A depicts a cemented crown and tooth combination 20. Crown 31 is cemented to a prepared tooth 36. Prior to seating, the crown 31 is lined with a cement 32. When the crown is seated onto the prepared tooth, the excess cement squeezes out at the margins. Overhang 33 results from incomplete removal of excess cement. If unremoved, the overhang may facilitate periodontal disease. Typically, such overhangs are removed with a dental instrument such as an explorer, which may result in an open margin. Figure 3B depicts a crown and tooth combination 20', where 36 is the prepared tooth, 31 is the crown, 32 is the cement, and 34 is an open margin resulting from the partially hardened cement being removed. Such an open margin may lead to caries or periodontal disease. Figure 5 depicts a cemented crown and tooth combination 20", where 36 is the prepared tooth, 31 is the crown, 32 is the cement, and 35 is a smooth wiped surface. There is typically a gap of about 50 to 150 micrometers between the crown and the tooth that should be filled with cement. Figure 4 depicts an embodiment ofthe invention 40, having carrier 42 such as a wood or plastic applicator to which the pad 10 or pad material is attached. The carrier 42 serves as a means to convey the pad 10 to the place where it will be used, such as the tooth or the model. The fibers of hydrophobic resinophilic material comprising the pad are of appropriate fiber diameter and density to absorb or adsorb a substantial amount of resin. Another important aspect ofthe fibers is surface area which is inversely related to the square ofthe fiber diameter. Fiber diameters and pad densities may be varied within a considerably wide range. It will be apparent to those skilled in the art that the lower the density ofthe pad, the more readily the pad will sorb and retain large amounts of resin. The size of the interstices influences the entrapment and retention of resin in the interstitial spaces, rather than sorption ofthe resin as a film on the surface ofthe fibers. Any suitable fibers which exhibit the desired characteristics may be used to form the web from which the pads are made. A particularly preferred material from which to form the pad is a polypropylene blown micro-fiber web as described in U.S. Pat. No. 3,764,527 (Sohl). Other suitable materials include polyethylene or a blend of polypropylene and polyethylene. The material selected must preferentially sorb resin. The material selected should be sufficiently hydrophobic so that the pad does not sorb a quantity of water such that it will interfere with the sorption ofthe resin and smear the resin. The preferred pad materials may be defined broadly as those materials (usually polymeric) which when contacted with a resin-water mixture, allow the resin to displace water from a smooth surface thereof and to form a contact angle with said surface of less than 90 degrees. Generally, the effectiveness ofthe fiberforming material has an inverse relationship to the size ofthe above described contact angle. Thus, polypropylene and polyethylene surfaces allow resin to assume a contact angle of substantially zero degrees and therefore fibers of these polymers provide the preferred materials for practicing the invention. An important physical property of material comprising the wipe is hydrophobicity, measured as a bulk property. The material comprising the cleanup pad ofthe invention is preferentially wetted by resin and selectively sorbs dental resin. Currently used materials such as cotton swabs or gauze are hydrophilic. These materials sorb water, becoming saturated so that they cannot effectively sorb resin. Consequently, these materials merely smear the resin instead of sorbing it. Thus, the cunently used cleanup materials leave the surface upon which they have been used gummy and sticky. A water repellency test was used to compare the hydrophobicity ofthe material comprising the cleanup pad ofthe invention to other currently used materials. Water repellency is defined as the ability ofa substrate to resist wetting by water or watery liquids. The test method used was designed to provide a simple measurement of aqueous stain resistance. The results obtained from this test depend primarily on the resistance to wetting (water repellency) ofthe fibers in the substrate, and not upon the construction ofthe substrate. To determine the Water Repellency Value, each substrate's resistance to wetting by a selected series of water and isopropyl alcohol mixtures is measured. The series of mixtures ranges from 100% water to 100% isopropyl alcohol, with the test liquid number increasing as the percentage of water decreases and the percentage of isopropyl alcohol increases. The Water Repellency Value ofa substrate is the highest numbered test liquid which will not wet the substrate within a period of thirty seconds, evaluated at 20°C. Table 1 gives the number and composition of each mixture in the selected series. TABLE 1 STANDARD TEST LIQUIDS Test Liquid Percent Composition of Test Liquid W 100 Water 1 90/10 Water/Isopropyl Alcohol 2 80/20 Water/Isopropyl Alcohol 3 70/30 Water/Isopropyl Alcohol 4 60/40 Water/Isopropyl Alcohol 5 50/50 Water/Isopropyl Alcohol 6 40/60 Water/Isopropyl Alcohol 7 30/70 WaterIsopropyl Alcohol 8 20/80 Water/Isopropyl Alcohol 9 10/90 Water/Isopropyl Alcohol 10 100 Isopropyl Alcohol Substrates were rated as a pass/fail ofthe appropriate test liquid. Resistance to wetting is indicated by a clear drop with a high contact angle. Wetting is normally evidenced by a darkening ofthe substrate at the liquid-substrate interface. TABLE 2 | Material Liquid 1 Liquid 2 Liquid 3 Liquid 4 | Cellulose Y | Cotton Y 1 Rayon/polyester blend Y | polypropylene N N N Y Table 2 shows the results ofthe water repellency test for various materials. The Ys and Ns in Table 2 denote if the material was wetted by the liquid (Y) or was not wetted by the liquid (N). Preferably, the material used to form the cleanup pad ofthe invention has a Water Repellency Value of no less than 3. Other liquids of varying surface tensions were also used to evaluate the sorbency properties of material comprising the pad ofthe invention. Surface tension is typically measured at 20°C, and reported in dynes per centimeter (dynes/cm). The material comprising the cleanup pad ofthe invention absorbed quinoline and, but did not absorb water, glycerol, formamide or ethylene glycol. TABLE 3 Liquid Surface Tension Sorbence by clean-up pad Water 73.05 N Glycerol 63.4 N Formamide 58.2 N ethylene glycol 47.7 N quinoline 45 Y benzyl alcohol 39 Y pyridine 38 Y The results of Table 3 indicate that material ofthe cleanup pad will preferably absorb liquids with a surface tension less than that of ethylene glycol, 47.7 dynes/cm. Thus, in a preferred embodiment, the material used to form the cleanup pad ofthe invention absorbs only those substances with a surface tension of less than 47.7 dynes/cm, and more preferably less than 40 dynes/cm. Random orientation ofthe fibers in the web may be preferable to a patterned orientation. Although the patterned orientation has a smaller surface area and thus sorbs less in bulk, the key parameter is the wetting ofthe fibers ofthe pad by the resin. The resin wets the fibers at the cement-fiber interface. Resin containing filler particles becomes entrapped in the interstitial spaces. Thus, the construction is not as critical as the affinity ofthe fibers for the resin. That is, the material needs to have some minimum bulk absorbency, but the loft ofthe pad is provided to give the pad sufficient thickness so that it can be gripped by a cotton pliers. Any process that results in a material with suitable physical properties may be used, although a prefened process for making the material from which the pads are formed is a web made by a blown microfiber process. The pad should possess sufficient integral strength to resist break-up even when saturated with fluids. Optionally, reinforcing fibers may also be incorporated to improve the strength characteristics ofthe resulting article. In a preferred embodiment, the pads are die cut from a web into 9.5 millimeter disks. The disks preferably have a thickness of between 1 and 2 millimeters. Other sizes and shapes of material will also suffice. Any cutting means that cuts the material cleanly without leaving loose fibers may be utilized. Approximately 2-3 pads per crown will normally be sufficient to remove excess resin- containing cement. The sorbent pads ofthe invention may be used in a variety of cleanup procedures, such as those for the placement of crowns, bridges, inlays, onlays, or veneers. The cleanup pad ofthe invention will generally provide efficient cleanup of any dental resin-based materials. The dental resin-containing materials may be unfilled or filled. If filled, any suitable dental filler or combination of fillers well known to those skilled in the art may be incorporated into the resin system. Examples of unfilled dental resin-containing materials include adhesives and sealants while examples of filled dental resin-containing materials include cements and composites. Dental resins are typically derivatives of acrylate or methacrylate compounds. Examples of dental resins include, but are not limited to, acrylate, methacrylate, urethane and epoxy resins and mixtures and derivatives thereof. Commonly utilized dental resins include 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane ("Bis-GMA"), triethyleneglycol dimethacrylate ("TEGDMA"), ethoxylated bisphenol A dimethacrylate, 2-hydroxyethyl methacrylate, polyethyleneglycol dimethacrylate, urethane dimethacrylate, and mixtures thereof. The dental resin-containing materials may be unfilled or filled. If filled, any suitable dental filler or combination of fillers well known to those skilled in the art may be incorporated into the resin system. Examples of unfilled dental resin- containing materials include adhesives and sealants while examples of filled dental resin-containing materials include cements and composites. The cleanup pad ofthe invention may also be used on models in the dental laboratory to remove excess resin-containing material. It is not as critical in this use that the material be hydrophobic as when the pad is used in the moist environment of the oral cavity. The material used to make the pads ofthe invention may also be drawn into a string, to be used as a floss. Such a floss is particularly useful for removing resin from interproximal spaces. EXAMPLES The invention will be further explained by the following illustrative examples which are intended to be non-limiting. EXAMPLE 1 Manufacture of he Cleanup Pad The cleanup pads can be made from a jumbo roll (91.4 cm" dia. x 48.3 cm" width) of polypropylene blown micro-fiber. This roll is fed into a slitter and reduced to 51 cm" dia. x 5 cm" width. The reduced roll is fed into a rotary die stamper setup with dies in the range of 0.64 cm"to 1.3 cm' in diameter. This process yields a finished pad free of strands on the perimeter due to cold welding ofthe filaments during the die stamping process. EXAMPLE 2 Resin Cement Cleanup of a Luted Crown Immediately after seating a crown, (PFM, all porcelain, metal, composite), initiate cleanup. Excess resin cement ( a filled Bis-GMA TEGDMA cement) is removed interproximally with dental floss (available from Johnson & Johnson Consumer Products Inc., Skillman, NJ). Facial and lingual surfaces are cleaned with the cleanup pad of Example l(disk of approximately 9.5 millimeters diameter and approximately 2.5 millimeters thickness) The pad is gripped with a cotton pliers (Miltex Instrument Co., Lake Success, NY) and wiped across the facial surface ofthe crown , at the margin ofthe crown and the tooth, and any other place where excess resin is present. This process is repeated on the lingual crown surface to complete the cleanup procedure. EXAMPLE 3 Resin Cement Cleanup : cleanup pads of Example 1 Compared to Competitive Materials The efficacy ofthe cleanup pads of Example 1 was demonstrated by the following test. A small amount (1/2 gram) of resin luting cement (3M ScotchbondO Resin Cement) was extruded as a film about 1/2 millimeter thick onto a glass microscope slide (from VWR Scientific Inc., San Francisco, CA 94120, catalogue #4800-025). The slide with the extruded resin film was immersed in a petri dish of water. While immersed in the water, the resin was wiped from the slide with a disk ofthe cleanup material. The slide was then examined for evidence of residual resin. The cleanup material ofthe invention resulted in a clean surface. The same procedure was performed using NuGauze™ sponge from Johnson & Johnson, which resulted in noticeable amounts of resin left on the slide. Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention.

Claims: Claims: 1. A dental article for use in selectively sorbing substantially hydrophobic dental resins from an environment containing aqueous fluids, said article comprising a material having a Water Repellency Value greater than 1. 2. The article of claim 1, wherein said environment is the oral cavity. 3. The article of claim 1, wherein said material is a nonwoven web. 4. The article of claim 1, wherein said material is a woven web. 5. The article of claim 1, wherein said material is attached to an applicator. 6. The article of claim 1, wherein said material is used as a dental floss. 7. The article of claim 1, wherein said material absorbs liquids having a surface tension less than 47.7 dynes/cm. 8. The article of claim 1, wherein said material absorbs liquids having a surface tension less than 40 dynes/cm. 9. The article of claim 1, wherein said material is selected from the group consisting of polypropylene and polyethylene, and mixtures thereof. 10. The article of claim 1, wherein said article has a sheet-like configuration having an overall size of less than about 250 cm 2 . 11. The article of claim 10, wherein said article has a sheet-like configuration having an overall size of less than about 25 cm 2 . 12. A method for selectively sorbing substantially hydrophobic dental resins comprising a) applying a substantially hydrophobic dental resin to a dental surface in need of treatment; and b) removing excess hydrophobic dental resin from said dental surface by wiping excess said resin with the article of claim 1. 13. The method of claim 10, wherein said dental surface is in the oral cavity. 14. A method for cementing a crown in place, comprising the steps of a) placing a substantially hydrophobic cement into a crown; b) seating said crown on a prepared tooth with excess cement exuding from the margins of said crown; and c) removing said excess cement from surfaces of said crown with the article of claim 1.

Inventors: CUMMINGS KEVIN M, SWANSON JEROME E, CUMMINGS, KEVIN, M., SWANSON, JEROME, E.
Applicants: MINNESOTA MINING & MFG, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 1996
Main classification: A61F13
IPC codes: A61C13, A61C19, A61F13