AU595803B2 - Dental pit and fissure sealant - Google Patents

Description

COMPLETJ

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Application Number: Lodged: ,R-PROVISIONALAUnIMALIA SPrCIFICATION NO. PH 00956 PATENTS ACT 1952 7- OMPLETE SPECIFICATION

(ORIGINAL)

59503 FOR OFFICE USE: 85 4 3 6 ?6 Class Int. Class Complete Specification Lod~ged:; 'Ar-NT *rIKA fA V ng Accepted. i MT PATENT OFFICE Published: Priority; r{l~e'a~ed Art: u *V 44 FOFTY DOLLARIS CNirf ofApicnC) Adis of Applicant(s) t C t Actual Inventor(s): t i Address for Service: JEFFERY JAMES CHEETHAM Brunsdon Stxeet 81AYSWATER VICTORIA

AUSTRALIA

NEOPHYTOS TELEVANTOS 3153 >1 Thi~qdoctiment containlsthel a nvznlents made uLnder ,Scctjon 49 and is coi-:ct for KelvinLord Co., 4 Douaro Place, WEST PERTH, Western Australia 6005.

Complete Specification for the invention entitled: "DENTAL PIT AND FISSURE SEALANT" The following statement is a full description of this invention, including the best method of performiing it known to me/ us The invention relates to a composition for sealing and protecting pits and fissures in tooth surfaces from dental caries.

BACKGROUND OF THE INVENTION In the last decade much attention has been focused on the use of pit anC fissure coatings as a means of protecting these susceptible areas. A considerable number of worldwide clinical trials have demonstrated the efficiency and safety of sealants. The same clinical .o 10 trials have shown impressive retention rates and caries reduction.

Si I The conservative nature of sealants and ease of use have I stimulated their use over traditional restorative methods.

Amalgams are gradually losing ground because they: 1. require destruction of more tooth structure, initially and at placement; *a 2, are aesthetically unacceptable; S. 3. are being questioned as a potential health hazard; and 4. cost more.

Traditional pit and fissure sealants are composed of an unfilled photopolymerisable low, viscosity acrylic resin system. The disadvantage of such sealants is that their h.ransltacent nature makes it impossible .or the dentist to evaluate the integrity of the sealant during placement -2- /IY I and also during periodical re-checks. More recent formulations have used titanium dioxide and strontium glass as opaquing fillers in an effort to make the sealant more detectable. However, it has been found that these fillers settle on standing and require thorough stirring prior to use. Other more satisfactory formulations, for example, as described in U.S. 4,150,012, combine finely divided hydrophobic opaquing fillers, such as titanium dioxide, in an amount of about 0.1 to 5%Wt and hydrophobic suspending agents present in an amount of 1 to 10%Wt. Others have used dyes in an attempt to a 4" make the sealant more visible, however, thege dyes, which may leach out with the passage of time, did not produce the desired effect.

SUMMARY OF THE INVENTION t t In accordance with this invention, it has been found that a tooth coloured photupolymerised dental pit and fissure sealant composition with improved opacity may be produced "from a particular class of hydrophobic precipitated silica without the need to use opaquing agents which may settle on standing. This class of silica contains calcium silicate which functions as an opaquing agent.

In accordance with one aspect of the present invention there is provided an rpaque dental pit and fissure sealant composition comprising a polymerisable acrylic resin, and hydrophobic precipited particulate silica filler 3

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I1 Ic i 1 7 containing calcium silicate, which functions as both suspending and opaquing agent.

DETAILED DESCRIPTION OF THE INVENTION The present invention has several features that corbine to provide a dental pit and fissure sealant composition of good characteristics.

One important feature of the invention is the dual function of the hydrophobic precipitated silica, that is, its ability to function as both suspending and opaquing 10 agent. This desirable feature is due to the calcium silicate which is present in this class of precipitated silica and functions as the opaquing agent, thus making additional opaquing agents unnecessary.

4* The use of silica containing calcium silicate is economic- 15 ally more feasible than pyrogenic silica and can be used 0' 4 conveniently by those skilled in the art to formulate 4 4V S4 very opaque sealants which are easily detectable during placement and also during periodical re-checks.

The microfine nature of precipitated silicas containing 20 calcium silicate makes them excellent suspending agents.

Formulations of pit and fissure sealants containing these silicas as fillers may be tooth coloured, or mad, even more visible by suspending therein colourants particularly inorganic colourants such as iron oxides.

The presence of these fillers in the sealant gives good -4- L, ,-rr x vear resistance, a low coefficient of thermal expansion and low polymerisation shrinkage of the coatings and resultant potential for microleakage. It has been found that wear resistance, water sorption and strength of balant can be improved by coating the surfaces of the particles of the :,ilica containing calcium silicate with an organosilane.

In order to formulate sealants with good clinical opacitites the polymerisable resin is preferably filled 10 with the silica containing cal-ium silicate in an amount Sin the range from about 5% to 30% preferably 15% to 25% based on the weight of the filled sealant composition.

Silicas which are preferred for use in this invention eE contain 5%Wt to 30%Wt, more preferably 5% to 15% calcium silicate based on the weight of the precipitated silica.

The polymerisable acrylic resin is preferably a methacrylic resin. Further, the sealant compositions of the present invention may contain a mixture of polymerisable acrylic, preferably methacrylic resins. A preferred ;resin is ethoxylated bisphenol A dimethacrylate or a mixture of this and other dinethacrylate monomers.

The silica containing calcium silicate preferably has a particle size of less than The present invention will now be illustrated by the following Examples.

EXAMPLE 1 A single component visible light cured dental pit and fissure sealant composition is prepared by mixing together and then homogenising on a, triple roll rtill, the following ingredients: Ingredient Part by Weight A. Bis-GM4A (Bisphenol-A diglycidyl dimethacrylate) 250 .0 10 EBADMA (Ethoxylated Bisphenol-A diJmethacrylate) 350. 0 Plex 6661-0 (7,7,9-Trimethyl-4, 13 dioxo-3,14 dioza-5,12 Tr~t V Cdiazahexadecane-1,46 diol- C Cdimethacrylate) 100 .0 C V t TEGDMA (Triethylene Glycol dimethacrylate) 300.0 is CQ (Camphorguinone) T-inuvin P (2-(2-hvdroxy-5methyl-phenyl) -2H-Benzotriazole) 10.0 BHT (Butylated Hydroxy toluene) TMA (N,N,3,5 Tetramethyl aniline) B. Extrusil (Hydrophobic silica containing calcium~ silicate of an average primary particle size of 0,4V25nm ancO BET surface of 35m 2 /g 280.0 Wacker HDK H15 (Hydrophobic Pyrogenic silica) 20.0 -6- The silica containing calcium silicate was treated Swith a solution of reactive silane primer in water, to have a silane content of 8% by weight of the coated silica.

It will be appreciated that the pyrogenic silica is added as a viscosity modifier. It is preferably added in an amount in the range from about 0.1%Wt to more preferably 0.1% to 2% based on the weight of the filled sealant.

10 To demonstrate the stability of the above sealant grams were placed in a test tube and centrifuged for O*t* two hours. After centrifuging, the fillers were uniformly distributed and there was no evidence of separation or settling.

EXAMPLE 2 4,s Another dental pit and fissure sealant was made up using resin A. of example 1. and iron oxide pigments.

.4 Ingredient Parts by Weight Resin A 1016.0 Extrusil 280.0 Wacker HDK H15 20.0 Iron Oxide Pigment 0.2 This tooth coloured formulation was also stable after centrifuging for two hours. There was no evidence of pigment or filler settling.

i :I i EXAMPLE 3.

To demonstrate the efficiency of silicas containing calcium silicate as suspending agents the following formulation was mixed and homogenised.

Ingredient Parts.by Weight Resin A 1016.0 Extrusil 100.0 Iron Oxide Pigment 0.2 0 019m 0 4t

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r I If 4* I? Centrifuging the above formulation for two hours showed no evidence of settling or separation.

Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.

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Claims (11)

1. An opaque dental pit and fissure sealant composition comprising a polymerisable acrylic resin, and hydrophobic precipitated particulate silica filler containing calcium silicate, whic functions as both suspending agent and opaquing agent.

2. A dental pit and fissure sealant according to Claim 1, which additionally comprises a colourant.

3. A dental pit and fissure sealant according to S 10 Claim 2, in which the zolourant is an iron oxide. a I

4. A dental pit and fissure sealant according to any S t one of the preceding Claims, in which the silica particles are coated with an organosilane. A dental pit and fissure sealant according to any one of the preceding claims, which contains from 5 to by weight of the silica filler.

6. A dental pit and fissure se7eant according to Claim 5, which contains from 15 to 25% by weight of the silica filler.

7. A dental pit and fissure sealant according to any one of the preceding claims, in which the silica filler yi contains from 5 to 30% by weight of calcium silicate.

8. A dental pit and fissure sealant according to Claim 7, in which the silica filler contains from 5 to 15% by weight of calcium silicate. 9 \n 1 1 1 S.

9. A dental pit and fissure sealant according to any one of the preceding clajTs, in which the silica filler has a particle size of less than A dental pit and fissure sealant according to any one of the preceding claims, in which the polymerisable acrylic resin contains a methacrylic resin.

11. A dental pit and fissure sealant according to any one of the preceding claims which is light curable.

12. A dental pit and fissure sealant according to any i U one of the preceding claims which additionally contains from 0.1 to 5% by weight of pyrogenic silica.

13. A dental pit and fissure sealant according to Claim 12, which additionally contains from 0.1 to 2% by weight of pyrogenic silica. 15 14. A dental pit and fissure sealant substantially as hereinbefore described with reference to Example 1 or Example 2. DATED MAY 16 1986 JEFFERY JAMES CHEETHAM By His Patent Attorneys KELVIN LORD AND COMPANY PERTH, WESTERN AUSTRALIA. 10 i-