WO2017020107A1

WO2017020107A1 - Dental restoration composition

Info

Publication number: WO2017020107A1
Application number: PCT/BR2016/050181
Authority: WO
Inventors: Isabela PINHEIRO CAVALCANTI LIMA
Original assignee: Technew Comércio E Indústria Ltda
Priority date: 2015-08-05
Filing date: 2016-08-02
Publication date: 2017-02-09
Also published as: BR102015018801A2; BR102015018801B1

Abstract

The present invention relates to a dental restoration composition with improved physical properties in comparison with commercially avaible compositions having similar indications in the same field.

Description

"Dental Restorative Composition"

Field of the Invention

[001] The present invention relates to a dental restorative composition with enhanced physical properties compared to those of similar indication available in the related market.

State of art

There are reports in the history of mankind about the art of the practice of dentistry, dating from 3000 BC, however modern dentistry emerged in 1728 when Fauchard, considered by many to be "the father of dentistry" published a treatise describing various types of dental restorations. In the mid-nineteenth century the first studies on dental amalgam brought more scientificity to the research methods of the time and in 1895 with the definitive entry of Black into scientific research these studies and sporadic findings assumed a consistent character, not only in dentistry, but in all fields of dentistry existing at the time.

In 1919, at the request of the US Army, the National Bureau of Standards (now the National Institute of Standards and Technology (NIST)) developed further studies on dental materials and their manipulations. The American Dental Association (ADA) and the studies have taken on huge proportions and subdivided into categories such as: physical properties, chemical properties, clinical behavior of materials, creation of new materials, instruments, research methodologies and testing technologies.

[004] In the mid-1950s, Buonocore, Willeman, Brudevold (1956), described in detail what would be the earliest scientific experiments on the adhesion of restorative materials to the human tooth, specifically dentin, through The use of acid attacks on this surface and the subsequent application of adhesives, even those used for the then employed acrylic resin, observed improvements in resin / tooth bond strength and margin solubility in evaluations that lasted five months.

The increment of colorless vinyl silane fused silica particles to the epoxy matrix of acrylic resin by Bowen (1956) brought a great quality gain as regards the increase in dimensional stability and lower solubility, which had been higher. problems of existing resins for dental restorations. The bisphenol A glycidyl methacrylate (bis-GMA) system, developed six years earlier and patented by the same Bowen only in (1962) generated at the end of the process smaller polymerization shrinkage by promoting crosslinking of large molecules, especially double carbon bonds (C = C) of the methacrylate groups present in the molecule, however, there were still serious problems such as marginal infiltrations, fractures and large surface wear. The development of bis-GMA thus began the dental age of composites.

[006] The development of composite resins has been pursued ever since. All current research points to the incorporation of inorganic reinforcing particles of different proportions and shapes, as Philips (1998) already pointed out.

[007] The current composites available on the market differ little, if any, in their composition from this evolutionary process. The macroparticle resins practically no longer exist since due to the size of the inorganic particles they presented unsatisfactory surface smoothness. Although microparticulate resins have excellent polish, their disadvantage is their high polymerization shrinkage rate due to the low percentage weight load of these resins. Nowadays they are indicated for the application of a superficial layer in the aesthetic restorations of the anterior teeth. In order to combine the advantages of macro and microparticle resins, hybrid and microhybrid resins have emerged, which currently represent the largest contingent of trademarks, and according to manufacturers, have a "universal" indication and can be associated to obtain better results. [008] Composites may also differ in their flow, there are now called flow and compactable resins. The former has high flowability and is suitable for ultra-conservative cavities and as a backing for posterior tooth restorations to function as a shock absorber due to the low modulus of elasticity. According to MESQUITA (2006) there are resins for lining posterior restorations that present similar hardness to dentin, thus avoiding fracture risk. Already the compactables, has the proposal to restore posterior teeth due to the best mechanical and physical properties.

[009] The most current resins have shown that not only the amount of charge has been the subject of studies but also their shape, composition and distribution in an attempt to increase their physical and optical properties. For this reason, much focus has been given to the so-called nanotechnology, which according to URE (2003) consists in the manipulation and measurement of materials in the scale of below 100 nanometers. These new materials have inorganic particles ranging from 20 to 75nm, which decreases the polymerization contraction and promotes a very satisfactory surface smoothness. Clinical research has been conducted to evaluate the performance of these new types of composite resin. MAHMOUD et al. (2008) in a 2-year follow-up found a very acceptable clinical performance similar to that of a microhybrid resin.

[010] Despite having this true arsenal of materials in hand, no composite resin has achieved excellence from an ideal restorative material. Considerable improvements in resin formulations are anticipated at the expense of this nanotechnology.

Background of the Invention

[01 1] Physical beauty is undoubtedly one of the most coveted attributes of societies of all time, much more vehemently of today's. The aesthetic varies according to the eye of the beholder, and is therefore extremely subjective and difficult to quantify. However, the importance of smile in any type of culture for facial harmony is undisputed. [012] Through the first really scientific experiments on the adhesion of materials to human dental structures by Buonocore, et al (1956), and on the inclusion of colorless fused silica particles treated with vinyl silane, the epoxy matrix of acrylic resin, which was previously used as the most aesthetic restorative material, and the bis phenol system. The glycidyl methacrylate (bis-GMA), developed six years earlier and patented by Bowen only in (1962), was beginning of the dental age of composites. Since then, the vast majority of research on composite resin for dental use, aimed at its mechanical improvements, as stated by Bayne, Heymann and Swift Jr. (1994) and Philips in 1996, points to the improvement of inorganic filler particles, both in concerning its shape and size, as well as its dispersion in the organic matrix.

[013] With the evolution of research several classifications have emerged for these materials, considering their use / clinical indication, size and / or shape of inorganic particles, among many other forms of concept. What is a constant is the search for resin composites for direct dental restorations to have mechanical properties such as resistance to wear, diametral traction and compression, sufficient to offer resistance to the dental element, as Dang and Sarret (1999), Suzuki assure. (1999) and Rudeli, et al (1999). And this must be independent of its categorization.

[014] What is ratified by the literature is that resin composites are the most versatile and reliable direct dental restorative materials on the market today. Among its main advantages are the possibility of preservation of the dental structure, due to its adhesiveness, and aesthetics, however, its main disadvantages lie in the fact of its polymerization contraction, and in the relative mechanical, and rather dependent, biological resistance. and mechanically, of the oral ecosystem of the patient receiving it.

From the scientific and practical point of view, the ideal would be that a resin, considered as universal, would serve as a restorative material. to the prerequisites peculiar to the front and rear teeth at the same time.

[016] To be considered universal, ie Black's Class I, II, III, IV and V cavity preparations as a primary indication, a direct dental restorative resin must have the following characteristics: easy and quick (non-sticky) handling; easy to carve; excellent finishing and polishing; fast and accurate color selection; chameleon effect, providing a perfect color match with the natural tooth; three levels of translucency, providing natural chromatic effects when the layering technique is used.

[017] Facing some weaknesses, especially mechanical new studies have pointed to the development of harder materials.

[018] For authors such as Jordan and Suzuki (1991), composites have a wide advantage over metallic materials in the restoration of posterior teeth, not only due to the absence of mercury and low thermal conductivity, but mainly by their bonding to the dental structure. Mondelli (1995) refers to posterior tooth resins as alternatives and not substitutes for amalgam, especially when considering that the latter are still widely used in the world, either by socio-economic factors or by the credibility of the material. Nash et al (2001), agreeing with the previous statement opines that such composites will quickly take the place of amalgam.

In order to offer the dentist an aesthetic material and at the same time more resistant to the masticatory efforts of the patient, condensable resins have emerged, their larger number of filler particles and their irregular shape make it difficult to slide and favor the compaction of the material in the cavity. , and it is this characteristic of manipulation that gives the condensation operator the sensation for Leinfelder, et al (1999). However, also due to this characteristic, its Young modulus reflects a greater possibility of compression fracture. [020] According to Busato (1996), Baratieri, et al (1999), Choi, et al (2000) and Manhart (2001), the purpose of the emergence of compactable resins was to combine the cosmetic quality of resins with the technical facilities of amalgam in posterior teeth. Its major advantages came from the increased viscosity and the presence of many large particles mixed with micrometer loads and consequently better condensing capacity of the material to the cavity, lower volumetric shrinkage and considerable increase in mechanical and wear resistance, greater polymerization depth. and high rigidity. The disadvantages would be the color due to the refractive index and the greater difficulty of finishing and polishing.

In view of the foregoing, and aiming at decreasing the undesirable attributes scientifically and clinically observed for direct dental restorative compositions, the development of this dental restorative composition which is now claimed by the present invention has been developed.

[022] The charge employed as a value-adding restorative composition and reason for the application of this unpublished patent is diatomite, which according to Joiy (1966), Bicudo and Bicudo (1970) and Moro, et al (1981) is a sedimentary rock constituted by the accumulation of diatom algae carapaces which are microscopic, unicellular algae, belonging to the division of the Chrysophyta vegetable kingdom and to the Bacillariophyceae class, order bacillares, having complete cells containing membrane, nucleus and protoplasm.

[023] For Kadey and Frederic (1975) and Moro et al (1977) the growth and reproduction of these algae only occurs under favorable environmental conditions, ie, in a non-toxic environment where there are also suitable conditions for photosynthesis to occur ( shallow bowls), rich in nutrients and silica.

[024] Ciemil (2004) reports that the average life of these algae is 24 hours and each individual can give birth to up to 100 million offspring within 30 days. Such factors led us to believe in its potential to improve the mechanical properties of said starting composition, because due to its origin presents chemically high silica content and low levels of Al 2 O 3, CaO, MgO and other impurities, according to Santos (1982).

[025] Smith (1962) studying diatomite and its possible applications in dental materials such as alginate found that this powder increased the rigidity of the irreversible hydrocolloid gel, making its texture smoother and giving it a firm, non-sticky surface. This was the first official report in the literature on the use of diatomite in dental materials.

[026] Noting the great ability to soak liquids as a result of its high porosity, Zimmermmann (1976) says that diatom rock is quite versatile, whether in dentistry or other areas of knowledge, such as removing color water contaminated by colored metals.

[027] Its versatility and chemical properties converge to a favorable incorporation of this dental resins such as bis-GMA, or other preloaded, in the industrialization phase. One of the advantages is that diatomite acts as an inert material, without reacting chemically with the resin, but acting simply as a filler and / or reinforcement that provides the materials with good mechanical properties as it allows a reasonable permeation of liquids through Yes.

[028] Dentistry as a science walks today aiming not only at the individual's oral rehabilitation, but more gain in their systemic quality of life. Increasingly, the importance of creating interfaces and links with areas of knowledge that for many years seemed to be unrelated, such as Dentistry and Materials Science and Engineering, is growing.

Thus, an unprecedented, synthesized and properly characterized dental restorative material is shown here, which is intended for use in both anterior and posterior teeth, therefore, it has universal employability as a direct restorative material due to its physical properties. higher than the resins sold today. [030] In order to avoid any conflict with existing dental restorative composite compositions, it is important to highlight the following items.

[031] There are currently various forms of silicas (SiO ₂ ) incorporated into dental restorative composite materials: crystalline, vitreous and amorphous silica, silica gel, colloidal silica, among others.

[032] Among the most common that perform the structural load function of the composite, quartz is the most common form of silica. There is also fumed silica, which is a pyrogenic, hydrophilic and thixotropic silica. It is obtained industrially and produced in a flame. It consists of microscopic drops of amorphous silica fused into branched chains into three-dimensional particles that then clump together into tertiary particles. The resulting powder has extremely low density and high area and surface. Its three-dimensional structure results in a thixotropic increase in viscosity, behavior that terminates when used as a thickener or reinforcing filler. Smoked silica has a very intense thickening effect. The primary particle is from 5.0 to 50.0 nm. The particles are non-porous, and are designed to

2 3 surface area from 50 to 600 m and density from 60 to 109 kg / cm. Another presentation is colloidal silica which results from the suspension of fine, amorphous, non-porous silica spherical particles.

Therefore, to demonstrate this invention as having an innovative character, it is ratified that no silica, currently described in the world as a component of a photopolymerizable dental restorative composition or sealer of photopolymerizable pits and fissures, exhibits the structural characteristics of DIATOMITE. Type of silica employed in this dental restorative composition which is currently applying for this patent application. Such silica confers to this innovative and unprecedented composition, physicochemical properties that differ from others of the same industrial lineage and of equal clinical employability. One can thus highlight its porosity. All other silicas used in the dental restorative composites industry have a structural arrangement that does not allow the permeation of any other components. of the composite through itself, unlike diatomite, as can be seen in the following image, which has pores all over its surface and body, these pores having nanometric dimensions. Because of this only diatomite can impart to a dental restorative composition the characteristics cited in this application.

Brief Description of the Figures

[034] - Figure 1: SEM images of diatomite powder (diatom frustules).

[035] - Figure 2: SEM image of diatomite powder (diatom frustules) measuring pores in nanometers.

[036] - Figure 3: The isotherm adsorption curve reveals that diatomite has the characteristic of superficial micropores.

[037] - Figure 4: The thermogravimetric curve of diatomite presents a very small moisture percentage, which is demonstrated by the linear character that assumes up to the maximum temperature of 600 ^Q C.

[038] - Figure 5: Thermogravimetric curve and thermogravimetry derived from the composition without the addition of diatomite.

[039] - Figure 6: Thermogravimetric curve and thermogravimetry derived from the composition plus diatomite.

[040] - Figure 7: Representative graphs of X-ray diffraction (XRD) of diatomite.

[041] - Figure 8a: X-ray diffraction of resin with diatomite.

[042] - Figure 8b: X-ray diffraction of resin without diatomite.

[043] - Figure 9: SEM image of composition plus diatomite. Illustration of homogeneous dispersion of polymeric matrix diatomite.

[044] - Figure 10: Microhardness values of the target composition.

[045] - Figure 1 1: MO view of composition surface after microhardness testing (72 hours after polymerization) with 200X magnification.

[046] - Figure 12: SEM images with magnifications of 25,

100 and 500 times respectively. [047] - Figure 13: Fracture pattern in the face of diametrical compression. SEM images with magnifications of 25, 100 and 500 times respectively.

[048] - Figure 14: Marginal integrity pattern, material / metal matrix in the face of diametric compression. Images obtained through SEM at 80 times magnifications.

Brief Description of the Invention

[049] The currently marketed direct dental restorative compositions are fundamentally composed of three distinct portions, both in chemical structuring and in relation to their function in the final material:

A - Polymerizable portion, organic matrix, represented by monomers (Bis GMA (bisphenol A diglycidyl methacrylate), Bis EMA (bisphenol A dimethacrylate ethoxylate), TEGMA (triethylene glycol dimethacrylate), UDMA (urethane dimethacrylate, among others possible and less applied) to this end) employed alone or in their various forms of association.

B - Photopolymerization initiator which may be: camphorquinone, EDB (ethyl-4-dimethylamino benzoate), Irgacure (phosphine oxide, phenyl (2,4,6-trimethylbenzoyl)) or a mixture thereof or any other of lower commercial employability.

[052] C - Inorganic fillers, the most commonly used being: barium glass (barium aluminum borosilicate), Aerosil (hydrophobic colloidal silica), zirconium dioxide (mixed zirconia oxide), pyrogenic silica, quartz, among many other commercially available structural forms.

[053] The studies leading to this patent application were based on comparing various concentrations of diatomite insertion in a base dental restorative composition, the composition of which is as follows: mixture of monomers (Bis GMA, Bis EMA, TEGMA, UDMA), primers (camphorquinone, EDB) and preservative (Butylated Hydroxytoluene) 19 - 21% by weight of the composition; silanized barium glass 55-57% by weight of the composition; colloidal silica 5 - 6% by weight of the composition; mixed oxide zirconia and silica 17 - 19 wt.% of the composition and pigments 1 -2 wt.% of the composition.

[054] In this sense the novelty of this invention lies in the fact that the incorporation of diatomite (calcined flux diatomaceous earth) as inorganic filler, to the above described monomeric organic matrix. Such diatomite should be included in the preferably unsilanized composition, so that its filtering auxiliary characteristics are maintained, that is, its ability to be permeated and percolated by the monomer is sustained, this being its main positive differential of other charges, including those of silica, components of the composition. However, small percentages of silane may be used as long as such property is not impaired.

Regarding the range of incorporation of diatomite the dental restorative composition stands out that it has amplitude of 0.05% to 5.0% by weight of the composition. However, the ideal values of such an increase in diatomite are between 1.0% and 2.0% by weight of the composition.

[056] Although diatomite is also a type of silica, it has not been described so far as being used in any direct dental restorative material. In addition, it has peculiar and individual structural characteristics that differentiate them from other silicas commonly used for this purpose.

[057] Thus, it is permissible to highlight its hollow structure, with nanometric pores, (unlike the other impermeable silica fillers) and therefore allows the permeation of monomers through itself, minimizing the "wedge" characteristic of the load within the matrix in view of the cariogenic challenge proposed by the buccal ecosystem, due to the increase of mechanical enticement between both (when compared to the conventionally employed loads), such structural arrangement also leads to its use by reducing the polymerization shrinkage (since its incorporation increases the amount of aggregate inorganic load that can be added to the organic matrix, making this composition unprecedented and having better properties as a result of this fact) and improving mechanical characteristics such as compression, diametral compression, roughness, strength flexural, microhardness and wear when using commercially available dental restorative compositions.

Detailed Description of the Invention

[058] Diatomite is the differential item of this dental restorative material. There is no report of any other material of the same clinical indication that contains it in its formulation, hence the originality of this patent proposal. Diatomite determines numerous positive differences in the chemical physical behavior of this direct dental restorative composition.

[059] There are reports, as Otmer (1997) demonstrates, of the use of diatomite since 532 AD, where in the Roman Empire building bricks were made of this material due to its lightness. In 1860, with the discovery of the large deposits of diatomite in Hanover, Germany, it began to be used on an industrial scale in the manufacture of liquid absorbent paper. In Brazil, studies of diatom algae began in 1880, when algae were classified according to the lacustrine environment, having been called Actinella brasiliensis. Around 1976, it began to be used in the United States as a substitute for paper pulp, cotton, and cellulose and asbestos filters for liquor filtration.

[060] Analyzing an alleged clay from Campos, Rio de Janeiro, Lohomann (1977) found that it was actually a diatomite consisting of tiny cylinders of Melosira and other diatoms, highlighting fructules of navicle and eunotia. , as well as sponges spikes.

[061] Findings of diatomite are reported practically all over the globe where there is fluoviolacustrine sediment. Brazilian diatomite reserves are in the order of 3.2 x 10 ⁶ tons and are mainly concentrated in the states of Rio Grande do Norte, Bahia, Ceará, Rio de Janeiro and Santa Catarina according to data from Melo (1989) and Yarbook ( 1996).

[062] World reserves of diatomite are in the order of 800 million tons, of which 250 million are in the USA. Brazil occupies a modest place in the production of diatomite in the world market, according to information from the Mexican Secretariat of Economy (SEM) (2005).

[063] Diatomite "in natura" is an amorphous hydrogel substance, so that the ore is pure, massive and stratified. Deposits according to technology-developing companies such as Brasilminas (2005) are sometimes pelagic, sometimes shallow lagoons, or sometimes even occur in narrow bays, usually such deposits are concentrated at the bottom of intermittent lagoons, marshy terrain. , disseminated in veins, reefs, curly, forming bodies and terraces.

[064] Meisiner's (1981) findings reveal that diatomite can also be loose and earthy, contaminated with organic matter, calcium and magnesium carbonate, thin clays associated with volcanic ash, and other minor impurities.

[065] The presence of diatom silica and organic matter, for Santos, Bon and Amaral (1998), is used as the base criterion for the distribution of three classes in order to define the quality of the main diatom deposits: 1. Class A Diatomites - Good quality diatomites having a chemical composition close to or within known international standards; 2. Class B diatomites - diatomites usable for beneficiation; and 3. Class C diatomites - diatom sediments of uneconomic use for beneficiation.

[066] This product is treated in three different ways: natural, calcined and calcined flux (or also called calcined with flux), according to its intended use, as described by Ciemil (2004).

[067] According to studies by Smith (1962) on diatomite and its possible applications in dental materials, it can be deduced that this whitish powder most often acts as an excipient when added in certain amounts, increasing the stiffness of the irreversible hydrocolloid gel (alginate), making its texture smoother and giving it a firm, non-sticky surface. [068] Zimmermmann (1976), suggests an implementation of the use of diatomite on an industrial scale based on its great versatility. The diatom rock due to its great porosity serves to soak nitroglycerin, constituting dynamite. And also based on this property, it suggests the use of processed rock as a raw material in the manufacture of filters. In the paint industry it also serves as a basic ingredient in the manufacture of artificial paints. When transformed into silicate it can be used as ceramic. Once reduced to impalpable dust, the diatom rock serves to polish and make dentifrice powders.

[069] For the Mexican Secretariat of Economics (SEM) (2004) diatomite can have many jobs such as industrial filters, especially in beverage manufacturing (especially beer), precious metal industries, solid separation ultramicroscopic, adhesives, pharmaceuticals, solvents, lubricants and dyes (its porous structure prevents blistering while ensuring faster drying due to solvent evaporation).

[070] According to Joly (1966), Bicudo and Bicudo (1970) and Moro, Kiyohara and Santos (1981) diatomite is a sedimentary rock consisting of the accumulation of diatom algae carapaces which are unicellular microscopic algae belonging to the division of the Chrysophyta plant kingdom and the Bacillariophyceae class, bacillares order, having complete cells containing membrane, nucleus and protoplasm.

[071] For Kadey and Frederic (1975) and Moro (1977) the growth and reproduction of these algae occurs only under favorable environmental conditions, ie, in a non-toxic environment where there are also suitable conditions for photosynthesis (shallow basins). ), rich in nutrients and silica. Ciemil (2004) reports that the average life of these algae is 24 hours and each individual can give birth to up to 100 million descendants within 30 days.

[072] According to Bon and Santos (2005) the term silica refers to silicon dioxide compounds, S1O2, in their various forms including vitreous and amorphous silicas. Silica and oxygen are the two most abundant elements. On the earth's crust, the authors find that silicas can be classified into: a) crystalline forms, b) amorphous forms, and c) rocks that contain more than 90% of their silica composition (diatomites are in this classification).

[073] The Bacillariophyceae class has two subclasses: the Centricae (discoid) with cylindrical, circular, polygonal or elliptical frustules, with symmetry and radial arrangement, presenting about 100 genera and 240 species, according to research by Abreu (1973). ); and Pennalles (peniform, navicular) that have non-cylindrical frustules, with axial arrangement and symmetry, presenting about 70 genera and 2,900 species, being more easily found in freshwater, but may also occur in marine waters, as confirmed by Kadey. and Frederic (1975) and Watson and Nicol (1975). The fructules of the Centricae and Pennalles diatoms have dimensions that can vary from 4 to 500μιη, being the predominant subclass in Pennalles in Brazil, as shown by Carvalho's research (2005).

[074] It is a lightweight, powdery material that roughly exhibits chalk roughness, and whose colors may vary from white to gray, depending on the content of organic matter in the raw state, as indicated by the studies of Batista (1973). Diatom frustules are formed of amorphous silica and impurities such as quartz, calcium and organic matter, according to the studies by Batista (1983).

[075] The physicochemical properties are intrinsically related to the morphology of intact and fragmented carapaces, texture, packaging, nature of the silica surface and solid impurities. Santos (1975) also highlights as main characteristics: color - white, cream. , brown, light gray and dark gray or even pink (when calcined); Mohrs scale hardness - from 1.0 to 1.50 as a function of porosity of microscopic particles; specific weight - 1.90 to 2.35 g / cm ³ , when calcined ranges from 0.20 to 0.50 g / cm ³ ; relative specific mass - 2.10 to 2.30 g / cm ³ ; bulk density - 0.12 to 0.50 g / cm ³ when calcined; crystalline system - amorphous; melting point - from 1400 to 1650 ^Q C; trait - opaque or earthy; cleavage - absent; solubility - insoluble in acids, except for hydrofluoric; refractive index - 1.42 to 1.48%; and, thermal conductivity - low.

[076] According to the Mexican Secretariat of Economics (SEM) (2003) diatomite is a powdery, thin and porous rock with a friable appearance, the color in case of high purity is bright white, but can vary between pink and gray, has high porosity, very low density, and therefore high absorption capacity of liquids, its abrasive power is low, considered a "soft" rock, also has low thermal conductivity and high temperature resistance, melting point between 1400 to 1750 ^Q C, specific gravity 2.0 g / cm ³ (after calcination 2.3 g / cm ³ ), generally exhibits a surface area of 10 to 30 m ² / g (calcination process reduces and stiffens diatomite particles, sintering part of the material in microscopic clusters with regular distribution by size), its refractive index is from 1.40 to 1.46 (after calcination can have 1.49), Mohs hardness is from 4.5 to 5.0 (after calcination from 5.5 to 6.0), it is chemically inert and the percentage of humid (varies by deposit between 10 and 60%).

[077] Chemically, diatomite has high silica content and low levels of Al2O3, CaO, MgO and other impurities which, depending on the type of application, have to be totally or partially removed from its composition, according to Santos (1982).

Diatomite employed in the composition of this dental composition has as its basic composition S1O2 (82.05%). Displays a particle size distribution with a range between: 0.10 μιη - 500.00 μιη / 100 Classes with Pressure / Distribution: 500 mb / [60] 10% diameter: 1.69 μιη, 50% diameter: 1 1 .60 μηπ, diameter at 90%: 30.03 μηπ and mean diameter: 14.43 μηπ.Α surface analysis by the BET method resulted in a surface area of 26.72m ² . The results show that this area is suitable for the incorporation of the polymeric resin in the diatomite pores. The isotherm adsorption curve (Figure 3) reveals that diatomite has the characteristic of surface micropores. [079] The thermogravimetric curve of diatomite (figure 4) shows a very small percentage of humidity, which is demonstrated by the linear character that assumes up to a maximum temperature of 600 ^Q C.

[080] The thermogravimetric curve for dental restorative composition without the addition of diatomite (Figure 5) shows that the material loses mass relative to the decomposition of the polymeric chain, at a temperature range of 30 to 600 ° C, remaining at 80% of the mass. initial A more detailed observation allows us to realize that there is moisture in the material up to around 190 ^Q C, from then onwards the water loss begins abruptly through the elimination of OH, which peaks around 400 ^Q C The polymeric chain is then broken into four (04) stages, and in the last stage there is the formation of a CO ₃ carbonaceous phase, which then decompose, forming the oxidized phase of S1O2 until the maximum temperature is reached. of 600 ^Q C.

[081] This test simulates the constant aggressions to which dental materials are subjected to the oral cavity and in an exacerbated manner demonstrates the phase variations that can be encountered and the severity of these changes for the longevity of restorations.

[082] In general, dental restorative composites absorb water from the oral environment and thus unbalance their polymeric structure, leading to major clinical disorders, however the constant thermal variations in the mouth cause this condition to change for greater loss or greater water gain by the matrix. Organic.

By treating the dental restorative composition without the addition of diatomite as a microhybrid, it can be stated that the water sorption values of the medium for such resins are lower (0.3 to 0.6mg / cm ² ) than for the microparticulate composites (1, 2 to 2.2mg / cm ² ) due to the low volume fraction of polymers of the former and obviously their large amount of inorganic charge present. Up to 0.08% volume expansion can be found. [084] Thus, the same reasoning can be used when it comes to the loss of this water by the matrices in the heat, the more compacted the inorganic charges, the lower the likelihood of hydroxyl (OH) elimination, and thus deducing that there is an inversely proportional relationship between amount of charge and water loss by the matrix.

[085] The addition of diatomite to the dental restorative composition slightly and positively altered the pattern of the initial curve (Figure 6). This result demonstrates that all the proportions of diatomite increase were able to change, even quite smoothly, the thermal behavior of the starting material in the thermogravimetric test applied, which evaluates the polymer chain decomposition and moisture loss versus (mass variation). , Am) temperature. It should be considered here that temperatures are purposely extrapolated.

[086] This behavior indicates that the material is sensitive to an additional load that interferes with its thermal properties. The high porosity of diatomite greatly facilitates the penetration of the monomers through it, high temperature resistance (melting point between 1400 to 1750 ^Q C), low thermal conductivity and its very low density, were able to positively alter the capacity of the matrix. Dental restorative compositions tests (plus diatomite), in proportion to the amount of diatomite present, lose less moisture in the face of the heat applied.

[087] Some researchers believe that the expansion due to sorption of water from the oral fluids by the matrix can minimize can lead to serious clinical failures we believe water loss as well.

[088] Evaluation of TG curves in addition to other characteristics of dental restorative compositions with and without diatomite in their formulation may lead to the general belief that the insertion of diatomite within acceptable mechanical limits slightly and positively alters the pattern. behavior of resins in the face of thermal stresses as can be understand in TG trials. This clinically results in decreased postoperative sensitivity, especially heat.

[089] Analysis of the diatomite X-ray diffraction (XRD) graphs (Figure 7) shows that the two most evident peaks represent crystalline peaks for quartz and cristobalite impurities.

It is also possible to conclude that in view of the amorphous character of dental restorative compositions of resin, the X-ray diffraction results for materials with (figure 8a) and without (figure 8b) diatomite are similar, such facts can be ratified. by thermogravimetric curves (TG), differential thermal analyzes (DTA), differential exploratory calorimetry (DSC) and infrared (IR) spectroscopy, these last three analyzes were performed only as ratifiers of TG and XRD.

[091] Also in the process of characterization of diatomite (alone) and dental restorative compositions with and without its addition, by scanning electron microscope (SEM), results from X-ray fluorescence tests (EFX) were obtained. x-ray dispersive energy spectrometry (EDS), and images of samples with high resolution and, in micrometric scale, which allows even the visualization of pores of diatomite, these in nanometric values.

[092] When analyzing the particle size distribution associated with these images, it is better understood why the increase in conjunctural diatomite in increased mechanical properties, especially in the dental restorative composition in question of this patent process.

[093] Their particle size variation also generates pores of various sizes, but all nanometric (see figure 2), which allow the polymeric matrix to pass through itself and thus the improvement of these materials as dental restorers. There is no formation of a "foreign body" acting as a wedge, as in today's polymeric dental restorative materials, the charge / diatomite is irrefutably incorporated and incorporated into the matrix without even the need for a surface treatment agent ( silane). Due to the insertion of diatomite, the dental restorative composition (Figure 9), as nanoparticulate load, its initial physicochemical properties were increased and, having as parameters others of the same clinical indication and analogous composition, before the imputed tests can Its superiority is noted in several respects.

[095] After compressive strength analysis of the dental restorative composition (destructive test), 12 specimens measuring 4.0mm in diameter X 2.0mm in height, contained in a stainless steel ring matrix, were evaluated at different times. after curing (immediately, 1 hour, 24 hours and 7 days after), stored according to ADA standards for such a test, the following results / average values were obtained: time immediately - 0.64mm / 9.67kN, 01 hour -0.74mm / 10.38kN, 24 hours - 0.69mm / 11, 31kN and 07 days after -0.82mm / 11.16kN.

[096] This test aims to establish via a mechanical simulation what is the resilience of the dental restorative composition against the stresses applied during the chewing cycles. It is necessary for the material to be reliable that it has a modulus of elasticity equal to or greater than dentin (14 to 19 GPa) and dentin compressive strength of 230 to 370MPa and 45 to 138 MPA shear (inverse diametric compression).

[097] We may conclude from an isolated evaluation of this test primarily that:

[098] All samples of the dental restorative composition were more resistant to compression than the dental restorative compositions available today of the same clinical indication, as well as showing greater resilience.

[099] The target dental restorative composition proves the good relationship established between diatomite and resin matrix in that it does not allow, or at least hinder, the rupture of the material mass when we observe its final values compared to those in the related literature for restorative compositions. of the same clinical indication. [0100] When 1 hour was passed from the initial polymerization, and a load was imposed on the specimens, the capacities to yield to this load were significantly different as shown by the displacement values. The flow may partly compensate for the polymerization contraction due to the fact that at this stage of material hardening there is only the formation of polymeric chains, without the presence of cross-links, which certainly facilitates the molecular repositioning and generating flow.

[0101] One day after light curing the currently available dental restorative compositions undergo a "hardening" that results in the finding of low "stretch" values at the applied force, this is not noticed in the dental restorative composition object of this patent. Note also that most existing commercial dental restorative compositions achieve the highest 24-hour compressive strength values, which was not seen in the target dental restorative composition, which indicates the most intense conversion of monomers to polymers, and consequently decreased chain size.

One week later it can be noted that the stability of the chemical bonds in the targeted dental restorative composition does not allow the return of strength and yield values to near the initial ones, as is common in materials already marketed today.

[0103] Other items worth mentioning to justify the success of the test material before the control, especially in the longest period of 07 days, are the coefficient of linear thermal expansion and thermal conductivity. If there is a change in length per unit of original length when temperature changes, if nanoparticulated dental restorative compositions behave better than microparticulate, precisely because of the lower concentration of organic matrix present and / or the presence of almost no void space. Between loads, this reasoning can also be used when comparing target restorative composition to those currently in use of the same clinical indication, regarding this coefficient of expansion, and at the same time for thermal conductivity. After analysis of the diametral compressive strength (generating tensile stresses) of the dental restorative composition (destructive test), where 12 specimens measuring 4.0mm diameter X 2.0mm height, contained in ring matrix, were evaluated. stainless steel, at different times after light curing (immediately, 01 hour, 24 hours and 07 days after), stored according to ADA standards for such test, the following results / mean values X time: immediately -0, 34mm / 0.92kN, 01 hour -0.34mm / 0.97kN, 24 hours - 0.36mm / 1, 21kN and 07 days after -0.38mm / 1, 32kN.

[0105] The mechanical test employed was the alternative test, called the diametric tensile compression test, Brazilian test or indirect tensile test, which is employed for friable materials. Generally the results found for these materials present inferior results for such tests when compared to the compression ones. Both for the absolute values of displacement and for the absolute values of resistance to applied stress. The compressive stress applied to the specimen introduces a tensile stress on the material in the plane of the test machine's force application. The tensile stress is directly proportional to the compression load applied by the following formula:

σ _χ = 2P where: σ = tensile stress

π X DXT P = load applied to sample

D = sample diameter

T = sample thickness

[0106] The results of the immediate and 7-day examination of the samples show that the displacement values are equivalent, but the supported loads have always been higher over time. It can also be noted that at both times the test resin showed a more positive behavior in relation to the amount of load supported.

Continuing with the analyzes, and evaluating surface roughness also at time intervals after light curing (immediate after curing, 01 hour after, 24 hours after and 07 days after, all polishing test plus 72 hours and 7 days after polishing polymerization) five readings were taken with the apparatus in distinct regions of the same sample (all made according to the ADA standard), and thus a simple average taken between data collected. Therefore, being evaluated 02 specimens different from the target dental restorative composition for each indicated time, even though the test did not present destructive characteristics of the sample surface, this prevention was chosen in order to provide results with smaller standard deviations within the same. material group and enable the smallest analysis error possible.

[0108] In experimental groups where specimens were submitted to the finishing and surface polishing procedure, for subsequent roughness evaluation. The finishing was done in the Politriz machine, with constant rotation of 300 rpm, pressing the sample for 10 seconds against each sandpaper granulation (600, 1,200 and 1,500 μιη), according to literature, under water cooling; The sandpaper was changed after each sample was finished.

Felt disc polishing associated with the polishing paste (Artec-Artdent: diatomite and aluminum oxide) was performed with 2 to 4 μιη granulation without water in the Polishing Machine. Following these procedures, the specimens were rinsed in running water and oil-blast dried. Surface roughness measurements were measured in the same way for groups that did not receive the finishing or surface polishing procedures.

[01 10] The mean surface arithmetic roughness (Ra) values expressed in μιη already considering the standard deviation were: immediate / unpolished 0.24, 01 hour / unpolished 0.23, 24 hours / unpolished 0.17 .07 days / without polishing 0.15, 72 hours / with polishing 0.06 and 07 days / with polishing 0.06.

[01 1 1] It can then be concluded that:

A) Surface roughness was lower in all samples where polishing was performed when compared to the unpolished samples. It can be argued that the presence of diatomite renders the surface after finishing and homogeneous polishing and, therefore, with greater superficial smoothness when comparing these values with those brought by the literature for dental restorative compositions of the same clinical indication that do not contain diatomite.

B) Studies show that average surface roughness above 0.7 mm may facilitate bacterial cell aggregation, resulting in injury to periodontal tissues and facilitation of dental tissue demineralization and degradation of the restoration organic matrix. Dental restorative compositions with diatomite had Ra values between 0.24 and 0.06; therefore, the surface does not theoretically favor bacterial aggregation on the surface of the restorative material.

C) It is also noted the higher initial roughness of the target dental restorative composition, without polishing in the first 02 evaluation intervals, when compared to the others, which implies that clinically there should be extra care with these in the pre-polishing time period. The explanation for this higher initial surface roughness is in the monomeric accommodation process until the first 24 hours after polymerization, which has different characteristics due to the presence and present amount of diatomite in the matrix. Even so, the values obtained are still much lower than those required to cause significant biofilm aggregation.

D) Although many studies indicate that the smaller and more regular the filler particles, especially silica, the lower the surface roughness immediately after the restoration, the presence of totally irregular but very well distributed loads / diatomites. Throughout the matrix, it can be an extremely positive factor, without the formation of precipitates or supernatants, this proves that reducing particle size and regularity are not the only alternatives for obtaining increased surface smoothness. Although this may seem seemingly illogical, a closer study of the chemical composition and physical structure of diatomite casts doubt on its ability, not reaction, as it is a chemically inert material, but a integration with the surrounding environment, allowing it to pass through liquids and often absorbing them, such as the resinous organic matrix, it is also worth mentioning that its pores are nanometric. Thus, due to the penetrability of diatomite, small rearrangements of the matrix with the loads led to a greater surface smoothness, and that this set underwent positive variations throughout the polymerization process.

[01 12] The wear resistance of the dental restorative composition with diatomite was evaluated using a tri-corporeal device that uses as an abrasive polymethyl methacrylate (PMMA) beads with a mean diameter of 44μιη. The purpose of this abrasive is to simulate the bolus during the chewing cycle, and thus, the wear caused in the restorative material, and simulating the antagonist teeth were 2.0mm diameter steel tips positioned in the center of the specimens, being applied 75N load and frequency of 7,500 cycles / hour. When the tip reached the specimen it would rotate 30 ^Q clockwise, applying the load on the PMMA beads. When the load was maximum, the steel tip would rotate in the opposite direction and be lifted, ending 1 mechanical cycle. After 100,000 cycles the materials removed from the devices were analyzed on a profiler, and the actual wear of the material in micrometers was quantitatively determined, as the same device had been used on the same sample prior to wear implementation (measured before wear - measured after wear). wear = final result).

[01 13] This test was performed under the same conditions of time after the specimen was made as the surface roughness tests and the number of sample units was 02 specimens of the same material for each time evaluated. This test aims to simulate and accelerate the wear process of restorations that occurred in the mouth and as the other mechanics is also destructive.

[01 14] The average amount of surface wear suffered by the samples after the wear process, expressed in μιη already considering the standard deviation was: immediate / unpolished 10.9, 01 hour / unpolished 8.6, 24 hours / unpolished 7.7, 07 days / unpolished 6.3, 72 hours / polished 5.9 and 07 days / polished 5.5.

[01 15] Some authors associate wear test methodologies making the correlation of every 400,000 cycles equivalent to approximately three years of material life in a patient's mouth. Our methodology that employed 100,000 cycles allows us to deduce that the average wear of the test materials was quite satisfactory.

[01 16] It is well known that immediately after clinical light curing, commercial dental restorative compositions do not yet meet their maximum monomer to polymer conversion values, a fact which obviously restricts their surface hardness and facilitates wear in either mechanical simulations, or in the patient's mouth. The observed values show that the samples made with diatomite in its composition responded more positively to this simulation when compared to those currently marketed.

[01 17] Samples made with the target dental restorative composition had an average immediate wear of around 50% lower than current commercial dental restorative compositions, which means resistance to pullout and consequent clinical advantage, especially in this critical period. continuous polymerization, which can last up to 72 hours.

[01 18] At the second moment of evaluation, the results, although apparently similar to those obtained in the immediate test, increased the tendency of the diatomite material to be much higher in terms of surface wear resistance when compared to those currently marketed with the same clinical indication. This fact is justified by the high porosity of diatomite to enable a better mechanical embracing of the matrix with the dispersed loads, since it passes through the load that is leaked, thus increasing the surface rigidity of the specimen.

[01 19] When verification of values occurred within 24 hours of initial light curing the target dental restorative composition proceeded exhibiting quite significant absolute values of surface wear resistance. The stabilization of the photopolymerization of the matrix after one week is even more noticeable in the resin. This becomes visible by evaluating its average structural loss in this range and considering its composition and thus the possibility of internal structural rearrangement.

[0120] Finishing and polishing are noticeably influential in the dental restorative compositions analyzed in order to reduce structural losses due to wear testing. Although it is clear that the time interval of 72 hours and 07 days has no statistical significance.

The values given for the amount of surface wear, when compared to the current materials on the market and the target restorative composition, leave no doubt that the incorporation of inorganic fillers in the resin matrices is largely responsible for the improvement of their mechanical properties. This result is confirmed by several researchers who throughout the history of dentistry have always pointed out as possible solutions to changes in shape, quantity, size and even type of material used as fillers in dental resins.

Decreasing the flow power of dental restorative compositions by introducing fillers that reduce voids in the material body, in this case of diatomite dust particles, and enable a better relationship between the components of the dental restorative composition, It is also another factor that may explain the increased wear resistance of the target material over existing dental restorative compositions. Once the force is impressed, the stable chemical bonds prevent the pullout of charge particles and consequently the loss of matrix.

[0123] The diatomite particles employed in this dental restorative composition have an average diameter of 14.43 μιη, this value allows a linear wear pattern over time. Clinically this fact is reflected in compatible wear between dental structures and restorations, which in itself minimizes and / or prevents the formation of micro-cracks in the tooth / restoration interface and the accumulation of plaque leading to the emergence of caries. [0124] Other considerable factors for the success of this dental restorative composition in the evaluation of wear resistance are that, due to diatomite being a pulverulent, thin, very porous and low density rock, it has a high absorption capacity of liquids, This means that despite being considered chemically inert, it may very well mechanically aggregate into the medium in which it is dispersed. In addition, it has low abrasive power, so it is considered a "soft" rock, which makes it not become or become less destructive within the matrix when applied loads generate internal friction in the mass of material, nor when it It is detached from this matrix and lies in the surrounding region of the specimen or the restoration itself in the dental cavity.

[0125] This fact is not observed when evaluating the power of charge silica particles themselves conventionally employed in today's commercial resins, which when displaced from the commercial resin matrix, promote their wear in the oral environment as they function as abrasives, even for the surrounding enamel.

[0126] Diatomite is also characterized by being a rock that has low thermal conductivity and high temperature resistance, so, in face of the heat generated by the surface wear test does not negatively influence the reduction of the charge / matrix union.

Due to its low density, diatomite has no tendency to form agglomerates or lumps, or to precipitate on the underside of the specimen prior to complete polymerization of the polymeric matrix. This event reinforces the theory that not only the type and size of load employed, but also its distribution throughout the organic matrix, are determining factors for reducing fatigue of the material and increasing its ability to resist wear.

[0128] Some authors already envisage the possibility that there is no significant difference between some dental restorative compositions and amalgam. Regarding the wear in the first five years of clinical life, this, in particular, plus diatomite, ratifies this claim in an irrefutable character.

While on the one hand the wear that occurs "in vivo" does not correspond exactly to the results obtained in laboratories, because the loss of the anatomical form is a summation of the chemical attack of the buccal environment and the mechanical wear on the main polymeric matrix and firstly. , with direct repercussion on oral health; On the other hand, the higher the quality and content of the inorganic filler, within a boundary that does not make the assembly excessively friable, the greater the resistance to this wear, since the loads will be abraded without displacing the surrounding matrix. .

[0130] In evaluating the performance of the target dental restorative composition in the microhardness test, the same time parameters were followed after confection (06 different times) and the same surface roughness test samples were used. Therefore, 02 specimens of each material and time are evaluated.

[0131] The standard employed was that of Knoop hardness. The analyzes took place in three indentations in each of the samples examined and then observed between them: the maximum hardness value, minimum hardness value, mean value (position of the samples on the median curve, which differs from a simple arithmetic mean), standard deviation and coefficient of variation (figure 10).

[0132] Note that there is less variation between the minimum and maximum values until the first 24 hours after polymerization, than when these values are analyzed after the first day of assessment. By comparison, based on the related scientific literature, it can be seen that the average values of the target dental restorative composition are higher than those of the current commercial dental restorative compositions, which indicates greater uniformity in charge distribution by the polymeric matrix. Finishing and polishing procedures greatly interfere with surface hardness over time for the targeted dental restorative composition.

Because flexural strength is also a feature of great importance for the qualification of a dental restorative composition [0133] Such a direct test after the patent-pending product adopted the following methodology to obtain the following results.

[0134] Three-point flexural strength test was performed on a universal testing machine using a 500N load cell and an average velocity of 01 mm / min until the specimen fracture, which was 24.0 mm long, 2.0 mm high and 2.0 mm wide. The values of s were calculated by the formula: □ = 3PL / 2wb2 where, "P" is the load applied at the moment of fracture (N); "L" is the distance between the two support points (mm); "w" is the width (mm) and "b" is the thickness of the specimen (mm).

[0135] 02 specimens were used for each distinct analysis time, 24 hours and 07 days after light curing. The point of application of the load, represented by the upper surface of the specimen, is placed in a state of compression (compressive deformation), while the lower surface is in tension (tensile deformation). The flexural strength of a dental restorative composition correlates with other mechanical properties and indicates the ability of a material to withstand large vertical forces. The three-point flexion test has been advocated by several studies because it is a reliable and relatively simple method for specimen preparation.

[0136] The mean values of flexural strength values expressed in MPa ± standard deviation obtained for the adida diatomite dental restorative composition were 138 ± 3.9 after 24 hours and 152 ± 4.6 after 07 days. Both results are superior to those found for materials of the same clinical indication currently available in the market.

[0137] Optical microscopy (MO) imaging, performed on the dental restorative composition added with diatomite, provides only "coarse" images of the surface of the materials, without providing deeper information, nor related to its phases, however, produces indications of regions that suffered major or minor damage during manipulation or insertion of the material in the matrix so that it can be delimited better observation area in the scanning electron microscope (SEM) or other available methods. In a way, it demonstrates the outermost condition of the restorative material before being subjected to cariogenic challenges in the mouth.

The varied time periods in which the samples were subjected to such evaluation (06 times) did not cause differences in the observed images, except for the higher surface oxidation of the materials before their polishing. Surface oxide accumulation in the first four times is directly related to the immersion of the samples in distilled water and not in acid-rich medium as the buccal medium. The two-step images after finishing and polishing reflect the positivity of these clinical procedures in the removal of oxides and other superficial residues.

[0139] The image of figure 11 refers to the MO view of the surface of the dental restorative composition after microhardness testing (72 hours after polymerization) with 200X magnification. There is no trace of fracture due to the indentation of diamond in this material, as occurs in other dental restorative compositions of the same clinical indication. It is also possible to perceive (although this technique is not best suited for this) bright spots on the image surface that correspond to the charges.

[0140] In addition to the use of SEM already described, such equipment also allowed the detailed visualization of samples after compression fracture and diametral compression tests.

The images of figure 12 were obtained by SEM (with magnifications of 25, 100 and 500 times respectively) and reflect the fracture pattern of the dental restorative composition plus diatomite before the compression test, after 7 days of its light curing. . The material tends to rearrange itself structurally, due to the possibility of permeation of the matrix through the pores of the diatomite, to prevent the propagation of fracture traces to the center of the sample, these traces start from the surrounding metal ring and this one. This aspect makes this material positively different from those of the same clinical indication that currently exist. THE The repercussion in practice of this physical chemical behavior in the patient implies in lower risks of cohesive fractures of the material.

From the visualization of the images of figure 13, it is conceived that the direct dental restorative composition plus diatomite presents fracture pattern in face of the diametral compression, proven by the SEM (in the magnifications of 25, 250 and 500 times), near proximal, this fact is related to the resilience of this being greater than the restorative dental compositions now available on the market and of the same clinical indication. The repercussion in practice of this physical chemical behavior in the patient implies in lower risks of adhesive fractures at the tooth / restoration interface.

The compression test and the diametric compression test (both performed obligatorily until specimen fracture and simulating the resilience of materials to chewing cycles) point to this restorative dental composition plus diatomite fracture rates mathematically compatible with the above. exposed through the images.

Undoubtedly, one of the biggest challenges of contemporary dentistry with regard to dentistry is the control of the polymerization contraction of direct dental restorative compositions and, consequently, their clinical implications, which, when faced with the cariogenic challenges in the oral ecosystem, in the appearance of microleakages that damage the tooth / restoration interface not only the artificial adhesive surface, but also the dental, due to the percolation generated.

[0145] The literature presents numerous ways of measuring polymerization contraction, however, the result of the evaluation of the dental restorative composition plus diatomite obtained by the use of SEM, which at the same time is fully computerized, will also facilitate the evaluation. compression due to its easy interpretation of generated images.

02 specimens were made (contained in metal matrices as for the mechanical compression tests) and the same were polished in the same way as for the surface roughness analysis test. They are then taken to an ultrasound device for 10 minutes for complete removal of waste. The arrays were marked in four different Pilot stylus positions, which corresponded to the 3, 6, 9, and 12 o'clock positions of a clock on the surface of the matrix closest to the tip of the curing apparatus. The specimens remained for 24 hours in organic oven at 37 ^Q C in containers with distilled water.

After this time, the polymerization contraction slit was measured by the scanning electron microscope at the four previously marked points. The gap was then measured in micrometers between the metallic matrix and the mass of the dental restorative composition. Subsequently, an arithmetic mean of the four measurements was calculated, considered with the measurement of the specimen gap. The results were submitted to statistical analysis by ANOVA and Tukey test at 5% significance level to verify the difference between the polymerization contraction crack of each dental restorative composition.

[0148] The average width of the contraction slits for the dental restorative composition plus diatomite was 3.69 μιη. This data is inferior to all others of the same nature for dental restorative compositions of similar clinical indication, which results in greater clinical benefits to the patient due to the greater possibility of restoration longevity.

According to the foregoing, the dental restorative composition described herein is not only unprecedented as a direct dental restorative material, but also exhibits superior physical chemical properties to those of the same clinical indication currently on the market.

[0150] Currently marketed direct dental restorative compositions are essentially composed of three distinct portions, both in chemical structuring and in relation to their function in the final material: A - Polymerizable portion, organic matrix, represented by the monomers (Bis GMA (bisphenol A diglycidyl methacrylate), Bis EMA (bisphenol A dimethacrylate ethoxylate), TEGMA (triethylene glycol dimethacrylate), UDMA (urethane dimethacrylate, among others possible and less applied) to this end) employed alone or in their various forms of association.

[0153] C - Inorganic fillers, the most commonly used being: barium glass (barium aluminum borosilicate), Aerosil (hydrophobic colloidal silica), zirconium dioxide (mixed zirconium oxide), pyrogenic silica, quartz, among many other commercially available structural forms.

The studies leading to this patent application started from comparing various concentrations of diatomite insertion in a base dental restorative composition, the composition of which is as follows: mixture of monomers (Bis GMA, Bis EMA, TEGMA, UDMA), primers (camphorquinone, EDB) and preservative (Butylated Hydroxytoluene) 19 - 21% by weight of the composition; silanized barium glass 55-57% by weight of the composition; colloidal silica 5 - 6% by weight of the composition; mixed zirconia oxide and silica 17 - 19 wt% of the composition and pigments 1 -2 wt% of the composition.

In this sense the novelty of this invention lies in the fact that the incorporation of diatomite (calcined flux diatomaceous earth) as inorganic filler, to the above described monomeric organic matrix

The addition of diatomite in a range of 0.05% to 5.0% by weight of the dental restorative composition makes the composition not only unprecedented but also more stable.

The addition of diatomite in a range of less than 0.05% by weight of the composition does not exhibit physical chemical change that justifies its clinical use for its intended purpose, and beyond this range. The interference becomes gradually more negative until it reaches 5.1% by weight of the composition, when compared to the ideal range of increase. In addition to the ideal range of diatomite addition, the material exponentially increases its filtering potential, which substantially contributes to the reduction of its resilience, the increase of its friability and the display of mechanical imbalances that are difficult to justify clinical use for this purpose ( universal direct dental restorative). In addition to undergoing ethical changes, undesirable for the aesthetic effect, especially opacity.

[0158] By analyzing this range in more detail it is possible to obtain three distinct cuts, namely the observation regarding the weight of the composition: the first concerns the values contained in the range between 0.05% and 0.09%. by weight of incorporation of diatomite in this range despite the aesthetic characteristics are widely visualized mechanical improvements although present are still subtle; In the following interval, comprised by the values of 1.0% to 2.0% by weight, of diatomite incorporation, the best physical and chemical characteristics are exposed with increasing aesthetics. diatom rock in the dental restorative composition; in the following interval, from 2.1% to 5.0% by weight, of adding diatomite the dental restorative composition successively loses the best aesthetic characteristics, although some physical properties are maintained and others even increased.

Although diatomite is chemically inert, it gives the material greater chemical stability and mechanical strength, without rendering it friable (provided that the weight percentage composition is maintained within the suggested preferred range), on the contrary the presence of diatomite It allows structural rearrangements that make it more resistant to compression loads, diametric compression loads, surface wear, and decreases its polymerization shrinkage. All these characteristics result in the greater possibility of better workability, thixotropism and clinical substantivity. That The uniform distribution of the diatomite load by the dental restorative composition also results in increased surface microhardness and color stability which reflects the improvement of its final aesthetic properties both immediately and in the medium to long term.

It is ratified that the insertion of diatomite within this aforementioned range of 0.05% to 5.0% by weight of the composition includes for the purposes of this claim and for the production of this dental restorative composition natural diatomite or any type of surface treatment, be it silanization, plasma (electron beam), or any other modification that may alter this filtering agent.

Claims

1 . DENTAL RESTORING COMPOSITION, characterized in that it comprises diatomite in a range of 0.05% to 5.0% by weight of the composition, and monomers, photoinitiators, preservatives, inorganic fillers and pigments.

DENTAL RESTORING COMPOSITION according to claim 1, characterized in that it comprises diatomite in a preferred range of 1.0% to 2.0% by weight of the composition.

DENTAL RESTORING COMPOSITION according to claim 1, characterized in that it comprises unsilanized diatomite or any type of surface treatment which alters this filtering agent.

Dental restorative composition according to claim 1, characterized in that the monomers are preferably Bis GMA, Bis EMA, TEGMA, UDMA or a combination thereof; the photoinitiators are preferably camphorquinone, E.D.B., or a mixture thereof; the preservative is preferably B.H.T; and the inorganic fillers are preferably silanized barium glass, colloidal silica, mixed zirconia oxide and silica.