COMPOSITIONS FOR THE TIPS OF DRILLS USED IN DENTISTRY

Field of the invention

This invention relates to the lubricant field, in particular to compositions used to lubricate the tips of drills used in dentistry.

State of the art

As is common knowledge, when drill tips are used, in particular fine tips, if subject to excessive force such as for example occurs when an attempt is made to widen fine or not perfectly straight channels, the tips are easily broken.

For example, on account of to daily use and difficulty of execution, endodontics is a significant part of dentistry and refers to all those interventions whose aim is to remove soft tissue in the root canal of the tooth and to shaping said canal to allow it to be filled with gutta-percha cones so as to seal it completely from the bone in which it is contained.

In order to achieve the aforementioned result, the rotating action of nickel-titanium tips is used, which when applied to special handpieces equipped with micromotors and a speed reducer, are guided by the dentist's hands into the root canal with gradual 1 - 1.5 mm backwards and forwards movements.

Tip advancement is restricted as set out above to ensure that the tip enters the root canal slowly thus preventing it from overheating, which could result in breakage.

Notwithstanding the operator's precautions, the tip can occasionally come into contact with fractures, especially when the canal is particularly narrow or has accentuated curves, with the tooth having a foreign body blocked within that cannot be efficiently repaired, being irreparably compromised.

The desirability of a product which allows the prevention (or the significant reduction) of the aforementioned risk of breakage is therefore clear.

Existing literature refers to pastes containing complexing agents (such as EDTA), sodium hypochlorite and urea (see US 4.758.163) or mixes of cetyl alcohol, sodium lauryl sulphate, propylene glycol, methyl- propyl-, butylparaben (see US 5.149.536), which are used as irrigants to remove detritus that forms following endodontic procedures or as lubricants for the tips and which, given their composition, have nothing in common with the compositions pursuant to this invention.

Summary of the invention

It has been surprisingly found that by applying a composition comprising a significant quantity of included liquid to the drill tips used in dentistry, it is possible to nil (or to an extremely low figure) the likelihood of tip breakage while at the same time increasing the cutting efficacy of the tip itself in that said composition prevents the shavings of material drilled with the file from sticking together and is in fact a transport agent which allows the removed material to be distanced by dragging it out of the drilled hole.

Summary of the invention

Examples of possible compositions pursuant to the invention are gel, emulsions or pastes essentially comprising polysaccharides (e.g. polysorbates), deriving from algae, collagens, clays, silica gels, modified cellulose, acrylic polymers (Carbomer and similar), vegetable gums or other similar water-dispersible compounds, polyethylene glycols, vegetable and animal oils, liquid paraffin and a liquid (preferably water, however liquid alcohols or polyols such as ethyl alcohol or glycerine or hydroalcoholic solutions could also be used).

Preference is given to compositions in which the aforementioned components form a gel, by which term we mean a composition in which the liquid is dispersed and incorporated in the solid phase.

Specific examples of components as defined above pursuant to the invention are: cellulose and its derivatives (e.g. hydroxymethylcellulose), carrageen, zeolites, montmorillonite, jojoba oil, tallow, and so forth).

The standard products used to promote the formation of gel can also be used depending on the products used for the formation of gel, such as triethylamine, sodium hydroxide, surfactants, and so forth.

In addition, compounds capable of increasing specific heat and the thermal capacity and conductivity of water (e.g. water-soluble saline compounds) are also preferably added to the aforementioned composition and, for such purposes, simple tap water may also be used instead of deionised water

For example, a composition pursuant to the invention (components expresses in weight to total weight) comprises:

water 93.4%

Carbomer ^® 2.4%

Sharomix ^® 1.0%

Tween 20 ^® 3.0%

Sodium hydroxide 0.2%

As previously mentioned, the chosen composition must also clearly have a suitable viscosity to allow it to adhere to the walls of the rotary tip without quickly dripping away.

Preferably the compositions pursuant to the invention should have a viscosity of between 300 - 25.000 mPa.s.

It is however essential that the compositions as described and defined above contain a significant quantity of absorbed water in that it is the very presence of the huge quantities of water that allows the desired outcome to be achieved; the water contents shall normally be in excess of 45% in weight compared to the total weight of the composition in question.

If desired, the composition may also include preservatives, odorant products and/or sugar substitutes, disinfectants or bactericides commonly used in compositions for oral use (such as for example para-oxybenzoates and other permitted substances that have a similar effect).

Similarly, and where necessary, complexing compounds may be added to eliminate the presence of any heavy metal ions.

The compositions pursuant to the invention may be available in ready-to-use form or may be prepared as needed by mixing the dry products with the necessary quantity of liquid to form the desired gel, paste or emulsion.

The composition is applied to the tip at the moment of use by simply spreading a thin layer on the surface of the tip or by dipping the tip in the product and repeating where necessary.

The invention will now be more clearly illustrated through the below examples. Example 1

After thorough cleaning, 9.36 litres of demineralised water are placed in a Turboemulsifier at the highest speed setting (around 1 ,800 rpm). 500 g of Metolose is slowly added until the product is completely dispersed thus eliminating any lumps that may have formed.

After dispersing the product, mixing continues for a further 15 minutes then the product is allowed to swell overnight without mixing.

At this point mixing is increased to a maximum by applying a vacuum (1 - 10 mmHg).

At this stage 0.1 litres of Sepicide HB is added and mixing is resumed for a further 10 minutes. The product is then poured into the containers.

Example 2

Proceeding as per example 1 9.6 litres of demineralised water and 20 g of imidazolidinyl urea are placed in the Turboemulsifier.

120 g of Carbopol ^® 940 are then added and, following a resting period, 120 g of triethanolamine 98% and 0.1 litres of Sepicide HB ^® , before pouring the product thus obtained into the special containers.

Example 3

Proceeding as per example 2, but using 180 g of Carbopol ^® 940, 180 g of triethanolamine and 0.1 litres of Sepicide in the corresponding steps.

Example 4

Proceeding as per example 1 , 9.4 litres of demineralised water are placed in the Turboemulsifier.

240 g of Carbopol ^® 940 are then added and, following a resting period, 240 g of triethanolamine 99% and 0.1 litres of Sepicide HB ^® , before pouring the product thus obtained into the special containers.

Example 5

24 g of Carbomer ^® 340 FD are added to 927 g of sterile water in a turboemulsifier that is being constantly mixed and left to hydrate the compound before activating the turboemulsifier until a complete homogeneity is achieved.

10 g of Sharomix ^® 707 and SML 20 ^® (TEGO) are mixed in a separate container before being added to the previous container that is being constantly mixed.

9.0 g of 30% sodium hydroxide solution are then added to the mass being mixed and allowed to rest before collecting the gel thus formed.

The products pursuant to the invention have been tested in tooth canal drilling tests using Hero nickel-titanium tips while observing the complete absence of breakage as regards the tips used compared to similar tests carried out without the use of the product together with a marked improvement in drilling efficacy.

Similarly, the use of the compositions pursuant to the invention may also significantly facilitate drilling that normally takes place in the course of other dentistry procedures such as for example for the placement of dental implants.