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WO2019034861A1 - Fraise à matériaux bioactifs - Google Patents

Fraise à matériaux bioactifs Download PDF

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Publication number
WO2019034861A1
WO2019034861A1 PCT/GB2018/052303 GB2018052303W WO2019034861A1 WO 2019034861 A1 WO2019034861 A1 WO 2019034861A1 GB 2018052303 W GB2018052303 W GB 2018052303W WO 2019034861 A1 WO2019034861 A1 WO 2019034861A1
Authority
WO
WIPO (PCT)
Prior art keywords
bur
bioactive
dentine
remineralisation
tissue
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2018/052303
Other languages
English (en)
Inventor
Timothy Frederick Watson
Ian Dennis Thompson
Frederic Festy
Garrit Koller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kings College London
Original Assignee
Kings College London
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kings College London filed Critical Kings College London
Publication of WO2019034861A1 publication Critical patent/WO2019034861A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C3/00—Dental tools or instruments
    • A61C3/02—Tooth drilling or cutting instruments; Instruments acting like a sandblast machine
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C3/00—Dental tools or instruments
    • A61C3/06—Tooth grinding or polishing discs; Holders therefor

Definitions

  • Embodiments of the present invention relate to a bur, such as for example a dental bur, having bioactive agents embedded therein that promote re-mineralisation of mineralised tissue after a tissue removal procedure.
  • Dental decay is the most common human infectious disease. It results in the demineralisation and denaturation of the outer protective layers of the tooth, and results in a heavily infected, softened structure mandating excavation and filling of the defect.
  • proprioceptive nerve endings are damaged, resulting in intra- operative and postoperative pain.
  • This is normally addressed by the provision of local anaesthetic prior to the procedure, but this is not always feasible, and particularly in children and patients with learning difficulties, where an injection of local anaesthetic will not always be tolerated and may be perceived as a traumatic experience.
  • This limitation of not being able to use injections in some subjects leads to under preparation of the carious lesion, rendering such under prepared lesions susceptive to secondary (recurrent) decay and further infections.
  • Overcutting carious teeth by dentists can be reduced by using a bur that cuts selectively.
  • Such self-limiting burs operate by being able to cut and remove decayed matter, but are made from material that is typically softer than healthy dentine material such that the burs abrade when they come into contact with healthy dentine and thereby do not cut thereinto.
  • Dental manufacturers such as SS White and Komet provide such self-limiting burs, such as the 'Smartbur' , described at http://www.sswhitedentai.com/products smartburs-ii, and the 'CeraBur', described at
  • Embodiments of the invention provide a bur in which is embedded bioactive remineralisation agents which are released onto the surface of the mineralised tissue being treated as the bur is used.
  • the bur is preferably formed as a self-limiting dental bur formed from a material having a hardness that is greater than that of decayed tooth matter to be removed by the bur, but softer than that of healthy dentine material such that the bur abrades against healthy dentine material when in use whilst still allowing the bur to dig into and remove decayed matter.
  • the bur is so formed so as to disintegrate or break down when it encounters these two hardness extremes (i.e.
  • the bur may be used for other in vivo surgical procedures, such as removing infected, necrotic or otherwise non-viable bone tissue.
  • the bioactive remineralisation agents are preferably particles of bioactive glass embedded within a sacrificial material, the sacrificial material being for example a polymer having a hardness of the required range for selective caries removal.
  • the bioactive glass is for example 45S5, although other compositions such as 58S, 70S30C, and S53P4 may be used in other embodiments. More generally any other materials capable of causing mineralisation within a suitable environment, such as for example many other mineral salts related to hydroxyapatite, may be used as the remineralisation agent.
  • the dental bur is used by a dentist for caries removal by being attached to a dental handpiece so as to be rotated and applied by the dentist to the dental caries.
  • the bur cuts into and removes the decayed dental tissue, but when it contacts healthy dentine the particles of bioactive remineralisation agent are released from the bur (for example as it abrades against the healthy dentine in the case of a self- limiting bur) so as to be applied to the healthy dentine, to thereby promote remineralisation of the dentine.
  • This remineralisation seals the dentine and filling interface, thereby protecting the dental pulp.
  • bioactive glasses such as 45S5 promote remineralisation by a seqential dissolution, and subsequent remineralistion of, matrix components, including Calcium phosphates and hydroxides and increase the pH to a basic environment, which favours remineralisation.
  • matrix components including Calcium phosphates and hydroxides
  • increase the pH to a basic environment which favours remineralisation.
  • an apparatus for the application of a remineralisation agent to mineralised tissue comprising a bur formed from a biocompatible substrate material having a bioactive remineralisation agent mixed therein, the bur having a hardness such that in use it wears against a mineralised tissue when the bur is driven thereagainst to thereby deposit the bioactive remineralisation agent onto the surface of the mineralised tissue.
  • the mixed material forming the bur has a hardness less than that of healthy mineralised tissue but greater than that of infected, necrotic or otherwise non-viable mineralised tissue, whereby the bur abrades away the nonviable mineralised tissue, but itself abrades against the healthy mineralised tissue when in use.
  • a "self-limiting" effect is obtained which allows the bur to excavate infected or other non-viable tissue but not to abrade healthy tissue.
  • the bur is a dental bur.
  • the mixed material forming the bur has a hardness less than that of healthy dentine but greater than that of infected dentine, whereby the bur is able to selectively cut the infected dentine.
  • the mixed material forming the bur has a hardness in the range 14 to 21 KHN.
  • the remineralisation agent is conveniently a bioactive glass, whereas in other embodiments the remineralisation agent may be a biomimetic apatite.
  • the biocompatible substrate is a biocompatible polymer material. This acts as a carrier matrix for the remineralisation agent, and is able to be worn away against healthy tissue without causing any side effects.
  • the bur comprises an inner core formed from the mixed material, surrounded by a sacrificial outer layer having a greater hardness. The sacrificial harder layer can help a user to penetrate into infected tissue to be treated, through potentially harder healthy tissue.
  • the sacrificial outer layer comprises a coating grit formed from a remineralisation agent such as bioactive glass particles.
  • Another aspect of the invention comprises a method for the application of a remineralising agent to mineralised tissue, comprising driving a bur formed from a mixed material including a biocompatible substrate having a bioactive remineralisation agent carried therein against mineralised tissue, the mixed material of the bur having a hardness less than the mineralised tissue whereby the bur wears against the mineralised tissue to thereby deposit the bioactive remineralisation agent onto the surface of the mineralised tissue.
  • Figure 1 is a diagram of a dental bur in accordance with an embodiment of the invention.
  • Figure 2 is a photograph of a prototype dental bur in accordance with the embodiment
  • Figure 3 is a photograph of part of a production process of the dental bur of the embodiment
  • Figure 4 is a graph illustrating the Knoop Hardness Number (KHN ) of the dental bur in dependence on the percentage of remineralisation agent that is included therein;
  • Figure 5 is a photograph of a reference dentine exhibiting caries prior to removal using the dental bur of the embodiment;
  • Figure 6 is a photograph of the reference dentine after caries removal using the dental bur of the embodiment
  • Figure 7 is a flow diagram of the method of use of the dental bur of the embodiment.
  • Figure 8 is a flow diagram of a method of manufacture of the dental bur of the embodiment. Overview of Embodiments
  • Embodiments of the invention provide a dental bur that is formed of a material that is formulated with a bioactive remineralisation agent contained therein that will leave a dentine surface that promotes remineralisation of the partially decayed dentine. This remineralisation seals the dentine and filling interface, protecting the dental pulp.
  • Example remineralisation agents that may be used include bioactive glasses, such as, for example, bioactive glass formulations 45S5, 58S, 70S30C, and S53P4 (which are already per se known in the art), or any other materials capable of causing mineralisation within a suitable environment, such as many other mineral salts related to hydroxyapatite.
  • the dental bur is a self-limiting dental bur that allows the dentist to selectively remove decayed enamel and then transition to removal of only decayed dentine, reducing the problems associated with dental fillings such as overcutting of dentine and pulpal injury leading to root canal therapy.
  • Such selective cutting embodiments of the invention do not require a full direct line of access (being able to cut undercuts of infected tissue) and thus will maximise the amount of healthy tooth tissue left after excavation, and also allow pain free treatment in the absence of local anaesthetic injections.
  • embodiments of the invention comprise a bur containing remineralisation agents such as bioactive glass (BAG) particles embedded into or attached to a polymer, resulting in an instrument with appropriate hardness for selective caries removal.
  • BAG bioactive glass
  • the bur conserves tooth structure, reduces the long- term cost of restoration, and helps reduce unpleasant, technically challenging and expensive root canal therapy.
  • Embedding remineralising bioactive materials within the tooth cavity surface using a bur that supplies bioactive minerals to a demineralised tooth surface whilst excavating decay will greatly enhance operative dentistry.
  • the bur uses a sacrificial material to gently abrade only decayed enamel and dentine, but will also promote biomimetic repair-remineralisation to increase restoration longevity and so cut future costs.
  • the bur will be a slow speed dental bur with an abrading head incorporating bioactive glass particles both imbedded into the sacrificial material as well as being utilized as a surface coating.
  • the coating grit may be slightly harder than demineralized enamel and the core fillers equivalent to the softer caries-infected dentine, with appropriate mechanical properties to remove only diseased enamel and dentine. With such an arrangement the surface abrades as the bur is being used, thereby impregnating the tooth cavity surface with bioactive minerals.
  • bioactive glass is used, and in particular in one embodiment the bioactive glass of choice is 45S5, which has quantified levels of antimicrobial activity which can be used to 'depot' load the surface of the excavated tissue, thereby minimising disease recurrence, in conjunction with a high pH environment to prevent disease progression.
  • the bur will conserve tooth structure and can cut undercuts, preventing loss of healthy tooth structure and making the filling more retentive.
  • the bioactive glass of choice (45S5) has quantified levels of antimicrobial activity which can be used to 'depot' load the surface of the excavated tissue, thereby minimising disease recurrence.
  • the bur may be used for other, non-dental, applications, such as operating to remove infected or necrotic bone, in vivo, whilst also depositing bioactive particles to promote healthy bone re-growth. Further features and advantages will be apparent from the following detailed description.
  • the bur comprises a generally cylindrical body portion 10 mounted on a mandrel 16 for connection to a conventional dental handpiece.
  • the cylindrical body portion 10 comprises a central cylindrical core 14 formed from an extruded composite glass-polymer mixture material (see Figure 3) having a Knoop hardness (KHN)) selected for caries removal, and which hardness is adjustable by changing the concentration of bioactive glass particles.
  • KHN Knoop hardness
  • Surrounding the core 14 is a thin annular shaped portion again formed of polymer but with a higher percentage of bioactive glass particles therein, so as to provide an outer surface of bioactive glass particles in the form of a coating grit.
  • This coating grit layer 12 is harder than the core 14, and should be slightly harder than demineralized enamel, and in use acts as a sacrificial relatively high abrasion layer to remove any decayed enamel or peripheral dentine prior to allowing the underlying softer layers of the bur in the core 14 to excavate the residual infected tissue in a self-limiting manner. That is, in removing the decayed enamel and peripheral dentine to expose the caries, the coating grit layer is sacrificed to allow the softer core 14 to be exposed to then excavate the infected caries material, but without excavating surrounding healthy material.
  • FIG. 4 illustrates that the hardness of the glass-polymer mixture in the core 14 can be set by varying the percentage of bioactive glass particles in the mixture, and that Knoop hardness (KHN) values of between approximately 14.5 and 21 are obtained by varying the percentage of bioactive glass particles in the mixture between 0 and 30%.
  • KHN Knoop hardness
  • the relationship between KHN and the percentage of bioactive glass is non-linear, with a greater increase in KHN per unit percentage increase between 20 and 30 % bioactive glass than when the concentration of bioactive glass in the mixture is less than 20%.
  • the core will not act to abrade and remove healthy dentine when in use, but on the contrary will itself in use wear against the healthy dentine, and thereby deposit on the healthy dentine as it wears against the particles of bioactive glass contained within the core. These particles of bioactive glass then act as a remineralisation agent to promote repair of the dentine surface.
  • 45S5 represents the prototypical bioactive glass, being comprised of 45% Si02, 24.5% Na20, 24.5% CaO and 6% P205.
  • various other bioactive glass compositions may be used, and non-limiting example compositions of bioactive glasses that may be used with embodiments of the invention range from 30-70 Si mol % silicate, 5-20% P2 05, 20-58 mol % CaO, 0- 0-30 mol % Na2 O and 0-5% Fluoride.
  • other materials that may be used as the remineralisation agent include biomimetic apatites, including hydroxyapatite, tricalcium phosphate and dicalcium phosphates, by way of example.
  • a mixture of polymer and remineralisation agent such as the bioactive glasses mentioned earlier is prepared (s.8.2), with the desired concentration of bioactive glass particles to give the desired KHN values.
  • a concentration of between 10 and 30 % bioactive glass particles to polymer should be sufficient, although different concentrations can be used if desired, the upper concentration limit being that the hardness of the resulting mixture should be less than the hardness of healthy dentine material, and the lower concentration limit being that the hardness of the resulting mixture should be greater than the hardness of infected dentine material.
  • the polymer and remineralisation agent mixture is then extruded, for example onto a rotating bobbin if required, to form a simple rounded bur shape (s.8.4).
  • a second polymer/remineralisation agent mixture can be prepared, with greater concentrations of remineralisation agent. This second mixture is then attached to the outer surface of the bobbin which forms the inner core 14 to give the completed bur 10.
  • a crude cutting edge to selectively abrade caries dentine may be formed on the extruded bobbin, although this is not essential.
  • the completed bur 10 is then mounted onto a drill mandrel to allow it to be connected to a dental handpiece (s.8.6).
  • Figures 5 and 6 show an example infected tooth exhibiting caries before and after treatment with the self-limiting bur of the present embodiment. Comparison of these two photographs show that the present embodiment is well able to remove all signs of caries without removing the surrounding healthy dentine.
  • the core is of a hardness that it is able to remove infected dentine, but is softer than healthy dentine and hence it wears away against such, depositing itself thereon as it does so, and hence impregnating the healthy dentine surface with bioactive remineralisation particles as it does so.
  • Figure 7 illustrates such a method of use in more detail.
  • bioactive remineralisation agents in the form of the bioactive glass particles onto the excavated surface of the healthy dentine (s.7.10). These remineralisation agents then act to promote sealing of the dentine surface, as described previously.
  • the embodiments of the invention therefore act to provide a highly effective delivery mechanism of bioactive remineralisation agents to the healthy dentine surface of the tooth in the same procedure and at the same time as the caries removal takes place.
  • an outer metal coating e.g. plasma sprayed Titanium is provided on the bur, either as an alternative to or in addition to the outer layer 12.
  • the metal-sprayed coating layer will still be sacrificial (as per the embodiment above) thus exposing the underlying bioactive glass core that will aid in remineralisation and antimicrobial properties.
  • a bur as provided by the present embodiments need not be limited to dental use, but can be used for other orthopaedic applications and implant dentistry.
  • the tribological deposition of bioactive particles as achieved by the above described dental embodiments can be obtained by matching the hardness of the bur to the mineralised tissue being operated upon e.g.

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  • Health & Medical Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Dentistry (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Dental Preparations (AREA)

Abstract

L'invention concerne une fraise (10) dans laquelle sont incorporés des agents de reminéralisation bioactifs qui sont libérés sur la surface d'un tissu minéralisé qui est traité à mesure que la fraise est utilisée. En particulier, la fraise se présente de préférence sous la forme d'une fraise dentaire auto-limitative constituée d'un matériau ayant une dureté qui est supérieure à celle de la matière dentaire cariée devant être éliminée par la fraise, mais plus molle que celle d'un matériau de dentine sain, de sorte que la fraise s'érode contre le matériau de dentine sain lors de l'utilisation tout en pouvant s'enfoncer dans la matière cariée et éliminer cette dernière. Les agents de reminéralisation bioactifs sont de préférence des particules de verre bioactif incorporées dans un matériau sacrificiel, le matériau sacrificiel étant par exemple un polymère ayant une dureté de la plage requise pour l'élimination sélective des caries. Selon certains modes de réalisation, le verre bioactif est par exemple du 45S5, bien que d'autres compositions telles que le 58S, le 70S30C et le S53P4 puissent être utilisées.
PCT/GB2018/052303 2017-08-16 2018-08-14 Fraise à matériaux bioactifs Ceased WO2019034861A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB1713166.5A GB201713166D0 (en) 2017-08-16 2017-08-16 Bur with bioactive materials
GB1713166.5 2017-08-16

Publications (1)

Publication Number Publication Date
WO2019034861A1 true WO2019034861A1 (fr) 2019-02-21

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WO (1) WO2019034861A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021038438A1 (fr) * 2019-08-28 2021-03-04 3M Innovative Properties Company Fraise dentaire, son procédé de fabrication, et flux de données

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6093084A (en) * 1988-08-01 2000-07-25 Dentsply Research & Development Corp. Device and method for dispensing polymerizable compositions
WO2009042110A1 (fr) * 2007-09-21 2009-04-02 New York University School Of Medicine Structures à base de zircone de qualité bioactive

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6093084A (en) * 1988-08-01 2000-07-25 Dentsply Research & Development Corp. Device and method for dispensing polymerizable compositions
WO2009042110A1 (fr) * 2007-09-21 2009-04-02 New York University School Of Medicine Structures à base de zircone de qualité bioactive

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021038438A1 (fr) * 2019-08-28 2021-03-04 3M Innovative Properties Company Fraise dentaire, son procédé de fabrication, et flux de données

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GB201713166D0 (en) 2017-09-27

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