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Předmět: Autor: Poznámky: Courseware Current adhesives and their development. Enamel and dentine adhesion principles. Use possibility, working procedure.

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Presentation on theme: "Předmět: Autor: Poznámky: Courseware Current adhesives and their development. Enamel and dentine adhesion principles. Use possibility, working procedure."— Presentation transcript:

1 Předmět: Autor: Poznámky: Courseware Current adhesives and their development. Enamel and dentine adhesion principles. Use possibility, working procedure. Common mistakes and their consequences in the clinical praxis. Stomatolog Julia Morozova, Ph.D. Operative Dentistry 1 ST1/ZAA35

2 Basic mechanism of adhesion The primary aim of dental adhesives is to provide retention to composite fillings or composite cements Twofold adhesion Co-polymerization of residual double bonds (-C=C-) in the oxygen inhibition layer Exchange process – replacement of inorganic components from hard tissue – by resin monomers micromechanically interlocked

3 Enamel structure The hardest tissue of the human body (96 % of mineral components) Prisms

4 Enamel bonding Developed by Buonocore (1955) Etching by 32–37% H 3 PO 4 : – interprismatic and intraprismatic strucure will be disrupted – creates micropores (5 – 50 microns deep) – increases surface energy – increases wettability 3 types of etching: Central intraprismatic Peripheral interprismatic Combined

5 Adhesion onto enamel Enamel adhesive (bond), strength >20 MPa It forms the interlayer allowing the resin adhesion onto tne enamel Contain: unfilled or partially filled composite resin with smaller molecules of monomers

6 Dentine structure Live tissue with methabolism Dentine composition Hydrophilic tissue (10–30 % H 2 O) Dentinal tubules with odontoblasts’ process and tubular liquid Changes in dentine structure Smear layer Dentinal wetness

7 Adhesion onto dentine Presence of smear layer Hydrophilic tissue Etching → dissolving of smear layer and mineral components → opening of dentinal tubules’ entrances, denaturation of surface proteins → baring of collagenous fibers’ net Primer (has influence on hydrophilic properties of the dentine and accents its hydrophobic properties)- hybridization of the dentine

8 Requirements for adhesives High strength and permanence of adhesion onto dentine and enamel Biocompatibility for tooth tissues, organismus in generally and personnel Perfect marginal integrity without risk of microleakage, secondary caries or marginal percolation Perfect and permanent contact with dentine and closure of dentinal tubules Suitable for moist and dry environments Fluoride-releasing Easy procedure and application Sufficient long expiration time

9 Classification of adhesives According to chemical composition (type of solvent) According to influence on smear layer According to generation criterion

10 Chemical composition of adhesives Monomers of composite resin Solvents Initiators (photo- or self-curing) Inhibitors or stabilizers Anorganic filler (not allways) Specific components (polyalkenoic copolymer, glutaraldehyd, antibacterial components, fluorides, dyes, acids)

11 Monomers of resin composite Methacrylic acid (MA) Methylmetacrylate (MMA) Hydroxyethyl metacrylate (HEMA) 4-MET 4-AETA 10-MDP MAC-10 Phenyl-P Di-HEMA-phosphate and HEMA-phosphate Di-methacrylates (BisGMA (Bowen‘s monomer), UDMA, TEGDMA) (Meth)acrylamides

12 Solvents Water Ethanol Acetone

13 Camphorquinone/co- initiator system 1-phenyl-1,2 propanedione (PPD) Acylphosphine oxides Benzoylperoxide (BPO) in conjunction with tertiary amine Tri-n-butyl borane (TBB) Initiator systems Photo-initiatorsChemical initiators

14 Inhibitors Antioxidants- scavenge free radicals originating from prematurely reacted initiators Prevent spontaneous initiation and propagation of the free-radical polymerization reaction Promote shelf life Butylated hydroxytoluene (butylhydroxytoluene BHT), monomethyl ether hydroquinone (MEHQ)

15 1st generation 1950–1970s NPG-GMA (N-phenylglycin-glycidyl methacrylate) Strength of adhesion: 1–3 MPa S.S. White’s Cervident

16 2nd generation Late 1970s Combination of Bis GMA (bisphenol A and glycidyl methacrylate) and HEMA (hydroxyethyl methacrylate) Strength of adhesion: 4.5–6 MPa 3 tendencies: Etching agent (25% citric acid - Dentin Bonding System, Den-Mat) Adhesive with phosphate aether (Bondite, Sybron/Kerr; Scotchbond TM, 3M ESPE; Prisma Universal, Dentsply Caulk) Adhesive with polyurethan polymer (Dentin-Adhesit, Ivoclar Vivadent )

17 3rd generation Late 1980s 3 parts: Conditioner: weak organic acid (maleic acid) or anorganic acids in low concentration (phosphoric or nitric acid) Primer: bifunctional monomer dissolved in solvent (acetone or ethanol) Bifunctional monomer has one hydrophilic end (it is adapted onto the dentine) and another one is hydrophobic (it is adapted onto composite resin); HEMA, 4-META, NPG, NSMA Adhesive: non-filled or low-filled resin, that connects with primer and forms hybrid layer (1–5 µm), that penetrates into dentinal tubules and forms composite tags Strength of adhesion: 12–15 MPa Scotchbond TM Multi-Purpose (conditioner maleic acid); Scotchbond TM Multi-Purpose Plus (conditioner phosphoric acid, 1994) (3 M ESPE) XR Bonding System (Sybron/Kerr), Gluma (Heraeus Kulzer), Tenure (Den-Mat), Syntac Classic (Ivoclar Vivadent)

18 4th generation Start of revolution in aesthetic dentistry (early 1990s) Complet removing of smear layer Total etching of enamel and dentine („total-etch“) The dentine surface after gentle drying must be wet to prevent the collapse of collagen fibres after the etching („wet bonding“) Technique sensitive Gold standard OptiBond FL (Sybron/Kerr); All-Bond (Bisco, Inc.)

19 5th generation Mid 1990s „One bottle systems“ (primer and adhesive are in one bottle) Two steps technique: etching and adhesive application (Etch & Rinse) OptiBond Solo (Sybron/Kerr), Gluma One Bond (Heraeus Kulzer), Single Bond (3M ESPE)

20 6th generation Early 2000s „Self-etching“: acidic primer Etching is not required→ decreasing of postoperative sensitivity Strength of adhesion: 18–23 MPa All-Bond SE (Bisco Inc.); ClearfilTM SE Bond (Kuraray); AdheSe (Ivoclar Vivadent), Nano-Bond (Pentron)

21 7th generation 2002–2003 One-bottle self-etching systems One step system OptiBond All-In-One (Sybron/Kerr); Xeno IV (Dentsply Caulk), ClearfilTM S3Bond (Kuraray), iBond (Heraeus Kulzer)

22 Currently available generations Fourth Generation – Three-step Etch & Rinse Fifth Generation – Two-step Etch & Rinse Sixth Generation – Two-step Self-Etch – One-step Self-Etch mix Seventh Generation – One-step Self-Etch no mix

23 Pros/Cons of Etch & Rinse (Col Kraig S. Vandewalle Enamel and Dentin Adhesives) Separate acid etch – good enamel etch pattern Potential to over-etch dentine – except sclerotic dentin Post-conditioning rinse is necessary – sensitive to level of dentine wetness Multiple long-term clinical studies

24 Acetone and ethanol based primers – displace remaining water – carry monomers into collagen – gently air-dried – leaving monomers behind Examples – One-Step – Prime & Bond NT Overwet phenomen – too moist (too much water) – not completely displaced Phase separation – blister and globule formation Disadvantages: Cannot check for enamel “frosted” etch Technique sensitivity – not too wet or too dry Solvents evaporate from bottle – may reduce monomer penetration Wet bonding (Col Kraig S. Vandewalle Enamel and Dentin Adhesives)

25 Dry bonding (Col Kraig S. Vandewalle Enamel and Dentin Adhesives) Water-based primers – effective on wet or dry dentine – self-rewetting effect – re-expand collapsed collagen Permits check of “frosted” enamel Examples – Scotchbond Multi-Purpose – Optibond

26 Pros/Cons of Self-Etch (Col Kraig S. Vandewalle Enamel and Dentin Adhesives) Good dentine conditioning – simultaneous infiltration – depth of demineralization Possible reduction in post-operative sensitivity No post-etching rinse – not sensitive to level of dentine wetness Reduced application time Relatively lower bond strengths

27 Unit Dose (Col Kraig S. Vandewalle Enamel and Dentin Adhesives) Improved infection control Simple working procedure Minimizes loss of volatile components over time Higher cost Examples – Optibond Solo Plus – Excite – Prime and Bond NT – Prompt L-Pop

28 Polymerization shrinkage and polymerization stress 3.5–4 % They are affected by fast photopolymerization Factors: C-factor (size and geometry of cavity) Application technique Light intensity and direction during the photopolymerization Viscosity and elastic modulus of composite resin, value of polymerization shrinkage Hydroscopic and thermal expansion of resin composite Consequences: bad marginal integrity, microleakage between filling and cavity, filling percolation, secondary caries, postoperative sensitivity, cusp break

29 C-factor Ratio of bonded to unbonded surfaces of cavity Scientific Compendium SDR, 2011

30 C-factor of different classes Karthic K., Sivakumar K., Geetha Priya P.R., Shankar S.: Polymerization Shrinkage of Composites-A Review. JIADS, vol. 2, issue 2, April-June, 2001, pp. 32–36

31 Incremental technique minimizing C-factor

32 Common mistakes Non-adequate etching Insufficient drying or overdrying of dentine Too thick or too thin layer of adhesive Insufficient polymerization Non-adequate material adaption onto the cavity walls

33 The influence of resins on the general health Contact allergy of personnel on adhesives and resins Cytotoxic and endocrine-disruptive effects of non- polymerated monomers (esp. dimethacrylates)

34 Thank you for attention

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