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Orthodontic resins /certified fixed orthodontic courses by Indian dental academy
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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Orthodontic resins /certified fixed orthodontic courses by Indian dental academy Orthodontic resins /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

  • ORTHODONTIC RESINS INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • • • • • • • • • • • • • • • • • • • • CONTENTS INTRODUCTION TYPES OF ADHESIVES 1st -5th GENERATION DUAL CURE RESIN THERMOCURED RESIN REVIEW OF ARTICLES RECENT ADVANCES SEP CYANOACRYLATE FLUORIDE RELEASING ADHESIVE ADHESION BOOSTER HYDROPHILIC PRIMERS APC REVIEW OF ARTICLES GLASS IONOMER CEMENT DYRACT REVIEW OF ARTICLES ADHESIVES THAT BOND TO CROWNS AND RESTORATIONS • • • • DEGRADATION OF POLYMER LEACHING CYTOTOXICITY www.indiandentalacademy.com CONCLUSION
  • • The major current category of orthodontic adhesive systems is based upon resin composites. They consist of three main components 1. An organic matrix 2. Filler powdered ceramic such as barium aluminoborate silica glass and 3.Coupling agent. • Organic Matrix Monomer Components • The organic matrix is formed by polymerization of an aromatic or urethane dimethacrylate. It is the chemically active component. Initially a fluid monomer but is converted into a rigid polymer by a radical addition reaction. Bis-GMA is commonly used monomer. It is derived from the reaction of Bisphenol –A & glycidyl methacrylate. Its molecular weight is higher than methyl methacrylate, which helps in reducing polymerization shrinkage. Bis – GMA monomer is highly viscous fluid, the addition of even a small amount of filler would produce stiffness that is excessive for clinical use. www.indiandentalacademy.com
  • • • • • • • • • • • Properties: Large molecular size and Large chemical structure, Advantage : It is superior to many monomers of lower molecular mass by virtue of -Lower volatility, -Lower polymerization shrinkage ------ more rapid hardening, and production of a stronger and stiffer resin. Since Bis-GMA is highly viscous, viscosity is reduced by adding monomers, like diethylene glycol dimethacrylate (DEGMA) and Triethylene glycol dimethacrylate (TEGDMA) . A typical formulation is 75% Bis-GMA and 25 % TEGDMA Another approach is the synthesis of Bis-EMA, a Bis-GMA analogue that does not have the hydroxyl group in the structure. Less sensitive to water than Bis – GMA. www.indiandentalacademy.com
  • • Polymerization Activation • Four types of activation of free radicals are used in the polymerization of the unsatu-rated methacrylate groups of the resin composites. Activation of free radicals is by: • Self cure (SC) – Two phase – One phase ( no mix ) • Light cure (CC) • Dual cure • Heat cure www.indiandentalacademy.com
  • • Extent of Reaction: Degree of Conversion (DC) • The DC of resin composite materials is the extent to which carbon double bonds (C = C) of the monomer are converted into carbon single bonds (C-C) to form polymers during the polymerization reaction. C = C  C-C • DC affects the physical properties of composites. • Inspite of extensive cross-linking on polymerization, there is considerable residual unsaturation in the final product ( 25% to 45 % ) • This ranges from 25 % to 45 %, or equivalently the degree of conversion (DC) ranging from 55% to 75%. . www.indiandentalacademy.com
  • • • • • • Unpolymerized resin has deleterious effects on: 1. The mechanical properties ----- acts as plasticizer 2. Dimensional stability of the restoration. 3. Biocompatibility.----- monomer leach in oral environment What happens to uncured resin? 1. The unconverted methacrylate group resides in the polymer network, either residual monomer or (a majority) as pendant side chains (PSC). 2. A further possibility is a cyclization reaction. The residual monomer molecules function as plasticizing agents that can reduce the properties of polymer network and monomers leach from the composite into the oral environment. Hence it is desirable to increase DC in order to produce stiffer and more durable resins although, for a given composite shrinkage increases with DC. www.indiandentalacademy.com
  • Polymerization Shrinkage • Polymerization shrinkage is partially explained by a volumetric decrease arising from the con-version of van der Waals bonds into covalent bonds. • There is an intrinsic shrinkage associated with resin composites and that the time dependence of this shrinkage reflects the progress of the polymerization. www.indiandentalacademy.com
  • • Dispersed Phase Components • The filler or reinforcing ceramic phase in the early materials was a ceramic oxide, such as silica or alumina, or a glass. A high proportion of ceramic may also reduce polymerization shrinkage. Filler selection: • 1. To reduce the thermal dimensional change of the resin composite to a value matching that of tooth structure,e.g. fillers such as lithium aluminum silicate. • 2. The need for a good refractive index match with the organic monomer to secure adequate translucence for aesthetic appearance. Radiopaque glasses containing elements such as barium, strontium, and zinc can be used. • 3. Large volume of hard filler particles has been incorporated based on the concept of attainment of high compressive strength and stiffness and on evidence that abrasion resis-tance improves as filler content increases and that fine fillers wear more than coarse particles. www.indiandentalacademy.com
  • Type of adhesives: They are classified as A. Based on the basic bonding system type 1. Acrylic base systems- Poly (methyl methacrylate) systems 2. Diacrylate systemsBis-GMA systems 3. Glass ionomer systems- 1. Chemical cured 2. Light cured 3. Dual cured B. Based on fluoride content 1. Fluoride releasing systems 2. Non-fluoride releasing systems C. Based on the filler content Lowly filled bonding systems Highly filled bonding systems. D. Based on the curing systems 1. Self curing system 2. Light curing system 3. Dual curing system 4. Heat curing system www.indiandentalacademy.com
  • First Generation Bonding Adhesives This generation included unfilled acrylic resins and epoxy resins. The first bonding adhesives used in orthodontics was essential unfilled poly (methyl methacrylate) anterior dental restoratives. The unfilled acrylic resins exist as powder - liquid or paste/paste. Powder Contains 1. Poly (Methyl methacrylate). Poly (methyl methacrylate) is a transparent resin of remarkable clarity it transmits light in the ultraviolet range to a wavelength of 250 nm 2. Initiator: Benzoyl peroxide (0.3 to 3%) To start an addition polymerization process, free radicals must be present. Free radicals can be generated by activation of monomer molecules with UV light, visible light, heat or energy transfer. Initiation period is the time during which molecules of the initiator become activated forming free radicals that interact with the monomer molecules. www.indiandentalacademy.com
  • Liquid : • Methyl methacrylate monomer The liquid monomer methyl methacrylate is mixed with the polymer. Methyl methacrylate is a clear, transparent liquid at room temperature. • • Cross-linking agent -- Ethylene dimethacrylate (5% or more) Inhibitor: (Monomethyl ether of hydroquinone: (0.006%) To minimize or prevent spontaneous polymerization of monomers, inhibitors are added to the resin systems. These inhibitors have a strong reactivity potential with free radicals. If a free radical is formed, the inhibitor reacts with it and controls the reaction. www.indiandentalacademy.com
  • Unfilled bonding adhesives cause less enamel damage and are indicated for bonding of acrylic orthodontic appliances to enamel. Disadvantages of Unfilled Acrylic Resins : Low hardness and strength High co-efficient of thermal expansion Lack of adhesion to tooth structure High polymerization shrinkage. E.g. of Unfilled Resins: Bracket Bond, Genie www.indiandentalacademy.com
  • Epoxy Resins The resins, which include a catalyst, are used in dental composites, pit & fissure sealants and orthodontic bonding resins. With so many different application, a large number of dental products that use epoxy resins were developed, especially Bis-GMA Bis-GMA is an aromatic ester of a dimethacrylate, synthesized from an epoxy resin (Ethylene glycol of Bisphenol A) and methyl methacrylate. Disadvantages: Lack of color stability Water sorption Patient sensitivity Report by Athas and associates suggest that Endur M produced carcinogenic effects. Endur M is now currently replaced with Endur, which shows no carcinogenic effects on ingestion. www.indiandentalacademy.com
  • Second Generation These are UV light activated resins. The second-generation materials provided greater bond strengths than had existed previously. The major disadvantage were UV light itself. which even with the best control was a moderate hazard and an indirect technique with a tray carrier was needed to position the brackets. This interfered with access of the UV light to the resin beneath the brackets and made cleaning difficult. It used Bowen's Hybrid molecule, similar to Epoxy resin, but functional reactive groups are acrylic. It consists of • Bisphenol glycidyl methacrylate • Esters of alkyl benzoin were incorporated to facilitate UV activation. Advantages as compared to 1st generation : • Higher bond strengths when compared to first generation. • Low polymerization shrinkage • Greater hardness • Low water absorption. www.indiandentalacademy.com Disadvantages are radiation hazards and limited depth of cure
  • • Third Generation (Two paste system) • Representative product Concise (3M) • First to be tried by orthodontists in the early days of bonding. Their application involves mixing of the paste and liquid components. • Compared with unfilled resins, the filled resins have greatly improved thermal expansion qualities. • Silane was used to coat filler particles that could bond chemically to the resin. www.indiandentalacademy.com
  • The major constituents are • Resin Matrix - Bis-GMA or Urethane Dimethacrylate (UEDMA)/or Triethylene glycol Dimethacrylate (TEGDMA). • Filler Particles - are produced by grinding or milling quartz or glasses to produce particles ranging in size from 0.1 to 100 / microns. Silica particle (0.04 /lm) are obtained by pyrolytic process. Depending on size of particle they are classified as: Macro filled (10 to 30 microns) e.g. Concise. Micro filled (0.2 to 0.3 microns) e.g. Endure, dynabond. • Coupling agents: The bond between the two phases of composite is provided by the coupling agent i.e., between resin matrix and filler particles. Titanates and Zirconates and organosilanes such as gamma -methacryloxypropyltrimethoxy silane is most commonly used. www.indiandentalacademy.com
  • Activator-Initiator system Third generation is two paste systems and activated by autopolvmerization. • One paste contains benzoyl peroxide initiator • Other tertiary amine activator - (N, N-dimethyl-P-toluidine). 1- 2 % BP (benzoyl peroxide) in the monomer portion as a free radical initiator. The activator in the other paste for these materials has usually been a tertiary amine. Most commonly di-hydroxyethyl-p-toluidine (DHEPT), which gives better color stability than the traditional dimethyl-Ptoluidine (DMPT). • The activator acts as an accelerator so that, on mixing, the benzoyl peroxide fragments into free radicals at room temperature, thus initiating polymerization. Inhibitor • To prevent spontaneous polymerization of monomers. Inhibitor reacts with free radicals until they are depleted. E.g. -7 butylated hydroxytoluene (0.01 wt %). www.indiandentalacademy.com
  • Disadvantages: Clinical handling 1. The manipulative process is problematic, relatively timeconsuming, and cumbersome. 2. Mixing of the two components introduces potentially critical defects such as surface porosity and air voids in the bulk material, owing to the prolonged exposure to air and the inevitable entrapment of air bubbles. 3.High amount of monomer leaching. Studies have shown that photo cured composites, intentionally mixed as if they were chemically cured materials, also demonstrated severely porous surfaces and voids in the bulk materials. Low degree of cure (DC-55%) and disproportionately high amount of monomer leaching is attributed to the mixing process and to the detrimental effect of air entrapment on the carbon double- bond conversion in the vicinity of voids. www.indiandentalacademy.com
  • 1 to 1 bonding system It is one of the most popular and dependable 2-paste selfcure adhesive systems available for direct or indirect bonding of metal, Ceramaflex ceramic or plastic attachment. Extra small quartz particles allow a smooth mix without sticking to spatula. Simple one to one mixing ratio of both the sealant resins and bonding pastes make 1 to 1 easy to use. It eliminates bracket drift and reduces decalcification due to the "feather edge" on the tooth surface. It is particularly recommended when close adaptation between tooth surfaces and bonding pads is not possible as is often the case with lingual bonding of brackets and retainers. Working Time = 1 /2 minutes It can be increased by cooling the paste and/or cooling the slab. www.indiandentalacademy.com
  • FOURTH GENERATION No-mix adhesives They were intended to minimize the mixing induced defects and to reduce the steps With these "no-mix" materials, the composite can be placed on the tooth surface in unpolymerized form, while the polymerization catalyst is placed on the back of the brackets. Contact between the bracket and tooth with the intervening adhesive permits inter diffusion of agents such as benzoyl peroxide (initiator) and amine ( activator) from the respective components. Inhomogeneous polymerization pattern due to sandwich technique involved in diffusion of liquid component into paste during application. Enamel and bracket sides of adhesive are more polymerized relative to middle zones When the tray carrying the brackets is placed against the tooth surface, the resin immediately beneath the bracket is activated and polymerizes, but excess can be scaled away around the margins of the brackets. www.indiandentalacademy.com
  • Disadvantages 1. Artun and Zachrisson states that, some components of the fluid reagents of no-mix systems, and of unreacted monomer have recently been suspected of having a mutagenic potential. 2. The 'no-mix' adhesive according to them does not save time as the archwire cannot be engaged with minimum of delay. E.g.Monolok Unite. 'Right-on' No mix Adhesive Right-on no mix adhesive is the most advanced self- cure bonding system available. It provides superior bond strength drift-proof bracket placement and 2-year shelf life without refrigeration. The adhesive paste is conveniently preloaded in syringes or disposable syringes to simplify bonding produces. Archwires can be placed after 7 minutes after the last bond.’ Right-on' bonds metal, Ceramaflex ceramic or plastic brackets to either etched enamel or acrylic crowns. It may be used for indirect bonding www.indiandentalacademy.com
  • FIFTH GENERATION Compared with UV light, visible light has deeper curing capabilities, more effective through enamel and does not diminish with time or with intensity of the light source. The light cured resin is a single paste system that consists of a ketone and an amine as initiators. The ketone, camphoroquinone is sensitive to blue light at 470 nm wavelength which catalyses the polymerization reaction. VLC resin usually employs free radical initiators such as camphoroquinone (CQ) and an amine reducing agent such as N, N-di-methyl-amino-ethyl methacrylate (DMAEMA). The radicalized ketone (CQ) alone may initiate the photo polymerization. A reducing agent is generally added to light-cured composites for the following reason. The amine radical is responsible for initiating the polymerization and is more efficient than the radical formed from the ketone. These intensified radicals can thus significantly improve the degree of cure. The concentration of CQ photo sensitizer is in the range 0.17-1.03 mass% of the resin phase and that of DMAEMA reducing agent is 0.86 -1.39 mass%. The combined photosensitizer/reducing agent complex has an extended absorption band within the visible light (VL) spectrum. www.indiandentalacademy.com
  • • Tavas and Watts showed that sufficient light may be transilluminated by the teeth to effect adequate photo polymerization of the material. In the case of translucent ceramic brackets, light-curing is straightforward. • Tawas and Watts developed the transillumination technique to bond metal brackets onto teeth in vitro with visible light-cured composite • Results from laboratory investigations have suggested that visible light-cured composite have similar physical properties to chemically cured resins. • Read stated that the entire adhesive under the bracket is polymerized after initial exposure to visible light and that a force can be immediately placed on the bracket after curing. • The disadvantages of light-cured resin are associated with incomplete polymerization beneath the surface and a limited depth of cure. Doubling the exposure time and exposure through tooth substance increased the cured depth. www.indiandentalacademy.com
  • Reliance Quick Cure Orthodontic Paste Light curing of a metal bracket in only 6 seconds with a conventional curing light is possible. Unique chemistry provides a broader area of sensitivity to blue light for a faster and more complete cure. Ideal viscosity, no bracket floatation, easy cleaning, no stringing. Quick cure paste can be used with light bond, assure or any light cured sealant. Transbond XT light cure adhesive Transbond XT is currently distributed with instructions to cure both the mesial and distal or incisal and gingival surfaces of metal orthodontic brackets for 10 seconds each, for a total of 20 seconds per bracket followed by immediate archwire insertion. Advantages Extended working time allows precise bracket placement. Immediate bond strength, allowing archwire to be placed immediately following cure. It saves time for rebonds. Efficient bonding of ceramic and metal brackets. Excellent handling properties like -No bracket drift &easy flash clean www.indiandentalacademy.com up.
  • • The disadvantage of UV-light like 1 minute of curing per millimeter of thickness led to development of visible Light cured adhesives. The longer curing time (40 seconds) of these lead to the introduction of Argon Lasers. They cure filled resins in 10 seconds and unfilled resins in 5 seconds, at a wavelength of 488 nanometer. More recently Xenon arc light units have been introduced for rapid light curing. • Visible Light cure emit light at 480 nm, but the energy is emitted over a much broader range. Light from the Argon laser is collimated, which results in more consistent power density over distance. The power density of light Cure decreases dramatically with distance due to divergence of light from the source. Visible Light curing units uses bulbs, reflectors and filter which can degrade and decrease curing efficiency. • Nazir Lalani et al (Angle2000) found that 5 seconds was adequate for bonding metal brackets. Increasing the time did not increase bond strength significantly. www.indiandentalacademy.com
  • Dual cure Resins These resins are both light activated and chemically cured. Thus they can be cured completely by using a light source or by the catalyst and base reaction of the material. These resins originally were applied to composite buildups and to cementing of laminate veneers where depth of cure is essential. Initiation is achieved through exposure to light. Reaction proceeds following a chemically-cured pattern Combines disadvantages of handling of both light-cured and chemically cured materials. The most time consuming applications Increased degree of cure and bond strength, but questionable clinical significance for their differences with light-cured materials. Introduced Into the profession from prosthetic dentistry applications. Ideal candidates for bonding molar tubes. www.indiandentalacademy.com
  • Smith and Shivapuja examined the dual cements • Vivadent "thick" • Vivadent "thin" • Reliance "fluoride releasing". "Thin" showed higher bond strength, because of reduced viscosity and increased wetting. But handling properties are diminished because of bracket drift. The "thick" cement has increased filler particles, which reduced bracket drift. The "fluoride releasing" has reduced bonding strength. It was extremely viscous and all failures occurred at the tooth adhesive interface. Advantages of Dual cure resins • Reduced curing time and good depth of cure. • Its main advantage was reduced bonding time. In the visible LC, time required to cure entire maxillary and mandibular arch is 13.5 minutes. 40 sec x 20 brackets = 13.5 minutes (VLC) The curing time of Dual Cured resins is approximately 6.5 minutes. www.indiandentalacademy.com 10 sec x 20 brackets + 3 minutes for SC = 6.5 minutes (DC)
  • Disadvantages It centered on the chemically cured properties of the dual cements. 1. Mixing may introduce bulk defects , increasing the porosity. 2. Placement of a bracket with half-hardened cement or removing the flash from such a bracket would drastically affect the bonding strength. In orthodontic bonding, the clinician can control the setting time by 1. Allowing the resin to set by chemical cure 2. Curing with visible light source for 30 seconds 3 Curing with a visible light source for 10 seconds and then allowing the resin to completely polymerize with its chemically cured properties. This gives more time for proper placement of brackets. Furthermore, the clinician can be assured of complete polymerization with the chemical properties of Dual Cured cements. www.indiandentalacademy.com
  • • Thermocured Introduced in orthodontics for indirect bonding . • It is claimed that these adhesives present increased polymerization rates and hence superior properties. • Not intended for direct bonding. • Nanda & Sinha et al (1995 jco feb) They used a thermal cured Fluoride releasing resin to secure brackets on the model. For bonding on cast, they used Thermocure and Maxicure sealant A & B was used in clinical setting. • They reported a failure rate of 5 % Drawback • Bracket float • Ceramic bracket cannot be exposed to heat www.indiandentalacademy.com
  • REVIEW OF ARTICLES A. Self cure Advantages of Concise (two phase) over 'no-mix' Adhesive (A.J. O. 1982 April) According to Artun and Zachrisson 1. Bond strength of concise exceeds no mix adhesive. 2. More homogenous and predictable mix is obtained. 3. No reports of allergic reactions to Concise 4. Shorter "snap" time, it is possible to ligate archwires sooner with Concise. They recommended a four-handed approach to Bonding to help mix the two paste system and enhance bonding results. www.indiandentalacademy.com
  • Whitlock et al (ajo1994) compared 3 different adhesive systems, when used alone and with a porcelain-priming agent, to bond ceramic brackets to porcelain surfaces. The 'no-mix' adhesive liquid had the lowest shear bond strength without the priming agent and the highest bond strength with the priming agent. This is because 'no-mix' adhesive liquid is not polymerized before the bracket is applied. Ching et al. (EJO2000) found that static loads such as tying in of archwires can be placed on Brackets 15 minutes after cementation, without a clinically significant reduction in bond strength of a No-mix adhesive (Unite). Ireland and Sheriff found that it was safe to tie to archwires on the same visit, 1 hour after cementation of the No-mix adhesive (Right on). www.indiandentalacademy.com
  • B. VLC vs SC • Greenlaw and Colleagues (1989 AJO ) found that the bond strength of visible light cured adhesives was insufficient after initial curing and suggested that the slow strength was due to incomplete polymerization. They recommended delaying archwire for 24 hrs. The Greenlaw study compared a visible light cure adhesive (Heliosit Orthodontic) with a one-paste chemically cured orthodontic adhesive (Unite). The Heliosit was used for 20 seconds from incisal and 20 seconds from gingival. The bond strength for the light-cured adhesive at one hour was only 26% of that found at 30 hours, but was still only one-half that of the chemically cured adhesive at 30 hrs. • Larry and Colleague’s study indicate that there are advantages to increasing the setting time of light cured adhesives. Extending the setting time to 5 minutes produced more than 20% increase in bond strength, than 2 minutes. At the 2minute setting time, bonds cured for 40 seconds were 30% stronger than those cured for 20 seconds. He suggests therefore 40 seconds curing time, 20 on mesial and 20 on distal for maximum shear strength. www.indiandentalacademy.com
  • • Wang and Meng (AJO l992) found that visible light is powerful in curing the visible light-activated composite resin under solid metal brackets. The bond strength of light cured resin of Transbond, except in cases of light exposure of 20 seconds, is stronger than that of the selfcured resin of Concise. Transbond cured for 40 sec is therefore recommended. • Rashid Ahmed Chamda (AJO 1996) compared the bond strength achieved with L.C. Bonding system and a chemically cured system over a 24 hr period. There was no significant difference between bond strengths achieved by chemically cured & Light Cured systems at 10 minute, 60 minute and 24 hr interval. www.indiandentalacademy.com
  • • Hugo R. Amass (Ajo98) compared L.C. achieve material (sequence) and C.C. adhesive (System 1+) and found no statistically significant failure rates between the two. • Millet et al. (Angle98) found that failure rates of brackets bonded with light cured resin (Transbond) to pre-molars were almost twice that of brackets bonded to canines or incisors. The large failure may be due to 1. Difficulty with moisture control. 2. Larger amounts of prismatic enamel. • Hugo et al. (1998 AJO ) compared the failure rates of a chemically cured resin (system 1+) and visible light cured bonding material (sequence). There were no statistically significant failure rates between the two. www.indiandentalacademy.com
  • • • • • • C. SC ( both two phase & no mix ) vs LC vs DC Eliades et al., (EJO2000 AUG) compared the degree of cure of A light cured (Transbond XL) Two pastes chemically cured (Concise) One phase (No-mix, chemically cure) – Unite Dual-cured (Two paste) - Duocement Metal brackets and ceramic bracket were bonded. 1. The dual-cured product demonstrated the highest degree of cure followed by Light cured combined with ceramic bracket No mix Two paste chemically cured system. The combination of metallic bracket with the light cured produced similar cure as that of the chemically cured material. www.indiandentalacademy.com
  • RECENT ADVANCES The Prompt L-Pop System • The Prompt L-Pop system is a unitdose system, with etchant, primer, adhesive, and microbrush sealed in a triple-lollipop-shape aluminum foil package. Acid etching, rinsing, priming and application of adhesive are thus combined into one step. Prompt L-Pop (ESPE Dental AG, Seefeld, Germany) is an all-in-1 adhesive for composites and compomers. Prompt L-Pop contains methacrylated phosphoric acid esters that combine an acidic component for etching the enamel and the primer. www.indiandentalacademy.com
  • • • • • Procedure 1. The enamel surface is pumiced or micro abraded. 2. The top bubble is folded, forcing the liquid into the second chamber. 3. The second chamber is popped and folded forcing the adhesive mixture into the third chamber, which contains the microbrush. The brush is stirred around in the 3rd chamber to saturate it with resin. 4. The adhesive is rubbed into the enamel surface for 15 seconds and air dried lightly to evaporate the water carrier, leaving a smooth glossy surface rather than the frosted appearance of phosphoric aid. www.indiandentalacademy.com
  • • Prompt is a low ph - self-etching adhesive that procedures a well defined etch pattern similar to that of phosphoric acid. • As with 4th and 5th generation adhesives, it forms a micro retentive bond with the treated surface. Unlike these systems, it allows the etchant and monomer to penetrate at the same time, avoiding potential technique errors and nanoleakage. Prompt shows outstanding bond strength to both dentin and enamel. • Light curing can be done with visible Light Curing unit or more intense Argon lasers and Plasma-arc curing systems by aiming at the adhesive bracket interface from the occlusal surface. www.indiandentalacademy.com
  • • Cyanoacrylate ( Moisture active adhesives ) • It requires rather than tolerate the presence of moisture for proper polymerization. It does not require bonding agent. The bonding surface must be intentionally wetted prior to application. Bonding is just one step procedure. The presence of saliva however adversely affects their long term clinical performance • A number of studies have found no adverse effects from longterm use of cyanoacrylates inside the human body. • Smart Bond (Gestenco) is not the same as the glue that can be bought in a hardware store; its viscosity has been altered with silica gel. It is also important that the surfaces to be bonded are as close together as possible. • Because polymerization starts only in the presence of moisture and pressure, the clinical procedure for bonding with Smart Bond differs from that of conventional adhesives. www.indiandentalacademy.com
  • Disadvantage 1. Cyanoacrylate does not work well on polycarbonate brackets with enlarged retention surfaces unless they are treated with water. 2. The excess material will be instantly polymerized and turned into white acrylic powder around the bracket, called "blooming". 3. The material cannot fill spaces or gaps, which is why a bracket base with deep mesh or undercuts will have lower bond strength. Advantages 1. Vapor from the unpolymerized material is immediately polymerized when it comes in contact with water, which also eliminates any taste. 2. No residual monomer can react later in the process, and thus the material absorbs no water. This prevents the adhesive from discoloring during treatment. High bond strengths are reported for Smart Bond. 3. Smart Bond presents no particular danger of fracturing the enamel during debonding. www.indiandentalacademy.com
  • Fluoride-Releasing Orthodontic Adhesives The presence of enamel demineralization or so-called 'white spots' is a significant problem. Incorporation of fluoride into enamel structure as fluoroapatite can result in remineralization of small decalcified or caries lesions and also reduces the formation of new lesions. Inorganic fluorides have high polar nature and dental resins have low polarity, which causes loss of mechanical integrity . Organic fluoride incorporation has a plasticizing effect that also yields poor properties. www.indiandentalacademy.com
  • Rawls and Zimmerman (Ajo1989) introduced an experimental fluoride releasing resin that has anti-cariogenic properties. FR 2.5 Ortho adhesive is unique. Fluoride release occurs when fluoride ions are exchanged for other anions in the oral environment. Rather than supplying fluoride to the oral environment by material dissolution, the fluoride is given up in exchange for other anions and the structure integrity of the resin is maintained. • Underwood, Rawls and Zimmerman found that the use of this adhesive resulted in 93% reduction of occurrence of dark zones, indicating a reduction of early demineralization. • Sansing, Rawls and Shage found that the bond strength of this experimental resin compares favorably to existing commercial adhesive. www.indiandentalacademy.com
  • Adhesion Boosters or Adhesion Promoters Adhesion booster, a tooth surface primer advocated by Bowen et al., to increase the bond strength of composite resin to tooth surface. Two recently introduced boosters include Enhance LC and All Bond 2 According to the manufacturer Enhance LC can increase adhesion of composite to any enamel (including fluorosed, hypocalcified, or deciduous enamel), metal or composite surface. With the adhesion Booster Megabond applied on the new bracket base Newman et al., found that the bond strength was lower than new brackets without Megabond, whereas the bond strength of sandblasted new brackets with Megabond was greater than brackets sandblasted without megabond. www.indiandentalacademy.com
  • Ching et al; compared Enhance LC and All Bond 2 to bond debonded brackets. They found that when new brackets are used neither AllBond 2, nor Enhance LC improves bond strength significantly. When rebonding debonded brackets, they found that without the use of any boosters, sandblasted rebonded brackets yield less bond strength than new brackets. Enhance LC fails to increase bond strength of sandblasted rebounded brackets. All-Bond 2 significantly increased bond strength of sandblasted rebonded brackets. All-Bond 2 when used with sandblasted debonded brackets provides comparable results (17 MPa) to new brackets. www.indiandentalacademy.com
  • Hydrophilic Bonding Systems (Ajo200l) Failure of orthodontic bonded attachments and brackets is mostly due to contamination. Materials that over come the moisture and contaminants in the oral environment have been developed. It contains hydrophilic primer (HEMA) dissolved in acetone. HEMA is a water soluble hydrophilic monomer . Webster and Nanda compared 2 hydrophilic bonding systems, MIP and Assure. Similar bonding procedures were used; the difference was in the application of primer. www.indiandentalacademy.com
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  • The results showed that the no contaminated surfaces had the highest bond strengths for both the hydrophilic and hydrophobic materials. Transbond XT with primer -- 26.9 MPa Transbond XT MIP -- 28.1 MPa Assure with prime -- 20.4 MPa When using hydrophobic primer, if the etched surface is contaminated with saliva before primer application, it may be necessary to reetch before proceeding with bonding. If contamination occurs after primer placement and curing, then a simple drying and reapplication of primer is all that is necessary. The hydrophilic primers also showed improved bond strengths with reapplication of primer after saliva contamination. www.indiandentalacademy.com
  • Adhesive Pre-coated Brackets In an attempt to save chair side time during bonding, orthodontists are using ceramic and metal brackets that have been pre-coated with adhesive material. The ingredients in the adhesive applied to bracket and that of ordinary Transbond XT is the same. The difference is limited to percentage of the different ingredients incorporated. Transbond XT contains 14% Bis GMA 9% Bis EMA 77% fillers (Silicate quartz and submicron silica). The corresponding values for pre coated brackets is 12% Bis GMA 8% Bis EMA 80% fillers. www.indiandentalacademy.com
  • • The composition changes are for increasing its viscosity, causing the bracket to adhere more readily to the tooth during initial stages of bracket positioning. • Bishara et al compared the shear bond strength of ceramic and metal brackets, which are not coated and pre-coated. They found that • 1. Pre-coated ceramic brackets have similar bond strength as that of uncoated brackets bonded with adhesive. • 2. Pre-coated metal brackets have lower bond strength than uncoated brackets because of high viscosity causing less flow into the mesh of the brackets. • 3. All three provided clinically acceptable bond strength. www.indiandentalacademy.com
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  • REVIEW OF ARTICLE SEP vs MULTI STEP CONVENTIONAL BONDING 1 (Bishara et al., AJO 2001). Brackets bonded with the SEP were found to have a significantly lower mean shear bond strength compared with those bonded with a conventional two-stage adhesive system. The study, however, did not compare bonding time for each adhesive system. www.indiandentalacademy.com
  • • Use of SEP to bond orthodontic brackets to the enamel surface resulted in a significantly lower, but clinically acceptable, shear bond force as compared with the control group The comparison of the adhesive remnant index scores indicated that there was significantly more residual adhesive remaining on the teeth that were treated with the new self-etch primer than on those teeth that were bonded with the use of the conventional adhesive system. www.indiandentalacademy.com
  • Effect of self-etching primers on bond strength--are they reliable? Angle 2003 Feb. Karaman et al studied to determine the effects of using three self-etching primers on the shear bond strength (SBS) of orthodontic brackets and on the bracket/adhesive failure mode. • In the control group, teeth were etched with 37% phosphoric acid. In the experimental groups, the enamel was conditioned with three different self-etching primers, Clearfil SE Bond (CSE), Etch & Prime 3.0 (EP3), or Transbond Plus (TBP), as suggested by the manufacturer. • The brackets were then bonded with Transbond XT in all groups www.indiandentalacademy.com
  • • TBP group produced significantly higher SBS ( 16.0 +/- 4.5 MPa) than that found in SE, EP3, and the control (acid-etched [AE]) groups. • CSE produced SBS ( 11.5 +/- 3.3 MPa) comparable to those Acid etching ( 13.1 +/- 3.1 MPa). • EP3 resulted in the lowest mean SBS value (mean 9.9 +/- 4.0 MPa). • A comparison of the adhesive remnant index scores indicated that there was more residual adhesive remaining on the teeth that were treated with conventional acid etching than in the CSE and EP3 groups. In the TBP group, the failure sites were similar to those of the AE group but different from those of the CSE group. www.indiandentalacademy.com
  • • Shear bond strength of orthodontic brackets bonded with a modified 1-step etchant-and-primer technique. Ajo 2003 oct Dorminey et al. The purpose of this study was to compare the shear bond strength of orthodontic brackets bonded to enamel with a conventional, multistep adhesive system and a self-etching primer adhesive system. In addition, a third group was included in which the air dispersion step in the self-etching primer system was omitted. SBS (SD) MPa • group 1: conventional multistep adhesive 11.3 (2.2) MPa • group 2: self-etching primer system 11.9 (3.2 MPa • group 3: SEP system without air dispersion 8.2 (2.8) MPa • The mean shear bond strength of the self-etching primer group in which the air dispersion step was omitted was significantly less than in the other 2 groups. There was no difference in mean shear bond strength between the conventional, multistep adhesive system and the self-etching primer system when the primer was dispersed correctly www.indiandentalacademy.com
  • • SEP & SALIVA CONTAMINATION • Efficacy of using self-etching primer with a 4-META/MMATBB resin cement in bonding orthodontic brackets to human enamel and effect of saliva contamination on shear bond strength. Angle 2004 apr Hayakawa et al The objective of this study was (1) to evaluate the effectiveness of Megabond when used with Superbond C&B, a 4- META/ MMA – TBB resin to bond orthodontic metal brackets to human enamel and (2) to examine the influence of saliva contamination on shear bond strength. • 4- META/ MMA – TBB resin -----( 4-methacryloloxyethyl trimellitate anhydride (4-META)/methyl methacrylate (MMA)tri-n-butyl borane (TBB) resin), www.indiandentalacademy.com
  • • • • • There were no significant differences in shear bond strength between phosphoric acid etching and self-etch priming for no contamination, saliva contamination, and repeat treatment (etching or priming) after saliva contamination. With phosphoric acid etching, saliva contamination significantly decreased the shear bond strength. With self-etching primer treatment, however, saliva contamination did not cause any decrease of bond strength. Phosphoric acid etching produced more enamel fracture than self-etching primer treatment. Field-emission scanning microscopy revealed less dissolution of enamel surface resulted from self-etching primer compared with phosphoric acid. These results suggest that Megabond when used with Superbond C&B resin cement may be a good candidate for bonding orthodontic brackets to human enamel. www.indiandentalacademy.com
  • • SEP (INCLUDING F RELEASING )VS CONVENTIONAL • Bishara et al ( Angle 2002 June • In group 1 (control), teeth were etched with 37% phosphoric acid; after the sealant was applied, the brackets were bonded with Transbond XT and light cured for 20 seconds. • In group 2, a self-etch acidic primer was applied as suggested by the manufacturer, and the brackets were then bonded with Transbond XT as in the first group. • In group 3, an experimental self-etch primer EXL #547 was applied to the teeth as suggested by the manufacturer, and the brackets were then bonded as in groups 1 and 2. • In group 4, a fluoride-releasing self-etch primer, One-Up Bond F was applied as suggested by the manufacturer, and the brackets were then bonded as in the other groups. www.indiandentalacademy.com
  • One-Up Bond F (mean +/- SD strength, 5.1+/-2.5 MPa) and Prompt L-Pop (strength, 7.1+/-4.4 MPa) had significantly lower shear bond strengths than both the EXL #547 self-etch primer (strength, 9.7+/3.7 MPa) or the phosphoric acid etch and the conventional adhesive system (strength, 10.4+/-2.8 MPa). www.indiandentalacademy.com
  • Effect of water and saliva contamination on shear bond strength of brackets bonded with conventional, hydrophilic, and self-etching primers. Sfondrini et al AJO 2003 jun • • • • • • • This study assessed the effect of water and saliva contamination on the shear bond strength and bond failure site of 3 different orthodontic primers Transbond XT, Transbond Moisture Insensitive Primer, Transbond Plus Self Etching Primer; used with a light-cured composite resin (Transbond XT). Each primer-adhesive combination was tested under 7 different enamel surface conditions: (1) dry, (2) water application before priming, (3) water application after priming, (4) water application before and after priming, (5) saliva application before priming, (6) saliva application after priming, and (7) saliva application before and after priming www.indiandentalacademy.com
  • • • • • • • • • • SEP, MIP & CONVENTIONAL MULTISTEP Effect of water and saliva contamination on shear bond strength of brackets bonded with conventional, hydrophilic, and self-etching primers. Sfondrini et al (AJO 2003 June) assessed the effect of of water and saliva contamination on the shear bond strength and bond failure site of 3 different orthodontic primers Transbond XT, Transbond Moisture Insensitive Primer, Transbond Plus Self Etching Primer; used with a light-cured composite resin (Transbond XT). Each primer-adhesive combination was tested under 7 different enamel surface conditions: (1) dry, (2) water application before priming, (3) water application after priming, (4) water application before and after priming, (5) saliva application before priming, (6) saliva application after priming, and (7) saliva application before and after priming www.indiandentalacademy.com
  • • 1.Non contaminated enamel surfaces had the highest bond strengths for conventional, hydrophilic, and self-etching primers, which produced the same strength values. • 2.In most contaminated conditions, the self-etching primer had higher strength values than either the hydrophilic or conventional primers. • 3.The self-etching primer was the least influenced by water and saliva contamination, except when moistening occurred after the recommended 3second air burst. www.indiandentalacademy.com
  • Effect of saliva on shear bond strength of an orthodontic adhesive used with moisture-insensitive and self-etching primer Chung et al. Ajo 2003 oct Materials were : • Transbond Moisture-Insensitive Primer (MIP) • Transbond Plus Self-Etching Primer (SEP) • Hydrophobic Transbond XT primer (XT) was used as a control. Conditions: • (1) control: etch/dry/XT, • (2) etch/dry/MIP, (3) etch/dry/MIP/wet (saliva)/MIP, • (4) etch/wet/MIP, (5) etch/wet/MIP/wet/MIP, • (6) dry/SEP, (7) dry/SEP/wet/SEP, • (8) wet/SEP, and (9) wet/SEP/wet/SEP. www.indiandentalacademy.com
  • • (1) Transbond XT adhesive with Transbond XT primer and MIP in a dry field yields similar bond strengths, which are greater than all other groups, • (2) saliva contamination significantly lowers the bond strength of Transbond MIP, • (3) saliva has no effect on the bond strength of Transbond SEP, • (4) Transbond XT adhesive with Transbond MIP and SEP might have clinically acceptable bond strengths in either dry or wet fields. www.indiandentalacademy.com
  • Effect of blood contamination on shear bond strength of brackets bonded with conventional and self-etching primers. AJO 2004 march • Sfondrini et al assessed the effect of blood contamination on the shear bond strength and bond failure site of 2 different orthodontic primers (Transbond XT and Transbond Plus Self-Etching Primer) used with adhesive-precoated brackets. • Four different enamel surface conditions were tested: (1) dry, (2) blood contamination before priming, (3) blood contamination after priming, and (4) blood contamination before and after priming. • www.indiandentalacademy.com
  • • SEP & conventional in blood contamination • Effect of blood contamination on shear bond strength of brackets bonded with conventional and self-etching primers. AJO 2004 • Sfondrini et al assessed the effect of blood contamination on the shear bond strength and bond failure site of 2 different orthodontic primers (Transbond XT and Transbond Plus SelfEtching Primer) used with adhesive-precoated brackets. • Four different enamel surface conditions were tested: (1) dry, (2) blood contamination before priming, (3) blood contamination after priming, and (4) blood contamination before and after priming. www.indiandentalacademy.com
  • • Noncontaminated enamel surfaces had the highest bond strengths for both conventional and self-etching primers, which produced almost the same strength values. • Under blood-contaminated conditions, both primers showed significantly reduced shear bond strengths. • For the conventional primer, no significant differences were reported among the blood-contaminated groups, whereas when the self-etching primer was used, condition 4 reduced significantly the bond strength values www.indiandentalacademy.com
  • • SEP: Transbond Plus & Ideal 1 • Comparison of the shear bond strength of 2 self-etch primer/adhesive systems. Bishara & Laffoon. (AJO 2004) march In group I, a self-etch acidic primer/adhesive system, Transbond Plus (3M ), was applied on the enamel surface as suggested by the manufacturer; it has 2 components that must be mixed before use. The brackets were then bonded with Transbond XT and light-cured for 20 seconds. • In group II, a no-mix self-etch bracket adhesive system, Ideal 1 (GAC), was applied to the teeth. The self-etch primer has 1 component that does not need to be mixed before use. The brackets were then bonded with the adhesive and light-cured for 20 seconds. • The in vitro findings indicated that the shear bond strength comparisons of the 2 adhesive systems were not significantly different . The mean shear bond strength of the 2-component acid etch primer was 5.9 +/- 2.7 MPa, and the mean for the 1component system was 6.6 +/- 3.2 MPa. www.indiandentalacademy.com
  • SEP VS CONVENTIONAL & FUJI ORTHO LC H21 Effect of using self-etching primer for bonding orthodontic brackets. Angle 2002 dec Yamada. et al determined the shear bond strengths of orthodontic brackets bonded with one of four protocols: • (1) a composite resin adhesive used with 40% phosphoric acid, • (2) the same composite resin used with Megabond self-etching primer, • (3) a resin-modified glass ionomer cement adhesive used with 10% polyacrylic acid enamel conditioner, and • (4) the same resin-modified glass ionomer cement used with Megabond self-etching primer. www.indiandentalacademy.com
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  • • Megabond self-etching primer gave the same shear bond strength as acid-etching when used with a resin-modified glass ionomer cement. • Megabond gave a significantly lower shear bond strength when used with a composite resin adhesive. • Megabond self-etching primer treatment produced less enamel dissolution than did etching with phosphoric acid and polyacrylic acids. • The present findings provide evidence that Megabond selfetching primer is a candidate for bonding orthodontic brackets using the resin-modified glass ionomer cement, with the advantage of minimizing the amount of enamel loss. www.indiandentalacademy.com
  • • SEP - CONVENTIONAL & FLUORIDE VARNISH • F 3 Effect of fluoride varnish on the in vitro bond strength of orthodontic brackets using a self-etching primer system. Kimura et al AJO 2004 • The results showed no difference in bond strength among the conventional or self-etching primer system.. Adhesive remnant index scores were not statistically different. The application of fluoride varnish does not affect the bond strength of orthodontic brackets to enamel with conventional or self-etching primer systems. www.indiandentalacademy.com
  • CYANOACRYLATE & CONVENTIONAL 2001 Dec angle Bishara & Laffoon •Cyanoacrylate did not show any significantly different shear bond force (5.8 +/- 2.4 MPa) as compared to the control group (5.2 +/2.9 MPa). •The comparison of the Adhesive Remnant Index scores indicated that there was significantly less residual adhesive remaining on the tooth with the cyanoacrylate than on the tooth with the conventional adhesive system. In conclusion, the new adhesive has the potential to be used to bond orthodontic brackets while reducing the total bonding time. www.indiandentalacademy.com
  • • Wilner and Oliver (Bjo2000sept) found that cyanoacrylates are unsuitable for use as a bonding agent in routine orthodontic practice. The bond strength deteriorated after few works. It can be used to adhere to wet surface and where less force is required for a short time, as in impacted canines www.indiandentalacademy.com
  • • Effect of time on the shear bond strength of cyanoacrylate and composite orthodontic adhesives. Ajo 2002 march Bishara & Laffoon. The bond strength of the cyanoacrylate adhesive was not significantly different from that of the composite adhesive. Their findings indicated that the cyanoacrylate and the composite adhesives tested have clinically adequate shear bond strengths at half an hour and at 24 hours after initial bonding. The clinician needs to consider the properties of each adhesive: e.g., the need to use a curing light and the ability to have more working time with the composite adhesive versus no light but only a 5-second working time before the cyanoacrylate adhesive starts to set. www.indiandentalacademy.com
  • • HYDROPHILIC & HYDROPHOBIC PRIMER • 1. Littlewood et al (BJO2000june) found that the bonds strength obtained with the use of hydrophilic primer (6.43 MPa) was significantly lower than the conventional primer (8.71 MPa). www.indiandentalacademy.com
  • • • • • • • Bond strength comparison of moisture-insensitive primers. Foleyet al. AJO 2002 sept The objective of this in vitro bonding study was to evaluate the effectiveness of 2 moisture-insensitive primers, Assure and MIP compared with a control hydrophobic primer, Transbond XT . Protocols: (1) Transbond XT primer and adhesive applied to a non contaminated surface; (2) Assure primer applied after saliva contamination; (3) MIP primer applied after saliva contamination; (4) Assure primer reapplied after saliva contamination; (5) MIP reapplied after saliva contamination; and (6) Assure adhesive applied after saliva contamination of the primer. www.indiandentalacademy.com
  • • 1. Both bonding systems provide adequate bond strengths whether saliva contamination occurs before or after the application of the hydrophilic primers; therefore, additional mechanical preparation and reetching of the enamel surface after saliva contamination might not be required. • 2. Comparing saliva contamination after application of primer(4 &5), both MIP and Assure had significantly greater shear-peel bond strengths than when contamination occurred before the application of each primer. • 3. Transbond XT and MIP group 5 (contamination between 2 layers of primer) showed significantly greater shear-peel bond strengths compared with the other groups. • 4. The groups with saliva contamination before application of the primer showed more frequent failures at the enamel/adhesive interface, suggesting that complete penetration of primer was prevented (nanoleakage) , whereas the groups with saliva contamination after the first application of primer showed more frequent failures at the adhesive/bracket interface. • 5. The greatest frequencies for EF on debonding occurred in the groups with the highest bond strengths. www.indiandentalacademy.com
  • • angle 2003 aug Klocke evaluated bond strength for a custom base indirect bonding technique using a hydrophilic primer on moisture-contaminated tooth surfaces. • 1. Bond strength for the custom base indirect bonding technique with the hydrophilic primer was not significantly different in groups without contamination and with water or saliva contamination before application of the primer. • 2. Moisture contamination after application of the hydrophilic primer resulted in significantly lower bond strength measurements compared with bond strength for uncontaminated enamel. www.indiandentalacademy.com
  • MIP UNDER MOIST & BLOOD CONTAMINATION G19 The effect of moisture and blood contamination on bond strength of a new orthodontic bonding material. AJO 2001 july Hobson et al evaluated the bond strength of Transbond MIP under dry, moist, and blood-contaminated conditions. Dry bonding resulted in significantly higher bond strength (15.69 MPa) than moist (12.89 MPa) or blood-contaminated (11.16 MPa) bonds. • However, all bond strengths were in excess of previous reports of required clinical bond strength, and it was concluded that Transbond MIP is a suitable adhesive for bonding in conditions of poor moisture control or blood contamination • Transbond MIP is therefore an ideal bonding agent for bonding during the surgical exposure of teeth. www.indiandentalacademy.com
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  • • From the review of the above articles it can be concluded that : • 1.Non contaminated enamel surfaces had the highest SBS for both the hydrophilic and hydrophobic materials. • 2.When the contamination occurred after the primer was cured a simple drying and reapplication of primer was enough to get adequate bond strength. • 3.Hydrophilic bonding systems showed improved bond strength after reapplication of primer after saliva contamination. www.indiandentalacademy.com
  • • FLUORIDE RELEASING ADHESIVES • .William A Wittshire and Sophia (AJO 95 SEPT) compared two non-fluoride visible light-cured orthodontic adhesives (Heliosit Orthodontic and Transbond) with 2 fluoridecontaining visible L.C orthodontic adhesives (FluorEver OBA and Light Bond). The 2 non-fluoride adhesives, both released small amounts of Fluoride, despite bring nonfluoridated. The Fluoride release could be due to small amounts of fluoride such as barium fluoride present in the inorganic phase. • Light-bond had an immediate burst of F release during the 1st day followed by sharp decrease such that F could not be detected for 2 weeks longer than non-fluoride adhesives. • FluorEver continued to release F up to 85 weeks. www.indiandentalacademy.com
  • • Fluoride release from FluorEver OBA up to 85 weeks. www.indiandentalacademy.com
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  • • .The study conducted by Oggard et al (Ajo 97Feb), with the fluoride releasing adhesive orthodontic cement VP 862 found that the anti cariogenic effect is due to release of fluoride in to the local environment than elevation of fluoride level in saliva. Orthodontic cement VP 862 is a halogen light curing adhesive. • Chung and Piatti (JCO2000 July) compared the clinical bond strength of fluoride releasing phase II with non-fluoride releasing Phase II. Phase II and the non-fluoride releasing Phase II, both had failure rates of less than 2% at 3 months and less than 5% at 6 months. • They concluded that fluoride releasing Phase II is clinically strong enough for use as an orthodontic bonding adhesive. (Fluoride may leach out of the material by ion exchange with other anions in the oral environment, as proposed by Rawls and Zimmerman.According to them, this type of fluorideexchanging resin should maintain its physical properties, since the fluoride is given up in exchange for other anions.) www.indiandentalacademy.com
  • • RESIN MODIFIED GIC , HYBRID GIC & CONVENTIONAL COMPOSITE • Foley & Mamandras (AJO 2001 Jan) The objective of this study was to compare 3 orthodontic adhesives in the areas of shear-peel bond strength, location of adhesive failure, and extent of enamel cracking before bonding and after debonding of orthodontic brackets. • The adhesives included a composite resin control (Transbond XT) • A resin-modified glass ionomer cement (Fuji Ortho LC) • A polyacid-modified composite resin( GIC HYBRID) under dry and saliva-contaminated conditions (Assure). www.indiandentalacademy.com
  • 1.Transbond XT displayed significantly greater shear peel bond strength than Fuji Ortho LC and Assure, although the bond strengths for all 3 adhesives were clinically acceptable. 2. There was no significant difference in mean shear-peel bond strengths between Assure-wet (saliva-contaminated) and Assure-dry (non-contaminated) protocols. 3. Fuji Ortho LC and Assure-wet tended to display adhesive failure at the enamel/adhesive interface while Assure-dry and Transbond XT tended to display cohesive failure within the adhesive. 4. The greatest frequencies for enamel fracture upon debonding occurred in the groups showing the highest bond strengths (Transbond XT and Fuji www.indiandentalacademy.com Ortho LC).
  • • Adhesives that Bond Chemically to Metal • During the 1980's, primers such as Fusion and adhesives such as Enamelite 500 and Goldlink were introduced for bonding to gold and dental metal alloys, they were not very effective. • Attachments are then bonded with highly filled adhesives (e.g. Concise) to the metal. • 2 different types of adhesives, 4-META resins and 10-MDP Bis- GMA resins have recently been developed to improve adhesion to metals. www.indiandentalacademy.com
  • Intermediate Resins to Enhance Bond Strengths All-Bond 2 and Scotch bond MP (Multipurpose) are the most popular and complete intermediate resins available today. All-Bond 2 A third generation dentin-bonding agent contains a 10% phosphoric acid gel for dentin conditioning. One drops each of Primer A and Primer B are mixed and applied to the enamel until the acetone solution evaporates. The site is then air dried for 5 to 10 seconds. All-Bond 2 can be used to increase the strength of any adhesive by this method. Primer B is claimed to be an effective metal primer when repairing a porcelain-metal crown or bonding a metal-based restoration. www.indiandentalacademy.com
  • • Bonding to Amalgam • Amalgabond (Super-Bond D Liner) is a 4-META resin that bonds to amalgam, as do Super Bond C & B. This cures in 60 seconds. • All Bond 2 and Amalgabond can be used during initial placement. Scothbond MP - Should be used only on hardened, Sandblasted amalgam . • Another 4-META intermediate resin that will enhance bond strength to artificial tooth surfaces and has a short polymerization time (30 seconds) is Reliance Metal Primer. • Therefore Amalgabond plus or Reliance Metal Primer can be used as an intermediate application before bonding with composite resin to amalgam www.indiandentalacademy.com
  • • Bonding to glazed porcelain with the assistance of a coupling agent (Silane) as an interface between the porcelain and the bonding agent. Silanes are recognized as coupling agents for bonding glass fillers intc polymers. Studies have shown that silane coupling agent will increase the adhesion of resins to dental porcelain. • Silane also helps in bonding brackets to composite prosthetic restorative material (Isosit), a heat cured composite resin. • The silane solution is prepared according to the protocol presented in the work of Chen and Brauer. It contains. • 5% Vol of silane (gamma - methacryloxypropyl methoxysilane) • 2% wt% of n-propylamine, in acetone • eg : Ormco Porcelain primer, Scotch prime ,Clearfill porcelain bond • The bond strength produced by this method is apparently inadequate for orthodontic purposes. www.indiandentalacademy.com
  • • High-Q-Bond (HQB) • HQB is a dentin-bonding agent that belongs to the fourth generation of dental adhesives. • It is composed of acrylic monomers methylmethacrylate (MMA) crosslinked with a multifunctional agent, an adhesion promoter a comonomer-aliphatic polyester and initiators for selfcuring process (dimethyl-P-toluidine and Benzoyl peroxide). It also includes poly MMA, inorganic fillers and coupling agent. • HQB provides high tensile bond strength and can be used for bonding to various substrates such as enamel, noble and base metal alloys, amalgam, composite and porcelain. www.indiandentalacademy.com
  • • Degradation of Polymeric Systems Degradation of high polymers can be character-ized into two broad areas: Random, Where chain rupture is induced by one or more factors" such as exposure to ozone, oxygen. ultraviolet radiation, and foreign agents. This type of degradation occurs at random sites in the polymer structure, resulting in the release of large structural fragments. Chain depolymerization, where release of monomer occurs in a more organized man-ner (depropagation). Depropagation is virtually the reverse of polymerization where bond breakage is initiated at a chain defect site and a hydrogen atom is released from the polymer structure. The polymer chain then splits, and both a free radical and an inactive species are created. www.indiandentalacademy.com
  • Carbon double bond unsaturation (C = C ) Water sorption Composite resin solubility Micro cracks Bacteria & enzymes Diffusion channels Degradation process. www.indiandentalacademy.com
  • • Munksgaard and Freud demonstrated the occurrence of enzyme-induced degradation of di-methacrylate polymers and the hydrolytic nature of the process. • Their work was preceded by experiments in several polymer systems that consistently showed enzymatic activityinduced degradation of the materials. • Initially, the applicability of these laboratory results to the clinical situation was questioned: Investigators claimed that, under clinical conditions; the' composite resin is covered by a proteinaceous film (pellicle) that masks the surface layer presumably decreasing its reactivity with the environment and any subsequent attraction and adsorption of molecular' complexes. Such adsorbed substances might affect' the 'enzymatic activity of adjoining resin molecules in an unpredictable manner. www.indiandentalacademy.com
  • • However, Matasa has demonstrated that aerobic and anaerobic microbial activity 'may weaken the resin, leading to compromised bond strength. These effects were attributed to the ability of some microbes to metabolize adhesive constituents. A suggestion was made to incorporate substances in the adhesive with bactericidal activity similar to the approach of including gentamycin in bone cements (PMMA-based) intended for use in total hip replacement arthroplasties. www.indiandentalacademy.com
  • • Leaching of Orthodontic Adhesives • Water immersion has been reported to cause release of 50% of the leachable species while ethanol-water immersion accelerated the release rate to 75 % from dental resins during the first three hours. • Ferracane and Gordon were unable to detect further elution from composite resins after 24 hours of immersion. • In contrast, other investigators found prolonged elution from composite resins and orthodontic adhesives Which continued for 115 days and two years, respectively. • Ethanol-water baths tend to accelerate the degradation of composite resins when compared, to water immersion, and also promote elution of leachable species. • The quan-tity and composition of the eluted substances are key factors for the toxic potential of a resin adhesive. In general the maximum accepted weight loss of restorative material has been stipulated at 5microgram /mm3. Filler components (mainly silicon) have been estimated to account for approxi-mately 180 micro mol/g weight loss. www.indiandentalacademy.com
  • • Eluted substances include fillers, enzymatic hydrolysis-induced methacrylic acid, benzoic acid resulting from degradation of the benzoyl peroxide initiator, and materials probably originating from the polymerization accelerators and catalysts. • A serious concern arises from the formation of formaldehyde (H2C= 0) as an oxidation reaction product of oxygen with the carbon-carbon double bonds , Oxygen is capable of detaching the pendant group from the polymer network, leading to structural degradation. www.indiandentalacademy.com
  • • AJO1995 Sep Eliades and Brantley in their study of residual monomer leaching from three adhesives showed that • 1. No statistically significant differences in the amount of released monomers were found among the ceramic bracket groups bonded to the visible light-cured adhesive and photo polymerized under direct or indirect irradiation. • 2. The polycarbonate base ceramic bracket demonstrated significantly higher amount of released monomers compared with ceramic brackets. Evidence of degradation of the polycarbonate base was detected. • 3. The highest amount of residual monomers was eluted from the chemically cured adhesive group. The visible light-cured adhesive bonded to the stainless steel brackets under indirect irradiation showed values comparable to ceramic brackets, while direct irradiation resulted in high amount of eluted monomers. www.indiandentalacademy.com
  • • CYTOTOXICITY • – Davidson et al ( 1983 AJO) • Orthodontic bonding materials were tested for in vitro cytotoxicity by an agar-diffusion cell culture technique. Vero cells were grown in a monolayer, covered with an agar/medium overlay, and exposed to equal amounts of orthodontic adhesives immediately after polymerization and at various time periods up to 30 days after mixing. The diameter of the area of unstained, nonviable cells (zone of inhibition) provided a quantitative measure of toxicity. • All materials were found to show cytotoxicity immediately after preparation, with the activator components of two "no-mix" materials exhibiting significantly higher toxicity than other materials tested. Polymerized adhesives generally showed decreased toxicity following soaking in saline solutions which simulated the bathing of materials by intraoral fluids. The sealant materials showed statistically significant greater toxicity than paste resins, both initially after mixing and after 30 days. • The significant finding in this study was that these materials not only were toxic immediately after mixing but remained toxic for extended periods of time. Excess material should be removed from teeth by thorough scaling and flushing with water and high-speed www.indiandentalacademy.com evacuation, particularly in areas adjacent to the gingiva.
  • 1. Cytotoxicity of direct-bonding adhesives – Davidson (AJO 1988 May )in their study showed that different direct bonding adhesives were toxic to varying degrees in vitro and that toxicity decreased more rapidly for some adhesives than others. Although these results do not necessarily translate to any direct toxic effects on patients, they do indicate that this technique can detect a potential long-term toxic effect in orthodontic adhesives, which should warrant further prudent in vivo animal model testing. www.indiandentalacademy.com
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