INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
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CERAMIC BRACKETS www.indiandentalacademy.com
Seminar presented by
Dr Nikhar Verma Under the guidance of
Prof Ashima Valiathan Head of Dept., Director of PG studies Dept of Orthodontics and Dentofacial Orthopedics MCODS, Manipal www.indiandentalacademy.com
Introduction. • Ideal orthodontic appliance: Good esthetics & Optimum technical performance. • Ceramic brackets – introduced in 1986. • Increase in the adult patients • Integral part of the orthodontists’ armamentarium www.indiandentalacademy.com
Ceramic Brackets •Types. •Physical properties. •Bond strength. •Frictional resistance. •Base surface characteristics. •Debonding techniques and enamel fracture risks. •Enamel abrasion and wear. •Bracket fracture. •Bracket recycling. www.indiandentalacademy.com
Evolution of brackets in terms of esthetics Bands Bondingcoated metal brackets smaller stainless steel brackets lingual orthodontics Polycarbonate Metal slots( Ceramic reinforced) ceramic brackets www.indiandentalacademy.com
Ceramics - material science • Greek word “Keramikos” meaning “earthen”. • Ceramics are materials which are first shaped and then hardened by heat. Form a broad class of materials that include precious stones, glasses, clays and metallic oxides. • Neither metal nor polymeric. www.indiandentalacademy.com
Ceramics - material science • Usually of a silicate nature. It may be a combination of one or more metals with a non-metal oxygen. The larger oxygen atoms serve as matrix, with the smaller metal atoms or semi-metal atoms such a silicon tucked into spaces between oxygen atoms. www.indiandentalacademy.com
Ceramics - material science • Ceramic brackets are composed of aluminum oxide . • Polycrystalline alumina & monocrystalline alumina are the two most common varieties. • Another category that is being developed is the Zirconium brackets www.indiandentalacademy.com
Monocrystalline brackets – manufacturing process • Heating aluminum oxide to temperatures in excess of 2100° C. The molten mass is cooled slowly, and the bracket is machined from the resulting crystal. www.indiandentalacademy.com
Polycrystalline brackets – Manufacturing process • Manufactured By blending aluminum oxide particles with a binder, the mixture can be formed into a shape from which a bracket can be machined. (sintering process) • Temperatures above 18000 C are used to burn out the binder and fuse together the particles of the molded mixture. • Heat treated to remove surface imperfections and relieve stresses created by the cutting operation www.indiandentalacademy.com
Polycrystalline brackets – Manufacturing process • The presence of pores, machining interferences, and propagation lines contribute to compromises of bracket use anytime during clinical use. • An alternative method of making polycrystalline brackets is injection molding. This process does not require the brackets to be machined and thus eliminates structural imperfections created by the cutting process. www.indiandentalacademy.com
Comparison of properties • Production of polycrystalline brackets is less complicated, these brackets are more readily available at present. • Single crystal brackets are noticeably clearer than polycrystalline brackets, which tend to be translucent. • Both resist staining and discoloration. • Come in a variety of edgewise structures including true Siamese, semi-Siamese, solid, and Lewis/Lang designs. www.indiandentalacademy.com
Zirconia brackets • Zirconia is a mineral extracted from beach sands of Australia. • The PSZ (Partially stabilized Zirconium) developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO) as a reliable highly stress-resistant material. • A remarkable quality of zirconia -based advanced ceramics is that wear actually makes the material stronger www.indiandentalacademy.com
Zirconia brackets • In theory, the low frictional coefficients achievable with yttria-stabilized zirconia1 should make it a suitable alternative to alumina for bracket construction. • However, zirconia brackets have problems related to color and opacity, which detract from the esthetics, and can inhibit composite photopolymerization. • A study by Kusy et. al. concluded that zirconia brackets offer no significant improvement over alumina brackets with regard to their frictional characteristics.( Kusy, AJO 1994) www.indiandentalacademy.com
Ceramic brackets- hardness • Extremely high hardness of aluminium oxide, so both monocrystalline and polycrystalline alumina have a significant advantage over stainless steel. • Because ceramic brackets are nine times harder than stainless steel brackets or enamel, severe enamel abrasion from ceramic brackets might rapidly occur, if contacts between teeth and ceramic brackets exist www.indiandentalacademy.com
Ceramic brackets- tensile strength • The ability to resist structural failure, called tensile strength:monocrystalline alumina >polycrystalline alumina, >> stainless steel. • Depends on the condition of the surface of the ceramic. A shallow scratch on the surface of a ceramic bracket will drastically reduce the load required for fracture. The elongation for ceramic at failure is less than 1% in contrast with approximately 20% of stainless steel, thus making ceramic brackets more brittle. www.indiandentalacademy.com
Ceramic brackets- tensile strength • Ceramics have highly localized, directional atomic lattice that does not permit shifting of bonds and redistribution of stress. So when stresses reach critical levels, interatomic bonds break, and “brittle failureâ€? occurs. www.indiandentalacademy.com
Ceramic brackets- fracture toughness • Fracture toughness in ceramics is 20 to 40 times less than in stainless steel, making it much easier to fracture a ceramic bracket than a metallic one. Among ceramic materials, polycrystalline alumina presents higher fracture toughness than single-crystal alumina. • Semi-twin brackets,( Fascination, Mystique, & Virage) have significantly higher tensile fracture strength than true-twin brackets, ( Clarity, lnVu, & Luxi) . Mono-crystalline bracket (Inspire) could not be fractured in the study. (Johnson et al, Angle 2005) www.indiandentalacademy.com
Bond strength • Ceramic material does not bond chemically with adhesives • Chemical bonding : glass is added to the aluminum oxide base and is treated with a silane coupling agent. Silane bonds with glass and leaves a free end of its molecules that react with any of the acrylic bonding materials. • Shiny surfaces of ceramic brackets bonded chemically allow greater distribution of stress over the whole adhesive interface without the presence of any localized stress areas. • Significantly greater shear bond is needed to cause debonding and pure adhesive failure www.indiandentalacademy.com
Bond strength • Mechanical bonding : brackets have retentive grooves in which edge angles are 90°. There are also crosscuts to prevent the brackets from sliding along the undercut grooves that have sharp edge angles, thus leading to high localized stress concentrations around the sharp edges and resulting in brittle failure of the adhesive. On application of shear debonding force, part of the adhesive is left on the tooth and part on the grooved bracket. www.indiandentalacademy.com
Bond strength of ceramic brackets • Mean shear bond strength of the polycrystalline ceramic brackets is significantly greater than that obtained when stainless steel brackets are used • Single crystal ceramic brackets produce the lowest mean shear bond strength values. • Gwinnett( AJO1988) reported that the mean values for the different bracket types are not statistically significant, but this conflicts with the results of many other studies. www.indiandentalacademy.com
Bond strength of ceramic brackets • Bond strengths are greater with chemical bonding than with mechanical retention which shows bond strengths comparable to metal brackets (Wang AJO1997). • Decreasing etching time, (with 37% phosphoric acid) from 30 seconds to 10 seconds maintains a clinically useful-bond strength. (Olsen & Bishara AJO 1996). • Light-cured GICs provide sufficient strength for bonding ceramic brackets, but in terms of bond failure site and bracket fracture, they provide no advantage over composite adhesives. (Jost-Brinkmann, J Adhesiv Dent 1999) www.indiandentalacademy.com
Silane coated chemical adhesive base
Mechanical retentive base
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Micromechanical retention
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Bond strength of ceramic brackets • Weinberger, Angle 1997, 1997 evaluated 3 different methods of curing for poly- and mono-crystalline brackets. the mean shear bond strengths of the single crystal alumina brackets with silanated bases were significantly higher than those of the polycrystal alumina brackets with non-silanated bases, and no enamel fractures were found on debonding the chemically cured brackets while the light and argon laser groups exhibited a 10% rate of enamel fracture on debonding. www.indiandentalacademy.com
Bond strength of ceramic brackets • Mean bond strengths of Clarity brackets (polycrystalline) and Inspire brackets ( monocrystalline) found to be comparable. No enamel damage was evident in any specimen when the brackets were removed with the appropriate pliers recommended by the manufacturers. ( Sadowsky, AJO 2004). www.indiandentalacademy.com
Frictional Resistance • Stainless steel brackets generate lower frictional forces than ceramic brackets, because of their lower surface roughness, which is clearly visible when comparing scanning electron micrographs. • Ceramic brackets produce significant greater friction. Beta-titanium and nickel-titanium wires are associated with higher frictional forces than stainless steel or cobalt-chromium wires. Progressively increasing frictional values: stainless steel bracket, ceramic bracket with a metal reinforced slot, and traditional ceramic bracket with a ceramic slot. (Cacciafesta et al, AJO2003; Nishio et al. AJO 2004) www.indiandentalacademy.com
Frictional Resistance • Mono-crystalline alumina brackets are smoother than polycrystalline samples, but their frictional characteristics are comparable.( Kusy AJO1994) • To reduce frictional resistance, development of ceramic brackets with smoother slot surfaces, rounding of slot base or consisting of metallic slot surfaces has been accomplished. • Metal-lined ceramic brackets can function comparably to conventional stainless steel brackets and 18-kt gold inserts appear superior to stainless steel inserts. (Kusy & Whitley, Angle 2001). www.indiandentalacademy.com
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Frictional Resistance • Ligation: Usefulness of Teflon-coated ligatures compared to elastomeric ligatures in minimizing the high friction of ceramic brackets when an esthetic appliance is imperative (DeFranco, Angle 1995). • Manufacturers have also introduced self ligating ceramic brackets.www.indiandentalacademy.com
Self ligating ceramic brackets www.indiandentalacademy.com
Self ligating ceramic bracket www.indiandentalacademy.com
Base surface characteristics • Formed with undercuts or grooves that provide a mechanical interlock to the adhesive. These brackets may have a flat base, covered with a silane layer with recesses for mechanical anchoring. • Bracket base has a smooth surface and relies on a chemical coating to enhance bond strength. A silane coupling agent is used as a chemical mediator between the adhesive resin and the bracket base because of the inert composition of the aluminium oxide ceramic brackets. The manufacturers of such brackets have reported that they achieve higher bond strength when compared with mechanical retention. www.indiandentalacademy.com
Base surface characteristics • Polycrystalline alumina with a rough base comprised of either randomly oriented sharp crystals or spherical glass particles. to provide micromechanical interlocking with the orthodontic adhesive. • To overcome the potential damage of enamel during debonding, a ceramic bracket with a thin polycarbonate laminate on the base has been manufactured (CeramaFlex, TP Orthodontics). The bond to the enamel is to the thin polycarbonate laminate. It is suggested that these brackets are as easy to remove as metallic brackets. Ceramaflex brackets have a significantly lower bond strength than traditional ceramic brackets. On the other hand, the bond failure location of the Ceramaflex bracket is consistently more favorable, i.e., occurring at the ceramic bracket-polycarbonate base.( Olsen & Bishara ,Angle 1997) www.indiandentalacademy.com
Bright-field polarized-light photomicrograph of a Starfire bracket base ( Silane coated), illustrating the partially coated area. (Original magnification x 50.)
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photomicrograph of a Lumina bracket base. uniformly distributed and embedded spherical particles
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micrographs of a Transcend 2000 bracket base ented crystals of various shapes that form an irregular substrate capable of micromechanica
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Bracket Placement • Certain ceramic brackets have color coded long axis indicators which enable easy identification and eliminate bonding errors. The long axis indicator is removed with a pull motion after the bonding procedure. www.indiandentalacademy.com
• Removable color coded indicators provide positive bracket identification and allow easier placement. • Millimeter marks aid in obtaining proper occlusalgingival height and eliminate the need for special placement instruments www.indiandentalacademy.com
3mm 4mm 5mm
Mechanical Debonding techniques • Delaminating method: In this method, a sharp-edge instrument is placed at the enamel-adhesive interface. The application of force produces a wedging effect of the sharp edge to separate the enamel and adhesive surfaces. Sinha & Nanda (AJO1997) found this technique to be safe for debonding mono- and polycrystalline ceramic brackets. • Wrenching method: Brackets are debonded by a special tool that uses a torsional or wrenching force at the base of the bracket. www.indiandentalacademy.com
Mechanical Debonding techniques • Specially designed pliers that apply some type of tensile or shear force to the tooth surface. • Lift-off debracketing method: This method uses a pistol grip debonding instrument, which is positioned over the brackets with its jaws aligned horizontally over the bracket in an occluso-gingival direction over the tie wings. Debonding occurs when the handles are squeezed and the jaws contact the tie wings and pull the bracket away from the tooth surface. www.indiandentalacademy.com
Enamel fracture & mechanical debonding • The degree of force required to achieve mechanical bond failure and the sudden nature of bracket failure could cause enamel fracture or cracks and raise the risk of aspiration of bracket fragments by the patient. • This debonding method imposes the risk of bracket fracture. In case of bracket fracture, the removal of the remaining fragments of the ceramic brackets from the enamel surface has to be carried out with a diamond bur in a www.indiandentalacademy.com high-speed handpiece.
Enamel fracture & mechanical debonding • This procedure is time-consuming, produces large fragments of the bracket during grinding, and results in large amounts of ceramic dust that has been associated with itchy skin on hands and eye irritation. • Grinding ceramic material from the tooth surface may generate heat, which could damage the dental pulp, if low-speed grinding without coolant is used. www.indiandentalacademy.com
Mechanical debonding
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Enamel fracture & debonding • Debonding with sharp-edged pliers that apply a bilateral force at the bracket base-adhesive interface was found to be the most effective method for debonding polycrystalline alumina orthodontic brackets. • Forces applied at the interface rather than the bracket itself may prevent breakages on debonding. Further, it was reported that brackets bonded by indirect techniques that create a resin interlayer facilitates debonding at the interface formed between this interlayer and the filled resin.( Sinha, Nanda AJO1995 ) www.indiandentalacademy.com
Enamel fracture & debonding • Ceramic >> metallic brackets, • Monocrystalline >> polycrystalline. • Chemical retention >> mechanical retention. • The damage to tooth structure by applying mechanical debonding methods is higher, if the integrity of the tooth structure is compromised by the presence of developmental defects, enamel cracks and large restorations, or it is a non-vital tooth. • The need for relatively strong forces to obtain bond failure may result in various degrees of patient www.indiandentalacademy.com discomfort.
Electrothermal debonding • It involves heating the bracket with a rechargeable heating gun while applying a tensile force to the bracket. The bracket separates from the tooth once sufficient heat has penetrated the bracket/adhesive interface. • The potential for pulp damage exists, because a significant rise in pulp temperature may result in tooth necrosis.
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Electrothermal debonding • The safety threshold of a 5.5° C increase in intra-pulpal temperature described by Zach and Cohen should not be violated. • Other disadvantages include the bulky nature of the handpiece that may make its intraoral use difficult, especially in the premolar region, and the risk of dropping a hot bracket in the patient's mouth. • Bishara and Trulove(AJO 1990) found the electrothermal technique to be quick, effective, and devoid of either bracket or enamel fracture. www.indiandentalacademy.com
Electrothermal debonding unit
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Debonding methods • Derivative of peppermint oil that is applied around the bracket base and is left for 2 minutes before debonding can facilitate ceramic bracket removal without damaging the tooth surface. • Ultrasonic debonding technique: The advantages include a decreased chance of enamel damage, a decreased likelihood of bracket failure, removal of the residual adhesive with the same instrument after debracketing. Drawbacks: time-consuming, excessive wear of the expensive ultrasonic tips & requires water spray to control the heating www.indiandentalacademy.com
Debonding methods • Lasers : Debonded by irradiating the labial surfaces of the brackets with laser light. Reduces the residual debonding force, the risk of enamel damage, and the incidence of failure. • less traumatic and painful for the patient and less risky for enamel damage. ( Toccio AJO 1993) www.indiandentalacademy.com
Laser debonding - Mechanism • Types of lasers : Nd YAG,, super-pulse carbon dioxide lasers ,carbon di-oxide lasers • Laser-initiated degradation can occur by: • Thermal softening: which occurs at relatively low rates of laser energy deposition, heats the bonding agent up until it softens, • Thermal ablation occurs when the rate of energy deposition is fast enough15 to raise the temperature of the resin through its fusion range and into its vaporization range before debonding by thermal softening occurs. The rapid buildup of gas pressure along the bonding interface will explosively "blow" the bracket off the tooth, independent of any externally applied debondingwww.indiandentalacademy.com force.
Laser debonding - Mechanism • Photoablation occurs when very high energy laser light interacts with a material. During lasing, the energy level of the bonds between the bonding resin atoms rapidly rises above their bond disassociation energy levels, and the material decomposes. High gas pressure would rapidly develop within the interface, and the bracket would be explosively blown off the tooth after a www.indiandentalacademy.com single light pulse.
Enamel abrasion and wear • Can occur during contacts of ceramic brackets with occluding teeth. • The highest abrasion scores have been reported with mono-crystalline ceramic brackets. • Contact of the opposing teeth with the ceramic brackets must be avoided . www.indiandentalacademy.com
Bracket Fracture • The breakage of ceramic brackets is a problem related to the low fracture toughness of the aluminium oxide, and the ability to resist it depends on the type and shape and the bulk of the material present. • Bracket breakage might occur either in function or in the debonding process. The internal defects and machining interference are primary causes of fracture. • Bracket-wing fracture is a frequent problem. Increased chair time and potential health risk due to the possibility of swallowing or aspirating a bracket fragment, which would be difficult to locate because of the radiolucentwww.indiandentalacademy.com nature of alumina.
Bracket Fracture • Third-order wire activations are more likely to cause ceramic bracket failure, but the fracture resistance of the ceramic brackets during arch wire torsion appears to be adequate for clinical use. (Aknin, Nanda AJO 1996) • Careful ligation is necessary and elastomeric rings, if feasible, or coated ligatures are recommended to prevent tie-wing fracture. www.indiandentalacademy.com
Bracket Fracture • Second-order wire activations do not cause ceramic bracket failure, unless the bracket has been previously weakened by a direct trauma or by surface defects during treatment.( Lindauer et al AJO1994). • Extra care should be undertaken during treatment to avoid scratching of the bracket surfaces with the instruments.
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Rebonding/ Recycling Ceramic Brackets • Gaffey et al (Angle 1995) evaluated different methods of recycling: silane coupling agent, heat plus silane coupling agent, hydrofluoric acid plus silane coupling agent, and heat plus hydrofluoric acid plus silane coupling agent. Treatment of electrothermally debonded ceramic brackets with silane or heat plus silane resulted in bond strength greater than 9 MPa, which was clinically acceptable. The use of hydrofluoric acid significantly reduced the bond strength below 2 MPa. www.indiandentalacademy.com
Rebonding Procedure • Heat: Lew and Djeng.(JCO 1990) - Brackets heated until cherry red to burn off residual composite resin. Bracket base then rinsed with 100% alcohol and left to dry. • Lew et al( EJO 1991) found that the bond strength of these recycled brackets was about 30% less than new chemically retentive ceramic brackets, yet it might maintain an acceptable bond strength and lead to fewer enamel fractures on debonding. www.indiandentalacademy.com
Rebonding mechanically retentive Brackets • The bond strength of sandblasted rebonded brackets with sealant applied on bases is adequate • Silane does not increase the bond strength of rebonded brackets. • Hydrofluoric acid treatment on sandblasted rebonded brackets significantly lowers bond strength. ( Chung ,AJO 2002) • Bond strength of recycled brackets is clinically adequate, although it is lower than that of new brackets. This weaker bond strength after "recycling" of ceramic brackets minimizes the likelihood of unwanted enamel removal during debonding. (Martina et al EJO1997). www.indiandentalacademy.com
Ceramic brackets Troubleshooting & Clinical implications
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Enamel fracture and flaking or fracture lines in enamel during debonding. • Is related to the high bond strength of ceramic brackets. • Solution A: Avoid sudden impact loading or stress concentration within the enamel by using proper debonding techniques. • The best available guidelines are those suggested by the manufacturer • Solution B: Do not bond ceramic brackets on structurally damaged teeth. • Crack lines, heavy caries, large restorations, hypoplasia and hypocalcification should be contraindications to bonding with ceramic brackets. Crowns – whether they are made of resin or porcelain – may break when ceramic brackets are debonded. Patients must be informed of this possible eventuality. www.indiandentalacademy.com
Enamel fracture and flaking or fracture lines in enamel during debonding. • Solution C: Reduce bond strength: • Add mechanical retention • Increased mechanical retention might reduce the side effects of debonding by favoring failure within the adhesive itself. • Reduce chemical adhesion • Add a metal mesh at the base of the bracket • A metal mesh at the base of the bracket would reduce bond strength to the levels observed with metal brackets. Adding the mesh, however, would mean an increase in production cost that is probably not acceptable at this time. It may also present an esthetic disadvantage. • Reduce the base area of the bracket • Reducing the bracket base area may decrease the bond strength but it does not eliminate high stress at the bond site. www.indiandentalacademy.com
Enamel fracture and flaking or fracture lines in enamel during debonding.
• Joseph and Rossouw (AJO 1990) reported a higher incidence of failure at the resin/bracket interface when original Transcend brackets (chemical retention) were bonded with lightactivated, microfilled, more brittle composite resin and increased failure within the enamel when the bracket was bonded with a chemicallycured, macrofilled, more elastic resin. • Modify the etching time and/or concentration of etching acid (H3PO4) www.indiandentalacademy.com
Enamel fracture and flaking or fracture lines in enamel during debonding.
• Use weaker resins: Iwamoto(1987) suggested that the composition of the resin influences the (tensile) strength of the bond. He reported that low-filled and highly-filled Bis-GMA resins used for bonding silane coated ceramic brackets led to higher percentages of bracket failure at the base/resin interface (80% and 90% respectively) or within the adhesive (20% and 10% respectively), than a 4 META/MMA-TBB unfilled resin. • Solution D: Debond with ultrasonic, electrothermal and laser devices www.indiandentalacademy.com
Removal of ceramic brackets by grinding • When a proper debonding technique fails, and/or risks subjecting the tooth to increased forces and fracture, grinding the ceramic bracket becomes the option of choice. • Grinding is usually conducted with high-speed diamond burs or low-speed green stones. • The procedure is time-consuming and the heat which can be generated by grinding may affect the dental pulp and, subsequently, the vitality of the tooth. www.indiandentalacademy.com
Removal of ceramic brackets by grinding • Solution: Reduce the size of ceramic to be ground by fracturing the tie wings with ligature cutting pliers, and avoid the build up of heat during grinding. • Air or water coolant must be used while grinding the bracket to avoid a rise in pulp chamber temperature. www.indiandentalacademy.com
Attrition of teeth occluding against ceramic brackets. • Solution: Select the teeth to be bonded with ceramic brackets. • The clinician must avoid bracket contact with opposing teeth. In a case with a deep anterior overbite, avoid bonding the mandibular teeth with ceramic brackets; in a case where the maxillary canine is retracted past the mandibular tooth, avoid bonding the mandibular canine. www.indiandentalacademy.com
Increased friction with ceramic brackets • Solution A: Develop brackets with smoother slot surfaces • Brackets with smoother slot surfaces, incorporated metal slots or brackets composed of ceramic and plastic may allow the archwire to slide smoothly. • Solution B: Avoid loss of anchorage and increase in overbite. • Strengthen the anchorage requirements and carefully select the teeth to be bonded. • Solution C : Avoid sliding mechanics www.indiandentalacademy.com
Breakage of ceramic brackets • Problem is due to the low fracture toughness of the aluminum oxide, affects bracket wings and occurs accidentally when cutting ligature wires or engaging a heavy archwire in the bracket. The slightest torque of such wire in the bracket interface leads to fracture. • Solution: Avoid direct contact of the brackets when cutting ligature wires and forceful engagement of increasingly heavy archwires used for leveling • Successive archwires should be fully engaged in the brackets. Also, it may be safer to avoid using ceramic brackets in people prone to trauma because of professional or numerous sports activities, such as football, martial arts or other contact sports. www.indiandentalacademy.com
Increased pain or discomfort while debonding ceramic brackets • This is related to the higher bond strength. • Solution: Have patient bite with pressure on cotton roll and/or gauze during debonding • Reactions vary from patient to patient and in an individual, may even vary from tooth to tooth and with the timing of debonding. • Pain may increase if the teeth being debonded have just undergone active movement or traumatic pressure from occlusion, elastics or other orthodontic forces www.indiandentalacademy.com
Limited rotation of teeth with ceramic brackets • Mainly affects brackets designed for mandibular incisors because they are necessarily the smallest. Incorporating four wings tends to weaken the brackets. Ceramic brackets also tend to be bulkier than metal brackets as this is required for sufficient resistance to fracture. • Solution: Further research and development • Some companies already manufacture smaller brackets with four wings but additional research is needed to develop less bulky ceramic or ceramic-like materials which can provide the properties of metal brackets with the esthetic advantages of ceramics. www.indiandentalacademy.com
Esthetic results are not absolute. • Ceramic brackets hold a definite advantage over plastic attachments, but some polycrystalline brackets do stain. This is due to individual diets – prolonged use of caffeine (coffee, tea, colas) for example, – or hygiene practices (certain mouthwashes), or lipstick, but may also be associated with the type of bonding resins used. • Solution: Avoid excessive use of staining substances and, perhaps, select least-discoloring resins • Ceramic brackets may look discolored when the brackets themselves stain (direct discoloration) or when stains on the teeth or bonding resin show through the bracket (indirect discoloration). It tends to occur with polycrystalline brackets Using two-base resins, which tend to discolor less than nomix one-step bonding resins, has been advocated www.indiandentalacademy.com
Operational risks • The primary operational risk for the patient is the accidental ingestion or aspiration of a bracket during bonding or debonding, or of bracket particles if the bracket fractures during debonding. • Ceramic brackets may not be detected on radiographs if aspired. During debonding, fractured fragments may subject the patient to oral soft tissue damage, and the patient, clinician and assistant to eye injury. • Solution: Use caution and protective equipment during bonding and debonding • Instructing the patient to bite on a cotton roll during debonding helps reduce the risk of dislodging brackets and/or fragments into the oral cavity and throat. The clinician and assistant should wear protective glasses and a mask. The patient should wear protective glasses as well, or at least keep both eyes shut. www.indiandentalacademy.com
Conclusions • Ceramic brackets became popular as esthetic appliances and have been available for clinical use for almost 2 decades! • The new designs of ceramic brackets offer excellent optical properties and the promise of additional esthetic appeal without significant functional compromises. • Ceramic brackets are durable, allow adequate force control over long treatment periods, and their risk for discoloration is minimal. www.indiandentalacademy.com
Conclusions • The introduction of ceramic brackets was a muchheralded development in the orthodontic treatment of adult patients. Their acceptance by these patients has been unprecedented in the practice of orthodontics and contributed significantly in the expansion and development of contemporary orthodontic therapeutic modalities. • However, there is still scope for improvement in some of the bracket characteristics before they are able to largely replace the use of metallic brackets, in the manner that direct bracket bonding replaced banding of teeth!! www.indiandentalacademy.com
Thank-you
Coloured ceramic brackets www.indiandentalacademy.com
REFERENCES 1)
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Karamouzos, Athanasiou, Dent, Papadopoulos. Clinical characteristics and properties of ceramic brackets: A comprehensive review . Am J Orthod Dentofac Orthop 1997;112:34-40. Eliades T, Lekka M, Eliades G, Brantley WA. Surface characterization of ceramic brackets: a multitechnique approach. Am J Orthod Dentofac Orthop 1994;105:10-8. Birnie D. Ceramic brackets. Br J Orthod 1990;17:71-5. Jost-Brinkmann PG, Radlanski RJ, Artun J, Loidl H. Risk of pulp damage due to temperature increase during thermodebonding of ceramic brackets. Eur J Orthod. 1997 Dec;19(6):623-8. www.indiandentalacademy.com
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10)Ghafari J, Skanchy TL, Mante F. Shear bond strengths of two ceramic brackets. J Clin Orthod 1992;26:491-3. 11). Joseph VP, Rossouw E. The shear bond strengths of stainless steel and ceramic brackets used with chemically and light-activated composite resins. Am J Orthod Dentofac Orthop 1990;97:121-5. 12)Kusy RP, Whitley JQ. Coefficients of friction for arch wires in stainless steel and polycrystalline alumina bracket slots: I, the dry state. Am J Orthod Dentofac Orthop 1990;98:300-12. 13). Angolkar PV, Kapila S, Duncanson MG, Nanda RS. Evaluation of friction between ceramic brackets and orthodontic wires of four alloys. Am J Orthod Dentofac Orthop 1990;98:499-506.
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14)Ghafari J. Problems associated with ceramic brackets suggest limiting their use to selected teeth. Angle Orthod 1992;62:145-52. 15) Eliades T, Viazis AD, Lekka M. Failure mode analysis of ceramic brackets bonded to enamel. Am J Orthod Dentofac Orthop 1993;104:21-6. 16)Dovgan JS, Walton RE, Bishara SE. Electrothermal debracketing of orthodontic appliances: effects on the human pulp. J Dent Res 1990;69:300. 17) Jost-Brinkmann PG, Stein H, Miethke RR, Nakata M. Histologic investigation of the human pulp after thermodebonding of metal and ceramic brackets. Am J Orthod Dentofac Orthop 1992;102:410-7. 18) Tocchio RM, Williams PT, Mayer FJ, Standing KG. Laser debonding of ceramic orthodontic brackets. Am J Orthod Dentofac Orthop 1993;103:15562. 19) Jeiroudi TM. Enamel fracture caused by ceramic brackets. Am J Orthod Dentofac Orthop 1991;99:97-9.
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20) Theodorakopoulou LP, Sadowsky PL, Jacobson A, Lacefield W Jr. Evaluation of the debonding characteristics of 2 ceramic brackets: an in vitro study. Am J Orthod Dentofacial Orthop. 2004 Mar;125(3):329-36. 21)Nishio C, da Motta AF, Elias CN, Mucha JN. In vitro evaluation of frictional forces between archwires and ceramic brackets. Am J Orthod Dentofacial Orthop. 2004 Jan;125(1):56-64 22) Hain M, Dhopatkar A, Rock P.The effect of ligation method on friction in sliding mechanics. Am J Orthod Dentofacial Orthop. 2003 Apr;123(4):416-22.
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