British Journal of Orthodontics
ISSN: 0301-228X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/yjor19
Methods of Debonding Ceramic Brackets Lindsay Winchester B.D.S., M.Sc., F.D.S., M.Orth.R.C.S. To cite this article: Lindsay Winchester B.D.S., M.Sc., F.D.S., M.Orth.R.C.S. (1992) Methods of Debonding Ceramic Brackets, British Journal of Orthodontics, 19:3, 233-237, DOI: 10.1179/ bjo.19.3.233 To link to this article: http://dx.doi.org/10.1179/bjo.19.3.233
Published online: 21 Jun 2016.
Submit your article to this journal
View related articles
Citing articles: 7 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=yjor19 Download by: [Tufts University]
Date: 29 November 2016, At: 02:49
Briti.vh Jnurnu/ of Orthodontics/ Vol. 19/1992/213-117
Trade Products News Methods of Debonding Ceramic Brackets LINDSAY WINCHESTER, B.D.S., M.Sc., F.D.S., M.ORTH.R.C.S. UMDS, Guy's Hospital, London and Queen Victoria Hospital, East Grinstead
Introduction
Attempts to produce aesthetic yet strong orthodontic appliances have led to many innovative designs. The most widely used aesthetic brackets are those manufactured from ceramics. Most of these brack~ts are made from alumina, either in monocrystalhne or polycrystalline form, of which there are n~merous bracket designs, with a variety of tiewmgs, base configurations, and methods of retention. Ceramic brackets are retained by either chemical retention, mechanical retention, or a combination of both. In vitro studies with ceramic brackets have reported extremely high bond strengths (Odegaard and Segner, 1988). The properties of ceramic brackets clearly differ from those previously used in orthodontics. They offered improved aesthetics and u~like pla~tic brackets they resist staining and discolouratiOn. Ceramics are, however, very hard and brittle. The combination of these properties and high bond strengths has led to reports of two significant problems. (1). Bracket fract~re. This '?lay occur during functton or debondmg. Ceramics are radiolucent and if swallowed or inhaled would not be visible on a radiograph. (2) Enamel fracture. This may also occur in function (Jeiroudi, 1991 ), but is of most concern du.ring debonding (Redd and Shivapuja, 1991; Wmchester, 1991 ). This is especially a problem where teeth have large restorations or are endodontically treated. The occurrence of such enamel damage on debonding has resulted in malpractice action being taken against orthodontists in America (Machen, 1990). Attempts to reduce the problems of debonding
Several studies have looked at many variables in an attempt to reduce the bond strengths of ceramics and, therefore, reduce the risk of enamel damage and bracket fracture during debonding. The length
of acid-etching (Britton et al., 1990; Storm, 1990), the type of etch including polyacrylic acid crystal g~owth (Maskeroni et al., 1990) and the use of diJ!erent types of adhesives (Eiiades et al., 1991; Wmchester, 1991) have all been unsuccessful in reducing bond strengths to the range recorded with metal brackets. Enamel fracture on debonding remains a problem. At least two suppliers (GAC International and Unitek/3M) have attempted to address this problem by modifying their product to make debonding easier and reduce the risk of enamel damage. Other manufacturers have introduced ceramic reinforced plastic brackets (Silkon, American Orthodontics· Aesthetic-line, Forestadent) which can be debonded with conventional instruments without any problems. The ability of these brackets to transmit torque and maintain their integrity over the course of treatment remains to be evaluated. T.P. Orthodontics have marketed a ceramic bracket with a polycarbonate base (Ceramaflex) which is available in straight wire and Begg. The integrity of the ceramic body/plastic base interface throughout treatment will need to be evaluated. The manufacturers claim that debonding is no problem and can be carried out with ligature cutters. Methods of debonding
Together with the wide variety of ceramic brackets there are a number of ways of debonding. Most manufacturers have their own recommendations but in every instance it is essential that all adhesiv~ flash is removed from the bracket base prior to attempting to debond. The risk of brackets shattering during debonding has already been mentioned and precautions to protect the airway and the eye~ of both patient and operator must be taken. (I) M echanica/
Some manufacturers recommend the conventional type of debonding pliers that are used in a squeez-
234 L. Winchester
ingjrotational manner. An example of this is the E.T.M. 346-RT plier which GAC recommend for removal of the Allure brackers. The brackets are bevelled on the incisal and gingival edges for easy insertion of the plier which is then slowly squeezed to remove the bracket. These brackets also have recesses in the base, so increasing the thickness of adhesive in an attempt to move the site of failure away from the vulnerable adhesive/enamel interface to the bracket/adhesive interface. A-Company have producd a debonding plier which is essentially similar, but has in addition, a replaceable shield either side of it to catch any splinters which may fly off during the process of debonding. This is particularly useful for the monocrystalline Starfire brackets which, if they do fracture, tend to fracture into many small splinters (Winchester, 1991). Unitek/3M do not recommend the use of conventional debonding tools with their Transcend ceramic brackets. The original chemically-retained Transcend ceramic brackets had to be removed using a special wrench which fitted tightly to ~he mesial and distal edges of the bracket base allowmg a sharp torsional force to be applied in a downward direction. This was often a painful experience for the patient and frequently resulted in bracket fracture leaving much of the bracket still attached to the tooth. The new Transcend Series 2000 brackets are mechanically retained and whilst still very stong in shear are significantly weaker in the tensile mode of testing (Winchester, 1992). Unitek have accordingly introduced a new debonding tool which applies a tensile force. This has been shown. to produce less enamel damage than the torqumg wrench (Redd and Shavapuja, 1991). Unitek will only guarantee the use of the bracket if de bonded in this specific way. The use of these mechanical means of debonding carries a risk of bracket fracture. This frequently results in large amounts of the bracket remaining ·attached to the enamel surface. Due to their extreme hardness removal has to be carried out using a diamond bur in a high-speed handpiece. This is obviously time consuming, can result in large fragments of ceramic fracturing off during grinding and produces a large amount of ceramic dust. The latter has been reported to be associated with itchy skin on the hands and eye irritation. It has been suggested that both operators and patients avoid wearing contact lenses during ceramic bracket grinding even in the presence of safety glasses and operators should wear gloves. It is also essential to use either water or air coolant during grinding of ceramic brackets to avoid pulpal damage due to heat generation (Vukovich et al., 1991).
BJO Vol. /9 No. 3
(2) Thermal and electrothermal
One recent development is the use of heat to reduce the force required for debonding. Lancer Orthodontics have marketed the Handi-Dri tooth dryer which is used to heat the bracket/adhesive interface by holding it 3-4 mm away from the bracket for I 015 seconds. Raising the temperature of the bracket/ adhesive interface to 52°C has been shown to reduce the force required for debonding by approximately half (Rueggenberg and Lockwood, 1990). The effectiveness of heat application to ceramic brackets which are extremely poor conductors remains suspect. A-Company have recently introduced an Electrothermal Debonding (ETD) instrument for debonding Starfire brackets. This consists of a rechargeable unit connected to a cylindrical handpiece with a heating element which elevates the temperatures of the bonding tip to 450°F. The blade fits into the vertical slot between the mesial and distal tie-wings, so transferring heat through the bracket base to the adhesive. Deformation of the adhesive together with a torsional force produces debonding. It is not recommended that the heat source should be applied for more than 5 seconds and failure to debond in this time should be abandoned. The bracket must completely cool down before a second attempt, after which alternative methods should be employed. A study by Bishara and Truelove (1990) found this method to be quick, effective and devoid of either bracket or enamel fracture. One concern with this method is the potential for pulpal damage, as a study by Zach and Cohen (1965) reported a rise in pulpal temperature to 47·7oC resulted in necrosis of 60 per cent of the teeth tested. Other possible disadvantages include the bulky nature of the handpiece which may make intra-oral use difficult, especially in the premolar region and the risk of dropping a h?t bracket in the patients' mouth. The ETD cannot m its present form be used with any other ceramic bracket. (3) Chemical aids to mechanical debonding
A recent development has been the introduction by GAC of P.De. A. (post-debonding agent). This is a derivative of peppermint oil which is available as a viscous gel in 2-ml syringes. It is applied around the bracket base and left for 2 minutes prior to debonding in the normal way. Laboratory studies have shown that a 60-second application of peppermint oil facilitates ceramic bracket removal and promotes failure at the adhesive/enamel interface, without damaging the tooth surface (Waldron, 1991 ).
BJO August /99]
(4) Other methods
Alternative methods of debonding which minimize bracket fracture and enamel damage have been reported. Ultrasonics have been used to create a purchase point within the adhesive between the bracket base and the enamel surface. This method, however, tends to be very time consuming and results in excessive wear of the expensive ultrasonic tips by the harder ceramic. The use of lasers for de bonding ceramic brackets has also been investigated (Tocchio et al., 1989) and were found to favour failure at the bracket/adhesive interface with no bracket or enamel damage. Clinical trials have not as yet been published. Summary
The problem of debonding ceramic brackets is still one which concerns the orthodontist. It is advisable to use the manufacturers recommended method of debonding each particular type of bracket. The risks of using such brackets need to be carefully assessed against the benefits. Risks can be minimized by carefully assessing the patient and the dentition, avoiding heavily restored teeth with preexisting enamel cracks. It would seem wise to obtain an informed consent from the patient having outlined the potential problems. References Bishara, S. E. and Truelove, T. S. (1990) Comparisons of different debonding techniques for ceramic brackets: an in-vitro study, Part /1. Findings and clinical implications. American Journal of Orthodontics and Dentofacial Orthopedics, 98, 263-273. Britton, J. C., Mclnnes, P., Welnberg, R., Ledoux, W. R. and Retlef, D. H. (1990) Shear bond strength of ceramic orthodontic brackets to enamel, American Journal of Orthodontics and Dentofacial Orthopedics, 98, 348-353. Eliades, T., Vlazls, A. D. and Eliades, G. (1991) Bonding of ceramic brackets to enamel: Morphologic and structural considerations, American Journal of Orthodontics and Dentofacia/ Orthopedics, 99, 369-375.
Trade Products News
235
Jeiroudi, M. T. (1991) Enamel fracture caused by ceramic brackets, American Journal of Orthodontics and Dentofacial Orthopedics, 99,97-99. Machen, D. E. (1990) Legal aspects of orthodontic practice: Risk management concepts. Ceramic bracket update, American Journal of Orthodontics and Dentofacial Orthopedics, 98,97-98. Maskeroni, A. J., Meyers, C. E. and Lorton, L. (1990) Ceramic bonding: A comparison of bond strength with polyacrylic acid and phosphoric acid enamel conditioning, American Journal of Orthodontics and Dentofacial Orthopedics, 97, 168-175. Odegaard, J. and Segner, D. (1988) Shear bond strengths of metal brackets compared with a new ceramic bracket, American Journal of Orthodontics and Dentofacial Orthopedics, 94, 201-206. Redd, T. B. and Shlvapuja, P. K. (1991) Debonding ceramic brackets: Effects on enamel, Journal of Clinical Orthodontics, 15, 475-481. Rueggenberg, F. A. and Lockwood, P. (1990) Thermal debracketing of Orthodontic resins, American Journal of Orthodontics and Dentofacial Orthopedics, 98, 56-65. Storm, E. (1990) Debonding ceramic brackets. Journal of Clinical Orthodontics, 24,91-94. Tocchlo, R., Wllllams, P. T. and Mayer F. (1989) Laser debonding of sapphire orthodontic brackets, Journal of Dental Research, 68, 993 (abstr. 1007). Vukovlch, M. E., Wood, D. P. and Daley, T. D. (1990) Heat generated by grinding during removal of ceramic brackets, American Journal of Orthodontics and Dento.facial Orthopedics, 99, 505-512. Waldren, M. (1991) An introduction into the fracture toughness of a light cured orthodontic adhesive, MSc thesis. University of London. Winchester, L. J. (1991) Bond strengths of five different ceramic brackets: an in-vitro study, European Journal of Orthodontics, 13, 293-305. Winchester, L. J. (1992) A comparison between the old Transcend and the new Transcend Series 2000 bracket, British Journal of Orthodontics, 19, 109-116. Zach, I. and Cohen, G. (1965) Pulp response to externally applied heat, Oral Surgery, Oral Medicine and Oral Pathology, 19, 515-530.
236 L. Winchester
BJO Vol. /9 No. J
Trade Product News-Appendix Forestadent Limited, 21 Carters Lane, Kiln Farm 12, Milton Keynes MK1 3HL. Tel: 0908 568922; Fax: 0908 560611 Aesthetik Line Reinforced Fibreglass Plastic Brackets can be de bonded with conventional instruments. Dentronix manufacture the classic box jointed plier, using vacuum instrument casting techniques. All instruments in this range are made from surgical grade 400 stainless steel with cobalt/carbon inserts. For debonding, models 231, 230W, and 230N are recommended. Dry heat sterilization is recommended using the DOS 5000. Alternatively, cold sterilisation can be performed using a solution containing a rust inhibitor such as Pro Cide 30. Presterilization cleaning can be carried out using MPUS solution. Forestadent's Aesthetik Line Reinforced Fibreglass Plastic Brackets were introduced into the UK in November 1990. It is available in 0·0 18 and 0·022 slot sizes. The best bond strengths have been achieved with no-mix adhesive such as Rely-a-Bond. Conventional debonding pliers can be safely used for debonding these brackets.
Hudson Limited, Hudson Building, Nunnery Drive, Sheffield S2 1TA. Twl: 0742 788515; Fax: 0742 786361 Debonding has been taken into account when designing the new Signature brackets by RMO. The bracket base is designed to fit individual teeth and provides mechanical retention. The bracket is shaped to allow the fine edge of debonding pliers to be directed to the interface between bracket and ,enamel so that the shearing force removes the oracket by breaking the seal where the bonding materal is thinnest. Mono-lok bonding adhesive is recommended for use with these brackets since it has minimum filler content.
Oradent Limited, Eton Square, Eton, Windsor, Berks SL4 6BQ. Tel: 0753 857714/5; Telex: 848767 ORADEN G GAC have introduced a number of changes to their ceramic bracket design which influences the method of debonding. The bases of the current brackets have a reverse chamfer leaving an undercut between the bracket base and the tooth surface. Before
debonding the brackets, GAC recommend that any adhesive residue surrounding the occlusaljgingival edges of the bracket base should be removed with a carbide bur. Whether a debonding ptier or ligature cutter is used to debond the bracket, it is important to ensure that the blades of the instrument are placed at the occlusaljgingival edges of the bracket/ tooth interface. P.De. A is a new development in bracket debonding. P.De. A is a green viscous solution which is applied to the margins of ceramic brackets to facilitate debonding. Any adhesive residue remaining on the enamel following debonding can also be more easily removed if P.De. A is applied to the remnants first. Ortho-care UK Ltd, 5 Oxford Place, Bradford, West Yorkshire BD3 OEF. Tel: 0274 392017; Fax: 0274 734446 Ortho-care supply the Lancer Handi-dry which can be used for thermal debonding of ceramic brackets. The handi-dry is used by simply holding the blow tip 3-4 mm from the tooth whilst directing the hot air at the bracket for 10-15 seconds. Raising the temperature of the bracket/adhesive interface to 52°C has been shown to reduce the force required for debonding by approximately half. The maximum temperature of the dry air stream is 65°C which is less than that of a hot drink, and is well tolerated by patients. It is also believed to reduce the sensitivity and discomfort of debonding. This low cost unit may also be used on metal brackets, for drying teeth prior to bonding and for speeding up setting time of bonding adhesives and cements. Orthologic, Summit House, Summit Road, Potters Bar, Herts EN6 3EE. Tel: 0707 46434/5; Fax: 0707 46429 The Electro Thermal De-Bonder (ETD) from Acompany has been specially designed to safely debond A-Company Starfire TMB brackets. The ETD works by applying enough heat to the bracket to elevate the temperature of the adhesive/bracket interface to the point at which only a small amount of torsional force is required for bracket removal. The heat is transferred rapidly the bracket and adhesive allowing the bracket to be removed before any significant amount of heat reaches the dental pulp.
BJO August 1991
Orthomax, Bankfield House, Carbottom Road, Bradford BD5 9BJ. Tel: 0274 733842; Fax: 0274 307871
3M Unitek's Transcend Ceramic Bracket Series 2000 has been developed to overcome the problems of de bonding. The crystalline base of Transcend 2000 provides mechanical rather than chemical retention. This mechanical retention enables the bracket to be debonded at the adhesive/bracket base interface as is the case with mesh based stainless steel brackets, rather than at the enamel/adhesive interface which helps to eliminate the possibility of enamel damage
Trade Products News
237
during the debonding process, whilst maintaining adequate bond strength throughout .treatment.. . When debonding Transcend Senes 2000, 1t IS important to use the specially designed debonding instrument which utilizes a reciprocal force between the bracket wing and the labial surface of the tooth producing minimum discomfort f~r t~e patient. Failure to use the correct debondmg mstrument may lead to enamel damage or fractured tie-wings. A Transcend Series 2000 video is available showing the correct debonding technique. For further information, please contact Orthomax, address, telephone, and fax number supplied above.
ISSN: 0301-228X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/yjor19
Methods of Debonding Ceramic Brackets Lindsay Winchester B.D.S., M.Sc., F.D.S., M.Orth.R.C.S. To cite this article: Lindsay Winchester B.D.S., M.Sc., F.D.S., M.Orth.R.C.S. (1992) Methods of Debonding Ceramic Brackets, British Journal of Orthodontics, 19:3, 233-237, DOI: 10.1179/ bjo.19.3.233 To link to this article: http://dx.doi.org/10.1179/bjo.19.3.233
Published online: 21 Jun 2016.
Submit your article to this journal
View related articles
Citing articles: 7 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=yjor19 Download by: [Tufts University]
Date: 29 November 2016, At: 02:49
Briti.vh Jnurnu/ of Orthodontics/ Vol. 19/1992/213-117
Trade Products News Methods of Debonding Ceramic Brackets LINDSAY WINCHESTER, B.D.S., M.Sc., F.D.S., M.ORTH.R.C.S. UMDS, Guy's Hospital, London and Queen Victoria Hospital, East Grinstead
Introduction
Attempts to produce aesthetic yet strong orthodontic appliances have led to many innovative designs. The most widely used aesthetic brackets are those manufactured from ceramics. Most of these brack~ts are made from alumina, either in monocrystalhne or polycrystalline form, of which there are n~merous bracket designs, with a variety of tiewmgs, base configurations, and methods of retention. Ceramic brackets are retained by either chemical retention, mechanical retention, or a combination of both. In vitro studies with ceramic brackets have reported extremely high bond strengths (Odegaard and Segner, 1988). The properties of ceramic brackets clearly differ from those previously used in orthodontics. They offered improved aesthetics and u~like pla~tic brackets they resist staining and discolouratiOn. Ceramics are, however, very hard and brittle. The combination of these properties and high bond strengths has led to reports of two significant problems. (1). Bracket fract~re. This '?lay occur during functton or debondmg. Ceramics are radiolucent and if swallowed or inhaled would not be visible on a radiograph. (2) Enamel fracture. This may also occur in function (Jeiroudi, 1991 ), but is of most concern du.ring debonding (Redd and Shivapuja, 1991; Wmchester, 1991 ). This is especially a problem where teeth have large restorations or are endodontically treated. The occurrence of such enamel damage on debonding has resulted in malpractice action being taken against orthodontists in America (Machen, 1990). Attempts to reduce the problems of debonding
Several studies have looked at many variables in an attempt to reduce the bond strengths of ceramics and, therefore, reduce the risk of enamel damage and bracket fracture during debonding. The length
of acid-etching (Britton et al., 1990; Storm, 1990), the type of etch including polyacrylic acid crystal g~owth (Maskeroni et al., 1990) and the use of diJ!erent types of adhesives (Eiiades et al., 1991; Wmchester, 1991) have all been unsuccessful in reducing bond strengths to the range recorded with metal brackets. Enamel fracture on debonding remains a problem. At least two suppliers (GAC International and Unitek/3M) have attempted to address this problem by modifying their product to make debonding easier and reduce the risk of enamel damage. Other manufacturers have introduced ceramic reinforced plastic brackets (Silkon, American Orthodontics· Aesthetic-line, Forestadent) which can be debonded with conventional instruments without any problems. The ability of these brackets to transmit torque and maintain their integrity over the course of treatment remains to be evaluated. T.P. Orthodontics have marketed a ceramic bracket with a polycarbonate base (Ceramaflex) which is available in straight wire and Begg. The integrity of the ceramic body/plastic base interface throughout treatment will need to be evaluated. The manufacturers claim that debonding is no problem and can be carried out with ligature cutters. Methods of debonding
Together with the wide variety of ceramic brackets there are a number of ways of debonding. Most manufacturers have their own recommendations but in every instance it is essential that all adhesiv~ flash is removed from the bracket base prior to attempting to debond. The risk of brackets shattering during debonding has already been mentioned and precautions to protect the airway and the eye~ of both patient and operator must be taken. (I) M echanica/
Some manufacturers recommend the conventional type of debonding pliers that are used in a squeez-
234 L. Winchester
ingjrotational manner. An example of this is the E.T.M. 346-RT plier which GAC recommend for removal of the Allure brackers. The brackets are bevelled on the incisal and gingival edges for easy insertion of the plier which is then slowly squeezed to remove the bracket. These brackets also have recesses in the base, so increasing the thickness of adhesive in an attempt to move the site of failure away from the vulnerable adhesive/enamel interface to the bracket/adhesive interface. A-Company have producd a debonding plier which is essentially similar, but has in addition, a replaceable shield either side of it to catch any splinters which may fly off during the process of debonding. This is particularly useful for the monocrystalline Starfire brackets which, if they do fracture, tend to fracture into many small splinters (Winchester, 1991). Unitek/3M do not recommend the use of conventional debonding tools with their Transcend ceramic brackets. The original chemically-retained Transcend ceramic brackets had to be removed using a special wrench which fitted tightly to ~he mesial and distal edges of the bracket base allowmg a sharp torsional force to be applied in a downward direction. This was often a painful experience for the patient and frequently resulted in bracket fracture leaving much of the bracket still attached to the tooth. The new Transcend Series 2000 brackets are mechanically retained and whilst still very stong in shear are significantly weaker in the tensile mode of testing (Winchester, 1992). Unitek have accordingly introduced a new debonding tool which applies a tensile force. This has been shown. to produce less enamel damage than the torqumg wrench (Redd and Shavapuja, 1991). Unitek will only guarantee the use of the bracket if de bonded in this specific way. The use of these mechanical means of debonding carries a risk of bracket fracture. This frequently results in large amounts of the bracket remaining ·attached to the enamel surface. Due to their extreme hardness removal has to be carried out using a diamond bur in a high-speed handpiece. This is obviously time consuming, can result in large fragments of ceramic fracturing off during grinding and produces a large amount of ceramic dust. The latter has been reported to be associated with itchy skin on the hands and eye irritation. It has been suggested that both operators and patients avoid wearing contact lenses during ceramic bracket grinding even in the presence of safety glasses and operators should wear gloves. It is also essential to use either water or air coolant during grinding of ceramic brackets to avoid pulpal damage due to heat generation (Vukovich et al., 1991).
BJO Vol. /9 No. 3
(2) Thermal and electrothermal
One recent development is the use of heat to reduce the force required for debonding. Lancer Orthodontics have marketed the Handi-Dri tooth dryer which is used to heat the bracket/adhesive interface by holding it 3-4 mm away from the bracket for I 015 seconds. Raising the temperature of the bracket/ adhesive interface to 52°C has been shown to reduce the force required for debonding by approximately half (Rueggenberg and Lockwood, 1990). The effectiveness of heat application to ceramic brackets which are extremely poor conductors remains suspect. A-Company have recently introduced an Electrothermal Debonding (ETD) instrument for debonding Starfire brackets. This consists of a rechargeable unit connected to a cylindrical handpiece with a heating element which elevates the temperatures of the bonding tip to 450°F. The blade fits into the vertical slot between the mesial and distal tie-wings, so transferring heat through the bracket base to the adhesive. Deformation of the adhesive together with a torsional force produces debonding. It is not recommended that the heat source should be applied for more than 5 seconds and failure to debond in this time should be abandoned. The bracket must completely cool down before a second attempt, after which alternative methods should be employed. A study by Bishara and Truelove (1990) found this method to be quick, effective and devoid of either bracket or enamel fracture. One concern with this method is the potential for pulpal damage, as a study by Zach and Cohen (1965) reported a rise in pulpal temperature to 47·7oC resulted in necrosis of 60 per cent of the teeth tested. Other possible disadvantages include the bulky nature of the handpiece which may make intra-oral use difficult, especially in the premolar region and the risk of dropping a h?t bracket in the patients' mouth. The ETD cannot m its present form be used with any other ceramic bracket. (3) Chemical aids to mechanical debonding
A recent development has been the introduction by GAC of P.De. A. (post-debonding agent). This is a derivative of peppermint oil which is available as a viscous gel in 2-ml syringes. It is applied around the bracket base and left for 2 minutes prior to debonding in the normal way. Laboratory studies have shown that a 60-second application of peppermint oil facilitates ceramic bracket removal and promotes failure at the adhesive/enamel interface, without damaging the tooth surface (Waldron, 1991 ).
BJO August /99]
(4) Other methods
Alternative methods of debonding which minimize bracket fracture and enamel damage have been reported. Ultrasonics have been used to create a purchase point within the adhesive between the bracket base and the enamel surface. This method, however, tends to be very time consuming and results in excessive wear of the expensive ultrasonic tips by the harder ceramic. The use of lasers for de bonding ceramic brackets has also been investigated (Tocchio et al., 1989) and were found to favour failure at the bracket/adhesive interface with no bracket or enamel damage. Clinical trials have not as yet been published. Summary
The problem of debonding ceramic brackets is still one which concerns the orthodontist. It is advisable to use the manufacturers recommended method of debonding each particular type of bracket. The risks of using such brackets need to be carefully assessed against the benefits. Risks can be minimized by carefully assessing the patient and the dentition, avoiding heavily restored teeth with preexisting enamel cracks. It would seem wise to obtain an informed consent from the patient having outlined the potential problems. References Bishara, S. E. and Truelove, T. S. (1990) Comparisons of different debonding techniques for ceramic brackets: an in-vitro study, Part /1. Findings and clinical implications. American Journal of Orthodontics and Dentofacial Orthopedics, 98, 263-273. Britton, J. C., Mclnnes, P., Welnberg, R., Ledoux, W. R. and Retlef, D. H. (1990) Shear bond strength of ceramic orthodontic brackets to enamel, American Journal of Orthodontics and Dentofacial Orthopedics, 98, 348-353. Eliades, T., Vlazls, A. D. and Eliades, G. (1991) Bonding of ceramic brackets to enamel: Morphologic and structural considerations, American Journal of Orthodontics and Dentofacia/ Orthopedics, 99, 369-375.
Trade Products News
235
Jeiroudi, M. T. (1991) Enamel fracture caused by ceramic brackets, American Journal of Orthodontics and Dentofacial Orthopedics, 99,97-99. Machen, D. E. (1990) Legal aspects of orthodontic practice: Risk management concepts. Ceramic bracket update, American Journal of Orthodontics and Dentofacial Orthopedics, 98,97-98. Maskeroni, A. J., Meyers, C. E. and Lorton, L. (1990) Ceramic bonding: A comparison of bond strength with polyacrylic acid and phosphoric acid enamel conditioning, American Journal of Orthodontics and Dentofacial Orthopedics, 97, 168-175. Odegaard, J. and Segner, D. (1988) Shear bond strengths of metal brackets compared with a new ceramic bracket, American Journal of Orthodontics and Dentofacial Orthopedics, 94, 201-206. Redd, T. B. and Shlvapuja, P. K. (1991) Debonding ceramic brackets: Effects on enamel, Journal of Clinical Orthodontics, 15, 475-481. Rueggenberg, F. A. and Lockwood, P. (1990) Thermal debracketing of Orthodontic resins, American Journal of Orthodontics and Dentofacial Orthopedics, 98, 56-65. Storm, E. (1990) Debonding ceramic brackets. Journal of Clinical Orthodontics, 24,91-94. Tocchlo, R., Wllllams, P. T. and Mayer F. (1989) Laser debonding of sapphire orthodontic brackets, Journal of Dental Research, 68, 993 (abstr. 1007). Vukovlch, M. E., Wood, D. P. and Daley, T. D. (1990) Heat generated by grinding during removal of ceramic brackets, American Journal of Orthodontics and Dento.facial Orthopedics, 99, 505-512. Waldren, M. (1991) An introduction into the fracture toughness of a light cured orthodontic adhesive, MSc thesis. University of London. Winchester, L. J. (1991) Bond strengths of five different ceramic brackets: an in-vitro study, European Journal of Orthodontics, 13, 293-305. Winchester, L. J. (1992) A comparison between the old Transcend and the new Transcend Series 2000 bracket, British Journal of Orthodontics, 19, 109-116. Zach, I. and Cohen, G. (1965) Pulp response to externally applied heat, Oral Surgery, Oral Medicine and Oral Pathology, 19, 515-530.
236 L. Winchester
BJO Vol. /9 No. J
Trade Product News-Appendix Forestadent Limited, 21 Carters Lane, Kiln Farm 12, Milton Keynes MK1 3HL. Tel: 0908 568922; Fax: 0908 560611 Aesthetik Line Reinforced Fibreglass Plastic Brackets can be de bonded with conventional instruments. Dentronix manufacture the classic box jointed plier, using vacuum instrument casting techniques. All instruments in this range are made from surgical grade 400 stainless steel with cobalt/carbon inserts. For debonding, models 231, 230W, and 230N are recommended. Dry heat sterilization is recommended using the DOS 5000. Alternatively, cold sterilisation can be performed using a solution containing a rust inhibitor such as Pro Cide 30. Presterilization cleaning can be carried out using MPUS solution. Forestadent's Aesthetik Line Reinforced Fibreglass Plastic Brackets were introduced into the UK in November 1990. It is available in 0·0 18 and 0·022 slot sizes. The best bond strengths have been achieved with no-mix adhesive such as Rely-a-Bond. Conventional debonding pliers can be safely used for debonding these brackets.
Hudson Limited, Hudson Building, Nunnery Drive, Sheffield S2 1TA. Twl: 0742 788515; Fax: 0742 786361 Debonding has been taken into account when designing the new Signature brackets by RMO. The bracket base is designed to fit individual teeth and provides mechanical retention. The bracket is shaped to allow the fine edge of debonding pliers to be directed to the interface between bracket and ,enamel so that the shearing force removes the oracket by breaking the seal where the bonding materal is thinnest. Mono-lok bonding adhesive is recommended for use with these brackets since it has minimum filler content.
Oradent Limited, Eton Square, Eton, Windsor, Berks SL4 6BQ. Tel: 0753 857714/5; Telex: 848767 ORADEN G GAC have introduced a number of changes to their ceramic bracket design which influences the method of debonding. The bases of the current brackets have a reverse chamfer leaving an undercut between the bracket base and the tooth surface. Before
debonding the brackets, GAC recommend that any adhesive residue surrounding the occlusaljgingival edges of the bracket base should be removed with a carbide bur. Whether a debonding ptier or ligature cutter is used to debond the bracket, it is important to ensure that the blades of the instrument are placed at the occlusaljgingival edges of the bracket/ tooth interface. P.De. A is a new development in bracket debonding. P.De. A is a green viscous solution which is applied to the margins of ceramic brackets to facilitate debonding. Any adhesive residue remaining on the enamel following debonding can also be more easily removed if P.De. A is applied to the remnants first. Ortho-care UK Ltd, 5 Oxford Place, Bradford, West Yorkshire BD3 OEF. Tel: 0274 392017; Fax: 0274 734446 Ortho-care supply the Lancer Handi-dry which can be used for thermal debonding of ceramic brackets. The handi-dry is used by simply holding the blow tip 3-4 mm from the tooth whilst directing the hot air at the bracket for 10-15 seconds. Raising the temperature of the bracket/adhesive interface to 52°C has been shown to reduce the force required for debonding by approximately half. The maximum temperature of the dry air stream is 65°C which is less than that of a hot drink, and is well tolerated by patients. It is also believed to reduce the sensitivity and discomfort of debonding. This low cost unit may also be used on metal brackets, for drying teeth prior to bonding and for speeding up setting time of bonding adhesives and cements. Orthologic, Summit House, Summit Road, Potters Bar, Herts EN6 3EE. Tel: 0707 46434/5; Fax: 0707 46429 The Electro Thermal De-Bonder (ETD) from Acompany has been specially designed to safely debond A-Company Starfire TMB brackets. The ETD works by applying enough heat to the bracket to elevate the temperature of the adhesive/bracket interface to the point at which only a small amount of torsional force is required for bracket removal. The heat is transferred rapidly the bracket and adhesive allowing the bracket to be removed before any significant amount of heat reaches the dental pulp.
BJO August 1991
Orthomax, Bankfield House, Carbottom Road, Bradford BD5 9BJ. Tel: 0274 733842; Fax: 0274 307871
3M Unitek's Transcend Ceramic Bracket Series 2000 has been developed to overcome the problems of de bonding. The crystalline base of Transcend 2000 provides mechanical rather than chemical retention. This mechanical retention enables the bracket to be debonded at the adhesive/bracket base interface as is the case with mesh based stainless steel brackets, rather than at the enamel/adhesive interface which helps to eliminate the possibility of enamel damage
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during the debonding process, whilst maintaining adequate bond strength throughout .treatment.. . When debonding Transcend Senes 2000, 1t IS important to use the specially designed debonding instrument which utilizes a reciprocal force between the bracket wing and the labial surface of the tooth producing minimum discomfort f~r t~e patient. Failure to use the correct debondmg mstrument may lead to enamel damage or fractured tie-wings. A Transcend Series 2000 video is available showing the correct debonding technique. For further information, please contact Orthomax, address, telephone, and fax number supplied above.
