- Email: [email protected]
Clinical experience with the acid-etch technique in orthodontics
Clinical experPiencewith the acid-etch technique in orthodontics D. H. Retief
and
Johannesburg,
P. 1. Sadowsky
South Africa
T
he lack of adhesion of dental materials to tooth structure is a major problem in dentistry.= Buonocore2 was the first to demonstrate that the bonding of acrylic filling materials to enamel could be substantially increased by conditioning the enamel surface with 85 per cent phosphoric acid. The acid-etch technique is now an accepted procedure in dentistry and widely applied in restorative and preventive dentistry and for the direct bonding of orthodontic attachments. The initial research efforts were concerned with the evaluation of existing dental materials for the direct bonding of orthodontic attachments31 * but subsequently various resin systems were developed for this purpose.5v G These resin systems were subjected to limited clinical evaluation.7* 8 With the advent of improved resin systems and a better understanding of the mechanism of action of phosphoric acid etching, the direct bonding of orthodontic attachments has become a practical clinical procedure.9-13 In this article, we present our experience with a direct-bonding system used in conjunction with the acid-etch technique and report on the clinical results obtained on a cross-section of the patients treated by them. The development
and pilot clinical evaluation
of a direct bonding
system
The bonding system. An epoxy resin formulation was developed for the direct bonding of orthodontic attachments .6 The composition of the formulation is as follows : Part
Part
I
II
Epikote Aerosilt
828*
Epikure Phenol
U*
1.0 ml. (1.12 mg.
Gm.)
0.3 ml. (0.31 70 mg.
Gm.)
140
From the Dental Research Unit of the University of the Witwatersrancl and the South African Medical Research Council (Dr. Retief) and Department of Orthodontics, School of Dentistry, University of the Witwatersrand (Dr. Sadowsky). *Shell tDegussa,
Chemical
S.A.
Frankfurt,
(Pty.), West
Ltd.,
Johannesburg,
Republic
of South
Africa.
Germany.
645
646
Retief
and Sadowsky
Fig. 1. Orthodontic attachments protected with Alastik rings.
welded
to
band
material
with
gauze
backing.
Flanges
Epikote 828 is a general-purpose epoxy resin and Epikure IJ is a modified polyamine curing agent. Aerosil is a thixotropic agent consisting of fine particles of silicon dioxide and was added to reduce the flow of the curing epoxy resin on inclined surfaces. Attachments bonded with this formulation maintained their desired positions on tooth surfaces after placement. Phenol is a catalyst and was added to accelerate the curing rate of the bonding system on the tooth surface. was too long for clinical application. The setting time of this formulation The rate of cure of epoxy resins is accelerated by heat, and the optimal preheat schedule for this formulation was determined. It was found that maximal tensile bond strengths to etched enamel surfaces were obtained by preheating the mixed resin at 50° C. for 6 minutes.8 The attachments. The epoxy resin formulation did not adhere to stainless steel under simulated intraoral conditions. Special stainless steel attachments were made to overcome this problem.6 Sixty-mesh stainless steel gauze was welded to the fitting surface of stainless steel orthodontic band material (0.006 x 0.220 inch). An edgewise orthodontic bracket was then welded to the center of this reinforced band material, the edges of the base were trimmed, and the base was contoured to fit the curvature of the tooth to be bonded. Adequate mechanical retention of the epoxy resin to stainless steel was achieved in this way (Fig. 1). The etching agent. Phosphoric acid is commonly used as a conditioning solution to obtain increased bonding of dental materials to tooth surfaces. Concentrations ranging from 3714 to 65 per cenF phosphoric acid are being supplied with commercial resin systems. The optimal concentration of phosphoric acid for the epoxy resin formulation was determined by evaluating the tensile bond strength, depth of etch, and surface roughness of etched enamel surfaces. It was found that 50 per cent phosphoric acid was the most suitab1e.l’ Bonding of attachments. The four components of the resin formulation were mixed on a glass slab and the mixture was spread evenly to allow dissipation of the exothermic heat; the prepared attachments were embedded in the resin; the slab and its contents were preheated in an oven at 50° C. for 6 minutes.
Volume Number
Acid-etch
68 6
technique in orthodontics
E 13M
D 11M
- ri--
1111 x!lLJ
Fig. 2. Teeth bonded in the pilot study. treatment; a cross, failure of a bonded
647
Patients attachment.
A to
H.
A dot
indicates
completion
of
In the meantime, the teeth to be bonded were cleaned with pumice and a rubber cup, etched with 50 per cent phosphoric acid for 1 minute, and washed well. The teeth were dried and the attachments placed on the teeth in the desired positions. Six attachments could readily be bonded with one mix. The bonded attachments were kept dry for 15 minutes. At the subsequent visit the excess material was removed and the arch wires were ligated. Pilot study. Eight patients were treated in the preliminary clinical trial and fifty-eight teeth were bonded. The duration of treatment ranged from 3 to 48 months (Fig. 2). The treatment method employed was a modified edgewise technique and the number of bonded attachments per patient ranged from one (Patients A and H) to 15 (Patient E). The malocclusicms treated included premolar extraction cases, anterior cross-bites, a Class II, Division 1, malocclusion in which a headgear was utilized (Fig. 3), and a partially erupted canine in a cleft-palate patient (Fig. 4). During the treatment of these patients fourteen bonded attachments became dislodged, nine before active orthodontic tooth movement was commenced. A failure rate of 24 per cent was calculated. Eleven of the dislodged attachments were rebonded and, of these, four failed again during treatment (Fig. 2). Definitive
clinicul
study
with
the
epoxy
resin
fomulation
Introduction. With experience obtained during the pilot study, certain modifications were introduced. The drying of the etched enamel surfaces prior to bonding was facilitated by using a commercially available drying agent, Prep-
648
Am. J. Orthod. December 197;
Retief and Sadowsky
Fig. 3. Headgear in patient with bonded Fig. 4. initial treatment of a partially
attachments. erupted
canine
by
means
of
a
removable
ap-
pliance.
Dry.” A rubber dam made the technique cumbersome and was not used. Alastikt rings were placed around the bracket flanges to prevent flow of excess resin beneath these flanges (Fig. 1). Subsequent laboratory tests, including tensile bond strengths, surfaceroughness measurements of etched enamel surfaces, ra,te of etching, and contact angle measurements, suggested that 50 per cent phosphoric acid attenuated with 7 per cent zinc oxide by weight was a more effective conditioning agent than the unbuffered 50 per cent phosphoric acid solution.” It was not found necessary to etch enamel surfaces for longer than 1 minute with the attenuated phosphoric acid solution. CZi&~Z study. In these clinical trials fifteen patients were treated and 123 attachments were bonded. The duration of treatment ranged from 5 to 35 months (Figs. 5 and 6). Twenty-three of the attachments became dislodged, seven prior to the application of orthodontic forces. Twelve were rebonded, and only one of these failed before completion of treatment. A failure rate of 18.8 per cent was recorded. The malocclusions treated in this study included crowding and spacing problems, premolar extraction cases, anterior cross-bites, and labially situated maxillary canines. From our clinical series of cases, the treatment of four patients-T, U, V, and W-in Fig. 6 will be described in more detail. Patient T. This patient was 23 years old and had a Class II. Division 1, malocclusion (Fig. 7). The lower first premolars had been extracted previously at an early age. The upper first premolars were extracted, and attachments were bonded to the remaining teeth in both arches from central incisor t,o first molar. The lower arch was corrected with round arch wires only, while a rectangular closing loop arch wire was used to close the extraction spaces in the maxillary arch. Active treatment extended over a period of approximately 1 year and *Lee tUnitek
Pharmaceuticals, Corporation,
South Monrovia,
El Monte, Calif.
Calif. 91016.
91733.
Volume
Number
68
Acid-etch
6
techwique in orthodontics
649 s 14hl
a
P
Q
12M
12M
11M ?’
M K
L
Fig. 5. Definitive
8M
clinical
study,
Patients
I to S.
V
T
Ol-
Fig. 6. Definitive
clinical
-
I &
Bol
ad
study,
Patients
T to W.
650
Retief
Fig.
7.
Fig.
8. Patient
Fig.
9. Study
a,nd Saclowsky
Initial
study
models
T during models
of
active
Patient
at completion
Fig.
10. Surgically
Fig.
11.
Patient
U during
exposed
Fig.
12.
Patient
U at completion
Headgear
of treatment
maxillary active
T.
treatment.
left
central
in place. in Patient incisor
T.
in Patient
U.
treatment. of treatment.
extraoral traction to the maxillary arch was utilized for approximately 5 months (Fig. 8). Two bonded attachments were lost prior to areh placement. These teeth were rebonded and no further attachments became dislodged during treatment. The result obtained at completion of treatment is shown in Fig. 9. Patient 77. A 14-year-old boy with a mild Class II, Division 1, malocclusion also had an unerupted maxillary left central incisor which required surgical exposure (Fig. 10). Bonded attachments were fitted to the upper six anterior
Volume Number
68 6
Acid-etch
technique
in orthodontics
651
teeth. Conventional bands were cemented to the maxillary first molars with extraoral traction (Fig. 11). A modified edgewise technique was utilized and no bonded attachments became dislodged during the treatment, which extended over 12 months. The result at completion of treatment is shown in Fig. 12. Although the gingival margin of the initially malposed incisor is more apical than the contralateral tooth, the result was considered satisfactory in view of its original position in the buccal sulcus (Fig. 10). Patient V. Patient V was an U-year-old girl who required surgical exposure of the labial surface of the maxillary left canine tooth (Figs. 13 and 14). Attachments were bonded to the labial surfaces of these teeth and initial removable appliance therapy was instituted. When the canines had been moved to a more satisfactory position within the arch, the maxillary incisor teeth were bonded. In order to correct undesired rotations, a new commercially available direct-bonding material was used to place lingual attachments on the maxillary left canine and second premolar teeth. A modified edgewise technique was utilized (Fig. 15) and the treatment extended over approximately two years. Just prior to the completion of treatment, one bonded attachment became dislodged and did not require replacement. Completed study models are shown in Fig. 16. Patie& W. This patient was a 15-year-old girl who had a Class II, Division 1, malocclusion with severe crowding in the lower arch (Fig. 17). The second premolar teeth were extracted in both arches, and attachments were bonded to all the remaining teeth except the second molars. A modified edgewise technique was utilized (Fig. 18). A Rampton type of headgear was used to reinforce maxillary posterior anchorage (Fig. 19). Study models at the completion of treatment are shown (Fig. 20). A preliminary
clinical
evaluation
of
a commercial
composite
direct
bonding
material
The clinical studies described in this article extended over a period of 7 years. Recently several materials for the direct bonding of orthodontic attachments have become commercially available. Initial laboratory studies have shown excellent bond strengths of these composite materials to etched enamel surfaces under simulated intraoral conditions. It was therefore decided to commence clinical trials with one of these bonding agents. The material selected was Genie,* and more than fifty attachments have been bonded in nine patients with differing types of malocclusion. These attachments have been in place for periods ranging from 3 to 12 months. To date, only one attachment has become dislodged. These clinical trials are proceeding and are being extended. Suggestions
for
the
direct
bonding
technique
As a result of our clinical experience with the direct bonding attachments, we offer some suggestions which may prove helpful : *Lee
Pharmaceuticals,
South
El Monte,
Calif.
91733.
of orthodontic
652
TZetief and Xadowsky
Fig.
13.
Fig.
14. Surgical
Patient
V at
exposure
of maxillary
Fig.
15.
Patient
V during
active
Fig.
16.
Study
Fig.
17.
Occlusal
Fig.
18.
Patient
Fig.
19.
Reinforcement
fig.
20.
Study
models
presentation
of
view W models
Patient of
during
study active
of maxillary at completion
for
treatment. left
canine
in Patient
V.
treatment. V at completion models
of
of treatment.
Patient
W.
treatment. anchorage of treatment
in Patient of Patient
W. W.
Volume Number
68 6
Acid-etch
technique
in orth,odmtics
653
1. To prevent excess adhesive from flowing beneath the flanges of the attachments, these may be protected with Alastik rings prior to the placement of the attachments (Fig. 1). 2. Lip retractors* were found to be of great help in keeping the mouth open and the lips and cheeks away from the bonded attachments. 3. Topical fluoride therapy should be deferred until the attachments have been bonded. The effect of etching agents is reduced on enamel surfaces treated with topical fluoride agents18 4. It is not necessary to etch for longer than 2 minutes. The etching solution should be confined to the area where the attachment is to be positioned. Excess acid may cause sloughing of the gingivae. 5. The use of a water repellent is advocated to keep the etched surfaces dry. Commercial water repellents are available. 6. Effective suction is essential to keep the mouth dry. 7. The application of a rubber dam is not necessary if adequate precautions are taken to maintain a dry field. 8. A trained assistant is essential. It is impossible for one person to mix the bonding resin and keep the mouth adequately dry at the same time. 9. Dabbing of the bonded attachments with cotton-wool pledgets soaked in chloroform prior to the removal of the bonded attachments may facilitate removal of these attachments. Advantages
of “bandless”
orthodontics
1. Gingival irritation is decreased because the bonded attachments do not impinge on the gingival margins. 2. It has been our experience that the oral hygiene of patients with bonded brackets is improved. This is a subjective conclusion. 3. When teeth are crowded it becomes imperative to separate the teeth prior to the fitting and cementing of bands. This procedure is obviously not necessary with the direct bonding technique. Another factor is the impingement on arch length by the interproximal band thickness. This is in the order of t4 mm.12 and there are times when this additional space is most welcome during orthodontic treatment. 4. Conventional banding of partially erupted teeth is often difficult and traumatic for the patient. The direct bonding of attachments to the exposed surfaces of these teeth presents no problems. 5. The last stage of orthodontic treatment may be devoted to space closure after removal of bands. No space closure is required with directly bonded attachments. 6. Orthodontic bands may become loose and remain undetected during treatment. As a result, decalcification may occur under these bands.lg The problem is not encountered with the direct-bonding technique because loosening of the attachments results in complete displacement. “O.I.S.,
P. 0. Box
2074,
Wilmington,
Del.
19899.
654
Retief
and Xadowsky
Conclusion
The acid-etch technique and the development of improved composite resin systems have made the direct bonding of orthodontic attachments an accepted clinical procedure. This technique can be used with confidence as an adjunct in the armamentarium of the orthodontist. REFERENCES
1. Phillips, R. W.: Advancements in adhesive restorative dental materials, J. Dent. Res. 45: 1662-1667, 1966. 2. Buonocore, M. G.: A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces, J. Dent. Res. 34: 849-853, 1955. 3. Swanson, L. T., and Beck, J. F. : Factors affecting bonding to human enamel with special reference to a plastic adhesive, J. Am. Dent. Assoc. 61: 581-586, 1960. 4. Mitchell, D. L. : Bandless orthodontic bracket, J. Am. Dent. Assoc. 74: 103-110, 1967. 5. Newman, G. V.: Epoxy adhesives for orthodontic attachments: Progress report, Arvr. J. ORTHOD. 51: 901-912, 1965. resins for bonding orthodontic attachments to 6. Retief, D. H., and Dreyer, C. J.: Epoxy teeth, J. Dent. Assoc. 5. Afr. 22: 338-346, 1967. 7. Newman, G. V.: Adhesion and plastic orthodontic att,achments, AM. J. ORTHOD. 56: 573-588, 1969. 8. Retief, D. H., Dreyer, C. J., and Gavron, G.: The direct bonding of orthodontic attachments to teeth by means of an epoxy resin adhesive, AE~. J. ORTHOD. 58: 21-40, 1970. 9. Miura, F., Nakagawa, K., and Mashuhara, F.: New direct bonding system for plastic brackets, AM. J. ORTHOD. 59: 350.361, 1971. 10. Cohl, M. E., Green, L. J., and Eick, J. D.: Bonding of clear plastic orthodontic brackets using an ultraviolet-sensitive adhesive, A&f, J. ORTHOD. 62: 400-411, 1972. 11. Silverman, E., Cohen, M., Gianelly, A. A., and Dietz, V. S.: A universal direct bonding system for both metal and plastic brackets, Anf. J. ORTHOD. 62: 236-244, 1972. 12. Daft, K. S., and Lugassy, A. A.: A preliminary study of orthodontic treatment with the use of directly bonded attachments, AM. J. ORTHOD. 65: 407-418, 1974. 13. Silverman, E., and Cohen, M.: Current adhesives for indirect bracket bonding, AM. J. ORTHOD. 65: 76-84,1974. 14. Concise Enamel Bond System, Dental Products 3M Company, Technical Bulletin. 15. Miura, F., Nakagawa, K., and Ishizaki, A.: Direct bonding system in general dentistry, J. Am. Dent. Assoc. 88: 359.366, 1974. 16. Retief, D. H.: The use of 50% phosphoric acid as an etching agent in orthodontics: A rational approach, AM. J. ORTHOD. 68: 165178, 1975. 17. Retief, D. H.: A comparative study of three etching solutions. Effects on contact angle, rate of etching and tensile bond strength, J. Oral Rehab. 1: 381-390, 1974. 18. Gwinnett, A. J., Buonocore, M. G., and Sheykholeslam, Z.: Effects of fluoride on etched human and bovine tooth enamel surfaces as demonstrated by scanning electron microscopy, Arch. Oral Biol. 17: 271-278, 1972. 19. Sadowsky, P. L.: A comparative study of some dental cements used in orthodontics, M. Dent. Thesis, University of the Witwatersrand, 1974.
and
Johannesburg,
P. 1. Sadowsky
South Africa
T
he lack of adhesion of dental materials to tooth structure is a major problem in dentistry.= Buonocore2 was the first to demonstrate that the bonding of acrylic filling materials to enamel could be substantially increased by conditioning the enamel surface with 85 per cent phosphoric acid. The acid-etch technique is now an accepted procedure in dentistry and widely applied in restorative and preventive dentistry and for the direct bonding of orthodontic attachments. The initial research efforts were concerned with the evaluation of existing dental materials for the direct bonding of orthodontic attachments31 * but subsequently various resin systems were developed for this purpose.5v G These resin systems were subjected to limited clinical evaluation.7* 8 With the advent of improved resin systems and a better understanding of the mechanism of action of phosphoric acid etching, the direct bonding of orthodontic attachments has become a practical clinical procedure.9-13 In this article, we present our experience with a direct-bonding system used in conjunction with the acid-etch technique and report on the clinical results obtained on a cross-section of the patients treated by them. The development
and pilot clinical evaluation
of a direct bonding
system
The bonding system. An epoxy resin formulation was developed for the direct bonding of orthodontic attachments .6 The composition of the formulation is as follows : Part
Part
I
II
Epikote Aerosilt
828*
Epikure Phenol
U*
1.0 ml. (1.12 mg.
Gm.)
0.3 ml. (0.31 70 mg.
Gm.)
140
From the Dental Research Unit of the University of the Witwatersrancl and the South African Medical Research Council (Dr. Retief) and Department of Orthodontics, School of Dentistry, University of the Witwatersrand (Dr. Sadowsky). *Shell tDegussa,
Chemical
S.A.
Frankfurt,
(Pty.), West
Ltd.,
Johannesburg,
Republic
of South
Africa.
Germany.
645
646
Retief
and Sadowsky
Fig. 1. Orthodontic attachments protected with Alastik rings.
welded
to
band
material
with
gauze
backing.
Flanges
Epikote 828 is a general-purpose epoxy resin and Epikure IJ is a modified polyamine curing agent. Aerosil is a thixotropic agent consisting of fine particles of silicon dioxide and was added to reduce the flow of the curing epoxy resin on inclined surfaces. Attachments bonded with this formulation maintained their desired positions on tooth surfaces after placement. Phenol is a catalyst and was added to accelerate the curing rate of the bonding system on the tooth surface. was too long for clinical application. The setting time of this formulation The rate of cure of epoxy resins is accelerated by heat, and the optimal preheat schedule for this formulation was determined. It was found that maximal tensile bond strengths to etched enamel surfaces were obtained by preheating the mixed resin at 50° C. for 6 minutes.8 The attachments. The epoxy resin formulation did not adhere to stainless steel under simulated intraoral conditions. Special stainless steel attachments were made to overcome this problem.6 Sixty-mesh stainless steel gauze was welded to the fitting surface of stainless steel orthodontic band material (0.006 x 0.220 inch). An edgewise orthodontic bracket was then welded to the center of this reinforced band material, the edges of the base were trimmed, and the base was contoured to fit the curvature of the tooth to be bonded. Adequate mechanical retention of the epoxy resin to stainless steel was achieved in this way (Fig. 1). The etching agent. Phosphoric acid is commonly used as a conditioning solution to obtain increased bonding of dental materials to tooth surfaces. Concentrations ranging from 3714 to 65 per cenF phosphoric acid are being supplied with commercial resin systems. The optimal concentration of phosphoric acid for the epoxy resin formulation was determined by evaluating the tensile bond strength, depth of etch, and surface roughness of etched enamel surfaces. It was found that 50 per cent phosphoric acid was the most suitab1e.l’ Bonding of attachments. The four components of the resin formulation were mixed on a glass slab and the mixture was spread evenly to allow dissipation of the exothermic heat; the prepared attachments were embedded in the resin; the slab and its contents were preheated in an oven at 50° C. for 6 minutes.
Volume Number
Acid-etch
68 6
technique in orthodontics
E 13M
D 11M
- ri--
1111 x!lLJ
Fig. 2. Teeth bonded in the pilot study. treatment; a cross, failure of a bonded
647
Patients attachment.
A to
H.
A dot
indicates
completion
of
In the meantime, the teeth to be bonded were cleaned with pumice and a rubber cup, etched with 50 per cent phosphoric acid for 1 minute, and washed well. The teeth were dried and the attachments placed on the teeth in the desired positions. Six attachments could readily be bonded with one mix. The bonded attachments were kept dry for 15 minutes. At the subsequent visit the excess material was removed and the arch wires were ligated. Pilot study. Eight patients were treated in the preliminary clinical trial and fifty-eight teeth were bonded. The duration of treatment ranged from 3 to 48 months (Fig. 2). The treatment method employed was a modified edgewise technique and the number of bonded attachments per patient ranged from one (Patients A and H) to 15 (Patient E). The malocclusicms treated included premolar extraction cases, anterior cross-bites, a Class II, Division 1, malocclusion in which a headgear was utilized (Fig. 3), and a partially erupted canine in a cleft-palate patient (Fig. 4). During the treatment of these patients fourteen bonded attachments became dislodged, nine before active orthodontic tooth movement was commenced. A failure rate of 24 per cent was calculated. Eleven of the dislodged attachments were rebonded and, of these, four failed again during treatment (Fig. 2). Definitive
clinicul
study
with
the
epoxy
resin
fomulation
Introduction. With experience obtained during the pilot study, certain modifications were introduced. The drying of the etched enamel surfaces prior to bonding was facilitated by using a commercially available drying agent, Prep-
648
Am. J. Orthod. December 197;
Retief and Sadowsky
Fig. 3. Headgear in patient with bonded Fig. 4. initial treatment of a partially
attachments. erupted
canine
by
means
of
a
removable
ap-
pliance.
Dry.” A rubber dam made the technique cumbersome and was not used. Alastikt rings were placed around the bracket flanges to prevent flow of excess resin beneath these flanges (Fig. 1). Subsequent laboratory tests, including tensile bond strengths, surfaceroughness measurements of etched enamel surfaces, ra,te of etching, and contact angle measurements, suggested that 50 per cent phosphoric acid attenuated with 7 per cent zinc oxide by weight was a more effective conditioning agent than the unbuffered 50 per cent phosphoric acid solution.” It was not found necessary to etch enamel surfaces for longer than 1 minute with the attenuated phosphoric acid solution. CZi&~Z study. In these clinical trials fifteen patients were treated and 123 attachments were bonded. The duration of treatment ranged from 5 to 35 months (Figs. 5 and 6). Twenty-three of the attachments became dislodged, seven prior to the application of orthodontic forces. Twelve were rebonded, and only one of these failed before completion of treatment. A failure rate of 18.8 per cent was recorded. The malocclusions treated in this study included crowding and spacing problems, premolar extraction cases, anterior cross-bites, and labially situated maxillary canines. From our clinical series of cases, the treatment of four patients-T, U, V, and W-in Fig. 6 will be described in more detail. Patient T. This patient was 23 years old and had a Class II. Division 1, malocclusion (Fig. 7). The lower first premolars had been extracted previously at an early age. The upper first premolars were extracted, and attachments were bonded to the remaining teeth in both arches from central incisor t,o first molar. The lower arch was corrected with round arch wires only, while a rectangular closing loop arch wire was used to close the extraction spaces in the maxillary arch. Active treatment extended over a period of approximately 1 year and *Lee tUnitek
Pharmaceuticals, Corporation,
South Monrovia,
El Monte, Calif.
Calif. 91016.
91733.
Volume
Number
68
Acid-etch
6
techwique in orthodontics
649 s 14hl
a
P
Q
12M
12M
11M ?’
M K
L
Fig. 5. Definitive
8M
clinical
study,
Patients
I to S.
V
T
Ol-
Fig. 6. Definitive
clinical
-
I &
Bol
ad
study,
Patients
T to W.
650
Retief
Fig.
7.
Fig.
8. Patient
Fig.
9. Study
a,nd Saclowsky
Initial
study
models
T during models
of
active
Patient
at completion
Fig.
10. Surgically
Fig.
11.
Patient
U during
exposed
Fig.
12.
Patient
U at completion
Headgear
of treatment
maxillary active
T.
treatment.
left
central
in place. in Patient incisor
T.
in Patient
U.
treatment. of treatment.
extraoral traction to the maxillary arch was utilized for approximately 5 months (Fig. 8). Two bonded attachments were lost prior to areh placement. These teeth were rebonded and no further attachments became dislodged during treatment. The result obtained at completion of treatment is shown in Fig. 9. Patient 77. A 14-year-old boy with a mild Class II, Division 1, malocclusion also had an unerupted maxillary left central incisor which required surgical exposure (Fig. 10). Bonded attachments were fitted to the upper six anterior
Volume Number
68 6
Acid-etch
technique
in orthodontics
651
teeth. Conventional bands were cemented to the maxillary first molars with extraoral traction (Fig. 11). A modified edgewise technique was utilized and no bonded attachments became dislodged during the treatment, which extended over 12 months. The result at completion of treatment is shown in Fig. 12. Although the gingival margin of the initially malposed incisor is more apical than the contralateral tooth, the result was considered satisfactory in view of its original position in the buccal sulcus (Fig. 10). Patient V. Patient V was an U-year-old girl who required surgical exposure of the labial surface of the maxillary left canine tooth (Figs. 13 and 14). Attachments were bonded to the labial surfaces of these teeth and initial removable appliance therapy was instituted. When the canines had been moved to a more satisfactory position within the arch, the maxillary incisor teeth were bonded. In order to correct undesired rotations, a new commercially available direct-bonding material was used to place lingual attachments on the maxillary left canine and second premolar teeth. A modified edgewise technique was utilized (Fig. 15) and the treatment extended over approximately two years. Just prior to the completion of treatment, one bonded attachment became dislodged and did not require replacement. Completed study models are shown in Fig. 16. Patie& W. This patient was a 15-year-old girl who had a Class II, Division 1, malocclusion with severe crowding in the lower arch (Fig. 17). The second premolar teeth were extracted in both arches, and attachments were bonded to all the remaining teeth except the second molars. A modified edgewise technique was utilized (Fig. 18). A Rampton type of headgear was used to reinforce maxillary posterior anchorage (Fig. 19). Study models at the completion of treatment are shown (Fig. 20). A preliminary
clinical
evaluation
of
a commercial
composite
direct
bonding
material
The clinical studies described in this article extended over a period of 7 years. Recently several materials for the direct bonding of orthodontic attachments have become commercially available. Initial laboratory studies have shown excellent bond strengths of these composite materials to etched enamel surfaces under simulated intraoral conditions. It was therefore decided to commence clinical trials with one of these bonding agents. The material selected was Genie,* and more than fifty attachments have been bonded in nine patients with differing types of malocclusion. These attachments have been in place for periods ranging from 3 to 12 months. To date, only one attachment has become dislodged. These clinical trials are proceeding and are being extended. Suggestions
for
the
direct
bonding
technique
As a result of our clinical experience with the direct bonding attachments, we offer some suggestions which may prove helpful : *Lee
Pharmaceuticals,
South
El Monte,
Calif.
91733.
of orthodontic
652
TZetief and Xadowsky
Fig.
13.
Fig.
14. Surgical
Patient
V at
exposure
of maxillary
Fig.
15.
Patient
V during
active
Fig.
16.
Study
Fig.
17.
Occlusal
Fig.
18.
Patient
Fig.
19.
Reinforcement
fig.
20.
Study
models
presentation
of
view W models
Patient of
during
study active
of maxillary at completion
for
treatment. left
canine
in Patient
V.
treatment. V at completion models
of
of treatment.
Patient
W.
treatment. anchorage of treatment
in Patient of Patient
W. W.
Volume Number
68 6
Acid-etch
technique
in orth,odmtics
653
1. To prevent excess adhesive from flowing beneath the flanges of the attachments, these may be protected with Alastik rings prior to the placement of the attachments (Fig. 1). 2. Lip retractors* were found to be of great help in keeping the mouth open and the lips and cheeks away from the bonded attachments. 3. Topical fluoride therapy should be deferred until the attachments have been bonded. The effect of etching agents is reduced on enamel surfaces treated with topical fluoride agents18 4. It is not necessary to etch for longer than 2 minutes. The etching solution should be confined to the area where the attachment is to be positioned. Excess acid may cause sloughing of the gingivae. 5. The use of a water repellent is advocated to keep the etched surfaces dry. Commercial water repellents are available. 6. Effective suction is essential to keep the mouth dry. 7. The application of a rubber dam is not necessary if adequate precautions are taken to maintain a dry field. 8. A trained assistant is essential. It is impossible for one person to mix the bonding resin and keep the mouth adequately dry at the same time. 9. Dabbing of the bonded attachments with cotton-wool pledgets soaked in chloroform prior to the removal of the bonded attachments may facilitate removal of these attachments. Advantages
of “bandless”
orthodontics
1. Gingival irritation is decreased because the bonded attachments do not impinge on the gingival margins. 2. It has been our experience that the oral hygiene of patients with bonded brackets is improved. This is a subjective conclusion. 3. When teeth are crowded it becomes imperative to separate the teeth prior to the fitting and cementing of bands. This procedure is obviously not necessary with the direct bonding technique. Another factor is the impingement on arch length by the interproximal band thickness. This is in the order of t4 mm.12 and there are times when this additional space is most welcome during orthodontic treatment. 4. Conventional banding of partially erupted teeth is often difficult and traumatic for the patient. The direct bonding of attachments to the exposed surfaces of these teeth presents no problems. 5. The last stage of orthodontic treatment may be devoted to space closure after removal of bands. No space closure is required with directly bonded attachments. 6. Orthodontic bands may become loose and remain undetected during treatment. As a result, decalcification may occur under these bands.lg The problem is not encountered with the direct-bonding technique because loosening of the attachments results in complete displacement. “O.I.S.,
P. 0. Box
2074,
Wilmington,
Del.
19899.
654
Retief
and Xadowsky
Conclusion
The acid-etch technique and the development of improved composite resin systems have made the direct bonding of orthodontic attachments an accepted clinical procedure. This technique can be used with confidence as an adjunct in the armamentarium of the orthodontist. REFERENCES
1. Phillips, R. W.: Advancements in adhesive restorative dental materials, J. Dent. Res. 45: 1662-1667, 1966. 2. Buonocore, M. G.: A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces, J. Dent. Res. 34: 849-853, 1955. 3. Swanson, L. T., and Beck, J. F. : Factors affecting bonding to human enamel with special reference to a plastic adhesive, J. Am. Dent. Assoc. 61: 581-586, 1960. 4. Mitchell, D. L. : Bandless orthodontic bracket, J. Am. Dent. Assoc. 74: 103-110, 1967. 5. Newman, G. V.: Epoxy adhesives for orthodontic attachments: Progress report, Arvr. J. ORTHOD. 51: 901-912, 1965. resins for bonding orthodontic attachments to 6. Retief, D. H., and Dreyer, C. J.: Epoxy teeth, J. Dent. Assoc. 5. Afr. 22: 338-346, 1967. 7. Newman, G. V.: Adhesion and plastic orthodontic att,achments, AM. J. ORTHOD. 56: 573-588, 1969. 8. Retief, D. H., Dreyer, C. J., and Gavron, G.: The direct bonding of orthodontic attachments to teeth by means of an epoxy resin adhesive, AE~. J. ORTHOD. 58: 21-40, 1970. 9. Miura, F., Nakagawa, K., and Mashuhara, F.: New direct bonding system for plastic brackets, AM. J. ORTHOD. 59: 350.361, 1971. 10. Cohl, M. E., Green, L. J., and Eick, J. D.: Bonding of clear plastic orthodontic brackets using an ultraviolet-sensitive adhesive, A&f, J. ORTHOD. 62: 400-411, 1972. 11. Silverman, E., Cohen, M., Gianelly, A. A., and Dietz, V. S.: A universal direct bonding system for both metal and plastic brackets, Anf. J. ORTHOD. 62: 236-244, 1972. 12. Daft, K. S., and Lugassy, A. A.: A preliminary study of orthodontic treatment with the use of directly bonded attachments, AM. J. ORTHOD. 65: 407-418, 1974. 13. Silverman, E., and Cohen, M.: Current adhesives for indirect bracket bonding, AM. J. ORTHOD. 65: 76-84,1974. 14. Concise Enamel Bond System, Dental Products 3M Company, Technical Bulletin. 15. Miura, F., Nakagawa, K., and Ishizaki, A.: Direct bonding system in general dentistry, J. Am. Dent. Assoc. 88: 359.366, 1974. 16. Retief, D. H.: The use of 50% phosphoric acid as an etching agent in orthodontics: A rational approach, AM. J. ORTHOD. 68: 165178, 1975. 17. Retief, D. H.: A comparative study of three etching solutions. Effects on contact angle, rate of etching and tensile bond strength, J. Oral Rehab. 1: 381-390, 1974. 18. Gwinnett, A. J., Buonocore, M. G., and Sheykholeslam, Z.: Effects of fluoride on etched human and bovine tooth enamel surfaces as demonstrated by scanning electron microscopy, Arch. Oral Biol. 17: 271-278, 1972. 19. Sadowsky, P. L.: A comparative study of some dental cements used in orthodontics, M. Dent. Thesis, University of the Witwatersrand, 1974.