Current Note No. 71
The bonding of orthodontic brackets to composite resin surfaces R. E. Schwartz* M . J. Tyasf V. C. West$ Most orthodontists today recognize the need for direct bonding techniques, especially where aesthetics is a concern. Numerous recent studies in the literature have investigated the bonding of orthodontic appliances to the porcelain of anterior crowns. With the incidence of traumatic injury to the permanent dentition estimated at 30 per cent for males and 20 per cent for females by the age of fourteen years, the acid etchlcomposite resin technique has become the treatment of choice for crown fractures involving the anterior permanent teeth.’ Despite the anticipated high frequency of composite restorations that the average orthodontist will encounter in clinical practice, there have been no studies which have investigated the bonding of orthodontic brackets directly to composite resin surfaces. The recently introduced ‘one-step’ or ‘no-mix’ adhesives are preferred by many clinicians due to the advantages of longer working times, less material wastage, and easier debonding with decreased enamel damage.2 With these systems, a thin layer of liquid activator is applied to the etched tooth surface and the bracket base. The resin is then placed onto the coated metal base and the appliance is firmly seated. Recent experiences in the Postgraduate Clinic at the Orthodontic Unit, School of Dental Science, University of Melbourne, suggested that the use of a specific ‘no-mix’ adhesives resulted in poor clinical performance when bonded to anterior composite resin restorations. The present study was designed to consider factors which may improve the integrity of orthodontic bonding procedures
*Orthodontic Postgraduate Student, Preventive and Community Dentistry Section, University of Melbourne. tSenior Lecturer, Restorative Dentistry Section, University of Melbourne. $Associate Professor, Preventive and Community Dentistry Section, University of Melbourne. 472
involving stainless steel mesh brackets, 1 ‘no mix’ adhesives,l and visible light-cured composite systems.** A full report is to be published in the future. The tensile strength of the adhesive Contacto, when used to bond stainless steel brackets to composite resin specimens, was obtained without surface treatment (controls) and after surface treatment of the composite resin by the following methods. 1. Etching with 37 per cent orthophosphoric acid. 2. Surface reduction with a high-speed diamond bur. 3 . Coating with a silane coupling agent.?? 4. Coating with dentine bonding agents.$$, $8 Tensile strength values of Unite, System 1 ,and Mono-Lok 2 adhesives, without composite surface preparation, were also obtained. No significant differences were evident between the control composites Silux Plus (4.3 f2.0 MPa) and P-50 (4.4k 1.4 MPa) bonded with Contacto. Both of these values were below the minimum in vitro tensile bond strength of 4.9 MPa, as recommended by R e y n o l d ~for , ~ adequate clinical results. For Silux Plus, bonding of untreated surfaces with Unite ( 1 0 . 3 f 2 . 6 M P a ) and Mono-Lok 2 (10.5 f 3.2 MPa) produced significantly greater mean tensile strength values than Contacto. With
+
RContacto, General Orthodontic Supply Inc., West Orange, NJ, USA. (1 Rocky Mountain Orthodontics, Denver, Colo., USA. !Unite, Unitek Corporation, Monrovia, Calif., USA. Mono-Lok, Rocky Mountain Orthodontics. System 1 + , Ormco Corporation, Glendora, Calif., USA. Contacto, General Orthodontic Supply Inc. **Silux Plus. 3M Dental Products Division, St. Paul, Minn., USA. P-50, 3M Dental Products Division. ttscotchprime, 3M Dental Products Division, St. Paul, Minn., USA. $$Scotchbond Dual Cure, 3M Dental Products Division. §§Scotchbond 2, 3M Dental Products Division. Australian Dental Journal 1990;35(5):472-3.
regard to all of the bonding materials and P-50, only treatment with Scotchprime (9.7 k 1.6 MPa) and Scotchbond 2 (9.9 3.5 MPa) resulted in statistically larger mean values when compared with the Contact0 controls. On the basis of these preliminary results, the use of Unite and Mono-Lok 2 ‘no-mix’ adhesives for bonding of orthodontic brackets to untreated microfilled composite resins can be recommended. Tensile strength values obtained with these adhesives were greater than figures reported on bonding of orthodontic brackets to For bonding of stainless steel brackets to hybrid posterior composite resins, the use of Scotchbond 2 or Scotchprime is suggested (with any of the tested adhesives) as a surface treatment. It may be that the former offers an economic benefit over the latter.
It may be worthy of mention that the widely practised clinical procedure encouraged by some workers of roughening the surface of a composite resin prior to orthodontic bonding produced a slight but insignificant increase in the tensile strength of the bond. References 1. Andreasen JO. Traumatic injuries of the teeth. 2nd edn.
Copenhagen: Munksgaard, 1981;79-88. 2. Delport A, Grobler SR. A laboratory evaluation of the tensile bond strength of some orthodontic bonding resins to enamel. Am J Onhod Dentofac Orthop 1988;93:133-7. 3. Reynolds IR. A review of direct orthodontic bonding. Br J Orthod 1975;2: 171-8. 4. Evans LB, Powers JM. Factors affecting in v i m bond strength of no-mix orthodontic cements. Am J Orthod 1985;87:508-12.
Australian Dental Research Fund Student Scholarships Abstract of Papers 1989-90 We regret that the heading of the following Abstract was incorrect in the original published version, and apologize to the authors and to our readers for this error.
Oral health status of recent Australian Navy recruits A-M Laslett and M. V. Morgan (Supervisor)* Studies concerning the oral health of military personnel have been conducted in Australia since 1948. This study was conducted on Royal Australian Navy recruits at the HMAS Cerberus Base in 1988. The aims were to describe the oral health status, dental attitudes, and dentally related behaviours of the sample. A sample of 1102 subjects aged 15-29 years was surveyed. They originated from all Australian States and represented a wide variety of socio-economic backgrounds. Soft tissue, periodontal, prosthetic, and tooth conditions were assessed in the clinical examination using standard World Health Organization criteria. Socio-metric, demographic, and fluoride history data, together with measures of attitudes and behaviours regarding oral health were elicited by questionnaire. The mean DMFT score for the sample was 4.77. The largest component of the DMFT index was *Preventive and Community Dentistry Section, School of Dental Science, The University of Melbourne, Victoria. Australian Dental Journal 1990;35:5
the F component with the mean value for the sample of 3.08. The decayed and missing components contributed respectively 1.56 and 0.12 to the total DMFT score. Those aged 15-19 years had a DMFT score of 4.34; the 20-24 year olds, 6.85; and the 25-29 year olds, 8.87. Analysis of DMFT by State revealed that the highest mean scores were found in Victorian (6.05) and Queensland (5.59) subjects, and the lowest score was found in Tasmanian subjects (3.51). The caries experience of Australian armed service recruits appears to have progressively and markedly decreased since 1948. In the early studies, the missing component constituted the largest percentage (44.8-56.5) of the caries experience, whereas in the present study the filled component was greatest (64.6 per cent). This suggests that dental caries is now managed more conservatively as indicated by the lower M and the higher F fractions. Although only one aspect of oral health has been described here, caries experience serves to illustrate not only the decreasing severity but also the changing patterns of oral disease and its management. 473
The bonding of orthodontic brackets to composite resin surfaces R. E. Schwartz* M . J. Tyasf V. C. West$ Most orthodontists today recognize the need for direct bonding techniques, especially where aesthetics is a concern. Numerous recent studies in the literature have investigated the bonding of orthodontic appliances to the porcelain of anterior crowns. With the incidence of traumatic injury to the permanent dentition estimated at 30 per cent for males and 20 per cent for females by the age of fourteen years, the acid etchlcomposite resin technique has become the treatment of choice for crown fractures involving the anterior permanent teeth.’ Despite the anticipated high frequency of composite restorations that the average orthodontist will encounter in clinical practice, there have been no studies which have investigated the bonding of orthodontic brackets directly to composite resin surfaces. The recently introduced ‘one-step’ or ‘no-mix’ adhesives are preferred by many clinicians due to the advantages of longer working times, less material wastage, and easier debonding with decreased enamel damage.2 With these systems, a thin layer of liquid activator is applied to the etched tooth surface and the bracket base. The resin is then placed onto the coated metal base and the appliance is firmly seated. Recent experiences in the Postgraduate Clinic at the Orthodontic Unit, School of Dental Science, University of Melbourne, suggested that the use of a specific ‘no-mix’ adhesives resulted in poor clinical performance when bonded to anterior composite resin restorations. The present study was designed to consider factors which may improve the integrity of orthodontic bonding procedures
*Orthodontic Postgraduate Student, Preventive and Community Dentistry Section, University of Melbourne. tSenior Lecturer, Restorative Dentistry Section, University of Melbourne. $Associate Professor, Preventive and Community Dentistry Section, University of Melbourne. 472
involving stainless steel mesh brackets, 1 ‘no mix’ adhesives,l and visible light-cured composite systems.** A full report is to be published in the future. The tensile strength of the adhesive Contacto, when used to bond stainless steel brackets to composite resin specimens, was obtained without surface treatment (controls) and after surface treatment of the composite resin by the following methods. 1. Etching with 37 per cent orthophosphoric acid. 2. Surface reduction with a high-speed diamond bur. 3 . Coating with a silane coupling agent.?? 4. Coating with dentine bonding agents.$$, $8 Tensile strength values of Unite, System 1 ,and Mono-Lok 2 adhesives, without composite surface preparation, were also obtained. No significant differences were evident between the control composites Silux Plus (4.3 f2.0 MPa) and P-50 (4.4k 1.4 MPa) bonded with Contacto. Both of these values were below the minimum in vitro tensile bond strength of 4.9 MPa, as recommended by R e y n o l d ~for , ~ adequate clinical results. For Silux Plus, bonding of untreated surfaces with Unite ( 1 0 . 3 f 2 . 6 M P a ) and Mono-Lok 2 (10.5 f 3.2 MPa) produced significantly greater mean tensile strength values than Contacto. With
+
RContacto, General Orthodontic Supply Inc., West Orange, NJ, USA. (1 Rocky Mountain Orthodontics, Denver, Colo., USA. !Unite, Unitek Corporation, Monrovia, Calif., USA. Mono-Lok, Rocky Mountain Orthodontics. System 1 + , Ormco Corporation, Glendora, Calif., USA. Contacto, General Orthodontic Supply Inc. **Silux Plus. 3M Dental Products Division, St. Paul, Minn., USA. P-50, 3M Dental Products Division. ttscotchprime, 3M Dental Products Division, St. Paul, Minn., USA. $$Scotchbond Dual Cure, 3M Dental Products Division. §§Scotchbond 2, 3M Dental Products Division. Australian Dental Journal 1990;35(5):472-3.
regard to all of the bonding materials and P-50, only treatment with Scotchprime (9.7 k 1.6 MPa) and Scotchbond 2 (9.9 3.5 MPa) resulted in statistically larger mean values when compared with the Contact0 controls. On the basis of these preliminary results, the use of Unite and Mono-Lok 2 ‘no-mix’ adhesives for bonding of orthodontic brackets to untreated microfilled composite resins can be recommended. Tensile strength values obtained with these adhesives were greater than figures reported on bonding of orthodontic brackets to For bonding of stainless steel brackets to hybrid posterior composite resins, the use of Scotchbond 2 or Scotchprime is suggested (with any of the tested adhesives) as a surface treatment. It may be that the former offers an economic benefit over the latter.
It may be worthy of mention that the widely practised clinical procedure encouraged by some workers of roughening the surface of a composite resin prior to orthodontic bonding produced a slight but insignificant increase in the tensile strength of the bond. References 1. Andreasen JO. Traumatic injuries of the teeth. 2nd edn.
Copenhagen: Munksgaard, 1981;79-88. 2. Delport A, Grobler SR. A laboratory evaluation of the tensile bond strength of some orthodontic bonding resins to enamel. Am J Onhod Dentofac Orthop 1988;93:133-7. 3. Reynolds IR. A review of direct orthodontic bonding. Br J Orthod 1975;2: 171-8. 4. Evans LB, Powers JM. Factors affecting in v i m bond strength of no-mix orthodontic cements. Am J Orthod 1985;87:508-12.
Australian Dental Research Fund Student Scholarships Abstract of Papers 1989-90 We regret that the heading of the following Abstract was incorrect in the original published version, and apologize to the authors and to our readers for this error.
Oral health status of recent Australian Navy recruits A-M Laslett and M. V. Morgan (Supervisor)* Studies concerning the oral health of military personnel have been conducted in Australia since 1948. This study was conducted on Royal Australian Navy recruits at the HMAS Cerberus Base in 1988. The aims were to describe the oral health status, dental attitudes, and dentally related behaviours of the sample. A sample of 1102 subjects aged 15-29 years was surveyed. They originated from all Australian States and represented a wide variety of socio-economic backgrounds. Soft tissue, periodontal, prosthetic, and tooth conditions were assessed in the clinical examination using standard World Health Organization criteria. Socio-metric, demographic, and fluoride history data, together with measures of attitudes and behaviours regarding oral health were elicited by questionnaire. The mean DMFT score for the sample was 4.77. The largest component of the DMFT index was *Preventive and Community Dentistry Section, School of Dental Science, The University of Melbourne, Victoria. Australian Dental Journal 1990;35:5
the F component with the mean value for the sample of 3.08. The decayed and missing components contributed respectively 1.56 and 0.12 to the total DMFT score. Those aged 15-19 years had a DMFT score of 4.34; the 20-24 year olds, 6.85; and the 25-29 year olds, 8.87. Analysis of DMFT by State revealed that the highest mean scores were found in Victorian (6.05) and Queensland (5.59) subjects, and the lowest score was found in Tasmanian subjects (3.51). The caries experience of Australian armed service recruits appears to have progressively and markedly decreased since 1948. In the early studies, the missing component constituted the largest percentage (44.8-56.5) of the caries experience, whereas in the present study the filled component was greatest (64.6 per cent). This suggests that dental caries is now managed more conservatively as indicated by the lower M and the higher F fractions. Although only one aspect of oral health has been described here, caries experience serves to illustrate not only the decreasing severity but also the changing patterns of oral disease and its management. 473
