An electron microscopic evaluation of the enamel surface subsequent to various debonding procedures S. Howell, MDSc (Sydney)* W. T . Weekes, MDS (Ade1aide)t
Key words: Debonding, enamel surface, orthodontics. Abstract In this study, enamel surface roughness was investigated following the use of various combinations of bonding agents, burs and polishing procedures. Orthodontic brackets were bonded to 135 premolar teeth extracted from adolescents. Subsequent to debonding and finishing, the enamel surface was gold coated and examined in the scanning electron microscope. Each 200 x photomicrograph was graded according to surface roughness and assigned to one of four selected standard grades. The use of different composites and different burs showed no significant effect on the finish of the enamel surface using Chi-square tests. Only two finishing procedures had a significant effect on surface roughness. The use of a Soflex disc followed by pumice slurry resulted in the roughest enamel surface and the use of pumice alone produced the smoothest enamel surface. (Received for publication April 1988. Accepted December 1988.)
Introduction The direct bonding of orthodontic brackets to the enamel surface of a tooth has been a widely accepted clinical procedure for a little more than a decade. Early reports of debonding procedures recommended the removal of any adhesive remnants with
‘Head of Unit - Orthodontics, Westmead Hospital Dental Clinical School. tVisiting Dental Officer - Orthodontics, Westmead Hospital Dental Clinical School. Australian Dental Journal 1990;35(3):245-52.
a hand instrument followed by a fluted bur, prior to prophylaxis with zircate, pumice, or composite finishing paste.’,’ Recent reports have warned that the use of hand instruments may damage the enamel s u ~ f a c e , ~ . ~ leaving ‘tear-out~’,~ gouges and scratches.‘ Consequently, several investigators have recommended the use of tungsten carbide burs to remove resin remnants.2-6 Gwinett and Gorelick2 suggested that debonding was quicker and easier where unfilled and lightly filled adhesives were used. They recommended using a green rubber wheel to remove the last resin remnants, and showed that the fine scratches left on the enamel by the green rubber wheel were removed by the final polishing with pumice. Retief and Denys5 also advocated the use of a lightly filled resin for bonding. They preferred to debond with a 12 bladed tungsten carbide bur used at high speed, followed by ceramist wheels and prophylaxis with pumice. This procedure resulted in a smooth enamel surface. Sandison’ used a tungsten carbide bur at 20-30 000 rpm followed by pumice for final polishing, whereas Zachrisson and Arthun4 used a similar bur only at low speed without prophylaxis. There is a lack of general agreement on debonding techniques and the damage which can be caused by some of the recommended instrumentation. The aim of this study was to determine which debonding procedure caused the least damage to the enamel surface. Various bonding agents and debonding procedures were investigated, some of which are in routine use at Westmead Hospital Dental Clinical School. 245
Table 1. Sources of products used Concise System 1
3M Dental Division, St Paul, MA, USA. Sybron Ormco Corporation, Glendorra, CA, USA Sun Medical Co Ltd, Kyoto, Japan
Superbond (Orthomite) Komet Burs Brasseler, Lippe, West Germany Ultrafine Paste Den-Mat, Santa Maria, CA, USA. Floran Paste Creighton Pharmaceuticals, Kingsgrove, NSW, Australia Soflex Discs 3M Dental Division, St Paul, MA, USA
Materials and method Premolar teeth extracted for orthodontic purposes were used in this study. After extraction, they were placed in Millonig’s formalin solution for decontamination and removal of debris. Teeth were subsequently rinsed with water and stored in 70 per cent ethanol solution. In order to minimize enamel surface variation due to age, only teeth from young patients were used. The presence of distinct perikymata was a requirement for any teeth used in this study. Prior to bonding, teeth were dried and mounted in plaster to ensure firm support during debonding. Begg orthodontic brackets were bonded to 144 premolar teeth, 135 of which were randomly assigned to three groups. Each tooth had orthodontic brackets placed with one of the following bonding materials according to the manufacturer’s instructions (For sources of products used see Table 1). Group I : Concise - heavily filled. Group 2: System 1 - lightly filled. Group 3: Superbond (orthomite) - unfilled. Each group was further subdivided into three subgroups, according to the type of tungsten carbide bur used to debond the bracket (Table 2). i Komet H283. ii. Komet H379. iii. Komet H33. Finally, each sub-group was again divided into five further groups and the following finishing procedures were performed (Table 2). i. Bur alone, no further finishing. ii Ultrafine (aluminium oxide) paste. iii. Floran (zirconium silicate) paste. iv. Pumice water slurry. o. Medium fine Soflex disc followed by pumice water slurry. Three teeth were used for each of the 45 combinations of bonding agent, bur type and final finishing procedure (Table 2). In addition, three teeth bonded with each bonding agent (9 teeth total) were examined after bracket removal without any subsequent finishing procedures. 246
Brackets were removed by squeezing the bracket slot with a pair of ligature cutters. Distortion of the bracket base which occurred was sufficient to break the bond for most of the brackets. The remaining brackets were removed with a pair of bond removing pliers applied to the bracket base. Twisting and shearing action was not employed. Bonding agent remnants were removed with one of the three types of tungsten carbide bur at low speed followed by one of the five finishing procedures. A magnifying loupe with a focal length of 250 mm and 2 x magnification was used during the finishing procedures and while using Soflex discs. The Soflex disc was used as briefly as possible to obtain an even surface. Prophylaxis was carried out for 20 seconds. The enamel surface was gold coated and examined in a scanning electron microscope$ with an accelerating voltage of 20 kV. Stereopair photomicrographs were taken at magnifications of 15x, 3 5 ~ ~, O O X ,and 1 5 0 0 ~ . Photomicrographs of all teeth were compared for the following features. 1. Surface roughness. 2. Presencelabsence of perikymata. 3. Surface morphology. Surface roughness was compared by grading each 200 x photomicrograph as follows. Grade A. Acceptable surface - fine scattered scratches (Fig. 1). Grade B. Mildly rough surface - denser fine scratches, some coarser scratches (Fig. 2).
Table 2. Bonding agent, bur, and finishing procedure used Debonding procedure Bonding agent
Tungsten carbide bur (Komet)
Concise (heavily Fluted, torpedotilled) shaped: H283
Finishing procedure Bur only
System 1 (lightly Fluted, barrel-shaped: Ultrafine paste filled) H379 (aluminium oxide) Superbond (unfilled)
Cross-cut, tapering: H33
Floran paste (Zirconium silicate) Pumice water slurry Medium Soflex disc and pumice slurry
tJEOL, JSM840. JEOL Lrd, Tokyo, Japan.
Australian Dental Journal 1990;35:3.
Fig. 1. Fig. 2. Fig. 3. Fig. 4.
- Grade A. Acceptable surface: fine scattered scratches. Orig x 200. Bar = 100pm. - Grade B. Mildly rough surface: denser fine scratches, some coarser scratches. Orig x 200. Bar = 100pm. - Grade C. Rough surface: numerous coarse scratches over the entire surface. Orig x 200. Bar = pm. - Grade D. Very rough surface: deep, very coarse scratches over the entire surface. Orig x 200. Bar = 100pm.
Grade C. Rough surface - numerous coarse scratches over the entire surface (Fig. 3). Grude D.Very rough surface - deep, very coarse scratches over the entire surface (Fig. 4). This system of grading is similar to the enamel surface index proposed by Zachrisson and A r t h ~ n . ~ Grading was carried out by each author independently. All teeth which had different grades allotted were re-graded. If there was still no agreement reached then the coarser grade was selected. The data were analysed using Chi-square tests.
slightly superior to Ultrafine paste at p
Key words: Debonding, enamel surface, orthodontics. Abstract In this study, enamel surface roughness was investigated following the use of various combinations of bonding agents, burs and polishing procedures. Orthodontic brackets were bonded to 135 premolar teeth extracted from adolescents. Subsequent to debonding and finishing, the enamel surface was gold coated and examined in the scanning electron microscope. Each 200 x photomicrograph was graded according to surface roughness and assigned to one of four selected standard grades. The use of different composites and different burs showed no significant effect on the finish of the enamel surface using Chi-square tests. Only two finishing procedures had a significant effect on surface roughness. The use of a Soflex disc followed by pumice slurry resulted in the roughest enamel surface and the use of pumice alone produced the smoothest enamel surface. (Received for publication April 1988. Accepted December 1988.)
Introduction The direct bonding of orthodontic brackets to the enamel surface of a tooth has been a widely accepted clinical procedure for a little more than a decade. Early reports of debonding procedures recommended the removal of any adhesive remnants with
‘Head of Unit - Orthodontics, Westmead Hospital Dental Clinical School. tVisiting Dental Officer - Orthodontics, Westmead Hospital Dental Clinical School. Australian Dental Journal 1990;35(3):245-52.
a hand instrument followed by a fluted bur, prior to prophylaxis with zircate, pumice, or composite finishing paste.’,’ Recent reports have warned that the use of hand instruments may damage the enamel s u ~ f a c e , ~ . ~ leaving ‘tear-out~’,~ gouges and scratches.‘ Consequently, several investigators have recommended the use of tungsten carbide burs to remove resin remnants.2-6 Gwinett and Gorelick2 suggested that debonding was quicker and easier where unfilled and lightly filled adhesives were used. They recommended using a green rubber wheel to remove the last resin remnants, and showed that the fine scratches left on the enamel by the green rubber wheel were removed by the final polishing with pumice. Retief and Denys5 also advocated the use of a lightly filled resin for bonding. They preferred to debond with a 12 bladed tungsten carbide bur used at high speed, followed by ceramist wheels and prophylaxis with pumice. This procedure resulted in a smooth enamel surface. Sandison’ used a tungsten carbide bur at 20-30 000 rpm followed by pumice for final polishing, whereas Zachrisson and Arthun4 used a similar bur only at low speed without prophylaxis. There is a lack of general agreement on debonding techniques and the damage which can be caused by some of the recommended instrumentation. The aim of this study was to determine which debonding procedure caused the least damage to the enamel surface. Various bonding agents and debonding procedures were investigated, some of which are in routine use at Westmead Hospital Dental Clinical School. 245
Table 1. Sources of products used Concise System 1
3M Dental Division, St Paul, MA, USA. Sybron Ormco Corporation, Glendorra, CA, USA Sun Medical Co Ltd, Kyoto, Japan
Superbond (Orthomite) Komet Burs Brasseler, Lippe, West Germany Ultrafine Paste Den-Mat, Santa Maria, CA, USA. Floran Paste Creighton Pharmaceuticals, Kingsgrove, NSW, Australia Soflex Discs 3M Dental Division, St Paul, MA, USA
Materials and method Premolar teeth extracted for orthodontic purposes were used in this study. After extraction, they were placed in Millonig’s formalin solution for decontamination and removal of debris. Teeth were subsequently rinsed with water and stored in 70 per cent ethanol solution. In order to minimize enamel surface variation due to age, only teeth from young patients were used. The presence of distinct perikymata was a requirement for any teeth used in this study. Prior to bonding, teeth were dried and mounted in plaster to ensure firm support during debonding. Begg orthodontic brackets were bonded to 144 premolar teeth, 135 of which were randomly assigned to three groups. Each tooth had orthodontic brackets placed with one of the following bonding materials according to the manufacturer’s instructions (For sources of products used see Table 1). Group I : Concise - heavily filled. Group 2: System 1 - lightly filled. Group 3: Superbond (orthomite) - unfilled. Each group was further subdivided into three subgroups, according to the type of tungsten carbide bur used to debond the bracket (Table 2). i Komet H283. ii. Komet H379. iii. Komet H33. Finally, each sub-group was again divided into five further groups and the following finishing procedures were performed (Table 2). i. Bur alone, no further finishing. ii Ultrafine (aluminium oxide) paste. iii. Floran (zirconium silicate) paste. iv. Pumice water slurry. o. Medium fine Soflex disc followed by pumice water slurry. Three teeth were used for each of the 45 combinations of bonding agent, bur type and final finishing procedure (Table 2). In addition, three teeth bonded with each bonding agent (9 teeth total) were examined after bracket removal without any subsequent finishing procedures. 246
Brackets were removed by squeezing the bracket slot with a pair of ligature cutters. Distortion of the bracket base which occurred was sufficient to break the bond for most of the brackets. The remaining brackets were removed with a pair of bond removing pliers applied to the bracket base. Twisting and shearing action was not employed. Bonding agent remnants were removed with one of the three types of tungsten carbide bur at low speed followed by one of the five finishing procedures. A magnifying loupe with a focal length of 250 mm and 2 x magnification was used during the finishing procedures and while using Soflex discs. The Soflex disc was used as briefly as possible to obtain an even surface. Prophylaxis was carried out for 20 seconds. The enamel surface was gold coated and examined in a scanning electron microscope$ with an accelerating voltage of 20 kV. Stereopair photomicrographs were taken at magnifications of 15x, 3 5 ~ ~, O O X ,and 1 5 0 0 ~ . Photomicrographs of all teeth were compared for the following features. 1. Surface roughness. 2. Presencelabsence of perikymata. 3. Surface morphology. Surface roughness was compared by grading each 200 x photomicrograph as follows. Grade A. Acceptable surface - fine scattered scratches (Fig. 1). Grade B. Mildly rough surface - denser fine scratches, some coarser scratches (Fig. 2).
Table 2. Bonding agent, bur, and finishing procedure used Debonding procedure Bonding agent
Tungsten carbide bur (Komet)
Concise (heavily Fluted, torpedotilled) shaped: H283
Finishing procedure Bur only
System 1 (lightly Fluted, barrel-shaped: Ultrafine paste filled) H379 (aluminium oxide) Superbond (unfilled)
Cross-cut, tapering: H33
Floran paste (Zirconium silicate) Pumice water slurry Medium Soflex disc and pumice slurry
tJEOL, JSM840. JEOL Lrd, Tokyo, Japan.
Australian Dental Journal 1990;35:3.
Fig. 1. Fig. 2. Fig. 3. Fig. 4.
- Grade A. Acceptable surface: fine scattered scratches. Orig x 200. Bar = 100pm. - Grade B. Mildly rough surface: denser fine scratches, some coarser scratches. Orig x 200. Bar = 100pm. - Grade C. Rough surface: numerous coarse scratches over the entire surface. Orig x 200. Bar = pm. - Grade D. Very rough surface: deep, very coarse scratches over the entire surface. Orig x 200. Bar = 100pm.
Grade C. Rough surface - numerous coarse scratches over the entire surface (Fig. 3). Grude D.Very rough surface - deep, very coarse scratches over the entire surface (Fig. 4). This system of grading is similar to the enamel surface index proposed by Zachrisson and A r t h ~ n . ~ Grading was carried out by each author independently. All teeth which had different grades allotted were re-graded. If there was still no agreement reached then the coarser grade was selected. The data were analysed using Chi-square tests.
slightly superior to Ultrafine paste at p
