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JOURNAL REVIEWKanish AgggarwalPG StudentDept. Of Orthodontics1Original ArticlePublished in March 2015 issue of American Journal of Orthodontics and Dentofacial Orthopedics (AJO DO)(Am J Orthod Dentofacial Orthop 2015;147:324-9)Monthly journal covering orthodontic researchDr. Rolf G. Behrents is the current editor-in-chief

In-vivo evaluation of the surface roughness and morphology of enamel after bracket removal and polishing by different techniquesAuthors : Elcio Mario Faria-Junior, Ricardo Danil Guiraldo, Sandrine Bittencourt Berger, Americo Bortolazzo Correr, Lourenco Correr-Sobrinho, Edwin Fernando Ruiz Contreras, and Murilo Baena LopesARTICLE METRICESNo. of tables02No. of pictures03No. of parameters used03No. of citations00INTRODUCTIONThe aim of this study was to evaluate the surface roughness and morphology of the enamel using a Surface Roughness Tester and Scanning Electron Microscope after the removal of metal brackets from the maxillary central incisors, in vivo.This study was conducted by Faria Junior et al in Brazil, South America.Since 1970, bonding of orthodontic brackets to tooth enamel has become an accepted clinical techniqueOrthodontic treatment commonly involves bonding of orthodontic brackets to tooth enamelThe bonding procedure involves alteration of the enamel surface by acid etching, followed by the application of adhesive primer and resin17The basis for the adhesion of brackets to enamel has been enamel etching with phosphoric acid, as first proposed by Buonocore in 1955Other methods such as air abrasion have also been employed for preconditioning of enamel before bonding of brackets. Air abrasion involves sandblasting enamel surface with 50 m aluminum oxide particles

A study conducted by Waveren et al (Am J Orthod Dentofacial Orthop 2000;117:20-6) on 42 bovine incisors showed that the amount of enamel loss was similar in case of air abrasion when compared to acid etching but the bond strength by air abrasion was less than that of acid etchingMethods like crystal growth conditioning have also been tested as an alternative to acid etch procedure Van Waveren Hogervorst WL, Feilzer AJ, Prahl-Andersen B. The air-abrasion technique versus the conventional acid-etching technique: a quantification of surface enamel loss and a comparison of shear bond strength. Am J Orthod Dentofacial Orthop 2000;117: 20-6.Artun J, Bergland S. Clinical trials with crystal growth conditioning as an alternative to acid-etch enamel pretreatment. Am J Orthod 1984;85:333-40In a study conducted by Artun J et al on 40 orthodontic patients it was found that the bond strength in acid etching using 37 % o-phosphoric acid was higher than enamel preconditioning using a solution of sulphuric acid, phosphoric acid and sodium sulphate which was higher than bond strength obtained by preconditioning enamel using a solution of sulphuric acid and sodium sulphate After the completion of orthodontic treatment the brackets are debonded and the resin is removed

The final procedure in returning the enamel surface to the original pretreatment condition involves the removal of all attachments such as brackets & bands and remaining resin from the tooth surfaces

Various methods have been advocated for debonding brackets After debonding of the bracket, the resin might remain on the tooth which is categorized as Artun J, Bergland S. Clinical trials with crystal growth conditioning as an alternative to acid-etch enamel pretreatment. Am J Orthod 1984;85:333-40Various techniques which are commonly employed to remove the resin are214Esthetics is one of the primary consideration for patients to seek orthodontic treatmentThe form and brightness of the maxillary anterior teeth are important for both dental and facial estheticsThe brightness of the buccal surface must be restored after orthodontic treatment, a goal that may not be possible to achieve with rough surfacesEach debonding procedure can result in variable surface quality according to the instruments used and the different degrees of enamel lossHence to achieve good esthetics it is necessary that the resin removal method should restore the enamel to its initial surface morphology. The null hypothesis : The surface roughness and the morphology of the areas of untouched enamel would not differ from those in areas that were polished by an aluminum oxide disc or a carbide bur.MATERIAL AND METHODSThis study was evaluation of 10 patients (5 male, 5 female) ranging in age from 14 years to 21 years 7 months (mean, 17 years 6 months). It was approved by the research ethics committee of the University of North Parana in BrazilNo patient had any caries, restorations, history of trauma, bruxism, or cracks on the maxillary incisors.

The middle third of the buccal face of all teeth was etched with 37% o-phosphoric acid gel (Condac 37)30 seconds, rinsed with air-and-water spray, and air dried for 20 secondsOne layer of adhesive primer (Adper Single Bond 2) was applied to the etched area. Stainless steel standard maxillary incisor brackets (Roth) were bonded to the teeth with Filtek Z100 (3M ESPE).A microbrush was used to remove any excess.

The resin was cured using Ultraled (Dabi Atlante) light-emitting diode device at an irradiance of 800 mW/per square centimeter. The edge of each bracket was exposed to the light-emitting diode for 10 seconds, with a total exposure time of 40 seconds.Orthodontic treatment ranged from 15 to 28 months (mean, 21.5 months)After treatment, the brackets were removed with pliersProphylactic procedures were performed with pumice and a Robinson brushImpression was taken in Polyvinylsiloxane using 1 step impression techniqueThe impression was cast in epoxy resinThe adhesive remnant index (ARI) of the epoxy resin replicas was analyzed using optical microscope at a 40x Magnification

ARI was used to classify the failure mode as follows: One side of the mouth was randomly selected, and the teeth on that side were finished and polished with aluminum oxide discsThe discs were used at low rpm under intermittent cooling, in decreasing order of abrasiveness for 20 seconds each, until a visibly smooth and polished surface was obtained.

On the other side, the teeth were finished with a multilaminated carbide bur used at low rpm under intermittent water cooling until a visibly smooth and polished surface was obtained (80 seconds).After the removing the remaining resin, new replicas with polished teeth were obtained using polyvinylsiloxane impression and casting using epoxy resinFor the surface roughness measurements, 3 sets of dental replicas were tested:The surface roughness was measured with a surface roughness tester (SJ 400; Mitutoyo, Kawasaki-Shi, Kanagawa, Japan) at a speed of 0.05 mm per second, with a length of 2.5 mm Three measurements were made in different directions with an angle of 120Mean of the three readings was calculatedThree replicas from each group were analyzed by SEM (JSM 5600; Jeol, Peabody, Mass). The specimens were gold sputtered to a thickness of about 50 in a vacuum evaporator (SCD 050; Oerlikon Balzers, Balzers, Liechtenstein).

Photomicrographs at 500 times magnification were taken in representative areas of the surfaces.

STATISTICAL ANALYSISThe distributions of the measurements were investigated with the Kolmogorov-Smirnov normality test; then parametric tests were used. Data for roughness values were statistically evaluated by repeated measurements analysis of variance at the 5% significanceRESULTS

DISCUSSIONThe maxillary central incisors are important determinants in evaluating anterior dental estheticThe surface roughness is connected directly with the brightness and, thus, the esthetics of the teethOrthodontic treatment has an inevitable influence on the enamel surface.Regardless of the method used, some groove occurs after bracket debonding and resin removal.Damage to the enamel surface may lead to decreased enamel resistance and an increased risk of decalcification.Roughness of the enamel surface provides an area for the attachment of dental plaque which predisposes it to decalcificationIn the study, the surface roughness values obtained after finishing with aluminum oxide discs were lower than the values in the areas of pumice polished enamel. Thus, polishing with aluminum oxide discs may improve the light reflection of enamel.The values of surface roughness for tungsten carbide bur were higher than the aluminum oxide groupEliades et al studied surface roughness of 30 premolar crowns after debonding. The resin removal was done by tungsten carbide burs and ultra fine diamond burs. The crowns were then polished using aluminum oxide discs. It was found that the surface roughness of tungsten carbide group was lower but diamond burs took half the time for resin removalEliades T, Gioka C, Eliades G, Makou M. Enamel surface roughness following debonding using two resin grinding methods. Eur J Orthod 2004;26:333-8.Karan S et al studied surface roughness of 20 premolars after debonding using atomic force microscopy. The resin removal was done using tungsten carbide bur and a composite bur, reinforced by zircon-rich glass fiber. It was found that the surface roughness by composite bur was lower as compared to the tungsten carbide bur but the duration of resin removal was higher for composite burKaran S, Kircelli BH, Tasdelen B. Enamel surface roughness after debonding. Angle Orthod 2010;80:1081-8.Zarrinia et al studied surface roughness of 60 premolars after resin removal by seven different methodsFine finishing diamond pointA no.169L carbide burA 12- fluted carbide finishing burA stainless steel finishing burCoarse,medium,and fine sandpaper disksMedium,fine,and superfine aluminum oxide disksZarrinia K, Eid NM, Kehoe MJ. The effect of different debonding techniques on the enamel surface: an in vitro qualitative study. Am J Orthod Dentofacial Orthop 1995;108:284-93.7. Shofu wheels from an enamel adjustment kitIt was found in the study that best results are obtained when resin is removed using aluminum oxide discs, but the method is time consumingHe recommended the removal of bulk of resin with tungsten carbide bur and then use of aluminum oxide discs and final polishing with rubber cup and zircate pasteFrom the result of the study the null hypothesis was not accepted because significant differences in the surface roughness were found between the areas of untouched enamel and the areas that were polished by aluminum oxide discs Differences in surface morphology were also found between the areas of untouched enamel and the areas that were polished by aluminum oxide disc or carbide bur.LIMITATIONS OF THE STUDYThe sample size was smallThe sample size was small (n=10), which decreases the potential of the study to be generally applicable2. Polyvinylsiloxane was used for impression procedureImpression material was used to create the replica of the surface of the tooth to be studied. There is always some detail loss associated with the impression material

3. Study was conducted on epoxy resin replicasEpoxy resin replicas were made from the impression of the teeth.There is always some loss of surface detail, this more so is important in this study as surface morphology is being studied using electron microscope4. Only central incisors were studiedCentral incisors, lateral incisors and canines form important aspect of the smile and facial esthetics.5. Surface morphology was studied using scanning electron microscopeScanning electron microscope was used to create 2-D images for the study of surface morphology. Better microscopes such as atomic force microscope are available which provide a 3D view and a better understanding of surface morphology. CONCLUSION

1. The aluminum oxide disc system resulted in less enamel roughness than did the carbide bur system for polishing enamel after bracket removal.2. The areas of untouched enamel showed no significant difference in surface roughness compared with enamel polished by the carbide bur system.3. The morphology of the enamel that was polished by aluminum oxide discs resulted in no apparent grooves.THANK YOU