mazhar th / orthodontic courses by Indian dental academy

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A COMPARATIVE EVALUATION OF A COMPARATIVE EVALUATION OF SHEAR BOND STRENGTH OF SHEAR BOND STRENGTH OF

ORTHODONTIC BRACKETS BONDED TO ORTHODONTIC BRACKETS BONDED TO PORCELAIN FUSED METAL CROWNS PORCELAIN FUSED METAL CROWNS

TREATED WITH DIFFERENT SURFACE TREATED WITH DIFFERENT SURFACE CONDITIONING TECHNIQUES – AN CONDITIONING TECHNIQUES – AN

INVITRO STUDYINVITRO STUDY INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

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CONTENTSCONTENTS

INTRODUCTIONINTRODUCTION AIMS AND OBJECTIVESAIMS AND OBJECTIVES REVIEW OF LITERATUREREVIEW OF LITERATURE MATERIALS AND METHODSMATERIALS AND METHODS RESULTSRESULTS DISCUSSIONDISCUSSION CONCLUSIONCONCLUSION


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INTRODUCTIONINTRODUCTION The introduction of acid etch bonding technique by The introduction of acid etch bonding technique by

Buonocore in 1955, brought the concept of bonding Buonocore in 1955, brought the concept of bonding various resins to enamel with applications in all fields of various resins to enamel with applications in all fields of dentistry, including orthodontics. dentistry, including orthodontics.

With the development of reliable and reproducible With the development of reliable and reproducible bonding techniques to enamel surfaces, cemented bands bonding techniques to enamel surfaces, cemented bands were replaced by bonded brackets on incisor, cuspid and were replaced by bonded brackets on incisor, cuspid and bicuspid teeth. bicuspid teeth.

Newman 1965 was the first person who used epoxy resin Newman 1965 was the first person who used epoxy resin for bonding stainless steel brackets to enamelfor bonding stainless steel brackets to enamelwww.indiandentalacademy.comwww.indiandentalacademy.com

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By the late 1970s bonding of orthodontic brackets had By the late 1970s bonding of orthodontic brackets had become an accepted clinical technique in routine fixed become an accepted clinical technique in routine fixed appliance treatment. appliance treatment.

With the increased number of adults seeking orthodontic With the increased number of adults seeking orthodontic treatment, clinicians often have to bond orthodontic treatment, clinicians often have to bond orthodontic brackets to teeth that have different types of restorations, brackets to teeth that have different types of restorations, including amalgam, gold, composite and porcelain. including amalgam, gold, composite and porcelain.

Various methods have been tried to improve the bonding Various methods have been tried to improve the bonding of orthodontic brackets to porcelain surfaces by pre-of orthodontic brackets to porcelain surfaces by pre-treating porcelain surface by mechanical or chemical treating porcelain surface by mechanical or chemical means, or by a combination of both. means, or by a combination of both.


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AIMS AND OBJECTIVESAIMS AND OBJECTIVES (1) (1) To compare the effect of different surface To compare the effect of different surface

conditioning methods on bond strength, when conditioning methods on bond strength, when orthodontic brackets are bonded to porcelain fused metal orthodontic brackets are bonded to porcelain fused metal surfaces. surfaces.

(2)(2) To compare the bond strength of brackets bonded to To compare the bond strength of brackets bonded to porcelain-fused-to-metal surface with bonding on natural porcelain-fused-to-metal surface with bonding on natural teeth as control.teeth as control.

(3) (3) To assess the type of bond failures using scanning To assess the type of bond failures using scanning electron microscope electron microscope

(4) (4) To discuss a more reliable and least variable surface To discuss a more reliable and least variable surface conditioning method for bonding brackets to porcelain conditioning method for bonding brackets to porcelain fused metal surfaces.fused metal surfaces.www.indiandentalacademy.comwww.indiandentalacademy.com

Ozcan M, Vallittu PK Ozcan M, Vallittu PK et alet al.,., (2004) (2004) evaluated the effects of 5 different evaluated the effects of 5 different surface conditioning methods on the bond strength of polycarbonate surface conditioning methods on the bond strength of polycarbonate brackets bonded to ceramic surfaces with resin based cement. brackets bonded to ceramic surfaces with resin based cement.

The specimens were randomly assigned to one of the following The specimens were randomly assigned to one of the following treatment conditions of the ceramic surface: treatment conditions of the ceramic surface:

(1) orthophosphoric acid, primer, bonding agent,(1) orthophosphoric acid, primer, bonding agent, (2) hydrofluoric acid gel, primer, bonding agent,(2) hydrofluoric acid gel, primer, bonding agent, (3) tribochemical silica coating (silicon dioxide 30µm) silane,(3) tribochemical silica coating (silicon dioxide 30µm) silane, (4) airborne particle abrasion (aluminum trioxide 30µm) silane, (4) airborne particle abrasion (aluminum trioxide 30µm) silane,

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Review of LiteratureReview of Literature


& (5) airborne particle abrasion (aluminum trioxide, & (5) airborne particle abrasion (aluminum trioxide, 30µm) silane, bonding agent30µm) silane, bonding agent

Results showed that brackets treated with silica coating Results showed that brackets treated with silica coating with silanization had significantly greater bond strength with silanization had significantly greater bond strength values (13.6 MPa,) than brackets treated with values (13.6 MPa,) than brackets treated with orthophosphoric acid (8.5 MPa).orthophosphoric acid (8.5 MPa).

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MATERIALS AND METHODSMATERIALS AND METHODS The present study was conducted in the Department of The present study was conducted in the Department of

Orthodontics and Dentofacial Orthopedics, Sibar Orthodontics and Dentofacial Orthopedics, Sibar Institute of Dental Sciences, Takkellapdu, Guntur and Institute of Dental Sciences, Takkellapdu, Guntur and Department of Organic Coatings & Polymers, Indian Department of Organic Coatings & Polymers, Indian Institute of Chemical Technology, Habsiguda, Institute of Chemical Technology, Habsiguda, SecunderabadSecunderabad

Sixty human maxillary premolar teeth extracted for Sixty human maxillary premolar teeth extracted for therapeutic purposes from patients seeking orthodontic therapeutic purposes from patients seeking orthodontic treatment in the Department of Orthodontics and treatment in the Department of Orthodontics and Dentofacial Orthopedics, Sibar institute of dental Dentofacial Orthopedics, Sibar institute of dental sciences were collected & stored in normal saline after sciences were collected & stored in normal saline after treating them with hydrogen peroxide for one week.treating them with hydrogen peroxide for one week.


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Inclusion & Exclusion Criteria for Teeth Inclusion & Exclusion Criteria for Teeth Selection:Selection:

Teeth with no signs of cariesTeeth with no signs of caries

Teeth free of restorationsTeeth free of restorations

Teeth with no cracks on the crown as a result of the Teeth with no cracks on the crown as a result of the pressure of the extraction forceps. pressure of the extraction forceps.

Teeth with no cement remnants as a result of previous Teeth with no cement remnants as a result of previous orthodontic treatment.orthodontic treatment.

Teeth with fluorosis, hypoplasia or abnormalities of Teeth with fluorosis, hypoplasia or abnormalities of crown morphology, which may have affected bracket crown morphology, which may have affected bracket bonding, were bonding, were excludedexcluded..


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GLASS IONOMER CEMENT USED TO CEMENT PFM'S ON EXTRACTED MAXILLARY PREMOLARS

TEETH MOUNTED IN TEETH MOUNTED IN ACRYLIC BLOCKSACRYLIC BLOCKS


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Fifty Porcelain Fused Metal crowns were fabricated over Fifty Porcelain Fused Metal crowns were fabricated over the extracted maxillary premolar teeth after crown the extracted maxillary premolar teeth after crown preparation for the study purpose, preparation for the study purpose,

and ten extracted natural maxillary premolar teeth were and ten extracted natural maxillary premolar teeth were acid etched in conventional manner using 37% acid etched in conventional manner using 37% phosphoric acid for 30 seconds phosphoric acid for 30 seconds

Composite bonding was done which acted as controls to Composite bonding was done which acted as controls to compare the bond strength with Porcelain Fused Metal compare the bond strength with Porcelain Fused Metal crowns.crowns.


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MATERIALS USED FOR THE STUDY

DENTSPLY QHL75 LITE USA DENTSPLY QHL75 LITE USA VISIBLE LIGHT CURING UNIT VISIBLE LIGHT CURING UNIT AND OTHER BONDING AND OTHER BONDING MATERIALS USED IN THE MATERIALS USED IN THE STUDYSTUDY


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Methods Methods Bonding procedure:Bonding procedure: The teeth collected were grouped The teeth collected were grouped

into six groups of ten each (Group I to Group VI) into six groups of ten each (Group I to Group VI)

And Following six protocols were executed for surface And Following six protocols were executed for surface preparation.preparation.

Group I:Group I: Orthodontic brackets were bonded to enamel Orthodontic brackets were bonded to enamel surfaces on ten teeth in Group I which acted as control surfaces on ten teeth in Group I which acted as control group, teeth were acid etched with 37% phosphoric acid group, teeth were acid etched with 37% phosphoric acid gel for 30 seconds, thoroughly washed, and air dried using gel for 30 seconds, thoroughly washed, and air dried using 3-in-1syringe, followed by application of primer & 3-in-1syringe, followed by application of primer & bonding agent (Transbond XT 3M, light cured composite bonding agent (Transbond XT 3M, light cured composite resin). resin). www.indiandentalacademy.comwww.indiandentalacademy.com

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Group II:Group II: etched with 37% phosphoric acid gel for 30 etched with 37% phosphoric acid gel for 30 seconds, teeth were thoroughly washed, and air dried using seconds, teeth were thoroughly washed, and air dried using 3-in-1syringe, followed by application of primer & bonding 3-in-1syringe, followed by application of primer & bonding agent. agent.

Group III:Group III: etched with 9% Hydrofluoric acid for 90 etched with 9% Hydrofluoric acid for 90 secondsseconds

Group IV:Group IV: were air abraded using 30 µm aluminum oxide were air abraded using 30 µm aluminum oxide particles from 10 mm distance with 250 Kpa pressure for 2-particles from 10 mm distance with 250 Kpa pressure for 2-3 seconds using sand blaster machine, & etched with 9% 3 seconds using sand blaster machine, & etched with 9% Hydrofluoric acid for 90 seconds,. Hydrofluoric acid for 90 seconds,.


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SAND BLASTING WITH 30 µm ALUMINUM OXIDE PARTICLES

FINE DIAMOND BUR 30 µm BRASSELER LEMGO

GERMANY


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Group V:Group V: were air abraded using 30 µm aluminum oxide were air abraded using 30 µm aluminum oxide particles from 10 mm distance with 250 Kpa pressure for 2-particles from 10 mm distance with 250 Kpa pressure for 2-3 seconds using sand blaster machine, followed by two 3 seconds using sand blaster machine, followed by two coats of silane coupling agent application and air dried. coats of silane coupling agent application and air dried.

Group VI:Group VI: Orthodontic brackets were bonded on ten Orthodontic brackets were bonded on ten Porcelain Fused Metal crowns belonging to Group VI, Porcelain Fused Metal crowns belonging to Group VI, which were roughened using Fine diamond bur 30 μm. which were roughened using Fine diamond bur 30 μm.

Subsequent to bondingSubsequent to bonding, the samples were , the samples were stored in stored in distilled water distilled water at physiological temperature (37ºC) for 1 at physiological temperature (37ºC) for 1 day, day,

and and thermocycledthermocycled 500 times between 5°C and 55°C with a 500 times between 5°C and 55°C with a dwelling time of 30 seconds using a computerised dwelling time of 30 seconds using a computerised thermocycling device (Nova Inc., Konya, Turkey) prior to thermocycling device (Nova Inc., Konya, Turkey) prior to shear bond strength testing.shear bond strength testing.www.indiandentalacademy.comwww.indiandentalacademy.com

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FINE DIAMOND BUR ROUGHENING

SILANE APPLICATION


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BRACKET PLACEMENT

LIGHT CURING AFTER BRACKET PLACEMENT www.indiandentalacademy.comwww.indiandentalacademy.com

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Shear Bond Strength Testing Shear Bond Strength Testing In order to maintain a In order to maintain a consistent debonding force in a controlled direction, teeth consistent debonding force in a controlled direction, teeth were mounted on to an acrylic jig. Facial surface of the were mounted on to an acrylic jig. Facial surface of the porcelain crown was kept exactly parallel to the debonding porcelain crown was kept exactly parallel to the debonding force or perpendicular to the floor. force or perpendicular to the floor.

SBS SBS was recorded with a universal testing machine (was recorded with a universal testing machine (Autograph Autograph Model AGS 10 ANG, Shimadzu, Japan). Model AGS 10 ANG, Shimadzu, Japan).

A crosshead speed of 1mm/min A crosshead speed of 1mm/min was used. was used.


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Debonded surfaces were observed under a Debonded surfaces were observed under a scanning scanning electron microscope electron microscope for the types of failures after the for the types of failures after the debonding procedure. debonding procedure.

Following debonding, the surfaces under the debonded Following debonding, the surfaces under the debonded brackets were coated with gold and palladium solution to brackets were coated with gold and palladium solution to prepare the specimens for viewing under scanning electron prepare the specimens for viewing under scanning electron microscope model Hitachi- S520, Japan; Oxford Link ISIS-microscope model Hitachi- S520, Japan; Oxford Link ISIS-300 UK at 500x and 1500x magnifications. 300 UK at 500x and 1500x magnifications.


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RESULTSRESULTS

The data was normally distributed and the results were The data was normally distributed and the results were tabulated and statistically analyzed using the S.P.S.S. 10 tabulated and statistically analyzed using the S.P.S.S. 10 statistical analysis package software. statistical analysis package software.

Shear bond strength in Megapascals (Mpa) and Standard Shear bond strength in Megapascals (Mpa) and Standard Deviation (±SD) for shear bond strength of brackets Deviation (±SD) for shear bond strength of brackets bonded to porcelain fused metal surfaces were bonded to porcelain fused metal surfaces were represented individually by tables for easy observation. represented individually by tables for easy observation.


maxmaximumimum mean shear bond strength of a sample mean shear bond strength of a sample belonged to belonged to group Vgroup V which was sandblasting with silane which was sandblasting with silane application 12.34 ± 0.95 Mpaapplication 12.34 ± 0.95 Mpa

and and minimumminimum belonged to belonged to group II group II which was acid which was acid etching with 37% phosphoric acid gel for 30 seconds 5.51 etching with 37% phosphoric acid gel for 30 seconds 5.51 ± 0.88 MPa. ± 0.88 MPa.

9% Hydrofluoric acid (9% Hydrofluoric acid (group IIIgroup III) showed the second ) showed the second highest shear bond strength mean values 11.48 ± 0.98 highest shear bond strength mean values 11.48 ± 0.98 MPa. MPa.

group IV group IV which was Sandblasting and 9% Hydrofluoric which was Sandblasting and 9% Hydrofluoric acid showed a bond strength of 7.96 ± 1.07 MPa acid showed a bond strength of 7.96 ± 1.07 MPa


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Table I: Summary statistics according to groups

Groups Minimum Maximum Range Mean Std.Dev. SE Median

Group I 9.01 13.61 4.60 11.03 1.63 0.51 10.84

Group II 3.82 7.01 3.19 5.51 0.88 0.28 5.52

Group III 10.11 13.54 3.43 11.48 0.98 0.31 11.29

Group IV 6.22 9.49 3.27 7.96 1.07 0.34 8.10

Group V 10.98 13.93 2.95 12.34 0.95 0.30 12.08

Group VI 7.27 11.21 3.94 9.28 1.11 0.35 9.16

and group VI which was Fine diamond bur roughening with silane application showed mean values of 9.28 ± 1.11 MPa

and group I which was control group (37% phosphoric acid) showed shear bond strength mean values of 11.03 ± 1.63 MPa


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11.0

3

1.63

5.51

0.88

11.4

8

0.98

7.96

1.07

12.3

4

0.95

9.28

1.11

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00M

ean

shea

r bon

d str

engt

h

Group I Group II Group III Group IV Group V Group VI

Figure: Comparison of mean shear bond strength in six groups

Mean Std.Dev.www.indiandentalacademy.comwww.indiandentalacademy.com

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Parametric tests for comparison of six groups Parametric tests for comparison of six groups by one by one way ANOVAway ANOVA test and Pair wise comparison of six test and Pair wise comparison of six groups by groups by Newman-Keuls multiple comparison post Newman-Keuls multiple comparison post hoc procedure were done.hoc procedure were done.

Both the tests showed significant difference between and Both the tests showed significant difference between and within the groups in shear bond strength and P value also within the groups in shear bond strength and P value also was highly significant, i.e. ***p<0.001was highly significant, i.e. ***p<0.001..


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Scanning Electron microscope ResultsScanning Electron microscope Results The SEM photomicrographs of all the six different surface The SEM photomicrographs of all the six different surface

preparations revealed different surface morphologies. preparations revealed different surface morphologies.

For the porcelain-fused-metal crowns treated with 30 μm For the porcelain-fused-metal crowns treated with 30 μm Al2O3 and Fine diamond bur 30 μm, loss of the glazed Al2O3 and Fine diamond bur 30 μm, loss of the glazed surface and mild roughening were seen. surface and mild roughening were seen.

Uniform peeling or an erosive appearance with shallow Uniform peeling or an erosive appearance with shallow penetration and undercuts was observed when compared penetration and undercuts was observed when compared with chemical etching. with chemical etching.

Hydrofluoric acid etching demonstrated mild roughening Hydrofluoric acid etching demonstrated mild roughening of the surface and orthophosphoric acid etching produced of the surface and orthophosphoric acid etching produced minimal change and did not appear to alter the glazed minimal change and did not appear to alter the glazed porcelain surfaces. porcelain surfaces. www.indiandentalacademy.comwww.indiandentalacademy.com

ORTHO PHOSPHORIC ACID AT ORTHO PHOSPHORIC ACID AT 1500X(GROUP II1500X(GROUP II))

CONTROL GROUP ORTHOPHOSPHORIC ACID AT 500 X (GROUP I)

CONTROL GROUP ORTHOPHOSPHORIC ACID AT 1500 X(GROUP I)

ORTHO PHOSPHORIC ACID AT 550 X(GROUP II)


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HYDROFLUORIC ACID AT 1500 X(GROUP III)

HYDROFLUORIC ACID AT 500 X(GROUP III)

SAND BLAST + HF ACID AT 500 X(GROUP IV)

SAND BLAST + HF ACID AT 1500 X(GROUP IV)


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SAND BLSATING + SILANE AT 500 X(GROUP V)

SAND BLSATING + SILANE AT 1500 X (GROUP V)

FINE DIAMOND BUR ROUGHENING AT 500 X(GROUP VI)

FINE DIAMOND BUR ROUGHENING AT 1500 X(GROUP VI)


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DiscussionDiscussion Even though the clinical relevance of in-vitro studies is considered to be limited, the mean shear bond strengths of metal brackets to ceramic surfaces in this study generally exceeded acceptable limits (except for 37% phosphoric acid) and therefore can be considered sufficient for clinical situations.

The clinical forces may dislodge the brackets in single traumatic incident (comparable to the universal debonding machine in vitro) or as a result of repeated stresses.

To overcome the above said limitations thermocycling is required to test the bond strength of brackets to ceramics, as it induces artificial aging and stresses at the level of various thermal expansion coefficients of metal, resin and ceramic materials. www.indiandentalacademy.comwww.indiandentalacademy.com

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Group I - 37% Phosphoric acid Group I - 37% Phosphoric acid Orthodontic brackets bonded to enamel surfaces on ten Orthodontic brackets bonded to enamel surfaces on ten

natural teeth gave clinically acceptable and significant natural teeth gave clinically acceptable and significant bond strength of 11.03 ± 1.63 MPa. bond strength of 11.03 ± 1.63 MPa.

Group II - 37% Phosphoric acid Group II - 37% Phosphoric acid Porcelain surface preparation using 37 % Phosphoric acid Porcelain surface preparation using 37 % Phosphoric acid

gave significantly low SBS of 5.51 ± 0.88 MPa. These gave significantly low SBS of 5.51 ± 0.88 MPa. These results were not in acceptable range for the orthodontic results were not in acceptable range for the orthodontic bondingbonding..

Group III - 37% Hydrofluoric acid Group III - 37% Hydrofluoric acid Preparation with Hydrofluoric acid (HFA) produced Preparation with Hydrofluoric acid (HFA) produced

significantly high bond strength of 11.48 ± 0.98 MPa, significantly high bond strength of 11.48 ± 0.98 MPa, which was similar to the reports of previous studieswhich was similar to the reports of previous studies..


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Surface conditioning with HFA successfully increased Surface conditioning with HFA successfully increased the adhesion of the composite resin to the porcelain the adhesion of the composite resin to the porcelain surfaces by producing physical or topographical changes surfaces by producing physical or topographical changes in the porcelain surface. in the porcelain surface.

This was an expected result as HFA facilitates This was an expected result as HFA facilitates micromechanical retention between porcelain and micromechanical retention between porcelain and composite resin.composite resin.

When the two acids, HFA and Phosphoric acid were When the two acids, HFA and Phosphoric acid were compared, higher bond values were obtained in the HF compared, higher bond values were obtained in the HF acid treated group. acid treated group.

- - However, HFA should be used with great care as it is However, HFA should be used with great care as it is capable of causing severe trauma to soft tissues and tooth capable of causing severe trauma to soft tissues and tooth substance (Hayakawa et al., 1992). substance (Hayakawa et al., 1992). www.indiandentalacademy.comwww.indiandentalacademy.com

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Group IV – Sand blasting + Hydrofluoric acid Group IV – Sand blasting + Hydrofluoric acid In the mechanical preparation we used sandblasting in In the mechanical preparation we used sandblasting in

combination with 9% hydrofluoric acid etching and bracket combination with 9% hydrofluoric acid etching and bracket bonding with composite material. bonding with composite material.

Surface preparation with 30 µm Al2O3 particles produced a Surface preparation with 30 µm Al2O3 particles produced a uniform peeling appearance of the porcelain with deeper uniform peeling appearance of the porcelain with deeper penetration and more undercuts compared to roughening; penetration and more undercuts compared to roughening; which increased potential mechanical retention. which increased potential mechanical retention.

Hydrofluoric acid further acted by dissolving the crystalline Hydrofluoric acid further acted by dissolving the crystalline and glassy phase of the ceramicand glassy phase of the ceramic(But this combination also (But this combination also seemed to cause irreversible alteration to the porcelain surface)seemed to cause irreversible alteration to the porcelain surface)


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Group V – Sand blasting + SilaneGroup V – Sand blasting + Silane

Gave the maximum SBS value in this study, which is Gave the maximum SBS value in this study, which is 12.34 ± 0.95 MPa. 12.34 ± 0.95 MPa.

These results were comparable to the previous studies done These results were comparable to the previous studies done by Kocadereliby Kocadereli et al et al. and Schmage . and Schmage et alet al. In contrast, . In contrast, Zachrisson reported earlier to these studies that silane Zachrisson reported earlier to these studies that silane application to sandblasted porcelain did not provide application to sandblasted porcelain did not provide clinically acceptable bond strengths and suggested clinically acceptable bond strengths and suggested abandoning this technique. abandoning this technique.


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In a study carried out by Tamer Türk In a study carried out by Tamer Türk et al. et al. stated thatstated that ssamples coated with silane, but not exposed to chemical or amples coated with silane, but not exposed to chemical or mechanical roughening, were considered as the control mechanical roughening, were considered as the control group but demonstrated bond failures during group but demonstrated bond failures during thermocycling. thermocycling.

Barbosa Barbosa et al. et al. (1995) reported the premature loss of (1995) reported the premature loss of brackets bonded to glazed ceramic surfaces coated with brackets bonded to glazed ceramic surfaces coated with silane after 7 days of water immersion. silane after 7 days of water immersion.

They explained that this premature loss was due to the They explained that this premature loss was due to the high solubility of silane in water. high solubility of silane in water.


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Group VI – Fine Diamond Bur roughening + SilaneGroup VI – Fine Diamond Bur roughening + Silane - Gave an SBS of 9.28 ± 1.11 MPa. - Gave an SBS of 9.28 ± 1.11 MPa. Barbosa Barbosa et al.et al. (1995)In their study stated that roughening (1995)In their study stated that roughening

with coarse diamond burs resulted in higher SBS when with coarse diamond burs resulted in higher SBS when compared with other groups, i.e. glazed and deglazed compared with other groups, i.e. glazed and deglazed surfaces with sandpaper disks. surfaces with sandpaper disks.

Silane presents a chemical link between the dental ceramic Silane presents a chemical link between the dental ceramic and the composite resin, and the organic portion of the and the composite resin, and the organic portion of the molecule enhances the wettability of the ceramic surface, molecule enhances the wettability of the ceramic surface, thereby displaying a closer micromechanical bond (Lu thereby displaying a closer micromechanical bond (Lu et et al.al., 1992)., 1992).

However, in order to obtain a viable bond between the However, in order to obtain a viable bond between the orthodontic bracket and the ceramic surface, mechanical orthodontic bracket and the ceramic surface, mechanical or chemical roughening is inevitable (Wood or chemical roughening is inevitable (Wood et al.,et al., 1986; 1986; Kao Kao et al. et al. , 1988 ; Barbosa , 1988 ; Barbosa et al. et al. , 1995 ; Gillis and , 1995 ; Gillis and Redlich,1998 ; Huang and Kao, 2001Redlich,1998 ; Huang and Kao, 2001


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Shortcomings of the studyShortcomings of the study

Although the results obtained in this study can be Although the results obtained in this study can be helpful for selection of the most effective method for helpful for selection of the most effective method for bonding orthodontic brackets to PFM’s clinically, it is bonding orthodontic brackets to PFM’s clinically, it is important to be updated with the continuous important to be updated with the continuous development of newer ceramic systems used these days. development of newer ceramic systems used these days.

This study was carried out only on feldspathic ceramics This study was carried out only on feldspathic ceramics with porcelain fused metal surfaces, and didn’t consider with porcelain fused metal surfaces, and didn’t consider all ceramic crowns, other ceramic types like Zirconia all ceramic crowns, other ceramic types like Zirconia based ceramics, leucite or lithium disilicate, composite based ceramics, leucite or lithium disilicate, composite restoration surfaces.restoration surfaces.


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Conclusion Conclusion Sand blasting followed by application of Silane (group V) Sand blasting followed by application of Silane (group V)

produced maximum bond strength comparable or even produced maximum bond strength comparable or even better than the control group followed by groups III and better than the control group followed by groups III and VI.VI.

37% Ortho Phosphoric acid (group II) produced least SBS 37% Ortho Phosphoric acid (group II) produced least SBS and hence not suitable for bonding Othodontic brackets in and hence not suitable for bonding Othodontic brackets in a clinical scenarioa clinical scenario..

Even though groups III and VI produced clinically Even though groups III and VI produced clinically acceptable SBS values, because of their technique acceptable SBS values, because of their technique sensitivity and side effects, they have to be used with great sensitivity and side effects, they have to be used with great care and caution.care and caution.

The best porcelain surface conditioning method The best porcelain surface conditioning method recommended clinically for bonding Orthodontic brackets recommended clinically for bonding Orthodontic brackets to porcelain fused metal crowns was to porcelain fused metal crowns was sand blasting sand blasting followed by the application of Silane coupling agentfollowed by the application of Silane coupling agent..



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