1. DEPARTMENT OF ORTHODONTICS MAULANA AZAD INSTITUTE OF DENTAL SCIENCES
NEW DELHI
SHEAR BOND STRENGTH OF ORTHODONTIC BONDING AGENTS----A COMPARATIVE PILOT STUDY
NAME OF THE STUDENT : DR. RAJKUMAR R.MAURYA

2. INTRODUCTION
The acid etch technique, first suggested by Buonocore, led to techniques that markedly improved bonding to enamel.
This technique was suggested for orthodontic use by Newman and is now widely accepted.
The merits of direct bonding include benefits for both the patient and the practitioner.

3. ADVANTAGE OF DIRECT BONDING
Decreased gingival irritation
Improved esthetics
Easier plaque removal by the patient
Elimination of pretreatment separation
Elimination of band occupying interdental spaces,
Decreased risk of decalcification of enamel,
Easier detection and treatment of dental caries by the practitioner.

4. MATERIALS USED FOR DIRECT BONDING
Historically, Bisphenol A glycidyl dimethacrylate, more commonly known as Bowen’s resin or bis-GMA, was patented in 1962 and is a diacrylate resin.
This resin is an acrylic-modified epoxy resin, combining the setting versatility of acrylic and the strength and dimensional stability of epoxy. .
Addition of filler particles to these resins to form composites greatly enhanced the strength of this material.

5. Wilson and Kent introduced glass polyalkenoate, or GIC, to dentistry in 1972.
GIC contains a powder similar to that of silicate cement and a polyacrylic liquid similar to that of polycarboxylate cement.
It bonds chemically to enamel, cementum, dentin, nonprecious metals, and plastics.

6. In response to the demand for improvement of the original product, Antonucci introduced resin modified glass ionomer cements (RMGICs) in 1988.
Light activated RMGICs were formulated to overcome the problems of moisture sensitivity of composites and low early mechanical strength of glass ionomers while maintaining the clinical advantages of conventional glass ionomers.
A small amount of resin in addition to a photo initiator was added to conventional GIC.

7. Tavas and Watts first described the use of visible light to cure composites used in orthodontic bonding in 1979.
RECENT BONDING MATERIALS
Colour changing LC composite bonding material
MIP

8. LACUNAE IN EXISTING KNOWLEDGE
Although many studies have been done so far for comparison & determination of shear bond strength of light cure resin based glass ionomer cement & composite resin cement, there is still some paucity of knowledge regarding shear bond strength of color changing orthodontic bonding agents & its relative strength in comparison to conventional agents.
Sample size that had been used in past needs to be expanded to reduce errors in studies & produce more authentic results.

9. AIMS & OBJECTIVES
Determination of shear bond strength of various Light-cured orthodontic bonding agents:
Glass-ionomer resin cement
Composite-resin based bonding agent with conventional etch & self etch primer
Color changing bonding agent with conventional etch & self etch primer
Comparative evaluation of these bonding materials to determine the most suitable one.

10. MATERIALS & METHOD
Proposed study had been conducted in the Department of Orthodontics, Maulana Azad Institute of Dental Sciences, New Delhi on extracted human teeth.

11. Criteria for selection
TEETH
300 extracted human teeth were selected according to the following inclusion criteria
Tooth with intact buccal enamel with no cracks due to pressure of extraction forceps .
No carious lesion should be present.
No chemical treatment should be done during storage.

13. BRACKETS
Edgewise stainless steel brackets with the curved base bonded to all extracted human teeth.
Brackets were identical for each tooth.

14. LC BONDING AGENTS
Resin based glass ionomer adhesive
Composite resin with conventional etchant
Composite resin with self etch primer
Composite based resin that changes color during setting that with conventional etchant.
Composite based resin that change color during setting with self etch primer

16. SHEAR STRENGTH MEASUREMENT
Instron Universal Testing Machine was used for shear bond strength analysis.

17. METHODOLOGY
Extracted human teeth were collected over a period of 3 months.
Teeth were stored in normal saline till the use.
Before the experiment, teeth were debrided, washed in water, treated with non fluoride containing pumice & water rinsed & randomly assigned to 5 equal groups.
Each group containd 60 teeth.

18. BONDING PROTOCOL GROUP 1: LIGHT CURE RESIN BASED GLASS IONOMER CEMENT
The enamel surface were conditioned with 10% of polyacrylic acid, rinsed with water, light dried. Surface were kept moistened with water until bracket containing mixed cement were bonded to the conditioned enamel surface & light cured

19. GROUP 2: CONVENTIONAL COMPOSITE BASED RESIN
The enamel surface were etched with 37% orthophosphoric acid, rinsed with air-water syringe to remove acidic gel & any demineralized tooth particle, dried for 5 seconds with air, coated with unfilled resin.
Conventional composite based resin adhesive loaded bracket were placed in firm contact with tooth surface & flash removed.

20. GROUP 3: CONVENTIONAL COMPOSITE WITH SELF ETCH PRIMER
Self etch primer were applied on the enamel surface. Conventional composite based resin adhesive loaded bracket were placed in firm contact with tooth surface & flash was removed & light cured.

21. GROUP 4: COLOR CHANGING ORTHODONTIC BONDING AGENT WITH CONVENTIONAL ACID ETCH TECHNIQUE
Same procedure were followed as for group 2.instead of conventional composite, color changing bonding adhesive were used.

22. GROUP 5: COLOR CHANGING ORTHODONTIC BONDING AGENT WITH SELF ETCH PRIMER
Same procedure were followed as for group 3.instead of conventional composite, color changing bonding adhesive were used.

23. Etching & light curing were done according to manufacturer’s instruction for all bonding agents.
After bonding the specimens were stored in distilled water.
All five groups of bonding were done at room temperature & by same operator.

24. DEBONDING PROCEDURE
Debonding procedure were carried out at same time interval for every tooth after bonding.
Occluso-gingival load were applied to the bracket, producing shear force at the bracket- tooth interface using an attachment to the crosshead of INSTRON UNIVERSAL TESTING MACHINE.
A computer electronically connected with the INSTRON machine recorded the result of each test.

25. STATISTICAL ANALYSIS
Comparison of the mean strength among the 5 group were observed by ANOVA or KRUSKAL WALLIS one way ANOVA followed by post hoc test.
‘P’< 0.05 were considered as significant level

26. RESULTS AND CONCLUSION
The present investigation was an in-vitro study conducted on three hundred extracted human premolars for determination of shear bond strength of different bonding adhesives.
The following conclusions were made.
Mean shear bond strength in Group I, II, III IV and V was found to be , , , and respectively.

27. Conventional composite resin with conventional etchant group showed the highest shear bond strength hence found to be the strongest orthodontic bonding adhesive.
Glass ionomer resin adhesive has lowest shear bond strength value among all the materials tested in this study hence found to be the weakest bonding adhesive among study Groups.

28. There was no statistically significant difference between conventional composite used with conventional etchant and colour changing composite resin when used with conventional etchant or with self etch primer.
Considering the advantage of colour changing composite and self etch primer without compromising the shear bond strength, colour changing composite used with self etch primer was the most suitable material for direct bonding as found in the present investigation.

29. THANK U!