CERAMIC BRACKETS BONDED USING MONOWAVE AND POLYWAVE LIGHT EMITTING DIODE CURING UNITS - AN INVITRO STUDY
Dissertation submitted to
THE TAMIL NADU DR. M.G.R. MEDICAL UNIVERSITY
In partial fulfilment for the degree of
MASTER OF DENTAL SURGERY
BRANCH - V
ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS
APRIL - 2017
TITLE OF DISSERTATION
Comparison of shear bond strength of orthodontic metal and ceramic brackets bonded using monowave and polywave light emitting diode curing units – An invitro study
PLACE OF STUDY K.S.R. Institute of Dental Science and Research.
DURATION OF COURSE 3 Years
NAME OF THE GUIDE Dr. K.P. Senthil Kumar, M.D.S., HEAD OF THE DEPARTMENT Dr. K.P. Senthil Kumar, M.D.S.,
I hereby declare that no part of the dissertation will be utilized for gaining financial assistance for research or other promotions without obtaining prior permission of the Principal, K.S.R Institute of Dental Science and Research, Tiruchengode. In addition, I declare that no part of this work will be published either in print or electronic without the guide who has been actively involved in dissertation. The author has the right to reserve for publish of work solely with prior permission of the Principal, K.S.R Institute of Dental Science and Research, Tiruchengode.
Head of the Department Signature of candidate
CERTFICATE BY THE GUIDE
This is to certify that dissertation titled “COMPARISON OF SHEAR BOND STRENGTH OF ORTHODONTIC METAL AND CERAMIC BRACKETS BONDED USING MONOWAVE AND POLYWAVE LIGHT EMITTING DIODE CURING UNITS” is a bonafide research work done by Dr.R.B. Sri Meenakshi, in partial fulfillment of the requirements for the degree of MASTER OF DENTAL SURGERY in the specialty of Orthodontics and Dentofacial Orthopedics.
Date:
Place:
Signature of the Guide Dr. K.P. Senthil Kumar, M.D.S.,
Professor.
K.S.R. Institute of Dental Science and Research,
Tiruchengode.
ENDORSEMENT BY THE H.O.D, PRINCIPAL/ HEAD OF THE INSTITUTION
This is to certify that the dissertation entitled “COMPARISON OF SHEAR BOND STRENGTH OF ORTHODONTIC METAL AND CERAMIC BRACKETS BONDED USING MONOWAVE AND POLYWAVE LIGHT EMITTING DIODE CURING UNITS – AN INVITRO STUDY” post graduate student (M.D.S), Orthodontics and Dentofacial Orthopaedics (Branch -V), KSR Institute of Dental Science and Research, Tiruchengode, submitted to the Tamil Nadu Dr. M.G.R Medical University in partial fulfilment for the M.D.S degree examination (April 2017) is a bonafide research work carried out by him under my supervision and guidance.
Seal and signature of H.O.D Seal & signature of Principal
PROF. DR. K.P. SENTHIL KUMAR, M.D.S., PROFESSOR AND GUIDE
PROF. DR. G.S. KUMAR., M.D.S.
PRINCIPAL
K.S.R. INSTITUTE OF DENTAL SCIENCE AND RESEARCH
TIRUCHENGODE
S.NO TITLE PAGE NO.
1 INTRODUCTION 1
2 AIMS AND OBJECTIVES 4
3 REVIEW OF LITERATURE 5
4 MATERIALS AND METHODS 26
5 STATISTICAL ANALYSIS 38
6 RESULTS 39
7 DISCUSSION 44
8 SUMMARY AND CONCLUSION 49
9 BIBLIOGRAPHY 50
10 ANNEXURE 59
FIGURE
NO: TITLE
PAGE NO:
1 Metal , Ceramic brackets used in the study 32
2 Monowave and Polywave LED light, Bonding materials 33
3 Teeth samples mounted in acrylic blocks 34
4 Light curing method 35
5 Universal testing machine and bond strength test 36
6 Optical stereomicroscope and the sample specimen 37
7 Stereomicroscopic picture to determine ARI 37
S.NO Title PAGE NO.
1 Classification of samples into four groups 28 2 Shear force / peak load values and the bond strength values of
all four groups 39
3 Mean and SD of shear bond strength values in mega pascals
( MPa) for all groups 40
4 Comparison of shear bond strength of metal brackets cured with
monowave LED and polywave LED 41
5 Comparison of shear bond strength of ceramic brackets cured
with monowave LED and polywave LED 41
6 Comparison of shear bond strength of metal and ceramic
bracket cured with monowave LED 41
7 Comparison of shear bond strength of metal and ceramic
bracket cured with polywave LED 41
8 Comparison of shear bond strength of metal and ceramic brackets
42 9 Frequency distribution of the Adhesive Remnant Index ( ARI )
and enamel fracture of the 4 groups evaluated 42
ACKNOWLEDGEMENT
With immense gratitude and respect, I thank Professor Dr.K.P. Senthil Kumar, M.D.S., Professor and Head of the department and my guide for his valuable guidance, support and encouragement throughout the study.
I owe my thanks and great honour to Professor Dr.S. Tamizharasi,M.D.S., for helping me with her valuable and timely suggestions and encouragement.
I am grateful to my department staffs Dr.M .Karthi,M.D.S., Dr.S. Raja,M.D.S., Dr.K.
Prabhakar,M.D.S., for their guidance and support.
My sincere thanks to Professor Dr.G.S. Kumar,M.D.S., Principal, KSR Institute of Dental Science and Research, for his kind support and encouragement and to chairman of KSR group of institutions,Thiru Lion.Dr.K.S. Rangasamy, MJF for providing me the opportunity to do postgraduation in this institution.
I take this opportunity to express my gratitude to my seniors and juniors, friends, non- teaching staffs and colleagues for their valuable help and suggestions throughout this study.
I offer my heartiest gratitude to my family members for their selfless blessing.
I seek the blessings of the Almighty, the God, without whose benevolence, the study would not have been possible.
Page 1
INTRODUCTION
Orthodontic treatment has revolutionized with the development of new inventions and innovations in materials and techniques. Bonding is an important orthodontic milestone that replaced the arduous task of banding and then the evolution of fixed appliance became popular. The ability to bond orthodontic brackets has reduced patient chairside time, reduced the band space that needed to be closed at finishing, improved the esthetics and aided in the improvement of oral hygiene. Direct bonding became popular after the contributions of the pioneers such as Michael G. Buonocore (1955 )16 suggested a surface acid treatment of enamel by 85% phosphoric acid for 30 seconds similar to that used in the paint industry to render the enamel more receptive to adhesion. The basis of bonding material, the Bisphenyl Glycidyl Dimethacrylate ( BISGMA) resin was introduced in 1956 by Rafael L. Bowen which led to the first successful production of a composite resin for filling teeth. Newman (1965 ) introduced direct bonding as a viable clinical technique and then orthodontic bonding developed as an excellent alternative to banding.
The chemically activated curing system has limitations such as the short working time for the operator and the light curing systems has advantages such as extended working time to position brackets and clean up flash and ability to place archwires immediately. In the development of light curing units due to safety and efficacy concerns the UV curing of restorative materials was replaced in 1978 by visible light curing and then quartz tungsten halogen units dominated the market for almost two decades and around 1995 Robin Mills stated the possibility of LED units for curing24 and also QTH and UV units were heavy and bulky compared to today‟s LED unit .
Page 2 The quartz tungsten halogen produced a broad emission spectrum ( 300 – 1000 nanometer range ) most of the light emitted in the UV and infra red regions that are outside the spectral absorption of camporoquinone(CQ), the principal resin photoinitiator used in dentistry61 must be blocked out using filter. QTH units gets hot and requires cooling fans. Plasma arc curing and argon laser curing became popular because of rapid curing3,4 and benefits of saving time but they were very expensive to purchase and maintain and are large units. Now small LED units are replacing their QTH and PAC Predecessors.
In the generations of LED , early in first generation LED units delivered a narrow spectral emission compared with QTH units and they require longer exposure times because of their low radiant power output, manufactures designed LCU to fit multiple LED emitters ( some had 64 LEDs in gun style)72, some manufacturers managed to have nineteen LED in pen style LED LCU which is battery powered. The second generation units resolved this problem by using smaller but much powerful blue LED chips.
Further development on LCUs has seen the introduction of broad spectrum “Polywave” LED LCUs that use upto four LED emitters each producing different wavelengths of light. These units are designed to simulate the broader spectrum of QTH and PAC units for activating materials containing alternative photoinitiators1. The benefits of broad spectrum polywave LED units relative to blue LED „ monowave‟ unit is topic for debate given the majority of practising dentists use exclusively CQ – initiated resin based materials. As Camporoquinone has an intense yellow colour due to its absorption properties, alternative initiators are for instance employed in the formulations of composites in bleach shades and colourless protective varnishes. Polywave units may enhance the polymerization and surface properties of resins that contain alternative photoinitiators in addition to CQ such as Lucirin TPO. This photoinitiator has gained popularity because it completely bleaches out after the light reaction is finished. The peak sensitivity of Camporoquinone is near 470 nm in the blue wavelength
Page 3 range whereas for Lucirin TPO the peak absorption is around 390 nm nearing the UV range.
Polywave LED achieves a spectral peak at approx. 410 nm and 470 nm which covers the wavelength range of 380 to 515 nm. In terms of light intensity their high intensity range nears that of Plasma arc curing, so curing time can be reduced .
However , the output from current polywave LED units is not spatially or spectrally uniform across the face of the light tip70, also the shorter violet wavelengths do not penetrate through the resin based composite as deeply as the blue light , the depth of cure may not be uniform.
Eventhough polywave LED is beneficial for a practitioner for curing not only the conventional composite but also other restorative materials or liners or adhesives containing non camporoquinone initiators, its orthodontic efficacy is need to be evaluated, so my study is undertaken to compare the shear bond strength of orthodontic brackets bonded using the second generation monowave LED with the newer generation polywave LED. Nowadays ceramic brackets are an esthetic alternative to conventional SS metal brackets and because of its high light transmission capacity through the bracket , the high intensity curing light can be very efficient in curing ceramic brackets than the SS metal brackets. So in this study the shear bond strength of ceramic brackets cured with monowave and polywave LED curing lights are also evaluated.
Page 4
AIM OF THE STUDY
The aim of the invitro study is to evaluate and compare the shear bond strength of orthodontic metal and ceramic brackets bonded using monowave and polywave light emitting diode curing units .
OBJECTIVES OF THE STUDY
1) To evaluate the shear bond strength of metal (stainless steel) and ceramic brackets (polycrystalline) bonded using two different light emitting diode curing units (monowave or single peak polymerization LED which is a second generation LED and polywave LED or dual peak polymerization LED which is a third generation LED).
2) To compare the shear bond strength of brackets bonded using monowave and polywave LED curing units.
3) To compare the shear bond strength of metal and ceramic brackets.
4) To calculate the Adhesive Remnant Index scores for all four groups in this study.
Page 5 REVIEW OF LITERATURE
Chun-Hsi Chung, Blair W. Fadem, Harvey L.Levitt, Francis K. Mante13(2000) did a study to evaluate the effects of 2 adhesion boosters, Enhance LC and All-Bond 2, on the shear bond strength of previously debonded/sandblasted brackets and of new brackets. In this study 60 new brackets were divided into three groups and 60 sandblasted brackets were divided into three groups. Group 1:Without use of booster (no booster); Group 2:Rebonded brackets/no adhesion booster; Group 3:New bracket/ Enhance LC; Group 4:Rebonded brackets/Enhance LC; Group 5:New bracket/All-Bond2; Group 6:Rebonded brackets/All- Bond 2.The bond strength test was done using an universal testing machine and the results showed that no difference was found among the 3 groups using new brackets and without use of adhesion booster, sandblasted rebonded brackets yield significantly less bond strength than new brackets and All-Bond 2 significantly increased bond strength where as Enhance LC failed to increase bond strength when using sandblasted rebonded brackets.
Travis Q.Talbot, et al60(2000) evaluated the effect of argon laser irradiation on shear bond strength of orthodontic brackets and also investigated for their ability to confer demineralization resistance on enamel. Three different laser energies (200,230,300mW) were used in this study at 3 unique time points (before ,during or after bracket placement). One hundred and fifty human posterior teeth were randomly assigned to 10 groups of 15 each-9 experimental groups and 1control group. The results showed that the mean bond strength was significantly different between all 3 bracket placement groups and also the mean bond strength of teeth lased after bonding was significantly higher than the control group.
Page 6 Larry J.Oesterle, et al33(2001) did a study to test the efficiency of a xenon plasma arc light versus a conventional tungsten-quartz halogen light in producing the bond strength for orthodontic brackets. The adhesive used in this study were 3 light polymerized composite resins such as TransbondAPC, the fluoride releasing light bond and another composite which was developed for use with the xenon plasma arc light and the curing light used in this study were the [Apollo 95E] xenon plasma arc light and the [Optilux 401] light a conventional tungsten-quartz halogen light. The result of this study showed that the xenon light produced equivalent bond strength at 3,6,9 seconds compared to tungsten-quartz halogen light of 40 seconds. However the bond strength of xenon plasma arc curing light with long exposure showed higher values.
Maria Francesca Sfondrini, et al34(2001) evaluated the shear bond strengths of a composite resin and a resin modified glass ionomer cured using a conventional visible light unit and a xenon arc light unit . One hundred and twenty freshly extracted bovine permanent mandibular incisors were randomly divided into 1 of 8 groups; each group consisted of 15 specimens.
Two orthodontic light cured adhesive systems were evaluated. TransbondXT( a conventional composite resin) and a Fujiortho LC(GC America) - a resin modified glass ionomer adhesive.
After testing in an universal testing machine the results showed that the bond strength of composite resin was significantly higher than Fuji GC but no statistically significant differences were found between the control group and those cured with visible light and similarly no statistically significant differences were found between the control group and those bonded with the xenon plasma arc curing system.
Ross S. Hobson, et al53(2001) evaluated the bond strength of moisture insensitive primer under dry, moist and blood contamination conditions. In this study ninety human premolars were bonded in 3 equal groups and then shear bond strength was recorded using an Instron
Page 7 testing machine . The results of the study showed that higher bond strength for dry bonding than moist bonding. Low bond strength for blood contaminated group but all the 3 groups had required clinical bond strength, so Transbond MIP can be used for bonding on moist or blood contaminated conditions.
Arndt Klocke, et al3(2002) compared the plasma arc curing lights with the halogen light by an invitro investigation to evaluate the bond strength with two commercially available plasma arc lights with curing time of 2 seconds and 6 seconds. 150 extracted human teeth of 75 premolars and 75 incisors were bonded with a composite adhesive. Five groups of 30 teeth each involving 15 premolars and 15 incisors were formed. The bond strength testing was performed in an universal testing machine . The results showed that a substantial reduction in curing time was possible with plasma arc curing light but in case of premolar brackets, the lowest bond strength values were found for plasma arc curing light with curing time of 2 seconds than those cured for 6 seconds whereas for incisor brackets 2 seconds of curing time might be adequate to achieve an acceptable bond strength.
Larry James Evans, et al32(2002) did a study to evaluate the effects of different curing times , light sources and light guides on shear bond strength of orthodontic brackets bonded with Transbond XT (3M Unitek,Monrovia,Calif) to bovine enamel. 240 bovine mandibular incisors were randomly divided into 16 groups. The shear bond test was done using an universal testing machine. The bond strength values were high in 24 hour groups compared with the 5- minute shearing groups but statistically there were no differences. They concluded that the power slot and turbo tip light guides with their collimation of visible light to increase its intensity can be advantageous for curing resins.
Arndt Klocke, et al4(2003) had done an investigation to evaluate the bond strength when using a plasma arc curing light to bond polycrystalline and monocrystalline ceramic brackets.
Page 8 240 extracted bovine mandibular incisors are bonded with composite adhesive and curing intervals of 1, 3,& 6 seconds were choosen and the control group was cured at 10 seconds per bracket. The results of the shear bond strength after testing in an universal testing machine showed higher values for monocrystalline brackets than the polycrystalline in both 1 second and 3 second curing interval methods. The study concluded that a curing interval of 3 seconds with plasma arc curing light is advantageous over 1 second curing interval time.
Rognvald A. Linklater, et al52(2003) did an invivo study to identify the presence and pattern of differences in bond failure between two types when bonding brackets with the no-mix chemically cured orthodontic composite adhesive Right-on. Bond failure of brackets were recorded for 108 patients undergoing fixed orthodontic treatment with total of 1531 attachments (0.018inch brackets=549, 0.022inch brackets =914, tipedge=45, bonded molar tubes=16, buccal buttons =7). The failure rates and the survival rates of the attachments were noted and the results of this study confirmed that invivo bond survival is not uniform for all teeth and varies significantly between tooth types, attachment and dental arches, both in overall failure rates and patterns of bond failure. Posterior teeth had poor survival than anterior teeth and the mandibular teeth had poor bond survival than maxillary teeth.
Bruno Manzo , Giuseppe Liistro, Hugo De Clerck.11(2004) did a clinical trial to evaluate the time saved with a plasma arc curing unit over a conventional curing unit for direct bonding of brackets with resin adhesive. 608 brackets were bonded on a contralateral quadrant pattern in fourty five patients. The survival analysis rate of brackets were also carried out to compare the bracket failure rate over a period of 11± 3.2 months. The curing time for each technique is recorded. The results of the study showed that there was no significant differences in survival time between the 2 bonding methods but the plasma arc
Page 9 curing light can save chair time as the curing time per bracket was significantly reduced with this curing when compared to conventional halogen curing unit.(65±19 vs 82±31seconds).
Ingrid Hosein, Martyn Sherriff, Anthony J.Ireland21(2004) did an investigation to compare the enamel loss at each stage of the bonding and debonding and clean-up with the use of a self etching primer. The 4 enamel clean-up methods used were 1)use of high speed tungsten carbide bur, 2)a slow speed tungsten carbide bur, 3)debanding pliers and 4)an ultrasonic scaler. In this study a planer surfometer was used to measure the enamel surface height. The enamel loss after conventional acid etching was -2.76µm where as with self etching primer, the enamel loss was significantly lower -0.27µm.In both the conventional and self etch groups the most enamel loss occurred after the use of ultrasonic scaler or high speed tungsten carbide bur and least with the slow speed tungsten carbide bur or the debanding pliers and there was also significant difference found in ARI scores of the two groups.
Maria Francesca Sfondrini, et al35(2004 ) did a randomized clinical trial to evaluate the clinical performance of brackets cured with conventional halogen light and plasma arc light.
It was a split mouth study design involving 83 patients with fixed appliance. In 42 patients ,the maxillary left and mandibular right quadrants were cured where as in the rest , maxillary right and mandibular left quadrants were cured with the plasma arc light. Curing time for conventional halogen light is 20 seconds for each bracket (totally 717 brackets) and the curing time with plasma arc light is 5 seconds for each bracket (totally 717 brackets). Both groups of patients were monitored for 12 months. The datas such as number, cause and date of bracket failure were recorded for each light curing unit. The results of the study showed that no statistically significant differences were found between the total bond failure rate between two curing lights and also there is no significant difference in clinical performance
Page 10 of the maxillary versus mandibular arches. They concluded that the advantage of plasma arc light over conventional light curing is that plasma arc light reduces the total curing time.
Timothy Swanson, et al64(2004) in an invitro study evaluated the relationship between the shear bond strength of orthodontic brackets bonded to enamel and the photopolymerization duration with three LED curing units (GC e-light,UltraLume LED-2,Ellipar FreeLight) and one halogen based light curing unit.(Ortholux). 240 extracted molars were collected and the brackets were bonded and the specimens were divided into 12 groups of 20 teeth. For each curing light, the curing time of 40,20 and 10 seconds were used . The results the shear bond strength after testing in an universal testing Machine showed higher bond strength for UltraLume LED-2 at 40 seconds and weaker bond strength with GC e-light at 10 and 40 seconds , but the bond strength for all groups were greater than 8 MPa even with a 10 second curing time.
Vittorio Cacciafesta, et al68(2004) conducted a randomized clinical trial to evaluate the performance of adhesive-precoated brackets cured with a conventional halogen light and plasma arc light. They did a split mouth study design in which maxillary left and mandibular right quadrants were cured with halogen lights and the maxillary right & mandibular left quadrants were cured with plasma arc light for 15 patients and for other 15 patients the quadrants were inverted. The study was carried out for 12 months and the number, cause, date of bracket failure were recorded. The results of the study showed that there is no statistically significant difference between 2 groups in the bond failure rate or in the performance of 2 curing lights but the advantage of using plasma arc is that it can enable the clinician to reduce the curing time.
Page 11 Cornelia Speer, et al14(2005) did an invitro study to compare whether disinfecting with cholorherxamed fluid had an influence on shear bond strength of metal and ceramic orthodontic brackets. Composite adhesives Transbond XT(light curing) and chemical curing composite adhesive 224 bovine permanent mandibular incisors and divided into eight groups of 28 each. Results showed that disinfection of metal brackets had no significant change on shear bond strength where as disinfecting ceramic brackets showed significant reduction in shear bond strength but the bond strength values were higher than 6-8 mpa, so the disinfection of the ceramic brackets is a suitable procedure for clinical use.
Fabio Lourenco Romano, et al17(2005) did a study to determine the shear bond strength of metallic orthodontic brackets bonded to enamel prepared with Transbond plus self etching primer(TPSEP). Forty human premolars were divided into four equal groups of 10 each.
Group 1 is the control group were Transbond XT was used and in group 2 TPSEP was used with Transbond XT and in group 3 TPSEP was used with Z-100 and in Group 4 TPSEP was applied and the brackets were bonded with Concise orthodontic product. Here 1 to 3 groups were light cured whereas Concise orthodontic composite is cured by chemical activation. The brackets were debonded using a universal testing machine and the results showed that there was no significant difference between first 3 groups and also superior to group 4. The ARI evaluation showed that the conventionally bonded Transbond XT showed better adhesive results than using TPSEP groups(2,3,4)
HakanTurkkahraman, H.Cenker Kucukesmen 20(2005) compared the shear bond strength of orthodontic metal brackets by two high power light emitting diode modes and halogen light. Here forty five SS orthodontic bicuspid brackets were divided into three groups of fifteen each. In first group mini LED(Satelec,Merignac,France) fast mode LED for 20 seconds and second group helioux DLX(Vivadent ETS,Schoan,Leichtenstein) soft start mode LED for 40 seconds, third group halogen light for 40 seconds were used. The shear bond
Page 12 strength of fast mode LED is similar to halogen based illumination, where as soft start mode LED yielded higher shear bond strength than the other two groups.
M Dolores Campoy, et al38(2005) did an invitro study to evaluate the effect of saliva contamination on the shear bond strength at different stages of the bonding brackets using Adper Prompt L-Pop (self etching primer) and Transbond XT (resin orthodontic adhesive system). Seventy premolars were bonded with brackets and were divided into four groups:
group 1,uncontaminated control; group 2, saliva application before priming; group 3, saliva application after priming and group 4, saliva application before and after priming. Shear bond strength was measured with a universal testing machine. The results showed that there was significant differences observed between group 1 and group 2 and group 4. The shear bond strength of brackets contaminated before priming showed significant difference than the control group.
Neslihan Eminkahyagil, et al42(2005) did an invitro study comparing the shear bond strength of a self etch primer adhesive and an antibacterial self etch primer adhesive for orthodontic metal brackets. They assigned twenty four premolars into two equal groups. In group 1- Transbond plus self etching primer was used and in group 2- antibacterial dentin bonding system was used. The results showed that the difference between the groups was not statistically significant. ARI score showed that the predominant mode of bracket failure for both groups was the bracket adhesive interface leaving less than 25% of the adhesive on the bracket base.
Raed Ajlouni, et al 48(2005) compared the use of new self etching primer/adhesive effects on shear bond strength of orthodontic metal brackets bonded to surface. Forty five maxillary central incisor teeth were divided in to 3 group - group 1(control), here porcelain teeth were bonded using 37% phosphoric acid, a sealant and composite adhesive. In group 2,
Page 13 microleaching of porcelain teeth, use of hydrofluoric acid and silane coupling agent and composite agent and composite adhesive was used. In group III , the porcelain teeth were etched using phosphoric acid and a new self etching primer / adhesive was applied before bonding. The results showed low shear bond strength in group I and II, group III showed no significant difference in shear bond strength. SEM study showed micro etching , use of hydrofluoric acid produced greatest damage to porcelain surface when compared with the new self etch / silane /adhesive combination.
Samir E.Bishara, et al 54(2005) studied the effects of changing the cross head speed of the testing machine on the shear bond strength of orthodontic metal brackets to enamel. They standardized all the other variables. In this study 40 extracted human molars were bonded using Transbond XT adhesive system and then divided into 2 groups. The test parameter such as the cross head speed is 5mm/minute for the group 1 and 0.5mm/minute for group II. The results showed significant difference in shear bond strength between two groups. The group II showed higher shear bond strength (Mean = 12.2±4Mpa) higher compared to group I with mean = 7.0±4.6Mpa respectively.
Y.Teresa Silta, et al72(2005) did an invitro study to evaluate the effect of shorter polymerization times when using the latest generation of light emitting diodes. Here two LED light curing units (Ortholux LED ,Ultralume LED 5) and a quartz tungsten halogen light cure unit (optilux) were used to bond orthodontic brackets for curing time of 20 seconds,10 seconds or 6 seconds .The results of the study showed significant differences in bond strength when compared to different light types and curing time. The 6 seconds cured brackets showed lower bond strength than the 20 second cured brackets and bond strength of brackets cured for 20 seconds with optilux 501 QTH LCU and the ultralume LED 5 LCU were significiantly high compared to 6 seconds cured brackets. Thus they recommend (at least ) 20 seconds of curing time with QTH or LED cutting lights.
Page 14 Zafer C. Cehreli, et al73(2005 ) did an invitro study to compare the shear bond strength of 4 self etching primer and adhesive formulations. The self etching products tested were PromptL-Pop, Clearfil SE Bond ,FL bond and one-up bond F. The conventional acid etch and bond system was Transbond XT and also they used the non-rinse conditioner and acetone based adhesive system(NRC and Prime and Bond NT). The brackets were bonded to 42 bovine mandibular incisors with 7 teeth each for 6 groups. The results of shear bond test after testing in an universal testing machine showed significantly lower value than the control group so they concluded that these products might not be suitable for orthodontic bracket bonding in terms of shear bond strength.
Ascension Vicente, et al5(2006) in an invitro study evaluated the effects of three adhesion promoters on the shear bond strength of orthodontic brackets. The promoters used in this study were Ortho sol, All bond-2, Enhance LC and two adhesives were used-Transbond XT and light bond. A total of 150 premolars were divided into 25 each of 6 groups. (1)Transbond XT, (2)Transbond XT Plus All bond 2, (3) Transbond XT plus Ortho solo, (4)Transbond XT Plus Enhance LC, (5)Light bond, (6)Light bond plus Enhance LC. The test was done in an universal testing machine and the results showed highest bond strength for light bond plus Enhance LC and none of the adhesion promoters significantly increased the bond strength.
Juliana Godoy-Bezerra, et al25(2006 ) did an invitro study to evaluate the three different enamel pretreatment on shear bond strength of resin modified glass ionomer cement after different enamel pretreatments in saliva contaminated environment. 125 bovine incisors were divided into three groups. Group I – received 10% polyacrylic acid moistened with saliva / Fuji Ortho LC (FOLC), Group II - received 37% phosphoric acid, moistened with saliva / FOLC, Group III was moistened with saliva / FOLC without acid etching, Group IV -10%
Page 15 polyacrylic acid, not moistened with saliva FOLC and Group V was used as control with 37%phosphoric acid / dry / TransbondXT. The results showed highest bond strength for group V and similar bond strength noted for group II. There were no statistically significant difference between groups I,III,IV. They concluded that the saliva moistened FOLC GIC showed no statistically significant difference from Transbond XT group.
Julio Pedra e Cal - Neto, et al 26(2006) evaluated the influence of a new self etching primer on bracket shear bond strength . Forty extracted human premolar were divided into two groups of 20 each . Group 1 ( control ), Phosphoric acid + Transbond XT primer and adhesive ( 3MUnitek) and group 2, Adper Prompt L Pop - self etching primer, Transbond XT adhesive paste was used and cured with Ortholux XT( 3M Unitek) visible light curing unit .Instron universal testing machine was used to calculate the shear bond test.The results showed no significant difference in the bond strengths of two groups evaluated . The ARI was less for the new self etching primer as the amount of adhesive on the enamel after debonding was significantly less than when using the phosphoric acid.
Maria Francesca Sfondrini, et al36
(
2006) did a study to assess the effect of light tip distance on the shear bond strength of resin modified glass ionomer cured with three curing units (high intensity halogen, LED and plasma arc). The shear bond strength test was done in an universal testing machine and the results of the study showed that when the light tip distance is 0 mm, there is no significant difference among three groups. At a light tip distance of 3mm, the bond strength of halogen and plasma arc curing is similar and it is higher than the LED curing light and at a light tip distance of 6mm, the bond strength of LED and halogen is similar but lesser than the plasma arc curing light. Thus the plasma arc curing light produced higher bond strength than other two light curing system. The ARI score is similar for all groups except with the LED light at a distance of 3mm.Page 16 Michael D.Signorelli, et al 39(2006) did an invitro shear bond strength test and also an invivo survival rate of orthodontic brackets bonded with either a halogen or a plasma arc light . 90 stainless steal brackets were bonded to the premolar teeth using a halogen light with 20 second curing time or a plasma arc light with 2,6 or 10 second curing time. Brackets were tested within 30 minutes or after thermocycling for 24 hours. For invitro study ,they did a spilt arch design to determine the brackets failure rate in 25 palients for a period of 1.1 years (386 days). The results of the study showed no statistically significant differences in bond strength and also the invivo study also showed no significant difference in bracket failure Ascension Vincente, Luis Alberto Bravo6(2007) did a study to compare the shear bond strength or the adhesive remaining on the tooth after debonding between APC plus precoated and uncoated brackets using a self-etching primer. Forty premolars were divided into twenty five for uncoated brackets and fifteen for precoated (APC Plus) brackets. The brackets are bonded using TPSEP(self etching primer)/Transbond XT adhesive resin and light cured. The results of the study showed that there is no significant difference in the shear bond strength and also in the percentage of area of adhesive remaining on the tooth between two bracket groups.
Hakan Bulut, et al19(2007) in an invitro study investigated the shear/peel bond strength of metal brackets bonded with three curing systems; No mix bonding adhesive(Unitek,3M Unitek), 2-paste chemically cured bonding resin(Concise,3M Unitek), light cured adhesive (Transbond XT). Each bonding group was separated into experimental (n=20) and control groups (n=20). The control group was bonded only with their relevant bonding system where as in the experimental group, an anti bacterial self etch adhesive was applied to the enamel.
The results of this study after testing in an universal testing machine showed groups 1 and 2 showed significant difference in bond strength than their control group where as group 3 did not differ from the control group and all the results showed clinically significant bond
Page 17 strength so they concluded that the newly developed antibacterial self etch adhesives can be combined with various bonding systems.
Kayo Saito, et al27(2007) did an invitro study to assess the antibacterial efficacy of 4- methacryloxyethyl Trimellitateanhydride /Methyl methacrylate –tri-n-butyl borane resin containing benzalkonium chloride and the shear bond strength of orthodontic brackets bonded using this material. The antibacterial activity of the BAC composite was measured by the disk diffusion method using streptococcus mutans and streptococcus sobrinus agar plates.
The shear bond test was done using anuniversal testing machine and the results showed that the bond strength declined with increase in BAC concentration and BAC composites showed significant antibacterial activity and the bond strength of BAC composite groups also had clinically significant bond strengths so they can be used as an orthodontic bonding adhesives.
Nikolaos Pandis, Sophia Strigou, Theodore Eliades43( 2007) made a clinical assessment with split mouth study to assess the long term failure rate of brackets bonded with a plasma curing light or a high intensity (LED) curing light. Twenty five patients were bonded with brackets according to a split mouth design with the 3M ortholite plasma or the high power satelec mini LED curing light. Bracket failures were recorded and the results were analysed with variables as light source (plasma or LED), arch(maxillary or mandibular), side(left or right), and region(anterior or posterior) separately or simultaneously. The results showed that the failure rates for plasma is less compared to the LED light source. The failure were found more for the mandibular arch(150% higher incidence) than maxillary arch. The arch side (right vs left) and location (anterior vs posterior) had no effect.
Page 18 Nirshpack, et al44(2007) did a study to examine the ultimate accuracy of bracket placement in labial Vs lingual systems and also in direct Vs indirect bonding techniques. 40 casts of 20 orthodontic subjects were selected and the subject were divided into four groups according to the appliance bonding(labial / lingual) and technique of bonding (direct/indirect). For labial system-Orthos brackets(Orcmo)were placed and (0.022x0.028 inch slot ) for lingual system (lingual generation 7 brackets (Orcmo)(0.018x0.025 inch anteriors) and 0.022x0028 inch slot premolars were placed.Tranbond XT was used for both direct and indirect bonding. labial brackets were oriented with a Boone gauge and the lingual brackets were oriented with the lingual-bracket jig system.Torque error (TqE) and rotation deviation were measured with a torque geometric triangle and a toolmaker’s microscope.The results of the study showed that the absolute TqE and Rot D values were significantly higher in direct that in indirect bonding technique. No statistically significant differences were found between labial and lingual system for the same bonding technniques.
Nuray Attar, et al45(2007) did a study to assess and compare the effects of one and step self etching primer and adhesive with conventional adhesive system(such as use of an enamel conditioner, a primer and an adhesive resin to bond brackets) on the shear bond strength brackets of orthodontic brackets.Forty two human premolars were randomly divided into three groups including seven maxillary and seven mandibular premolars in each group.For group 1(control group) - 40% phosphoric acid (k-etch) used as etchant and Kurasper F bond was applied and light cured for 10 seconds .For group 2: clearfil protect bond ,a two step self etchintg primer and adhesive was used and light cured.For group 3,clearfil tri- S bond ; a one step self – etching primer and adhesive system was applied on the enamel for 20 seconds and light cured for 10 seconds. Stainless Steel premolar brackets were used in all the groups and light curing was performed with LED LCU (Elipar free light ,3MESPE,St Paul ,MN,USA).The results of the study after testing in an universal testing machine showed no
Page 19 statistically significant differences among three groups.TheARI scores showed that failure was at the bracket adhesive interface with score of 1.
Rodney G.Northrup, et al51(2007) compared the shear bond strength of two adhesives (TransbondXT, Blugloo) and self-ligating and conventional brackets. Sixty extracted premolars were divided into three groups of 20 teeth. In group 1 light cure conventional bonding with Transbond XT primer & adhesive with conventional SS brackets were done, In group 2 bonding with light cure self ligating brackets with Transbond XT primer & adhesives were done, In group 3 they used light cured adhesive (Blugloo) and light cured primer (orthosolo) to bond self ligating brackets. Results of shear bond test in an universal testing machine showed lower shear bond strength for conventional brackets compared to the self ligating brackets and ARI score for all groups were not stastistically different.
Samir E.Bishara, et al55(2007) did a study to compare the shear bond strength of brackets when self etching primer A, different brands and the brackets adhesive are light cured either separately or simultaneously. Seventy five human molars are divided into five groups. The five protocols were: group 1(control), the SEP Transbond plus was applied and light cured;
group 2, SEP Adper prompt L-pop was applied, light cured, brackets placed and light cured.
In group 3, SEP Adper prompt L-pop was applied, after placing the bracket with adhesive it was light cured simultaneously. In group 4, SEP Clearfil S3 bond was applied and after placing the bracket with adhesive it was light cured simultaneously. The results showed when compared to control(group 1), the bond strength were higher for S3 bond(2 light exposure) and S3 bond(1 light exposure), where as the Adper Prompt L-pop group(1 light exposure) does not differ significantly than other two groups.
Page 20 Toshiya Endo, et al63(2007) evaluated the bond strength of identical orthodontic brackets bonded to maxillary deciduous and permanent teeth and also their modes of brackets /adhesive failure. Metal premolar brackets were bonded to teeth in each group by acid etch adhesive system and the shear bond strength test was performed using an universal testing machine and the results showed low bond strength for deciduous teeth compared to the permanent teeth but the bond strength of all 4 groups were higher than the clinically significant range of 6 to 8 Mpa . ARI scores showed that bond failure at enamel –adhesive interface occurred more frequently in the deciduous second molars compared to the permanent 1st premolars and they concluded that the deciduous teeth could also be used as anchor teeth in sectional mechanics.
Virna Cavalcante Patusco, et al67(2007) tested the bond strength of metallic brackets after at-home and in-office vital bleaching. Forty five human premolars were divided into three groups of 15 each. First group served as control , second group is bleached with 10%carbamide peroxide, third group is bleached with 35% hydrogen peroxide. The results of shear bond strength showed no satisfactory difference between group 1&2 where as group 3 had lower mean shear bond strength than group 1 &group2. This shows that in-office bleaching significantly reduces bond strength and also the amount of resin remnant on the tooth surface after the debonding procedure. rates between the two light sources.
Y.Sinasi Sarac, et al71(2007) investigated an invitro study to evaluate the effects of three surface conditioning methods on shear bond strength(SBS) of a feldspathic ceramic and also investigated its surface roughness and compared the efficiency of three polishing techniques.
Three specimens were divided into three groups as air particle abrasion(APA) with 25-µm aluminium trioxide(AL2O3)(Group A); hydrofluoric acid(HFA)(Group H); APA and HFA(Group AH) .The surface conditioning methods employed are adjustments kit, diamond polishing paste, adjustment kit +diamond polishing paste and 63 specimens were divided into
Page 21 three groups. The results of this study showed that lowest shear bond strength for group H(Hydrofluoric acid group) compared to group A and AH and also the Ra value was lowest for group H .The surface conditioning methods are equally effective to smooth the porcelain.
Asli Baysal, Tancan Uysal, Mustafa Ulker, Serdar Usumez 8(2008) did a study to evaluate the effects of high intensity light curing units (LED) and plasma arc curing on the microleakage of flexible spiral wire retainers at the composite / enamel and composite / wire interfaces. Three groups of 15 human mandibular incisors were bonded with multistranded PentaOne wire of 0.0215 inch diameter and cured with three different light source. Group 1(Control ) – QTH for 10 seconds and group 2 : LED for 5 seconds and group 3 : PAC for 3 seconds were used .The samples were sealed with nail varnish, stained with 0.5 % basic fuschine and sectioned. Under a stereomicroscope the transverse sections were evaluated and scored for microleakage for the composite / enamel and composite / wire interfaces. The results of the study showed at composite /enamel interface there were little or no microleakage where as at composite /wire interface the microleacage was less in QTH group than other two with statistically significant difference and there was no significant difference between LED and PAC groups.
Jeff A. Foster, David W.Berzins, Thomas G.Bradley 23(2008) did a study to evaluate whether an amorphous calcium phosphate (ACP)-containing adhesive has an acceptablelevel of shear bond strength when used as an orthodontic adhesive. In this study 60 brackets were bonded to premolars which where randomly divided into three groups; Group 1: Transbond XT-composite resin adhesive; Group 2: Aegisortho-ACP containing adhesive;Group 3: Fuji ortho LC- Resin modified glass ionomer. After etching with 35%phosphoric acid for 15 seconds, Transbond XT light cured primer was applied to the teeth and then followed by corresponding adhesive application in each group. An instron testing machine was used to debond the brackets and the results of the study showed that the mean shear bond strength is
Page 22 greater for group 1(15.2±3.6 Mpa) than group 2(6.6±1.5 Mpa) and group 3(8.3±2.8 Mpa).
Group 1&3 exhibited lower ARI score than group 2 and they concluded that the ACP- containing adhesive demonstrated a low but satisfactory bond strength needed to function as an orthodontic adhesive.
Phillip D. Lowder, Tim Foley and David W.Banting46(2008 ) did a study to investigate the shear / peel bond strength (SPBS) of orthodontic brackets bonded with 1 of 4 orthodontic adhesives (TransbondXT ,Blugloo,Light bond and APC plus applied over a filled resin sealant(Proseal). 240 extracted premolars were collected and the teeth were randomly assigned to 1 of 6 groups (40 teeth per group). There were 4 adhesive - sealant groups and 2 groups with adhesive (TransbondXT,Blugloo)only. The adhesive sealant groups were Transbond XT/Proseal ,Light bond/Proseal, APC plus/Proseal, and Blugloo/Proseal. After the brackets were cured, the shear bond test was done using a calibrated universal testing machine (model 3345-Instron) and the results showed that three adhesive sealant combination groups had lower shear bond strength than the 2 reference groups but the lightbond/Proseal group had a higher mean SPBS compared with 2 reference groups.
Samir E.Bishara, et al56(2008) did an invitro study to test the difference in brackets failure characterstics when using a new ceramic debonding instrument when compared with the use of conventional pliers.Ceramic maxillary premolar brackets (APC plus,clarityseries : 3M Unitek) were used .The enamel surface was studied under transillumination with a fiber optic light head and evaluatedfor enamel cracks.Teeth were bonded with Transbond SEP and precoated brackets was placed and light cured with use of a halogen light.Teeth were divided into two groups of 15 teeth each and in group 1 - utility pliers (3M Unitek) were used and in group 2- new debonding instrument (3M unitek) were used. Once the brackets were debonded the enamel surface of each tooth wasexamined under 10X magnification in an stereomicroscope and the modified ARI score was used to evaluate the adhesive remained on
Page 23 the tooth. Results of the study showed statistically significant difference in bond failure patterns between two groups and the brackets debonded with a new instrument showed more adhesive to be removed from the tooth during debonding.
Selma Elekdag-Turk et al58 (2008) did a study to evaluate the effects of thermocycling on the shear bond strength values of an self etching primer after 0,2000 and 5000 thermal cycles.
The results of the study showed that in the control group the shear bond strength does not vary with thermocycling, whereas in the thermocycling group SBS decreased with 2000 and 5000 cycles. The ARI scores also varied when compared to control group with 5000 cycles and SEP group with no thermocycling and with 5000 thermal cycles. Within the SEP group also ARI scores varied with nothermocycling and with 5000 thermal cycles group. With this results of the study they concluded that the bond strength values of SEP group is less than the control but SEP provides clinically acceptable bond strength.
Matheus Melo Pithon,et al37(2009) did a study to evaluate the effect of increasing storage time after activation on the influence of shear bond strength of brackets bonded to enamel with a self etching primer.210 brackets were divided into seven groups of 30 each. The self etching primer were mixed, activated and stored inside a refrigerator at 8 degree celcius.
TPSEPs were kept activated for 30(group 30),21(group 21),15(group 15),7(group 7),3(group 3)or 1(group 1)days before bonding and in one group(group 0) was used immediately after mixing, activated TPSEP was applied and brackets were bonded with Transbond XT and light cured. The result of the study showed no significant difference in bond strength +ARI score among 0 to 15 and among groups 21 to 30.They concluded that storing activated TPSEP upto 15 days did not produce significant change on the shear bond strength.
Virna Cavalcante Patusco et al67 (2009) tested the bond strength of metallic brackets after at-home and in-office vital bleaching. Forty five human premolars were divided into three
Page 24 groups of 15 each. First group served as control, second group is bleached with 10%carbamide peroxide, third group is bleached with 35% hydrogen peroxide. The results of shear bond strength showed no satisfactory difference between group 1&2 where as group 3 had lower mean shear bond strength than group 1 & group 2. This shows that in-office bleaching significantly reduces bond strength and also the amount of resin remnant on the tooth surface after the debonding procedure.
Theorde Eliades61(2010) reviewed the fundamentals of photocuring with various type of lamps in orthodontics. The key properties such as polymerization efficiency(degree of cure), mechanical properties(bond strength), clinical performance(failure rate) and biological properties of blue light are reviewed to know their clinical usefulness in application to orthodontic bonding. The light intensity , their penetration into the adhesive,(the composition of the adhesives , their resin, fillers, initiators, inhibitors)are factors that can vary the polymerization efficiency. For any light cure lamp its light intensity, wavelength and the curing time are the important factors to be considered before its selection for the orthodontic purpose. For evaluating the bond strength factors such as the bracket design, variation in load application, loading rate, teeth storage and preparation, testing conditions can significantly alter the results in addition to type of curing system used.
Adrian.C.Shortall, Will M Palin , Bruno Jacquot and Bruno Pelissier2(2012) described the history of light curing in dentistry and about the four generations of LED and about selection criteria for the clinician considering purchasing a new LED. The features of third generation LED such as reduced power consumption , their ergonomic design features , either battery powered or corded and broad spectral output with universal curing of photo activated dental resins irrespective of initiator formulation shorter irradiance time made them popular than the second generation blue LED. Now the LED is towards its fourth generation
Page 25 incorporating the features of third generation and also it has features of four different diode wavelength selection for curing adhesives with minimized over heating issues and the polymerization stresses are reduced due to its soft scan options.
Adrian.C.Shortall, R.B.Price, L.Mackenzie, F.J.T.Burke1(2016) discussed the development of LCUs in dentistry and also about the selection, use and maintanence of LED light-curing units. Early LED required longer exposure time because of their low energy output. In order to increase their output they started fitting multiple LED emitters in gun style or pen style models. The second generation LED units were smaller as they had powerful blue LED chips. The newly introduced third generation polywave LED simulated the broader emission spectrum of QTH and PAC units for activating materials containing alternative photoinitiators which had 4 LED emitters each producing different wavelengths of light. Manufacturers of polywave LED curing light are Ivoclar Vivadent, GC, Heraeus Kalzer, Ultradent and their resins are benefited from polywave LED curing light as these composite manufacturers market materials that use alternative photoinitiator other than camphoroquinone.
Page 26 MATERIALS AND METHODS
MATERIALS
BRACKETS : [ Figure 1 ]
Metal brackets : Unitek Gemini metal brackets Forty stainless steel brackets [First and second maxillary premolars of both sides] - 0.022 x 0.028 inch slots with MBT prescription, with -7 degree torque and 0 degree angulation - REF 119 -142 ( 3M Unitek Corp )
Ceramic Brackets : Unitek Gemini clear ceramic brackets. Forty polycrystalline ceramic brackets [First and second maxillary premolars of both sides] - 0.022 x 0.028 inch slots with MBT prescription with -7 degree torque and 0 degree angulation - REF 117 -100 (3M Unitek Corp )
The average bracket base area was 9.806 mm2 for metal brackets and 11.74 mm2 for ceramic brackets as given by the the manufacturer and it is also verified by an image analysis software (CMEIAS Ver .1.28 operating in UTHSCSA image tool Ver.1.28).
LIGHT EMITTING DIODE CURING LIGHTS : LED – LCUs [ Figure 2 ]
Monowave LED curing light - Bluephase C5 ( Ivoclar Vivadent ) with light intensity of 500 mW/ cm2 and wavelength of 430-490 nm , corded operation , 10 mm black light probe.
Curing time recommended by the manufacturers is 20 seconds.
Poly wave LED curing light - Bluephase Style ( Ivoclar Vivadent ) with light intensity of 1,100 mW / cm2 and wavelength of 385 -515 nm, lithium - polymer battery , 10 mm black light probe. Curing time recommended by the manufacturers is 10 seconds even for 4mm bulk fill.
Page 27 Bonding Materials used [Figure 2 ]
Etchant - 34 % Phosphoric acid solution( Scotchbond – 3M ESPE ) Primer -Transbond XT –3 M Unitek
Composite Adhesive - Transbond XT – 3 M Unitek
TEETH SAMPLES
80 extracted human maxillary and mandibular premolars extracted for therapeutic purpose as a part of fixed orthodontic treatment in the department of oral and maxillofacial surgery , KSR Institute of Dental Science and Research, Thiruchengode were used as the test samples.
Criteria for tooth selection :
1)Intact enamel with no developmental defects.
2)No pretreatment use of chemical agents.
3)No caries with normal tooth morphology.
4)No cracks due to the pressure of the extraction forceps.
Storage:
The samples were stored in distilled water at room temperature in an airtight humid environment to prevent dehydration and it is periodically changed until their use.
Mounting: [ Figure 3 ]
Teeth were cleansed of soft tissue and embedded in cold curing acrylic ( DPI )
Page 28 Pink Acrylic group – Poly Wave
Clear Acrylic group - Monowave
Each tooth was oriented such that its labial surface would be parallel to the force during the shear bond test.
Sample grouping
80 samples were divided into 4 groups such that there are twenty samples in each group.
The samples were grouped based on the type of bracket material ( metal brackets / ceramic brackets) and their LED curing light ( monowave LED / polywave LED ).
Table 1 – Classification of samples into four groups
Bracket material
Curing light Total number of
samples/group
Curing time / bracket
Group I
(Metal Monowave)
Metal MonoWave
LED
20 20 seconds
Group II
(Metal Polywave)
Metal Polywave LED 20 10 seconds
Group III
(CeramicMonowave)
Ceramic MonoWave
LED
20 20 seconds
Group IV
(Ceramic Polywave)
Ceramic Polywave LED 20 10 seconds
Page 29 METHODS
Method of bracket bonding for both metal and ceramic brackets for all 4 groups are as follows
Cleaning - Before the bonding , the facial surface of each premolar was cleansed with a mixture of water and fluoride free pumice with a rubber polishing cup for 10 seconds.
The enamel surface was thoroughly rinsed with water to remove any pumice or debris and dried with an oil free air stream .
Etching -The buccal enamel surfaces were etched with 34 % phosphoric acid solution ( Scotchbond – 3M ESPE ) for 30 seconds followed by thorough washing and drying.
Priming- A thin , uniform film of the primer ( Transbond XT – 3M unitek ) were applied to the etched surface of the tooth.
Light cure adhesive placement and bonding
The brackets with the adhesive were placed on the tooth near the center of the facial surface with sufficient pressure to express excess adhesive which was removed from the margins of the bracket base with a sickle scaler before polymerization.
Page 30 Curing Method (Figure 4)
Group I and III( Monowave LED ) : light – curing for 20 seconds / bracket, 10 seconds for the mesial side and 10 seconds for the distal side at a distance of 1mm away from the bracket.
Group II and IV(Polywave LED ) : light – curing for 10 seconds /bracket, 5 seconds for the mesial side and 5 seconds for the distal side at a distance of 1mm away from the bracket.
The intensity check was done with an intensity meter to confirm whether proper light intensity of light is emitted from the light source.
Immediately after bonding the samples were stored in distilled water at room temperature for 24 hours after which the testing was performed.
Shear bond testing procedure (Figure 5 )
The KALPAK universal testing machine- 121101( Kalpak Instruments and Controls , Pune India) was used to test the shear bond strength of each tooth. The acrylic block is mounted on a universal joint to ensure that the applied force was parallel to the tooth surface.The force was applied with a beveled flattend steel rod at the bracket-tooth interface at a crosshead speed of 0.5 mm per minute in a occlusogingival direction. The force values ( in Newton) recorded at the point of failure were converted to shear stress by dividing by the bracket surface area (mm2 ) and were reported in megapascals ( N/ mm2) for all 80 samples by the UTM software in computer connected to the testing machine.
Page 31 ARI scoring for all groups ( Figure 6)
After bracket failure , the enamel surface was examined under an optical stereomicroscope magnification x10) and the amount of adhesive remaining on the tooth was imaged.
Analysis of residual adhesive on the tooth surface was done according to Artun and Bergland – ARI score by visualizing in the microscope and the scores were made.
The criteria for scoring were as follows : 0 = No adhesive on the tooth
1= Less than half of the adhesive on the tooth 2= More than half of the adhesive on the tooth 3= All the adhesive on the tooth , with a distinct impression of the bracket mesh.
Page 32 FIGURE 2 - METAL AND CERAMIC BRACKETS USED IN THE STUDY
FIGURE 1 – METAL AND CERAMIC BRACKETS USED IN THE STUDY
Metal Brackets
Ceramic Brackets
Page 33 FIGURE 2 – CURING LIGHT AND THE LIGHT CURE BONDING MATERIALS
FIGURE 3 - CURING LIGHT AND THE LIGHT CURE BONDING MATERIALS
Monowave LED Bluephase C5 ( Ivoclar Vivadent )
Polywave LED Bluephase Style
( Ivoclar Vivadent ) Bonding materials Monowave LED
Bluephase C5 (Ivoclar Vivadent)
Polywave LED Bluephase style (Ivoclar Vivadent)
Bonding Materials Bonding Materials Bonding Materials FIGURE 3 - CURING LIGHT AND THE LIGHT CURE BONDING MATERIALS
Monowave LED Bluephase C5 ( Ivoclar Vivadent )
Polywave LED Bluephase Style
( Ivoclar Vivadent ) Bonding materials
Bonding Materials Bonding Materials
Page 34 FIGURE 3 – TEETH SAMPLES MOUNTED IN ACRYLIC BLOCKS
Total of 80 samples
4 groups of 20 samples Acrylic used for the blocks
Page 35 FIGURE: 4 - LIGHT CURING METHOD
FIGURE 4 - LIGHT CURING METHOD
Page 36 FIGURE 5 – UNIVERSAL TESTING MACHINE AND THE SHEAR TEST
FIGURE 5 - UNIVERSAL TESTING MACHINE AND THE SHEAR TEST
Page 37 FIGURE 6 – OPTICAL STEREOMICROSCOPE
FIGURE 7- STEREOMICROSCOPIC PICTURE OF TOOTH SURFACE TO DETERMINE ARI
Page 38 STATISTICAL ANALYSIS
The mean and standard deviation were estimated for the four groups of samples.
To find out the significant difference between the groups and the Student’s t-test were used.
The formula used to assess the student t-test was t = d / SE (d) Where
SE (d) = Standard error of d S / √n ∑n
S = i=1 (di-d)2 n - 1
∑n di
d = i = 1 n
Where di is the difference of the observation at two time points
The frequency of distribution of the ARI scores obtained for all four groups were determined using a Chi - square analysis and P value of less than 0.055 was considered to be statistically significant.
