EVALUATION OF THE MICRO SHEARBOND
STRENGTH BETWEEN A COMMERCIALLY AVAILABLE CERAMIC REPAIR COMPOSITE TO LITHIUM
DISILICATES USING DIFFERENT AIR ABRASIVE PARTICLE SIZES-AN IN VITRO STUDY
A Dissertation Submitted
to the Tamil Nadu Dr. M.G.R. Medical University In partial fulfillment of the requirement for the degree of
MASTER OF DENTAL SURGERY
(BRANCH I - PROSTHODONTICS)
APRIL 2017
CERTIFICATE
This is to certify that the dissertation titled “EVALUATION OF THE MICRO SHEARBOND STRENGTH BETWEEN A COMMERCIALLY AVAILABLE CERAMIC REPAIR
COMPOSITE TO LITHIUM DISILICATES USING DIFFERENT AIR ABRASIVE
PARTICLE SIZES-AN IN VITRO STUDY ” is a bonafide record of work carried out by Dr.
S. UTHAYANA RAAJA , during the period of 2014-2017. This dissertation is submitted in partial fulfillment, for the degree of Master of Dental Surgery awarded by TamilNadu Dr.
MGR Medical University, Chennai in the branch of Prosthodontics.
GUIDE PRINCIPAL
Dr. P.MANIMARAN, M.D.S., Dr. A.SIVAKUMAR,M.D.S
HEAD OF THE DEPARTMENT
FOREWARD
I am extremely thankful to Dr.P.MANIMARAN, MDS., Professor and Head of the Department, Department of Prosthodontics, J.K.K NATTRAJA Dental College and Hospital for his constant guidance, encouragement, and monitoring during this study. I also thank him for the valuable guidance he has given throughout my post graduation.
My sincere thanks to Dr.A.SIVAKUMAR, MDS.,Professor, Dept of Oral and maxillo facial surgery, Principal, J.K.K NATTRAJA Dental College and Hospital, for his kind help, and permitting me to use the facilities in the institution.
I consider it my utmost privilege to express my sincere and heartful gratitude to Dr.SAISADAN M.D.S., senior lecturer , Department of Prosthodontics, J.K.K NATTRAJA Dental College and Hospital for his able guidance and support rendered at various stages of the dissertation.
I am thankful to Dr. C. Dinesh Kumar M.D.S, reader and Dr. M.Abirami M.D.S lecturer, department of prosthodontics for helping me in this study . My sincere thanks goes to my juniors Dr.M.H. Hareesh , Dr. K.C.Gowthama raaj , Dr. S. Preethi suganya for their concern amd support .
I express my sincere thanks to Dr.B. PADHMANABAN, PhD., Professor, and the students of Dept. of Metrology, Kongu Institute of Technology, Perundurai for permitting me to use the various testing equipments available in the institution to conduct the test. I thank Dr.KUMARESAN , Principal, Al Ameen College, Erode for helping me to carry out statistical analysis of the various test results.
I am highly indebted to my family and friends who have helped me in several ways during the course of the study.
Above all I offer my sincere thanks to the SUPREME for making me to complete this study
INTRODUCTION
The quest for an artificial prosthesis similar to natural tooth, both in function and esthetics,in the oral environment still remains a foremost concern to the dentist , which has led to the use of ceramics in dentistry. The word ceramic is derived from the greek term
‘KERAMOS’ which means ‘EARTHEN’. Ceramics had been used from the medival period.
Down the ages ceramics have undergone tremendous transformations.
The evolution and formation of new ceramic systems was trending in late 20th century with advancements in processing methods and clinical techniques. The use of all ceramics as a restorative substitution for metal-ceramic has increased substantially, because of the cosmetic and esthetic demands that are faced by the dentists and the translucent properties of ceramics that can be affected by the metal core.
Ceramic systems are of different types like aluminous and magnesia, castable ceramics, pressable ceramics, glass infiltrated core porcelains and machinable ceramics. In that Glass infiltrated machinable systems like Lithium disilicate based ceramic systems occupy the major crystalline phase of the core material which are then layered with a glass containing dispersed apatite crystals.Eg: Empress-2. The advantage of all ceramic restorations include life like appearance that is aesthetics, biocompatibility, durability chemical stability, improved thermal and mechanical properties.
Fracture of veneering ceramics still remains the primary cause of failure of all ceramic crowns .Core- veneer interface is one of the weakest aspects of the layered all ceramic crowns, leading to ceramic chipping or cracking .
Fracture of ceramic restorations are due to impact and fatigue load, occlusal forces, incompatible thermal expansion, seating force or cementation and improper design that may lead to fracture at core-veneer interface. Replacing a fractured crown increases cost, discomfor,
time and labour. So chair side repairing procedures had been introduced to crop up all these difficulties.
A number of ceramic repair materials and techniques are available. Daily practice utilises the hybrid composite resins for the repair of lithium disilicates . Bond between the resin composite and lithium disilicates is usually acheived by two mechanisms.Micro-mechanical attachment is provided by air abrasion with aluminium oxide particles and hydrofluoric acid etching .Chemical bonding is achieved by silane coupling agents .Studies show that the composite resins of appropriate shade have been the material of choice for the repair of lithium disilicates to provide aesthetic appearance and ease of manipulation. To withstand functional loads, the bond between the repair material and the restoration must be sufficiently strong. The repair material which ensures this bond should have a minimal coefficient of thermal expansion and minimal polymerization shrinkage, as it may affect its bond strength to ceramics.
There are different brand of composite resin available for repair of lithium disilicates.
Every manufacturer claims that their brand of composition of materials is superior to others in their functional efficiency and bonding qualities. A Study has been conducted to asses, the micro-shear bond strength of one of the commercially available composite resin to the lithium disilicate which may be influenced by different surface treatments like air abrasion with different particle sizes, hydrofluoric acid etching, and silane coupling agents.
AIMS AND OBJECTIVES
AIMS AND OBJECTIVES
The aim of this study were,
To find out the shear bond strength between lithium disilicates and composite resin materials namely,
1. BIO-COMP INGOTS
2. IPS IMPRESS DIRECT – IVOCLAR.
This study was done with the following objectives,
To evaluate the shear bond strength of lithium disilicates and composite resin.
To evaluate the suitable surface treatment for the all ceramic repair.
To evaluate the mode of failure (adhesive, cohesive or combination).
REVIEW OF LITERATURE
1. J Robert Kelly 38 (1990) evaluated a study based upon fracture mechanics and fracture tomography for clinically failed restoration. This will improve the procedures and guide the ceramic engineer in desigining of material to resist intraoral stresses. A majority of the crown apparently failed from internal surface, indicating this as the highest tensile surface or location of largest flaws.
2. A.Llobell et al 25 (1992) – studied about eight intraoral porcelain system i.e oral ceram – etch , scotch prime, rocatec, command ultrafine, silistor, clearfil, porcelain bond were used .Load fatigue was used in this testing method to stimulate the repetitive action of mastication. Clearfil and bisfil did not fail the group. Fracture of porcelain restoration is often considered as emergency treatment and represents a challenge for the dentist.
3. Douglas A.Terry 13 (1993) evaluated adhesive and restorative success for indirect restoration. At the restorative tooth interface, the dentin bond strength of the cerec and IPS empress 2 ceramic inlays cemented with two different luting cements was similar.
Microtensile testing evaluates the bond capability of the restorative system to dentin.
4. Abdul- Haaj A suliman 1 (1993) evaluated the porcelain repair by use of various surface treatment and hydrophilic bonding resins. Surface treatments were air abrasion, roughing with a diamond bur, hydrofluoric acid and Silane coupling agent applied to all porcelain surfaces. Porcelain with clearfil bonding agents showed better results.
5. Daniel & Tylka DMD 10 (1994) made a study on comparision of fluoride gel and hydrofluoric acid etchants, which produce a porous surface visible under scanning electron microscope and analysed for bond strength which revealed cohesive failures in more number .
6. Karson A. Kupiee 23 (1996) conducted a study based on porcelain surface treatment and agent for composite porcelain repair. Intra oral repairs often involve bonding composite to fractured porcelain. Eight different treatment procedures were used to bond composite cylinders to porcelain surfaces in each group. This study also indicated that silane treatment of porcelain is critical for development of suitable bond strength for composite.
7. David A. Felton27 (1997) evaluated bond strength & durability of ceramic bonding system joined to fixed porcelain. The use of 3 component ceramic bonding agent in combination with dual cured luting agent can be recommended for achieving consistent and durable bonds of the porcelain material.
8. Jeffery C.Chang 22 (1998) Dual cured cements have been used with castable ceramic restorations. Four cements tested in this study produced moderately high tensile bond strength which are suitable for clinical use. The weak link was seen between the cements and the ceramic surface, because the majority of fracture was adhesive and at the interface. The purpose of this study is to determine the tensile bond strength of dual cured cements.
9. Chalermpol Leevailoj 9 (1998) In this study, advanced cement (Resin modified GIC) is not recommended for use with all ceramic crowns. The use of this cements in clinical situation showed expansion which could result in brittle fracture of tooth structure. The study used human maxillary premolars which is prepared and luted with five types of cements and stored for two months and analysed for fracture lines and crack initiation.
Specimens were loaded for compressive test and resulted more fractures in advanced cements.
10. Konji Kamda 24 (1998) evaluated the effect of various ceramic surface treatments on shear bond strength of four resin luting agents to cerec 2 ceramic material. This study demonstrated that silane coupling agent was essential to obtain a strong shear bond between four commercial resin luting agents and cerec 2 ceramic material. This bonding of composite to ceramic materials has played an important role in dentistry.
11. Goran Sjogren 17 1999- studied fracture rates of the dicor crowns placed on molars incisors and canine, were relatively high. Thus dicor crowns should be used with caution when the restoration are likely to be subjected for high stress. Ninety- eight all ceramic Dicor crowms placed in 46 patients regularly visiting a general practice were evaluated with California dental association (CDA) criteria , to analyse the fracture rates.
12. Mutlu Ozcan 34 (2002) described the use of intraoral silica coating and silanization as an alternative bonding procedure for 3unit, all ceramic resin- bonded FPD. The shear bond strenghgt was analysed which resuled in specimens with silica coating showing higher bond strength.
13. Deniz Gemalmaz 11 (2002) studied multiple and single step dentin adhesives used on cemented IPS Empress crown which provides an acceptable survival rate. All the crowns were examined for marginal integrity .The slight over extension observed above cervical margin of crowns with subgingival finish lines contributed to increased bleeding on probing, resulted in less longevity period.
14. Won Suck45 (2003) demonstrated that air borne particle abrasion followed by acid etching with hydrofluoric acid produced the highest tensile bond strength values of composite to ceramic .It depended on the surface topography of ceramic.
15. Giuseppe Isgro 16(2003) invitro study demonstrated that overglazed surface treatment increases the strength of ceramic core and veneering porcelain materials .The final surface preparations is of clinical importance because it may have a positive effect on longevity of all ceramic heat pressed restorarions which can be single or double layered.
16. In-Sung Yeo 21 (2003) demonstrated that the marginal discrepencies of 3-all ceramic systems tested were within the clinically acceptable standard of 120µm .Marginal fit is avery important aspect of FPD because large marginal opening allows more plaque accumulation ,gingival sulcular fluid flow ,bone loss ,resulting in microleakage ,recurrent caries and periodontal disease.
17. Mohammad Albakry 35 (2003)- This study deals with grinding , sand blasting and polishing. Surface roughness may not be the only feature that determines strength.
Other issues such as porosity, microstructural residual stresses, surface and bulk defects. Also determines the bonding strength of ceramic surface and composite.
18. Ariel.J.Raigrodski 6 (2004)-many restorative systems for fabricating all –ceramic (FPD)have been tested .Because of material –inherent advantages Y-TZP-based all ceramic restorative system allow clinicians to use traditional clinical procedures similar to those used in fabrication of metal ceramic restoration in term of preparation design and cementation procedures.
19. Alfredo meyer Filho et al 4 (2004) evaluated the effect of different surface treatment on the microtensile bond strength (µ-tbs) of composite bonded to hot –pressed ceramic .The null hypothesis tested was that neither of the surface treatments (salinization or fluroric acid etching) would produce greater bond strength of composite resin to the ceramic.
20. Mehmet A kilicarslan26 2004 studied the fracture loads of posterior complete coverage metal ceramic restorations with all ceramic inlay-retained resin bonded FPDs. Resulted in inlay retained zirconia – based ceramic RBFPDS showed the greatest fracture resistance among all.
21. Ahmed Attia2 (2004) studied the application of ceramic primer may be an alternative to hydrofluoric acid etching with its expected health hazards when luting CAD-CAM and low fusing all ceramic crowns.
22. Carlos Jose sores8 (2005) evaluated tooth colored restorative material vary considerably in composition and require different protocols for adhesive cements.
Sandblasting, etching technique and silanes coupling agents are the most common procedures with improved results.
23. P. Vult Von sterfem43 (oct 2005) investigated the fracture resistance of zirconia crowns and to compare the results with crown made of a material with clinical performance. Dentalceramics, dental porcelains, all ceramic crowns, aluminium oxide, zirconium di oxide, thermocycling were employed.
24. Moustafah Aboustelin32 (2005) studied about bond strength of zirconia veneers which is considered as a weak link in the layered all ceramic restorations. Zirconia disc press
on and layering of veneer and double veneering were done. The double veneering technique promises superior function & performance.
25. Ahmed Atta3 (2006) studied fracture loads of CAD-CAM crown fabricated from millable composite resin blocks. They are an alternative to all ceramic crowns fabricated from conventional feldspathic machinable ceramic. Specimens were cemented and cyclic load of fracture was applied. Resulted in high fracture strength resistance of the crowns fabricated using CAD-CAM.
26. Mitsuyoshi Tsumitha DDS phd28 (2006) evaluated the effects of the shape of the zirconium framework of implant supported all ceramic fixed partial denture (FPDs) on the fracture strength and fracture mode.
27. Saadet Saglam Atus39 (2006)- recommened the application of silica coating and phosphate monomer containing bonding/silane coupling agent mixture to increase the adhesive resins bond strength to an airborne –particle abrasion.
28. Stefen Wolfartet al42 (2007)-compared the quari static(qsfs)and fatigue fracture strength of all ceramic resin bonded 3 unit inlay- retained fixed partial dentures made from a heat –pressed lithium-disilicate based glass-ceramic(LDGC) and a CAD-CAM manufacturer yttrium –oxide partially stabilized zirconia frame work.
29. Wallison a Vasconcellous44 (2007) evaluated the effects of distinct surface treatments on the micro-tensile bonding strength (µTBS)of different ceramic materials .The occlusal surface of eighteen human maxillary molars were flattened perpendicularly to the long axis and divided in groups based on surface treatment and ceramic materials.
Luting resin were used to bond ceramic materials to the exposed dentin specimens under a load of 7.5N .Ceramic materials with different chemical formulation and
application yielded significantly different bond strengths to human dentin must receive distinct surface treatments accordingly.
30. Mohammad Zahran29 (2007) All ceramic crowns have a tendency to fracture during function , especially the posterior areas.The use of yttrium-stabilized Zirconium oxide ceramic as a substructure for all –ceramic crowns improves fracture resistance is un proven . The aim of this study was to compare fracture strength and fatigue resistance of new Zirconium –oxide and feldspathic all-ceramic crowns made with computer – aided design /computer –aided manufacturing (CAD-CAM).
31. Moustafa N.Aboushelib 31(2007) studied on newly introduced yttrium partially stabilized zirconia polycrystals (Y-TZP) of all-ceramic restorations. The mechanical properties of these materials can be further improved by the addition of a secondary dopant phase.The aim of this work was to evaluate the properties of a new nano- composite ceramic used as a dental framework material.
32. Anuratha Prakki5 (2007) evaluated the fracture resistance of ceramic plates cemented to dentin as a function of the resin cement film thickness .ceramic plates (1 and 2 mm thicknesses) were cemented to bovine dentin using resin composite cement .The film thicknesses used were approximately 100 ,200 and 300 µm . Non cemented ceramic plate were used as control. Fracture load (N) were obtained by compressing a steel indenter in the centre of the ceramic plates.ANOVA and tukey tests (α=0.05) were used for each ceramic thickness to compare fracture loads among resin cement film used.
33. Nadia Z.Fahmy37 (2008) evaluated the effect of artificial saliva storage on the hardness ,crack length and fracture toughness of a glazed ,polished and bleached hydro thermal low –fusing glass –ceramic (Duceram LFC).
34. Mohamed F.Ayad30 (2008) evaluated the effect of surface treatments on surface roughness and bond strength to dentin and enamel of a commercially available heat – pressed dental ceramic(IPS empress)
35. Murat Yenisey33 (2008) evaluated the effect of 2 chemical solvents, hydrogen peroxide and methylene chloride, on the shear bond strength of quartz and glass fiber posts to a composite resins.
36. Gokhan Akgungor et al18 (2008) evaluated the effect of different surface treatments on the short term bond strength and durability between a zirconia post and composite core resin .He had four groups with different surface treatments and subjected to distill water storage . Specimens were then sectioned perpendicularly under cooling water.
37. Mehmet dalkiz,DDS, PhD 36(2009) determined the effects of six surface treatment methods on the surface of feldspathic ceramic materials ,using metal discs coated with low fusing and ultralow fusing feldspathic ceramic. Treated ceramic surfaces were examined by means of profilometry and transmission electron microscopy.
38. Gilberto A BORGES15 (2008) studied the hypothesis that fracture loads of fatigued dental ceramic crowns are effected by testing environment and luting cements. Fracture load of the three ceramic systems was found to be influenced by ceramic composition.
Moreover cement and the fatigue condition influenced the fracture loads of the crown specimens evaluated.
39. Mehmet del kiz et al27 (2008) determined the effects of six surface treatments methods on the surface roughness of two feldspathic ceramic materials. Surface treatments were autoglazing , over glazing , corse diamond disc grinding .
40. Bandar M.A.AL Makramani7 (2008) conducted this study to resist the occlusal fracture of turkom ad ceram fused alumina compared to procera all ceram and in ceram all ceramic restoration. This will load the fracture and modes of fracture happens. This demonstrates equal / higher loads at fracture than currently accepted all ceramic materials.
41. Hyun-Pil Lim et al20 (2010) compared the fracture load and failure types of implant supported zirconia all ceramic crowns cemented with various luting agents. The ceramic frameworks from a presintered yttria stabilized zirconia dioxide block using computer aided design / computer assisted manufacturing technology and were then veneered with feldspathic porcelain. Three luting agents were used. Composite resin cement showed the highest mean fracture load followed by acrylic/ urethane cement and zinc oxide eugenol cement. This types of failure varied between groups.
42. Siegward40 (2010) evaluated the clinical fracture rate of crowns fabricated with pressable, leucite- reinforced ceramic IPS empress and related the results to the type of tooth restored. Here adhesively luted IPS empress crowns showed a low fracture rate on incisor & premolar of a somewhat higher fracture rate on molars & canine.
43. Dr Med Dent46 (2010) Investigated the durability of repaired all ceramic crowns after cyclic loading. The tested hypothesis was that silica coating of the fracture site using cojet system followed by silane application increased fracture load of the repaired
crowns compared to the other method of surface treatments o the fracture site before repair.
44. Shaymaa E.Elsaka41 (2015) evaluated the repair bond strength of non-hybrid resin composite to a novel CAD-CAM hybrid ceramic based on intraoral ceramic repair system. Adhesion, microtensile bond strength, CAD-CAM hybrid ceramic, surface treatment were reported.
45. M.P.Dittmer12 (2010) investigated the influence of 4 different occlusal concepts on stress distribution in 4 –unit FPD made of Zirconia. Finest element analysis,stress fracture, materials were tested and occlusion checked.
46. Futoshi Komine14 (2012) evaluated the effect of various surface treated for zirconia ceramics on shear bond strength between an indirect composite material and zirconia ceramic, Air borne particle abrasion at pressure of 0.1Mpa or higher, increases initial and durable bond strength between indirect composite material and zirconia ceramic
MATERIALS AND METHODS
The objecti ve of thi s stud y was t o evaluat e the shear bond st rength of com posit e resin repair m at erial to lithi um disili cat es. It was an invitro st ud y conduct ed with singl e repair s ystem undergoi ng di fferent s urface treatm ents .
MATE RIALS
The m at eri als us ed in t his stud y were
Li thium di sili cate ingots
Alumi na part icl es [50 , 110 , 250 µm]
H ydrofl uoric aci d 9.6%
Compos ite – IPS EM PRESS D IREC T - Ivocl ar
Repai r m at eri als of Ivoclar (Fi g-1).
Cerami c Rep ai r ki t -Ivocl ar material
Comp on ents Comp osi tion Us e
Tot al Etch H ydrofluori c acid (9.6% i n wat er)
Us ed t o cl ean cerami c, com posit e, and met al surfaces
Monobond-N Alcohol solution of s ilane methacr yl ate, phos phori c acidm ethacr yl ate and sulphide methacr yl ate.
Act s as one com ponent prim er that ai ds i n adhesi on
Hel iobond Bis -GMA and tri et h ylene
gl ycoldi met hacr yl at e (99wt .%), catal ys ts and st abiliz ers < 1%.
Li ght -pol ym erizing bondi ng agent
Composi te res torative mate ri al for repair –E mp ress Di rect , I voclar
Empres s Direct is a radi opaque, nano -hybri d com posi te us ed for th e restorative repai r procedures. It is li ght cured at t he wavelengt h range of 400 – 500 nm of blue l i ght .
Trad e name Comp osi tion Us e
Empres s Direct
Dim ethacr yl at es (17 –18 wt. %) Fill ers: bari um gl as s , ytt erbium tri fluoride, mixed oxide and prepol ym er (82 – 83 wt %).
Addit ional cont ents : additives, catal ys ts , st abilizers and pi gments (< 1.0 wt %).
Li ght -
pol ym erizing h ybrid composit e restorative
mat eri al
INSTRUMENTS
The instruments used in this study were
1. Thick plastic scaffold [4x4x4mm3]
2. Orthodontic separator placer
3. Mould for holding ingots and metal rod
EQUIPMENTS
The equip m ents us ed in t his st ud y were
1. UTM (Universal testing machine)
2. SEM –Scanning electron microscope
3. Optical microscope 4. Sand blaster (Santer) 5. Optical microscope
FABRICATION OF SPECIMENS
A) INGOTS FABRICATION-
In this study, total of 90 readily available lithium disilicate cylindrical ingots of dimension 10x10x10mm3 were used (BIO- COMP INGOTS, SHADE A1). (Fig 2)
B) SCAFFOLD FABRICATION –
A thick plastic scaffold of 4x4x4mm3 was exactly measured and sectioned off from commercially available thick quality straws .(Fig 3).
C) COMPOSITE FABRICATION
Composite resin is flowed into the scaffold and polymerized to get the desired dimension which will resemble repair of fractured all ceramic crown by composite resin .
METHODOLOGY
All the 90 samples were divided into three groups A , B , and C based on the different sizes of aluminium oxide particle [50-µm , 110-µm , 250-µm] were the samples are subjected to air abrasion using sand blaster (Santer Fig-4) . The samples are then etched with HYDROFLUORIC ACID 9.6% for 30 seconds, rinsed for 30 seconds , dried with oil free compressed air for 30 seconds (Fig-5). This sample represents the surface treatment of a fractured all ceramic crown. Based on aluminum oxide particle sizes used for air abrasion.
The samples were divided three groups. (FIG-6,7and 8) GROUP A - 30 SAMPLES AIR ABRADED WITH 50µm GROUP B - 30 SAMPLES AIR ABRADED WITH 110µm
GROUP C- 30 SAMPLES AIR ABRADED WITH 250µm
Before attaching the repair material, the ceramic ingots were coated with Silane coupling agent [Monobond –N] (Fig-9) and placed in open air for 30 seconds, so that excess bonding agent can evaporate. This M onobond –N acts as an one compon ent prim er and ai ds in adhesion . Foll owi ng thi s Heliobond -l i ght pol ymerizing bonding agent was appli ed to the s urface and a thick pl ast ic scaffol d of 4x4x4mm3 dimension whi ch is c yli ndri cal in shape ,was pl aced on the uncured adhesive surfaces of each s am ple.(Fi g -10)Composi te resi n will be loaded l ater int o the scaffol d to obt ain the desi red shape.(Fi g -11) Thes e s urfaces are t hen pol ym erized to st abil ise the plastic scaffolds on t he cerami c surface, t o ensure
that no fl as h of resin com posi te extends on to t he ceramic ingot sam pl e be yond the base of t he s caffold.(Fi g -12)
The composit e resin is t hen packed into the s caffol d and cu red for 40 seconds (Fi g-13) and the ingots were placed in the room t em perature (230 C) for one hour pri or to the removal of pl asti c s caffol d. This procedure is repeat ed for all t hree groups of 30 sam pl es each. The s pecim ens were t hen st o red in distill ed wat er at 370C for 24 hours (Fi g14 ). All the sampl es were checked under the opti cal m i cros cope (30x zoom ) to exami ne the int erfaci al defect s or air bubbl e i nclusi on (Fi g-15 ). If found positive, s ampl es were di scarded and new s amples were m a de.
These s ampl es now represent t he fractured all cerami c crowns repa i red with composit e resi n (Fi g 16 ). The com po sit e resin i s now subject ed to s hear bond anal ys is usi ng universal t esting m achi ne (Fi g-17 ), in order to determi ne the shear bond st rength bet ween t he all ceram ic ingots and t he com posit e resi n repair mat eri al.
Each cerami c i ngot was attached to t he t esti ng m achine with the help of cust omis ed m et al di es whi ch had been al re ad y m ade (Fi g -18) for the desired dimension. The com posit e resi n is then subj ected to the shear bond b y usi ng the custom is ed m et al rods whi ch has tapered and sharp edges . (Fi g-19) In t he universal t es ting m achi ne a shear load was appli ed at a crosshead speed of 0.5mm/ min until the breakage(Fi g -20 ).
The int erfaci al shear strengt h was cal cul at ed b y divi ding the maximum load recorded on the fai lure b y the ci rcul ar bonding area in square milli met ers
and express ed i n M p a. Specimens that fai led prematurel y duri ng handli ng were assi gned zero strengt h values and were i ncluded in st ati st ical anal ys is . Statist ical anal ys is was perform ed using ONE WAY ANALYS IS OF VAR IANCE (ANOVA).A Dunet T3 m ul tiple comparision t est was used to det ermine i f a si gni ficant difference in t he l oad among the group exists. All debonded specim ens were examined und er the s canning el ect ron mi cros cope to det ermine the mode of fract ure (Fi g-21,22and23). The fract ure modes were recorded as
Mode 1: adhesive failure (if one fracture site was at the composite or ceramic surface and the other site remained adhesive only)
Mode 2: cohesive failure in adhesive layer (fractures extending through the adhesive),
Mode 3: cohesive failure in composite (failure totally within composite)or cohesive in ceramic (failure totally in ceramic),
Mode 4: mixed failures (failure including at least two of these materials).
The readings were stastically analysed to derive at the results and conclusion.
PHOTOGRAPHS
FIG- 1 IVOCLAR VIVADENT CERAMIC REPAIR KIT
FIG – 2 LITHIUM DISILICATE INGOTS (BIO COMP )
FIG – 3 PLASTIC SCAFFOLDS
FIG – 4 AIR ABRASION WITH SANTER
FIG – 5 HYDROFLUORIC ACID ETCHING
FIG -6 GROUP A AIR ABRADED WIT 50 µm
FIG – 7 GROUP B AIR ABRADED WIT 110µm
FIG- 8 GROUP C AIR ABRADED WITH 250µm
FIG – 9 MONOBOND – N APPLICATION
FIG- 10 HELIO BOND APPLICATION
FIG -11 PLASTIC SCAFFOLD STABILISATION
FIG-12 LIGHT CURING STEP
FIG-13 PACKING OF COMPOSITE RESIN
FIG-14 DISTILLED WATER STORAGE
FIG-15 OPTICAL MICROSCOPIC
FIG-16 INGOTS WITH COMPOSITE RESIN
FIG 17 UTM
FIG-18 METAL DIE
FIG 19 SPECIMENS PLACED IN UTM
FIG-20 SPECIMENS ANALYSED FPR SHEAR IN UTM
FIG 21 SEM image of 110µm
FIG 22 SEM image of 50µm
FIG 23 SEM image of 250µm
TABLE OF READINGS
SHEAR BOND STRENGTH – READINGS
With all 3 groups of 30 samples each [total 90 samples] where subjected to shear bond strength testing using Universal Testing Machine. The readings are tabulated as follows.
TABLE -1 READINGS Sample 50 µm -A
In MPa
110µm-B In MPa
250µm In MPa
1 5.61 0.00 6.65
2 5.69 6.94 4.92
3 0.00 7.24 4.09
4 6.31 6.75 0.00
5 6.51 7.12 5.04
6 4.91 6.90 5.64
7 5.20 6.69 6.64
8 4.01 7.10 6.02
9 5.92 6.89 5.12
10 6.09 6.85 0.00
11 8.04 7.16 4.03
12 0.00 6.94 5.92
13 6.49 8.92 6.47
14 6.42 6.81 0.00
15 7.01 7.90 5.82
16 3.12 6.12 6.34
17 5.91 7.09 0.00
18 0.00 8.09 9.12
19 4.21 6.14 4.92
20 4.10 0.00 0.00
21 6.11 6.11 6.56
22 5.12 7.04 6.46
23 4.89 8.87 4.29
24 0.00 7.85 5.12
25 5.60 6.19 6.12
26 5.14 6.01 5.69
27 6.12 8.75 5.64
28 4.92 6.14 4.39
29 0.00 7.14 7.04
30 5.69 7.86 6.12
THE MEAN STANDARD DEVIATION OF ALL THE THREE GROUPS
TABLE-2
Experimental Groups
N Mean (SD) Premature Failure
50 µm 30 4.64 (2.32) 5
110 µm 30 6.65 (1.98) 2
250 µm 30 4.81 (2.41) 5
COLOUR GRAPHIC REPERSENTAION OF MEAN OF THE SHEAR BOND STRENGH VALUE CHANGES OF 3 GROUPS
AT DIFFERENT TIME INTERVAL MEASUREMENTS
GRAPH-1
GRAPH-2
4.64
6.65
4.81
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00
50 m 110 m 250 m
Mean values
Mean values
2.32
1.98
2.41
0 0.5 1 1.5 2 2.5 3
50 m 110 m 250 m
Standard Deviation
Standard Deviation
COLOUR GRAPHIC REPERSENTATION OF PREMATURE FAILURES WITHIN 3 GROUPS
GRAPH-3
STATISTICAL ANALYSIS
MATERIAL GROUPS
All the 90 samples were divided into three groups based on the aluminium oxide particle sizes-used for air abrasion
GROUP A – SAMPLES TREATED WITH 50µm GROUP B – SAMPLES TREATED WITH 110µm GROUP C – SAMPLES TREATED WITH 250µm
ANALYSIS FOR SHEAR BOND STRENGTH
In this study the shear bond strength values between lithium disilicate and composite resin repair materials were calculated after immersing in distilled water for 24 hours using Universal Testing Machine. The mean standard deviation and test of significance of mean values of the three different groups were tabulated and comparison was done within each group.
ANOVA TABLE-3
Group-A Source of variation Sum of Squares
DF Mean
Square
F value p value
50 µm Between Groups 2.39 2 1.196 0.211 0.811
Within Groups 153.27 27 5.677
Total 155.67 29
Since the F value between groups is 0.211 and the p value is 0.811 which is greater than 0.05, the null hypothesis is accepted and it is concluded that there is no significant difference among the three groups at 50 µm.
TABLE-4
Group-B Source of variation Sum of Squares
DF Mean
Square
F value p value
110 µm Between Groups 4.77 2 2.387 0.595 0.559
Within Groups 108.40 27 4.015
Total 113.17 29
Since the F value between groups is 0.595 and the p value is 0.559 which is greater than 0.05, the null hypothesis is accepted and it is concluded that there is no significant difference among the three groups at 110µm.
TABLE-5
Group-C Source of variation Sum of Squares
DF Mean
Square
F value p value
250 µm Between Groups 13.29 2 6.646 1.16 0.329
Within Groups 154.70 27 5.73
Total 167.99 29
Since the F value between groups is 1.16 and the p value is 0.329 which is greater than 0.05, the null hypothesis is accepted and it is concluded that there is no significant difference among the three groups at 250 µm.
TABLE-6
Experimental Groups
N Mean (SD) Premature Failure
50 µm 30 4.64 (2.32) 5
110 µm 30 6.65 (1.98) 2
250 µm 30 4.81 (2.41) 5
Using ANOVA, there is a significant difference among the groups at p < 0.01.
Group I 50 µm The mean and standard deviation is 4.64±2.32 which is statistically significant at p < 0.01.
Group II 110 µm The mean and standard deviation is 6.65±1.98 which is statistically significant at p < 0.01.
Group III 250 µm The mean and standard deviation is 4.81±2.41 which is statistically significant at p < 0.01.
Where the F value stating the difference in the variation among the three groups was found to be 7.475 while the p value was 0.00101. Since the p value is less than 0.01, it is concluded that there is a significant difference among the three groups at 1% level of significane.
Multiple Comparisons - Dunnett t (2-sided) a TABLE-7
Dependen t Variable
(I) Group
(J) Group
Mean Difference
(I-J)
Std.
Error
Sig. 95% Confidence Interval Lower
Bound
Upper Bound
50 µm 50µm 250µm 0.67 1.07 0.76 -1.82 3.15
110µm 250µm 0.17 1.07 0.98 -2.32 2.66
110 µm 50µm 250µm -0.95 0.90 0.48 -3.04 1.14
110µm 250µm -0.68 0.90 0.67 -2.77 1.41
250 µm 50µm 250µm -1.33 1.07 0.37 -3.83 1.17
110µm 250µm -1.48 1.07 0.30 -3.98 1.02
A Dunnett t-tests treat one group as a control, and compare all other groups against it.
Multiple comparisons have been made between the three groups using Dunnett t (2 sided) method. The results showed that there is no significant difference between 50 µm, 110 µm and 250µm at p < 0.01.
Group I – Multiple comparisons were made. 50 µ has showed statistically insignificant difference in values from 110µm and 250µm at p < 0.01.
Group II – Multiple comparisons were made. 110 µ has showed statistically insignificant difference in values from 50 µm and 250 µm at p < 0.01
Group III – Multiple comparisons of were made. 250 µ has showed statistically no significant difference in values from 50 µm and 110 µm at p < 0.01.
The mean difference between three groups showed statistically insignificant differences. 110 µm showed greater values than 250µm which in turn is found to be lesser than the values of 50µm. Thus 110 µm shows greater values. Which proves the micro shear bond strength composite resin is greater in Group-B .
RESULTS
RESULTS FOR SHEAR BOND STRENGTH
30 samples from each group A, B , C underwent a shear bond test using a universal testing machine –INSTRON . The results obtained were tabulated and graphs were made. After statistical analysis, the following inference was obtained
All 3 groups of 30 samples each, underwent the shear bond test using INSTRON .As per the obtained results it shows that GROUP –B (110µm) has more shear bond strength values compared to GROUP -A followed by GROUP-C .
All the samples were viewed under scanning electron microscope to rule out the mode of failure. Resulted in mode-1 failure, adhesive failures were more prominently seen.
GROUP-B ˃ GROUP-A˃ GROUP-C
Experimental Groups
N Mean (SD) Premature Failure
A-50 µm 30 4.64 (2.32) 5
B-110 µm 30 6.65 (1.98) 2
C-250 µm 30 4.81 (2.41) 5
DISCUSSION
All cerami c restorations are considered as a good opti o nal procedures in fixed prosthodont ics not onl y becaus e of me chani cal st rengt h but also for estheti c qual ities i mpart ed b y cerami c m ateri al2. The modern da y dent al practices util ize cerami c restorations i n two st ructures. The substructure is made wit h less thi cknes s whi ch devel ops hi gh ri gidit y maint ai ning t he struct ural durabilit y of superst ructure of cerami c restoration s.11
All cerami c crowns and bridges are comm onl y us ed in fixed prosthodont ics because of thei r excell ent biocom patibili t y and superi or estheti c qualiti es. However cerami c fail ures have been oft en report ed due to fracture of either as mat eri al its el f or exposing the cerami c s ub st ructure .16 In such cases repai r of cerami c fracture has been a m andator y procedure t o continue t he funct ional as pe cts of porcel ain restorations i ntraorall y. The repair of ceram ic int raorall y i s a neces sit ating procedure. For repair develops a unpl eas ant experi ence for the pati ent and arduous for the cl ini ci an . To rem ove t hese rest orations from mout h .25
Int ra oral rep ai r of porcel ain reduces cl inical ti me and l ess treatm ent sess ions for the pati ent. M oreover this procedure rest ores es thetic and function in eas y, inexpensive and rapid form38.
Fracture of all ceramic rest orati ons may be due to traum a, i nadequate occlusal adjustment, parafunctional habi ts, fl exural fati gue of the cerami c subst ructure, incom patibi lit y of t he coeffici ent of t herm al expansi on between the porcel ain and t he venerred cerami c struct ures, failures i n the adhesive bondi ng, i nadequat e tooth reducti o n during dent al preparati on, porositi es in porcel ain and inappropri at e coping desi gn. These failures m ay be cl assifi ed as
fracture invol ving onl y t he cerami c bo dy or as sociated with the expos ure of the sub st ructure .38
Various mat eri als have been us ed to m eet the dem ands of repai r ing cerami c. Earli er m eth yl methacr yl at e pol ym ers were us ed as a veneering mat eri al i n fixed parti al dentures. However the us e of met hyl m et hacr yl at e pol ym er was rest ri ct ed becaus e of the s ubstanti al differences in coeffi cient of therm al expans ion compared with cerami cs, l ow abrasive resi stance and poor estheti cs .25 Later i nt erest in li ght activat ed mat eri als was renewed becaus e of marked im provem ent in m echan i cal properti es after addition of mi crofillers to the res inous mass. The l atest improvem ent i n t hese m at eri al s was t he creation of chemi cal bonding of resi n t o the ceramic surfac e wi th t he pret reat ment o f the surface and the appli cat ion of coupl ing agent s. The chemical adherence of the opaque l a yer on t he cerami c subst ruct ure r educed the creat ion of m arginal gaps caus ed b y t he pol ym eriz ation s hri nkage of t he resi n and the appreci abl e differences in coeffi ci ent of therm al expansi on of t wo m at eri als. The t ype of com posit e resin also affects its bond strengt h to cerami c. For repai r purposes , use of the h ybri d composit e resins was advised as the m ost s uitable ones .16
Various methods have been i ntroduced to repair fractured lithi um disili cate crown wit h resin composit e. In earlier repair s yst ems, mechanical ret ention was aim ed throug h the cerami c surface t reat ments s uch as di amond rougheni ng. Furt her i mprovements i ncludes ai r -part icl e abrasion of the s urface with alumi num oxi de, and et chi ng the fract ured porcel ain parts with h ydrofluori c acid, to enhance bonding the com pos ite resin to lithi um disili cates. Furt herm ore, silane -coupling agent forms a chem ical coval ent bond bet ween sili ca on the cerami c surface and resin compos ite whi ch will i mprove
the microm echani cal int erl ock and al s o improves wetti ng of the cerami c surface for t he comp osit e.38
The sil ane most oft en used in dentist r y is t he 3 -methacr yl ox yprop yl - trim ethox ys ilane, which i s a difunctional molecul e. The one s ide of t his molecul e has a m ethacr yl ate group capabl e of co -pol ymerizati on wit h methacr yl ate -bas ed adhesives and resi ns routinel y us ed for dental procedures . The other side, aft er h ydrol ys is, has the pot enti al to form chemi cal bonds t o the porcelai n s urface. Aceti c acid is com monl y us ed to acti vate or h ydrol yz e silane b y reacting wi th the t hree m ethox y ( -OC H3) groups loc at ed at one end of t he sil ane m olecule and replacing them wit h h ydrox yl ( -OH) groups. The h ydrox yl groups on one end of the activat ed silane mol ecul e are now capabl e of reacting di rect l y with corresponding hydrox yl groups present on t he surface of fel dspat hic ceram ic. The opposi ng h ydrox yl groups fi rst i nteract with one another vi a h ydrogen bonding. As water i s lost, a condens ation pol ym erizati on reaction occurs and covalent bonds are formed. The individual s ilane mol ecul es have coval entl y bonded not onl y t o the porcelai n surface, but also to adj acent silane mol ecul es , es sent ial l y formi ng a pol ym er net work on the surface. The methacr yl ate group on the ot her end of t he si lane mol ecul e can now react vi a free radi cal addit ion pol ym erizati on wit h methacr yl ate gr oups in subs equentl y placed adhesives and met hacr yl at e -based mat eri al s .10
Sandbl asting was described as t he most effective surface t reatm ent for the fractured all ceramic rest orati ons regardl ess of whet her the fracture was at super structure or sub st ructu re because i t improves t he ret ent ion bet ween the surfaces of resin by cl eaning oxides or an y greas y m at eri al from cerami c surfaces creating ver y fi ne roughness enhancing m echani cal and chem ical
bondi ng bet ween resins and ceramics. However compulsory use of sil ane together with alumi nium oxide was advised in order to avoid changes i n ret ention .35
Different s ys t ems for repai ring cerami c restorati ons have been used s uch as Enamilit e 500 . Si lanit , C eram Et ch, S cot ch Prim e, Porceli te and recentl y Cojet S yst em , Cl earfil SE Bond, Bistit e II, Scot ch Bond, Cim ara, R evi tal ize Kit, Silist or and P orcel ain R epair Ki t of Ultra Dent , Pulp Dent, Dent Zar.
Among thes e m at erials this stud y was conducted to eval uat e t he bond strength of Cerami c R epai r -Ivocl ar s ys tem wi th co mm ercial l y avail abl e lit hium disili care i ngot s Bi o-Comp.38
The dent al profes sion still has no univers all y accept ed bond st rength t est for resin composit es bonded t o cerami c, despit e t he great am ount of research papers on t his t opi c. Tensi le, flexural , and shear tests have been us ed t o measure the resi n porcel ain bond st rengt h, with the shear bond s trength test bei ng the most requi red tes t for efficient bondi ng. Shear bond was chosen for this s tud y becaus e m ultipl e s ubstrat es were us ed for bonding t he compos ite. In addition, ant erior res torations are subject ed prim aril y t o shear s tress es, and t he shear t est is consi dered appropriat e for quanti f ying t he st rength of cerami c repairs . Thi s stud y appli ed minimal t herm al c ycl es to the bonded int erface. The addition of therm al stress m a y have affect ed adhesion, but it has never been dem onst rated t hat c ycli c therm al t esti ng i s rel at ed t o clinical failures .4
The ingots after the shear test were s canned under SE M (Scanning Elect ron Mi cros cope ). To find out if the failur e i s adhesive, cohesi ve or com binational . Here all the ingots maxi mum sho wed the adhesi ve fai lures at the composit e resin bondi ng int erface .25
CONCLUSION
The aim of this study was to find out the micro shear bond strength between all ceramic crown material and its repair systems. The materials used were,
1. BIO-COMP INGOTS
2. IPS IMPRESS DIRECT – IVOCLAR.
A standardized procedure was adopted for the preparation of test specimens.
Total of 90 samples of dimension 10x10x10mm3 were used. They were divided into three groups based on the aluminium oxide particle sizes.
GROUP A - 30 SAMPLES AIR ABRADED WITH 50µm GROUP B - 30 SAMPLES AIR ABRADED WITH 110µm GROUP C- 30 SAMPLES AIR ABRADED WITH 250µm
All the 30 samples of each group A, B and C were etched with HYDROFLUORIC ACID 9.6% for 30 seconds , rinsed for 30 seconds , dried with oil free compressed air for 30 seconds . Now the samples have under gone both physical and chemical surface treatments. This sample represents the surface treatment of a fractured all ceramic crown. Composite resin is then bonded to lithium disilicate ingot sample using Monobond-N and Heliobond . Overall now, this sample represents an all ceramic crown fracture subjected to surface treatment repaired with composite resin.
The s amples now repres ent the repai red all ceram ic crown. All t he 90 samples were subj ect ed t o s hear bond st rength anal ys is in t he Univers al Testi n g Machine – INSTR ON. Each cerami c i ngot s was att ac hed to t he tes ting machine with the help of cust omis ed m et al die whi ch has been al r ead y made of specifi c dimension.
Shear load was applied to all the sam ples at the cerami c compos ite interface and the readi ngs w ere appli ed in M pa. The s peci mens that fail ed prem aturel y during handling were assi gned z ero strength val ues. The obt ai ned val ues of each group were statisti call y anal ys ed and res ulted as,
Experimental
Groups
N Mean (SD) Premature Failure
A-50 µm 30 4.64 (2.32) 5
B-110 µm 30 6.65 (1.98) 2
C-250 µm 30 4.81 (2.41) 5
Group –B shows highest bond strength, because this group is air abraded with aluminium oxide particle size of 110µm which creates uniform abrasion in the surface of the lithium disilicates enhancing the mechanical interlocking of the composite towards the ceramic surface. In Group-A and Group-C the surface treatments with 50µm and 250µm respectively the bonding was not so effective in the bonding of composite. In Group-C were the samples are abraded wit 250µm internal cracks were absorbed in the ceramic ingots.
It is known that both airborne-particle abrasion and HF selectively dissolve the weaker glassy phase and exposed lithium disilicate crystals, both of which serve as retentive features.
The porous irregular surface facilitates the penetration of the resin into the micro-retentions of the treated ceramic surfaces. The only difference that could be observed was the presence of grooves on the ceramic after the airborne-particle abrasion. A possible explanation for this may be that as the surface abrades with alumina particle, microscopic cracks are produced.
Therefore, HF acid is able to penetrate and remove the glass matrix along the groove. The enhancement in surface associated with the altered topography caused the stronger bond, because resin could penetrate deeply in micromechanical undercuts.
All the debonded specim ens were exami ned under the s canni ng el ect ron micros cope t o det ermine the mode of fracture i ndividuall y for each group. The mode of failure was recorded as
Mode 1: adhesive failure (if one fracture site was at the composite or ceramic surface and the other site remained adhesive only)
Mode 2: cohesive failure in adhesive layer (fractures extending through the adhesive), Mode 3: cohesive failure in composite (failure totally within composite)
or cohesive in ceramic (failure totally in ceramic),
Mode 4: mixed failures (failure including at least two of these materials).
Scanning all the specimens mode-1 failures were more prominently seen. which are adhesive failures.
Within the limitations of the study the following conclusion were drawn.
1. The bond strength of GROUP-B samples, surface treated with aluminium oxide of 110µm was higher than the other groups followed by GROUP-C and GROUP-A .
2. Both mechanical and chemical surface treatments together enhanced the bond strength of ceramic surface towards composite resin.
3. Adhesive failiures were more prominently seen. (mode-1)
In this in vitro study, there was significant difference in the fracture load of lithium disilicate ingots depending on the surface treatment methods. Airborne particle abrasion followed by 9.6% Hydrofluoric Acid etching and application of silane coupling agent yielded the highest micro shear bond strength. Indicates smaller size particle showed weak bond strength and the larger size particle showed internal cracks on lithium disilicates. Efficient bond strength was seen in the particle size of 110µm.
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