I take this opportunity to sincerely thank my post graduate teacher and my guide Dr. M. Rajasekaran ,M.D.S., Professor ,Department of Conservative Dentistry and Endodontics, Ragas Dental College and Hospital, for his perseverance in motivating, guiding and supporting me throughout my study period. ,which had helped me to complete my thesis and moreover be a better student and clinician. Without his whole hearted support and scholarly advice this thesis work would not have been a reality.
I extend my sincere thanks to Dr. Anil Kumar ,M.D.S, HOD and Professor , Department of Conservative Dentistry and Endodontics, Ragas Dental
College and Hospital, who has been a support , a caring guide and also for his constant encouragement to widen the knowledge in various perspectives.
My sincere thanks to Dr. S. Ramachandran, M.D.S., Professor & former Principal, Dr. R. Indira, M.D.S., Professor and former H.O.D., Department of Conservative Dentistry and Endodontics, Ragas Dental College and Hospital, who helped me with her guidance, during my study period.
I extend my sincere thanks to Dr. P. Shankar, M.D.S., Professor, Ragas Dental College and Hospital, for his encouragement, support and guidance all throughout my study period.
May I acknowledge my profound gratitude to Dr. B. Veni Ashok, M.D.S., Professor, Dr.Shankar Narayan, M.D.S., Reader, who has been a great source
of support for me throughout my P.G program and have encouraged me wholeheartedly for my thesis and also for clinical works .
I would like to solemnly thank Dr. S.M. Venkatesan, M.D.S., Dr.
B.Venkatesh, M.D.S.,Dr. M. Sabari M.D.S, Dr. Arrvind, M.D.S. Readers, for
all the help and support during my study period. I would also like to thank Dr.
Nirmala, M.D.S., Dr. Shalini, M.D.S., Senior lecturers for their friendly
guidance and support. I also wish to thank the management of Ragas Dental College and Hospital, Chennai for their help and support.
I remain ever grateful to all my batchmates especially Dr.Suryalakshmi V.
Dr.Darlene Ann Johnson, juniors and friends - Dr.Ashok Jacob Abraham,
I would like to extend my heartfelt love and gratitude to my father - P.K.
Koshy , mother - Annie T. Koshy, and brother - Alan P. Koshy for their love, understanding, support and encouragement throughout these years without which, I would not have reached so far.
My sincere thanks to Mr.Muthukrishnan for his assistance in SEM analysis, Mr. K.Thavamani for his support in DTP and Binding works. I extend my thanks to Dr. Bijvin for his help in statistical work.
Above all, I am thankful to God, who always guides me, keeps me safe and has given these wonderful people in my life.
1 Bis GMA 2,2-bis[4-(2-hydroxy-3-
methacryloxypropoxy)phenyl]propane
2 TE Total Etch
3 SE Self Etch
4 SEM Scanning Electron Microscopy
5 RBCs Resin Based Composites
6 CTE Co- efficient of Thermal Expansion
7 TEGDMA Triethylene Glycol Dimethacrylate
8 MMA Methyl Methacrylate
9 PS Polymerisation Shrinkage
10 C-Factor Configuration Factor
S. NO. INDEX PAGE.NO
1. INTRODUCTION 1
2. AIM AND OBJECTIVES 6
3. REVIEW OF LITERATURE 7
4. MATERIALS AND METHODS 30
5. RESULTS 42
6. DISCUSSION 47
7. SUMMARY 65
8. CONCLUSION 68
9. BIBLIOGRAPHY 69
10. ANNEXURES -
Table 1 FREQUENCY DISTRIBUTION OF SCORES OF DIFFERENT GROUPS AT ENAMEL LEVEL.
Table 2 FREQUENCY DISTRIBUTION OF SCORES OF DIFFERENT GROUPS AT CEMENTUM LEVEL
Table 3 BETWEEN GROUP COMPARISON USING KRUSKAL WALIS TEST
Table 4 PAIRWISE COMPARISON OF GROUPS AT ENAMEL LEVEL
Table 5 PAIRWISE COMPARISON OF GROUPS AT CEMENTUM LEVEL
S.NO. TITLE
Graph 1 GRAPH SHOWING DISTRIBUTION OF SCORES OF DIFFERENT GROUPS AT ENAMEL LEVEL
Graph 2
GRAPH SHOWING DISTRIBUTION OF SCORES OF DIFFERENT GROUPS AT CEMENTUM LEVEL
FIGURE 1 TEETH SPECIMENS
FIGURE 2 MATERIALS USED FOR MOUNTING AND EMBEDDING SAMPLES
FIGURE 3 EMBEDDED SAMPLE
FIGURE 4 ARMAMENTARIUM
FIGURE 5 CAVITY PREPARATION
FIGURE 6 ETCHANT AND TETRIC N BOND(TOTAL ETCH)
FIGURE 7 TETRIC N BOND UNIVERSAL(SELF ETCH)
FIGURE 8 APPLICATION OF ETCHANT
FIGURE 9 APPLICATION OF BONDING AGENT
FIGURE 10 TETRIC N CERAM AND TETRIC N - CERAM BULK FILL
FIGURE 11 RESTORING WITH RESIN COMPOSITE
FIGURE 14
GOLD SPUTTERING MACHINE
FIGURE 15 GOLD SPUTTERED SPECIMENS
FIGURE 16 SCANNING ELECTRON MICROSCOPE
FIGURE 17 SEM IMAGES OF THE SPECIMEN SHOWING A PERFECT MARGIN AT 200X
FIGURE 18 SEM IMAGES OF THE SPECIMEN SHOWING A PERFECT MARGIN AT 500X
FIGURE 19 SEM IMAGES OF THE SPECIMEN SHOWING A MARGINAL GAP AT 200X
FIGURE 20 SEM IMAGES OF THE SPECIMEN SHOWING A MARGINAL GAP AT 500X
Introduction
1
INTRODUCTION
Restoration is a term used in dentistry to describe the repair of a missing or damaged tooth structure. Restorations are classified as either direct or indirect14 .The selection between direct and indirect technique is a clinically challenging decision-making process and is decided based on the remaining tooth structure, lesion size and aetiology, aesthetic, occlusal, endodontic and periodontal considerations ,number of teeth affected ,patient compliance, habits23 .Direct restorations have been largely employed to restore posterior teeth due to their low cost and less need for the removal of sound tooth substance when compared to indirect restorations, as well as to their acceptable clinical performance24,53.
Both amalgam and composite resin are considered suitable materials for restoring direct posterior Class I and Class II cavities. Some advantages can be related to composite restorations over amalgam such as better esthetics, their adhesive properties resulting in reduced preparation size18, reinforcement of the remaining dental structure74 and the public’s concern about mercury48 . Composite resins have been introduced into the field of conservative dentistry to minimise the drawbacks of the acrylic resins that replaced silicate cements in the 1940s. In direct composite technique, following cavity preparation the surface is etched ,bonding agent is applied ,
2
composite restoration is built up in increments or bulk and cured thus restoring the tooth morphology and function91.
Adhesive bonding to tooth structure has been an integral part of modern restorative dental practice that obviously improves the biomechanical and esthetic quality outcomes of restorations In 1955, Buonocore used orthophosphoric acid to improve the adhesion of acrylic resins to the surface of the enamel6. Since then development of composite resins for dental restorative purpose continues till date .
Despite great advances in the field of composite resin technology and extension of its applications in restorative dentistry, they still have disadvantages, including high wear rate, low strength, technique sensitivity and more importantly, polymerization shrinkage (PS) that gives rise to gap formation at the restorative material‒cavity wall interface, leading to microleakage due to the internal and interfacial stresses it creates.
The most essential factors determining preservation of restoration placed in a cavity are the marginal seal and absence of leakage 1,22. When marginal quality is not adequate, problems like leakage, recurrent caries and pulpal irritation may occur29.Marginal microleakage first defined by Kidd in 1976 is a process consisting in clinically undetectable penetration of bacteria, their metabolites, enzymes, toxins, ions, and other cariogenic factors between the filling and the cavity wall30.
3
Marginal integrity can be achieved by a combination of factors taken into consideration like the composite type used, the method of composite
placement , the adhesive system curing time ,cavity preparation etc.
Restoration placement techniques are widely recognized as a major factor in the modification of marginal seal. The two known placement techniques include bulk filled and incremental placement of composites. The incremental technique places 2mm increments of composite followed by curing it .While in bulk filled ,single increment of thicknesses ranging from 4 to 6 mm is placed and cured. 2-mm thick incremental composite placement is recommended usually due to the compromised light penetration through this material, which is especially true when using darker shades31. Thickness more than 2mm causes the surface composite to be cured and the material in depth may not polymerise17. Placing and light-curing composite in increments decreases the total PS, and stresses developed. If the force of polymerisation shrinkage exceeds the strength of the bonding agent and composite interface, then a marginal gap is formed.
Studies shows that to avoid the clinical consequences of polymerization shrinkage, incremental filling techniques are usually preferred over the bulk filling method to obtain effective marginal seal44,81. In some studies, better marginal quality with incremental methods of composite placement was observed60. However, other studies found no significant differences in marginal quality using different stratification methods13,27,28.
4
Although incremental technique may be important for adequate light penetration, its disadvantages are the possibility of trapping voids between layers and the time required to place the restoration. Bulk application technique is simpler and it makes the work quicker by reducing the number of clinical steps.
Bonding is another factor that determines the marginal integrity of composite resin. Recent dentin adhesives use one of two strategies to bond the resin to tooth and interact with the dentin smear layer: the Total etch (TE) technique or the self-etch, or SE, technique77. TE materials use 30 to 40 percent phosphoric acid to etch dentin and enamel before the clinician applies the adhesive to the preparation. Etching dentin removes the smear layer and opens up the dentinal tubules. SE do not require a separate acid-etch step, and do not remove the smear layer. They are composed of aqueous mixtures of acidic functional monomers, generally phosphoric acid esters, with a pH relatively higher than that of phosphoric acid etching gels.
With total-etch systems, phosphoric acid etchants can cause over- conditioning of the dentin surface (organic [collagen] and inorganic [hydroxyapatite] components), collapsing the collagen fibers with absolute demineralization of the dentin substrate. Dentinal tubules are also denatured and funnelled, increasing the flow of dentinal fluids with possible post- treatment sensitivity14.SE systems facilitate complete infiltration and penetration of the resin monomers into the collagen network of demineralized
5
dentin, enhancing marginal integrity, and reducing or eliminating patient symptom. Study by Perdigão and others (2003) concluded that SE adhesive systems did not differ from TE systems in restoration sensitivity and marginal discoloration.
Various in vitro tests of marginal adaptation have been widely used to predict the in vivo quality of restorations, but reports are inconsistent regarding their clinical relevance. These tests include dye penetration and microscopic marginal and interfacial analysis. While low or moderate correlation was found between scanning electron microscopic (SEM) marginal analysis and clinical findings, no available systematic correlation exists between dye tracing and clinical findings of hypersensitivity, marginal discoloration, caries at restorations margins, and retention.
With this background, the present marginal integrity of Bulk (Tetric N Ceram Bulk Fill.) vs Incremental Fill (Tetric Ceram HB Incremental) Class II composite restorations using Total Etch (Tetric N-Bond Total Etch) and Self Etch (Tetric N Bond Universal) bonding systems using Scanning Electron Microscopy Study.The null hypothesis tested was that there would be no differences in marginal adaptation in cavities restored with Bulk and Incremental composites using Self Etch or Total Etch bond technique.
Aim and Objectives
6
AIM AND OBJECTIVES
AIM:
The aim of this in vitro study is to evaluate the marginal integrity of Bulk (4mm placement)vs Inceremental Fill (2mm placement ) of Class II composite restorations using Total Etch and Self Etch bonding systems and to analyse it using Scanning Electron Microscopy after thermocycling each tooth samples. “
OBJECTIVES:
To analyse the marginal integrity of Composites using two different placement techniques - Incremental and Bulk Fill.
To evaluate the effect of two different types of Bonding Agents (Self etch and Total etch) used in the Composite resin - Tooth interface.
Compare the marginal integrity when each bonding agents are applied with the different Composite resin Placement techniques and evaluate whether a perfect margin is formed .
To evaluate whether placement of restoration margin on enamel or non enamel tooth structure affects the marginal integrity.
Review of Literature
7
REVIEW OF LITERATURE
Asmussen Erik et al (1974)4 assessed the effect of temperature changes on adaption of resin fillings. Fillings made in extracted human teeth were studied.
After closure of the initial gaps by water absorption expansion the fillings were polished and examined microscopically under water. Marginal gaps between filling and tooth were measured between 37 and 2°C. The effect of a rise in temperature was investigated by heating the fillings to O or 60°C, with subsequent measurement of gap size at 2°C. He found that the fillings could be cooled through a certain temperature range without marginal gaps being formed.
They concluded that heating to 60°C increased the gap size at 2°C only in unfilled resins
Goldman et al(1983)37 assessed polymerization shrinkage of resin based restorative materials. The values obtained for the polymerization shrinkages ranged from 1.67 to 5.68 per cent with most materials being in the 2 to 3 per cent range and the overall average result being 2.81 per cent. It was observed that powder‐liquid systems seemed to have the highest shrinkage and light‐activated materials the least with the paste‐paste materials having intermediate results. An experiment carried out to examine the effect of voids incorporated upon mixing
8
showed that increased void content caused a greater shrinkage of material per unit mass.
Donly KJ et al (1986)26 evaluated posterior composite polymerization shrinkage in primary teeth and a comparison of three techniques were done.
Mesio-occluso distal preparations were placed in primary teeth, followed by posterior composite resin restoration placement, using 3 different application techniques (technique I--placement and polymerization in 1 complete unit;
technique II--placement and polymerization in gingivo-occlusal increments; and technique III--placement and polymerization in buccolingual increments). A precision strain gage was attached to the buccal surface of each tooth, balanced at O, and after each increment was polymerized, the strain appearing on the strain gage indicator was recorded. Each tooth was restored using all 3 techniques.
Results demonstrated the mean microstrain units to be 60.3 for technique I, 46.5 for technique II, and 38.5 for technique III. Scheffe’s test indicated that the buccolingual incremental polymerization produced a statistically significant lower amount of strain on the tooth than polymerizing the restoration as 1 complete unit (P < 0.05).
Mandras RS et al(1991)52 evaluated the effects of thermal and occlusal stresses on the microleakage of Scotchbond 2 dentinal bonding system. The microleakage of the Scotchbond 2 Dentinal Bonding System was evaluated under
9
various experimental conditions. In this in vitro study, Class V restorations involving both enamel and cementum were placed on the buccal surfaces of 54 extracted human permanent canines and on the buccal and lingual surfaces of eight extracted human permanent mandibular molars. The canines were divided into three groups, each undergoing different conditions of thermocycling in 0.5%
basic fuchsin or distilled water and storage time in the dye. The molars were subjected to an occlusal load of 8 MPa for 66,000 times prior to being thermocycled. They found that there were no significant differences in microleakage of the restorations placed in the canine teeth; however, microleakage in the group of molars subjected to occlusal stresses was significantly increased.
Rigsby DF et al(1992)72 evaluated the effect of axial load and temperature on microleakage of resin restorations. The preparations were made at the mesial and distal aspects of 29 mandibular first and second molars. The enamel margins were beveled, acid etched, washed and dried. Kerr XR Bonding System was applied to the dentin and etched enamel and Herculite composite cured in two increments. The teeth were stored in saline for 7 days, thermocycled x500 in 0.5%
basic fuchsin between 8 degrees C and 50 degrees C (A); subjected to an occlusal load of 34 MPa in the dye without thermocycling (B); or followed by thermocycling (C). The leakage was scored from 0 to 4 at both the enamel and cementum aspects of the restorations. Result revealed that the microleakage of
10
the mesial restorations was significantly greater at the cementum aspects of the restorations subjected to both temperature and occlusal loading when compared to the restorations subjected to temperature cycling or load cycling only. The microstrain in eight of the 10 restorations was significantly greater at the cementum aspects of the restorations than at the enamel aspects.
Suliman AH et al (1994)77 evaluated polymerization shrinkage of composite resins comparing with tooth deformation. Polymerization shrinkage of two posterior composite resin restorative materials was measured by dilatometry.
The results were compared with a decrease in cavity width of MOD preparations in extracted premolars restored with the composite resins. A highly filled hybrid composite exhibited greater free shrinkage and cuspal deformation than a hybrid composite with a lower filler content. Deformation of the cusps was less than the unrestricted shrinkage of the composite resins. Hydrated teeth exhibited less deformation than dehydrated teeth because of polymerization shrinkage. Greater cuspal deformations were measured with the microscopic technique than with interferometry because of differences in experimental design.
Groten M et al (1997)38 evaluated marginal fit consistency of copy- milled all ceramic crowns during fabrication by light- and scanning electron- microscopic analysis . A master steel die of an upper middle incisor with a shoulder preparation and a rounded inner line angle was used. Impressions were
11
taken to produce 10 working stone dies. One crown per working die was manufactured. The evaluation of the external marginal gap was performed on the master steel die by using a light microscope and a computerized video image analysis system after copy milling (A), glass infiltration (B), and veneering (C).
Approximately 3900 readings were taken. Therefore, it is concluded that the manufacturing steps after copy milling have no obvious influence on the external marginal gap width. Scanning electron microscopic data seem to confirm the light-microscopic results. Hence, we expect that the Celay In-Ceram method yields a clinically acceptable marginal fit.
Prati C et al (1999)67 assessed effect of air, dentin and resin-based composite thickness on light intensity reduction. Two different light-units were used in the study. Light intensity was measured using a curing radiometer.There was an exponential decrease in light intensity with distance. The light-intensity value at a specific distance from the tip during passage through a specific dental material was calculated. Both composite and dentin caused a dramatic reduction in light intensity rate, e.g. 2.0 mm of composite are sufficient to reduce the light- intensity to 6% of its initial value.
Kanemura N et al (1999)43 evaluated tensile bond strength to and SEM evaluation of ground and intact enamel surfaces. One-Step (OS, Bisco), Single Bond (SB, 3M), Clearfil Liner Bond II (LBII, Kuraray), and Tokuso Mac Bond II
12
(MBII, Tokuso) were evaluated for their ability to bond to enamel. There was no significant difference in bond strengths between the materials when they were applied to ground enamel surfaces (p > 0.05). However, the bond strengths of the self-etching systems, LBII and MBII, had significantly lower bond strengths to intact enamel than the bonding systems OS and SB using phosphoric acid etching (p < 0.05). FE-SEM revealed that the etching pattern of self- etching primers was not deep enough to obtain good penetration of bonding resin when applied to intact enamel surfaces. They concluded that phosphoric acid etching produced good resin adhesion to ground and intact enamel. The self- etching/self-priming systems also produced good adhesion to ground enamel, but had lower bond strengths to intact enamel.
De Munck J et al (2003)25 evaluated four-year water degradation of total- etch adhesives bonded to dentin.The micro-tensile bond strength (microTBS) to dentin of 2 three-step total-etch adhesives was compared with that of 2 two-step total-etch adhesives after 4 years of storage in water. Quantitative and qualitative failure analyses were conducted correlating Fe-SEM and TEM. Results revealed that indirect exposure to water did not significantly reduce the microTBS of any adhesive, while direct exposure resulted in a significantly reduced microTBS of both two-step adhesives. It is concluded that resin bonded to enamel protected
13
the resin-dentin bond against degradation, while direct exposure to water for 4 years affected bonds produced by two-step total-etch adhesives.
Van Meerbeek B et al (2003)83 assessed microtensile bond strengths of an etch & rinse and self-etch adhesive to enamel and dentin as a function of surface treatment. An etch&rinse adhesive (OptiBond FL, Kerr) applied with and without prior acid-etching and a self-etch adhesive (Clearfil SE, Kuraray) were employed to bond the restorative composite (Z100, 3M ESPE) to the diversely prepared enamel and dentin surfaces.. The results indicated that the manner of preparation of enamel and dentin prior to bonding procedures significantly influenced the bonding effectiveness of both the etch&rinse and the self-etchadhesive. They concluded that bonding to diamond-sono abraded and air-abraded enamel and dentin was, in general, not different from bonding to conventional diamond-bur prepared surfaces, whereas, bonding to Er:YAG- irradiated enamel and dentin surfaces in general resulted in a significantly lower bonding effectiveness compared to bonding to diamond-bur prepared surfaces.
Perdigao J et al (2003)63 assessed bonding characteristics of self-etching adhesives to intact versus prepared enamel. Single Bond, the total-etch adhesive, resulted in statistically higher microtensile bond strength than any of the other adhesives regardless of the enamel preparation .All the self-etching adhesives resulted in higher microtensile bond strength when enamel was roughened than
14
when enamel was left unprepared. One-Up Bond F did not bond to unprepared enamel. The study concluded that commercial self-etching adhesives performed better on prepared enamel than on unprepared enamel. The field-emission scanning electron microscope revealed a deep interprismatic etching pattern for the total-etch adhesive, whereas the self-etching systems resulted in an etching pattern ranging from absent to moderate.
Brunthaler A et al (2003)14 evaluated longevity of direct resin composite restorations in posterior teeth. The data were evaluated statistically in order to assess the role of materials, study design, and personnel on failure rates.
Observation periods varied from 1 to 17 years, and failure rates ranged between 0% and 45%. A linear correlation between failure rate and observation period was found .Thirteen of 24 studies were terminated after 3 years, while seven studies continued for more than 10 years, indicating that favourable results for composite materials are frequently based on short-term results, despite higher dropout rates in longer studies.
Quintas AF et al (2004)69 evaluated vertical marginal discrepancy of ceramic copings with different ceramic materials, finish lines, and luting agents.
Two stainless steel molars were prepared for complete crowns with 2 different finish lines (heavy chamfer and rounded shoulder); each molar was duplicated to fabricate 90 copingsIt was shown that Procera copings presented the lowest mean
15
values ( P <.05) of vertical marginal discrepancy before and after cementation (25/44 microm) when compared to Empress 2 (68/110 microm) and InCeram Alumina copings (57/117 microm), regardless of any combinations among all finish lines and luting agents tested. Considering each factor separately, the ceramic manufacturing technique appeared to be the most important factor tested for the definitive vertical discrepancy of all-ceramic copings, with lower mean values for Procera copings.
Manhart J et al (2004)54 reviewed the clinical survival of direct and indirect restorations in posterior teeth of the permanent dentition. It provided a survey on the longevity of restorations in stress- bearing posterior cavities and assessed the possible reasons for clinical failure. It was found that mean (SD) annual failure rates in posterior stress-bearing cavities are: 3.0% (1.9) for amalgam restorations, 2.2% (2.0) for direct composites, 3.6%
(4.2) for direct composites with inserts, 1.1% (1.2) for compomer restorations, 7.2% (5.6) for regular glass ionomer restorations, 7.1% (2.8) for tunnel glass ionomers, 6.0% (4.6) for ART glass ionomers, 2.9% (2.6) for composite inlays, 1.9% (1.8) for ceramic restorations, 1.7% (1.6) for CAD/CAM ceramic restorations and 1.4% (1.4) for cast gold inlays and onlays. He concluded that indirect restorations exhibited a significantly lower mean annual failure rate than direct techniques (p=0.0031).
16
Braga RR et al (2004) investigated alternatives in polymerization contraction stress management. Polymerization contraction stress of dental composites is often associated with marginal and interfacial failure of bonded restorations. The magnitude of the stress depends on the composite's composition (filler content and matrix composition) and its ability to flow before gelation, which is related to the cavity configuration and curing characteristics of the composite. He reviewed the variations found among studies regarding the contraction stress testing method, contraction stress values of current composites, and discussed the validity of contraction stress studies in relation to results from microleakage tests.
Cenci M et al (2005)18 did a study on Class II composite resin restorations with two polymerization techniques and relationship between microtensile bond strength and marginal leakage. Class II slot preparations were made in 40 non-carious human third molars and restored using Single Bond and P-60. Teeth were incrementally restored either with direct polymerization from occlusal surface or with indirect polymerization through translucent matrices and reflective wedges. It was concluded that bond strengths were higher in preparations with enamel margins than in preparations with dentin margins, when restored with indirect polymerization technique (p<0.05). No significant correlation was found between leakage and bond strength .
17
Owens BM et al (2005)60 evaluated the effect of insertion technique and adhesive system on microleakage of Class V resin composite restorations.
Standardized mixed Class Vcavities were prepared at the CEJ. A total- and a self- etching adhesive system were evaluated using either an incremental or single- step (bulk) insertion technique. The preparations were restored with Esthet*X micromatrix hybrid composite. The teeth were thermocycled 1000 cycles, immersed in 1% methylene blue dye for 24 h, and investigated and then sectioned longitudinally, with dye penetration (microleakage) examined .
Significance was exhibited between the group
(adhesive material/insertion technique) at the coronal and apical margins. At the coronal margin, the total-etch adhesive/ incremental insertion group exhibited significantly less leakage than the other groups, while at the apical margin, the total-etch adhesive/ incremental insertion group showed significantly less leakage than the self-etching adhesive /bulk insertion group. Significantly less leakage was found at the coronal margins compared to the apical margins of the material/technique groups.The use of a total-etch adhesive system and incremental insertion of composite significantly reduced microleakage at the coronal and apical margins of Class V composite restorations.
Peumans M et al (2005)65 evaluated clinical effectiveness of contemporary adhesives. Comparison of retention of class-V adhesive restorations
18
as a measure to determine clinical bonding effectiveness of adhesives revealed that glass-ionomers most effectively and durably bond to tooth tissue. Three-step etch-and-rinse adhesives and two-step self-etch adhesives showed a clinically reliable and predictably good clinical performance. The clinical effectiveness of two-step etch-and-rinse adhesives was less favourable, while an inefficient clinical performance was noted for the one-step self-etch adhesives.
Da Rosa Rodolpho PA et al (2006)23 did a study on clinical evaluation of posterior composite restorations: 17-year findings. Patients that received restorations in posterior teeth with P-50 (3M) or Herculite XR (Kerr) resin composites were selected . Dentine walls were covered with glass ionomer cement, and composites were placed . Results showed ninety-eight failures among the 282 restorations providing a crude estimate of 34.8% failures. He concluded that the survival rate was not significant for material but was significant between tooth , cavity type and size . The main failure cause was fracture of both composites. However, the probability of failure of resin composite restorations in molars, Class II, and large restorations is higher.
Duarte S Jr et al (2007)27 evaluated the influence of resin composite insertion technique in preparations with a high C-factor. Standardized Class 5 cavities were prepared in the lingual and buccal aspects of 30 third molars. The prepared teeth were randomly assigned to 3 groups: (1) oblique incremental
19
placement technique, (2) horizontal incremental placement technique, and (3) bulk insertion (single increment). The preparations were restored with a 1-bottle adhesive and microhybrid resin composite .Specimens were isolated with nail varnish and thermocycled . The specimens were immersed in an aqueous solution of 50 wt% silver nitrate for 24 hours, followed by 8 hours in a photo-developing solution and evaluated for microleakage using an ordinal scale of 0 to 4. The microleakage scores obtained from occlusal and gingival walls were analyzed with Wilcoxon and Kruskal-Wallis nonparametric tests. The horizontal incremental placement technique, the oblique incremental technique, and bulk insertion resulted in statistically similar enamel and dentin microleakage scores.Neither the incremental techniques nor the bulk placement technique were capable of eliminating the marginal microleakage in preparations with a high C- factor.
Asmussen E et al(2008)5 compared Class I and class II restorations of resin composite: An FE analysis of the influence of modulus of elasticity on stresses generated by occlusal loading. A cylindrical tooth was modelled in enamel and dentin and fitted with a Class I or a Class II restoration of resin composite. In one scenario the restoration was bonded to the tooth, in another the restoration was left nonbonded. The stresses decreased with increasing modulus of elasticity of the resin composite. In the nonbonded
20
scenario, the stresses were higher in the dentin and lower in the enamel than in the bonded cases, and the influence of the modulus of elasticity was less pronounced.
The marginal stresses in the restoration were below 6 MPa in the bonded scenario and below 3 MPa in the nonbonded scenario.Occlusal restorations of resin composite should have a high modulus of elasticity in order to reduce the risk of marginal deterioration.
Coelho-De-Souza FH et al (2008)19 evaluated fracture resistance and gap formation of MOD restorations along with the influence of restorative technique, bevel preparation and water storage. The study evaluated the effect of technique, use of a bevel and thermal cycling on the fracture resistance and gap formation of resin composite MOD restorations. Fracture resistance was measured on standard MOD cavities prepared in 100 upper premolars that were stored for 24 hours and 6 months with 1000 thermal cycles. Subgroups (n=10) were: beveled or non-beveled preparations and direct restorations and indirect restorations .Results showed that thermal cycling decreased fracture resistance in the majority of the groups.. Under SEM examination, no difference was observed among the groups after 24 hours .It was concluded that storage with thermal cycling decreased fracture resistance, bevels improved fracture resistance and, in general, indirect restorations were not superior to direct restorations.
21
Duarte S Jr et al (2008)28 evaluated the marginal adaptation of Class 2 adhesive restorations. Standardized Class 2 preparations were made in 60 caries- free extracted third molars and randomly assigned to 3 groups (n = 20): (1) oblique incremental insertion technique (control), (2) centripetal incremental insertion technique, and (3) bulk insertion. The teeth were restored with a total- etch adhesive and microhybrid composite resin. The specimens were isolated with nail varnish except for a 2-mm-wide area around the restoration and then thermocycled. The specimens were immersed in an aqueous solution of 50%
silver nitrate for 24 hours, followed by 8 hours of immersion in a photo- developing solution and subsequently evaluated for leakage. The microleakage scores (0 to 4) obtained from the occlusal and cervical walls were analyzed with median nonparametric tests (P < .05). All techniques attained statistically similar dentin microleakage scores (P = .15). The centripetal insertion technique displayed significantly less microleakage than the oblique technique at the enamel margins (P = .04).None of the techniques eliminated marginal microleakage in Class 2 preparations. However, in occlusal areas, the centripetal technique performed significantly better than the other techniques.
Yumei Niu et al (2009)87 assessed effect of layering techniques on the micro-tensile bond strenght to dentin in resin composite restorations. The results showed that there is a significant difference between the strength of the micro-
22
tensile bonds to the dentin of occlusal cavities depending on which of the four layering restorative techniques was used (P<0.01). SEM observation showed that failure patterns were most evidently interfacial cohesive failure.Layering techniques in resin composite restorations affected the micro- tensile bond strength between the resin compositeand the dentin. But the outcomes related to only Single Bond, as the same using other adhesives might have different outcomes.
Peumans M et al (2010)66 evaluated eight-year clinical evalution of a two-step self-etch adhesive with and without selective enamel etching. The recall rate at 8 years was 76%. Only two restorations, one of the C-SE non-etch group and one of the C-SE etch group, were clinically unacceptable due to loss of retention leading to a retention rate and a clinical success rate of 97% in both groups. At the enamel side, the presence of small marginal defects (C-SE non- etch: 86%; C-SE etch: 65%) and superficial marginal discoloration (C-SE non- etch: 11%; C-SE etch%) was more frequently noticed in the control group than in the experimental group. The difference, however, was only statistically significant for the presence of superficial marginal discoloration (McNemar, p=0.01). After 8 years of clinical functioning, the clinical effectiveness of Clearfil SE remained excellent, with selective acid-etching of the enamel cavity margins only having some minor positive effect on marginal integrity and absence of marginal discoloration at enamel.
23
Manhart J et al (2010)54 evaluated marginal adaptation of an etch-and- rinse adhesive with a new type of solvent in class II cavities after artificial aging . Standardized class II cavities were cut in 40 human molars with one proximal box limited within enamel and one proximal box extending into dentin. Teeth were assigned randomly to five groups (n = 8) and restored with incrementally placed composite restorations. After finishing and polishing, teeth were stored for 48 h in water at 37°C before subjected to artificial aging by thermal stress (5/55°C;
×2,000; 30 s) and mechanical loading (50 N; ×50,000). Marginal adaptation of the restorations was evaluated in a SEM (×200) using a replica technique. Statistical analysis was performed with nonparametric test methods (p < 0.05). The percentages of "perfect margin" after aging ranged from 95.9% to 99.6% in enamel and 85.9% to 96.0% in dentin. "Marginal opening" was observed between 0.1% to 2.6% in enamel and 2.6% to 11.8% in dentin. In enamel and dentin, both, G3 showed significantly more gap formation than G1 and G2. Comparing marginal adaptation to enamel and dentin within each group yielded only for G1 no significant differences. Tert-butanol-based XP Bond showed excellent marginal adaptation in both enamel and dentin.
Da Rosa Rodolpho PA et al (2011)24 did a 22-Year clinical evaluation of the performance of two posterior composite with different filler characteristics.
Patients with at least 2 posterior composite restorations placed , were selected.
61 patients presenting 362 restorations (121 Class I, 241 Class II) placed using a
24
closed sandwich technique were evaluated by 2 operators using the FDI criteria.
110 failures were detected. Results revealed that there was higher probability of failure in molars and for multi-surface restorations. Both evaluated composites showed good clinical performance over 22 years with 1.5% (midfilled) and 2.2%
(minifilled) annual failure rate. it was concluded that superior longevity for the higher filler loaded composite (midfilled) was observed in the second part of the observation period with constant annual failure rate between 10 years and 20 years, whereas the minifilled material showed an increase in annual failure rate between 10 years and 20 years, suggesting that physical properties of the composite may have some impact on restoration longevity.
Van Dijken JWet al (2011)81 evaluated clinical performance of a hybrid resin composite with and without an intermediate layer of flowable resin composite on 7-year evaluation. A prediction of the caries risk showed that 18 of the evaluated 46 patients were considered as high risk patients. Seventeen failures were observed, 8 in restorations with and 9 in restorations without an intermediate layer of flowable resin composite, resulting in a 14.9% failure rate after 7 years. The main reasons for failure were: fracture of resin composite, secondary caries and cusp fracture . No statistical difference was seen between restorations restored with and without flowable layer. The hybrid resin composite showed a good clinical performance during the 7-year evaluation. The
25
use of flowable resincomposite as an intermediate layer did not result in improved effectiveness of the Class II restorations.
Campodonico CE et al (2011)17 evaluated cuspal deflection and depth of cure in resin-based composite restorations filled by using bulk, incremental and transtooth-illumination techniques. The authors found no difference in cuspal deflection between filling techniques within the same materials .They found no difference in hardness for X-tra fil at any depth with either the bulk or the incremental technique Filtek Supreme Plus had higher hardness values at depths of less than 1.5 mm with the bulk/transtooth-illumination technique, whereas the bulk technique resulted in lower hardness values at depths of 2.0 mm and below (P < .05). Cuspal deflection was not affected by filling techniques. X- tra fil cured up to a depth of at least 3.5 mm; Filtek Supreme Plus had lower curing values below a depth of 2 mm. The transtooth-illumination technique improved curing depth for restorations placed in bulk.
Kramer N et al (2011)44 compared nanohybrid vs. fine hybrid composite in extended Class II cavities after six years. Success rate was 100% after six years of clinical service, while the drop out of patients was 0%.
Neither materials nor localization of the restoration had a significant influence on clinical outcome in any criterion after six years. Marginal quality revealed a major portion of overhangs having been clearly reduced after the one year recall
26
(baseline: 44%; 6 months: 65%; 1 year: 47%; 2 years: 6%; 4 years: 4%; and 6 years: 3%). Beyond the 1 year recall, negative step formations significantly increased due to wear (p<0.05), having been more pronounced in molars than in premolars .Tooth integrity significantly deteriorated due to enamel cracks, which increased over time (p<0.05). Enamel chippings and cracks were significantly more frequent in molars than in premolars Restoration integrity over time mainly suffered surface roughness and wear .Both materials performed satisfactorily over the 6-year observation period. Due to the extension of the restorations, wear was clearly visible after six years of clinical service with 91% bravo ratings.
R Nagpal et al (2011)70 evaluated In vitro bonding effectiveness of self- etch adhesives with different application techniques: a microleakage and scanning electron microscopic study. At enamel margins for both the adhesives tested, groups 2 and 4 showed significantly lesser leakage than groups 1 and 3. At dentin margins, groups 3 and 4 depicted significantly reduced leakage than groups 1 and 2 for Xeno III. SEM observation of the resin-dentin interfaces revealed generalized gap and poor resin tag formation in both the adhesives. Xeno III showed better interfacial adaptation when additional hydrophobic resin coat was applied.In enamel, prior phosphoric acid etching reduces microleakage of self- etch adhesives, while in dentin, hydrophobic resin coating over one-step self-etch adhesives decreases the microleakage.
27
Roggendorf MJ et al (2011)73 evaluated marginal quality of flowable 4- mm base vs. conventionally layered resin composite. In enamel, high percentages of gap-free margins were initially identified for all adhesives. After TML, etch- and-rinse adhesives performed better than self-etch adhesives (p<0.05). Also in dentine, initially high percentages of gap-free margins were found for all adhesives. After TML, etch-and-rinse adhesives again performed better than self- etch adhesives for both marginal and internal adaptation (p<0.05). The presence of a 4mm layer of SDR had no negative influence on results in any group (p>0.05).SDR as 4mm bulk fill dentine replacement showed an good performance with the material combinations under investigation
El-Safty S et al (2012)31 evaluated creep deformation of restorative resin- composites intended for bulk-fill placement. The maximum creep strain % ranged from 0.72% up to 1.55% for Group A and the range for Group B increased from 0.79% up to 1.80% due to water sorption. Also, the permanent set ranged from 0.14% up to 0.47% for Group A and from 0.20% up to 0.59% for Group B.
Dependent on the material and storage condition, the percentage of creep strain recovery ranged between 64% and 81%. Increased filler loading in the bulk-fill materials decreased the creep strain magnitude.Creep deformation of all studied resin-composites increased with wet storage. The "bulk-fill" composites exhibited
28
an acceptable creep deformation and within the range exhibited by other resin- composites.
A. Moorthy et al (2012)2 evaluated Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials. The mean total cuspal deflection for the oblique incremental restoration technique was 11.26 (2.56) μm (Group A) and 4.63 (1.19) μm (Group B) and 4.73 (0.99) μm (Group C) for the bulk-fill flowable RBC bases. A significant increase in the mean total cuspal deflection for the incrementally filled GrandioSO compared with the SDR (P=0.007) and x-tra base (P=0.005) restored teeth was evident. No significant difference in the cervical microleakage scores was recorded between groups AC (P>0.05).The bulk-fill flowable RBC bases significantly reduced cuspal deflection compared with a conventional RBC restored in an oblique incremental filling technique with no associated change in cervical microleakage recorded.
Heintze SD et al (2012)41 assessed Clinical relevance of tests on bond strength, microleakage and marginal adaptation. Dental adhesive systems should provide a variety of capabilities, such as bonding of artificial materials to dentin and enamel, sealing of dentinal tubules, reduction of post-operative sensitivity and marginal sealing to reduce marginal staining and caries.Many of these tests are not systematically validated and show therefore different results between different research institutes. The correlation with clinical phenomena has only partly been
29
established to date. There is some evidence, that macrotensile and microtensile bond strength tests correlate better with clinical retention of cervical restorations than macroshear and microshear bond tests but only if data from different test institutes are pooled. Also there is some evidence that marginal adaptation has a moderate correlation in cervical restorations with clinical retention and in Class II restorations (proximal enamel) with clinical marginal staining. There is moderate evidence that microleakage tests with dye penetration does not correlate with any of the clinical parameters (post-operative hypersensitivity, retention, marginal staining).
Le prince JG et al (2014)47 evaluated physico-mechanical characteristics of commercially available bulk-fill composites. The reduction of time and improvement of convenience associated with bulk-fill materials is a clear advantage of this particular material class. However, a compromise with mechanical properties compared with more conventional commercially-available nano-hybrid materials was demonstrated by the present work. Given the lower mechanical properties of most bulk-fill materials compared to a highly filled nano-hybrid composite, their use for restorations under high occlusal load is subject to caution. Further, the swelling behaviour of some of the bulk- fill materials may be a reason for concern, which highlights the critical requirement for a veneering material, not only to improve aesthetic quality of the translucent material, but to reduce the impact of degradation.
Materials and Methods
30
MATERIALS AND METHODS
Armamentarium
(FIGURE 4,2): Tooth coloured self cure acrylic resin powder and liquid monomer.(DPI-RR Cold Cure)(FIGURE2)
Round tungsten carbide bur(BR-31,BR-41(MAN, ,Inc, Japan I))
Flat end straight fissure bur.(SF-11,MANI, ,Inc, Japan)
Tapered round end polishing bur(TR-13 EF)(MANI).
Metal ruler and pencil
High speed Airotor handpiece (NSK)
Micromotor handpiece and unit (SPRINT) (ORO gold)
Disposable micro applicators
Graduated periodontal probe (Dentsply)
Universal matrix retainer (Tofflemire Retainer-Universal, Dentsply).
Light curing unit(3M ESPE).
Bonding Agent Self Etch (Tetric N Bond Universal - Ivoclar Vivadent)
Bonding agent (Tetric N-Bond Total Etch -Ivoclar Vivadent ).
Incremental Fill Composite Resin(Tetric N- Ceram- Ivoclar Vivadent)
Bulk fill Composite Resin (Tetric N Ceram Bulk Fill- IvoclarVivadent)
Plastic instrument(GDC)
Surgical scalpel blade no. 15 (GLASSVAN).
Sof- flex discs(3M ESPE)
31
Thermocycling machine
Scanning Electron Microscope along with gold sputtering machine (SEM - S – 3400 N – HITACHI)
A total of 30 human maxillary premolars(FIGURE 1)(n= 12) that showed no caries, cracks, or developmental defects were used in this study.
Teeth were extracted for orthodontic reasons, and their use in research was approved by the ethics committee.
Each premolar was wrapped coronally with wax 2 mm below the cemento-enamel junction (CEJ). The teeth were then embedded vertically in self-curing acrylic blocks to a level 2 mm below the CEJ (FIGURE 3).
On each premolar, class II mesial and distal box only cavities were prepared with butt joint margins and 4-mm buccolingual dimensions(FIGURE 5). Access was gained through enamel with a round tungsten carbide bur(MANI), and the preparation was completed with a cylindrical diamond abrasive with a flat end (brand); new burs and abrasives were used . The preparations were performed using high-speed ranges under abundant air- water coolant. The buccolingual dimensions were measured using a metal ruler , the outline was marked with a pencil, and an axial depth of 1.5 mm was measured at the gingival floor using a graduated periodontal probe (Dentsply).
In each tooth, the proximal gingival margin was placed 1 mm above the CEJ on one side and 1 mm below it on the other side of the tooth.
32
Consequently, two restorations were inserted in each premolar using the same bonding agent, restorative material, and technique, the only difference being the location of the cervical margin.
The 30 teeth were initially divided into two groups of 30 each(2 restoration in one teeth) based on the gingival floor position as 1mm above CEJ and 1 mm below CEJ. Then each of these 2 groups of 30 specimens were randomly divided into 2 study groups - Incremental technique and Bulk Fill composite placement technique and then subdivided according to the bonding agent used as Self Etch and Total Etch technique and a control group (n=12).
During the bonding procedure and subsequent application and light curing of the restorative materials, a metallic matrix band attached to a universal matrix retainer (Tofflemire Retainer-Universal, Dentsply) ,was used.
It was applied to each premolar to maintain the adaptation of the band to the cavity margins. For maximum and curing conversion curing light(3M ESPE) (FIGURE 12) was used with a wavelength of 430-480 nm . All restorative materials were light cured from an occlusal direction.
Each increment of restorative material, conventionally layered or bulk placed, was light cured for 20 seconds, while adhesives were light cured for 10 seconds before composite application(FIGURE 11), which is in agreement with the manufacturer’s instructions.
Thereafter, resin composite restorations were inserted according to the assigned study groups.
33
GROUP 1: Bonding Agent Tetric N Bond Universal(FIGURE 7) and Tetric Ceram HB Incremental resin composite(FIGURE 10) .
After preparation, cavity was water washed and air dried; thick layers of Tetric N-Bond universal was applied to the enamel and dentin surfaces of the preparation and brushed in for 30 s(FIGURE 9). Excess bonding agent was air thinned and light cured for 10 s.
The resin Tetric Ceram HB Incremental resin composite was inserted in horizontal increments of 2 mm each by using a metallic plastic instrument (stainless steel, GDC) and light cured for 20 seconds until complete filling of the cavity. The plastic instrument was used to provide the proper anatomical form before light curing the most superficial increment.
GROUP 2: Bonding Agent Tetric N Bond Universal and Tetric N Ceram Bulk Fill (FIGURE 10).
Bonding was done similar to group 1 with Bonding Agent Tetric N Bond Universal.
A 4-mm-thick increment of Tetric N Ceram Bulk Fill was inserted into the cavity using a plastic instrument (GDC) and light cured for 20 seconds, followed by a second increment to completely fill the cavity, contour, and light cure it
GROUP 3: Bonding agent Tetric N-Bond (total etch)(FIGURE 6) and Tetric Ceram HB Incremental resin composite .
34
After preparation, cavity was water washed and air dried, etched for 15 s (FIGURE 8), and washed with vigorous water spray, and excess moisture was removed.
Thick layers of bonding agent Tetric N-Bond (total etch) were applied to the enamel and dentin using an application brush, air thinned, and light cured for 10s.
The resin Tetric Ceram HB Incremental resin composite was inserted in horizontal increments of 2 mm each by using a metallic plastic instrument (stainless steel, GDC) and light cured for 20 seconds until complete filling of the cavity. The plastic instrument was used to provide the proper anatomical form before light curing the most superficial increment.
GROUP 4: Bonding agent Tetric N-Bond (total etch) and Tetric N Ceram Bulk Fill.
After preparation, cavity was water washed and air dried, etched for 15 s, and washed with vigorous water spray, and excess moisture was removed.
Thick layers of bonding agent Tetric N-Bond (total etch) were applied to the enamel and dentin using an application brush, air thinned, and light cured for 10s.
A 4-mm-thick increment of Tetric N Ceram Bulk Fill was inserted into the cavity using a plastic instrument (GDC) and light cured for 20
35
seconds, followed by a second increment to completely fill the cavity, contour, and light cure it.
GROUP 5 : Control group . Tetric N Ceram Bulk Fill.
A 4-mm-thick increment of Tetric N Ceram Bulk Fill was inserted into the cavity using a plastic instrument (GDC) and light cured for 20 seconds, followed by a second increment to completely fill the cavity, contour, and light cure it.
After completion of the restorations, gross marginal overhangs were removed by a surgical scalpel blade (no. 15). Afterward, restorations were finished and polished using Sof- lex discs (brand), starting with a courser grit descending down to a superfine grit. The discs, mounted on the Sof- Lex finishing and polishing disc mandrel, were used in a slow-speed range under abundant air-water spray.
Following finishing and polishing, the margins of the restorations were carefully inspected for complete removal of overhangs.
All samples were artificially aged by thermal cycling. Specimens were thermocycled for10,000 cycles in water baths between 5ºC and 55º C at a dwell time of 30 seconds in each bath and a transfer time of 15 seconds between baths (Thermocycling machining)(FIGURE 13). After drying the samples, all the samples are now analysed using Scanning electron microscope (FIGURE 16 ) with magnifications 200x and up to 500x when required. All
36
samples of the five groups underwent gold sputtering (FIGURE 15 ) in the gold sputtering machine (FIGURE 14) for about 15 seconds to make the samples more electro-conductive underneath the SEM.Then they were cement glued at their bases on a metallic holder and examined under SEM at 200x and then the magnification was then increased to 500x (FIGURE 16) and the material - tooth interface were recorded.
The quality of the marginal seal at the gingival margins of restorations was categorized into three scores:
1. Perfect margin: The margin appears with smooth and uninterrupted tooth-restoration continuity.(FIGURE 17,18)
2. Marginal gap: A distinct gap exists at the tooth-restoration margin.(FIGURE 19,20)
3. Nonassessable margin: Does not fit the previous two categories The quality of marginal seal between the tooth and restoration were analysed in each of the 5 groups as above perfect margin at 200x (FIGURE 17) and 500x (FIGURE 18) ; gap in margin at 200x(FIGURE 19) AND 500x(FIGURE 20).The results for each groups were recorded, tabulated and statistically analysed.
37
FLOWCHART
A TOTAL OF 30 HUMAN MAXILLARY PREMOLARS WERE USED.
EACH PREMOLAR WAS WRAPPED CORONALLY WITH WAX 2 MM BELOW THE CEMENTO-ENAMEL JUNCTION AND EMBEDDED VERTICALLY IN SELF-CURING
ACRYLIC BLOCKS TO A LEVEL 2 mm BELOW THE CEJ .
CLASS II MESIAL AND DISTAL BOX ONLY CAVITIES WERE PREPARED WITH 4-mm BUCCOLINGUAL DIMENSIONS AND THE PROXIMAL GINGIVAL MARGIN PLACED 1 mm ABOVE THE CEJ ON ONE SIDE AND 1 MM BELOW IT ON THE OTHER SIDE.
TEETH WERE DIVIDED INTO 2 MAIN STUDY GROUPS AND SUBDIVIDED INTO 2 GROUPS EACH AND A CONTROL GROUP
38
RESTORATIONS WERE FINISHED AND POLISHED USING SOF- LEX DISCS, STARTING WITH A COURSER GRIT DESCENDING DOWN TO A SUPERFINE
GRIT.
RESTORATIVE PROCEDURE : APPLICATION OF BONDING AGENT ,CURING AND RESTORING THE CAVITY WITH LIGHT CURE COMPOSITE
ALL SAMPLES WERE ARTIFICIALLY AGED BY THERMAL CYCLING.
MARGINAL INTEGRITY OF SAMPLES WERE EVALUATED WITH SEM.
DATA ANALYSIS AND INTERPRETATION
39 GROUP 1
SELF ETCH BONDING TECHNIQUE
(n=12)
GROUP 3 TOTAL ETCH BONDING TECHNIQUE (n=12)
GROUP 2 SELF ETCH
BONDING TECHNIQUE
(n=12)
GROUP 4 TOTAL ETCH
BONDING TECHNIQUE
(n=12)
BULK FILL LIGHT CURE COMPOSITE INCREMENTAL LIGHT CURE
COMPOSITE
(EACH TOOTH HAS 2 CAVITIES : MESIAL AND DISTAL.
THUS 30 TEETH = 60 RESTORATIONS IN TOTAL)
MARGIN LOCATION
ENAMEL (n=30)
CEMENTUM (n=30)
BASED ON RESTORATION AND BONDING SYSTEM
GROUP 5 CONTROL
GROUP (n=12)
40 BONDING
SYSTEM
USED WITH BONDING PROCEDURE
Tetric N Bond Universal
Tetric N Ceram Bulk Fill
Tetric N Ceram
After preparation, cavity was water washed and air dried, etched for 15 s, and washed with vigorous water spray, and excess moisture was removed.
Thick layers of bonding agent Tetric N- Bond (total etch) were applied to the enamel and dentin using an application brush for 30s, air thinned, and light cured for 10s.
Tetric N- Bond (total etch)
Tetric N Ceram Bulk Fill
Tetric N Ceram
After preparation, cavity was water washed and air dried, etched for 15 s, and washed with vigorous water spray, and excess moisture was removed.
Thick layers of bonding agent Tetric N- Bond (total etch) were applied to the enamel and dentin using an application brush, air thinned, and light cured for 10s.
SUMMARY OF THE BONDING PROCEDURE
41
SUMMARY OF THE RESTORATIVE TECHNIQUE
RESTORATION SYSTEM
BONDING AGENT USED
RESTORATIVE PROCEDURE
Tetric N Ceram Bulk Fill
Tetric N- Bond (total etch)
Tetric N Bond Universal
A 4-mm-thick increment of Tetric N Ceram Bulk Fill was inserted into the cavity using a plastic instrument (GDC) and light cured for 20 seconds, followed by a second increment to completely fill the cavity, contour, and light cure it
Tetric N Ceram
Tetric N- Bond (total etch)
Tetric N Bond Universal
The resin Tetric Ceram HB
Incremental resin composite was
inserted in horizontal increments of 2
mm each by using a metallic plastic
instrument (stainless steel, GDC) and
light cured for 20 seconds until
complete filling of the cavity. The
plastic instrument was used to provide
the proper anatomical form before
light curing the most superficial
increment.
Figures
FIGURES
FIGURE 1: TEETH SPECIMENS
FIGURE 2: MATERIALS USED FOR MOUNTING AND EMBEDDING SAMPLES
FIGURE 3: EMBEDDED SAMPLE
FIGURE 4: ARMAMENTARIUM
FIGURE 5:CAVITY PREPARATION
FIGURE 6:ETCHANT AND TETRIC N BOND(TOTAL ETCH)
FIGURE 7:TETRIC N BOND UNIVERSAL(SELF ETCH)
FIGURE 8:APPLICATION OF ETCHANT
FIGURE 9:APPLICATION OF BONDING AGENT
FIGURE 10:TETRIC N CERAM AND TETRIC N - CERAM BULK FILL
FIGURE 11:RESTORING WITH RESIN COMPOSITE
FIGURE 12:LIGHT CURING
FIGURE 13:THERMOCYCLING UNIT
FIGURE 14: GOLD SPUTTERING MACHINE
FIGURE 15: GOLD SPUTTERED SPECIMENS
FIGURE 16: SCANNING ELECTRON MICROSCOPE
FIGURE 17: SEM IMAGES OF THE SPECIMEN SHOWING A PERFECT MARGIN AT 200X
FIGURE 18: SEM IMAGES OF THE SPECIMEN SHOWING A PERFECT MARGIN AT 500X
FIGURE 19: SEM IMAGES OF THE SPECIMEN SHOWING A MARGINAL GAP AT 200X
FIGURE 20: SEM IMAGES OF THE SPECIMEN SHOWING A MARGINAL GAP 500X
