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Theses & Dissertations Boston University Theses & Dissertations
2016
Evaluation of fluoride release and
mechanical properties of different
glass ionomers
https://hdl.handle.net/2144/18310
BOSTON UNIVERSITY
HENRY M. GOLDMAN SCHOOL OF DENTAL MEDICINE
DISSERTATION
EVALUATION OF FLUORIDE RELEASE AND
MECHANICAL PROPERTIES OF DIFFERENT GLASS
IONOMERS
by
SARAH AHMED BAHAMMAM
BDS, KING ABDULAZIZ UNIVERSITY FACULTY OF DENTISTRY, 2006
MSD, BOSTON UNIVERSITY, 2011
C.A.G.S, BOSTON UNIVERSITY, 2014
Submitted in partial fulfillment of the requirements for the degree of
Doctor of Science in Dentistry
In the Department of Pediatric Dentistry
2016
Approved by
First Reader
Signature: ……….
Date: ……….
Dr. Dan Nathanson, D.M.D., M.S.D. Professor and Chairman,
Department of Restorative Sciences and Biomaterials
Second Reader
Signature: ………
Date: ……….
Dr. Yuwei Fan, MSc., PhD. Research Assistant Professor,
Department of Restorative Sciences and Biomaterials
Third Reader
Signature……….
Date……….
Dr. Athanasios Zavras, DMD, DDS, MS, DrMedSc Professor and
CHAIRMAN’S APPROVAL
Signature: ………
Date: ………
Dr. Dan Nathanson, D.M.D., M.S.D. Professor and Chairman,
iv
EVALUATION OF FLUORIDE RELEASE AND MECHANICAL PROPERTIES OF DIFFERENT GLASS IONOMERS
SARAH AHMED BAHAMMAM
Boston University, Henry M. Goldman School of Dental Medicine, 2016
Major Professor: Dan Nathanson, D.M.D., M.S.D. Professor and Chairman, Department of Restorative Sciences and Biomaterials
ABSTRACT
Objective: To assess the fluoride release and mechanical properties of four restorative glass ionomer cements (GIC) and to determine the correlation between the mechanical properties and fluoride release.
Materials and methods: Four restorative glass ionomers were studied: ChemFil ROCK (DENSPLY), Fuji IX (GC), Riva self cure (SDI), and Ketac Nano (3M ESPE). Fluoride release in deionized water from the tested specimens was measured using a fluoride-selective ion electrode for 9 days. The compressive strengths and diametral tensile strengths after storing in distilled water (room temperature, 24) were tested. Glass ionomer surface wear by dental ceramic (Vita Mark II cylinders) was evaluated by a depth micro analyzer. Data were analyzed using ANOVA followed by Tukey’s test or Bonferroni method (p= 0.05).
Results: The fluoride release exhibited high concentration, following by a significant drop on the second day. Fuji IX had the highest fluoride release followed by “Ketac”,” Riva”, and
“ChemFil”. Compressive strength results ranked that ChemFil as the highest value, followed by Fuji IX, Ketac, and Riva. The diametral tensile strength test ranked ChemFil and Ketac as the
v
highest values. Surface ear against dental ceramic (Vita Mark II cylinders) revealed that Fuji IX had the lowest material loss, followed by Ketac, ChemFil, and Riva. Data showed significant differences between all of them. After coating the glass ionomer, the surface wear loss was reduced significantly in Riva and ChemFil.
Conclusions: The tested restorative glass ionomers showed differences in fluoride release and the differences decreased over time, with Fuji IX releasing the highest amount of fluoride ion. ChemFil Rock showed the highest mechanical properties but the lowest fluoride release. Riva self cure had the highest material loss value in wear test. There was a weak inverse correlation between fluoride release and compressive strength (r = - 0.32); fluoride release and diametral tensile strength (r = - 0.60), and fluoride release and surface wear against dental ceramic (Vita Mark II cylinders) (r = - 0.55).
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Table of Contents
ABSTRACT ... iv
Table of Contents ... vi
List of figures ... viii
List of tables ... ix
Chapter 1. Introduction ... 1
1.1 Glass ionomer cement development ... 2
1.2 Glass ionomer compositions ... 2
1.3 Glass ionomer chemistry ... 3
1.4 Clinical properties of glass ionomers ... 3
1.5 Uses of glass ionomers ... 4
1.6 Fluoride Release ... 5
1.7 Mechanical properties ... 6
1.7.1 Compressive Strength and Diametral Tensile Strength ... 6
1.7.2 Wear of GIC materials: ... 7
Objectives ... 10
Chapter 2 Materials and Methods ... 11
2.1 Material ... 11
2.2 Fluoride Release ... 14
2.3 Mechanical Properties ... 17
2.3.1 Compressive Strength ... 17
2.3.2 Diametral Tensile Strength ... 17
2.3.3 Surface wear of GIC’s against dental ceramic (Vita Mark II cylinders) ... 18
2.4 Scanning Electron Microscopic Analysis ... 21
Chapter 3 Results ... 22
3.1 Fluoride Release ... 22
3.2 Mechanical Properties ... 25
3.2.1 Compressive Strength ... 25
3.2.2 Diametral Tensile Strength ... 26
3.2.3 Surface wear of GIC’s against dental ceramic (Vita Mark II cylinders) ... 27
3.3 Correlation between fluoride release and mechanical properties ... 30
vii
Chapter 4 Discussion ... 38
Chapter 5 Conclusions ... 42
Bibliography ... 44
viii
List of figures
FIGURE 1: SCHEMATIC ILLUSTRATION OF COMPRESSIVE STRENGTH (BRESCIANI ET AL. 2004) ... 6
FIGURE 2:SCHEMATIC ILLUSTRATION OF DIAMETRAL TENSILE STRENGTH (BRESCIANI ET AL. 2004) ... 7
FIGURE 3: GC FUJI IX GP CAPSULE (RADIOPAQUE POSTERIOR GLASS IONOMER RESTORATIVE CEMENT IN CAPSULES) ... 13
FIGURE 4: SDI RIVA SELF CURE CAPSULE (GLASS IONOMER RESTORATIVE MATERIAL) ... 13
FIGURE 5: CHEMFIL ROCK (ADVANCED GLASS IONOMER RESTORATIVE) ... 13
FIGURE 6: 3M ESPE KETAC NANO (LIGHT-CURING GLASS IONOMER RESTORATIVE AND PRIMER) 13 FIGURE 7: SDI RIVA COAT ... 14
FIGURE 8: GC FUJI VARNISH ... 14
FIGURE 9: 3M ESPE KETAC GLAZE ... 14
FIGURE 10: THE SPECIMENS IN DEIONIZED WATER ... 15
FIGURE 11: GLASS IONOMER SPECIMENS FOR MEASURING FLUORIDE RELEASE (MEASURING 6MM × 3 MM) ... 15
FIGURE 12: SELECTIVE IONIC ELECTRODE FOR TESTING FLUORIDE CONCENTRATION ... 15
FIGURE 13: CALIBRATING SOLUTIONS WITH DIFFERENT FLUORIDE CONCENTRATIONS ... 16
FIGURE 14: SPECIMEN IN COMPRESSIVE STRENGTH TESTING ... 18
FIGURE 15: SPECIMEN IN DIAMETRAL TENSILE STRENGTH TESTING ... 18
FIGURE 16: GIC SPECIMENS PLACED IN SPECIAL MOLDS ... 19
FIGURE 17: METAL RODS WITH MOUNTED CYLINDERS (VITA MARK II) FOR WEAR TEST OF GIC MATERIALS ... 19
FIGURE 18: SAMPLE’S WEAR DEPTH MEASUREMENT UNDER MICROMETER ... 20
FIGURE 19: CUSTOM MADE WEAR TEST APPARATUS ... 20
FIGURE 20: SELECTED GLASS IONOMER PREPARED TO BE OBSERVED UNDER SEM ... 21
FIGURE 21: FLUORIDE RELEASE OVERTIME ... 22
FIGURE 22: FLUORIDE RELEASE FROM DAY 6 TO DAY 9 ... 23
FIGURE 23: DIFFERENCES IN COMPRESSIVE STRENGTH ... 25
FIGURE 24: DIFFERENCES IN DIAMETRAL TENSILE STRENGTH ... 26
FIGURE 25: DIFFERENCE IN WEAR DEPTH OF GIC SPECIMENS AGAINST DENTAL CERAMIC (VITA MARK II CYLINDERS) ... 30
FIGURE 26: RIVA SELF CURE (INTACT AREA) AT 1.00K MAGNIFICATION ... 34
FIGURE 27: RIVA SELF CURE (ABRASION AREA) AT 1.00 K MAGNIFICATION ... 34
FIGURE 28: FUJI IX (INTACT AREA) AT 1:00 K MAGNIFICATION ... 35
FIGURE 29: FUJI IX (ABRASION AREA) AT 1.00 K MAGNIFICATION ... 35
FIGURE 30: CHEMFIL ROCK (INTACT AREA) AT 1:00 K MAGNIFICATION ... 36
FIGURE 31: CHEMFIL ROCK (ABRASION AREA) AT 1:00 K MAGNIFICATION ... 36
FIGURE 32: KETAC NANO (INTACT AREA) AT 1.00 K MAGNIFICATION ... 37
FIGURE 33: KETAC NANO (ABRASION AREA) AT 1.00 K MAGNIFICATION ... 37
ix
List of tables
TABLE 1: RESTORATIVE MATERIALS USED IN THIS STUDY ... 11
TABLE 2: COATS AND GLAZES USED OVER THE MATERIALS ... 12
TABLE 3: STATISTICAL DIFFERENCE OF FLUORIDE RELEASE FROM DAY 1 TO DAY 9 ... 24
TABLE 4: STATISTICAL DIFFERENCE IN COMPRESSIVE STRENGTH ... 25
TABLE 5: STATISTICAL DIFFERENCE IN DIAMETRAL TENSILE STRENGTH ... 26
TABLE 6: STATISTICAL DIFFERENCE IN SURFACE WEAR OF GIC MATERIALS AGAINST DENTAL CERAMIC (VITA MARK II CYLINDERS) ... 28
TABLE 7: STATISTICAL DIFFERENCE (BONFERRONI METHOD) IN SURFACE WEAR OF GIC MATERIALS AGAINST DENTAL CERAMIC (VITA MARK II CYLINDERS) ... 28
TABLE 8: RIVA SELF CURE’S COMPOSITION (WT%) ... 32
TABLE 9: KETAC NANO’S COMPOSITION (WT%) ... 32
TABLE 10: CHEMFIL ROCK’S COMPOSITION (WT%) ... 33
1
Chapter 1. Introduction
Restorative dental materials are used to replace missing tooth structure. Amalgam, resin composites, and glass ionomers are the three broad categories of materials used in restorative dentistry for direct restoration.
Ideal restorative material has chemical bond to enamel and dentine, biocompatability, bacteriostatic, high compressive and tensile strength, high esthetic, release fluoride, and similar wear rate and thermal expansion to tooth structure. (Rodríguez-Farre et al. 2016)
Currently there are a variety of options to restore primary teeth. Many of them are tooth-colored materials due to high demand. (Stavridakis, Krejci, and Magne 2005)Some of the available materials in the market are conventional glass ionomer cements and composite resins, resin modified glass ionomer cements and polyacrylic acid modified composites (compomers). (Burke et al. 2002)
Conventional glass ionomer cement adheres to enamel and dentine, biocompatible, release fluoride, and has good thermal expansion. (Calvo et al. 2016) A three-year clinical study showed that resin modified glass ionomer cement could be another treatment of choice in primary dentition. (Croll et al. 2001)
Composite resin has the highest esthetic properties, adhere to tooth structure, high wear resistance. It is recommended in preventive resin restoration. It could be used in anterior teeth, class I, class II restoration within the line angels. (K. J. Donly and García-Godoy 2002)
Compomers restoration is another option in primary dentitions because it releases fluoride and has similar composite characteristics. (J. O. Burgess, Walker, and Davidson 2002)
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1.1Glass ionomer cement development
After development of different materials in the early sixties, it was known that hydrophilic materials can wet and react with hydroxyapatite and/or dentine to create a sturdy bond to the tooth structure. In 1963, polyacrylic acid was considered for the first time to adhere to dental tissue. It was found that polyacrylic acids has the capability to react with calcium and form hydrogen bond with organic polymer similar to collagen. Therefore, materials having fillers, fluorides and copolymer became commercially present. (Lohbauer 2009)
Glass ionomer cement was first introduced by Wilson and Kent in 1972. It was marketed in Europe in 1975 and introduced to the North American market in 1977. The original cement consists basically of a powder and a liquid. The powder is alumino-calcuim silicate glass
prepared in fluoride flux, while the liquid is mainly modified polyacrylic acid. (Valanezhad et al. 2016)
1.2 Glass ionomer compositions
Glass ionomer cements are composed of fluoride containing silicate glass and polyalkenoic acid. When acid-base reaction takes place, high fluoride release from glass ionomers happens in the first 24 hours most probably due to the burst of fluoride release from glass particles from the reaction with polyalkenoic acid. After that the amount of fluoride release reduces but continues for long term as the glass dissolves in the acidified water of the hydroxyl matrix.
3
Resin modified glass ionomer cements have less moisture sensitivity and better intial mechanical strength compared to conventional glass ionomers. Fluoride release in resin modified glass ionomer cements depends on the amount of resin used for the photochemical
polymerization but still have high fluoride release in the 24h. (Kiri and Boyd 2015)
1.3 Glass ionomer chemistry
Glass ionomer cements are classified into three main categories: conventional, metal reinforced and resin modified. They consist of a powdered calcium aluminosilicate glass that also contain fluoride and liquid that is aqueous solution of polyacrylic acid and tartaric acid. (G. Mount 1991)
When powder and liquid are mixed, acid attack on the glass release calcium, aluminum, and fluoride ions. These ions interact with polyacrylates in the matrix around the glass particles. The cements are thought to adhere to tooth structure by formation of ionic bonds at the tooth cement interface as a result of chelation of carboxyl groups in the acid with the calcium and or phosphate ions in the apatite of enamel and dentin. (Berg 1998)
Metal reinforced glass ionomer cement is formed after the addition of silver amalgam alloy powder to conventional materials (McLean 1992b). However, resin modified glass ionomer cement which could be light cured due to the addition of resin polymerization that needs to be activated by a light curing process. (Gj Mount, Patel, and Makinson 2002)
1.4 Clinical properties of glass ionomers
Glass ionomer cements bond chemically to tooth structure during the setting reaction. (Millar, Abiden, and Nicholson 1998) They are biocompatible because weak acids are used such
4
as polyacrylic acids. Regarding mechanical strength, conventional glass ionomer cements have
weak mechanical properties but newer products shows an increase in the compressive strength but still low in tensile strength. (McLean 1992a)
Conventional glass ionomer cements are opaque because of high fluoride content, but now are more translucent with the drop in fluoride and the adding of more translucent glasses. (Kupietzky et al. 1994) In addition, they have anticariogenic and antimicrobial properties due to fluoride release. (Mitra 1991)
1.5 Uses of glass ionomers
Although resin-based sealants are known for most effective material in pits and fissure sealant, (Forsten 1995) glass ionomers are more practical in certain situations such as difficult to isolate deeply pitted and fissured primary molars, partially erupted permanent molars. (Manhart et al. 2000)
Glass ionomers are available as luting agents. They are self-adhesive and only require removal of the smear. (J. Burgess, Norling, and Summitt 1994) Glass ionomers are the material of choice for stainless steel crowns cementation (Hse, Leung, and Wei 1999)and cementing orthodontic bands. (Kilpatrick 1996)
Glass ionomers can be used in primary dentition for class I preparation.(Curzon, Pollard, and Duggal 1996)Resin modified glass ionomer is used for small- to medium-sized Class II restorations(Nj 2000)and small Class III and Class V-type restorations. (Rutar, McAllan, and tyas 2002)
5 1.6 Fluoride Release
When demineralization of inorganic portion and destruction of organic substance of hard dental tissue, caries process starts and tooth cavitation happens. So it is really important to find a mechanism that prevents acid production and slows down demineralization or even helps in remineralization. (Bansal and Bansal 2015) the caries progression depends on the balance between pathological and protective factors. Fluoride is an important protective factor which shifts the caries balance to the favorable side. (Mungara et al. 2013)
Fluoride is known for years in the reduction of dental caries by the formation of
fluoroapatite and fluorohydroxyapatite which are most resistance to acid dissolution.(Bansal and Bansal 2015) there are two categories in the use of fluoride as a protective agent against caries production which are preventive and restorative. (Mungara et al. 2013) The well-known
preventive delivery systems for fluoride are the professional application such as fluoride varnish, and home methods such as mouth wash and fluoridated toothpaste. (Bansal and Bansal 2015)
The restorative materials such as glass ionomer cements and resin modified glass ionomer cements are the other category of preventing dental caries. The main characteristics in fluoride releasing material is the fluoride release which helps in decreasing mineral tooth structure solubility and inhibiting microbial metabolism. (Cabral et al. 2015)
After the addition of fluoride to dental materials, it draws the attention of the clinicians and researchers to use these materials as a source of low fluoride releasing substance. It is really important to find out how much fluoride is producing and for how long. It depends on several factors such as the materials’ composition, powder liquid ratio, setting mechanism, fluoride content, and nature of fluoride. (Ananda and Mythri 2014)
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1.7Mechanical properties
1.7.1 Compressive Strength and Diametral Tensile Strength
Compressive strength test allows us to understand the mechanical integrity of a material since ideal restorative material should have the ability to withstand occlusion forces. In a compressive strength two axial forces are applied to the test material in opposite directions, as shown in Figure 1. It is significant to represent the material’s performance under masticatory forces.(Aksakalli et al. 2015) (Mittal et al. 2015)
Figure 1: Schematic Illustration of compressive strength (Bresciani et al. 2004)
It is very important for a material to have a good diametral tensile strength because a lot of the failures in the oral cavity are due to tensile stress. Diametral tensile strength test is
appropriate for brittle materials. (Hammouda 2009) To measure the diametral tensile strength in the lab, an applied force is directed across the diameter of a cylindrical specimen by compression plate, as shown in Figure 2. (Bresciani et al. 2004)
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Figure 2:schematic illustration of diametral tensile strength (Bresciani et al. 2004)
1.7.2 Wear of GIC materials:
Wear is defined by Pugh as interaction between surfaces which resulted in gradual removal of the material. (Freitas et al. 2011) Another important mechanical properties of glass ionomer cement is wear resistance and the ability of it to withstand forces and maintain stable surface overtime. Even with the improvement in glass ionomer in regards to other properties such as adhesion to dental tissue and materials, fluoride release, and biocompatibility, still glass ionomer exhibits relatively low wear resistance compared to other material such as composite especially in load-bearing areas. (Shabanian and Richards 2002) One of the main reasons for clinicians to replace glass ionomer materials in posterior teeth is its abrasive wear when subjected to masticatory and brushing friction forces. (Yap, Pek, and Cheang 2003) As known extreme wear can decrease masticatory function, affect a child’s facial growth, and other oral disorders such as tooth sensitivity and temporomandibular joint disorder. (Galo, Contente, and Borsatto 2014)
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Wear is a loss of material as a result of the contact of two or more materials. It has four different types which are corrosive, surface fatigue, adhesive and abrasive. Corrosive wear is the removal of reaction products of corrosion by mechanical action. It is important type of wear in metal system but not to nonmetals in the oral environment. Surface fatigue is found where stress repetition is of a high order such as rolling system. Loss of the material occurs as flaking off of sheet-like particles. Adhesive wear occurs as the result of fragment caused by strong and true adhesive forces between opposing materials in sliding contact. (Culhaoglu and Park 2013)
Abrasive wear occurs from the mechanism of hard and/or rough material against a softer material. It has two types 2-body and 3-body abrasive. The difference between them is the presence of substance in between the two surfaces such as dentifrice in the 3-body
abrasive.(Freitas et al. 2011)
There were several attempts to increase the mechanical properties of glass ionomer materials by incorporating bioactive ceramic particles and glass powder but it was found that significant strength happened when adding short glass fibers of similar composition to glass ionomer cements. The chemical and physical formulation of the glass and new glass preparation has high impact on better glass ionomer cements properties. (Kim et al. 2015)
After adding resin monomers (HEMA and Bis-GMA and activating substance) to conventional glass ionomer cement, resin-modified glass ionomer cement was formed. It is found that resin modified glass ionomer has higher mechanical properties and still has fluoride release. (Li et al. 2015) In addition they overcome some weakness of conventional glass ionomer cement such as surface crazing during dehydration, brittleness and low fracture strength.
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It is essential for glass ionomer cement to resist masticatory and parafunctional stresses when placed in wet oral cavity. It is well-known that polycarboxylate and glass ionomer cements have good wettability and bonding properties. In addition to those properties, it is really
important to have good compressive and tensile strength as well to stay intact long enough in the oral cavity.(Patil, Sajjan, and Patil 2015)
It was found that filler load and composition have a large effect on the mechanical properties within the same material’s type. In general, when the filler load increases the mechanical properties increase. As the filler load contributes to the mechanical properties of a material, the fillers’ composition has even more influence on the mechanical properties. (Xu and Burgess 2003)
In fluoride releasing material the fluoroaluminosilicate glass is the main component in fluoride releasing material. Another component in conventional glass ionomer cements and resin modified glass ionomer cements is calcium which starts the chemical reaction with acid or polyacid to form crosslinked gel network. It is known that Ca-Al-F silicate glass fillers are more soluble and weaker when compared composite’s filler which doesn’t contain calcium. Most of the time composite materials contain silica (SiO2) which gives composite higher mechanical properties. (Xu and Burgess 2003)
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Objectives
The objectives of the study are:
1. To assess the fluoride release of 4 restorative glass ionomers.
2. To assess the mechanical properties (compressive strength, diametral tensile strength) of 4 restorative glass ionomers.
3. To assess the surface wear against dental ceramic of 4 restorative glass ionomers. 4. To determine the correlation between compressive strength, diametral tensile strength,
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Chapter 2 Materials and Methods
2.1 MaterialFour restorative glass ionomers were studied: A. ChemFil Rock (Dentsply); B. Fuji IX (GC); C. Riva (SDI); and D. Ketac Nano (3M ESPE) as shown in Table 1. Three coats are used over the materials: A. SDI Riva coat; B. GC Fuji varnish; C. 3M ESPE Ketac glaze as shown in Table 2.
Table 1: Restorative materials used in this study
Materials Composition
A. GC Fuji IX GP CAPSULE (radiopaque posterior glass ionomer restorative cement in capsules), Figure 3.
Powder: alumino silicate glass 95%, polyacrylic powder 5% Liquid: polyacrylic acid powder 5-10%
B. SDI Riva self-cure capsule (glass ionomer restorative material), Figure 4.
Compartment 1: polyacrylic acid 20-30% and tartaric acid 10-15 % (by weight)
Compartment 2: fluoro aluminosilicate glass 90-95% and polyacrylic acid 5-10% (by weight)
C. ChemFil ROCK (advanced glass ionomer restorative), Figure 5.
1-calcium-aluminum-zinc-fluoro-phosphor-silicate glass 2-polycarboxylic acid
3-iron oxide pigments 4-tartaric acid
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D. 3M ESPE Ketac Nano (light-curing glass ionomer restorative and primer), Figure 6.
1-silane treated glass 40-55% (by weight) 2-silane treated zirconia 20-30% (by weight)
3-polyethylene glycol dimethacylate (PEGDMA) 5-15% (by weight) 4-silane treated silica 5-15% (by weight)
5-2-hydroxyethyl methacylate (HEMA) 1-15% (by weight) 6-glass powder <5% (by weight)
7-bisphenol a diglycidyl ether dimethacrylaste (BISGMA) <5% (by weight)
8-Triethylene glycol dimethacylate (TEGDMA) <1% (by weight)
Table 2: Coats and glazes used over the materials
Materials Composition
A. SDI Riva coat, Figure 7. Acrylic monomer
B. GC Fuji varnish, Figure 8.
1- isopropyl acetate 60-70% (by weight) 2-acetone 10-20%
3-copolymer of vinyl chloride and vinyl acetate 10-20%
C. 3M ESPE Ketac glaze, Figure 9.
1- 2-propenoic acid, 2-methy-,[(3-methoxypropyl)imino]di-2,1-ethanediyl ester 1-5 % trade secret (by weight)
2-dicyclopentyldimethylene diacrylate >95 % trade secret (by weight)
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Specimens were mixed and fabricated at room temperature according to manufacturer’s instructions.
Figure 3: GC Fuji IX GP CAPSULE (radiopaque posterior glass ionomer restorative cement in capsules)
Figure 4: SDI Riva self cure capsule (glass ionomer restorative material)
Figure 5: ChemFil ROCK (advanced glass ionomer restorative)
Figure 6: 3M ESPE Ketac Nano (light-curing glass ionomer restorative and primer)
14 2.2 Fluoride Release
Four samples from each material measuring 6mm (diameter) × 3 mm were made in special molds. Each material was prepared in a spilt Teflon mold following manufacturers’ directions. The material was injected into the Teflon mold and pressed between two microscopic glass slides. The specimens were allowed to set in the mold between the glass slides. After the material completely set, each specimen was measured for its diameter and length using electronic digital caliper, as shown in Figure 10.
Figure 7: SDI Riva coat
Figure 8: GC Fuji varnish
Figure 9: 3M ESPE Ketac glaze
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After that, the specimens of each material were placed in plastic tube containing 15 mL deionized water immediately after fabrication and curing, as shown in Figure 11. After each day (24 h interval) the specimens were removed, dried and returned into a new tube containing 15 mL deionized water.
Fluoride release was measured daily for 9 days in deionized water using a fluoride-selective ion electrode (Fisher Scientific accumet 13-620-629) connected to an pH/ionic meter (Thermo Scientific Orion 4. Star) as shown in Figure 12.
Figure 12: Selective ionic electrode for testing fluoride concentration
Figure 11: Glass ionomer specimens for
measuring fluoride release (measuring 6mm × 3
mm)
Figure 10: The glass ionomer specimens in deionized water
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Before fluoride concentration measurement, the ionic meter was calibrated with three different fluoride concentrations of 1, 2, and 10 ppm for high concentration range, as shown in Figure 13, or calibrated with four fluoride concentrations 0.1, 0.2, 0.5, and 1 ppm for low concentration range.
Before measurement, 10 mL of the solution was pipetted into clean plastic tube and 10 mL of TISAB II solution (Thermo Scientific) (total ionic strength adjustment buffer concentrate) with CDTA (1,2-cyclohexylenedinitrolotetraacetic acid) was added to each solution. The TISAB was added to provide constant background ionic strength, decomplex fluoride, and adjust the solution pH. The fluoride concentration (mg/L) was read directly on the instrument display and recorded.
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2.3Mechanical Properties
2.3.1 Compressive Strength
Cylindrical specimens (N=10) for testing compressive strength (CS) measured 6mm diameter. × 6mm high. The specimens were made in a Teflon mold following manufacturers’ directions. The material was forced into the Teflon mold and pressed between two microscope glass slides. The materials were allowed to set and then taken out of the mold. The specimens’ measurements were taken using digital caliper for accuracy before starting the experiment. The specimens were stored in distilled water at room temperature for 24 h before tested.
They were loaded in with the flat ends between the platens of the apparatus so the load applied in the long axis of the specimens at a crosshead speed of 0.5 mm/min as shown in Figure 14. The maximum load applied to fracture the specimens was recorded (MPa) using universal testing machine (INSTRON 5566A).
2.3.2 Diametral Tensile Strength
Specimens for diametral tensile strength (DTS) measured 6mm diameter × 3mm high (N=10) for each material. The specimens were made in a Teflon mold and pressed between two microscopic glass slides until the materials are completely set then taken out and measured before continuing the experiment. The specimens were stored in distilled water at room temperature for 24 h before tested.
The specimens were placed with the flat ends perpendicular to the platens of the apparatus so the load was applied to the diameter of the specimens at a crosshead speed of
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0.5mm/min as shown in Figure 15. The maximum load applied to fracture the specimens were recorded (MPa) using a universal testing machine (INSTRON 5566A).
Figure 15: specimen in diametral tensile strength testing
2.3.3 Surface wear of GIC’s against dental ceramic (Vita Mark II
cylinders)
Rectangular specimens were prepared in molds with dimensions 10 mm length, 3 mm width and 2 mm depth. The mixture of the cement were placed into the molds and then slightly overfilled, covered with acetate strips and compressed with microscopic glass plates to extrude excess material. Immediately after setting, the acetate strips were discarded and the specimens were stored in distilled water for 24 hours at room temperature, as shown in Figure 16.
To test the efficacy of varnish application, a layer of varnish was placed on top of the material using micro-brush flowing manufactures instructions after glass ionomer cements completely set. Designated varnishes made by the same companies for Riva self cure, Fuji IX, and Ketac Nano of Riva coat, GC Fuji varnish, and Ketac glaze, respectively. However, ChemFil
Figure 14: specimen in compressive strength testing
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ROCK has no designated varnish in the market, so 3M ESPE Ketac glaze was used with it in this test.
Cylinders with 2.6mm in diameter were prepared with Vita Mark II. Specimens were cut into cylindrical shape using trephine diamond bur. Each Vita Mark II cylinder was mounted to metal rod with sticky wax. Each load is loaded with 90 grams to reproduce average forces observed in vivo, as shown in Figure 17.
Figure 17: Metal rods with mounted cylinders (Vita Mark II) for wear test of GIC materials
A traditional approach to measure in vitro wear was used by using pins and plates. It is a two-body abrasion test where no abrasive material is between the pins and plates but running tap water to flush out glass ionomer particles generated by the wear test. Plates of materials are set against each other horizontally at a fixed distance with an exact load in a submerged
environment for 100,000 cycles (30 cycles/min), and the number of cycles was counted digitally.
Figure 16: GIC specimens
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The apparatus was designed to produce continuous contact between the pins and plates and provide a back and forth movement over a distance of 5mm under constant load of 90 gram as shown in Figure 18. Wear evaluation is performed by measuring the depth of the groove created in micrometer (µm), as shown in Figure 19.
Figure 19: Custom made wear test apparatus
Figure 18: sample’s wear depth measurement under micrometer
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2.4 Scanning Electron Microscopic Analysis
Selected glass ionomer specimens were glued on an aluminum stub (TED PELLA, INC), as shown in Figure 20. The specimens were sputter coasted with gold/palladium using a sputter coater (Hummer II Technics, Alexandria, Virginia). Specimens were then viewed under the SEM to compare abrasion part from intact part, and check composition by EDS (Energy dispersive spectrum).
Figure 20: Selected glass ionomer prepared to be observed under SEM
The comparison of fluoride release, compressive strength, diametral tensile strength and surface wear against dental ceramic (Vita Mark II cylinders) were analyzed using ANOVA followed by Tukey’s test or Bonferroni method. A significance level of 0.05 was used for all statistical analysis.
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Chapter 3 Results
3.1 Fluoride ReleaseThere was a significant difference in fluoride release in all materials except between Ketac Nano and Riva self cure in day 1, as shown in Table 3. Fuji IX had the highest fluoride release (6.19 ± 1.04 mg/L) followed by Ketac Nano (3.88 ± 0.13 mg/L), then Riva self cure (3.19 ± 0.66 mg/L), and ChemFil ROCK (1.68 ±0.08 mg/L).
There were still significant differences between higher fluoride release materials Fuji IX and Ketac Nano and lower fluoride release materials Riva self cure and ChemFil ROCK in day 2, as shown in Table 3. The differences became smaller overtime and stabilized at low level after day 5 with still Fuji IX has the highest fluoride release and ChemFil ROCK has the lowest fluoride release, as shown in Table 3. The fluoride release over time diagram for the 4 materials is shown in Figure 21- 22.
Figure 21: Fluoride release overtime
0 1 2 3 4 5 6 7 8
day1 day2 day3 day4 day5 day6 day7 day8 day9
mg/L
23 Figure 22: Fluoride release from day 6 to day 9
It was found that conventional glass ionomer materials tested in this study had a wide range of fluoride release values. Fuji IX had the highest fluoride release while ChemFil ROCK had the lowest fluoride release among tested materials. Both materials are conventional glass ionomer materials.
The highest release was in the first day and then significant drop happened in the second day. From day 5 to day 9 no statistical significance differences in the fluoride release within the same material. The fluoride release stabilized at very low level.
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
day6 day7 day8 day9
ChemFil ROCK Fuji IX Ketac Nano Riva self cure
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Table 3: Statistical difference of fluoride release from day 1 to day 9
Ma te ri al s Mean fluoride-release (day 1) mg/L Tukey Significa nce Mean fluoride-release (day 2) mg/L Tukey Significa nce Mean fluoride-release (day 3) mg/L Tukey Significa nce Mean fluoride-release (day 4) mg/L Tukey Significa nce Mean fluoride-release (day 5) mg/L Tukey Significa nce Mean fluoride-release (day 6) mg/L Tukey Significa nce Mean fluoride-release (day 7) mg/L Tukey Significa nce Mean fluoride-release (day 8) mg/L Tukey Significa nce Mean fluoride-release (day 9) mg/L Tukey Significa nce Fu ji I X 6.19 (1.04) A 1.67 (0.10) A 0.81 (0.26) A 0.55 (0.15) A 0.45 (0.12) A 0.41 (0.11) A 0.38 (0.12) A 0.33 (0.08) A 0.27 (0.07) A Ke ta c Na no 3.88 (0.13) B 1.41 (0.35) A 0.74 (0.09) AB 0.43 (0.04) AB 0.35 (0.03) AB 0.33 (0.03) AB 0.29 (0.03) AB 0.20 (0.06) B 0.18 (0.05) B Ri va se lf cu re 3.19 (0.66) B 0.88 (0.20) B 0.60 (0.14) BC 0.37 (0.14) BC 0.31 (0.11) BC 0.31 (0.14) AB 0.27 (0.09) AB 0.19 (0.05) B 0.17 (0.05) B Ch em F il RO CK 1.68 (0.08) C 0.59 (0.22) B 0.41 (0.11) C 0.24 (0.07) C (0.04) C 0.20 0.20 (0.05) B 0.18 (0.05) B 0.14 (0.03) B 0.13 (0.02) B
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3.2Mechanical Properties
3.2.1 Compressive Strength
Compressive strength results showed that ChemFil Rock has the highest mean value 171.3 ± 30.99 MPa followed by Fuji IX 131.2 ± 10.03 MPa, then Ketac Nano 118.2 ± 16.45 MPa, and Riva had the lowest value 90.2 ± 19.84 MPa as shown in Figure 23. The ANOVA test reveals that there was a statistically significant difference between the groups in compressive strength. Data showed significant differences among the materials except between Fuji IX and Ketac Nano, as shown in Table 4.
Table 4: Statistical difference in compressive strength
Material Compressive Strength (CS) MPa Standard deviations Tukey Significance ChemFil ROCK 171.3 30.99 A Fuji IX 131.2 10.03 B Ketac Nano 118.2 16.45 B Riva self cure 90.2 19.84 C
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3.2.2 Diametral Tensile Strength
Table 5 and Figure 24 show the diametral tensile strength of tested materials. ChemFil ROCK and Ketac Nano showed the highest values 19.1± 3.44 and 18.8 ± 4.10, respectively, and no significant difference between them. The diametral tensile strength of Riva self cure was 14.2 ± 5.47 MPa and Fuji IX was 14.1 ± 2.13 MPa. The diametral tensile strength values of Fuji IX and Riva self cure had no statistically significant difference.
Table 5: statistical difference in diametral tensile strength
Material Diametral Tensile Strength (DTS)
MPa Standard deviations Tukey Significance
ChemFil ROCK 19.1 3.44 A
Ketac Nano 18.8 4.10 A
Riva self cure 14.2 5.47 B
Fuji IX 14.1 2.13 B
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All compressive strength values were lower than diametral tensile strength values among the four tested materials. The lowest and highest values in both compressive and diametral tensile strength were from materials from the same class that is conventional glass ionomer materials.
3.2.3 Surface wear of GIC’s against dental ceramic (Vita Mark II
cylinders)
Surface wear of GIC’s against dental ceramic (Vita Mark II cylinders) revealed that Fuji IX had the lowest material loss with mean value of 0.038 ± 0.006 µm followed by Ketac Nano 0.049 ± 0.009µm, then ChemFil ROCK 0.062 ± 0.011 µm, and Riva self cure had the highest material loss value 0.097 ± 0.007 µm, as shown in Table 6. Statistical significant differences were found between all groups, as shown in Table 7.
After applying the coat (varnish) on the material, the material loss was reduced in some materials more than others. In Fuji IX with varnish the material loss wasn’t reduced much. It was 0.038 ± 0.018 µm which is similar to Fuji IX without varnish application. Similarly with Ketac Nano with varnish, the material loss was minimally reduced compared to Ketac Nano. It was reduced to 0.043 ± 0.003 µm. However, in Riva self cure with varnish the material loss was significantly reduced compared to Riva self cure without varnish. Riva self cure with varnish was reduced to 0.045 ± 0.006µm. likewise Riva self cure with varnish, ChemFil Rock with varnish the material loss was statistically significant reduced compared to ChemFil Rock without varnish application. It was reduced to 0.025 ± 0.005µm in ChemFil Rock with varnish, as shown in Table 6 and Figure 25. There was a statistically significant difference between the material with and without applying the varnish in Riva self cure and ChemFil Rock but not in Ketac Nano and Fuji IX, as shown in Table 7.
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Table 6: Statistical difference in surface wear of GIC materials against dental ceramic (Vita Mark II cylinders)
Material Material loss (µm) by
wear Standard deviations
Fuji IX 0.038 0.006
Ketac Nano 0.049 0.009 Riva self cure 0.097 0.007 ChemFil ROCK 0.062 0.011 Fuji IX with varnish 0.038 0.018 Ketac Nano with varnish 0.043 0.003 Riva self cure with varnish 0.045 0.006 ChemFil ROCK with varnish 0.025 0.005
Table 7: Statistical difference (Bonferroni method) in surface wear of GIC materials against dental ceramic (Vita Mark II cylinders)
Material Mean difference µm Significance Bonferroni method Riva self cure- Ketac Nano 0.048 Yes
Riva self cure- ChemFil ROCK 0.035 Yes Riva self cure- Fuji IX 0.059 Yes Riva self cure- Riva self cure with varnish 0.052 Yes Riva self cure- Ketac Nano with varnish 0.054 Yes Riva self cure-ChemFil ROCK with varnish 0.072 Yes Riva self cure- Fuji IX with varnish 0.067 Yes Ketac Nano- ChemFil Rock -0.012 Yes Ketac Nano-Fuji IX 0.011 Yes Ketac Nano- Riva self cure with varnish 0.005 No
29
Ketac Nano-Ketac Nano with varnish 0.006 No Ketac Nano-ChemFil ROCK with varnish 0.025 Yes Ketac Nano-Fuji IX with varnish 0.019 Yes ChemFil ROCK-Fuji IX 0.023 Yes ChemFil ROCK-Riva self cure 0.017 Yes ChemFil ROCK-Ketac Nano with varnish 0.018 Yes ChemFil ROCK-ChemFil with varnish 0.037 Yes ChemFil ROCK-Fuji IX with varnish 0.031 Yes Fuji IX-Riva self cure with varnish -0.006 No Fuji IX- Ketac Nano with varnish -0.005 No Fuji IX-ChemFil ROCK with varnish 0.014 Yes Fuji IX- Fuji IX (varnish) 0.008 No Riva self cure with varnish-Ketac Nano with
varnish
0.001 No
ChemFil Rock with varnish)-Fuji IX with varnish
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Figure 25: Difference in wear depth of GIC specimens against dental ceramic (Vita Mark
II cylinders)
3.3Correlation between fluoride release and mechanical properties
A weak inverse correlation was found between fluoride release and compressive strength (r= -0.32), fluoride release and diametral tensile strength (r=-0.60), and fluoride release and surface wear against dental ceramic (Vita Mark II cylinders) (r=-0.55).
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3.4Scanning electron microscopic analysis
Scanning electron microscope images were taken for each material in the abrasion and intact area. In addition, the elemental composition of the material was examined by energy dispersive spectrometer.
All materials were viewed under the microscope. The following images were taken at 1 k, magnification in the abrasion and intact area, Riva self cure as shown in Figure 26-27, Fuji IX as shown in Figure 28-29, ChemFil ROCK as shown in Figure 30-31, Ketac Nano as shown in Figure 32-33.
When comparing the abrasion and intact areas at the same magnifications. It was found that in the abrasion area, the fillers are more defined with sharp edges compared to the fillers in the intact area. In addition the fillers are more exposed to the surface in the abrasion area. The fillers are mostly embedded in the intact area for resin modified glass ionomers. This indicate the surfaces of unpolished glass ionomer are polymer-riched.
All materials’ compositions were examined under microscope using energy dispersive spectrum (EDS). It was found that Riva self cure has several elements such as oxygen, fluoride, sodium, magnesium and aluminum. The elements’ average and standard deviation of Riva self cure showed in Table 8. The most abundant elements in Riva self cure were oxygen by 41.1%, followed by aluminum by 18.88%, then strontium by 14.24%. Ketac Nano has several elements such as oxygen, aluminum, sodium, silicon, strontium, and zirconium, as shown in Table 9. The most abundant elements were oxygen 37.5% followed by silicon 18.01% and the lowest
elements were phosphorus 0.99% then calcium 0.87%. By examining ChemFil ROCK, it was found that the most abundant elements were oxygen 36.32%, followed by aluminum 18.11%, then strontium 10.03% and the lowest elements were calcium 5.7% and sodium 1.54% as shown
32
in Table 10. Similarly, it was found that oxygen 32.85%, strontium 21.79%, and aluminum 16.23% were the most abundant elements in Fuji IX and calcium 0.33% and sodium 0.75 % were the lowest elements as shown in Table 11.
Table 8: Riva self cure’s composition (wt%)
Element O F Na Mg Al Si P S Ca Sr
Average 41.1 8.33 0.97 0.28 18.88 13.13 1.81 0.67 2.59 14.24
Standard Deviation
5.94 3.38 0.36 0.04 2.72 1.91 0.47 0.40 1.18 4.62
Table 9: Ketac Nano’s composition (wt%)
Element O F Na Al Si P Ca Zn Sr Zr
Average 37.5 6.91 1.61 8.24 18.01 0.99 0.87 4.71 10.36 15.74
Standard Deviation
33 Table 10: ChemFil ROCK’s composition (wt%)
Element O F Na Al Si P Ca Zn Sr
Average 36.32 3.14 1.54 18.11 10.52 7.12 5.7 8.15 12.03
Standard Deviation
9.76 1.09 0.196 5.36 2.75 2.71 2.09 2.25 4.22
Table 11: Fuji IX’s composition (wt%)
Element O F Na Al Si P Ca Sr
Average 32.85 10.70 0.75 16.23 14.96 2.43 0.33 21.79
Standard Deviation
34
Figure 26: Riva self cure (intact area) at 1.00k magnification
35
Figure 28: Fuji IX (intact area) at 1:00 k magnification
36
Figure 30: ChemFil ROCK (intact area) at 1:00 k magnification
37
Figure 32: Ketac Nano (intact area) at 1.00 k magnification
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Chapter 4 Discussion
In glass ionomer filler chemical composition, porosity, and particle size have significant influence on the fluoride release. As we have seen from EDS microanalysis on glass ionomer fillers, fluoroaluminosilicate glass (F-Al-Si) is the major component of the filler and the main source of fluoride in all fluoride-releasing materials, some contains small amount of sodium fluoride (NaF) and strontium fluoride (SrF2).
Our results were supported by the elemental microanalysis under SEM. The filler of Fuji IX has higher content of fluorine by wt % that is 10.70 ± 0.56 followed by Riva self cure which has 8.33 ± 3.38 of fluorine , then Ketac Nano which has 6.91 ± 0.06 of fluorine. ChemFil ROCK has the lowest fluorine content of 3.14± 1.09. Regarding this order, Riva self cure has more aluminum 18.88 ± 2.72 and less sodium 0.97 ± 0.36 contents by wt% compared to Ketac Nano which has aluminum of 8.24 ± 0.87 and sodium of 1.61 ± 0.60. The difference in aluminum and sodium ratio explains Ketac Nano releases more fluoride ion in deionized water compared to Riva self cure, because sodium salts usually have lower ionization free energy in aqueous solution.
The results of this study contradict the commonly held opinion that conventional glass ionomer has superior fluoride release compared to resin modified glass ionomer (Bansal and Bansal 2015). It was found that Ketac Nano had higher fluoride release compared to Riva self cure and ChemFil ROCK. The possible reason could the incorporation of nanoparticle
conglomerate in Ketac Nano as active filler. Nanoparticles have higher specific surface area, therefore, could releases more fluoride ions than the crystalline filler found in Riva self cure and ChemFil ROCK.
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This study found that there was a high fluoride release in the first day and then a significant drop in all four materials on the second day. Eventually after day 5, the fluoride release reached a plateau where it seemed to stay the same for some time at low level. This indicted the active fluoride release was depleted after 5 days. This finding is consistent with (Cabral et al. 2015) findings where fluoride release started high then decreased after the first day and then from day 7 it plateaued with no statistical differences.
A study by Preston et al. (2003) found that Ketac Nano had higher fluoride release compared to ChemFil ROCK which is similar to the results in our study. However, the exact fluoride release values could not be compared due to differences in the methodologies, such as sample size and media used to measure the fluoride level.
In a study done by Xu and Burgess (2003), it was found that Fuji IX fluoride release was among the highest fluoride release groups compared to other materials in the study. In another study by Cabral et al. (2015) found that Fuji IX showed the highest fluoride release. Both studies’ findings matched our result.
Future studies using artificial saliva as a storage media which is comparable to the oral environment will be helpful. In addition, to evaluate the recharge potential of the materials because the fluoride release from the materials decreases dramatically after few days. The capability to be recharged is an important property to evaluate long-term efficacy of fluoride releasing restorative materials.
The mean compressive and diametral tensile strength values of the four materials fall within the range values of previous studies. (Bresciani et al. 2004), (Xu and Burgess 2003). These were used as the standardization procedure for sample preparation and loads using
40
universal testing machine. All tested materials in the study were in capsules, so there was no manual mixing interference (Bresciani et al. 2004).
One of the limitations of this study was the lack of evaluating the mechanical properties (compressive and diametral tensile strength) of the material over time. It is known that the strength of these materials tends to increase over time. A study by Bresciani et al. (2004)
demonstrated that all tested materials showed higher compressive and diametral tensile strengths when tested after 24h and 7 days compared to 1h.
The two-body wear test was used in this study, to test the effect of opposing teeth on GIC restorations. For standardization of the test, dental ceramic (Vita Mark II cylinders) of uniform shape were used against the tested GIC materials. The two-body wear test is simple and easy to perform. It doesn’t perfectly reflect the conditions in the oral environment, but it provides a comparative indication of restorative materials behavior.
In this study, the material loss including all materials ranged from 0.038 to 0.079 µm. Fuji IX exhibited the lowest wear 0.038 ± 0.006 µm compared to the other materials tested. This result is consistent with the findings of previous study (Kunzelmann, Bürkle, and Bauer 2003). In their study it was found that Fuji IX had the lowest material loss compared to other materials used such as Ketac Molar and Ketac Silver. The level of material loss in this study and their study cannot be comparable because of their use of a different antagonist (aluminum), as well as different load and velocity.
Wear resistance and material loss under abrasion from this study cannot be explained only by filler size, shape, distribution, and elemental content. There are more factors behind the mechanical properties of a material. It can be attributed to many factors such as filler particle
41
loading, hardness, interaction between the filler and the matrix, degree of polymer resin matrix conversion. (Xie et al. 2000) (Kunzelmann, Bürkle, and Bauer 2003).
42
Chapter 5 Conclusions
Within the limitation of this in-vitro study the following conclusions can be drawn:
1. There was a significant difference in fluoride release among all materials (except between Ketac Nano and Riva self cure in day 1). Fuji IX had the highest fluoride release,
followed in decreasing level by Ketac Nano, Riva self cure, ChemFil ROCK.
2. Fluoride release started high, then a significant drop occurred on day 2 for all four materials (p < 0.05). However, there was still a significant difference between higher fluoride release materials Fuji IX and Ketac Nano and lower fluoride release materials Riva self cure and ChemFil ROCK in day 2.
3. The differences in fluoride release became smaller overtime and stabilized at low level after day 5, still with Fuji IX the highest fluoride release and ChemFil ROCK the lowest fluoride release.
4. Compressive strength data showed significant differences among the materials (p<0.0001) except between Fuji IX and Ketac Nano (p = 0.17).
5. ChemFil ROCK and Ketac Nano exhibited the highest diametral tensile strength values. There was no significant difference between the two groups (p = 0.86).
6. Wear test revealed that Fuji IX had the highest surface wear resistance with lowest material loss followed by Ketac Nano, then ChemFil. Riva self cure had the highest material loss. There was significant difference between the groups (p < 0.05)
43
7. Applying varnish to the glass ionomer materials in the surface wear test reduced material loss after abrasion significantly in Riva self cure and ChemFil ROCK (p > 0.05).
8. There was a weak inverse correlation between fluoride release and compressive strength (r= -0.32); fluoride release and diametral tensile strength (r=-0.60), and fluoride release and surface wear against dental ceramic (Vita Mark II cylinders) (r=-0.55).
9. Overall, the restorative glass ionomers tested exhibited significant differences in fluoride release, with Fuji IX releasing more fluoride ion. ChemFil Rock exhibited the highest mechanical properties but the lowest fluoride release. Riva self cure had the highest material loss in the surface wear test.
44
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Curriculum Vitae
Sarah Ahmed BahammamAddress 10 Florence st. apt#603 Malden, MA, 02148 Cell: 781- 888-9866 E-mail:sasb@bu.edu Education
2014 Certificate of Advanced Graduate Study (CAGS) in Pediatric Dentistry
Henry M. Goldman School of Dental Medicine. Boston, MA 2011 Master of Science in Dentistry (MSD), Dental Public Health
Henry M. Goldman School of Dental Medicine. Boston, MA 2001 - 2006 Bachelor of Dental Science degree (B.D.Sc.)
Faculty of Dentistry, King Abdulaziz University (KAU), Jeddah, Saudi Arabia.
Grade: (B)
1997 - 2000 High School Diploma
Jeddah, Saudi Arabia Grade: (A).
Certificates
50 Work Experience
2008 - present Teacher Assistant in Dental Public Health and Community Dentistry Division, Faculty of Dentistry.
2006 – 2007 General Dentist as part of a one year internship training program. This includes rotations at different hospitals.
Professional Memberships
2004 - Present SDS, Saudi DentalSociety.
Personal
Saudi national
Bilingual, English and Arabic as a first language
