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RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES, BANGALORE, KARNATAKA
“COMPARATIVE EVALUATION OF MICROHARDNESS OF
CORONAL
DENTIN WITH RESIN MODIFIED GLASS IONOMER AND
COMPOMER IN CLASS V RESTORATION - AN INVITRO STUDY”
By
Dr. PRAKASH LOKHANDE
Dissertation Submitted to the Rajiv Gandhi University of Health Sciences, Karnataka,
Bangalore.
In partial fulfillment of the requirements for the degree of
M.D.S (Master of Dental Surgery)
in
Conservative Dentistry and Endodontics
Under the guidance of
Dr. Mangala T.M.
Department Of Conservative Dentistry And Endodontics BAPUJI DENTAL COLLEGE & HOSPITAL
DAVANGERE – 577 004, KARNATAKA 2006 - 2009
1
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5
ACKNOWLEDGEMENT
At the very onset I would like to convey my heartful gratitude to my parents
who have been the backbone in every aspect of my life. This thesis would not have
been possible without their blessings and support.
Its great honor to express my gratitude to my guide Dr. Mangala T.M.M.D.S.
professor, Department of Conservative Dentistry and Endodontics, Bapuji Dental
College and Hospital, Davangere. She has given me excellent guidance all through in
my academics as well as for my thesis. Her professionalism and knowledge has
always inspired me during the course of my study. I am deeply indebted to her kind
concern and being a sincere advisor which has put me on the right track.
It is with humble sense of gratitude that I thankfully acknowledge my
esteemed Professor and Head Dr. Mallikarjun Goud. K.M.D.S. Department of
Conservative Dentistry and Endodontics , Bapuji Dental College and Hospital,
Davangere, who made this formidable task possible. I shall always be grateful to him
for his sincere advice and timely suggestions.
I can’t forget Dr. Girija Sajjan M.D.S. our former Head of the Department.
She was always kind and supportive during the study period in the College.
I wish to thank Dr. Basavanna M.D.S. Dr. Sophia Thakur M.D.S. Dr. Arvind
Shenoy.M.D.S. Dr.Satya Narayanan K.M.D.S. Dr. Subhash T.S. M.D.S.
Dr. Kanchan M.D.S. Department of Conservative Dentistry and Endodontics, for
providing their support and guidance during the course of my study.
6VI
It is with great honor and pleasure that I will take this opportunity to thank our
beloved Principal, Dr. K. Sadashiva Shetty, Bapuji Dental College and Hospital,
Davangere, for facilitating my study.
I sincerely thank our Chairman, Late Sri I.P. Vishwaradhya. M.Com. for the
providing an opportunity to pursue this course.
I am deeply indebted to Mr. Shyam Sundar, Department of Mechanical
Engineering, Indian Institute of Science (IISC), Bangalore, for providing me that
opportunity to use the microhardness equipment.
I thank to Mr. Ganesh (Chaithanya Studio), for his excellent photography in
helping me record various photos.
I am grateful to Mr. Thomas & Mrs. Rashika Thomas (THOMAS
COMPUTERS) for helping me to shape out the manuscript and bring out this
dissertation in a neat and coherent manner.
I thank my batchmates Dr. Arun, Dr. Roopa, Dr. Fayaz, Dr. Nikhil and Dr.
Ritesh for extending their valuable help and guidance during the study period.
I thank to all my supportive seniors and lovable juniors for their flawless
support.
Not to forget my seniors Dr. Hemadri, Dr. Amit, Dr. Manjunath, Dr.
Harikiran, Dr. Purushotham for their invaluable encouragement embedded with
humor.
7VII
I extend my sincere gratitude to Netravati B. Yashodhamma H.B.,
Anupama Patil, Umadevi B.T., the paradental staff and not to forget Rudramma
G.C., Annapurnamma and Veeranna J. the attenders.
I immensely thank to my lovable, caring would-be Miss Preethi, for her kind
advice and moral support in my study period.
I can’t forget my elder brother Mr. Santosh N.L. and younger sister
Poornima for their good wishes and prayers
Finally I surrender myself to “Almighty God” for all his divine grace and
fulfilling my dreams.
Date :
Place : Davangere. Dr. Prakash Lokhande
8VII
ABSTRACT
Background and Objective :
Microhardness is one of the most important characteristic for comparative
study of dental biomaterials. Fluoride promotes remineralisation of dental hard tissue
and as we know Glass-ionomer Cement are well known fluoride releasing restorative
material. This study throws a light on, changes taking place in microhardness of
dentin adjacent to Resin modified glass-ionomer (RMGI) or compomer. The aim of
this study is to compare the microhardness of coronal dentin over class V cavities
restored with Resin modified glass-ionomer (RMGI) restorative material and
compomer.
Methodology ;
Thirty extracted human permanent molars with class V caries were taken for
the study. After storing in normal saline, standardized class V cavities were prepared
for each group (n=10). Group I : Without restoration, Group II : Restored with Resin
modified glass-ionomer (RMGI), Group III : Restored with compomer. After ten
days the teeth were embedded in acrylic resin to avoid displacement of restoration
during sectioning. Later dentinal sections of 2 mm were obtained at a level of cavity
floor and roof (cross section) by means of diamond blade. The specimen are
ground, flat and polished with abrasive paper (grit 60-100).
Viker’s microhardness (VHN) measurements were performed by using
Digital Microhardness Tester (Zwick / Roell) at 10th, 20th and 30th day under a
load of 25 grams for 15 seconds at a distance of 100 µm, 200 µm and 300 µm
9IX
from cavity floor. The statistical significance of hardness was analyzed by
one-way ANOVA and Post-Hoc Tukey test. (P<0.05).
Conclusion and Interpretation :
The present invitro study showed an increase in microhardness of dentin
adjacent to Resin-modified glass-ionomer (RMGI) as compared to compomer,
because of its higher fluoride release and remeniralising capacity.
Key Words : Vicker’s Microhadness (VHN); Class V cavity;RMGI;
Compomer; Remineralisation.
10X
LIST OF ABBREVIATIONS USED
APF : Acidulated Phosphate Fluoride
Ca2+ : Calcium
CT : Computer Tomography
DEJ : Dentino Enamel Junction
FTIR : Fourier Transform Infrared Spectroscopy
G.I.C. : Glass Ionomer Cement
g : Grams
μm : Micrometer
μl : Micro liter
MPa : Mega Pascal
mm : Millimeter
mm2 : Square Millimeter
N : Newton
PH : Figure for expressing acidity and alkalinity
PO4-3 : Phosphate
RMGI : Resin-Modified Glass Ionomer
RPD : Removable Partial Denture
SnF2 : Stannous Fluoride
SEM : Scanning Electron Microscopy
VHN : Vicker’s Microhardness
11XI
TABLE OF CONTENTS
Page No.
1. INTRODUCTION 1
2. OBJECTIVES 3
3. REVIEW OF LITERATURE 4
4. METHODOLOGY 16
5. RESULTS 24
6. DISCUSSION 34
7. CONCLUSION 42
8. SUMMARY 43
9. BIBLIOGRAPHY 44
10. ANNEXURE 50
12XII
LIST OF TABLES
Sl. No. Tables Page
1 Vicker’s Microhardness (VHN) of coronal dentin at 100μm from
cavity floor for group I, II and III at 10th, 20th and 30th day
28
2 Vicker’s Microhardness (VHN) of coronal dentin at 200μm from
cavity floor for group I, II and III at 10th, 20th and 30th day
30
3 Vicker’s Microhardness (VHN) of coronal dentin at 300μm from
cavity floor for group I, II and III at 10th, 20th and 30th day.
32
LIST OF GRAPHS
Sl. No. Graphs Page
1 Vicker’s Microhardness (VHN) of coronal dentin at
100μm from cavity floor for group I, II and III at
10th, 20th and 30th day
29
2 Vicker’s Microhardness (VHN) of coronal dentin at
200μm from cavity floor for group I, II and III at
10th, 20th and 30th day
31
3 Vicker’s Microhardness (VHN) of coronal dentin at
300μm from cavity floor for group I, II and III at
10th, 20th and 30th day.
33
13XIII
LIST OF FIGURES
Sl. No. Figures Page No.
1 Materials 20
2 Instruments 20
3a Light curing Unit (3M,ESPE) 21
3b Digital Micro Hardness Tester (Zwick / Roell) 21
4 Extracted Teeth with class V caries 22
6 After Class V cavity Preparation 22
6 After Restoration 23
7 After Sectioning 23
14XIV
15
Dedicated
To My
Beloved Parents &
Lord Almighty
Introduction
16
Introduction
INTRODUCTION
Knowledge of the hardness of material and dental structure is a valuable
information to the dentist. Measuring microhardness makes it possible to evaluate the
mineral content of the tissues, and to assess whether there was loss of mineral due to
dissolution of the inorganic part, as it occurs during carious process, and also to
quantify the gain in density through a process of ion incorporation (remineralisation).
Hardness is the resistance of a material to plastic deformity typically measured
under an indentation load. There are various tests to check hardness: Barcol, Brinell ,
Rockwell , Shore, Vickers and Knoop. Most commonly used are Brinell, Rockwell
which are macrohardness tests and Vickers and Knoop which are microhardness tests.
Both Knoop and Vickers tests employ loads less than 9.8 N. The resulting
indentations are small and are limited to a depth of less than 19 μm. Hence they are
capable of measuring the hardness in small regions of thin objects. 1 Hardness has
been associated with relative infectivity of carious dentin, helping the dentist to
distinguish, between either infected (soft) or affected(hard) dentin..2
Microhardness is one of the most important physical characteristic for a
comparative study of dental materials. 3.
To know the microhardness of each and every material and that of the tooth
structure is of utmost importance. The microhardness of healthy dentin, carious
dentin and dentin overlying a restorative material varies.
Dental caries is an infectious disease, which causes the local destruction of the
tooth structure of hard tissues and it is associated to diet, microorganisms
accumulation and salivary conditions. Due to frequent ion loss during demineralizing
process, there will be decrease in microhardness.
11
Introduction
When a pH of the oral environment reaches a critical value of 5.5,
subsaturation of Ca2+ & PO4-3 ions occurs. The tendency is thus, the loss of ions from
the teeth to the environment, which is called demineralisation.
When the pH becomes higher than 5.5, through the buffering action of the
saliva, there is a Ca2+ & PO4-3 ions supersaturation in the environment. In this
situation, the tendency is for the teeth to incorporate ions, which is called
remineralisation 4.
Fluoride and other ions have been detected in high concentrations in the dentin
adjacent to GIC restoration and by placing GIC onto demineralised dentin, it resulted
in hypermineralisation of the dentin.5
RMGI cements and polyacid modified resin composites (compomers) claim to
improve the mechanical properties, while retaining the esthetics, adhesion and
enhancing fluoride releasing properties of conventional G.I.C’s. 6
The advantage of using RMGI in this study is, it is less technique sensitive,
fluoride release, stronger than traditional glass ionomer, light cured and finished at the
time of placement.
The advantage of using compomer in this study is, it possesses a combination
of characteristics of both composite and glass ionomer (fluoride release) 7.
22
Objectives
3
Objectives
OBJECTIVES
1. To check microhardness, (VHN) Vicker Hardness of coronal dentin in class V
restoration filled with resin modified glass ionomer restorative material.
2. To check microhrdness (VHN) Vicker hardness of coronal dentin in class V
restoration filled with compomer.
3. To compare microhardness (VHN) Vicker Hardness of coronal dentin in class
V restoration filled with resin modified glass ionomer restorative material and
compomer.
3
Review of Literature
3
Review of Literature
REVIEW OF LITERATURE
The purpose of this study was to investigate the relationship between the
microhardness and calcium content in sound and decalcified enamel. Twenty freshly
extracted human caries-free permanent incisors and premolars and twenty incisor
bovine teeth were selected for this study. They were then subjected to slow
decalcification and etching. Microhardness measurements show that surface layer
covering the lesion possess a significantly greater hardness value than within the
lesion. In the etched enamel, microhardness and calcium content were at lower level
as compared to that of unetched enamel. The hardness in the etched enamel was
reduced to approximately 50% of its original value. This study shows that etching
reduces microhardness of enamel. 8
The purpose of this study was to evaluate the effect of various fluoride
treatments on microhardness of dentin. Fifty mid coronal dentin specimens of 2mm
thick, which were sectioned transversally, were taken from extracted human
premolars. They were then mounted and polished, then subjected to Knoop hardness
test with load of 500 g with help of Tukon hardness tester. Ten specimens was then
subjected for two minutes treatment period with each solution(1) Deionised water pH7
(2) Acidulated phosphate fluoride (APF) solution at pH3.0 containing 0.31% fluoride
(3) APF with PH 4.0(4) sequential treatment with 0.31% F – APF PH4.0 followed by
SnF2. After treatment they were subjected to microhardness testing. The results
showed that, sequential treatment with APF pH4.0 followed by SnF2 produced
significant hardening of dentin.9
The purpose of this study was to determine the relationship between dentin
microhardness and tubule density in normal human permanent teeth. Unerupted third
4
Review of Literature
molars were extracted and stored in phosphate buffered saline. The roots were
sectioned from the crown at the level of cemento-enamel junction. After removing the
pulpal soft tissue with an endodontic broach, 0.1µl of 0.5% tryptan blue or Congo
red dye was placed in the tip of the pulp horn. The dye was allowed to diffuse to the
dentin surfaces, thereby marking a group of tubules from the pulp to the surface. After
the dye had completely diffused through the tubules, the dentin surface were
polished. Microhardness measurements were only made within the dyed zone of
dentin using a Knoop indenter microhardness tester. The results revealed that there is
a highly stastically significant inverse correlation between microhardness and
tubular density. Tubular density increased as the pulp chamber was approached. This
was associated with a decrease in microhardness of dentin, presumably due to a
decrease in the amount of intra-tubular dentin and an increase in individual tubular
diameter. 10
The aim of this study was to examine the time dependency of microhardness
indentations in human and bovine dentin and to make a comparision between these
indentations and similar indentation set in human enamel. Microhardness indentations
were made perpendicular to the sound as well as in demineralised dentin. The
indentations were made with Leitz miniload microhardness tester with a Knoop
diamond indenter at load of 500gram for 10 seconds. From microradiographic
analysis of the samples it was found that there was no correlation between mineral
content and microhardness. The results indicated that for microhardness indentation
measurements in human demineralised dentin, the time dependency should be taken
into account. In human dentin no direct relation was found between hardness and the
mineral content 11.
5
Review of Literature
The purpose of this study was to evaluate invitro effect of glass-ionomer
cement restoration on enamel subjected to a demineralization and remineralisation
model. Expieremental secondary caries was induced around cavities restored with
glass-ionomer cement and composite resin. The effect of these materials was assessed
by microhardness profile. The result showed that G.I.C. has potential value as a
restorative material for the prevention or reversal of caries in enamel adjacent to
restoration, even in situation of high cariogenic challenge. 12
The purpose of this study was to examine intermediate layer between a glass-
ionomer restoration and dentin with the help of Scanning Electron Microscopy (SEM)
and Fourier Transform Infrared Spectroscopy (FTIR). SEM analysis of this study
showed that there was strong bonding between G.I.C and dentin and formation of an
intermediate layer between them. FTIR spectroscopy showed that the intermediate
layer is composed primarily of mineral fluoridate carbonatoapatite. This mineral
presence between dentin and restoration provide high resistence to secondary caries
and may be of clinical importance. 13
The study was done to determine whether glass-ionomer cement could
contribute to the remineralisation of carious lesion in dentin. Small cylindrical
specimens were prepared from freshly extracted bovine incisors, which had incipient
caries-like lesions in the remaining tissue. The control group were filled with
amalgam or composite. The experimental group were filled with GIC. They were
then placed contralaterally in buccal surface of removable partial denture (RPD) that
were worn for 12 weeks experimental period. They were sectioned and analysed by
microradiography. The results showed that specimens with GIC restorations exhibited
hypermineralization in the dentin adjacent to the filling. This study shows that, there
6
Review of Literature
is significant remineralisation potential exerted by fluoride releasing G.I.C. restorative
materials. 14
The aim of this study was to investigate the influence of RMGI on carious
dentine that remains under restorations, when compared to amalgam. Forty patients
with occlusal dentinal caries on molars were taken for the study. After removing the
enamel caries, carious dentin was sampled just beneath the DEJ using a round bur.
Later restored with RMGI or amalgam. Microbiological analysis was done for
determining total viable count (TVC), mutans streptococci (MS) and lactobacilli.
After six months of period, molars were reopened and samples were taken. Then the
cavities were restored with permanent restorations after complete removal of caries.
RMGI showed a significantly larger decrease in count of mutans streptococci and
lactobacilli than amalgam. 15
The study was done to correlate Knoop and triangular hardness numbers by
measuring the microhardness of invitro caries inhibited and demineralised dentin
adjacent to a conventional and two resin-modified glass ionomer cements. Box
shaped cavity measuring 3mm long, 2mm wide and 1.5mm deep were prepared on
bovine root dentin. They were then restored with either Fuji II which is conventional
glass-iononer, Fuji II LC or Vitremer which is RMGI cements. The specimens were
then subjected to decalafication. Knoop and triangular microhardness indentation
were performed perpendicular to the surface and parallel to the cavity wall, in the
demineralised and inhibition zone. The microhardness of inhibition zone created by
conventional glass-ionomer was significantly higher than RMGI cements. This study
concludes that G.I.C were effective in producing an acid-resistant layer.
Microhardness and intensity of acid-resistant layer were material dependent. 16
7
Review of Literature
The main purpose of this study was to evaluate the Calcium, Strontium,
Aluminium, Sodium and Fluoride release profiles from three conventionalG.I.C.
(Ketac Cem, Ketac Bond, Fuji II) and RMGI(Fuji II LC improved). Strontium was
released only from Fuji II which is conventional glass-ionomer and Fuji II LC which
is RMGI, while calcium was released from conventional G.I.C . All four materials
released aluminium and sodium. The study concludes that calcium and strontium
released from G.I.C. may complement fluoride in promoting remineralization. 17
The main purpose of this study was to measure the compressive strength,
flexural strength, microhardnes and surface roughness of compomers and compare the
value with RMGI and resin composite. The study revealed that,RMGI showed lesser
values of compressive strength, flexural strength, microhardness as compared to
compomer and resin composite. Resin composite showed highest values. 18
The purpose of this study was to measure the microhardness values of carious
deciduous dentin and to compare with transparent dentin and sound dentin. Seven
extracted or exfoliated deciduous anterior tooth with dentinal caries on one or both
proximal surface were taken and stored in physiologic saline solution. The sectioned
dehydrated and dried specimens were subjected to miniload 2TM microhardness
tester with Knoop indenter using a load of 15 gram for 15 seconds. The results
showed that microhardness values under caries is significantly lower as compared to
outer and middle region of dentin. There was decrease in microhardness from DEJ to
pulp chamber wall except under caries 19.
The purpose of this study was to compare compomer and RMGI clinically for
marginal adaptation, marginal discoloration , secondary caries, anatomic form, color
match and retention, over a period of two-years. Thirty-four pairs of equivalent sized
8
Review of Literature
abrasion and Abfraction lesion, were restored with compomer and RMGI.
Evaluation of the restorations were clinically done at a baseline, 6,12,18 and 24
months. A significantly higher incidence of failed restorations was found with
compomer. Accordingly to this study RMGI appears to be superior in restoration of
cervical erosion and abfractions 20.
The purpose of this study was to determine tensile properties of human
mineralized dentin. Slabs of dentin were obtained and trimmed to reduce the central
area of the coronal dentin to a cross-sectional area of approximately 0.5mm2 . The
results were statistically analysed. The results revealed that the ultimate tensile
strength of dentin is higher when a load is applied perpendicular to the tubule
orientation (80±13MPa) than when applied parallel to tubule orientation(58±11MPa).
There was a tendency for dentin to be weaker as the number of tubules at the site of
fracture increased, although this relationship was not stastistically significant. It was
concluded that the ultimate tensile strength of dentin is dependent on the tubule
direction. Dentin tends to be weaker as the number of tubules per area increases 21.
The purpose of this study was to evaluate microhardness of dentin after
exposure of two 10% carbamide peroxide bleaching materials and a placebo agent for
42 days of treatment. The microhardness was measured 7 and 14 days post treatment.
The bleaching agents (Opalescence 10% and Rembrandt 10%) and placebo (control)
were applied to the suface of human dentin fragements for 8 hours and then stored in
artificial saliva for the 16 hours each day. Microhardness testing was performed at
baseline, after 8 hours, 7,14,21,28,35 & 42 days of treatment and 7 and 14 days post
treatment. The results demonstrated a decrease in the mean microhardness values of
dentin treated with Opalescence and Rembrandt during treatment period. The
dentinal surfaces treated with placebo exhibited an increase in microhardness values
9
Review of Literature
post treatment. It was concluded that, bleaching agents decreased dentinal
microhardness over time, but after 14 days in artificial saliva storage at the
completion of treatment, the baseline microhardness value were recovered 22.
The purpose of this study was to determine fluoride release from three glass-
ionomer based restorations following multiple daily exposures to three-topical
fluoride regimens. Thirty two cylindrical specimens, each of a glass-ionomer (Ketac
Fil), RMGI (Photac Fil) and compomer (Dyract AP) were prepared. Each specimens
were subjected to various topical fluoride treatments. Later the specimens were
subjected to demineralising followed by remineralising solution. Fluoride levels were
measured using a digital ion analyzer and fluoride electrode. Flouride release
decreased from day 1 to day 3 regardless of fluoride treatment. By day 7, RMGI
demonstrated both the greatest total fluoride release and the greatest rechargability
followed by conventional G.I.C. and compomer 23.
The purpose of this study was to determine the microhardness of superficial
and deep dentin by means of Knoop and Vickers hardness test, under two different
loads. Twelve dentin discs approximately 2mm thick were obtained from both
superficial and deep dentin by transverse sectioning the crowns of sound, extracted
human third molars. They were then subjected to either Vickers hardness test of load
300g on superficial dentin and 500 g on deep dentin or Knoop hardness test of load
100g on superficial dentin and 50g on deep dentin. The results were subjected to
statistical analysis which showed that, microhardness of dentin was influenced by the
different loads applied for both indentation methods. Knoop hardness values of the
superficial dentin was higher as compared to deep dentin. Conversely, Vickers
hardness values for the superficial and deep dentin was not significantly different. 24
10
Review of Literature
The purpose of this study was to compare the effect of twelve month storage
period in water on surface microhardness measured in Vickers unit (VH) between
GIC and RMGI group. The Vickers microhardness was measured in three GIC: Ketac
Fil, Ketac Molar and Ketac Silver and three RMGI: photac-Fil, Fuji LC and Vitremer.
The hardness measurements were done with the help of Vickers diamond indenter
with load of 200g for 20 seconds at 1st, 7th, 15th, 80th, 90th, 180th and 365th day. The
results of this study revealed that GIC group except for Ketac sliver showed higher
VH throughout the study period. Among the RMGI group, Vitremer showed higher
microhardness values as compared to photac Fil & Fuji LC. 3
The study was done to evaluate the physiologic remineralisation of artificially
demineralised dentin beneath glass ionomer cements with or without bacterial
contamination. The artificial demineralised dentin were produced on eighty- four
teeth using demineralising solution. Half of the samples were left open to oral cavity
for one week, later all cavities were filled with Fuji IX and Fuji II LC glass ionomer.
Then samples were subjected to nanohardness testing at 3rd, 90th and 360th day. The
results showed that mean nanohardness of three day samples was significantly lower
that 360 day samples. The mean nanohardness of the bacterial contaminated samples
were significantly lower than non-bacterial contaminated samples. 5
The purpose of this study was to determine and compare the surface
microhardness as well as calcium (Ca) and phosphorus (P) mineral content of sound
and carious human enamel and dentin of primary teeth. Sixteen specimens consisting
of eight sound and eight carious primary molars were prepared for microhardness test,
the indentation were made on centre of enamel, dentin below DEJ (superficial dentin)
and deep dentin (above pulp) using a Vickers hardness tester. With help of Energy
Dispersive x-ray microanalysis, calcium (Ca) & phosphorus (P) contents, near the
11
Review of Literature
indentation were determined. The results were subjected to statistical analysis which
showed that, microhardnes of enamel and superficial dentin on carious primary teeth
was significantly softer than sound enamel and dentin. The calcium & phosphorus
ratio of sound enamel had higher content of calcium than superficial and deep
dentin 25.
The objective of this study was to evaluate the influence of fluoride
concentration of tooth and dental fluorosis severity on dentin microhardness and
mineralization. One hundred and thirty seven extracted human teeth were collected
from three different places with fluoride water levels of 0.2, 0.7 and 1ppm. There was
positive co-relation between dental fluorosis and dentin microhardness. Genetic and
environmental factors influenced mechanical properties and microhardness of teeth,
while only environmental factors influenced their mineralization 26.
The purpose of this study was to evaluate the marginal and internal adaptation
of restorative system in combination with flowable materials as an intermediate layer
in class V cavities. Thirty caries free extracted human maxillary premolars were
selected. Round shaped class-V cavities with 3mm diameter and 1.5mm deep were
prepared. They were then restored with five restorative materials1) compomer.2)
compositeE, 3) Flowable compomer / composite, 4) composite RF 5) flowable
composite/composite RF. The study revealed that the best marginal adaptation in
dentin was obtained by compomer restoration 27.
The purpose of this study was to evaluate remineralization and fluoride uptake
of demineralised enamel specimens in artificial proximal spaces using a 250ppm
fluoride mouth rinse. Twenty-four volunteers who worn intra-oral appliance were
taken for the study. They were asked to rinse and brush their teeth twice daily with
12
Review of Literature
fluoride mouth-rinse and dentifrice respectively, for 28 days. The quantitative light-
induced fluorescence showed a significant remineralising effect of the fluoride mouth
rinse 28.
The purpose of this study was to find the fluoride release and recharge
capabilities and antibacterial properties of fluoride releasing dental restoratives and
their prevention or inhibition of caries development and progression. Results revealed
that the short-term and long term fluoride release from restoratives are related to
their matrices, setting mechanisms and fluoride content and depend on several
environmental conditions. Fluoride releasing materials act as a reservoir and may
increase the fluoride level in saliva, plaque and dental hard tissues. The significance
of this study is that, fluoride releasing materials, predominantly glass-ionomors and
compomers did show cariostatic properties and may effect bacterial metabolism under
simulated cariogenic conditions 29.
The purpose of this study was to compare fluoride release profile of various
restorative materials by using linear regression analysis. Cylindrical specimens were
prepared and immediately placed in artificial saliva, which was replaced at various
times during 6 weeks. Fluoride released was measured by ion selective electrode. The
results were subjected to stastical analysis. The results revealed that, largest fluoride
release was obtained from conventional G.I.C. This was followed by RMGI cement,
compomer and fluoride releasing composite resin. 30
The aim of this invitro study was to evaluate the hardness of dental enamel
after placing a glass-ionomer surface protector cement with increased fluoride
content, a conventional G.I.C and a resin fissure sealent on enamel fissure’s. One
hundred extracted non-carious human molar teeth were divided into five groups. 31
13
Review of Literature
a) Group I : Fissure were conditioned with 20% polyacrylic acid and sealed with Fuji
VII. b) Group II : Fissure were conditioned with 20% polyacrylic acid and sealed
with Fuji IX (High Strength G.I.C). c) Group III : Fuji VII. Directly restored to the
fissures. d) Group IV : After etching with 37% orthoposphoric acid the fissures were
sealed with resin-fissure sealent. d) Group V : Untreated (Control). Half of each
group were stored in artificial saliva for one month other half of the group for three
months. Teeth were then sectioned and Vickers hardness was measured. Hardness
values were increased for all the groups at the end of third month. The results
revealed that concentration of fluoride in G.I.C materials seemed to be effective in
increasing the hardness of the adjacent enamel tissue 31.
The purpose of this study was to examine the effects of fluoride combined
with strontium on enamel remineralisation. Sixty caries free premolors which where
demineralised to induce caries like lesions, was taken for the study. Half of each
lesions were untreated and taken as control group. The specimens were divided into
fluoride and strontium-fluoride treatment groups. These groups were exposed to
remineralising solutions. With the help of contact microradiography, the level of
remineralisation was determined. The results showed that fluoride and strontium
showed a synergistic effect on remineralization 32.
The purpose of this study was to evaluate remineralisation of incipient
artificial interproximal caries-like lesions adjacent to the restorations: highly filled
G.I.C,. compomer, RMGI and resin-composite. Proximal restorations were simulated
by placing tooth specimens and various glass-ionomer cements in closed containers
with artificial saliva at 370C and PH7.0 for 30 days. With the help of micro-CT
14
Review of Literature
scanner, tomographic images were obtained at 90,180,270 days. Density measuring
software was used to calculate microdensity of artificial caries and compare that with
other groups to evaluate remineralisation. G.I.C. showed increased density as time
lapsed. The clinical significance of this invitro study showed that glass-ionomer
restorations can remineralise adjacent tooth structure .33
15
Methodology
16
Methodology
METHODOLOGY
The present invitro study was conducted in the post graduate, Department of
Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital,
Davangere, Karnataka.
Selection of Teeth:
Thirty freshly extracted human permanent molars were collected from the
Department of Oral and Maxillofacial Surgery, Bapuji Dental College and Hospital,
Davangere.
Materials used:
1) Resin Modified glass Ionomer (RMGI) [Vitremer (3M,ESPE)]
2) Compomer (Dyract Flow, Dentsply)
3) Acrylic Resin(DPI-RR Cold cure)
4) Normal saline
5) Abrasive paper (60-100 grit)
Instruments used:
1) Contra angle hand piece (NKS, Japan)
2) Carbide burs (Round/Straight)
3) Explorer
4) Plastic Filling instrument
5) Diamond blade
Equipment used:
1. Light curing unit( 3M,ESPE)
2. Digital Microhardness Tester (Zwick / Roell)
16
Methodology
METHODOLOGY
Thirty freshly extracted human permanent molars with class-V carious
infected lesion, on either buccal or lingual surface were selected. The specimens were
cleaned free of debris and calculus and were stored in normal saline. The teeth with
cavity depth extending more than 2mm, age of the patient, caries involving pulp,
cracks, abrasion erosion, abfraction and tooth with occlusal caries were excluded
from the study.
Caries excavation was done with round carbide bur followed by straight
carbide bur. The cavity preparation for all groups were standardized, with occluso-
cervical width of 2mm, mesio-distal width of 5mm and depth of 2mm from the cavity
margins.. Complete removal of caries was evaluated by visual evidence like
cavitations, surface roughness, opacification and discoloration.
Group I : Control Group : 10 Class V prepared cavity without restoration
Group II : 10 class V prepared cavity, filled with RMGI [Vitremer (3M,ESPE)]
Group III :10 class V prepared cavity, filled with compomer [Dyract Flow
(Denstply)]
After the completion of the preparation, the cavities were cleaned and dried
with oil free air. Over drying was avoided. Group II and Group III were restored
with RMGI and compomer respectively, according to the manufacturers instructions.
After storing the samples in normal saline for 10 days, the samples blotted dry and
embedded in acrylic resin. Dentinal sections of 2mm are obtained at a level of cavity
floor and roof (cross-section) by means of diamond blade. The specimens are ground,
flat and polished with abrasive paper (grit 60-100).
17
Methodology
Vickers microhardness (VHN) measurements were performed by using Digital
Microhardness tester (Zwick / Roell) at 10th, 20th and 30th day under load of 25 grams
for 15 seconds at a distance of 100 μm, 200μm & 300μm from cavity floor.
18
Methodology
STATISTICAL ANALYSIS
Results are expressed as mean + standard deviation. One way ANOVA was
used for multiple comparisons followed by post Hoc Tukey test for group
comparison.
For all the tests ‘p’ value of 0.05 or less was considered for statistical
significance.
Formula Used :
Mean x = i = 1,2,3,…………10
∑ xi n
∑ (xi-x)2
(n – 1) Standard Deviation , SD =
Variance = SD2
One way ANOVA:
F=
Post – Hoc Tukey’s Test:
Highest Significance Difference (HSD)
HSD = tuk tuk: Table value
Between group variance Within group variance
2s2
n
s2 : Within group variance
n : Sample size
19
20
21
22
23
Results
24
Results
RESULTS
The present invitro study with thirty molars was aimed to comparatively
evaluate the Vicker’s microhardness (VHN) of coronal dentin with Resin Modified
glass ionomer and compomer in class-V restorations.
Thirty molars were divided into three groups, each group consisting of ten
samples. Vicker’s microhardness (VHN) value was measured with digital
microhardness tester (Zwick/Roell) at 10th day. 20th day and 30th day under a load of
25 grams for 15 seconds. The indentations were made at distance of 100μm, 200μm
and 300μm from cavity floor.
Table I: Shows Vicker’s Microhardness (VHN) of coronal dentin at 100μm from
cavity floor for group I, II and III at 10th, 20th and 30th day.
Table II : Shows Vicker’s Microhardness (VHN) of coronal dentin at 200μm from
cavity floor for group I, II and III at 10th, 20th and 30th day.
Table III: Shows Vicker’s Microhardness (VHN) of coronal dentin at 300μm from
cavity floor for group I, II and III at 10th, 20th and 30th day.
24
Results
Table 1:
Group I: Class V cavities without restoration (Control)
Group II: Class V cavities with RMGI restoration
Group III: Class V cavities with Compomer restoration
a) Comparison of Vicker’s Microhardness (VHN) between groups at 10th day at
100 µm from cavity floor.
Group I: 40.9(VHN) Group II 54.2(VHN) Group III 50.7(VHN)
b) Comparison of Vicker’s Microhardness (VHN) between groups at 20th day at
100 µm from cavity floor.
Group I: 37.1(VHN) Group II 57.0(VHN) Group III 50.9VHN)
c) Comparison of Vicker’s Microhardness (VHN) between groups at 30th day at
100 µm from cavity floor.
Group I: 39.6(VHN) Group II 59.9(VHN) Group III 52.4(VHN)
When microhardness values were compared between the groups, group II
showed more microhardness followed by group III and least with group I.
25
Results
Table II:
Group I: Class V cavities without restoration (Control)
Group II: Class V cavities with RMGI restoration
Group III: Class V cavities with Compomer restoration
a) Comparison of Vicker’s Microhardness (VHN) between groups at 10th day at
200 µm from cavity floor.
Group I: 42.2(VHN) Group II 54.5(VHN) Group III 52.7(VHN)
b) Comparison of Vicker’s Microhardness (VHN) between groups at 20th day at
200 µm from cavity floor.
Group I: 39.1(VHN) Group II 52.0(VHN) Group III 51.9(VHN)
c) Comparison of Vicker’s Microhardness (VHN) between groups at 30th day at
200 µm from cavity floor.
Group I: 40.4(VHN) Group II :57.3(VHN) Group III 52.6(VHN)
When microhardness values were compared between the groups, group II
showed more microhardness followed by group III and least with group I.
26
Results
Table III:
Group I: Class V cavities without restoration (Control)
Group II: Class V cavities with RMGI restoration
Group III: Class V cavities with Compomer restoration
a) Comparison of Vicker’s Microhardness (VHN) between groups at 10th day at
300 µm from cavity floor.
Group I: 42.6(VHN) Group II 48.4(VHN) Group III 55.2(VHN)
b) Comparison of Vicker’s Microhardness (VHN) between groups at 20th day at
300 µm from cavity floor.
Group I: 40.0(VHN) Group II 46.3(VHN) Group III 53.5(VHN)
c) Comparison of Vicker’s Microhardness (VHN) between groups at 30th day at
300 µm from cavity floor.
Group I: 39.3(VHN) Group II 57.2(VHN) Group III 50.3(VHN
Group II and Group III showed comparably equal microhardness at 300 μm
but more as compared to group I.(Control).
27
Results
Table 1 : Vicker’s Microhardness (VHN) of coronal dentin at 100μm from cavity floor for group I, II and III at 10th, 20th and 30th day
10th Day 20th Day 30th Day
Group I 40.9 + 4.0 37.1 + 2.4 39.6 + 4.9 F = 2.46
P > 0.05 NS
F = 10.9 Group II 54.2 + 2.2 57.0 + 2.3 59.9 + 33
P < 0.01
Group III 50.7 + 2.6 50.9 + 1.8 F = 1.11
52.4 + 3.6 P > 0.05
NS
S
ANOVA ( Analysis Of Variance)
F=52.60 F= 217.0 F= 66.0
P< 0.001 S P < 0.01 S P < 0.01 S
28
Results
Graph 1 : Vicker’s Microhardness (VHN) of coronal dentin at 100μm from
cavity floor for group I, II and III at 10th, 20th and 30th day
40.9
54.2
50.7
37.1
57
50.9
39.6
59.9
52.4
0
10
20
30
40
50
60
Mea
n M
icro
hard
ness
Val
ue (V
HN
)
10th Day 20th Day 30th Day
Group IGroup IIGroup III
29
Results
Table II : Vicker’s Microhardness (VHN) of coronal dentin at 200μm from
cavity floor for group I, II and III at 10th, 20th and 30th day
10th Day 20th Day 30th Day
Group I 42.2 +4.4 39.1 + 3.4 40.4 + 4.3 F = 1.51
P > 0.05
Group II
NS
52.0 + 3.5 57.3 + 4.9 F = 3.77
P < 0.05S 54.5 + 4.2 S
52.7 + 2.8 51.9 + 3.9 52.6 + 2.6 F = 0.14
P > 0.05 Group III NS
F = 27.7 F = 42.9 F = 47.0 ANOVA
P < 0.01 P < 0.01 S S P < 0.01 S
30
Results
Graph II : Vicker’s Microhardness (VHN) of coronal dentin at 200μm from
cavity floor for group I, II and III at 10th, 20th and 30th day
42.2
54.5
52.7
39.1
52 51.9
40.4
57.3
52.6
0
10
20
30
40
50
60
Mea
n M
icro
hard
ness
Val
ue (V
HN
)
10th Day 20th Day 30th Day
Group IGroup IIGroup III
31
Results
Table III: Vicker’s Microhardness (VHN) of coronal dentin at 300μm from
cavity floor for group I, II and III at 10th, 20th and 30th day.
10th Day 20th Day 30th Day
Group I 42.6 + 3.6 40.0 + 1.8 39.3 + 3.7 F = 2.97
P > 0.05 NS
Group II 48.4 + 4.8 46.3 + 5.2 57.2 + 2.1 F = 18.3
P < 0.01 S
Group III 55.2 + 48 53.5 + 4.8 50.3 + 4.9 F = 2.69
P > 0.05 NS
F = 20.3 F = 25.9 F = 57.0 ANOVA
P < 0.01 S P < 0.01 S P < 0.01 S
32
Results
Graph III: Vicker’s Microhardness (VHN) of coronal dentin at 300μm from
cavity floor for group I, II and III at 10th, 20th and 30th day.
42.6
48.4
55.2
40
46.3
53.5
39.3
57.2
50.3
0
10
20
30
40
50
60
Mea
n M
icro
hard
ness
Val
ue (V
HN
)
10th Day 20th Day 30th Day
Group IGroup IIGroup III
33
Discussion
34
Discussion
DISCUSSION
Microhardness is one of the most important physical characteristic for
comparative study of dental materials. 3 The importance of microhardness test lies in
the fact that it throws a light on the mechanical properties of a material. 34 Hardness
of dentin depends on state of mineralisation & location. Hydroxyapatite arranged in
crystal lattice affords the hardness of the healthy tissue. Sound circumpulpal dentin
has got more hardness as compared to dentin adjacent to DEJ. 2
It is possible to evaluate microhardness when there is loss of mineral due to
dissolution of inorganic part as happens during carious process and quantity gain in
density through the process of ion incorporation (Remineralisation). 35.
Hardness has been associated with relative infectivity of carious dentin
helping dentist to distinguish between infected (soft) or minimally affected (hard)
dentin. Changing orientation and density of the tubules from DEJ to the pulpal
interface may play an important part in the differences in hardness found between
these areas in healthy dentin. 2
In several studies teeth used for hardness measurement were fixed or stored in
a formalin solution, physiologic saline solution, deionised water, phosphate buffer
saline or distilled water, as there was no dehydration of the specimens after
sectioning. 19
The microhardness was checked at 10th, 20th and 30th day because after placing
glass ionomer based restoration, there will be a high rate of fluoride release for a
period of 6-12 weeks.36 And fluoride promotes remineralization and inhibits
34
Discussion
demineralization of dental hard tissue. Glass ionomer based restraction are well
known for fluoride release. 33.
The microhardness was checked at 100 μm, 200 μm and 300 μm from the
cavity floor. The reason behind this is, there will be ion exchange between restoration
and tooth structure and remineralisation of adjacent tooth structure 36.
The influence of fluoride is found in a zone of resistence to demineralization
which is atleast 3 mm thick around G.I.C. This favourable result has been attributed
to the release of fluoride from the cement and its movement into adjacent tooth
structure. The ionic radius of fluoride ion (1.36A0) is similar to that of hydroxyl ion
(1.40A0) and this has important consequences because the fluoride ion can replace the
hydroxyl ion in the apatite lattice 37.
Vickers and Knoop hardness tests seem to be preferred choice of test among
majority of the investigators 19,38.
Vickers microhardness testing (VHN) was done with Digital microhardness
tester (Zwick/Roell). Load of 25 grams was applied through the indentor with a dwell
time of 15 seconds. 38
Conventional G.I.Cs were introduced to dental profession by Wilson and Kent
(1972), RMGI was introduced in 1988 3 and compomers in 1990’s 39.
GIC’s are glass - polyalkenoate cements. They are a true acid base material,
where the base is a fluoroaluminosilicate glass with high fluoride content, and this
interacts with poly (alkenoic acid). Following mixing of the two components,
calcium polyacrylate chains form quite rapidly and develop the initial matrix that
holds the particles together. Same way aluminium polyacrylate chains forms which
35
Discussion
are less soluble and stronger. At the same time some of the fluoride is released from
the glass in the form of micro droplets that lie free within the matrix. More fluoride is
retained in the matrix, bonded to aluminium and most of the subsequent fluoride
release is the result of ion-exchange reactions. Glass ionomer in any form, can be
regarded as a fluoride reservoir. Fluoride represents approximately 20% of the final
glass powder, following mixing, the fluoride becomes available from matrix more
readily than from the original glass particles.36 Fluoride promotes remineralisation and
inhibits demineralization of dental hard tissue. 33
Conventional GIC’s presents several important properties expected from ideal
restorative materials such as fluoride release; coefficient of thermal expansion and
Modolus of Elasticity similar to that of dentin, bonding to both Enamel and Dentine.40
low solubility, high opacity, anticariogenic, retention at cervical area (75%) as
compared to composite. 41
Fluoride release detected through various methods like: Spectrophotometry or
fluorometry, fluoride ion specific electrode, Gas chromatography, Aluminium
mono fluoride molecular absorption spectrometry (Al F MAS), Secondary ion mass
spectrometry (SIMS), Proton - induced x-ray emission (PIXE), Proton – induced
gamma – ray emission (PIGE), Electron probe microanalysis (EPM), and x-ray
induced photoelectron spectroscopy (XPS also called ESCA).42
Fluoride and other ions have been detected in high concentration in dentin
adjacent to GIC restorations and by placing G.I.C onto demineralised dentin, it
resulted in hypermineralisation of the dentin. 5
36
Discussion
The main disadvantages of conventional GIC are: Suscepetibility to
dehydration,43 less setting time, less esthetic, technique sensitivity 23 and reduced
occlusal wear resistance. 44
The reason for using RMGI in this study, because of caries inhibition and
fluoride release similar to conventional GIC, 33 better esthetics, adhere to tooth
structure and possess the capacity to inhibit both in vivo and in vitro secondary caries,
16 less sensitive to water dehydration and dissolution because of rapid setting; better
rechargeablity, 23 finished at time of placement, stronger than traditional G.I, light
cured to depth of 2.7 mm,7
RMGI powder components consist of ion-leachable fluoroalminosilicate
glass-particles and initiators for light curing and or chemical curing. The liquid
component usually contain water and polyacrylic acid or polyacrylic acid modified
with methacrylate and hydroxyethyl methacrylate (HEMA) monomers. The initial
setting reaction of the material occurs by polymerization of methacrylate groups. The
slow acid base reaction will ultimately be responsible for the unique maturing process
and the final strength.1
The reason for using compomer in this study is because of structure and
physical properties similar to those of composite, fluoride release, bond strength to
tooth structure similar to conventional GIC, light cured upto 4.7mm, 7 better
compressive strength and flexural strength, 18 when used in class V restoration
provide better marginal adaptation to dentin than composite. 27
Compomer is usually provided as a one paste system. It consist of silicate
glass particles, sodium fluoride and polyacid modified monomer without any water.
Setting is initiated by photo polymeristion of the acidic monomer that yields a rigid
37
Discussion
metarial. Acid base reaction is induced by water absorption through saliva, that
eventually sustains fluoride release. 1
RMGI and compomer claim to improve the mechanical properties while
retaining esthetic, adhesion and fluoride release. 6
Group I: Class V cavities without restoration (Control)
Group II: Class V cavities with RMGI restoration
Group III: Class V cavities with Compomer restoration
Group I : “ Class V Cavities without Restorations” (Control):
This group showed no significant changes in Vickers microhardness (VHN)
upto 30th day and at 100,200,300 μm from cavity floor. Caries results in
demineralization of inorganic substance followed by dissolution organic substance
resulting in loss of tooth structure. There will be loss of mineral content from the
demineralised dentine 7 studies have been reported that in both deciduous and
permanent dentin, the hardness of the peripheral dentin was lower than that of central
dentin, and the hardness of the pulpal dentin was lowest. Lower hardness values, 100
to 200 μm from DEJ were also reported, probably due to the presence of mantle
dentin. Hardness values of dentin decrease with distance from DEJ. Central area of
coronal dentin is harder than peripheral dentin.19
Group II: Class –V cavities restored with RMGI:
The results showed that, an increase in Vicker’s microhardness (VHN) by the
end of 30th day. Reason for this:
38
Discussion
Remineralisation, has received considerable attention during the past decades
and has become one of the cornerstones of the fluoride treatment strategy. The
phenomenon of remineralisation was first described by Head in 1909.45 Fluoride
promotes remineralization and inhibits demineralization of adjacent tooth structure. 33
Enzyme alkaline phosphatase present in dentine increases the concentration of
phosphates and these combine with calcium taken up from tissue fluid to form
calcium hydroxyapatite.46 The lost calcium from calcium hydroxyapatite is replaced
by fluoride which results in formation of fluorohydroxyapatite which is less soluble as
compared to hydroxyapatite.45 Fluoride, Strontium and Calcium released from glass
ionomer based restoration helps in remineralization of adjacent tooth structure 5,14,17,45
There is an constant increase in fluoride release over a period of 6 weeks with RMGI
30 and the release is equal to or higher than conventional GIC. 6,33
Group III: Class V cavities restored with Compomer.
The results of this group showed no significant changes in Vickers
microhardness (VHN) upto 30th day and at 100,200,300 μm from cavity floor. The
microhardness values (VHN) was significantly lower than group II. The reason
behind this:
As we know fluoride helps in remineralization of adjacent tooth structure
5,14,17,33. The rate of fluoride released from compomer decreases over time.33 Fluoride
release from compomer is less as compared to RMGI and GIC.6,18,23 This is because
of low fluoride release, limited acid base reaction6,40 and also due to presence of
lesser amount of glass ionomer. 41
39
Discussion
Group II vs Group III:-
When Vicker’s microhardness (VHN) was compared between group II and
Group III. Group II i.e., class – V cavities restored with RMGI showed more hardness
values. The reason for this: As we know, fluoride promotes remineralisation and
inhibits demineralization of dental hard tissue.33 The lost calcium from calcium
hydroxyapatite, is replaced by fluoride resulting in formation of flruorohydroxyapatite
which is less soluble as compared to hydroxyapatite.45 Other than fluoride, calcium
and strontium released from glass ionomer based restoration results in
hypermineralisation of adjacent tooth structure 5,14,17,45 The fluoride released from
RMGI is high or equal to that of conventional G.I.C. 6,33
The fluoride release from compomer is less as compared to RMGI 6,23,33,40. As
the rate of fluoride release from compomer decreases over time, the remineralisation
affect also decreases with time.33 The chemistry behind the decrease in fluoride
release with compomer is because of limited extent of the acid base reaction. 40
Because of the lower amount of glass ionomer present in compomer, the amount of
fluoride release are lower than that of glass ionomer & RMGI. 41
There was decrease in microhardness at 300 µm at 10th , 20th and 30th day for
group II and group III, this is because, there is ion exchange between restoration and
tooth structure and remineralization of adjacent tooth structure. The influence of
fluoride is found in a zone of resistence to demineralization which is atleast 3mm
thick around GIC. This favourable result has been attributed to the release of fluoride
from the cement & its movement into adjacent tooth structure. 36 ,37
40
Discussion
Limitations of the Study
1) There is a question about the long term action of these materials (RMGI and
compomer), because microhardness measurements were taken for 1 month
period of study.
2) It is known that glass ionomer cements can function as a fluoride reservoir and
can reaptake fluoride from the oral environment again, thus recovering its
anticariogenic action with time.
3) Drawbacks of using Vicker’s microhardness
a) Measures the hardness after indentation is removed.
b) Resolution variations of optical system
c) Perception of operator
d) Elastic recovery of material after the load is removed.
4) The present study was done invitro, therefore not truly mimicking the true oral
environment.
Recent advances are available at present for checking the microhardness like
Martens hardness test. It is also possible to quantify the mineral content present in
dentin. The further research is carried out to check the microhardness variation with
other resent biomaterials.
41
Conclusion
42
Conclusion
CONCLUSION
On the basis of the study carried out, the results obtained using RMGI and
compomer in class-V cavities and their effect on microhardness of dentin, shows that:
Resin modified glass ionomer (RMGI) showed increase in microhardness of
dentin as compared to compomer and control group (class-V without restoration).
So this shows the use of biomaterials with improved mechanical properties
like flexural strength and fluoride release enhances the structure and microhardness of
dentin.
42
Summary
7142
Summary
SUMMARY
Microhardness is one of the most important characteristic for comparative
study of dental biomaterials. As we know fluoride promotes remineralisation of dental
hard tissue and inhibits demineralization. GIC are well known fluoride releasing
restorative material. But conventional GIC are susceptible to dehydration, less
setting time, less esthetic and reduced occlusal wear resistance.
The present study was yet another effort to solve this whelming problem and
in this study, we have used improved quality of glass ionomer based restoration.
The aim of the present study was an invitro comparative evaluations of
microhardness of coronal dentin with RMGI and compomer in Class V restoration.
Thirty freshly extracted human permanent molars with Class V carious
infected lesion were selected and stored in normal saline. Class V cavity preparation
for all groups were standardized with occluso-cervical width of 2mm, mesio-distal
width of 5mm and depth of 2mm from cavity margins. Group I (n=10) : class V
cavities without restoration (conrol), Group II (n=10) Class V cavities with RMGI
and Group III, Class V cavities with compomer.
After storing the samples in normal saline for 10 days, the samples bottled dry
and embedded in acrylic resin. Sectioning was done and then subjected to
microhardness measurements by using digital microhardness tester (Zwick / Roell) at
10th, 20th and 30th day under load of 25 grams for 15 seconds at a distance of 100 μm,
200μm and 300 μm from cavity floor.
The data was recorded and submitted to statistical analysis. The results
showed, an increase in microhardness of dentin adjacent to RMGI as compared to
compomer. And the control group showed the least valves of microhardness of dentin.
724243
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734243
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49
Annexure
50
Annexure
ANNEXURE
Days Distance from
cavity floor (µ m) Groups 10th Day 20th Day 30th day
100 40.9 + 4.0 37.1 + 2.4 39.6 + 4.9
200 42.2 + 4.4 39.1 + 3.4 40.4 + 4.3 Group I
300 42.6 + 3.6 40.0 + 1.8 39.3 + 3.7
100 54.2 + 2.2 57.0 + 2.3 59.9 + 3.3
200 54.5 + 4.5 52.0 + 3.5 57.3 + 4.9 Group II
300 48.4 + 4.8 46.3 + 5.2 57.2 + 2.1
100 50.7 + 2.6 50.9 + 1.8 52.4 + 3.6
200 52.7 + 2.8 51.9 + 3.9 52.6 + 2.6 Group III
300 55.2 + 4.8 53.5 + 4.8 50.3 + 4
5150
52
53
54