i
EFFECT O F DI FFE RENT FI NISHI NG AND POLISHI NG TECHNIQUES ON THE SURFACE RO UGHNESS O F FO UR CE RAMIC MAT ERIALS AFTER
SURFACE ADJUST MENT
S ILV IA P. AMAYA -PAJ ARES
A thesi s s ubmitt ed to the Facult y of T he Universit y of North Carolina at Chapel Hill i n parti al ful fill ment of the requirem ents for the degree of M ast er of Sci ence in the D epartment of Operati ve Denti str y at t he School of Dentist r y
Chapel Hil l 2014
Approved by:
Terence Donovan
André Ritter
ii © 2014
iii
ABSTRACT
S ILV IA P. AMAYA -PAJ ARES: Effect o f Different Fini shing and Pol ishi ng Techniques on the S urface Roughness o f Four Cerami c M at eri als a ft er Surface
Adjustm ent
(Under the direction of Terence Donovan)
Pu rpose: To m easure and compare t he surface roughness of glazed and poli shed monolit hi c cerami c mat eri al s wi th t he s urface roughnes s produced b y di fferent
intraoral pol ishi ng s ys tems on adj ust ed monolit hi c ceramic mat eri al s. Materials and Meth ods : Mill ed cerami c di sks ( 10mm di am et er x 2m m thickness ) were manufactured and di stribut ed according t o the following groups (n=10): Brux Zir
(gl azed and poli shed), Zenost ar (gl az ed and polished), IPS Empress and IPS
e.m ax. Surface roughness , express ed as Ra and RMS val ues, was m easured
using AFM and profilometer before and aft er adj ustm ent and poli shing with the
foll owi ng int raoral polis hing s ys t ems : Brux Zi r and Di alit e ZR (for BruxZi r) ,
Zenost ar and Di alit e ZR ( for Zenost ar), and OptraFine and Dialite LD for IPS
Empress and IPS e.m ax Mean and st andard error for each m at eri al and polis hing
s yst em w ere cal cul at ed. Dat a w ere anal yzed with T-t est , one-wa y ANOVA, and
Bonferroni pos t h oc tests . Results: In general, all mat eri als present ed a
smoot her surface at bas eline than aft er adjus tment an d polishing. The AFM
results showed that bas eli ne values were no t si gnifi cant l y di fferent among t he
iv
Brux Zi r Polis hed was polis hed wit h Dialit e ZR when compared to Brux Zi r
S ystem and IPS e.m ax specim ens were adj ust ed and polished with OptraFi ne
S ystem in compari son to Di alit e LD S ys t em. St atisti call y s i gnifi cant di fference
was found i n Zenost ar Gl az ed and IPS Empress groups (p<0.005) and lower Ra
and RMS values were found usi ng the Zenost a r polis hing s ys tem in Zenost ar
gl az ed respectivel y.
The profilomet er res ults s howed t hat the Ra and RMS bas eline val ues of Brux Zi r
polished and Zenost ar polis hed were si gni ficantl y lower than all other mat eri als.
Aft eradjustment and polis hing, Brux Zir polis hed and Brux Zi r gl azed specim ens
pres ent ed si gni fi cant difference (p<0,005) and l ower RA and RMS values when
Dialite Zr was used com pared t o Brux Zi r .
Con clusion s: Brux Zir zirconia result ed in a sm oother surface w ith Di alit e ZR polishing s ys t em compar ed t o BruxZi r poli shi ng s ys t em, Zenost ar zi rconi a
produced a smoother surface with Zenost ar polishi ng s yst em compared to Di alit e
ZR polis hing s yst em and IPS Empress CAD and IPS e.m ax CAD pres ent ed a
smoot her surface wi th Opt raFine pol ishi ng s yst em i n comparison to Di alit e LD
polishing s ys t em. The AFM compl em ents the Profil om eter information and
v
To m y parents R afael and Emperat riz for thei r unconditional l ove and support
throughout m y l ife. Thank you both of you for gi ving m e t he strength and
encourage m e to reach m y goals and al ways beli eve i n m e.
To m y beloved s ist er Carm en for her endl ess support and for being an
exceptional fri end.
To t he memor y of m y grandparents Absal ón and J ulia w ho have been excell ent
exampl es of hard work and dedicati on
To m y aunt ies P att y, Vi ck y, Viol e, Vil a and Elmira for their cari ng and l ove,
vi
ACKNOWLE DGE MENTS
I woul d li ke to thank m y thesis advi sor Dr. Te rence E. Donovan for his
guidance as well as his tim e during all t his process.
I would like to express m y appreci ation to the com mitt ee members Dr.
André Ritt er and Dr. Timot h y W ri ght for thei r tim e, us eful comm ents and
rem arks for improving thi s res earch.
Speci al thanks to Dr. Haral d He ym ann for suggesting t his topi c as a thes is
research and Dr. Edward Swi ft for al l owing the financi al support for this
research from t he Operati ve Departm ent.
I would l ike to thank Dr. C arolina Vera for hel ping me to devel op the
proj ect and for bei ng an ex cell ent fri end duri ng thes e three ye ars.
I would li ke to gratefull y thank Mr. Brett Henson for hi s help and support
as a res earch assis tant , all your tim e invested in thi s research is well
-appreciat ed.
I als o would li ke to t hank Ms. C arri e Donle y, Mr. Am ar Kumbhar and Mr.
Bob Geil and Chapel Hill Anal yti cal and Nanofabri cation Laborator y Instit ut e
vii
techni cal support i n the us e of the Atomi c Force Micros cope and
Profilom et er that were required in thi s research.
I would like to express m y great appreciation to Dr. Chait an ya P uranik
and Mr. Domi nik Rei nhold for thei r hel p with the dat a anal ys i s.
I thank Dr. Lee Boushell, Dr. John S t urdevant, Dr. J am es Par ker, Dr.
Andrea Zandona, Dr. Scot t Eidson, Dr. Ken M a y and Dr. R ick W alt er, it has
been a pl easure being part of t he Operati ve Denti str y Famil y.
I woul d li ke to express s peci al appreci ati on t o the st aff of the Department
of Operat ive Dentist r y, M rs. Shanno n Tate, Mrs. Da yna M cNaught, Mrs. J amie
Desoto, M rs . Barbara Walt on, Mrs. C ynthi a Lambert and M rs . R osanna
Arrington, for all t heir assi st ance provi ded during t hese years .
M y s peci al t hanks are extended to Mr. Lee Cul p and Microdent al
Laborat ori es for prov iding t he speci mens used in thi s res earch as well as t he
techni cal support.
I woul d like t o offer t hanks to t he com panies Ivocl ar -Vivadent and
Brass eler US A for providi ng t he m ateri als needed for the res earch.
I would li ke t o thank Al ex Del gado and Sumitha Ahm ed who have been
viii
unforget table mom ents, as well as have exchanged our experi ences and expertis e
that al lowed us to learn from each ot her.
Finall y, I als o would like to thank m y co -residents A yesha Swarn,
Roopsi e Kaur, Hi roko Nagaoka, Krist y Erickson, Fernando Astorga, Upoma
Guha, Vil hel m Ol afsson, Cl a yt on Rau, Mohamm ad Ati eh, Taneet Ghum an
Anm ar Kens ara and Tai seer Sulaiman who contri but ed all thi s years to have an
extraordinar y expe ri ence.
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TABLE O F CONTE NTS
LIS T OF TABLES ... x i
LIS T OF FIGUR ES ... x ii
LIS T OF ABBR EV IAT IONS ... xiv
1. CHAP TER 1: INTRODUC TION ... 1
LITER ATURE R EV IEW ... 2
1.1 Dental cerami cs ... 2
1.1.1 IP S Em pres s C AD ... 2
1.1.2 IP S e.m ax CAD ... 3
1.1.3 Zirconia ... 3
1.2 CAD/C AM Technol ogi es ... 5
1.3 Finishi ng of ceram ic restorations ... 5
1.4 Adjusting and pol ishing m at erial s for cerami cs ... 6
1.4.1 Coat ed abrasi ve devices or di am onds ... 9
1.4.2 Bonded abrasi ve devices or rubber, el asti c finis hing and poli s hing devi ces ... 9
x
1.5 Facto rs that i nfl uence finis hing and poli shing procedures ... 10
1.6 Met hods t o ass es s surface roughnes s ... 12
1.6.1 Atomi c Force Microscope ... 12
1.6.2 P rofilom et er ... 12
1.7 R oughness param et ers ... 13
1.7.1 Ra ... 13
1.7.2 RMS ... 13
2. CHAP TER 2: M ANUSCR IPT ... 14
2.1 Int roduction ... 14
2.2 Mat eri als and m eth ods ... 16
2.3 Stati sti cal Anal ys is ... 20
2.4 Res ults ... 21
2.5 Dis cussion ... 22
2.6 Limit ati ons ... 25
2.7 Conclus ions ... 26
3. TABLES ... 27
4. F IGURES ... 30
xi
LIST O F TABLES
Table 1. The rel ative hardness of rest orati ve mat eri als
and abrasive compounds (using Moh’s hardness scale) ... 27
Table 2. Cl assi fi cat i on of dent al cerami c mat eri al s ... 28
xii
LIST O F FI GURES
Fi gure 1. C omputer desi gn of t est disks ... 30
Fi gure 2. S pecim ens distribut ed in groups ... 31
Fi gure 3. S pecim en . A: s urface wit h final treatm ent B. Back of t he specim en wit h a num ber assi gned ... 32
Fi gure 4. AFM and P rofilom et er scan l engt h ... 33
Fi gure 5. S pecim en s howi ng 3 s urface measurem ents recorded at t he center of the s ampl e ... 34
Fi gure 6. Atomic Force Mi cros cope (AFM) As yl um R es earch MFP -3D ... 35
Fi gure 7. Di fferences between AFM and Profilom et er tips ... 36
Fi gure 8. P rofil omet er K LA -Tencor P -6 ... 37
Fi gure 9. Devi ce to monitor pressure ... 38
Fi gure 10. Flowchart of group di stributi on and surface roughness recordings .. 39
Fi gure 11. OptraFi ne S yst em P rot ocol ... 40
Fi gure 12. Di ali te LD S ys tem Protocol ... 41
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Fi gure 14. Di ali te ZR S yst em P rot ocol ... 43
Fi gure 15. Brux Zir S ys tem Protocol ... 44
Fi gure 16. M ean Bas eline R a (nm) values with At om i c Force Micros cope ... 45
Fi gure 17. M ean R a (nm ) val ues with Atomic Force Mi cros cope
aft er adj ustm ent and polis hing ... 46
Fi gure 18. M ean Bas eline R MS (nm ) val ues with At omi c Force Mi cros cope .... 47
Fi gure 19. M ean RMS (nm ) values with Atomi c Force Micros cope after adj ustm ent and polis hing ... 48
Fi gure 20. M ean Bas eline R a (µm ) val ues with Profi lom et er ... 49
Fi gure 21. M ean R a (µm) values wit h P rofilom et er aft er
adj ustm ent and polis hing ... 50
Fi gure 22. M ean Bas eline R MS (µm) values with Profi lom et er ... 51
Fi gure 23. M ean RM S (µm ) values wi th P rofilom et er
aft er adj ustm ent and polis hing ... 52
Fi gure 24. R a Bas eli ne values with Profil omet er ... 53
Fi gure 25. R a values with Profi lom et er after polishi ng
xiv
LIST O F ABB REVI ATIO NS
CAD: Comput er assi sted desi gn
CAD-CAM: Comput er aided desi gn – C omput er ai ded m anufacturing
AFM: Atomi c force m icros cope
Ra: Arithm eti c average hei ght
RMS: Root m ean s quare roughness
N: Newton
nm: nanometers
µm: micromet ers
1
CHAPTER 1: I NTRODUCTIO N
The us e of ceramic restorations has increased ext ensi vel y over the past
years due to a hi gh dem and of estheti cs by pati ents .1
The final occl us al adj ustm ent of t he cerami c rest orati on with abrasi ve
rot ar y i nst rum ent s has to be m ade aft er cem entat ion, and this procedure
creat es a rough surface, whi ch can facilit at e bi ofi lm accumul ation producing
gi ngi val infl amm ati on or can increase t he wear of t he opposing enam el or
other rest orative material . Furthermore, a sm oot h surface i s import ant for
pati ent s com fort2.
The surface roughness of restorative m at eri als should be minimized to
contribute to the patient’s comfort, optimum esthetics, oral hygiene and
provide clini cal success, and this is why t here is al wa ys need for int raoral
2
LITERATURE REVIEW
1.1 Dental cerami cs
Dental cerami cs consist of sili cat e gl ass es, porcel ains , gl ass -ceramics, or
hi ghl y cr ys t alline solids . Dent al ceramics are nonm et al lic, inorganic
struct ures t hat mai nl y cont ai n compounds of ox ygen wit h one or more
met alli c or semi -m et alli c el em ent s (al uminum , boron, cal cium , cerium,
lithium , m agnes ium, phosphorus, pot assi um, s ilicon, sodium , titanium , and
zirconium )3.
1.1.1 I PS E mpres s CAD
IP S Empres s C AD is a leuci te -rei nforced glass -ceram ic block for
CAD/C AM t echnology. The IPS Empress CAD i s an estheti c mat eri al , which
can be found wit h hi gh and l ow translucenc y levels, and pres ents a fl exural
strength of 160 MP a. According to t he manufacturer this mat eri al can be
used in singl e-t oot h restorations s uch as veneers, inl a ys , onlays , ant erior and
post erior crowns. The com pos ition of IP S Emp ress CAD corresponds to that
of t he well -proven IPS Empress, whi ch has been in cli nical use for m ore
than 15 years. The manufacturing process has been adjusted and optimiz ed.
The mi crost ructure of IPS Empress CAD consists of a gl ass y m at rix and
3
distribut ion of l euci te cr ys t als. The l eucite cr ys t als are evenl y and densel y
distribut ed. The di amet er of the cr yst al s is 1 -5µ m, and the cr yst al phas e
volum e i s 35 -45% b y volume. Leucit e is t he resul t of s urface cr yst alliz ation.
1.1.2 I PS e.max CAD
IP S e.m ax CAD is a lithium disili cat e gl ass -cerami c block for CAD/CAM
technology. In i ts cr yst alli ne int ermedi at e st at e (blue), the block can be
easil y mill ed with C AD/C AM equi pm ent . Aft er the IPS e.m ax CAD b locks
have been mill ed, t he m at erial is cr yst all ized i n a cerami c furnace.
The blocks do not shrink si gni fi cantl y. The cr ys tallizat ion process caus es
the mi crost ructure to change t hrough controll ed growth of lit hium disili cat e
cr ys t als . The trans formatio n of the microst ructure produces t he final
ph ysi cal properti es i ncl uding 360MP a fl exural s trength and s uitable opti cal
charact eri sti cs s uch as s hade, t ranslucency and bri ghtness . This mat eri al can
be used to fabri cat e veneers, part ial crowns and anterior a nd post erior
crowns.
1.1.3 Zi rconia
Zirconia is one of t he m ost studi ed ceramic m at erial s in the world. This
mat eri al is st ronger and tougher than most other cerami c mat eri al s us ed in
dentist r y4. An import ant propert y of zirconi a is its transform ati on
toughening and it s abili t y to slow crack propagation and improve fracture
4
Zirconia, s peci fi call y yt t rium -st abilized tet ragonal zirconi a pol ycr ys t al
(Y-TZP), was chos en as a subst ructure m aterial . It has a range of i ndi cations
and it i s veneered wi th gl ass y cerami c.3 - 5
The m ajor complications of t hese res torations are the possibi lit y of
fracture or chi pping of the cerami c veneer. Thes e problems ma y b e
att ributed to t he m is mat ch of t he coeffi cient of t herm al expansion be tween
the zi rconi a and t he veneered porcelain, strength of the porcelain to zi rconi a
bond, fram ework surface treatm ent s, porcel ai n and zirconi a t ypes ,
fabri cation m ethods, the relati vel y low t herm al conductivit y of zirconi a, and
the rel ativel y low el asti c m odulus of zirconi a4 , 6 - 1 0.
As a propos al for overcomi ng t he chi pping compli cation, CAD/ CAM
fabri cat ed a non -veneered, monolithi c zirconi a mat eri al. R estorations wit h
this mat eri al have becom e ver y popul ar. To achi eve acceptabl e estheti cs,
pre-stained zi rconi a and shading liqui ds are avail abl e. The m onolithi c
zirconi a mat eri al has hi gher fracture toughness than veneered zirconia
restorations. One concern ass ociat ed wi th the us e of monolithi c zirconi a
restorations is the possibl e abrasiveness of the mat eri al t owards enam el3.
Depending on the parti cle -siz e dist ribut i on of t he zi rconi a and the amount
of grinding perform ed t o adjust the occlus ion, the surface ma y be ver y
diffi cult to grind and polish and intraoral fi nishi ng and poli shing m a y t ak e
si gni fi cant chai r tim e. This m a y res ult i n a rough surface t hat can produce
5 1.2 CAD/ CAM T ech nolog i es
The advances i n dent al cerami cs m at eri al s and process ing techniques such
as com put er -aided desi gn (CAD)/ computer -aided manufact uring (CAM ) and
milling t echnology have im proved the qualit y of dent al ceram ics. Ti ghtl y
controlled indust rial ceramic proce ss ing produces increas ed microst ructural
uniformit y, hi gher densi t y, l ower porosi t y, and l es s resi dual stress es . All
thes e im provements have the pot enti al to provide more clinical predi ctabilit y
of t he res torati ons3 , 1 1.
Initi al C AD/C AM s ys tems produced res torations that had poor m arginal
fidelit y due to low resolution scanning devi ces and defi cient computing
power1 1.
Technologi cal im provem ent s in new s ys tems and software devel opm ent
reduced or el iminat ed previous probl ems so that good margi nal int egrit y can
be anticipated3 , 1 1.
1.3Finishing of cerami c restorations Defini tions:
Glaz e: 1: To cover with a gl oss y, s mooth surface or coati ng 2: the att ainm ent of a sm ooth and refl ecti ve surface 3: the fi nal fi ri ng of porcel ai n in which the surface is vit ri fi ed and a hi gh gl oss is im part ed to the m at erial
6
Autogl aze: the production of a gl azed surface b y raisi ng t he t emperature of a
cerami c t o creat e surface flow1 2.
Nat ural glaz e: The product ion of a gl az ed surface b y the vitrifi cat ion of t he
mat eri al its el f and without additi on of ot her fluxes or glasses1 2.
Overglaz e: t he producti on of a gl az ed surface b y the addi ti on of a fl uxed
gl as s that us ual l y vit rifies at a l ower t em perature1 2.
Polishi ng: t o m ake s mooth and gloss y us uall y b y fri cti on1 2.
Jagger investi gated the wear effects of gl azed, ungl azed, and pol ished
porcel ain (Vit a, Vit adur N) agai nst human enam el in the laborator y b y us e of
a wear machi ne desi gned to simul at e the masti cator y c ycl e. The result s from
this st ud y s ugges ted that t he am ount of wear of enam el caused b y gl azed and
ungl azed porcel ain was simi lar. Duri ng the wear tes t, t he gl aze was removed
aft er a rel ati vel y short peri od of wear (2hours). Polished porcel ain produced
subst ant ial l y l ess enam el wear. Thi s stud y indi cat ed the pot enti al dam age
porcel ain can produce upon enam el and suggest ed that porcel ain should be
polis hed instead of regl azed aft er chai rsi de adjustm ent1 3.
1.4Adjus ting and p olis hing material s for ceramics
Normal l y ever y rest oration needs to be adjusted, so gri ndi ng, finis hing
and polis hing procedures are requi red. The main purpos e of thes e procedures
7
The m ain benefi ts of finis hing and polis hing of res torat ive mat eri al s are
thought to be: bett er gingival healt h, chewing effici enc y, pati ent com fort,
estheti cs and wear.
A sm oother s urface provides less retenti on of pl aque, and it is easi er to
maint ai n b y the pati ent and the dentist. Also, oral function i s enhanced wit h
a well -polis hed res toration si nce food can glide more freel y over the
occlus al and embrasure areas during masti cation. Furthermore, smooth
restoration surfaces minimize wear rat es on opposi ng and adj acent t eet h.
This is import ant in materi als that are harder than tooth enamel and denti n
such as cerami cs .
Different t ypes of i nstrum ents are used in dentist r y d epending on the
mat eri al t hat needs to be adjus ted and polis hed. The inst rument s availabl e
for finis hing and pol ishing rest orati ons i ncl ude carbi de burs, diam ond burs,
stones, coat ed abras ives , polishing past es, soft and hard pol ym eri c cups,
point s, and wh eel s impregnat ed wi th specifi c t ypes and siz es of abrasi ve
parti cles.
Gri nding:
Gri nding instrum ent s cont ain randoml y arranged abras ion parti cles. Each
parti cle m a y cont ain several s harp points that run al ong the mat eri al surface
and remove particles of i t. For inst ance, a di am ond -coat ed rotar y i nst rum ent
ma y contain m an y sharp di amond parti cl es that pass over a cerami c m ateri al.
8
produced on the surface of the mat eri al. A coars e d i am ond bur removes
mat eri al more quickl y, but l eaves a rougher surface.
Manufacturer’s instructions should be followed to adjust and polish in order
to minim ize t he tim e requi red. S ometim es, inst rum ents used in dent al lab
ma y be di fferent from those us ed c hai rsi de.
Finishi ng:
Finishi ng has the objective of i ntroducing finer s crat ches to the surface of
the adj ust ed m at erial to remove deeper scrat ches . The finis hing action is
usuall y accom plished usi ng fine and superfine di amond burs.
Polishi ng:
The purpos e of the polis hing is t o provide an enam el -like luster t o the
restoration. Sm all er parti cles provide sm oother and shi nier s urfaces. Lust er
can be ass es sed without magni fi cat ion, and to obt ain this wil l depend on the
hardnes s and size of the abrasi ve parti cl e s and the m et hod of abrasion.
Polishi ng is obt ained from the finest abrasive that can rem ove scratches and
is complet ed when t he l evel of surface s moothness want ed is achieved. All
the st eps should be foll owed in sequence until no further i mprovement in
surface finis h is observed. S ome poli shing m ateri als are rubber abrasive
point s and fine -part icl e polishi ng past es . Polishing is considered
multidi rect ional, s o the final surface scrat ches are ori ent ed in m an y
9
Adequat e cooli ng is requi red when ce rami c rest orations are fi nished and
polis hed. S everal kit s are avail able to accomplis h the finis hing and polishi ng
and manufacturers’ instructions should be followed when those systems are
used.
Abrasives devi ces :
Jeffri es cl as sifi ed abrasive and fini shing devices as coat ed, bonded and loos e
abrasives:1 4 , 1 5
1.4.1 Coated abrasive devices or diamonds : The prim ar y purp ose for finishing di amonds is to contour, adj ust and sm oot h porcelain. Fi nis hing
diam onds com e in vari ous grit s rangi ng from 5 -60µ. Diam onds burs should
alwa ys be us ed i n t he pres ence of water spra y and at rot ati onal speeds of
less than 50,000 revolutions per m inut e (rpm ).
1.4.2 Bonded ab ras ive devi ces or Rubb er, elas ti c finishin g and polishing devices : The y are frequentl y used for i nt erm edi at e fini shing and initi al poli shing and the y have different pres ent ations such as points , dis cs
and cups .
1.4.3 Loos e ab rasives or polishing pas tes: The y are considered as nonbonded abrasives and are pri maril y used for fi nal polis hing, The y are
applied to the s ubst rat e with a nonabrasive device s uch as s yntheti c foam,
brush, rubber, et c. Alumi num oxide and di amond are t he most popula r
nonbonded abrasi ves . Di amond polis hing pas tes are preferred for porcel ain
10
abrasive parti cles are di spersed in a wat er -s oluble m edium s uch as gl ycerin.
Gl yceri n is compatible with dr y and wet t echni ques.
1.5 Factors that infl uence finish ing and polishing p rocedu res1 6:
• Structure and m echanical propert ies of t he s ubst rat e m at eri al
• Difference in hardnes s bet w een the abrasive and the s ubst rate.
Hardness is measured using Moh’s hardness scale. The greater the
differenti al between the abras ive and t he restorative m at erial, t he
more abrasive t he effect will be (Tabl e 1).
• Part icl e hardness, si ze and shape of the ab rasive us ed
• Ph ysi cal properti es of the bonding m at eri al t o carr y the abrasive
mat eri al
• Speed and press ure at whi ch the abrasi ve is appli ed to the s ubs trate
• Lubri cat ion during the appli cat ion of the abrasive (wat er -sol ubl e
pol ym ers, gl ycerol, s ilicon greas e, pet rol eum j ell y)
Several st udi es have eval uated the sm oothnes s resulting from di fferent
polis hing techniques .
Klausner compared qualitativel y, b y means of s canning el ectron mi cros cop y
and low-power photographs, and als o ass es sed quantit at ivel y us ing a
Surfanal yz er to evaluat e t he effects of various pol ishi ng abrasives on
porcel ain (Vit a VM K 68 Vacuum porcel ain). Poli shing abras ives used were:
1. Superfine di amond, foll owed b y fi ne im pregnated rubber wheel and
polis hed on a l athe wit h a m oist ened wheel im pregnat ed with a mix of
11
point s) 3. Superfi ne di amond, followed b y m edi um -grit rubber -im pregnat ed
abrasive, Burl ew rubber disk and final polishi ng wit h a moist ened wheel
impregnat ed with a mix of al umina and wat er 4. C arving wheel foll owed b y
polis hing wit h J el enko polishing wheel . All t hese treatm ent s were com pared
with an unground, glaz ed s ampl e (control ). There was no stat isti cal
difference bet ween t he 4 t ypes of treatm ent wi th abrasiv es us ed1 7.
Cam acho evaluated the efficac y of different vehi cl es ass oci at ed with
different diamond polishi ng past es i ndi cated for dental cerami c pol ishi ng.
Four di fferent vehicles were us ed for t he appli cation of polishi ng pastes :
rubber cup, Robi ns on bris t le brus h, felt wheel and buff dis cs. It was
obs erved t hat Robinson bri stl e brush provided lower roughness m eans t han
fel t wheel and buff discs but thi s difference was not st ati sti cal l y s i gni fi cant.
On the other hand, polishi ng wit h a rubber cup as a vehicl e resul ted in
si gni fi cantl y hi gher roughness t hen t hat obs erved for t he other tested
vehicl es . The use of rubber cups for polishing cerami c rest orations i s not
advisabl e. The poor effi cac y of thi s vehi cl e mi ght be explai ned b y the
limited ret ention of the past e on its surface during the procedure. Al so, an
increase of t emperature was observed on t he ceramic when rubber was
empl o yed, whi ch can caus e mi crofissures on the surface of the subst rat e.
Fissures can decreas e the cerami c struct ural strength and contr i but e to the
12 1.6 Meth ods to ass es s s urface rou ghness 1.6.1 Atomi c Force Mi cros cop e
The Atomi c For ce Micros cope i s one of a vari et y of s canning probe
micros copes that have evolved from the pioneeri ng res earch of Young et al,
who dem onst rated the princi ple of the scanning tunnel i ng microscope
(STM ). 1 9
This type of microscope was developed in early 1990’s. AFM is a highly
com plex m ethod. The equipm ent is ver y expensive and s ensit ive.
Usuall y the AFM us es a si licon nitride probe, is well s uit ed for st ud yi ng
the st ructure of polis hed optical surfaces.
The mi cros cope us es a sharp ti p, whi ch is mount ed on a cantilever. The
tip has a radi us of about 20 to 50nm and is maint ained i n cont act with t he
surface under ver y s mall loads. The norm al force on the tip can be cal cul at ed
b y the defl ection and spri ng constant of the l ever. A l as er s hines -up at the
back part of the probe ’s tip and it hi ts t he det ector. Depending where the
las er hit s the detect or, the det ector det ermines how t he tip of t he probe is
moving such as i f the tip i s in a tall or a valle y feature. As the ti p pass es
over t he surface, the norm al force is kept cons tant.
1.6.2 Profil ometer:
This devi ce is l oaded on the s urface t o be m easured and then moved acros s
13 1.7 Rou ghnes s parameters:
1.7.1 Ari th meti c average h eigh t (Ra)
This param eter is als o kno wn as the cent er line average whi ch is the m ost
universall y us ed roughnes s paramet er for general qualit y cont rol. It is
defined as t he average absolut e devi ati on of the roughnes s irregul ariti es
from the m ean line over one sampling length. This param et er i s eas y to
define, eas y t o m easure, effi cient and gi ves a good descri ption of hei ght
vari ations. It is not s ensi tive t o sm all changes2 0.
1.7.2 Root mean squ are roughn es s (RMS or Rq)
It repres ents t he st andard deviation of t he di stri buti on of surface hei ghts .
It is an import ant param et er to describe t he surface roughness b y statisti cal
methods . This param et er is more sensitive t han the ari thm eti c average hei ght
(Ra) to l arge deviation from the m ean line.2 0
The meas urem ent of surface roughness is com pl ex and di ffi cult . That is
wh y the lit erature suggests that surface charact eristi cs s hould be des cri bed
as using more t han one param et er, s uch as Ra, RMS , et c, i n order to give
rel iable inform ation on the profile shape.1
The morphology of a s urface will depend on the l ength s cal e of
14
CHAPTER 2 : Effect of differen t finishi ng and polishing
intra-oral techniqu es on the su rface roughness of fou r cerami c materi als
2.1 Introdu ction
The use of ceram ic restorations has cl earl y increas ed in the past s everal
years mostl y due t o t he demand of estheti cs b y patients.
The occlusal adj ust ment usuall y done with di amond rot ary i nst rum ents
can create a si gni fi cant increase i n surface roughness whi ch can produce
wear of t he opposing denti tion. Al -Hi yasat et al report ed in an in vitro stud y
that the wear of ant agonis t tooth agai nst porcel ain was 0.6 t o 0.9m m, whi ch
is greater than nat ural enam el2 1. Monasky and Ta yl or showed that porcelain
with a rough surface caused more opposi ng wear than a sm ooth surface and
report ed t hat porcelai n causes m ore wear than gold al lo y, am al gam ,
com posit e resin, or enam el. 2 2 , 2 3
It is im port ant that roughness of s uch surfaces be m inimized b y
appropri at e poli shing wi th specifi c poli shing s ys t ems to m i nimize wear of
the opposi ng dentition.
Monol ithi c zirconia restorat ions have becom e popul ar in recent ye ars.
15
and pol ished forms , and after occl us al adjustm ent and polishi ng with
different int raoral s ystems .
Indi rect rest orations oft en requi re i ntraoral adjus tment and the us e of
adj ustm ent and pol ishing s yst ems are necess ar y to re -es tabli sh surface
smoot hness.
There are man y di fferent polis hing s ys t ems recomm ended for chairs ide
restorations. However, it is not clear if al l the s ys tem s are abl e to provi de a
smoot h surface equal to, o r bett er than, that of existing m at eri als.
Project Goal
To provide i nform at ion t o clini ci ans regarding whi ch i ntraoral polis hing
s yst em will produce a smoot her surface aft er adj ustm ent and polis hing of
IP S Em pres s C AD, IPS e.m ax CAD, BruxZi r and Zenostar m at eri als (Tabl e
2).
Specifi c Ai ms:
- To m easure t he surface roughness of gl azed and poli shed monolithi c cerami c
mat eri al s
- To compare the s urface roughness produced b y different i ntraoral poli shing
16 Null H ypoth es is
There are no difference bet ween the s urface roughness of monolithic
cerami c m ateri als before and aft er adj ustment and polis hing with di fferent
intraoral polis hing s ys tems
Materi als and Meth ods Speci men fab ri cation
The stud y incl uded 6 groups of cera mi c mat erial s, (N=10) s pecim ens per
group of mill ed dis cs made of 4 di fferent ceram ic m ateri als , 4 of t he groups
were monolit hi c z irconi a (Wieland Zenost ar; Ivocl ar Vivadent ) and
(BruxZir; Glidewell Laborat ori es ) i n gl azed and polis hed forms , the ot her
gro ups were l eucit e -rei nforced gl ass cerami c ( IPS Empres s CAD; Ivocl ar
Vivadent ) and lithium disilicat e ( IPS e.max CAD, Ivocl ar Vivadent ) that
were gl azed. All the specim ens had 10m m of diam et er x 2mm of t hickness
(Fi gure 1) whi ch were prepared b y an experi enced com merci al laborat or y
(Mi croDent al Laboratori es ). From the zirconi a Zenost ar groups, one group
(N=10) was Zenos tar Polis hed, and the other group (N=10) was Zenost ar
Glaz ed. From the BruxZi r groups , one group (N=10) was BruxZi r Polis hed,
and the other group (N= 10 ) was Brux Zir Glaz ed (Fi gure 2 ).
All the specimens present ed the fi nal treatm ent surface (glaz ed or
polis hed) at one side and at t he back a number was assi gned at random to be
17 Surface Rou ghnes s Ass ess ment
The t wo i nst rum ent s used t o ass ess the surface roughness of t he s pecim ens
before and aft er the adj ustm ent and poli shing wit h i ntraoral adjustm ent and
polis hing s ys tem s were the Atomic Force Mi cros cope As ylum R es earch
MFP -3D AFM and the KLA -Tencor P -6 P rofilom et er.
Atomi c Force Mi croscop e
The AFM gi ves a fi ne res oluti on of a s urface area. For each specim en,
three 40 X 40µm s can size (Fi gure 4) in different l ocati ons were m ade at the
cent er of each speci men (Fi gure 5) using an As yl um Res earch MFP -3D AFM
(Fi gure 6). The AFM s cans were made i n air wit h a Si3 (Budget s ensors , t ap
300Al-G tips with nominal frequenc y 3 00 kHz and a force const ant 40 N/m )
tip in t appi ng m ode. The tip has a dim ens ion of 10nm (Fi gure 7).
Each s pecim en was affixed wit h a copper tape t o a gl ass slide and t he slide
was secured b y m agnets . The probe of t he AFM was mount ed on the head of
the AFM . The s can rat e was 0.20 Hz, scan speed 20.08µm/ s.
Profil ometer
A KLA -Tencor P -6 Profil er is a st ylus -bas ed profil er and it was us ed to measure step hei ght and roughness on specim en s urfaces (Fi gure 8 ). The
s yst em perform ed a scan l ength of 600µ m. The st yl us tip has a 5µm radi us
(10 µm di am eter) and 60 degree cone angl e (Fi gure 7). The s can tim e was 1
18 Preli minary Study
A preli minar y stud y w as conduct ed in order to decide whi ch prot ocol was
going to be us ed for adj ustm ent and polishing since man y of t he
manufacturer’s didn’t give clear indications how to use their products.
A device fabri cat ed at t he Universit y of North C aroli na at C hapel Hil l -
School of Dent ist r y was used to moni t or the contact press ure during the
adj ustm ent and polis hing procedures (Fi gure 9). The pressure device cons ists
of a load cell , a bri dge am pli fier, and a dat a acqui sition unit connected t o an
IBM compatibl e PC throu gh a US B port. This device m easured the pres sure
applied b y t he hand duri ng the adjustm ent and poli shing procedures. The
soft ware coll ect ed t he dat a in Newt ons (N) and exported the dat a to a
Micros oft Excel spreadsheet (Mi crosoft. Redm ont, WA). The ceramic
specim ens were fixed to the devi ce b y using pol yvin yl sil oxane mat eri al
(Regisil P B Bit e R egistration, Dentspl y C aul k, M ilford, DE).
The preliminar y stud y consist ed in t r yi ng di fferent contact pressures and
time duri ng polishi ng. The cont act pressures t es t ed were 1N, 1.5N and 2N.
The tim e was t est ed from 1 0 seconds up t o 50 s econds per inst rum ent .
Aft er the prelimi nar y test was compl eted and final paramet ers were
det ermined for force and tim e to m aximize surface s moothness, the
concl usions were:
All t he ins truments had t o be us ed wi th wat er s pra y and the pressure
19 for polishers.
The adjustment pressure and ti me wit h di amond burs was determi ned
bas ed on previous researches.
Protocols f or p olish ing each cerami c material :
The di stri buti on of t he ceram ic groups and polishi ng s yst ems are shown in
Fi gure 10. One part of the specimens were adj ust ed wit h di amond burs and
polished with their manufacturer’s recommended polishing system (BruxZir
S ystem for Brux Zi r zirconi a gl az ed and polished, Zenost ar S ys t em for
Zenost ar zirconia gl az ed and poli shed and OptraFi ne S ys tem for IPS
Empres s CAD and IP S e.m ax CAD) and the remai ning s pecim ens were
adj ust ed and polis hed wit h t wo alt ernative S ys t ems (Di al ite ZR for t he
zirconi a ceramic groups Brux Zir and Zenost ar i n thei r gl azed and poli shed
forms and Dialit e LD for IPS Em press C AD and IPS e.m ax C AD) (Tabl e 3).
For the IPS Em press CAD and IPS e.m ax CAD specim ens, both groups of
mat eri al s were subdi vided in groups of 5 specim ens each and adjust ed and
polis hed with OptraFine S yst em and Di alit e LD S yst em . Two di amond burs
(fi ne and extrafi ne) were added to the OptraFine S yst em to s tandardiz e the
procedures si nce t hi s is the onl y s ys tem that does not come with diam ond
burs t o perform the adj ustm ent . The prot ocols for adjustm ent and poli shing
foll owed with Opt raFine S ys t em and Dialite LD S ys tem are s hown in Fi gure
11 and Fi gure 12.
20
specim ens e ach. Two of t he subdivi ded groups (Glaz ed and Polished) were
adj ust ed and poli shed wit h Zenost ar S ys tem (Fi gure 1 3) and the other two
subgroups were adjusted and poli shed wit h Di alit e ZR S ys t em (Fi gure 1 4).
The protocols for Zenostar S ys tem and Dialite ZR S yst em are s hown in
Fi gure 13 and Fi gure 14.
For the BruxZi r zirconia specim ens, fi ve of t he Glaz ed and five of the
Polished s pecim ens were adjust ed and polished with Brux Zi r S yst em and the
rem ai ning five Glaz ed and P olished specim ens were adjus ted and pol i shed
with Di alit e ZR S ys tem. The prot ocols for BruxZi r S yst em and Di alit e ZR
S ystem are shown in Fi gure 15 and Fi gure 14.
Aft er al l the adjust ment s and pol ishi ng procedures were complet ed i n all
the cerami c groups , another 3 m easurem ents were obt ained at the cent er of
the specim ens for each speci men usi ng Atomi c Force M icros cope and
Profilom et er.
Statis tical Anal ysis :
Dat a was anal yz ed using SPSS software version 2 1.
Mean and st andard error for each ceramic m at erial and polishi ng s ys t em
were cal cul at ed. No rmalit y of t he dat a was tested and t-t es t for pair -wis e
com paris on was perform ed and one -wa y ANOVA was us ed for comparison of
21
Bonferroni Post Hoc anal ysis was used and p val ues were report ed, α val ue
was s et at 0.05.
Results
Results with AFM
The m ean R a bas eli ne val ues ranged from 7.25 to 11.63nm (Fi gure 16 ).
The m ean RMS bas el ine values ranged from 9.43 t o 15.93nm (Fi gure 18 ).
For R a and RMS bas eline values, there was no st ati sticall y si gnifi cant
difference bet ween t he groups (Fi gure 1 6 and Fi gure 18 ).
All the m at erial s t est ed were rougher than the bas eli ne val ues aft er
adj ustm ent and polis hing with all the int raoral polis hing s ys t ems (Fi gure 17
and Fi gure19). Stat i sticall y si gni fi cant differe nce were found in Brux Zi r
Polished and IPS e.max CAD specim ens (p value <0.05). BruxZi r Polis hed
pres ent ed l ower m ean Ra and RMS values with Di alit e Zr S ystem com pared
to Brux Zi r S ys tem, and IPS e.m ax CAD pres ent ed l ower mean R a and R MS
val ues with Opt raFi ne S ys tem compared t o Di alit e LD. St atisti call y
si gni fi cant di fference were found i n Zenostar Glaz ed and IP S Empres s CAD
specim ens (p value <0.005). Lower m ean Ra and R MS values were obtai ned
in Zenost ar Gl azed s pecim ens when Di ali te Zr S ys t em was us ed and in IPS
Empres s C AD speci mens when Opt raFine S ys t em was used (Fi gure 17 and
Fi gure1 9).
Results with Profilometer
22
Polished were si gnificantl y l ower than all other m at eri als t ested (Fi gure 20
and Fi gure 22 ). The mean basel ine R a values of all the ceram ic t est ed were
in the ranges from 0.04 to 0.37µm . The mean bas eline R MS values were
from 0.05 to 0.46 µ m (Fi gure 20 and Fi gure 2 2).
All t he m ateri als tested were rougher t han the basel ine val ues af t er the
adj ustm ent and poli shing with int raoral polishi ng s ys tem s (Fi gure 20 and
Fi gure 22). St atisti call y si gnifi cant di fference was found in the BruxZir
Glaz ed and Brux Zir Polished specimens (p value <0.005). In Brux Zi r Gl az ed
and Polis hed s peci mens , low er Ra and RMS val ues were obtained with
Dialite ZR S yst em than wit h the Brux Zi r S ys tem (Fi gure 2 1 and Fi gure 23 ).
Brux Zi r pol ished and Zenost ar Polished at bas eline pres ented lower R a
val ues and Empress and e.m ax present ed hi gher R a values (Fi gure 24 )
When the s pecim ens were poli shed us ing the recommended m anufacturer’s
s yst ems Zenost ar glazed and polished present ed l ower Ra values and Brux Zir
Polished and Brux Zi r Glaz ed presented higher Ra values (Fi gure 2 5).
Dis cussi on
The adjust ment of t he occlusion at t he moment of deli vering a cerami c
restoration is cruci al since a rough surface ma y abrade opposing tooth or
restorative materi al s. Abrasivenes s is more correlated with cerami c
23
Most of the ti me dent ists need to us e di amond burs of di fferent parti cl e
size t o adjust t he occlus ion and t hen poli sh t he adjus ted surface with
intraoral polis hing s ys tems t o reduce the roughnes s creat ed previ ousl y.
This st ud y ass es sed the surface roughness of gl az ed l eucit e -reinforced
gl as s cerami c, glaz ed lithium di sili cate and gl az ed and pol is hed monoli thi c
zirconi a m at eri als before adjust ment and polis hing. The result s of this stud y
obt ained wit h the profil ometer agreed wi th previous studi es where poli shed
zirconi a dem onst rated l ess surface roughness than gl azed zirconia.5 , 2 5
This s tud y compared the surface roughness produced b y dif ferent int raoral
polis hing s ys t ems on adj ust ed l eucit e -reinforced gl ass cerami c, lit hium
disili cate and zirconi a materi als. The di fferent poli shing s yst ems us ed in the
pres ent s tud y were chos en because most of t hem are ver y popul ar i n the US
and there is n o publ i cation that compares all of them .
Surfaces can be sm ooth, s uch the Him al a yas viewed from space, but the
sam e surface can be rough if t he y are viewed from earth. So the morpholo g y
of a surface depends on the lengt h scale of obs ervat ion.
The effecti v eness of one or another met hod for meas uring s urfac e
roughnes s and the degree of agreem ent bet ween one m ethod and another is
24
Inst rum entat ion -dependent factors include st yl us or probe si ze, scanning
speed, frequenc y r esponse and sampling rat e of the recording
instrum ent ation, l im itati ons due to feat ure sl ope or s harpnes s, s am pling
length or area and the t ype of s oftware us ed to filt er and refine t he raw dat a.
The abilit y of the st yl us or tip to reproduce t he ori gi nal s urface features
depend on the st ylus size. The sm all er the st ylus size, the closer it will
foll ow the ori ginal profil e. The AFM pres ents a tip of 10nm and with
p yrami dal shape which provi des a m ore preci se m easurem ent of the
topograph y of a surface. The pr ofilom et er ti p has 10µm of di am eter (5µm of
radius) which doesn’t allow to measure defects smaller than the size of the
tip.
The AFM meas ures a small area, whi ch is repres entati ve becaus e goes
point b y point. The roughness is scale -dependent and increas es when l arger
area is studied. The AFM has a scan s ize of 40x40µm whil e t he P rofilom et er
pres ents a scan length of 600µm. The areas canned with the AFM can be
visualized in 3 -D. The present stud y agrees wit h a stud y published b y Tholt
in that b y combining t he Profilom et er and At omi c Force Micros cope, th e
results are more rel i abl e and precise. New protocols shoul d be est ablished to
stud y surface roughness in cerami cs wi th the AFM .1
The des cription of surface roughness b y R a i s comm onl y used in
25
that the y onl y report the average roughnes s paramet er. Ra not com pl etel y
des cribes t h e surface of a mat eri al. R a gi ves a represent at ive esti mat e of
surface roughness and it is eas y to cal cul at e it . The m ain problem of t he Ra
paramet er is t hat i t cannot dist inguish peaks from vall e ys . This is wh y i t is
important to calcul ate ot her param et er s that can m easure peaks and vall e ys
and profi le s hape and spacing. The root mean s quare (RM S) param et er i s
sensitive to peaks and vall e ys on a surface and the reading accounts for
extreme peaks or val le ys .2 3
Brux Zi r specim ens pres ent ed hi gher surface roughnes s val ues with AFM
and Profilom et er, and the reason for this mi ght be becaus e BruxZi r S ys t em i s
the onl y poli shi ng s ys tem that pres ent ed onl y one di am ond t o perform the
adj ustm ent . Previous res earch s uggest ed to foll ow a sequence of di am onds
and polis hers to reduce the surface roughness of the ceramic m ateri al to
obt ain bet ter result s.2 6
Li mi tations
This is an in vit ro s tud y and therefore t he effi cac y of pol is hing s ys tems
mi ght be di fferent under clinical condi tions . Moreover, it is possi bl e to
obt ain di fferent res ults usi ng di fferent t ypes of cerami cs and polishi ng
techni ques. A di fferent press ured appli ed and di fferent tim e used wil l give
26 Con clusion s
Under the condit ions of this st ud y we can concluded:
• At basel ine, poli shed zirconi a was les s rough than glaz ed zircon ia (when
measured with Profil omet er).
• Brux Zi r zirconi a res ulted in a sm oother surface wit h Di alit e ZR pol ishi ng
s yst em.
• Zenost ar zirconia produced a smoot her surface with Zenostar polishi ng
s yst em.
• IP S Em press CAD and IPS e.max CAD pres ent ed a s moot her sur face with
Opt raFi ne polishi ng s yst em.
• The Atomi c Force Micros cope compl ement s the P rofil om et er information
27
Table 1. The rel ati ve hardness of restorative mat eri als and abrasive comp ounds
(using Moh’s hardness scale)
Restorati ve materials
Porcelai n 6 -7
Gold allo ys 2.5 -4
R esi n composite 5 -7
Amal gam 4 -5
Abrasive materials
Diamond 1 0
Sili con carbi de 9 -10
Tungst en carbide 9
Alumi nium oxide 9
Zirconium si licat e 7 -7.5
28
Table 2. Cl assi fi cat i on of dent al cerami c ma t eri al s
Materi al Type of Cerami c Manufactu rer Indication s BruxZi r Yttria -st abi lized
monolit hi c zirconi a
Glidewell Dental Laborat ori es
Singl e crowns and
fixed partial
dentures Zenos tar Yttria -st abi lized
monolit hi c zirconi a
Ivocl ar-Vivadent Singl e crowns and
fixed partial
dentures I PS E mpres s
CAD
Leucit e -rei nforced gl as s cerami c
Ivocl ar-Vivadent Singl e crowns
I PS e.max CAD Li thium di sili cate Ivocl ar-Vivadent Singl e crowns and
fixed partial
29 Table 3. Finis hing and polis hing S yst ems
Adjus ting and Polishin g Sys tem
Manufactu rer Indication s
OptraFin e Ivocl ar-Vivadent Leucit e -rei nforced gl as s
cerami c and Lithium
disili cate
Diali te L D Brass eler US A Li thium disili cat e and Leucit e -rei nforced gl as s cerami c
BruxZi r Glidewell Dental Laborat ori es
Zirconia rest orati ons
30
31
32
Fi gure 3. S pecim en. A: s urface wit h final treatm ent B. Back of the specimen
33
34
Fi gure 5. S pecim en s howi ng 3 s urface measurem ents recorded at t he center of
35
36
37
38
39
40
41
42
43
44
45
Fi gure 16. M ean Bas eline R a (nm) values and st andard errors with
46
Fi gure 17. M ean R a (nm ) val ues and st andard error bars with Atomi c Force
47
Fi gure 18. M ean Bas eline R MS (nm ) val u es standard errors wi th
48
Fi gure 19. M ean RM S (nm ) values standard errors with Atom i c Force
49
50
Fi gure 21. M ean R a (µm) values st andard errors with P rofil om et er
51
Fi gure 22. M ean Bas eline R MS (µm) values and st andard errors wit h
52
Fi gure 23. M ean RM S (µm ) values st andard errors with P r ofil omet er
53
Fi gure 24. R anki ng order (from more to l ess rough, bott om t o t op) for Ra
54
Fi gure 25. R anki ng order (from more to l ess rough, bott om t o t op) for Ra values
55
RE FE RENCES
1. T hol t de V asconcel l os B, Mi randa -J uni or WG, Pri ol i R, T ho mpso n J , Oda M. Surf ace rou ghness i n cer a mi cs wi t h di f f erent fi ni shi ng t echni ques usi ng at o mi c for ce mi cr oscope and pr ofi l o met er . Operat i ve de nt i st ry. J ul -Au g 2006; 31(4): 442 -449 .
2. Gha zal M, K er n M. T he i nfl uence of ant a gon i st i c sur face roughnes s on t he wea r of hu ma n ena mel and nanof i l l ed co mp osi t e resi n ar t i fi ci al t eet h. The Journal of prost het i c dent i st ry. May 2 009; 101(5): 34 2 -349.
3. Anusa vi ce. Phi l l i p's S ci ence of Dent al M at e ri al s. 11t h ed20 13.
4. Marchack BW, Sat o S , Mar chack CB, Whi t e SN. C o mpl et e and pa rt i al cont our zi r coni a desi gns for c r owns and fi xed dent a l prost heses: a cl i ni cal report . The Journal of prost het i c dent i st ry. Sep 20 11; 10 6(3): 145 -1 52.
5. J anya vul a S , La wson N, Ca ki r D , Bec k P, Ra mp L C, Bur gess J O . T he wear of pol i shed and gl a zed zi rconi a agai nst en a mel . The Journal of prost het i c dent i st ry. J an 2013; 10 9( 1) : 22 -29 .
6. Marchack BW, Fut at s uki Y, Marchac k C B, Whi t e SN. Cust o mi zat i on of mi l l ed zi r coni a copi n gs f or al l -cer a mi c cr o wns: a cl i ni cal report . The Journal of prost het i c dent i st ry. Mar 2008; 99( 3): 169 -1 73.
7. Aboushel i b M N, K l ever l aan CJ , Fei l zer AJ . Eff ect of zi rconi a t yp e on i t s b ond st rengt h wi t h di ff er en t veneer cera mi cs. Jo urnal of prost hodont i cs : of f i ci al j ournal of t he A meri ca n Col l ege of Prost hod ont i st s. J ul 2008; 17(5): 401 -4 08.
8. Fi scher J , St awar zc yk B, T rot t mann A, Ha m mer l e C H. I mpact of t her mal mi sfi t on shear st ren gt h of veneer i ng cer a mi c/ zi rconi a co mp osi t es. Dent al mat eri al s : of f i ci al publ i cat i on of t he Academy of Dent al M at eri al s. Apr 2009; 25(4) : 419 -423.
9. Swai n MV . Unst abl e c r acki n g (chi ppi n g) of veneer i n g por cel ai n o n al l -cera mi c dent al crowns a nd fi xed part i al de nt ures. Act a bi o ma t eri al i a. J un 2009; 5( 5) : 1668 -167 7.
10. Anun mana C, Anusa vi ce KJ , Mechol sky JJ , J r. Int erfaci al t oughn e ss of bi l ayer dent al cera mi cs based on a shor t -bar, c he vron -not ch t est . Dent al mat eri al s : of f i ci al publ i cat i on of t he Acade my of Dent al M at eri al s. Feb 201 0; 26(2): 111 -117.
11. McLaren EA, T er r y D A. CA D/ C AM s yst e ms , mat eri al s, and cl i ni cal gui del i nes for al l -cera mi c cr o wn s and fi xed par t i al de nt ur es. Co mpendi u m of cont i nui ng educat i on i n dent i st ry (Ja mesburg , N .J. : 1 995) . J ul 2002; 23( 7): 637 -641, 644, 646 passi m; qui z 654 .
56
13. J agger DC , Harri son A. An i n vi t ro i n vest i gat i on i nt o t he w ear eff ect s of un gl aze d, gl a zed, a nd pol i shed porcel ai n o n hu man ena mel . The Journal of prost het i c dent i st ry. S ep 1994; 72( 3) : 320 -3 23 .
14. J ef f eri es SR. T he ar t and sci ence of ab r asi ve fi ni shi n g and pol i shi n g i n rest orat i ve dent i st r y. Dent al cl i ni cs of N ort h Ameri ca . Oct 1998; 4 2(4): 613 -6 27.
15. J ef f eri es SR. Abra si ve fi ni shi ng and pol i shi ng i n rest orat i ve dent i st r y: a st at e -of -t he -ar t re vi ew. Den t al cl i ni cs of Nort h A meri ca. Apr 200 7; 51(2 ): 379 -39 7, i x.
16. Owen S RD, Ne wso m e P. Fi ni shi n g and pol i shi ng poecel ai n surfa ces chai rsi de. Int ernat i onal Dent i st r y - Aust ral asi an.6(4): 68 -7 3.
17. K l ausner LH, Cart wr i ght C B, Charbeneau GT . Pol i shed versu s aut ogl a zed por cel ai n sur faces. T he Journal of prost h et i c dent i st ry. Feb 1 982; 47( 2): 157 -162.
18. Ca mach o G B, V i nha D, P an zeri H , N ona ka T , Goncal ves M. S ur face r ou ghness of a dent al cerami c af t er pol i shi ng wi t h di ffer ent vehi cl es and di amond past es. Brazi l i an dent al j ourn al . 2006; 17( 3) : 19 1 -19 4.
19. Bennet t J M, El i ngs V , Kj ol l er K . Recent de vel op me nt s i n pro fi l i ng opt i cal sur faces. Appl . Opt . 1 993/ 07/ 01 19 93; 32(19) : 3442 -3447.
20. Gadel ma wl a E S K M, Ma ksoud T MA, El ewa IM, S ol i man H H. Rou ghness para met ers. Journ al of Mat eri al s Processi ng Technol ogy. 2002(12 3 ): 133 -14 5.
21. Al -A ml eh B , L yons K , Swai n M. Cl i ni cal t r i al s i n zi rconi a: a syst e mat i c revi ew . J Oral Re habi l . Au g 2010; 37( 8) : 6 41 - 652.
22. Monasky GE , T ayl or DF. St udi es o n t he w ear of porcel ai n, enamel , and gol d. The Journal of prost he t i c dent i st ry. Mar 197 1; 25(3) : 299 -306.
23. Al -Sha mmer y H A, Bu bb NL, Yo un gson C C, Fasbi nder DJ , Wood DJ . T he use of confocal mi cr osco p y t o ass ess surface r o u gh ness of t wo mi l l ed CA D -C AM cer a mi cs fol l owi n g t wo pol i shi n g t echni ques. Dent al mat eri al s : of f i ci al publ i cat i on of t he Ac a demy of Dent al M at eri al s. J un 2007; 23( 6): 73 6 -74 1.
24. V an Di j ken JW, Horst edt P. Mar gi nal breakdown of 5 -year -ol d di r ect comp osi t e i nl ays. J Dent . N o v 19 96; 24(6) : 389 -394.
25. Par k J H, Par k S, Lee K , Yun K D, Li m HP. Ant a goni st wear of t hr ee CA D/ C AM anat o mi c cont our zi rc oni a cerami cs. T he Journal of prost het i c dent i st ry. J an 2014; 111( 1) : 20 -29.
