The Effects of Surface Roughening Techniques on Surface and Electrochemical Properties of Ti Implants










Chapter 8
The Effects of Surface Roughening Techniques on
Surface and Electrochemical Properties of Ti Implants
Youssef Al Jabbari, Wolf Dieter Mueller,
Abdulaziz Al-Rasheed and Spiros Zinelis
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/62791
Abstract
This
chapter deals with the effect of commonly used surface roughening techniques for
rapid osseointegration on surface and electrochemical properties of dental implants.
Dental implants prepared by smooth machining (MAC), double acid etching (DAE),
sandblasting and acid etching (SLA), Ti plasma spray (TPS) and anodization (ANO) were
included, and their electrochemical properties were compared to untreated commercial‐
ly pure titanium (cpTi). The treated surfaces demonstrated great differences in surface
roughness, morphology, elemental composition and oxide type. Open circuit potential
(OCP) and anodic scan potentiodynamic curves showed that electrochemical proper‐
ties of treated surfaces are inferior to untreated cpTi in an original Ringer’s solution and
a Ringer’s solution enriched with NaF except from the case of ANO where the electro‐
chemical properties were enhanced. Galvanic action between dental implants and
prosthetic superstructures and more importantly between the treated root and polish‐
ed collar of dental implants is also discussed.
Keywords: dental implants, electrochemical testing, corrosion, surface roughness,
SEM
1. Introduction
Ti
and its alloys (Ti–6Al–4V, Ti–6Al–7Nb, Ni–Ti and others) have a long record of applica‐
tions in dental field. [1–3]. Although Ti is well known for its biocompatibility and excellent
corrosion resistance, there are still concerns for the ionic release of Al and V from Ti alloys as
they are connected with adverse biological consequences [4–9]. To overwhelm this complica‐
tion, most dental implants are manufactured of commercially pure titanium (cpTi: grade II and
IV), although a few implants are still produced by the stronger Ti–6Al–4V alloy.
In first place corrosion of dental implants is not a primary concern as the implant surface is
not exposed to oral fluids. Ideally after the implant placement the collar will be covered by the
soft tissue at cervical region while root region will be covered by the attached bone. However,
under inflammatory conditions like peri-implantitis, the environment can be very acidic and
thus much more aggressive. In general, peri-implantitis establishes two changes at the region.
The first is a significant decrease in pH value at the region resulting in a more aggressive
environment for Ti surfaces. Both cpTi and Ti6Al4V alloys showed inferior corrosion resistance
in lower pH while the corrosion rate and kinetic is accelerated [10]. The second is the direct
contact of collar and root regions with oral fluids due to the resorption of soft and hard tissues
has to be considered. Under these conditions, different corrosion mechanisms can be activated:
Uniform corrosion: Ti surfaces cannot withstand the corrosive action of oral fluids and a
uniform regular removal of metal from implant surface is occurred [11].
Pitting corrosion: A form of localized corrosion, where small surface fissures are developed
on the metal surface.
Crevice corrosion: Corrosion takes place between two close metallic surfaces as in the case of
implant and abutment [12]. Crevice corrosion can be also developed on a deep surface crevice
where stagnant conditions of the solution are achieved and oxygen exchange between surface
and environment is impossible.
Galvanic corrosion: A galvanic couple is developed when dissimilar metallic materials are
placed in contact.
Microbial corrosion: Microbial corrosion or microbiologically-influenced corrosion is the
corrosion form caused or promoted by the metabolic actions of microorganisms which reduce
the pH levels.
Fretting corrosion: Fretting corrosion is caused due to micro movements of mechanically
connected parts of an implant structure.
Recently, a research study claims that corrosion of dental implants might be not the result but
the triggering factor for peri-implantitis [13]. In 2009, Alberkston et al [13] claimed that
corrosion along with the presence of aggressive bacteria, lesion of peri-implant attachment
and excessive mechanical loading, among the four triggering factors of peri-implantitis. They
concluded that “peri-implantitis is a general term dependent on a synergy of several factors,
irrespective of the precise reason for first triggering of symptoms” and thus corrosion resist‐
ance might be associated with the failure of dental implants.
Although Ti oxide can be instantly rebuilt after an unexpected damage, a recent study has
pointed out that the breakdown of the oxide film is followed by a dissolution process which
finally deteriorates the corrosion resistance if this happens repeatedly [14]. In a retrieval
analysis study, the corrosion and pitting potential of an intra-oral aged implants were found
lower compared to unused ones. The retrieved implants showed lower passivation range and
Dental Implantology and Biomaterial
154

polarization resistance, indicating that in vivo aging deteriorates the electrochemical proper‐
ties of Ti implants [15]. Moreover, a retrieval study of four failed dental implants showed that
all had been corroded during intra-oral service [16]. The authors concluded that surface
oxidation of dental implants might be changed due to the acidic environment developed by
bacteria biofilms and/or the inflammatory conditions at the region. This process may perma‐
nently breakdown the oxide film facilitating the release of debris and metal ions around the
implant. The latter might also hinders the re-integration of bone on implant surface. [16]
Given that corrosion has not yet considered among the risk factors of implant failure there are
no specific guidelines to clinicians to minimize the possibility of in vivo corrosion (i.e minimize
galvanic coupling between implant and supestructure alloys). Unfortunately, till today, there
are no comparative studies on the electrochemical behavior of contemporary dental implants
with different surface treatments. A few studies have employed advanced techniques such as
electrochemical impedance spectroscopy to characterize the electrochemical properties of
anodized and machined dental implants [17–19]. However, the diversity of the applied
methods and solutions used for testing makes comparison between the surface treatments
rather invalid. A few papers have studied the galvanic coupling of Ti with different dental
alloys used for the preparation of implant-retained superstructures providing data for suitable
and nonsuitable combinations [20–23]. However, the aforementioned results cannot be directly
extrapolated in clinical practice as the experimental conditions are far from intra-oral envi‐
ronment.
2. Effect of surface roughening techniques on morphology, roughness,
composition and oxide type of modified Ti implant surfaces.
The modification of implant surface in a way to accelerate the osseointegration process is a
topic of intense research and competition among implant companies. A variety of surface
roughening techniques have been implemented till today including Ti plasma spray (TPS),
double acid etching (DAE), sandblasting with large grit and acid etching (SLA), anodization
(ANO), machining (MAC) (Table 1), laser etching and others [24].
Implant (Manufacturer) Surface treatment Code
Ice (3i, Palm Beach Gardens, FL, USA) Smooth machining MAC
IMZ TPS (Friedrichsfeld, Mannheim, GER) Ti plasma-sprayed TPS
OsseotiteFull (3i) Double acid etched DAE
SLA Active (Institute Straumann, Basel, CH) Sandblasting, acid etching SLA
Replace Select (Nobel Biocare, Göteborg, Sweden) Anodized ANO
Table 1. Dental implants, manufacturer, surface roughening technique and code for commercially available products.
The Effects of Surface Roughening Techniques on Surface and Electrochemical Properties of Ti Implants
http://dx.doi.org/10.5772/62791
155

Today, products prepared with the aforementioned techniques are available in dental market
as there is no clear evidence for the superiority of one surface modification over the others.
The different surface roughening techniques provide characteristic surface patterns on Ti
implant surfaces. MAC is characterized by parallel serrations with a rather smooth surface
(Figure 1). TPS provides surfaces with a random distribution of small granules resemble to
solidified droplets probably due to plasma spray process along with a random distribution of
surface cracks (Figure 1). DAE and SLA depict some similarities due to the final step of acid
etching, although SLA illustrates shallow grooves probably due to grit blasting before etching.
ANO is characterized by valleys and open craters although the size, the shape and the
distribution of these craters are significantly dependent on operational parameters during
anodization.
Figure 1. Secondary electron images from the root surface of dental implants in 4000 (left) and 24000 (right) nominal
magnifications. Parallel serrations are shown on MAC surface due to surface grinding. TPS provides surfaces with a
random distribution of small granules along with surface cracks. DAE and SLA illustrate some similarities due to the
final step of acid etching although SLA demonstrates shallow grooves associated to grit blasting before etching. ANO
is characterized by open craters and valleys.
Dental Implantology and Biomaterial
156

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Chapter 8The Effects of Surface Roughening Techniques onSurface and Electrochemical Properties of Ti ImplantsYoussef Al Jabbari, Wolf Dieter Mueller,Abdulaziz Al-Rasheed and Spiros ZinelisAdditional information is available at the end of the chapterhttp://dx.doi.org/10.5772/62791AbstractThis chapter deals with the effect of commonly used surface roughening techniques forrapid osseointegration on surface and electrochemical properties of dental implants.Dental implants prepared by smooth machining (MAC), double acid etching (DAE),sandblasting and acid etching (SLA), Ti plasma spray (TPS) and anodization (ANO) wereincluded, and their electrochemical properties were compared to untreated commercial‐ly pure titanium (cpTi). The treated surfaces demonstrated great differences in surfaceroughness, morphology, elemental composition and oxide type. Open circuit potential(OCP) and anodic scan potentiodynamic curves showed that electrochemical proper‐ties of treated surfaces are inferior to untreated cpTi in an original Ringer’s solution anda Ringer’s solution enriched with NaF except from the case of ANO where the electro‐chemical properties were enhanced. Galvanic action between dental implants andprosthetic superstructures and more importantly between the treated root and polish‐ed collar of dental implants is also discussed.Keywords: dental implants, electrochemical testing, corrosion, surface roughness,SEM1. IntroductionTi and its alloys (Ti–6Al–4V, Ti–6Al–7Nb, Ni–Ti and others) have a long record of applica‐tions in dental field. [1–3]. Although Ti is well known for its biocompatibility and excellentcorrosion resistance, there are still concerns for the ionic release of Al and V from Ti alloys asthey are connected with adverse biological consequences [4–9]. To overwhelm this complica‐ tion, most dental implants are manufactured of commercially pure titanium (cpTi: grade II andIV), although a few implants are still produced by the stronger Ti–6Al–4V alloy.In first place corrosion of dental implants is not a primary concern as the implant surface isnot exposed to oral fluids. Ideally after the implant placement the collar will be covered by thesoft tissue at cervical region while root region will be covered by the attached bone. However,under inflammatory conditions like peri-implantitis, the environment can be very acidic andthus much more aggressive. In general, peri-implantitis establishes two changes at the region.The first is a significant decrease in pH value at the region resulting in a more aggressiveenvironment for Ti surfaces. Both cpTi and Ti6Al4V alloys showed inferior corrosion resistancein lower pH while the corrosion rate and kinetic is accelerated [10]. The second is the directcontact of collar and root regions with oral fluids due to the resorption of soft and hard tissueshas to be considered. Under these conditions, different corrosion mechanisms can be activated:Uniform corrosion: Ti surfaces cannot withstand the corrosive action of oral fluids and auniform regular removal of metal from implant surface is occurred [11].Pitting corrosion: A form of localized corrosion, where small surface fissures are developedon the metal surface.Crevice corrosion: Corrosion takes place between two close metallic surfaces as in the case ofimplant and abutment [12]. Crevice corrosion can be also developed on a deep surface crevicewhere stagnant conditions of the solution are achieved and oxygen exchange between surfaceand environment is impossible.Galvanic corrosion: A galvanic couple is developed when dissimilar metallic materials areplaced in contact.Microbial corrosion: Microbial corrosion or microbiologically-influenced corrosion is thecorrosion form caused or promoted by the metabolic actions of microorganisms which reducethe pH levels.Fretting corrosion: Fretting corrosion is caused due to micro movements of mechanicallyconnected parts of an implant structure.Recently, a research study claims that corrosion of dental implants might be not the result butthe triggering factor for peri-implantitis [13]. In 2009, Alberkston et al [13] claimed thatcorrosion along with the presence of aggressive bacteria, lesion of peri-implant attachmentand excessive mechanical loading, among the four triggering factors of peri-implantitis. Theyconcluded that “peri-implantitis is a general term dependent on a synergy of several factors,irrespective of the precise reason for first triggering of symptoms” and thus corrosion resist‐ance might be associated with the failure of dental implants.Although Ti oxide can be instantly rebuilt after an unexpected damage, a recent study haspointed out that the breakdown of the oxide film is followed by a dissolution process whichfinally deteriorates the corrosion resistance if this happens repeatedly [14]. In a retrievalanalysis study, the corrosion and pitting potential of an intra-oral aged implants were foundlower compared to unused ones. The retrieved implants showed lower passivation range andDental Implantology and Biomaterial154 polarization resistance, indicating that in vivo aging deteriorates the electrochemical proper‐ties of Ti implants [15]. Moreover, a retrieval study of four failed dental implants showed thatall had been corroded during intra-oral service [16]. The authors concluded that surfaceoxidation of dental implants might be changed due to the acidic environment developed bybacteria biofilms and/or the inflammatory conditions at the region. This process may perma‐nently breakdown the oxide film facilitating the release of debris and metal ions around theimplant. The latter might also hinders the re-integration of bone on implant surface. [16]Given that corrosion has not yet considered among the risk factors of implant failure there areno specific guidelines to clinicians to minimize the possibility of in vivo corrosion (i.e minimizegalvanic coupling between implant and supestructure alloys). Unfortunately, till today, thereare no comparative studies on the electrochemical behavior of contemporary dental implantswith different surface treatments. A few studies have employed advanced techniques such aselectrochemical impedance spectroscopy to characterize the electrochemical properties ofanodized and machined dental implants [17–19]. However, the diversity of the appliedmethods and solutions used for testing makes comparison between the surface treatmentsrather invalid. A few papers have studied the galvanic coupling of Ti with different dentalalloys used for the preparation of implant-retained superstructures providing data for suitableand nonsuitable combinations [20–23]. However, the aforementioned results cannot be directlyextrapolated in clinical practice as the experimental conditions are far from intra-oral envi‐ronment.2. Effect of surface roughening techniques on morphology, roughness,composition and oxide type of modified Ti implant surfaces.The modification of implant surface in a way to accelerate the osseointegration process is atopic of intense research and competition among implant companies. A variety of surfaceroughening techniques have been implemented till today including Ti plasma spray (TPS),double acid etching (DAE), sandblasting with large grit and acid etching (SLA), anodization(ANO), machining (MAC) (Table 1), laser etching and others [24].Implant (Manufacturer) Surface treatment CodeIce (3i, Palm Beach Gardens, FL, USA) Smooth machining MACIMZ TPS (Friedrichsfeld, Mannheim, GER) Ti plasma-sprayed TPSOsseotiteFull (3i) Double acid etched DAESLA Active (Institute Straumann, Basel, CH) Sandblasting, acid etching SLAReplace Select (Nobel Biocare, Göteborg, Sweden) Anodized ANOTable 1. Dental implants, manufacturer, surface roughening technique and code for commercially available products.The Effects of Surface Roughening Techniques on Surface and Electrochemical Properties of Ti Implantshttp://dx.doi.org/10.5772/62791155 Today, products prepared with the aforementioned techniques are available in dental marketas there is no clear evidence for the superiority of one surface modification over the others.The different surface roughening techniques provide characteristic surface patterns on Tiimplant surfaces. MAC is characterized by parallel serrations with a rather smooth surface(Figure 1). TPS provides surfaces with a random distribution of small granules resemble tosolidified droplets probably due to plasma spray process along with a random distribution ofsurface cracks (Figure 1). DAE and SLA depict some similarities due to the final step of acidetching, although SLA illustrates shallow grooves probably due to grit blasting before etching.ANO is characterized by valleys and open craters although the size, the shape and thedistribution of these craters are significantly dependent on operational parameters duringanodization.Figure 1. Secondary electron images from the root surface of dental implants in 4000 (left) and 24000 (right) nominalmagnifications. Parallel serrations are shown on MAC surface due to surface grinding. TPS provides surfaces with arandom distribution of small granules along with surface cracks. DAE and SLA illustrate some similarities due to thefinal step of acid etching although SLA demonstrates shallow grooves associated to grit blasting before etching. ANOis characterized by open craters and valleys.Dental Implantology and Biomaterial156 3D profilometric images (Figure 2) provide a better idea for the highest (red) and lowest (blue)areas of each surface. For MAC the highest points are the ridges of serrations while for TPSrandomly distributed granular regions. The highest points for SLA are region surroundingvalleys while the top of craters constitutes the highest points for ANO. Table 2 presentsrepresentative values for roughness parameters from dental literature. In general, the im‐plants’ surfaces are classified based on Sa (average roughness over the complete 3D surface)in smooth (0.0–0.4 μm), minimally rough (0.5–1.0 μm), moderately rough (1.0–2.0 μm) andrough (>2 μm) [25]. The first category includes the well-polished implant collars while MACand DAE are classified as minimally rough surfaces. SLA and ANO belong to moderatelyrough surfaces and TPS to rough ones. Despite this general classification, it must be noted thatmanufacturers can modify the procedural parameters, and thus commercially availableimplants might have big differences in their surface roughness even if they are prepared bythe same surface roughening technique.From corrosion standpoint, this difference in surface roughness might trigger the crevicecorrosion mechanism. In this mechanism, the surface can withstand the corrosive environmentbut the stagnant solution in the crevice changes the chemistry increasing the aggressivenessof solution.Figure 2. Representative 3D profilometric images from the collar (representative from all implants) and the surfaces ofdifferently modified root surfaces. Red areas are the highest and blue the lowest areas of each surface. Note the differ‐ence in scale among 3D images.The Effects of Surface Roughening Techniques on Surface and Electrochemical Properties of Ti Implantshttp://dx.doi.org/10.5772/62791157 Sa [26] Sa [27] Ra [24]Collar 0–0.4MAC 0.9 0.5 0.2TPS 5.2 7.0DAE 0.9 0.5SLA 2.6 1.6 1.2ANO 1.7 2.0Table 2. Sa (average roughness over the complete 3D surface) and Ra (average roughness along X or Y axes) values forcollar and root regions of implants from dental literature.Implant surfaces are further differentiated in elemental composition as appeared by EDXanalysis (Figure 3). All spectra showed C and N which should be appended to surfacecontamination while O should be attributed to surface oxide film. For SLA, Na and Cl werealso identified and might be appended to residues of NaCl solution where the implant is placedto avoid atmospheric contamination. P in ANO has been retained from the solution usedduring anodization.Although Ti oxide is spontaneously formed when Ti is exposed to atmospheric oxygen, a recentstudy employing Raman analysis illustrated great differences among the oxide type developedon different surfaces [28]. According to the results of this study, MAC surface contains mainlyFigure 3. X-ray EDS spectra from the root surface of dental implants prepared by different surface roughening techni‐ques. All surfaces illustrated the presence of Ti while C and N should be appended to surface contamination. The pres‐ence of O is involved with oxide film. Na and Cl were also identified for SLA and might be appended to residues ofNaCl solution where the implant is stored. P in ANO has been retained from the solution used during anodization.Dental Implantology and Biomaterial158 amorphous Ti oxide and less anatase, TPS amorphous and less rutile, DAE mainly Ti2O3 andamorphous and less rutile, SLA mainly Brookite and lesser rutile and ANO anatase and lessrutile. Given the big differences in all the aforementioned properties, different electrochemicalproperties are anticipated.3. Electrochemical propertiesAll the surfaces show an almost steady open circuit potential (OCP) in Ringer’s (Figure 4),indicating a rapid establishment of equilibrium between surface and solution. The OCP valuesrange from −0.28 up to −0.05 V while cpTi showed −0.05 V close to previous reported values[29]. OCP curves illustrate that the potential of all surfaces is quickly stabilized. MAC and TPSshowed values close to cpTi while SLA and ANO showed slightly lower OCP values. A fewpeaks at ANO curve might be appended to reactions taking place at the surface craters.However this is only a speculation and it needs further experimental verification. DAE showedthe lowest OCP value. All the treated surfaces showed lower OCP values compared to cpTi afinding which has been also detected for sandblasting compared to reference Ti surface [30].Figure 4. Open circuit potential (OCP) curves in Ringer’s solution. All implants show an almost steady curve over thetime, indicating a rapid establishment of equilibrium between surface and solution. The ionization tendency is in‐creased towards lower OCP values.Figure 5 illustrates representative anodic scan curves along with a small part of reversescanning while the electrochemical data are presented in Table 3. SLA and TPS demonstratea few oxidation peaks (pointed by the black arrows) while all curves show negative hysteresisimplying that the oxide film can be reformed after an unexpected breakdown. Similar EcorrThe Effects of Surface Roughening Techniques on Surface and Electrochemical Properties of Ti Implantshttp://dx.doi.org/10.5772/62791159 values have been reported in dental literature (−0.35 V [31], −0.4 V [32] and −0.18 V [29]).However, all Ecorr values of treated surfaces moved cathodically denoting an increase tendencyof surface to react. All surfaces show a passivation region and Epit of cpTi was found close topreviously reported values (0.45 V [32]. ANO showed the highest Epit (Table 3) compared toothers.Figure 5. Anodic scans from dental implants with different surface modifications. Oxidation peaks (pointed by blackarrows) were identified for TPS and SLA. All the surfaces showed a breakdown potential (Epit) and negative hysteresisin reverse scanning (a small part of reverse scanning curve at 2 V is appeared for all materials).Ecorr(V)Icorr(μA/cm2)Epit(V)HysteresiscpTi −0.27 3.8 0.22 NegativeMAC −0.84 3.6 0.55 NegativeTPS −0.52 20.3 0.43 NegativeDAE −0.79 7.4 0.29 NegativeSLA −0.62 39.4 0.04 NegativeANO −0.68 3.4 1.26 NegativeTable 3. Ecorr, Icorr, Epit and type of hysteresis from the anodic scan curves obtained in Ringer’s solution. Higher Ecorr andEpit, lower Icorr and negative hysteresis benefit the corrosion resistance.Dental Implantology and Biomaterial160 Figure 6. OCP curves in 2% NaF+Ringer’s solution. ANO showed an increase in OCP values compared to Ringer’s sol‐ution. However, the OCP values of the rest implants moved cathodically although potential is again quickly stabilizedas in the original Ringer’s solution.Many researchers have focused on the effect of fluoride ions on the corrosion resistance ofdental implants as many dental products such as toothpastes, mouthwashes, prophylacticsgels and others are proposed for the oral hygiene of patients with dental implants. However,Ti oxide is very vulnerable to fluoride ions and thus the corrosion resistance of dental implantsis seriously compromised [33–35]. Generally, in F− containing media the surface of Ti showeda strongly bound complex Na2TiF6 followed by a huge increase in surface roughness [36].However, the presence of F− reduces the corrosion resistance of dental alloys too [37]. InRinger’s solution with 2% NaF all OCP curves moved cathodically in a range from −0.4 to −0.2V. Previous studies reported that OCP of cpTi in Ringer’s solution is ranged between −0.08 [29]and 0.05 V [38], implying that the surface roughening techniques applied have moved the OCPcathodically. Surprisingly, ANO showed an increase in OCP in the 2% NaF+Ringer’s solution,while the OCP of the rest implants moved cathodically due to the more aggressive nature ofthis reagent. However, the potential is again quickly stabilized as in the original Ringer’ssolution.Similar to Ringer’s solution the anodic scan curves showed that surface roughening techniquesmove Ecorr value to lower values while passive region was vanished for cpTi, MAC and SLA.In addition, DAE and MAC showed positive hysteresis denoting that in the case of oxidebreakdown the reformation of the oxide film is impossible under these conditions (Figure 7).Again ANO showed the best corrosion resistance properties demonstrating the highest (1.32V) Epit value (Table 4).The Effects of Surface Roughening Techniques on Surface and Electrochemical Properties of Ti Implantshttp://dx.doi.org/10.5772/62791161 Figure 7. Representative anodic scans from dental implants with different surface modifications. All surfaces showed abreakdown potential while MAC and DAE demonstrated a positive hysteresis in reverse scanning (a small part of re‐verse scanning curve at 2 V is appeared for all materials).Ecorr(V)Icorr(μA/cm2)Epit(V)HysteresiscpTi −0.42 1.7 Without passive region NegativeMAC −0.47 46.2 Without passive region PositiveTPS −0.69 19.1 0.20 NegativeDAE −0.72 4.0 0.18 PositiveSLA −0.68 83.8 Without passive region NegativeANO −0.56 1.8 1.32 NegativeTable 4. Ecorr, Icorr, Epit and type of hysteresis from the anodic scan curves acquired in 2% NaF+Ringer’s solution. HigherEcorr and Epit, lower Icorr and negative hysteresis benefit the corrosion resistance.There is limited knowledge for the effect of surface roughening techniques on electrochemicalproperties of dental implants. OCP and anodic scans showed that sandblasting deterioratesthe electrochemical properties of Ti surface, a finding that has already been reported byprevious studies [30]. A speculation for this behavior is that the residual stresses developed inthe subsurface during sandblasting have a detrimental effect on corrosion properties. The sametrend was identified for both the Ti6Al4V and Ti6Al7Nb alloys after sandblasting in phosphate-buffered solution (PBS) [39]. However, all previous studies on ANO surfaces agreed that ANOhas a positive effect on electrochemical properties. This has been tested in a variety of reagentsDental Implantology and Biomaterial162 including PBS and media with cells simulating inflammatory conditions [17], Ringer’s [40],PBS [41] and 0.9% NaCl [42]. Interestingly the same findings were found for Ti6Al4V andTi6Al7Nb [42]. Recent data showed that no correlation was identified between roughnessparameters and electrochemical properties in both the aforementioned solutions meaning thatsurface roughness cannot affect the corrosion resistance and thus the electrochemical proper‐ties are not dependent on how rough the surface is [26].4. The galvanic aspectGalvanic coupling can be easily developed in the oral cavity between dental implants andimplant-retained superstructures especially under peri-implantitis conditions. Concerning thegalvanic couple of Ti with dental alloys, a few studies have been conducted employingdifferent reagents. Tables 5, 6 and 7 illustrate potential differences of various galvanic couplesbetween Ti and dental alloys. The values are sorted in descending order from the highestpositive value towards the lower negative value. In most cases, the precious alloys showpositive values implying that Ti will be under anodic control. In this scenario if the galvaniccorrosion is triggered, then the alloy under cathodic control (precious alloys) remains immunewhile Ti will be dissolved. In contrast Ti is in cathodic control with all base Co–Cr and Ni–Cralloys which means that Ti will be protected while the base alloys will be corroded under thegalvanic action [21]. Given that galvanic action is triggered when the difference in potential isabove 0.2 V the couples with minimal difference to Ti is ideal to avoid galvanic action andcorrosion of one of the two alloys. As implant-retained superstructures are replaced easier thanimplants themselves, it is recommended that dental implants should be under minimalcathodic control.Couple Potential(V)(Ti)/(60Pd–28Ag–6Sn–6In) 0.067(Ti)/(40Au–35Ag–7.9Pd–7Cu–5In–3.5Zn) 0.002(Ti)/(63.5Co–30Cr30–5Mo–1Si) −0.027(Ti)/(61Ni–26Cr–11Mo–1.5Si) −0.031(Ti)/(61Co–25Cr–7Mo–5W–1.5Si) −0.107Table 5. Difference in potential between Ti and dental alloys in modified artificial saliva with pH 7.2 [20].However, all previous values used smoothly machined or polished Ti surfaces which achievedgreat difference in OCP values with treated root surfaces (Figures 4 and 6). DAE have almost0.2 V difference with MAC surface which can be representative of collar. This means that theexposure of DAE surface and collar to Ringer’s solution is close to galvanic threshold.Differences with MAC surface (collar) is even higher in the case of 2% NaF+Ringer’s solutiondenoting that galvanic corrosion is still possible between collar and root of the implant itselfThe Effects of Surface Roughening Techniques on Surface and Electrochemical Properties of Ti Implantshttp://dx.doi.org/10.5772/62791163 in some cases. Of course, the presence of superstructure facilitates the galvanic phenomenamore. However there is limited knowledge on this matter and definitely further research isrequired in this topic while the development of guidelines for clinicians to minimize intraoralcorrosion of dental implants might have a beneficial effect on longevity of implant-retainedrestorations.Couple Potential(V)(Ti)/(68.9Ag–26Pd26–4Cu–0.9Au–0.1In–0.1Zn) −0.09(Ti)/(76.5Au–12Ag–8Cu–2Pd–1.5Pt) −0.14(Ti)/(66.5Ni–22Cr–9Mo–1.6Si0.5Fe–0.4Ce) −0.22(Ti)/(67Co–28.5Cr–4.5Mo) −0.31Table 6. Difference in potential between Ti and dental alloys in artificial saliva at 37°C [12].Couple Potential(V)(Ti)/(60Au–24Pt–15Pd) 0.210(Ti)/(85.5Au–6.5Pt–4.8Pd–1.5Ag) 0.175(Ti)/(51.5Au−38.4Pd–8.5In–1.5Ga) 0.148(Ti)/(65Ag–23Pd–6.4Cu–2In) 0.099(Ti)/(68.5Au–11.7Cu–11Ag–3.8Pd–3.5Pt–1.5Zn) 0.097(Ti)/(71Au–14.5Cu–9Ag–2Pd–2Pt–1.5Zn) 0.088(Ti)/(63Ni–21.7Cr–10.8Mo–1.8Fe–1.5Si–1W) −0.132(Ti)/(65.2Ni–21.6Cr–10.5Mo1.3Si–0.7Fe–0.5Mn–0.2Yt) −0.167(Ti)/(79.2Ni–14.5Cr–6Mo–0.3Co) −0.191(Ti)/(77.5Ni–13.3Cr–3.1Mo–2Ti–1.5Be–1Si–0.5Co) −0.229(Ti)/(78.4Ni–13.Cr–4.5Mo–3.4Al–0.6Fe) −0.274Table 7. Difference in potential between Ti and dental alloys in Fusayama reagent with pH 5 at 37°C [21].5. Conclusions• Surface roughening techniques significantly affect the roughness, morphology, elementalcomposition, oxide type and electrochemical properties of Ti implants.• Electrochemical properties of dental implants are inferior compared to untreated cpTi apartfrom that of ANO where the electrochemical properties are enhanced.Dental Implantology and Biomaterial164 • Galvanic action might be seriously implicated in corrosion under clinical conditions, a factorassociated recently to peri-implantitis.• Extensive research must be exerted in order to minimize the galvanic phenomena amongtreated root, polished collar and implant-retained superstructure.• ANO of Ti surface significantly increases the electrochemical properties of dental implantsbut these findings must be verified by clinical data.AcknowledgementsThis chapter was supported financially by Vice Deanship of scientific research and researchchairs, King Saud University, Riyadh, Saudi ArabiaAuthor detailsYoussef Al Jabbari1,2*, Wolf Dieter Mueller3, Abdulaziz Al-Rasheed2,4 and Spiros Zinelis5,2*Address all correspondence to: [email protected] Prosthetic Dental Sciences Department, School of Dentistry, King Saud University, Riyadh,Saudi Arabia2 Dental Biomaterials Research and Development Chair, School of Dentistry, King SaudUniversity, Riyadh, Saudi Arabia3 Dental and Biomaterial Research Group, Dental School, “Charite” Medical University of,Berlin, Germany4 Periodontics and Community Dentistry Department, School of Dentistry, King Saud Uni‐versity, Riyadh, Saudi Arabia5 Department of Biomaterials, School of Dentistry, National and Kapodistrian University ofAthens, Athens, GreeceReferences[1] Zinelis S, Eliades T, Eliades G. 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