based on the literature the SLA  is the best surface because it increases the BIC 

In term of surface stability, I think that a substractive mechanical treatment can be more stable than an additive chemical treatment. However, implant surfaces stability is a key factor in manifacturing procedures so there is no commercially avaliable surface which present the risk of poor stability.

Furthermore, there is no evidence in literature of SLA surfaces being the best in achieving bone to implant contact.  (Coelho et al, 2011)

Article Characterization of Five Different Implant Surfaces and Thei...

The article that Dr. Toffoli provided does a nice job of comparing different implant surfaces but from what I am seeing in the article all the surfaces were prepared by the same manufacturer. Does this matter? Well other manufacturers would certainly say that it does matter. I think that if you talk to one company that makes or uses an SLA surface they will claim that their SLA surface is different than someone else's SLA surface. In the Coelho article I think, if I'm reading this correctly,  that all the implants were 6-4 alloys. You cannot make a Ti Unite  surface on the 64 alloy, that's what the materials folks have told me at least. The largest producer of SLA surface implants uses a grade 4 titanium commercially pure. So the fact that all the implants in this cited study were made with an alloy, the fact that they were all made by one manufacturer and the fact that they did not test Ti Unite may make the information gathered from this article less valuable to you as a reader or you may look at it and have it not change your opinion at all. This is a question of interpretation.

If we were to say that machine  turned implants, the first generation of implants that were to undergo osseointegration, were the implants that would have the lowest early bone to implant contact this would probably be correct. After a year in function it may not make any difference. In fact micro roughened implants probably make the biggest difference within the first two weeks after the implant was placed and it may have little impact long-term. So when you ask the question of which surfaces better the reality is that there are two viable answers. The first answer might be that in the, let's be generous, first month of the implant being in the bone that micro roughened implants probably recruit more cellular activity and have more early bone to implant contact. The second answer might be that after three years of function it doesn't make any difference.

Why do we want early bone to implant contact? Perhaps this is the most important question. Remember that osseointegration occurs if you are able to limit micro motion, according to Brunski,  to less than 100 µm. Cameron and Pilliar  Compared 150 µm of micro motion to 29 µm of micro motion  and found out that 29 µm allowed osseointegration to occur but  150 interfered with it. So somewhere between 29 and 100 µm is the amount of micro motion that would still allow osseointegration to occur. The reason that we use micro-roughened surface is because it should induce more early bone to implant contact which then means that you have less need for patient compliance. If we ask a patient to avoid chewing on an implant or to avoid use of a removable prosthesis that is placed over the top of an implant we have to realize that most patients are relatively compliant but some patients are not compliant at all. If we figured that the majority are are relatively compliant and we can cut the time during which they need to be compliant in half or in one quarter of the original time requirement we probably will have a slight improvement in the osseointegration rate.

So which is better? Better if we are defining more rapid integration we would probably be able to say that there are slight differences and in many instances those differences are probably more related to study design rather than true superiority.   Long-term, it probably doesn't matter.

Specific to the two surfaces that were asked about, neither of these surfaces should corrode with time. 

Dr. Eckert has clearly stated the correct answer to what would seem to be a simple question. Careful analysis and critical appraisal of the literature can be daunting even for the informed reader. Hopefully the peer review process used by journals would bring these critical issues to the surface so that the reader and clinicians can properly interpret and provide the best care possible for the patient. This benefits everyone.

http://www.ncbi.nlm.nih.gov/pubmed/21092053

I'm not so sure that the reference that Dr. Rashid has provided gives us compelling information on this topic. Six dogs with induced periimplant disease. Two implants appear to have failed to integrate and bone healing was found to be superior  for some Surfaces  rather than others.   it sounds like good information to you realize that you're only looking at six animals. Indeed we have seen clinical reports of soft and hard tissue loss associated with virtually all implant surface treatments.

 I look back on the article by Jovanovic and colleagues that must've been published 15 years ago or more that tested a variety of different surfaces and found that with ligament induced disease hydroxyapatite coated implants  experience the most induced bone response, bone loss, but also were the implants that were most likely to demonstrate bone gain with grafting intervention. It was an old article that basically found that one surface was most likely to be affected and most likely to receive a favorable response with intervention. As I say the article has been around for a long time, it is every bit as good of a study as the more current reference but neither demonstrates information that would lead you to change your clinical practices.

I think the article from Jaffin & Berman (J Periodontol 1991) provides an excellent clinical statement on the problems of  bone quantity/quality in the posterior regions. This paper is corroborated by Lazzara et al (1999) showing the effects of a new implant surface compared to a machined one. So, the point is that the therapy (implant surface) must also be tailored to local bone conditions. Logically, due to market competition, no more machined surfaces exist  in the dental practice; also, the "real biologic state" of bone-implant interface in our patients cannot be measured without biopsies. Regardless of implant surface, poor occlusal control is a  considerable factor for implant failure.

In the old days when we had TPS and HA coatings along with machine turned titanium implants there were discussions about the best location for a specific material.  In the posterior TPS and HA were popular because they gained more rapid bone to implant contact and this helped especially in bone with lower mineral density.  Lazarra described an implant that has about the same micro-roughness as does turned titanium but the surface used by Lazzara was isotropic while turned surfaces are anisotropic...did this matter?  Hard to say.

None the less, as Dr Rossetti states, the market has moved away from machine turned implants.  We are back to a one size fits all now with the vast majority of implants having similar surfaces (albeit, with slight differences).  Today the differences in implants relate to macro-geometry of the implant and the thread configuration.  While years ago there were authors stressing the need to match to implant (meaning implant surface) to the bone type or to a specific anatomic area, these "theories" are pretty well discarded today.

The comment about occlusion is a difficult one.  There have been a number of "occlusion" studies that look at occlusion (dynamic functional occlusion) or intentional misfit (a static load) and only one, to my knowledge, every showed a correlation between hyper occlusion and implant survival.  That article came from Isidore and it correlated with implant failure in primates only when implant restorations were placed in 6 mm of hyper occlusion.  Frankly the study was irrelevant to clinical dentistry because no one would ever make a dental prosthesis 6mm high relative to the remainder of the dentition.