in the case of GBR and some special surface coated implants such as those with fluorapatite, that precise adaptation may not be as critical as for others.

Primary stability is an important factor specially when planning immediate provisionalization or loading but it's not a "must" for osseointegration to occur. If you have type III or IV bone and primary stability is not achieved but the implant is fully surrounded by bony walls, there's no reason to believe you won't achieve osseointegration.

That's an interesting question. If you were to prepare a 6mm wide osteotomy and place an unsecurred 3.5mm wide fixture and close it with soft tissue, I'd imagine that the implant might very well become integrated. The socket without the implant would fill with a blood clot, turn over into osteoid and eventually fill with woven and then lamellar bone, and if soft tissue were to be excluded, perhaps the implant would integrate -- we just wouldn't know the position or tilt of the implant until it's all healed. It'd be an interesting investigation!

Nelson -- I'm new here so I'm not sure how to do this, but I want to send you two articles that discuss osseointegration with 0 initial bone contact, if I can find your email address -- the implants were fixed, though, by using adjacent implants and a substructure framework.

Roberto Villa, Giuseppe Polimeni, Ulf M. E. Wikesjö. Implant osseointegration in the absence of primary bone anchorage: A clinical report. J Prosthet Dent 2010;104:282-287

Stefano Sivolella, Eriberto Bressan, Luiz A. Salata. Osteogenesis at implants without primary bone contact – An experimental study in dogs. Clin. Oral Impl. Res. 2012;23:542–549

I'll try to send it through email.

Nasser, I.P.PT, Universiti Sains Malaysia.

First it is very important to study the factors that cause looseness of the implant, like smoking, clenching, radiotherapy or chemotherapy then try to manage these factors as possible and change the implant to another suitable site after estimating the bone width and bone height. May be you need to use bone graft with this case to ensure bone integration.

Its a weird question but plausible, my point of view that it is important because of bone healing.....imagine you have a skin wound if you keep scratching it the longer time it will take to heal and the more chance you have at scarring your skin...

So if you don't have primary stability with your implant you the higher the chance of fibrosis around the implant.

But that doesn't really disapprove your point of view.. Its just that there hasn't been much researches in vivo of the need of primary stability...

Primary stability is the pre-requisite for successful osseointegration. Bio-oss and bioguide may promote bone formation; however, these materials cannot stabilise the implant immediately after surgical placement.

Loosening or micromotion might cause break down of the newly formed bone and subsequent formation of fibrous tissue encapsulation. Probably, this micromotion might activate macrophages and prevent bone formation. Nevertheless, factors such as, the degree of micromotion, type of bone, implant surfaces, health status of the patient should be taken in consideration.

we should not confuse initial primary stability (insertion torque values) with micro (

Indeed, primary stability is essential. Macromovements (as George Michelinakis said) will certainly lead to fibrous encapsulation.

you need a minimal stabilization in the apical zone or supporting in one socket wall , and the complete closing with a adequate flap reflexion can achieve osseointegration. a Guided Bone regeneration can improve your results.

Thanks, to for all the good comments.

We are all agree about primary stabilization , micro and macrovement and the different types of bone density that may affect the primary stability and the insertion torque value plus that we should have good manage of the soft tissues around it. And we all are agree that this is a must to get osseointegration and good long term prognosis.

What I really mean in my question is: what happens ? if we are in a situation where we end in a larger preparation than the implant size, with no primary stability at all, cero insertion torque value - no direct bone contact in any bone wall and no way to get minimal stabilization in the apical zone or to use a screw or mesh to stabilize it - and even more we can not get a complete closing of the site with the flap reflexión.

Should we abort the implant placement?, there is any chance if we place the implant to get osseintegration? and even more, to have a complete functional single implant with a single crown on top of it after few months . I would like your comments on this.

Under that conditions the best option is to delay the implant placement 2 months at least

In my view, CT scan can provide more relevant information regarding the amount of bone available after osteotomy. In other wards, a proper treatment plan might be helpful to avoid larger preperation. However, the question is, can we use larger implant size to get some bone-implant contact? if we cannot, then bone substitutes or autogenous bone graft and flap closure is the best solution and wait for 3-5 months until bone healing and regeneration occur.

Actually, it was surprising for me as i had a case where 2 implants were not stable at the time of insertion and then they became stable after a couple of months, but of course this is one case and the answer to your question need more research work

Dear Dr Pinto,

The premise upon which Osseointegratability of an Implant is based, is the availability of "adequate" number of bone building units (BBUs) around the perimeter of the Implant upon its insertion.For it is the presence of these units that is an assurance of the ability of the peri-implant native bone to be able generate the optimal quality and quantity of Bone progenitor cells and the establishment of an environment for Osteogenesis and thereafter Osseointegration.

Since the first 2 weeks after Implant placement is characterized by a catabolic phase predominantly, concommittant to the inflammatory phenomenon that accompanies Osteotomy site preparation as well as tissue response thereafter, there is a significant loss of this very environment (causing a depletion in the BBUs inevitably) during this period (Refer -Cruess & Dumont, 1975)

In the event that there is a lack of Primary stability (characterized by sub-optimal torque), it denotes a deficiency in the number of BBUs in the vicinity of the Implant. Obviously this would add up and furhter compromise the host environment, leading to a lack of Contact Osteogenesis, and perhaps promote Distance Osteogenesis at best. In fact, the discrepancy between healing processes in the Mandible and Maxilla after placement of the Implant (of the same macro/micro features); is an allusion to this very fact. Higher Insertion Torques in the Mandible are often a representation of the abundance of BBUs in the mandible as represented by the highly compact trabeculae and dense mineralized bone.

So, if you were to achieve less than optimal Torque in a particular situation, it would be debatable whether it would head straightaway in the direction of Fibrous encapsulation (or Fibro-osseous integration - Ref C Wiess, 1987)

As suggested by a colleague in a previous response, it would perhaps be prudent to graft and return after the prescribed period (based on the resorbability and conversion of that graft material) to place an appropriate configuration of implant at a later date instead of wrongly choosing to place a 'wider' diameter than necessary simply because one has an osteotomy diameter that can take that size of implant.

It is almost like inserting a nail with larger diameter in relatively smaller diameter hole gives more stability compared with a nail and access hole of same diameter. That is because of condensing the adjacent bone and making it relatively denser when osteotomy site is smaller than the implant, which in turn improves stability. (more stable in dense bone)

It is logical that more stable nail will last longer and also takes more load than a one with less stability. Same holds good with implants

the principles of osseointegration have been throughly studied since the time of BRANMARK.primary stabilty is pre requesite for osseo integration. aim is to achieve osseointegration and not fibro-osseous integration.

Nelson~

I'd like to address a number of the comments here for clarification:

Primary stability is the initial stationary relationship of the implant fixture, via either direct or indirect fixation, relative to the surrounding alveolar bone and/or bone graft material and/or barrier membranes. Osseointegration is the secondary phenomenon of bone fusing onto the surface of the implant fixture. In order to achieve appropriate osseointegration, the implant fixture must remain fixed relative to the bone much like the fixation between two fractured edges of a long bone -- otherwise, fibrous encapsulation occurs, analogous to the non-union or mal-union between improperly fixated long bones.

1) Samira states that "in the case of GBR and some special surface coated implants such as those with fluorapatite, [the] precise adaptation [of primary stability] may not be as critical," but this ignores the tenet that primary stability exists to permit a fixed spatial relationship between the bone and the fixture in order to allow for the bone to grow onto and then ankylose the implant. Guided bone regeneration has nothing to do with avoiding the need for this rigid fixation of implant to the surrounding bone, and neither does fluorapatite, which is merely meant to increase the rate at which bone deposition occurs -- notwithstanding the increased rate, it will still not be instantaneous, and lack of a fixed relationship between the implant surface and the surrounding bone will result in fibrous encapsulation.

2) Saurabh makes the claim that "micro-movement in the molecular structure of bone" is relevant, but the key point here is not movement within the bone, but rather movement of the osseointegrating fixture relative to the osseointegrating bone.

3) Fernando erroneously asserts that primarily stability is "not a must for osseointegration to occur" -- please provide evidence in the form of a clinical trial before making wild claims such as this. He also states that "if you have type III or IV bone and primary stability is not achieved but the implant is fully surrounded by bony walls, there's no reason to believe you won't achieve osseointegration," but this is also stated without existing evidence. Any bone in which the fixture is safe from micromotion in excess of ~150 microns can potentially provide for osseointegration, but it's certainly not a foregone conclusion, as Fernando pretends. Four walls provides for retention of the healing clot, not immobilization of the implant relative to the surrounding bone.

4) Nasser states that things like smoking, clenching, radiotherapy or chemotherapy are "factors that cause looseness of the implant" -- this is just not true. Smoking compromises wound healing and angiogenesis, but doesn't contribute to implant loosening is a direct fashion. Clenching will only lead to implant loosening if the implant is attached to a transgingival component or is placed under thin tissue under an overlying removable appliance that is able to transmit forces to the fixture during healing. And both radio- and chemotherapy are both similarly not responsible for any direct "loosening of implants."

5) Mohammed says "if you don't have primary stability...you [have a] higher chance of fibrosis around the implant," seemingly implying that one can have lack of primary stability and have some reasonable expectation of osseointegration. This also downplays the notion that rigid fixation of the fixture relative to the bone is a necessary component to proper hard tissue integration.

6) George mistakenly equates initial primary stability with insertion torque value. As demonstrated by investigators like Villa (above), primary stability need not be maintained by the surrounding bone, and thus insertion torque need not be high, or actually, even present. Primary stability of press-fit implants would not be described with torque values, yet present valid means of achieving osseointegration.

7) Einer makes some comment about the need for "minimal stabilization in the apical zone or supporting in one socket wall" -- but primary stability can just as well be provided by coronal stabilization, or even external stabilization by a bar or connection to adjacent teeth.

8) Ahmed states that a "CT scan can provide more relevant information regarding the amount of bone available after osteotomy," but despite the fact that CT offers exquisite accuracy (Sonick 1994), it has been shown that Misch's A-D bone type classification, along with similar I-IV classifications, is terribly poor at being able to be sued to actually clinically differentiate between the middle two categories (Trisi 1999). Even so, CT scans do not provide reliable information relative to whether or not primary stability will be achieved.

9) Satyanaranayana makes an analogy to a nail in a wall: "That is because of condensing the adjacent bone and making it relatively denser when osteotomy site is smaller than the implant, which in turn improves stability. (more stable in dense bone) It is logical that more stable nail will last longer and also takes more load than a one with less stability. Same holds good with implants"

While the nail in the wall is a good analogy for primary stability, if fails to convey any notion of increasing stability that accompanied osseointegration. A nail achieves its greatest stability in a board of wood the day it's placed -- it never develops a greater stability. Not so for dental implants, which require primary stability only until osseointegration kicks in after a few weeks/months. Once the bone fuses onto and ankyloses to the implant surface, the degree of primary stability and manner in which is was provided makes no difference.

Dr Dale thank you so much for your comments. But do you mean that CT scan can not differentiate between grade II and III bone type according to bone classification?

and what means you think are more reliable to determine the achievement of primary stability?

Please read the work of "Osteogenesis at implants without primary bone contact - an experimental study in dogs.

Sivolella S, Bressan E, Salata LA, Urrutia ZA, Lang NP, Botticelli D.

Clin Oral Implants Res. 2012 May;23(5):542-9. doi: 10.1111/j.1600-0501.2012.02423.x. Epub 2012 Feb 15".

Dear Dr. Dale

Your question as an exercise its very good. But as a reality its not possible.

The concept of primary stability its one of the fundamental factors that affect the osseointegration of the implant. Sometimes by the use of different appliances we could obtain information regarding specific values of implant stability, previously to the implant insertion (Bone Density Evaluation by Scan Tomography or other image techniques), or during and after implant insertion (Insertion Torque, Perio Test Value, Resonancy Analysis).

Implants with lower values of primary stability could osseointegrate in the abscence of micromovement, if you use biomaterials to fill the gap and to ensure the osteoconduction and if you use membranes to avoid the soft tissue migration.

If you insert an implant in a big space without no single contact with the bony walls, or without the use of some biomaterial that ensures the osteoconduction, or initial stabilty its impossible to avoid the formation of fibrous tissue around the implant surface.

In your specific case the osseointegration of the implant is extremely impaired and risky, because the implant will continue moving inside the cavity, you leave to the random the osseointegration.

All the best

My answer was for Dr. Nelson Pinto, so Im sorry for include Dr. Dale in my previous message (I agree 100% with Dr. Dale)

Dear Dr Rafael,

I think the primary implant stability is related to the bone quality more than bone quantity. This is what I understood from Dr Dale discussion and I know that primary stability can be measured by different means e.g periotest...etc. But the question is how we can evaluate bone quality before osteotomy preparation?

Dear Dr. Ahmed:

Among the factors that could affect primary stability for sure we have to included bone quality. However we can´t exclude the quantity, please imagine a implant in the first molar region of the maxilla within the sinus area, althought the implant possess a good primary stability (35Ncm), the lenght of the bony portion that are in contact with the implant its crucial. So the evaluation of the quantity is another factor to include.

Thinking in the primary stability as a mechanical factor, more surface of bone in contact with the implant its preferable to less surface of bone in contact with the implant.

Before Osteotomy preparation the bone quality (availability) could be avaluated:

1. Densitometric analysis (pixels) and volumetric analisys (voxels) depending of the diagnostic technique.

2. Bone Dimensions (Quantity)

3. Other experimental techniques as bone thermography could be included as Ultrasonnography that could be applied to the cortical bone. (Experimental)

During the Osteotomy

1. Drilling subjective tactil sensation (operator)

Posterior to the osteotomy

1. ITV (Insertion torque value)

2. RFA (Resonance Frequency analysis)

Best regards

RAFAEL

Dear Dr Rafael,

Thank you very much for your explanation. I understood that both bone quality and quantity are important to achieve primary stability. From your example, it seems to me that the bone-implant surface contact is crucial to achieve primary stability since bone quality in this region is more cancellous than compact.

Best wishes,

Ahmed

Contact osteogenesis must for integration.

Thank you all, for taking the time to participate in this debate, and for your interesting answers.

Of course you are all correct and I used to think the same way .

I add this question a year ago to see the reaction to such statement .

I know it may sound unbelievable but, it is possible to get osseointegration of an implant under such conditions, without any initial stability and no bone contact .

Beyond that , after four to five months the implant can bel loaded and become completely functional .

I have been followed these implants for two years now, and you can´t tell any difference in any way with an implant placed , lets say by a "regular implant protocol".

I´m not saying we should propose this as a routine technique , is just to show from this pilot study that we still don´t know some intrinsic characteristics of the osseointegration process .

Moreover the paradigm of primary stability and initial bone contact could be questioned due to the new implant´s surface new design and the recent advances in biotechnology, biomaterials, and tissue engineering that are changing the way we used to see the healing process .

Sure, the primary stability is very important for the osseointegration, the implant will fail practically if there is no primary stability (loose implant from the beginning will result in fibrous tissue formation instead of osseous tissue and the implant will be lost)

I had a case of one biohorizon implant which placed for young women to replace Lower 1st molar, at time of placement I couldn't get primary stability that the implant turned around it self ( zero primary stability ) after 4 month the stage II procedure performed and I am suprized that the RFA of this implant was 80% with nice Osseo integration radiographically