Like other products of Stomatotech Inc. the SGLA is an innovative approach to the guided surgery. First of all the main feature of the SGLA guide is the stability. Unlike other guides the tubes in the SGLA are adjustable. The inner tube moves in the apical direction until it stops on the bone. That allows the dentist to measure the depth on the occlusal end of the tube and turns the tube into a support of the whole guide (useful for complete, edentulous cases).
Another advantage of the SGLA is; that it doesn't have the CBCT artifact error since it doesn't use the reconstructed model to build the guide. Fabrication time can vary from 10 min. to one hour depends on the base-plate material and the amount of the implants, anyways it's not like waiting days or sometimes weeks to get the guide from Simplant.
The patient should be sent to the CBCT already with a CT guide (mandatory)but there is no need to scan the model or the CT guide separately. Since there is no SLA printing the cost of one guide is mainly the cost of the tubes. One SGLA tube is $10, so you can make the math. The SGLA has only pilot tubes for 2mm drills so this mayby the only drawback.
We all wish for a surviving rate of 10 years and more for all our implants. But how do we achieve that? It is already clear that a successful integration of the implant in the bone is not enough. This is maybe one of the missing complements in the equation. The other components of this equation are less visible, but as much as significant.
Every thing starts from planning. It is proven by many researches that a minimum distance between the implants, and between implants and teeth should be kept. Too lingual or too buccal position of the implant resulting soft tissue trauma or hygiene problems. The solution is guided surgery. A surgical guide produced from a CBCT allows to use maximum of the bone by placing bigger implant in length and diameter with better capacity to withstand heavy load.
The next challenge is to create a restoration that has a passive fit. Monitoring marginal seal and absence of micro-gap using a simple x-ray is not a serious approach.
Up to this moment, there is no mean to check a fit of a framework of fixed restoration in vivo. The only way to achieve a passive fit and a marginal accurate seal is to eliminate from the working process bad factors that were proven, in vitro, and found to be harmful for the accuracy. These factors are: impression transfers, impression copings and lab analogs.
Direct impression with G-Cuff eliminates these three elements and assures a passive fit.
According to Zipprich study about interface micro-gap I don't see any justification to use other connections but tapered. Flat connections infection around the implant, continuous bone lose and implant loss.
Finally, the preservation of the Peri-implant zone from contamination with remains of cement is very important. Using the G-cuff for cementation, prevents the cement from going into the peri-implant area and prevents peri-implantitis.
In order to guarantee a long survival rate for our implants we need three things:
1. Planning and guided implant surgery
2. Direct impression with G-cuff
3. Clean cementation using G-cuff
4. Implants with tapered connection
Following three years of development of the non invasive tissue management cuff, the G-Cuff receives a US patent.
The idea of the invention was born as a result of a twenty years of research and a profound understanding of impression materials properties as well clinical observation of soft and hard tissue behavior.
The G-Cuff allows the dentist to manage the soft tissue around the implant abutment complex without traumatizing the supporting elements. The unique feature of the G-Cuff to prevent cement from going subgingival environment turns the G-Cuff into a device of the choice when a cementation of C&B on implant is required.
Dear reader Imagine yourself an airplane with a high efficiency turbo-jet engines made of railway steel, wood, rope and nails. Sounds absurd? But that's what you get today from the implant manufacturers. For example did you know that the analog is always loose in the body of the stone model? The worse thing that it is not sometimes it is all the times.
Lets see: we pour the stone, the stone expands, the analog is a piece of machined metal with external retentions. Here you go.
Hard to believe? You can check it yourself. Take a stone model with analog. Glue the stone model to a cardboard. Grip the analog with an instrument such as "mosquito". Take a pen or a pencil and draw a line adjacent to the handle of the "mosquito". Then rotate the "mosquito" and draw a second line. Now you see? Yes you do. Want to solve that problem? Start taking impressions with G-Cuff. With G-Cuff you don't need analog.
Passive fit in multi - unit implant restorations
Many things have been said about the passive fit. I want to explain why we have to distinguish between the passive fit of dental implant supported restorations and natural teeth restorations. In case when there is no fit there is a 50 microns of tolerance to adapt. This is the physiologic mobility due to the capacity of the healthy periodontal apparatus to absorb pressure. In case of the implants there is no physiologic mobility of a fully integrated implant thus the tolerance to adapt to pressure is zero.
In case of screw retained fixture such as bar we can calculate how much force will be applied on the implants if by tightening the screws the bar will be expanded by 50 microns. This is very easy to calculate knowing the size of the bar and the metal used in bar fabrication. To calculate we take the Modulus of Elasticity (Young Modulus), in our case it is CrCo which is 300 mega Psi cross section of the bar 3x2mm (in meter units) divided by its length 10mm.(in meter units)
Implant Prosthetic Guides IPG classification
Main Measuring methods
Many things have been said about the IPG classifications, but up to this moment it is more and more confusing. For instance what does it mean model based Surgical Guide? If we scan the model and import it into the imaging software and CAD software, is it model based IPG? Probably yes. Does a guide made from linear markers is a model base? Probably yes too.
So what is the right way to differentiate and to classify the guides?
Well, no matter the technique the common milestone in the process of creating a guide, is linking the model to the image of the CBCT. That link can be done by using two different ways.
The first way is to link separately each implant location by using linear markers that were prepared from drillings of the model (SGLA, Guide Right). In that technique each marker defined as a new X, Y, Z, having value 0 while the common foothold is the apical end of the marker on the CBCT equal to the mucosal end of the model drilling (fig.1 and fig.2)
The second way of linking the CBCT with the model is to create a digital image of the model, to align that image with the image of the digital model resulting from the reconstruction of the CBCT. In that case one point of that 3D image will have a relative value of zero (0) in all three axes x,y,z. Planning one or more osteotomies in that model means expressing mathematically the value relatively to the point zero (0). This method also known as computer numerical control (CNC) Fig. 3 .
The fact that there is a discrepancy between the CBCT and the stone model, resulting serious issues of accuracy in both these methods. However in the first method having resetting the foothold to zero with every new location of the implant preventing the error from being dragged all over the model. Another advantage of the first method is the fact that we actually transfer from the CBCT the angles only and not the locations. The locations of the osteotomy in the first method are linked exclusively to the stone model.
The (CNC) method allows working in a relatively simple algorithm that is much easier for 3D printing manufacturing. In cases where there is an abundant amount of bone (more then 3mm of bone from each side of the implant) the (CNC) method may be applicable.