What size cheek implant (Conform Midfacial Implantech) is equal to 1 syringe of filler?

When trying to compare fillers to implants, the definitive method is by weight comparison. Having actually studied it, it takes over 1.5 cc of filler for a small to medium midfacial implant of the style and manufacturers you have listed. But regardless of these comparisons you want to stay in the smaller side with your thinner and more lean face. A midface implant will not improve your undereyes nor the nasolabial folds.  

 Both the cheeks and the Cheek implants are three-dimensional structures, so a thorough examination of the face is required to make a determination about the appropriate sized and shape implant. In our practice, we use Implantech solid silicone cheek implants for over 25 years with an excellent success rate. They can be custom carved when necessary to match patient's unique anatomy and asymmetries. The implants are not designed to help the nasolabial fold, just augment the mid-face. They are also manufactured the large variety of sizes( small, medium, large, and extra large) and a variety of shapes (malar, sub-malar, and combined). For more information  and many before and after examples cheek implants, please see the link and the video below

Re posting my earlier response, "As long as you understand fully the increased risks of oversized implants and infection rates than if your chosen surgeon is ok with the sized implant chosen that it is your decision. Personally, I stopped cheek implants years ago because of infection rates. I use long lasting HA fillers with slow build up, i.e. Voluma (at least 4 syringes), plus Sculptra injections for collagen in growth, sometimes with Silhouette InstaLift sutures/PDO threading, or doing The Y Lift (filler facelift). ".....

 Hi, I have performed many facial shaping procedures using dermal fillers, silastic facial implants (cheek implants, chin implants, lip implants), liposuction and/or facelifts for over 30 years.  As you may have learned already there are many different opinions on how to shape the face and augment the cheeks.  I completely disagree that cheek implants have high rates of infection, rejection or malposition (moving) when properly placed.  In my experience and humble opinion, cheek implants are the best tolerated implants used anywhere in the body with an extremely high rate of aesthetic success, longevity (permanent) and history of providing the "most natural" results.  For these reasons, I feel that properly silastic cheek implants remain the "gold standard" in cheek augmentation.  I do however feel that placing implants is far more technically challenging than injecting an off the shelf dermal filler or fat that simply does not last in a predictable manner (more on fat below).   From the photos, your cheeks are very full and round on the sides with roughly 75% of the ideal shape and volume.  There are, as you mentioned, some flat spots in the front with tissue thinning along the sides which adds angularity to the cheeks and face.  In my practice, I place many silastic cheek implants in both men and women.  
 Following my beauty principles, women look the most feminine, youthful and attractive with heart shaped faces.  Heart shaped faces have cheeks that are full and round in the front.  Cheek augmentation with a dermal filler or using cheek implants for a permanent enhancement will create full, round cheeks that will feminize the entire face.  Conversely, men look chiseled and handsome with angularity in the cheeks, chin and mandibular angles.  The issues is when there are "isolated" areas of the cheek (typically in the front) that require augmentation but the remaining area of the cheek is already prominent.  This is your case and although an in person consultation is always the best for evaluating cheeks and facial shape, using a cheek implant would make the cheeks too large overall in my humble opinion.  The conform style implants flatten out which would add a flat structure to an already concave or flat front section of the cheeks resulting in a "flat" result.  To achieve a convex, full, round, front portion of the cheeks alone (while at the same time avoiding over sized cheeks) would entail precise placement of a dermal filler.  In some cases I can gently rasp down "high spots" on the other portions of the cheeks but it makes no sense to me to rasp down 75% of the cheek shape to augment the front 25%.  In these types of cases, again in my humble opinion, using a small portion of an implant (carved or custom) would not provide as effective of an aesthetic solution as precise placement of an off the shelf dermal filler.  Perhaps you can try Radiesse instead of an HA filler to see if you have better luck with that filler.   In my experience and despite its recent increase in popularity, fat transfer (fat injection) offers "far" less of a reliable and predictable volume for facial shaping than an off the shelf dermal filler or facial implant.  For that reason, I do not use fat to shape the cheeks, chin, lips or jaw line.  Tissue physiology is quite simple.  Tissue requires a blood supply in and out as well as lymphatic connections to remain viable and alive.  Once fat is removed from the body all of these things have been disrupted.  Just because the removed fat is mixed with PRP or something else doesn't make the blood and lymphatics magically re-appear.  The fat at that point is not living tissue which means that it's prone to being dissolved by the body (most likely in an uneven and unpredictable manner).  Injecting fat back into the face does not create the required elements to make the fat living tissue once again.  So the argument that fat is alive and viable in the face once it's been removed and re-injected makes no sense to me as a physician and surgeon.
 The other issue that I have with fat transfer is the lack of precision.  Fat is thick by nature which means it's not the same consistency as an off the shelf dermal filler.  Fat injections use an increased volume injected in an attempt to compensate for the volume loss that "will" happen.  This means a lack of specific shape and volume that simply can not begin to compare with the specificity of using a silastic facial implant of a "known" shape and volume.  In that regard fat offers too much of an unknown to make it a reliable and predictable method for facial shaping.  There's a significant difference between a 3mm and 5mm thick cheek implant.  You can imagine the magnitude of difference there is between retaining 60% of 25cc's of fat versus 35%.  In my humble opinion, I just don’t see how fat could possibly be used to precisely shape facial features?
Hope this helps.