Why don't more dentists use mini implants for fixed full arch?

Mini dental implants have been used to stabilize a loose denture or to replace a missing tooth if the space is too small.  For a full upper screw retained upper denture or porcelain, it is not the best option.  The cost looks appealing to most patients but the long term result may be compromised.  The implants selected to hold the full arch are chosen to have as much height and width as possible to take the chewing forces.  Bone quality also affects what an be used.We like to place a long lasting implant with teeth that look, chew and feel like natural teeth.  Have a few consultations with doctors who have a team of dentists who can place the implants, restore the teeth and followup. 

Determining success of treatment require data on many cases and long term success. This was never the case with mini dental implants. Mini dental implants can only be used successfully to support removable dentures or a single small tooth. The cannot support multi teeth fixed restorations. The result would be failure on the short term. 

The answer to this question is really very simple & quite obvious. Mini dental implants have far less surface area to allow for integration with the surrounding bone as compared to full-size dental implants. This means they are far less capable of withstanding the tremendous forces that we exert during function and they are far more likely to break down.To use an example that most people can relate to, consider the

Mini-implants are by their very design much thinner than other implants.  They were designed to either fit in tight areas between existing teeth or if there are no teeth and need full arch restoration...they are placed and used as over-denture removable bridges.  They work best if at least 4-6 are placed in the lower jaw or 6-10 in the upper jaw (due to more porous bone).. not all implant dentists prefer them and would like to use a wider diameter implant where possible for broader bone adaptation.  They are not designed for FULL arch replacement on a fixed cemented basis.

Personally I have used mini implants for denture retention in both the upper and lower jaw. I would never use them for replacing missing teeth with a fixed, cemented in bridge. My feeling is that these implants are really not designed for that type of restoration.