ORTHODONTIC : Reasons for mini-implants failure: choosing installation site should be valued!

Dental implants conceptually required months for crown placement and functional recovery. 

It was believed that it took weeks or months for cells to colonize the implant surface, produce matrix and mineralize it by efficient osseointegration. 

orthodontic

Science developed and now it is possible to apply a functional load nearly immediately after implants are placed, provided that they are mechanically interlocked in a previously mineralized bone. Appropriate mechanical interlocking between implant and bone surfaces allow mini-implants to withstand masticatory forces while gradual osseointegration occurs. 

The type of bone and clinical condition will determine whether immediate-load implants are recommended or not. Absolute anchorage during orthodontic treatment may be obtained with mini-implants  or miniplates placed in thick cortical bone and dense trabecular bone. 


Mini-implant threads must be perfectly fitted or adapted to the bone where they are inserted, allowing stability and nearly immediately withstanding the forces applied. Mini-implants are also known as micro-implants, micro-screws or anchorage screws, and comprise what is known as temporary anchorage devices (DAT). 

Some specialists suggest that forces may be applied 3 days after mini-implant placement, while others recommend a waiting period of 21 or 40 days. As for immediate loading for absolute anchorage mini-implants, the waiting time is shorter - in fact, it could be immediately applied. 


Cortical bone thickness and trabecular bone density are important factors to be considered when determining a mini-implant placement site. 

Moreover, the material, surgical technique, patient's hygiene care and patient control performed by the professional are also of paramount importance. The main mechanism related to the efficiency of mini-implants for absolute anchorage in Orthodontics is their mechanical adaptation to previously mineralized bone structures. Such mechanism is also known as interlocking. 

After a few weeks or months, osseointegration, represented by cell colonization and bone formation on the surface of mini-implants, will be of secondary importance, given that, at this point, mini-implants can be removed after fulfilling their role of orthodontic anchorage. 



Dental Press Journal of Orthodontics 
Alberto Consolaro, Fábio Lourenço Romano



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