Rationale for Mini Dental Implant Treatment
Mini dental implants can be used to support crowns and partial and complete dentures in compromised edentulous sites. Lack of bone width or site length may be treated with mini implants. Mini implants have less percutaneous exposure and displacement that may reduce complications. Nonetheless, mini implants transmit about twice the load to the supporting bone, and thus, control of occlusal loading is important. In fixed prosthetics, rounded flat cusps, splinting, implant protective occlusal schemes, and placement only in dense bone sites are features of successful mini implant treatment. With removable prosthetics, multiple mini implants may be needed for appropriate retention and load resistance. Maxillary lateral incisor and mandibular incisor sites may be best suited for mini implant treatment. However, past research on dental implants has been directed at standard sized implants. While mini implants are indeed dental implants, they behave somewhat differently under functional load, and the clinician should be circumspect and very judicious in their use. This article is a mini review and not a systematic review. The topics covered are not pervasive because each would require a monograph or textbook for a complete discussion.
Figure 1. After an extraction, the bone remodels and the cortices approach each other. The facial cortex generally approaches the lingual cortex. Figure 2. Cone-beam computerized tomography image of a severely atrophic edentulous site. Figure 3. The atrophic cortices can provide dense osseous support for mini implants. Figure 4. After tooth extraction, bone may remodel and produce different densities of bone. Figure 5. A peaked atrophic ridge may be reduced with a bone burr to produce a flat, wider surface for a mini implant osteotomy. Figure 6. Two mini implants may provide enough support for a molar site.
Figure 7. Immediately after extractions, mini implants were placed. Figure 8. Mini implants immediately placed were grafted with particulate allograft and covered with dermal allograft; any resorbable barrier membrane will suffice. No flap was raised. Figure 9. Splinted crowns supported by mini implants after 2 months of service. Figure 10. Four mini implants are generally adequate retention for a complete removable overdenture. Figure 11. A single mini implant may support a single crown in the anterior mandible where occlusal loads are less, and space may be limited. Figure 12. A clinical view of the mini implant–supported crown. Figure 13. A year 2001 radiograph of a single mini implant in the anterior mandible. Figure 14. A 2010 image of the implant-supported crown placed in year 2001. The crown is still in situ at the time of this writing. Figure 15. A radiograph of multiple mini implants supporting splinted crowns in the posterior jaw where occlusal loads are increased.
Figure 16. A clinical image of the multiple mini implants supporting splinted crowns. Figure 17. An anecdotal image of a mini implant that fractured after several attempts at seating. Metal fatigue may have caused the fracture. Redrilling the osteotomy may relieve the osseous resistance and allow appropriate seating. Figure 18. Teeth may drift mesially and open the interproximal contact between the implant-supported crown and the tooth. Caries can occur inferior to the prior contact area and should be restored to remove caries and restore the contact area. Figure 19. Insoluble cements should be used to retain mini implant retainers. Soluble cement dissolution may occur and subsequently cause an overload of the retained retainers, resulting in implant failure.
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