ABSTRACT

Purpose: The aim of this randomized clinical trial was to evaluate biologic and prosthetic complications with two versus four mini-implants supporting mandibular overdentures in patients with knife edge ridges. Materials and methods: Twelve edentulous participants (6 men and 6 women, mean age =58.47 years) were randomly assigned into 2 groups; Group 1(control); included six participants who received four mini dental implants equally distributed in the interforaminal area of the mandible. Group 2 (study); included six participants who received two mini dental implants the canine area of the mandible. For both groups mandibular dentures were connected to the implants by O-ring attachments. The incidence biologic and prosthetic complications (related to the implants/ attachments and to the overdentures) were measured from base line 12 months after overdenture insertion and compared between groups.

Results: The implant survival rate, peri-implantitis, pocket depth >3mm, bone loss >1mm, separation of the metal housing from the denture base, teeth fracture, overdenture fracture, and denture relinings did not significantly differ between groups. The 4-implant group showed significant higher pain, edema, peri-implant mucositis, teeth wear, and denture border adjustments than the two implant group. The 2-implant group showed significant higher abutment bending / fracture, O/ring wear/ distortion, and O/ring damage/replacement than the 4-implant group

Conclusion: Within the limits of this short term trial, 2 mini-implants may be a suitable alternative to 4-mini-implants when used to retain mandibular overdentures as it was associated with reduced pain, edema, peri-implant mucositis, teeth wear, and denture border adjustments. However, 2-mini-implants are associated with increased prosthetic complications related to attachments as abutment bending /fracture, O/ring wear/ distortion, and O/ring damage/replacement.