Flapped versus flapless surgery and delayed versus immediate loading for a four mini implant mandibular overdenture: A RCT on post-surgical symptoms and short-term clinical outcomes.

OBJECTIVE

This factorial randomized clinical trial (RCT) tested the effects of the surgical approach (flapped-FPS vs. flapless-FLS surgery) and loading protocol (delayed-DL vs. immediate-IL) for treatment with a four mini implant mandibular overdenture.

MATERIAL AND METHODS

A total of 296 one-piece titanium-zirconium mini-implants were inserted in 74 patients (IL/FLS = 17; IL/FPS = 18; DL/FLS = 20; and DL/FPS = 19). Outcomes included patient's perceived surgical burdens, clinical time, implant survival, and post-surgical symptoms and complications, assessed immediately after surgery, in the 7-day and 6-week follow-ups.

RESULTS

Perceived surgical burdens were relatively low, higher for females, and no difference was found between FPS and FLS surgery. Surgical time was lower for FLS surgery. Overall symptoms were mild after 24 h, and higher for females. Less symptoms were recorded for the FLS surgery compared to the FPS for the delayed loading patients, and FLS surgery was associated with a lower risk of bleeding. No early implant failure was observed until the 6-week follow-up. Delayed was associated with discontinuous use of the prosthesis and poor function. Lower complaint rates were observed for immediate loading regardless of the surgery protocol.

CONCLUSIONS

Mini implants for mandibular overdenture are a feasible option regardless of surgical access and loading protocol, with high safety and predictable survival rates, and low incidence of post-insertion complications. FLS surgery requires less clinical time and results in easier intraoral prosthetic incorporation of attachments compared to FPS surgeries. Immediate loading did not increase the risk of early implant failure when satisfactory primary stability was achieved.