Immediate Loading Implant-Retained Overdenture: A Randomized Controlled Study.
The predictability of dental implants has changed the prosthetic rehabilitation of mandibular edentulous patients. The preponderance of recent evidence suggests that the use of dental implants to retain mandibular overdenture has significantly improved clinical outcomes and quality of life.1, 2 Moreover, using unsplinted implants with a mandibular overdenture improves patients’ satisfaction, and appears to meet expectations in edentulous patients.3 It has been suggested that implant retained mandibular overdenture may be considered the standard of care treatment in mandibular edentulism of which implant supported fixed prosthesis is not treatment of choice.1-3
Branemark’s initial recommendation called for a healing period of three months prior to
loading mandibular implants.4 Thus, conventional treatment with implant-retained overdentures requires that, the attachments be installed no sooner than three months after implant placement. This delay in loading often presents a significant detriment to a patient’s function quality of life.
It has been suggested that implants with enhanced surface microtopography can achieve secondary stability at earlier healing times.5 Several clinical studies on different
implant systems showed that the loading time for implant retained mandibular complete overdentures can be safely shortened without compromising osseointegration process and implant success rate.6-10 Delayed or early loading of implant-retained mandibular overdentures
showed equivalent success rate when implant retained mandibular complete overdenture opposed a maxillary complete denture.6-8 Several studies on immediately functional loaded and splinted implant-supported overdenture reported high success rates.11-15
The aim of this study was to clinically and radiographically compare implant stability and crestal bone changes around implant immediately loaded versus delayed loaded implant to retain mandibular overdenture.
This study was a single site, randomized, controlled, and prospective clinical study. Twenty completely edentulous patients were enrolled in this study from the clinics of the University of Kentucky, College of Dentistry. This study was received IRB approval.
Each subject was randomly assigned to one of the treatment groups:
Test Group (n=10): The test group were received immediate loaded unsplinted implant retained mandibular complete overdenture (20 implants). 1 patient dropped out of study.
Control Group (n=10): The control group were received delayed loaded unsplinted implant retained mandibular complete overdenture (20 implants).
All participants received new maxillary and mandibular complete dentures prior to implant placement. The two implants were inserted under local anesthesia following the routine administration of prophylactic antibiotic medications one hour prior to the surgical procedure. A crestal incision was made and full thickness flap was conservatively reflected to reduce the possibility of postsurgical swelling and to allow surgical access to the implant sites. The implant positions were pre-determined with a surgical guide. Two osteotomies at the site of mandibular canines were prepared according to the protocols specified by BioHorizons®. For both test and control groups, implants were inserted and peak insertion torque was measured immediately. Implant stability quotient (ISQ) measurements were recorded by using resonance frequency analysis (RFA) using Osstell mentor®. Using the manufacturers’ guidelines, Smartpig type 4 were attached to the implant platform and the mean of two consecutive ISQ values were calculated. Then locator abutments were connected to the implant fixture with 20 Ncm torque in the test group and cover screw were placed into implant fixture in the control group. The flap was sutured with “4-0” Vicryl® sutures to achieve tension-free primary closure. The complete denture was modified by creating a space in the intaglio surface for the metal housing of the attachment. The attachment were picked up intraorally with Quick-Up® autopolymerizing resin. Cone Beam CT scan was made immediately after implant placement for research purposes for both groups. For the control group, the locator abutments delivery and intraoral attachment pick up were performed at 3-month following implant placement.
No statistically significant difference between groups (p > .05
Recent study by Elsyad et al, found no statistically significant difference in implant stability at 12 months between immediate and delayed loading groups.14 Ma and Payne found no detrimental effect on marginal bone levels with immediate loading protocols,15 while others found statistical significance in levels of increased vertical bone loss around immediately loaded implants compared with a delayed loading protocol.14
This preliminary data supports a suggestion that any difference in crestal bone loss found between groups may be considered to lack clinical significance for outcome measurements. Further long term evaluation of
crestal bone height remains necessary as immediate loaded IOD is utilized more in clinical practice. Preliminary data reflecting ISQ values supports previous findings and suggests that immediate loading of implants achieving optimal primary stability yields predictable results at 3 and 12 months. 14
Although, the limitations of this study and the small sample size, the results are clinically relevant and significant. Immediate loading protocol for unsplinted implant retained mandibular complete overdenture is predictable treatment, safe, and as successful as delayed loading protocol.