One-Year Results of a Randomized Controlled Clinical Trial of Immediately Loaded Short Implants Placed in the Lower Posterior Single Molar Using a Complete Digital Workflow

The purpose of this randomized clinical trial is to evaluate immediately loaded single implants with varying lengths in the posterior mandible using a fully digital, model-free prosthetic-driven implant planning pathway, and to compare clinical and radiological outcomes of short and long implants. The 52 patients with the single tooth missing in the posterior molar regions of the mandible were randomly assigned to the control (CMI IS-III active((R)) long implant; 5.0 x 10 mm) and experimental (CMI IS-III active((R)) short implant; 5.5 x 6.6, 7.3, 8.5 mm) groups. For each patient, a single implant was placed using the computer aided surgical template and all prostheses were fabricated by means of computer-aided design/computer-aided manufacturing (CAD/CAM) system on the virtual model. The patients received provisional and definitive monolithic zirconia prostheses at 1 week and 12 weeks after implant surgery, respectively. The implant stability quotient (ISQ) measurements and periapical radiographs were taken and peri-implant parameters were evaluated at 1, 3, 4, 8, 12, 24, 36, and 48 weeks after surgery. Nineteen long implants and 27 short implants were finally used for the statistical analysis. There was no significant difference between the groups in terms of insertion torque, ISQ values (except 3 weeks), marginal bone loss, and peri-implant soft tissue parameters (p > 0.05). Both groups exhibited no stability dip during the early phase of healing. The average marginal bone loss from the baseline of implant placement for the control and experimental groups was -0.07 and 0.03 mm after 12 weeks and 0.06 and 0.05 mm after 48 weeks. All of the soft tissue parameters were within normal limits. Within the limits of the short term follow up, immediate loading of short single implants can be considered as one of predictable treatment modality in mandible with reduced bone height when primary stability can be achieved.