###### Abstract  
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 \(\times\) 10 mm) and experimental (CMI IS-III active(r) short implant; 5.5 \(\times\) 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 (ISO) 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, ISO 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. Keywords:dental implants; short dental implants; immediate loading; primary stability; digital work flow +
Footnote †: journal: Applied Soft  
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installation with a fully digital, model-free pathway [1]. A virtual model of the patient is easily created by merging DICOM (Digital Imaging and Communications in Medicine) files obtained from CBCT (Cone beam computed tomography) imaging and standard tessellation language (STL) files obtained from intraoral scanning via the virtual implant planning software [2]. Furthermore, the virtual implant planning and the CAD/ CAM implant-supported, screw-retained interim restorations can be designed and fabricated digitally according to the planned implant placements on the same program [3]. Moreover, the associated computer-guided surgery offers patients the benefits of minimally invasive implant placement without flap elevation (flapless surgery). This procedure also provides multiple advantages, including decreased postoperative pain and trauma, short recovery time, reduced intraoperative bleeding, and further preserved soft and hard tissue [4; 5]. In the posterior mandible the bone height is limited by the inferior alveolar nerve as well as physiologic bone atrophy after tooth extraction. Numerous techniques, such as guided bone regeneration (GBR), block bone grafts, distraction osteogenesis, and transposition of the inferior alveolar nerve, have been used to increase available ridge dimensions where significant horizontal and vertical bone loss has occurred [6; 7]. Although bone augmentation techniques are proven to be predictable and successful [8], patients may not accept such treatments fearing donor site morbidity, invasive operation, additional cost, and longer treatment time [9; 10]. Short implants with length shorter than 10 mm, can be considered an effective alternative treatment option in reduced bone height to avoid invasive bone augmentation procedures.