3D Evaluation the Accuracy of Free-Handed-Countersink Guided and Fully-Guided Implant Surgery in Partially Edentulous Patients: A Clinical Trial With Quasi-experimental Study

This clinical trial with a quasi-experimental study design explores the comparative accuracy of dental implant placement using three different surgical protocols in partially edentulous patients: free-handed countersink guided, fully-guided, and traditional freehand methods. The precision of implant positioning plays a pivotal role in the long-term success and aesthetics of dental implant therapy. Although osseointegration is fundamental, optimal functional and esthetic outcomes are contingent upon the precise three-dimensional positioning of the implant within the jawbone. The rationale behind this study stems from the clinical observation that improper implant placement can result in technical and biological complications, leading to treatment failure or compromised prosthetic outcomes.

The advent of digital imaging and surgical planning has revolutionized implant dentistry. Traditional radiographic stents and manual implant placement methods have been increasingly replaced by static computer-assisted implant surgery (s-CAIS), allowing for improved preoperative visualization and enhanced implant positioning accuracy. In the digital workflow, combining intraoral scans with cone-beam computed tomography (CBCT) enables clinicians to plan implant positions based on bone quality, soft tissue contours, and the spatial relationship with adjacent teeth or anatomical landmarks.

Despite these advancements, there remains a lack of clinical evidence on the performance of countersink guided protocols specifically. Countersink guided placement involves using drills designed to widen the crestal cortical bone, especially in cases of dense bone, facilitating a passive fit of the implant at the neck. This approach is typically categorized under the freehand technique but is believed to offer enhanced stability during insertion. Fully-guided surgery, in contrast, utilizes a prefabricated guide that controls each step of the drilling and implant placement process, theoretically minimizing deviation.

The study involved the recruitment of partially dentate adults who fulfilled strict inclusion criteria such as having at least six remaining teeth, good oral hygiene, sufficient bone volume for implant placement without the need for grafting, and the ability to maintain mouth opening of at least 40 mm. Patients with parafunctional habits, heavy smoking, psychiatric or systemic conditions that contraindicate implant surgery, a history of radiotherapy in the head and neck region, or younger than 18 years of age were excluded.

Each patient received two implants-one placed with the countersink guided freehand method, and the other placed using a fully-guided surgical protocol. Both procedures were performed by the same surgeon using a parallel surgical kit (Dentsply®, MIS, M4, Germany), ensuring consistency in technique and instrumentation. The implants were placed on the same day and with identical preoperative planning to eliminate inter-operator and time-related variability.