Ⅰ. Introduction
Conventional dental implant surgery typically requires flap elevation to allow direct visualization of the alveolar bone morphology before implant placement.1 However, advances in cone-beam computed tomography (CBCT) and implant planning software have popularized flapless implant surgery, which allows for three-dimensional evaluation of the surgical site without raising flaps.2,3,4,5 Flapless surgery entails direct osteotomy through the gingiva to the alveolar bone using rotary instruments and a tissue punch to preserve the blood supply, soft tissue architecture, and bone volume. These benefits include a reduced surgical time, less patient discomfort, and rapid healing.6 Despite these advantages, flapless surgery is limited by the lack of direct visualization of anatomical landmarks and vital structures, risk of thermal damage from restricted irrigation, potential perforation of buccal or lingual bone plates due to malangulation, and reduced control over implant depth.7 The technique becomes especially challenging when the alveolar bone width or keratinized gingiva is insufficient around the implant site. Consequently, conventional flapless techniques are generally limited to cases with adequate bone and soft tissue conditions, requiring experienced clinicians.
This case report introduces a minimally invasive implant technique utilizing a 1 mm guide pin in the alveolar bone as a stable landmark for CBCT-confirmed implant positioning, while enhancing the soft tissue contour through a small semilunar incision.
Ⅱ. Case Report
A 65-year-old female patient visited the clinic for implant restoration at the site of a missing mandibular left first premolar, as well as first and second molars. At the initial visit, the mandibular left first premolar region demonstrated severe soft tissue collapse, accompanied by an insufficient width of the keratinized gingiva in the first and second molar areas (Fig. 1).
The conventional approach for addressing the lack of keratinized tissue, as observed in this case, is flap surgery. The conventional crestal incision limits preservation of the buccal keratinized gingiva from the lingual gingiva and necessitates additional suturing. However, a minimally invasive alternative involved making a semilunar incision, less than 1 cm in length, slightly lingual to the mid-crest, using a #15 blade. This technique effectively addressed both the collapse of soft tissue and the insufficient width of the keratinized gingiva. Subsequently, the full-thickness soft tissue was buccally reflected using a surgical curette. A 1-mm-diameter guide pin was then inserted (Fig. 2). Following confirmation of the stability of the installed guide pin, CBCT was performed (Fig. 3). After confirming proper implant positioning along the guide pin trajectory, the implants were placed in accordance with the manufacturer’s instructions. Even if the guide pin is suboptimally positioned, the osteotomy can be guided in the corrected path using the existing guide pin, thereby reducing the need for repeated CBCT examinations. The osteotomy was performed using a hollow cutting drill to maintain the guide pin’s position. Unlike a milling (twist) drill, the hollow drill preserves its trajectory without deflection from the bone quality. Furthermore, as the guide pin remains inside the drill during osteotomy, the risk of complications such as cortical bone perforation is minimized even in narrow alveolar ridges. Following a semi-lunar incision, the soft tissue was displaced buccally, at sites with insufficient attached gingiva, and a one-stage MagiCore implant (Innobiosurg, Daejeon, South Korea) was placed. The displaced soft tissue was repositioned on the buccal side after implant placement. Moreover, no sutures were placed afterward (Fig. 4). Panoramic radiography and CBCT revealed satisfactory implant placement (Fig. 5). One week after implant placement, the intraoral examination confirmed that the soft tissue buccally displaced soft tissue remained stable and had begun healing over the implant surface (Fig. 6). One month after the implant placement, the abutments were connected to temporary prostheses. Intraoral findings confirmed expansion of the peri-implant soft tissue width and immobilization of the previously mobile soft tissue (Fig. 7). Panoramic radiography and intraoral photographs acquired 4 years and 4 months after the surgery confirmed a stable crestal bone and the absence of mobile soft tissue on the buccal side of the prostheses (Fig. 8).
This case demonstrated successful minimally invasive implant placement at a site with limited keratinized gingiva and a narrow crestal bone width. A semilunar incision allowed soft tissue repositioning without flap elevation, resulting in stable, immobile soft tissue and well-maintained crestal bone at the 4-year and 4-month follow-up. The use of a guide pin enabled precise evaluation and determination of the osteotomy direction, whereas the implant fixture with variable cuff lengths (2, 3, 4, 5 mm) allowed for accurate depth control without the need for additional bone grafting. The length of the cuff was determined by measuring the soft tissue thickness 2–2.5 mm buccally, lingually, mesially, and distally from the center of the guide pin, with the greatest measurement representing the clinical soft tissue thickness, taken as the cuff length.
Ⅲ. Discussion
Flapless implant surgery is increasingly supported in the literature for its ability to preserve the vascular supply, minimize periosteal disruption, and reduce early crestal bone resorption. Multiple studies have reported significantly less marginal bone loss in flapless procedures than in conventional flap surgery,8,9,10 along with reduced postoperative pain, swelling, and faster recovery times.11 These benefits are especially relevant for older or medically compromised patients, where minimizing surgical trauma is a priority. However, the flapless approach poses challenges, including limited visibility, risk of angulation errors, and difficulty managing soft tissue deficiencies.
The present case demonstrates that these limitations can be overcome by using a combination of simple and effective techniques. A 1-mm guide pin enabled accurate three-dimensional positioning at a site with a narrow crestal bone, while a semilunar gingival incision allowed controlled soft tissue repositioning without full flap elevation. Additionally, the use of an implant fixture with variable cuff lengths (2, 3, 4, 5 mm) eliminated the need for bone grafting and allowed precise placement depth adjustments based on soft tissue thickness. These innovations facilitate safe and accurate minimally invasive implant placement in challenging bone and soft tissue conditions. At the 4-year and 4-month follow-up, the implant site exhibited immobile keratinized soft tissue and stable crestal bone, indicating long-term biological and prosthetic success.
Ⅳ. Conclusion
This case supports the broader applicability of flapless implant surgery when combined with proper radiographic evaluation, minimal soft tissue modification, and implant selection tailored to anatomical conditions. With careful planning, these approaches may broaden the indications for flapless procedures and provide reliable alternatives to more invasive techniques in select cases.
