The present study involved 3 patients, none of whom; 1) had relevant medical or dental histories, 2) were smokers, 3) had any contraindications for periodontal surgery, or 4) had taken medications known to interfere with periodontal tissue healing.

All surgical procedures were performed by a single operator (Y.K.), and all involved extraction of a periodontally compromised tooth followed by vertical bone augmentation using a K-incision at the healed, low-level alveolar ridge. Specifically, the teeth were diagnosed as hopeless, with severe alveolar bone defects caused by chronic periodontitis. They were extracted under local anesthesia (lidocaine HCl; 2% injection [1:100,000], Huons, Seongnam, Korea), meticulous debridement of the socket was carried out, and the area was thoroughly cleaned using sterile saline (0.9% sodium chloride). After a soft tissue healing period of around 2 months, guided bone regeneration (GBR) was performed before implant placement. In the missing tooth site with a vertical bone defect (Figure 2A), a partial-split K-incision was made using a Kirkland knife to split the gingival flap into 2 equal parts (Figure 2B). The denuded cortical bone was drilled using a round bur to ensure decortication and to promote osteogenesis from the bone marrow (Figure 2C) [13]. A microscrew (Jeil Medical Corp., Seoul, Korea) was used as a tent pole to support the augmented bone height. GBR was carried out using inorganic bovine bone mineral (OCS-B^®, NIBEC, Jincheon, Korea) and a titanium-reinforced (TR), high-density polytetrafluoroethylene (Gore-Tex^®, W. L. Gore & Associates Inc., Newark, DE, USA) or collagen membrane (Bio-gide^®, Geistlich Pharma AG, Wolhusen, Switzerland) was used (Figure 2D). The soft tissue was extended for as long as it was divided in half, and the buccal vestibular depth was not changed, securing the keratinized gingiva (Figure 2E).

A 59-year-old woman presented with periodontally compromised maxillary molars (teeth #2 and #3) and severe bone resorption. The teeth were extracted (Figure 3A). The woman showed severe vertical bone loss, and microscrew-retained GBR was thus planned before implant placement (Figure 3B). To this end, a partial-split K-incision was performed, and inorganic bovine bone mineral and a TR membrane were applied. The flap was then sutured (Figure 3C and D). The elongated soft tissue portion was extended by approximately 4–5 mm (Figure 3D). After 4 months, an External Hex RESTORE^® RBM implant (4.0 mm in diameter×10.0 mm in length MAUSA, Keystone Dental, Inc., Burlington, MA, USA) was successfully placed in the proper position without any sinus bone graft, and the denuded connective tissue was fully covered using keratinized gingiva (Figure 3E). The radiograph in Figure 3F shows a moderate length of the implant prosthesis, and the alveolar bone around the dental implant was well maintained during 5 years of periodic follow-up.

The maxillary molar (tooth #3) of a 47-year-old man was scheduled for extraction after a diagnosis of chronic periodontitis. The clinical and radiographic examinations showed severe vertical bone loss (Figure 4A), so a microscrew-retained GBR was planned before the implant placement (Figure 4B). After 4 months of GBR, sufficient bone height and width were achieved to place the implant fixture (Figure 4C). A dental implant (RESTORE^® RBM, 4.0 mm in diameter×10.0 mm in length) was successfully placed in the proper position (Figure 4D). During a 3-year follow-up after installation of the implant prosthesis, a stable augmented bone condition was observed (Figure 4E); around the implant prosthesis, there was proper keratinized gingiva and a healthy periodontal region (Figure 4F).

A 63-year-old man was referred from a local clinic because implant placement was impossible at the site of a previously extracted tooth (#14) without a sinus bone graft. A narrow, saucer-like alveolar ridge was observed upon an oral examination (Figure 5A), and the radiograph from the local clinic showed deficient bone healing and a sinus septum at the center of the site of the missing tooth (Figure 5B). We performed microscrew-retained GBR (Figure 5C-E) with a K-incision using inorganic bovine bone mineral and a TR membrane. We could see the extended soft tissue in the palatal site (Figure 5E). After 4 months, the surgical site was well healed and showed sufficient recovery of alveolar bone width and height, so the microscrews were removed (Figure 5F). The augmented bone was well maintained (Figure 5G), and the implant fixture (RESTORE^® RBM, 4.0 mm in diameter×10.0 mm in length) was successfully placed in the correct position using a sinus septum without any sinus bone graft (Figure 5H). After installation of the implant prosthesis, the augmented bone was well maintained during 2 years of periodic follow-up (Figure 5I).