Autogenous Block Bone Grafting

The use of autogenous block bone grafts for three‐dimensional (3D) defect reconstruction of deficient alveolar bone, while considered the gold standard, has significant drawbacks. Morbidity associated with pain and wound healing complications at the donor site have been observed. Another drawback is that the incidence of complications associated with block bone grafting (38.1%) is significantly higher than that of GBR (16.80%). [9] These surgical techniques also have the disadvantage of prolonging the patient’s edentulous period and increasing the need for surgical revisits because simultaneous implant placement is not possible. In addition, autogenous intraoral block grafts show 17.4% resorption at 4–6 months post surgery, while extraoral bone grafts (e.g. iliac crest) exhibit average resorption of 42% in anterior maxilla and 59% in the posterior mandible after 1 year. Thus, due to rapid resorption, such approaches to 3D osseous reconstruction are not advisable in esthetically demanding premaxillary regions. [10, 11]

Intraoral Distraction Osteogenesis

When vertical bone augmentation of 5 mm or more is needed, intraoral distraction osteogenesis may be preferred over block bone grafting. Distraction osteogenesis involves gradual separation of osteotomized bone segments to stimulate new bone formation and can achieve augmentation of 6–10 mm [12, 13]. Unlike block bone grafting, distraction osteogenesis eliminates the need for bone harvesting, reducing morbidity, while also preserving vitality in the distraction area and promoting accompanying soft tissue gain. Although simpler and more predictable than block bone grafting, distraction osteogenesis is associated with a higher rate of complications, requires strict patient compliance for daily rotation of the distraction screw and frequent follow‐ups. Complications such as infection, malpositioning of the distractor, painful tension, pin‐related scarring, and bleeding at the osteotomy site can occur. Additionally, relapse is common, necessitating a 20% overcorrection.

Sandwich Augmentation with Interpositional Bone Grafting

Sandwich augmentation with interpositional bone grafting presents an effective approach for addressing extensive vertical defects. It involves freeing a local pedicle bone segment through osteotomy cuts and relocating it crestally, resulting in a vertical bone height increase of 6–10 mm. Importantly, maintaining the vascular supply to the segmented bone helps prevent bone resorption, distinguishing it from free block bone grafting. [14, 15] In comparison with distraction osteogenesis, this sandwich augmentation technique requires less patient compliance and is more cost effective. However, patients commonly complain of the necessary prolonged healing period without teeth, as it is not possible to place implants simultaneously, nor is simultaneous horizontal alveolar ridge augmentation possible.

Split Bone Block Technique

The split bone block technique involves harvesting an autogenous ramus block from the mandibular retromolar area, splitting it longitudinally with a microsaw, placing the divided thinner blocks in the defect area, stabilizing them with long miniscrews and filling the enclosed defect with particulate cancellous autogenous bone. Over a 10‐year period, the mean vertical bone gain achieved can remain stable at 6.72 ± 2.26 mm in posterior mandible [7]. The technique does result in predictable in 3D bone reconstruction in both posterior mandible and maxilla. However, drawbacks include high donor morbidity, surgical complexity, increased surgical time, and the need for multiple surgeries again because simultaneous implant placement again is not possible. [16, 17]

Guided Bone Regeneration (GBR)

GBR or localized augmentation with particulate bone substitute materials covered by resorbable commonly collagen barriers is frequently used to achieve bone augmentation at sites elected to receive immediate dental implants. However, the achievable regeneration falls short in comparison with other surgical techniques, with a mean of only 3.7 mm for vertical and horizontal augmentations [18]. In addition, GBR augmented ridges often undergo considerable resorption (13–37%) by 6 months [19–21]. Therefore, over correction with biomaterials is essential, especially when placing implants simultaneously [22]. GBR is a relatively simple surgical procedure, but as stated, the limited results achievable make it less suitable than other approaches in augmenting significant defects in the anterior esthetic region. GBR using non‐resorbable PTFE (polytetrafluoroethylene) membranes or titanium meshes rather than resorbable barrier membranes can achieve greater and more predictable bone gain, due to superior space‐making capacity. However, adequate membrane/mesh stabilization using tacks or microscrews can be technically difficult and time consuming, and can make the outcomes susceptible to early membrane and graft exposure, causing poor bone regeneration.

Soft Tissue Matrix Expansion Technique Using A Tenting Pole Technique

The soft tissue matrix expansion technique using tent pole technique overcomes the limitation of conventional GBR in vertical ridge augmentation because tenting of the periosteum and soft tissue matrix with titanium tenting devices will minimize unwanted migration of added particulate bone grafts by maintaining an undisturbed space for new bone formation [23, 24]. The technique also can achieve more favorable horizontal ridge augmentation than PTFE and tunnelling techniques [25]. GBR using tenting can achieve gains of 9.7 mm in vertical ridge height and an increased mean bone content of 43% [26, 27]. The technique is technically simple compared with other complex approaches and yields predictable reconstruction of large vertical defects without the need for autogenous bone in the graft material [28, 29]. Simultaneous implant placement is possible, but the healing needs to be submerged and the period of edentulism is prolonged. Additionally, since multiple screws need to be inserted, the surgery time can be prolonged and the number of surgical interventions is increased.

Marx et al. [21] introduced the concept of soft tissue matrix expansion (tent pole) for reconstruction of severely resorbed mandibles using a tenting device for implant placement and transplantation of crushed iliac bone collected under general anesthesia and provision of a fixed prosthesis after 3 months site healing. The average bone gain achieved was 10.2 mm, together with expansion of the soft tissue volume. Other reports were limited to reconstruction of severely resorbed fully edentulous mandibles [22,30–32]. However, again, the augmented bone does suffer resorption over time making overgrafting necessary [33, 34].

The soft tissue matrix expansion technique (STMET) with simultaneous dental implant placement uses vertical tenting healing abutments to prevent dislocation and compression of added biomaterials [34, 35]. It offers reliable and long‐lasting reconstruction of severely resorbed, partially edentulous mandibles and maxillae, while minimizing complications commonly associated with alternative methods. A significant advantage for patients is the reduced number of surgeries needed. Unlike conventional GBR techniques, STMET is indicated for reconstruction of large 3D defects at the time of implant placement, and the newly regenerated bone remains stable even after enduring extended functional loading.

The Vertical Tenting Pole Abutment

The SANTA® (Biotem Implant Co., Busan, Korea) device is a tenting pole healing abutment that can be added to implants to aid in horizontal and vertical ridge augmentation with GBR. It is positioned on the implant platform facilitating overgrafting of implants with biomaterials and prevents graft particle displacement and compression by eliminating pressure from periosteum and overlying mucosa on the bone graft material. Additionally, the SANTA abutment allows a greater volume of bone graft material to be placed, including over the implant platforms, thanks to its narrower neck. It is produced with cover heads of 5 mm or 6 mm width and two cuff heights: 1 mm (SANTA‐1) and 2 mm (SANTA‐2) (Figure 5.4.1). SANTA‐1 is recommended for both vertical horizontal bone augmentation, while SANTA‐2 is suitable for vertical and three‐dimensional ridge augmentation. When using SANTA‐1, the implant should be positioned 1 mm deeper than the lingual crest, and the implant platform situated 2 mm sub‐crestal to the height of the adjacent proximal bone (Figure 5.4.2).

Description of the Sohn Bone Builder Tenting Pole Approach

The Sohn Bone Builder (SBB; Biotem Implant Co., Busan, Korea) is a vertical tenting pole screw featuring a wide head of either a round or rectangular shape. The round SBB comes in head diameters of 6 or 8 mm and is typically positioned in pontic site defects between implants. Additionally, it is used to stabilize bone graft materials in regions with severe bone defects equivalent to the size of one or two teeth where simultaneous implant placement is not possible. A round SBB is also indicated for the horizontal reconstruction of pontic sites (Figure 5.4.3).

The rectangular SBB comes in cover head lengths of 12 mm or 15 mm. It is recommended for reconstruction of severe alveolar bone defects where simultaneous implant placement is not feasible. A single rectangular SBB is sufficient for achieving favorable bone reconstruction in areas where three or four teeth are missing. It features a self‐tapping macro screw of 1.2 mm diameter. Compared with surgical techniques using multiple tent pole screws for bone reconstruction, using a single rectangular SBB results in significant time saving during surgery. Furthermore, after covering the bone graft with resorbable barrier membranes, there is no need to secure the membranes with tacks as the bone graft remains well protected (Figure 5.4.4).

Using Vertical Tenting Pole Healing Abutments in a Maxillary Anterior Site

Case One

A 69‐year‐old woman presented with severe mobility of her maxillary anterior bridge and adjacent maxillary lateral incisor. Marked gingival recession and alveolar bone loss were noted. There were also periapical radiolucencies at the right lateral and left central and lateral incisors (Figure 5.4.5).

The surgical procedure was performed under local anesthesia (2% lidocaine with epinephrine 1: 100 000) after intravenous injection of lomoxef. After raising a full‐thickness buccal flap, the bridge and lateral incisor were removed and periapical pathoses carefully debrided using a curettage insert connected to a piezoelectric device. The extracted teeth then were immediately prepared as an autogenous decalcified osteoinductive particulate graft material using a vacuum ultrasonic machine. This “tooth–bone” graft then was prepared as “sticky bone” by combining it with autologous fibrin glue prepared from a sample of the patient’s venous blood, as described previously [36]. Periosteal‐releasing incisions were made using a new #15c blade to confirm that the buccal mucosa could be easily overlapped towards the palatal by more than 10 mm, ensuring that tension‐free closure of the site could be predicted after bone grafting. Undersized osteotomies were prepared at the right and left lateral incisor sockets using a drill 1 mm narrower in diameter than the planned implant to ensure adequate initial implant stability. Implants of 4.0 mm diameter × 13 mm length were placed immediately at both sites with stability measuring greater than 20 Ncm. The implant platforms were placed 2 mm subcrestal to the adjacent proximal bone heights.

Vertical tenting pole abutments with 2 mm cuff heights (SANTA‐2) were added to both implants to assist in minimizing the impact of soft tissue healing and contraction on added bone graft material. A 2‐mm‐wide × 13 mm‐long mini‐implant was placed in the center of the edentulous ridge (Figure 5.4.5g) to provide the patient with retention of a temporary fixed prosthesis. The sticky osteoinductive tooth–bone graft was applied to the defects at the right lateral incisor while a composite of sticky bovine bone and allograft was needed to graft the left lateral incisor site (Figure 5.4.5h). Four concentrated growth factor membranes (which are equivalent to platelet‐rich fibrin membranes) [37, 38, 39] (Figure 5.4.5i) were used to cover the grafts in an attempt to accelerate wound healing. After perforating the flap tissue using a point drill at the site where the head of the mini‐implant was positioned, the flap was sutured and the temporary prosthesis connected to the Dentis temporary implant (Figure 5.4.5j).

Healing was uneventful, with uncovering of the implants performed after 4 months. A plain radiograph and cone beam computed tomography revealed successful ridge augmentation over the implant platforms. The mini‐implant was removed with a ratchet and adapter. After making a small incision in the mucosa where the SANTAs were located, they were removed, and scan bodies positioned for the impression. A new temporary prosthesis was installed the next day. After waiting 2 months for the healing of the soft tissues around the implants, the final prosthesis was installed (Figure 5.4.5k–o).

Case Two

A 50‐year‐old woman presented with mobility of her maxillary central and lateral incisors and right canine, as well as loss of the first and second premolars and first and second molars. The maxillary left second premolar and first and second molars also were absent. Her maxillary right central was extruded (Figure 5.4.6a). The patient had no significant medical history. A preoperative radiograph (Figure 5.4.6b) highlighted severe horizontal and vertical alveolar defects at the right central and lateral incisors and canine. CBCT showed an oroantral communication with the right pneumatized maxillary sinus (Figure 5.4.6c). Cross‐sectional CBCT revealed major bone deficiencies in the edentulous area (Figure 5.4.6d).

The three hopeless anterior teeth were extracted, and the sites left after meticulous degranulation for a 6‐week healing period. The implant surgical procedure was performed under local anesthesia after intravenous administration of preoperative Flomoxef. A full‐thickness buccal flap was reflected, and periosteal‐releasing incisions made to ensure that the buccal flap could later be advanced by more than 10 mm to ensure tension‐free primary wound closure after bone grafting. As anticipated, severe bone loss was present anteriorly (Figure 6.5.7a), while a 15 mm oroantral opening was seen posteriorly (Figure 5.4.7b). For accurate placement of the anterior implants, a BonePen^® guide kit (Acrodent Co., Kimhae, Republic of Korea) was employed (Figure 5.4.7c) following the manufacturer’s instructions [40]. To facilitate elevation of the maxillary sinus floor, it was decided that a bony window (residual oblique bone width, ROBW) was needed to enlarge the existing opening into the sinus. Accordingly, a saw insert tip with a thin blade (Figure 5.4.7d) connected to a piezoelectric device was used under copious saline irrigation to create the ROBW. The anterior vertical osteotomy cut was made 2 mm distal to the anterior vertical wall of the sinus, while the inferior cut was located 2 mm above the sinus floor. The height of the vertical cut was approximately 10 mm. The bony window was carefully detached to expose the sinus membrane (Figure 5.4.7e), and elevation of the sinus membrane continued (Figure 5.4.7f) until the medial wall of the maxillary sinus was exposed. Exposing this medial wall was crucial to ensure an adequate blood supply for successful sinus grafting. This further elevation of the sinus membrane allowed it to be overlapped to manage the membrane perforation.

All osteotomies were under‐prepared using a drill bit that was 1 mm narrower in diameter that the actual implant placed in each site. Implants of 4‐mm diameter by 13 mm were placed at the central incisor and canine sites. Initial stability was recorded as greater than 40 Ncm (Figure 5.4.8a). A 4.5‐mm diameter by 11.5‐mm long implant was used to replace the first premolar and a 5‐mm diameter by 10‐mm long implant placed at each of the second premolar and first molar sites. The initial stability of all posterior implants showed more than 30 Ncm. SANTA‐2 healing abutments were placed on the two anterior implants to promote 3D ridge augmentation, while SANTA‐1 healing abutments were used posteriorly to help with horizontal augmentation. A 6‐mm diameter round SBB 12 mm in length was installed at the edentulous lateral incisor spot using a 1‐mm diameter pilot drill run at 50 rpm. The vertical height of the cover head of this SBB corresponded with those of the cover heads of the SANTA‐2 abutments (Figure 5.4.8b). A similar sized SBB was placed on the buccal ridge around the second premolar implant to promote horizontal augmentation (Figure 5.4.8c), but also to prevent the displacement of bone graft into the sinus. The large sinus membrane perforation was sealed with a fast‐resorbing gelatin sheet, and the ROBW repositioned in the lateral widow of the sinus. No bone grafting was used in the sinus. Sticky osteoinductive tooth–bone graft material prepared from the patient’s extracted anterior teeth was grafted around the anterior implants to promote 3D ridge regeneration, while a mixture of sticky bovine bone and human allograft was used over the posterior implants (Figure 5.4.8d). Afterwards, a resorbable collagen membrane was placed over the graft materials without stabilization with tacks or membrane stabilizing sutures (Figure 5.4.8e). Tension‐free primary soft tissue closure was achieved (Figure 5.4.8f).

Surgeons should ensure a 2‐mm overlap of the buccal flap over the palatal flap to avoid premature flap opening. Postoperative periapical radiographs (Figure 5.4.9a) confirmed effective grafting over the SANTAs and SBBs, while CBCT indicated sinus mucosal elevation of over 10 mm (Figure 5.4.9b), and bone graft material surrounding the implanted devices (Figure 5.4.9c,d).

After 5 months of healing, radiographs (Figure 5.4.10a) and the panoramic CBCT (Figures 5.4.10b–d and Figure 5.4.11) revealed favorable 3D ridge augmentation and some limited bone regeneration in the right sinus with closure of the oroantral defect.

Uncovering was performed and a provisional restoration delivered 2 weeks later. After a further 2 weeks with loading of the provisional restoration, a sutureless free gingival graft [41] was performed to establish attached keratinized gingiva around the buccal aspects of the implant restoration, and the definitive zirconia restoration delivered 2 months later.

Vertical Bone Regeneration Around Immediate Implants Using Demineralized Tooth “Rings”

Demineralized autogenous tooth/bone graft material, as already shown, can be prepared as an osteoinductive particulate material for bone regeneration with immediate implants placed into damaged extraction sockets. Patient’s extracted teeth also can be used to create “ring” block grafts suitable for use as bioactive solid space makers to aid in vertical bone regeneration around immediate dental implants. Dentin is known to have similar inorganic and organic components to alveolar bone [24]. Demineralization of dentin blocks increases the number of exposed dentinal tubules and enlarges them to promote rapid release of osteoinductive proteins (Figure 5.4.12) [42–44], leading to faster rates and higher volumes of new bone than seen with non‐demineralized dentin block grafts [45, 46].

Teeth extracted from a patient can be immediately prepared as demineralized graft materials [47]. To do this, all soft tissues attached to the extracted tooth, decay, calculus, pulpal tissue, and restorations are removed with rotary instruments. The root is then separated from the crown and the root apex sectioned and flattened using a disk. A 5–6 mm segment of the root length then is created as a tooth–bone ring‐shaped block. Meanwhile, the crown and root apex segments are ground into a particulate material. To facilitate the insertion of the implant into its “ring”, the root canal of the ring is prepared using an implant drill matching the diameter of the implant to be placed. Microperforations (0.5 mm diameter) are made in the “ring” at 5–6 mm intervals using a small round bur and high‐speed handpiece with saline irrigation. Thereafter, the prepared ring is sterilized in a peracetic acid ethanol solution and then demineralized in a solution of 0.6 N hydrochloride for 60 minutes under vacuum compression and ultrasonic vibration in a VacuSonic (CosmoBioMedicare Co., Seoul, Korea) machine. The demineralized blocks then are washed thoroughly in phosphate‐buffered saline (PBS), and finally in distilled water all within the VacuSonic device (Figures 5.4.13 and 5.4.14).