A Combination of Buccal Plate Preservation and Dual Zone Therapeutic Technique in Immediate Implants: A One-Year Follow-Up

Interest in immediate replacement of teeth has increased in recent years by patients and clinicians alike. Thanks to improvement in techniques and materials, immediate implant placement and loading has become more predictable.^1–4  Recent studies have shown that immediate implant placement accompanied with bone grafting reduces the horizontal resorption of the facial bone caused by tooth extraction.^5–8  To reduce the horizontal bone resorption and prevent recession, 2 techniques have been proposed: the buccal plate preservation technique,^9,10  and the dual-zone therapeutic concept.¹¹  In the following case we will present a technique utilizing both approaches.

A 39-year-old male presented to the dental clinic with a complaint: “I want to replace my fractured tooth.” Past medical history revealed no contraindication to dental treatment. Oral examination revealed acceptable oral hygiene, few restored teeth, and fractured upper left second premolar (#13) (Figures 1 and 2). Periodontal examination revealed thick periodontal biotype, normal gingival scallop, and probing depth ranging from 1–3 mm. Radiographic examination showed previous root canal treatment for tooth #13 and normal proximal bone levels (Figure 3). A treatment plan was formulated and discussed with the patient; it was decided to extract tooth #13 and replace it immediately with an endosseous implant, bone graft, and an immediate provisional crown.

Under local anesthesia (Lidocaine 2%, Epinephrine 1:100 000) with buccal and palatal infiltration, tooth #13 was atraumatically extracted in a flapless technique with a periotome and forceps (Figure 4). The socket was curetted and irrigated with saline, and the buccal wall was evaluated and deemed intact. The faciopalatal dimension of the socket measured 8 mm (Figure 5). Osteotomy was initiated according to the manufacturer's instructions in a palatal direction and a standard diameter implant (Straumann Bone Level Implant RC Ø 4.1 mm × 12 mm) was immediately inserted, leaving at least 3 mm of space from the buccal wall and seated 3 mm apical to the free gingival margin (Figure 6). The primary stability of the implant was 40Ncm, which permitted immediate provisionalization. A screw-retained provisional crown was fabricated before the grafting procedure to avoid any contamination of the bone graft. With a periosteal elevator, a small pouch was created facial to the buccal bone in a full thickness manner in the middle area of the socket, slowly extending beyond the mucogingival line in a mesiodistal direction (Figure 7). Then xenograft bone granules (0.25–1 mm, Geistlich Bio-Oss, Princeton, NJ) were hydrated with saline and placed in the pouch until adequately filled, then the xenograft was also added in the gap between the implant and buccal bone until the gap was filled to the soft tissue level (Figure 8). The provisional crown was screwed to the implant, and the access was closed with cotton pellet and composite, occlusion was checked, and there was no contact in centric and eccentric movements (Figure 9). Postimplant radiograph showed proper implant placement and proper abutment adaptation (Figure 10). Postoperative instructions were given to the patient, which included adhering to a soft diet, avoiding hot or spicy foods, and avoiding rinsing the mouth vigorously. Medication prescribed Amoxicillin 500 mg every 8 hours for 5 days, Ibuprofen 400 mg every 8 hours for 5 days and 0.12% chlorhexidine gluconate oral rinse twice a day for 2 weeks.

After 4 months the prosthetic phase was initiated. The provisional crown was removed and an impression post for closed tray was inserted; flowable composite was immediately injected around the post to capture the well-developed soft tissue architecture created by the provisional crown to transform it to the final impression. With a custom tray in a closed-tray technique, a polyether final impression was taken. The impression was poured and the master models were mounted on a semi-adjustable articulator. A custom abutment was selected, and a porcelain fused to metal crown was fabricated. At the time of delivery, the custom titanium abutment was screwed to the implant, torqued to 35 Ncm, and a sterile cotton pellet was used to close the access. A copy abutment was fabricated by using vinyl polysiloxane impression material applied to the fitting surface and the outer surface of the crown, which would be used to remove excess cement (Figures 11 and 12). Zinc oxide eugenol cement was mixed and brushed on the fitting surface of the crown and then tried on the copy abutment to remove excess cement. The crown was cemented on the final abutment, and all excess cement was removed. One-year follow-up showed stable soft tissue architecture with optimal esthetics (Figures 13 and 14). Radiographs showed stable bone levels and proper implant position (Figure 15).

When clinicians face a situation regarding whether or not to extract a tooth, the decision is not easy to make. But when indicated, extraction and immediate implant placement is a highly predictable procedure when proper guidelines are followed. Case selection is the most important criteria. Kois mentioned the 5 diagnostic keys for predictable peri-implant esthetics: relative tooth position, form of the periodontium, biotype of the periodontium, tooth shape, and position of the osseous crest.¹²  Further, the type of socket present after extraction is important; type I is the most favorable for immediate implant placement due to proper levels of bone and soft tissue in relation to the cementoenamel junction.¹³  When atraumatic extraction is performed with a flapless approach, the gingival architecture and blood supply to the buccal plate is preserved; therefore, every effort should be made to maintain an intact buccal plate. Using a surgical guide can be beneficial even in single tooth replacement, not only does it provide prosthetically guided implant position but also prevents elliptical osteotomy preparation.¹⁴  Rosa et al mentioned a technique for proper implant size selection, in which the implant size is selected with a goal of leaving a 3 mm space from the implant surface to the outer buccal wall. This 3-mm gap provides better placement and compaction of grafting material.¹⁵  Many techniques have been proposed to decrease the amount of hard and soft tissue collapse after extraction and immediate implant placement, with different ranges of success.^16–24 

The buccal plate preservation technique showed that alveolar ridge and soft tissue contours can be maintained by overcompensating with xenograft material packed in a pouch that is facial to the buccal plate.¹⁰  In an animal study, it was histologically proven that placement of Bio-Oss Collagen in the void between an implant and the buccal-approximal bone walls of a fresh extraction socket modified the process of hard tissue healing by providing additional amounts of hard tissue at the entrance of the previous socket, improved the level of marginal bone-to-implant contact, and prevented soft tissue recession.²⁵  The dual zone therapeutic technique explains that when the 2 regions—the tissue zone and bone zone—are grafted by different types of bone replacements, substitutes, and/or materials, it helps serve as a scaffold to maintain hard and soft tissue volume as well as blood clot for initial healing.¹¹  In addition, immediate provisionalization when primary implant stability is favorable (> 45 Ncm) serves as a prosthetic seal to contain the bone graft material.²⁶  The research outcomes of the dual zone therapeutic technique showed that grafting the bone and tissue minimized ridge collapse to −0.1 mm and increased peri-implant soft tissue thickness by +0.5–1.0 mm.²⁷ 

In conclusion, utilizing all the aforementioned techniques was shown to maintain the bone and soft tissue contour in the case presented. It is important to note that these procedures were performed when there was an intact buccal plate after extraction. However, several studies have suggested that immediate implant placement and provisionalization should not be performed in cases of buccal bone defects extending to the buccal crest. Such situations require a staged procedure with hard tissue grafting before implant placement and connection of a restoration.^28–30  Further long-term studies are needed to confirm the efficacy of these procedures.