Idealizing Bone for Implant Placement in the Anterior Maxilla

There is an average of 3.8 mm of horizontal bone loss 6 months after extraction.² In the anterior region of the maxilla, there is approximately 35% horizontal loss in the most coronal aspect of the socket during this period, with approximately one third of this loss occurring in the palatal/buccal direction.³ Therefore, it is reasonable to infer that if there is bidirectional bone loss in the horizontal direction, a bidirectional bone reconstruction approach should be used if possible.

The traditional tenting, block grafting, titanium mesh, and split crest techniques tend to promote an increase in bone in one direction only (ie, on the buccal aspect),⁴ especially considering the difficulty associated with placing stabilizing screws or pins on the lingual or palatal side of the ridge.⁵ Therefore, to date, horizontal bone augmentation techniques have primarily focused on the buccal aspect despite the usual concomitant loss on the palatal/lingual aspect. Unfortunately, when increased buccal dimensions are achieved with no palatal/lingual augmentation, it can result in implants being positioned more buccally, which can lead to prosthetic and esthetic problems.⁵

To address traditional bone grafting techniques' lack of ability to augment the ridge on both sides of the defect and provide a more predictable prognosis with guided bone regeneration procedures, a new surgical approach called the "barbell technique" was developed. This technique involves the use of a titanium screw with a hexagonal tip at both ends, which is inserted through the ridge in the recipient bone bed. This screw then capped at both ends with polyetheretherketone (PEEK) caps to prevent compression and collapse of the soft-tissue flap onto the grafted site and biomaterials during healing (Figure 1 through Figure 6).

The Barbell Technique represents an important advancement over the traditional tent technique because it permits bidirectional horizontal appositional bone augmentation if the clinical case requires it. It should be noted that the tent technique involves the use of screws that were not developed specifically for the purpose of tenting soft tissue but instead were developed to fixate bone blocks, whereas the barbell technique involves the use of smooth and curved PEEK caps that contact the soft tissue flap and suppress tissue compression. In addition to suppressing tissue compression, the PEEK caps enhance the viability, proliferation, and adhesion of osteoblasts and gingival fibroblasts even better than titanium.⁶ These benefits contribute to achieving the desired tissue integration of both the hard and soft tissues. PEEK also has a bactericidal effect,⁷ which can be useful, especially in cases that involve a greater risk of soft-tissue dehiscence and exposure of the graft biomaterial during the healing period.

Depending on the clinical situation, the barbell technique can be performed with screws that are 6 mm, 8 mm, 10 mm, or 12 mm in length. If unidirectional augmentation is needed, a shorter screw may be used along with a single PEEK cap. The technique also requires drills for decortication and preparing the bed to receive the screw in high and low/medium density bone, a contra-angle wrench, a manual screw carrier, a PEEK cap capturer, a rescue drill (ie, trephine), and tweezers for applying the PEEK caps. The following clinical case report illustrates the use of the barbell technique to achieve bidirectional horizontal bone augmentation on one side of the anterior maxilla and unidirectional horizontal augmentation on the other side.

A 37-year-old female patient presented to the practice missing teeth Nos. 8 through 10 (Figure 7). A preoperative cone-beam computed tomography (CBCT) scan was acquired, which showed significant horizontal bone loss (Figure 8). The barbell technique (Barbell Surgical Kit, Geistlich Brasil) was performed to achieve bidirectional bone augmentation on the left side of the site and unidirectional bone augmentation in the right side (Figure 9 through Figure 12).

In this case, an osseoconductive bovine bone substitute biomaterial was used. The choice to avoid autogenous bone harvest, and consequently a mix of xenograft and autograft, was based on the presence of cancellous bone between the cortical buccal and palatal bone plates, which could be seen in the preoperative CBCT scan. In making this decision, a classification system of horizontal alveolar changes (HAC), which was developed by some of the authors of this article, was used.⁸ This classification system enables clinicians to categorize ridge defects and select the most appropriate bone grafting approach for each situation.⁸ In this case, a resorbable collagen membrane was used with no need for any other device to provide mechanical resistance and structure to maintain the particulate graft in position and resist the pressure exerted by the overlying soft tissues. This was only possible due to the inner presence of the barbell technique components, which provided the structuring necessary to maintain space for new bone formation and to accomplish bone regeneration.

After a 9-month healing period, the site was reopened to install the implants (Figure 13). The PEEK caps and titanium screws were removed, the implant osteotomies were performed, and the implants were placed (Figure 14 through Figure 16). Because the bone augmentation was accomplished bidirectionally, the implants could be placed in ideal positions to accommodate a final prosthesis with excellent esthetics (Figure 17 and Figure 18).

The barbell technique is a versatile technique that enables both unidirectional and bidirectional horizontal bone augmentation. Prospective clinical research published in the literature by Pelegrine and colleagues has demonstrated the predictability of the technique for this purpose.^4,5 Furthermore, research published by Nunes and colleagues has demonstrated the predictability of the barbell technique for vertical bone augmentation.⁹ The versatility and effectiveness of this technique permits it to be used for all types of appositional bone augmentation procedures.

André Antonio Pelegrine, DDS, PhD
Professor and Head
Department of Implant Dentistry

São Leopoldo Mandic
Campinas, São Paulo, Brazil

Luís Guilherme Scavone de Macedo, DDS, PhD
Professor
Department of Implant Dentistry

São Leopoldo Mandic
Campinas, São Paulo, Brazil

Marcelo de Sá Zamperlini, DDS, MS
ProfessorInstituto de Cuidados Odontológicos
Campinas, São Paulo, Brazil

Peter Karyen Moy, DMD
Professor
Department of Oral and Maxillofacial Surgery
University of California
Los Angeles, California