Bone Spreading Technique

Figure 1. Occlusal preoperative view. Figure 2. Buccal aspect is too narrow to consider implant placement. Figure 3. Mucoperiosteum flap was elevated. It showed fenestration on buccal aspect and was inadequate for implant placement. Figure 4. Surgical procedure: initial spreader (2.2 mm in diameter). Figure 5. Final spreader (3.0 mm in diameter). Figure 6. Occlusal view with implant inserted. Figure 7. Buccal aspect with implant inserted. Figure 8. The flaps are sutured into their original positions.

INTRODUCTION
The advanced resorption of alveolar bone of the maxillary region is often a problem area for implant placement. Bone volume must be available in the position needed to placement fixture position. The limitations of drilling into an atrophic ridge in the maxilla constitute a challenging clinical situation.
     One of the major problems encountered after the tooth extraction is the hard- and soft-tissue loss. Reduction of the buccal alveolar bone caused by bone resorption in a partially edentulous maxilla is a frequent problem. Implants need an adequate volume of bone to stabilize the fixture. In partially edentulous patients often maxilla atrophy requires to be augmented. Numerous augmentation techniques^1-7 have been reported in the dental literature to facilitate implant placement in the atrophic ridge using blocks grafts, which require several steps before prosthetic restoration. In an effort to shorten the length of treatment, avoid an additional surgical appointment, and to decrease patient morbidity, a technique that would both lessen the trauma to patient and conserve the maximum amount of alveolar bone at precise site of anticipated implant placement would offer clinical benefits.
     Spreaders of increasing diameters are gently introduced sequentially to expand the implant site. With each insertion of a larger diameter spreader, the bone is pushed laterally. The implant should be slightly larger in diameter than the site created by the largest diameter spreader. Bone spreading technique (BST) is described for placing implants with sufficient bone height but insufficient bone width. BST is an alternative to Summers’ Osteotome Technique^8,9 both for clinical use as well as the armamentarium. The BST is a method of placing implants into bone with no drilling.
     The objective of this article is to emphasize the surgical advantages that the BST has shown when compared to Summers’ Osteotome Technique.

SURGICAL TECHNIQUE
Patients are instructed to take 2.0 g of amoxicillin (or 600 mg clindamycin) one to 2 hours prior to surgery. After administering approximately 2 carpules of 2% mepivacaine, the maxillary alveolar ridge is exposed via a crestal incision and elevation of the mucoperiosteoum. To secure a proper alignment of the implants, a surgical template is used.
     The Split-Control Bone Spreading & Condensing System (Meisinger) is used, as described next. The osteotomy is started by using the pilot burs in 1.0 mm diameter followed by the 1.8 mm diameter bur under copious irrigation with sterile saline. The pilot drill is used to penetrate to the desired height. The expansion drill in 2.3 mm diameter produces a subdimensional bone cavity. There is a successive deployment of a series of smaller threadformers in a progressive way (first 2.2 mm; then, 2.4 mm, 2.6 mm, 2.8 mm; and 3.0 mm). Care is taken to proceed as slowly as possible. With the help of the appropriate carrier and, if necessary, with the help of the driver, the threadformer must be screwed in cautiously. After each half turn, a 30-second waiting time is used before turning another half turn. By widening the implant cavity in this manner, it is now possible to place the suitable Cone Morse implant (Conexão Sistemas de Prótese). Furthermore, the clearly inreased bone rigidity achieved by bone condensation results in optimized primary stability. Finally, the flaps are sutured in their original positions.
     Patients are given home care instructions and told not to rinse their mouth vigorously. Use of 0.2% chlorhexidine gluconate mouthwash twice daily is also prescribed. The sutures are usually removed at one week postoperatively.

CASE REPORT
A 47-year-old man presented for replacement of a missing canine in the maxilla. The canine had been extracted 8 years ago. A clinical exam revealed significant buccal bone loss in the canine maxilla, although adequate ridge height was present for implant placement (Figures 1 and 2). The patient requested that we avoid any bone grafting procedure. With the use of a periapical radiograph, it was decided to place a 15 mm x 3.75 mm tapered-screw implant.
     The alveolar ridge exposure was achieved through a crestal ridge incision slightly toward the palate. The mucoperiosteum was elevated on the buccal side to expose the height of the alveolar bone, and showed further bone concavity and fenestration (Figure 3). The following BST sequence was used: a 1.8-mm diameter pilot drill was used to produce a sub-dimensional bone cavity. The pilot drill penetrated to the desired height. Following the osteotomy, widening began with the use of the primary 2.2 mm diameter spreader (Figure 4). After placing the thinnest spreader, the following spreaders in ascending order were used without drilling (Figure 5). The successive deployment of a series of spreaders with increasing diameters led to bone spreading and horizontal condensing. The final lateral expansion was prepared to receive a 3.75-mm diameter tapered screw implant (Conexão Sistemas de Prótese) (Figures 6 and 7). As can be seen, an increase was achieved in bone dimension. Primary stability was achieved by torquing the implant to 35 Ncm. The flap was then approximated and sutured (Figure 8).

DISCUSSION
The ultimate objective of implant treatment is to provide support for the replacement of missing teeth. As with any treatment, presurgical planning is vital in achieving a successful outcome.
     The author has employed the BST in the maxilla for the last 3 years with consistently outstanding results. The BST involves horizontal augmentation with minimal trauma for simultaneous implant placement and is an alternative Summers’ Osteotome Technique. BST uses a successive series of threadformers in progressive way, while the Summers’ technique uses progressive osteotomes. Both techniques have been described as indicated for implant placement in ridges with narrow dimensions.⁹ The crest dilation technique is desirable because it is a substantially less invasive method; the buccal wall expands after the medular bone is compressed against the cortical bone. The lateral dilation and compaction of medular bone also improve primary stability.
     The edentulous ridge expansion (ERE) technique was developed by Scipioni, et al^10-11 to slowly dislocate the buccal plate in a facial direction. An aspect of ERE technique is the partial thickness flap, which maintains the integrity of the periosteum. Elian, et al¹² have used the split ridge expansion technique in fully edentulous maxilla. The BST is an immediate bone dilation and implant placement. This is preferred over the ERE 2-stage approach. The BST is essentially unlike both the ERE and Summers’ Osteotome Technique in design and technique.
     The BST utilizes a “screw type” design smoothly introduced in increasing diameters for lateral bone dilation, and for condensing the medular bone for the simultaneous placement of dental implants. With each insertion of a larger spreader, the bone is pushed laterally. Patient acceptance of this technique has been very high. The ERE technique and Summers’ Osteotome techniques are based on a “palm-held” design and the mallet. Sethi and Kaus¹³ described the use of a D-shaped (in cross section) osteotome and mallet to progressively separate the cortical plate. Such force application and repeated malleting can be quite uncomfortable to the patient.
The chances of achieving a sufficiently lateral dilation with the BST are excellent.^14,15 The author’s clinical experience indicates that threadformer and “screw-type” design are most appropriate in placing implants in areas of buccal bone resorption and in soft maxillary bone.

CONCLUSION
BST for ridge horizontal augmentation with immediate implant placement has been shown to be predictable and successful in treating the maxilla with deficient alveolar bone width. BST is superior to drilling techniques for application in soft maxillary bone and offers a number of advantages over Summers’ Osteotome Technique. The BST has proven to be more comfortable for patients, increasing their acceptance and overall satisfaction. As with any implant treatment, presurgical planning is important to achieving a desirable outcome.

References

1. Collins TA. Onlay bone grafting in combination with Brånemark implants. Oral Maxillofac Surg Clin North Am. 1991;3:893-902.
2. Jensen J, Sindet-Pedersen S. Autogenous mandibular bone grafts and osseointegrated implants for reconstruction of the severely atrophied maxilla: a preliminary report. J Oral Maxillofac Surg. 1991;49:1277-1287.
3. Misch CM, Misch CE. The repair of localized severe ridge defects for implant placement using mandibular bone grafts. Implant Dent. 1995;4:261-267.
4. Misch CM. Comparison of intraoral donor sites for onlay grafting prior to implant placement. Int J Oral Maxillofac Implants. 1997;12:767-776.
5. Montazem A, Valauri DV, St-Hilaire H, et al. The mandibular symphysis as a donor site in maxillofacial bone grafting: a quantitative anatomic study. J Oral Maxillofac Surg. 2000;58:1368-1371.
6. Triplett RG, Schow SR. Autologous bone grafts and endosseous implants: complementary techniques. J Oral Maxillofac Surg. 1996;54:486-494.
7. Shulman LB: Surgical considerations in implant dentistry. J Dent Educ. 1988;52:712-720.
8. Summers RB. A new concept in maxillary implant surgery: the osteotome technique. Compendium. 1994;15:152-162.
9. Summers RB. The osteotome technique: Part 2—The ridge expansion osteotomy (REO) procedure. Compendium. 1994;15:422-436.
10. Scipioni A, Bruschi GB, Calesini G. The edentulous ridge expansion technique: a five-year study. Int J Periodontics Restorative Dent. 1994;14:451-459.
11. Scipioni A, Bruschi GB, Giargia M, et al. Healing at implants with and without primary bone contact. An experimental study in dogs. Clin Oral Implants Res. 1997;8:39-47.
12. Elian N, Jalbout Z, Ehrlich B, et al. A two-stage full-arch ridge expansion technique: review of the literature and clinical guidelines. Implant Dent. 2008;17:16-23.
13. Sethi A, Kaus T. Maxillary ridge expansion with simultaneous implant placement: 5-year results of an ongoing clinical study. Int J Oral Maxillofac Implants. 2000;15:491-499.
14. Nishioka RS, Souza FA. Bone spreading and standardized dilation of horizontally resorbed bone: technical considerations. Implant Dent. 2009;18:119-125.
15. Nishioka RS, Paixão JC. Bone spreading technique. A case report. Chirurgia. 2009;22:121-123.

Dr. Nishioka is a professor of prosthodontics and implant dentistry in the Department of Dental Materials and Prosthodontics, State University of São Paulo, São José dos Campos, São Paulo, Brazil. He can reached via e-mail at nishioka@fosjc.unesp.br or nishiokaunesp@gmail.com.

Disclosure: Dr. Nishioka reports no disclosures.