A Modified Crestal Ridge Expansion Technique for Immediate Placement of Implants: A Report of Three Cases

Alveolar bone atrophy often presents a significant obstacle to achieving successful oral rehabilitation with endosseous implants. Although autologous bone grafts harvested from the oral cavity or hip have been successfully used for the reconstruction of atrophic ridges, significant postoperative morbidity typically is associated with bone harvesting performed with chisels and burs. In addition, lateral bone grafts frequently require a healing period of 4 to 6 months before dental implants can be placed. Bone splitting and widening procedures were first developed by Tatum1 in 1984 as an alternative method for the immediate placement of implants in the atrophic residual ridge.

This technique subsequently was modified for the placement of implants through a submerged protocol that allowed for oseointegration in a closed environment.2,^–7 Bone preparation through this method can considerably increase bone contact with the implant surface in areas of low bone density, can enhance the prognosis of implant survival, and can significantly improve the esthetic results of the final prosthetic restoration. In cases of severe ridge resorption, this method can be combined with guided bone regeneration (GBR).

This article reports on the treatment of 3 patients subjected to ridge expansion attained by splitting the crest of an edentulous ridge followed by immediate placement of implants and GBR.

Three consecutive patients (2 male, with a mean age of 49 years, and 1 female, aged 51 years) with thin, narrow alveolar ridges were selected for split-crest ridge augmentation followed immediately by implant placement.

Criteria for patient selection included the following:

• Good general state of health

• Nonsmoker or light smoker status

• Class IV alveolar atrophy according to Cawood and Howell⁸

• Correct interarch relationships

• Patient consent to treatment

Patient evaluations included measurement of the new alveolar ridge by means of a low-dose computerized tomography (CT) scan and the use of Fanucci's protocol9 (slice thickness, 1.25; interval, 0.6; table feed, 11.25 mm × rotation; field of view, 0.6 mm; matrix, 512 × 512; 200 Ma; 80 Kv) (Figure 1). This parameter is a mandatory prerequisite to performance of the split-crest technique.

A mid crestal full-thickness incision was made (Figure 2), and a partial-thickness flap was dissected and elevated from the palate and reflected to the buccal portion of the alveolar crest (Figure 3). Periosteum preservation was intended to reduce bone resorption and prevent free fracture of the split ridge.

Implant site osteotomies were performed according to the manufacturer's surgical guide with the use of spiral drills of increasing diameter (Figure 4). Finger pressure on the buccal and palatal bone plates during drilling procedures helped to stabilize the buccal bone plate.

After the implant osteotomies had been completed, the outline of a sagittal osteotomy was scored in the bone with a blade (No. 64 Beaver blade, BD Beaver, Waltham, Mass). The blade then was used as a chisel and was tapped with a surgical mallet (Aesculap, Tuttlingen, Germany) in small increments until a 1- to 3-mm-deep furrow was created along the length of the ridge. This same procedure was performed vertically within 2 mm of the adjoining teeth.

Once the crestal furrow and adjacent vertical bone releases were defined, a bone chisel (Hu-Friedy Mfg Co, Inc, Chicago, Ill) was progressively driven more deeply into the furrow (Figure 5), and implant osteotomy sites were prepared further to their full dimensions via an osteotome technique (bone condenser) (DENTSPLY Friadent, Mannheim, Germany) (Figure 6). Tapered, multithreaded implants (tapered screw-vent) (Zimmer Dental, Carlsbad, Calif) (Figure 7) were gently placed.

To avoid bone sequestrum or necrosis, holes were prepared with a small spiral drill (010/H254) (Komet Gebr Brasseler GmbH & Co, Kg, Lemgo, Germany) to enable suturing of the bony plates. In a segmental ridge-split procedure developed by Coatoam and Mariotti,10 an orthodontic ligature wire was used to stabilize the bone plates. The present procedure altered the original technique by replacing the ligature wire with absorbable ligatures (Safil 2–0, Braun, Melsungen, Germany), which would better resist penetration through the soft tissue during healing (Figure 8).

The furrow between the bone plates was grafted (Biogen equine spongy granular 0.5 gr, Bioteck, Vicenza, Italy) if the gap was more than 2 mm deep.11 Before suturing, a collagen membrane (eg, Biocollagen, Bioteck) was layered over the cover screw (Figure 9). The flap was reapproximated buccally and palatally, and primary closure was achieved with 4–0 sutures (Trofilene, Lorca Marin, S.A., Murcia, Spain) (Figure 9).

All patients received 2 gr of amoxicillin and clavunate per day starting approximately 1 hour before surgery and continuing for 6 days after surgery, and a nonsteroidal analgesic was given postoperatively. Postoperative instructions included a soft diet for 2 weeks and appropriate oral hygiene with 0.2% chlorhexidine mouth rinses. Sutures were removed 10 days postoperatively.

Six months after implant placement, abutments were connected and the prosthetic rehabilitation was initiated.

None of the patients who underwent the split-crest technique with GBR showed any signs or symptoms of infection during the period of postsurgery follow-up.

A total of 9 implants (3.7 to 4.7 mm × 11.5 to 13 mm) were placed with good primary stability. No intraoperative complications were recorded. At 1 year follow-up, all implants (100%) met the criteria for success as specified by Albrektsson et al.12 An increase in keratinized tissue was clinically recorded.

When compared, preoperative (Figure 1) and postoperative radiographs (Figure 10) show that substantial bone was reconstructed through the split-crest procedure. No fracture of the buccal or palatal cortical plates occurred. Healing was uneventful, and all implants were successfully loaded.

Patients with edentulous arches may have narrow, knife-edged ridge crests that make implant placement difficult. Alteration of normal anatomic properties causes intraoperative problems, compromised implant angulation, and inadequate bone support on the lingual and buccal sides of an implant. Patients may benefit from augmentation procedures; however, it can be difficult to choose the most appropriate one. Conventional onlay grafts, interpositional sandwich osteotomies, GBR with semipermeable membranes, piezoelectric stimulation, and alveolar distraction osteogenesis procedures all can be used for alveolar ridge augmentation.13,^–18 

The split-crest procedure may be indicated for sharp mandibular and maxillary ridges in patients whose bone quantity is inadequate for primary implant stabilization or in those for whom immediate placement of implants is desired.

Bone plate stability is fundamental for implant stability and for avoidance of bone sequestration. Rather than a metallic ligature, the present technique used an absorbable suture to prevent its penetration through the soft tissue during healing. Complete suture absorption generally occurs at between 60 and 90 days, when the tissue is normally healed. This procedure used a collagen membrane as a cover over the graft, which augmented the keratinized mucosa and avoided additional mucogingival surgery.

Recently, a new technique for atraumatic ridge expansion that used motor-driven instruments at low speeds was reported.19 Siddiqui and Sosovicka20 presented 2 cases in which endosseous dental implants were placed with the use of a new bone expansion osteotome kit that used a screw-type configuration for bone condensing and expanding of the receptor site.

The split-crest procedure that included GBR with a resorbable collagen membrane was a viable therapeutic alternative for implant placement into areas that otherwise would not be suitable for implants.