Ridge Expansion with Motorized Expanders
The treatment of atrophic ridges with traditional expansion techniques has a number of clear limitations—primarily that they can be used only for the maxilla. Atrophic maxillae with type II bone also present significant challenges. The principal advantage of the BTI standard and short-length Motorized Expander/Compactor Drill System (BTI of North America, Blue Bell, PA) is that it simplifies the technique and can be used in both the maxilla and the mandible in type II and type III bone. It also offers excellent operator control over the implant insertion path (Figure 1A through Figure 2). More precise and atraumatic expansion increases patient comfort and improves conditions for im-plant site preparation.
Digital surgical planning is essential for the ridge-expansion technique and determines the drilling and expansion/compaction sequence. Dimension charts and drilling sequence guides are provided with the kit.
Since the introduction of maxillary ridge expansion using osteotomes in 1994, the technique has undergone numerous modifications.1 Still, percussive expansion with a mallet is excessively traumatic for the patient and can occasion a labyrinthine concussion or benign paroxysmal positional vertigo.2
Motorized titanium osteotome drills are used almost exclusively for the compaction of type IV and type V bone and for a sinus-lift procedure (only expander Nos. 3 and 4 with blunted tips are recommended for the sinus-lift procedure).3 An electric surgical motor equipped with torque control is set no higher than 20 Ncm to 25 Ncm to prevent damage to the handpiece. When resistance increases, expansion continues with the manual ratchet wrench. The initial drill is operated at high (800 rpm to 1,000 rpm) speed with irrigation. The other two drills (1.8 mm [not shown] and 1.8/2.5 mm) are inserted with slightly more pressure toward the palatine process. They are run at 30 rpm to 50 rpm without irrigation to maintain a safe temperature for preserving bone and preventing washing away viable autologous material ideal for grafting.4 For type II bone, a 3.3-mm diameter implant in the maximum length possible is preferable rather than splitting the cortical layer completely by installing a 3.75-mm diameter implant (Figure 3).
The implant must be the last expander. Most implants work well; however, rounded, cylindrical, or blunt screw-type designs are inappropriate following this technique. The tapered design of the self-tapping BTI implant (BTI of North America) apex is similar to a tooth root and has an active cutting apex to advance in and safely store bone.
Micro- or macrofractures usually occur and provide an excellent osteogenic bed that encourage graft revascularization (Figure 4A; Figure 4B; Figure 4C;). Overcorrection is achieved using autologous bone obtained from a donor area or from the adjacent implant sites by using BTI bone harvesting drills and compacting into a PRGF® (Plasma Rich in Growth Factors, BTI of North America) clot, facilitating handling and enhancing the graft with signaling cells. If sufficient autologous bone is unavailable, the next layer consists of a biomaterial mixed with PRGF.5-9 The entire graft is covered and compacted with autologous fibrin (Figure 5A; Figure 6A; Figure 6B).
References1. Summers RB. A new concept in maxillary implant surgery: the osteotome technique. Compendium. 1994;15(2):152-162.
2. Lee EA, Anitua E. Atraumatic ridge expansion and implant site preparation with motorized bone expanders. Pract Proced Aesthet Dent. 2006;18(1):17-22.
3. Anitua E. Ridge expansion with motorized expander drills. Dental Dialogue. 2004;2:3-13.
4. Anitua E. New process for drilling, placing implants and obtaining autologous bone. Implant Dialogue. 2004;1:2-11.
5. Anitua E. PRGF®. Dental Dialogue. 2004:3:2-15.
6. Anitua E. Platelet rich plasma. Growth factor enhancement for developing future sites. Paper presented at: XIII Annual Meeting Academy of Osseointegration; March 1998;Atlanta, GA.
7. Anitua E. Plasma rich in growth factors: preliminary results of use in the preparation of future sites for implants. Int J Oral Maxillofac Implants. 1999;14(4):529-535.
8. Anitua E. A New Approach to Bone Regeneration. Plasma Rich in Growth Factors (PRGF®). Vitoria, Spain: Puesta al Día Publicaciones, 2000.
9. Anitua E. PRGF—Plasma Rich in Growth Factors: A Simple Solution for Post-Extraction Sites. Inside Dentistry. 2006:2(5):92-93.
This article was written by Dr. Eduardo Anitua, an oral surgeon specializing in complex oral rehabilitation and tissue regeneration techniques. He lectures extensively worldwide on these topics and maintains a private practice in Vitoria, Spain.
|Figure 1A and Figure 1B Standard-length (up to 15 mm) (Figure 1A) and short-length (up to 11.5 mm) (Figure 1B) motorized ridge expander/compactor drills. Short drills are available for use with the shorter compactor drills for patients with limited opening. (Images not to scale.)||Figure 2 The BTI motorized expander/compactor drill system can be used with high-torque electric motors with reduction-gear contra-angles.|
|Figure 3 The BTI initial drill is always used first, penetrating to a depth of 8 mm to 10 mm, leaving a socket with a maximum diameter of 1.5 mm. It is followed by the 1.8 mm and 1.8/2.5 mm burs for deeper drilling toward the palatine process (expander No. 1, followed by the initial drill, allows expansion of both type II and type III bone). Expander No. 2 prepares the surgical bed for installation of the last expander (a 3.3-mm BTI implant with patented self-tapping apex designed for adequate bone storage capacity). Grafting material is applied to completely cover the implant surface.||Figure 4A Extremely resorbed ridge precisely assessed for bone density with BTI Scan® (BTI of North America).|
|Figure 4B Apical third of the implants engaged.||Figure 4C Overcorrection achieved with biomaterial and an autologous membrane made from PRGF.|
Figure 6A Before treatment.
Figure 6B After treatment.
|Figure 5A through Figure 5C Overcorrection is achieved by layering autologous bone enhanced with PRGF (Figure 5A) followed by a layer of Bio- Oss® (Osteohealth, Shirley, NY) mixed with PRGF (Figure 5B) and then an autologous fibrin membrane, also prepared with PRGF (Figure 5C).|