Implant bone expanders-Atraumatic use

Limitations and Complications 
While effective in the anterior maxilla, the osteotome technique exhibits limitations when utilized in posteriorareas. The instruments frequently encroach upon the facial soft tissues when treating second premolar or molar sites.
Although osteotomes with angled offsets have been designed to circumvent this limitation, they are not as effective in transmitting compressive or expansion forces.8 By nature, the osteotome technique is a traumatic procedure. The instruments are advanced with the impact of a surgical mallet, which compacts and expands the bone in the process of preparing osteotomy sites that will allow implant placement.2 Treatment of mandibular sites is often limited due to the increased density and reduced plasticity exhibited by the bone. Additionally, since the osteotome is inserted by hammering, the explosive nature of the percussive force that is delivered instantaneously provides limited control over the expansion process, which often leads to unintentional displacement or fracture of the labial plate of bone

Figure 1. Proprietary initial drill (BTI, Blue Bell, PA) provides
increased accuracy and eliminates vibration and “walking”
movements. Note resorption of the labial plate

Figure 2. Illustration of recommended surgical
drill and bone-expander sequences for placement
of 3.75-mm–diameter implants

Figure 3. Diagram of the surgical drill and boneexpander
sequences for the placement of
5-mm–diameter implants

Many patients do not tolerate the osteotome technique well, frequently complaining about the impact from the surgical mallet. In addition, several reports have documented the development of a variety of complications
(eg, labyrinthine concussion, benign paroxysmal positional vertigo) that result from the percussive trauma.9- 12 Preparation of implant sites with osteotomes and a mallet transmits forces capable of detaching heavy inorganic
particles from the otoconial layer of the utricular macula.
The surgical positioning of the patient, with the head in hyperextension, favors the displacement of these particles into the posterior semicircular canal. Once the patient resumes a seated position, the particles deposit themselves on the ampullar crest, triggering an anomalous stimulus that results in vertigo. Symptoms include

Figure 4. The 1.8-mm and 1.8-mm/2.5-mm
surgical burs may be utilized prior to the bone
expanders if sufficient ridge width is present

Figure 5. Ridge expansion with the #3 bone
expander. Despite adequate bone, expansion
will prevent excessive lingual positioning

dizziness, nausea, and vomiting; in more serious cases, the patient’s gait could be imbalanced and the eyes may show nystagmus (ie, constant involuntary cyclical movement of the eyeball in any direction). The condition is
considered self-limiting, usually with a duration of several days, but may last several weeks. If symptoms persist, treatment may include physical therapy, medication, chemical ablation, and surgery. Middle-aged and elderly patients exhibit increased susceptibility, particularly those with degenerative cervical spine disease that exhibit cervical proprioceptive dysfunction

Atraumatic Implant Site Preparation
A technique has been developed that allows the atraumatic
preparation of implant sites by eliminating the use
of a surgical mallet.13 This procedure is based on the
use of a proprietary ridge expansion system that includes a bur kit and instruments known as motor-driven bone expanders (ie, BTI, Blue Bell, PA). The expanders are introduced into the bone with motor-driven rotation rather than hammer taps, which decreases surgical trauma while providing superior control over the expansion site. The
thread pattern has been designed to compact bone laterally as the instrument advances into the osseous crest.
This system allows expansion and preparation of implant sites in Type II and III bone, as well as compaction of Type IV bone.
Atrophic ridges frequently exhibit significant amounts of Type I bone. In addition to being difficult to manipulate, this bone also tends to guide the expansion toward  the path of less resistance. With the traditional technique, the osteotome would be forced in a labial direction after encountering the denser Type I bone.This situation would frequently result in expansion of the atrophic ridge purely at the expense of the labial plate, leading to an unusable site, inadequate primary stability, or to an implant placed in an excessively labial position. The motor-driven bone-expander system includes surgical burs that allow drilling into the cortical bone to improve control of the expansion so that the implant may ultimately be placed in an appropriately centered position within the expanded crest. Expansion may be initiated at a more palatal position, and then mechanically oriented in a labial direction by applying pressure on the bone expander as it rotates while advancing into the atrophic ridge. Since they are operated with an electric handpiece, the expanders can be utilized in the anterior as well as posterior regions without impingement of the facial tissues or the positional limitations imposed by traditional osteotomes

Figure 6. Expansion is completed by inserting the #4 expander. It is
safer to undersize the osteotomy when placing the implants

Furthermore, the rotational control of the expansion permits treatment of the mandibular atrophic ridge. The system can be utilized by itself or with osteotomes and surgical drills to assist in the placement of a variety of implant designs. In the authors’ experience, this technique offers enhanced control of the application, timing, and direction of the expansion forces

Clinical Technique
Site preparation begins with the use of the initial bur at a speed of 700 rpm to 800 rpm with irrigation, according to the manufacturer’s instructions (Figure 1). This bur will remain in place without vibration or “walking” movements, even when utilized on inclined surfaces or uneven residual ridges. The initial bur is used to a depth o 8 mm to 10 mm, creating an osteotomy of 1.5 mm in diameter. The specific drill and bone-expander sequence followed will vary according to the width of the atrophic ridge, the expansion characteristics of the site, and the desired diameter of the implant (Figures 2 and 3).
Provided that the residual ridge is sufficiently wide, the 1.8-mm and 1.8-mm/2.5-mm burs may be subsequently utilized at 50 rpm without irrigation, followed by the #3 expander and, when indicated, the #4 expander (Figures 4 through 8). The bone expanders are drive by an electric handpiece used at speeds of 15 rpm to 30 rpm. The torque settings on the surgical motor shouldremain between 15 Ncm and 20 Ncm to prevent damage to the handpiece. Once sufficient resistance is encountered, expansion should then continue with a manual ratchet wrench. The instruments may be inserted in intervals, pausing to allow time for the bone to expand.
Since the bone expanders have a tapered design, it is important that the clinician possess a clear understanding of the dimensions involved in order to avoid excessive expansion that may compromise implant placement.
The maximum diameter for each instrument is reached at the 15-mm–length marking. Clinical judgment must, therefore, be exercised to determine the degree to which the bone expander should be inserted in order to accommodate the length, diameter, and design of the implant selected.
Generally speaking, it is safer to keep the diameter of the expanded site less than the diameter of theimplant. Final expansion of the site, however, will dependon the type of implant selected. Implants with a tapered,self-tapping design may be placed into a more undersizedosteotomy; the only prerequisite is that the site should be prepared to an adequate width to accommodate
the implant apex. Conversely, implants with alimited self-tapping ability should be placed into anosteotomy that closely approximates the dimensions ofthe fixture selected. This situation may require preparation with the corresponding final drill, following the utilization of bone expanders

Figure 7. A 5-mm–diameter platform implant is
placed. Rotational control of the expansion
allows treatment of mandibular sites

Figure 8. Postoperative radiograph of implant in
situ. Sufficient expansion of Type II bone was
achieved to accommodate the flared collar

Figure 9. Motor-driven bone expanders allow
gradual expansion of the labial plate, which
allows greater manipulation of the site

Figure 10. Significant displacement of the fractured
segments may be controlled to allow
fixture insertion

Figure 11. Once adequate implant stability is
achieved, the fracture site may be grafted utilizing
a one-stage approach

Figure 12. An autologous fibrin clot was placed
over the graft mixture to serve as a space maintainer
and to enhance soft tissue healing

Figure 13. Re-entry procedure shows complete
healing of fracture site and regenerated labial
plate following a 4-month postoperative period

Figure 14. View following extraction of a retained
deciduous maxillary molar. This site is frequently
not amenable to immediate implant placement

Clinical Applications
The authors’ clinical experience suggests that the motordriven bone expanders may provide increased control over the expansion site, therefore allowing treatment of more severely atrophic ridges than previously possible with traditional osteotomes. Additionally, once the plastic capacity of the bone has been exceeded, this technique allows a gradual and controlled fracture of the buccal plate that may be deliberately induced to meet the expansion requirements. The displacement of the fractured segments may be closely monitored and, as long
as adequate implant stability is achieved, the fracture site may be grafted and implant placement may be accomplished with a single-stage approach (Figures 9 through 13). Compared to the smooth-sided osteotomes, the threaded design of the motor-driven bone expanders prepares taps in the osteotomy site that facilitate the subsequent insertion of a threaded implant, and promote initial stability as well.
Furthermore, the dental professional's enhanced ability to manipulate and expand the alveolar walls and interradicular crests may result in an increased number of sites that may be amenable to immediate postextraction implant placement and avoid the need for
multiple-stage procedures. Sinus floor elevation may also be performed with these motor-driven bone expanders by utilizing a crestal approach to access the maxillary sinus and elevate the Schneiderian membrane (Figures 14 through 17). Due to their dimensions and blunt apical design, the #3 and #4 expanders
are better suited for this purpose. Additionally, these instruments may subsequently be used to pack the grafting material. Although the narrower bone expanders may be utilized to penetrate the sinus floor, caution must be taken because of the increased risk of perforating the Schneiderian membrane

Figure 15. With the use of motor-driven bone expanders, the implant
site was developed by expanding the interradicular bone into the
adjacent sockets

Figure 16. Adequate expansion allowed immediate placement of a
5-mm–diameter, wide-platform implant with no exposed threads and
excellent primary stability

Figure 17. The maxillary sinus floor was atraumatically elevated utilizing
the blunt apex of the bone expanders through a crestal
approach. Final implant length was 11.5 mm


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