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Written by Dennis Flanagan, DDS Saturday, 01 April 2006 00:00
Osteotomes are surgical instruments that can be used effectively to enhance the placement of dental implants.1-4 The term osteotome means a bone-cutting or bone-deforming instrument. Osteotomes are generally wedge-shaped instruments with varied steepness of taper, designed to compress, cut, or deform bone (Figure 1). They are available with flat blades, pointed tips, and concave (cupped) and convex (D-shaped) ends. Osteotomes are used in several ways during implant surgery, but generally they cut, compress, or deform bone to facilitate the placement of implants.
RATIONALE FOR OSTEOTOME USE
|Figure 1. Osteotomes are tapered to compress and expand the bone opening. (Photo courtesy of Implant Innovations.)|
The inorganic hydroxyapatite crystals in bone do not effectively dissipate energy, but the organic portion of bone can dissipate a significant amount of energy. Collagen is the primary organic polymer of bone. Deforming bone to accommodate the placement of an implant takes advantage of a unique molecular property of bone collagen. The main column of a collagen molecule is rigid and difficult to break. However, the molecular bonds between these main polymeric chains are easily broken. These are termed sacrificial bonds. This molecular property of collagen gives bone its toughness and ability to deform before breaking ("greenstick fracture"). Further, reduced cross-linking of collagen is associated with reduced bone strength.5
It is important to emphasize that healing of bone depends on an adequate blood supply. If bone deformation associated with implant placement can be accomplished without raising a full-thickness mucoperiosteal flap, the periosteum, and thus the blood supply, remains intact. In this situation two walls of cortical bone would contain both a blood supply and viable osteocytes.6 This is advan-tageous for osteogenesis. Further, any gaps created that are more than 1 mm in width can be filled with bone graft material.7
The osteotome gives the surgeon a tactile sense of the bone quality. These instruments compact the bone, resulting in greater density, which is better for initial implant support. They serve to extend the apical floor of the osteotomy, and in contrast to rotary instruments, they have the added advantage of not generating heat during use.2
Figure 2. The osteotome condenses and compresses the bone trabeculae.
Figure 3. Ridge expansion occurs by gradually expanding the bone ridge.
Figure 4. A D-shaped osteotome (Tatum Dental).
Figure 5. An atrophic edentulous site.
Figure 6. The initial bone cut is made with the scalpel.
Figure 7. The osteotome is introduced to begin the expansion.
Figure 8. The osteotome deforms the facial bone to the facial as the opening is expanded.
Figure 9. A flat blade osteotome for ridge expansion (DF Flanagan).
Figure 10. The atrophic edentulous site is split and expanded to accept an implant.
Osteotomes generally are manufactured with round, flat, or a variety of shaped blades. The round osteotomes are used during ridge crest approach sinus lift procedures and for bone compression (Figure 2). The sinus lift is performed to move the sinus lining away from the bone cavity of the sinus, creating a space for placement of bone graft material with the intent of creating additional bone volume to receive and encase a dental implant.8 The cortical bone must be of sufficient thickness and density for implant support, and ultimately will serve to resist occlusal forces on the restored implant.
A D-shaped blade channel former osteotome (Tatum Dental) is used to cut and separate the cortices to create space and to expose the more apical bone for osteotomy drilling (Figures 3 to 8). The coronal or crestal bone is spread apart and bent to allow access for drilling the deeper portion of the implant site. As noted, the apical bone must be sufficiently dense to support the implant and provide initial stability to allow osseointegration to occur. The coronal bone is fractured during site preparation and may not initially be able to provide support for the implant. Generally, the lingual cortex is thicker and more rigid than the buccal cortex and is used to brace the osteotome to bend and deform the facial cortex in a facial direction. This creates space for grafting, osteogenesis, and apical access.
Other osteotome shapes can be used for the same purpose (Figure 9).9 Bladed osteotomes can be used to cut into the cortex of bone to split the cortices apart or segment a portion of bone (Figure 10).9 A pointed-end osteotome can be used to advance and widen the osteotomy in less dense bone. The cortex must be drilled wide enough to accommodate the osteotome so the instrument does not meet resistance. Cupped-ended osteotomes are used to collect and compress bone into the apical end of the osteotomy (Figure 1). This can be useful during sinus lift procedures. Flat-ended osteotomes can compress (but not collect) bone fragments for increased density.
Many implant manufacturers provide "fitters" in their surgical kits. A fitter is made in the exact shape and dimensions of a selected implant. It is used to determine if the osteotomy is correctly sized for the implant that will be placed. The fitter can also be used as an osteotome to compress the bone of an intentionally undersized osteotomy in sites where the bone is less dense. The fitter can be held in a needle holder and pressed into the osteotomy. The gingival architecture need not be disturbed in cases that can be performed without raising a surgical flap (Figure 9). When a mucoperiosteal flap is not raised, the periosteal blood supply is not disturbed, and the gingival aesthetics are preserved.
Due to variations in bone density, resorption patterns, and the proximity of different anatomical structures that must be considered or avoided, it is useful to divide the jaws into 4 areas where osteotomes can be used: anterior maxilla, posterior maxilla, anterior mandible, and posterior mandible.
ANTERIOR MAXILLA: TOOTH SITE NOS. 6 TO 11
Bone density can be characterized from dense cortical to fine trabecular. The more cortical the nature of the bone, the more difficult it is to manipulate and deform. The anterior maxillary bone is usually less dense than the anterior mandibular bone, but is more dense than the posterior maxillary bone. Misch has ranked bone densities into 4 categories: D-1, D-2, D-3, and D-4 in decreasing densities.10
Figure 11. Sagittal view of an atrophic edentulous site with an initial bone cut.
Figure 12. The facial cortical plate needs to be deformed facially.
Figure 13. The osteotomes deform the facial plate to the facial to create an opening.
Figure 14. The site is apically drilled for placement of an implant.
Figure 15. An atrophic edentulous No. 9 site.
|Figure 16. The site was split and expanded and an implant placed; note the improved facial contour that will rebound and round out further.|
Figure 17. An acceptable aesthetic outcome.
Bone density in the anterior maxilla can range from D-1 to D-4. The osteotomes used in the anterior maxilla are generally flat-bladed instruments. The bone in this area can be thin due to a pattern of facial resorption (Figures 11 to 14).11 The anterior maxilla can also have a curvilinear bone contour that may complicate ridge expansion. When the facial cortex is deformed facially, the bone is now in a longer outer arch. The cortex does not readily stretch to make up the length discrepancy. That is, the facial aspect of the maxillary bone cortex, when expanded to the facial, will not be an intact plate and will fracture. Thus, the facial cortical plate will not be contiguous. These expanded sites may need flap designs where adjacent soft tissue is recruited to close the surgical site. Additionally, soft-tissue grafts or acellular dermal grafts (AlloDerm [Life-Cell]) can be used to ensure primary closure of the expanded bone to promote osteogenesis and osseo-integration. Small or single sites may require initially splitting the ridge with a No. 15 scalpel and subsequently expanding the split with flat blade osteotomes such as thin chisels, followed by apical preparation for implant insertion (Figures 10, 15 to 17).
POSTERIOR MAXILLA: TOOTH SITE NOS. 1 TO 5 AND NOS. 12 TO 16
In the posterior maxilla, bone density generally ranges from D-2 to D-4. Further, the antrum can be pneumatized to reduce the available bone volume, and resorption on the facial surface can produce a thin ridge.12 These limited sites may require staged expansions and augmentations. The narrow ridge may need to be split, expanded, and grafted with flat blade osteotomes before lifting the sinus lining and bone grafting using round osteotomes.
ANTERIOR MANDIBLE: TOOTH SITE NOS. 22 TO 27
The bone density in the anterior mandible can range from D-1 to D-4. The primary blood supply is from the periosteum, which arises from the facial artery. Flapless or split-thickness mucoperiosteal flaps may be considered when placing implants in the anterior mandible to minimize disruption of the blood supply. The bone in this area is generally denser and less amenable to splitting and expansion. As in the anterior maxilla, single implant sites may be split with flat blade osteotomes. Extracortical augmentation, ie, addition of bone graft material to the facial aspect of the bone cortex, may be accomplished instead if a complete alveolar bone fracture is anticipated. In large edentulous sites, space for insertion of graft material and/or the implants themselves (bone flaps) may be created by cutting through the buccal cortical bone at the crest, continuing to the proximal borders, and then elevating the soft and hard tissues with flat osteotomes. Note that small perforations at the base of the bone flap may be needed to release and move the bone flap facially. The perforations must be made at the base of the bone flap where the thickness of bone will allow flexure in the facial direction. That level is usually where the facial cortex is less than 1 mm thick. Again, there may be a primary closure-arch form problem with expansion of the facial cortex.
POSTERIOR MANDIBLE: TOOTH SITE NOS. 17 TO 21 AND NOS. 28 TO 32
Facial resorption can occur in the posterior mandible, resulting in a thin alveolar ridge. Bone density in this area ranges from D-2 to D-4. The blood supply in the posterior mandible comes primarily from the inferior alveolar artery. Since this artery is intraosseous, bone splitting and expansion must consider the position of the vessel. The artery is usually in the superior position within the neurovascular bundle. If during surgery only the artery is damaged, a temporary neuropathy may result from the metabolic breakdown products of porphorins.13,14
Figure 18. An edentulous site in the mandible.
Figure 19. The site was split and expanded, and an implant was placed.
Using osteotomes to achieve expansion of the bone ridge in the posterior mandible is possible, but as with the anterior mandible, this bone can be rigid and less flexible than maxillary bone. Drill cuts and flat blade osteotomes are used to elevate and raise a bone flap at large sites. Any perforations at the base of the bone flap must be made so as to avoid the neurovascular bundle. Single implant sites may be expanded for implant placement (Figures 18 to 19). Implant sites that are located more posteriorly may pose access problems. Angled or off-set osteotome handles can be used. In conclusion, osteotome expansions in the mandible can be major oral surgical procedures.
THE USE OF OSTEOTOMES
Osteotomes can be lubricated with saline or sterile water to facilitate movement through tissue. Round osteo-tomes should be used with straight, in-and-out movements to prevent the osteo-tomies from assuming an oval shape. This shape will be detrimental to implant healing and/or osseointegration. Other shaped osteotomes, such as those with a convex shape (D shape), may be removed by movement in a mesial-distal direction rather than a straight, in-out movement; but facial-lingual movement should be avoided so as not to deform further the facial cortex.
Osteotomes are optimally used by pressing the instrument into the bone and malleting, ie, tapping the osteotome into place with a surgical mallet only when there is slight resistance. Firmer resistance may indicate the need for wide-ning the cortex with a drill. Generally, most resistance is caused by a cortical opening that is too small for the osteo-tome to easily pass through.
COMPLICATIONS ASSOCIATED WITH THE USE OF OSTEOTOMES
A misdirected osteotome can result in a malpositioned implant. This may be corrected by redrilling and reworking the site in the appropriate direction with the properly sized osteotome. If the osteotomy cannot be salvaged, the site may need to be grafted and re-entered after an appropriate healing time of about 3 to 6 months.
During malleting of an osteotome, a labyrinthine concussion may occur.15 The labyrinth is the internal ear and receives the ultimate distribution of the acoustic nerve. It communicates to the brain the body's position in space and is essential for balance. If a labyrinthine concussion occurs during minor head trauma, the otoliths in the semicircular canals of the labyrinth dislodge and relocate in the ampulla or vestibule of this organ. Since the labyrinth orients balance and position, the patient may incur a benign positional vertigo. The patient will arise from the dental chair and almost immediately feel dizzy when turning the head to the right and/or left. This condition is generally self-limiting and lasts 1 to 3 weeks. However, some patients may require specific treatment in the form of head maneuvers to reposition the otoliths. The patient is placed in the prone position, and a clinician, usually an appropriately trained ear, nose, and throat physician, maneuvers the head in various positions to reposition the dislodged otoliths. Sedatives or antivertigo medications may also be required.
Osteotomes can be important adjunctive instruments during dental implant placement. Bone manipulation with osteotomes can create space for osteogenesis, lengthen the apical floor of the osteotomy, compact the bone for better density and initial implant stabilization, and give the surgeon a tactile sense of bone quality. This is accomplished without heat being generated. Various osteotome blade designs are used to define the appropriate shape and size of the osteotomy.
1. Garg AK. The use of osteotomes: a viable alternative to traditional drilling. Dent Implantol Update. 2002;13:33-40.
2. Hahn J. Clinical uses of osteotomes. J Oral Implantol. 1999;25:23-29.
3. Saadoun AP, Le Gall MG. Implant site preparation with osteotomes: principles and clinical application. Pract Periodontics Aesthet Dent. 1996;8:453-463.
4. Summers RB. The osteotome technique: part 2--The ridge expansion osteotomy (REO) procedure. Compendium. 1994;15:422-426.
6. Yin XM, Dai JX, Wang XH, et al. Observation of blood supplies system to mandible in transparent specimen [in Chinese]. Shanghai Kou Qiang Yi Xue. 2003;12:266-268.
7. Oikarinen KS, Sandor GK, Kainulainen VT, et al. Augmentation of the narrow traumatized anterior alveolar ridge to facilitate dental implant placement. Dent Traumatol. 2003;19:19-29.
8. Fugazzotto PA. Treatment options for augmentation of the posterior maxilla. Implant Dent. 2000;9:281-287.
9. Flanagan D. Cortical bone spreader osteotome and method for dental implant placement. J Oral Implantol. 2002;28:295-296.
10. Silverstein LH, Kurtzman GM, Moskowitz E, et al. Aesthetic enhancement of anterior dental implants with the use of tapered osteotomes and soft tissue manipulation. J Oral Implantol. 1999;25:18-22.
11. Misch CE. Bone density: a key determinant for clinical success. In: Misch CE. Contemporary Implant Dentistry. 2nd ed. St Louis, Mo: Mosby; 1999:109-118.
12. Horowitz RA. The use of osteotomes for sinus augmentation at the time of implant placement. Compend Contin Educ Dent. 1997;18:441-452.
13. Pirouzmand F, Midha R. Subacute femoral compressive neuropathy from iliacus compartment hematoma. Can J Neorol Sci. 2001;28:155-158.
14. Brash PD, Foster JE, Vennart W. Magnetic resonance imaging reveals micro-haemorrhage in the feet of diabetic patients with a history of ulceration. Diabet Med. 1996;13:973-978.
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