Patent Application
20130224683
The present disclosure generally relates to dental tools and, more particularly, relates to drills used for forming an osteotomy.
Dental implants have become an increasingly common procedure for people needing tooth replacement as a result of a traumatic event, or through decay. With such a procedure, an osteotomy must first be performed to create an opening in the soft tissue of the gums and then ultimately into the bone of the jaw, either the upper or lower. Once the osteotomy is formed, an anchor portion of the implant is secured within the osteotomy after which other components can be built on top of the anchor, ultimately ending in an aesthetic crown or cap.
While effective, the osteotomy is typically formed by using a rotating drill bit extending from a drill which the dentist or oral surgeon manually positions and engages. As the soft tissue and even bone are relatively soft materials, the drill is typically provided with a cutting tip having a relatively narrow angulation. It is believed by the industry that such narrow angulation reduces wear on the drill and thus prolongs its life while at the same time reducing chatter, or vibrational kickback. Nonetheless, it is desired to have a drill bit which has an even greater usable lifetime over that which is currently available in the marketplace.
In addition, typical osteotomies are created with a tapered bottom if not an overall conical shape. This has typically been done to accommodate the generally tapered or conical shape of typical implants. However, more recent implants have more of a cylindrical shape and thus typical drills to not accommodate such implants. As a result, installation of cylindrical implants into more conically shaped osteotomies can lead to air pockets surrounding the implant. This not only invites bacteria and infection, but leads to more prolonged recovery times and thus discomfort for the patient.
In accordance with one aspect of the disclosure, an orthopedic drill bit is disclosed which may comprise a shaft, a spiral flute, and a cutting tip. The shaft may have a proximal and a distal end, the spiral flute extending along the shaft from the distal end to the proximal end. The cutting tip may be provided at the distal end. The cutting tip may also have first and second facets intersecting at an apex, with the apex forming an angle of at least 125°.
In accordance with another aspect of the disclosure, a method of forming a dental osteotomy is disclosed which may comprise providing a dental drill bit having a shaft, a spiral flute and a cutting tip, with the shaft having a proximal end and a distal end, the spiral flute extending along the shaft from the distal end to the proximal end, and the cutting tip being provided at the distal end. The cutting tip may have first and second facets intersecting at an apex, with the apex forming an angle of at least 125°. The method may include a second step of engaging the cutting edge with human tissue, the cutting edge removing tissue as it rotates.
In accordance with another aspect of the disclosure, the dental osteotomy kit is disclosed which may comprise a dental drill bit and a dental implant. The dental drill bit may have a shaft, a spiral flute and a cutting tip, with the shaft having a proximal end and distal end, and the spiral flute extending along the shaft from the distal end to the proximal end. The cutting tip may be provided at the distal end of the shaft and include first and second facets intersecting at an angle of at least 125°. The dental implant may have an apical end in the shape of the drill bit distal end.
These and other aspects and features of the disclosure will become more readily apparent upon reading the following detailed description when taken into conjunction with the accompanying drawings.
While the following detailed description has been given and will be provided with respect to certain specific embodiments, it is to be understood that the scope of the disclosure should not be limited to such embodiments, but that the same are provided simply for enablement and best mode purposes. The breath and spirit of the present disclosure is broader than the embodiments specifically disclosed and encompassed within the claims appended hereto.
Referring now to
Again with reference to
The distal end 26 on the other hand includes cutting tip 30 as well has spiral flutes 32 sweeping away from the cutting tips 30 toward the proximal end 24. While the spiral flutes 32 may perform some cutting function in the sides of the osteotomy as well, they are primarily provided as means of transporting the soft tissue and bone fragments away from the osteotomy site during the procedure. While the teachings of this disclosure can be used to create a drill bit 20 with any desired dimension, the inventors have found that diameters ranging from 2.8 millimeters to 5.7 millimeters and lengths of around 40 millimeters (15-18 mm of which, for example, would be spiral flutes) can generally create osteotomies suitable for placement of dental implants in human anatomy.
Referring now to
The angle, or angulation, at which the facets 36 and 38 extend from the apex 42 to the outer circumference 40 is of importance. As shown in each of
The impact of the angulation angle α is perhaps best depicted with reference to
One additional benefit of having such a shallow angle of angulation α is that the overall depth of the osteotomy 46 which needs to be created to accommodate an implant 48 is greatly reduced. This is shown most effectively in a comparison between
With the osteotomy 46 formed by the present disclosure drill 20, on the other hand, it can be seen that when the implant 48 is fully inserted therein, a greatly reduced amount of air space 52 is created in that the osteotomy 46 much more closely matches the overall shape of the implant 48. In so doing, the drill 20 of the present disclosure not only affords a better fit for the implant 48, but also greatly reduced recovery time, lessened likelihood of infection, and a reduction in the tissue volume needed to successfully place the implant. Moreover, given the close match between the shape of the resulting osteotomy 46 and the implant 48, both may be sold or otherwise provided as a kit 51.
Referring again to
From the foregoing, it can be seen that the present disclosure sets forth a dental drill which results in an osteotomy having a lower overall depth than prior art osteotomies, a more cylindrical shape than prior art osteotomies, and a general form which more closely matches that of cylindrically shaped dental implants. In so with doing, the amount of excess space surrounding the dental implant once inserted in the osteotomy is reduced and thus the ability of the surrounding tissue to infiltrate and fuse with the implant is enhanced while also reducing the likelihood of infection, generally reducing overall recovery time, and allowing the implant to be placed in regions of reduced vertical tissue height.
In addition, Applicants wish to point out that the drill drastically departs from the general understanding of drill design. More specifically, it has been generally thought, and is still believed in the industry (both dental and heavy industry) today that when drilling in softer materials such as gum tissue and bone, relatively narrow angulations are desired to prolong drill serviceability and reduce chatter or vibration. Only with relatively hard materials such as metal, was it believed to be beneficial to use a more obtuse angulation. However, the inventors have found that this is not the case. As shown in the test data replicated in the charts and steps below, by increasing the angulation angle, the amount of chatter is greatly reduced while at the same time spreading the cutting force over a larger area thus reducing drill wear and increasing drill life.
Axial force testing was performed on the drills 20 to determine their functional ability. It established that the force required to advance a reusable drill into a substrate at a constant rate/RPM over 25 cycles is a sufficient predictor of drill wear. Test setup and parameters were established similar to previously known drill analysis.
Acceptance of performance was based on the drills demonstrating force values equivalent to or less than the predicate device, indicating satisfactory cutting efficiency over wear and corrosive attack due to sterilization. Previous performance testing on drills demonstrated a standard deviation 0.2512 lbf within the same drill and test. As this was a released device with substantial clinical history, this amount of variation has assumed to be clinically insignificant. Thus, equivalence for this device was determined by 2-Sample t-tests detecting a difference of two standard deviations.
Using the previously derived standard deviation, a difference of two standard deviations, and a target power level of 80%, a minimum sample size of four drills was tested. As the testing process was resource intensive to repeat if sample size was deemed insufficient, six samples per drill design were tested from the beginning to ensure a sufficient power.
The drills were created to match a reduced length implant and minimize the amount of bone removed by each osteotomy. Two different variations on the drill were created. Group A (signified by the ‘A’ appended to the part number) modified the known drill design by removing the diameter ‘step’, reducing the height of the cutting flutes to a maximum effective cutting depth of 8 mmL, and adding a 6 mmL etch line. The distance of etch lines to drill tip in both groups was slightly reduced from the traditional distance, decreasing the amount of overdrill by 0.5 mm (from 1.25 to 0.75 mm). Group B (signified by the absence of the ‘A’ on the part number) added the same features as Group A, but also increased the cutting angle from 120° to 135°. Both groups had the same straight, non-cutting hub. Both groups utilize an identical, short length pilot drill, which retained the original 120° cutting tip. The pilot P/N did not feature an ‘A’ on the end of the P/N, as it is identical for both groups.
The surgical sequence of the existing drills resulted in the following diametrical bone displacement per drill, with a maximum bone displacement of 0.7 mm:
By removing the step from the drill design, the straight drills no longer had the benefit of a stabilizing lead-in diameter. To ensure the drill resistance was the same as the predicate device, the surgical sequence for the drills was then modified to maintain the same maximum bone removal (0.7 mm).
The proposed existing surgical sequence for the drills resulted in the following diametrical bone displacement per drill:
As seen above, the proposed drilling protocol increased the number of drills required for placement of the larger implant lengths, but ensured a similar amount of bone was removed for each subsequent drill in the sequence. The amount of bone removed by the drill correlated with the amount of downward force needed to complete the osteotomy.
The surgical sequence had two different types of drills. First, the pilot drill (2.3) engaged the bone and drilled from the tip on to the edge of the cutting diameter, removing the full volume of bone. This engaged all cutting features on the tip (drill to edge). All subsequent drills drilled into the pilot osteotomy avoiding the center and cutting towards the edge of the drill.
The test designs in both groups A and B did not modify the cutting surface of the pilot drill leaving it identical to the predicate device. The overall drill length was reduced shortening the cutting flutes. Shortening the cutting flutes decreased the distance between the cutting edge of the drill and ejection area clearing bone chips more quickly. The changes had no potential for negative impact on the performance; the pilot drill was not tested.
For the remaining drill configurations, the worst-case was simulated by testing the drilling pair that removed the maximum amount of bone, magnifying any potential difference in cutting efficiency. Based on Table 1 and 2, the worst-case pairs were the 4.4/3.8 mm→5.7/5.1 mm of the predicate protocol, and the 4.4→5.1 mm drilling step in the proposed surgical protocol. Both of these steps removed 0.7 mm of bone from the previously drilled osteotomy.
Both Group A and Group B were tested along with the predicate device. All drills were tested in identical bone substrates. The test bed was a dense bone simulating material, as denser bone amplifies the resistance to the cutting edge that the drill will encounter, creating a worse case wear pattern. Bone-simulating foam, as opposed to natural bone, was utilized in order to provide a more homogenous test environment, reducing variation and allowing for a more precise evaluation. Because this test was a relative comparison of predicate and prototype (production equivalent) performance, natural bone was not required to verify functionality. The comparative substrate used to model clinically dense bone was polyurethane foam composed of a dense outer layer, representing cortical bone, pressed onto a solid rigid foam core, a model of trabecular bone. The outer layer had a density of 50 lb/ft3 (pcf) and the internal foam core a density of 30 pcf.
Based on the foregoing, the following summarization chart was compiled showing the improved performance of the drill disclosed herein.
The present disclosure can find industrial applicability in many situations including medical or dental procedures wherein a generally cylindrical opening needs to be formed in human tissue. Using dental procedures as an example, an osteotomy often needs to be performed within the gum and bone of the human jaw and the dental drill set forth in the pending disclosure allows for such an osteotomy to be created in a manner which much more closely matches the generally cylindrical shape of modern dental implants. For the patient this reduces infection risk, discomfort, and recovery time, and for the dentist or oral surgeon this reduces the wear imparted to the drill itself and thus increases its serviceable life.
