Abstract:
The present invention is a tool to measure depth and width of bone cavities prior to and during oral implant placement. The tool includes a passive-depth gauge arm and an active spring caliper arm. The tool can be used to define the extraction socket for oral implant placement and allows measurement verifications after each step of the bone bed preparation prior to or during the actual implant placement in the extraction socket. There are multiple modifications of the primary design into separate embodiments to accommodate usage in different parts of the jaw and different points during the implant procedure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/779,443, filed Mar. 7, 2006. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention combines functions for measuring depth and width in one tool for use in oral implant placement. It can be used to measure the bone cavity either immediately after the tooth extraction or at later stages directly after initial preparation of the implant cavity. 
   2. Description of the Related Art 
   The replacement of lost teeth with oral implants has proven to be the preferable treatment option for many patients. Successful oral implants help prevent healthy oral structure loss while they rehabilitate the patient both functionally and esthetically. The correct three-dimensional selection and placement of oral implants is mandatory for predictable treatment outcomes. Misplacement of an oral implant can lead to severe or even life threatening consequences (e.g., Hemorrhagic swelling of the mouth floor after accidental damage of blood vessels). 
   Currently, diagnostics are mostly based on panoramic X-rays and plaster jaw models. Advanced diagnostics include the bone sounding procedure, bone mapping procedure, transversal cut X-rays, and different types of CT scans. Due to distortion and magnification, conventional panoramic X-rays provide limited information. Plaster models usually do not include the basic portion of the alveolar ridge into which the oral implants are placed. Preoperative bone sounding requires an additional use of local anesthetics and does not deliver adequate results related to the preparation of the implant bed. Although CT scans deliver correct three-dimensional data of the operational site, they expose the patient to a considerable amount of radiation. Although three-dimensional planning based on CT data is highly accurate, the transfer into the operational site remains difficult and work-intensive. Furthermore, all of the diagnostics listed above provide limited guidance during the implant procedure itself. 
   SUMMARY OF THE INVENTION 
   The use of the new tool offers a series of benefits to the dentist. First, it can be used to define the potential of the extraction socket for oral implant placement, leading to increased efficiencies during surgery. Second, it allows the dentist to check the situation after each step of the bone bed preparation during or prior to the actual implant placement in the extraction socket, increasing accuracy of placement. Third, dehiscences and fenestrations of oral or vestibular bone walls can be detected and the potential need and extent for Guided Bone Regeneration (GBR) procedures can be determined early, assuring better patient outcomes. The new tool is useful in immediate implant placement procedures, early implant placement procedures or late implant placement procedures. No matter which placement protocol is applied, the new tool is always quickly available, enabling more accurate placement without either additional X-ray exposure or the time taking one requires. Multiple embodiments of the primary measurement tool all aid the accuracy and efficiency of the surgical implant procedure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view of the straight embodiment shown with the tool in its closed and un-activated position. 
       FIG. 2  is a close-up of the closed and un-activated top of the straight embodiment. 
       FIG. 3  is the side view of the measurement device in its closed and un-activated position. 
       FIG. 4  is the side view of the straight embodiment in a partially open position. 
       FIG. 5  is an enlargement of the side view of the downward-angled embodiment in a closed position. 
       FIG. 6  is a detailed view of the joint of a downward-angled depth gauge. 
       FIG. 7  is an enlargement of the side view of the upward-angled embodiment in a closed position. 
       FIG. 8  is a detailed view of the joint of an upward-angled depth gauge. 
       FIG. 9  is a detailed view of a tapered gauge tip. 
       FIG. 10  is a front plan view of a double spring and single depth gauge embodiment. 
       FIG. 11  is an enlarged side view of the joint between the double spring and single depth gauge of an angled top embodiment having different angulations. 
       FIG. 12  is an enlarged side view of the joint between the double spring and single depth gauge of an angled top embodiment shown from the opposite side of  FIG. 11 . 
       FIG. 13  is a double-ended depth gauge in combination with a double-ended spring caliper. 
       FIG. 14  is a detailed, enlarged view of the double-ended depth gauge. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  represents the primary embodiment of the invention. The measurement tool  10  consists of a depth gauge  22  with a passive arm  20  and a spring caliper with an active arm  30 . The passive arm  20  of the depth gauge  22  has a flat or rounded top  70 . The depth gauge  22  has a scale  24 , preferably in millimeters, and originates at the body of the passive arm  20 . The depth gauge  22  may include a removable, spring caliper tip for easy replacement of the depth gauge when the tip wears down. The body of the passive arm  20  is curved at the bottom. The scaling  28  at the bottom is for the spring caliper function. The body of the passive arm  20  gives rise to a spring  26  which applies force to the active spring caliper arm  30  under the joint  40  between the passive and active arms to keep the spring caliper closed. The top of the active spring caliper arm  32  represents the mobile part of the spring caliper function. Its continuation under the joint  40  connects it to the passive arm  20  that is under pressure from the spring  26 . Toward the bottom, the active spring caliper arm  30  is twisted. At the bottom, split end  34  overlaps the width measurement scale  28  on the passive arm  20 . 
   The new tool has a variety of uses in oral implant surgery. The first use is extraction socket measurement immediately after extraction. It works by applying finger pressure to the active arm  30 , so the spring caliper function is no longer in contact with the tip of the depth gauge function. The depth gauge  22  is placed into the depth of the extraction socket until there is resistant bone at the extraction socket bottom. By releasing pressure from the active arm  30 , the spring of the passive arm forces the tip  32  of the spring caliper function back into the direction of the tip of the depth gauge function. The outside of the extraction socket&#39;s bone wall resists against this force. The distance between the tip of the depth gauge function and the tip of the spring caliper function can be read from the scale  28  of the spring caliper function, representing the width of the bone wall. After measuring bone width at the bottom of the socket, force is then reapplied to the active arm  30  in order to increase the distance between the tip of the depth gauge function and the tip of the spring caliper function. The depth gauge function is repeatedly lifted upwards to the desired extent to obtain additionally required measurements. The number of measurements required depends on the thickness of the patient&#39;s bone wall. Thin walls usually require more measurements than thick walls. Lastly, the bone width at the extraction socket top is measured in the described manner. The instrument is then turned and the opposite bone wall is measured accordingly. A “0” measurement at the extraction socket top that may or may not continue further down indicates a dehiscence. Any “0” measurement at any point below measured bone indicates a fenestration. 
   The second use is in implant bed preparation for measuring cavity depth and bone wall width. Measurement is highly recommended to evaluate the bony surrounding of the implant bed cavity. Even using advanced protocols involving CT data-derived surgical guides, it is necessary to check the accordance of the actual drilling compared to the prior virtual planning. Any bone formation changes that occur between the time the CT is taken and when the surgery is performed, can be instantly measured and identified using this tool. 
     FIG. 2  is an enlarged view of the top of the device. The cut top of the depth gauge includes a depth gauge measurement scale  24 , preferably in millimeters. A scale mark circles the depth gauge at intervals, such as every 2 millimeters, and may also include a measurement number for easier reading by the user of the device. The body of the depth gauge arm  20  is the origin of the spring  26  that applies force to the body of the spring caliper arm  30 . The depth gauge arm  20  and the spring caliper arm  30  are connected by a joint  40 . Force from the spring  26  against the spring caliper arm  30  results in the contact of the spring caliper arm tip  32  to the depth gauge arm tip  22 . 
     FIG. 3  is a two-dimensional side view of the measurement tool described in  FIG. 1 , with the measurement device in its closed and un-activated position. The spring caliper function width measurement scale  28  includes markings, preferably in millimeters. When measurement tool  10  is in the closed and un-activated position, the split end  34  rests at the stop at the end of passive arm  20 , giving a zero reading. 
     FIG. 4  shows the device  10  in a partially-open position. Any open position of the device requires force against the active spring caliper arm  30 . That force has to be larger than the force of the spring  26  that originates from the body of the passive arm  20 . Through this construction, the device remains closed when there is no external force applied to the device. The distance between the top of the depth gauge arm  22  and the top of the spring caliper arm  32  correlates with the position of the split end  34  of the active arm  30  on the scale  28  at the bottom of the passive arm  20 . 
     FIG. 5  represents an enlarged view of another embodiment of the invention. In this embodiment, the top of the device is downward-angled in the range of 60 to 90 degrees to facilitate its use in rear parts of the jaws, especially the lower-right jaw buccal bone walls, lower-left jaw lingual bone walls, upper-left jaw buccal bone walls and upper-right jaw palatal bone walls. The top of the passive arm  22  is angled at point  50  along with the top of the active arm  32  at point  60 . All other details remain similar to those described in  FIG. 1 . 
     FIG. 6  is an enlarged, two-dimensional side view of the top of the embodiment described in  FIG. 5 . The broken line indicates different degrees of angulation to include obtuse as well as acute angles. 
     FIG. 7  represents an enlarged view of another embodiment of the invention. In this embodiment, the top of the device is upward-angled in the range of 60 to 90 degrees to facilitate its use in rear parts of the jaws, especially the lower-right jaw lingual bone walls, lower-left jaw buccal bone walls, upper-left jaw palatal bone walls and upper-right jaw buccal bone walls. All other details remain similar to those described in  FIG. 1 . 
     FIG. 8  is an enlarged, two-dimensional side view of the top of the embodiment described in  FIG. 7 . The broken line indicates different degrees of angulation, to include obtuse as well as acute angles. 
     FIG. 9  is an enlarged view of an embodiment of the top of the depth gauge arm  22 . In this embodiment, the top  70  is rounded and extends over the zero mark of the scale. The purpose of this embodiment is to be in accordance to the bone cavity that is created through the use of a drill. Most pilot drills exhibit an apical excess length, meaning that the implant bed is deeper than the depth measured at the deepest point with the full diameter. The depth gauge  22  diameters range from 0.1 to 7 millimeters. 
     FIG. 10  represents another embodiment of the invention. It is the combination of one depth gauge function with two spring caliper functions used to allow measurements of oral and vestibular bone walls at the same time. The body of the depth gauge arm extends at the bottom into two directions and contains two spring caliper function width measurement scales  28  and  88 . The depth gauge arm  90  divides into two springs which apply force to the two active spring caliper arm bodies  30  and  80  under the joint  40 . This force results in the two spring caliper function tips  32  and  82  contacting the depth gauge function tip  22 . In this position, the split ends  34  and  84  of the spring caliper functions are at the zero mark of the corresponding scales  28  and  88 . The spring caliper function of the first spring caliper arm  30  and function tip  32  results in measurements on scale  28  independently of the measurements on scale  88  resulting from the spring caliper function of the second spring caliper arm  80  and function tip  82 . 
     FIGS. 11 and 12  represent the enlarged, two-dimensional views of the top of another embodiment shown from opposite sides. This embodiment differs from the embodiment described in  FIG. 10  because it is angled at point  62 . The broken line represents different degrees of angulation in the range of 60 to 90 degrees to include both acute and obtuse angles. The angled top facilitates using the device in rear parts of the patient&#39;s jaw. As seen by the side views, the top joint  40  controls the spring caliper function of the first spring caliper arm  30  and function tip  32  with respect to the depth gauge arm  90  having a divided spring. The bottom joint  42  controls the spring caliper function of the second spring caliper arm  80  and function tip  82  with respect to the depth gauge arm  90  having a divided spring. 
   The use of this tool is to measure oral bone wall width and vestibular bone wall width at the same time. It can be used in both extraction socket measurement and implant bed preparation. For certain regions of the jaw, this embodiment is a more efficient measuring tool, speeding the implant procedure. Angulations on the tool equivalent to earlier embodiments may be required to ensure efficient and accurate measurement. 
     FIG. 13  is the enlarged view of the top of another embodiment which consists of a double-ended depth gauge  104  in combination with a double-ended spring caliper  102 . The instrument is shown in a closed position where the double-ended depth gauge  104  and the double-ended spring caliper  102  are in contact. The origin  114  of the double-ended depth gauge  104  is the body of the depth gauge arm  20 . The origin  112  of the double-ended spring caliper  102  is the body of the spring caliper arm  30 . 
   Using all other embodiments, measurements are read from the scale(s)  28  (and  88 ). With this embodiment, bone width can be either measured by reading the scale  28  or by viewing a visual approximation demonstrated by the distance between the tip of the spring caliper function and the depth gauge outside of the bone. This embodiment is useful when the scale position that may result from jaw location is too awkward for easy viewing. 
     FIG. 14  represents the detailed, two-dimensional side view of the embodiment described in  FIG. 13 . The double-ended depth gauge  104  with its origin  114  is at the top of the depth gauge arm body  20 . The joint  40  connects the bodies of depth gauge arm  20  with the spring caliper arm  30 .