AU2018201058B2 - Dental Surgery Method - Google Patents

Abstract

EDITORIAL NOTE APPLICATION NUMBER - 2018201058 Please note: Abstract page 20 should be numbered 19. 20 ABSTRACT A method for preserving the alveolar ridge using partial extraction therapy. The method comprises de-coronating the tooth to leave a tooth root, de-coring a coronal portion of the tooth root to leave a tooth ring, severing an apical root portion of the tooth root from the tooth ring and removing the apical root portion. The tooth ring provides a ring of natural material that reinforces the coronal part of the tooth socket in the gum and reduces or obviates alveolar resorption. 37a 35 41 33 39 FIG. 11B FIG. 11B.1 FIG. 11C

Description

ABSTRACT A method for preserving the alveolar ridge using partial extraction therapy. The method comprises de-coronating the tooth to leave a tooth root, de-coring a coronal portion of the tooth root to leave a tooth ring, severing an apical root portion of the tooth root from the tooth ring and removing the apical root portion. The tooth ring provides a ring of natural material that reinforces the coronal part of the tooth socket in the gum and reduces or obviates alveolar resorption.

37a

35 41

33

39

FIG. 11B FIG. 11B.1

FIG. 11C

DENTAL SURGERY METHOD

TECHNICAL FIELD The present invention concerns a dental surgery method. The present method also relates to instruments for use in dental surgery.

BACKGROUNDART

Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

Tooth extraction is associated with dimensional changes of the alveolar ridge. Bone resorption can occur in both a horizontal and vertical direction. These resorptive changes can continue for the life of the patient.

Fixed crown and bridgework is often the treatment modality of choice for replacement of missing teeth. Crowns can be supported from implants inserted into the actual tooth socket following tooth extraction. Alternatively, bridges can be used whereby the crown used to replace the missing tooth or teeth is suspended from an adjacent natural tooth or an adjacent dental implant. This is called a "pontic" crown.

Removable dentures can also be used to replace a missing tooth or teeth. Patients generally prefer a fixed solution to replace missing teeth as it is more similar in function to natural teeth.

Continued resorption of bone and gum around fixed crown and bridgework can severely compromise the aesthetic outcome of dental treatment. As the gum shrinks away from the teeth interproximally, annoying food traps are created. This inevitable atrophy following tooth loss can be particularly destructive under removable dentures. Pain can occur as the denture impinges on a reduced soft tissue base and retention of this prosthesis can be diminished with time.

This resorption of hard and soft tissues is inevitable after tooth extraction using current extraction techniques. Over the years a number of different approaches have been undertaken to address this problem. The gold standard for many years has been the addition of de-proteinized bovine bone to or adjacent to the tooth socket to offset this resorptive process. Connective Tissue Grafts have also been used extensively to increase the gum thickness to disguise this atrophy.

A newer technique to combat this problem is the "Socket Shield" technique. The socket shield technique involves leaving a buccal root segment that remains in place to avoid resorption of buccal bone and gum. A dental implant is placed behind the buccal root and is used to affix a dental crown.

A variant of this technique known as the "Pontic Shield" technique can be used to preserve the alveolar ridge under a dental bridge. A pontic crown is suspended over the extraction socket with a retained portion of the buccal root.

The present inventor believes that the Socket Shield technique is difficult for the dentist to perform and traumatic for the patient since it typically involves cutting the tooth into sectors and then drilling and levering sectors behind the buccal root segment from the bone. Such operations are time consuming and may be traumatic for the patient; often there is inadvertent damage to the site for the implantation and to the surrounding gum tissue. Mobility of the shield can also result when the sectors are removed causing the procedure to be abandoned. Only the buccal bone is supported by the tooth root and not the palatal bone. This may lead to a future atrophy of the palatal bone and gum. Furthermore, depending on the tooth involved, it is difficult for the dental surgeon to ascertain the desired geometry for the buccal root segment. Infection can develop if this geometry is incorrect and the shield extends to close the root apex. Whilst the Socket Shield technique can be performed on front teeth, it is more difficult to perform on teeth toward the back of the jaw because of limited access and complicated root morphology.

Migration and or exposure of the shield can also occur during the provisional stage of treatment as the shield is not secured to the implant itself.

It is an objective of the present invention to provide a method and apparatus that addresses one or more of the above problems.

SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a dental surgical method at the site of a tooth comprising the steps of: de-coronating the tooth to leave a tooth root; de-coring a coronal portion of the tooth root to leave a tooth ring; severing an apical portion of the tooth root from the tooth ring; and removing the apical portion of the tooth root.

Throughout this specification, the term "coronal" will be used to refer to the portion of the tooth or tooth root that is located closer to the external surface of the gum and the term "apical" will be used to refer to the portion of the tooth or tooth root that is located deeper in the gum.

The method may include fixing an implant through the tooth ring into the bone. A crown can then be affixed to his implant to replace the missing tooth.

Alternatively, the tooth ring can serve as a foundation underneath a pontic crown or a removable denture to prevent or minimise resorption of the alveolar process.

The step of de-coronating the tooth involves removing the crown of the tooth. Preferably the step of de-coronating the tooth involves cutting into an exposed side of the tooth or about the tooth with a cutting tool and then levering the crown off the remainder of the tooth. It will be appreciated that any known technique for removing the crown of a tooth may be used in this step.

In a preferred embodiment of the invention the cutting about the tooth with the cutting tool is performed a little above a gum adjacent the tooth.

Preferably the method further includes applying a tool to the tooth root to reduce it below the gum line. For example, in the preferred embodiment of the present invention the tooth root is reduced about 2mm below the gum line to the level of the Junctional Epithelium or further in the case of periodontal disease.

In a preferred embodiment of the present invention the step of de-coring a coronal portion of the tooth root to leave the tooth ring involves enlarging a root canal of the tooth root. For example progressively larger Gates-Gliddon drills may be used to sequentially enlarge the root canal. Progressively larger drills may then be used to further enlarge the coronal portion of the root canal to a depth of 7mm.

In a preferred embodiment of the invention a bur is used to finally enlarge the coronal portion of the tooth root to thereby leave the tooth ring. Accordingly, preferred embodiments of this step of the present invention involve drilling into the coronal part of the tooth root to form a hole, such as an essentially circular hole, in the tooth root and then using a bur or other appropriate tool to remove additional material from the tooth root so that the coronal portion of the tooth root is reduced to a ring of tooth having a largely uniform or consistent wall thickness. Preferably the tooth ring has a wall thickness of 0.5mm to 1.0mm.

In embodiments where an implant is used, the ring of tooth will provide a shield for the implant.

In one embodiment, the step of removing part of the coronal portion of the tooth root to leave a tooth ring involves forming a hole in the tooth root to a desired depth, the hole having an essentially flat base, and using a bur or other tool to remove additional tooth material located laterally of the hole. The essentially flat base of the hole assists in locating a base part of the tool that is used to remove the lateral tooth material.

In one embodiment of the present invention, the step of severing the apical portion of the tooth root from the tooth ring includes making a peripheral opening through a lower part of the tooth ring to thereby remove a peripheral region of the tooth root to leave a coronal tooth ring and an apical tooth root. In one embodiment, the peripheral opening may be made through a base of a coronal flaring of the tooth root. In one embodiment, the peripheral opening may be made with a bur having a "T" profile wherein the edges of the cross bar of the "T" are formed to cut tooth material.

The peripheral opening that is used to sever the apical tooth root from the tooth ring may desirably have a height in the range of 1 mm to 3 mm.

Once the apical tooth root has been severed from the tooth ring, the apical tooth root may then be fully removed. In one embodiment, the step of removing the apical tooth root involves loosening the tooth root and then removing the tooth root from the socket or gum.

In one embodiment, the step of extracting the apical root portion of the tooth from the bone includes drilling a hole in the root portion and affixing an anchor (such as a post) therein. The post may then be coupled to an extraction mechanism whereby operation of the extraction mechanism causes the anchor to sufficiently tension the root portion to thereby detach it from the bone. For example, the withdrawal mechanism may comprise a line and pulley tool, such as a "Benex" (http://www.benex-dent.com/en/) or alternatively it may comprise a swiveling screw jack.

The step of loosening the apical tooth root may involve pulling the apical tooth root outwardly towards the gum. In embodiments where the step of severing the apical tooth root from the tooth ring involves forming a peripheral opening having a longitudinal length, a space or a gap is formed between the tooth ring and the severed apical tooth root. Pulling the apical tooth root towards the gum results in the apical tooth root being loosened from the tissues in the tooth socket. The apical tooth root can move into the space or gap towards the tooth ring, thereby facilitating loosening of the tooth root.

In some embodiments, the step of removing the apical portion of the tooth root includes withdrawing the detached apical root portion through the tooth ring in either a single piece or in sections.

In a preferred embodiment of the invention, where the detached root is too large to pass through a lumen or opening of the tooth ring, then the method may further include sectioning the detached root and withdrawing sections of the detached root through the lumen or opening of the tooth ring. Sectioning may be done using any suitable technique, such as with a long-shank surgical round bur on a high-torque water-cooled surgical handpiece. Alternatively, a saw tip, mounted on a piezo-electric handpiece, may be used to section the detached root.

In an alternative embodiment, the apical tooth root portion may be removed by surgical extraction through the gum and not through the lumen of the tooth ring. In this embodiment, it may not be necessary to loosen the apical tooth root prior to surgical extraction.

In embodiments where an implant is fixed into the tooth socket, the step of fixing the implant through the tooth ring into the bone may include positioning a crest of the implant slightly above the base of the tooth ring so that unobstructed access to the internal surface of the implant is provided.

In embodiments whereby the implant cannot be fixed to the tooth ring as the tooth ring is much larger than the implant diameter, prosthetic attachments connected to the implant can be used to engage the tooth ring.

According to a further aspect of the present invention there is provided a tooth root detachment instrument comprising: a lead screw including a screw portion about which an operative member, for example a nut, is threaded for translating the lead screw and a threaded point for screwing into the tooth root; a swiveling member having a bore traversed by the lead screw wherein the operative member captures the threaded portion on a coronal side of the swiveling member; and a platform for supporting the swiveling member including an opening for passage of the point therethrough.

Preferably the swiveling member includes a hemispherical portion. The swivelling mechanism or hemispherical portion is preferably made from a rigid material.

A coupling formation fast with the lead screw may be provided for applying rotation to the lead screw to thereby screw the point into the tooth root.

In a preferred embodiment of the invention the instrument includes a rotatable handle arranged to mate with the coupling formation whereby rotation of the rotatable handle is transmitted to the lead screw by means of the coupling formation.

In some embodiments, a thrust washer or a thrust bearing may be located between the operative member and the swivelling member such that rotation of the operative member does not cause rotation of the swivelling member.

The platform may be shaped for positioning over one of an anterior, posterior or canine tooth.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

Figures 1A, 1A.1 and 1B illustrate cutting into a side of a crown of a tooth, being a first stage in de-coronation of the tooth.

Figures 2A, 2B, 2B.1 illustrate the use of a lever to separate the crown from the remainder of the tooth to thereby leave a tooth root.

Figures 3A, 3A.1 and 3B illustrate the use of a bur to reduce the root below the gum line.

Figures 4 and 4.1 show the use of root canal files to enlarge the root canal.

Figures 5A to 5D show the use of progressively larger Gates-Gliddon drills to sequentially enlarge the canal.

Figures 6A, 6A.1 and 6B illustrate the use of a first diameter drill bit to further enlarge the coronal portion of the canal.

Figures 7A, 7A.1 and 7B illustrate the use of a second, larger diameter drill bit to further enlarge the coronal portion of the canal.

Figures 8A to 8C.1 illustrate the use of progressively larger diameter drill bits to further enlarge the coronal portion of the canal.

Figure 9A to 9D depict a custom-tapered bur and its use in milling-out the tooth root around the canal to leave a tooth ring at the coronal portion of the tooth.

Figures 10 and 10.1 show plan and sagittal cross sectional views of the tooth ring.

Figures 11A to 1IC show the use of a "T" shaped bur to sever the tooth root from the tooth ring.

Figures 12A, 12B and 12C show a situation in which the "T" shaped bur has not cut through all the way around the periphery of the tooth ring.

Figures 13A, 13A.1 and 13B illustrate the drilling of a hole in the severed apical tooth root.

Figures 14A to 14C illustrate the insertion of a post into the severed apical tooth root.

Figures 15A to 15B.1 illustrate the fixing of the post to a root extraction device.

Figure 16 and 16.1 show a root detached from the bone subsequent to operation of the root extraction device and removal of the post.

Figures 17A and 17B illustrate the sectioning of the detached apical root.

Figure 17B.1 illustrates the end of a piezo saw tool for sectioning the detached root.

Figure 17B.2 is a sagittal cross sectional view of the sectioned detached tooth.

Figures 18 and 18.1 illustrate the removal of the sectioned root through the lumen of the tooth ring.

Figure 19 shows the tooth ring left intact subsequent to removal of the sectioned root.

Figures 20 and 20.1 show the implant placed through the tooth ring and secured to the underlying bone.

Figure 21 depicts a root extraction instrument according to a preferred embodiment of an aspect of the present invention.

Figure 22 depicts a wrench for operating an operative member in the form of a nut of the root extraction instrument of Figure 21.

Figure 23 depicts a platform or "tray" of a root extraction instrument according to a further embodiment of the present invention.

Figure 24 depicts further trays for use of the tooth extraction instrument on anterior, posterior and canine teeth.

Figure 25 illustrates a further embodiment of the root extraction instrument including a height adjustable post.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A method for fixing a dental implant according to a preferred embodiment of the present invention will now be described. Initially, as illustrated in Figures 1A, 1A.1 and 1B, a side of the crown 3 of the tooth 1 is cut away or removed to form a recess 5 by means of a bur 7, such as a round bur or long-tapered bur driven by a high-torque, water-cooled, high-speed handpiece 9. The bur is used to cut the recess 5 into part of the outer periphery of the tooth, a little above the gum line.

With reference to Figures 2A, 2B, 2B.1 a crowbar 11, such as a Luxator or similar instrument, is used to snap the crown 3 from the tooth 1 to thereby leave a de coronated tooth la (as shown in Figure 3A).

Referring now to Figures 3A, 3A.1 and 3B, a large round diamond bur 13 is fitted to handpiece 9 and is then used to reduce the root 15 of the de-coronated root la to about 2mm below the gum line 17, or further in the case of periodontal disease.

As illustrated in Figures 4 and 4.1, a conventional root canal file 19 is then used to access the root canal system 21 of the tooth root la. Canal(s) can then be enlarged. Penetration control, by means of a stop 23, is suggested for abnormally short teeth or those in close proximity to the Inferior Alveolar Nerve in the mandible.

Referring now to Figures 5A-5D, Gates-Gliddon drills 25 can then be used sequentially to enlarge the canal(s) 21 further. Sizes 1, 3, 5 are usually sufficient for adequate enlargement.

A 1.5mm diameter drill bit 27 is next used to further enlarge the coronal portion of the canal to a depth of 7mm as shown in Figures 6A and 6B. A 2mm diameter drill bit 27 is then used to further enlarge the coronal portion of the canal to the depth of 7mm as shown in Figures 7A and 7B.

As illustrated in Figures 8A to 8C.1, sequentially larger drill bits 27 are then used to successively enlarge the coronal 7mm portion 28 of the canal 21 until minimum thickness of the tooth ring approaches 0.5mm to 1mm. At this stage, a generally circular hole 21A has been formed in the coronal portion of the tooth root. However, there remains a significant amount of tooth material left between the generally circular hole 21A and the outer periphery of the tooth. The next steps in the method of this embodiment of the present invention involve removing a significant proportion of that tooth material between the generally circular hole 21A and the periphery of the tooth such that a ring of tooth (or a tooth ring) is left, with the tooth ring having a largely uniform wall thickness around its periphery.

With reference to Figures 9A to 9D, a custom tapered bur with a flat non-cutting base 31 is applied at high torque and high speed (max 80,000 RPM) to continue enlargement of coronal portion 28 of the canal 21. The shape of the preparation should follow the anatomical outline of the de-coronated tooth la. Water-cooling is not essential at this point providing no perforations are made. The depth of this flaring vertically is performed to a depth of 7mm. For multi-rooted teeth, de-coring of the entire pulpal chamber using a tapered bur is the first step. The pulpal floor is removed in its entirety and the roots are then severed at the furcation level using the custom "T" bur. Care must be taken not to perforate the shield on multi-rooted teeth by careful observation of the root morphology. The shield that connects the tooth roots is where most perforations occur. For periodontally-affected molars, the bone may be apical to the furcation area. In this case, the roots can be prepared separately as with single rooted anterior teeth.

As illustrated in Figure 10 at the end of the application of the bur 31 a ring of tooth, i.e. tooth ring 33, is formed that will ultimately act as a shield to prevent resorption of bone. The wall thickness of the tooth ring 33 is roughly 0.5mm to 1.0mm in width. The tooth ring may have a height or depth that is around 7 mm, although variations from this measurement are possible. Essentially, the tooth ring 33 remains in the tooth socket and provides a surface of natural tooth material remaining in the gum that reinforces and strengthens the tooth socket.

With reference to Figures 11A to 1IC, using a long-shank, slow-speed custom "T" bur 35 in the water-cooled surgical handpiece 9, the apical portion of the root 37 is severed from the tooth ring 33. This is performed by positioning the "T" bur 35 at the base of the 7mm deep coronal flaring, i.e. at the base of the lumen of the tooth ring 33 and by moving the bur Into contact with and around the periphery of the internal wall of the tooth root to make a cut 41 through the internal wall of the tooth root la. The cut 41 defines a gap between the lower part of the tooth ring 33 and the upper part of the apical portion of the tooth root 37. The shank 39 needs to be kept hard against the walls to ensure maximum depth of cutting. The bur 35 may be 3mm in diameter and 2.5mm in height and is suitably configured for edge and top cutting only. The generally flat base of the opening in the coronal portion of the tooth root can be used as a guide for the base of the bur when cutting the peripheral opening.

If the custom "T" bur does not completely sever the root 37, further reduction is required to reduce the thickness of the walls. A clean dissection is characterised by bleeding bone and an obvious difference in colour. In the situation illustrated in Figures 12A to 12C, the "trough" 41A from the cut-off bur is clearly visible, however no perforation of the root has occurred. In this situation, the custom "T" bur is dragged coronally up the root to reduce the thickness of the walls (see Fig 12B and 12C). Then the custom "T" bur is positioned at the base of 7mm deep preparation and used in a centric motion to severe the root.

As shown in Figures 13A and 13B, a 1.5mm drill bit 45 is then used to drill a hole in the severed root 37 by following the root canal 21. It is preferable to follow the root canal to avoid the risk of perforation. A depth of 5 - 7mm is sufficient.

A 1.6mm diameter post 47 is then screwed into the severed root 37 by means of tool 48 as shown in Figures 14A - 14C.

The post 47 is then connected to a Benex or similar root extraction mechanism 46, as illustrated in Figures 15A (which shows placement of a support tray over the gum), 15B and 15B.1, to thereby extract the apical portion of the root 37 from the underlying bone as shown in Figure 15B.1.

With reference to Figure 16, the severed root 37 is then free to move up and down in a vertical motion. The post 47 is then removed by unscrewing it in an anti-clockwise direction. The severed root 37 will usually be too wide to pass through the lumen of the tooth ring 33, except in multi-rooted teeth. Therefore, as illustrated in Figures 17A and 17B, a surgical round bur on a high-torque, water-cooled surgical handpiece is then used to section the root into two pieces 49a, 49b. Alternatively and preferably, a piezo-electric cutting drill such as VS3-LED-HPSC, with a tip as illustrated in Figure 17B.1, may be used to section the detached root. This is performed at the isthmus. The root pieces 49a, 49b can then be removed through the lumen of the tooth ring 33 by means of forceps 51 or any other suitable tool as illustrated in Figures 18 and 18.1. As a consequence, the tooth ring 33 is left intact and is approximately 4- 5mm in height and 0.5-1mm in wall thickness as illustrated in Figure 19.

In one embodiment of the present invention an implant 53 (if required) is then inserted through the shield 33. The implant may derive stability by contacting the inside wall of the shield. It is preferable that the implant crest 55 extends slightly beyond the base 34 of the tooth ring 33 so that unobstructed access to the internal surface of the implant 53 is preserved. Figures 20 and 20.1 show a clinical view of an implant within a tooth ring.

Although the Benex cable and pulley root extraction mechanism that has been described has been found satisfactory with anterior teeth, the Inventor has found that a smaller device, which can be more readily manoeuvred in relation to the back teeth, would be preferable.

Referring now to Figure 21 there is depicted a root withdrawal apparatus 56 according to a preferred embodiment of an aspect of the present invention. Apparatus 56 includes a platform in the form of a tray 57 that locates over the gum and which has a central opening 75 with arcuate sides 77 that supports a corresponding hemispherical swivel 59 having a central bore 60 formed therethrough.

A lead screw 65 is provided having a threaded portion 67 that passes through the central bore 60 and which is captured by an operative member in the form of a nut 61. The threaded portion 67 terminates in a hexagonal coupling protrusion 63 that is received into a complementary recess 72 of a rotary handle 71.

An inner end of the lead screw 65 terminates in a threaded point 69 that in use is screwed into a canal of a tooth root 49 by rotation of the handle 71. Once the threaded point 69 has been sufficiently screwed into the root 49 the handle 71 is removed. A spanner 73 is then placed over the nut 61 and used to rotate the nut 61 relative to the threaded portion 67 of the lead screw 65. The action of tightening the nut 61 causes its lower face to self-align with the upper surface of hemispherical swivel 59 in the hemispherical tray 57. This results in no bending moment being applied to lead screw 65. Thus the lead screw 65 is translated away from the bone to which the root 49 is attached so that the root 49 is extracted from the underlying bone.

In the embodiment shown in figure 21, the nut 61 rests directly on the hemispherical swivel 59. When the nut 61 is rotated to withdraw the lead screw 65, as the nut 61 is in contact with the hemispherical swivel 59, there is a risk that a rotational movement will be applied to the hemispherical swivel 59 or to the lead screw 65. In order to minimise or avoid rotation of the hemispherical swivel 59 or the lead screw 65, a thrust bearing (not shown) may be placed between the nut 61 and the hemispherical swivel 59. Rotation of the nut will then cause rotation of the thrust bearing, but there will be no rotation of the surface of the thrust bearing that is in contact with the hemispherical swivel 59.

Tray 57 may be provided in various configurations to accommodate different positions in the mouth. For example, Figure 23 depicts a platform 57a that is designed to be used with molar teeth. Figure 24 illustrates trays 57a, 57b and 57c, each having different shapes that are for use with posterior, anterior and canine teeth of the patient. Figure 25 illustrates how a post 74 with an adjustable foot 75 may be provided to assist in supporting the tray where it is partially positioned over a toothless area of gum.

The Inventor believes that the extraction tool 56 may be made sufficiently compact to be used in relation to posterior teeth where line and pulley extraction tools such as the Benex may be difficult to utilise.

The Inventor has found that embodiments of the previously described method for placement of dental implants may be practiced quickly so that the time that the patient is subjected to the procedure is relatively brief. Furthermore, the step of making the tooth ring and then subsequently withdrawing the extracted root through the ring addresses the difficulties that have been previously described in relation to the Socket Shield and Pontic Shield technique. Namely, it is not necessary to lever sectioned tooth from the bone and the difficulty of leaving a buccal root segment is avoided.

The present inventor believes that leaving the tooth ring in the gum socket will reduce or prevent alveolar resorption over time. In particular, the tooth ring provides a ring of natural tooth material in the gum socket. This reinforces the coronal part of the gum socket. Further, resorption is likely to be minimised as the tooth material is a natural material of the body.

Embodiments of the present invention also involve significantly less trauma to the gum socket then the "Socket Shield" technique. This results in less pain and discomfort to the patient and to a quicker recovery time from surgery.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term "comprises" and its variations, such as "comprising" and "comprised of' are used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described herein comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims (19)

The claims defining the invention are as follows:

1. A dental surgical method for a tooth, the dental surgical method comprising:

de-coronating the tooth to leave a tooth root;

de-coring a coronal portion of the tooth root to leave a decoronated tooth root portion;

severing an apical root portion from the decoronated tooth root portion to leave a ring shaped portion of the tooth root and a gap between a lower end of the ring-shaped portion of the tooth root and an upper end of the apical root portion;

and

removing the apical root portion through a lumen at a center of the ring-shaped portion of the tooth root.

2. A method according to claim 1, including fixing an implant through the ring-shaped portion of the tooth root into the bone for a dental implant crown procedure.

3. A method according to claim 1 or claim 2, wherein de-coronating the tooth involves cutting into a side of the tooth with a cutting tool and then levering a crown off to form the decoronated tooth root portion.

4. A method according to claim 3, wherein the cutting about the tooth with the cutting tool is performed a little above a gum adjacent the tooth.

5. A method according to claim 4, wherein the tooth root is reduced about 2mm below the gum line.

6. A method according to any one of the preceding claims, wherein de-coring the coronal portion of the tooth root to leave the decoronated tooth root portion involves enlarging a coronal portion of a root canal of the tooth root.

7. A method according to claim 6, wherein the enlarging is performed by application of progressively larger Gates-Gliddon drills to sequentially enlarge the root canal.

8. A method according to claim 7, wherein progressively larger drills are used subsequent to application of the Gates-Glidden drills to further enlarge the root canal.

9. A method according to any one of the preceding claims wherein a bur is used to enlarge the coronal portion of the tooth root to thereby leave the ring-shaped portion of the tooth root.

10. A method according to any one of the preceding claims, wherein the ring-shaped portion of the tooth root has a wall thickness of 0.5mm to 1.0mm.

11. A method according to any one of the preceding claims wherein severing the apical root portion from the decoronated tooth root portion includes making a peripheral opening through a base of a coronal hole.

12. A method according to claim 11, wherein the peripheral opening is made with a bur having a "T" profile wherein edges of a cross bar of the "T" are formed to cut tooth material.

13. A method according to any one of the preceding claims, further including loosening the apical root portion following severing of the apical root portion.

14. A method as claimed in claim 13 wherein the step of loosening the apical tooth root includes drilling a hole in the apical root portion and affixing an anchor therein.

15. A method according to claim 14, wherein the anchor is coupled to an extraction mechanism whereby operation of the extraction mechanism causes the anchor to tension the apical root portion to thereby detach it from the bone.

16. A method according to claim 15, wherein the extraction mechanism comprises one of a line and pulley tool and a swiveling screw jack.

17. A method according to any one of the preceding claims wherein removing the apical root portion comprises withdrawing sections through the lumen at the centre of the ring shaped portion of the tooth root, sectioning the apical root portion and withdrawing sections of the apical root portion through the lumen at the centre of the ring-shaped portion of the tooth root.

18. A method according to any one of the preceding claims,, including fixing an implant through the ring-shaped portion of the tooth root into a bone to thereby facilitate a dental implant crown procedure, wherein fixing the implant through the ring-shaped portion of the tooth root into the bone includes positioning a crest adjacent to the ring-shaped portion of the tooth root to provide unobstructed access to an internal surface of the implant.

19. A method according to any one of the preceding claims, wherein the ring-shaped portion of the tooth root is left submerged in the gum to preserve an alveolar ridge.