U.S. patent application number 11/016635 was filed with the patent office on 2005-05-12 for dental implants and dental implant/prosthetic tooth systems.
Invention is credited to Elian, Nicholas.
Application Number | 20050100864 11/016635 |
Document ID | / |
Family ID | 23911075 |
Filed Date | 2005-05-12 |
United States Patent
Application |
20050100864 |
Kind Code |
A1 |
Elian, Nicholas |
May 12, 2005 |
Dental implants and dental implant/prosthetic tooth systems
Abstract
A one-piece dental implant having a longitudinal axis comprises
a head portion at a first end of the implant, a tip portion at a
second end of the implant and a body portion between the head
portion and the tip portion. The body portion has a first portion
proximate the head portion with a plurality of longitudinal grooves
substantially parallel to the longitudinal axis and a second
portion proximate the tip portion having a substantially
circumferential groove, wherein the outer diameter of the first
portion is greater than the outer diameter of the second portion.
The first and second portions are for being embedded in the jaw
bone. The dental implant is preferably dimensioned to conform to
the natural shape of the cervical 1/3 of the root of the tooth
being replaced, and to the natural relationship between the
cemento-enamel junction of the tooth being replaced and to minimize
adverse immunological responses by the jaw bone during healing,
thereby improving the aesthetic appearance of the implant and
prosthetic tooth attached thereto. A dental implant and prosthetic
tooth system is also disclosed, wherein the prosthetic tooth
conforms to the shape of the cervical 1/3 of the crown of the tooth
being replaced. A method for implanting a dental implant through
use of a reference, is also disclosed.
Inventors: |
Elian, Nicholas; (New York,
NY) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
23911075 |
Appl. No.: |
11/016635 |
Filed: |
December 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11016635 |
Dec 17, 2004 |
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09481212 |
Jan 11, 2000 |
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6854972 |
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Current U.S.
Class: |
433/173 |
Current CPC
Class: |
A61C 8/0012 20130101;
A61C 8/0022 20130101; A61C 8/0006 20130101; A61C 8/0077 20130101;
A61C 8/0018 20130101; A61C 8/0013 20130101 |
Class at
Publication: |
433/173 |
International
Class: |
A61C 008/00 |
Claims
1-30. (canceled)
31. A method of inserting a dental implant into the jaw bone of a
patient, the dental implant having a head portion with a side wall
and a reference on the side wall for positioning the dental implant
in the jaw bone, the method comprising: forming an opening in the
jaw bone of the patient for receiving the dental implant; and
inserting the dental implant into the opening such that the
reference is properly positioned with respect to the bone
crest.
33. The method of claim 31, wherein the head portion has a top
surface and at least one longitudinal groove extending into the
head portion, an end of the at least one longitudinal groove in the
head portion providing the reference, the method comprising
inserting the dental implant into the opening such that the end of
the at least one longitudinal groove is positioned at or slightly
below the bone crest and the top surface is above the bone
crest.
34. The method of claim 31, wherein the head portion has a top
surface and a side wall, a portion of the side wall distanced from
the top surface being surface treated, the method comprising
inserting the dental implant such that an end of the surface
treatment proximate the top surface is at or slightly below the
bone crest and the top surface is above the bone crest.
35. (canceled)
36. The method of claim 31, wherein the step of inserting the
dental implant comprises positioning the reference at or slightly
below the bone crest of the jaw bone.
37. The method of claim 36, wherein the reference is a longitudinal
groove or a surface treatment of a portion of the dental
implant.
38. The method of claim 36, wherein the head portion has a top
surface and wherein at least a portion of the contour of the top
surface substantially matches the shape of the cemento-enamel
junction of a tooth being replaced, and wherein the step of
inserting the dental implant comprises positioning the top surface
proximate the location of the cemento-enamel junction corresponding
to the tooth to be replaced.
39. The method of claim 36, wherein the head portion has a top
surface, the top surface having a circumference substantially
matching the circumference of the tooth to be replaced, proximate
the cemento-enamel junction of the tooth being replaced, and
wherein the step of inserting the dental implant comprises
positioning the top surface proximate the location of the
cemento-enamel junction corresponding to the tooth to be
replaced.
40. The method of claim 36, wherein the head portion has a side
wall having a shape substantially matching the shape of the
cervical {fraction (1/3)} of the root of the tooth being
replaced.
41. The method of claim 36, wherein the top surface of the head
portion has a surface contour substantially following the shape of
the cemento-enamel junction of the tooth being replaced, at least
at the portions of the implant corresponding to the buccal and
inter-proximal portions of the implant.
42. The method of claim 31, wherein the outer diameter of the
dental implant is tapered in the direction extending perpendicular
to the head portion.
43. The method of claim 31, further comprising attaching a
prosthetic tooth to the dental implant.
44. A method of implanting a dental implant in a jawbone of a
patient to replace a tooth, the dental implant having a contoured
top surface, the method comprising: forming an opening in the
jawbone; and positioning the dental implant in the opening, wherein
at least a portion of the contoured top surface is located
proximate the cemento-enamel junction of the tooth being replaced,
and wherein at least a portion of the contoured top surface
substantially matches the shape of the cemento-enamel junction of
the tooth being replaced.
45. The method of claim 44, wherein the dental implant has a side
wall with a reference, and wherein the step of positioning the
dental implant comprises positioning the reference at or slightly
below the bone crest of the jaw bone.
46. The method of claim 44, wherein the reference is a longitudinal
groove or a surface treatment of a portion of the side wall.
47. The method of claim 44, wherein the step of positioning the
dental implant comprises positioning an apical tip of the dental
implant in contact with an inner surface of the inner cortical bone
of the jaw bone.
48. The method of claim 44, wherein the contoured top surface has a
circumference substantially matching the circumference of the tooth
being replaced proximate the cemento-enamel junction of the tooth
being replaced.
49. The method of claim 44, wherein portions of the contoured top
surface corresponding to the mid-buccal to mid-interproximal
portions of the implant substantially follow the shape of the
cemento-enamel junction of the tooth being replaced.
50. The method of claim 44, wherein the dental implant has a side
wall, and wherein at least a portion of the shape of the side wall
substantially follows the shape of the outer surface of the
cervical {fraction (1/3)} of the root of the tooth being
replaced.
51. The method of claim 44, wherein the outer diameter of the
dental implant is tapered.
52. The method of claim 44, further comprising attaching a
prosthetic tooth to the dental implant.
53. The method of claim 44 further comprising the step of
determining an appropriately dimensioned dental implant.
54. The method of claim 53 wherein the step of determining
comprises: measuring the dimensions of the tooth being replaced,
taking an impression of the tooth being replaced, or approximating
based on an analysis of adjacent teeth and the height and width of
the face of the patient.
55. A method of inserting a dental implant into a jaw bone, the
dental implant having a contoured top surface wherein at least a
portion of the contoured top surface substantially matches the
shape of the cemento-enamel junction of a tooth being replaced, a
side wall, and a reference on the side wall, the method comprising:
forming an opening in the jaw bone; and positioning the dental
implant in the opening with the reference positioned at or slightly
below the bone crest of the jaw bone and the at least a portion of
the contoured top surface positioned proximate the cemento-enamel
junction of the tooth being replaced.
Description
BACKGROUND OF THE INVENTION
[0001] Dental implants are inserted into the base of the jaw and
have a portion protruding through the mucous gum tissue for
providing attachment anchorage for artificial teeth. An artificial
tooth may be attached directly to the implant, or to an abutment
connected to the implant. Dental implants are becoming increasingly
popular alternatives to dentures.
[0002] Dental implants have been used in the hard bone of the lower
jaw with great success. The upper jaw bone, however, is very soft
and it is common for dental implants in the upper jaw to lack
primary stability.
[0003] There are three major types of dental implants: 1)
press-fit; 2) self-tapping; and 3) pre-tapping. The press-fit type
implants are inserted into holes drilled into the bone without
rotation. Press-fit implants do not couple tightly to the soft bone
of the upper jaw.
[0004] Self-tapping and pre-tapping type implants have horizontal
threads for being screwed into holes drilled into the jaw-bone, for
better mechanical coupling to the jaw bone. Self-tapping implants
create grooves in the hole as the implant is screwed in. Prior to
the insertion of pre-tapped implants, a tool is used to form
threads in the hole. While screwing self-tapping and pretapping
implants into the bone generally improves the mechanical coupling
between the implant and bone, it has been found that in the soft
bone of the upper jaw, the rotation of both the self-tapping and
pre-tapping implants may destroy the grooves, preventing tight
coupling between the implant and the bone.
[0005] After insertion of the implant, a sufficient period of time
must be given for the tissue to heal and for the bone to grow
sufficiently around (and sometimes through) the implant for the
dental implant to become securely engaged in the jaw. This
typically requires about three months. An artificial tooth is then
attached to the implant, directly or by attachment to an abutment
attached to the implant.
[0006] Primary stability, osteointegration and the aesthetic
appearance of the implant and prosthetic tooth in the mouth are
important considerations in the design of a dental implant.
Mechanical solutions to achieving primary stability and
osteointegration have generally ignored the natural shapes of the
root and crown of the natural tooth being replaced and have not
conformed to the natural relationship between the tooth and the jaw
bone, resulting in adverse immunological responses by the jaw bone
which both weakens primary stability and osteointegration, and
sacrifices aesthetics.
[0007] FIG. 1 shows two adjacent natural adult teeth 100, in the
upper jaw. A tooth 100 has a crown and a root. The crown may be
divided into a cervical {fraction (1/3)}, a middle {fraction (1/3)}
and an incisal {fraction (1/3)}. The root may be divided into a
cervical {fraction (1/3)}, a middle {fraction (1/3)} and an apical
{fraction (1/3)}. The interface between the cervical {fraction
(1/3)} of the tooth and the cervical {fraction (1/3)} of the root
is referred to as the cemento-enamel junction. It has been observed
that in a natural tooth, the distance d3 between the cemento-enamel
junction 104 and the crest 102 of the jaw bone is typically about
1.8 mm and the distance d4 between the crest 102 of the jaw bone
and the gingival margin 108 is typically about 3 mm.
[0008] Adverse immunological responses may be caused by a variety
of stimuli. For example, it has been found that the failure of
interface between the dental implant and the prosthetic tooth to
conform to the shape and location of the cemento-enamel junction
between the crown and root of the tooth being replaced causes an
adverse immunological response by the bone to the dental implant,
resulting in bone resorbtion. This can weaken the bond between the
implant and the bone and leave pockets which can collect plaque. In
addition, since a constant distance is naturally maintained between
the bone crest and the gingival margin, as the bone resorbs, the
gingival margin recesses, presenting an unpleasant aesthetic
appearance.
[0009] Another cause of adverse immunological responses in the
jawbone are microgaps between the dental implant, whose top surface
is typically positioned at or below the bone crest, and the
abutment attached to the implant. Once again, bone resorbtion and
gingival margin recession may result.
[0010] Some dental implants, such as the ITI(R) implants from the
Straumann Company, Waltham, Mass., position the top surface of the
implant above the bone crest. The jaw bone is not, therefore,
exposed to microgaps between the implant and an abutment,
decreasing adverse immunological responses. However, the flat tops
of these implants do not match the shape of the cemento-enamel
junction of the natural tooth being replaced. Bone resorbtion and
the resulting recession of the gingival margin still occur,
particularly interproximally.
[0011] Dental implants are also typically cylindrical. However,
teeth are not so regularly shaped. While attempts have been made to
conform the abutment and the prosthetic tooth to the natural shape
of the cervical {fraction (1/3)} of the root and the cervical
{fraction (1/3)} of the crown of the tooth being replaced, the
unnatural shape of the dental implant limits how closely the
natural shape of the root and crown can be recreated. Voids are
therefore present between the dental implant and the bone of the
jaw, and between the prosthetic tooth and the gingivus, which can
allow for the growth of soft tissue and the collection of plaque.
Such soft tissue may interfere with the osteointegration of the
implant, resulting in implant failure. Attempts have been made to
prevent soft tissue growth by filling the gaps between the implant
and the jaw bone by artificial bone or by covering the interface
between the gums and the implant with a membrane. Such designs have
an increased risk of infection and lack osteointegration. Rotation
of the implant, either during rotation of the implant to insert the
implant into the jaw bone or after final positioning of the
implant, also interferes with attempts to close such gaps.
SUMMARY OF THE INVENTION
[0012] In one aspect of the invention, a dental implant has both
longitudinal and vertical grooves for improved primary stability
and osteointegration. In other aspects of the invention, a dental
implant and a dental implant/prosthetic tooth system substantially
conforms to the natural relationships and shapes of the tooth being
replaced. In particular, a dental implant is shaped and dimensioned
to substantially conform to the natural biological relationship
between the bone crest and the cemento-enamel junction. The
gingival margin is therefore maintained. The preferred dental
implant combines these aspects of the invention.
[0013] A one-piece dental implant is disclosed having a
longitudinal axis comprising a head portion at a first end of the
implant, a tip portion at a second end of the implant and a body
portion between the head portion and the tip portion. The body
portion has a first portion proximate the head portion with at
least one longitudinal groove substantially parallel to the
longitudinal axis and a second portion proximate the tip portion
having a substantially circumferential groove or threads.
Preferably, a plurality of longitudinal grooves are provided. The
outer diameter of the first portion is greater than the outer
diameter of the second portion. The first and second portions are
embedded in the jaw bone. The longitudinal grooves of the implant
are received in longitudinal grooves formed in the opening made in
the jaw bone for receiving the implant, preventing rotation of the
implant during placement and healing. During healing, the jaw bone
grows into the circumferential groove, securing the implant in the
jaw bone. The circumferential groove may be a spiral thread which
circles the body portion a plurality of times, or a plurality of
parallel grooves substantially perpendicular to the longitudinal
axis.
[0014] In another embodiment of the embodiment of the invention, a
dental implant is disclosed having a head portion. The head portion
has a top surface with a circumference substantially matching the
circumference of the tooth to be replaced, at the cemento-enamel
junction of the tooth being replaced.
[0015] In another embodiment of the embodiment of the invention, a
dental implant is provided having a buccal side for being aligned
with the buccal side of the jaw bone, a lingual side for being
aligned with a lingual side of the jaw bone and interproximal sides
between the buccal and lingual sides. The height of the top portion
of the dental implant is less on the buccal side of the implant and
rises toward the interproximal sides of the implant, as does the
cemento-enamel junction. The height of the top portion may decrease
from the interproximal sides of the implant to the lingual side, as
well.
[0016] In another embodiment of the invention, a dental implant and
prosthetic tooth system is disclosed,.wherein the height of the top
portion of the dental implant is less on the buccal side of the
implant and rises toward the interproximal sides of the implant.
The prosthetic tooth has a portion having a shape substantially
matching the shape of the cervical {fraction (1/3)} of the crown of
the tooth being replaced. The height of the top portion may
decrease from the interproximal sides of the implant to the lingual
side.
[0017] In another embodiment of the invention, a dental implant and
prosthetic tooth system is disclosed comprising a dental implant
having a head portion, a tip portion and a body portion between the
head portion and the tip portion. The head portion has a top
surface with a circumference substantially matching the
circumference of the tooth being replaced, at about the
cemento-enamel junction of the tooth being replaced. A prosthetic
tooth for being attached to the top surface of the implant has a
shape substantially matching the shape of the cervical {fraction
(1/3)} of the tooth being replaced.
[0018] In another embodiment of the invention, a method of
implanting a dental implant is disclosed wherein a reference
provided on the implant is used to properly position the implant in
the jaw bone. The reference can be defined by the ends of
longitudinal grooves extending into the head of the implant, or by
the end of the surface treated portion of the head of the implant,
which is positioned at or slightly below the bone crest.
Preferably, the head portion of the implant is positioned above the
bone crest after implantation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a view of two adjacent teeth of the upper jaw;
[0020] FIG. 2 is a side view of the buccal side of a dental implant
in accordance with one embodiment of the present invention;
[0021] FIG. 3 is a side view of the proximal side of the dental
implant of FIG. 1;
[0022] FIGS. 4a and 4b are side views of the buccal side and
proximal side of an alternative configuration for the dental
implant of the present invention.
[0023] FIGS. 5a-5c are plan views of the top surfaces of the dental
implants of showing preferred shapes for supporting a molar, a
premolar and an anterior incisor, respectively;
[0024] FIGS. 6a-6f are a series of saggital cross-sectional views
of the upper jaw, illustrating a method of inserting the dental
implant of FIG. 1 into the upper jawbone in accordance with the
present invention;
[0025] FIG. 7a and FIG. 7b are side views of osteotomes for use in
the process of the present invention;
[0026] FIG. 8 is a front view of the upper jaw bone with the dental
implant of the present invention positioned therein;
[0027] FIG. 9 is a side view of the proximal side of another
implant in accordance with the present invention;
[0028] FIGS. 10a-10c illustrate various steps in the method of
inserting the dental implant in the upper jawbone to replace a
tooth to be extracted in accordance with the present invention;
and
[0029] FIGS. 11a and 11b are side views of the buccal and proximal
sides, respectively, of a dental implant with a head portion which
is longer than in the configuration of FIGS. 4a and 4b.
DETAILED DESCRIPTION OF THE INVENTION
[0030] FIG. 2 is a side view of the buccal side of a dental implant
10 in accordance with one embodiment of the present invention. FIG.
3 is a side view of the proximal side of the dental implant 10 of
FIG. 2. The dental implant 10 is preferably a single piece with a
head portion 12, a body portion 14 and a tip portion 16, extending
along a longitudinal axis "L".
[0031] The body portion is cylindrical and includes a first section
18 with a plurality of longitudinal grooves 20 substantially
parallel to the longitudinal axis L of the implant 10, proximate
the head portion 12. Preferably, at least some of the longitudinal
grooves 20 extend into the head portion 12. The depth of each
groove 20 may be about 1 mm. The outer diameter of the first
section is preferably from about 3.75 mm to about 5.00 mm depending
on the type of tooth being replaced and the position of the tooth
in the mouth.
[0032] The cylindrical body portion 14 includes a second section 22
with a circumferential spiral thread 24. Preferably, the spiral
thread 24 encircles the second section 22 of the body portion 14 a
plurality of times. Alteratively, a plurality of parallel
circumferential grooves can be provided. Such parallel grooves can
be perpendicular to the longitudinal axis L of the implant or they
may be at a slight angle from perpendicular. The circumferential
thread 24 or grooves may be rough or serrated. The outer diameter
of the horizontal thread 24 or grooves of the second section 22 is
less than the outer diameter of the vertical grooves 20 of the
first section 18.
[0033] A narrow flat walled section 26 is preferably provided
between the first section 18 and the second section 22 to separate
the first and second sections, easing manufacture of the implant
10. The outer diameter of the flat walled section 26 is preferably
about the same as the outer diameter of the second section 22.
[0034] The head portion 12 has an outwardly flaring side wall and a
top surface 28 including a hex 30 for attachment of an artificial
tooth. The edge 30a between the top surface 28 and the hex 30
preferably has a chamfer-like finish so that the edge 30a is
curved. An internal hex may also be provided through the top
surface of the implant, as is known in the art. Other attachment
mechanisms may be used, as well. The portion of the head portion 12
between the longitudinal grooves and the top surface 28 is
preferably polished to provide a smooth surface which inhibits the
collection of bacteria.
[0035] The extent of the outward flare of the head portion 12 is
sufficient to close the opening formed in the jaw bone for
receiving the implant, as described further, below. In addition,
the shape of the side wall of the head portion 12 preferably
substantially matches the shape of the cervical {fraction (1/3)} of
the root of the natural tooth being replaced. The shape of the root
of the natural tooth may be determined through a CAT and clinical
measurements scan prior to extraction of the tooth, as is known in
the art. If the natural tooth is not present, then the shape of the
root may be approximated by analysis of adjacent teeth by CAT scan
and/or clinical measurements, which is also known in the art.
[0036] The distance "d1" from the terminus of the body portion 14
to the top surface 28 is preferably less at the buccal side of the
implant and rises toward the interproximal side of the implant, as
shown in FIG. 2. More preferably, the surface contour of the top
surface substantially matches the shape of the cemento-enamel
junction of the tooth being replaced, at least from the mid-buccal
portion to the mid-interproximal portion of the implant 10, as
shown in FIG. 8.
[0037] Returning to FIGS. 2 and 3, as mentioned above, it is
preferred that the longitudinal grooves 20 extend into the head
portion 12 of the dental implant 10. During implantation, described
further below, it is preferred that the ends of the longitudinal
grooves be positioned at or slightly below the bone crest, to help
maintain natural bone morphology during healing. The ends of the
longitudinal grooves 20 can be up to about 0.5 mm below the bone
crest to obtain this advantage. In addition the top of the
longitudinal grooves 20 in this embodiment provide a reference
position for the practitioner to know when the implant has been
sufficiently inserted. In the insertion of prior art implants, it
is difficult to precisely position the implant, resulting in
penetration of the sinus cavities.
[0038] The distance "d2" between the end of each groove 20 within
the head portion 12 and the top surface 28 of the implant 10 is
preferably constant. For a typical implant, 1.80 mm, which is the
natural distance from the crest 102 of the jawbone to the
cemento-enamel junction 104 in an adult tooth, is the preferred
distance d2. (See FIGS. 2 and 3). The top surface 28 of the implant
is then positioned approximately at the location of cemento-enamel
junction of the tooth being replaced.
[0039] The shape of the circumference of the top surface 28 of the
head portion 12 also preferably substantially matches the
circumference of a cross-section the natural tooth at the
cemento-enamel junction of the natural tooth. FIGS. 5a, 5b and 5c,
are plan views of the top surfaces 28 of three head portions of
three dental implants, showing the preferred shapes for supporting
a molar, a premolar and an incisor, respectively.
[0040] Returning to FIGS. 2 and 3, the tip portion 16 of the
implant 10 preferably includes a hole 32 extending therethrough.
Preferably, the hole 32 extends completely through the tip portion
16, but that is not required. The surface of the tip portion 16 is
preferably roughened. The tip portion preferably has a slight
inward taper from the end of the body portion to the tip 17 of the
implant 10, as shown in FIGS. 2 and 3.
[0041] The dental implant 10 is preferably made of titanium in
accordance with known manufacturing techniques. Other biocompatible
materials used as dental implants may be used, as well.
[0042] FIGS. 4a and 4b are side views of an alternative
configuration of a dental implant 10a, wherein the longitudinal
grooves 20 do not extend into the head portion. Instead, a lower
portion of the head portion 12a, below line X in the implant 10a,
is surface treated by acid etching, sand blasting with large grit
and acid etching ("SLA"), titanium plasma sprayed ("TPS") or
blasted with hydroxyapetite ("HA"), as is known in the art, to
improve bone integration with the implant 10. As above, the upper
portion of the head 12b, above line X in FIGS. 4a and 4b, is
preferably polished to provide a smooth surface which inhibits the
collection of bacteria. The interface between the upper portion of
the head 12b and the lower portion 12a is preferably positioned at
or slightly below the bone crest and provides a reference position
for placement of the dental implant 10a. The distance from line X
to the top surface 28 is also preferably a constant 1.80 mm. The
remainder of the implant 10a is the same as the implant 10 in FIGS.
2 and 3.
[0043] FIGS. 6a-6h are a series of saggital cross-sectional views
of the upperjaw 50 of a patient, illustrating a method of inserting
the dental implant 10 into the upper jawbone, in accordance with
the present invention. The gums 52, an outer layer of cortical bone
54a, an inner layer of the cortical bone 54b, a portion of
trabecular bone 56 and a sinus cavity 58 are shown.
[0044] An implant drill with a round tip is used to penetrate the
outer layer of cortical bone 54a, as shown in FIG. 6a. A 2 mm twist
drill 60 is then used to penetrate through the trabecular bone 56,
to the inner layer of cortical bone 54b, as shown in FIG. 6b,
forming an opening. A 3 mm twist drill 66 is then used to widen the
opening created by the 2 mm twist drill 64, as shown in FIG.
6c.
[0045] A profiling instrument, or osteotome 68, is then used to
shape the opening, as shown in FIG. 6d. Two osteotomes 68a, 68b are
shown in FIGS. 7a and 7b, as well. The osteotome 68a is for the
implantation of dental implants for supporting molar type
prosthetic teeth. The osteotome 68b is for the implantation of
dental implants for supporting anterior and pre-molar type
prosthetic teeth. The osteotomes 68a and 68b include a body portion
with longitudinal grooves 70 substantially matching the
longitudinal grooves 20 of the dental implant 10 to be inserted
into the opening. The outer diameter and the depth of the
longitudinal grooves 70 of the osteotome 68a, 68b are slightly
smaller than that of the longitudinal grooves 20 of the dental
implant 10, so that the implant will fit tightly in the opening,
improving primary stability. The depth of the grooves 70 is
preferably about 1 mm. The portion 71 of the osteotome 68 between
the grooves 70 and the tip of the osteotome is preferably smooth.
The outer diameter of the portion 71 is also preferably slightly
smaller than the outer diameter of the second section 22 and the
tip portion 16 of the dental implant 10. The longitudinal grooves
70 of the osteotomes 68a, 68b can have an outer diameter of from
about 3.15 mm to about 6.0 mm, for example, depending on the tooth
being replaced.
[0046] FIG. 6e is a side view of the opening 72 shaped by the
osteotome 68. The osteotome 68 a traumatically forms a plurality of
grooves 74 in the trabecular bone 56 and outer layer cortical bone
54a, substantially in the direction of the longitudinal axis of the
opening 72. FIG. 6f is a cross-sectional view of the opening 72
along line f-f of FIG. 4e, showing the longitudinal grooves 74.
[0047] A dental implant 10 is preferably chosen having a length
such that when inserted, the apical tip 76 of the dental implant 10
contacts the inner surface of the inner cortical bone 54b and the
ends of the longitudinal grooves 20 in the head portion 12 are at
the level of the crest 102 of the cortical bone 54a, or slightly
below the crest 102, as shown in FIG. 8g. In FIG. 9, which is a
front view of upper jaw, a natural -tooth 100 is shown adjacent to
the extracted tooth, the cemento-enamel junction 104 of the natural
tooth 100, the gingivus 106 and the gingival margin 108 are also
indicated.
[0048] To insert the dental implant 10, the implant 10 is oriented
such that the buccal side of the implant faces the buccal side of
the jaw and the lingual side of the implant 10 faces the-lingual
side of the jaw. During insertion of the dental implant 10, the
longitudinal grooves 20 of the dental implant 10 are aligned with
the longitudinal grooves 70 formed in the wall of the opening 72,
preventing rotation of the implant 10 after placement in the
opening 72. Since the outer diameter of the horizontal thread 24 or
grooves of the dental implant 10 is less than the outer diameter of
the longitudinal grooves 74 formed in the opening 72, the
horizontal threads 24 of the dental implant 10 pass through the
opening 72 unimpeded. The implant 10 is inserted into the opening
72 until the ends of the longitudinal grooves 20 in the head
portion are aligned with or slightly below the bone crest 102. The
ends of the grooves 20 are preferably not more than 0.5 mm below
the bone crest.
[0049] FIGS. 6g and 8 show the dental implant within the opening
72. The longitudinal grooves 74 of the opening 72 provide primary
stability for the implant 10 and properly align the head of the
implant in the mid-buccal portion of the osteotomy. Positioning the
ends of the longitudinal grooves 20 at or near the bone crest 102
locates the top surface 28 of the implant 10 at or near the
cemento-enamel junction 104a of the tooth being replaced. The
contour of the the top surface 28 of the head portion 12 from the
mid-buccal to mid-interproximal portions of the implant, generally
follows the shape of the cemento-enamel junction 104, 104a, the
bone crest 102 and the gingival margin 108. The shape of the side
wall of the head portion 14 also substantially matches the shape of
the outer surface of the cervical {fraction (1/3)} of the root of
the natural tooth being replaced. These conditions contribute to
minimizing adverse immunological responses.
[0050] After implantation, bone grows into the recesses of the
horizontal thread 24 or grooves, as well as the longitudinal
grooves 20, securing the dental implant 10 in position in the jaw
bone. The longitudinal grooves 20 continue to prevent rotation of
the implant 10 while the horizontal grooves 24 prevent the dental
implant from being pulled out. As the bone grows into the opening
32 in the tip portion 16, it is further secured against pull-out.
The surface treatments also contribute to osteointegration.
[0051] After sufficient time for the implant to become integrated
with the bone, a prosthetic tooth 120 is attached to the implant,
as shown in FIG. 6h. Since the head portion 12 matches the shape of
the natural tooth and the top surface 28 of the head portion 12
extends above the bone crest 102, an abutment is not be required.
However, an abutment may be used if desired. Use of an abutment
does not provoke an adverse immunological response in the bone
since the top surface of the implant 10 is above the bone crest
102.
[0052] Preferably, the shape of the portion 120a of the prosthetic
tooth 120 corresponding to the cervical {fraction (1/3)} of the
crown of the tooth being replaced substantially matches the shape
of the cervical {fraction (1/3)} of that tooth, minimizing pockets
between the prosthetic tooth and the gingivus. The remainder of the
prosthetic tooth can also now more closely match the shape of the
natural tooth being replaced. The shape of the cervical {fraction
(1/3)} of the tooth being replaced may be determined by taking an
impression of the natural tooth, as is known in the art. If there
is no natural tooth, then the optimum shape of the prosthetic tooth
may be approximated by analysis of adjacent teeth and the height
and width of the patient's face, as is known in the art. Since the
shape of the head portion 12 of the dental implant 10 of the
invention more closely matches the shape of the cervical {fraction
(1/3)} of the root of the tooth being replaced, the prosthetic
tooth 120 can more closely match the shape of the cervical
{fraction (1/3)} of the tooth being replaced. The transition
between the dental implant and the prosthetic tooth is more smooth
than with dental implants of the prior art, also decreasing the
presence of pockets between the prosthetic tooth and the
gingivus.
[0053] The outwardly flaring head portion 12 of the dental implant
10 closes the orifice of the opening 72 in the jawbone, preventing
soft tissue penetration and improving bone regeneration. Gaps below
the bone line, where soft tissue cannot enter, will be filled with
bone as the bone grows around the implant 10. Voids do not develop
which can collect food or plaque, or provide space for the growth
of soft tissue. In addition, since the cross-sectional shape of the
head portion 12 of the implant 10 generally matches the
corresponding cervical {fraction (1/3)} of the root and cervical
{fraction (1/3)} of the crown of the natural tooth being replaced,
gaps which could develop at the bone line into which soft tissue
can grow are minimized.
[0054] As discussed above, the distance d3 from the crest 102 of
the jawbone to the cemento-enamel junction 104 in an natural adult
tooth is typically about 1.80 mm and the distance d4 from the crest
102 to the gingival margin in an adult tooth is typically about 3
mm. The implant system including the dental implant 10 and the
prosthetic tooth preferably approximates these natural conditions,
minimizing adverse immunological responses by the bone to the
implant.
[0055] It is noted that the actual cemento-enamel junction drops
slightly from the midpoint of the interproximal surface of the
tooth toward the lingual side of the tooth. That portion of the
junction is preferably not matched by the dental implant 10, to
ease manufacturability and clinical application. Since the top
surface of the head portion 12 of the implant 10 is above the bone
crest 102 and the majority of the top surface of the head portion
12 (from the mid-buccal to mid-interproximal portion) matches the
shape of the cemento-enamel junction there should not be
significant bone resorbtion and resulting recession of the gingival
margin. Even if there is some bone resorbtion and gingivus
recession, however, it is at the rear of the tooth, which cannot be
seen.
[0056] If desired, however, the lingual portion of the top surface
of the implant could also follow the lingual portion of the
cemento-enamel junction of the tooth being replaced. FIG. 9 is a
plan view of the proximal side of such an implant 10b, wherein the
height d1 of the head portion 12 of the implant, from the body
portion 14 to the top surface 28, increases from the buccal portion
B of the implant 10a, to the interproximal portion I, and the
decreases from the interproximal portion I to the longitudinal
portion of the implant, as does the cemento-enamel junction of a
natural tooth. The height d1 of the buccal portion is substantially
the same as the height d1 of the lingual portion. The distance d2
from the ends of the longitudinal grooves 20 in the head portion 14
to the top surface 28 is also preferably maintained constant, at
about 1.80 mm. The remainder of the implant 10b is the same as
implant 10 in FIGS. 2 and 3.
[0057] FIGS. 10a-10c illustrate various steps in the method of
inserting the dental implant 10 of the present invention to replace
a tooth 100 to be extracted. FIG. 10a shows a tooth 100 to be
extracted by an a traumatic technique which minimizes damage to the
bone, as is known in the art. Before extraction, the mesial-distal
(MD) and buccal-lingual (BL) dimensions of the tooth are measured.
A properly sized implant is then selected. FIG. 10b shows the
opening 82 left by the extracted tooth. A 3 mm twist drill 64 is
then used to widen the hole left by the tooth 100, as shown in FIG.
10c. The osteotome 68a, 68b is then used and the dental implant 10
is inserted, as described above with respect to FIGS. 6d-6g.
[0058] FIGS. 11a and 11b show another configuration of a dental
implant 10b in accordance with the present invention, wherein the
head portion 12' is surface treated as described above with respect
to the dental implant 10a shown in FIGS. 4a, and 4b. The head
portion 12' has a greater length, as measured from the terminus of
the body portion 14' to the top surface 28' of the head portion
12', than in the dental implant 10a of FIGS. 4a and 4b. The body
portion 14' and in particular the longitudinal grooves 20', are
correspondingly shorter. As in the configuration of FIGS. 4a and
4b, the upper portion 12b' is polished and the interface X' between
the upper portion 12b' and the lower portion 12a' serves as a
reference line for positioning of the implant with respect to the
bone crest. In this configuration, the distance d1' from the
terminus of the body portion 14' to the top surface 28' of the head
portion 12' is less at the mid-buccal portion of the implant 10b,
rises toward the mid-interproximal proximal portion of the implant
and then decreases toward the mid-lingual portion of the implant.
As above, it is not necessary for that distance to decrease from
the mid-interproximal to the mid-lingual portion of the
implant.
[0059] It is noted that due to natural asymmetries between the
right and left sides of certain types of natural teeth, it may be
impractical with current manufacturing and implantation methods to
exactly match the cemento-enamel junction, even at the buccal
portion of a tooth. It is not necessary for the implant of the
present invention to match the right-left asymmetries of
cemento-enamel junction of a natural tooth, to achieve the
advantages of the present invention. However, if the implant is
custom designed for a particular tooth and such asymmetry is
matched, even better results may be obtained.
[0060] While the dental implants and prosthetic teeth of the
present invention have been discussed with respect to implantation
in the upper jaw, such implants and prosthetic teeth may be used in
the lower jaw, as well.
[0061] While preferred embodiments for practicing the present
invention have been described above, it is understood that
modifications may be made from these preferred embodiments without
departing from the scope of the present invention, which is defined
by the following claims.
* * * * *