Dentistry – Method or material for testing – treating – restoring – or... – Endodontic
Reexamination Certificate
2002-02-21
2004-06-08
O'Connor, Cary E. (Department: 3732)
Dentistry
Method or material for testing, treating, restoring, or...
Endodontic
C433S102000
Reexamination Certificate
active
06746245
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention is in the field of endodontistry. More particularly, the invention is in the field of systems and methods for treating root canals.
2. The Relevant Technology
To preserve a tooth with a pulp that is diseased or is potentially diseased, it is generally necessary to remove the pulp material in the pulp canal from the tooth, to shape the root canal(s), to prevent or minimize the presence of bacteria through the use of irrigants and dressings, to clean the walls of the root canal(s), to eliminate the smear layer made during instrumentation of the root canal(s) to open the dentinal tubules. These steps are all done to prepare the root cavity for being filled or obturated with biocompatible materials, such as gutta percha, before the pulp cavity is sealed, thereby promoting the healing and functional recovery of the tooth. This procedure is referred to as root canal therapy.
Root canal preparation, which generally involves the pulp removal and cleaning of the root canal walls as well as shaping of the canal walls, is typically achieved by mechanical or hand instrumentation with files or bits that are configured to bore and/or cut. Mechanical instrumentation can be achieved through the use of endodontic handpieces that give instruments such as files a rotational motion, reciprocal motion, sonic movements or ultrasonic movements.
Before endodontic therapy is begun, a preoperative X ray is prepared to assess the health and the pathological status of the tooth and to determine the approximate length of the root canal in order to select an instrument for use in the root canal with an appropriate working length. The X ray yields an image, such as the schematic representations shown in
FIGS. 1A and 1B
, which generally show teeth
10
with sufficient clarity to view some of the properties of roots
12
and the root canals
14
located therein, particularly the location of the radiographic apex
17
just beyond the apical foramen
16
. The distance between radiographic apex
17
and a fixed reference position on the occlusal surface of a tooth is used to determine the working length of the instrument.
FIG. 1B
, an enlarged view of root
12
a
shown in
FIG. 1A
taken along cutting line
1
B—
1
B, shows the relative position of the radiographic apex designated at line
17
with that of the endodontic apex and the anatomical apex, which are designated by lines
18
and
19
, respectively.
Preoperative or intraoperative X ray images of a tooth requiring endodontic treatment, such as the X ray image depicted in
FIG. 1A
, are obtained by lingual placement of film packets as shown in
FIG. 2
at
22
and by an X ray film packet holder (not shown) and a long cone X ray head (not shown) seated outside of the cheek. Although, X ray images formed, as shown in
FIG. 2
, from a buccal-lingual X ray projection are generally useful for determining the length of the root canal and the working length for a file, such images provide only limited information regarding the overall anatomy of the root canal and can also be misleading as to the actual length of the root canal.
The information is limited because only one dimension of the overall anatomy of the pulp cavity can be viewed in vivo. Such images show only a linear aspect of the root canal but cannot show a tridimensional view of a tooth and its root canal(s). Although, it would be very helpful to view a tooth from a position between the teeth or from the interproximal space such a mesial-distal view cannot be clearly produced when the tooth is still positioned in a patient's mouth.
The difficulties presented to an endodontist in assessing the overall anatomy of teeth from just the X ray images obtained from buccal-lingual X ray projections can be clearly identified with reference to
FIGS. 3-6
.
FIGS. 3A-6A
are longitudinal cross-sectional schematic views of extracted teeth taken from the front or back of the respective tooth which corresponds with the images obtained from buccal-lingual X ray projections.
FIGS. 3B-6B
depict longitudinal cross-sectional schematic views of the same extracted teeth shown in
FIGS. 3A-6A
from the mesial-distal or side view that cannot be obtained or seen while the teeth are still positioned in a patient's mouth.
FIGS. 3-4
illustrate the necessity for practitioners to rely heavily on their experience and knowledge of typical anatomical structures to properly prepare a root canal.
FIG. 3A
depicts a lower premolar
30
from the buccal-lingual view of the tooth which shows root
32
and a root canal
34
therein that appears to be rather narrow and to have a relatively uniform perimeter along its length.
FIG. 3B
, however, shows that when seen from the mesial-distal view, the root canal is initially wide and then tapers significantly before reaching the apical foramen
36
. The practitioner may not be able to accurately assess the anatomical structure of the root anatomy when limited to knowledge derived from an x-ray corresponding to the image shown in FIG.
3
A. Similarly,
FIG. 4B
, which depicts an upper premolar
40
with roots
42
a
and
42
b
and root canals
44
a
and
44
b
located therein, illustrates the need for practitioners to rely merely on accumulated experience and knowledge of typical anatomical structures as the configuration of pulp chamber
48
may be difficult to accurately ascertain from only an X ray photograph that corresponds with the image shown in FIG.
4
A.
Additionally, practitioners encounter anatomies with widely varying aberrations and intercommunications of root canals.
FIG. 5A
depicts a mandibular or lower incisor
50
from the buccal-lingual view of the tooth, which shows root
52
and root canal
54
.
FIG. 5B
depicts the same lower incisor
50
from the mesial-distal view of the tooth. The mesial-distal view shown in
FIG. 5B
clearly shows that root canal
54
branches and then merges to have a single foramen
56
. This common root canal morphological variation shown in
FIG. 5B
may not be ascertainable to a practitioner as the practitioner can only obtain a preoperative or intraoperative X ray image of lower incisor
50
which corresponds to FIG.
5
A. Similarly, a root canal may branch without merging to yield multiple foramina as shown in
FIGS. 6A-6B
which depict a lower first molar
60
. Again, the buccal-lingual view, as shown in
FIG. 6A
, provides inadequate information compared with the depiction taken from the mesial-distal view of mesial root
62
b
in
FIG. 6B
wherein branches
64
a
and
64
b
are shown which do not merge and accordingly have two foramina
66
a
and
66
b.
In addition to the morphological variations in anatomy as discussed above, there are also substantially different perimetrical configurations of root canals. The shape of root canal perimeters varies not only between different types of teeth but also along the length of a single root canal of a tooth as is illustrated in
FIGS. 7A-7B
.
FIG. 7A
depicts a maxillary right first molar
70
with cutting lines which show the division of the tooth into transverse cross-sections for segmentation as shown in FIG.
7
B.
FIG. 7B
displays roots,
72
a
,
72
b
and
72
c
, of molar
70
cut into four respective segments,
80
-
83
, to clearly show the variations of root canals
74
a
,
74
b
and
74
c
. Also displayed in
FIG. 7B
are segments
84
and
85
which respectively contain the floor of the pulp chamber
78
and pulp chamber
78
. Contrasting the perimeters of root canals
74
a
,
74
b
and
74
c
beginning in segment
84
as each root canal tapers to its respective apices
76
a
,
76
b
and
76
c
clearly shows that the perimeter anatomy varies along the length of each root canal.
As indicated above, root canals have a variety of perimetrical or circumferential anatomies depending on the type of tooth. Accordingly, the practitioner must utilize instruments in root canals with diverse perimetrical anatomies that each also vary and transition in the configuration of their respective perimeters alo
Fischer Dan E.
Riitano Francesco
O'Connor Cary E.
Ultradent Products Inc.
Workman Nydegger
LandOfFree
Methods for cleaning and shaping asymmetrical root canals in... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods for cleaning and shaping asymmetrical root canals in..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods for cleaning and shaping asymmetrical root canals in... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3357685