Association Between Amount Of Remaining Tooth Structure And Tooth Morphology In Post Selection. - An Institution Based Retrospective Study
Trinaina Somas Kandhan1, Iffat Nasim2*, Arvina Rajasekar3
1 Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Science, Saveetha University, India.
2 Professor, Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospital, Saveetha Institute Of Medical and Technical Science, Saveetha University, India.
3 Senior Lecturer, Department of Periodontics, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences Saveetha University, Chennai, India.
*Corresponding Author
Iffat Nasim,
Professor, Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospital, Saveetha Institute Of Medical and Technical Science, Saveetha University,
India.
Tel: +91 99400636567
E-mail: iffatnasim@saveetha.com
Received: November 07, 2020 Accepted: November 22, 2020; Published: November 30, 2020
Citation:Trinaina Somas Kandhan, Iffat Nasim, Arvina Rajasekar. Association Between Amount Of Remaining Tooth Structure And Tooth Morphology In Post Selection. - An Institution Based Retrospective Study. Int J Dentistry Oral Sci. 2020;S10:02:0021:113-119. doi: dx.doi.org/10.19070/2377-8075-SI02-0100021
Copyright: Iffat Nasim© 2020. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.
Abstract
The lifespan of an endodontically involved tooth has been greatly influenced by continued emergence of different modalities
in endodontic treatment and the restorative procedures.In the last few years, various prefabricated posts systems have emerged.
The selection of a suitable post design and type is important, as it may have an influence on the survival of the tooth. Teeth have
characteristic morphology and have many anatomical variations, which may adversely affect the selection and placement of a post.
This study aims to assess the correlation between the amount of remaining tooth structure and tooth morphology during post
selection.
A retrospective cross-sectional study was conducted using the patient records from the Department of Conservative Dentistry and
Endodontics from June 2019-April 2020. The patients were assessed based on the type of post used, the remaining tooth structure
and type of tooth/tooth morphology. Data was collected and then subjected to statistical analysis. A total of 714 patients, it was
observed that 60 patients underwent post endodontic treatment with custom made posts, 334 patients with Prefabricated Fiber
reinforced posts and 320 patients with Prefabricated Metal posts. 24.4% of the cases had a remaining tooth structure between
1-2mm, 66.1% cases between 2-4mm and 9.1% of the cases had a between 4-6 mm. It was noticed that 40 year old patients mostly
underwent post endodontic treatment and usually upper right maxillary central incisors were subjected to post endodontic restorative
therapy. On statistical evaluation it was noticed that there was a positive correlation between remaining tooth structure and
type of post used with a statistically significant result, p<0.05.
For restored endodontically treated teeth that do not have complete circumferential tooth structure between the core and preparation
finish line, the location of the remaining coronal tooth structure may affect their fracture resistance.Therefore it is of paramount
importance that the analysis between types of post to be selected depending on the amount of tooth structure should be
further studied so as to provide clarity to dentists during treatment planning of post endodontic restorations.
2.Introduction
3.Materials and Methods
4.Results and Discussion
5.Conclusion
6.Author Contribution
7.Acknowledgements
8.References
Keywords
Custommade Post; Post Endodontic Restoration; Prefabricated FRC Post; Prefabricated Metal Post; Remaining Tooth
Structure
Introduction
Restoration of endodontically treated teeth is an important aspect
of dental practice that involves a range of treatment options
of variable complexity [28]. The challenge may be complicated
by substantial loss of coronal tooth structure and the ability to
predict restorative success [21]. The likelihood of survival of a
pulpless tooth is directly related to the quantity and quality of
the remaining dental tissue. A post is usually placed in an attempt
to strengthen the tooth. However, in vitro and in vivo studies
have demonstrated that a post does not reinforce endodontically
treated teeth. Posts are required for supporting a core foundation when there is insufficient clinical crown remaining [10, 13].
Nowadays, cast post-core restorations are the option of choice
for endodontically treated teeth but this kind of restoration, according
to many authors, makes teeth fragile and more susceptible
to fracture. Prefabricated post systems have recently become
increasingly popular because they can provide satisfactory results
[5].
According to Cohen, et al.the association of prefabricated intraradicular
posts, light-, chemical- and dual-cured resins, and dentin
primers used for core build-up allows higher core preservation
as well as adequate resistance.The use of prefabricated posts has
brought special attention to core materials. This core build-up was
designed to be made of composite, yet more specific materials
have been developed [6]. It has been shown that composites have
adequate resistance to compressive strength and fracture. With
recent improvements in the bonding of composite resins to dentin,
true internal support is now available. In 1998, Zalkind and
Hochman recommended the use of composite as core material
only when adequate coronal dentin structure is available [35].
There are various features that play an important role in selection
of type of post to be used in post endodontic therapy such
as, The length and shape of the remaining root determines the
length of the post [8]. It has been suggested that root length
should be considered for the selection of the ideal post length. It
has been demonstrated that the greater the post length, the better
the retention and stress distribution [2]. However, it may not
always be possible to use a long post, especially when the remaining
root is short or curved. Each tooth in the arch exhibits anatomic
characteristics such as root curvature, mesio-distal width,
and labio-lingual dimension. Hence, root anatomy dictates post
selection [3]. Each tooth is anatomically different from the other
and the same type of tooth may have certain variations, which
may adversely affect the post placement. The amount of remaining
coronal tooth structure is also a critical factor in determining
the post selection [19].
Endodontically treated teeth often lack coronal tooth structure
as a result of caries, previous restorations, trauma, or endodontic
procedures [17]. In these situations, successful restoration of an
endodontically treated tooth may be a challenging procedure.
This study aims to analyse the correlation between the remaining
tooth structure and the post used so as to aid in the appropriate
selection of posts during post endodontic therapy and thereby aid
in efficient treatment planning.
Materials And Methods
Study design and setting
This institution based retrospective study examined the records
of patients from June 2019-April 2020 undergoing treatment at
our hospital. The approval from the institutional ethics committee
was obtained. The sample population included patients who
underwent post endodontic restorative therapy at the Outpatient
ward of our hospital by means of non-probability sampling. Patients
who were systemically healthy and were included in the
study, those with mental and physical disabilities were excluded
from the study.
Data collection
Data was obtained from exclusive patient management records
which was used to identify 714 patients in the hospital database
who underwent post endodontic replacement therapy using different
types of posts, namely Custom made posts, Prefabricated
FRC post and Prefabricated Metal posts. Data relevant to the
study such as Patients unique ID, Name, Age, Sex, Tooth Number
and Remaining Tooth Structure was recorded. Repeated patient
records and incomplete records were excluded. Data was verified
by an external reviewer.
Statistical analysis
Data was recorded in Microsoft Excel 2016 (Microsoft Office 10)
and later exported to the SPSS software for Windows (Version
20.0, SPSS Inc, IBM, Chicago Ill., USA) and subjected to statistical
analysis. Chi square test was employed with significance level
set at p<0.005.
Results And Discussion
In the present study, the final data comprised of 714 patients in
total of Indian origin who underwent post endodontic restorative
therapy, out of which, it was observed that 60 patients underwent
post endodontic treatment with custom made posts, 334 patients
underwent post endodontic treatment with Prefabricated Fiber
reinforced posts and 320 patients underwent post endodontic
treatment with Prefabricated Metal posts. (Table 1,Graph 1)
This table indicates that 60 patients underwent post endodontic
treatment with custom made posts, 334 patients underwent post
endodontic treatment with Prefabricated Fiber reinforced posts
and 320 patients underwent post endodontic treatment with Prefabricated Metal posts.
On analysing the remaining tooth structure prevalence it was noticed
that, 24.4% of the cases had a remaining tooth structure
between 1-2mm, 66.1% cases had a remaining tooth structure
between 2-4mm and 9.1% of the cases had a remaining tooth
structure between 4-6 mm (Table 2, Graph 2).
This table indicates that out of 714 patients, 24.4% of the cases
had a remaining tooth structure between 1-2mm, 66.1% cases
had a remaining tooth structure between 2-4mm and 9.1% of the
cases had a remaining tooth structure between 4-6 mm.
It was also noticed that 40 year old patients mostly underwent
post endodontic treatment and usually upper right maxillary central
incisors (11) were subjected to post endodontic restorative
therapy. (Graph 3, Graph 4)
In the present study, it was noted upon running Chi square tests
of the correlation between the type of post used and tooth number
that, there was positive correlation, the results were statistically
significant p<0.05, (p=0.00), thereby suggesting that type of
tooth or tooth morphology played a predominant role in post
selection. It was observed that Prefabricated FRC posts were preferred
in cases of maxillary anterior teeth, followed by custom
made posts. It was also observed that Prefabricated Metal posts
were preferred in case of mandibular anteriors and posterior
teeth.(Table 3, Graph 5)
Chi square test were done to correlate between the type of post
used and the remaining tooth structure, it was observed that teeth
with remaining tooth structure of 2-4mm usually were treated
with prefabricated FRC or Metal posts and those with 1-2mm of
remaining tooth structure were subjected to therapy using Prefabricated
FRC posts, the results were statistically significant p=0.043
(Table 4, Graph 6)
On observing the above results, it was noticed that thorough planning and understanding of tooth morphology and the remaining
tooth structure forms the foundation for post endodontic therapy,
and therefore, thorough knowledge regarding the indications
and properties of different posts is of paramount importance.
Post and cores contribute in providing efficient restorative options
for priorlyendodontically treated teeth. After reviewing various
literature, it is observed that an ideal post system should have
the following features:
(a) physical properties similar to that of the tooth's dentin,
(b) maximum retention with minimal dentin removal,
(c) distribution of various stresses evenly along the surface of the
tooth and the root,
(d) esthetic compliance with the final restoration and the tissue
surrounding it
(e) during placement and cementation, minimal stress should be
dissipated ,
(f) inability of the restoration to be displaced,
(g) proper retention of the core,
(h) easily retrievable if need be,
(i) material should be compatible with core,
(j) ease of use, safety and reliability, and
(k) reasonable cost.
Therefore, the clinician should be knowledgeable in selecting the
right type of post and core systems to meet the biological, mechanical,
and esthetic needs for each individual tooth [7].
One major cause of failure of the post endodontically restored
tooth is usually root fracture.Therefore, it is of an advantage
if tooth preparation and post designs minimize the chance
of root fracture. A ferrule is a metal ring or cap intended for
strengthening.A dental ferrule is an encircling band of cast metal
around the coronal surface of the tooth. It has been noted that
the use of a ferrule as a unit of the core or an artificial crown
may be of vital importance in root canal filled teeth. The ‘ferrule
effect’ occurs dueto the ferrule resisting various stresses such as
functional lever forces, the wedging effect of tapered posts and
the lateral forces exerted during the post insertion, the ferrule acts
as a protective unit and is often referred to as the ferrule effect.
The restoration of endodontically treated teeth involves different
materials and principles.Conservative preparations restricted to
only endodontic access preparation can be restored using amalgam
or composites associated with bonding agents to avoid microleakage.
However, some posterior teeth whose greater amount
of structure was missed need cuspal protection to direct forces
at the long axis of the root, avoiding longitudinal fractures while
anterior teeth often require post because of oblique forces.Even
though posts are indicated to retain a core when coronal structure
is missed, some authors have advocated the use of posts associated
with composites as an alternative to crowns in posterior teeth
[16].
Nevertheless, it is necessary to consider that there are metallic,
ceramic and fiber posts, prefabricated or customized. Fiber posts
have been indicated in situations where there is loss of root structure
because its moduli of elasticity is close to dentin, but some
coronal remaining structure is necessary to retain the core using
adhesive systems. Different from these posts, metal cast posts
have been used when greater quantities of coronal structure is
missed and functional demand is higher such as support teeth of
removable or fixed partial prostheses [31].
On observing, previously conducted invivo studies [11, 14, 18,
22-25, 29] and in vitro studies [12, 13, 15, 20, 26, 27, 34], regarding
the conservative and endodontic considerations pertaining to
post endodontic restorative therapy over the past few years, we
have now focused on the epidemiology and prevalence pattern
so as to analyze the current scenario and further elaborate on the
possibility of the present diagnostic and treatment modalities to
ultimately aid in efficient treatment planning.
In this study it was noticed that Prefabricated Fibre Post and
Core systems were preferred in comparison to other post endodontic
systems and predominantly maxillary central incisors [11]
were subjected to treatment with a remaining tooth structure of
2-4mm. This was further cross referenced with other epidemiological
studies to further understand the relevance of the present
study.
In a study by Spear et.al, he states that, to ensure functional longevity,
endodontically treated teeth must have at least 5 mm of
tooth structure coronal to the crestal bone. Three millimeters are
needed to maintain a healthy soft tissue complex, and 2 mm of
coronal tooth structure incisal to the preparation finish line are
necessary to ensure structural integrity [32].
An in vitro study by Al Wahadani et.al, he compares the fracture
resistance of adhesively cemented titanium, prefabricated, glass
fiber, and carbon fiber posts on teeth with 2 mm of remaining
tooth structure favored titanium posts. However, the teeth were
not restored with crowns, negating the ferrule effect [1].
Another study by Gu et.al, compared metallic with nonmetallic
posts cemented with adhesive or nonadhesive cements on teeth
with 2 mm of remaining tooth structure. The authors concluded
that fiber posts showed greater fracture resistance than cast posts
and cores and that the use of resin cement did not improve the
performance of metallic posts. This is in synchrony to the present
study which reveals that Prefabricated Fiber reinforced posts are
preferred in teeth with remaining tooth structure of 2-4mm [9].
In a study by Sidoli et.al, [30] it was observed that the bulk of
the tooth above the restorative margin should be at least 1.5 to 2
mm to achieve resistance form [30]. This was synonymous with
this study where it was noted that 61.1% of the patients who were
chosen for post endodontic restorative therapy had a remaining
tooth structure of 2-4mm.
It was also found by Bergman et.al, that teeth restored with carbon
fiber posts had inferior strength compared with those restored
with metal posts when subjected to forces simulating those
in a clinical setting.The use of cast post and cores in restoring endodontically
treated teeth with moderate to severe coronal tooth
loss [4]. This may be the reason attributing to Prefabricated Metal
posts being a close competitor to Prefabricated FRC posts as a
gold standard treatment of choice.
It was also observed in a study by Standlee st.al, [33] that nonmetal
posts, such as a carbon fiber post system, can be used when
ample coronal dentin remains and the crown supported by the
remaining tooth structure; or, cast post and core is preferred in
cases when there is minimal tooth structure or excessive tooth
loss [33]. Although the present study varies from this school of
thought, this may explain the reason for Prefabricated metal posts
in posterior teeth in comparison to FRC posts, which thereby
sheds light on the need for further exploration.
Endodontically treated teeth are more brittle due to loss of structural
integrity associated with access preparation or caries. Because
of the brittleness of these elements, planning will be associated
with the remaining tooth structure and functional demands,
once load received depends on tooth position in the arch, occlusion
and rehabilitation planning. With the vast development and
availability of different materials and post designs present for the
restoration of teeth that have priorly undergone endodontic therapy,
the operator must be selective in choosing the post system
that is most suitable for the individual needs of each tooth. For
restored endodontically treated teeth that do not have complete
circumferential tooth structure between the core and preparation
finish line, the location of the remaining coronal tooth structure
may affect their fracture resistance.
Therefore it is of paramount importance that the analysis between
types of post to be selected depending on the amount of
tooth structure should be further studied so as to provide clarity
to dentists during treatment planning of post endodontic restorations.
Graph 1. Frequency distribution of various post endodontic therapy.
Graph 2. Frequency distribution of remaining tooth structure.
Graph 3. Frequency distribution of the age of patients.
Graph 4. Frequency Distribution of type of tooth subjected to post endodontic therapy.
Graph 5. Association between tooth morphology/tooth number and the type of post used.
Graph 6. Association between remaining tooth structure and type of post used.
Table 1. Frequency distribution of patients undergoing various post endodontic therapy.
Table 2. Frequency distribution of remaining tooth structure.
Table 3. Statistical Analysis of correlation between tooth morphology and type of post used.
Table 4. Statistical analysis of the correlation between remaining tooth structure and type of post used.
Conclusion
From the present study, it was observed that most patients underwent
post endodontic treatment with Prefabricated Fiber reinforced
posts followed by treatment with Prefabricated Metal
posts. It was also noticed that the remaining tooth structure was
between 2-4mm. It is concluded that restored endodontically
treated teeth that do not have complete circumferential tooth
structure between the core and preparation finish line, the location
of the remaining coronal tooth structure may affect their
fracture resistance and overall quality of post endodontic restoration.
Further studies pertaining to the correlation between remaining
tooth structure, tooth morphology and post selection
will aid in efficient treatment planning.
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