Keywords
Dental surveyor - hand piece - intra-oral mouth mirror - photographic mirror
Clinical Significance
A dental student or a future dental practitioner needs to be trained to visualize
their teeth preparations to detect any amount of undercuts present so as to minimize
further clinical and laboratory problems such as over taper and open margins.
Introduction
During teeth preparation, our main aim is always to develop a common path of placement/insertion
to achieve passive and complete seating of the prosthesis.[[1]] Path of placement or withdrawal according to GPT is defined as: “the specific direction
in which prosthesis is placed on the residual alveolar ridge, abutment teeth, dental
implant abutment(s), or attachments.”[[2]] Fixed partial denture (FPD) with unparalleled abutments will necessitate excessive
seating force that often results in fractures in the veneering ceramic. In order to
avoid these side effects, clinicians tend to over taper the preparation. The excessive
reduction of the prepared abutments can compromise restoration retention and resistance
and jeopardize the biological health of the dentin-pulp complex in vital abutment
teeth.[[3]],[[4]] el-Ebrashi et al.[[5]] and Jogerson [[6]] suggested an optimum convergence angle (CA) of 2.5°–6.5° to decrease stress concentrations.
Jadhav et al.[[7]] suggested 2°–7° of taper or 4°–14° of CA to obtain maximum retention and stated
some techniques to measure taper and assess the relative parallelism of the prepared
abutment teeth to ensure the long-term success of cement-retained FPD. Nordlander
et al.[[8]] stated the use of mouth mirror, photographic mirror (PM), and dental periscope
when multiple abutments are being evaluated for a common path of placement. An intraoral
direct visual survey of the abutment preparations can be conducted using a mouth mirror
held at an angle above one of the prepared abutments, but it unfortunately may be
inaccurate and unreliable: Clinicians tend to over taper the preparation when using
this technique. Some clinicians use an extraoral indirect technique that consists
of surveying the stone cast on a dental surveyor (DS), which is more accurate than
the direct visual examination, but it necessitates extra laboratory steps and may
require additional visits before making a definitive impression, particularly if the
laboratory is far away from the clinic.[[3]],[[4]] Therefore, Vitsentzos in 1989 developed intraoral devices such as dental periscope
to examine the parallelism of abutment teeth.[[9]] However, these intraoral devices can be bulky and uncomfortable for patients.[[10]] Lee and So in 2008 used a modified laser pointer attached to a DS to detect the
undercut extraorally by surveying the intaglio surface of an irreversible hydrocolloid
impression.[[11]] Unfortunately, the major shortcoming of this technique was that it rendered impossible
visualization of the preparation in detail and required survey of the impression,
which is a negative reproduction unlike the surveying cast. While Farah in 2016 pointed
a technique facilitating the assessment of extra-oral preparation and the detection
of undercuts before making a definitive impression. This technique utilizes casts
fabricated from polyvinyl siloxane impression material and a class II laser module
attached to a DS.[[12]]
Although there is enough literature stating different CA measuring techniques, there
is a lack of documentation regarding the reliability and acceptance of these techniques
by different educational levels for measuring the path of insertion or withdrawal
of multiple abutments in fixed prostheses. The main aim of the study was to recommend
a particular technique to be included and stressed upon the curriculum of the undergraduate
course to limit the common mistakes done by dental students during tooth preparation.
The null hypotheses stated that there would be no differences in the opinions, attitudes,
and adoption of the four techniques across educational levels and no differences in
the accuracy within and between these techniques when used to check relative parallelism
of the abutment teeth.
Materials and Methods
Four different techniques, three intraoral (intraoral mouth mirror [IOM], PM, and
handpiece with torbido bur [HP]) and one extraoral (DS) were used to examine preparation
taper and relative parallelism of the prepared abutment teeth in the maxillary and
mandibular arches by participants in different educational levels (dental students,
interns, and faculty member). In addition, their level of satisfaction and their opinion,
attitudes in regard to difficulty, time consumption, and adoption among these techniques
were measured. Three stations were arranged with random combinations of maxillary
and mandibular sets to be evaluated by the participants.
Specimen preparation
A total of 12 artificial teeth (3 maxillary right 2nd molars, 3 mandibular right 2nd
molars, 3 maxillary right 2nd premolars, and 3 mandibular right 2nd premolars) were
mounted on a typodont model (Frasaco An-4 Puk, Pok).[[13]] The teeth were prepared simulating three completed sets of prepared abutments for
6 three-unit FPD divided equally for both arches. Standard models of occlusal planes
parallel to horizon were used. In addition, putty indices were made for the maxillary
and mandibular models, separately, to place them along with the digital protractor
in the same repeatable position for the determination of molar tooth preparation angle
to its long axis and the premolar abutment. In such arrangement, the protractor was
held accurately and repeatedly against the buccal surfaces of both abutments for all
models. The study set-up was made in the same location to ensure the standard management
of the samples. The preparation of premolars was finished first in both arches with
the proximal walls parallel to each other and 90° to the occlusal plane. The buccal
surface of molars was then prepared to remove any bulge or undercut and a line parallel
to premolar preparation was drawn. Another line was marked parallel (0°) (Set A for
maxilla and Set B for mandible), 20° (Set C for maxilla and Set D for mandible), and
45° (Set E for maxilla and Set F for mandible) to the first line. The proximal tooth
preparation was carried out using the second marked line as reference with a tapered
flat-ended diamond bur (201 R). Lingual and occlusal reduction was then followed to
finish the preparation [[Figure 1a-f]]. Abutments with unclear margins were excluded and replaced to avoid confusion when
measuring the angulations. Digital protractor was used for all angles measurements
[[Figure 1g]]. The manufacturer reported accuracy for Atrium digital protractor (Model: CR 2032)
used was ± 0.1°, which was accurate enough as a guide to achieve the desired pre-determined
angles. Duplicating silicone (Dupliflex-22; Protechno, Vilamalla, Girona, Spain) was
then used to prepare three sets of molds for both arches, and poured in type IV dental
stone (Lab Stone; Dentsply, York, PA) following the manufacturer's instructions using
a vacuum mixer (Mix-R; Dentalfarm, Torino, Italy) and a laboratory vibrator [[14]] (MiniExport; Dentalfarm) [[Figure 2a-f]].
Figure 1: Preparation of the abutment teeth with different angles (a-f) and the digital protractor
used in the measurements (g)
Figure 2: Duplicated maxillary and mandibular casts with second molar preparation as 0° (a
and b), 20° (c and d), and 45° (e and f) to the long axis of premolar preparation
Experiment and survey
A standard sheet to check teeth parallelism was prepared for this study. In addition,
a questionnaire was also prepared for the participants' opinions about difficulty,
time, and sensitivity while practicing the techniques. The difficulty was rated on
a scale of 1–5; 1 being the easiest and 5 being the most difficult. The next questions
were related to time required and sensitivity. Another question was related to individual
preference for the techniques on a scale of 1–4, with 1 being the highest while 4
being the lowest. The next part included a question in relation to technique favorable
for the adoption in dental school education/teaching or in private clinic. Moreover,
the last question was directed to the faculty members in the department of prosthetic
dental sciences to nominate the preferred technique to be included in the curriculum.
The questionnaire also included a table in the end for the researchers to note down
the correct/incorrect entries of the evaluations.
Ethical Approval to conduct this study was obtained from the Institutional Review
Board at Jazan University College of Dentistry before initiating the study (Ref letter
no. CODJU-18021). Three examiners were trained and calibrated, and a pilot study was
conducted to evaluate the intra- and inter-examiner measurement reliability. Intra-
and inter-examiner calibration was done in the pilot phase of the study to ensure
that data collectors were consistent. Since the study did not include active measurement
and it only involved evaluation of agreement between the predetermined angles on the
samples and participants assessment, the data collectors were initially blinded and
considered by the principal investigators as participants and went through the study.
Their responses were evaluated with regard to agreement between them and the angles
made on the samples. The measurements in that sense were “correct” if their responses
match the angle made on that particular sample or “incorrect” if their responses were
not matching. A total of 210 right-handed subjects participated in this study. Of
them, 83 were 4th and 5th year students (junior students), 50 were 6th year students
(senior students), 61 were interns, and 16 were the faculty members. Each participant
evaluated the three stations four times using four different methods. The study was
conducted over the period of September 1, 2018, to March 31, 2019. Participants were
called individually and each was given a brief description of the study as follows:
-
IOM: Conventional intra-oral examination mirror was used. The mouth mirror is to be
centered over one abutment and moved to the next without changing the angulation of
the mirror. Preparations are viewed with one eye closed to avoid undetected undercuts
with binocular vision
-
PM: Same maxillary and mandibular preparations (confined to one quadrant) are viewed
with a buccal photography mirror
-
Hand piece with torbido bur (HP): The participants use a torbido bur mounted on handpiece,
directly, to evaluate the path of insertion in two dimensions: Facio-lingually and
mesiodistally
-
DS: The casts obtained are positioned on the horizontal plane one by one on the DS
(A3005 Surveyor Type A; Dentalfarm) and the participants use analyzing rod to evaluate
the parallelism between abutments.
Each participant was given a copy of the questionnaire to complete and asked to leave
the study area at the completion of evaluation. The researchers were supposed to note
down the correct/incorrect evaluations of the participants.
Data analysis
The questionnaire and the correct/incorrect responses were coded and entered into
a Microsoft Excel Spreadsheet (Microsoft Inc., Redmond, WA). The questionnaire documents
were stored in the assigned area provided by the college. The participants' responses
to the questionnaires were presented in terms of frequencies, percentages, and charts.
Statistical analyses for the differences between the different educational levels
in relative to the different methods were utilized using the Chi-square test with
P < 0.05 was regarded as statistically significant. Data were analyzed using the statistical
software program for Windows (IBM SPSS Statistics v20; IBM Corp., Armonk, NY, USA).
Results
[[Table 1]] shows the results of the evaluation of the maxillary prepared abutments by the
four techniques in Sets A, C, and E. The technique that was correctly used by majority
of participants for Set A was the DS (77.4%), followed by PM (51.9%), HP (48.1%),
and IOM (47.6%). For Set C, the maximum correct responses were with the HP (57.1%)
followed by DS (55.7%), IOM (50.5%), and PM (48.1%). In Set E, IOM (75.0%) had the
highest correct response rate followed by the PM (74.1%) and the DS (47.6%) was the
least. The results of the evaluation of the mandibular prepared abutments by the four
techniques in Sets B, D, and F are presented in [[Table 2]]. Correct responses for Set B, the same was true with the DS (47.6%), followed by
HP (44.3%) IOM (38.7%), and PM (37.3%). While in Set F was with DS (77.4%) followed
by HP (70.8%) and the IOM (65.1%) was the least. While the technique that was correctly
used by the majority of participants for Set D was DS (46.7%) followed by HP and IOM
(37.3% and 36.3%, respectively). The PM group had the least correct responses (30.2%).
There were no significant differences among the correct responses (a correct response
is a true match between the participant's response and the angle made on the samples)
for different techniques for both maxillary and mandibular arches across the education
levels.
Table 1:
The reported correct responses across the educational levels to the four techniques
with regard to angle differences in the preparations of maxillary abutments
|
Juniors
|
Seniors
|
Interns
|
Faculty
|
Total
|
|
Maxillary second molars prepared with 0° (Set A)
|
|
PM
|
49 (59.0)
|
19 (36.5)
|
33 (54.1)
|
9 (56.3)
|
110 (51.9)
|
|
IOM
|
44 (53.0)
|
17 (32.7)
|
30 (49.2)
|
10 (62.5)
|
101 (47.6)
|
|
HP
|
45 (54.2)
|
18 (34.6)
|
29 (47.5)
|
10 (62.5)
|
102 (48.1)
|
|
DS
|
66 (79.5)
|
39 (75.0)
|
48 (78.7)
|
11 (68.8)
|
164 (77.4)
|
|
Maxillary second molars prepared with 20° (Set C)
|
|
PM
|
42 (50.6)
|
22 (42.3)
|
33 (54.1)
|
5 (31.3)
|
102 (48.1)
|
|
IOM
|
45 (54.2)
|
21 (40.4)
|
34 (55.7)
|
7 (43.8)
|
107 (50.5)
|
|
HP
|
53 (63.9)
|
23 (44.2)
|
34 (55.7)
|
11 (68.8)
|
121 (57.1)
|
|
DS
|
56 (67.5)
|
25 (48.1)
|
31 (50.8)
|
6 (37.5)
|
118 (55.7)
|
|
Maxillary second molars prepared with 45° (Set E)
|
|
PM
|
66 (79.5)
|
32 (61.5)
|
49 (80.3)
|
10 (62.5)
|
157 (74.1)
|
|
IOM
|
64 (77.1)
|
36 (69.2)
|
49 (80.3)
|
10 (62.5)
|
159 (75.0)
|
|
HP
|
57 (68.7)
|
33 (63.5)
|
41 (67.2)
|
8 (50.0)
|
139 (65.6)
|
|
DS
|
43 (51.8)
|
27 (51.9)
|
33 (54.1)
|
8 (50.0)
|
111 (52.4)
|
IOM: Intra-oral mouth mirror, PM: Photographic mirror, HP: Hand piece, DS: Dental
surveyor
Table 2:
The reported correct responses across the educational levels to the four techniques
with regard to angle differences in the preparations of mandibular abutments
|
Juniors
|
Seniors
|
Interns
|
Faculty
|
Total
|
|
Mandibular second molars prepared with 0° (Set B)
|
|
PM
|
28 (33.7)
|
17 (32.7)
|
27 (44.3)
|
7 (43.8)
|
79 (37.3))
|
|
IOM
|
39 (47.0)
|
20 (38.5)
|
14 (23.0)
|
9 (56.3)
|
82 (38.7))
|
|
HP
|
38 (45.8)
|
25 (48.1)
|
25 (41.0)
|
6 (37.5)
|
94 (44.3))
|
|
DS
|
46 (55.4)
|
21 (40.4)
|
27 (44.3)
|
7 (43.8)
|
101 (47.6))
|
|
Mandibular second molars prepared with 20° (Set D)
|
|
PM
|
28 (33.7)
|
12 (23.1)
|
20 (32.8)
|
4 (25.0)
|
64 (30.2))
|
|
IOM
|
34 (41.0)
|
16 (30.8)
|
22 (36.1)
|
5 (31.3)
|
77 (36.3))
|
|
HP
|
30 (36.1)
|
19 (36.5)
|
24 (39.3)
|
6 (37.5)
|
79 (37.3))
|
|
DS
|
43 (51.8)
|
24 (46.2)
|
27 (44.3)
|
5 (31.3)
|
99 (46.7))
|
|
Mandibular second molars prepared with 45° (Set F)
|
|
PM
|
61 (73.5)
|
35 (67.3)
|
38 (62.3)
|
10 (62.5)
|
144 (67.9))
|
|
IOM
|
57 (68.7)
|
34 (65.4)
|
36 (59.0)
|
11 (68.8)
|
138 (65.1))
|
|
HP
|
61 (73.5)
|
36 (69.2)
|
43 (70.5)
|
10 (62.5)
|
150 (70.8))
|
|
DS
|
68 (81.9)
|
42 (80.8)
|
41 (67.2)
|
13 (81.3)
|
164 (77.4))
|
IOM: Intra-oral mouth mirror, PM: Photographic mirror, HP: Hand piece, DS: Dental
surveyor
[[Table 3]] detects that PM was considered as easiest among faculty members (43.8%) followed
by juniors (26.5%), interns (26.2%), and the senior students (25.0%). While IOM was
rated as the easiest among faculty members (37.6%), followed by seniors (36.5%). HP
was easy for all participants, while DS was the easiest among the most participants
except among dental interns for whom responses were equally distributed as the easiest
and most difficult technique (37.5% each). There were no significant differences in
the distribution of difficulty of PM, IOM, and HP, but it was near to be significant
between the study groups for DS with P = 0.051.
Table 3:
Percentages of participants' reported scores across techniques and educational levels
relative to technique difficulty (score 1 means the easiest, while score 5 means the
most difficult)
|
Technique
|
Score
|
Juniors
|
Seniors
|
Interns
|
Faculty
|
Total
|
χ2
|
P
|
|
PM
|
1
|
22 (26.5)
|
17 (32.7)
|
13 (21.3)
|
7 (43.8)
|
59 (27.8)
|
13.607
|
0.556
|
|
2
|
12 (14.5)
|
13 (25.0)
|
16 (26.2)
|
2 (12.5)
|
43 (20.3)
|
|
3
|
21 (25.3)
|
10 (19.2)
|
12 (19.7)
|
2 (12.5)
|
45 (21.2)
|
|
4
|
14 (16.9)
|
6 (11.5)
|
11 (18.0)
|
2 (12.5)
|
33 (15.6)
|
|
5
|
14 (16.9)
|
6 (11.5)
|
9 (14.8)
|
3 (18.8)
|
32 (15.1)
|
|
IOM
|
1
|
20 (24.1)
|
14 (26.9)
|
18 (29.5)
|
6 (37.6)
|
58 (27.3)
|
21.465
|
0.123
|
|
2
|
14 (16.9)
|
9 (17.3)
|
15 (24.6)
|
4 (25.0)
|
42 (19.8)
|
|
3
|
21 (25.3)
|
19 (36.5)
|
8 (13.1)
|
3 (18.8)
|
51 (24.1)
|
|
4
|
16 (19.3)
|
6 (11.5)
|
10 (16.4)
|
2 (12.5)
|
34 (16.0)
|
|
5
|
12 (14.5)
|
4 (7.7)
|
10 (16.4)
|
1 (6.3)
|
27 (12.7)
|
|
HP
|
1
|
44 (53.0)
|
27 (51.9)
|
23 (37.7)
|
9 (56.3)
|
103 (48.6)
|
16.644
|
0.341
|
|
2
|
19 (22.9)
|
8 (15.4)
|
14 (23.0)
|
4 (25.0)
|
45 (21.2)
|
|
3
|
12 (14.5)
|
6 (11.5)
|
12 (19.7)
|
1 (6.3)
|
31 (14.6)
|
|
4
|
3 (3.6)
|
5 (9.6)
|
10 (16.4)
|
2 (12.5)
|
20 (9.4)
|
|
5
|
5 (6.0)
|
6 (11.5)
|
2 (3.3)
|
0
|
13 (6.1)
|
|
DS
|
1
|
57 (68.7)
|
37 (71.1)
|
33 (52.4)
|
6 (37.5)
|
132 (62.3)
|
24.888
|
0.051
|
|
2
|
9 (10.8)
|
2 (3.8)
|
4 (6.6)
|
0
|
15 (7.1)
|
|
3
|
6 (7.2)
|
4 (7.7)
|
7 (11.5)
|
1 (6.3)
|
18 (8.5)
|
|
4
|
3 (3.6)
|
5 (9.6)
|
7 (11.5)
|
3 (18.8)
|
18 (8.5)
|
|
5
|
8 (9.6)
|
4 (7.7)
|
11 (18.0)
|
6 (37.5)
|
29 (13.7)
|
IOM: Intraoral mouth mirror, PM: Photographic mirror, HP: Hand piece, DS: Dental surveyor
[[Figure 3]] shows that DS required maximum time among the different participants. There was
a significant difference between different techniques and participants with P = 0.04. DS was the technique which was assumed to have less errors, but more expensive
with more equipment usage. As illustrated in [[Figure 4]], most of the participants rated IOM as the most skilful technique, while for the
faculty members, it was the DS. There were no significant differences in the responses
for errors, skill required and expense and equipment needed between the participants
and different techniques with the P = 0.662, 0.235, and 0.612, respectively.
Figure 3: Composite graph showing the percentages among the different participants of the time
needed and less error of the different techniques used to check teeth parallelism
Figure 4: Composite graph showing the percentages among the different participants of the skills
and less adoption of the different techniques used to check teeth parallelism
All participants chose DS as the method that requires more steps (57.6%), followed
by IOM (19.0%), PM (14.3%), and least method was HP (9.0%). Senior and junior dental
students as well as the faculty members preferred the use of DS as the technique that
must be adopted during their education and teaching program or in their private clinics.
PM was the least preferred among all participants followed by IOM and HP. There were
no significant differences for a particular technique to be preferred (P = 0.548, 0.214, and 0.658, respectively). For DS, it was obvious that all participants
recommended this technique for teeth parallelism measurements except the interns (43.8%),
where it was least preferred. There was a significant difference between participants
in DS technique with P = 0.004. Half of the faculty members chose DS to be implemented in the academic curriculum,
while 25% found HP is more suitable, 18.8% chose PM, and only one faculty member (6.3%)
chose PM.
Discussion
With the advent of more complex fixed prostheses that involve multiple abutment teeth,
the difficulties of achieving the stated ideal tapers are multiplied. The conventional
method of the use of a freely held hand piece and “eye-balling” tooth preparations
for intra- and inter-tooth convergence has at least two obvious shortcomings.[[15]],[[16]] First, during the process of preparation, the dentist must depend on whatever degree
of hand-eye coordination and visibility he or she has at that moment. Second, it is
impossible to put back tooth structure if the tapers turn out to be excessive. Previous
studies have reported that the CA prepared by dental students was greater than that
recommended in textbooks, with a mean CA of 19.2° mesiodistally and 23° buccolingually
for vital teeth.[[17]] Most of the students used freehand methods during preparation. However, it is difficult
to prepare teeth with the minimal tapers deemed necessary in the literature, particularly
in multiple abutment prostheses, when freehand methods were used.[[18]],[[19]] When evaluating the tooth preparation path of placement parallelism for multiple
abutments intraoral PM s may allow easy visualization. Multiple preparations confined
to one quadrant or sextant may be viewed with a buccal photography mirror, whereas
an occlusal photography mirror provides a better view of multiple preparations in
an entire arch.[[20]]
A dental student or a future dental practitioner needs to be trained to visualize
their teeth preparations to detect any amount of undercuts present to minimize further
clinical and laboratory problems such as over taper and open margins. Careful literature
review revealed that this was the first study to survey and experimentally compares
the choices of different techniques to check the relative parallelism across all educational
levels and the faculty. The main aim was to recommend the most preferred technique
in the future curriculum which could save patients from more invasive procedures later
on by limiting common mistakes done by the students. The results of the present study
supported rejection of the null hypotheses. The results stated that the technique
that DS gave the maximum correct responses except in the maxillary arch when the molar
preparation was 20° to the premolar preparation where it was the hand piece and bur
technique and when the preparation of molar was 45° to the premolar preparation where
it was the intraoral mirror technique. DS being an extraoral technique was easier
for most of the participants to give correct answers for both the arches. With the
correct use of analyzing rod, it was easy for most of the respondents to detect the
amount of undercuts. The final position subsequent to cast orientation is crucial
in a surveyor, as changes in AP and lateral tilt may result in changes in the path
of insertion.[[14]] Passively adapted on the surveyor's horizontal shelf upon the placement of the
casts which could have perhaps led to small amount of incorrect responses for the
surveyor technique.
With PM, all the preparations need to be viewed with single eye centered over one
abutment and shifting to the next is done without moving the mirror. The undercut
areas relative to the opposing axial walls are difficult to examine since an operator
does not have any guideline to move the eye from over one abutment to the other.[[20]] Furthermore, this technique is not commonly used among the students. These could
have been the two most important reasons for maximum incorrect responses regarding
the PM technique. Study by Surathu and Nasim [[21]] stated that with regard to types of procedures that influence mouth mirror use,
only 20% of the dental students felt that it was mandatory to use a mouth mirror during
tooth preparation of posterior teeth. Moreover, only 10% of respondents used a mouth
mirror for indirect vision. This study clearly demonstrates the deficiencies in the
understanding of the use of a mouth mirror by dental students and suggested that most
students are not using the mouth mirror to its maximum advantage and are either unaware
of its potential for use or are simply not employing it for all its functions. This
could perhaps be a possible reason of many incorrect responses for the mouth mirror
technique.
The use of PM technique was rated as easiest among the interns (26.2%). This could
because of their experience in using PMs in the 6th year comprehensive course and
internship training programme. In addition, consistent responses from all educational
levels disclosed DS as the least difficult and most practical of the studied techniques
except among dental interns (37.5%) for whom it was the most difficult technique.
This could be related to the multiple factors including stress during graduation requirements,
instructor's evaluation methods or student experience.[[13]] However, the skills for using surveyor could be improved with proper clinical training.
The majority of the participants reported higher preference and adoption rates for
surveyor technique, except for dental interns who preferred hand piece (43.8%). The
intern group was freshly graduated dentists who were familiar with the techniques
used in the study; however, their preference tends to use much easier techniques that
utilize less steps, technical sensitivity, and armamentaria. In contrast, the faculty
members prefer the DS due their academic background and ample experience with such
device and they believe in its accuracy, while the undergraduate students may felt
excited about the application of such sophisticated tool and got enthusiastic in term
of preferring it among other techniques. Although this finding is supported in the
literature and familiar, it not used as a chair side technique due to increase in
number of appointments. The existence of special types of mirrors, particularly front
surface and concave surface mirror is not familiar with the dental students. The use
of these special mirrors can enhance the accuracy factor that indirect vision brings
to dentistry.[[10]] There is certainly scope to make students more aware of the advantages of indirect
vision and focused training on the use of indirect vision will help many students
incorporate this ergonomically useful technique into their clinical technique. Even
the undercut evaluation were incorrect by some participants, still their answers to
the questionnaire were accepted. Future questionnaires can include questions about
the techniques' steps so as to know the particular steps which need to be stressed
upon in the undergraduate curriculum.
Conclusions
Within the limitations of this study, it can be concluded that:
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The DS was more favored among the respondents across all educational levels
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This technique presented high potential in accurately evaluating tooth preparation
undercut, abutments parallelism, and path of withdrawal in comparison to the intraoral
techniques.
