10.59987/ads/2013.1.142-148
Objectives. The aims of this study were to conduct a morphometric analysis on the buccal furcation grooves in freshly extracted bifurcated maxillary first premolars (MFPs) and to correlate all anatomical measurements using microcomputed tomography.
Materials and Methods. Twenty-three human MFPs with bifurcated canals were selected for this study. The specimens were analyzed with microcomputed tomography.The length, the beginning, and the ending of the grooveswere measured. The minimum cross-sectional canal wallthickness in the grooves was located, and the width ofthe dentin thickness was calculated. All measurementswere recorded and statistically analyzed.
Results. The concavity of the grooves begins before the bifurcation site in 9/23 samples and after the bifurcation in 56.5% of samples. The groove length varied between 1.1-9 mm; the cross-sectional area with minimum palatal dentin thickness was 0.78±0.14 mm, which was locatedat a mean distance of 7.1 mm from the cementoenamel junction (CEJ) and 1.38 mm from the furcation.
Conclusions. The presence of the furcation grooves in the palatal aspects of the buccal roots of the MFPs was 100%. The length, depth, location, and width of the dentinthickness of the grooves varied in relation to tooth length, bifurcation, and CEJ. These parameters shouldbe taken into consideration before any endodontic orrestorative procedures are performed. Reducing dentin width too vigorously by intracanal instrumentation can predispose to vertical root fractures or perforations; if a post cannot be avoided, it should not extend 6.5 mmfrom the CEJ.
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morphometric analysis
Microcomputed tomographic analysis of the furcation grooves of maxillary first premolars
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Microcomputed tomographic analysis of the furcation grooves of maxillary first premolars
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                                                                                                        Original article


Microcomputed tomographic analysis of the
furcation grooves of maxillary first premolars




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Saad Misfer Al-Shahrani, BDS, MSD, SBE1                        post cannot be avoided, it should not extend 6.5 mm
Dina Al-Sudani, DDS, MSEd2                                     from the CEJ.




                                                                                        io
Majed Almalik, BDS3
Gianluca Gambarini, MD, DDS4                                   Key words: Buccal furcation groove, maxillary premolar,
Faisal Ahmed AlRumaihi, BDS, DSc5                              microcomputed tomography, morphometric analysis.




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1
    Armed Forces Hospital, Riyadh City, Saudi Arabia           Introduction
2
    King Saud University, College of Dentistry, Riyadh City,
    Saudi Arabia                                               Maxillary first premolars (MFPs) have a unique anatom-




                                                                       n
3
    Karolinska institute, Division of Endodontics,             ical features includes bifurcated roots, a narrow furcation
    Solna, Sweden                                              entrance, deep mesial concavities, and multiple canals




                                                                    er
4
    “Sapienza” University of Rome, Italy                       (1). Few studies have mentioned the presence of the
5
    Riyadh Military Hospital, Riyadh City, Saudi Arabia        furcation grooves in the palatal aspects of the buccal
                                                               roots of the MFPs (2-5). The prevalence of this phenom-
                                                               enon was reported to be very high, ranging from 62% to
Corresponding author:
Dina Al-Sudani, DDS, MSEd
King Saud University, College of Dentistry,
                                           nt                  100% (6-8). A lack of knowledge about the extent and
                                                               thickness of the dentin in this area might lead to exces-
                                                               sive thinning or perforation of the dentinal wall during ei-
                                         iI
P.O. Box 60169, 11545, Riyadh City, Saudi Arabia               ther endodontic or restorative procedures, increasing the
Phone: +966 504441941                                          possibility of vertical root fractures (9-11).
E-mail: drdina_2000@yahoo.com                                  Furthermore, morphometric studies on the palatal groove
                                       on

                                                               of the buccal root and its relationship to the dentin width
                                                               found that the palatal wall in unprepared roots was, on av-
                                                               erage, less than 1 mm (4, 5, 9-12). Nevertheless, several
Summary
Objectives. The aims of this study were to conduct a           studies have shown that posts must be surrounded by 1
                               i


morphometric analysis on the buccal furcation grooves          mm of sound dentin (13-15).
                            iz


in freshly extracted bifurcated maxillary first premolars      Several methods have been used to assess tooth mor-
(MFPs) and to correlate all anatomical measurements us-        phology, including the use of simple visual inspection of
ing microcomputed tomography.                                  sectioned or cleared teeth (16, 17) and radiographic ex-
              Ed




Materials and Methods. Twenty-three human MFPs with            amination (18-21). The furcation grooves in MFPs were
bifurcated canals were selected for this study. The spec-      investigated initially by Tames et al. (4). They used the
imens were analyzed with microcomputed tomography.             Tool Makers Microscope after embedding the teeth in
The length, the beginning, and the ending of the grooves       acrylic and sectioning them into 1-mm-thick slices from
were measured. The minimum cross-sectional canal wall          the apex to the furcation. Lammertyn et al. (22) used a
thickness in the grooves was located, and the width of         sectioning method and profile projector to assess the
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the dentin thickness was calculated. All measurements          furcation grooves in the buccal roots of MFPs. This ap-
were recorded and statistically analyzed.                      proach is complicated, time consuming, and can introduce
Results. The concavity of the grooves begins before the        artifacts and distortion of internal tooth anatomy (23). Al-
bifurcation site in 9/23 samples and after the bifurcation     though the authors produced three horizontal slices (2
C




in 56.5% of samples. The groove length varied between          mm from the furcation, 2 mm from the anatomic apex, and
1.1-9 mm; the cross-sectional area with minimum palatal
                                                               the third slice equidistant between the first and second
dentin thickness was 0.78±0.14 mm, which was located
                                                               slices), they still could not provide a complete picture of
at a mean distance of 7.1 mm from the cementoenamel
                                                               the furcation grooves.
©




junction (CEJ) and 1.38 mm from the furcation.
                                                               Recently, a more advanced and non-destructive method
Conclusions. The presence of the furcation grooves in
the palatal aspects of the buccal roots of the MFPs was        to evaluate furcation grooves has been made available.
100%. The length, depth, location, and width of the dentin     Microcomputed tomography (MCT) scanning is a non-de-
thickness of the grooves varied in relation to tooth           structive method and, allowing the view of three-dimen-
length, bifurcation, and CEJ. These parameters should          sional structures, has promising applications in endodon-
be taken into consideration before any endodontic or           tics (24, 25). MCT has been used to investigate the
restorative procedures are performed. Reducing dentin          presence of anatomical structures (13, 26) and evaluate
width too vigorously by intracanal instrumentation can         the centering ability and efficiency of rotary systems and
predispose to vertical root fractures or perforations; if a    hand files when used for root canal preparations (27-29).


142                                                                              Annali di Stomatologia 2013; IV (1): 142-148
Microcomputed tomographic analysis of the furcation grooves of maxillary first premolars


However, to date, there are no reports on the use of         SKYSCAN, Kontich, Belgium) at 100 kV and 100 μA with
MCT scanning to assess the furcation grooves in the          a resolution of 18.6 μm and a 0.5-mm-thick aluminum fil-
buccal roots of MFPs.                                        ter and 54% beam-hardening reduction. Using NRecon
This in vitro study aimed to conduct a morphometric          software (SKYSCAN), these images were reconstructed,
analysis on the palatal grooves of the buccal roots in a     producing two-dimensional, cross-sectional slices of the




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sample of freshly extracted bifurcated MFPs using MCT.       tooth structure. Subsequently, CT Analyzer software
                                                             (SKYSCAN) was used for the linear measurements of all




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                                                             variables, including canal length (measured coronally
Materials and methods                                        from the first slice where enamel appear to the last slice
                                                             of the root dentin disappear apically) (Fig. 1), the points
Twenty-three untreated human bifurcated permanent            where the grooves begin and end (starting from the first




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MFPs were selected from a pool of teeth that were freshly    slice where grove depression appear to the last slice
extracted from an adult Saudi population for orthodontic     where the depression of the groove disappear) (Fig. 2) in
reasons and stored in 10% neutral buffered formalin.         relation to the cementoenamel juction CEJ (measured
Teeth were scanned using a MCT scanner (1172 scanner;        from the last slice show enamel on the buccal canal)




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Figure 1. Canal length.
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Figure 2. Groove start and end points.


Annali di Stomatologia 2013; IV (1): 142-148                                                                        143
S. M. Al-Shahrani et al.


(Fig. 3) and furcation, groove length, and the location of   Statistical analysis
the minimum cross-sectional canal wall thickness in the
grooves (all slices in the groove length measured and the    Collected data were statistically analyzed using SPSS 15
one with minimum cross section thickness selected and        for Windows software (SPSS Inc, Chicago, IL); Pearson
average reading were recorded) (Fig. 4).                     correlation coefficients r with two-tailed significance were




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Figure 3. CEJ measures.
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                               Distance = 0.784 mm




Figure 4. Dentin thickness measurements.


144                                                                            Annali di Stomatologia 2013; IV (1): 142-148
Microcomputed tomographic analysis of the furcation grooves of maxillary first premolars


calculated for all pairs of measurements. The test was                  The concavity of the grooves began before the bifurcation
considered statistically significant when p < 0.05.                     site in 9/23 samples (39.1%) with a mean value of
                                                                        0.47±0.43 mm and exactly where the furcation began in
                                                                        one sample (4.4%) (Fig. 6). In the rest of the samples
Results                                                                 (13/23 [56.5%]), the grooves began after the furcation with




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                                                                        a mean value 0.77±0.98 mm (Tab. 1).
Palatal invagination on the bifurcation aspect of the buc-              The groove lengths varied between 1.1-9 mm with a




                                                                                                     na
cal roots was present in all samples selected for this                  mean ±SD value of 4.7±2.08 mm; the mean ±SD cross-
study. Measurements were taken at the vertical and hor-                 sectional area with minimum palatal dentin thickness was
izontal planes (Fig. 5).                                                0.78±0.14 mm, located at a mean distance of 7.1 mm




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Figure 5. Measurements at vertical and horizontal planes.
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                                                                    Groove start


                                                                 Cross section with
                                                              minimum dentin thickness
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                                                                    Groove end




Figure 6. Sample with groove starts before furcation (a). Cross section at furcation area (b). Sample with groove starts after furcation
(c). Cross section at furcation area (d).


Annali di Stomatologia 2013; IV (1): 142-148                                                                                       145
S. M. Al-Shahrani et al.


Table 1. Mean±SD, and groove length in relation to furcation.

                                                        N                    %            Range (Min/Max)             Mean±SD

Groove begins before furcation                         13                39.10                0.10–1.60               0.48±0.43
Groove begins at furcation                              1                 4.40                    -                       -




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Groove begins after furcation                           9                56.50                0.10–3.20               0.78±0.99




                                                                                                          na
from the CEJ and 1.38 mm from the furcation (Tab. 2).                        and periradicular bone destruction (32, 33). Moreover, our
Correlation coefficients and significance between all pairs                  current technique overcomes the shortcomings of previ-
of measurements in the vertical and horizontal planes are                    ously reported techniques (16, 22). In addition, with the
presented in Table 2. Significant positive correlations ex-                  use of MCT, cross-sections can be made at a precise dis-




                                                                                                       io
ist between A and C (r = 0.62, p = 0.00), A and E (r = 0.59,                 tance from the apex, furcation, or CEJ.
p = 0.00), A and F (r = 0.44, p = 0.04), E and F (r = 0.86,                  It was possible to trace the grooves from their start points
p = 0.00), and E and G (r = 0.59, p = 0.00). The length of                   (where the concavity appears coronally) to their ends




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groove F was negatively correlated with dentin thickness                     (where the concavity disappears). The groove lengths var-
of palate wall I, that is, as the length increased, the palatal              ied between 1.1-9 mm with a mean ±SD value of 4.7±2.08
dentin thickness decreased, and vice versa (r = - 0.42, p                    mm in 39.1% of the samples, and the grooves began be-
= 0.02); a similar relationship was present between G and                    fore the furcation with a mean ±SD value of 0.47±0.43 mm




                                                                                     n
I (r = - 0.41, p = 0.05) (Tab. 2).                                           and a mean ±SD distance of 5.5±1.05 mm from the CEJ.




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Table 2. Mean, SD, correlation coefficient, and significance of measurement sites in the vertical and horizontal planes.

          Mean          SD                                      Correlation Coefficient and (Significance)


A          23.92      1.73
                                     A

                                                 nt
                                                  B
                                                .25
                                                .26
                                                                C
                                                            .62**
                                                              .00
                                                                         D
                                                                       .26
                                                                       .23
                                                                                      E
                                                                                  .59**
                                                                                    .00
                                                                                                F
                                                                                             .44*
                                                                                              .04
                                                                                                           G
                                                                                                         .41
                                                                                                         .06
                                                                                                                      H
                                                                                                                    .23
                                                                                                                    .27
                                                                                                                                -.41
                                                                                                                                 .05
                                                                                                                                    I
                                               iI
B           5.74      1.34                                  -.42*    .74**          .27      -.14       .50*       -.23         -.19
                                                              .05      .00          .24       .54        .01        .28          .37
C           9.10      1.56                                            -.17          .41      .48*        .11       .48*         -.31
                                             on

                                                                       .43          .05       .02        .61        .02          .15
D           5.56      1.05                                                          .19      -.33       .46*       -.10         -.01
                                                                                    .40       .13        .03        .65          .96
E          10.31      2.03                                                                  .86**      .59**       .43*        -.52*
                                                                                              .00        .00        .04          .01
                                   i


F           4.71      2.08                                                                               .36       .50*        -.42*
                                iz


                                                                                                         .09        .01          .02
G           7.16      1.86                                                                                        .70**        -.41*
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                                                                                                                    .00          .05
H           1.38      1.64                                                                                                      -.28
                                                                                                                                 .11
I           0.78      0.14

** Correlation is significant at the 0.01 level (2-tailed).
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* Correlation is significant at the 0.05 level (2-tailed).


Discussion                                                                   These results disagree with those of Tamse et al. (4)
                                                                             who described the grooves as concavities that begin at
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Several studies found the presence of grooves on the fur-                    the bifurcation. These findings make the CEJ a more re-
cation aspects of the buccal roots of MFPs varied be-                        liable and clinically relevant reference point than the fur-
tween 62% and 100% of cases using different evaluation                       cation.
methods (2-8), supporting the results of the current inves-                  Another interesting finding is the highly significant cor-
©




tigation.                                                                    relation between the length of canal A and the end of
Our study appears to be the first study to investigate fur-                  groove E (r = 0.59, p = 0.00); as canal length increased,
cation grooves using MCT, which made it possible to ob-                      the groove was longer and ended further from the CEJ,
tain a two-dimensional analysis of the external and inter-                   resulting in a natural thinning of the palatal dentin thick-
nal macromorphologies of the root complex. MCT is                            ness of the buccal root. Therefore, discretion should be
non-destructive and a very accurate and useful tool with                     taken to avoid over-instrumentation, especially with long
which to study external and internal tooth anatomy. Par-                     roots.
allel findings have been previously reported using MCT to                    Several studies have shown that posts must be sur-
study external and internal tooth morphologies (30, 31)                      rounded by 1 mm of sound dentin (14, 34). Other studies

146                                                                                            Annali di Stomatologia 2013; IV (1): 142-148
Microcomputed tomographic analysis of the furcation grooves of maxillary first premolars


measured the average groove depths and dentin thick-                      mesial root surface of the adolescent maxillary first bicus-
nesses at different levels (4, 8, 22). Tamse et al. (4) found             pid. J Periodontol 1985; 56:666-70.
that the concavities reach a maximum value of 0.40 mm               8.    Joseph I, Varma BBR, Bhat KM. Clinical significance of fur-
at a mean distance of 1.18 mm from the furcation, 5.3 mm                  cation anatomy of the maxillary first premolar: a biometric
                                                                          study on extracted teeth. J Periodontol 1996; 67:386-9.
from the apex, and a mean distance of 0.81 ± 0.24 mm
                                                                    9.    Gutmann JL. The dentin-root complex: anatomic and bio-




                                                                                                       li
from the invagination to the canal wall. In the present                   logic considerations in restoring endodontically treated teeth.
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                                                                                                    na
dentin thickness within the groove for each sample was              10.   Kishen A. Mechanisms and risk factors for fracture predilec-
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0.78 ± 0.14 mm, and the mean ± SD distance was 7.1 ±                      13:57-83.
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                                                                          endodontically treated teeth: a clinical survey of 36 cases.




                                                                                                 io
tion. Therefore, before any endodontic or restorative pro-
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                                                                    12.   Katz A, Wasenstein-Kohn S, Tamse A, Zuckerman O. Resid-
the dentin width too vigorously by instrumentation with ei-
                                                                          ual dentin thickness in bifurcated maxillary premolars after
ther hand files or rotary instruments could predispose to




                                                                                              az
                                                                          root canal and dowel space preparation. J Endod 2006;
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                                                                              n
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                                                                           er
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                                                                          Dent Assoc 1983; 49:61-6.
5.5 ± 1.05 mm from the CEJ. Even if the root is long
                                                                    17.   Vertucci FJ. Root canal anatomy of the human permanent


                                              nt
enough (as indicated above), there is a highly significant
correlation between the length of the tooth and the end of
the groove: as tooth length increases, the groove length-
ens and ends further from the CEJ.
                                                                    18.
                                                                          teeth. Oral Surg Oral Med Oral Pathol 1984; 58:589-99.
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                                            iI
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                                          on

quire the clinician close attention and assessment of the           20.   Deutsch AS, Musikant BL, Gu S, Isidro M. Morphological
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                                                                    21.   Lee MM, Rasimick BJ, Turner AM, Shah RP, Musikant BL,
                                 i


                                                                          Deutsch AS. Morphological measurements of anatomic
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Acknowledgment                                                            landmarks in pulp chambers of human anterior teeth. J En-
                                                                          dod 2007; 33:129-31.
Special thanks to Engineer Abdulla Bugshan Growth Fac-              22.   Lammertyn PA, Rodrigo SB, Brunotto M, Crosa M. Furca-
              Ed




tors & Bone Regeneration Research Chair for the support                   tion groove of maxillary first premolar, thickness, and dentin
                                                                          structures. J Endod 2009; 35:814-7.
and the grant of the Micro-CT Lab coded NRM 0001.
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                                                                          mography used in the analysis of the morphology of root
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148                                                                                  Annali di Stomatologia 2013; IV (1): 142-148
