Introduction
Periodontal disease is considered being a dreadful microbial disease that affects
tooth-supporting structures.[1 ] Extensive case recording and radiological evaluation are crucial for successful
treatment outcomes in such patients.[2 ] The conventional periodontal diagnostic approaches include recording pocket probing
depth, bleeding on probing, clinical attachment loss, and intraoral radiography, which
plays a vital role in diagnosing the type and amount of alveolar defect.[3 ] At present, conventional diagnostic techniques have drawn various limitations that
have put clinicians to look at other alternative methods, which would help provide
a better diagnosis.
Intraoral radiography is the most familiar diagnostic technique used in periodontics.
Its major limitation is its inability to provide a three-dimensional (3D) view of
the anatomic structures. Hence, it can affect the interpretation and identification
of the defect. The technique also underestimates the amount of bone loss and fails
in identifying various anatomical landmarks.[4 ]
[5 ]
[6 ]
With the introduction of computed tomography (CT) to the medical field, the possibility
of visualizing through a 3D image has come true. However, the high cost incurred by
the tool and the amount of radiation emitted by it limit the usage of this technology
in the dental field.
Cone-beam computed tomography (CBCT) is comparatively a newly emerged diagnostic technology.
They have received massive appreciation in dental maxillofacial surgery.[7 ]
[8 ]
The technique offers numerous advantages, such as the low cost incurred by the equipment
and lower radiation emission.[9 ] The method uses an X-ray source that produces a cone beam of radiation, unlike in
CT, where it emits a fan beam-like radiation.[10 ]
The system consists of a flat panel detector, an image intensifier, and a detector.
The source and detector directly connect to a platform to produce sequential planar
images as the sensor rotates around the object. The entire scanning completes in a
single rotation. Therefore, it can tremendously reduce the radiation exposure to the
person.[11 ] When we compare the exposure dose of panoramic radiograph with that of periapical,
it is around 0.0063 and 0.0012 mGy, respectively.[12 ] Reports also suggest a dose range within 33 to 84 Sv for performing intraoral estimation.[13 ]
The application of CBCT widely spreads among fields including dentoalveolar surgeries,
implantology, general/specialized dentistry (orthodontics, periodontics, endodontics,
and forensic dentistry).[14 ]
[15 ]
[16 ]
[17 ]
The article here focuses on the different applications of CBCT in the field of periodontics.
Soft Tissue Assessment
Assessing facial soft tissue thickness plays an integral role in the treatment plan
and the degree of success in various periodontal procedures. Even though several methods
have emerged to measure soft tissue, the accuracy of these techniques is still under
debate.
The literature provides numerous studies supporting the application of CBCT to determine
the measurements of hard tissue, while publications are very scarce concerning soft
tissue assessment.[18 ]
In a study conducted by Alessandro et al in 2008, they devised a new technique based
on the principle of CBCT, known as soft tissue CBCT (ST CBCT), which helps visualize
and estimate the distances respective to hard–soft tissues as well. The technique
was simple and non-invasive. Thus, clinicians found it helpful in determining the
association between various structures of the periodontium.
Three patients with distinct periodontal biotypes were asked to obtain two separate
CBCT scans for the study. The first scan followed the standard methods, while the
second used the ST CBCT method. The routine scan could only procure the distance between
the cementoenamel junction and the facial bone crest and the width of the alveolar
bone. In contrast, the ST CBC scans showed better visualization and accurate measurements
of periodontal structures.[19 ] Thus, the latter plays a significant role in determining the dimensions of various
structures in the periodontium.
However, certain studies have depicted that the technique can't be used as a precise
tool for assessing soft tissues.
A study conducted by Gupta et al in 2015 evaluated the thickness of palatal masticatory
mucosa through the CBCT scan, along with bone sounding conducted on 20 patients assigned
palatal surgery. They found no significant differences among the two groups. However,
the results could not be generalized as the sample size was inadequate and not accurately
determined ([Table 1 ]).[20 ]
Table 1
CBCT studies assessing soft tissue components as listed by Ashwini S et al (2017)
Author
Study design
Proband characteristics
Radioigraphic assement
Accuracy
Potential benefit
Januário 2008
Cross sectional
Three patients with different periodontal biotypes.
Two separate CBCT scans.
First scan: standard methods used.
Second scan: ST- CBCT.
First scan: measurements of the distance between the CEJ and the facial bone crest
and the width of the facial alveolar bone.
ST-CBCT: measurement of the distance between the gingival margin and the CEJ and width
of the facial gingiva.
ST-CBCT scans may allow clear visualization, measurements, and analysis of the relationship
of the structures of the periodontium and dentogingival attachment apparatus
Barriviera et al. 2009
Cross sectional
Thirty-one patients (11 males and 20 females; age ranging from 19 to 53 y).
CBCT scans: thickness of the palatal mucosa was obtained at 40 different locations.
Average thickness of the palatal mucosa: 2.92 mm in the canine area, 3.11 mm in the
first pre-molar, 3.28 mm in the second pre-molar, 2.89 mm in the first molar, and
3.15 mm in the second molar.
CBCT may allow the determination of the dimensions of the palatal mucosa.
Ueno et al. 2014
Retrospective
CBCT images of 44 subjects (Japanese population; 22 males and 22 females; age ranging
from 19 to 77 y).
Measurements on the coronal plane in 3-mm interval in the canine, first and second
premolar, mid-point between first and second, and first and second molar.
Palatal mucosa: thickest between canine and premolar regions was 9 to 12 mm from the
gingivolal margin.
CBCT can be used for evaluating the thickness of palatal mucosa.
Yilmaz et al. 2015
Retrospective
CBCT images of 368 patients (181 males and 164 females; age ranging from 15 to 69
y).
Thickness of palatal mucosa measured.
Greater palatine foramen location in relation to the tooth determined.
The mean palatal mucosal thickness from second molar to the canine teeth was 3.7,
3.3, 3.7, 3, and 3 mm.
The second premolar to second molar zone can be considered a suitable graft site based
on the mean palatal mucosal thickness.
Gupta et al 2016
Cross sectional
20 systemically healthy subjects (10 males and 10 females; age ranging from 19 to
53 y) requiring palatal surgery.
Thickness of the palatal tissue measured and various points using CBCT scans and clinically.
Clinical and radiographic methods comparison showed no significant difference.
CBCT may be used as a non-invasive method to accurately and consistently determine
the soft tissue thickness of the palatal masticatory mucosa.
Abbreviations: CBCT, cone-beam computed tomography; CEJ, cementoenamel junction; ST-CBCT,
soft tissue CBCT.
Periodontal Ligament Space
The status of the lamina dura in a radiograph marks as an early sign for the detection
of periodontitis. Periodontal diseases are accompanied in most cases by a discontinuity
of the lamina dura.
An imaging technique with a higher sensitivity would be required to detect variations
in the periodontal ligament space. As conventional imaging modalities pose several
disadvantages such as overlapping, processing errors, or errors in patient positions,
clinicians look forward to novel innovations like CBCT to address these issues.[21 ]
Ozmeric et al compared CBCT and conventional radiographs by creating an artificial
periodontal ligament space in a phantom model. The results showed that periapical
radiographs were superior to CBCT in regard to estimating the periodontal ligament
space.[22 ]
A series of in vitro studies were used in an artificial periodontal ligament (PDL)
model to compare the images of CBCT and radicular grooves (RGs). The images were presented
to 20 people including dentists, dental assistants, and students. Weeks later, the
same photos were mixed and given to the same subjects. The results showed a significant
difference, where RGs elicited better images compared with CBCT.
However, detailed studies on assessing minor slice/window level techniques for image
optimization are required to validate these results further.[23 ]
Alveolar Bone Defect
The accurate detection of the alveolar bone defects depends upon the precision of
the radiograph taken. Usually, 2D radiographs are insufficient for evaluating bone
defects. This is due to various reasons such as obstruction of spongious bone changes
in the cortical plate or blurring of anatomic bone structures.
With the addition of a third diagnostic plane, images generated were more precise
and accurately determined, especially in a buccolingual direction.[24 ]
A study conducted by Balasundaram in 2014 showed CBCT scanners as a reliable source
for quantitative information on periodontal bone levels. However, accuracy in the
anterior jaw was unsatisfactory.[25 ]
Another study conducted by Vandenberghe et al compared defect measurements in CBCT
with intraoral digital radiographs. The results showed intraoral imaging with a better
image detail accuracy, while CBCT illustrated a more appropriate morphological assessment
of defects.[26 ] However, in cross-sectional sections, CBCT measurements were considered to have
better accuracy than digital imaging.[27 ]
Similarly, Misch and colleagues suggested that the CT system exhibited intraoral measurements
as equivalent and authentic as clinical calibrations and radiographs.[28 ]
In a case report by Mohan et al in 2014, a patient reported with a complaint of loose
teeth. Clinical and direct digital radiography failed to accurately assess the extent
of the periodontal lesion. With the means of CBCT imaging, the detailed morphology
of the defects was attained. Post-surgically, the CBCT measurements were also found
to be exactly identical to the actual intrasurgical measurements ([Fig. 1 ]).[29 ]
Fig. 1 3D volumetric CBCT images (a , b , c , d ), in the areas of maxillary and mandibular arch with 2D digital periapical radiographs
(e , f , g , h ) from the study by Mohan et al.[29 ]
Mengel et al and Noujeim et al were few among the many remaining authors who have
also validated the potentiality of this approach in estimating intrabony defects in
their studies.[30 ]
[31 ]
A systematic review done by Haas et al assessed the capability of CBCT in estimating
alveolar defects. The results showed a moderate amount of evidence, supporting its
role as an appropriate imaging modality, yet also mentioned not to be selected as
clinicians first choice for Perio assessment.[32 ]
Also, available literature was unable to arrive at a consensus regarding the efficacy
between CBCT and in situ measurements. Studies constantly depicted contradictory results.
A possible technical limitation of under- or over-estimation of values was pointed
out by numerous clinicians through this scan. A valid justification for this could
be the differences in the voxel sizes.[33 ]
[34 ]
The influence of co-variables such as the probing force, probe diameter, and presence
of granulation tissue may also suggest the discrepancies between the two routes.[27 ]
[33 ]
Moreover, access and visualization pose a challenge in direct clinical calibration.[35 ]
Furcation Involvement
Furcation involvement commences once the attachment loss progresses up to the level
of root furcation. Furcation involvement possesses two components: horizontal defect
depth and vertical depth. Anatomical variations like cervical enamel pearls, length
of root trunk, root anatomy, and root entrance dimensions can influence horizontal
and vertical dimensions.
An integral step in assessing furcation involves estimating radicular bone loss. Conventional
radiographs, however, might fail in determining the bone support in the intraradicular
area, especially in the maxillary molar area.
CBCT images have provided detailed data on the furcation involvement of maxillary
molars.[36 ] Umetsubo et al in their in vitro study done in pig mandibles reported that CBCT
images showed an accuracy within a range of 78 to 88%, suggesting its potentiality
in the detection of furcation defects.[37 ]
In the in vitro assessment conducted by Vandenberghe et al, he compared the results
obtained from cone-beam and intraoral radiography. They concluded that the latter
failed to accurately detect crater defects and furcation involvement in approximately
29 and 44% of cases, respectively, while CBCT demonstrated 100% detectability for
both cases.[27 ]
Similarly, Walter et al reported 84% data accuracy in surgical assessments taken before
and after the furcation surgery in maxillary molars of 14 selected subjects. His reports
suggested CBCT holding more weightage compared with conventional and clinical measurements.[36 ]
Milena et al from Belgrade University Serbia conducted a clinical examination to compare
the diagnostic efficiency in clinical probing and cone-beam radiography for furcation
involvement in periodontitis patients. Furcation was assessed at three sites in maxillary
molars and two sites in mandibular teeth. The number of diseased sites revealed by
CBCT was higher compared with digital probing after the study, hence supporting its
adjunctive role in FI assessment. Buccal furcation involvement was denoted positive
in CBCT scans but was unable to be detected clinically by probing.[38 ]
Pajnigara et al conducted a study to assess the dimensions of furcation defects clinically,
intrasurgically, and through CBCT. Pre- and post-surgical evaluation and photographs
were taken by the clinicians after 6 months. The study group consisted of 40 subjects
with grade II furcation defects, treated with demineralized freezed-dried allograft.
Statistical significance was noted between pre-surgery clinical and CBCT measurements
with post-surgery CBCT and clinical values in vertical and horizontal aspects of the
defect. The authors suggested that CBCT is an advisable diagnostic tool in furcation
defects for advanced periodontal disease ([Figs. 2 ] and [3 ]).[39 ]
Fig. 2 Pre-operative measurements of furcation defects from Pajnigara et al study.[39 ] (a ) Clinical measurement of the vertical component. (b ) Intrasurgical measurement of the vertical component. (c ) CBCT measurement of the vertical component. (d ) Clinical measurement of horizontal component. (e ) Intrasurgical measurement of horizontal component. (f ) CBCT measurement of horizontal component.
Fig. 3 Post-operative measurements of the same furcation defects. (a ) Clinical measurement of the vertical component. (b ) CBCT measurement of the vertical component. (c ) Clinical measurement of horizontal component. (d ) CBCT measurement of horizontal component.
Furcation-involved teeth usually possess less successful treatment outcomes and a
poorer long-term prognosis. Accurate detection in such cases is, therefore, crucial
in formulating an appropriate treatment plan. Thus, CBCT enables the clinicians to
adequately visualize the furcation defects and compare the data with clinical measurements
to manage such clinical cases efficiently.
Regenerative Periodontal Therapy and Bone Graft
Cone beam techniques were also investigated for bone level detection following regenerative
periodontal procedures.
A similar study was conducted by Grimard et al who compared direct clinical, periapical
radiograph, and CBCT measurements for detecting bone-level differences. They evaluated
the changes in 35 intrabony defects, which were followed by regenerative periodontal
therapy. CT provided more definitive measurements compared with periapical radiographs.
Thus, it is inferred as a potential tool that can prevent surgical re-entry as a technique
for assessing regenerative periodontal therapy outcomes.[40 ]
In 2010, Ito et al investigated the role of CBCT for the ideal placement of GTR membrane
in inter-proximal defects. It allowed for detailed visualization of the characteristics
of alveolar defects in all three dimensions. Using a template in axial dimension for
the membrane made clinicians easier to arrive at a definitive conclusion. The membrane
was easily adaptable over to the root surface on both the arches by using a template.
The dimensions of the membrane were altered when viewed without CBCT. It also presented
a shorter membrane trimming time and better accurate measurement in the volume assessment
of bony defects and bone graft used in cleft surgeries.[41 ]
CBCT in Implant Dentistry
Radiographs play a crucial role in implant dentistry in assessing the bone levels
and determining the prognosis of treatment outcomes.
Hu et al, in their study, evaluated the reliability of two pre-surgical radiographic
methods, i.e., panoramic radiography and CBCT, in implant planning concerning specific
regions (maxilla and mandible). The results suggested that in mandible, digital panoramic
radiography was safer to perform, while in maxilla, CBCT was better recommended.[42 ]
A study by Ekrish et al attempted to investigate the effect of exposure time on the
accuracy of CBCT in implant sites on a dry skull. He found that reduced dose exposure
time has no significant impact on the accuracy of the site measurements.[43 ]
Various other articles also suggest its ability to limit the rate of implant failures
to a certain extent by providing the necessary information regarding the density,
shape, height, and width of the alveolus at the implant site.[44 ]
