Clinical Aspect and Applications of

CBCT

Author: Lokender Yadavwww.lokender.in

What is CBCT or DVT ? A cone beam CT scanner uses x-rays and computer graphic interfaces to produce 3D cross sectional images of the

jaws and teeth. Through the use of a cone shaped x-ray beam, and ultra low dose function, the time needed forscanning and radiation exposure are all much reduced, compared to traditional methods.

The machine moves around the patient’s head in a circular motion in a similar way to the panoramic radiographyunits.

www.lokender.in

CBCT

Cone Beam Computed Tomography

X-RAY

SOURCE

DETECTOR

CENTRE OF

ROTATIONUsing a sensor and X-ray source we

are able to acquire a volume of data

The system rotates around a central

point acquiring:

“image cross sections”

These cross sections are processed

by reconstruction software to produce

a cylindrical volume matrix

The resulting volume is a cylinder of data,

◦ whose height would equal the height of the

detector

◦ and whose radius would equate the width of

the detector

“WOULD”

If magnification factor did not come into the

play

◦ this is the difference between detector size

and field of view

The reconstruction algorithm should take into

account the magnification factor thus ensuring

objects are represented as “true” size

FOCAL

POINT

DETECTOR SIZE IS GREATER THAN

FIELD-OF-VIEW SIZE

Field of View

The resulting 3D volume following reconstruction.

Basic planes

AXIAL CORONAL SagittalGtIT

TALAxial Coronal

AXIAL CORONAL SAGITTAL

Displaying 3D aquisition

Following reconstruction the imaging software will show for example, the volume, projection

planes, MPR, simulated 2d, etc.

AXIALCORONAL

SAGITTAL2D

CBCT in dental Implantology..

◦ CBCT has revolutionized the way dental implant is

performed in dental clinics & hospitals.

Need of 3D in implant…

◦ To improve the overall success of implant therapy

with possible reduction in surgical and postoperative

implant complications, implantologist should 3D

information of :

◦ Bone volume

◦ Bone Topography

◦ Bone Density

◦ Proximity to anatomical structure

What doctor wanted to see as an implantologist?

Ridge Morphology :

◦ The Buccolingual ridge pattern cannot be viewed on 2D radiograph but CBCT come with advantage of showing the ridge pattern present.

◦ Ridge may be:

◦ Irregular

◦ Narrow Crestal

◦ Knife shape

◦ Case of Compromised jaw bone

◦ (quantity or quality)

◦ (2D is insufficient)

Quality of bone at site of implant

◦ The bone quality is most important marker/information for

implant planning(In determining the success of Implant),

◦ Type-1

◦ Type-2

◦ Type-3

◦ Type-4(higher chance of failure compare to other types of

bone)

◦ *Bone density is subjected to mineral density & bone

structure

CBCT-Guided Implant Surgery

Type and size of the planned implant, its position

with in the bone, its relationship to the planned

restoration can be determined before performing

surgery ,

◦ Implant Guide helps:

virtual planning

Allowing for more accurate and predictable implant

placement

Reduced Chances of Medical Errors

Requirement of Virtual Implant Planning

◦ Three or more implants in a row

◦ Proximity to vital anatomical structure

◦ Questionable bone volume

◦ Flapless implant placement

◦ Immediate placement

◦ Implant position that is critical to the planned

restoration

CBCT in oral and Maxillofacial surgery:

Third Molar Evaluation:

◦ Third molar removal in young adults reported frequently at

clinic's. IAN(Inferior Alveolar Nerve) is a serious complication in

third molar removal. So it becomes important to pre assess. In

case of overlapping impacted tooth with mandibular canal, IOPA

or Pano view provides a limited information

Maxillofacial Trauma

◦ Dentoalveolar fracture, Maxillary Bone fracture,Zygomatic fracture, Madibular Fracture, or gunshotinjuries .

◦ CBCT is more sensitive and accurate in imagingthe maxilla and mandible.

◦ It is reported that Mandibular Fractures that are notevident in conventional CT can be Identified usingCBCT.

◦ CBCT uniquely useful in the diagnosis of alveolarfractures.

Maxillofacial Region

Bone Graft Analysis:

◦ Volumetric analysis offers better prediction of defect

morphology(e.g. cleft palate) ,understanding the

morphology of a traumatic defect is critical in

developing the implant site before planned implant

placement.

Temporomandibular Joint Assessment

◦ TMJ disorders are often quite challenging.

◦ CBCT should be considered for:

◦ Limitation in mandibular movement and function

◦ Stiffness of jaw

◦ Pain in the TMJ upon palpation are present

◦ Evolution of bony changes of the TMJ

Craniofacial Surgery:

◦ Cleft lip and palate pose unique challenges to

dentists.

◦ Timely treatment is important , young age of

patient and concern surrounding radiation

exposure, Conventional CT is not always useful.

◦ CBCT is a reliable tool for volumetric assessment

of bone defects in alveolar and palatal regions.

Orthognathic Surgery

◦ Lateral Ceph view is a standard image modality

when diagnosing skeletal & dental deformities.

◦ Superimposition of right and left side along with

machine magnification ,accurate surgical

prediction and treatment planning become difficult.

◦ CBCT can be a better choice

◦ Cases: hemifacial microsomia , severe facial

asymmetries etc.

CBCT in Endodontics:

Assessment of root canal morphology

◦ Second Mesiobuccal canal(MB2) in maxillary first

molar vary from 70-90%, this variability occurs in

the Buccolingual plane, where the superimposition

of anatomical structures impedes the detection of

small structural density changes.

Dental Periapical Pathoses

Most common pathologic condition that involves teeth have inflammatory lesions of the pulp and periapical areas, lesions confined to cancellous bone with little or no cortical plate erosion is difficult to diagnose with intraoral modality

Root Fractures

◦ CBCT in diagnosis and management of specific

aspects of Dentoalveolar trauma, especially root

fractures, luxation, displacement and alveolar

fracture.

Root Resorption

◦ Root resorption is the loss of dental hard tissues

as a result of clastic activities(Int & Ex).

Postoperative Assessment

◦ Healing of apical lesions is an important aspect of

postoperative assessment in endo, adequacy of

root canal obturation is a important determinant of

endodontic success, integrity of root canal fillings,

precise nature of perforation etc.

CBCT in Orthodontics:

◦ CBCT images for Cephalometric analysis

◦ Tool for assessing facial growth ,age, airway function and disturbance in tooth eruption.

◦ Orthodontic assessment tools: Dolphin(USA), Invivo Dental (USA), allow dentist to work on CBCT images for orthodontic assessments.

◦ CBCT : proximity to impacted tooth, check for orthodontic movement space, assessing bone density before after during treatment

CBCT in Periodontics:

Assessment of bone loss amount and available bone due to

projection errors.

2D underestimate such assessments.

Other applications are

◦ Periodontal cyst

◦ Intrabony defects

◦ Small osseous defects

CBCT in Forensic Dentistry

◦ Age Estimation

◦ Pulpo-dential complex(Dentin ,cementum and pulp) shows

physiological and pathological changes with advancing

age

◦ (basically extraction and sectioning is required to quantify

but CBCT is a more viable option )

◦ Visualization of cervical vertebral morphology gives

footprint for skeletal age assessment, segmentation of

individual vertebrate is possible using CBCT

CBCT in OSA(Obstructive Sleep Apnea )

3D airway imaging : It is possible to make airway minimum

cross sectional area and volumetric assessment .

CBCT in ENT

◦ Inflammatory Pathology

◦ Fungal Sinusitis

◦ Tumoral Pathology(NC)

◦ Temporal Bone Assessment

◦ Sinuses and nasal fossae

T AH N K

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