History of X-ray in dentistry

D E N TA L R A D I O L O G Y I N

P E D I AT R I C D E NT I S T RY

CONTENTS

•

Introduction

•

History of X-ray in dentistry

•

Guidelines for prescribing radiographs in children

•

Behavioural consideration and management techniques

•

Radiographic techniques

•

Newer digital radiographic techniques

•

Radiation safety and protection

•

References

I N T R O D U C T I O N

• Dental radiology is considered to be best and useful diagnostic aid for proper and thorough examination of oral cavity of a child.

• It helps to arrive at a correct diagnosis, followed by a proper treatment planning.

H I S T O RY

Wilhelm Conrad Roentgen 1845 - 1923

The first radiograph – Mrs. Roentgen’s hand

Marwah N, Nonpharmacological Behaviour Management, Textbook of Pediatric Dentistry,3^rded. Jaypee;2014; 219.

I N D I C AT I O N S O F D E N TA L R A D I O G R A P H S

Positive Historical Findings

History of pain History of trauma

Familial history of dental anomalies Postoperative evaluation of healing

Previous periodontal or endodontic treatment

Prescribing Dental Radiographs for Infants, Children, Adolescents, and Persons with Special Health Care Needs. American Academy of Pediatric Dentistry, 2017; 40(6): 213-215.

Positive Clinical Signs/Symptoms

• Deep carious lesion

• Swelling

• Clinically suspected sinus pathology

• Evidence of dental and facial trauma

• Mobility of teeth

• Growth abnormalities

• Oral involvement in known or suspected systemic disease

• Large or deep restorations

• Unusual absence, eruption, spacing or migration

R A D I O G R A P H I C E X A M I N AT I O N

• 4 film series:

• 8 film series:

• 12 film series:

• 16 film series:

G U I D E L I N E S F O R P R E S C R I B I N G R A D I O G R A P H

Prescribing Dental Radiographs for Infants, Children, Adolescents, and Persons with Special Health Care Needs. American Academy of Pediatric Dentistry, 2017; 40(6): 213-215.

Age Consideration Radiograph

3- 5 No apparent abnormalities ( open contacts)

None

No apparent abnormalities ( closed contacts)

4- film survey

Extensive caries/ Deep caries Selected periapical

radiographs in addition to 4-film survey

G U I D E L I N E S F O R P R E S C R I B I N G R A D I O G R A P H

Marwah N, Nonpharmacological Behaviour Management, Textbook of Pediatric Dentistry,3^rd ed. Jaypee;2014; 219.

Age Consideration Radiograph 6- 7 No apparent abnormalities

Extensive or deep caries

8- film survey ( available by 7 years of age)

Selected periapical radiographs in addition to 8- film survey

8- 9 No apparent abnormalities or extensive or deep caries

10- No apparent abnormalities or 12 extensive or deep caries

12-film survey

12 or 16 film survey depending upon size

Marwah N, Nonpharmacological Behaviour Management, Textbook of Pediatric Dentistry,3^rd ed. Jaypee;2014; 219.

SPECIAL CONSIDERATIONS IN PEDIATRIC PATIENTS

• Introduce him to the “camera”

• Tell-show-do

• Careful words to describe the procedure

• Easiest region first

• Topical L.A. in case of exaggerated gag reflex

• Patience for repeated attempts

Tandon S. Pediatric Dentistry, 3^rd ed., Paras Medical Publishers, New Delhi, 2018.

• If the child, less than three years of age it may be necessary for the child to sit in the parent’s lap while the radiograph is exposed.

• Adequately protect parent and child with lead aprons to reduce radiation exposure.

• If the child is uncooperative, then additional restraint by a second adult may be necessary.

• Older children may also be uncooperative for a variety of reasons.

• These can range from the jaw being too small to adequately accommodate the radiograph, fear of swallowing the radiograph, fear of the procedure itself, or the patient exhibits a severe gag reflex.

• For the child with the small mouth, use the smallest size film available (size 0 film).

• Roll the film (do not place sharp bends) to allow the film to accommodate the shape of the jaw and not impinge on the soft tissues.

POSITIONING THE RADIOGRAPH

• By biting on the large positioning device and watching in a mirror they are assured they will not swallow the radiograph

• A self sticking sponge tab may also reduce impingement of the radiograph on the intraoral soft tissue.

DESENSITIZATION

• Desensitization is defined as gradually exposing child to new stimuli or experiences of increasing intensity.

• Example of desensitization is “Lollipop Radiograph Technique.”

• Child is given a lollipop to lick (preferably sugarless).

• After a few licks, lollipop is taken from child and radiograph is attached to lollipop using an orthodontic rubber band.

• Child is made to hold the lollipop and radiograph in his mouth while we take a tooth picture.

Tandon S. Pediatric Dentistry, 3^rd ed., Paras Medical Publishers, New Delhi, 2018.

TECHNIQUES-

MANAGING GAG PATIENTS

• Easiest is through diversion & positive suggestion.

• Reduced by concentrating on something other than procedure.

• Patient’s palate can be sprayed with topical anesthetic.

• Use of nitrous oxide analgesia.

• Another alternative- Place radiograph that doesn’t contact palate or tongue. Extraoral placement of film or placing film between cheek and tooth, exposing film from opposite jaw. Film side of packet (solid color side) is facing buccal surface of tooth.

• X-ray head is placed at opposing side, and cone is positioned under angle of ramus on opposite side.

• As x-ray beam is traveling a longer distance to film than in typical positioning, necessary to double exposure time.

• It is imperative that after mounting radiographs are reversed.

• Incorrect mounting and labeling of the reverse radiograph can result in misdiagnosis and treatment of wrong tooth.

1 . P a r a l l e l l i n g Te c h n i q u e:

T E C H N I Q U E S

2 . B i s e c t i n g A n g l e Te c h n i q u e

T E C H N I Q U E S

Difference in techniques

Bisecting angle technique Parallel technique

Image distortion Slight image distortion

Superimposition of zygomatic process

Control of shadow of zygomatic process

Anatomical relationship altered Correct anatomical relationship Crown- root ratio is not preserved Crown-root ratio is preserved Poor image standardization and

reproducibiliy

High image standardization and reproducibility

No need of film holding device Need of film holding device

• Paralleling technique has geometric advantage over bisecting angle technique, so it has comparatively less distortion.

• However, bisecting angle technique is more appropriate when it comes to patient’s comfort and is more recommended in pediatric population.

Ibrahim MF, Azif MS. Comparison of paralleling and bisecting angle technique in endodontic working length radiography. Pakistan oral and dental Journal, 2013; 33: 160-164.

SIZES OF INTRA ORAL FILMS

X-RAY TUBE:

• Cathode accelerates electrons & leads them to anode(electron beam).

• Only a small portion of electron beam is converted to x-rays.

• Beam of x-ray passes out from the x-ray tube.

RADIOGRAPHIC TECHNIQUES USED IN CHILDEN

Intraoral-

• Intra oral periapical

• Bite wing

• Occlusal

Extraoral-

• Panaromic radiograph

• Radiography of Paranasal sinuses

• Radiography of mandible

• Radiography of TMJ

• Radiography of zygomatic arches

• Radiography of the skull

INDICATIONS:

• To evaluate development of root end & study periapical tissue.

• Assess depth of dental caries.

• Assess alterations in integrity of periodontal membrane.

• Evaluate prognosis of pulp treatment by observing health of periapical tissues.

• Identify stage of development of unerupted teeth.

• Detect developmental abnormalities like supernumerary, missing or malformed teeth.

PERIAPICAL

RADIOGRAPH

Posterior maxillary +30 degree

Posterior mandibular - 10 degree

Anterior maxillary +45 degree

Anterior mandibular -15 degree

BITEWING RADIOGRAPH

INDICATIONS:

• Early detection of incipient interproximal caries

• Understand configuration of pulp chamber

• Record width of spaces created by premature loss of deciduous teeth

• Determine relation of tooth to occlusal plane for possibility of ankylosis

• Detect levels of periodontal bone at interdental area

• Detect secondary caries

I N D I C AT I O N S -

• Determine presence, shape & position supernumerary teeth

• Determine impaction of canines

• Assess extent of trauma to teeth and anterior segments arches

• In case of trismus & trauma, where patient cannot open mouth completely

• Determine medial and lateral extent of cysts & tumors.

• Localize foreign bodies in jaws & stones in ducts of salivary glands.

OCCLUSAL

RADIOGRAPH

E X T R A O R A L T E C H N I Q U E

RADIOGRAPHY OF PARANASAL SINUSES

1. Standard Occipitomental Projection

2. Modified method (30 degree OM)

3. Bregma Menton

4. PA Water’s

RADIOGRAPHY OF MANDIBLE

1. PA Mandible

2. Rotated PA Mandible

3. Oblique lateral radiography

I. True laterals

II. Oblique laterals

III. Bimolars (two oblique laterals on one film).

RADIOGRAPHY OF BASE OF SKULL Submento-vertex projection

RADIOGRAPHY OF ZYGOMATIC ARCHES

Jughandle view (A modification of submentovertex view)

RADIOGRAPHY OF TEMPOROMANDIBULAR JOINT

1. Transcranial Projection

2. Transpharyngeal projection

3. Transorbital projection

RADIOGRAPHY OF THE SKULL.

1. Lateral Cephalogram

2. True lateral (Lateral Skull) 3. PA Cephalogram

4. PA Skull

5. Towne’s projection

6. Reverse Towne’s projection

STANDARD

OCCIPITOMENTAL

PROJECTION

MODIFIED METHOD

(30 DEGREE OM)

SUBMENTO-VERTEX

PROJECTION

PA VIEW OF SKULL

LATERAL

CEPHALOGRAM

TRANS CRANIAL VIEW OF TMJ

PA N A R O M I C

R A D I O G R A P H p h

• It is a technique for producing a single tomographic image of facial structures that includes both maxillary and mandibular arches and their supporting structures.

I N D I C AT I O N S

• Diagnose missing and supernumerary teeth.

• Detect gross pathologies.

• Asses development of the dentition.

• Detect bone fractures, traumatic cysts.

• In some patients with disabilities (if the patient can sit in a chair and hold head in position).

 RadioVisiography

 Xeroradiography

 Subtraction radiography

 Computed tomography

 Cone beam computed tomography

 Tuned aperture computed tomography

A D VA N C E D R A D I O G R A P H I C T E C H N I Q U E S

• Method of capturing a radiographic image using sensor, breaking it into electronic pieces, presenting & storing image.

• DIRECT DIGITAL IMAGING- a digital sensor used

• CCD

• CMOS

• INDIRECT DIGITAL IMAGING- Uses film like photo phsphor plates that are activated using X-rays, then scanned in special devices that read images from plate.

• ADVANTAGES-

• Working time reduced.

• Chemical processing is avoided.

• Exposure to radiation is reduced.

• Cephalometric meaurements and analyses can be more easily performed with the aid of task dependent software.

• Storage and communication are electronic

D I G I TA L R A D I O G R A P H Y

R A D I O V I S I O G R A P H Y

• System is capable of rapidly displaying a digital radiographic image on a monitor with a 80% radiation dose reduction when compared with conventional radiography

• Major components of RVG system include an X-ray head with an advanced timer, radiographic sensor connected to a charged coupling device (CCD), monitor for image display & computer with appropriate software for image storage and manipulation.

• Introduced by Mouyen et al in 1989

MERITS-

• Image processing time is very short being about 5 seconds.

• Sensors can be easily moved from operatory to operatory, allowing operators to work with a minimum number of sensor and within a computer network environment.

• Problems caused by processing faults are eliminated.

• Opportunity to enhance images for more precise viewing.

DEMERITS-

• Sensors are thicker than films and cables running off sensor which some patients don’t tolerate well.

• High cost of sensor

• Difficulty in placing sensor due to its rigidity.

X E R O R A D I O G R A P H Y

• Records images without film

• Consist of images receptor plates- selenium particles

• Latent image is converted to a positive image.

ADVANTAGES

• Reduced radiation dose

• Image can be produced in 20 seconds

• Ability to have both positive and negative prints

• Two times more sensitive than conventional D-speed films.

• Improves visualization of files and canals.

DISADVANTAGE-

• Exposure time varies according to thickness of plate

D I G I TA L S U B T R A C T I O N R A D I O G R A P H Y

• Method by which structured noise is reduced in order to increase detectability in radiographic pattern.

• Image–enhancement method– area displayed against a neutral background

• Standard radiographs are produced with identical exposure geometry

• If there is change in radiographic attenuation between baseline and follow up examination, this change shows up as a brighter- if there is Gain. And darker area, when change represents Loss

• Strength of digital subtraction radiograph is that it cancels out complex anatomical background against which this change occurs.

C O M P U T E D TO M O G R A P H Y

• CT has evolved into an indispensable imaging method in clinical routine.

• Images are not biased by superimposition of anatomical structures

• CT yields images of much higher contrast.

CONE BEAM COMPUTED TO M O G R A P H Y

• CBCT is an X-ray imaging approach that provides high resolution 3-dimensional images of the jaws and teeth

• CBCT shoots out a cone shaped X-ray beam and captures a large volume of area requiring minimal amounts of generated x-rays.

• Within 10 seconds, machine rotates around head and captures 288 static images.

• ADVANTAGES-

• Precise identification and detection of periapical lesions

• Complete 3-D reconstruction and display from any angle.

• Patient radiation dose 5 times lower than conventional CT

• Excellent resolution

• Require only a single scan to capture the entire object with reduced exposure time.

TUNED APERTURE COMPUTED TOMOGRAPHY

• Improve accuracy in caries diagnosis because of its 3-D or pseudo 3-D capabilities.

Principle of TACT

• TACT slices can be produced from an arbitary number of X- ray projections, each exposed from a different angle.

• Using TACT , it is possible to use one X-ray source and move it through several points in space or use several fixed sources to collect multiple X-ray projections which in turn can be processed to produce TACT slices

Radiation Safety In Dental Practice - A Study Guide. California Dental Association, 2014: 2-69.

Any exposure, however small it may be, can produce harmful effects

R A D I AT I O N S A F E T Y &

P R O T E C T I O N

CRITICAL ORGANS & ASSOCIATED ADVERSE BIOLOGIC EFFECTS-

• The skin (cancer)

• Red bone marrow (leukemia)

• The gonads (mutation, infertility and fetal malformations)

• The eyes (cataracts)

• The thyroid (cancer)

• The breasts (cancer)

• The salivary glands (cancer)

S o u rc e of r a d i a t i o n in d e n t a l r a d i o l o g y d e p a r t m e n t

• Primary beam- radiation originating from focal spot

• Secondary radiation-originating from irradiated tissue of patient.

• Leakage or stray radiation- leaked radiation from X-ray tube

• Scattered radiation – from filters and cones, coming from objects other than patient such as walls and furnitures that the primary beam may strike

Means of protection can be divided into:

1. Protection for operator

2. Protection for patient

Radiation Safety In Dental Practice - A Study Guide. California Dental Association, 2014: 2-69.

I . PROTECTION FOR OPERATOR-

• Effort must be made so that operator can leave room or can take a suitable position behind a barrier.

• If there is no barrier operator should use lead aprons

• Film should never be held by operator .

• Ideally, film holding devices should be used .

• If correct retention or placement is still not possible a parent must hold film in position.

OPERATOR LOCATION-

• The operator of dental unit must stand at least 6 feet from useful beam or behind a protective barrier.

• Stand at an angle of 90 to 135 degrees from central ray.

• DO NOT stand in path of primary x-ray beam.

1 . R e q u i r e d D i s t a n c e s -

• Use of long source to film distance of 40cm(16inch), rather than short distance of 20cm, decreases exposure 10-25%.

Distances between 20 cm-40 cm are appropriate.

2 . C o l l i m a t o r s-

• Collimators limit size and shape of Useful beam which reaches patient.

• X-ray field must be limited to circle having a diameter of no more than 7 cm [~3 in].

• Rectangular collimators are recommended for periapical radiographs as their use significantly reduces area of patient’s body that is exposed to radiation

II. PROTECTION FOR PATIENT-

Radiation Safety In Dental Practice - A Study Guide. California Dental Association, 2014: 2-69.

3 . C o n e s -

• ADA discourages use of short, closed, pointed cones because of increased scatter radiation close to face and adjacent areas of patient’s body.

4. S y s t e m S p e e d-

• Faster image receptor systems result in decreased radiation exposure to patient.

5. T h y r o i d-

• Thyroid gland, especially in children, is among most radiosensitive organs. Thyroid shield may reduce dose to gland without interfering with obtaining a diagnostic image.

LEAD APRONS & SHIELDS-

• Even though dose from digital radiography is less than conventional radiography, patients should be shielded with lead aprons

& thyroid shields.

• Shields should have at least 0.5 mm of lead or equivalent.

• Do not fold or bend aprons.

• Hang aprons to prevent damage &

loss of protective qualities.

Radiation Safety In Dental Practice - A Study Guide. California Dental Association, 2014: 2-69.

• The use of proper and innovative radiographic techniques can help the dentist to obtain diagnostic radiographs with minimum harm and maximum comfort for the pediatric patient.

• The dentist should use every means to reduce unnecessary exposure to their patients and themselves.

• This philosophy of radiation exposure is often referred to as principle ALARA- As Low As Reasonably Achievable.

CONCLUSION

REFERENCES

• Dean JA. McDonald and Avery’s Dentistry for the child and adolescent, 1^st South Asia ed.

Elsevier, New Delhi, 2016.

• Tandon S. Pediatric Dentistry, 3^rd ed., Paras Medical Publishers, New Delhi, 2018.

• White SC, Pharoah MJ. Oral Radiology- Principles and Interpretation. 1^st South Asia Edition.

• Marwah N, Nonpharmacological Behaviour Management, Textbook of Pediatric Dentistry,3^rd ed. Jaypee;2014; 219.

• Prescribing Dental Radiographs for Infants, Children, Adolescents, and Persons with Special Health Care Needs. American Academy of Pediatric Dentistry, 2017; 40(6) :213-215.

• Madan K, Baliga S, Thosar N, Rathi N. Recent advances in dental radiography for pediatric patients: A review. Journal of Medicine Radiology Pathology and Surgery, 2015; 1:21-25.

• Ibrahim MF, Azif MS. Comparison of paralleling and bisecting angle technique in endodontic working length radiography. Pakistan oral and dental Journal, 2013; 33: 160-164.

• Kumar R, Khambete N, Priya E. Extraoral periapical radiography: An alternative approach to intraoral periapical radiography: Imaging Science in Dentistry; 2011; 41:161-5.