supplementary diagnostic aids in orthodontics

Supplementary diagnostic aids

B.SRINIVASANKIDS

ESSENTIAL DIAGNOSTIC AIDSEssential diagnostic aids, as the name suggests are considered essential for the

diagnosis of an orthodontic case. Ideally before starting a case, a treating clinician

must possess these aids.

1. Case history

2. Clinical examination

3. Study models

4. Certain radiographs:

a. Periapical radiographs

b. Lateral radiographs

c. Orthopantomograms

d. Bite wing radiographs.

5. Facial photographs.

NONESSENTIAL / SUPPLEMENTALDIAGNOSTIC AIDS

1. Specialized radiographs

a. Occlusal view of maxilla & mandible.

b. Selected lateral jaw views

2. Electromyographic examination

3. Hand-wrist radiographs

4. Computed axial tomography (CT scan).

5. Magnetic Resonance Imaging (MRI)

6. Endocrine tests and/or other blood tests

7. Estimation of the basal metabolic rate

8. Sensitivity (vitality) tests

9. Biopsy

Occlusal radiograph

Specialised radiographs

I.Maxillary occlusal projections

• Upper standard occlusal (standard occlusal)

• Upper oblique occlusal (oblique occlusal)

• Vertex occlusal (vertex occlusal)

II.Mandibular occlusal projections

• Lower 90 degrees occlusal (true occlusal)

• Lower 45 degrees occlusal (standard occlusal)

• Lower oblique occlusal (oblique occlusal)

Standard maxillary occlusal

Vertex occlusal

Oblique occlusal

Lower 90 degrees occlusal

Lower 45 degrees occlusal

Lower oblique occlusal

Special radiographs

•Lateral oblique•Water’s view ( Sinus)•Townes•Reverse townes.•Submentovertex•Temporomandibularjoint projections

Lateral oblique view

Water’s view projection•Also known as sinus projection•It’s similar to the posteroanterior projection Except that the center of interest is focused on the middle third of the face.

Purpose:To Evaluate the maxillary , frontal and ethmoid sinuses.

Townes view Reverse townes

Submento vertex view

Main clinical indications• Detection of the presence and position of

radiopaque calculi in the submandibular salivary ducts

• Assessment of the bucco/lingual position of unerupted mandibular teeth

• Evaluation of the bucco/lingual expansion of the body of the mandible by cysts, tumours or osteodystrophies

• Periapical assessment of the lower incisor teeth, especially useful in adults and children unable to tolerate periapical films

• Evaluation of the size and extent of lesions in the anterior part of the mandible

• Assessment of displacement fractures of the anterior mandible in the vertical plane

• Periapical assessment of the upper anterior teeth in patients unable to tolerate periapical films

• Detecting the presence of unerupted canines, supernumeraries and odontomes

• As the midline view, when using the parallax method for determining the bucco/palatal position of unerupted canines

• Evaluation of the size and extent of lesions such as cysts or tumors in the anterior maxilla

• Assessment of fractures of the anterior teeth and alveolar bone, especially useful for children

• Clinical indications- assessment of the bucco/palatal position unerupted canines

• Disadvantages:- There is a lack of detail and contrast on the

film because of the intensifying screens, the mass of tissues the X-ray beam has to penetrate and the consequent scatter

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Electromyography The instrument used for evaluating

the activity of the orofacial muscle is the electromyograph. It is used to measure the electrical activity .

Recording Methodology• Electrical potential difference measured between two points

bipolar electrode configuration used• Bipolar Electrode Types

• Fine Wire• Needle• Surface

• Electrode Placement• Overlying the muscle of interest in the direction of predominant fiber

direction• Subject is GROUNDED by placing an electrode in an inactive region of

body

http://www.hhdev.psu.edu/atlab/EMG.jpg

2218.05.2004

All types of the electrodes record the membrane action potentials from the several to many fibers in a single motor unit

A flat metal plate is placed over the muscle to be tested. Then, a thin sterile needle attached to wires of a recording machine is inserted through the skin into the muscle. The electrical activity of the muscle is recorded at rest and during contraction. It is then displayed as electrical waves on an oscilloscope and amplified to produce sounds over an audio speaker.

This permits to study the behaviour of individual units and how the units are recruited.

Fine Wire

Represented graphically electromyogram

The action potentials from the various units merge together and produce the typical electromyogram.

EMG Uses

• Whether a muscle is active or not during a movement activity

• When the muscle turns ON/OFF during a movement activity

• Phasic relationship between muscles during a movement activity

• Does an increased EMG magnitude imply a higher muscular stress?

• Is the muscle fatigued?

Hand and wrist radiographs

• Chronological age- not sufficient for assessing the

developmental stage and the somatic maturity of the

patient

• Assessment of the skeletal age is made with the help

of hand radiographs which can be considered as

biological clock

• Standard method for the evaluation of the skeletal age

• Easily identifiable maturity indicators

• Reliable source of maturation process

• Serves as a useful diagnostic aid

Indications for hand & wrist radiographs

• Prior to rapid maxillary expansion

• When maxillomandibular changes are indicated

• Marked discrepancy b/w chronologic and dental age

• Orthodontic patients requiring orthognathic surgery

between 16 &20 yrs of age.

• Most commonly used, comprising of 28 – 30 separate

centers of bone growth and maturation

Anatomy of skeleton of the hand Distal ends of long bones CarpalsMetacarpals Phalanges

Carpel bones:I. TrapeziumII. Trapezoid III. CapitateIV. HamateV. Hamular processof the hamateVI. TriquetralVII. Pisiform VIII.Lunate IX. Scaphoid

carpals

Atlas method of Greulich & Pyle

• Radiograph is compared with a standard series of films, representative of normal children at different chronological ages and for each sex.

Bjork, Grave & Browns method

• 9 developmental stages • Area of ossification events Area of phalanges Carpel bones Radius • This method describes the relationship b/w the

epiphyses and the diaphysis in 3 stages

1976( )

Stages of ossification

First stage

• PP2 = stage 1• The epiphysis and

diaphysis of proximal phalanx of index finger are equai

• Occurs 3yrs before prepubertal growth spurt

Second stage:• MP3 = stage• The epiphysis and diaphysis of middle phalanx of the middle

finger are equal•

Third stage

This stage is characterized by presence of 3 areas of ossification

a. The hamular process of the hamate exhibits ossification

b. Ossification of pisiformc. The epiphysis and

diaphysis of radius are equal

Fourth stage

This stage marks the beginning of the pubertal growth spurt an is characterized by:

a. lnitial mineralization of the ulnar sesamoid of the thumb

b. Increased ossification of the hamular process of the hamate bone

• Reach shortly before or at the beginning of the pubertal growth spurt

Fifth stage

This stage marks the peak of the pubertal growth spurt. Capping of diaphysis by the epiphysis is seen in

a. Middle phalanx of the third finger

b. Proximal phalanx of thumbc. Radius

• Marks the peak of pubertal growth spurt

Sixth stage DP3 U stage – constitues the

end of pubertal growth• This stage signifies the

end of the pubertal growth spurt and is characterized by the union between epiphysis and diaphysis of the distal phalanx of the middle finger

Seventh stage• PP3 U stage• This stage is represented by the union of

epiphysis and diaphysis of the proximal phalanx of the little fingers

Eighth stage • MP3 U stage• This stage is represented by the fusion between

the epiphysis and diaphysis of the middle phalanx of the middle finger

Ninth stage • This is the last stage and it signifies the end of skeletal

growth. It is characterized by fusion of epiphysis and diaphysis of the radius

• Ossification of all the hand bones is completed and skeletal growth is finished.

Singers method• Julian Singer 1980,It involved six stages of

hand-wrist development

• Early, • Pre pubertal• Pubertal onset• Pubertal• Pubertal deceleration • Growth completion

6 stages of hand & wrist developement

Stage 1(early) Absence of pisiform,Hook of hamate.Epiphysis of proximal phalanxOf second digit narrower than Its shaft

Stage 2(prepubertal)-Initial ossification of pisiform &Hook of hamate.-Proximal phalanx of second digitAnd its epiphysis are equal in width

• Stage 3( pubertal onset)

• Beginning of calcification

of ulnar sesamoid Increased ossification of pisiform & hook of

hamate

• Stage 4(pubertal)• Calcified ulnar

sesamoid• Capping of shaft of

middle phalanx of third digit by its epiphysis-MP3cap.

• Stage 5(pubertal decelaration)

• Ulnar sesamoid fully calcified

• DP3u stage • All phalanges and carpals

fully calcified• Epiphyses of radius and ulna

not fully calcified with respect to shafts

• Stage 6(growth completion)

• No remaining growth sites

Fishman method

This system uses;- Only four stages of

maturation- Six anatomic sites

located on the thumb, third finger, fifth finger radius.

11 discrete adolescent SMIs

System of SMA

-organized

-relatively simple

Cervical vertebraeLateral ceph. Dens(odontoid process) Body of C3 Body of C4

C2C1

CATEGORY 1(initiation)• Corresponds to SMI 1&2.

• 80-100% of growth expected

• Inferior borders of C2,C3 & C4 were flat

• Vertebrae wedge shaped

• Tapered from post. to Ant.

Six categories of CV maturation

CATEGORY 2 (acceleration)• Corresponds to SMI 3&4• 65-85% of growth

expected• Inferior borders of C2,C3-

concavities developing• Inf. Border C4 flat• C3 &C4 bodies rectangular

CATEGORY 3 (transition)

• Corresponds toSMI 5& 6• 25-65% GROWTH EXPECTED

• Distinct concavities-C3&C4• Concavity begins to develop-C4• C3 &C4 rectangular.

CATEGORY4(DECELERATION)

• Corresponds to SMI 7&8.

• 10-25% growth expected

• Distinct concavities- C2, C3&C4.

• C3&C4-becoming square in shape.

CATEGORY 5(maturation) • Corresponds to SMI 9 & 10

• 5-10% growth expected.

• Accentuated concavities-C2,C3 &C4.

• C3 &C4 almost square in shape.

CATEGORY 6 (COMPLETION)

• Corresponds toSMI 11

• Adolescent growth complete

• Deep concavities-C2, C3 &C4.

• Vertebral bodies greater vertically than horizontally.

•Orthodontists have always relied on 2-

dimensional X-rays for diagnosis, treatment

planning and patient education

•But the introduction of 3-dimensional imaging

systems like computerized tomograms have

radically altered the ability of the orthodontist in

making diagnosis and treatment planning

COMPUTED TOMOGRAPHY

Parts of the Equipment;1. Scanner ( movable x

ray table + gantry)2. Computer system3. A display console

RADIATION DOSAGE FOR CT

Radiation dosage 1.536 rad for a single section

1.8432 rad for multiple sections

Estimated dose to the centre of the condyle with CT is 180mR

Cleft of the upper lip

Skeletal and soft tissue abnormalities can also be seen

Airway analysis

A recent study conducted on 11 subjects using lateral cephalograms and CBCT’s showed moderate variability in airway dimension

Assessment of alveolar bone height and volume

For implant placement

Assessing the height, width of the bone

TMJ morphology

Conventional Computerized Tomography

Computerized Tomography was developed by sir Godfrey Hounsfield in 1967

Since its evolution it has gone through 5 generations.

The method of organization of these systems depends on the individual moving parts and physical motion of the beam in capturing the data

FIRST GENERATION Consists of a single radiation source and a single detector

The second generation made use of multiple detectors arranged in the same plan but they need not be continuous

The third generation CT’s made use of laarge detectors there by reducing the need for the beam to translate around the object

They were also known as fan beam CT’s

Disadvantage was ring artefacts seen in the image thus distorting the 3D image

Fourth Generation CT’s counteracted the problem of ring artefacts

They consisted of a moving radiation source but a fixed detector ring

Scattered radiation was more

The Fifth Generation CT’s were developed to overcome motion or scatter effects

The detector is stationery and the electron beam is swept around in a semicircular tungsten strip anode .X-rays are produced when the electrons hit the anode and rotate around a patients head with no translational components or moving parts

The X-ray tube rotates around the patient as the table is translated through the

gantry , net effect being that the X-ray tube traveling in a helical path around the

patient

Multiple detector arrays are used

Detectors are closely packed

Disadvantages of conventional CT’s

Requires more space

Expensive than conventional radiographic machines

Images captured are made up of multiple slices and therefore the ‘stacked’ image is time consuming and less cost efficient

Radiation exposure is more so limited only to complex craniofacial problems

Cone Beam Computerized Tomography (CBCT) was introduced in 1990’s

Evolutionary process resulting from the demand for three dimensional information information obtained from conventional CT’s

Custom built CBCT’s are in the market specifically for use in dentistry

CBCT

The object to be evaluated is captured as the radiation source falls on a 2- dimensional detector

An entire region of interest can be obtained with a single rotation of the X-ray source

The cone beam produces a more focused beam, so less scatter radiation

Significant increase in X-ray utilisation and reduces tube required for volumetric scanning

Total radiation exposure is approximately 20% of conventional CT’s

Nearly equal to a full mouth periapical radiographic exposure

Less expensive and smaller, so can fit in dental office

CBCT Acquisition systems

New Tom 3G - Quantitative radiology, Verona, Italy

i-CAT - Imaging sciences International,USA

CB MercuRay – Hitachi, Japan

3D Accuitomo - Kyoto, Japan

CBCT technology in dentistry

Patient in supine position or sitting position

Scan takes place in 36 seconds

3 possible fields of view

0.125mm voxel resolution

12 BIT Gray Scale

Higher resolution for all views

0.125 mm voxel resolution

Good contrast

Amorphous silicon flat panel image sensor

Views possible with CBCT

periapical

panoramic

Cephalogram

occlusal view

TMJ series

separate axial views

Orthodontic implications of CBCT’s

Impacted canines and abnormalities

Airway analysis

Assessment of alveolar bone height and volume

TMJ morphology

Impacted canines and abnormalities

2 D View

3D CBCT View

The quality of TMJ images is comparable to

conventional CT’s

Radiation exposure is less

Image taking faster

Less expensive

• The New Tom 9000 Volume scan has been extremely valuable for investigating impacted teeth, temporo mandibular joints, implant planning, and pathology.

• Three-dimensional scans can give valuable information about areas of the dentition, such as the position of the maxillary incisor roots relative to the lingual cortical border of the palate to plan retraction, the amount of bone in the posterior maxilla available for distalization, the amount of bone lateral to the maxillary buccal segments available for dental rather than skeletal expansion, airway information on the pharynx and nasal passages, maxillary root proximity to the maxillary sinus, and the position of the mandibular incisor roots in bone.

• These scans also allow 3D visualization of bony defects and supernumerary teeth in patients with cleft lips or palates.

• axially corrected tomograms of the temporo mandibular joints can be obtained from the same scan.

Magnetic Resonance Imaging

Principles: Magnetism is a dynamic invisible

phenomenon consisting of discrete fields of forces.

Magnetic fields are caused by moving electrical charges or rotating electric charges.

Images generated from protons of the hydrogen nuclei.

Essentially imaging of the water in the tissue.

Magnetic Resonance Imaging The technique is based on the presence of specific magnetic properties found within atomic nuclei containing protons and neutrons,

Inherent property of rotating about their axis Causes a small magnetic field to be generated around the

electrically charged nuclei. When dipoles exposed within a strong electric field Orientation in response to the field Depending on density and spatial relation Signal interpreted and image produced

When images are displayed; intense signals show as white and weak ones as Black and Intermediate as shades of gray.

Cortical bone and teeth with low presence of hydrogen are poorly imaged and appear black.

Equipment;1. The Gantry ;houses the

patient. Patient is surrounded by magnetic coils

2. Operating console ; where the operator controls the computer and scanning procedure

3. Computer room network.

The objectives of MRI imaging of the TMJ are; Determine relationship between the disc and Temporal and

mandibular components of the TMJ Detect inflammation, hematoma and effusion for the soft

tissue components

MRI clearly differentiates the soft tissue components . Short and long echo imaging of the TMJ enables identification

of the positional relationships between the disc and the condyle

The contrast and appearance of images can be varied by selecting the field strength and other factors.

Special head holders have been designed which facilitates orientation of the patient and reduces patient movement during imaging

Complications;Magnetic forces and radio waves - not know to produce any

biological side effects in man.Non invasive technique and can be used in most patients.

Contraindications; Patients with cardiac pacemakers. Patients with cerebral metallic aneurysm clips. Slight movement

of the clip could produce bleeding Stainless steel and other metals produce artifacts ; obliterate

image details of the facial area.*

Indications Assessing diseases of the TMJ Cleft lip and palate Tonsillitis and adenoiditis Cysts and infections Tumors

Short comings Inability to identify ligament tears or perforations Dynamics of tissue joint not possible Cannot be used in patients suffering from claustrophobia.

Hormones – in Greek means “I excite

or arouse”, was introduced by Starling

in 1905.

DEFINITION : Secretory product of

Endocrine glands released directly into

the circulation in small amount in

response to specific stimulus.On

delivery in circulation it produces response

on the target cells or organs.

Endocrine tests

GROWTH HORMONE (GH)

Protein hormone, secreted by acidophills of anterior pitutary Secretion is more during strenuous excercises and deep sleep. No specific target organ. Anabolic harmone. No direct action on bone but act thru substance called STOMATOMADIN.

TWO TYPES:1. Insulin like growth factor(IGF-1)2. Insulin like growth factor(IGF-2)

GH carries almost all the metabolic activity withIGF-1 .

Normal concentration of GH ;2 – 4 ng/ml in growing child

GH DEFICIENCY

Children with big skull with babyish faceCephalometric studies : Small size of ant. & post. Cranial base Smaller mandibular dimensions Small post. Facial height & mand. height.

Study done on 13 pts. with pitutary deficiency,Cephalometric finding were low as compared to normal

HYPERSECRETION OF GH

1. GIGANTISM2. ACROMEGALY

GIGANTISM

Occur during adolescence before epiphysial closure.Features: Tall stature Bilateral gynaecomastia Large hand and feet Associated features like:coarse hair,loss of libido,etc.

ACROMEGALY

Occur during adulthood after epiphyseal closure.Usually a result of benign pitutary tumor.

Features :Broad,thick noseThickening of the skinProminent browCoarsening of facial featuresPrognathism : elongation and widening of mandible (class 3 malocclution)Serum level of IGF-1 was 10 times high.Development of cross bite

ELONGATION AND WIDENING OF MANDIBLE IN ACROMEGALY

Mandibular growth in Acromegaly results fromappositional growth and hypertrophic changesin the condylar cartilage.

THYROXINE HORMONE (TH)

It has no specific target organRegulates the pace of metabolism thru interactionswith mitochondrial,nuclear & extra mitochondrial processes.Prenatal hypothyroidismDevelopment of bone & teeth are retardedLater enamel defects in prenatally developed teeth are seen.Some degree of mental retardation is seen.After birthGrowth of cranium is retarded – brachycephalic faces developIncreased mental retardation.

TH important for synthesis of IGF-1Reduced facial height seen in children hypothyroidism of long duration.

Orthodontic consideration

TH administration leads to :

Increased bone remodelling Increased bone resorptive activityReduced bone density This result in increased tooth movement during ortho. treatment.(study done by Sherazi,Dehpour,Jafari)

PARATHORMONE(PTH)

Polypeptide hormone,secreted by parathyroid glands.It mobilizes calcium and phosphorous from bonesIt increases serum calcium level, and decreases serum phosphorous.

Study done by Anthony and Richard on rats:50U in 0.5cc solution injected in distal aspect of left central incisor of 6 rats.After 5th day- appliance fitted(1 ounce force)6th day animal sacrificed and maxilla removed and examined.

Lat. Incisor treated with PTH moved more than the right lat. Incisor

Result ; PTH enhance ortho. Tooth movement if applied locally.

CALCITONIN

Peptide hormone, secreted by intra follicular or C- cells in the thyroid gland.also called Thyrocalcitonin.

It flows in bloodstream and attracts Ca to bone, thus reducing Serum calcium.It reduces bone resorption by reducing the no. of osteoclasts.

It is used in the treatment of Hypercalcemia and Osteoporosis.

Ortho consideration

It inhibit tooth movement and consequently delays orthodontic treatment .

VITAMIN D - 3

Vit. D3 with parathyroid and cacitonin hormoneregulates the amount of Ca and phosphorous in human body.

It promotes interstitial Ca and phosphorous absorption

Vit.D3 increases the bone mass and thus reduces fractures in osteoporosis .

It can be assumed that they can inhibit tooth movement.

SEX HORMONES

They are steroidal hormone.

At puberty, the increase in GH and IGF-1 production is sex hormone dependent.

Promotes protein synthesis in the body.

They regulate normal bone metabolism(after menopause- osteoporosis)

Role of sex hormone in dental & craniofacial development

delayed facial growth in Hypogonadism . Estrogen directly stimulates the bone forming activity of osteoblasts. Androgens also inhibit bone resorption &also modulate growth of muscle system.

In Athletes excess use of drugs may effect the length and the results of orthodontic treatment.)

CORTICOSTEROIDS

HYPERGLUCOCORTICOIDISM leads to short stature and developed bone maturation.

Very small amount may decrease growth rate.

Skeletal IGF-1 synthesis decreased by Cortisol.

Cortisol has inhibitory effect on bone collagen synthesis

Cortisone accelerate the tooth eruption.

PROSTAGLANDINS(PG)

They act by increasing number of osteoclasts and activating already existing osteoclasts on application of mechanical stress.

ROLE OF VITAMINS IN GROWTH AND DEVELOPMENT

Certain “CRITICAL PERIOD” exist during development of organcharacterized by HYPERPLASTIC AND HYPERTROPHIC GROWTHPHASES.Any dietary deficiency during these phases may cause irreversible changes like growth retardation & orofacial alteration in humans like:

1. Cleft lip and Palate2. Reduced dental arch dimensions with inadequate spaces3. Insufficient dental eruption4. Short root and interosseous rotation of per. Teeth5. Shorter mandible in ant. And post. Direction6. Reduction in ascending ramus7. Dentoalveolar inclinations in the incisor region8. Reduction in mesio – distal dimension of 3rd molar.

BIOPSY

DEFINITION : Biopsy is the removal of tissue from the living organism for the purpose of microscopic examination and diagnosis.

TYPES : The total excision of a small lesion for microscopic study is called excisional biopsy.

A small section is removed for examination which is termed as incisional biopsy.

METHODS :

Surgical excision by a scalpel Surgical removal by cautery or high frequency cutting knife. Removal by biopsy forceps or biopsy punch. Aspiration through a needle with a large lumen Exfoliative cytology.

EXFOLIATIVE CYTOLOGY :

* Cleansing the surface of the oral lesion of debris & mucin & scraping the entire surface of lesion several times with a metal cement spatula or moistened tongue blade.

* Collected material is the quickly spread over a microscopic slide & fixed immediately.

* Fixative may be 95% Alcohol or equal parts of alcohol & ether.

* After the slide is flooded with fixative it should be allowed to stand for 30 Min to Air dry.

Classification :Class I : (Normal) – Indicates that only normal cells present Class II : ( Atypical) – Indicates presence of Atypia but no malignant changes.Class III : ( Indeterminate) – This is an in between Cytology that seperates cancer from Non-Cancer Diagnosis.Class IV : (Suggestive of cancer) – A few cells malignant characteristics Class V: (+For cancer)

BIOPSY TECHNIQUE :The instruments include a scalpel handle & blade (No:15, Forceps, a Needle holder, sutures & L.A.

Few drops L.A are placed at periphery of the lesion

An elliptical or wedge incision is then made that includes both normal & Abnormal tissue with in the lesion.

Grasp the tissue with a forceps & then circumscribe the area while under tension.

Once the sample is removed, it is placed in fixative (10% formalin)

The sample along with description is sent for histologic Examination

Hemostasis can be accomplished by direct pressure, suture or placement of a periodontal pack.

Healing of Biopsy wound :The healing of biopsy wound of oral cavity may be classified as primary healing or secondary healing.

The nature of healing process depends upon whether the edges of wound can be brought in to apposition often by suturing or whether the lesion fill in gradually with granulation tissue.

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