Diagnostic Aids In Orthodontics

Diagnostic Aids In Orthodontics

Classify diagnostic aids used in orthodontics and discuss in detail non­essential diagnostic aids.
Answer.

Classification of Diagnostic Aids:

Essential Diagnostic Aids

• Case history
• Clinical examination
• Study models
• Certain radiographs:
  • Periapical radiograph
  • Bitewing
  • Panoramic.
• Facial photographs.

Diagnostic aids in orthodontics

“Importance of diagnostic aids for accurate orthodontic planning”

Non­essential or Supplement Diagnostic Aids

• Specialized radiographs:
  • Cephalometric radiographs:
    • Lateral cephalometric radiographs.
    • Frontal cephalometric radiographs.
    • Oblique cephalometric radiographs.
  • Occlusal radiographs.
  • Selected lateral jaw view.
  • Cone shift technique.
• Electromyographic examination of muscle activity.
• Hand and wrist radiographs to assess bone age.
• Endocrine tests.
• Occlusograms.
• Estimation of basal metabolic rate.
• Diagnostic set-up.

Orthodontic diagnostic tools

“Common diagnostic aids used in orthodontics explained”

Non­essential Diagnostic Aids

Radiographs: They are a valuable tool in establishing the orthodontic diagnosis.

Occlusal Radiograph

• They are advantageous to patients who have restricted mouth opening for IOPAs.
• A large segment of the dental arch is viewed in these radiographs including palate and dental arch.
• Uses for location of impacted and supernumerary teeth.
• For studying of arch expansion procedures
• For diagnosing the presence or absence of fractures.
• For locating foreign bodies in the jaws and stones in the salivary duct.

“Complications of delaying orthodontic diagnosis”

Extraoral Radiographs

These radiographs enable viewing of orofacial region with placement of the fim extraorally.

Panoramic Radiographs

They enable viewing of maxillary and mandibular arches with supporting structures.

“Cephalometric analysis in orthodontics”

Uses

• Shows ankylosed and impacted teeth.
• Useful in assessing mixed dentition.
• For studying path of eruption.
• For diagnosing pathologies, fractures and supernumerary teeth.

Advantages

• Broad anatomic area and landmarks are seen.
• Radiation exposure is low
• Can be used easily in cases which have restricted mouth opening.

Disadvantages

• Artifacts can occur.
• It is expensive.
• Inclination of anterior teeth is not visualized.
• Clarity of structures is less as compared to IOPAs.

“Role of dental X-rays in orthodontic diagnosis”

Cephalometric Radiographs

• In this the head is held in predetermined position.
• These radiographs are used for comparison of serial radiographs.
• Types of cephalograms are frontal, lateral and oblique.

Advantages

• A broad anatomic area can be visualized.
• Patients radiation exposure is low.
• It helps in orthodontic diagnosis by enabling the study of skeletal, dental and sof tissue structures of craniofacial region.
• It helps in treatment planning.
• It helps in evaluation of the treatment results by quantifying the changes brought about by treatment.
• It helps in predicting the growth related changes.
• By cephalometries the skeletal and dental abnormalities can be classified.

“Panoramic radiographs for orthodontic assessment”

Disadvantages

• Give 2 dimensional view of three dimensional object.
• Give a static picture, which does not take time into consideration.
• Reliability is not always accurate there can be errors in determining the landmarks.
• There are different methods of analyzing a cephalogram and so no standardization of analyze.

Hand-wrist Radiograph

Hand-wrist Radiograph is a Skeletal Maturity Indicator.

• There are numerous small bones in the hand-wrist region. They follow a pattrn in ossifiation and union of epiphysis with diaphysis.
• Carpal bones were fist named by Lyser in 1683.
• In hand-wrist radiographs left hand wrist is used and a PA view is taken for hand-wrist region.
• Bjork divided the skeletal development in the hand-wrist area into 8 stages. These stages represent a particular level of skeletal maturity.

Indications of hand-wrist radiograph

• In cases with major discrepancies between chronological and dental age.
• In cases where prediction of pubertal growth spurt is required.
• In cases with skeletal Class 2 and Class 3 malocclusion before beginning their treatment so that their growth potential is assessed.
• For skeletal age assessment to study growth of an individual.
• Indicated in research studies to make out the effct of hereditary and environment on dentofacial growth.
• In patients with skeletal malocclusion and need orthognathic surgery.

“Use of study models in orthodontic diagnosis”

Diagnostic set up

• Diagnostic set up was fist proposed by H.D. Kesling.
• Diagnostic set up is made from an extra set of trimmed and polished study models.
• Individual teeth and their associated alveolar processes are sectioned of and replaced on the model base in desired positions.
• Diagnostic set up thus helps in simulating various tooth movements which are planned for patients.

Procedure of diagnostic set up

• Cut the cast by using a Fretsaw blade to separate the individual teeth.
• A horizontal cut is made 3 mm apical to gingival margin.
• Vertical cuts are made to separate the individual teeth.
• The individual teeth are set in the desired position by using red wax.

Uses of diagnostic set up

• It is useful in visualizing and testing the effect of complex tooth movements and extractions on occlusion.
• Patient can be motivated by simulating the various corrective procedures on the cast.
• Tooth size: Arch length discrepancy can be visualized by means of a set up.

Occlusograms

An occlusogram is 1:1 reproduction of occlusal surfaces of plaster models on an acetate tracing paper. Upper tracing should be oriented to lower tracing by help of grooves cut in back side of plaster models.

Technique

• For making the occlusogram either the photostatic or photographic copies of both maxillary and mandibular study models is made.
• Copies should be placed parallel to occlusal plane.
• Tracing of teeth of mandibular and maxillary arches should be superimposed to match the occlusion.

Classification of diagnostic aids in orthodontics

“Digital imaging as a diagnostic aid in orthodontics”

Uses

• For estimation of arch length as well as width and predicting occlusal relationship.
• For estimation of spacing and crowding.
• For estimation of requirement of anchorage
• For analyzing tooth movement requirement in three planes of space.
• It permits clinician to make accurate and reliable arch length discrepancy measurements.

“Treatment planning using orthodontic diagnostic aids”

Electromyography

It is the procedure which is used to record the action potentials formed in voluntary muscles when they are excited. Here instrument used is electromyograph and the output is electromyography.

• Surface membrane of muscle cell is positively charged on the external surface and negatively charged on internal surface. Action potential reverses charge on the muscle membrane. Now, a series of changes occur, which bring the muscle contraction.
• Electromyograph measures amplitude, frequency, and duration of action potential. Action potential is received, amplified and recorded.
• Recording of electrical charges from the muscle is done by surface or needle electrodes.
• Surface electrode should be placed in the skin overlying the muscle. It has superficial activity
• Needle electrode should be placed in the belly of the muscle. It is an invasive procedure and is used in deep muscles.
• Permanent paper record should be taken by pen writing device. An electromyogram is displayed by an oscilloscope.

Uses

• It is used to study role of musculature in craniofacial growth.
• It also shows activity of mandibular elevators and depressors.
• It studies the pronounced buccinator activity in class 2 division 1 malocclusion.
• It is used to assess the aberrant muscular activity which is associated with various habits.