What a telereentgenogram shows
On a lateral head X-ray, the orthodontist can examine a complex set of anatomical structures in detail. First of all, the bones of the neurocranium and viscerocranium are visualized, as well as the cervical spine. The most important advantage of this method is that in addition to hard tissues and dental arches, the contours of the patient's facial soft tissue profile can be clearly traced on the image.
To extract accurate diagnostic data from the image, the method of cephalometry is used. Tracing is performed over the obtained X-ray image—the precise delineation of key anatomical structures. Next, the doctor places specific reference points through which diagnostic lines are drawn and angles are measured. This geometric analysis translates the visual picture into exact numerical values.
Clinical significance of TRG
In modern orthodontics and maxillofacial surgery, telereentgenography is an indispensable tool. The clinical significance of this method covers several key areas of diagnostics at once:
- Determination of the facial skeleton growth pattern. The analysis helps to understand individual trends in skull formation.
- Diagnosis of anomalies. The clinician determines the exact position of the upper and lower jaws relative to the cranial base. This is necessary to identify sagittal and vertical anomalies.
- Assessment of tooth position. TRG makes it possible to reliably evaluate the inclination of the incisors.
- Analysis of profile aesthetics. The harmony of relationships between the underlying bone structures and the external soft tissues of the face is studied.
- Strategic planning. The obtained data form the basis of the orthodontic treatment plan or preparation for orthognathic surgery.
Hand radiography
In addition to analyzing the structure of the skull, successful orthodontic treatment often requires an understanding of the patient's stage of physical development. For this purpose, radiography of the hand and wrist in the anteroposterior projection is used. Such an image visualizes the distal ulna and radius, carpal bones (ossa carpi), metacarpal bones (ossa metacarpi), and phalanges (phalanges).
When analyzing the radiograph, the clinician pays special attention to specific zones of interest: the epiphyses of the finger phalanges, the epiphyses of the metacarpal bones, and the distal radial epiphysis. This study is recognized as the absolute "gold standard" for accurate determination of bone (skeletal) age.
Assessment of bone age and pubertal growth spurt
The process of skeletal age assessment requires careful study of growth plates. Diagnostics are carried out according to several criteria: the presence of ossification centers, their current size and shape are evaluated. In addition, the most important indicator is the degree of synostosis—the process of fusion of the epiphyses with the metaphyses.
In orthodontic practice, this analysis is of critical importance for identifying the peak of pubertal growth. Precise determination of this time window is necessary for prescribing functional appliances that stimulate jaw growth. The method is also widely used in pediatrics and endocrinology to diagnose delayed or premature physical development.
To remember which hand structures are evaluated to determine bone age (from fingertips to forearm), use the phrase: Focus Peaking Zone of the Radius (Fhalanges, Palmar/metacarpal bones, Zarpie [Carpal bones], Radius).
Class and exam questions
Why does an orthodontist need a hand X-ray if teeth are being treated?
The hand X-ray is the "gold standard" for determining skeletal age. It helps to accurately catch the peak of pubertal growth, which is critically important for installing functional appliances that stimulate jaw development.
What is cephalometric analysis?
This is the calculation of parameters from a telereentgenogram. The clinician applies a tracing to the image, sets reference points, draws lines, and measures angles to assess jaw position and tooth inclination.
Can facial soft tissues be assessed using TRG?
Yes, the soft tissue contours of the profile are clearly visualized on the lateral telereentgenogram. This allows for the analysis of facial aesthetics and the relationship of the skeletal framework to the external integument.
How is bone age determined from a hand X-ray?
The physician studies ossification centers (their presence, size, and shape), and also assesses the degree of synostosis—the fusion of epiphyses with metaphyses in the phalanges, metacarpal bones, and radius.
What else to study on this topic
- Methodology for performing tracing on a telereentgenogram
- Main reference points, lines, and angles in cephalometry
- Sagittal and vertical jaw anomalies on TRG
- Stages of epiphyseal and metaphyseal synostosis
- Types of functional appliances for stimulating jaw growth
Master the entire topic in the «Propaedeutics of Dentistry» course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Telereentgenography in Orthodontics" and 868 more subject pages
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 65 video lessons on the subject
Other topics in the "Additional Topics" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.