Instructions to users

This training exercise contains 15 TMJ cases examined by CBCT. You are asked to evaluate the images according to the following assessment criteria* for TMJ osseous changes.

In each case, there are 18 decisions followed by 1 out of 3 diagnoses that must be done to be able to go to the next case. First, you have to choose Yes or No for each of the following 11 criteria regarding Condylar head:

Condylar hypoplasia: Condylar morphology is normal but the size is small from all dimensions. This is associated with either an increase in the joint space in a normal articular fossa, or a small articular fossa.
Condylar hyperplasia: Condylar morphology is normal but the size is large in all dimensions. This is associated with either lack of joint space in a normal articular fossa or an enlarged articular fossa to accommodate the large condyle.
Articular surface flattening: A loss of the rounded contour of the surface.
Subcortical sclerosis: Any increased thickness of the cortical plate in the load-bearing areas relative to the adjacent nonload-bearing areas.
Subcortical cyst: A cavity below the articular surface that deviates from normal marrow pattern.
Surface erosion: Loss of continuity of articular cortex.
Osteophyte: Marginal hypertrophy with sclerotic borders & exophytic angular formation of osseous tissue arising from the surface.
Generalized sclerosis: No clear trabecular orientation with no delineation between the cortical layer & the trabecular bone that extends throughout the condylar head.
Loose joint body: A well-defined calcified structure(s) that is not continuous with the disc or osseous structures of the joint.
Deviation in form: Condylar deviation in form is defined as a departure from normal shape, such as concavity in the outline of the cortical plate, & not attributable to flattening, erosive changes, osteophytes, hyper or hypoplasia.
Bony ankylosis: Continuous osseous structure between the condyle & temporal bone associated with no discernable joint space & no translation of the condyle in the open mouth views.

Second, you have to choose Yes or No for each of the following 3 criteria regarding Articular Fossa (Eminence):

Articular surface flattening: A loss of the rounded contour of the surface.
Subcortical sclerosis: Any increased thickness of the cortical plate in the load-bearing areas relative to the adjacent nonload-bearing areas.
Surface erosion: Loss of continuity of cortical margin.

Third, you have to choose ≥1 of the 4 options regarding Condylar position:

Concentric position with normal joint space.
Concentric position with decreased joint space.
Anterior position.
Posterior position.

Finally, according to your previous answers you have to choose one diagnosis from the following table that presents the osseous diagnoses for TMJ from CBCT imaging.

A. No Degenerative joint disease

Normal relative size of the condylar head; and
No subcortical sclerosis or articular surface flattening; and
No deformation due to subcortical cyst, surface erosion, osteophyte, loose joint body or generalized sclerosis.

B. Indeterminate for Degenerative joint disease

Normal relative size of the condylar head; and
Subcortical sclerosis or/and articular surface flattening; and
No deformation due to subcortical cyst, surface erosion, osteophyte, loose joint body or generalized sclerosis.

C. Degenerative joint disease

Deformation due to subcortical cyst, surface erosion, osteophyte, loose joint body or generalized sclerosis.

Note: For the diagnosis, Osteoarthritis is also a used term although Degenerative joint disease might be the best term to use for interpretation of radiographs when no clinical information is available.
*Ahmad et al 2009