Abstract
The vertical position (depth) of anterior concave plane (ACP) of the orbital floor was evaluated by plain films of Waters' view. A vertical line was drawn and passed through the center of the infraorbital canal. The point where the vertical line crosses the superior orbital margin was chosen for the start of measurement. The distance (A) from the point to the infraorbital canal is one of the indicators for determining the depth of ACP. Another distance (B), from the point to where the vertical line crosses the inferior orbital margin, was also included. The analysis included; 478 adults with bilateral standard development of the sinuses, 20 adults with unilateral small sinuses and 48 adults with bilateral small sinuses as well as 108 infants with standard sinus development for the respective ages.
The distance (A) was larger and such was of statistical significance (5% risk) in the small sinus groups, both unilateral and bilateral, in comparison to the standard group, the average difference being 3.2mm. No significant difference was seen in distance (B). The orbital floor was investigated from the standpoint of phylogenetic, developmental and histological aspects. The orbital floor was shown to be both adaptable and unstable under various postnatal conditions. The significance of the maxillary sinus itself was also discussed according to the functional matrix concept of Moss and others.
