Infrazygomatic crest (IZC) dimension is an important factor in the safety and stability of bone screws. The dimension is known to vary according to the dimensions of the maxillary sinus, which in turn depends on the vertical facial skeletal pattern.

The objective of the study was to compare the infrazygomatic crest thickness (IZC) above the mesiobuccal root of the first and second maxillary molar in different vertical skeletal patterns.

This was a retrospective study conducted in Saveetha Dental College, Chennai. Cone beam computed tomography (CBCT) and lateral cephalograms of 36 subjects were collected and divided into 3 groups (12 subjects in each group) depending on their vertical skeletal pattern, namely normal, low and high angle. Vertical skeletal pattern was assessed using lateral cephalogram whereas IZC thickness was measured using CBCT. Mann Whitney U test was done to compare the bone thickness in the right and left sides and also to compare the same above the mesiobuccal root of the first and second molar. Kruskal Wallis and post hoc tests were done to compare bone thickness among the three groups. P-value was set at 0.05 for all the analysis.

Significant difference in IZC bone thickness above the first molar region was noted between high angle and average angle groups (P-value 0.001) and high angle and low angle (P-value 0.001). Above the second molar region, a significant difference was seen between high angle and average angle groups (P-value 0.001). Significant difference in bone thickness was also observed among the first molar and second molar region in all the three groups (P-value<0.05).

IZC thickness was the least in high-angle subjects. Clinically, it is desirable to place the IZC screw above the mesiobuccal root of the maxillary second molar especially in high-angle subjects.