Assessment of infrazygomatic bone depth for mini-screw insertion.

OBJECTIVE: To investigate the bone depth at the infrazygomatic crest with regard to orthodontic mini-screw insertion.

MATERIAL AND METHODS: Twenty-nine adult human dry skulls were imaged using CBCT technology, slice data were generated and multiple measurements were undertaken at three sites associated with the infrazygomatic crest and five different measurement levels. The data were analyzed using intraclass correlation and repeated measures ANOVA.

RESULTS: The greatest bone depth was available at, on average, 11.48+/-1.92 mm apical from the cemento-enamel junction of the maxillary first molar and decreased rapidly further apically. Maximum bone depth (7.05+/-3.7 mm) was present at the lowest measurement level. However, here, insufficient clearance to the molar roots was present. Both the measurement site and the level at which the measurements were conducted had a significant impact on bone depth.

CONCLUSIONS: When inserting orthodontic mini-screws (6 mm or longer) into the infrazygomatic crest while staying clear of the molar roots perforation of the maxillary sinus or the nasal cavity can be expected, but bone depth varies considerably between individuals.