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Context: Variations in palatal bone thickness (PBT) at various locations have caused considerable problems when using these sites for anchorage purposes. Aims: To find the comparative thickness of the palatal bone at different locations and to validate its morphology for anchorage purposes using mini-implants (MI). Settings and Design: This investigation was undertaken to compare the mean PBT and level of significance of differences between male and female subjects and between two different age-groups. Materials and Methods: The computed tomography (CT) data for 60 patients (30 males and 30 females) in two different age-groups (group A: 15-24 years; group B: 25-35 years) were imported into CAD-based medical software, (MIMICS® ; Materialise, Belgium) for multiplanar reconstruction. The measurements were made in two planes- transverse and sagittal-and at different positions in each of the planes. Statistical Analysis: The mean and standard deviations of the PBT at different points were calculated. The Student′s t-test and Mann-Whitney U test were used for comparisons between the groups. Results: Significant variations were observed in the thickness of the palatal bone for both groups tested, with the anterior region at 4 mm behind the incisive papilla showing the maximum thickness. Conclusions: Despite the palatal bone being thickest in the mid-palatal suture (MPS) region, this is not the ideal site for anchorage purposes due to inadequate calcification and interposition of connective tissue, especially in young growing children. So, the alternate optimum position is the paramedian region, 3 mm lateral to the MPS and 4 mm from the incisive foramen (IF).

Currently clinicians advice rotational panoramic radiography (RPR) for preliminary investigation. Despite few inherent limitations, rotational panoramic radiography still remains the diagnostic tool of choice. Abnormal structures such as a supernumerary tooth or a device falling within the certain central regions in conventional RPR images may mislead the clinicians towards an inaccurate diagnosis by producing multiple ghost images. Such cases must be treated with circumspect, and apart from RPR, additional imaging modalities need be employed to provide a judicious interpretation of the clinical situation. Thus this manuscript, we present a case where a paramedian supernumerary tooth which exhibited double ghost images on a conventional RPR. This prompted us to elicit the use of a CBCT and 3 dimensional images to determine the true nature of the problem. We outline the working of the diamond principle behind a conventional RPR which cause the appearance of multiple ghost images. The discerning clinician must be cognizant of the possible positional and analytical errors which may be prevalent in a conventional RPR when viewing structures lying in the palatal region, specifically in the midline while making diagnosis. Key words:CBCT, double image, midline supernumerary, OPG.