A New Anterior and Posterior Maxillary Expansion Index in Orthodontics via Digital Dental Models

Abstract

The aim of this study was to determine the maxillary expansion index (MEI) for Pakistani population. Also to determine the sexual disparities in sum of incisors perimeter, arch width and expansion indices of maxillary arch. Hirox digital stereomicroscope was used for the fabrication of the digital models. The estimated sample size was 128 Pakistanis (64 females and 64 males; age range from18 -24 years). The perimeters of the maxillary permanent incisors, as well as intercanine, interpremolar, and intermolar arch widths, were measured on digital dental models. Significant sexual disparities were observed (***p < 0.001). There was significant difference observed in arch length and arch perimeter group of maxilla. For the prediction of ideal arch width in intercanine, interpremolar, and intermolar region to be achieved at the finishing stage, orthodontist can forecast the arch width before the initiation of orthodontic treatment. The new formula and the new indexes of arch width can be a helpful adjunct in the orthodontic treatment.

Validity of Pont’s analysis in a sample of Bangladeshi orthodontics patients.

“…These findings are in agreement with those of Nimkarn et al, 9 who found an over-estimation of arch widths estimated by Pont's index relative to actual arch width measured on dental casts. 3 On the other hand, Alam et al, 6 found an under-estimation of the dental arch width.Pont index should not be extrapolated to individuals of different ethnic origins as it does not give accurate estimates of ideal arch widths for a given individual in the majority of cases. 10 The reasons that may explain the lack of applicability of the index in the studied population may be due to the dental size or the amplitude of the arch.…”

“…A digital slide calipers (Mitutoyo, Japan) with sharpened beaks was used to measure the mesiodistal crown diameters of the maxillary permanent incisors and arch widths on the dental casts, to an accuracy of 0.1mm. 3,5 The mesiodistal crown diameter of the tooth was measured from anatomical contact point of one tooth to another on the occlusal side perpendicular to the long axis of the teeth. In those instances where there was slight attrition, the measuring point for arch width was determined as the middle of the facet on the tooth.…”

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“…Also, the mesiodistal width of the teeth in males and females were the same at certain ages. Shahid et al [8] in 2015 reported that only the size of maxillary lateral incisors, canines, and first premolars and mandibular lateral incisors was significantly different in the right and left quadrants. Considering the gap of information regarding the tooth size and arch size in an Iranian population, the existing controversy in this regard, and the significance of this topic in orthodontic and prosthodontic treatments, and forensic medicine, study of tooth size and arch size in an Iranian population is a necessity.…”