الفهرس 
Introduction.Only 14 pages are availabe for public view
 |  | from | 122 |  |  |
| | | from | 122 | | |
Abstract
Anterior dental crowding stands out as perhaps the most prevalent type of malocclusion. Various methods have been proposed to evaluate incisor crowding, but none have provided a combination of simplicity and true quantification. Little’s Irregularity Index (LII) has been widely utilized for objectively assessing mandibular incisor alignment in epidemiological studies and insurance programs. Recently, the orthodontic community has expanded the application of LII to encompass both maxillary and mandibular arches, for assessment of different orthodontic brackets, retainer effectiveness, and treatment modalities. However, the adaptation of Little’s Irregularity Index to the maxillary anterior teeth, with their distinct anatomy and size, has not been thoroughly examined or adjusted. Therefore, a comprehensive investigation was essential to evaluate the validity and reliability of Little’s Irregularity Index in the maxillary arch.
A survey was conducted at the Outpatient Orthodontic Clinic, Ain-Shams University involving 1000 orthodontic diagnostic study casts, encompassing those with various degrees of anterior crowding. from this pool, 100 maxillary and 100 mandibular study casts were chosen, these casts were thoroughly inspected to fulfill our inclusion criteria. Each coded study cast was scanned using 3-shape R-750 scanner, then rendered into a 3D stereolitographic digital model (.stl) through specific software ScanIt™ Orthodonthics. Each STL file was named after the code that identified each model and saved. Ortho-Analyzer software was used for
conducting Little’s Irregularity Index measurements. The data collection process was divided into two phases:
The first phase included five orthodontic professors assessed 100 maxillary and 100 mandibular study casts in order to assign a subjective score describing the anterior crowding (from the mesial aspect of the right canine to the mesial aspect of the left canine). The scores that were given by the professors were considered the gold standard. The second phase included four examiners of different orthodontic background levels and clinical experience used the digitized study models of the same 100 maxillary and 100 mandibular study casts to determine quantitatively the amount of anterior crowding (from the mesial aspect of the right canine to the mesial aspect of the left canine) as recommended by Dr. Little.
Starting with the primary investigator, the anterior crowding of the maxillary and mandibular digital models were measured using Little’s irregularity index as proposed by Dr. Little. The localization of each contact point was examined in all three dimensions by manipulation the digital model. The sum of contact point displacement of each cast was then calculated to give a final index score.After completing the whole 100 maxillary and 100 mandibular digital casts; The same process was then repeated two more times so that all casts would be measured three times in total, three weeks apart. The other three examiners then followed the same protocol.
To assess the validity of LII in the maxillary and mandibular arches, the mean of the final index scores obtained in phase one for each
cast by the orthodontic professors were tested against the mean of scores obtained in phase two for each cast by the four examiners. The maxillary and mandibular measurements exhibited considerable separation between their means, resulting in high DE and extremely high RDE exceeding 100%. Therefore, both maxillary and mandibular measurements were deemed not valid.
Inter and Intra-observer reliability of the individual contact point displacement measurements of Little’s Irregularity Index were assessed from the data obtained in phase two of the study. Intra-observer reliability was assessed through the comparison of each of the three measurements conducted by individual examiners to one another. All RDE values were below 20%, indicating strong agreement. Concordance Correlation Coefficients CCC were consistently almost equal 1, indicating perfect agreement. Inter-observer reliability was assessed through the comparison between the average of the three measurements taken by the four examiners. DE and RDE were minimal (RDE<10%), indicating excellent reliability. Concordance Correlation Coefficients (CCC) were consistently close to 1, signifying perfect agreement.