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Definition and Calculation of Little's Irregularity Index
- Little's Irregularity Index measures the horizontal linear displacement of anatomic contact points of mandibular incisors.
- The index considers the rotation and displacement of teeth during mandibular crowding.
- It sums the five displacements together to determine the degree of anterior irregularity.
- A perfect alignment yields a score of 0 on the index.
- Dial Calipers with an accuracy to tenths of a millimeter were used in Little's study to measure distances on plaster models.
Scoring and Interpretation of Little's Irregularity Index
- The scale of the index ranges from 0 to 10, with different score ranges indicating different levels of irregularity.
- A score of 1-3 represents minimal irregularity.
- Scores of 4-6 indicate moderate irregularity.
- Scores of 7-9 suggest severe irregularity.
- A score of 10 corresponds to very severe irregularity.
Disadvantages of Little's Irregularity Index
- The index assigns a high score to malocclusions with severe rotation of one or more teeth, which may not reflect the complexity of treatment required.
- Other features of malocclusion are not taken into account before assigning a score.
- The vertical discrepancy between contact points is not considered in the index.
- The index focuses solely on the mandibular anterior teeth.
- It may not provide a comprehensive assessment of overall dental irregularities.
Dentition Analysis
- Little's Irregularity Index is a tool used in dentition analysis.
- It helps quantify the degree of anterior alignment in the mandibular arch.
- Dentition analysis involves assessing various aspects of dental occlusion and alignment.
- Little's Irregularity Index provides a specific measurement for mandibular anterior irregularities.
- It contributes to the overall evaluation of a patient's orthodontic needs.
References
- 'The Irregularity Index: A quantitative score of mandibular anterior alignment' - American Journal of Orthodontics.
- Bernabé, Eduardo; Flores-Mir, Carlos (2006). 'Estimating arch length discrepancy through Little's Irregularity Index for epidemiological use' - European Journal of Orthodontics.
- Macauley, Donal; Garvey, Thérèse M.; Dowling, Adam H.; Fleming, Garry J. P. (2012). 'Using Little's Irregularity Index in orthodontics: Outdated and inaccurate?' - Journal of Dentistry.
- These references provide further information on the concept, application, and criticism of Little's Irregularity Index.
- They contribute to the understanding and evaluation of the index's relevance in orthodontics.
Little's Irregularity Index is an index used in the field of Orthodontics to measure the crowding of Mandibular anterior arch. The index was first proposed by Robert M. Little in 1975 in his paper The Irregularity Index: A quantitative score of mandibular anterior alignment.
The index takes the anatomical contact points of anterior Incisors into account. A contact point is created by touching of edges of two different teeth. During mandibular crowding, teeth are often rotated, displaced either palatally or buccally. The Little's irregularity index measures the horizontal linear displacement of anatomic contact points of each mandibular incisor from the adjacent anatomic point and sums the five displacement together. Once summed, the value represents the degree of anterior irregularity.
A perfect alignment from canine to canine will yield a score of 0 on the Irregularity Index. As the crowding increases, the score will increase. Little used Dial Calipers in his study to measure the distances on a plaster model taken of mandibular arches. The caliper had an accuracy to tenths of millimeter. The vertical discrepancy between the contact points does not play a role in the index. The scale of the index is listed below. The number correspond to the distance in mm of the sum of horizontal displacements of the anatomical contact points of the mandibular anterior teeth.
