Comparison of accuracy, reliability and reproducibility of plaster and digital study models measurements

• Grant number: 07/07438-0
• Support Opportunities: Regular Research Grants
• Start date: March 01, 2008
• End date: February 28, 2009
• Field of knowledge: Health Sciences - Dentistry - Orthodontics
• Principal Investigator: Lourdes Aparecida Martins dos Santos-Pinto
• Grantee: Lourdes Aparecida Martins dos Santos-Pinto
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The objective of the present study is to assess accuracy, precision and reproducibility of measurements obtained from plaster models by means of different instruments. Thirty plaster models will be randomly selected according to the inclusion requirements of the sample as follows : 1) Presence of incisors, canines, premolars and the permanent first molars in both maxillary and mandibular arches; 2) Normal morphology on every tooth of the models; 3) Absence of irregularities on the plaster due to carious lesions and restorations which may affect the mesiodistal or buccolingual diameter of the dental crown ; 4) No previous orthodontic treatment; 5) No anteroinferior or anterosuperior tooth crowding, and/or tooth crowding no higher than 4.0 mm. Three instruments will be used to make the measurements: 1- Mitutoyo Digimatic® digital caliper, Mitutoyo (UK) Ltd; 2- MicroScribe 3DX System (Immersion, San Jose, Calif.) : with MicroScribe , a 3D scanner , register the location of a selected point marked with one end of a pen. By placing the pen on different points of the object to be measured, one can collect the coordinates and make a three dimensional model;3- O3d System (widialabs©): the plaster models image is scanned by means of a scanning scanner, thus creating a three dimensional image. With the help of the program software the points to be measured are identified and the measurements are automatically recorded. Linear measurements to be assessed are as follows: size of teeth, horizontal overlap, vertical overlap, arch length, arch width. From the collected data, dependability of both Little irregularity index and Bolton analysis will be tested. (AU)