Accuracy of arch analysis in mixed dentition using digital study models versus the plaster models using Tanaka and Johnston prediction equation:

Space analysis is traditionally performed by diagnostic measurements that have been obtained from plaster dental casts through measurements which might be influenced by subjective interpretation and bias when constructed.

*So another method of diagnostically measuring study models was introduced (Digital software). This system creates digital images of dental casts with software. From the digitized models, various analyses and routine measurements could be done that might accelerate and solve many problems and difficulties associated with storage, retrieval, reproduction, communication, and breakage of conventional plaster casts.

• Taking an impressions for a mixed dentition aged children.
• Perform a measurements using Tanaka and Johnston equation for an arch analysis using a caliper and 3Shape ortho-analyzer software.
• Casts will be scanned using the 3D scanner then by using the 3shape software measurements will be held according to Tanaka and Johnstopn prediction equation.

Inclusion Criteria:

• Aged range from 6-10.
• patients medically free from any syndromes that could affect the normal eruption.
• Normal radiographical findings in teeth eruption.
• Erupted lower incisors.

Exclusion Criteria:

• Extracted lower 1st permanent molar.
• congenital missing of incisors.
• Badly decayed permanent incisors or 1st molar that could compromise the measurements.
• Any sensitivity to any of the impression materials.

Children aged six to Ten years.