•Purpose: to determine the relationship between in vitro studies dealing with the root canal systems of the maxillary first and second premolars and their comparison to clinically endodontically treated teeth.
•N= clinically treated maxillary 1st ) 514 ( and 2nd premolars (630) •inclusion/exclusion criteria: not mentioned
•A total of 1144 endodontically treated maxillary premolars 1st ) 514 ( and 2nd premolars )630 ( were viewed by both authors using clinical records covering a span of 13 years.
•The final radiographic films of teeth with multiple canal systems were mounted , projected and evaluated with the utilization of clinical records.
• Frequencies of teeth with single canal, two canals and three canals were recorded for both 1st and 2nd premolars.
Most highlighted Results:
•maxillary 1st premolars: 6.2% one canal, 90.5% two canal and 3.3% three canals.
•maxillary 2nd premolars: 40.3% one canal, 58.6% two canals and 1.1% three canals.
the results reinforced that more care and attention should be paid in access preparation and exploration of multiple canal systems, to avoid missing canals.