Comparison of the flexibility of two different stainless steel crowns (3M and MIB) while seating on primary molars

One of the most important restorative methods in pediatric dentistry is the use of stainless steel crowns(ssc). Evaluation of the flexibility of existing crownsand whether the crowns that have more crimping ability are necessarily more flexible, was the basis of the present research.

In this in vitro study, 13 extracted intact maxillary second molars were mounted 1 mm lower than the CEJ and the appropriate crown size was selected from the 3M and MIB brands. Preparation of the teeth for ssc was performed by a pediatric dentist. Sufficient seating and retention of the crowns were evaluated. The photographs of crown margins were taken by a digital camera and crown circumference measured with the Auto Cad software. Then, the ZWICK machine measured the force required to place each of the crowns on the tooth. Using the proportionality between the measured force and the circumference of the margin of each crown, the level of force equilibrated in each crown was obtained and compared.

In 8 cases, the force applied to the crown and force to environment ratio in the case of 3M was higher than the MIB, and in 5 cases, 3M was less than the MIB. P-Value of difference of force to environment ratio, force difference and environmental difference between the two types of MIB and 3M crowns were calculated 0.113, 0.111 and 0.728, respectively, which were not statistically significant.

thecrowns that have more crimping ability are not necessarily more flexibleand the preparation is not different for the 3M and MIB crowns.