Retention of Creative Pin Placement vs. Traditional Method in Human Mandibular Molar Teeth (In vitro)

Extensive caries restoration has always been considered as one of dental issues. To resolve this problem different methods have been suggested such as dentinal pins.Previous clinical studies revealed that the use of retentive pins, faces numerous risks (pulp exposure, dentin cracks, root perforations, etc). Introducing of bonding and composite systems, resulted in minimized mechanical retention for cavity preparation. Advantages of amalgam restorations such as simplicity of use, better mechanical properties, suitable clinical longevity and being less costly sustained its use in practice. On the other hand, caries removal usually results in a cavity form with small undercuts. So if we fill these small undercuts with “Bonding & Composite ", then insertion of pins in this base, could be considered as a safe way for obtaining retention. The purpose of this study was comparing the retention of creative pin placement (using composite) to the retention of traditional method. In this experimental study thirty sound human mandibular molar teeth free from decay and restoration were selected. The occlusal surface of samples was removed up to 3mm above CEJ. Teeth were divided in 2 groups: Group A: (N=15) T.M.S Minim pin inserted in dentin at 2mm depth. Group B: (N=15) One layer of composite (1mm) bond to flat occlusal surface of teeth and then the pin was inserted in it at 2mm depth so only 1mm of pin placed into dentin. Group C: (N=15) cylinders of composite were prepared (height=5mm, dimension= 8mm) and pin was inserted in them at 2mm depth. The retention of pins was determined under tensile force with Zwick universal testing machine and data was charted by Test Xpert. 10-11 program. Data were analyzed by variance analysis (ANOVA) and L.S.D test. The ANOVA showed: a statistically significant difference between all groups. (p≤ 0.05) The L.S.D test showed: - No significant difference between A and B. (p> 0.05) - Significant difference between A, B and C (p<0.05). The highest tensile strength belonged to group A. there was no significant difference between group A & B. So by using this technique 1mm depth of pin in dentin can result as same retention as 2mm depth. The lowest tensile strength belonged to group C.