Influence of pins on the compressive and transverse strength of dental amalgam and retention of pins in amalgam

In Vitro Assessment of Retention and Resistance Failure Loads of Teeth Restored with a Complete Coverage Restoration and Different Core Materials

“…Retention pins are reported to increase the retention of amalgam restoration. Nevertheless, it has been proven that their use decreases the compression and tensile strength of the tooth . In addition, it has been demonstrated that retention pins act as stress concentrators leading to tooth fractures .…”

“…After each injection phase the material was light‐cured for 3 × 20 seconds by a LED‐curing unit (Elipar DeepCure S; 3M ESPE AG, St Paul, MN) (Fig ). Group 3 : Specimens (n = 20) received anatomic direct amalgam restorations (Dispersalloy; Dentsply Inc., York, PA). An inverted cone bur (805/010; JTC Fulldent SA) was used to prepare a retentive slot for each tooth, peripherally onto the pulpal wall, at 0.5 mm distance from the dentoenamel junction (DEJ) . The depth of the retentive slots was 1 mm.…”

“…An inverted cone bur (805/010; JTC Fulldent SA) was used to prepare a retentive slot for each tooth, peripherally onto the pulpal wall, at 0.5 mm distance from the dentoenamel junction (DEJ). [25][26][27][28][29] The depth of the retentive slots was 1 mm. The anatomic amalgam restorations were conducted with the use of the celluloid molds and a 6-mm dental matrix (Matrix Band), while the amalgam condensation was achieved again through a hole on the palatal cusp of each mold ( Fig 6).…”

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“…Retention beyond this range is presumably unimportant, while retentive failure or fracture of the pin below this range would indicate inadequate resistance to masticatory forces. Studies of pin retention in amalgam (Moffa & others, 1969;Welk & Dilts, 1969;Butchart & Lloyd, 1986) have generally been limited to conventional amalgams and stainless-steel pins.…”

“…Studies examining the effect of pins on the strength of amalgam are similarly limited. The only demonstrated effects of pins within conventional amalgam are a reduction in transverse strength (Welk & Dilts, 1969), reduced diametral tensile strength when pins are oriented perpendicular or oblique to the tensile forces (Going & others, 1968), and decreased compressive fracture resistance in amalgam cylinders of equal height and diameter (Welk & Dilts, 1969).…”