The effectiveness of auxiliary features on the resistance of complete cast crowns on short abutments (in vitro study)

effectiveness of auxiliary features on the resistance of crowns

Abstract

aim: Fixed prosthodontics is considered the most used restorations to treat endodontically-treated and heavily destructive teeth. Retention and resistance form of abutments is the preliminary and most important factor for the success and longevity of prosthesis.

Short abutments teeth impose a big challenge for dental professionals, for these teeth doesn’t possess enough retention and resistance form.

Historically, it has been proposed addition of auxiliary features to increase the contact surface area and therefore enhancing the retention and resistance of short abutments.

Resistance is the key element for a prosthesis to achieve an acceptable functional performance. This study was to evaluate the effectiveness of auxiliary features on the resistance of complete crowns cemented on short abutments.

Materials and Methods: 36 copper abutments were prepared with molar shape and short length (3mm), and were divided into 3 equal groups: control group (abutments and crowns with no modification), group with two opposing seating grooves (SG) on the mesial and distal surfaces and group with an occlusal hole (OH) in the center of the occlusal surface. The metal crowns were waxed directly to abutments and were cemented using zinc phosphate cement. Resistance tests (oblique forces) were applied till failure. The data were analyzed by one-way ANOVA.

Results: The mean values of resistance calculated (in kg) according to studying groups were: control group 419.0 kg, (SG) group 418.2,

(OH) group 511.5 kg. the test doesn’t show any significant differences teen the studying groups in resisting the oblique forces (p=0.074) with advantage for occlusal hole group.

Conclusion: Adding auxiliary retentive features to the preparation of short abutments enhance the resistance values of crowns cemented on it, but there was no significant difference for this improvement with an advantage for occlusal hole over seating grooves.