Objective: Utilize micro-tensile bond strength (µTBS) testing to evaluate the interfacial bonding strength of commercial PMMA denture repair materials and a cyanoacrylate denture repair product (Permabond 910) after 12 month soaking.

Method: Blocks of PMMA (Lucitone 199) were fabricated, fractured and repaired under pressure (75° C held at 20 psi for 20 min) or bench top cold cure for 1.5 hrs. Cyanoacrylate repair followed manufacturer's directions regarding denture surface preparation. 20 bars (1x1x30mm) per group were sectioned from each block parallel to the long axis and ~90° to the resin-resin repair interface and stored (12 months, wet, 38.5° C) before µTBS testing in a servo-hydraulic tensile testing machine (Instron Model 5569, CHS=1mm/min, Bencor Multi-T jig). Intact PMMA bars soaked for 24 hours and 12 months were tested for reference. Differences among the group means (±sd, MPa), and repair strength as a % of the soaked PMMA strength (control) are reported below. 

Results:

Repair material	PMMA µTBS MPa at 24 hours & 12 months	Repair strength as a  % of  soaked PMMA strength (control)
Control	24 hrs  43±6 (P)
	12 m  34±5  (P)
Permabond 910	12 m  9±3  (C)	26%
Acraweld (Schein)	12 m   26±4  (C)	76%
	12 m  15±4  (P)	44%
Repair (Hygenic)	12 m  21±2  (C)	62%
Repair (Lucitone)	12 m   18±2  (C)	53%
	12 m  20±2  (P)	59%
Tru-repair (Bosworth)	12 m   22±3  (C)	65%

C = cold cure           P = pressure cure                          

 

Conclusion: µTBS can be used to analyze the resin-resin interface of repaired acrylics. Twelve month soaking resulted in a 20% decrease in strength for the PMMA control. Repair strengths after 12 months soaking ranged from 44% (pressure cure Acraweld) to 76% (cold cure Acraweld) of the 12 month soaked material strength (control). The relatively small sd's makes the µTBS approach attractive.