Fracture Resistance of Temporary Crown and Bridge Materials after Chewing-Simulation

Objectives: To compare flexural strength (FS) and number of fractures (NF) of one novel and 5

established crown and bridge materials before and after thermocycling and mechanical loading

(TCML) in a 2 year simulation.

Methods: 3-unit bridges were fabricated of each material and cemented on Co-Cr alloy abutments

with RelyX Temp NE. Abutments were fixed in a PMMA block where each root area was covered

with a 0.5mm polyether (Permadyne Garant) layer to imitate the periodontium. Each material had

ten bridges tested before (waterstorage at 36°C for 14d) and after chewing simulation (waterstorage

at 36°C for 4 d followed by TCML). TCML (3.000x5°C/55°C;480.000x100N) was performed to

simulate a 2 year clinical simulation using a stainless steel antagonist (diameter: 3mm). Finally all

bridges were loaded until fracture using a Zwick universal testing machine (Zwick Z010; crosshead

speed: 1mm/min; fracture detection: 50% of Fmax). Descriptive statistics were performed.

Results are summarized in the table below.

 

Results: Material	FS before TCML[N]  median(25%/75%)	FS after TCML [N] median(25%/75%)	Difference in FS [N] before and after TCML median(25%/75%)	NF (n) before end of TCML
New Protemp	1.371(1.198/1.575)	1.288(1.026/1.575)	272(-117/339)	0
Protemp 3 Garant	1.299(1.198/1.525)	981(770/1.525)	313(155/592)	1
Voco Structur Premium	1.246(1.127/1.468)	634(521/1.062)	469(1.38/1048)	4
Luxatemp Fluorescence	1.352(1.197/ 1.441)	847(769/1.019)	481(272/614)	4
Integrity Fluorescence	1.337(1.097/1.643)	1.076(620/1643)	303(-17/774)	1
Kanitemp Royal	1.268(980/1.391)	898(632/1.179)	206(143/482)	1

New Protemp showed the highest value of flexural strength (FS) and fracture resistance (NF)

compared to the other materials tested after a TCML simulation of 2 years in vitro. No fracture

occurred after TCML.

Conclusion: These results are an indicator that New Protemp has improved mechanical properties

suitable for long-term temporization.