Temperature rise on dentin caused by temporary crown and fixed partial denture materials: influencing factors.

OBJECTIVES

Temporary crowns and fixed partial denture materials (t-c&b) generate exothermic heat during polymerization. The amount of temperature, reaching the pulp chamber, is dependent on the residual thickness of the prepared dentin as well as the volume of the t-c&b used. Hence, the aim of this study was to investigate the influence of both factors on the temperature rise at the pulpal dentin surface as well as in the bulk of the t-c&b during polymerization.

METHODS

Four t-c&bs (Luxatemp AM Plus, Protemp 3 Garant, Structur Premium, Trim) were used to fabricate flat cylindrical specimens (∅ 15.5mm) of different thicknesses (1, 2 and 4mm) using an over-impression placed on top of dentin discs (thickness 0.5, 1 and 2mm). Temperature was recorded at the pulpal dentin surface as well as inside the t-c&b (n=6). Data was subjected to parametric statistics (α=0.05).

RESULTS

Peak temperatures inside the t-c&b varied between 37.0°C and 51.9°C and at the pulpal dentin side between 37.0°C and 50.6°C. The maximum temperatures registered depended significantly on the thickness of the dentin disc and t-c&b, respectively (ANOVA p<0.05). Peak temperatures were reached 2-3 min after start of mixing (dimethacrylates) and 6 min (mono-methacrylate), respectively, whereas Trim exhibited significantly higher peak temperatures (p<0.05).

CONCLUSIONS

At 4mm layer thickness of the t-c&b, temperature rise may become critical if the material is not cooled properly. Composite-based t-c&bs showed significant lower curing temperatures than Trim and should therefore be preferred in daily practice.