Comparative evaluation of two natural collagen-cross linking agents on the long-term microtensile bond strength of composite resin to dentin- an invitro study.

Aim: To compare the effects of two natural cross-linking agents, 2 % theaflavin and 2 % proanthocyanidin on enhancing the long-term microtensile bond strength of resin to dentin. Materials and methods: 45 single rooted-mandibular premolars were collected and sectioned to expose the mid-coronal dentin. The samples were acid-etched with 37 % phosphoric acid for 15 s. The samples were randomized into 3 groups of 15 each based on dentin pretreatment -Group 1- Control - No dentin pretreatment, Group 2 - 2 % Theaflavin for 1 min and Group3- 2 % Proanthocyanidin for 1min. Following this the samples were further sub-divided into 3 groups of 5 each based on the ageing process. Subgroup A - Immediate analysis, Subgroup B - 1year time interval (10,000 thermocycles) and Subgroup C - 3 years time interval (30,000 thermocycles). The samples were then subjected to microtensile bond strength testing in Instron at a cross-head speed of 1 mm/min until failure. The data was recorded and statistically analysed. Results: The results showed that Groups 2 and 3 had a statistically significant increase in bond strength when compared to Group 1 at all time periods Conclusion: 2 % Theaflavin can be used as a promising alternative to 2 % Proanthocyanidin to increase the long-term bond strength of adhesive restorations. Clinical significance: Natural collagen cross-linkers can strengthen the collagen network without the adverse effects typically linked to synthetic cross-linkers. They play a key role in preventing the degradation of the adhesive interface, which is crucial for the long-term clinical performance of dental restorations thereby reducing the risk of secondary caries, marginal leakage, and, ultimately failure of the restoration.