Impact of hybrid layer formation on the 15-year survival, complications, and failures of full-coverage retainers

To compare the effect of 4-META/MMA-TBB resin, which can provide hybrid layer formation, and acid-base cements on survival, complications, and failure risks of full-coverage retainers evaluated for 15 years.

A total of 1,161 abutment teeth in 260 patients treated with at least one single crown or fixed partial denture were recalled for clinical examination. Survival was defined as not having undergone extraction of abutments or renewal of prostheses. Secondary caries, pulp necrosis, or prosthesis detachment were recorded as complications. Survival and complications rates were analyzed using the Kaplan-Meier method and log-rank test. Multivariable analysis of factors associated with failure or complications using Cox's proportional hazard regression model was performed (α = 0.05).

Significant differences were observed in survival (p = 0.007), secondary caries (p = 0.000), and prosthesis detachment (p = 0.025) complications between luting agents. The 5-, 10-, and 15-year survival rates for 4-META/MMA-TBB resin were 95.2%, 90.5%, and 90.5%, while those of acid-base cements were 93.2%, 80.6, and 67.4%, respectively. Secondary caries and prosthesis detachment complications for 4-META/MMA-TBB resin were 1.9% and 0.5%, whereas those for acid-base cements were 15.2% and 4.3% respectively. Acid-base cements were associated with a 1.664-, 2.950-, 3.333-, and 4.444-times greater risk of failure, prosthesis renewal, secondary caries, and prosthesis detachment, respectively.

4-META/MMA-TBB resin has higher long-term survival rate with lesser caries, and prosthesis detachment than acid-base cements. The ability of this resin to create an acid-base resistant hybrid layer may contribute to a life-long function of tooth abutment.