Lorenzo Breschi1, Tatjana Maravic2, Sandra Ribeiro Cunha3, Allegra Comba4, Milena Cadenaro5, Leo Tjäderhane6, David H Pashley7, Franklin R Tay7, Annalisa Mazzoni4. 1. Department of Biomedical and Neuromotor Sciences, DIBINEM, University of Bologna-Alma Mater Studiorum, Bologna, Italy. Electronic address: lorenzo.breschi@unibo.it. 2. Department of Biomedical and Neuromotor Sciences, DIBINEM, University of Bologna-Alma Mater Studiorum, Bologna, Italy; School of Dentistry, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia. 3. Department of Biomedical and Neuromotor Sciences, DIBINEM, University of Bologna-Alma Mater Studiorum, Bologna, Italy; Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil. 4. Department of Biomedical and Neuromotor Sciences, DIBINEM, University of Bologna-Alma Mater Studiorum, Bologna, Italy. 5. Department of Medical Sciences, University of Trieste, IRCCS "Burlo Garofolo", Trieste, Italy. 6. Department of Oral and Maxillofacial Diseases, University of Helsinki, and Helsinki University Hospital, Helsinki, Finland; Research Unit of Oral Health Sciences, and Medical Research Center Oulu (MRC Oulu), Oulu University Hospital and University of Oulu, Oulu, Finland. 7. Department of Oral Biology, The Dental College of Georgia, Augusta University, Augusta, GA, USA.
Abstract
OBJECTIVES: Efforts towards achieving durable resin-dentin bonds have been made for decades, including the understanding of the mechanisms underlying hybrid layer (HL) degradation, manufacturing of improved adhesive systems, as well as developing strategies for the preservation of the HL. METHODS: This study critically discusses the available peer-reviewed research concerning the formation and preservation of the HL, the mechanisms that lead to the degradation of the HL as well as the strategies to prevent it. RESULTS: The degradation of the HL occurs through two main mechanisms: the enzymatic degradation of its collagen fibrils, and the leaching of the resin from the HL. They are enabled by residual unbound water between the denuded collagen fibrils, trapped at the bottom of the HL. Consequently, endogenous dentinal enzymes, such as the matrix metalloproteinases (MMPs) and cysteine cathepsins are activated and can degrade the denuded collagen matrix. Strategies for the preservation of the HL over time have been developed, and they entail the removal of the unbound water from the gaps between the collagen fibrils as well as different modes of silencing endogenous enzymatic activity. SIGNIFICANCE: Although there are many more hurdles to be crossed in the field of adhesive dentistry, impressive progress has been achieved so far, and the vast amount of available research on the topic is an indicator of the importance of this matter and of the great efforts of researchers and dental material companies to reach a new level in the quality and longevity of resin-dentin bonds.
OBJECTIVES: Efforts towards achieving durable resin-dentin bonds have been made for decades, including the understanding of the mechanisms underlying hybrid layer (HL) degradation, manufacturing of improved adhesive systems, as well as developing strategies for the preservation of the HL. METHODS: This study critically discusses the available peer-reviewed research concerning the formation and preservation of the HL, the mechanisms that lead to the degradation of the HL as well as the strategies to prevent it. RESULTS: The degradation of the HL occurs through two main mechanisms: the enzymatic degradation of its collagen fibrils, and the leaching of the resin from the HL. They are enabled by residual unbound water between the denuded collagen fibrils, trapped at the bottom of the HL. Consequently, endogenous dentinal enzymes, such as the matrix metalloproteinases (MMPs) and cysteine cathepsins are activated and can degrade the denuded collagen matrix. Strategies for the preservation of the HL over time have been developed, and they entail the removal of the unbound water from the gaps between the collagen fibrils as well as different modes of silencing endogenous enzymatic activity. SIGNIFICANCE: Although there are many more hurdles to be crossed in the field of adhesive dentistry, impressive progress has been achieved so far, and the vast amount of available research on the topic is an indicator of the importance of this matter and of the great efforts of researchers and dental material companies to reach a new level in the quality and longevity of resin-dentin bonds.
Authors: L M Barcelos; M G Borges; C J Soares; M S Menezes; V Huynh; M G Logan; A P P Fugolin; C S Pfeifer Journal: Dent Mater Date: 2020-01-28 Impact factor: 5.304
Authors: Eliseu A Münchow; Adriana F da Silva; Evandro Piva; Carlos E Cuevas-Suárez; Maria T P de Albuquerque; Rodolfo Pinal; Richard L Gregory; Lorenzo Breschi; Marco C Bottino Journal: J Mater Chem B Date: 2020-11-10 Impact factor: 6.331