Chlorhexidine preserves the hybrid layer in vitro after 10-years aging

Lorenzo Breschi; Tatjana Maravic; Allegra Comba; Sandra Ribeiro Cunha; Alessandro D Loguercio; Alessandra Reis; Viviane Hass; Milena Cadenaro; Edoardo Mancuso; Eric Mayer-Santos; Lina Niu; David H Pashley; Franklin R Tay; Annalisa Mazzoni

doi:10.1016/j.dental.2020.03.009

Chlorhexidine preserves the hybrid layer in vitro after 10-years aging

Dent Mater. 2020 May;36(5):672-680. doi: 10.1016/j.dental.2020.03.009. Epub 2020 Apr 10.

Authors

Affiliations

¹ Department of Biomedical and Neuromotor Sciences, University of Bologna, Via San Vitale 59, 40125 Bologna, Italy. Electronic address: lorenzo.breschi@unibo.it.
² Department of Biomedical and Neuromotor Sciences, University of Bologna, Via San Vitale 59, 40125 Bologna, Italy. Electronic address: tatjana.maravic2@unibo.it.
³ Department of Biomedical and Neuromotor Sciences, University of Bologna, Via San Vitale 59, 40125 Bologna, Italy. Electronic address: allegra.comba@unibo.it.
⁴ Department of Restorative Dentistry, College of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes 2227, 05508-000 São Paulo, Brazil; Department of Operative Dentistry, College of Dentistry, University of Iowa, Iowa City, IA, USA. Electronic address: sandra-cunha@uiowa.edu.
⁵ School of Dentistry, Department of Restorative Dentistry, State University of Ponta Grossa, Rua Carlos Cavalcanti, 4748, Bloco M, Sala 64A-Uvaranas, Ponta Grossa, Paraná CEP 84030-900, Brazil. Electronic address: alelog@uepg.br.
⁶ School of Dentistry, Department of Restorative Dentistry, State University of Ponta Grossa, Rua Carlos Cavalcanti, 4748, Bloco M, Sala 64A-Uvaranas, Ponta Grossa, Paraná CEP 84030-900, Brazil. Electronic address: alereis@uepg.br.
⁷ School of Dentistry, Oral & Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, 650 E 25th St, Kansas City, MO 64108, USA; Postgraduate Program in Dentistry, Biomaterials, University of Northern Parana, Av. Paris, 675 - Jardim Piza, Londrina - Paraná 86041-100, Brazil. Electronic address: hassv@umkc.edu.
⁸ University of Trieste, Trieste, Italy; Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Via dell'Istria, 65, Trieste, 34137, Italy. Electronic address: mcadenaro@units.it.
⁹ Department of Biomedical and Neuromotor Sciences, University of Bologna, Via San Vitale 59, 40125 Bologna, Italy. Electronic address: edoardo.mancuso2@unibo.it.
¹⁰ Department of Restorative Dentistry, College of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes 2227, 05508-000 São Paulo, Brazil. Electronic address: eric.mayer.santos@usp.br.
¹¹ School of Stomatology, The Fourth Military Medical University, Shaanxi, China. Electronic address: niulina@fmmu.edu.cn.
¹² The Dental College of Georgia, Augusta University, 1430 John Wesley Gilbert Drive, Augusta, GA, USA. Electronic address: ednapashley@gmail.com.
¹³ The Dental College of Georgia, Augusta University, 1430 John Wesley Gilbert Drive, Augusta, GA, USA. Electronic address: ftay@augusta.edu.
¹⁴ Department of Biomedical and Neuromotor Sciences, University of Bologna, Via San Vitale 59, 40125 Bologna, Italy. Electronic address: annalisa.mazzoni@unibo.it.

PMID: 32284197
DOI: 10.1016/j.dental.2020.03.009

Abstract

Objective: The present study investigated the ability of a chlorhexidine (CHX)-containing primer (0.2% aqueous solution) to inhibit dentinal enzymes, preserve the hybrid layer (HL) and remain within the HL, after 10 years of aging in artificial saliva at 37°C.

Methods: Non-carious extracted molars were assigned to two groups, cut into slabs exposing middle/deep dentin, etched and bonded with Adper Scotchbond 1XT (SB1XT) with or without 0.2% CHX aqueous solution pretreatment. Composite build-ups were made, and the specimens were cut in 1-mm thick bonded sticks. In situ zymography was performed on freshly prepared specimens (T₀) and specimens aged for 10 years (T_10-yr) at 37°C in artificial saliva, to investigate endogenous gelatinolytic activity within the HL. At T_10-yr, specimens were also decalcified and embedded in epoxy resin for TEM analysis. Micro-Raman spectroscopy was performed at T₀ and T_10-yr to evaluate the chemical profiles in intertubular dentin and the HL.

Results: In situ zymography showed less pronounced enzymatic activity in the CHX-pretreated group (p<0.05) regardless of aging, maintaining a similar level of fluorescence at T₀ and T_10-yr (p>0.05). TEM results showed that 98% of the HL had been degraded in the control group, while 95% of the HL was intact in the experimental group. Moreover, all the Raman spectra peaks assigned to CHX could be identified only in the CHX-pretreated group (T₀ and T_10-yr).

Significance: In vitro, CHX remains in the HL after 10 years with its inhibitory effect preserved. This may be the underlying factor for HL preservation after this long aging period.

Keywords: Dentin bonding agents; Hybrid layer; In situ zymography; In vitro aging; MMPs inhibitors; Raman spectroscopy; TEM.

MeSH terms

Chlorhexidine* / pharmacology
Composite Resins
Dental Bonding*
Dentin
Dentin-Bonding Agents
Materials Testing
Resin Cements
Tensile Strength

Substances

Composite Resins
Dentin-Bonding Agents
Resin Cements
Chlorhexidine