Underperforming light curing procedures trigger detrimental irradiance-dependent biofilm response on incrementally placed dental composites

Haifa Maktabi; Maria Ibrahim; Qoot Alkhubaizi; Michael Weir; Hockin Xu; Howard Strassler; Ana Paula P Fugolin; Carmem S Pfeifer; Mary Anne S Melo

doi:10.1016/j.jdent.2019.04.003

Underperforming light curing procedures trigger detrimental irradiance-dependent biofilm response on incrementally placed dental composites

J Dent. 2019 Sep:88:103110. doi: 10.1016/j.jdent.2019.04.003. Epub 2019 Apr 22.

Authors

Haifa Maktabi¹, Maria Ibrahim², Qoot Alkhubaizi¹, Michael Weir², Hockin Xu², Howard Strassler¹, Ana Paula P Fugolin³, Carmem S Pfeifer³, Mary Anne S Melo⁴

Affiliations

¹ Division of Operative Dentistry, Department of General Dentistry, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.
² Ph.D. Program in Biomedical Sciences, Division of Biomaterials & Tissue Engineering, Dept. of Advanced Oral Sciences and Therapeutics, University of Maryland Dental School, Baltimore, MD 21201, USA.
³ Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University, Portland, OR 97239, USA.
⁴ Division of Operative Dentistry, Department of General Dentistry, University of Maryland School of Dentistry, Baltimore, MD 21201, USA; Ph.D. Program in Biomedical Sciences, Division of Biomaterials & Tissue Engineering, Dept. of Advanced Oral Sciences and Therapeutics, University of Maryland Dental School, Baltimore, MD 21201, USA. Electronic address: Mmelo@umaryland.edu.

PMID: 31022421
DOI: 10.1016/j.jdent.2019.04.003

Abstract

Objectives: Insufficient radiant exposure (J/cm²) may provide an early trigger in a cascade of detrimental responses on incrementally-place composite, especially the bottom layer. This study aimed to assess the influence of poor radiant exposure, the degree of conversion (%DC), water sorption/ solubility and S. mutans biofilm formation on conventional, incrementally placed composites and to establish a relationship between these factors.

Methods: Two light units operating at 600 and 1000 mW/cm² and four most common operator-dependent curing conditions had the radiant exposure (R_E) recorded. All the specimens were subjected to S. mutans biofilm model for 14 days. The %DC, biofilm formation expressed by colony-forming units (CFU), water sorption/ solubility and surface roughness/ SEM were assessed. Data were submitted to two-way ANOVA and Tukey post-hoc test (α = 0.05). Pearson correlation was also determined.

Results: The influence of R_E on S. mutans CFU values and DC are dependent on the curing conditions and irradiance (p < 0.05). A negative relationship was observed between R_E and biofilm formation. The operator-dependent curing conditions have shown R_E reduction varying from 49.4% to 73.5% in relation to control. The difference in DC between top/bottom of cylinder varied from 13% to 21% for 1000 mW/cm²and from 29% to 53% for LCU600. The roughness, solubility and salivary sorption were greater for low R_E.

Conclusion: Poor, deficient curing procedures provide an early trigger in a negative pathway of events for incrementally-place dental composite including a biological response by increased biofilm formation by S. mutans, a relevant factor for secondary caries development.

Significance: The susceptibility to variation in the outcomes was R_E -dependent. The optimization of the curing procedures ensures the maximum performance in the chain of events involved in the light curing process of resin-based materials and potentially reduce the risk factors of secondary caries development.

Keywords: Light curing; Oral biofilm; Resin composite; S. mutans; The degree of conversion.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bacterial Adhesion
Biofilms / radiation effects*
Composite Resins / chemistry
Composite Resins / radiation effects*
Curing Lights, Dental*
Dental Materials
Humans
Light-Curing of Dental Adhesives / methods*
Materials Testing
Solubility
Streptococcus mutans
Water / chemistry

Substances

Composite Resins
Dental Materials
Water