Haifa Maktabi1, Maria Ibrahim2, Qoot Alkhubaizi1, Michael Weir2, Hockin Xu2, Howard Strassler1, Ana Paula P Fugolin3, Carmem S Pfeifer3, Mary Anne S Melo4. 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.
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 (RE) 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 RE on S. mutans CFU values and DC are dependent on the curing conditions and irradiance (p < 0.05). A negative relationship was observed between RE and biofilm formation. The operator-dependent curing conditions have shown RE 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 RE. 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 RE -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.
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 (RE) 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 RE on S. mutans CFU values and DC are dependent on the curing conditions and irradiance (p < 0.05). A negative relationship was observed between RE and biofilm formation. The operator-dependent curing conditions have shown RE 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 RE. 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 RE -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.
Authors: Fabrício M Collares; Isadora M Garcia; Mariana Klein; Clarissa F Parolo; Felipe Antonio L Sánchez; Antônio Takimi; Carlos P Bergmann; Susana Maria W Samuel; Mary Anne Melo; Vicente Cb Leitune Journal: Polymers (Basel) Date: 2020-04-02 Impact factor: 4.329
Authors: Abdulrahman A Balhaddad; Isadora M Garcia; Haifa Maktabi; Maria Salem Ibrahim; Qoot Alkhubaizi; Howard Strassler; Fabrício M Collares; Mary Anne S Melo Journal: Restor Dent Endod Date: 2021-09-24