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9 results on '"Mathieu, Mouhat"'

1. How does indirect air-cooling influence pulp chamber temperature in different volume teeth and absence/presence of resin-based composite during light curing?

Author

Mathieu Mouhat, Lina Stangvaltaite-Mouhat, Emil Finnäs, Amani Andersen, Anneli Lirhus Evertsen, and Bo W. Nilsen

Subjects
LED dental curing light, Pulp chamber, Temperature, Composite resins, Dentistry, RK1-715
Abstract

Abstract Background Light-curing of materials during restorative dental procedures poses a risk for pulp tissue overheating. Therefore, the aim of this study was to investigate the effect of indirect air-cooling on pulp chamber temperatures during light-curing of varying volume teeth and absence/presence of resin-based composite (RBC) at different exposure time. Methods The volume of 11 human teeth was measured by micro computed tomograph. An experimental rig controlled the thermal environment of the teeth and a thermocouple inserted retrograde into the root canal measured temperature changes. Pulp chamber temperature was measured with and without air-cooling on teeth without and with RBC at 15 s, 30 s and 60 s intervals. Generalized estimating equations were used for statistical analysis. Results The temperature increase with air-cooling (versus no air-cooling) was lower in teeth despite absence/presence of RBC (β = − 4.26, 95%CI − 5.33 and β = − 4.47, 95%CI − 5.60, respectively). With air-cooling, the temperature increase in teeth with RBC was lower compared to teeth without RBC (β = − 0.42, 95%CI -0.79; − 0.05). Higher teeth volume resulted in lower temperature increase with air-cooling than without air-cooling (β = − 0.04, 95%CI -0.07; − 0.01 and β = − 0.17, 95%CI -0.30; − 0.05, respectively). Conclusions Air-cooling resulted in lower pulp chamber temperature increase. Using air-cooling, the temperature increase was lower in teeth with RBC compared to teeth without RBC. Lower volume teeth resulted in higher temperature increase, thus they seemed to benefit more from air-cooling compared to higher volume teeth. Air-cooling could be an effective tool in controlling pulp temperature increase during light-curing, especially when the tooth volume is small.

Published
2022
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2. Quantification of porosity in composite resins delivered by injectable syringes using X-ray microtomography

Author

Bo Wold Nilsen, Mathieu Mouhat, and Asbjørn Jokstad

Subjects
composite resins, porosity, x-ray microtomography, Dentistry, RK1-715
Abstract

Objective To assess whether composite polymer resin delivered in compules include pores and the possible effect on the amount of porosity in dental restorations. Method and materials Original compules containing unpolymerised composite polymer resin (CPR) were scanned in a micro-CT. Four products were examined, which comprised universal composites (Herculite XRV Ultra, Ceram.X Universal, Tetric Evo Ceram) and a flowable bulk-fill composite (SDR) (n = 10 per group). The pore size distribution and amount of porosity (vol.%) were estimated for the unpolymerized and polymerized material used to restore a standardised cavity in a typodont tooth. Manufacturers’ instructions were followed regarding material handling, and polymerisation by use of a calibrated light-curing unit. The pore characteristics and their size distribution, and the amount of porosity in the dental restoration were contrasted with the values measured in the compule. Non-parametric tests were used to analyse differences between the four products. Results All the composite polymer resin compules contained unpolymerised material that included pores. The universal composite compules included pores predominantly in the sub-100 µm sizes. In contrast, the flowable bulk-fill compules included a few pores with a diameter >100 µm, which were assumed to be air-bubbles. The unpolymerised material within the compule included consistently more pores compared to the extruded portion from the compule tip, and in the final restoration (p

Published
2020
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3. In vitro Candida albicans biofilm formation on different titanium surface topographies

Author

Mathieu Mouhat, Robert Moorehead, and Craig Murdoch

Subjects
dental implants, candida albicans, titanium, surface roughness, surface tension, Dentistry, RK1-715
Abstract

Objectives To investigate if differences in titanium implant surface topography influence Candida albicans biofilm formation. Materials and Methods Titanium discs were prepared and characterized using a profilometer: Group A (Ra 0.15 µm, smooth), Group B (Ra 0.64 µm, minimally rough) and Group C (Ra 1.3 µm, moderately rough). Contact angle and surface free energy (SFE) were determined for each group. Non-preconditioned titanium discs were incubated with C. albicans for 24 h. In additional experiments, the titanium discs were initially coated with human saliva, bovine serum albumin or phosphate-buffered saline for 2 h before incubation with C. albicans for 24 h. The amount of fungal biofilm formation was quantified using a colorimetric assay. Results C. albicans biofilm formation was significantly lower (p

Published
2020
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4. Effect of cements on fracture resistance of monolithic zirconia crowns

Author

Keisuke Nakamura, Mathieu Mouhat, John Magnus Nergård, Solveig Jenssen Lægreid, Taro Kanno, Percy Milleding, and Ulf Örtengren

Subjects
Monolithic zirconia crowns, fracture resistance, zinc phosphate cement, glass-ionomer cement, resin-based cement, Dentistry, RK1-715
Abstract

Objectives The present study investigated the effect of cements on fracture resistance of monolithic zirconia crowns in relation to their compressive strength. Materials and methods Four different cements were tested: zinc phosphate cement (ZPC), glass-ionomer cement (GIC), self-adhesive resin-based cement (SRC) and resin-based cement (RC). RC was used in both dual cure mode (RC-D) and chemical cure mode (RC-C). First, the compressive strength of each cement was tested according to a standard (ISO 9917-1:2004). Second, load-to-failure test was performed to analyze the crown fracture resistance. CAD/CAM-produced monolithic zirconia crowns with a minimal thickness of 0.5 mm were prepared and cemented to dies with each cement. The crown–die samples were loaded until fracture. Results The compressive strength of SRC, RC-D and RC-C was significantly higher than those of ZPC and GIC (p

Published
2016
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5. Heat Development in the Pulp Chamber During Curing Process of Resin-Based Composite Using Multi-Wave LED Light Curing Unit

Author

Ulf Örtengren, Bo Wold Nilsen, Torbjørn Haukland, James B. Mercer, and Mathieu Mouhat

Subjects
Exothermic reaction, Molar, chemistry.chemical_classification, Materials science, 0206 medical engineering, Composite number, 030206 dentistry, 02 engineering and technology, Polymer, Resin-Based Composite, medicine.disease_cause, 020601 biomedical engineering, 03 medical and health sciences, 0302 clinical medicine, chemistry, Mold, medicine, Irradiation, Composite material, General Dentistry, Curing (chemistry)
Abstract

Objective The study aimed to investigate factors contributing to heat development during light curing of a flowable bulk-fill resin-based composite (SDRTM, Lot # 602000876, Dentsply Sirona, Konstanz, Germany) (RBC). Materials and Methods Temperatures were measured with calibrated thermocouples. A multi-wave light-emitting diode (LED) light curing unit (LCU) was used (Ivoclar Vivadent, Schaan, Lichtenstein). In all experiments, the RBC was first cured (cured) for 30 s and, after 5 min of recovery time, received a second LCU irradiation (post-cured) for 30 s. The exothermic reaction was measured by calculating the Δ temperature between cured and post-cured RBC. In a cylinder-shaped polymer mold, temperature was recorded inside of RBC during curing (part 1) and light transmission through RBC during curing was investigated (part 2). Pulpal temperatures were assessed in an extracted third molar during light curing (part 3). Data were statistically analyzed using one-way ANOVA (α=0.05). Results Increased thickness of RBC led to decreased pulp chamber temperatures. Inside RBC, there was a large variation in heat development between the cured and post-cured groups (p

Published
2020
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6. Light-curing units used in dentistry: Effect of their characteristics on temperature development in teeth

Author

Ulf Örtengren, Lina Stangvaltaite-Mouhat, Bo Wold Nilsen, Mathieu Mouhat, and James B. Mercer

Subjects
Curing Lights, Dental, Materials science, Infrared, Bench model, Temperature, Light guide, Composite Resins, Light curing, Spectral emission, stomatognathic diseases, stomatognathic system, Thermocouple, Ceramics and Composites, Dental Pulp Cavity, Composite material, General Dentistry, Light-Curing of Dental Adhesives
Abstract

This study aimed to investigate pulp chamber and surface temperature development using different LED light curing units (LCUs). Eight brands of LED-LCUs were tested in a laboratory bench model. The pulp chamber and surface temperature were recorded with a type T thermocouple and infrared cameras, respectively. The highest pulp chamber and surface temperature increase was 6.1±0.3°C and 20.1±1.7°C, respectively. Wide-spectrum LED-LCUs produced higher pulp chamber temperature increase at 0 mm and 2 mm but lower at 4 mm. Narrow-spectrum LED-LCUs produced higher surface temperature increase. LED-LCU featuring modulated output mode resulted in lower increase in pulp chamber temperature but higher on surface temperature. LED-LCU with light guide tip delivering an inhomogeneous beam caused higher increase in temperature on the surface and in the pulp chamber. LED-LCUs with different spectral emission, output mode and light guide tip design contributed to different temperature development in the pulp chamber and at the surface of teeth.

Published
2021

7. Heat Development in the Pulp Chamber During Curing Process of Resin-Based Composite Using Multi-Wave LED Light Curing Unit

Author

Bo Wold, Nilsen, Mathieu, Mouhat, Torbjørn, Haukland, Ulf Thore, Örtengren, and James B, Mercer

Subjects
dentistry, composite resins, LED dental curing light, temperature, pulp chamber, Original Research
Abstract

Objective The study aimed to investigate factors contributing to heat development during light curing of a flowable bulk-fill resin-based composite (SDRTM, Lot # 602000876, Dentsply Sirona, Konstanz, Germany) (RBC). Materials and Methods Temperatures were measured with calibrated thermocouples. A multi-wave light-emitting diode (LED) light curing unit (LCU) was used (Ivoclar Vivadent, Schaan, Lichtenstein). In all experiments, the RBC was first cured (cured) for 30 s and, after 5 min of recovery time, received a second LCU irradiation (post-cured) for 30 s. The exothermic reaction was measured by calculating the Δ temperature between cured and post-cured RBC. In a cylinder-shaped polymer mold, temperature was recorded inside of RBC during curing (part 1) and light transmission through RBC during curing was investigated (part 2). Pulpal temperatures were assessed in an extracted third molar during light curing (part 3). Data were statistically analyzed using one-way ANOVA (α=0.05). Results Increased thickness of RBC led to decreased pulp chamber temperatures. Inside RBC, there was a large variation in heat development between the cured and post-cured groups (p

Published
2020

8. Effect of cements on fracture resistance of monolithic zirconia crowns

Author

John Magnus Nergård, Percy Milleding, Taro Kanno, Ulf Örtengren, Mathieu Mouhat, Keisuke Nakamura, and Solveig Jenssen Lægreid

Subjects
musculoskeletal diseases, Materials science, medicine.medical_treatment, 0206 medical engineering, Glass ionomer cement, 02 engineering and technology, Crown (dentistry), Article, 03 medical and health sciences, 0302 clinical medicine, stomatognathic system, medicine, General Materials Science, Composite material, Cement, Significant difference, Monolithic zirconia, technology, industry, and agriculture, 030206 dentistry, Monolithic zirconia crowns, fracture resistance, equipment and supplies, 020601 biomedical engineering, lcsh:RK1-715, Compressive strength, surgical procedures, operative, glass-ionomer cement, lcsh:Dentistry, Fracture (geology), Original Article, resin-based cement, zinc phosphate cement, Zinc Phosphate Cement
Abstract

Objectives - The present study investigated the effect of cements on fracture resistance of monolithic zirconia crowns in relation to their compressive strength. Materials and methods - Four different cements were tested: zinc phosphate cement (ZPC), glass-ionomer cement (GIC), self-adhesive resin-based cement (SRC) and resin-based cement (RC). RC was used in both dual cure mode (RC-D) and chemical cure mode (RC-C). First, the compressive strength of each cement was tested according to a standard (ISO 9917-1:2004). Second, load-to-failure test was performed to analyze the crown fracture resistance. CAD/CAM-produced monolithic zirconia crowns with a minimal thickness of 0.5 mm were prepared and cemented to dies with each cement. The crown–die samples were loaded until fracture. Results - The compressive strength of SRC, RC-D and RC-C was significantly higher than those of ZPC and GIC (p Conclusion - The values achieved in the load-to-failure test suggest that monolithic zirconia crowns with a minimal thickness of 0.5 mm may have good resistance against fracture regardless of types of cements.

Published
2016

9. Light-curing units used in dentistry: factors associated with heat development-potential risk for patients

Author

Mathieu Mouhat, Lina Stangvaltaite, Ulf Örtengren, and James B. Mercer

Subjects
Curing Lights, Dental, Hot Temperature, Light, Dentistry, 02 engineering and technology, In Vitro Techniques, Light curing, 03 medical and health sciences, Patient safety, 0302 clinical medicine, stomatognathic system, Risk Factors, Medicine, Humans, General Dentistry, Dental Pulp Cavity, Dentistry(all), business.industry, Potential risk, Temperature, Reproducibility of Results, 030206 dentistry, 021001 nanoscience & nanotechnology, VDP::Medisinske Fag: 700::Klinisk odontologiske fag: 830, VDP::Medical disciplines: 700::Clinical dentistry disciplines: 830, Curing lights, Thermography, Molar, Third, Original Article, Patient Safety, 0210 nano-technology, business, Tooth
Abstract

Source: doi: 10.1007/s00784-016-1962-5 Objectives:To investigate how heat development in the pulp chamber and coronal surface of natural teeth with and without cusps subjected to irradiance using light-emitting diode (LED)–light-curing units (LCUs) is associated with (i) irradiance, (ii) time, (iii) distance, and (iv) radiant exposure. Materials and methods:Three different LED-LCUs were used. Their irradiance was measured with a calibrated spectrometer (BlueLight Analytics Inc., Halifax, Canada). An experimental rig was constructed to control the thermal environment of the teeth. The LED-LCU tip position was accurately controlled by a gantry system. Tooth surface temperature was measured by thermography (ThermaCAM S65 HS, FLIR Systems, Wilsonville, USA) and pulp chamber temperature with a thermocouple. LED-LCU tip distance and irradiation times tested were 0, 2, and 4 mm and 10, 20, and 30 s, respectively. Ethical permission was not required for the use of extracted teeth. Results:Maximum surface and pulp chamber temperatures were recorded in tooth without cusps (58.1 °C ± 0.9 °C and 43.1 °C ± 0.9 °C, respectively). Radiant exposure explained the largest amount of variance in temperature, being more affected by time than irradiance. Conclusions:At all combinations of variables tested, repeated measurements produced consistent results indicating the reliability of the method used. Increased exposure time seems to be the factor most likely to cause tissue damage. Clinical relevance:Risk of superficial tissue damage at irradiances >1200 mW/cm2 is evident. There is a risk of pulp damage when only thin dentin is left at higher irradiances (>1200 mW/cm2). Clinicians should be aware of LED-LCU settings and possible high temperature generated.

Published
2016

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