Richard Price - Academia.edu (original) (raw)

Papers by Richard Price

PLOS ONE

Background Given the increasing use of photo-activated resins in dentistry, dentists and research... more Background Given the increasing use of photo-activated resins in dentistry, dentists and researchers need a user-friendly dental radiometer to measure the power output from dental light-curing units (LCUs). Objective Our goal was to measure the accuracy of two brands of dental radiometers in reporting the power (mW) from twelve brands of contemporary LCUs compared to a ‘gold standard’ (GS) reference value obtained from an integrating sphere attached to a fiberoptic spectroradiometer. Methods The power output was measured from two units of 12 brands of LCUs, five times on the ‘‘GS” system, five times on two Bluephase Meter II dental radiometers, and five times on two Mini Gig hand-held spectroradiometers. The emission spectrum was also recorded using the ‘GS’ integrating sphere. The power values reported by each meter were subjected to t-tests to compare the two examples of each LCU, and 3-way ANOVA followed by Bonferroni’s post-hoc tests. Regression analyses were also performed to d...

The Journal of the American Dental Association, 2019

wing to increased demand for natural-looking esthetic restorations, environmental concerns about ... more wing to increased demand for natural-looking esthetic restorations, environmental concerns about the mercury in amalgam restorations, and the Minamata Convention on Mercury, which requires a phase-down in the use of dental amalgam, 1 there has been a steady increase in the use of resin-based composite over the last decade. 2,3 Placing composite restorations is a technique-sensitive procedure requiring that sufficient quantities of light, at the appropriate spectra, be delivered to the resin-based composite. However, it appears that light polymerization by dentists using light polymerization units (LPUs) does not always receive the attention it merits. 4 In contemporary dental practice, light-emitting diode (LED) LPUs have now become ubiquitous to polymerize lightsensitive restorations. 5 It is often stated that if radiant exposure of approximately 16 joules per square centimeter is delivered to a 2-millimeterethick increment of resin-based composite, then the material will be adequately polymerized. 6-8 However, this minimum radiant exposure can vary depending on the specific brand, shade, material properties, and chemical formulation. 6-10 Many contemporary LPUs have radiant exitant (RE) levels higher than 1,500 milliwatts per square centimeter; however, their spectral irradiance, radiant power, and corresponding tip sizes vary greatly. Because there is a limit on how fast the polymerization reaction can occur, the final degree of conversion of a resin-based composite, as well as its ultimate shrinkage stress value, is affected by the RE and the corresponding rate of polymerization. 11,12 Thus, there is no true reciprocity between RE and time to deliver the same radiant exposure. 13 Numerous studies have examined the performance of LPUs in private dental practices and, so far, they have all reported that deficiencies existed in many of the LPUs examined. Many previous studies used dental radiometers to measure RE, but some studies also used microhardness measurements of resin-based composites polymerized with these LPUs as well. 14-29 However, because dental radiometers are known to be inaccurate, 30 the RE and the radiant exposure values reported in these studies may also be inaccurate. A previous study reported 3 assessment categories for RE values: sufficient intensity (400 milliwatts per square centimeter and higher), 201 through 399 mW/cm 2 (marginal intensity), and 200 mW/cm 2 or less (low intensity). 16 Seven international studies have stated that their cutoff RE value was 300 mW/cm 2. 18-20,22,26-28 Three studies considered the

Operative Dentistry, 2017

SUMMARY Purpose: This study examined the influence of different emission spectra (single-peak and... more SUMMARY Purpose: This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm2 on the polymerization and light transmission of four resin-based composites (RBCs). Methods and Materials: Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm2) or high irradiance (3600 mW/cm2) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradi...

European Journal of General Dentistry

Objectives The manufacturers of budget light-curing units (LCUs) often claim to provide high-qual... more Objectives The manufacturers of budget light-curing units (LCUs) often claim to provide high-quality units that are equivalent to LCUs from major manufacturers. This study investigated the effects of battery discharge on the light output from different budget LCUs compared to a major manufacturer. Materials and Methods Two brands of budget LCUs (LY-A180 and LED-CL) were compared to a control LCU from a major manufacturer (3M). The LCUs were fully charged, and their light outputs were measured over one battery discharge cycle using repeated 10-second exposures at a 0-mm distance. Statistical Analysis Data were analyzed using one-way analysis of variance and Bonferroni post-hoc test. Results The budget LCUs delivered fluctuating light output values. In their first exposure, the budget LCUs delivered between 205 and 444 mW power, an irradiance between 533 and 1154 mW/cm2, and a radiant exposure between 5.3 and 11.5 J/cm2. As the number of exposures increased, their light output decreas...

Operative Dentistry, 2018

SUMMARY Objective: To evaluate the effects of different mold materials, their diameters, and ligh... more SUMMARY Objective: To evaluate the effects of different mold materials, their diameters, and light-curing units on the mechanical properties of three resin-based composites (RBC). Methods and Materials: A conventional nano-filled resin composite (Filtek Supreme Ultra, 3M Oral Care, St Paul, MN, USA) and two bulk-fill composites materials, Tetric Evoceram Bulk fill (Ivoclar Vivadent, Schaan, Liechtenstein) and Aura Bulk Fill (SDI, Bayswater, VIC, Australia), were tested. A total of 240 specimens were fabricated using metal or white semitransparent Delrin molds that were 4 or 10 mm in diameter. The RBCs were light cured for 40 seconds on the high-power setting of either a monowave (DeepCure-S, 3M Oral Care) or polywave (Bluephase G2, Ivoclar Vivadent) light-emitting diode (LED) curing unit. The depth of cure was determined using a scraping test, according to the 2009 ISO 4049 test method. Data were analyzed using multivariate analysis of variance followed by Tukey multiple comparison ...

International Endodontic Journal, 2009

Kodonas K, Gogos C, Tziafas D. Effect of simulated pulpal microcirculation on intrapulpal tempera... more Kodonas K, Gogos C, Tziafas D. Effect of simulated pulpal microcirculation on intrapulpal temperature changes following application of heat on tooth surfaces. International Endodontic

Operative Dentistry, 2016

SUMMARY Recently, “budget” dental light-emitting diode (LED)–based light-curing units (LCUs) have... more SUMMARY Recently, “budget” dental light-emitting diode (LED)–based light-curing units (LCUs) have become available over the Internet. These LCUs claim equal features and performance compared to LCUs from major manufacturers, but at a lower cost. This study examined radiant power, spectral emission, beam irradiance profiles, effective emission ratios, and the ability of LCUs to provide sustained output values during the lifetime of a single, fully charged battery. Three examples of each budget LCU were purchased over the Internet (KY-L029A and KY-L036A, Foshan Keyuan Medical Equipment Co, and the Woodpecker LED.B, Guilin Woodpecker Medical Instrument Co). Major dental manufacturers provided three models: Elipar S10 and Paradigm (3M ESPE) and the Bluephase G2 (Ivoclar Vivadent). Radiant power emissions were measured using a laboratory-grade thermopile system, and the spectral emission was captured using a spectroradiometer system. Irradiance profiles at the tip end were measured using...

The International journal of prosthodontics, 2021

PURPOSE To evaluate the effect of tooth brushing and dentifrice fluoride (F-) concentration on ch... more PURPOSE To evaluate the effect of tooth brushing and dentifrice fluoride (F-) concentration on changes in color and translucency (ΔE00 and ΔT00, respectively), surface gloss (GS), surface roughness (Sa), and microstructure of a glazed CAD/CAM ceramic. MATERIALS AND METHODS Ceramic blocks (e.max/CAD) were sectioned into rectangular plates (14 x 12 x 1 mm), and one surface of each sample was glazed. Samples were divided into three groups according to the F- concentration in the dentifrice (0, 1,100, and 5,000 μg/g) and were then subjected to 60,000 tooth brushing cycles. Luminosity and color were measured using a spectrophotometer at baseline and after every 20,000 cycles to obtain their ΔE00 and ΔT00 values. Another set of samples was prepared to measure the GS with a gloss meter and the Sa with a confocal laser microscope. The GS and Sa results were subjected to analysis of variance, Tukey test, and Dunnett test (α = .05). RESULTS After 60,000 tooth brushing cycles, all of the varia...

Iranian Endodontic Journal, 2014

Introduction: The aim of this descriptive cross-sectional study was to assess the general dental ... more Introduction: The aim of this descriptive cross-sectional study was to assess the general dental practitioners (GDPs)’s knowledge regarding the emergency management of traumatic dental injuries (TDI) in Isfahan, Iran. Methods and Materials: In this study a two-part questionnaire consisting of 14 questions was distributed among 241 GDPs. Part 1 included seven questions focusing on personal and professional information and part 2 asked questions about seven given cases of dental traumas. One score was dedicated to each correct answer; the total score of 0 to 4 was considered as poor knowledge, while scores 5-8, 9-11 and 12-14 were assigned as moderate, good and excellent knowledge, respectively. The data were analyzed using the Student’s t-test and one-way ANOVA. Spearman’s and Pearson’s correlation coefficient were used to determine the associations between the emergency treatment knowledge and dentists’ professional information. Results: With regards to the level of GDP’s knowledge,...

Dental Materials, 2018

To evaluate how the light delivered to resin-composites was described in recent articles. Method:... more To evaluate how the light delivered to resin-composites was described in recent articles. Method: PubMed was searched for 300 articles published between January 2017 and May 2018 with keywords relating to photocuring of dental materials. The articles examined a wide range of resin-composite properties and performance. For each article, the information provided about the light curing unit (LCU), the light curing conditions and the characteristics and quantity of the light used in the study were recorded. Specifically, the type of LCU used; the irradiance; how the irradiance was measured; the exposure times; whether the light energy (radiant exposure) received by the specimen was determined, or if only the light output at the LCU tip was measured; whether the distance between the tip of the LCU and the specimen was reported; and whether the emission spectrum from the LCU was reported. Where possible, the resin manufacturer's minimum energy requirement (MER: the product of the recommended minimum exposure time and irradiance) was compared to the radiant exposure delivered to the specimen. Results: Of the 300 articles examined, 217 were published in 2017 and 83 in 2018. Of these articles, 130 (43%) were found in open access journals, and 170 (57%) were in subscription-based journals. The name of the LCU used was not provided in 31 articles, 14 articles did not provide the exposure time, and 227 articles did not report the distance to the specimen. An irradiance value was reported in 231 articles, but this was the irradiance received by the specimen in only 48 instances. The emission spectrum from the LCU was reported in 15 articles. There was a large range in the radiant exposures from below 10 J/cm 2 to greater than 100 J/cm 2 .

Operative dentistry

I do not remember a time during my dental career when direct resin restorations were not being di... more I do not remember a time during my dental career when direct resin restorations were not being disparaged by someone. Some of the expressed concerns have validity. Certainly the earlier composite resins offered little wear resistance or ability to predictably create a bonded interface. The chemical activation system used in early materials also limited the ability of a practitioner to form and sculpt restorations. I remember being taught that the placement of a composite resin restoration should include the same level of care and attention to detail provided to direct gold restorations. I have held the opinion that many of the problems associated with composite resin restorations can be attributed to approaching their placement in a way that mimics the approach taken when placing amalgam, a material that is much more forgiving of less-than-optimal handling. An important issue in the placement of lightactivated composite resin is the amount and type of light energy that is actually being received by the material. Inadequate light curing can easily result in compromised restorative material properties, compromises that likely have a negative influence on restoration longevity. It has been well documented that, worldwide, many offices have been using inadequate amounts of energy and less-thanoptimal technique and are delivering inadequate amounts of energy when light curing resins. 1-9 If that is the case, then it should be no surprise to anyone when reading reports about the substandard performance of posterior composite resin restorations. 10-13

British Dental Journal, 1996

The Journal of the American Dental Association

The perils of online purchasing ... ( https://authors.elsevier.com/a/1edif\_46QxGnd )

Operative Dentistry, 2018

SUMMARY Objectives: This study compared light transmission through different thicknesses of bulk-... more SUMMARY Objectives: This study compared light transmission through different thicknesses of bulk-fill resin-based composites (RBCs) using a polywave and a single-peak light-emitting diode light-curing unit (LCU). The effect on the surface hardness was also evaluated. Methods: Five bulk-fill RBCs were tested. Specimens (n=5) of 1-, 2-, 4-, or 6-mm thickness were photopolymerized for 10 seconds from the top using a polywave (Bluephase Style) or single–peak (Elipar S10) LCU, while a spectrophotometer monitored in real time the transmitted irradiance and radiant exposure reaching the bottom of the specimen. After 24 hours of storage in distilled water at 37°C, the Vickers microhardness (VH) was measured at top and bottom. Results were analyzed using multiple-way analysis of variance, Tukey post hoc tests, and multivariate analysis (α=0.05). Results: The choice of LCU had no significant effect on the total amount of light transmitted through the five bulk-fill RBCs at each thickness. The...

Bioorganic & Medicinal Chemistry Letters, 2000

ÐA series of monocyclic and bicyclic amino acids have been synthesised and incorporated into thro... more ÐA series of monocyclic and bicyclic amino acids have been synthesised and incorporated into thrombin inhibitors based on CGH728, an analogue of the Mitsubishi compound MD805. Benzthiazolylalanine (Bta) was found to be a good non-polar substitute for arginine at the P1 position, yielding compounds with low nanomolar potency and good selectivity for thrombin.

The journal of adhesive dentistry, 2018

The use of resin-based composites, both clinically and for laboratory studies, continues to incre... more The use of resin-based composites, both clinically and for laboratory studies, continues to increase. As is well known, the quantity (radiant exposure in J/cm2) and characteristics (wavelength in mW/nm and beam profile) of light delivered to a photocured resin will have a significant impact on its polymerization. The nature of light emitting diodes (LEDs) means that, unlike halogen (QTH) light sources, they can only produce a narrow emission spectrum. Thus, not all LED light-curing units (LCUs) deliver the same wavelengths of light and, in order to produce a broad spectrum of light, LED LCUs must contain multiple LEDs. Depending on the optical design of the LCU, both the emission spectrum and the radiant emittance may be non-uniformly distributed across the light tip of the LCU. Furthermore, the irradiance and the beam profile of the light received by the resin will change as the distance from the light tip to the composite surface increases. If we wish for research that requires th...

STOMATOLOGY EDU JOURNAL, 2018

Fifty years ago, for the most part, all the dentist had to know about direct restorative material... more Fifty years ago, for the most part, all the dentist had to know about direct restorative materials was how to use dental amalgam and silicate cement. The preparation design for amalgams was well understood, and mechanical retention was a fundamental requirement. Reliable adhesion to both dentin and enamel was utopian, metal free ceramics were not durable, and light-cured resins had yet to be developed. Today, we have a multitude of materials and techniques that enable the dentist to produce direct and indirect restorations that are practically undetectable for both the dentist and the patient. However, there are tremendous consequences from having so many restorative materials and techniques available, and it has become more and more difficult for both practitioners and university professors to find their way through what is now considered a restorative jungle. On the one side, the internet offers in milliseconds a vast amount of information, which often sounds interesting and authoritative but, unfortunately, it is not always correct. Most dental schools claim to teach evidence-based dentistry and focus on providing treatment recommendations that are free from bias and based on prospective randomized double-blinded clinical trials. This approach should ascertain the truth, but has some severe disadvantages. Firstly, it requires a long time for valid results to be produced; secondly, patients cannot be standardized; thirdly, there is often an element of bias in that the exclusion criteria for the very studies that we rely on often eliminate some significant parts of populations that are candidates for the treatment being evaluated. Finally, ethical considerations often limit the questions that can be asked from a prospective randomized, double-blinded clinical trial. This is further compounded by the fact that it has been estimated that more than 95% of recent prosthodontic and implant review articles failed to use search strategies that were systematic, thus undermining the conclusions upon which treatment decisions are based [1]. One solution to the problems described above is a consensus conference. The principle is the following: experts, key opinion leaders, who represent the profession and industry come prepared to discuss a well-defined topic. Based on all their combined scientific, clinical and epidemiologic knowledge, together with presentations, a structured discussion occurs, in which proven, accepted information is sorted out from less valid information. In essence, this is now peer review by some 50 key opinion leaders instead of peer review by 2 or 3 selected reviewers for a 'peer reviewed' journal publication. At the end of such a conference, a draft consensus paper is formulated, which is subsequently reviewed, edited and approved by those key opinion leaders. The Northern Light conferences at Dalhousie University in Halifax (Canada) have produced such recommendations for the light curing of direct restorations (2014) [2-4], dental light-curing units (2015) [5], bulk-fill restorations (2016)

PLOS ONE

Background Given the increasing use of photo-activated resins in dentistry, dentists and research... more Background Given the increasing use of photo-activated resins in dentistry, dentists and researchers need a user-friendly dental radiometer to measure the power output from dental light-curing units (LCUs). Objective Our goal was to measure the accuracy of two brands of dental radiometers in reporting the power (mW) from twelve brands of contemporary LCUs compared to a ‘gold standard’ (GS) reference value obtained from an integrating sphere attached to a fiberoptic spectroradiometer. Methods The power output was measured from two units of 12 brands of LCUs, five times on the ‘‘GS” system, five times on two Bluephase Meter II dental radiometers, and five times on two Mini Gig hand-held spectroradiometers. The emission spectrum was also recorded using the ‘GS’ integrating sphere. The power values reported by each meter were subjected to t-tests to compare the two examples of each LCU, and 3-way ANOVA followed by Bonferroni’s post-hoc tests. Regression analyses were also performed to d...

The Journal of the American Dental Association, 2019

wing to increased demand for natural-looking esthetic restorations, environmental concerns about ... more wing to increased demand for natural-looking esthetic restorations, environmental concerns about the mercury in amalgam restorations, and the Minamata Convention on Mercury, which requires a phase-down in the use of dental amalgam, 1 there has been a steady increase in the use of resin-based composite over the last decade. 2,3 Placing composite restorations is a technique-sensitive procedure requiring that sufficient quantities of light, at the appropriate spectra, be delivered to the resin-based composite. However, it appears that light polymerization by dentists using light polymerization units (LPUs) does not always receive the attention it merits. 4 In contemporary dental practice, light-emitting diode (LED) LPUs have now become ubiquitous to polymerize lightsensitive restorations. 5 It is often stated that if radiant exposure of approximately 16 joules per square centimeter is delivered to a 2-millimeterethick increment of resin-based composite, then the material will be adequately polymerized. 6-8 However, this minimum radiant exposure can vary depending on the specific brand, shade, material properties, and chemical formulation. 6-10 Many contemporary LPUs have radiant exitant (RE) levels higher than 1,500 milliwatts per square centimeter; however, their spectral irradiance, radiant power, and corresponding tip sizes vary greatly. Because there is a limit on how fast the polymerization reaction can occur, the final degree of conversion of a resin-based composite, as well as its ultimate shrinkage stress value, is affected by the RE and the corresponding rate of polymerization. 11,12 Thus, there is no true reciprocity between RE and time to deliver the same radiant exposure. 13 Numerous studies have examined the performance of LPUs in private dental practices and, so far, they have all reported that deficiencies existed in many of the LPUs examined. Many previous studies used dental radiometers to measure RE, but some studies also used microhardness measurements of resin-based composites polymerized with these LPUs as well. 14-29 However, because dental radiometers are known to be inaccurate, 30 the RE and the radiant exposure values reported in these studies may also be inaccurate. A previous study reported 3 assessment categories for RE values: sufficient intensity (400 milliwatts per square centimeter and higher), 201 through 399 mW/cm 2 (marginal intensity), and 200 mW/cm 2 or less (low intensity). 16 Seven international studies have stated that their cutoff RE value was 300 mW/cm 2. 18-20,22,26-28 Three studies considered the

Operative Dentistry, 2017

SUMMARY Purpose: This study examined the influence of different emission spectra (single-peak and... more SUMMARY Purpose: This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm2 on the polymerization and light transmission of four resin-based composites (RBCs). Methods and Materials: Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm2) or high irradiance (3600 mW/cm2) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradi...

European Journal of General Dentistry

Objectives The manufacturers of budget light-curing units (LCUs) often claim to provide high-qual... more Objectives The manufacturers of budget light-curing units (LCUs) often claim to provide high-quality units that are equivalent to LCUs from major manufacturers. This study investigated the effects of battery discharge on the light output from different budget LCUs compared to a major manufacturer. Materials and Methods Two brands of budget LCUs (LY-A180 and LED-CL) were compared to a control LCU from a major manufacturer (3M). The LCUs were fully charged, and their light outputs were measured over one battery discharge cycle using repeated 10-second exposures at a 0-mm distance. Statistical Analysis Data were analyzed using one-way analysis of variance and Bonferroni post-hoc test. Results The budget LCUs delivered fluctuating light output values. In their first exposure, the budget LCUs delivered between 205 and 444 mW power, an irradiance between 533 and 1154 mW/cm2, and a radiant exposure between 5.3 and 11.5 J/cm2. As the number of exposures increased, their light output decreas...

Operative Dentistry, 2018

SUMMARY Objective: To evaluate the effects of different mold materials, their diameters, and ligh... more SUMMARY Objective: To evaluate the effects of different mold materials, their diameters, and light-curing units on the mechanical properties of three resin-based composites (RBC). Methods and Materials: A conventional nano-filled resin composite (Filtek Supreme Ultra, 3M Oral Care, St Paul, MN, USA) and two bulk-fill composites materials, Tetric Evoceram Bulk fill (Ivoclar Vivadent, Schaan, Liechtenstein) and Aura Bulk Fill (SDI, Bayswater, VIC, Australia), were tested. A total of 240 specimens were fabricated using metal or white semitransparent Delrin molds that were 4 or 10 mm in diameter. The RBCs were light cured for 40 seconds on the high-power setting of either a monowave (DeepCure-S, 3M Oral Care) or polywave (Bluephase G2, Ivoclar Vivadent) light-emitting diode (LED) curing unit. The depth of cure was determined using a scraping test, according to the 2009 ISO 4049 test method. Data were analyzed using multivariate analysis of variance followed by Tukey multiple comparison ...

International Endodontic Journal, 2009

Kodonas K, Gogos C, Tziafas D. Effect of simulated pulpal microcirculation on intrapulpal tempera... more Kodonas K, Gogos C, Tziafas D. Effect of simulated pulpal microcirculation on intrapulpal temperature changes following application of heat on tooth surfaces. International Endodontic

Operative Dentistry, 2016

SUMMARY Recently, “budget” dental light-emitting diode (LED)–based light-curing units (LCUs) have... more SUMMARY Recently, “budget” dental light-emitting diode (LED)–based light-curing units (LCUs) have become available over the Internet. These LCUs claim equal features and performance compared to LCUs from major manufacturers, but at a lower cost. This study examined radiant power, spectral emission, beam irradiance profiles, effective emission ratios, and the ability of LCUs to provide sustained output values during the lifetime of a single, fully charged battery. Three examples of each budget LCU were purchased over the Internet (KY-L029A and KY-L036A, Foshan Keyuan Medical Equipment Co, and the Woodpecker LED.B, Guilin Woodpecker Medical Instrument Co). Major dental manufacturers provided three models: Elipar S10 and Paradigm (3M ESPE) and the Bluephase G2 (Ivoclar Vivadent). Radiant power emissions were measured using a laboratory-grade thermopile system, and the spectral emission was captured using a spectroradiometer system. Irradiance profiles at the tip end were measured using...

The International journal of prosthodontics, 2021

PURPOSE To evaluate the effect of tooth brushing and dentifrice fluoride (F-) concentration on ch... more PURPOSE To evaluate the effect of tooth brushing and dentifrice fluoride (F-) concentration on changes in color and translucency (ΔE00 and ΔT00, respectively), surface gloss (GS), surface roughness (Sa), and microstructure of a glazed CAD/CAM ceramic. MATERIALS AND METHODS Ceramic blocks (e.max/CAD) were sectioned into rectangular plates (14 x 12 x 1 mm), and one surface of each sample was glazed. Samples were divided into three groups according to the F- concentration in the dentifrice (0, 1,100, and 5,000 μg/g) and were then subjected to 60,000 tooth brushing cycles. Luminosity and color were measured using a spectrophotometer at baseline and after every 20,000 cycles to obtain their ΔE00 and ΔT00 values. Another set of samples was prepared to measure the GS with a gloss meter and the Sa with a confocal laser microscope. The GS and Sa results were subjected to analysis of variance, Tukey test, and Dunnett test (α = .05). RESULTS After 60,000 tooth brushing cycles, all of the varia...

Iranian Endodontic Journal, 2014

Introduction: The aim of this descriptive cross-sectional study was to assess the general dental ... more Introduction: The aim of this descriptive cross-sectional study was to assess the general dental practitioners (GDPs)’s knowledge regarding the emergency management of traumatic dental injuries (TDI) in Isfahan, Iran. Methods and Materials: In this study a two-part questionnaire consisting of 14 questions was distributed among 241 GDPs. Part 1 included seven questions focusing on personal and professional information and part 2 asked questions about seven given cases of dental traumas. One score was dedicated to each correct answer; the total score of 0 to 4 was considered as poor knowledge, while scores 5-8, 9-11 and 12-14 were assigned as moderate, good and excellent knowledge, respectively. The data were analyzed using the Student’s t-test and one-way ANOVA. Spearman’s and Pearson’s correlation coefficient were used to determine the associations between the emergency treatment knowledge and dentists’ professional information. Results: With regards to the level of GDP’s knowledge,...

Dental Materials, 2018

To evaluate how the light delivered to resin-composites was described in recent articles. Method:... more To evaluate how the light delivered to resin-composites was described in recent articles. Method: PubMed was searched for 300 articles published between January 2017 and May 2018 with keywords relating to photocuring of dental materials. The articles examined a wide range of resin-composite properties and performance. For each article, the information provided about the light curing unit (LCU), the light curing conditions and the characteristics and quantity of the light used in the study were recorded. Specifically, the type of LCU used; the irradiance; how the irradiance was measured; the exposure times; whether the light energy (radiant exposure) received by the specimen was determined, or if only the light output at the LCU tip was measured; whether the distance between the tip of the LCU and the specimen was reported; and whether the emission spectrum from the LCU was reported. Where possible, the resin manufacturer's minimum energy requirement (MER: the product of the recommended minimum exposure time and irradiance) was compared to the radiant exposure delivered to the specimen. Results: Of the 300 articles examined, 217 were published in 2017 and 83 in 2018. Of these articles, 130 (43%) were found in open access journals, and 170 (57%) were in subscription-based journals. The name of the LCU used was not provided in 31 articles, 14 articles did not provide the exposure time, and 227 articles did not report the distance to the specimen. An irradiance value was reported in 231 articles, but this was the irradiance received by the specimen in only 48 instances. The emission spectrum from the LCU was reported in 15 articles. There was a large range in the radiant exposures from below 10 J/cm 2 to greater than 100 J/cm 2 .

Operative dentistry

I do not remember a time during my dental career when direct resin restorations were not being di... more I do not remember a time during my dental career when direct resin restorations were not being disparaged by someone. Some of the expressed concerns have validity. Certainly the earlier composite resins offered little wear resistance or ability to predictably create a bonded interface. The chemical activation system used in early materials also limited the ability of a practitioner to form and sculpt restorations. I remember being taught that the placement of a composite resin restoration should include the same level of care and attention to detail provided to direct gold restorations. I have held the opinion that many of the problems associated with composite resin restorations can be attributed to approaching their placement in a way that mimics the approach taken when placing amalgam, a material that is much more forgiving of less-than-optimal handling. An important issue in the placement of lightactivated composite resin is the amount and type of light energy that is actually being received by the material. Inadequate light curing can easily result in compromised restorative material properties, compromises that likely have a negative influence on restoration longevity. It has been well documented that, worldwide, many offices have been using inadequate amounts of energy and less-thanoptimal technique and are delivering inadequate amounts of energy when light curing resins. 1-9 If that is the case, then it should be no surprise to anyone when reading reports about the substandard performance of posterior composite resin restorations. 10-13

British Dental Journal, 1996

The Journal of the American Dental Association

The perils of online purchasing ... ( https://authors.elsevier.com/a/1edif\_46QxGnd )

Operative Dentistry, 2018

SUMMARY Objectives: This study compared light transmission through different thicknesses of bulk-... more SUMMARY Objectives: This study compared light transmission through different thicknesses of bulk-fill resin-based composites (RBCs) using a polywave and a single-peak light-emitting diode light-curing unit (LCU). The effect on the surface hardness was also evaluated. Methods: Five bulk-fill RBCs were tested. Specimens (n=5) of 1-, 2-, 4-, or 6-mm thickness were photopolymerized for 10 seconds from the top using a polywave (Bluephase Style) or single–peak (Elipar S10) LCU, while a spectrophotometer monitored in real time the transmitted irradiance and radiant exposure reaching the bottom of the specimen. After 24 hours of storage in distilled water at 37°C, the Vickers microhardness (VH) was measured at top and bottom. Results were analyzed using multiple-way analysis of variance, Tukey post hoc tests, and multivariate analysis (α=0.05). Results: The choice of LCU had no significant effect on the total amount of light transmitted through the five bulk-fill RBCs at each thickness. The...

Bioorganic & Medicinal Chemistry Letters, 2000

ÐA series of monocyclic and bicyclic amino acids have been synthesised and incorporated into thro... more ÐA series of monocyclic and bicyclic amino acids have been synthesised and incorporated into thrombin inhibitors based on CGH728, an analogue of the Mitsubishi compound MD805. Benzthiazolylalanine (Bta) was found to be a good non-polar substitute for arginine at the P1 position, yielding compounds with low nanomolar potency and good selectivity for thrombin.

The journal of adhesive dentistry, 2018

The use of resin-based composites, both clinically and for laboratory studies, continues to incre... more The use of resin-based composites, both clinically and for laboratory studies, continues to increase. As is well known, the quantity (radiant exposure in J/cm2) and characteristics (wavelength in mW/nm and beam profile) of light delivered to a photocured resin will have a significant impact on its polymerization. The nature of light emitting diodes (LEDs) means that, unlike halogen (QTH) light sources, they can only produce a narrow emission spectrum. Thus, not all LED light-curing units (LCUs) deliver the same wavelengths of light and, in order to produce a broad spectrum of light, LED LCUs must contain multiple LEDs. Depending on the optical design of the LCU, both the emission spectrum and the radiant emittance may be non-uniformly distributed across the light tip of the LCU. Furthermore, the irradiance and the beam profile of the light received by the resin will change as the distance from the light tip to the composite surface increases. If we wish for research that requires th...

STOMATOLOGY EDU JOURNAL, 2018

Fifty years ago, for the most part, all the dentist had to know about direct restorative material... more Fifty years ago, for the most part, all the dentist had to know about direct restorative materials was how to use dental amalgam and silicate cement. The preparation design for amalgams was well understood, and mechanical retention was a fundamental requirement. Reliable adhesion to both dentin and enamel was utopian, metal free ceramics were not durable, and light-cured resins had yet to be developed. Today, we have a multitude of materials and techniques that enable the dentist to produce direct and indirect restorations that are practically undetectable for both the dentist and the patient. However, there are tremendous consequences from having so many restorative materials and techniques available, and it has become more and more difficult for both practitioners and university professors to find their way through what is now considered a restorative jungle. On the one side, the internet offers in milliseconds a vast amount of information, which often sounds interesting and authoritative but, unfortunately, it is not always correct. Most dental schools claim to teach evidence-based dentistry and focus on providing treatment recommendations that are free from bias and based on prospective randomized double-blinded clinical trials. This approach should ascertain the truth, but has some severe disadvantages. Firstly, it requires a long time for valid results to be produced; secondly, patients cannot be standardized; thirdly, there is often an element of bias in that the exclusion criteria for the very studies that we rely on often eliminate some significant parts of populations that are candidates for the treatment being evaluated. Finally, ethical considerations often limit the questions that can be asked from a prospective randomized, double-blinded clinical trial. This is further compounded by the fact that it has been estimated that more than 95% of recent prosthodontic and implant review articles failed to use search strategies that were systematic, thus undermining the conclusions upon which treatment decisions are based [1]. One solution to the problems described above is a consensus conference. The principle is the following: experts, key opinion leaders, who represent the profession and industry come prepared to discuss a well-defined topic. Based on all their combined scientific, clinical and epidemiologic knowledge, together with presentations, a structured discussion occurs, in which proven, accepted information is sorted out from less valid information. In essence, this is now peer review by some 50 key opinion leaders instead of peer review by 2 or 3 selected reviewers for a 'peer reviewed' journal publication. At the end of such a conference, a draft consensus paper is formulated, which is subsequently reviewed, edited and approved by those key opinion leaders. The Northern Light conferences at Dalhousie University in Halifax (Canada) have produced such recommendations for the light curing of direct restorations (2014) [2-4], dental light-curing units (2015) [5], bulk-fill restorations (2016)