R.J.M. Lynch

Goddard Space Flight Center

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Frank Lippert

Indiana University – Purdue University Indianapolis

Anderson T. Hara

Indiana University Health

Domenick T. Zero

Indiana University – Purdue University Indianapolis

Andrew Butler

University of New Hampshire

Steven Neshyba

University of Puget Sound

P. J. Parbrook

University College Cork

Ullas Mony

Saveetha University

Robert R. Gamache

University of Massachusetts Lowell

David Churchley

GlaxoSmithKline (United Kingdom)

Lívia Maria Andaló Tenuta

University of Michigan–Ann Arbor

Cooperative Institutions

Space Telescope Science Institute

455

Goddard Space Flight Center

304

Northrop Grumman (United States)

136

Johns Hopkins University

University of Arizona

Michigan Science Center

Centre National de la Recherche Scientifique

European Space Agency

European Space Research and Technology Centre

Max Planck Institute for Astronomy

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Effect of Fluoride, Lesion Baseline Severity and Mineral Distribution on Lesion Progression

Caries Research (2012)

Frank Lippert Andrew Butler R.J.M. Lynch Anderson T. Hara

The present study investigated the effects of fluoride (F) concentration, lesion baseline severity (ΔZ(base)) and mineral distribution on lesion progression. Artificial caries lesions were created using three protocols [methylcellulose acid gel (MeC), hydroxyethylcellulose acid gel (HEC), carboxymethylcellulose acid solution (CMC)] and with low and high ΔZ(base) groups by varying demineralization times within protocols. Subsequently, lesions were immersed in a demineralizing solution for 24 h in the presence of 0, 1, 2 or 5 ppm F. Changes in mineral distribution characteristics of caries lesions were studied using transverse microradiography. At baseline, the protocols yielded lesions with three distinctly different mineral distributions. Secondary demineralization revealed differences in F response between and within lesion types. In general, lowΔZ lesions were more responsive to F than highΔZ lesions. LowΔZ MeC lesions showed the greatest range of response among all lesions, whereas highΔZ HEC lesions were almost unaffected by F. Laminations were observed in the presence of F in all but highΔZ HEC and CMC lesions. Changes in mineral distribution effected by F were most pronounced in MeC lesions, with remineralization/mineral redeposition in the original lesion body at the expense of sound enamel beyond the original lesion in a dose-response manner. Both ΔZ(base) and lesion mineral distribution directly impact the F response and the extent of secondary demineralization of caries lesions. Further studies - in situ and on natural white spot lesions - are required to better mimic in vivo caries under laboratory conditions.

Carious lesion

Tooth Remineralization

10.1159/000334787

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Citations (29)

Laboratory assessment of the anticaries potential of a new dentifrice.

PubMed (2009)

Frank Lippert Evelyn Newby R.J.M. Lynch Vijeash K. Chauhan B.R. Schemehorn

The aim of the present study was to investigate the anticaries potential of a new sodium fluoride dentifrice in comparison to two commercial dentifrices containing different fluoride compounds by determining enamel fluoride uptake (EFU) and early caries lesion remineralization (REM) in an established in vitro caries remineralization/demineralization pH cycling model.Test products were: new dentifrice formulation in a fluoride dose-response (0; 675; 1426 ppm F as sodium fluoride [NaF-0; NaF-675; NaF]); Elmex Kariesschutz (1400 ppm F as amine fluoride [AmF]); and Oral-B Pro-Expert (1450 ppm F-1100 ppm F as stannous fluoride and 350 ppm F as sodium fluoride [SnNaF]). Artificial caries-like lesions were formed in human enamel specimens by immersion in lactic acid buffer (LA). Specimens were then subjected to a daily cycling regime for 20 days comprising four one-minute dentifrice slurry treatments (prepared in pooled human saliva), and one four-hour LA challenge and remineralization in pooled human saliva. After 20 days, REM was evaluated as the change in surface Vickers microhardness from lesion baseline and EFU using the microdrill technique. The data were analyzed using ANOVA.A good fluoride dose-response was established for EFU and REM, with NaF delivering greater EFU and REM than NaF-675, which was superior to NaF-0 (p < 0.05). The new dentifrice NaF also showed greater EFU and REM than AmF and SnNaF (p < 0.05). In EFU, AmF and SnNaF were as efficacious as NaF-675 and superior to NaF-0 (p < 0.05). AmF and NaF-675 were also comparable in REM, whereas both products exhibited superior REM vs. SnNaF (p < 0.05), which was superior to NaF-0 (p < 0.05).The present study has demonstrated that fluoride dentifrices vary in their capability of enhancing anticaries potential as determined using an established in vitro caries cycling model. The new dentifrice NaF showed superior predicted anticaries potential compared to the two commercial dentifrices AmF and SnNaF in this model, which demonstrates the importance of fluoride compound and formulation excipients on driving anticaries potential in vitro.

Dentifrice

Sodium fluoride

Tooth Remineralization

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Citations (16)

The Effect of Lesion Characteristics at Baseline on Subsequent De- and Remineralisation Behaviour

Caries Research (2006)

R.J.M. Lynch J.M. ten Cate

The aim was to study the effect of lesion characteristics at baseline on subsequent de- and remineralisation behaviour. Artificial lesions used during in vitro and intra-oral studies exhibit an increasing tendency toward net remineralisation with increasing integrated mineral loss at baseline (DeltaZ(base)). Proposed explanations include: (i) small lesions may be more vulnerable to demineralisation, and (ii) large lesions may be more difficult to remineralise. To evaluate these hypotheses, subsurface lesions were created in numerous blocks of human and bovine enamel, with a range of depths and DeltaZ(base), measured by microradiography. One group of lesions was further demineralised, a second group remineralised, and subsequently, both groups re-analysed. Under demineralising conditions, there was a marked decrease in further mineral loss with increasing DeltaZ(base). Under remineralising conditions lesions gained mineral in proportion to DeltaZ(base). The decrease in demineralisation of lesions with larger DeltaZ(base) may be partially a result of decreased intrinsic solubility through modified chemical composition, e.g. loss of magnesium, carbonate etc. The results may explain the tendency toward net remineralisation with increasing DeltaZ(base) in pH-cycling regimes.

10.1159/000095653

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Citations (62)

LED pumped Nd:YAG laser development program

G. I. Farmer Y. C. Kiang R.J.M. Lynch

The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

Rod

Reflector (photography)

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Theoretical calculations of pressure broadening coefficients for H2O perturbed by Hydrogen or helium gas

Journal of Quantitative Spectroscopy and Radiative Transfer (1996)

Robert R. Gamache R.J.M. Lynch Linda R. Brown

Formalism (music)

Helium gas

10.1016/0022-4073(96)00098-2

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Citations (56)

The Effect of Fluoride at Plaque Fluid Concentrations on Enamel De- and Remineralisation at Low pH

Caries Research (2006)

R.J.M. Lynch Ullas Mony J.M. ten Cate

The aim was to study the effect of fluoride, at concentrations typical of plaque fluid, on de- and remineralisation of subsurface lesions at low pH. Artificial lesions in human enamel were microradiographed to quantify mineral loss and placed in acid-gel systems at pH 4.8, 5.0 and 5.2. Calcium and phosphate were added to give initial Ca and Pi concentrations of either 4.1 and 8.0 mM, or 4.7 and 9.7 mM, at each pH value. Further, at each pH and combination of Ca and Pi, fluoride was added to the gels to give initial concentrations of 1, 2 or 5 ppm, with a non-fluoride control group. The lesions were removed after 10 days and change in mineral content quantified. Those in the non-fluoride control groups had demineralised further. Those exposed to fluoride had remineralised, the amount increasing with increasing fluoride concentration, up to a maximum value of approximately 75%. Calcium activity in the gels was reduced significantly, to levels similar to those reported for plaque fluid at low pH. Fluoride activity was also reduced, though to a lesser extent. These findings contrast with those from studies which have simulated conditions on smooth surface sites and which used experimental solutions composed to reflect salivary fluoride concentrations, where net demineralisation was observed at low pH. This reflects the need for further study of de- and remineralisation under plaque-fluid conditions. In conclusion, subsurface lesions were remineralised at low pH by fluoride at concentrations found in plaque fluid during a cariogenic challenge.

Fluorite

10.1159/000095652

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Citations (45)

Remineralisation of enamel white spot lesions pre-treated with chitosan in the presence of salivary pellicle

Journal of Dentistry (2018)

Jing Zhang R.J.M. Lynch Timothy F. Watson Avijit Banerjee

Bioactive Glass

Knoop hardness test

Tooth Remineralization

Polyacrylic acid

10.1016/j.jdent.2018.02.004

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Citations (37)

Status of the JWST sunshield and spacecraft

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2016)

Jonathan W. Arenberg J. Flynn Andy Cohen R.J.M. Lynch J. Cooper

This paper reports on the development, manufacture and integration of the James Webb Space Telescope's sunshield and spacecraft. Both of these JWST elements have completed design and development testing. This paper will review basic architecture and roles of these systems. Also to be presented is the current state of manufacture, assembly integration and test. This paper will conclude with a look at the road ahead for each subsystem prior to integration with the integrated telescope and instrument elements at Northrop Grumman's Space Park facility in late 2017.

10.1117/12.2234481

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Citations (16)

Effect of Fluoride, Lesion Baseline Severity and Mineral Distribution on Lesion Progression

Frank Lippert Andrew Butler R.J.M. Lynch Anderson T. Hara

The present study investigated the effects of fluoride (F) concentration, lesion baseline severity (ΔZbase) and mineral distribution on lesion progression. Artificial caries lesions were cr

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Terahertz pulsed imaging study to assess remineralization of artificial caries lesions

Journal of Biomedical Optics (2011)

David Churchley R.J.M. Lynch Frank Lippert Jennifer Susan O’Bryan Eder Jesse Alton

We compare terahertz-pulsed imaging (TPI) with transverse microradiography (TMR) and microindentation to measure remineralization of artificial caries lesions. Lesions are formed in bovine enamel using a solution of 0.1 M lactic acid/0.2% Carbopol C907 and 50% saturated with hydroxyapatite adjusted to pH 5.0. The 20-day experimental protocol consists of four 1 min treatment periods with dentifrices containing 10, 675, 1385, and 2700 ppm fluoride, a 4-h/day acid challenge, and, for the remaining time, specimens are stored in a 50:50 pooled human/artificial saliva mixture. Each specimen is imaged at the focal point of the terahertz beam (data-point spacing = 50 μm). The time-domain data are used to calculate the refractive index volume percent profile throughout the lesion, and the differences in the integrated areas between the baseline and post-treatment profiles are used to calculate ΔΔZ((THz)). In addition, the change from baseline in both the lesion depth and the intensity of the reflected pulse from the air/enamel interface is determined. Statistically significant Pearson correlation coefficients are observed between TPI and TMR/microindentation (P < 0.05). We demonstrate that TPI has potential as a research tool for hard tissue imaging.

10.1117/1.3540277

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Citations (29)