A S S O C I A T I O N R E P O R T S

Dental chairs

Acceptable

Elegan, JSA, JSR, SPD-5, VSA & VSR, Syntex Dental Products

Dental porcelains and ceram ics

Provisionally Acceptable

Dicor, Dentsply International

Dental X-ray equipment

Acceptable

Healthco Lumix III, Healthco Co

Endosseous implants

Provisionally Acceptable

Biotes, Bofors Nobelpharma

Nitrous oxide/oxygen scavenging equipment

Acceptable

Porter/Brown Clean-Air Scavenging Equipment, Por­ter Instrum ent Co

Powered oral hygiene devices

Provisionally Acceptable

Interplak, Dental Research Corp

Recogn ition program for products not currently

covered by a formal acceptance program or certifi­

cation program

Additions

Caridex 100, National Patent Dental Products, IncCentrays, Coopercare, IncCentwins, Coopercare, IncIdeal Sutures, Interstate Drug Exchange, IncLactona Toothbrushes & Stimulator, Lactona CorpSuper-Dent Sutures, Rugby Laboratories

T h e following p roducts have been rem oved from the list o f classified den ta l m aterials, in ­strum en ts, and equipm ent.

Crown and bridge and temporary crown and bridge

resins

Acceptable

SR-Isosit-PE, Degussa

Nitrous-oxide/oxygen scavenging equipment

Acceptable

Brown Mask, Summit Services Brown Scavenger, MDT Corp

--------------------JA B A --------------------This informational report was prepared by the

council in December 1985. Address requests for re­prints to the Council on Dental Materials, Instru­ments, and Equipment.

The effects of blue light on the retina and the use of protective filtering glasses

Council on Dental Materials, Instruments, and Equipment

D en ta l office p e rso n n el shou ld use pro tective filte ring devices, e ith e r eyeglasses o r eye shields, while curing

visible light-activated resins.1 O phthalm ic re ­search into the appearance o f blue light lesions has no t ru led ou t the possibility th a t short wavelength light (light with wavelengths o f less than 500 nm ) may contribute to the p rem atu re aging o f the retina and to senile m acular degen­era tion2 (the decreasing ability o f the m acular region o f the retina to provide visual acuity). N ear ultraviolet and blue lights also may cause the form ation o f cataract. M acular degenera­tion is a m ajor cause o f visual loss in o lder people in the U nited States.3 Also, reports indi­cate that light-induced retinal dam age can be hastened by increased exposure to visible light with wavelengths o f less than 500 nm. This ef­fect is photochem ical ra th e r than therm al o r s tru c tu ra l.4' 7 T h e m acular d e g en e ra tio n is a m o n g th e m ost active re se a rc h a rea s in ophthalm ology. Most o f the d a ta on light- induced re tinal dam age have been derived from studies o f animals and have not been con­firm ed in studies o f hum ans. A lthough no di­rect cause-and-effect re la tio n sh ip has been docum ented fo r dental visible light-curing unit use, the council recom m ends the use o f ap p ro ­priate, protective, filtering eyeglasses.1

T h e ocular m edia (composed o f the cornea,

aqueous media, crystalline lens, and vitreous hum or) passes light between 400 and 1,400 nm to the retina (the range o f the visual spectrum is approxim ately 400 to 700 nm ).8 As the lens ages, it acts as a natural absorber o f wavelengths o f betw een 320 and 400 nm .2 In addition, the lens provides partial protection to the retina from blue light. This protection increases with age, as the lens becomes m ore yellow. W hen the lens is rem oved after cataract surgery, this nat­u ra l filter is rem oved, causing exposure of ultraviolet and near blue lights to the retina. T h e fovea, o r the m acular region o f the retina, provides the eye with the m ost sensitive visual acuity. It is com posed alm ost entirely o f the color-sensitive cone cells o f the retina. It is this vital zone that may be subjected to p rem ature aging by increased exposure to ultraviolet and blue lights (up to wavelengths o f approxim ately 500 nm). Dental visible light-activated resin sys­tem s are polymerized by light in the 470-nm ra n g e . C u r r e n tly av a ilab le v is ib le lig h t- activating units generally transm it light begin­n ing a t approxim ately 370 nm and peaking at 470 nm . Some units continue to transm it light beyond 700 nm .9' 12 T h e specific range depends prim arily on the filters in the unit. It is the area o f less than 500 nm that is o f specific concern.

T h e use o f appropria te , protective eyeglasses when operating visible light-curing units is rec­

om m ended by the council1 and by the C enter fo r Devices and Radiological H ealth/Food and D ru g A dm in is tra tion .9 Protective eyeglasses sh o u ld f i lte r o u t m ost o f th e in ten sity o f wavelengths o f less than 500 nm.

T h e council’s laboratory recently m easured the transm ission characteristics o f 20 com m er­cially available p ro tective eyeglasses.13 T h e transm ission curves are shown in Figures 1 and2. As noted in the illustrations, considerable d ifferences exist am ong the glasses and, thus, the protection that they offer. Users o f visible light-curing units should be aware that p ro tec­tive eyeglasses should be selected carefully fo r adequate protection o f the eyes. As emission spectra o f various curing units d iffer (Fig 3), the possible protection offered by eyeglasses that transm it some irradiance at levels o f less than 500 nm would depend on a specific cu ring unit and the specific set o f protective eyeglasses. It is possible that com binations may exist that result in little o r no irradiance at levels o f less than 500 nm reach ing the eyes o f the user; fo r exam ­ple, w hen the transm ission region o f the eye­glasses at levels o f less than 500 nm corresponds to the no emission intensity in that region from the curing units. Fu rtherm ore , even if some irradiance o f less than 500 nm is transm itted th ro u g h the eyeglasses, the irradiance m ight have been reduced to a safe level by the eye-

JADA, Vol. 112, April 1986 ■ 533

Grey Sunglasses

Translux

0 7 0 0Wavelength (nm)

Fig 1 ,2 ■ Transmission curves o f 20 commercially available protective eyeglasses. Fig 3 distribution o f three visible light-curing units.

Spectral

5 0 0 6 0 0Wavelength (nm)

7 0 0

Figure 2

North Pacific G40

Figure 1

Guardian

Safety-Bond -

Healthco ------

M&R Improved Premier -----------

M&R-l Younger 540

Younger 550

Dioptics

Extra - Lite

Prisma

7 0 0

Figure 3

EUpar

6 0 0

Wavelength (nm)

glasses. T h is consideration , however, is com ­plex, is d ep en d en t on m any factors, and is d if­ficult to apply to general cases.9 Protective eye­glasses th a t transm it less than 1% below 500 nm would o ffe r less depen d en ce on the com bina­tion o f the curing u n it an d eyeglasses fo r gen­e ra l c o n sid e ra tio n . H ow ever, th e m inim al transm itted irrad iance values and the optim al protection still a re influenced by m atching ap ­p ro p ria te eyeglasses with the curing un it used.

T h e transm ission characteristics rep o rted are fo r p iano lenses w ithout prescrip tion m odifica­tions. T hese characteristics may be affected by variations in thicknesses o f the lenses and may be d ep en d en t on w hether the filtering effect is in surface coatings o r inheren tly in the m ate­rials o f th e lens bodies. In addition, the possibil­ity o f changes in transm ission characteristics with tim e o r a fte r exposure to light has no t been evaluated.

Summary

T h e council recom m ends the use o f ap p ro p ri­ate, protective, filtering eyeglasses. T h e eye­glasses should transm it less than 1% below 500 nm if the glasses are no t m atched with the cu r­in g u n it. A p p r o p r ia te ey eg lasses m ay be m atched with the cu rin g un it used.

------------------- J A D A ----------------------

This report was approved by the council in October 1985, and was prepared at the request o f the council by

John C. Mitchem, DMD, MS, professor, departm ent of dental materials, School o f Dentistry, Oregon Health Sciences University, Portland, OR; P. L. Fan, PhD, assistant secretary, Wayne T . Wozniak, PhD, assistant secretary; Sharon McGill, research assistant, Council on Dental Materials, Instrum ents, and Equipment, American Dental Association, Chicago; and John B. Moser, PhD, professor, departm ent of biological ma­terials, N orthw estern U niversity Dental School, Chicago. Address requests for reprints to the council.

1. Council on Dental Materials, Instruments, and Equipment. Visible light-cured composites and activat­ing units. JADA 110(1): 100-103, 1985.

2. Ham, W.T. Ocular hazards o f light sources: re­view o f current knowledge. J Occup Med 25(2): 101- 103, 1983.

3. Macular photocoagulation study group. Argon laser photocoagulation for senile macular degenera­tion. Results o f a random ized clinical trial. Arch Ophthalmol 100(6):912-918, 1982.

4. Sliney, D.H. Standards for use o f visible and nonvisible radiation on the eye. Am J Optom Physiol O pt 60(4):278-286, 1983.

5. Ham, W.T., and others. The nature o f retinal radiation damage: dependence on wavelength, power level and exposure time. Vision Res 20( 12): 1105-1111,1980.

6. Sliney, D.H. Biohazards o f ultraviolet, visible and infrared radiation. J Occup Med 25(3):203-206, 1983.

7. Ham, W.T.; Mueller, H.A.; and Sliney, D.H. Re­tinal sensitivity to damage from short wavelength light. Nature 206:153-155, 1976.

8. Ham, W.T., Jr.; Mueller, H.A.; and Ruffalo, J.J., Jr . Retinal effects o f blue light exposure. In Ocular effects o f non-ionizing radiation. Bellingham, WA, Society o f Photo-optical Instrumentation Engineers, 229:46-50, 1980.

9. Ellingson, O.; Landry, R.; and Bostrom, R. An

534 ■ JADA, Vol. 112, April 1986

A S S O C I A T I O N R E P O R T S

evaluation of optical radiation emissions from dental visible light photopolym erization devices. JADA 112(l):67-70, 1986.

10. Cook, W.D. Spectral distributions o f dental photopolymerization sources. J Dent Res 61(2): 1436- 1438, 1982.

11. Blankenau, R.J., and others. Wavelength and intensity of seven systems for visible light-curing com­posite resins: a comparison study. JADA 106(4):47l- 474, 1983.

12. O ’Brien, W.J., and others. T he application of blue polym er curing lights fo r diagnostic trans­

illumination. JADA 106(6):839-842, 1983.13. Fan, P.L., and others. Evaluation o f light trans­

mission characteristics of protective glasses for visible light curing units. J Dent Res 64 (Special Issue) 64:242, abstract no. 609, 1985.

Scientific consensus conference on methods for assessment of the cariogenic potential of food

A m erica n D en ta l A sso c ia tio n H ea lth F o u n d a tio n R esearch In stitu te

M ore than 150 dental research scien­tists m et in San A ntonio, T X , Nov 17-21, 1985, to de term ine w hether

scientific consensus exists regard ing m ethods used to assess the cariogenic potential o f foods.

Recognizing th a t a lthough m uch progress has been m ade in the reduction o f den ta l caries in children , ADA President A braham K obren, DDS, MS, highlighted the significant caries problem th a t still exists in adolescent adults. He challenged the conference a ttendees to a b e tte r un d erstan d in g o f the re lationship th a t exists betw een food and dental caries to continue the progress tow ard elim inating den tal decay as a national health problem .

Dominick DePaola, DDS, PhD, chairm an o f the p rogram com m ittee, viewed the conference ob jec tives as b e in g tw ofo ld : to d e te rm in e w hether scientific consensus exists on m ethods used to assess the cariogenic potential o f foods, and, in areas w here consensus does no t exist, to iden tify th e research a reas th a t need to be stressed to advance the field.

T h e first p a rt o f the m eeting was an open program with au thors invited to p resen t their p apers on the four m ethods used in targe ting the conference: hum an plaque acidity m odels; anim al caries m odels; de- and rem ineralization m odels; and an integration m odel—th at is, the use o f some com bination o f the p reced ing th ree m ethods. T hese resource papers and the sub­s e q u e n t o p e n d is c u s s io n p r o v id e d th e fram ew ork for fo u r working groups to m eet in closed sessions to p rep are position papers for p lenary open discussions to be held on the last day o f the conference.

In an in troductory p ap er on the complexities o f den tal caries, Brian A. B art, BDS, MPH, PhD, and Amid I. Ismail, BDS, MPH, reviewed the diet, nutrition , and food cariogenicity re la­tionships. T hey concluded, “T h e m ore we look at the whole question o f food cariogenicity, the m ore it shapes itself in term s o f total d ietary p a tte rn ra th e r than individual foods, and the dietary p a tte rn is ju st part o f the m ultifactorial etiology o f caries.”

A fter the in troductory rem arks, several re­ference papers were p resen ted on the various tes tin g m odels. T h e h u m an p laque acidity m odel fo r evaluation o f foods is based on the p roduction o f acid by plaque bacteria when it com es in to contact with a fe rm entab le sub­stance. Acid production , as estim ated by a fall in pH , is m onitored by one o f th ree m ethods: p laque sam pling, touch electrodes, o r inter- proxim al telem etry. In Switzerland, any food no t resulting in a plaque “critical” pH level o f 5.7 o r lower is considered safe fo r teeth. E xper­im entation to date has shown that no product

ju d g e d dentally safe fo r teeth by that criterion has been found to prom ote dental decay.

In the anim al caries m odel, a test food is o f­fe red to animals, usually rats, fo r a period. T h en , a caries score is d e term ined fo r com pari­son with scores from reference test foods o f known cariogenicity.

T h e use o f the de- and rem ineralization m odels involves th e p lacem en t o f slabs o f enam el into a food-saliva m ixture to de term ine w hether destruction o f the enam el surface will occur. A lthough the m ethods in the first two processes (plaque pH and anim al testing) were agreed to by the working groups, the exact na­tu re o f the de- and rem ineralization tests re­quires fu rth e r definition and research.

Need for indirect methods

T h e integration o f m ethods w orking group considered that although the true cariogenicity o f a food can be established only by experi­m entally determ in ing in hum ans the ex ten t to which tooth decay is associated with a given food, such experim ents are unfeasible and, th erefo re , indirect m ethods a re needed.

T h e plaque pH and anim al caries m ethods w ere reviewed as valid approaches to estim ate the cariogenic potential o f food. Foods could be ju d g e d as having no cariogenic po ten tial if when tested twice by the plaque pH m ethod, they prov ided decreases in pH statistically equivalent to o r less than those generated by

sorbitol.W hen a food was found to p roduce some

decrease in pH , however, it could be evaluated fu r th e r in the anim al caries m odel. W hen test­ing showed low caries activity as com pared with a ran g e o f reference foods, the food could be considered to have low cariogenic potential.

N ot all foods are adaptable to the p reced ing m ethods. For exam ple, rats canno t be taugh t to chew gum . In such instances, the developm ent o f o th e r m ethods m ust be aw aited . T h e w orking g roups recom m ended areas in which fu tu re re ­search should be done:

—T h e de- and rem ineralization m odels in tim e could em erge as valid and sim ple tests but fu r th e r refinem en t and testing in both in vivo and in vitro systems are necessary.

— Research should be continued to re fine the p laque pH m easurem ent m ethods so that they can be used m ore effectively to assess foods o f low cariogenic potential.

— B etter m ethods should be developed to test foods that are difficult to assess fo r cariogenic potential using existing m ethods.

— T o assist research an d developm en t on non- an d low-cariogenic foods, g rea te r em ­phasis should be placed on find ing sim ple yet reliable m ethods fo r screening foods with re ­spect to cariogenic characteristics.----------------------- J f tD A -------------------------

T he proceedings of the conference will be published in the Journa l o f Dental Research. Financial support for the conference was provided by food ingredient suppliers including Roquette, Imperial Chemical In­dustries, Monsanto, Stauffer, Xyrofin, Purac, and the Nutrasweet Group o f G. D. Searle. Sponsoring food manufacturers included Nabisco, Continental Baking, Gerber, Procter 8c Gamble, Kraft, W arner Lambert, Hershey, and Mead Johnson. Also providing support were International Life Sciences Institute, Block Drug, the Chocolate Manufacturers Association, Sugar As­sociation, and National Confectioners Association, and the National Institute of Dental Research.

This report was prepared in December 1985. Ad­dress requests for reprints to the ADA Health Founda­tion Research Institute.

JADA, Vol. 112, April 1986 ■ 535