8/13/2019 j.1749-6632.1968.tb20274.x

1/10

M A T E R I A L S IN R E S T O R A T IV E D E N T I S T R YFloyd A. Peyton

Universi ty of Michigan, School ofDentis tryAnn Ar b o r , M ich .T w o major a reas of practice are recognized in dentistry. On e is directed tow ardthe prevention of oral disease by the reduction of dental caries and the controlof periodontal dis turba nce s and or al lesions of all types in the mo uth , the patientthereby being assured of the best possible oral health services from such pre-ventive practice. The other area is the practice of restorative dentistry, whichincludes the treatment of localized infections and the preparation of restorationsto replace lost tissue. It is with regard to this second area that an understandingof materials is important.T h e con struc tion of d enta l restorations and the practice of restorative dentistryare a necessity while people c on tinue to suffer from involvements of the o ral tis-sues. When teeth and adjacent tissues are lost by accident or disease, the losttissues must be replaced by functionally and esthetically effective artificial sub-stitutes. A m ajo r portion-variously estimated at SO-70 -of de ntal service an dtime is devoted to these biomechanical p rocedures. Un fortu nate ly, this conditionis likely to continu e throughou t the present ge neration, or until research providesmethods to assure a reduction of prevailing dental disorders. One should recog-nize, therefore, that restorative dental practice is important to the patient, is anaccepted fact of the profession, depends on a knowledge and choice of avail-able materials, and will continue to be needed in the future as a part of ourdental health service.In restorative procedures, two major activities must be recognized as funda-mental: T he proper treatment, preservation and ca re of the remaining oral tis-sues, with an evaluation of tissue tolerance, compatibility or tissue reaction tothe various restorations; and the understanding of the fundamental nature, thephysical and mechanical properties, and the functional and esthetic performanceof the materials employed in the restoration. Dental materials science is con-cerned with all facets of these activities, and restorative dental practice involves

the attempt to replace with appropriate substitutes either hard or soft tissues ofthe mouth which has been lost through accident or disease.Research Benefits

During recent years, research on restorative materials has had a profoundeffe ct on all restorative de nta l practice. It is evident that research efforts will co n-tinue to result in further refinements, improvements and modifications in mate-rials, techniques an d Su ch advancement m ake s restorative prac ticemore satisfying and more productive, both to the patient and to the dentist. Inmaterials research, multidiscipline efforts are employed to solve existing prob-lems in r e s tora t ive den t i~ t ry .~tudies are under way to correlate the efforts ofthe physical, chemical, or engineering scientist with the basic biologist or clinicalinvestigator in order to achieve the greatest benefits for the practitioner and forthe health of the patient. The results of this trend in research practice are en-couraging, and the potential benefits are great.One actual benefit is the development of improved and refined materials andtechniques for restorative pra~tice,~,6n the f o rm of bette r physical properties,simplification of technical procedures, development and introduction of new

96

8/13/2019 j.1749-6632.1968.tb20274.x

2/10

Peyton: Materials in Restorative Dentistry 97materials and discovery of their specific applications in practice. A wide rangeof materials is necessary for current restorative practice, including metals andalloys, plastics, ceramics and various combinations of substance. For each typeof m aterial, it is necessary to evaluate the tissue reaction it will evoke, its physicaland mechanical characteristics and the influence of variation in manipulation, inorde r to estim ate its serviceability in practice.

Mouth Tissue Properties and ReactionsIncreased understanding of the nature and characteristics of hard and softmouth tissues and their reaction to restorations has resulted from studies duringrecent years. The physical and mechanical properties of tooth tissue have beendescribed in several studies, as well as the reaction of mouth tissues to various

restorative materials. Information of this type is funda m enta l for the preservationof the remaining oral tissue and the success of the restoration or prosthesis.Studies have dem onstrated that a significant difference in hardness and strengthexists between h um an de ntin and enamel. Fo r example, the average Kno op hard -ness value of enamel has been observed at 343 23, while that of den tin is only68 3.7 In com pression, th e pro po rtiona l limit of d entin is approximately 24,000psi while that of enamel is 51,200 psi, with an ultimate compressive strength of43,000 psi for dentin and 55,700 psi for hum an T h e elastic mod ulusof dentin is 2.65 X 10' psi and of enamel 12.2 X 10 psi. Information of thistype is vital in the design of tooth-supported restorations such as inlays, crownsand bridges. For example, in the construction of bridges it is good to know thatthe unfilled plastic materials are softer, weaker and more flexible than humandentin tooth tissue. Some of the cements have properties similar to dentin, andgold alloys in general a re stronger, harder and m ore rigid th an den tin, but all areso f t e r t ha n e na me l t i~ sue . ~used porcelain approaches the hardness value ofenamel more nearly than most other restorative materials. Other properties showsimilar relations.T h e therma l conductivity of tooth tissue has been studied an d repo rted, alongwith com paris ons with cem ents and amalgam fillings.10-12 nfo rm ation of this typeis helpful in providing proper thermal protection for the dental pulp and nervetissue when large metallic restorations are necessary.cal/sec/cm z/o C/ cm , which is a little less than the value of 2.23 X forenamel, 2.5 X 10-3 and 1.8 X 10-3 for zinc phosphate and silicate cementsrespectively. These nonmetallic materials can serve as thermal insulators undersilver amalgam having a thermal conductivity of 5.4 X o r 90 gold-10%copper alloy with a conductivity of approximately 0.29 cal/sec/cm2/o C/cm.More information is needed on the proper insulation protection required undermassive metal restorations, but it is known that a nonmetallic base gives somedegree of protection under such restorations.Studies are being reported for the first time which indicate the magnitude anddirection of stress concentration, as well as the amount of deformation in fixedbridges of conventional design when loaded by forces similar to those encoun-tered during m a~ ti ca ti 0 n . l ~ emovable partial denture restorations are beingsubjected to similar stress analysis. Studies are being initiated to determine thestress concentration developed in the supporting tooth and bone tissues, sinceinterest frequ ently lies in the preservation of th e rem ainin g body tissue, as wellas in th e design of the prosthesis that will keep stress concen tration to a m inimum.Th e m ethods of stress analysis being em ployed f or these studies include a combi-

The average thermal conductivity of dentin is reported to be 1.36 X

8/13/2019 j.1749-6632.1968.tb20274.x

3/10

98 Annals New York Academy of Sciencesnation of the engineering practices of using brittle lacquer coatings, electric straingages, and photoelastic analysis of models. Such studies may have the beneficialeffect of creating improved designs for, and better service from, partial denturerestorations.The reaction of the soft pulp or nerve tissue of the tooth to the acidity ofcements, the monomer of plastic fillings, the leakage around or through restora-tions, and the cutting operations on enamel and dentin are being studied exten-~ i v e l y . ~ ~ - l ~tudy is being directed toward adequate protection against such re-active agents, and toward the development of a restorative material that willform true adhesion to the tooth tissue. To date, no such material is available.The relative toxicity or tissue reaction to the many materials employed inrestorative dentistry is receiving increased attention. A committee composed ofrepresentatives of areas of dental practice, biologic sciences, and pharmaco ogyas well as of materials research and manufacture, are working through the DentalMaterials Group of the International Association for Dental Research, with theCouncil on Dental Research of the American Dental Association in an effort toestablish standardized methods for evaluating the compatibility of various typesof materials. Progress has been made in grouping dental materials into threebroad types and classes: (1) Those which contact parts of the body rather thanthe oral cavity during manipulation and fabrication; (2) those which contactmucous membranes and other soft tissues in service; and 3 ) those which con-tact the hard tooth tissues and may affect the vitality of the tooth tissue. Appro-priate standard tests are being developed to evaluate materials of these types.Where surgical implants are needed following oral surgery, the problems oftolerance, compatibility, toxic effects and functional strength are comparable tothose of orthopedic or other prostheses where bone or soft tissue replacementmaterials are employed. The cobalt base alloys, stainless steel and a variety ofplastic materials are employed for oral rehabilitation in cases where tissue hasbeen lost as a result of accident or disease. The prosthodontist must be familiarwith the materials available for maxillofacial restorations, obturators and simi arprostheses. The materials science is more advanced in conventional restorativematerials than in this highly specialized area of surgical implants, which requiresa great deal more research.

Metals and Al loys n DentistryThe variety of metals and the number of alloys used for dental restorationscontinue to increase. Not many years ago, only a few yellow gold alloys wereavailable for cast and wrought structures, whereas today, a large variety of yellowand white gold alloys covering a range of compositions and properties can beobtained. The casting alloys are grouped into four types, ranging from soft,ductile products that can be adapted and adjusted with simple hand instrumentsto hard, high-strength alloys, subject to controlled heat treatment to alter andmodify the properties, and suitable for casting to high precision.20 A comparablerange of properties is available in gold alloy wires, bars or other prefabricatedforms. The proportional limit of the cast alloys may be as high as 75,000 psiwith a tensile strength value in excess of 100,000 psi.21J2 Gold alloy wires canhave a proportional limit in excess of 100,000 psi with tensile strength valuesover 150,000 psi. Numerous basic studies on the fundamental metallurgicalnature of the gold alloy systems have been reported; much is known about theircrystal structure, and about the effect of composition and the influence of heattreatment on their properties.23-26During the past 25 years, the cobalt-chromium alloys have almost completely

8/13/2019 j.1749-6632.1968.tb20274.x

4/10

Peyton: Materials in Restorative Dentistryreplaced the go d alloys fo r precision-cast, removable, pa rtial den tur e restora-tions. Th e composition, characteristic properties a nd fun dam enta l natu re of theseden tal alloys a re now q uite well ~ n d e r s t o o d . ~ ~ - ~ ~he effects of fabric ation varia-bles and other factors related to casting operations have been studied and de-~ c r i b e d . ~ l - ~ ~asically, and insofar as they apply to the field of surgical implant,the cobalt-chromium alloys are similar to the cobalt-base alloys. Progress hasbeen made in the development of suitable m old materials for c astin g these high-melting alloys, and a shell-casting process was recently introduced which permitsthe formation of a completed casting within a period of one hour and which hasnum erous advantages over the m ore conventional casting methods. Perhap s m orethan 90 of all removable partial denture prostheses are produced from cobaltbase alloys. T he p rincipal differe nce between their p roperties and those of thegold alloys lies in the increased hardness and greater modulus of elasticity orrigidity of the cobalt alloys. Thi s added rigidity can have the effect of giving be tterstress distribution o n the remaining su ppo rting teeth.Go ld alloy wire was formerly employed fo r orthodon tic springs and a rch wires.Now, however, most orthodontic appliances are fabricated from stainless steelalloys. T h e 18-8 type austenitic stainless steel was po pu lar until recently, whe nthe 17-7 hardenable stainless steel was introduced for various application^.^^Because of the greater modulus of elasticity or rigidity, of the stainless steel incomparison to gold alloys, its resistance to tarnish or discoloration, and well-developed methods of fab ricatio n available, it seems certain that th e use of stain-less steel in orthodontic applications will continue to grow.Within recent years, a new group of alloys for cast restorations has becomeavailab e to the den tal profession. The se alloys are unique because they are sup-porting bases to which porcelain can be attached by fusion. A variety of alloysare available fo r this purpose, but most are alloys of gold with 8-10% platin um ,6 5 palladium and 0.2-0.5 of tin, iron, and indi~m.359~6ne alloy is basic-ally a combination of palladium, silver and ruthenium, and another is developedfro m a cob alt-chrom ium base m etal formulation. These alloys are app ropriatefor crown and bridge restorations; and in general, the properties of the specialalloys are a n im pro vem ent over conventional gold casting alloys intended fo r thesam e purpose. F o r this type restoration, it has been necessary to develop bo th aspecial alloy and m old m aterial, as well as to m odif y the porcelain t o be attache dto the metal frame. This has been accomplished to an extent such that lastingattachment of the porcelain to the metal is now possible. Greater problems existin the production of accurate castings from the high-melting alloys, and in thedevelopment of the positive esthetic potential of porcelain veneers, a charac-teristic problem with fused porcelain restorations.

Silver Am alga m RestorationsAfter more than 75 years of use, silver amalgam continues to be one of themost satisfactory restorative dental materials. Studies have described the basicnature of the silver-tin alloy which is combined with mercury to form amal-gam.38239 Other studies have described the reaction between mercury and thesilver a l l0 y .~ ~ ,* 1vailable evidence indicates that most variables of manipulationhave som e influence on the properties of the ama lgam mas^.^'-^^ In spite of th epoisonous nature of some mercury compounds, there is no clinical or experi-mental evidence to suggest that silver amalgam has any seriously toxic effect onmo st patients. T h e use of silver amalg am is unique to dentistry, since no other

branch of health science employs this type of material.

8/13/2019 j.1749-6632.1968.tb20274.x

5/10

100 Annals New York Academy of SciencesPlastics in Dentistry

Restorative procedure in dentistry has always been dependent on contempo-rary developments in related sciences and arts. In recent years, the introductionof synthetic plastics has greatly advanced the production of good fittings, andof functionally and esthetically satisfactory restorations and prostheses. Resinscan be extensively used in restorative dentistry as a result of the many hoursdevoted to their development, evaluation, and adaptation for specific problems.Most commercially available plastic prod ucts have been evaluated , som e adapted,and m any discarded as being im practical for dental applications.Plastics are used successfully in the formation of complete and partial pros-theses, plastic teeth, repair and reline materials, attractive veneers, and soft linersfor temporary relief of sore tissues.47 Direct tooth-filling applications, veneers,and crown forms have some specific indications, and maxillofacial prosthesesinvolving both intra- and extraoral replacement of hard or soft tissues requirespecial qualities in the resin. Protective m ou th guards, plastic cem ents, impressiontrays, o r inlay an d other pattern form s represent som e of the dental uses of resinplastic. Both silicone and polysulfide synthetic rubber materials serve satisfac-torily as elastic impression materials in dentistry. The range of desirable physicaland mechanical properties is as varied as the uses, extending from soft, flexiblematerials that polymerize while the patient waits, to harder, more rigid materialsthat can be used f o r bridges or other prostheses. No on e m aterial is equ ally satis-fac tory for all den tal applications.

omplete and Partial Denture ProsthesesFor the construction of dental prostheses, there exists a variety of acryliccopolymers, blended acrylic-vinyl plastics, and polystyrene plus a variety ofprocessing techniques. Recent studies have demonstrated that these materialscan be used t o produ ce acceptab le dentures if the ap propriate construction pro-cedure i s fo l lowed fa i th f~ l ly .48 ,~~he superiority of one technique or materialover ano ther has no t been established, tho ugh an individual quality of one m ate-rial or method of processing may be a limited imp rovem ent over another. Ser vic e

able, attractive prosthetic restorations with excellent dimensional relationshipsare readily constructed if proper technical procedures are followed. There isevidence that nylon is definitely cont raind icated as a dentu re m aterial because ofdifficulty in processing and ser~iceability.5~Re cen t research studies have sho w n tha t the wettability of poly- (methyl meth-ac ry late) can be increased by coa ting with s ilicon te t r a ~ h l o r i d e .~ ~h e w ettabilityof treated plastic was increased by 50-70 with saliva and water. Improvedcleanliness and n onad herence to chewing gum to den ture teeth was observed bypatients whose dentures had been coated.Artificial plastic teeth ar e both esthetically and f unc tiona lly serviceable. Inmany instances, they are to be preferred to porcelain teeth, but not in all appli-cations. The choice depends on the clinical diagnosis. A recent report indicatesth at plastic is used in th e ma nufa cture of approximately 30 of all artificial teethin the United States, while it is more widely used in other countries.47It frequently happens that a soft resilient liner attached to the hard acrylicbase gives added comfort to the patient.52 Such liners m ay be used fo r a sho rttime to prevent chronic soreness from dentures, or as adjuncts in tissue condi-tioning. Longer use may be indicated following irradiation therapy, or in thereparation of congenital or acquired oral defects. In all instances, the funda-mental principles of denture construction are to be observed, and soft liners are

8/13/2019 j.1749-6632.1968.tb20274.x

6/10

Peyton: Materials in Restorative Dentistry 101exists between th e tooth an d th e r e ~ t o r a t i o n . ~ ~ ~ ~ ~s a result, marginal penetra-neither considered perm anent in nature n or recom me nded for all patients by m ostprosthedontists.

Important qualities of these resilient materials include color stability, bondstrength, tear strength, permanent resiliency, and ease of finishing or polishing.The products available differ appreciably in many of their properties, and givesignificantly different clinical performances. M ost of th e pro duc ts are modified orplasticized acrylic resins, but one is a vinyl resin and two are silicones.53 Com-parative tests have shown o ne silicone material to be relatively s oft, with a d urom -eter hardness value of 24 which is retained after one month in water at mouthtem pera ture. On e pop ular acrylic material shows a hardness of 25 w hich increasesto 40 after one month, and another possesses an initial hardness of 52, whichincreases to 55 after standing. O ther qualities vary accordingly. A n unusual andunfavorable quality of the silicone liner is its ability to support yeast growthCu ndidu ulbicuns, fungu s colonies) in som e mouths.54 T he me ans of overcomingthis characteristic have not been discovered.Plastic Anterio r Fillings and Ve neers on Fixed Prosthesis

Some improvements have been made in recent years in restorative resins thatpolymerize at mouth temperature. New products have more color stability andmay develop better marginal adaptation than older products. These materialsare still best suited for protected restorations of the cervical or proximal typewhich are free from stress concentration during mastication, since all plasticsare readily deformed elastically if used in locations where large stresses areapplied. T h e plastic fillings are subject to leakage due to polymerization shrin kag eo r a coefficient of expansion different from tha t of the to oth tissue. The y d o notinhibit c aries activity as do silicate cements, a nd t o da te, there ha s been n o suc-cess in developing a plastic cement or filling material with anticariogenic prop-erties. Some investigators urge caution on the basis of possible pulp reaction toplastic fillings, and discourage their use in deep cavities.55A new type of plastic filling material has been introduced in recent monthswhich contains approximately 70 inorganic vitreous filler, with the remain-ing 30 an organic binder made up of blended acrylates and cross linkingagents.58 Like the others, this material does not adhere to tooth tissue. Becauseof the filler, it has reduced polymerization shrinkage and lower thermal expan-sion than unfilled plastics. W hile it sho ws som e promise, furth er imp rovem entsin the material are desirable.The desire for attractive veneers on crown and bridge restorations has pro-duced renewed interest in plastic facings and veneer~.5 ' -~~hey are less expen-sive to fabrica te and easier to replace th an restorations of porcelain fused to gold.Epoxy plastics and glass fiber-filled resins have been recommended in this con-text, but they offer no advantage over the heat-polymerized acrylics and vinyl-acrylic blended materials. While veneer restorations can be formed from any ofthe suggested plastics, presently the most color-stable and dimensionally satis-facto ry are th e acrylic an d vinyl-acrylic materials.

An terio r Filling MaterialsResearchers and practitioners are increasingly concerned by the fact that nofilling material or cem ent ad here s to th e too th tissue.eo*e'Th is condition has beenrecognized generally for at least 25 years; an d during the past five years, exten-sive studies have established tha t n o existing m aterial adh eres to tooth

Because of this lack of tr ue adhesion, a space or a crevice of varying dimensions

8/13/2019 j.1749-6632.1968.tb20274.x

7/10

102 Annals New York Academy of Sciencesexists between the tooth and the As a result, marginal penetra-tion m ay o ccur, which in tu rn m ay con tribute to recu rrent caries, pulpal responseand fracture of the restoration.

Several methods of stud y have bee n employed to dete rm ine the exte nt of leak-age tha t m ay O C C U ~ , ~ ~ ~ ~ ~ncluding studies of radioisotope penetration, leakagefrom applied air pressure, penetration of dyes around and under the fillings,bacterial penetration, and percolation of liquids. The degree and magnitude ofthe leakage differs to some extent with the choice of material and technique ofuse. I n view of the fac t tha t leakage und er restorations has been a perp etua l con -dition, it is a credit to the integrity and skill of clinicians in the past that theirrestorations of gold foil, am alg am , well-designed cast cro w ns , or inlays have givenservice for 20-30 or more years, indicating that well-placed restorations can beserviceable and satisfying.Studies related t o the development of a tru ly adhesive material f or too th tissueare underway and some progress is being made, although to this time, no com-pletely acceptable material is available. Such studies involve not only the prob-lems of surface chemical reactions, wetting and spreading of liquids, themechanism of adhesion, solubilities and related physicochemical problems, butalso the development of compatible cavity liners or filling materials and cementswith improved properties and surface qualities. If such studies continue and areencouraged, they may produce results of great potential significance. In themeantime, it is appropriate that effort be spent on becoming familiar with the

nature and quality of acceptable materials currently available. Many investi-gators and practitioners believe that fine restorative results may be achievedwith existing materials. Cem ent Base and Ca vity LinersIn recent years, interest has centered on the protection of the pulp by meansof the p roper c eme n t base a nd /or c av ity liner i n dee p a nd extensive c a v i t i e ~ . ~ ~Where indicated, zinc oxide-eugenol or calcium hydroxide pastes provide suit-able protection, sedation, or thermal insulation. They may reduce the acid pene-tration to the p ulp area an d possibly by neutralizing th e fre e acid, T h e presenceof a suitable varnish with the base gives added protection.

Product Quality ControlIn the development and refinement of restorative materials, investigators arebeing guided-and th e profession protected-by a n increasing nu m ber of A m eri-can D enta l A ssociation specification^.^^ These serve as a basis for quality co ntro lof products, a nd there is practical evidence to indicate that prod ucts which com -ply with ADA specifications will produce serviceable and acceptable restorations.Eighteen such standards are available and an additional ten are being prepared.The specifications available for gold alloys, cobalt-chrome alloys, amalgam,mercury, plastics, cements and other materials have done much to maintain thehigh quality of products available to the American dental practitioner. Evidenceindicates that techniques of processing more than choice of materials influencethe quality of many products.Though it is impossible to predict what further trends will develop or whatadditional refinements will take place in restorative materials, it is certain thatmany of the challenges of restorative practice will be met in the years ahead byfurther modifications and improvements of materials. The practitioner mayanticipate advances through research during the next ten years which will equalor surpass those of the past, and which hopefully will continue giving rise tomore efficient and more effective clinical practices.

8/13/2019 j.1749-6632.1968.tb20274.x

8/10

8/13/2019 j.1749-6632.1968.tb20274.x

9/10

104 Annals New York Academy of Sciences32. PEYTON, . A.33. DOOTZ, . R., R. G. CRAIG F. A. PEYTON.

1958. Cast chromium-cobalt alloys. Symposium on Dental Materials. nDental Clinics of North America, 759. W . B. Saunders Co., Philadelphia, Pa.1965. Influence of investments and dupli-cating procedures on the accuracy of partial denture castings. J. Prosthetic Dentistry15: 679.34. CRAIG, . G., H. J. SLESNICK F. A. PEYTON. 1965. Application of 17-7 precipitation-hardenable stainless steel in dentistry. J. Dental Res. 4 4: 587.35. RYGE,G. 1965. Current American research on porcelain-fused-to-metal restorations.Intern. Dent. J 15: 385.36. SHELL, S. J. P. NIELSEN. Study of the bond between gold alloys and por-celain. J. Dental Res. 41: 1424.37. SCHNELL, . J., G. MUMFORD R. W. PHILLIPS. 1963. An evaluation of phosphatebonded investments used with a high fusing gold alloy. J. Prosthetic Dentistry 13: 324.38. RYGE,G., J C. MOFFETT A. G. BARKOW. 1953. Microstructural observations andx-ray diffraction studies of silver-tin amalgams. J. Dental Res. 32: 152.

39. MURPHY, . J. 1926. The constitution of the alloys of silver and tin. J. Inst. Metals35: 107.40.MITCHELL,. A., I. C. SCHOONOVER,. DICKINSON J. C. VACHER.1955. Some factorsaffecting the dimensional stability of Ag-Sn (Cm-Zn) amalgams. J. Dental Res. 34: 273.41. RYGE,G., R. F. TELFORD C. W. FAIRHURST. 957. Strength and phase formation ofdental amalgam. J Dental Res. 36: 986.42. SCHOONOVER,. C., W. SOUDER J. R. BEALL. 1942. Excessive expansion of dentalamalgam. J. Am. Dental Assoc. 29: 1825.43. WARE,A. L. A. R. DOCKING.1955. The effect of manipulative variables on dentalamalgams. Australian Dental J 58: 283; 59: 167.44. PEYTON, . A. E. L. LIATUKAS. 961. Compressive strength of amalgam as influencedby different condensation forces. J. Prosthetic Dentistry 11: 934.45. TAYLOR, . O., W. T. SWEENEY, . B. MAHLER E. J. DINGER. 1949. The effects ofvariable factors on crushing strengths of dental amalgams. J. Dental Res. 28: 228.46. WILSON, . J. G. RYGE. 1963. Clinical study of dental amalgam. J. Am. Dental Assoc.66: 63.47. BRAUER,. M. 1966. Dental applications of polymers: A review. J. Am. Dental Assoc.

72: 1151.48. PEYTON,. A. D. H. ANTHONY.1963. Evaluation of dentures processed by differenttechniques. J. Prosthetic Dentistry 13: 269.49. WOELPEL,. B., G. C. PAFFENBARGERW. T. SWEENEY.1963. Some physical proper-ties of organic denture base materials. J. Am. Dental Assoc. 67: 489.50 GEORGE, . A.51. OBRIEN,W. J. G. RYGE. 1965. Wettability of poly- (methyl methacrylate) treated52. GONZALEZ,. B. W. R. LANEY. 1966. Resilient materials for denture prostheses. J.

1962.

1965. Notes and comments. Dental Abstracts. 10: 9 .with silicone tetrachloride. J. Prosthetic Dentistry 15: 304.

Prosthetic Dentistry 16: 438.53. EICK,J. D., R. G. CRAIG F.A. PEYTON. 1962. Properties of resilient denture liners insimulated mouth conditions. J. Prosthetic Dentistry 12: 1043.54 GIBBONS, . 1965. Clinical and bacteriological findings in patients wearing silastic 390soft liner. J. Michigan State Dental Assoc. 47: 64.55. MASSLER, . Biologic considerations in the selection and use of restorative mate-rials. n Dental Clinics of North America, 131. W. B. Saunders Co., Philadelphia, Pa.56. LANCELAND,. K., J. GUTTUSO, . R. JEROME K. LANGELAND.966. Histologic andclinical comparison of addent with silicate cements and cold-curing materials. J. Am

Dental Assoc. 72: 373.57. PEYTON, . A. R. G. CRAIG. 1963. Current evaluation of plastics in crown and bridgeprostheses. J. Prosthetic Dentistry 13: 743.58. KAFALIAS, . C., M. L. SWARTZ R. W. PHILLIPS. 1963. Physical properties of selecteddental resins, Part I. J. Prosthetic Dentistry 13: 1083.59. FITZROY,. C., M. L. SWARTZ R. W. PHILLIPS. 1963. Physical properties of selecteddental resins, Part 11. J. Prosthetic Dentistry 13: 1108.60. VOLKER,. F. 1962. Report of the committee on scientific investigation of the Americanacademy of restorative dentistry. J. Prosthetic Dentistry 12: 770.61. PHILLIPS, . W. 1963. Report of the committe on scientific investigations of the Ameri-can academy of restorative dentistry. J. Prosthetic Dentistry 13: 515.62. MYERS,C. L., G. RYGE J. F. GLENN. In vivo test for bonding strength. J DentalRes. 42: 907.

1965.

1963.

8/13/2019 j.1749-6632.1968.tb20274.x

10/10

Peyton: Materials in Restorative Dentistry 10563. P H n m s , R.W., . W. GILLMORE, M. L. SWARTZ S. I. SCHENKER.1961. Adaptation

of restorations in vivo as assessed by Ca. 5 J. Am. Dental Assoc. 62: 9.64. NELSON,. J. R. B. WOLCOTT G. C. PAFFENBARGER.952. Fluid exchange at themargins of dental restorations. J. Am. Dental Assoc. 44:288.65. PARRIS,. P. KAPSIMALIS.960. The effectof temperature change on the sealing prop-erties of temporary filling materials. Oral Surg. Oral Med. Oral Pathol. 13: 982.66. LYELLE,. D. BARBER M . MASSLER. Effects of saliva and sulfide solutions onthe marginal seal of amalgam restorations. J. Dental Res. 4 :375.67. FIASCONANO,. E. H. SHERMAN.1952. Sealing properties of acrylics.N.Y. tate Den-tal J. 18:198.68. PINTO,J. M. G. BIJONOCORE.963. Effect of bones and cavity liners on marginalleakage of filling materials. N.Y. State Dental J. 28: 199.69.MORTENSEN, D. M., N . E. BOUCHER G. RYGE. Method of testing for marginalleakage of dental restorations with bacteria. Abs. Gen. Meeting. Intern. Assoc. DentalRes. 33.

1962. Continued studies on thepermeability of cavity liners. J. Dental Res. 41:66.1959. Bio-assay of cavity liners under silicate cement fillingsin rat incisors. J. Dentistry Children 26: 335.

1964.

1963.

70. SWARTZ,M. L., R. W. PHDLLIPS N. CHAMBERLAIN.71. PAPPAS, . M. MASSLER.