Elements of Light-cured Epoxy-based Dental Polymer Systems

Abstract

The greatest problem with current dental composite systems is their polymerization shrinkage. Extensive work is being done by many investigators to alleviate this problem. Our approach has been to examine epoxy- and spiro-orthocarbonate (SOC)-based resins. The hypothesis to be tested in this study was that the cure characteristics of experimental visible-light-cured epoxy resin systems are governed by the types and concentrations of co-reactants and activators. Resin samples containing onium salt initiators and a thiozanthone sensitizer were successfully cured by means of either an experimental visible-light irradiation system or a commercially available dental lamp. Test resins consisted of di-epoxies alone or in combination, epoxy mixtures in combination with an SOC, or an epoxy in combination with a caprolactone-derived polyol. Significant findings were as follows: (a) Resins containing the SOC had longer cure times than their counterparts; (b) the optimum ratios of epoxy to polyol for most rapid cure were 50:50 or 60:40 under conditions tested; (c) resins containing TONE 305 polyol generally were faster to cure than those containing no polyol, or TONES 201 or 310; and (d) a resin mixture was found that had a cure time of 1 to 3 min when irradiated with a commercial dental lamp. Based on this exploratory study, it should be possible for clinically relevant cure times to be achieved for visible-light-cured epoxy-based resins by careful manipulation and optimization of key elements.

Keywords

epoxy copolymerization non-shrinking dental composites aliphatic epoxides and polyols cationically cured epoxy resin mixtures visible light photoinitiation.

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References

Byerley TJ , Eick JD , Chen GP , Chappelow CC , Millich F. (1992). Synthesis and polymerization of new expanding dental monomers. Dent Mater 8:345-350.

Chappell RP , Pinzino C. , Chappelow C. , Eick JD ( 1995). Density determination and dimensional change of a nonshrinkable polymer (abstract). J Dent Res 74 (Spec Iss):230.

Chappell R. , Glaros A. , Eick D. , Pinzino C. , Chappelow C. (1996). Density determination and volume change calculations for monomer to polymer (abstract). J Dent Res 75 (Spec Iss):235.

Crivello JV (1984). Cationic polymerization-iodonium and sulfonium salt photoinitiators. Adv Polym Sci 62:1.

Crivello JV , Lam Jhw (1976). New photoinitiators for cationic polymerization . J Polym Sci Symp No. 56:383-395.

Crivello JV , Lee JL (1989). Alkoxy-substituted diaryliodonium salt cationic photoinitiators. J Polym Sci Part A: Polymer Chem 27:3951-3968.

Crivello JV , Sasaki HJ (1992). Structure and reactivity relationships in the photoinitiated cationic polymerization of oxetane monomers. J Macromol Sci-Pure Appl Chem 30(A):189-206.

Eick JD , Byerley TJ , Chappell RP , Chen GR , Bowles CQ , Chappelow CC (1993). Properties of expanding SOC/ epoxy copolymers for dental use in dental composites. Dent Mater 9:123-127.

Endo T. , Bailey WJ (1975). Synthesis of monomers expanding on polymerization . Makromol Chem 176:2897.

10.

Kaisaki DA , Mitra SB , Schultz WJ , Devoe RJ (1995). Visible light-curable epoxy system with enhanced depth of cure. Intl Patent Application No. 9613538 A2 960509.

11.

Kuskova VF , Lappo VG , Kondaurov VN (1972). Effect of epoxide filling materials on immunological reactivity of the organism (experimental study). Stomatologiya 51(5):68-70.

12.

Lappo VG , Kondaurov VN (1971). Toxicity of polymers proposed as filling materials . Stomatologiya 50(5):29-31.

13.

Millich F. , Eick JD , Chen GP , Byerley TJ , Hellmuth EW (1993). Determination of density changes with expansion polymerization. J Polym Sci Part B: Polym Physics 31:729-733.

14.

Parkhova RL (1973). Toxicity of dental filing material composed of epoxy resins. Ter Stomatol 8:42-43.

15.

Piggott MR , Woo MS (1986). Fiber composites with internal-stresses under control. Polymer Composites 7:182-185.

16.

Sadhir RK , Luck RM , editors (1992). Expanding monomers: synthesis, characterization and applications. Boca Raton, FL: CRC Press (contains historical review).

17.

Spur OK ( 1986). Blends of polycaprolactone polyols and polyepoxides. Eur Patent Application No. 198498 A2 861022.

18.

Takata T. , Endo T. ( 1992). Ionic polymerization of oxygen-containing bicyclic, spirocyclic, and related expandable monomers. In: Expanding monomers: synthesis, characterization, and applications. Sadhir RK , Luck RM , editors. Boca Raton, FL: CRC Press, pp. 130-134.

19.

Wictorin L. , Larson A. (1995). Photopolymerizable composition for use as dental filling material. Int Patent Application No. 9530402 A1 95116.

20.

Wu S. , Soucek MD (1997). Novel reactive diluents for cationic UV coatings . Polym Mater Sci Eng 76:64-65.