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COSMETIC & RESTORATIVE CAREAn alternative method to reduce polymerization shrinkage in direct posterior composite restorations
SIMONE DELIPERI, D.D.S.; DAVID N. BARDWELL, D.M.D., M.S.
Spreafico RC, Gagliani M. Composite resin restorations on posterior teeth. InAdhesion
The silent revolution in dentistry. Chicago: Quintessence; 2000:253-76.
Yoshikawa T, Sano H, Burrow MF, Tagami J, Pashley DH. Effects of dentin depth and cavity configuration on bond strength.
J Dent Res 1999;78:898-905.
In three decades ago resine-based composite was…..
• Wear resistance• Micro leakage• Secondary caries• Lack of appropriate proximal
contact
In the past 10 years… dramatic improvement in newer-generation bonding agents and resin-based composite
formulations
• Significantly improved wear resistance• good proximal contact and contour• P olymerization shrinkage remains the bi
ggest challenge
Polymerization shrinkage • Def:
– formation of a gap between resin-based composite and the cavity wall
– 縮合體積量= 1.67 to 5.68 percent of the total volume
• Effect:– postoperative sensitivity and recurrent carie
s– bonding failure
Stress from polymerization shrinkage is influenc
by
• restorative technique• modulus of resin elasticity• polymerization rate• Cavity configuration or “C-factor.”
C-factor • = bonded / unbonded
surfaces• an increase in this r
atio results in increased polymerization stress
-Three-dimensional cavity preparations (Class I) have the highest (most unfavorable)
To minimize the stress from polymerization shrinkage
(I)improving placement techniques(II)improving material and composite for
mulation(III) improving curing methods
Placement techniques and issues.
• The incremental technique• Direct shrinkage• Bulk technique
(I)The incremental technique
• polymerizing with resin-based composite layers less than 2-millimeters thick
• achieve good marginal quality• prevent distortion of the cavity wall• ensure complete polymerization of
the resin-based composite
• Horizontal technique– occlusogingival layering – generally used for small restorations– increases the C-factor.
• Three-site technique– clear matrix and reflective wedges– guide the polymerization vectors
toward the gingival margin.
• Oblique technique– wedge-shaped composite increments – prevent distortion of cavity walls and reduce
the C-factor– polymerization first through the cavity walls
and then from the occlusal surface– direct vectors of polymerization toward the
adhesive surface (indirect polymerization technique)
• Successive cusp buildup technique– the first composite increment is
applied to a single dentin surface without contacting the opposing cavity walls
– And then wedge-shaped composite increments
– Each cusp then is built up separately– to minimize the C-factor in 3-D cavity
preparations
Figure 1. Schematic representation of wedge-shaped composite increments (1-6) used to build up the enamel proximal surface. F: Facial aspect. L: Lingual aspect.
Figure 2. Schematic representation of the flowable composite increment (1) and wedge-shaped increments (2-7) used to build up dentin;two increments (8 and 9) are used to build up enamel using the successive cusp buildup technique. F: Facial aspect. L: Lingual aspect.
Resin-based composite materials &
Dentin-enamel adhesive systems
(II)Resin-based composite materials
• By experimenting with particle size, shape and volume, manufacturers have introduced resin-based composites with differing physical and handling properties
– microfill,– hybrid– microhybrid– packable – flow-able
RESIN-BASED COMPOSITE CLASSIFICATION AND PHYSICAL PRPERTIES.
COMPOSITE TYPE
AVERAGE PARTICLE SIZE
(MICROMETERS =um)
FILLER PERCENTAGE(VOLUME %)
PHYSICAL PROPERTIES
Wear Resistance抗磨性
Fracture Toughness斷裂韌性
Polishability磨光性
Microfill 0.04-0.01 35-50 E F E
Hybrid 1-3 70-77 F-G+ E G
Microhybrid 0.4-0.8 56-66 E E G
Packable 0.7-20 48-65 P-G+ P-E+ P
Flowable 0.04-1 44-54 P P F-G+
E: Excellent G: good F: fair P:poor+ Varying among the same type of resin-based composite
TABLE 1
CLINICAL INDICATIONS OF RESIN-BASED COMPOSITES.
COMPOSITE TYPE CLINICAL INDICATIONS
Microfill Enamel replacement in Class III, IV and V restorationsMinimal correction of tooth form and localizeddiscoloration
Hybrid Posterior resin-based composite restorationClass V restorationDentin build-up in Class III and IV restoration
Microhybrid Posterior and anterior direct composite restorationVeneerCorrection of tooth form and discoloration
Packable Posterior resin-based composite restoration
Flowable Pit and fissure restorationLiner in Class I, II and V restoration (dentin)
TABLE 2
(II’)Dentin-enamel adhesive system
• Contemporary DAS(dentin-enamel adhesive systems) – around 22 Mpa– early bond strength to dentin ranged from 1 to 10
megapascals
……………..
(III)Curing methods
soft-start” polymerization
• “soft-start” polymerization (Miyazaki et al.)
– composite exhibited improved physical properties when cured at a low intensity and with slow polymerization vs. higher intensity and faster polymerization
• initially uses low-intensity curing – for a short period to provide sufficient
network formation on the top composite surface
• delaying – until the gel point
• final high-intensity polymerization
• highly mineralized tissue (Enamel) – resulting in a lower flexibility and decreased ability in relief
of shrinkage stress
• high–C-factor restorations • high-modulus composites
– transmit more polymerization shrinkage forces to the tooth
RECOMMENDED PHOTOCURING INTENSITIES AND TIMES FOR ENAMEL AND DENTIN BUILDUP.
BUILDUP LOCATION
COMPOSITE SHADE (PRODUCT NAME)
POLYMERIZATION TECHNIQUE
INTENSITY MW/CM2†)‡
INTENSITY MW/CM2†)‡
Proximal Enamel
Pearl Smoke Pearl Neutral/Pearl Frost (Vitalescence)
Pulse 200 (300) 3 (40)
Dentin A2 (flowable, PermaFlo) A3.5-A3-A2-A1 (Vitalescence)
Progressive curing
(300) (40)
Occlusal Enamel
Pearl Smoke/Pearl Neutral/Pearl Frost Trans Smoke/Trans Mist/Trans Frost (Vitalescence)
Pulse 200 (600) 3 (10 occlusal], 10 [facial], 10 [palatal])
•Vitalescence and PermaFlo are manufactured by Ultradent Products Inc., South Jordan, Utah.• † mW/cm2: Milliwatts per square centimeter.‡ Intensity at first polymerization (intensity after waiting period).§ Photocuring time at first polymerization (time after waiting period).
TABLE 3
Clinical Case
Figure 3. Preoperative occlusal view of tooth no. 3.
Figure 4. Tooth no. 3 after a rubber dam was placed, caries was removed and the cavity preparation was completed with a gingival butt joint and no bevel either on the axial or occlusal surface
Figure 5. A matrix was placed to protect adjacent tooth structure during cavity preparation and etching. Then etching was performed using 35 percent phosphoric acid.
Figure 6. Enamel’s and dentin’s glossy appearances after application of a fifth-generation, 40 percent filled ethanol-based adhesive system.
Figure 7. A sectional matrix, plastic wedge and G-ring placed to reconstruct the proximal surface.
Figure 8. Tooth no. 3 after the enamel proximal surface was built up using the Pearl Neutral enamel shade of the microhybrid composite (Vitalescence, Ultradent Products Inc., South Jordan, Utah).
Figure 9. Tooth no. 3 after the sectional matrix, plastic wedge and G-ring were removed and the A2 shade of the flowable composite (PermaFlo, Ultradent Products Inc., South Jordan, Utah) was applied to a single dentin surface.
Figure 10. A and B. Tooth no. 3 after wedge-shaped composite increments of A3. 5, A3 and A2 shades of the microhybrid composite (PermaFlo, Ultradent Products Inc., South Jordan, Utah) were used to reconstruct dentin
Figure 11. Tooth no. 3 after Pearl Neutral enamel shade of the microhybrid composite (Vitalescence, Ultradent Products Inc., South Jordan, Utah) was used to build up the occlusal surface according to the successive cusp buildup technique.
Figure 12. Postoperative occlusal view of tooth no. 3.
1 2
3 4
5 6
7 8
Before After
To minimize the stress from polymerization shrinkage
• improving placement techniques– placing successive layers of
wedge-shaped composite(1- to 1.5-mm) to decrease the C-factor
To minimize the stress from polymerization shrinkage
• improving material and composite formulation– select different composite materials t
o restore dentin (flowables and microhybrids) and enamel (microhybrids)
To minimize the stress from polymerization shrinkage
• curing methods– “soft-start” polymerization
EXPERIMENTAL ARTICLE REVIEW
The suitability of packable resin-based composites for posterior restorations
• Modulus of elasticity• Vickers hardness• Depth of cure
– Scraping– Producing a hardness profile
RESTORATIVE MATERIALS INVESTIGATED.MATERIAL CATEGORY
BRAND NAME
SHADE
FILLER VOLUME (%)
FILLER WEIGHT (%)
AVERAGE FILLER SIZE (µm)†
MANUFACTURER
Packable Resin-Based Composite
Solitaire
A20 90 66 2.0 - 20 Heraeus Kulzer, Wehrheim, Germany
Definite A2 61 77 1.0 Degussa AG, Hanau, Germany
SureFil A2 66 82 0.8 Dentsply De Trey, Konstanz, Germany
Alert A2 70 84 0.7 (glass fibers: 60 -
80)
Jeneric/Pentron, Wallingford, Conn.
Hybrid Composite
Tetric Ceram
A2 60 78 0.7 Ivoclar Vivadent, Schaan, Liechtenstein
Ion-Releasing Composite
Ariston pHc
universal 59 79 1.3 (alkaline
glass: 1.6)
Ivoclar Vivadent, Schaan, Liechtenstein
* Based on information from individual manufacturers.+ micrometer.
TABLE 1
MEAN VALUES AND STANDARD DEVIATIONS.COMPOSITE MATERIAL†
ELASTIC MODULUS (GPa)‡
VICKERS HARDNESS (HV§ 0.2/40)
CURING DEPTH (mm*)
By Producing Hardness Profile
By Scraping
Solitaire 4.4 (0.3)a 41.7 (3.5)a 3.0 (0.2)c,d 2.6 (0.2)a,b
Definite 6.3 (0.9)b 65.8 (1.6)c 2.5 (0.0)a,b 2.6 (0.3)a,b
SureFil 9.3 (0.9)c 70.4 (9.0)c,d 2.7 (0.3)b,c 2.8 (0.3)b
Alert 12.5 (2.1)d 75.2 (10.9)d 3.5 (0.6)e 3.5 (0.4)c
Tetric Ceram 6.8 (0.5)b 54.8 (1.1)b 3.2 (0.3)d,e 2.9 (0.2)b
Ariston pHc 7.3 (0.8)b 66.5 (2.6)c 2.2 (0.3)a 2.3 (0.3)a
*Superscript letters indicate statistically homogeneous subsets (Tukey test, = .05).†Manufacturers are as follows: Solitaire, Heraeus Kulzer, Wehrheim, Germany; Definite, Degussa AG, Hanau, Germany; Surefil, Dentsply De Trey, Konstanz, Germany; Alert, Jeneric/Pentron; Tetric Ceram and Ariston pHc, Ivoclar Vivadent, Schaan, Liechtenstein.‡GPa: Gigapascal.§HV: Vickers hardness.**mm: Millimeters.
TABLE 2
Figure. Determination of curing depth of the tested materials by scraping vs. producing a hardness profile (r2 = 0.9945). mm: Millimeters. Manufacturers are as follows: Ariston pHc and Tetric Ceram, Ivoclar Vivadent, Schaan, Liechtenstein; Definite, Degussa AG, Hanau, Germany; Solitaire, Heraeus Kulzer, Wehrheim, Germany; SureFil, Dentsply De Trey, Konstanz, Germany; Alert, Jeneric/Pentron.
CONCLUSIONS
• Packable composites that are promoted for the restoration of stress-bearing posterior carious lesions are quite different in their mechanical and physical properties