. 2019 Jan 17;2019:6190610. doi: 10.1155/2019/6190610

Table 1.

TiO₂NP applications in denture base and its effect on the tested properties.

Authors /year	Particle size	Addition percentage	Type of Acrylic	Nanocomposite preparation	Properties tested	Specimen size	Effects (Increase/Decrease/Unchanged)
Chatterjee, 2010 [9]	5 nm	0%-15wt%	PMMA from Scientific Polymer Products (Ontario, NY)	(i) Measured TiO₂NP mixed with PMMA for 5-10 min (ii) DACA twin-screw extraction process at 190°C and 100 rpm. (iii) Acrylic mixed for 6-7 min and extruded 5 times	(i) Tensile modulus (ii) Dimensional stability (iii) Glass transition temperature (T_g) (iv) UV absorption	10 x 6 x 0.3 mm 5 mg	(i) Improvement in tensile modulus. (ii) Increased thermal stability (iii) Increased T_g (iv) Improvement in UV absorption ⟶maximum at 2% TiO₂NP

Chatterjee, 2010 [10]	5 nm	0% 2.0% 5.0% 7.5% 10.0% 15.0% 30.0%	PMMA from Scientific Polymer Products (Ontario, NY)	(i) Measured TiO₂NP mixed with PMMA for 5-10 min (ii) DACA twin-screw extraction process at 190°C and 100 rpm. (iii) Acrylic mixed for 6-7 min and extruded 5 times	(i) Glass transition temperature (T_g) (ii) Thermal stability (iii) Decomposition temperature	10 x 6 x 0.3 mm	(i) T_g increased linearly up to 7.5% TiO₂NP. (ii) Thermal stability increased (2%-15% TiO₂NP) (iii) Decomposition temperatures increased with filler content up to 10% TiO₂NP.

Anehosur et al., 2012 [11]	31 nm “Anatase phase”	3.0% In addition to surface coating.	DPI heat cure acrylic resin, (India)	(i) Visible light activated TiO₂NP were mixed with methyl methacrylate monomer.	(i) Microbial inhibitory effect against S. Aureus	5 x 5 x 2 mm	(i) 3w% of TiO2 shows antimicrobial activity against S. Aureus.

Sodagar et al., 2013 [12]	21 nm “Anatase phase”	0% 0.5% 1.0%	Selecta Plus (self-cure acrylic resin)	(i) TiO₂NP were added to acrylic monomer.	(i) Flexural strength	50 x 10 x 3.3 mm	(i) Flexural strength decreased as the filler content increased.

					(i) Flexural modulus		(i) No change in flexural modulus.
Hamouda and Beyari, 2014 [13]	21 nm	5.0%	Conventional heat cure acrylic resin (Acroston, WHN, England) and high impact (Metrocryl Hi, Metrodent, LTD, England)	(i) TiO₂NP were mixed thoroughly with acrylic powder by hand.	(ii) Flexural strength (iii) Toughness	65 x 10 x 2.5 mm	(ii) Flexural strength and toughness decreased.
					(iv) Monomer release		(iii) No difference between control and TiO₂ reinforced regarding monomer release.

Nazirkar et al., 2014 [14]	7 nm “Anatase phase”	0% 0.5% 1.0%	DPI heat cure acrylic resin	(i) TiO₂NP added to acrylic monomer.	(i) Flexural strength	65 x 10 x 3.3 mm	(i) Flexural strength decreased as the TiO₂ amount increased.

Shirkavand and Moslehifard, 2014 [15]	<25 nm (average ~ 20.4 nm) “Anatase and Rutile phases”	0% 0.5% 1.0% 2.0%	Heat cure acrylic resin from Ivoclar Vivadent	(i) TiO₂NP were mixed with the acrylic resin polymer in an amalgamator for 20 min.	(i) Tensile strength	60 x 12 x 4 mm	(i) Tensile strength and elastic modulus improved with 1% TiO₂NP. (ii) 0.5% and 2% TiO₂ were not significantly different from each other or control.

Harini et al., 2014 [16]		0% 1.0% 2.0% 5.0%.	Clear heat cure acrylic resin	(i) Nanoparticles were incorporated into monomer by ultrasonic dispersion.	(i) Flexural strength	65 x 10 x 3 mm	(i) Flexural strength improved with TiO₂ addition, significant difference noticed with 5%.

Safi, 2014 [17]		5.0%	Heat cure denture base acrylic (Superacryl plus, Czechoslovakia)	(i) Nanoparticles added to monomer and sonically dispersed.	(i) Coefficient of thermal expansion (ii) Modulus (iii) Glass transition	15 x 6 mm Cylinders 65 x 10 x 2.5 mm Powder form (10g)	(i) Decrease in coefficient of thermal expansion. (ii) Decreased in modulus of elasticity (iii) Increased T_g

Alwan, and Alameer, 2015 [18]	<50 nm size	0% 3.0% (i) Silanized with TMSPM	Heat cure acrylic resin	(i) Silanized TiO₂NP were added to monomer and sonicated.	(i) Impact strength (ii) Transverse strength (iii) Hardness (iv) Surface roughness (v) Water sorption and solubility	80 x 10 x 4 mm 65 x10 x 2.5 mm 50 x 0.5 mm disc	(i) Increased (ii) Increased (iii) Increased (iv) Increased (v) Decreased

Ahmed et al., 2016 [19]	46 nm	0% 1.0% 5.0%	Conventional heat cure acrylic resin (Implacryl, Vertex) and high impact heat cure acrylic resin (Vertex-Dental, Netherlands)	(i) TiO₂NP were added into acrylic resin.	(i) Flexural strength (ii) Impact strength (iii) Hardness	50 x 10 x 3 mm 60 x 6 x 4 mm 25 x 10 x 3 mm	(i) Decreased with TiO₂ addition. (ii) Increased only for conventional acrylic resin modified by 1%. (iii) Increased with 5% addition TiO₂NP for both types of acrylic.

Sodagar et al., 2016 [20]	21 nm	0.5% 1.0%	Selecta Plus (self-cure acrylic resin)	(i) Nanoparticles were added to acrylic monomer and stirred	(i) Antimicrobial properties	20 x 20 x 1 mm	(i) TiO₂ reduced microbial growth at both concentrations at 90 min under UVA exposure (ii) Antimicrobial activity of TiO₂ is time dependent

Ahmed et al., 2017 [21]	<25 nm	0% 0.5% 1.0%	Heat cure acrylic resin from Dentsply International Inc., (Chicago, IL, USA)	(i) TiO₂NP were added to acrylic polymer and mixed using amalgam capsule.	(i) Flexural strength (ii) Fracture toughness (iii) Hardness	65 x 10 x 2.5 mm 65 x 10 x 2.5 mm 30 x 10 x 2.5 mm	(i) Increased with both filler percentages. (ii) No effect on fracture toughness of both filler percentages. (iii) Increased with 1% filler.

Hashem et al., 2017 [22]	90 nm	0% 1.0% 2.0% 3.0%	Self-cure acrylic resin from Eco-crylcold, Protechno, (Spain)	(i) TiO₂NP were mixed with the monomer.	(i) Flexural modulus and flexural strength (ii) Hardness (iii) Surface wetting	30 x 8 x 1 mm 50 x 1 mm discs	(i) Increased linearly (ii) Increased. (iii) Reduced with 1% filler content and increased with higher percentages. (iv) T_g decreased with TiO₂ addition

Ghahremani et al., 2017 [23]	20-30 nm “Anatase phase”	0% 1.0%	SR Triplex Hot, heat cure acrylic resin (Ivoclar Vivadent Inc. Schaan, Liechtenstein)	(i) TiO₂NP were mixed with acrylic resin powder in an ultrasonic mixer.	(i) Tensile strength (ii) Impact strength	60 x 12 x 3.9 mm 75 x 10 x 10 mm	(i) Increased (ii) Increased

Totu et al., 2017 [24]	65-170 nm	0% 0.2% 0.4% 1% 2.5%	PMMA+PEMA for 3D printing (eDent 100, EnvisionTec GmbH Gladbeck, Germany)	(i) Nanoparticles were added into PMMA solution with continuous stirring and ultrasonic mixing for 1 hour.	(i) Antimicrobial effect (Candida scotti) (ii) Complete denture manufacturing using stereolithography		(i) 0.4, 1% and 2.5% inhibited candida growth (ii) PMMA/0.4%TiO₂ composite successfully used for denture fabrication

Aziz, 2018 [25]	30 nm	0% 3.0%	High impact heat cure acrylic resin (Vertex-Dental, Netherlands)-	(i) TiO₂NP were dispersed in monomer and sonicated at 120W and 60 KHz for 3 minutes.	(i) Impact strength (ii) Color stability (iii) Thermal conductivity	80 x 10 x 4 mm 35 x 15 x 0.5 mm 40 x 2.5 mm	(i) Increased (ii) Increased color stability for test groups (iii) No effect

Alrahlah et al., 2018 [26]	80-100 nm	0% 1% 2% 3%	Heat cure acrylic resin (Lucitone 550, Dentsply Int. Inc. Pa, USA)		(i) Hardness and modulus (ii) T_g, degradation temperature and rate (iii) Creep-recovery and relaxation behavior (iv) Antibacterial adhesion	50 x 10 mm discs cut in different sizes for different tests 7 mg 5 x 10 mm	(i) Increased (ii) Slight increase with 2% nano-filler content (iii) Improvement in behavior (iv) Decrease in bacterial attachment content

Karci et al., 2018 [27]	13 nm	0% 1% 3% 5%	(i) Auto-polyerized (Heraeus Kulzer, Newbury Berkshire, UK) (ii) Heat-polymerized Heraeus Kulzer, Newbury Berkshire, UK. (iii) Microwave-polymerized (GC Dental, Tokyo, Japan)	(i) TiO₂NP were mixed with acrylic resin powder using ball milling at 400 rpm for 2 hours	(i) Flexural strength	65 x 10 x 3 mm	(i) Increased for heat- and auto-polymerized acrylic at 1% (ii) Decreased for all types of acrylic at 5%

Totu et al., Totu et al., 2017 [28]	“Anatase phase”	0% 0.2% 0.4% 0.6% 1.0% 2.5%	(i) PMMA-MA (ii) PMMA-MMA-BPO (iii) 3D printed PMMA (eD, EnvisionTec GmbH Gladbeck, Germany)	(i) TiO₂ modified by methacrylic acid then manually mixed with PMMA mixture	(i) Thermal stability (ii) T_g	Stereolithographic dentures	(i) Increased (improved) (ii) Increased

Totu et al., 2018 [29]	“Anatase phase”	0% 0.2% 0.4% 0.6% 1.0% 2.0% 2.5% 5.0%	PMMA for 3D printing (eDent 100, EnvisionTec GmbH Gladbeck, Germany)		(i) Resistance (ii) Electrical conductivity (iii) Dielectric constant		(i) Decreased with 1.0%, 2.0%, 2.5% and 5% (ii) Increased but material still maintained insulating properties (iii) Increased with 5%