Table  3.  Results of  post  hoc  LSD  hardness  test  of  Heat-
Cured Acrylic Resin 
Sample 
groups 
Without 
NHA 
1% NHA  3% NHA 
Without 
NHA 
  0,000*  0,000* 
1% NHA      0,003* 
3% NHA       
 
The LSD test results in Table 3 show a significant 
difference (p≤0.01) in all treatment groups with the 
control  group.  Besides,  there  was  a  significant 
difference between groups II and III. 
4  DISCUSSION 
TEM characterization determined the size and shape 
of  the  particles.  Figure  5.2  shows  an  overview  of 
NHA  particles.  A  weak  magnification  of  5,000x 
indicates a spherical particle with a size of about 20 
nm.  A  strong  magnification  of  30,000x  shows  a 
clearer  picture  of  the  particle  shape,  a  163  nm 
spherical  shape.  The  morphological  description  of 
hydroxyapatite particles is indeed round and tends to 
be  irregular.  NHA  also  tends  to  experience 
agglomeration,  namely  the  fusion  of  several 
hydroxyapatite nanoparticles. 
The agglomeration of the hydroxyapatite particles 
occurs  during  the  synthesis  process  of  making 
hydroxyapatite.  Agglomeration  of  nano-sized 
particles usually occurs because nanoparticles have a 
high surface area and a more significant number of 
particles, so they tend not to be quickly stabilized, so 
they easily clump. Agglomeration also occurs due to 
the  lack  of  stirring  speed  during  the  synthesis  of 
hydroxyapatite. The description of NHA particles as 
per the research conducted by (Dong et al., 2009) that 
the particle morphology formed from hydroxyapatite 
is an irregular sphere, but this study only reports at a 
magnification of 5,000x . 
The  results  showed  that  the  addition  of  NHA 
particles with a  concentration  of  1%  and 3%  could 
increase the hardness of heat-cured acrylic resin. The 
most significant increase in hardness occurred in the 
group with the addition of 3% nano hydroxyapatite. 
The  hardness  of  heat-cured  acrylic  resin  was 
influenced by several factors, one of which was the 
particle  size.  The  particle  size  ranges  from  20-200 
nm.  This  result  is  per  the  research  conducted  by 
Afrizal et al. (2016) that hydroxyapatite with a small 
and delicate grain size will fill the space between the 
atoms of heat-cured acrylic resin and inhibits the rate 
of  dislocation  of  heat-cured  acrylic  resin  atoms, 
thereby  increasing  the  density  and  mechanical 
properties of heat-cured acrylic resin (Afrizal, 2016). 
The nano-hydroxyapatite that fills the space between 
the  atoms  of  the  heat-cured  acrylic  resin  is  a 
mechanical  bond.  The  use  of  nanofillers  with  a 
particle size of 10-100 nm can increase mechanical 
properties such as abrasion resistance, hardness, and 
flexural strength, so that the use of dentures with a 
sufficient period long expected to withstand abrasion 
(Rodrigues et al., 2008). 
5  CONCLUSIONS 
The  addition  of  blood  cockles  nano-hydroxyapatite 
could  increase  the  hardness  of  heat  cured  acrylic 
resin. 
ACKNOWLEDGEMENTS 
The  authors  especially  thank  LPPM  Jenderal 
Soedirman University for funding this research at the 
Competency Improvement Research scheme. 
REFERENCES  
Afrizal,  A.,  2016.  Analisa  Struktur  Mikro  Material 
Substitusi Hidroksiapatit Cangkang Kerang Darah dan 
Resin Akrilik Bahan Pembuat Gigi untuk Aplikasi Gigi 
Tiruan. Jurnal Surya Teknika, 2(04), pp. 1–9.  
Alla, R. K., Swamy, R. K., Vyas, R., & Konakanchi, A., 
2015.  Conventional  and  Contemporary  polymers  for 
the fabrication of denture prosthesis: part I-Overview, 
composition  and  properties.  International Journal of 
Applied Dental Sciences, 1(4), pp. 82–89.  
Awang, A. J. H., Zuki, A. B. Z., Noordin, M. M., Jalila, A., 
&  Norimah,  Y.,  2007.  Mineral  Composition  of  the 
Cockle  (Anadara  granosa)  Shells  of  West  Coast  of 
Peninsular Malaysia and  It’s Potential as  Biomaterial 
for  Use  in  Bone  Repair.  In  Journal of Animal and 
Veterinary Advances, 6(5),  pp. 591–594. 
Dong,  Z.,  Li,  Y.,  &  Zou,  Q.,  2009.  Degradation  and 
biocompatibility  of  porous  nano-
hydroxyapatite/polyurethane  composite  scaffold  for 
bone  tissue  engineering.  Applied Surface Science, 
255(12), pp. 6087–6091.  
Hameed,  H.  K.,  &  Rahman,  H.  A.,  2015.  The  Effect  of 
Addition  Nano  Particle  ZrO2  on  Some  Properties  of 
Autoclave Processed Heat Cure Acrylic Denture Base 
Material.  Journal of Baghdad College of Dentistry, 
27(1), pp. 32–39.  
Kenneth  J  Anusavice,  C  Shen,  H.  P.  R.,  2013.  Philips 
Science of Dental Material 12th  (12th  ed.).  Elsevier 
The Effect of Addition of Blood Cockles (Anadara granosa) Shell Nano-Hydroxyapatite on Hardness of Heat Cured Acrylic Resin