• the relative amount of mineralised tissue (=newly formed bone plus BO)
  

• Histology:
  
• Relative amount of newly formed bone, graft residues, bone marrow, residual bone and connective tissue.
  
• Clinical parameters:
  
• complications during surgery related to the material.
  
• post-operative complications.
  
• Max torque for implant insertion.
  
• short-term implant survival (up to one year post loading)
  

the use of bovine bone mineral particles (Bio-Oss®)in sinus floor augmentation is well established. bovine bone mineral is an oseoconductive material which serves as a space maintainer and a scaffold for bone augmentation. the commercial product is manufactured in two different particles sizes, "large"1-2 mm, and "small"0.25-1 mm.

Comparison: the histologic characteristics of augmented bone after the use of Bio-Oss® (BO) with particle size of 0.25-1 mm vs. Bio-Oss® (BO)with particle size of 1-2 mm.

Inclusion Criteria:

• The patients included in this study are over 18 year old men and women.
• The patient must be a candidate for sinus floor augmentation.
• The patient is able to comply with the study-related procedures such as exercising good oral hygiene and attending all follow-up procedures.
• The patient is able to fully understand the nature of the proposed surgery and is able to provide a signed informed consent.

Exclusion Criteria:

• Pregnant women.
• People who smoke more than 10 cigarettes a day.
• Alcohol and drug abusers.
• People suffering from uncontrolled diabetes, severe osteoporosis, rheumatic arthritis, precancer or neoplastic lesions of oral cavity.
• The patient is nursing.