Sinus floor elevation is often applied to the molar region of the atrophic maxilla to increase bone mass between the alveolar crest and
the sinus floor. Although autogenous bone graft is, so far, gold standard, limitations of donor site bone volume and post-operative
morbidity could be disadvantages. Thus, artificially synthesized bone substitutes, hydroxyapatite (HA) and tricalcium-phosphate
(TCP), might be advantageous useful materials compared to the autogenous bone.We have developed a novel technique of the sinus floor elevation using plate-shaped beta-TCP . In this study, changes of grafted
bone volume were quantitatively evaluated with cone-beam computed tomography (CBCT) and image analyzing software before and
1, 2, and 5 years after the surgery. Ten cases were recruited in this study. The bony windows were prepared on the lateral wall of the sinus and the sinus membrane was
carefully removed and elevated. Subsequently, the TCP plate was inserted and supported with dental implants or micro-screws.
Then, CBCT scan was performed to estimate temporal changes of the bone volume before surgery and at the time points of one, two,
and five years after the surgery. Digital Imaging and Communication in Medicine (DICOM) files of CBCT were converted into
Stereolithography (STL) files, using dedicated image analysis software for bone volume measurement and superimposing image data
with the best fit method. The difference of the image data representing the bone volume before and after the surgery was amalyzed
three-dimensionally, and the rate of change was calculated. This clinical research was approved by Ethics Committee, School of
Dentistry, Iwate Medical University, and the patient's consent was also obtained. Ten cases of the sinus floor elevation with plate-shaped beta-TCPs have been performed since 2011. This study consisted of three
men and seven women. The average age of all the patients was 53.3 years old. Bone volume decreased slightly until 2 years after the
surgery and then increased again until 5 years after the surgery. There had no complications concerning the abnormalities of the
maxillary sinus since the postoperative to the present, and it passed well. In most cases, newly formed bone in the sinus was
observed on X-ray photos 6 month after the operation. The good stability of the dental implant, at the second stage surgery, was
confirmed. TCP plates remained in the same position and achieved the secure space making for long time. Panoramic X-ray and
X-ray CT analyses revealed that TCP-plates were resorbed in 5 years post operation in most cases. The results of our study demonstrated that it is possible to evaluate the change of bone volume of the sinus floor elevation
quantitatively using the data of the STL form which converted DICOM. In this clinical trial, a new bone formation was observed in the
empty space between the TCP plate and the original sinus floor. TCP is a bone-conductive material and might have accelerated bone
formation. This newly established method for sinus floor elevation could bring better long-term prognosis.

Quantitative evaluation of sinus floor elevation using the plate shaped bone substitute