Maxillary sinus floor augmentation with autogenous bone and bovine bone mineral in the resorbed maxilla: a 1-year multicentre, split-mouth, randomized clinical trial

Insufficient bone height is a common problem in the reconstruction of the
edentulous posterior maxilla with dental implants. The dimensions of the
alveolar ridge and maxillary sinus change after tooth extraction, which can
negatively influence the possibility of placing dental implants (Juodzbalys &
Kubilius 2013, Sharan & Madjar 2008).

To create sufficient height in the severe resorbed posterior maxilla, sinus
floor augmentation (MSFA) is performed with autogenous bone (AB) grafts, bone
substitutes, or a mixture of both (Esposito, et al. 2014). MSFAs for the
placement of implants are originally described by Boyne and James (1980) and
Tatum (1986). Nowadays, these augmentations are a commonly performed and
successful procedure for the reconstruction of the edentulous posterior maxilla
(Del Fabbro, et al. 2013, Esposito, et al. 2014, Wallace & Froum 2003).

The use of AB for grafting procedures is still considered the gold standard. No
other type of graft can match the abilities of AB, were surviving osteoblasts
directly produce bone (osteogenesis) and undifferentiated mesenchymal cells are
stimulated to differentiate into osteoblasts (osteoinduction) (Hallman & Thor
2008, Misch & Dietsh 1993). However, there are major drawbacks of using AB,
such as fast resorption, the morbidity of the donor location and the amount of
grafting material available in cases of major resorption (Kuik, et al. 2016,
Raghoebar, et al. 2001, Raghoebar, et al. 2007). Different bone substitutes are
described in literature to bypass these shortcomings of AB (Hallman & Thor
2008), such as alloplastic substitutes (Danesh-Sani, et al. 2016, Schulten, et
al. 2012, Zerbo, et al. 2004), allogeneic bone grafts (Froum, et al. 2006,
Xavier, et al. 2015, Xavier, et al. 2015) and currently most used, xenografts
such as bovine bone mineral (BBM) (Hallman, et al. 2002, Merli, et al. 2013,
Rickert, et al. 2011, Xavier, et al. 2015).

Why it is important to do this comparison study of AB versus bone-substitutes?

There are 3 reasons:
1. 1. It is unknown if AB or BBM with some AB is more successful for MSFA
Hallman, et al. (2002)a is the only RCT (N=11) describing AB versus BBM in
combination with some AB for two stage bone augmentation with the BBM as the
only procedural variable. In the AB group an implant failure of 18% was found
versus 6% in the group with BBM. This difference was described as not
statistically different. Both treatment options have their pro and cons but the
resistance of xenograft material to resorption and degradation may be an
advantage for maintaining the initial dimensions of the augmented sinus, as
analysis revealed a less than 10% change over 12 months of loading (Hallman, et
al. 2002)b. Our aim is to determine which treatment is more successful for
MSFA.
2. No need for harvesting AB from a second surgical site but via the existing
incision for MFSA Only very few randomized controlled trials compared AB with
(xenogeneic) bone substitutes in MFSA procedures (Al-Nawas & Schiegnitz 2014,
Esposito, et al. 2014, Jensen, et al. 2012). These studies showed promising
results, as bone substitutes may overcome the major drawbacks of solely using
AB which is associated with co-morbidity of the donor site and the limited
amount of bone available in case of major site reconstruction and resorption
(Kuik, et al. 2016, Raghoebar, et al. 2001, Raghoebar, et al. 2007). However
recent studies on MSFA with bone substitutes still showed considerable
co-morbidity as bone substitutes are mixed with additional AB from the
mandibular ramus (Hallman, et al. 2002) or stem cells harvested from the iliac
crest (Rickert, et al. 2011). In this study we will harvest AB via the existing
incision and thereby possible co-morbidity at a second surgical site is no
issue any more.
3. Shortening healing period after MSFA. If only bone substitutes are used with
no additional autogenous material, extensive healing periods of 9 months are
reported (Hallman, et al. 2002, Merli, et al. 2013). In our study we will use
bone substitutes mixed with locally harvested bone chips through the existing
incision. With this mixture we expect to place and load implants after a
shorter healing time (4-6 months).

The aim of this study is to assess the success of MSFA determined by 1-year
clinical performance of dental implants placed in the posterior maxilla after
MSFA surgery with AB versus BBM with some locally harvested autogenous bone
chips.

The study will be designed as a multicenter, split-mouth, randomized clinical
trial (RCT).

In all patients billateral maxillary sinus floor augmentation's will be
performed

Sides will be randomly assigned to:
* 1. AB harvested from mandibular ramus
* 2. BBM, Cerabone (Cerabone, Botiss Dental, Berlin, Germany) mixed with
approximately one-fifth locally harvested AB chips (via existing incision for
sinus elevation).

The measurements performed in this research are clinical and radiological
analyses of the peri-implant tissues and histological analyses of the bone
samples collected at dental implant placement. Participation in this research
is not dangerous and the patients are not at risk. The radiographs (before and
after placing the implants) are taken, whether or not the patient is
participating in this research. Radiological follow-up is not hazardous; the
health of the patients is not at risk. Due to the fact that the treatments have
been performed for many years we expect no complications. In case of pregnancy
the treatment is not performed, but postponed till after pregnancy. In case the
patient wants to withdraw from this research this does not have any
consequence. The treatment will be identical. However, the collected
measurements will not be used for this research.