A Randomized Trial to Evaluate the Effect of Allograft Bone Particle Size on Histomorphometric and Clinical Outcomes Following Ridge Preservation/Augmentation Procedures
Phase: NA
Conditions: Alveolar Ridge Augmentation, Alveolar Ridge Preservation
Sponsor: University of Alabama at Birmingham

The Influence of Bone Allograft Particle Sizes 
on the Quantity and Quality of New Bone 
Formation in Grafted Extraction Sockets and 
Edentulous Ridges
Study Protocol & Statistical Analysis Plan 
NCT03468998 
February 6, 2022
Ramzi V. Abou-Arraj, DDS, MS, Principal Investigator 
University of Alabama at Birmingham 
Birmingham, Al 35294 

 
 
The Influence of Bone Allograft Particle Sizes on the Quantity and Quality of New Bone 
Formation in Grafted Edentulous Ridges 
 
 
1. Abstract:   
 
 
Ridge deficiency is an unfortunate obstacle that obviates the placement of dental implants or 
results in placing them at an angle that compromises the prosthetic restoration.An ideal volume 
is essential for implant placement in the buccal/palatal, apical/coronal, mesial/distal dimensions. 
Several methods for augmenting the alveolar ridge in preparation for implant placement have 
been described. Autogenous bone grafts, which are considered to be the “gold standard” ,are 
associated with significant morbidity and require a second surgical site.Guided bone regeneration 
(GBR), is an alternative technique that use bone-substitute materials as adjuncts to or 
replacements for autografts in bone augmentation procedures to overcome the limitations related 
to the use of autografts.Freeze-dried bone allograft (FDBA), of various particle sizes, is commonly 
used today and has shown success  in augmenting deficient ridges. A graft material that promotes 
a high percentage of new vital bone is beneficial for implant placement and stability.The effect of 
particle size on the clinical and histological outcomes of lateral ridge augmentation (insufficient 
edentulous ridge width) has been scarcely studied or reported in the literature.This randomized 
clinical trial aims to clinically and histologically compare the amount of the bone gained after lateral 
ridge augmentation procedures performed using small (100-300μm) versus large(1000-2000μm) 
particle size bone cortico-cancellous allograft (MaxxeusTM Dental, Community Tissue Services, 
Kettering, OH) at 6 months following surgical intervention. 
 
 
 
2. Introduction/Background: 
 
Dental rehabilitation of partially or totally edentulous patients 
with oral implants has become a routine treatment modality in the last 
decades, with reliable long-term results(1-7).However, early loss of 
the teeth due to trauma or periodontitis often leads to deformities in 
these resulting edentulous ridges. Studies have demonstrated that 
bone resorption will occur secondary to tooth extraction(8-10). This 
tends to occur over a 12 month period, most notably in the first 4 
months following extraction (Fig. 1) and, depending upon location, 
may range up to 5–7 mm bucco-lingually. In addition, 2–4 mm of 
vertical height loss frequently accompanies the horizontal loss and 
usually is seen when multiple adjacent extraction sites are 
combined(8-10). 
 
Fig. 1. Ridge resorption following tooth 
extraction. (A) 1 week after tooth extraction 
(B) 12 weeks after extraction  
A) 
B 

 
 
           
 
Unfavorable local conditions of the alveolar ridge, may provide 
insufficient bone volume or unfavorable vertical, horizontal, and 
sagittal inter-maxillary relationships, which may render implant 
placement impossible or incorrect from a functional and esthetic 
viewpoint (11).Several methods for augmenting the alveolar ridge in 
preparation for implant placement have been described. Among 
these techniques, guided bone regeneration (GBR) has probably 
generated the most interest(12,13).The concept of GBR (Fig. 2) is 
based upon the use of a barrier membrane to exclude rapidly 
growing soft tissue cells from a bony defect and, more importantly, to 
maintain a space for the slower process of bone formation. Bone 
grafts or bone substitutes are commonly used in GBR procedures to 
provide support for the barrier membrane, for additional space 
maintenance, and/or for their osteoconductive / osteoinductive 
properties. 
 
Autogenous bone grafts are still considered the gold standard in bone regeneration 
procedures(14). However, donor site morbidity, unpredictable resorption, limited quantities 
available, and the need to include additional surgical sites are drawbacks related to autografts 
that have intensified the search for suitable alternatives(15-16). Bone-substitute materials have 
increased in popularity as adjuncts to or replacements for autografts in bone augmentation 
procedures to overcome the limitations related to the use of autografts. Bone-substitute materials 
can be categorized in three groups: (1) allogenic, from another individual within the same species; 
(2) xenogenic, from another species; or (3) alloplastic, synthetically produced. 
 
Due to the success in space maintenance, rapid bone turnover, biocompatibility, and the 
lack of need to harvest from another site, allograft materials have become increasingly popular. 
Evidence-based treatment results indicate that guided bone regeneration (GBR) for localized 
alveolar ridge deformities can effectively augment the ridge with new bone in the range of 1.5 to 
5.5 mm(14,16,17). Freeze-dried bone allograft (FDBA) is commonly used today and has shown 
success, both clinically and histologically in augmenting deficient ridges. A graft material that 
promotes a high percentage of new vital bone is beneficial for implant placement and stability. 
Because particulate mineralized freeze-dried bone allograft (FDBA) is effective in producing 
dense new bone, it is often preferred to decalcified freeze-dried bone allograft (DFDBA) for lateral 
ridge augmentation prior to implant placement(18,19). However, there is a paucity of 
documentation to verify this clinical impression. Both clinical and histologic results indicate a 
beneficial effect from the addition of DFDBA to GBR procedures in humans(20).This combination 
results in the formation of viable new bone at 9 months(21) . Histologic examination of biopsy 
samples from the sub-membranous hard tissue reveals particles of DFDBA partially surrounded 
by un-inflamed connective tissue and by vital bone adjacent and adhered to the DFDBA 
particles(22). The histologic results of a study comparing FDBA and DFDBA showed that in 
DFDBA sites, only the particles near the host bone are involved in the mineralization processes, 
while in FDBA sites, even the particles that are farthest from the host bone are lined by 
Fig. 2. GBR concept   

 
 
osteoblasts, actively secreting osteoid matrix and newly 
formed bone(23). This suggests more of an osteo-conductive 
effect with FDBA than DFDBA. 
 
The effect of particle size (Fig. 3) on the clinical and 
histological 
outcomes 
of 
lateral 
ridge 
augmentation 
(insufficient edentulous ridge width) has been scarcely studied 
or reported in the literature. Shapoff et al  (24) did a study 
Rhesus Monkeys to determine if particle size should be 
considered as a factor for evaluation of osteogenic activity of 
FDBA.He found that there is a significantly more new bone 
formation associated with small particle FDBA when mixed 
with autogenous marrow than that of the large particles.Also, 
he found that there is a marked resolution of small graft 
particles in the new bone formed. He concluded that small 
particles FDBA enhance osteogenesis when mixed with 
autogenous marrow by increasing the number of pores. 
 
In a prospective randomized controlled clinical trial, 
Testori 
et 
al. 
(25) 
compared 
the 
histologic 
and 
histomorphometric vital bone formation and residual graft 
volume in human bilateral sinus augmentations performed with 
either large (1.0 to 2.0 mm) or small (0.25 to 1 mm) particle 
size anorganic bovine bone matrix in 13 patients. For each 
patient, one subantral compartment was grafted with 100% 
large particle Bio-Oss and the contralateral subantral 
compartment was grafted with small particle Bio-Oss. At stage-
one implant placement surgery 24 to 32 weeks later, a trephine core sample was taken (10 × 3 
mm) from the superior-distal area of the former lateral window site as identified by measurements 
taken at the time of sinus elevation. Blinded paired histomorphometric  and histologic analysis 
was subsequently performed on 11 bilateral cases. Vital bone formation was 26.77% ± 9.63% vs 
18.77% ± 4.74% for the large particle and small particle grafts, respectively. Residual xenograft 
was 20.01% ± 8.97% vs 21.66% ± 10.47% for the large and small particle grafts, respectively. At 
the 24- to 32-week time interval, the new bone appeared as woven bone with several large 
rounded osteocyte lacunae. Close contact between graft granules embedded in the mineralized 
bone and bone matrix is observed.  Hence, the histologic results of this study reaffirm the 
osteoconductive ability of the ABBM (Bio-Oss) when used as the sole grafting material in maxillary 
sinus augmentation and the histomorphometric results indicate a statistically significant increase 
in vital bone formation when the larger particle size is used. These findings were not shown in a 
previous maxillary sinus augmentation study where there was not a statistically significant 
difference in the percentage of new vital bone formation. (26) The authors related the difference 
between studies to the small sample size included in both. (25) 
 
 
3. Objectives/Specific Aims:  
 
The aim of this study is to histologically and clinically compare the amount of the 
bone gained after lateral ridge augmentation (edentulous ridge) procedures performed 
using small versus large particle size bone cortico-cancellous allograft (MaxxeusTM 
Dental, Community Tissue Services, Kettering, OH).  
 
 
 
Fig. 3. Maxxeus Allograft ;  
(A)Small 
particles 
(100-300μm).(B)Large 
particles (1000-2000μm).  
(A) 
(B) 
(A) 
(B) 

 
 
Hi st o m or p h o m etri c  o ut c o m e s( Pri m ar y  O ut c o m e s):   
               -e v al u at e  t h e q u alit y  of  b o n e  r e g e n er at e d wit h  t h e u s e  of  t h e t w o a v ail a bl e  b o n e  
all o gr aft  p arti cl e  si z e s  
          -e v al u at e  w h et h er  t h e si z e  of  c o m m er ci all y  a v ail a bl e  b o n e  all o gr aft s  i nfl u e n c e s 
t h e o ut c o m e s  of  g ui d e d  b o n e  r e g e n er ati o n ( G B R) pr o c e d ur e s  
 
Cli ni c al  a n d  R a di o gr a p hi c  o ut c o m e s( S e c o n d ar y  O ut c o m e s):   
           -q u a ntif y  t h e a m o u nt  of  b o n e  a u g m e nt ati o n  a c hi e v e d  b y  t h e t w o a v ail a bl e  b o n e   
all o gr aft  p arti cl e  si z e s  b y  dir e ct  cli ni c al  m e a s ur e m e nt s  
          -q u a ntif y  t h e a m o u nt  of  b o n e  a u g m e nt ati o n  a c hi e v e d  b y  t h e t w o a v ail a bl e  b o n e  
all o gr aft  p arti cl e  si z e s  b y  r a di o gr a p hi c m e a s ur e m e nt s  ( C B C T) 
          -e v al u at e  t h e h a n dli n g  c h ar a ct eri sti c s  of  t h e t w o a v ail a bl e  b o n e  all o gr aft  p arti cl e  
si z e s.   
 
 
4.  M at eri al s  a n d  M et h o d:  
 
St u d y  p o p ul ati o n   
A  t ot al of  5 0  p ati e nt s  s e e ki n g  tr e at m e nt at  t h e U A B  S O D  Gr a d u at e  P eri o d o nt ol o g y  cli ni c s  will  b e  
r e cr uit e d t o p arti ci p at e  i n t hi s st u d y  a c c or di n g  t o t h e crit eri a  i n T a bl e  1.   
If d e e m e d  eli gi bl e,  st u d y  vi sit s,  o bj e cti v e s,  ri s k s a n d  b e n efit s  will  b e  e x pl ai n e d  t o all  p arti ci p a nt s  
a n d  I R B-a p pr o v e d  writt e n  i nf or m e d c o n s e nt  will  b e  o bt ai n e d..  O n e  tr ai n e d c ali br at e d  e x a mi n er  
will  b e  a v ail a bl e  f or all  st u d y  vi sit s  w h e n  cli ni c al  m e a s ur e m e nt s  ar e  r e q uir e d. P h ot o gr a p h s  will  b e  
t a k e n d uri n g  all  vi sit s  u si n g  a  S L R  di git a l c a m er a  i n a  1: 1  r ati o. 
 
R a n d o mi z ati o n   
R a n d o mi z ati o n  will  t a k e pl a c e  o n  t h e d a y  of  s ur g er y  vi a  s e al e d  e n v el o p e s  i n di c ati n g t h e s ur gi c al  
a p pr o a c h  t h e p ati e nt  will  r e c ei v e, a s  f oll o w s: 
• 
Gr o u p  1:  S m all  p arti cl e  ( S P) b o n e  all o gr aft  ( 0. 2 5-1. 0  m m),  or   
• 
Gr o u p  2:  L ar g e  p arti cl e  ( L P) b o n e  all o gr aft  ( 1. 0-2. 0  m m)  
 
 
 
T a bl e  1.  St u d y  I n cl u si o n a n d  E x cl u si o n  Crit eri a  
I n cl u si o n Crit eri a  
E x cl u si o n  Crit eri a  
P ati e nt s:  
 
E n gli s h  s p e a ki n g  
 
At  l e a st 1 8  y e ar s  ol d  
 
A bl e  t o r e a d a n d  u n d er st a n d  i nf or m e d c o n s e nt  
d o c u m e nt  
 
N e e d  i m pl a nt s t o r e pl a c e mi s si n g  t o ot h or  t e et h i n at  
l e a st o n e  q u a dr a nt  of  t h e m o ut h.  
 
P ati e nt  at  U A B  d e nt al  s c h o ol  
 
willi n g  a n d  a bl e  t o c o m pl y  wit h  t h e pr e o p er ati v e  a n d  
p o st o p er ati v e  di a g n o sti c  a n d  cli ni c al  e v al u ati o n s  
r e q uir e d. 
• S y st e mi c  c o n diti o n s  c o ntr ai n di c a ti n g or al  s ur gi c al  
pr o c e d ur e s  or  a d v er s el y  aff e cti n g  w o u n d  h e ali n g  
• si g nifi c a nt  m e di c al  c o n diti o n s  or  h a bit s  e x p e ct e d  t o 
i nt erf er e wit h  b o n y  h e ali n g.  
S m o ki n g  > 1 0  ci g ar ett e s/ d a y  
P ati e nt  i s a  p o or  c o m pli a n c e  ri s k (i. e., p o or  or al  h y gi e n e,  
hi st or y  of  al c o h ol  or  dr u g  a b u s e)  
I n s uffi ci e nt al v e ol ar  ri d g e wi dt h  f or e n d o s s e o u s  i m pl a nt 
pl a c e m e nt  d efi n e d  a s  5 m m  or  l e s s a s  d et er mi n e d  b y  b o n e  
s o u n di n g  a n d  c o n e  b e a m  c o m p ut e d  t o m o gr a p h y ( C B C T) 
s c a n.   
V erti c al  l o s s of  b o n e  at  e d e nt ul o u s  ri d g e 
 
 
 

 
 
 
Screening/baseline visit:  
Upon enrollment into the study the patient’s medical history and electronic records will be 
reviewed. Patients will be treatment planned by an interdisciplinary team consisting of a 
surgeon and a prosthodontist or restoring dentist. Cone Beam Computed Tomography 
(CBCT) scan will be taken to optimize the treatment plan and determine the feasibility of 
implant placement following bone grafting. Clinical examiners will conduct clinical and 
radiographic exams to determine eligibility according to the above inclusion criteria. Study 
visits and objectives will be explained to all participants. IRB approved written informed 
consent will be obtained from all the participants. 
 
Surgical visit (Visit 1):(Fig. 4) 
A course of prophylactic antibiotics will be dispensed at the time of surgery (mostly 
Amoxicillin 2 g or Clindamycin 600 mg, 30 minutes to one hour prior to surgery).  After 
preparation and isolation of the surgical area, anesthesia will be accomplished by intravenous 
or inhalation sedation (when indicated) plus local anesthesia.  
 
The graft material utilized for all surgical procedures, for all patients, will be obtained from one 
manufactured lot, from the same donor to account for variation in age, race, gender and 
related healing potential of different grafts (MaxxeusTM Dental, cortico-cancellous bone 
allograft, Community Tissue Services, Kettering, OH).    
 
For patients that present with an edentulous ridge insufficient to house one or more dental 
implants, requiring a lateral ridge augmentation procedure: 
A crestal incision will be made on the study quadrant. A superficial split thickness will be made 
on the facial surface to allow flap extension to achieve complete coverage of the barrier 
membrane material.  The secondary periosteal flaps will be fully reflected to allow adequate 
access to the surgical site.  The surgical site will be debrided and degranulated.  After 
exposure of the bone the implant sites will be located with the use of the surgical stent and 
the ridge width will be measured at the crest and 4 mm apical to the crest with the a 
standardized caliper. The area of augmentation will be decorticated using a high speed hand 
piece with a #2 round bur perforating the cortical plate every 4 mm throughout the area 
needing the augmentation. The defects will be grafted with the randomized bone allograft (SP 
or LP). The graft sites will be covered with a resorbable barrier membrane.  The same type of 
membrane from the same manufactured lot will be used for all defect sites; however, the 
membrane will be trimmed for the individual defects during surgery.  All surgical sites will be 
closed with the same, vicryl PGA Hu-Friedy Perma Sharp® suture.   
 
Post-surgical analgesics will be prescribed and/or dispensed as necessary.  All subjects 
will be dispensed Peridex® chlorhexidine mouth rinse and instructed to rinse twice daily for 
two weeks following the regenerative surgery, to help guard against possible infection.  Pre-
surgical antibiotics will also be dispensed and prescriptions for relief of post-surgical 
discomfort, follow-up antibiotics and written home care instructions will be provided. 
Immediately following the surgery the surgeon will complete a handling characteristics survey 
on the properties of bone graft material.  
 
 
 
 
 
 
 
 
 

 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Visit 2 (Follow-up): (Fig. 5) 
The sutures will be removed 
after two weeks after cleaning the 
sutures with a gauze stacked with 
Peridex® chlorhexidine mouth 
rinse . Surgical sites will be evaluated for healing status and postoperative instructions on 
resuming oral hygiene measures will be instructed to patients. 
 
 
 
Visit 3 (Bone Biopsy and Implant Placement):  
Six months post-ridge augmentation, a second CBCT scan will be taken to evaluate the 
success of the grafting procedures and to plan the optimal implant position. The sites will be 
exposed for surgical placement of implants. The surgical approach will be similar to the 
(A) 
(B) 
(C) 
(D) 
(E) 
(F) 
(G) 
(H) 
(I) 
Fig. 4. Surgical steps .(A) Clinical appearance of horizontal ridge defect, (B) Crestal and vertical incisions, (C) Full thickness 
flap elevation .notice horizontal defect, (D) Mucoperiosteal release,(E) Bone decortication, (F) Particulate bone graft placed 
to rebuild defect,(G) bioresorbable collagen membrane shaping,(H) Placing the collagen membrane over grafted area,(I) 
Suturing 
Fig. 5 . (A) initial appearance (B) 2 weeks follow-up and suture removal  
(A) 
(B) 

 
 
procedures for the graft procedures. After exposure of the bone the 
implant sites will be located with the use of the surgical stent (prepared 
by the restoring dentist) and the ridge width will be measured at the 
crest and 4 mm apical to the crest with the same standardized caliper. 
If ridge width permits implant placement, root form dental implants will 
be placed. Prior to implant placement a bone biopsy will be taken from 
the implant sites using a 2 mm internal diameter trephine(Fig. 6). For 
the bone biopsy, first the new bone will be measured, next the center 
of the new bone will be identified, and finally the core will be taken from 
the center of the new bone.  The biopsy will be stored in the correct 
medium and will be sent to the Histomorphometry and Molecular 
Analysis Core for histomorphometric analysis. The implant preparation 
will be completed and implants will be placed according to 
manufacturer protocol. 
 
All clinical measurements will be taken by one experienced examiner blinded 
to the randomization process (small vs. large particles) before grafting and 
at time of implant placement.Another examiner will perform the radiographic evaluations and will 
also be blinded to the randomization process. Intra-examiner calibration will be conducted to 
ensure reliability of measuring method. 
 
Sample size rationale:  
To reject the null hypothesis of equal means with a significance level (alpha) of 0.05 using 
a two-sided two-sample unequal-variance t-test, 22 patients in each group (total of 44) will reach 
0.90 statistical power. Accounting for a 8 patient loss-to-follow up, 50 patients will be enrolled in 
the study. 
 
Histomorphometric Analysis 
Immediately following the bone biopsy at the center of the healed and regenerated ridge 
with a trephine (2-mm internal diameter), the specimen is placed in a formalin solution. Following 
fixation with 10% neutral buffered formalin for 48h, the bone biopsy specimens will be dehydrated, 
embedded in methylmethacrylate, ground sectioned at the center of the biopsy in its long axis into 
50-70 micron-thick sections (Exakt Technologies, Inc., Oklahoma City, OK), and polished with 
4000 grit sandpaper and Novus Polish to create as smooth a surface a possible. All sections will 
be stained with Sanderson’s Bone Stain and imaged for quantification of bone formation. 
Histomorphometry will be done using the Bioquant® Image Analysis Software (R&M Biometrics, 
Nashville, TN) by measuring the total surface of vital bone, residual graft particles, organic matrix 
and artifact/air components. Corresponding percentages will be calculated for each of these 
tissues and compared between small and large particle grafts for ridge preservation and 
augmentation separately.  
These experiments will be conducted at the UAB Histomorphometry and Molecular Analysis Core 
and all measurements made by an experienced blinded lab technician 
 
 
Table 2. Clinical parameters and their respective timing of measurement  
Clinical parameters 
Timing of measurements 
Cone Beam CT Scan  
Screening, 6 months post-op  
Width of bone at the crest level and 4mm apical  using a gauge(Pre-surgical) and 
a surgical stent (surgical ) 
Screening, Surgery (Pre-surgical), 
6 post-op 
Biopsy at the center of healed bone graft  
 6 months post-surgery 
 
 
Fig.6 Bone Biopsy taken 
prior to implant placement 
using a trephine  

 
 
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The Influence of Bone Allograft Particle Sizes on the Quantity and Quality of New Bone 
Formation in Grafted Extraction Sockets  
 
 
1. Abstract 
 
 
Ridge preservation (socket grafting) at the time of tooth extraction is a commonly performed procedure that prevents 
extensive ridge resorption and allows for optimal implant placement. Ridge preservation can be achieved with 
different graft materials from autogenous, allogenic, xenograft, and alloplast sources. Due to its success in space 
maintenance, rapid turnover, biocompatibility, and the lack of need to harvest from another site, small-sized bone 
allograft materials (especially freeze-dried bone allografts, FDBA) have become increasingly popular. However, the 
effect of particle size on the clinical and histological outcomes following site preservation at the time of tooth 
extraction has not been well studied or reported in the literature. This randomized trial aims to clinically and 
histologically compare the amount and quality of the bone gained following ridge preservation procedures when using 
small (250-1000μm) versus large (1000-2000μm) particle size bone cortico-cancellous allografts at time of dental 
implant placement, 3 months following surgical intervention. 
 
 
2. Introduction/Background 
 
Studies have demonstrated that bone resorption occurs 
secondary to tooth extraction with the majority of dimensional 
changes occurring within the first 3 to 6 months [1-5]. The 
buccal wall of the socket (Fig. 1) tends to be resorbed to a greater 
degree than the lingual wall because the coronal aspect of the 
buccal plate is often comprised of bundle bone, a very thin layer 
(≤1mm in most cases) of bone [6]. Cardaropoli et al. [1] reported 
a meaningful negative correlation between baseline buccal wall 
thickness and ridge width change at sites receiving tooth 
extraction but no ridge preservation procedures. Vertical height loss frequently accompanies the horizontal loss and 
usually is seen when multiple adjacent extraction sites are combined (Fig. 2). Some have described a loss of up to 
50% of the overall ridge width without ridge preservation  at time of tooth extraction [7]. 
 
Implant dentistry has become a successful routine treatment modality for partially or totally edentulous patients [8-
14]. Socket grafting at the time of tooth extraction (referred to as ridge preservation) tends to maintain the bone 
volume necessary for the esthetic and functional placement of a dental implant [5, 7, 15-19]. In post-extraction ridge 
preservation procedures, a systematic review by Jambhekar et al. [5] reported on the histologic outcomes and/or 
changes in the bucco-lingual dimension and buccal wall height for a total of 117 extraction sockets grafted with 
allograft in 5 studies. For the re-entry point at implant placement at or beyond 12 weeks, the mean loss of bucco-
lingual width at the crest level was 1.63 mm and the mean loss of buccal wall height from the ridge crest was 0.58 
mm [5]. These average dimensional changes are dramatically less than those observed following tooth loss in the 
absence of socket preservation.  
 
Allografts are the most widely used bone replacement grafts for intra-oral applications in the US. Certified tissue 
banks use typically proprietary techniques for processing and packaging these allografts, to ensure their safety and 
Fig 1. A. Socket anatomy, B. Loss of buccal bone 
following tooth extraction.  
Fig. 2 A. Ridge shape and volume 
before 
extraction 
of 
mandibular 
anterior teeth. B. Ridge shape and 
volume after extraction without socket 
grafting of 3 adjacent teeth. Note 
vertical loss of ridge height.  
A 
B 

 
 
their clinical availability. Two of the most commonly used allografts in dentistry are freeze-dried bone allografts 
(FDBA) and demineralized freeze-dried bone allografts (DFDBA). It has been reported that FDBA physically 
maintains the socket space and acts as a scaffold for host osteoprogenitor cells during the healing phase. On the other 
hand, released bone morphogenetic proteins (BMPs) from DFDBA give the allograft the added benefit of 
osteoinductivity by stimulating the host osteoprogenitor cells to differentiate into osteoblasts and begin new bone 
formation [20]. 
 
Eskow and Mealey [16] histologically evaluated in a randomized clinical trial the new bone formation following ridge 
preservation with cortical FDBA compared with cancellous FDBA. All bone graft materials were obtained from the 
same donor and a standard particle size of 250 to 1,000 μm was chosen for the study. A greater percentage of residual 
graft material was found in the cortical group compared with the cancellous group and as the percentage of new bone 
formation increased, the percentage of residual graft material decreased. No difference was found in the percentage 
of new bone formation between the two groups when core biopsies were harvested an average of 18 weeks after 
extraction and socket grafting.  
 
Whitman and Mealey [19] reported on the differences in healing after tooth extraction and ridge preservation of non-
molar teeth using DFDBA at 8 to 10 weeks of healing compared with 18 to 20 weeks of healing. There was no 
difference in ridge dimensional changes between sites healing for an average of 9 weeks compared with 19 weeks. 
There was a significantly different percentage of new vital bone between the short-term group and the long-term 
group. The short-term group had a mean of 32.63% vital bone compared with 47.41% in the long-term group. 
However, the authors stated that it was uncertain if the percentage of vital bone at an implant site would directly affect 
implant survival or success. 
 
In another ridge preservation randomized clinical study, Wood and Mealey [15] histologically evaluated and 
compared the healing of non-molar extraction sockets grafted with DFDBA versus FDBA. There were no statistically 
significant differences in the changes in ridge dimensions after ridge preservation is performed with DFDBA versus 
FDBA. However, histology showed a significantly greater percentage of vital bone in sites grafted with DFDBA 
(81.26%) versus FDBA (50.63%), and DFDBA sites had significantly fewer residual graft particles. 
 
The effect of particle size on the clinical and histological outcomes of ridge preservation has been scarcely studied or 
reported in the literature. Hoang and Mealey [21] conducted a ridge preservation randomized clinical trial after molar 
extractions. The objectives were to histologically and clinically compare human demineralized bone matrix (DBM) 
putty with one size of bone particles (SPS) to human DBM putty with two different sizes of bone particles (multiple 
particle sizes [MPS]). After 20 weeks of healing, core biopsies were obtained during implant placement and analyzed 
for the percentage area of vital bone, residual graft particles, and non-mineralized structures (connective tissue/other 
non-mineralized tissue [CT]). Changes in alveolar ridge dimensions were also determined. The SPS group had a mean 
of 49% vital bone, 8% residual graft, and 43% CT. The MPS group had 53%, 5%, and 42%, respectively. Patients in 
both groups lost a mean of <1 mm alveolar height on the buccal and lingual aspects and <1.5 mm of total ridge width 
with no reported statistically significant differences. The authors concluded that addition of larger bone particles to 
DBM putty did not offer additional benefit in the preservation of alveolar bone after the extraction of molar teeth. 
However, this conclusion is based on the effect of a mixture of different particle sizes and a small number of patients. 
Most commercially available grafts are categorized in either small or large particle sizes. 
 
The use of large sized particles of anorganic bovine bone matrix resulted in significantly more vital bone formation 
than small particle grafts (26.77% ± 9.63% vs 18.77% ± 4.74%, respectively) in a prospective randomized controlled 
clinical trial of bilateral sinus augmentations [22]. While the histomorphometric results of this study indicated a 
statistically significant increase in vital bone formation when the larger particle size was used, these findings were 
not shown in a previous maxillary sinus augmentation study where there was not a statistically significant difference 
in the percentage of new vital bone formation [23]. The authors related the difference between studies to the small 
sample size included in both (<15 patients). Due to the conflicting information and paucity of the literature on this 
topic, this proposed study will help shed the light on the influence of bone graft particle size on the amount of new 
bone formation in the most common bone defect in the oral cavity, i.e. the extraction socket, after ridge preservation.  
 
 

 
 
3. Objectives/Specific Aims 
 
The aim of the study is to clinically and histologically analyze the amount of the bone gained after ridge preservation 
procedures performed using small (250-1000μm) versus large (1000-2000μm) particle size bone cortico-cancellous 
allograft (MaxxeusTM Dental, Community Tissue Services, Kettering, OH) at time of implant placement, 3 months 
following surgical intervention. 
 
Specific objectives include: 
A. To compare the bone quantity (bucco-lingual ridge width) between the two bone allograft particle sizes by direct 
clinical measurements 
B. To compare the bone quantity (bucco-lingual ridge width and apico-coronal ridge height) between the two bone 
allograft particle sizes by 3-dimensional radiographic measurements (CBCT scan) 
C. To evaluate the quality of bone regenerated with the use of the two bone allograft particle sizes via histological 
and histomorphometric analyses. 
 
Primary outcome: histologic and histomorphometric bone core analyses (from the implant preparation site). 
Secondary outcomes: clinical and radiographic dimensional changes of the edentulous ridges. 
Null Hypothesis: Large-sized particle bone allografts will achieve similar histologic and clinical outcomes as small-
sized particle allografts. 
 
 
4. Materials and Methods 
 
Patients presenting to the graduate periodontal clinic at the University of Alabama at Birmingham School of 
Dentistry will be screened according to the following criteria: 
 
Inclusion criteria 
Exclusion criteria 
• 
English speaking, able to read and understand 
informed consent document  
• 
Less than 18 years old 
• 
Hopeless non-molar tooth or teeth that are planned 
to be replaced with dental implants after ridge 
preservation  
• 
Smokers/tobacco users (>10 cigarettes/day) 
• 
Socket with residual 4 walls following minimally 
invasive tooth extraction (a dehiscence ≤ 3 mm 
may be included)  
• 
Patients with systemic pathologies or conditions 
contraindicating oral surgical procedures or adversel
affecting wound healing as uncontrolled diabetes 
• 
Healthy adjacent teeth must be present and not 
planned for extraction 
• 
Poor compliance risk (i.e., poor oral hygiene, 
history of alcohol or drug abuse) 

 
 
To reject the null hypothesis of equal means with a significance level (alpha) of 0.05 using a two-sided two-sample 
unequal-variance t-test, 22 patients in each group (total of 44) will be required to reach 0.90 statistical power. 
Accounting for 8-patient loss-to-follow up, 50 patients will be enrolled in the study. 
 
All clinical measurements are being taken by one experienced examiner blinded to the randomization process (small 
vs. large particles) before grafting and at time of implant placement. Another examiner will perform the radiographic 
evaluations and will also be blinded to the randomization process. Intra-examiner calibration will be conducted to 
ensure reliability of measuring method. 
 
Screening/baseline visit:  
Patients’ medical history and electronic records will be reviewed. A treatment plan will be developed by an 
interdisciplinary team consisting of a periodontist and a restoring dentist and respective residents. Study examiners 
will conduct clinical and radiographic exams to determine eligibility according to the above criteria. If deemed 
eligible, study visits and objectives will be explained to all participants and IRB approved written informed consent 
will be obtained. 
 
Surgical visit - Study visit 1:  
Patients will be randomized on the day of surgery to receive either Small Particle (SP) (Group 1) or Large Particle 
(LP) bone allograft (Group 2) by permuted block randomization approach to ensure the same number of patients in 
each group, using computer-generated random number list. A course of prophylactic antibiotics will be dispensed at 
the time of surgery (Amoxicillin 2 g or Clindamycin 600 mg, 30 minutes to one hour prior to surgery). The graft 
material utilized for all surgical procedures, for all patients, will be obtained from one manufactured lot, from the 
same donor to account for variation in age, race, gender and related healing potential of different grafts (MaxxeusTM 
Dental, cortico-cancellous FDBA, Community Tissue Services, Kettering, OH). Following local anesthesia, tooth or 
teeth will be gently elevated using a minimally traumatic technique that prevents loss of supporting bone. Socket(s) 
will be curetted, irrigated and inspected following extraction and the presence of intact walls or minimal dehiscence 
(≤3mm) will be verified. The randomized bone allograft (SP or LP) will be hydrated in saline and then placed in the 
socket and covered with a collagen dressing. Vicryl sutures will be used to achieve stability of the collagen dressing 
over the graft material (Fig. 3). Standardized photographs will be taken to document the procedure. 
 
 
 
Figure 3.  
A. Tooth is elevated, B. 
Extracted tooth, C. Socket is 
curetted, 
irrigated 
and 
inspected for presence of bone 
walls D. Graft is placed in the 
socket and covered with a 
collagen dressing and sutures. 
 
 
 
Cone Beam Computed Tomography (CBCT) scan will be taken immediately after socket preservation and will serve 
for baseline measurements. 
Post-surgical antibiotics will be prescribed for the first post-operative week and analgesics will be prescribed as 
necessary.  All subjects will be dispensed Peridex® chlorhexidine mouth rinse and instructed to rinse twice daily for 
two weeks following the surgery, to help guard against possible infection. Verbal and written home care instructions 
will be provided.  
 
Follow-up visit- Study visit 2 
The sutures will be removed after two weeks. Surgical sites will be evaluated for healing status and postoperative 
instructions on resuming oral hygiene measures will be instructed to patients. 
 
 
 

 
 
Bone Biopsy and Implant Placement - Study visit 3 
Three months’ post-socket grafting, a second CBCT scan will be taken to evaluate the success of the grafting 
procedures and to plan the optimal implant position. The site(s) will be exposed for surgical placement of the 
implant(s). After exposure of the healed edentulous ridge, the implant sites will be located with the use of the surgical 
stent (prepared by the restoring dentist) and the ridge width will be measured at the crest and 4 mm apical to the crest 
with the same standardized caliper. If ridge width is deemed adequate, a dental implant of appropriate size will be 
placed. Prior to implant placement a bone biopsy will be taken from the implant site using a 2-mm internal diameter 
trephine. The biopsy will be stored in formalin and sent to the UAB Histomorphometry and Molecular Analysis Core 
for histomorphometric analysis.  
 
 
Fig 4.  A. Site after 3 months 
of healing, B. Flap elevation, 
C. Core biopsy trephine, D. 
Implant placement, E. Flap 
replaced and sutured. 
  
 
 
 
 
Histomorphometric Analysis 
Each specimen will be fixated with 10% neutral buffered formalin for 48 hours prior to be dehydrated and embedded 
in methylmethacrylate. It will be ground sectioned at the center of the biopsy in its long axis into 50-70 micron-thick 
sections (Exakt Technologies, Inc., Oklahoma City, OK), and polished with 4000 grit sandpaper and Novus Polish to 
create a surface as smooth as possible. All sections will be stained with Goldner’s Trichrome stain and imaged for 
quantification of bone formation. Histomorphometry will be done using the Bioquant® Image Analysis Software 
(R&M Biometrics, Nashville, TN) by measuring the total surface of vital bone, residual graft particles, organic matrix 
and artifact/air components.  
Corresponding percentages will be calculated for each of these tissues and compared between small and large particle 
grafts for ridge preservation and augmentation separately. These experiments will be conducted at the UAB 
Histomorphometry and Molecular Analysis Core and all measurements made by an experienced blinded lab 
technician. 
 
Clinical and Radiographic Measurements 
Direct measurements (in mm) of the bucco-lingual ridge width will be taken following tooth extraction at the largest 
area of the socket orifice, using a UNC-15 periodontal probe. This measurement will be repeated at time of implant 
placement, 3 months after socket preservation. 
 
Using baseline and implant placement CBCT data, the 2 scans will be superimposed in a virtual implant planning 
software (coDiagnostix) to evaluate 3-D volumetric changes (in cc). In addition, a virtual tooth (planned in optimal 
position at the implant site) will serve as reference point for standardized assessment of 2-dimensional ridge width 
and height changes (in mm) from the time of grafting until time of implant placement.  
 
Statistical Analysis 
To reject the null hypothesis of equal means with a significance level (alpha) of 0.05 using a two-sided two-sample 
unequal-variance t-test, 22 patients in each group (total of 44) will be required to reach 0.90 statistical power. 
Accounting for 8-patient loss-to-follow up, 50 patients will be enrolled in the study. 
A two-sample t-test was conducted to compare the difference between the two groups in terms of new 
bone formation. Both the clinical and the radiographic dimensional changes between the groups were 
evaluated using two-sample t-tests. A paired t-test was used to compare among all subjects the 
radiographic vertical loss at the facial, midline, and lingual of the crest. The correlation between the 
clinical and radiographic changes in width at the crest and the influence of the type of tooth site on the 
radiographic dimensional changes were evaluated with two-sample t-tests. 
 

 
 
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