Clinical Evaluation Of Soft Tissue Closure In Alveolar Ridge Preservation Procedures
Conditions: Alveolar Ridge Preservation
Sponsor: University of Tennessee

 
 
 
TITLE 
Histological evaluation of alveolar ridge preservation using MInerOss® versus Osteogen plug® 
bone graft techniques: clinical study analysis part II. 
 
  
 
 
 
NCT Number: Unassigned 
 
 
 
Date:  February 8, 2019 
 
 
 
 
 
 
 
 

ABSTRACT  
Background: The aim of this histological study was to compare the percentage of hard tissue 
(bone) after 12 -weeks to 20 weeks post-ridge augmentation surgery after using two different 
ridge preservation procedures.  
Methods: Eleven extraction sites were randomly allocated to either group using a computer-
generated randomization assignment software. The groups were: group CCBC, received cortico-
cancellous bone chips (CCBC) mix and a dense polytetrafluoroethylene (dPTFE) barrier membrane; 
and group CPCAC, received type I bovine Achilles tendon collagen plug with bioactive resorbable 
calcium apatite crystals -OsteoGen- (CPCAC). The histomorphometry analyses were done using a 
computer-based image analysis system (IMAGE-J 1.4, National Institute of Health, Bethesda, MD, 
USA) to calculate pixel area of bone tissue and remaining bone graft material. The 
histomorphometry data were analyzed by the Student t test to compare the data from both 
groups. In addition, histological quantitative evaluation was conducted for evidence of presence 
of foreign body reaction in both groups.  Statistical significance was evaluated at p< 0.05. 
Results: There was no statistical significance when comparing percentage of surface area of bone 
for both experimental groups, CCBC and CPCAC. However, there was evidence of foreign body 
reaction in group CPCAC. Conclusion: The sockets that received CPCAC showed less bone 
formation compared to the CCBC group. However, there was no statistically significant difference 
between the experimental groups. In addition, group CPCAC showed more evidence of foreign 
body reaction when compared to group CCBC.  
Keywords: ridge preservation, histomorphometry. Bone graft(s), alveolar bone, osteocyte(s), 
osteoblast(s), osteoclast(s), collagen(s). 

  
Introduction  
Ridge dimensions preservation after tooth extraction is critical to success of dental implant 
placement.1 Ridge preservation procedures are also necessary for esthetic purposes. Even if an 
implant is not planned to be placed in the site, the healed site will be more aesthetic for the final 
restorative plan.2 
Following tooth extraction, the alveolar ridge undergoes resorption and  exhibits a wide range of 
dimensional changes.3, 4 The soft and hard tissue healing within the extraction sockets following 
tooth removal was studied by histologic and clinical evaluations.4, 5In this study, healing of the 
extraction socket involved a series of events, including the formation of a coagulum that was 
replaced with a connective tissue matrix: after 1 month, woven bone filled the extraction socket; 
a cortical ridge, including woven and lamellar bone, was observed after 3 months. Subsequently, 
the woven bone was gradually replaced with lamellar bone and marrow.6 According to Tan et al. 
(2012), extraction without ridge preservation can result in a mean height loss of 1.24 mm and 
mean width reduction of 3.79 mm. 7 If the ridge is severely resorbed, the dimension loss may 
prevent implant placement in the ideal restoratively driven position.  
Also, Avila-Ortiz et al. (2014), 1 demonstrated that ridge preservation procedures show beneficial 
effect on reducing resorption by an average of 1.89 mm in the buccal-lingual width and 2.07 mm 
in the mid-buccal height when compared to no ridge preservation. Anatomic concerns of the 
maxillary sinus and the mandibular nerve make implant placement precarious at times, limiting 
the general dentist’s desire to place implants in compromised situations. Therefore, considering 

that more than 45 million teeth are extracted annually in the United States, socket grafting must 
become a routine procedure. 8 
Wound healing can be described as a race between various cells, like pluripotent, osteogenic, 
epithelial, fibroblasts cells to the healing site. The epithelium invagination can compromise the use 
of the socket grafting technique, so the graft material must be shielded from the epithelial 
advancement. The socket preservation procedures are centered on the migration of pluripotent 
and osteogenic cells from the periosteum and alveolar bone to the extraction site while at the 
same time excluding epithelial cells and fibroblasts from infiltrating and potentially disrupting new 
bone formation.2, 9 This tissue exclusion process is accomplished using resorbable or non-
resorbable barrier membranes. it is critical that either resorbable or non-resorbable membrane 
extend at least 2.0 mm beyond the facial and lingual defect to avoid premature bone exposure. 
The non-resorbable barrier membrane can be removed 4-6 weeks after placement, but it requires 
an extra patient visit. If the membrane is prematurely lost, the prognosis becomes compromised 
due to invagination of the epithelium cells into the grafted site or infection. In addition, a 
resorbable membrane must be a long-lasting resorbable membrane to contain the bone graft 
particulates in the extraction site.1 
To achieve these goals a variety of materials and techniques are commonly used including 
autogenous tissues, allografts, alloplasts, and xenografts. Allograft and Xenograft materials have 
gained recognition because they do not require a second surgical site and have slower resorption 
rates when compared to some materials and hence can maintain dimensional stability of the ridge. 
1, 10 Freeze-dried bone allograft (FDBA) is an alternative to alloplasts. The performance of the FDBA 
is similarly to autogenous grafts, which are the gold standard for bone graft, and has out-

performed alloplastic materials regarding dimensional stability and new bone formation. 11, 12 
Benefits of FDBA also include low-cost, unlimited supply, and lack of a secondary surgical site. 11 
FDBA has is osteoconductive, and therefore serves as a scaffold to permit capillary proliferation 
and migration of host osteoprogenitor cells to initiate the process of new bone formation, In this 
process, host cells will slowly resorb the residual graft particles as new bone is forming.13 14 Ideally, 
a graft material would provide enough resistance to resorption to maintain dimensional stability 
while simultaneously permitting adequate proliferation of blood vessels and migration of host cells 
for new bone formation. 11 
Cortical and cancellous FDBA are available for use in ridge preservation procedures. The healing 
process after grafting procedures with cortical bone is different compared with cancellous bone. 
11 Cortical allografts have been indicated to have slower rate of resorption by the host compared 
with cancellous allografts. 15 Others have found a cancellous allograft to be beneficial over a 
cortical allograft in that the lower density of cancellous bone offers a greater surface area for more 
rapid revascularization and cell proliferation, then providing faster healing.16 However, an animal 
study showed no difference in healing patterns and new bone formation when comparing cortical 
with cancellous grafts. 17 In human study Eskow & Mealey (2014)18  showed similar new bone 
formation when comparing cortical and cancellous FDBA in ridge preservation. Also Demetter, 
Calahan & Mealey (2017)11  compared a 50%:50% of cortico:cancellous allograft to 100% cortical 
allograft and 100% cancellous allograft when used in alveolar ridge preservation in non-molar 
teeth sites. The histomorphometric analysis showed no significant differences among groups 
regarding percentage of vital bone or CT. 

Placing a collagen-based clotting material, also called collagen plug, such as a 100% collagen plug, 
is not considered a simple procedure and won’t preserve the ridge in the edentulous site due to it 
resorbing in less than 2 weeks and not providing sufficient scaffolding for new bone formation. 2 
The OsteoGenR® nonceramic bone graft with bovine Achilles tendon collagen contains crystals 
inside of the collagen matrix and therefore cannot wash out after placement, as it happens with 
particulate graft materials. 19, 20 This feature allows the use of this material as a plug, without the 
need to add a separate membrane over the site.  OsteoGen® is highly hydrophilic and has been 
used as a particulate graft material since 1984. It shows documented clinical success when used 
for prior to implant placement in periodontal procedures. 20, 21 OsteoGen® strips were cleared by 
the FDA in 2009 and, more recently,  OsteoGen® plugs  were introduced to address the grafting 
needs of ridge preservation procedures.  
The OsteoGen® plug is radiolucent, on the radiograph, when placed in the socket after the 
extraction and as the crystals are resorbed and replaced by host bone, the site gradually becomes 
radiographically radiopaque. The collagen component promotes keratinized tissue coverage while 
the graft component promotes new bone formation.2 
Clinical case studies have been reported in the use of OsteoGen® plugs for ridge preservation.2 To 
date, and to the best knowledge of the authors, no histological studies have compared FDBA 
allograft with OsteoGen® plug in alveolar ridge preservation after tooth extraction. Therefore, the 
purpose of this study is to compare bone healing after the use of FDBA allograft with a non-
resorbable membrane to OsteoGen® plug alone in alveolar ridge preservation procedures. The 
primary outcome of the current study is to histologically evaluate bone formation in the two 
groups. The secondary outcome is to evaluate the foreign body reaction on each of the groups. 

 
Materials and Methods 
The present histomorphological study is part II of a previously conducted clinical study on wound 
closure after the use of the same experimental groups described below. The part I of this study 
had 17 patients. Of those, 11 were used for the present histomorphometry study.  
 
 In the present study, the samples were collected from study part I to conduct histomorphometric 
analysis. This study had 2 experimental groups. The groups were: 
 
Experimental group (CCBC) 
Exodontia was conducted as part of the patient’s treatment plan. After extraction the sockets were 
thoroughly curetted, and a clot was left in place. Cortico-cancellous allograft (MinerOss®, 
BioHorizons, Birmingham, AL, USA) were hydrated with saline solution and compacted into the 
socket up to the level of the alveolar crest. The cortico-cancellous allograft was selected for this 
study due to its confirmed bone formation at the treatment site that would receive 
osseointegrated implants to replace the missing maxillary posterior teeth. Expanded 
polytetrafluoroethylene (ePTFE) (Cytoplast™ TXT-200 non-resorbable high-density) membrane 
were mapped, trimmed, and placed on the surgical site. 4-0 ePTFE (Cytoplast) thread were used 
to conduct a hidden “X” suture. 
 
 

Experimental group (CPCAC) 
Same surgical protocol was conducted as indicated in experimental group CPCAC until exodontia. 
After exodontia and preparation of the socket, the OsteoGen® plug was compacted into the site.  
 
Sample collection phase 
 The patients from the study were monitored during the healing phase. At the time of planned 
implant placement, the samples were collected for histomorphometric analysis. Patients that were 
submitted to mandibular ridge preservation procedures were   scheduled for dental implant 
placement 3-4 months after the ridge preservation procedure had been conducted. Patients that 
were submitted to maxillary ridge preservation procedures were scheduled for dental implant 
placement 5-6 months after the ridge preservation procedure had been conducted. At the implant 
placement visit, the bone sample was collected from the surgical site by a 3.0 mm by 4.0 mm 
trephine and subsequently placed into a 10% buffered formalin solution. An osteotomy site was 
then prepared for the dental implant followed by manufacturer instruction. Flaps were replaced 
and sutured with 4-0 chromic gut.  
 
Histologic Analysis 
The Trephine cores (Figure 1) were submitted for routine formalin-fixed, paraffin-embedded 
histologic studies. All the specimens were decalcified using Decal solution, then processed, 
longitudinally sectioned, and stained with hematoxylin and eosin. Then the microscopic slides 
were scanned and viewed using the software of CaseViewer (2.4.0.119028).    

For histomorphometric analysis for each core sample three components including viable bone, 
residual graft, and connective tissue. Other tissues, such as: vascular tissue, macrophages, and 
adipose tissue were considered. Viable bone was defined by visualization of osteocytes within 
lacunae of the mineralized tissue. Residual bone graft was defined as a mineralized tissue with no 
lacunae. Connective tissue/other was defined as the absence of the above categories and the 
presence of fibrous connective tissue. Once tracing of components was completed, individual 
images for each layer were created and converted to binary images (ImageJ, National Institutes of 
Health, Bethesda, MD). Binary images were then used to calculate the total number of pixels in 
each image. Using the total number of pixels per component and the total number of pixels in all 
three images, the percent of total area occupied by vital and residual graft material, and 
connective tissue/other were calculated. 
 
Statistical analysis 
Student paired ‘t’ test was be conducted to evaluate differences between groups. Student ‘t’ test 
was employed to compare the data in two sets of groups to identify the significance of difference 
in their means (intergroup). Probability values (p) less than 0.05 will be used considered significant 
(Table 3). 
 
 
 
 
 

RESULTS 
Fifteen (15) patients were enrolled from the period of July 2019 to January 2021. The patient 
profile included 7 females and 8 males, with ages ranging from 25 to 75. Two (2) patients were 
withdrawn due to lack of compliance to the scheduled PO visits. An additional two patients were 
withdrawn due to the COVID-19 related school closure, leaving a total of 11 patients who 
completed the study. Of the 11 patients who completed the study, the average age was 55 (range 
27 to 82), consisting of 6 females and 5 males (Table 1).  
 
The patients received a VAS pain rating scale to report their pain levels at 1-, 3- 5- and 7-days post-
operatively. The patient pain levels evaluated by the VAS pain rating scale showed no statistical 
significance between groups I and II. 
 
None of the patients developed any complications and PO infections. A total of 11 extraction sites 
were evaluated, of which 5 patients were in the group CCBC and the remaining patients were in 
the extraction sites were for group CPCAC.   
 
Histologic studies of the group CCBC (CBCT/PTEF, total 5 cases) samples revealed variable viable 
lamellar bone exhibiting focal reversal lines and osteoblastic rimming (except one case which 
showed woven bone) interspersed with fibrous/fibro-vascular connective tissue.  Minimal or no 
inflammation was noted and all the cases except one demonstrated minutes remnants of the graft 
material (Figure 1). In the group CPCAC (the OsteoGen® plug, total 6 samples) a variable amount 
of viable bone, either of lamellar or woven type, intermixed with fibro-vascular connective tissue 

was noted.  Reversal lines and plump osteoblastic rimming were also noted.  The remnants of graft 
material were found in all the cases and 3 out of the 6 cases showed foreign body granulomatous 
inflammation (Figure 2).  
 
Table 2 shows average of the bone area measurements in (pixels) for each of the experimental 
sample of groups CCBC and CPCAC. Table 3 shows the percent bone area measurements for each 
of the experimental sample of groups CCBC and CPCAC. Note a higher average bone presence in 
the histological sections for group CCBC when compared to group CPCAC. The histomorphometric 
results showed an average of 35.13% of bone area in group CPCAC when compared to an average 
of 42.38% group CCBC, but there is no statistically significant difference between the groups. 
 
DISCUSSION 
The primary purpose of ridge preservation is to maintain the ridge dimensions to allow for 
restoratively driven implant placement22, 23. Secondly, ridge preservation procedures may provide 
adequate vital bone for dental implant placement 23. Xenografts and allografts are the two most 
used bone graft materials in dentistry.  Osteogen® plug is a unique product in that it is a synergy 
between both bovine type I bovine Achilles tendon collagen and non-ceramic resorbable calcium 
apatite bone graft crystals. To the knowledge of the authors no study compared the Osteogen plug 
bone formation to the allograft material. 
In this histomorphometric study comparing two different ridge preservation techniques, there 
were no histomorphometric statistically significant differences found between the two 
experimental groups. Primary outcome variable tested was percentage of bony tissue area present 

for both experimental groups. The second outcome variable observed was trace of inflammatory 
reaction for group CPCAC, which may affect the long-term outcome of implant success. 
From the standpoint of implant placement, both experimental groups evaluated in this study 
showed similar results in a short-term success basis, but long-term analysis is necessary in order 
to further evaluate the success of future implants place in the sites using both techniques, 
especially for the technique that included the use of Osteogen® plug, due to it’s histological 
evidence of foreign body reaction in the sites presenting this product. 
Also, the maxillary bone type could be deferent from mandibular24 , so with larger sample group 
the bone formation may be evaluated in each arch. 
The radiograph CBCT can also be used for comparing the dimensional changes before and after 
grafting in the future studies. 
The benefits of using Osteogen® plug is it’s simplified clinical application, no needs of second 
surgery for removal of the membrane, in addition to being cost effective when compared to the 
technique for group CCBC.  
There was a limitation in our study, the sample size became limited due to the COVID-19 pandemic 
which caused three patients to withdraw from the study.  
 
CONCLUSION 
To our knowledge, this is the first study to compare the amount of the bone available between 
use of Osteogen® plug   and the use of MinerOss and Cytoplast membrane for ridge augmentation 
procedures. The current findings indicate that there was no significant difference for the hard 
tissue available for placing the implant 3-5 months after grafting. 

 
 
 

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