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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 13  |  Issue : 1  |  Page : 6-11

The role of decalcified freeze-dried bone allografts in the healing of postoperative osseous defects resulting from cyst enucleation: A pilot study


1 Department of Oral and Maxillofacial Surgery, Ahmedabad Dental College and Hospital, Ahmedabad, Gujarat, India
2 Department of Clinical Pharmacology, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra, India

Date of Submission16-May-2020
Date of Acceptance04-Sep-2020
Date of Web Publication31-Dec-2020

Correspondence Address:
Tejashvini Joshi
Department of Oral and Maxillofacial Surgery, Ahmedabad Dental College and Hospital, Ahmedabad - 382 115, Gujarat
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/IJDS.IJDS_73_20

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  Abstract 


Background: We performed this pilot study to evaluate the osteoinductive potential of decalcified freeze-dried bone allografts (DFDBA) in the healing of postsurgical osseous defects after cyst enucleation through radiographic bone density monitoring over a 6-month period. Materials and Methods: Patients aged between 18 and 70 years of either gender with noninfected odontogenic or nonodontogenic cystic jaw lesions measuring 1–5 cm in size were enrolled and randomly assigned to study group or control group. The study group patients were filled with DFDBA graft in bony defects resulting from the enucleation of the cysts, whereas no filling material was used in the control group. Sutures were removed on the 7th postoperative day and healing was assessed. Further follow-up visits were done at 1, 3, and 6 months. Bone densities were recorded with grayscale histogram using Adobe Photoshop (version CS 5.1) and compared across all follow-ups. Results: A total of 20 patients were enrolled in the study. Both the groups were balanced in terms of the baseline (preoperative) characteristics. There was a significant increase in bone density in the study group as compared to the control group at months 1, 3, and 6 after the surgery. There was an overall percentage increase in bone density (postoperative density as reference) at months 1, 3, and 6 in the study and control groups. However, the increase was significantly greater in the study group as compared to the control group at month 3 and month 6, whereas there was no difference between both the groups at month 1. Conclusion: Our findings suggest the osteoinductive potential of DFDBA in the healing of osseous defects resulting from the enucleation of cysts.

Keywords: Odontogenic cyst, osteoconduction, osteogenesis


How to cite this article:
Joshi T, Vyas N, Shah N, Thaker S, Sanghvi N. The role of decalcified freeze-dried bone allografts in the healing of postoperative osseous defects resulting from cyst enucleation: A pilot study. Indian J Dent Sci 2021;13:6-11

How to cite this URL:
Joshi T, Vyas N, Shah N, Thaker S, Sanghvi N. The role of decalcified freeze-dried bone allografts in the healing of postoperative osseous defects resulting from cyst enucleation: A pilot study. Indian J Dent Sci [serial online] 2021 [cited 2021 Jan 24];13:6-11. Available from: http://www.ijds.in/text.asp?2021/13/1/6/305978




  Introduction Top


Bone grafting is a procedure commonly performed to replace missing bone or to enhance bone formation for bony defects. The aim is to fill the empty space with biological material, which encourages bone reconstruction.[1] Current approaches to bony reconstructive surgery make use of autografts, allografts, and alloplasts. The autograft is graft material obtained from one anatomic site to another within the same subject and remains the gold standard in bone grafting.[2] However, their use is limited by challenges such as lack of sufficient available bone, the need for a second intraoral or extraoral surgical site, and consequent increase in patient inconvenience and morbidity.[3] Alloplasts are synthetic graft materials having some clinical use.[2] The allograft is transferred from a genetically nonidentical member of the same species. Nonrequirement for another donor site, ease of handling, greater yield, reduced cost, lesser inconvenience to patients, and no donor-site morbidity make allogenic bone graft a preferred material for filling bony cavities.[4] Allografts are available in the form of freeze-dried and decalcified freeze-dried bone allografts (DFDBA). DFDBA has osteoinductive and osteoconductive potential and it acts as a space-maintaining and bone growth-promoting agent.[1],[3],[5] Bone grafting is recommended following cyst enucleation to reduce jaw weakness and shorten the period of healing.[6] There is sufficient evidence on the role of DFDBA in maxillofacial deformities and periodontal osseous defects.[7],[8],[9] However, there are limited data on its osteoinductive potential following cyst enucleation in Indian patients. In our setting, enucleated cyst cavities are not routinely treated with bone grafting because most of the patients cannot afford the cost of the graft material. However, the surgical outcomes remain suboptimal in these patients. Therefore, we carried out this pilot study to evaluate the effectiveness of DFDBA in the healing of postsurgical osseous defects after cyst enucleation.


  Materials and Methods Top


Ethics

The study was initiated following ethics committee approval and informed consent from all patients. It has been submitted to the clinical trial registry of India (REF/2020/05/033559).

Study design

This was an open-label, controlled comparative pilot clinical study conducted in the department of oral and maxillofacial surgery of a teaching hospital from January 2013 to December 2014.

Study patients

Patients aged between 18 and 70 years of either gender with noninfected odontogenic or nonodontogenic cystic jaw lesions measuring 1–5 cm in size, fit for surgery as per the American Society of Anesthesiologists Class I and II, willing to give the written informed consent, and ready to come for regular follow-ups were included in the study. Patients who were medically compromised, with the history of allergy or hypersensitivity, infected cystic lesions of the jaw, chronic tobacco chewers, chronic smokers, and any history of substance abuse were excluded from the study.

Study intervention

A total of 20 patients were randomly allocated to the study group or control group based on the allocation list generated from randomization.com. The study group patients were filled with DFDBA graft in bony defects resulting from the enucleation of the cysts, whereas no filling material was used in the control group patients [Flow Chart 1].



Surgical procedure

Extraoral painting, draping, and intraoral irrigation were done. Regional nerve blocks were given using injection lignocaine hydrochloride with adrenaline (1:100,000) for local anesthesia, and hemostasis was achieved with local infiltration. According to the site and size of lesion, the incision was made along the crevicular gingiva and relieving incision in the respective vestibule using no 15 Bard-Parker blade. A trapezoidal mucoperiosteal flap was reflected with a periosteal elevator exposing the surgical site. Deroofing of lesion was done using surgical round bur No. 8 and straight bur No. 702, 703, and bony window was created, if required. After exposure, the cyst was enucleated using Lucas curette [Figure 1]. The cavity was irrigated with betadine and saline. The reapproximation of the flap was done with interrupted sutures using 3–0 silk. Broad-spectrum antibiotics and analgesics were prescribed and instructions to maintain strict oral hygiene were advised.
Figure 1: Enucleation done

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Allograft placement

DFDBA samples were purchased from Tata Memorial Hospital, Mumbai, available in the powder form. The DFDBA was prepared as per the method described by Gajiwala.[10] The DFDBA material was well soaked in saline for 30 min before placement to form a paste-like consistency. The bony defects were filled with bone allograft paste [Figure 2]. A resorbable poly-lactide poly-glycolide membrane of suitable size was then positioned over the grafted defect extending ≥2 mm in all directions onto the sound bone.
Figure 2: Placement of decalcified freeze-dried bone allograft in the bony cavity

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Follow-up visits

Sutures were removed on the 7th postoperative day and healing was assessed. Further follow-up visits were done at 1, 3, and 6 months [Flow Chart 1].

Bone density measurement

The intraoral digital radiographs were taken using radiovisiography (RVG) machine and the densitometric analysis was done on Owandy window software. The screen resolution was 1280 by 768 pixels. Densities of bony defects and the bone formed were recorded using the grayscale histogram. The values were tabulated and evaluated by digital analysis in both groups. Bone density values were recorded preoperatively, immediate postoperatively, at 1, 3, and 6 months after the surgery [Figure 3], [Figure 4], [Figure 5].
Figure 3: Postoperative radiovisiography at 1 month (decalcified freeze-dried bone allograft treated)

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Figure 4: Postoperative radiovisiography at 3 months (decalcified freeze-dried bone allograft treated)

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Figure 5: Postoperative radiovisiography at 6 months (decalcified freeze-dried bone allograft treated)

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The radiographic findings were analyzed both subjectively and using a digital technique to reduce the bias derived from the subjective evaluations. The computer analysis was performed using Adobe Photoshop (version CS 5.1) software to transfer the areas on the radiograph into pixels. Histogram provided bone density values (tonality) in grayscales. Denser parts gave high tonality values. The grayscale values were reported by an independent person to minimize the reporting bias. The values were compared between both the groups across all time points.

Statistical analysis

No formal sample size calculation was done since it was a pilot study. The sample size of 20 was arrived at by considering patient flow in the hospital and the number of patients willing to give their informed consent in a 1-year time period. Continuous variables were presented as mean and standard deviation (SD)/median (range) depending upon the distribution. Categorical variables were presented as actual numbers and proportions. Categorical variables were analyzed using the Chi-square test/Fisher's exact test. Change in bone densities (actual and percentage) at each follow-up was compared between both the groups using unpaired t-test/Mann–Whitney U-test depending upon the distribution, followed by suitable post hoc tests. Change in bone densities at all the follow-up visits was compared using repeated measures ANOVA/Friedman's test as per the distribution, followed by suitable post hoc tests. Change in bone densities at month 6 in both the treatment groups was compared using ANCOVA with age, gender, baseline bone density, and treatment groups as covariates. All analyses were done at 5% significance using GraphPad InStat 3.0 for Windows, SPSS 20.0 (Chicago, IL, USA) and STATA 11.0 (TEXAS) for Windows.


  Results Top


The study included 20 patients who were to undergo enucleation of the cyst under local anesthesia. The patients were randomly divided equally into study and control groups.

Baseline characteristics

Out of the 20 patients enrolled, 14 (70%) were male and 6 (30%) were female. Both the groups were comparable in terms of age and gender distribution. Of the 20 patients, four patients had lesion in the mandible and 16 had lesion in the maxilla. In the study group, one patient had lesion in the mandible and nine patients had lesion in the maxilla, whereas in the control group, three patients had lesion in the mandible and seven patients had lesion in the maxilla. A total of eight patients in the study group had cysts in relation to the incisor, while one each in both premolar and molar, whereas all the patients in the control group had cyst located in the incisors [Table 1]. Both the groups were also comparable in terms of the size of the cystic lesion (sum of the largest diameters) and bone density at the baseline and immediately postsurgery. (unpaired t-test; P = 0.27, 0.34, and 0.19, respectively) [Table 2].
Table 1: Comparison of baseline characteristics

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Table 2: Comparison of size of the lesion at each visit (cm)

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Comparison of bone densities between the study and control groups

The overall preoperative bone density (mean [SD]) across cases and controls was 47.35 (26) which increased to 95.30 (41.66) on grayscale.

There was a significant increase in bone densities at month 1, month 3, and month 6 after the surgery in both the groups. (repeated measures ANOVA with Tukey–Kramer multiple comparison test; P < 0.0001 each).

However, the increase was significantly greater in the study group as compared to the control group at months 1, 3, and 6 after the surgery. (unpaired t-test Welch corrected; P = 0.02, 0.001, and 0.002, respectively).

The change in bone density was significantly higher in the test group as compared to the control group at month 6 as compared to baseline (ANCOVA; P = 0.00001) [Table 3].
Table 3: Comparison of bone densities at each visit

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There was an overall percentage increase in bone density (postoperative density as reference) at months 1, 3, and 6 in the study and control groups. (repeated measures ANOVA with Tukey–Kramer multiple comparison test; P < 0.0001 each). However, the increase was significantly greater in the study group as compared to the control group at month 3 and month 6, whereas there was no difference between both the groups at month 1. (unpaired t-test Welch corrected; P = 0.03, 0.04, and 0.19, respectively) [Table 4].
Table 4: Comparison of the percentage change in bone density at each visit

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Overall, there was a significant increase in (mean and percentage) bone density at month 6 from the preoperative bone density in the study group relative to the control group (ANCOVA; P = 0.001, 0.002 each).


  Discussion Top


Bone is a dynamic tissue and has unique properties to regenerate, remodel, and replace itself. These unique properties make bone grafting a gold standard in filling bony defects after craniofacial surgeries including the enucleation of cysts.[11],[12] Bone grafting is routinely advocated after conventional enucleation of large cysts in order to avoid facial deformities and other complications.[13]

The formation of bone following bone grafting is a combination of three processes: osteogenesis, osteoconduction, and osteoinduction. Osteogenesis requires surviving osteoblasts and osteoblast precursors to repopulate the graft and to form new bone. Osteoconduction involves the replacement of the graft by osteoprogenitor cells from the host. Osteoinduction requires coordination between bone morphogenetic proteins (BMP) and mesenchymal cells to form cartilage and bone.[1] The choice of suitable graft material to replace a bone is a big challenge for a maxillofacial surgeon.[11] Recently, a lot of attention is diverted to allografts, vascularized grafts, bone substitutes, and osteoinductive factors in grafting applications owing to the challenges associated with autografts.[12] The concerns with allografts are the risk of transmission of infectious disease such as human acquired immunodeficiency syndrome and possibility of rejection by the host. The amount of time for revascularization of the allograft is longer than that with reconstruction with autogenous bone owing to a better immunologic response with the later. However, freezing and lyophilization reduce the chances of infection and preserve properties to improve the chance of graft incorporation.[4]

The high osteogenic potential of DFDBA could be attributed to the presence of BMP, a protein or a derivative of protein family which is bound to collagen. The BMP hypothesis proposed by Urist and Strates suggested that BMPs are released from a supramolecular aggregate of noncollagenous proteins in the process of normal bone turnover or in response to injury or transplantation.[14],[15] Demineralization of allograft releases the mineral which insulates the BMP and prevents its migration from the matrix to the proliferating mesenchymal cells. The surface charge of DFDBA is highly negative as compared to the freeze-dried bone graft which contributes to the greater osteogenic potential of the former.[16]

In the present study, DFDBA was chosen to fill the defects created subsequent to the enucleation of cystic lesions affecting the maxilla and mandible owing to their osteoinductive potential and proven safety. The aim of the present study was a radiographical evaluation of the effect of DFDBA on the healing of bony defects of the jaws. The bony defects were filled with DFDBA and RVG were taken at month 1, 3, and 6 months after surgery. These postoperative radiographs were compared with the follow-up radiographs using grayscale histogram for bone density.[16],[17]

Digital radiographic techniques are superior and widely used in conventional radiographic techniques. The reasons behind the growing popularity of digital radiographic techniques are fixed-dose latitude, fixed nonlinear grayscale response, and limited potential for reducing the dose to the patient. Apart from these, the images can be changed, long-term storage. Conventional radiographic techniques are not compatible with the picture archiving and communication systems.

We observed a consistent increase in bone density from months 1 to 6 (in terms of grayscale histogram) in the study group, whereas the increase in bone density was minimal in the control group. Our findings are consistent with Guillemin et al. and Jaiswal et al. who observed a significant increase in bone density as early at 90 days till day 180 in the DFDBA group, whereas no significant difference was observed in the nongrafted site from 90 to 180 days.[18],[19]

In the study group, we found a statistically significant change in the bone density and observed almost 43%, 81%, and 94% gain on 1st, 3rd, and 6th month postoperative follow-ups respectively. On the other hand, the control group showed almost 21%, 35%, and 55% gain on the respective follow-up periods. These results indicate that the new bone formation was ensured in the study group within 1 month of graft placement compared to the control group. Our findings corroborate with Narang et al.[20] and Lee et al.[21] who concluded from their studies that decalcified allogenic grafts show new bone formation within 4 weeks period.

We observed a consistent increase in bone density with maximum increase in 1st month postoperative radiographs (from 52.94 to 121.23). This initial rise in bone density observed in the present study simulates the results of Mulliken et al. who concluded from their study that DFDBA triggers bone healing by induced osteogenesis bypassing the resorption seen with the healing of other grafts or nongrafted defects.[7]

We observed no signs of implant rejection such as discharge, extrusion, and tissue dehiscence in the study group. No postsurgical complications such as pain, infection, and bleeding were encountered in either group. These findings corroborate with Mishra et al. and Jaiswal et al.[11],[18]

Our study findings need to be interpreted in-light of the following limitations. First, this was a pilot study with a very limited sample size and requires validation of the observations through a large-scale randomized controlled clinical trial. Second, we did not confirm the osteoinductive potential of DFDBA through histomorphometric analysis. Second, we did not confirm our RVG findings of new bone formation with computerized tomography scan evaluation.


  Conclusion Top


Overall, our findings suggest the osteoinductive potential of DFDBA in osseous defects following enucleation of cysts. The bone formation following DFDBA starts within 1 month and increases consistently till month 6 with no major complications. However, future large-scale randomized controlled clinical trials with head to head comparison between various graft materials and/meta-analyses will confirm their role in the healing of the osseous defects and will aid the maxillofacial surgeons in the selection of appropriate graft material.

Acknowledgments

We would like to thank Dr. Mihir Shah, Dean, for allowing us to carry out this research in the institute and all the patients for participating in the study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Bodner L. Effect of decalcified freezedried bone allograft on the healing of jaw defects after cyst enucleation. J Oral Maxillofac Surg 1996;54:1282-6.  Back to cited text no. 1
    
2.
Nascimento C, Issa J, Oliveira R, Iyomasa M, Siéssere S, Regalo S. Biomaterials applied to the bone healing process. Int J Morphol 2007;25:839-46.  Back to cited text no. 2
    
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Elsalanty ME, Genecov DG. Bone grafts in craniofacial surgery. Craniomaxillofac Trauma Reconstr 2009;2:125-34.  Back to cited text no. 3
    
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Gomes KU, Carlini JL, Biron C, Rapoport A, Dedivitis RA. Use of allogeneic bone graft in maxillary reconstruction for installation of dental implants. J Oral Maxillofac Surg 2008;66:2335-8.  Back to cited text no. 4
    
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Froum S, Cho SC, Rosenberg E, Rohrer M, Tarnow D. Histological comparison of healing extraction sockets implanted with bioactive glass or demineralized freeze-dried bone allograft: A pilot study. J Periodontol 2002;73:94-102.  Back to cited text no. 5
    
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Chiapasco M, Rossi A, Motta JJ, Crescentini M. Spontaneous bone regeneration after enucleation of large mandibular cysts: A radiographic computed analysis of 27 consecutive cases. J Oral Maxillofac Surg 2000;58:942-8.  Back to cited text no. 6
    
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Mulliken JB, Glowacki J, Kaban LB, Folkman J, Murray JE. Use of demineralized allogeneic bone implants for the correction of maxillocraniofacial deformities. Ann Surg 1981;194:366-72.  Back to cited text no. 7
    
8.
Altiere ET, Reeve CM, Sheridan PJ. Lyophilized bone allografts in periodontal intraosseous defects. J Periodontol 1979;50:510-9.  Back to cited text no. 8
    
9.
Mellonig JT. Autogenous and allogeneic bone grafts in periodontal therapy. Crit Rev Oral Biol Med 1992;3:333-52.  Back to cited text no. 9
    
10.
Gajiwala AL. Setting up a Tissue Bank in India: The Tata Memorial Hospital experience. Cell Tissue Bank 2003;4:193-201.  Back to cited text no. 10
    
11.
Mishra S, Singh RK, Mohammad S, Pradhan R, Pal US. A comparative evaluation of decalcified freeze dried bone allograft, hydroxyapatite and their combination in osseous defects of the jaws. J Maxillofac Oral Surg 2010;9:236-40.  Back to cited text no. 11
    
12.
Oppenheimer AJ, Tong L, Buchman SR. Craniofacial bone grafting: Wolff's law revisited. Craniomaxillofac Trauma Reconstr 2008;1:49-61.  Back to cited text no. 12
    
13.
Das BK, Iqbal MM, Islam E, Rahman QB, Ahammed M, Molla MR. Allogenic bone grafting after cyst enucleation. Int J Oral Maxillofac Surg 2007;36:1056.  Back to cited text no. 13
    
14.
Urist MR, Strates BS. Bone formation in implants of partially and wholly demineralized bone matrix. Clin Orthop 1970;71:271-8.  Back to cited text no. 14
    
15.
Zhang M, Powers RM Jr., Wolfinbarger L Jr. Effect (s) of the demineralization process on the osteoinductivity of demineralized bone matrix. J Periodontol 1997;68:1085-92.  Back to cited text no. 15
    
16.
Mellonig JT, Bowers GM, Bailey RC. Comparison of bone graft materials. Part I. New bone formation with autografts and allografts determined by Strontium-85. J Periodontol 1981;52:291-6.  Back to cited text no. 16
    
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Marx RE. Bone and bone graft healing. Oral Maxillofac Surg Clin North Am 2007;19:455-66, v.  Back to cited text no. 17
    
18.
Jaiswal Y, Kumar S, Mishra V, Bansal P, Anand KR, Singh S. Efficacy of decalcified freeze-dried bone allograft in the regeneration of small osseous defect: A comparative study. Natl J Maxillofac Surg 2017;8:143-8.  Back to cited text no. 18
[PUBMED]  [Full text]  
19.
Guillemin MR, Mellonig JT, Brunsvold MA, Steffensen B. Healing in periodontal defects treated by decalcified freeze-dried bone allografts in combination with ePTFE membranes. Assessment by computerized densitometric analysis. J Clin Periodontol 1993;20:520-7.  Back to cited text no. 19
    
20.
Narang R, Ruben MP, Harris MH, Wells H. Improved healing of experimental defects in the canine mandible by grafts of decalcified allogenic bone. Oral Surg Oral Med Oral Pathol 1970;30:142-50.  Back to cited text no. 20
    
21.
Lee DW, Koo KT, Seol YJ, Lee YM, Ku Y, Rhyu IC, et al. Bone regeneration effects of human allogenous bone substitutes: A preliminary study. J Periodontal Implant Sci 2010;40:132-8.  Back to cited text no. 21
    


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