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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 13  |  Issue : 5  |  Page : 772-777  

Utility of Chitra–HASi granules in cystic defects of the maxillofacial region: A pilot study


1 Department of Oral and Maxillofacial Surgery, Meenakshi Ammal Dental College and Hospital; Meenakshi Cleft and Craniofacial Centre, Meenakshi Academy of Higher Education and Research (Deemed-to-be University), Chennai, Tamil Nadu, India
2 Department of Oral and Maxillofacial Surgery, Meenakshi Ammal Dental College and Hospital, Chennai, Tamil Nadu; Department of Oral and Maxillofacial Surgery, Ex-servicemen Contributory Health Scheme (ECHS), Sagar, Madhya Pradesh, India
3 Department of Oral Pathology, Sree Anjaneya Institute of Dental Sciences, Atholi, Calicut, Kerala, India
4 Department of Oral and Maxillofacial Surgery, Meenakshi Ammal Dental College and Hospital, Chennai, Tamil Nadu, India
5 Meenakshi Cleft and Craniofacial Centre, Meenakshi Academy of Higher Education and Research (Deemed-to-be University), Chennai, Tamil Nadu, India
6 Division of Bioceramics, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India

Date of Submission08-Dec-2020
Date of Acceptance16-Dec-2020
Date of Web Publication05-Jun-2021

Correspondence Address:
Manikandhan Ramanathan
Department of Oral and Maxillofacial Surgery, Meenakshi Ammal Dental College and Hospital, #23, Alapakkam Main Road, Maduravoyal, Chennai . 600 095, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jpbs.JPBS_816_20

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   Abstract 


Background: Cystic defects that are critical sized or larger require bone replacement strategies. However, due to inherent disadvantages of the various types of grafts, none of the available materials are best suited for these defects. Among the alloplastic materials, hydroxyapatite (HA)-based grafts are the most popular, due to their osteoconductive nature and resemblance to mineral bone. The aim of the study was to assess the utility of the novel material “Chitra-HASi” as a bone substitute in the maxillofacial region. Materials and Methods: In a single-arm, prospective study, patients with radicular and dentigerous cysts were included and the minimum defect size was standardized at 20 × 20 mm or above. The Chitra–HASi material was developed by a wet precipitation technique and adopted for use following multiple in vitro and in vivo studies, confirming its safety and biocompatibility profile. All cysts underwent enucleation, followed by peripheral ostectomy and apicectomy of the teeth involved. The HASi graft was packed inside the cystic defect in a granular form and covered with a mucoperiosteal flap. Panoramic radiographs were taken preoperatively and at 3, 6, and 12 months postoperatively. Results: Twenty-three patients were included in the study, of which only 10 patients could be followed up for 12 months after graft placement. The mean preoperative bone density was found to be 14.9% ± 4.97 (standard deviation), whereas the postoperative 3-month, 6-month, and 12-month densities had a mean difference of −11.3%, −22.9%, and −37.3%, respectively, and the differences were statistically significant. Minor complications such as sinus formation (n = 7) and extrusion of granules (n = 4) were noted, which were managed conservatively. Only two patients required graft removal secondary to infection, leading to a persistent sinus tract. Conclusion: The results of the study suggest that Chitra–HASi granules show potential as an alternative to other bone substitutes. The addition of silica to the porous HA material offers superior strength characteristics and needs long-term evaluation to assess its stability in large cystic defects.

Keywords: Bone density, bone regeneration, Chitra–HASi granules, cystic defects


How to cite this article:
Ramanathan M, Tiwari RK, Mohan SP, Shankar DP, Bagadia RK, Harikrishna Varma P R, Fernandez FB, Babu S S. Utility of Chitra–HASi granules in cystic defects of the maxillofacial region: A pilot study. J Pharm Bioall Sci 2021;13, Suppl S1:772-7

How to cite this URL:
Ramanathan M, Tiwari RK, Mohan SP, Shankar DP, Bagadia RK, Harikrishna Varma P R, Fernandez FB, Babu S S. Utility of Chitra–HASi granules in cystic defects of the maxillofacial region: A pilot study. J Pharm Bioall Sci [serial online] 2021 [cited 2021 Jul 29];13, Suppl S1:772-7. Available from: https://www.jpbsonline.org/text.asp?2021/13/5/772/317705




   Introduction Top


Bone is a metabolically active tissue that contains a variety of cells interspersed in a complex system. The unique feature of its structure is the extracellular matrix, which consists of collagen and a mineral phase of calcium phosphate crystals, which is primarily composed of hydroxyapatite (HA). Due to its inherently dynamic nature, bone has the capacity to regenerate in small quantities.[1] However, certain critical-sized defects that are created secondary to trauma, pathology, or infection require bone replacement strategies to heal adequately and retain their original strength.[2] The replacement may be in the form of an osteoinductive, osteoconductive, or osteogenic material. Autografts are considered “ideal,” as they satisfy all of the above criteria and also reduce the risk of foreign body reactions. However, the disadvantages of a second surgical site, donor site morbidity, and inadequate tissue disfavor its use in cases with larger requirements. Allografts and xenografts offer nonautologous options; however, the lack of cost-effectiveness and availability, in addition to adverse host responses, has precluded their utilization in sizeable bone defects.[3],[4]

Calcium orthophosphate compounds, otherwise known as bioceramics, are the preferred synthetic bone grafts due to their resemblance to the mineral phase of bone. HA is the only one among these which can be derived by precipitation and solid-state reactions (sintering).[5] A wide spectrum of apatites have been developed to enhance their porosity, bioactivity, mechanical properties, biodegradation rate, osteoinductivity, and osteoconductivity to match native tissue.[6] Studies have shown that HA with a lower granule size and greater percentage of porosities portends better bony ingrowth and strength.[7],[8],[9],[10] Chitra–HASi is a new-generation bone graft material that is developed based on HA produced via a solid phase reaction of calcium phosphate and silicate ingredients, ensuring that the final product has silica, calcium, and phosphate.

To demonstrate preclinical efficacy of this novel material, a robust segmental defect model in a goat (femoral diaphyseal segmental defect) was chosen for HASi application. A critical-sized defect of 2 cm was generated and remedied using triphasic ceramic-coated hydroxyapatite (HASi) in conjunction with autologous stem cells. Lamellar organization of newly formed bone was visualized throughout the defect in cell-seeded constructs.[11] Histological evaluation indicated that new bone was reorganized, mineralized, and attained native contour and appearance within 1 year.[12] Based on these results, the present study was designed to assess the use of Chitra–HASi granules as a synthetic bone graft material in cysts of the jaws following enucleation.


   Materials and Methods Top


Synthesis of triphasic calcium phosphosilicate (HASi) bioceramics

HA powder is synthesized by a wet precipitation technique involving calcium nitrate and ammonium dihydrogen phosphate in stoichiometric proportion at pH 11 and 80°C. Precipitated hydroxyapatite powder is freeze-dried and washed with distilled water. It is meshed to generate less than 125 micron free flowing powder. This is compacted with a pore former and compressed to form desired shapes or placed in desired molds. This is biscuit fired at 300°C for binder removal. Forms are sintered at 1200°C to generate porous ceramics. Silica coating was applied by treating forms with a silica sol, removal of excess sol, dried, and sintered at 1200°C to form HASi.[13],[14]

Characterization

X-ray diffraction

Ceramic sample powders of HASi were scanned between 20° and 40° 2θ at a rate of 2° min−1 under a step size of 0.02° using CuKα radiation at a voltage of 40KV and current strength of 30 mA (Bruker). Phase identification was carried out with comparison of data with JCPDS files.

Fourier transform infrared spectroscopy

Sample powders were pelleted with KBr powder and analyzed on a Thermo Nicolet 5700 spectrometer. Spectra were collected using (DRIFT) diffuse reflectance mode resolution of 4 cm−1 and scanned between 400 and 4000 cm−1 wave number range and with an average scan of 200.

Scanning electron microscopy

Material was stuck to the stub with conducting tape and sputter coated with gold (Hitachi E1010). The morphology and microstructure of HASi granules were examined by an environmental electron microscope (FEI-Quanta 200, Germany) [Figure 1].
Figure 1: Scanning electron microscope micrographs show porous granules with rough surfaces. The pores were found to be open and comprising uniformly distributed large cavities, in the 500 μm range, and fine grains, in the nanometer range. The homogenous distribution of composite phases are evident from the micrographs

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Design of the study and participants

The study was a prospective, single-arm study of Chitra–HASi granules for bone regeneration in cystic defects of the maxillofacial region. It was carried out in Meenakshi Ammal Dental College and Hospital, Chennai, Tamil Nadu, India from November 2014 to November 2016. A total of 23 patients were included after obtaining informed consent. Inclusion criteria were based on patients diagnosed with a radicular or dentigerous cyst, treated by enucleation, with a defect diameter of 2 cm or more, and consenting to the study. Those excluded were patients with bleeding disorders, coexisting bone pathologies or morphological bone conditions, history of systemic treatment contraindicating surgery (such as CT/RT), defects that involved the maxillary sinus or inferior alveolar nerve, and recurrent cysts. A panoramic radiograph was taken preoperatively and at 3, 6, and 12 months postoperatively for bone density assessment. Ethical committee clearance was obtained from the Institutional Review Board of Meenakshi Ammal Dental College (Protocol number MADC/IRB/2015/108).

Surgical procedure

All the surgical procedures were performed by a single surgeon (M. R.) [Figure 2]. The surgery was performed under local/general anesthesia. Crevicular incisions with lateral releasing incisions were made for all the cases to obtain adequate exposure of the cystic lesion. A mucoperiosteal flap was reflected and the cyst lining was exposed. Following enucleation of the cyst, peripheral ostectomy was done wherever indicated. Apicoectomy was undertaken in all the teeth associated with the cyst, followed by root-end filling using MTA. The HA block (Chitra–HASi granules) was commercially available in sizes 10 mm × 10 mm × 20 mm and 5 mm × 5 mm × 5 mm for clinical use [Figure 3]; it was then crushed to a granular form after soakage in normal saline. The material was then packed tightly within the cystic cavity to completely fill the bony defect. Closure was done using 4-0 Vicryl and postoperative instructions included maintenance of good oral hygiene. The enucleated cyst along with its contents was sent to the Department of Oral Pathology and Microbiology for histopathological examination.
Figure 2: The surgical procedure involving cyst enucleation and placement of HASi granules in the cystic defect

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Figure 3: HASi blocks

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   Results Top


A total of 23 patients were included in the study, which comprised 16 males and 7 females, with a mean age of 33.39 years (range, 16–64 years). All patients underwent cyst enucleation with peripheral ostectomy and apicoectomy of involved tooth/teeth followed by filling of defect using Chitra–HASi granules. The minimum size of the cystic defect considered for grafting was 20 mm × 20 mm and size of the granules ranged from 0.5 up to 2 mm. The data were analyzed using ANOVA test, and the statistical analysis was performed using SPSS software (version 14.2, BioGraft HABG Active IFGL Refractories Ltd., Unit 1, Sector A, Kalunga Insdustrial Estate, Kalunga - 770031 Sundargarh, Odisha, India). P < 0.05 was considered statistically significant.

Preoperative assessment

The radiological assessment for all the cases was done by the same author (R. T.). Of the 23 patients who were included in the study, 18 were diagnosed to have a radicular cyst, whereas the remaining 5 patients had dentigerous cysts. Only cysts with a critical size bone defect of maxilla or mandible >20 mm × 20 mm were included. The average dimension of the cysts was 28.33 mm × 20.59 mm.

Postoperative assessment

Bone density was assessed using panoramic radiographs taken preoperatively and postoperatively at 3, 6, and 12 months, and the analysis was done using SIDEXIS XG software [Figure 4]. Of the 23 patients who participated in the study, only 10 patients were followed up for a period of 12 months. The remaining 13 patients could not be evaluated at the intended intervals due to lack of patient compliance or were lost to follow-up.
Figure 4: A maxillary cyst in the left upper anterior region assessed using panoramic radiographs preoperative, and at 3, 6 and 12 months postoperative

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Comparison of bone density profile

The mean preoperative bone density was calculated to be 14.9% ± 4.97 (standard deviation [SD]). The 3-month, 6-month, and 12-month comparative postoperative densities had a mean difference of −11.3%, −22.9%, and −37.3%, respectively.

The average 3-month postoperative bone density was 26.2% ± 4.18 (SD). A statistically significant difference was observed between the 3-month postoperative values compared to preoperative and 6-month and 12-month postoperative values. There was a mean difference of 11.3%, −11.6%, and −26%, respectively.

The mean bone density measured 6 months postoperatively was 37.8% ± 4.68 (SD). The mean difference of 22.9%, 11.6%, and −14.4% was observed when compared with densities measured preoperatively and postoperatively at 3 months and 12 months, respectively, also demonstrating a statistically significant difference between the groups.

The overall mean bone density measured 12 months postoperatively was 52.2% ± 7.33(SD). On comparison with the values obtained preoperatively and 3 months and 6 months postoperatively, a significant difference was observed, with a mean difference of 37.3%, 26%, and 14.4%, respectively.

A steady increase in bone density was seen in all the ten patients who were followed up for 12 months. To determine if the bone density at the grafted site is similar to that of sound bone, 5 patients were randomly selected for a comparison analysis. It was noted that the mean density after 12 months on the grafted side was 52.2% ± 7.3 (SD), whereas that of the nonoperated contralateral side was 52.75% ± 10.3 (SD).

Complications

Local inflammation and swelling

None of the patients participating in the study had any signs of adverse local reactions or inflammation (redness, pain, swelling, and loss of function).

Sinus formation

Formation of a sinus opening was observed in four out of the 23 patients. The patients were given oral antibiotics based on the culture and sensitivity report and complete remission of the infection was seen in 2 out of four patients, with good uptake of Chitra–HASi graft material. In the remaining two patients, the sinus tract was persistent and required removal of the graft, along with wound debridement and primary closure.

Extrusion of Chitra–HASi granules

A total of 7 patients, including 5 patients with radicular cyst and 2 patients with dentigerous cysts, showed extrusion of some of the Chitra–HASi granules from the surgical site 3 months postoperatively. The size of the extruded granules ranged from 0.5 to 1 mm in size.


   Discussion Top


The criteria for an ideal graft proposed by Emmings include immunobiologic neutrality, ability to restore form and/or function, readily available, provide elements for, support or stimulate bone growth, inexpensive, and have a prolonged shelf life.[15] The more pertinent question in such situations is the need for a bone graft at the defect site. Multiple studies have shown uneventful, spontaneous healing of defects of varied sizes.[12]

However, when considering Schmitz and Hollinger's[16] definition of a critical-sized defect as “the smallest intraosseous defect that does not heal spontaneously with bone during the lifetime of the animal unless some osteogenic, osteoconductive or osteoinductive material has been placed in or onto the defect”, due attention must be given to larger cystic defects. Research on canine mandibles have found that the critical-sized defect varies between 20 to 40 mm.[16] Such defects, when left untreated, get filled with fibrous connective tissue along with limited bony regeneration near the margins of the defect.[17] Hence, we considered 20 mm × 20 mm as the critical defect size for the present study and have included patients with defects equal to or larger than this.

While no material has been found to satisfy all the criteria required to fill these defects, a plethora of bone graft materials of different origins have been tested in an attempt to regenerate bone. Among synthetic bone grafts, the most popularly used are HA- and calcium phosphate-based materials, due to their resemblance to inorganic bone.[18]

A recent phase-3, multicenter study demonstrated the use of octacalcium phosphate combined with atelocollagen as a bone substitute for use in oral and maxillofacial defects. However, all the patients in the trial suffered adverse events in the form of swelling, pain, and increasing C-reactive protein and white blood cell levels.[19]

In the pursuit to create an ideal bone substitute, Chitra–HASi material was developed by a solid phase reaction of calcium phosphate and silicate ingredients. Addition of silica aims to improve the quality of regenerated bony tissue with higher strength and improvements in its matrix quality.[20] This quality mimics that of natural bone, thus differentiating Chitra–HASi granules from other bone substitutes.

Preliminary studies carried out using HASi granules in a rat model demonstrated compatibility at the system level.[13] Cells via fluorescent imaging and FACS analysis were highly competent in differentiation and viability of HASi system.[21] Increase in gene expression related to bone formation also validated the cell–material construct of HASi and stem cell populations.[22]

Inherent material properties and appropriate cellular interactions favored further application of HASi[23], and the material was evaluated in a goat femur defect in the granule format. HASi was able to stimulate a favorable environment for de novo bone formation with faster resorption. The material has an attractively low Si content with negligible levels at implanted sites and vital organs postimplantation.[24]

Furthermore, a HASi scaffold loaded with culture-expanded autologous bone marrow-derived mesenchymal stem cells primed into osteogenic lineage was implanted in a 12-year-old child presenting with a post-septic gap non-union of 4 cm in the proximal humerus successfully.[25] a HASi scaffold loaded with culture-expanded autologous bone marrow-derived mesenchymal stem cells primed into osteogenic lineage was implanted in a 12-year-old child presenting with a postseptic gap nonunion of 4 cm in the proximal humerus successfully.[25] This demonstrated the ability of the cell–material construct to remedy a condition notorious for a high failure rate. The results of these studies suggest that the infections with sinus tract formation noted in the present study may have been secondary to the type of cysts, the infection status at the time of enucleation, and the oral hygiene as maintained by the patients following grafting. A randomized study with long-term follow-up is likely to clarify questions pertaining to the immunobiological properties of the graft and its rate of infection.

In terms of long-term prognosis, the fate of porous HA has been assessed in facial augmentation procedures in a prospective radiological study, which showed that 99.7% of the augmented volume remained even after 2 years. This finding showed no statistical difference from the baseline values and no evidence of overlying soft tissue atrophy or bone resorption.[26] This suggests that HA not only provides longevity but also delivers adequate strength to the grafted site.

The major drawbacks of the present study are the limited number of patients that could be evaluated postoperatively at 1 year and the method of assessment of bone density following placement of the Chitra–HASi graft. Although CT offers better specificity, a panoramic radiograph was used to demonstrate bone density, as it was readily available and cost-effective. While a histological examination of the grafted bone would be considered gold standard for assessing bone fill, the procedure was not feasible in view of its invasiveness.


   Conclusion Top


The efficacy of this newly developed HA silica-based bone regeneration material “Chitra–HASi” was evaluated as a primary bone filling material in the treatment of maxillofacial cystic defects. Its advantages are primarily reflected in its terminology as HA coated with silica (HASi), wherein the silica offers improved strength and toughness, as in native bone. Absence of host rejection, superior biocompatibility, and increased bone density levels on radiographic evaluation indicate its ability to replace auto-, allo-, and xenografts. In addition, its porous nature also encourages vascular ingrowth, thus improving osteogenic potential.

In view of these encouraging results, the authors believe that Chitra–HASi granules can be used as a bone substitute in large cystic defects of the jaws. Despite certain limitations of the study, the material shows promise for bone regeneration in the maxillofacial region, and further studies can help evaluate its long-term stability.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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