Ginekologia i Poloznictwo
ISSN 1896-3315 e-ISSN 1898-0759

Impact of diabetes mellitus on osseointegration of tantalum oxynitride-coated titanium implants in female rabbits: A histological perspective with implications for reproductive health

Hassan Jawad Farhan¹ and Akram Yousif Yasear^{2* *}Correspondence: Akram Yousif Yasear, College of Dentistry, University of Kerbala, College of Dentistry, University of Hilla, Iraq,

Received: 20-Jun-2025, Manuscript No. gpmp-25-168364; Editor assigned: 23-Jun-2025, Pre QC No. P-168364; Reviewed: 15-Jul-2025, QC No. Q-168364; Revised: 23-Jul-2025, Manuscript No. R-168364; Published: 29-Aug-2025

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Introduction

In the 1960s, Swedish orthopaedist Branemark discovered by chance the integration of Titanium (Ti) with human bones; it was subsequently called osseointegration. Osseointegration refers to the clinically asymptomatic rigid and direct fixation of alloplastic materials to the bone, which is maintained and activated during continuous functional loads [1]. An osteocyte is a type of bone cell that originates as an osteoblast and gradually transforms into an osteocyte by surrounding itself with a newly formed matrix. Osteocytes form a network of highly oriented interconnected cells inside the bone. These cells are the most abundant and widely distributed in all bone cells in humans [2]. The osteocyte is an essential component of the bone. It is estimated that the human skeleton contains about 40 billion osteocytes. About 10 million such cells are replaced daily in the human skeleton [3]. They are situated inside lacunae embedded in the bone matrix between the bone lamellae. Only one osteocyte is found in each lacuna. Each osteocyte exhibits several processes that establish contact across the communicating gap junctions, enabling molecules to pass from one osteocyte to another. This exchange of metabolites provides nourishment for a chain of about 15 cells. Osteocytes are important for detecting the mechanical loading imposed on the bone and regulating the process of bone remodeling [4-6]. Osteocytes are mechanosensory cells and are vital for assessing bone density by using their processes to connect with osteoblasts and osteoclasts [7] and cellular processes [8]. For this reason, osteocytes have been found to be active participants in the maintenance of osseointegration around metal implants [9].

Tantalum (Ta), regarded as one of the most important materials used in dental implants, may be used to coat the outer surface of core materials [10]. Tantalum oxide (TaO) and Tantalum Nitride (TaN) are stable and provide a protective film which offers a larger hydrophilic surface, better bioactive properties, and stronger corrosion resistance than non-coated CpTi [11]. Implants with surface coatings have lower failure rates and can support stronger and more dynamic forces [12].

Diabetes mellitus is a chronic metabolic disorder that manifests as elevated glucose plasma levels, also called hyperglycaemia, owing to defects in insulin action, secretion, or both. Glucose release by the liver may be impacted, or the body tissues might not have a normal physiological equilibrium of glucose utilisation by body tissues. Animal studies remain the only experiments that facilitate a systematic evaluation of the pathological and biological effects of diabetes on dental implants and their osseointegration with bones, even though several clinical studies have analysed the success and failure rate of dental implants in diabetic patients [13]. This work aimed to assess the distribution and importance of osteocytes in the osseointegration of TaON-coated Commercial pure Titanium (CpTi) screws in healthy and diabetic rabbits.

Materials and Methods

Tantalum Oxynitride (TaON) coating of CpTi was conducted over eight hours by reactive plasma sputtering. Of the eight white female New Zealand rabbits, four were alloxan-induced diabetic rabbits, and four were normal. Two CpTi screws, one non-coated and one TaON-coated, were inserted in each femur of each rabbit, for a total of 32 screws. Sixteen (16) screws comprising eight TaON-coated and eight non-coated ones were inserted in diabetic rabbits. At the same time, 16 screws were inserted in healthy rabbits, following a distribution identical to diabetic rabbits. Treated rabbits were given an alloxan injection to induce diabetes before metal implantation. These rabbits formed the second group, as per the procedure suggested by Mir, et al. [14]. In the third group, the rabbits were allowed to adapt to diabetes before they were subjected to any experimental manipulation.

The implanted metals, along with 10mm of the bone, were harvested from the femur of all rabbits in all groups. The fixation of collected samples was done for 48 hours in 10% formalin. The collected samples were subjected to conventional tissue preparation steps used in histology. The protocol includes washing with running water, dehydration in ascending grades of ethanol, and cleaning with xylene before embedding in methacrylate. Subsequently, 30 µm sections of the CpTi and bone were cut using a saw microtome. The sections were stained with toluidine blue.

Results

The histological results of the femurs of the non-coated CpTi screws in normal and diabetic rabbits after two weeks indicated mostly immature primary bone tissue at the screw-bone interface (Fig. 1.). Bone trabeculae were thin with a wide area of marrow space. The bone trabeculae were covered by osteoblasts. The osteocytes were sparsely scattered inside bone trabeculae. No osteoclasts were detected in bones in this group.

Fig. 1. Sections of the uncoated CpTi screws showing immature primary bone with bony trabeculae around the implant (left side of the section). The trabeculae were covered with osteoblasts (arrowed). Many osteocytes were present inside the trabeculae (arrowheads). The spaces between the trabeculae were marrow spaces (rectangles). Toluidine blue stain. X bar 1mm.

In healthy rabbits with TaON-coated CpTi screws, the peri-implant bone was more mature. The bone showed widely distributed osteons, with their bone lamellae (Fig. 2.). The osteoblasts were present at the interface close to the implant, while the osteocytes were greatly dispersed at regular intervals between or, occasionally, within lamellae (Fig. 2.). On the other hand, the peri-implant bone contact with TaON-coated CpTi screws inserted in the femurs of diabetic rabbits showed results almost similar to the second group (Fig. 3.).

Fig. 2. Light micrographs of the femur segments of the normal rabbits implanted with TaON-coated CpTi screws. Several bone osteons (red circle) and osteocytes (arrowheads) were observed around the central canal of the osteons. No bone marrow regions were observed. The osteoblasts (arrows) were close to the metal’s surface. Toluidine blue stain. X 100.

Fig. 3. Light micrographs of the femur segments of the diabetic rabbits two weeks post-implantation with TaON-coated CpTi screws. Several bone osteons (red circles), and osteocytes (arrowheads) were observed around the central canal of the osteons No bone marrow regions were observed. The osteoblasts (arrows) were close to the metal’s surface. Toluidine blue stain. X 200.

Discussion

Several implantology studies have highlighted several factors outlining the criteria that could be considered to evaluate the success of dental implants. These include frequency resonance analysis combined with implant insertion and removal value torque [15, 16] and other methods like surgical techniques, microscopic and macroscopic dental implant design, and the quantity and quality of the bone in contact with and around the dental implant [17].

In the present study, osseointegration enhancement was achieved by implanting TaON-coated CpTi screws in the femurs of both normal and diabetic rabbits. The bone developed in a close contact area around the CpTi screw has shown a significantly higher osteocyte cell density around implants that were immediately inserted, compared to the methods indicated in previous studies [18], in which Ti was coated with tantalum pentoxide (Ta₂O₅) and titanium nitride (TiN) separately. The increase in the number of osteocytes may be attributed to the fact that the bone tissue exhibited better adaptation to the rough surface of the implant, indicating a significant role of osteocytes in maintaining bone matrix [19]. The observations align with Kusakari and Maeda’s [6] conclusion that proper metal implantation is achieved when osteocytes develop and mature with time. These observations are also supported by Shah, et al. [9] and Shah, et al. [20]. Moreover, they stated that long-term successful dental implantation requires continued maintenance of osseointegration of implants, which is a requirement that osteocytes fulfil.

The presence of osteoblasts close to the surface of implant screws indicated successful osseointegration, suggesting that bone remodelling had happened [21]. Huang, et al. [22] pointed out that adequate bone remodelling was a good long-term marker for successful and complication-free dental implant treatment. Osteocytes gradually maintain the osseointegration with the implant over time through stimulation of bone remodelling in the preimplantation area. Bone remodelling stimulation by osteocytes is related to the fact that these cells exhibit mechanosensory properties in connection with bone status [23].

In response to surface treatment, the rise in osteoblast count and, consequently, significantly higher osteocyte cells indicate that the survival rate of these cells can be externally controlled [24]. The implant stability quotient scale, or vibration frequency, ranges between ~1 to ~10kHz and increases with increasing stability of an implant in the bone [25], which is influenced by factors such as bone density, the degree of osseointegration, implant site preparation, and implant design [9]. Previous histomorphometry studies relating to bone healing around implants have considered the number of osteocytes present inside the osseointegrated bone tissue as a good indicator of successful implantation [21, 22].

In a previous study [26], the histological features of the non-coated screws in rabbit femurs after two weeks of implantation showed less osteoid tissue with fewer osteocytes around the implant compared to TaON-coated CpTi screws. Thus, the present work has noticed better osseointegration in rabbits with induced diabetes. The bone formation around TaON-coated CpTi screws inserted in rabbit bone was more compared to the non-coated screws [27].

Conclusion

The authors of this study would like to invite dental clinicians to try TaON-coated CpTi screws. The results after a two-week recovery period provided after inserting the implants have indicated promising sustained success. The enhancement of osseointegration and functional adaptation required in an implant manifests as an increase in the number of osteocytes in TaON-coated CpTi screws in both normal and diabetic rabbits.

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