Rat Mandible Research Articles

Enhancement of bone regeneration by coadministration of angiogenic and osteogenic factors using messenger RNA

BackgroundBone defects remain a challenge today. In addition to osteogenic activation, the crucial role of angiogenesis has also gained attention. In particular, vascular endothelial growth factor (VEGF) is likely to play a significant role in bone regeneration, not only to restore blood supply but also to be directly involved in the osteogenic differentiation of mesenchymal stem cells. In this study, to produce additive angiogenic-osteogenic effects in the process of bone regeneration, VEGF and Runt-related transcription factor 2 (Runx2), an essential transcription factor for osteogenic differentiation, were coadministered with messenger RNAs (mRNAs) to bone defects in the rat mandible.MethodsThe mRNAs encoding VEGF or Runx2 were prepared via in vitro transcription (IVT). Osteogenic differentiation after mRNA transfection was evaluated using primary osteoblast-like cells, followed by an evaluation of the gene expression levels of osteogenic markers. The mRNAs were then administered to a bone defect prepared in the rat mandible using our original cationic polymer-based carrier, the polyplex nanomicelle. The bone regeneration was evaluated by micro-computerized tomography (μCT) imaging, and histologic analyses.ResultsOsteogenic markers such as osteocalcin (Ocn) and osteopontin (Opn) were significantly upregulated after mRNA transfection. VEGF mRNA was revealed to have a distinct osteoblastic function similar to that of Runx2 mRNA, and the combined use of the two mRNAs resulted in further upregulation of the markers. After in vivo administration into the bone defect, the two mRNAs induced significant enhancement of bone regeneration with increased bone mineralization. Histological analyses using antibodies against the Cluster of Differentiation 31 protein (CD31), alkaline phosphatase (ALP), or OCN revealed that the mRNAs induced the upregulation of osteogenic markers in the defect, together with increased vessel formation, leading to rapid bone formation.ConclusionsThese results demonstrate the feasibility of using mRNA medicines to introduce various therapeutic factors, including transcription factors, into target sites. This study provides valuable information for the development of mRNA therapeutics for tissue engineering.

The Condylar Effects of Mesenchymal Stem Cells, Low-Level Laser Therapy and Grape Seed Extract on Functional Mandibular Advancement of the Rat Mandible.

Functional treatment of Class II malocclusion is expected to lead to adaptation in the condyle. This study aimed to evaluate the effects of adipose tissue-derived mesenchymal stem cells (ADMSCs), low-level laser therapy (LLLT), and grape-seed extract (GSE) on condylar growth after functional mandibular advancement. Forty-five rats were randomly divided into 8 groups. Functional appliances were applied to all groups (n=6) except the control group (n=3). One group was treated with appliances only; the other six groups received various combinations of ADMSCs, LLLT, and GSE. Analyses for new osteoblasts and new bone formation, vascular endothelial growth factor, and Type II collagen were performed on condylar tissues, after an experimental period of four weeks. The quantitative data obtained from the results of the experiments were evaluated by H-score and analyzed using One-Way ANOVA by Tukey-Kramer multiple comparisons test (p≤0.05). Levels of all investigated parameters increased in all groups (p≤0.05). The highest increases were achieved by a combined application of functional appliance, ADMSCs, LLLT and GSE (p≤0.05). Single LLLT administrations or single GSE applications did not create a statistical difference from appliance alone (p>0.05). A positive effect of ADMSCs or LLLT on osteoblast formation, neovascularization, and Type II collagen level was apparent (p≤0.05), however, neither affected new bone formation (p>0.05). This study shows that ADMSCs with LLLT and GSE applications provide differing levels of new osteoblast and bone formation, new vascular formation, and Type II collagen formation in rat condyles after functional mandibular advancement.

The feasibility of discriminating BRONJ lesion bone with Raman spectroscopy.

With the frequent use of Bisphosphonates (BPs), the morbidity of BP-related osteonecrosis of the jaw (BRONJ) is also increasing. However, the prevention and treatment of BRONJ is faced with enormous challenges. This study aimed to illuminate the influence of BP administration in the rat mandible and explore the feasibility of discriminating BRONJ lesion bone with Raman spectroscopy. First, we explored the time- and mode-dependent effects of BP administration on the rat mandible with Raman spectroscopy. Second, the BRONJ rat model was constructed, and the lesion and healthy bone components were analyzed using Raman spectroscopy. When only BPs were administered, no rats showed BRONJ symptoms, and no difference could be found in the Raman spectra. However, when combined with local surgery, six (6/8) rats showed BRONJ symptoms. The Raman spectra also showed a significant difference between the lesion and healthy bone. In the progression of BRONJ, BPs and local stimulation play an essential role. Both BPs administration and local stimulation need to be controlled to prevent BRONJ. Moreover, BRONJ lesion bone in rats could be discriminated with Raman spectroscopy. This novel method would become a complement in the treatment of BRONJ in the future.

3D-printed gelatin/sodium alginate/58S bioactive glass scaffolds promote osteogenesis in vitro and in vivo.

Three-dimensional (3D)-printed scaffolds are a new strategy to fabricate biomaterials for treating bone defects. Here, using a 3D-printing technique, we fabricated scaffolds consisting of gelatin (Gel), sodium alginate (SA), and 58S bioactive glass (58S BG). To evaluate mechanical properties and biocompatibility of Gel/SA/58S BG scaffolds, the degradation test, compressive strength test, and cytotoxicity test were performed. The effect of the scaffolds on cell proliferation in vitro was determined by 4',6-diamidino-2-phenylindole (DAPI) staining. To evaluate osteoinductive properties, rBMSCs were cultured on the scaffolds for 7, 14, and 21days and the expression of osteogenesis-related genes was analyzed using qRT-PCR. To examine the bone healing properties of Gel/SA/58S BG scaffolds in vivo, we used a rat mandibular critical-size defect bone model. The scaffolds were implanted into the defect area of rat mandible and bone regeneration and new tissue formation were assessed using microcomputed tomography (microCT) and hematoxylin and eosin (H&E) staining. The results showed that Gel/SA/58S BG scaffolds had appropriate mechanical strength as a filling material for bone defects. Furthermore, the scaffolds could be compressed within certain limits and then could recover their shape. The extract of the Gel/SA/58S BG scaffold showed no cytotoxicity. In vitro, the expression levels of Bmp2, Runx2, and OCN were increased in rBMSCs cultured on the scaffolds. In vivo, microCT and H&E staining demonstrated that scaffolds induced the formation of new bone at the mandibular defect area. These results indicated that Gel/SA/58S BG scaffolds have excellent mechanical characteristics, biocompatibility, and osteoinductive properties, suggesting that it could be a promising biomaterial for the repair of bone defects.

Is modified Carnoy’s solution as effective as Carnoy’s solution in terms of amount of bone necrosis and depth of penetration?

Carnoy’s solution, a chemical cauterisation agent, has been indicated as one of the adjuvant treatment modalities for odontogenic keratocyst. In 2000, after the ban of chloroform many surgeons adopted the use of Modified Carnoy’s solution. The purpose of this study is to compare the depth of penetration and amount of bone necrosis of Carnoy’s versus Modified Carnoy’s solution on the mandible of Wistar rats at different time intervals. Twenty-six male Wistar rats of six to eight weeks old, weighing approximately 150–200 grams, were allocated for this study. The predictor variables were type of solution and application time. The outcome variable was depth of penetration and amount of bone necrosis. Carnoy’s solution was applied on the defect on the right side of the mandible and Modified Carnoy’s solution on the left side for five minutes on eight rats, eight minutes on eight rats, and 10 minutes on eight rats. All specimens were subjected to histomorphometric analysis done using Mia image AR software. Univariate ANOVA test, and paired sample t test was done to compare the results. The depth of penetration for Carnoy’s solution was more than Modified Carnoy’s solution in the three different exposure times. Statistically significant results were observed at five minutes and eight minutes. The amount of bone necrosis was more in Modified Carnoy’s solution. The results were not statistically significant at the three different exposure times. To conclude, when one wants to use Modified Carnoy’s solution, the minimum exposure time should be 10 minutes to achieve similar results as those of Carnoy’s solution.

Effects of barium titanate on the dielectric constant, radiopacity, and biological properties of tricalcium silicate-based bioceramics.

This study evaluated the effect of barium titanate (BT) on the dielectricity, radiopacity, and biological properties of tricalcium silicate (C3S). C3S/BT samples were prepared with varying proportions of BT (0, 20, 40, and 60 wt%; referred to as BT00, BT20, BT40, and BT60, respectively). Dielectric constant and radiopacity were measured. Cytocompatibility was evaluated on human dental pulp cells. After surgical procedures on rat mandible, immunohistochemistry and Masson's trichrome staining were performed. The dielectric constant increased with higher proportions of BT (p<0.05). BT40 and BT60 satisfied the clinical guideline of radiopacity. There were no significant differences among groups in the cytocompatibility tests (p>0.05). New bone was observed well, along with the expressions of the dentin matrix protein 1 (DMP1), osteocalcin (OC), and osteonectin (ON) in BT40 and BT60. Conclusively, the contents of 40-60 wt% of BT in C3S provided proper radiopacity, favorable cytocompatibility, and beneficial effect on bone regeneration.

Low-level laser efficiency in reparation of bone defects

Introduction/Objective. Bone resorption is a common problem in dentistry, and bone reparation cannot be easily achieved. Several techniques of bone grafting and the use of low-level laser treatment (LLLT) as a new therapeutic optional recommended for improving bone repair were applied. The aim of the study was to investigate the influence of LLLT in bone repair of artificially made bone defects in the rat mandible using histomorphometry. Methods. The research was carried out on 60 female rats. Bone defects were made in the mandible, and animals were divided into two groups, each containing 30 animals. In the study group, the implantation site was submitted to GaAlAs laser irradiation 670 nm, 5 mW, 4 minutes per day for 5 days. The control group had no postoperative treatment. The animals were sacrificed after two, six, and eight weeks post LLLT, and preparations were analysed by histomorphometry, determining bone area fraction, bone area, integral density, mean density, and density variation. Results. Histomorphometric analysis revealed statistically higher values of area fraction, area, and integral density in the study group after two and six weeks. However, no beneficial laser effect was noticed after eight weeks. Conclusion. Low-level lasers have a stimulating effect on reparatory mechanisms in the early regeneration stage of artificially made bone defects in the rat mandible and can be used as a useful helping method in bone treatment.

The mechanism of bone metabolism in a Sprague Dawley rat model of mandibular osteoradionecrosis.

Osteoradionecrosis (ORN) is a serious complication of radiotherapy for head and neck cancer. There is currently a lack of data on the dynamic expression of genes related to bone remodeling during the development of mandibular ORN. This study aimed to establish an animal model of ORN in Sprague Dawley (SD) rats, detect the expression of genes related to bone metabolism, observe morphological changes, and clarify the mechanism of ORN. A total of 24 male SD rats in group 1 were randomly divided into four groups (n=6/group): group a, normal control; group b, simple tooth extraction; group c, simple radiation; and group d, radiation extraction group. The right mandible of rats in groups c and d was irradiated with a single dose of 35 Gy. The right mandibles were taken from each group for morphological observation 90 days after irradiation. SD rats in group 2 (n=144) were randomly divided into four groups (in similar fashion to group 1 but with groups a', b', c', and d'). Samples were collected at six time points after irradiation. Histopathological changes were observed, and Western blotting (WB) was used to analyze protein expression. The formation of dead bone and pathological fracture was visible under micro-computed tomography (micro-CT), and tissue biopsy showed late fibrosis repair. In group d', osteogenesis and osteoclasis coexisted in the early irradiation stage. Vascular endothelial growth factor (VEGF) receptor expression was lower in groups c' and d' than in group a'. On day 45, runt-related transcription factor 2 (RUNX2) expression in group d' was lower than that in the other groups. The ratio of receptor activator of nuclear factor-κβ ligand to osteoprotegerin (RANKL:OPG) differed significantly among groups b', c', and d' on the 45th day (d' > c' > b'). Radiation and vascular function damage resulted in the lower expression of VEGF. The first 15 days after radiation was mainly characterized by new bone formation. After 15 days, bone resorption increased. Tooth extraction trauma can aggravate the bone metabolism imbalance and promote ORN occurrence. These findings shed light on the mechanism of ORN.

Gingival inflammation induction in pregnant Sprague-Dawley rats: A pilot study

Pregnancy gingivitis is an inflammation of the gingiva caused by dental plaque and exacerbated by hormonal changes. Gingival inflammation is often induced in laboratory animal models, such as SpragueDawley rats used for experimental models. This investigation was to establish inducing gingival inflammation in pregnant rats. The purpose of this study was to establish a reproducible method for inducing gingival inflammation in both incisive mandibles of pregnant Sprague-Dawley rats using ligation and dietary manipulation. Pregnant Sprague-Dawley rats were used as experimental subjects. As ligation, 4-0 nonresorbable silk thread was utilized and affixed using a “8”-shaped knot technique. The ligatures were inserted between the mandible’s central incisors. The operation was carried out under anaesthesia. Once the rat’s ligature was removed after 5th,7th,10th and 14th days. The clinical appearance and radiographic examination were evaluated. Gingival inflammation induction by ligation and dietary intake modification caused inflammation of gingival tissue, was seen at 5th day. Clinical examination showed getting worst at 14th day. In our study, gingival inflammation on pregnant rat was achieved five days after ligation and dietary intake modification.

Definition of the Region of Interest for the Assessment of Alveolar Bone Repair Using Micro-computed Tomography.

The objective of this study was to evaluate the influence of the extraction socket (distal or lingual root) and the type of region of interest (ROI) definition (manual or predefined) on the assessment of alveolar repair following tooth extraction using micro-computed tomography (micro-CT). The software package used for scanning, reconstruction, reorientation, and analysis of images (NRecon®, DataViewer®, CT-Analyzer®) was acquired through Bruker < https://www.bruker.com > . The sample comprised the micro-CT volumes of seven Wistar rat mandibles, in which the right first molar was extracted. The reconstructed images were analyzed using the extraction sockets, i.e., the distal and intermediate lingual root and the method of ROI definition: manual (MA), central round (CR), and peripheral round (PR). The bone volume fraction (BV/TV) values obtained were analyzed by two-way ANOVA with Tukey's post hoc test (α = 5%). The distal extraction socket resulted in significantly lower BV/TV values than the intermediate lingual socket for MA (P = 0.001), CR (P < 0.001), and PR (P < 0.001). Regarding the ROI, when evaluating the distal extraction socket, the BV/TV was significantly higher (P < 0.001) for MA than for CR and PR, with a lower BV/TV for CR. However, no significant difference was observed for MA (P = 0.855), CR (P = 0.769), or PR (P = 0.453) in the intermediate lingual extraction socket. The bone neoformation outcome (BV/TV) for alveolar bone repair after tooth extraction is significantly influenced by the ROI and the extraction socket. Using the predefined method with a standardized ROI in the central region of the distal extraction socket resulted in the assessment of bone volume, demonstrating the most critical region of the bone neoformation process.

Effects on Tissue Integration of Collagen Scaffolds Used for Local Delivery of Gentamicin in a Rat Mandible Defect Model.

Surgical site infections (SSIs) are a common complication following orthopedic surgery. SSIs may occur secondary to traumatic or contaminated wounds or may result from invasive procedures. The development of biofilms is often associated with implanted materials used to stabilize injuries and to facilitate healing. Regardless of the source, SSIs can be challenging to treat. This has led to the development of devices that act simultaneously as local antibiotic delivery vehicles and as scaffolds for tissue regeneration. The goal for the aforementioned devices is to increase local drug concentration in order to enhance bactericidal activity while reducing the risk of systemic side effects and toxicity from the administered drug. The aims of this study were to assess the effect of antibiotic loading of a collagen matrix on the tissue integration of the matrix using a rat mandibular defect model. We hypothesized that the collagen matrix could load and elute gentamicin, that the collagen matrix would be cytocompatible in vitro, and that the local delivery of a high dose of gentamicin via loaded collagen matrix would negatively impact the tissue–scaffold interface. The results indicate that the collagen matrix could load and elute the antimicrobial gentamicin and that it was cytocompatible in vitro with or without the presence of gentamicin and found no significant impact on the tissue–scaffold interface when the device was loaded with a high dose of gentamicin.

Effects of functional mandibular lateral shift on craniofacial growth and development in growing rats

Unilateral posterior crossbite, one of the most frequent malocclusions, is often associated with functional lateral shift of the mandible. Although the effects of functional lateral shift on the mandible and temporomandibular joint have been examined in various animal experiments, cranial and maxillary changes have received less attention. The aim of this study was to investigate the effects of functional lateral shift on the craniofacial complex in growing rats. Eighty 5-week-old male Sprague-Dawley rats were randomly divided into an experimental group (n=40), which received an oblique guide appliance that shifted the mandible to the left during closure, and a control group (n=40). The rats were scanned by cone-beam computed tomography at 3 days and 1, 2, 4 and 8 weeks. The dimensions of the mandibular bone, condyle, maxilla and cranium were measured. The mandibles of rats in the experimental group were smaller than those of the rats in the control group and were asymmetrical. The condyles of the rats in the experimental group were thinner than those of the control rats. The condylar length on the ipsilateral side was shorter and wider than that on the contralateral side from 4 to 8 weeks. No significant differences in cranial length or height were observed between the experimental and control groups. The height of the upper first molar and alveolar bone on the contralateral side was significantly smaller than that on the ipsilateral side and in the controls from 4 to 8 weeks. Functional shift in the mandible produces morphological asymmetries in the mandible and maxillary region and may cause bilateral condylar degenerative changes.

The Effect of Thyroid Status on the Structure and Process of Restoration of the Area of Traumatic Injury to the Mandible in Rats under Stress

The Effect of Thyroid Status on the Structure and Process of Restoration of the Area of Traumatic Injury to the Mandible in Rats under Stress

Craniofacial Bones and Teeth in Spacefarers: Systematic Review and Meta-analysis.

Estimating the risk of dental problems in long-duration space missions to the Moon and Mars is critical for avoiding dental emergencies in an environment that does not support proper treatment. Previous risk estimates were constructed based on the experience in short-duration space missions and isolated environments on Earth. However, previous estimates did not account for potential changes in dental structures due to space travel, even though bone loss is a known problem for long-duration spaceflights. The objective of this study was to systematically analyze the changes in hard tissues of the craniofacial complex during spaceflights. Comprehensive search of Medline, Embase, Scopus, the NASA Technical Report Server, and other sources identified 1,585 potentially relevant studies. After screening, 32 articles that presented quantitative data for skull in humans (6/32) and for calvariae, mandible, and lower incisors in rats (20/32) and mice (6/32) were selected. Skull bone mineral density showed a significant increase in spacefaring humans. In spacefaring rodents, calvariae bone volume to tissue volume (BV/TV) demonstrated a trend toward increasing that did not reach statistical significance, while in mandibles, there was a significant decrease in BV/TV. Dentin thickness and incisor volume of rodent incisors were not significantly different between spaceflight and ground controls. Our study demonstrates significant knowledge gaps regarding many structures of the craniofacial complex such as the maxilla, molar, premolar, and canine teeth, as well as small sample sizes for the studies of mandible and incisors. Understanding the effects of microgravity on craniofacial structures is important for estimating risks during long-duration spaceflight and for formulating proper protocols to prevent dental emergencies. Avoiding dental emergencies in long-duration spaceflights is critical since this environment does not support proper treatment. Prior risk estimates did not account for changes in dental structures due to space travel. We reviewed and synthesized the literature for changes in craniofacial complex associated with spaceflight. The results of our study will help clinicians and scientists to better prepare to mitigate potential oral health issues in space travelers on long-duration missions.

Micro-CT analysis of the mandibular bone microarchitecture of rats after radiotherapy and low-power laser therapy.

To investigate whether low-level laser therapy (LLLT), at different times of application (immediate and late) in the region of the parotid glands, has a distance effect on the microarchitecture of the trabecular bone in mandible of rats irradiated by volumetric modular arc therapy (VMAT). Thirty adult Wistar rats were randomly divided into placebo control groups (CG, n = 2), only radiotherapy (RG, n = 2), only LPLT (LG, n = 2), and two other groups using LLLT in the immediate time (24h) (ILG, n = 12) and late (120h) (LLG, n = 12) to radiotherapy by VMAT in a single dose of 12Gy. LLLT with AsGaAl laser (660nm, 100 mW), a spot size of 0.0028 cm2, was applied in three points in the region of the right parotid gland, with energy of 2J/cm2, 20s per point, for 10 consecutive days. After euthanasia, the right hemimandibles of each animal were dissected, prepared, and analyzed by computerized microtomography (micro-CT) and histomorphometry. The different groups were analyzed by the Tukey and Bonferroni multiple comparison tests. The micro-CT analysis found statistically significant differences between the groups, especially in the LLG, which had the highest average bone volume compared to the CG (p = 0.001) and ILG (p = 0.002) and a greater number of trabeculae than the CG (p = 0.000) and ILG (p = 0.031). The ILG also had a higher number of trabeculae than the CG (p = 0.005). Trabecula separation (Tb.Sp) was lower in the LLG (p = 0.000) and ILG (p = 0.002) when compared to the CG. In the histomorphometry, there was no statistical difference between the groups in relation to all the analyzed variables. Micro-CT analysis showed that the LLLT, even applied at a distance, both in the immediate and late VMAT times, has an effect on the mandibular bone microarchitecture by increasing the volume and number of trabeculae and decreasing the spaces between them.

The Significance of Iodine-Containing Thyroid Hormones in Postfractural Changes in the Function and Structure of the Rat Mandible under Stress

The Significance of Iodine-Containing Thyroid Hormones in Postfractural Changes in the Function and Structure of the Rat Mandible under Stress

Impact of Diet Consistency on the Mandibular Morphology: A Systematic Review of Studies on Rat Models.

Apart from genetics, environmental factors, such as food consistency, may affect craniofacial morphology and development. The present systematic review aims to systematically investigate and appraise the available evidence regarding the effect of diet consistency on the anatomical structures of the basal bone of the rat mandible. The search was performed without restrictions in five databases (PubMed, Scopus, Web of Science, ProQuest Dissertations and Theses Global, including grey literature) and hand searching through January 2022. A total of 14,904 references were initially identified, and 16 articles were finally included in the systematic review. Rats that consumed hard diets were found to exhibit an increase inbigonial width, corpus height, condylar depth, condylar base inclination, condylar process inclination, mandibular plane inclination, height and length of angular process, mandibular body height, depth of antegonial notch, growth rate in the gonial angle, angular process convexity and height of condylar process. It was also noted that mandibular depth, mandibular height, ramus angle and angle between the angular process and mandibular plane were decreased in rats that were fed with a hard diet. On the other hand, there were conflicting results about the growth of mandibular length and width, corpus length, mandibular body length, ramus height, condylar length and width, gonial angle and height of coronoid process. From the abovementioned results, it can be concluded that food consistency may affect the morphology of anatomical structures and the overall growth and development of rat mandibles in various ways.

IS THE REITERATION OF EXTRACORPOREAL SHOCK WAVE THERAPY BENEFICIAL TO ENHANCE THE BONE INTEGRITY IN TYPE 1 DIABETIC RATS?

Objective: Type 1 Diabetes Mellitus is an important endocrine disease that causes disorders in the musculoskeletal system. Extracorporeal shock wave therapy (ESWT) may be effective in the improvement of these disorders due to its reported anabolic effects. Material and Methods: The effects of unfocused shock waves on the mandible in healthy and diabetic rats were investigated. 36 wistar albino rats were used and randomly divided into 4 groups: non-diabetic control (n-cont), non-diabetic eswt (n-eswt), diabetic control (d-cont), diabetic eswt (d-eswt). Geometric structure, bone mineral density (BMD) and biomechanical properties of the mandibles were analyzed. Datas were statistically analyzed by one-way variance analysis and Tukey post-hoc test. Results: According to the results, BMD was lower in the diabetic groups. There was no significant increase in ESWT groups. The surface area of the mandible was significantly lower in the diabetic groups than in the n-cont group. However, it was significantly higher in the d-eswt group than in the d-cont group. Ultimate load values were found to be significantly lower in the d-eswt group than in the d-cont group. While there was no significant difference between the groups in terms of stiffness, ultimate strain and young modulus, lower ultimate stress values were observed in the d-eswt group compared to the d-cont group. Conclusions: As a result, type 1 Diabetes Mellitus caused a decrease in bone dimensions and bone mineral density, but did not affect the biomechanical properties. Interestingly, ESWT application caused the bone to be more fragile in diabetics

Effect of Inferior Alveolar Nerve Transection on the Inorganic Component of Molars of Rat Mandible.

The objective of the study was to determine the effects of inferior alveolar nerve transection on inorganic components in mandibular molars of the rat. We used 26 male laboratory rats of the Wistar strain for the study, age 7-9 weeks. The rats were divided in three groups. The control group (intact) included 6 rats. The surgery was performed under general anesthesia. The experimental group included (group with the nerve transected on the left) included 12 rats. The sham group (group with the nerve prepared without transection) included 8 rats. The animals were sacrificed after 4 weeks. Molars from the left and right sides of the mandible were extracted. Element content levels were determined using inductively coupled plasma mass spectrometry. The following elements were determined in all samples: magnesium (Mg), sodium (Na), potassium (K), calcium (Ca), zinc (Zn), and strontium (Sr). The nerve transection caused: a reduction of the contents of Ca and Sr in the mandibular molars; an increase in the contents of Mg and Zn; a difference arrangement of both sides for Na. The surgery approach itself caused a decrease in the contents of Na and K in the experimental and sham groups; the difference in K in M3 between the left and right sides disappeared due to the surgery. Our results have confirmed the hypothesis of inferior alveolar nerve transection having an effect on inorganic components in mandibular molars in the rat.

Effect of Hafnium Coating on Osseointegration of Titanium Implants: A Split Mouth Animal Study

The behaviour of hafnium as surface coating in biological environments has not been studied. Little is known about osseointegration of hafnium-coated titanium implants. Thus, further studies of hafnium coating under biological conditions are required in order to determine the suitability of this material, as a surface coating for biomedical application. The aim of the study is to analyse the difference between hafnium-coated titanium and uncoated titanium by evaluating the osseointegration ability of hafnium metal and mechanism of which promotes better bone integration. The study was conducted with a split mouth design on 16 Wistar Albino rats of both sexes, at the age of 6-7 months, weighing 2526.5 ± 74.4 g . Self-tapping titanium osteosynthesis screws ( 4 mm × 2 mm ) (LeForte System Bone Screw®) were implanted in the mandible of rats: Group A (pure titanium screws, n = 12 ) and Group B (hafnium-coated screws, n = 12 ). The implanted screws’ stability was checked and noted with a specially customised torque apparatus during insertion and removal of implant. The tissue sections were then processed for hematoxylin and eosin and Masson’s trichrome for bone and connective tissue examination, after 4 and 8 weeks of placement. Hafnium coating appears to have offered similar biocompatibility (aspartate transaminase (AST), alanine aminotransferase (ALT), and creatine kinase (CK) enzyme assay), statistically significant improvement (independent Student’s t -test, p &lt; 0.05 ) in insertion torque ( 25.42 ± 3.965 ) and removal torque ( 29.17 ± 2.887 ) than commercially pure titanium with insertion torque ( 22.08 ± .575 ) and removal torque ( 25.42 ± 2.575 ). Hafnium coating in the rat mandible showed promising osseointegration with good tissue biocompatibility. Further human trials of hafnium-coated implants are needed to understand the biological behaviour better to enhance clinical performance.