Pleiotropic effect of intramucosal injection of FTY720 on angiogenesis and tissue healing after free gingival graft surgery: a comparative experimental study in rabbits.

OBJECTIVES: Free gingival graft surgery is the gold standard for increasing the size of keratinized tissue. Blood supply in the recipient site is critical for healing. Therefore, in this study, the effect of FTY720 on angiogenesis, healing, and scar tissue presence following free gingival graft surgery is investigated. MATERIALS AND METHODS: Surgeries were performed on 10 New Zealand white rabbits. Rabbits were randomly assigned to two groups. In the experimental group, immediately after surgery, 2 and 4 days later, FTY-720 was injected into the tissue surrounding the recipient site. In the control group, the same frequency of placebo vehicle was injected. After 30 days, tissue samples were assessed histologically and histomorphometrically. RESULTS: The blood vessel count (P < 0.000) and rete ridge formation (P < 0.05) in the experimental group were significantly higher, while the epithelial thickness was lower in this group (P < 0.000). There was no significant difference in the percentage of regions occupied by collagen fibres between the groups (P = 0.987). Furthermore, a significant and negative relationship between epithelial thickness and blood vessel count was shown (Pearson correlation coefficient = - 0.917). CONCLUSIONS: The findings indicate that the angiogenic effects of FTY-720 in the recipient site of free gingival graft can be employed to promote tissue healing and reduce scar tissue presence. CLINICAL RELEVANCE: A significant decrease in epithelial thickness and increase in angiogenesis as well as rete ridge formation score in the FTY-720 group were shown, which can be translated into improved tissue healing and less presence of scar tissue.

Multi-walled carbon nanotube/hydroxyapatite nanocomposite with leukocyte- and platelet-rich fibrin for bone regeneration in sheep model.

BACKGROUND: The aim of this study was to evaluate the effects of multi-walled carbon nanotubes/hydroxyapatite (MWCNT/HA) granules with or without leukocyte- and platelet-rich fibrin (L-PRF) on bone regeneration in cancellous bone of sheep model. METHODS: Totally, 32 cylindrical holes were drilled in female sheep (n = 4) in the distal epiphysis and proximal metaphysis of right and left humerus and femur. The defects were randomly filled with (1) MWCNT/HA, (2) MWCNT/HA mixed with L-PRF, (3) L-PRF, and (4) left empty as control. After 8 weeks, defects were evaluated and compared radiographically using multi-slice computed tomographic (CT) scan and cone beam CT scans, histologically and histomorphometrically. RESULTS: The results showed that there was no significant inflammation (> 10%) or foreign body reaction around the granules. The new lamellar bone was regenerated around the MWCNT/HA nanocomposite granules. Addition of L-PRF to MWCNT/HA demonstrated significantly improvement of new bone formation, about 27.40 ± 1.08%, in comparison with the L-PRF alone, about (12.16 ± 1.46%) (P < 0.01). Also, the rate of new bone formation was significantly greater with the use of MWCNT/HA granules (24.59 ± 1.54%) compared to the control (10.36 ± 1.17%) (P < 0.01). CONCLUSION: Consequently, both biocompatibility and osteoconductivity of MWCNT/HA nanocomposite were demonstrated in the preclinical sheep model, and the use of L-PRF in combination with MWCNT/HA nanocomposite can improve bone regeneration.

Micronucleus Assay of Buccal Mucosa Cells in Waterpipe (Hookah) Smokers: A Cytologic Study.

BACKGROUND & OBJECTIVE: Micronucleus assay of buccal mucosa cells is a simple bio- monitoring method for diagnosing the genetic damages of toxic agents. The aim was to study the genotoxic effect of waterpipe smoking on buccal mucosa cells using micronucleus assay. METHODS: This was a case control. A total of 30 male waterpipe smokers and 30 non-smokers were included in the study. The exfoliated buccal mucosa cells were scrapped using wooden spatula and were spread over glass slides. The mean number of micronuclei was determined using Feulgen-stained slides. The number of micronuclei per 1000 cells was calculated and compared between the two groups of smokers and non-smokers. RESULTS: The mean number of micronuclei in waterpipe smokers and non-smokers was 1.94±0.39 and 1.68±0.35, respectively. The micronuclei count in waterpipe smokers was significantly higher than non-smokers (P=0). The difference between the number of waterpipe smoking and micronuclei count was significantly different (P=0). CONCLUSION: The mean number of micronuclei in buccal mucosa cells of waterpipe smokers was significantly higher than non-smokers. The genotoxicity effect of waterpipe was dose-dependent.

Oral Health Related Quality of Life of Patients Using Conventional Dentures versus Implant-Supported Overdentures.

OBJECTIVES: This study aimed to compare the oral health related quality of life (OHRQoL) of patients using conventional dentures versus implant-supported overdentures. MATERIALS AND METHODS: This study evaluated the OHRQoL of 90 patients between 35 to 75 years who were selected from several public and private dental clinics in Tehran in 2018. Of all, 45 had conventional dentures of both jaws, and 45 had a mandibular overdenture supported by two implants at the site of mandibular canine teeth and a conventional maxillary denture. The OHRQoL of patients was determined using the Oral Health Impact Prfile-20 (OHIP-20). The questionnaire was translated to Persian, and its content validity and internal consistency were confirmed. Data were analyzed by one-way ANOVA, Mann-Whitney test, and independent t-test. RESULTS: In the conventional denture group, 46.7% had good, 46.7% had moderate, and 6.6% had poor OHRQoL. These values were 55.6%, 37.8% and 6.6% in the overdenture group, respectively. Level of education had a significant correlation with the total score of OHIP-20 in both groups (P<0.05). But no significant association was noted between the residential status and gender of patients with different domains of OHRQoL (P>0.05) except for the psychological disability domain, which had a higher mean value in males with conventional dentures (P<0.05). CONCLUSION: Patients with a mandibular overdenture supported by two implants at the site of canine teeth and a conventional maxillary denture had higher OHRQoL than patients with conventional dentures of both jaws.

A collagen-based hydrogel containing tacrolimus for bone tissue engineering.

Bone tissue engineering aims to develop bone graft structure that can heal bone defects without using autografts or allografts. The current study was conducted to promote bone regeneration using a collagen type I hydrogel containing tacrolimus. For this purpose, different amounts of tacrolimus (10 µg/ml, 100 µg/ml, and 1000 µg/ml) were loaded into the hydrogel. The resulting drug-loaded hydrogels were characterized for their porosity, swelling capacity, weight loss, drug release, blood compatibility, and cell proliferation (MTT). For functional analysis, the developed hydrogel surrounded by a film made of gelatin and polycaprolactone (PCL) was administrated in the calvarias defect of Wistar rats. The results indicated that the hydrogel has a porosity of 89.2 ± 12.5% and an appropriate swelling, drug release, and blood compatibility behavior. The in vitro results indicated that the collagen hydrogel containing 1000 µg tacrolimus was adequate in terms of cell proliferation. Finally, in vivo studies provided some evidence of the potential of the developed hydrogel for bone healing.

Fabrication and characterization of collagen-hydroxyapatite-based composite scaffolds containing doxycycline via freeze-casting method for bone tissue engineering.

In this study, hydroxyapatite nanoparticles containing 10% doxycycline, a structural isomer of tetracycline, was prepared by the co-precipitation method. It was added to collagen solution for the preparation of the scaffold with freeze-casting method in order to develop a composite scaffold with both antibacterial and osteoinductive properties for repairing bone defects. The scaffolds were evaluated regarding their morphology, porosity, degradation and cellular response. The scaffolds for further investigation were added in a rat calvaria defect model. The study showed that after eight weeks, the bone formation was relatively higher in the collagen/nano-hydroxyapatite/doxycycline group with completely filled defect when compared with other groups. Histopathological evaluation showed that the defect in the collagen/nano-hydroxyapatite/doxycycline group was fully replaced by the new bone and connective tissue. Our results provide evidence supporting the possible applicability of doxycycline-containing scaffolds for successful bone regeneration.

Histologic and histomorphometric evaluation of bone regeneration using nanocrystalline hydroxyapatite and human freeze-dried bone graft : An experimental study in rabbit.

PURPOSE: Bone regeneration is an important concern in periodontal treatment and implant dentistry. Different biomaterials and surgical techniques have been used for this purpose. The aim of the present study was to compare the effect of nanocrystalline hydroxyapatite and human freeze-dried bone graft (FDBG) in regeneration of rabbit calvarium bony defects by histologic and histomorphometric evaluation. METHODS: In this experimental study, three similar defects, measuring 8 mm in diameter, were created in the calvaria of 16 white New Zealand rabbits. Two defects were filled with FDBG and nanocrystalline hydroxyapatite silica gel, while the other one remained unfilled to be considered as control. All the defects were covered with collagen membranes. During the healing period, two animals perished; so 14 rabbits were divided into two groups: half of them were euthanized after 6 weeks of healing and the other half after 12 weeks. The specimens were subjected to histologic and histomorphometric examinations for assessment of the following variables: percentage of bone formation and residual graft material, inflammation scores, patterns of bone formation and type of newly formed bone. RESULTS: The percentages of new bone formation after 6 weeks were 14.22 ± 7.85, 21.57 ± 6.91, and 20.54 ± 10.07% in FDBG, NanoBone, and control defects. These values were 27.54 ± 20.19, 23.86 ± 6.27, and 26.48 ± 14.18% in 12-week specimens, respectively. No significant differences were found in the amount of bone formation between the groups. With regard to inflammation, the control and NanoBone groups showed significantly less inflammation compared to FDBG at the 6-week healing phase (P = 0.04); this difference was not significant in the 12-week specimens. CONCLUSIONS: Based on the results of this experimental study, both NanoBone and FDBG exhibited a similar effect on bone formation.

Evaluating the bone regeneration in calvarial defect using osteoblasts differentiated from adipose-derived mesenchymal stem cells on three different scaffolds: an animal study.

The aim of this study was to investigate the effect of three different scaffolds on the viability and differentiation of adipose-derived mesenchymal stem cells (ADMSCs) to osteoblast for bone regeneration of calvarial defect in rabbit model. Adipose was harvested from the nape of 12 rabbits by direct surgery or hollow-tip cannula. Two standardized circular calvarial defects (case and control), 8 mm in diameter each, were created in all the animals. The animals were divided into 3 different groups. In group 1 (G1), the defect was filled with polyamide + ADMSC. In group 2, poly lactic-co-glycolic acid + ADMSC was used. In group 3, decellularized amniotic membrane + ADMSC was applied. In the control defect, the non-seeded scaffolds were applied for filling the defect. Decellularized pericardial scaffolds were used as a membrane on the scaffolds. The animals were euthanized 2, 4, and 8 weeks of operation and new bone formation was assessed by different analyses. Immunohistochemical (IHC) staining with osteopontin and osteocalcin antibodies was also performed. After 2 weeks of wound healing, minimal bone regeneration was detected in all groups. Almost complete defect closure was observed in all experimental groups after 8 weeks of operation, with the greatest defect closure in the animals treated with polyamide scaffolds as compared to biopsies obtained from control defects and other experimental groups. The maximal tensile load was higher in G1, 4 and 8 weeks postoperatively, suggesting the usefulness of polyamide + ADMSC for bone regeneration in calvarial defects. Results of the IHC staining demonstrated a significant difference between seeded and non-seeded scaffold in both short- and long-term follow-ups (P < 0.05). In addition, a significant difference was observed in enhancement of IHC staining of both markers in polyamide group (seeded or non-seeded) 4 and 8 weeks postoperatively in comparison with other scaffolds. It was concluded that bone regeneration in critical calvarial defect was more successful in seeded polyamide.

The Impact of Smoking on Gingiva: a Histopathological Study.

BACKGROUND AND OBJECTIVE: Smoking can be associated with the decreasing gingival blood flow and epithelial changes. The aim of this study was to evaluate the histopathological changes of gingival epithelium and connective tissue in smokers . METHODS: The study was case-control. Sixty male patients ( 28 smokers and 32 non smokers) suffering chronic periodontitis were participated in the study . Periodontal parameters consisting the gingival (GI) and periodontal (PI) indexes were registered. Tissue samples were taken during flap surgery. The hemotoxylin and eosin stained slides were assessed for blood vessel density, inflammatory cells infiltration and epithelial changes. The histopathological findings were compared between smokers and nonsmokers. Data analyzed using t -test and chi-square tests. RESULTS: Smokers had lower GI (1.35 ± 0.48) and higher PI (2.87±0.68) than nonsmokers (2.72 ±0.31 and 1.87±0.25, respectively). The mean count of blood vessels with ≤ 0.5µ diameter was 18.78±10.06 and 5.90±2.93 in smokers, nonsmokers, respectively. The mean inflammatory cells infiltration in smokers, and nonsmokers were 0.89±1.03 and 70±0.46 that showed significant difference between two groups ( P = 0.001, SD=1.21). The difference of epithelial hyperkeratosis, atrophy and acanthosis was not different in smokers and nonsmokers. Loss of normal epithelium pattern comprising of bulbous rete ridges, loss of polarity and increased parabasal cells was seen in 23(82.14%) of smokers and 2(6.25%) of nonsmokers. CONCLUSION: Despite the normal appearance of gingiva in smokers, smoking increasing the epithelial changes resemble to early phases of dysplasia and decreasing inflammatory reaction.

Bilateral mandibular supernumerary canines: a case report.

Supernumerary teeth are defined as the teeth developed in excess of the number found in a normal dentition. Supernumerary canine is an extremely rare finding particularly in the mandible. This case report presents a 25-year-old female patient with the unique feature of bilateral mandibular supplemental supernumerary canines. The patient was non-syndromic without any other supernumerary teeth.