Use of bioactive glass doped with magnesium or strontium for bone regeneration: A rabbit critical-size calvarial defects study.

Background: This study aimed to evaluate the amount of bone regeneration in critical defects of rabbit calvaria filled with magnesium- and strontium-doped bioactive glasses. Materials and Methods: In this rabbit critical-size calvarial defects study, 12 male New Zealand white rabbits were randomly divided into two groups. On the calvaria of each rabbit, four lesions (two lesions in the frontal bone and two lesions in the peritoneal bone) were created with a diameter of 8 mm spaced apart. Each lesion was filled in with (1) strontium-doped bioactive glass, (2) magnesium-doped bioactive glass, (3) 45S5 bioactive glass, and (4) empty lesion (control). Six rabbits were sacrificed at the end of 4 weeks, and six rabbits were randomly sacrificed at the end of 8 weeks. Bone sections with a 5-µ thickness of rabbit calvary bone were prepared, and the percentage of new bone, connective tissue, and residual material were calculated in microscopic images. Statistical analysis was performed by two-way ANOVA and Bonferroni additional tests, and the level of significance was set at P < 0.05 in all categories. Results: At 4 weeks, magnesium-doped bioactive glass showed the highest new bone formation with a mean of 11.66 ± 2.64, followed by the strontium-doped bioactive glass with the mean of 11.10 ± 1.69 (P = 0.0001). While at week 8, the highest amount of new bone observed in the strontium-doped group with a mean of 28.22 ± 3.19, and then, the magnesium-doped bioactive glass with a mean of 22.55 ± 3.43 (P = 0.0001). Conclusion: Doping strontium and magnesium in the structure of bioactive glasses increases new bone regeneration in comparison with 45S5 bioactive glass.

Dental Implants in Sjögren Syndrome.

Sjögren's syndrome (SS) is a complex autoimmune disease that predominantly affects the exocrine glands, notably the salivary and lacrimal glands, resulting in dryness of the mucosa recognized as xerostomia. Chief oral complications reported by patients consist of high caries rate, burning sensation of the mucosa, early tooth loss, intensified tooth wear and repetitive failure of dental restorations. In particular, due to the decreased salivary flow, conventional removable prostheses might irritate the mucosa and lead to painful ulcerations at the borders of the denture. Implant-supported prostheses offer a unique solution to the difficulties experienced by edentulous patients with Sjögren's syndrome. This research showed no signs of peri-implantitis or peri-implant mucositis during 7-years following the placement of implants. The present study indicates that successful long-term maintenance of dental implants can be also achieved in SS patients.

Histologic Evaluation of the Bone Regeneration Capacities of Bio-Oss and MinerOss X in Rabbit Calvarial Defects.

Several methods are used for periodontal regeneration and alveolar ridge reconstruction. This study aimed to compare the bone regeneration capacities of MinerOss X, Bio-Oss, and autograft in rabbit calvaria. In this animal study, four defects measuring 8 mm in diameter were created in the calvaria of 10 rabbits using a trephine bur. Three defects were randomly filled with MinerOss X, Bio-Oss, and autogenous bone. The fourth defect remained empty as a control. The rabbits were sacrificed after 4 or 8 weeks. Calvarial samples were taken and histopathologically evaluated. The mean number of osteoblasts and the amount of newly formed bone in all groups were higher at 8 compared to 4 weeks. At 4 and 8 weeks, the amount of newly formed bone and number of osteoblasts and osteocytes in MinerOss X group were significantly greater than the corresponding values in other groups, and MinerOss X was superior to Bio-Oss and autograft in all the assessed variables at both 4 and 8 weeks (P < .001). Within the limitations of this study, the results showed that the number of osteoblasts and osteocytes and the amount of newly formed bone in the MinerOss X group were higher than those in Bio-Oss and autograft groups. However, further clinical studies are warranted.

NMDA receptor subunits change in the prefrontal cortex of pure-opioid and multi-drug abusers: a post-mortem study.

Addiction is a chronic relapsing disorder and is one of the most important issues in the world. Changing the level of neurotransmitters and the activities of their receptors, play a major role in the pathophysiology of substance abuse disorders. It is well-established that N-methyl-D-aspartate receptors (NMDARs) play a significant role in the molecular basis of addiction. NMDAR has two obligatory GluN1 and two regionally localized GluN2 subunits. This study investigated changes in the protein level of GluN1, GluN2A, and GluN2B in the prefrontal cortex of drug abusers. The medial prefrontal cortex (mPFC), lateral prefrontal cortex (lPFC), and orbitofrontal cortex (OFC) were dissected from the brain of 101 drug addicts brains and were compared with the brains of non-addicts (N = 13). Western blotting technique was used to show the alteration in NMDAR subunits level. Data obtained using Western blotting technique showed a significant increase in the level of GluN1 and GluN2B, but not in GluN2A subunits in all the three regions (mPFC, lPFC, and OFC) of men whom suffered from addiction as compared to the appropriate controls. These findings showed a novel role for GluN1, GluN2B subunits, rather than the GluN2A subunit of NMDARs, in the pathophysiology of addiction and suggested their role in the drug-induced plasticity of NMDARs.

Formation of biofilm on various implant abutment materials.

The characteristics of prosthetic implant components, such as the type, material, and surface roughness of abutments, can affect biofilm formation. Since an ideal abutment surface for the reduction of bacterial adhesion has yet to be found, this in vitro study aimed to quantify biofilm formation on laser-treated titanium, zirconia, and titanium surfaces. Sterile titanium, zirconia, and laser-treated titanium discs were placed in sterile 48-well plates. Biofilm formation was induced by adding sterilized, unstimulated human saliva and suspensions of Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), and Prevotella intermedia (Pi) to the wells. Viable bacteria in the biofilm were quantified with real-time polymerase chain reaction in conjunction with propidium monoazide. The disc material, the type of bacteria, and their interactions had significant effects on the bacterial counts. On all surfaces, the Pg count was significantly higher than both the Pi and Aa counts (P = 0.0001). The highest count of periodontal pathogens was found on laser-treated surfaces. The second highest and the lowest counts were found on zirconia and titanium surfaces, respectively.

Successful Implant Placement in a Case of Florid Cemento-Osseous Dysplasia: A Case Report and Literature Review.

Florid cemento-osseus dysplasia (FCOD) has been described as a reactive process in which normal bone is replaced by fibrous connective tissues and cementum-like materials. Radiographically it appears as dense, lobulated masses, often occurring bilaterally with symmetric involvement. In this case report, a successful implant placement has been reported in a 62-year-old Caucasian woman with a chief complaint of mandibular partial edentulous. Radiographic images showed the bilateral radiopaque lesions in edentulous regions of mandible, and mandibular anterior teeth alike. All mandibular teeth were vital and no root resorption was detected. The findings of X-ray images were attributable to FCOD. A highly conservative step-by-step 2-stage implant surgery was performed. After 6 months the implants loaded with fixed prosthesis. 2, 4, 6, 12, and 18 months after the surgery radiographic images were taken, which revealed an optimal functional rehabilitation and complete integration of implants. This report confirms that treating the edentulous area near the FCOD lesions could be planned, if conservative step- by-step implant placement been considered. To the best of our knowledge, a case of FCOD with successful implant placement has not been reported previously. More studies in more patients are needed to confirm results of such a therapeutic modality.

Do we need keratinized mucosa for a healthy peri-implant soft tissue?

The presence of keratinized mucosa plays a fundamental role in peri-implant soft tissue health. This study assessed the impact of the width of keratinized mucosa (WKM) on peri-implant soft tissue parameters. A cross-sectional study was conducted on 110 bone-level implants in 36 patients. A minimum of 6 months had passed since the loading of implants, and the patients had at least 1 implant in 1 quadrant at the molar or premolar site restored with a single crown or fixed partial denture. The health of peri-implant soft tissue was assessed with a modified bleeding index (MBI), modified plaque index (MPI), and modified gingival index (MGI). Probing depth (PD), gingival recession (GR), and WKM were also measured. History of smoking and oral hygiene methods were recorded. A significant inverse correlation existed between WKM and the parameters MBI, MPI, MGI, and GR (P < 0.05). Values of MBI, MPI, MGI, and GR were significantly lower in areas with WKM ≥ 2 mm and higher in areas with WKM < 2 mm (P < 0.05). The WKM was greatest in subjects using the vibratory toothbrushing technique and narrowest in those using the horizontal toothbrushing technique (P < 0.05). The mean WKM was significantly greater in smokers than in nonsmokers (P < 0.05). Results of this study indicate that an association exists between WKM and peri-implant soft tissue health. A minimum of 2 mm of keratinized mucosa around implants is recommended.

Morphology, proliferation, and gene expression of gingival fibroblasts on Laser-Lok, titanium, and zirconia surfaces.

Soft tissue seal plays a critical role in long-term success of dental implants, and the effects of implant surface treatments such as laser ablation have been a topic of particular interest in this respect. Considering the existing controversy regarding soft tissue behavior in contact with implant surfaces, this study sought to assess the morphology, proliferation, and gene expression of human gingival fibroblasts (HGFs) on different abutment surfaces. In this in vitro, experimental study, HGFs were cultured on 45 discs (Laser-Lok, titanium, and zirconia). Cell morphology, proliferation rate, and interleukin 10 (IL-10), tumor necrosis factor alpha (TNFα), fibronectin, and integrin gene expressions were assessed by electron microscopy, methyl thiazol tetrazolium (MTT) assay, and real-time polymerase chain reaction (PCR), respectively. Data were analyzed using ANOVA and the Kruskal-Wallis H test. Fibroblast attachment was noted in all the three groups. Spindle-shaped cells with pseudopod-like processes were more frequently seen in the Laser-Lok group. Cell proliferation was significantly higher in the Laser-Lok group compared to those in the other groups (P = 0.0002). Significant differences were found in the expression of IL-10, TNFα, fibronectin, and integrin genes among the groups (P < 0.01). Within the limitations of this study, HGFs on Laser-Lok surfaces had a more mature morphology and greater proliferation and differentiation as compared to those on zirconia and titanium surfaces. This indicates better attachment of these cells to laser-modified surfaces, creating a more efficient soft tissue seal around dental implants.

Correlation Between Bone and Soft Tissue Thickness in Maxillary Anterior Teeth.

OBJECTIVES: The purpose of this study was to determine buccal bone and soft tissue thicknesses and their correlation in the maxillary anterior region using cone beam computed tomography (CBCT). MATERIALS AND METHODS: In this cross sectional study, 330 sound maxillary incisors in 60 patients with a mean age of 37.5 years were assessed by CBCT scans. For better visualization of soft tissue, patients were asked to use plastic retractors in order to retract their lips and cheeks away from the gingival tissue before taking the scans. Measurements were made in three different positions: at the crest and at 2 and 5mm apical to the crest. The cementoenamel junction-crest distance was measured. for data analyses, the Pearson's correlation coefficient, ANOVA and intraclass correlation coefficient were used. RESULTS: There were mildly significant linear associations between labial soft tissue and bone thickness in the canines and incisors (r<0.40, P<0.05), but no association was found for the lateral incisors. The mean thickness of buccal bone differed significantly in the maxillary anterior teeth, being greater for the lateral incisors (P<0.05). For soft tissue thickness, the results were the same, and the least thickness was recorded for the canines. There was a mild association between labial soft tissue and bone thickness in canines and incisors (r=0.2, P=0.3), but no such linear association was seen for the lateral incisors. CONCLUSIONS: The mean thickness of buccal bone and soft tissue in the anterior maxilla was <1mm and there was a mild linear correlation between them.

Correlation between bone mineral density of jaws and skeletal sites in an Iranian population using dual X-ray energy absorptiometry.

BACKGROUND: The aim of the present study was to evaluate the relationship between the bone density of various regions of jaws and skeletal bones. MATERIALS AND METHODS: A total of 110 patients with a mean age of 55.01 ± 10.77 years were selected for the purpose of the present descriptive study. Dual X-ray Energy Absorptiometry (DXA) was carried out to determine bone mineral density (BMD) of the femur and lumbar vertebrae. Then all the subjects underwent DXA of the jaw bones and BMD values were determined at four jaw regions. Data were analyzed by SPSS 16 statistical software, and the correlation between the various BMD values was determined by Pearson's correlation coefficient. RESULTS: The results showed that 42.7% of females had normal BMD values in the femur, and in vertebrae, 20% were osteopenic and 37.3% suffered from osteoporosis, with statistically significant differences in the BMD values of the jaws between the three above-mentioned groups (P < 0.001). There was an increasing tendency toward osteopenia and osteoporosis with age. There was a positive correlation between BMD values of the femur and lumbar vertebrae and those of all the jaw regions under study (P < 0.005). There was a negative correlation (P < 0.01) between age and the BMD values of the femur, lumbar vertebrae and anterior maxilla. CONCLUSION: The bone density of the maxilla and mandible and presence of osteoporosis or osteopenia in these bones might reflect the same problem in skeletal bones.

Assessing the amount of interdental bone in posterior areas of the mandible for placing orthodontic mini-implants.

Objective : The aim of this study was to assess the amount of interdental bone in posterior areas of the mandible for placing orthodontic mini-implants to provide and control anchorage in orthodontic treatment. Materials and Methods : The amount of interdental bone in areas between the second premolars and first molars, first and second molars on the right and left sides of the mandible were determined in fifty patients by RVG using periapical radiographs. The images were assessed using Cygnus Media Software to determine the mesio-distal width of the interdental bone, starting at the crest of the alveolar bone (2 mm below the CEJ) every one millimeter up to 12 mm from the CEJ. The actual amount of interdental bone and the effect of related factors were assessed using chi-square test at a 95% confidence interval. Results : The minimum desired interdental bone width for placing mini-implants, 3 mm from the CEJ, between the second premolar and first molar and the first and second molars of the mandible on both sides were significantly different (p<0.01): 1.8 mm (31%) more apical in the area between the second premolar and the first molar. There was also a statistically significant difference between the areas under study on the right side (p<0.002), which was 2.2 mm (44%) more apical in the area of the second premolar and the first molar. Conclusion : The most secure site for placing orthodontic mini-implants in the mandible is between the first and second molars at the height of 5.8 mm from the CEJ.

A survey on substance abuse related deaths referred to Tehran's Legal Medicine Organization during 2007 and 2008.

Doubtlessly one of the major problems in Iran is drug abuse or substance abuse. The transmission of HIV/AIDS has made the problem so complicated that has created an urgent need for a campaign against this awful phenomenon. The objective of this study-that was carried out through the cross-sectional method- is considering the situation of the addict death and the related factors. The target population consists of the corpses of the addicts referred to the Legal Medicine Organization of Tehran during 2007 and 2008. The cadavers were examined in the preliminary stage. The blood, urine and the contents of the gall-bladder, stomach and viscera were collected and sent to the toxicology laboratory to examine and find narcotics metabolites and other drugs. The samples of the brain, heart, lungs, liver and kidneys were sent to the pathology laboratories. All of the extracted data were recorded and analyzed using SPSS software. It was diagnosed that 248 cases (79.7%) out of the total 311 in this study, died of substance abuse. Totally 300 cases were reported as male addicts (96.5%). The oldest and youngest addicts were 49 and 17 respectively. The most frequent drugs used were heroin and combination of heroin and opium. No meaningful difference was observed between the death cause of different groups of drug abusers . It seems that the increase in the population of the substance users is the main cause of frequency changes of the addicts' deaths.

Correlation between oral hygiene and Helicobacter pylori infection.

As introduced by different studies, dental plaque is known as a reservoir of Helicobacter Pylori (HP) and a potential source for gastric re-infection. Also, it has been demonstrated that individuals with gastric HP infection manifest a greater plaque index and a higher incidence rate for gingivitis. The goal of the present research was survey of severity and prevalence of periodontal diseases associated with gastric HP infection among patients having referred to the endoscopy wards of Imam Khomeini and Milad hospitals. In this research, 122 patients with gastric HP infection were investigated for determining 4 indices: plaque index (PI), gingival index (GI), clinical attachment loss (CAL) and pocket depth (PD), for all existing teeth, using RUT (rapid urease test). The results indicated that about 86.9% of patients had developed gingivitis of various degrees and 100% of them were afflicted with periodontitis of different degrees, and about 64.8% of patients showed a weak PI, and 61.5% had a low level of education. This low-level education seen in majority of the studied subjects, addresses a high degree of importance and influence of the oral hygiene in gastric HP infections. Hence, gastroentrologists are required to refer patients to dentists in line of preserving oral and dental health.