AIM: To evaluate early bone loss around three different implant systems (Straumann Bone Level. Noble Biocare Replace, 3i Biomet Certain) and compare them to each other in a prospective clinical study using clinical and radiographic measurements. MATERIALS AND METHODS: Twenty-three patients were recruited for the study. Three implant systems were included in study design; one system was abandoned due to lack of subjects. Two implant systems (Nobel Biocare Replace n= 12, Straumann Bone Level n= 11) were evaluated. Periodontic residents placed the implants. Radiographic and clinical measurements were obtained at two different time points, at the time of implant placement and at the time of second stage surgery. RESULTS: Mean clinical bone loss was 0.14 ± 0.20 mm, and 0.72 ± 1.02 mm for Straumann and Nobel Biocare respectively. The mean change in the radiographic bone loss for Straumann and Nobel Biocare was 0.23 ± 0.26 mm and 0.53 ± 1.06 mm. There was no statistically significant difference between the two groups. CONCLUSION: Nobel Biocare Replace tapered implants showed a two and five times higher average bone loss in radiographic and clinical parameters respectively, compared to Straumann implants. However, this difference did not reach statistical significance in either the clinical or the radiographic measurement. It is suggested that study size should be increased.

Since the endodontic files were introduced in the late 1980s, NiTi showed enhanced performance in root canal instrumentation when compared to stainless steel files. It was reported that NiTi files had a higher tendency to break inside root canals compared to stainless steel files. The aim of this research was to evaluate the cutting efficiency and the cyclic fatigue of Protaper® endodontic files and EndoSequence® endodontic files when their surface character was modified through coating the files with two types of silanes, as “dry” lubricants. The first coating was Octadecylsilane and the second was (3- Hepta-fluoroisopropoxy)propylsilane. Each file type was devided into 3 groups. A specially designed platform was made to test the cutting efficiency of 120 edodontic files in custom made epoxy resin blocks using a universal testing machine and an endodontic motor. The files rotated at 300rpm and were introduced into the blocks at 10mm/minute. Weight of the blocks was measured before and after testing and weight difference was recorded, maximum and minimum load that the files were subjected to during testing were measured and load difference was recorded. In the second part of this research 72 files were tested for cyclic fatigue in a specially designed platform that was built for this purpose. Files were tested with water flowing through a bent glass tube to flush away any resulting debris generated during testing. Files were rotated inside the tubes at 300rpm. Time to fracture, length of broken parts was recorded, and maximum strain amplitudes (MSA) were calculated. Broken files were examined under scanning electron microscope (SEM) to evaluate their broken edges. The results did not show significant difference in cutting efficiency between groups, this is acceptable since the coating was considered a monomolecular layer limited to the surface of the files, with no changes to the core properties or the cross section of the files. Results also did not show significant difference in the number of cycles to failure or length of broken part between the groups. EndoSequence® files broke at lower MSA than Protaper® files, because of the thinner diameter at which EndoSequence® files failed.

OBJECTIVES: To investigate the effect of different ceramic powders on the microstructure, biaxial flexural strength, hardness and absorption coefficient of resin-infused zirconia and alumina, to investigate the effect of sintering temperatures on the microstructure, biaxial flexural strength, hardness and absorption coefficient of resin-infused spinel, and to investigate the effect of cyclic fatigue on biaxial flexural strength of resin-infused ceramics. MATERIALS: Resin-infused zirconia, resin-infused alumina and resin-infused spinel METHODS: Zirconia powders (TOSOH TZ and Zpex) and alumina powders (Almatis and Taimei) were dry-pressed in a stainless steel mold to fabricate ceramic discs. Discs were sintered to 1050°C. McMaster-Carr partially sintered alumina rod was cut into discs of 1.5 mm thickness. Ceranova spinel discs were divided into two groups sintered at two different temperatures (1250°C and 1350°C). Density of each disc was measured and a total of 8 discs per group were prepared. Specimens were silane treated, and then infused with an UDMA mixture under vacuum. Infused specimens were cured with an Isopress machine at pressures of 20,001 psi. Biaxial flexural strength was measured using an Instron Universal Testing machine at 0.5 mm/min crosshead speed. Another group was subjected to cyclic fatigue (50,000 cycles) before biaxial flexural strength test. Hardness was tested using vickers microhardness indenter (Buehler Micromat 2003). Spectrophotometer was used for direct transmission measurements and absorption coefficient was calculated. Microstructure of each group was investigated with a scanning electron microscope (SEM). The data were analyzed using one-way ANOVA and Tukey multiple comparisons. T-test was used to compare biaxial flexural strength of each group before and after cyclic fatigue. RESULTS AND CONCLUSIONS: Using different ceramic powders had no significant effect on the biaxial flexural strength and absorption coefficient of resin-infused zirconia. Resin-infused Zpex zirconia had significantly greater microhardness than resin-infused Tz zirconia. Resin-infused MCM alumina had significantly greater biaxial flexural strength than resin-infused Almatis alumina. Resin-infused MCM and Taimei alumina had significantly greater microhardness than resin-infused Taimei alumina. Resin-infused Almatis alumina had significantly greater absorption coefficient than resin-infused Taimei alumina. Cyclic fatigue had significantly reduced the biaxial flexural strength of resin-infused Tz zirconia, Almatis alumina and spinel 1250 but had no significant effect on the rest of the groups. Increasing sintering temperature of resin-infused spinel from 1250°C to 1350°C had no significant effect on biaxial flexural strength and absorption coefficient but it significantly increased the microhardness. / 2019-09-26T00:00:00Z

Sjogren’s syndrome (SS) is a chronic autoimmune disease, that affects primarily salivary and lacrimal glands, leading to increased morbidity. Recent studies indicate that loss of salivary gland function is associated with defective cell polarity, lymphocytic infiltration and fibrosis. Our previous studies showed that deregulation of E-cadherin-mediated adhesion was associated with nuclear localization of YAP and suggested that the latter may be a key event in SS. In this study, our goal was to align altered morphological features in SS with cell polarity regulators. Specifically, we focused on the Par complex, known to play an important role in epithelial polarity, as well as components of tight junctions (TJs), ZO-1 and JAM-1, and compared them to changes in their expression and localization with markers of fibrosis, vimentin and α-smooth muscle actin (α-SMA). Using immunofluorescence staining and confocal microscopy we examined expression levels of YAP, Par3, ZO-1, JAM-1, vimentin, and α-SMA, and correlated them with a ductal differentiation marker K7 and a marker for lymphocytic infiltration, CD45+. Our results showed reduced levels of Par3, ZO-1 and JAM-1, in tissues from SS patients that were associated with increased nuclear localization of YAP. Collectively, these studies suggest that cell polarity cues are critical for normal function of salivary glands and that their deregulation is likely to be the underlying basis of at least a subset of SS patients. These findings will further contribute to a better understanding of the molecular basis of SS and will serve in improved diagnosis and future therapeutic intervention.

Ligaments serve as compliant connectors between hard tissues. In that role, they function under various load regimes and directions. However, the 3D structure of ligaments is still considered uniform. The periodontal ligament connects the tooth to the bone and like other ligaments, it sustains different types of loads in various directions. Using the PDL as a model, and employing a fabricated motorized set-up in a microCT instrument, morphological automated segmentation methods and 2nd harmonic generation imaging, we demonstrate that the fibrous network structure within the PDL is not uniform, even before the tooth becomes functional. We find that areas sustaining compression loads are pre-structured with sparse collagenous networks and large blood vessels, whereas other areas contain dense collagen networks with few blood vessels. Therefore, the PDL develops as a non-uniform structure, with an architecture designed to sustain specific types of load in different areas. Based on these findings, we propose that ligaments in general should be regarded as non-uniform entities structured for optimal functioning under variable load regimes. / 2019-09-26T00:00:00Z

OBJECTIVES: To quantitate and analyze casein and gluten-degrading protease activities produced by natural inhabitant oral microorganisms in human saliva, and to isolate new gluten-degrading oral species. METHODS: Whole saliva samples were collected from visitors to the Museum of Science in Boston, MA. At total of 769 samples were collected and sample number, subject age, race, gender and dietary habits with regard to gluten consumption were reported. At least 1 ml of saliva was collected from each subject and the samples were aliquoted into several 150 µl aliquots. To one of the aliquots 150 µl 80% BHI/20% glycerol was added to preserve the microbes. Enzyme activity analysis was conducted on pre-cast casein and zymogram gels. After electrophoresis, gels were renatured and developed, and enzyme activities were visualized and analyzed. Protease activity in each sample was evident from well-defined bands in the gels resulting from casein digestion. Enzyme activities were quantitated within the 75-150 kDa region and compared among subjects. Based on this value, subjects were grouped into displaying high, medium, low or negligible enzyme activity. Lastly, saliva aliquots from four selected subjects were plated for bacteria isolation and characterization of enzyme activities on a gliadin zymogram gel. RESULTS: The average overall salivary enzymatic activity among the various race groups was in the order of other/mixed race > Caucasian > Asian > African American > Hispanics, where the Other/mixed race group showed statistically significantly higher values than any of the other race groups. With respect to age, the overall enzymatic activity was in the order of 7-12 > 31-54 > 55-80 > 13-18 > 19-30 age group. As for the gender groups, no statistically significant differences were found in activities between males and females. A good consistency was observed in banding patterns between saliva samples analyzed on a casein zymogram and a gliadin zymogram gel, indicating that the same enzymes act on both substrates. From four selected donors showing unusual and/or high salivary enzyme activities, 12-15 individual salivary bacterial strains were cultured to purity, and analyzed individually on a zymogram gel. Among these, some showed proteolytic activity ~75 kDa, and were suspected to be Rothia bacteria based on previous studies. Others showed activity in high or low MW regions indicating different and potentially novel species of oral gluten degrading bacteria. CONCLUSION: This large scale study has provided insights into the extent and inter-subject variation of salivary enzyme activities, and the apparent molecular weights of the major enzymes involved. It furthermore showed conclusively that gliadin-degrading enzyme activity is present in saliva, and that casein is a good substitute substrate for investigating such activities. Novel gluten-degrading oral species were isolated. Their enzymes could potentially be further explored for aiding in the digestion of gluten in vivo as a means to treat patients suffering from gluten-intolerance disorders

Immature permanent teeth may develop pulpal pathosis due to caries or trauma and preserving these young teeth is quintessential. The general consensus for clinical treatment of immature teeth with non-vital pulps is Apexification. However, this treatment modality does not result in further root development and increase incidence of root fractures in teeth after apexification. Regenerative Endodontics has been defined as biologically based procedures designed to replace damaged structures such as dentin, root structures, and cells of the pulp-dentin complex. The advantages of pulp revascularization lie in the possibility of further root development and reinforcement of dentinal walls by deposition of hard tissue, thus strengthening the root against fracture. This retrospective study evaluated treated cases by regenerative endodontic procedures performed by Endodontists/endodontic residents in the United States/Canada with a minimum of 1-year recall. The participating Endodontists evaluated the regeneration success parameters as defined by the AAE and filled out a Data Collection Form for each patient. 27 of the 28 submitted cases showed absence of clinical symptoms and apical resolution of pathology at the time of one year follow up; 19 cases showed increase in the root width; 15 cases showed increase in the root length; However none of the cases showed any positive response to pulp vitality tests. The results obtained are promising and prove that pulp regeneration/revascularization is indeed a viable treatment option. Further investigation should be considered with a larger sample size for a valid statistical analysis.

OBJECTIVE: To evaluate access and utilization of both preventive and other dental care services among Children with Special Health Care Needs (CSHCN) in the US in 2005 and 2009. METHODS: We analyzed data for 81,082 CSHCN from the National Survey of Children with Special Health Care Needs (NS-CSHCN) 2005 and 2009. The three main dependent variables were: access to and utilization of dental care, and health insurance status. The independent variables were: gender, age, race/ethnicity, type of insurance, number of criteria met on the screener tool, federal poverty level (FPL), family structure, language, family work life, financial burden and out-of-pocket expenses. Bivariate and multivariate weighted analyses were conducted to evaluate the study outcomes. RESULTS: We found that CSHCN had a high degree of access and utilization of the dental care system in the US. In 2005, 98.2% and 99.03% of CSHCN had “very good to good” access to preventive dental care and other dental care, respectively, and in 2009, the access was 98.1% and 98.7% for both services, respectively. Further, in 2005, 92.9% and 90.4% “fully utilized” preventive dental care services and other dental care, respectively, while 91.9% and 84.7% of CSHCN “fully utilized” both services respectively in 2009. Barriers to access dental care were commonly seen among CSHCN of an older age (5-17 years old), other Non-Hispanics, those from low-income families, with complicated health conditions, living with single mothers, who were uninsured or publically insured, and having family out-of-pocket expenses of more than $250 for their health services. Low levels of utilization were found among non-Hispanic Blacks, Hispanics and other Non-Hispanics CSHCN, from low-income families, with complicated health conditions, who were uninsured or publically insured, having family out-of-pocket expenses of more than $250 for their health services and had other unmet specialist care needs. Hispanic CSHCN from low-income families were more likely to be uninsured. Family work life and family financial status were both significantly associated with access and utilization of dental care services in 2005 and 2009. CONCLUSION: Although the results of this study show that, in 2005 and 2009, CSHCN accessed and utilized both preventive and other dental care services at a high level, disparities still exist among some CSHCN.

PURPOSE: The objective of this study was to examine the association between oral hygiene home care habits and cardiovascular (CVD) mortality. METHODS AND MATERIALS: This study involved the secondary analysis of data from an 18 year follow up prospective cohort study of 506 participants with approximately 50.6% of them having CVD. Logistic regression model was used to compare their exposure OH scores, which includes brushing, flossing, use of mouthwash and electronic tooth brush, and were regressed to observed outcome, in relation to CVD mortality. RESULTS: In the multiple regression model a significant association was observed between OH scores and cardiovascular disease (CVD) mortality (p = 0.004) as well as independent association with flossing in particular (p = 0.03). Conclusion: Oral hygiene and oral health are key components to overall systemic health, and have an important impact on CVD outcome. Oral hygiene, home care flossing in particular, has an independent association in acting as a risk factor for CVD mortality.

Dental caries has affected humans for millions of years and even today is present in a large portion of the world’s population. There are several factors that can cause tooth decay, but one of the main reasons is sugar consumption. As bacteria inside our oral cavity break down the carbohydrates and sugars we eat, they produce acid that seeps into the grooves and pits of our teeth and cause demineralization of the enamel. Subsequently, the enamel structure and composition is compromised and if left untreated for long enough, caries develop and can affect the dentin and pulpal layers, which contain the nerves and blood vessels, underneath the enamel. Dentists restore dental caries by removing the decayed portions and filling the cavity with amalgam or composite material to mimic the dental anatomy that was present before. Fortunately, caries can be prevented with regular oral hygiene such as brushing and flossing as well as sealants, especially in children, that can prevent pit and fissure caries in the molars. Additionally, saliva acts as a pH buffer in our mouths to reduce the acidity caused by the bacteria and the fluoride in our drinking water and toothpastes assists in the remineralization process. With all the factors involved in dental caries, research is important in broadening our knowledge of the disease. In order to conduct a study on caries, a researcher can choose to create a caries simulation model in a laboratory setting or use patients in a clinic setting. Each method has advantages and disadvantages. Choosing a model can also depend on the research question, budget, or time. The simplest model is the in vitro chemical demineralization model, in which researchers place teeth or slides of enamel or dentin into an acidic gel or solution for a specific time period before measuring the amount of demineralization that has occurred. The advantages of this model are that it is inexpensive, easily reproducible, and studies can be completed within a reasonably short time frame. The in vitro bacterial biofilm model uses several different species of bacteria that are commonly found during biofilm formation process in order to generate the type of acid that would be present in the oral environment. Although the biological in vitro model is more clinically relevant than the chemical in vitro model, one of its main disadvantages is that unlike the chemical in vitro model, there is no way for remineralization to occur because the biofilm cannot be removed and reapplied periodically. In vivo studies are typically conducted on teeth in living patients and are usually the last step used in product testing. In situ studies offer scientists a compromise between in vitro and in vivo studies in regards to its cost, duration, and clinical relevance. In this type of study, patients wear a dental appliance that contains test samples for a predetermined amount of time. The benefit of this design is that researchers have access to an active oral microcosm present in the oral cavity. Typically, clinical trials are carried out after extensive experimentation in the laboratory. In situ studies offer a middle ground between bench and clinical research models. The purpose of this study was to explore the existing models used for caries simulation and determine whether a standardized model can be developed that can be used for future research on dental caries. After reviewing the literature, there was no conclusive evidence that any one model would suffice for all types of experiments. Researchers should continue to use the most appropriate model for their particular study with the in situ model offering a compromise between in vitro and in vivo models.