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Journal of Periodontology Jun 2016Multiple variables have been shown to affect early marginal bone loss (MBL). Among them, the location of the microgap with respect to the alveolar bone crest, occlusion,... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Multiple variables have been shown to affect early marginal bone loss (MBL). Among them, the location of the microgap with respect to the alveolar bone crest, occlusion, and use of a polished collar have traditionally been investigated as major contributory factors for this early remodeling. Recently, soft tissue thickness has also been investigated as a possible factor influencing this phenomenon. Hence, this study aims to further evaluate the influence of soft tissue thickness on early MBL around dental implants.
METHODS
Electronic and manual literature searches were performed by two independent reviewers in several databases, including Medline, EMBASE, and Cochrane Oral Health Group Trials Register, for articles up to May 2015 reporting soft tissue thickness at time of implant placement and MBL with ≥12-month follow-up. In addition, random effects meta-analyses of selected studies were applied to analyze the weighted mean difference (WMD) of MBL between groups of thick and thin peri-implant soft tissue. Metaregression was conducted to investigate any potential influences of confounding factors, i.e., platform switching design, cement-/screw-retained restoration, and flapped/flapless surgical techniques.
RESULTS
Eight articles were included in the systematic review, and five were included in the quantitative synthesis and meta-analyzed to examine the influence of tissue thickness on early MBL. Meta-analysis for the comparison of MBL among selected studies showed a WMD of -0.80 mm (95% confidence interval -1.18 to -0.42 mm) (P <0.0001), favoring the thick tissue group. Metaregression of the selected studies failed to demonstrate an association among MBL and confounding factors.
CONCLUSION
The current study demonstrates that implants placed with an initially thicker peri-implant soft tissue have less radiographic MBL in the short term.
Topics: Alveolar Bone Loss; Alveolar Process; Bone Diseases, Metabolic; Dental Implantation, Endosseous; Dental Implants; Humans; Surgical Flaps
PubMed: 26777766
DOI: 10.1902/jop.2016.150571 -
Therapeutic Advances in Ophthalmology 2022The distance between the optic disc center and the fovea is a biometric parameter; however, it is unclear whether DFD (disc-fovea distance) affects the choroidal...
BACKGROUND
The distance between the optic disc center and the fovea is a biometric parameter; however, it is unclear whether DFD (disc-fovea distance) affects the choroidal thickness.
OBJECTIVE
The aim of this study is to investigate the association between DFD and choroidal thickness.
DESIGN
This is a prospective, and cross-sectional study.
METHODS
Two hundred fifty eyes of 250 healthy participants were examined in terms of DFD, age, axial length, spherical equivalent, and choroidal thickness. Inclusion criteria included aged between 20-40 years, no posterior segment disorders, and participants with best-corrected visual acuity (10/10 according to Snellen's chart). Participants with high hypermetropia (>4 diopter) or myopia (>6 diopter) or any systemic disease likely to affect choroidal thickness were excluded. Choroidal thickness measurements were performed at subfoveal, 1.0 mm temporal, and 1.0 mm nasal using the enhanced-depth imaging optical coherence tomography.
RESULTS
The mean age of all the participants was 26.21 ± 5.73 years, mean DFD was 4634.29 ± 274.70 µm, mean axial length was 23.62 ± 0.83 mm, and mean spherical equivalent was -0.61 ± 1.06 diopter. The mean subfoveal, nasal, and temporal choroidal thicknesses were 388.73 ± 90.15 µm, 351.26 ± 88.09 µm, and 366.50 ± 79.56 µm, respectively. A negative correlation was found between subfoveal, nasal, and temporal choroidal thicknesses and axial length ( = -0.157, = 0.013; = -0.168, = 0.008; = -0.174, = 0.006, respectively). Insignificant correlation was found between choroidal thicknesses and spherical equivalent ( > 0.05). There was not a statistically significant correlation between DFD and subfoveal, nasal, and temporal choroidal thicknesses ( = -0.028, = 0.655; = 0.030, = 0.641; = -0.025, = 0.699, respectively). In addition, there was not a statistically significant correlation between age and choroidal thickness.
CONCLUSION
This study shows that DFD and spherical equivalent do not affect choroidal thickness; axial length negatively affects choroidal thickness. In addition, age does not affect choroidal thickness between 20 and 40 years.
PubMed: 35602660
DOI: 10.1177/25158414221096062 -
Journal of Ophthalmic & Vision Research 2020To investigate the effects of refraction on retinal thickness measurements at different locations and layers in healthy eyes of Saudi participants. (Review)
Review
PURPOSE
To investigate the effects of refraction on retinal thickness measurements at different locations and layers in healthy eyes of Saudi participants.
METHODS
Thirty-six randomly selected adults aged 27.0 5.7 years who attended a Riyadh hospital from 2016 to 2017 were categorized into three groups: non-myopic (spherical equivalent refraction [SER], +1.00 to -0.50 diopters [D]), low myopic (SER, -0.75 to -3.00D), and moderate to high myopic (SER -3.25D). Full, inner, and outer retinal thicknesses were measured at nine locations by spectral-domain stratus optical coherence tomography (Optovue Inc., Fremont, CA, USA) and were compared according to refractive group and sex.
RESULTS
The mean SERs for the non-myopia, low myopia, and moderate to high myopia groups were 0.2 0.6, -1.5 0.5, and -7.5 1.9 D, respectively. Refractive error, but not sex, had significant effects on the retinal layer thickness measurements at different locations ( 0.05). The parafoveal and outer retinal layers were significantly thicker than the perifoveal and inner retina layers in all groups ( 0.05). The full foveal thickness was higher and the full parafoveal and perifoveal regions were thinner in moderate to high myopic eyes than in the non-myopic eyes ( 0.05), but were similar to those in the low myopic eyes ( 0.05). The foveal thicknesses measured in the inner and outer layers of the retina were higher but the thicknesses measured at the inner and outer layers of the parafoveal and perifoveal regions were lower in moderate to high myopic eyes.
CONCLUSION
There were regional differences in the retinal layer thicknesses of healthy Saudi eyes, which was dependent on the central refractions. This is important when interpreting retinal nerve fiber layer thicknesses in myopia and disease management in Saudi participants.
PubMed: 32308952
DOI: 10.18502/jovr.v15i2.6735 -
Clinical and Experimental Dental... Dec 2020Creating a tooth-like appearance by use of dental ceramics is still a challenge. Opalescence is a unique property of dental enamel, attempted to be mimicked by dental...
OBJECTIVES
Creating a tooth-like appearance by use of dental ceramics is still a challenge. Opalescence is a unique property of dental enamel, attempted to be mimicked by dental restorative materials. This study aimed to assess the effect of ceramic thickness on opalescence.
MATERIALS AND METHODS
Twenty-four discs were fabricated of feldspathic ceramic, IPS e.max, zirconia and Enamic ceramics with 10 mm diameter and 0.5 and 1 mm thicknesses (n = 12). The opalescence of ceramic specimens was calculated by measuring the difference in yellow-blue axis (CIE ∆b*) and red-green axis (CIE ∆a*) between the transmitted and reflected spectra. One-way ANOVA was applied to compare the opalescence of different ceramic specimens with variable thicknesses at .05 level of significance.
RESULTS
The opalescence of feldspathic, IPS e.max, zirconia and Enamic ceramic specimens with 0.5 mm thickness was 1.06 ± 0.15, 3.39 ± 0.15, 1.98 ± 0.15 and 1.44 ± 0.15, respectively. By increasing the thickness to 1 mm, the opalescence of feldspathic, IPS e.max, zirconia and Enamic ceramics changed to 1.12 ± 0.15, 1.47 ± 0.15, 3.85 ± 0.15 and 2.00 ± 0.15, respectively. In all groups except for IPS e.max, the mean opalescence of 1-mm-thick specimens was higher than that of 0.5-mm-thick specimens.
CONCLUSION
Type and thickness of ceramic affect its opalescence. The opalescence of all ceramic specimens tested in this study with 0.5 and 1 mm thicknesses was lower than that of the enamel.
Topics: Ceramics; Dental Enamel; Dental Porcelain; Dental Restoration, Permanent; Humans; Iridescence; Materials Testing; Surface Properties; Zirconium
PubMed: 32902165
DOI: 10.1002/cre2.325 -
Journal of Ophthalmology 2021To compare the results and repeatability of the corneal thickness (CT) and epithelial thickness (ET) maps provided by Swept-Source-Optical Coherence Tomography with...
OBJECTIVE
To compare the results and repeatability of the corneal thickness (CT) and epithelial thickness (ET) maps provided by Swept-Source-Optical Coherence Tomography with those of Spectral-Domain-OCT in normal eyes.
METHODS
30 normal eyes of 30 patients were assessed by 3 trained operators with SS-OCT and SD-OCT.
RESULTS
The central and minimum ET obtained with both devices were correlated: central ET, = 0.86, < 0.05; minimum ET, = 0.72, < 0.05. Compared with SD-OCT, SS-OCT tended to underestimate these figures by 1.4 and 1.9 m on average. The central and minimum CT obtained with both devices were strongly correlated: central CT, = 0.994, < 0.05; minimum CT, = 0.995, < 0.05. SS-OCT tended to overestimate these figures by 11 and 14 m on average. Repeatability was good for both devices with a mean coefficient of variation of measurements <6% for ET and <2% for CT. Interoperator variability (standard deviation and COV) was significantly higher for SS-OCT than for SD-OCT for all local epithelial thicknesses and significantly lower for the central CT and several local corneal thicknesses, whereas no significant differences between both technologies were found for the central and minimum ET and the minimum CT.
CONCLUSION
SS-OCT and SD-OCT provide reproducible measurements of CT and ET in normal corneas with a strong correlation between both technologies. However, both technologies are not interchangeable when the main thickness parameters (i.e., central and minimum CT and minimum ET) are used for diagnosing early keratoconus or calculating the expected residual stromal bed thickness before corneal refractive surgery or anterior lamellar keratoplasty.
PubMed: 34650817
DOI: 10.1155/2021/3444083 -
Arquivos Brasileiros de Oftalmologia 2019Obesity is associated with eye diseases, but the underlying structural changes and pathogenic mechanisms have not been examined in detail. Here, we assessed the effects...
PURPOSE
Obesity is associated with eye diseases, but the underlying structural changes and pathogenic mechanisms have not been examined in detail. Here, we assessed the effects of morbid obesity on the morphometric indices of eye disease.
METHODS
Morbidly obese volunteers (n=101, body mass index [BMI] ³40) and healthy individuals (n=95, BMI: 18.50-24.99) were examined by Goldman applanation tonometry, pachymetry, and spectral domain optical coherence tomography. Intraocular pressure, anterior chamber depth, axial length, central corneal thickness, retinal nerve fiber layer thickness, central foveal thickness, and choroidal thickness were compared between groups.
RESULTS
Uncorrected intraocular pressure was significantly greater in the morbidly obese group than in the healthy control group (15.5 ± 2.5 vs. 14.5 ± 2.6 mmHg, p=0.009), whereas axial length, anterior chamber depth, and central corneal thickness did not differ between the groups. The mean retinal nerve fiber layer thickness at the temporal quadrant was reduced in the morbidly obese group (72.7 ± 13.6 vs. 85.05 ± 52.6 mm, p=0.024). Similarly, the mean retinal thicknesses at nasal and temporal 1500-mm locations were lower in the morbidly obese group (346.6 ± 18.2 vs. 353.7 ± 18.8 mm, p=0.008; 323.1 ± 20.3 vs. 330.0 ± 18.9 mm, p=0.001). The mean choroidal thickness was also reduced in almost all measurement locations (fovea, temporal 500 and 1000 mm, and nasal 500, 1000, and 1500 mm) of the obese group (p<0.05). Weight and BMI were negatively correlated with subfoveal choroidal thickness (r=-0.186, p=0.009; r=-0.173, p=0.015).
CONCLUSION
Morbid obesity is associated with elevated uncorrected intraocular pressure and signs of neuropathy and retinopathy. Obesity may thus increase the risks of glaucoma and glaucomatous optic neuropathy.
Topics: Adolescent; Adult; Body Mass Index; Case-Control Studies; Choroid; Choroid Diseases; Corneal Pachymetry; Female; Glaucoma; Humans; Intraocular Pressure; Male; Middle Aged; Obesity, Morbid; Retina; Retinal Diseases; Statistics, Nonparametric; Tomography, Optical Coherence; Tonometry, Ocular; Young Adult
PubMed: 30652762
DOI: 10.5935/0004-2749.20190007 -
Polymers Apr 2023This paper aimed to experimentally clarify the crushing mechanism and performance of expanded polypropylene foam (EPP) and analyze the influence of density and thickness...
This paper aimed to experimentally clarify the crushing mechanism and performance of expanded polypropylene foam (EPP) and analyze the influence of density and thickness on its mechanical behavior and energy absorption properties under static crushing loadings. Hence, a series of compression tests were carried out on EPP foams with different densities and thicknesses. For foam with a density of 60 kg/m, the mean crushing strength, energy absorption (E, energy absorption efficiency (E), specific energy absorption (SEA), and energy absorption per unit volume (w) increased by 245.3%, 187.2%, 42.3%, 54.3%, and 242.8%, respectively, compared to foam with a density of 20 kg/m. Meanwhile, compared to foam with a thickness of 30 mm, the mean crushing strength, energy absorption (), energy absorption efficiency (), SEA, and energy absorption per unit volume () for foam with a thickness of 75 mm increased by 53.3%, 25.2%, -10.8%, -4.7%, and -10.6%, respectively. The results show that foam density has a significantly greater influence on static compressive performance than foam thickness. The microstructures of the EPP foam before and after static compression were compared by observing with a scanning electron microscope (SEM), and the failure mechanism was analyzed. Results showed that the load and energy as well as the deformation and instability processes of its cells were transferred layer by layer. The influence of density on the degree of destruction of the internal cells was obvious. Due to its larger mass and larger internal damping, thicker foams were less damaged, and less deformation was produced. Additionally, the EPP foam exhibited a considerable ability to recover after compression.
PubMed: 37177205
DOI: 10.3390/polym15092059 -
Proceedings of the National Academy of... Dec 2021The relationship between sample thickness and quality of data obtained is investigated by microcrystal electron diffraction (MicroED). Several electron microscopy (EM)...
The relationship between sample thickness and quality of data obtained is investigated by microcrystal electron diffraction (MicroED). Several electron microscopy (EM) grids containing proteinase K microcrystals of similar sizes from the same crystallization batch were prepared. Each grid was transferred into a focused ion beam and a scanning electron microscope in which the crystals were then systematically thinned into lamellae between 95- and 1,650-nm thick. MicroED data were collected at either 120-, 200-, or 300-kV accelerating voltages. Lamellae thicknesses were expressed in multiples of the corresponding inelastic mean free path to allow the results from different acceleration voltages to be compared. The quality of the data and subsequently determined structures were assessed using standard crystallographic measures. Structures were reliably determined with similar quality from crystalline lamellae up to twice the inelastic mean free path. Lower resolution diffraction was observed at three times the mean free path for all three accelerating voltages, but the data quality was insufficient to yield structures. Finally, no coherent diffraction was observed from lamellae thicker than four times the calculated inelastic mean free path. This study benchmarks the ideal specimen thickness with implications for all cryo-EM methods.
Topics: Animals; Benchmarking; Cryoelectron Microscopy; Crystallization; Crystallography; Electrons; Humans; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Models, Molecular; Specimen Handling
PubMed: 34873060
DOI: 10.1073/pnas.2108884118 -
Acta Stomatologica Croatica Mar 2022Dentin thickness in concave areas of the root creates risk for complications such as strip perforation during endodontic treatment. The study aims to examine dentin...
OBJECTIVES
Dentin thickness in concave areas of the root creates risk for complications such as strip perforation during endodontic treatment. The study aims to examine dentin thickness of the danger (DZ) and safety zone (SZ), canal configuration, and the presence of isthmus in the mesiobuccal root of maxillary molars.
MATERIAL AND METHODS
Cone-beam Computed Tomography (CBCT) images of 1251 teeth belonging to 642 patients were retrospectively reviewed. The dentin thicknesses at DZ and SZ in maxillary molars with one (MB) or two mesiobuccal canals (MB1, MB2) were measured at the 3 mm apical to the furcation level. Vertucci's canal configurations and the isthmus rate were recorded. The Chi-square test andThe Student's t-test were performed.
RESULTS
MB2 rate was higher in maxillary first molars (61.68%) than second molars (39.36%). Isthmus rates were 27.3% and 44.11% in first and second molars. DZ thickness was thinner than the dentin thickness in the SZ in both first and second molars with one or two mesial canals (p< 0.05). In teeth with single canal, the mean DZ thickness was 0.88mm. In teeth with two canals, the mean DZ thicknesses were 0.83mm and 0.80mm for MB1 and MB2 canals, respectively.
CONCLUSION
MB2 rate was higher in the first molar (61.68%), and the isthmus rate was higher in the second molar (44.11%). DZ and SZ were thinner in MB2 than in MB1 at the maxillary molars with two mesial canals. The results indicated that more conservative preparation must be applied to the MB2 canal in the maxillary molars.
PubMed: 35382485
DOI: 10.15644/asc56/1/6 -
Arquivos Brasileiros de Oftalmologia 2020This study aimed to evaluate optic nerve head parameters and inner retinal layer thicknesses in obese children and adolescents.
PURPOSE
This study aimed to evaluate optic nerve head parameters and inner retinal layer thicknesses in obese children and adolescents.
METHODS
Forty-one eyes of 41 pediatric obese participants and 41 eyes of 41 age- and sex-matched healthy controls were included in this study. Body mass index was calculated, based on sex and age, using body weight and height measurements. Blood lipid values (i.e., cholesterol, low-density lipoprotein, high-density lipoprotein, and triglyceride) were measured in obese participants. Optical coherence tomography was used to examine optic nerve head parameters, including rim area, disc area, cup-to-disc ratio, and cup volume, as well as the thicknesses of retinal nerve fiber layers and macular ganglion cell-inner plexiform layers.
RESULTS
Optic disc parameters were similar in obese and healthy children (p>0.05). The percentage of binocular retinal nerve fiber layer thickness symmetry was significantly different between obese and control groups (p=0.003). Compared to the control group, participants in the obese group exhibited thinner retinal nerve fiber layers in the superior quadrants (p=0.04) and thinner ganglion cell-inner plexiform layers in the superior-temporal sectors (p=0.04). There were no statistically significant correlations between the ocular parameters and lipid blood test values assessed in this study (p>0.05). Body mass index was significantly negatively correlated with the mean retinal nerve fiber layer thickness (r=-0.33, p=0.03) in the obese group. There was no significant correlation between intraocular pressure and body mass index (r=0.05, p=0.74).
CONCLUSION
Compared to healthy children, obese children had greater binocular retinal nerve fiber layer thickness asymmetry and thinner retinal nerve fiber and ganglion cell-inner plexiform layers in several sectors. Blood lipid levels were not associated with retinal thickness or optic disc parameters in obese children.
Topics: Adolescent; Child; Humans; Nerve Fibers; Obesity; Optic Disk; Retina; Retinal Ganglion Cells; Tomography, Optical Coherence
PubMed: 33084815
DOI: 10.5935/0004-2749.20200047