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The International Journal of Oral &... 2021To evaluate the factors that could influence the fracture resistance of implant-supported posterior monolithic zirconia crowns.
PURPOSE
To evaluate the factors that could influence the fracture resistance of implant-supported posterior monolithic zirconia crowns.
MATERIALS AND METHODS
Sixty zirconia molar crowns with three different occlusal thicknesses of 0.5, 1.0, and 1.5 mm (20 samples per group) were prepared for implant abutments using a CAD/CAM system. In each group, 10 crowns were luted on the abutment with resin cement (Panavia F), and the other 10 crowns were luted with resin-modified glass-ionomer cement (Ketac Cem Plus). Dynamic loading (1.2 × 10 cycles; 70 N) and thermal cycling were applied to the samples using a chewing simulator before evaluating their fracture resistance with a universal testing machine and examining their fracture type using a stereomicroscope. One-way analysis of variance (ANOVA), the Duncan test, and two-way ANOVA were used for data evaluation (α = .05).
RESULTS
The occlusal thickness (P < .001) and cement type (P < .01) affected the fracture load of the monolithic zirconia crowns. The highest fracture resistance was found in 1.5-mm-thick crowns luted with resin cement (4,212 ± 501 N), and the lowest fracture resistance was found in 0.5-mm and 1-mmthick crowns luted with resin-modified glass-ionomer cement (1,198 ± 116 N and 1,197 ± 66 N). A significant difference was not found in the mean maximum fracture load between the 1.5-mm-thick crowns cemented with resin cement and glass-ionomer resin cement.
CONCLUSION
Both the occlusal thickness and cement type remarkably affected the fracture resistance of the crowns, but occlusal thickness was more significant. Implant-supported posterior zirconia crowns can withstand physiologic occlusal forces even with a thickness as low as 0.5 mm. Resin luting cement is recommended for implant-supported posterior zirconia crowns with reduced occlusal thickness.
Topics: Computer-Aided Design; Crowns; Dental Implants; Dental Porcelain; Dental Prosthesis Design; Dental Stress Analysis; Glass Ionomer Cements; Materials Testing; Resin Cements; Zirconium
PubMed: 34115062
DOI: 10.11607/jomi.8503 -
Arquivos Brasileiros de Oftalmologia 2021To comparatively evaluate the subfoveal choroidal thickness and the peripapillary retinal nerve fiber layer thickness in patients with chronic heart failure relative to...
PURPOSE
To comparatively evaluate the subfoveal choroidal thickness and the peripapillary retinal nerve fiber layer thickness in patients with chronic heart failure relative to control subjects.
METHODS
A total of 72 chronic heart failure patients and 40 healthy control subjects were enrolled in this study. The patients were categorized into 2 groups: group 1: patients with 30-50% left ventricle ejection fraction and group 2: patients with the corresponding fraction value of <30%. The subfoveal choroidal thickness and the peripapillary retinal nerve fiber layer thickness were measured by spectral domain-optical coherence tomography.
RESULTS
The mean subfoveal choroidal thickness was 250.24 ± 68.34 µm in group 1 and 216.72 ± 71.24 µm in group 2, while it was 273.64 ± 77.68 µm in the control group. The differences among the 3 groups were statistically significant. The average peripapillary retinal nerve fiber layer thicknesses were 100.34 ± 8.24, 95.44 ± 6.67, and 102.34 ± 8.24 µm, respectively. No significant differences were noted in the peripapillary retinal nerve fiber layer thicknesses between group 1 and control group, but it was significantly lower in group 2.
CONCLUSION
Our study thus revealed that the subfoveal choroidal thickness was lower in patients belonging to both the chronic heart failure groups in comparison to those in the control group. However, the alteration in the peripapillary retinal nerve fiber layer thickness was noted in only patients with <30% left ventricle ejection fraction. In the clinical practice, reductions in these values are correlated with decreased left ventricle ejection fraction, which may be important for the follow-up of chorioretinal diseases and the evaluation of glaucoma risks in patients with chronic heart failures.
Topics: Choroid; Heart Failure; Humans; Nerve Fibers; Optic Disk; Retinal Ganglion Cells; Tomography, Optical Coherence
PubMed: 34320107
DOI: 10.5935/0004-2749.20210077 -
Indian Journal of Ophthalmology Oct 2022To compare the optical coherence tomography (OCT)-based retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness at the posterior pole, and total macular...
PURPOSE
To compare the optical coherence tomography (OCT)-based retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness at the posterior pole, and total macular thickness of women with the polycystic ovarian syndrome (PCOS) versus healthy reproductive age group females.
METHODS
The study included 110 eyes of 55 diagnosed cases of PCOS (study group) and 110 eyes of 55 healthy reproductive age group (15-49 years) females (control group). All patients underwent a detailed ophthalmological evaluation followed by an OCT to measure their retinal thicknesses. The body mass index (BMI) of patients was noted and compared with the retinal thickness. Also, the lipid profile and serum testosterone levels of PCOS patients were recorded.
RESULTS
The retinal thicknesses in the two study were similar and there was no statistically significant difference. However, on stratification with BMI, it was seen that in patients with BMI>30 kg/m, the superior Retinal Nerve Fibre Layer (RNFL) was significantly thicker in the PCOS group as compared with the control group (P = 0.0006). The mean serum testosterone level in patients with PCOS was 141.3 ± 23.2. Also, 65.45% of patients had a serum testosterone level of more than 70 ng/dL. The mean HDL cholesterol in patients with PCOS was 38.1 ± 15.6. The mean LDL cholesterol in PCOS patients was 98.4 ± 21.7, and the mean total cholesterol in PCOS patients was 153.6 ± 27.3.
CONCLUSION
Androgens have a trophic action on nerves, which could explain the increased RNFL thickness in these patients.
Topics: Adolescent; Adult; Cholesterol, HDL; Cholesterol, LDL; Female; Humans; Middle Aged; Nerve Fibers; Polycystic Ovary Syndrome; Retinal Ganglion Cells; Testosterone; Tomography, Optical Coherence; Young Adult
PubMed: 36190052
DOI: 10.4103/ijo.IJO_36_22 -
American Journal of Orthodontics and... Sep 2020Enameloplasty of maxillary canines is often needed for aesthetic substitution in patients with congenitally missing lateral incisors. The exact enamel thicknesses for...
INTRODUCTION
Enameloplasty of maxillary canines is often needed for aesthetic substitution in patients with congenitally missing lateral incisors. The exact enamel thicknesses for the various canine surfaces are unknown because previous studies failed to employ accurate measurement tools to report and compare detailed enamel thicknesses for each surface at various crown heights.
METHODS
Thirty-two extracted maxillary canines were collected and scanned in a microcomputed tomography scanner. The scans were imported into a custom-written MATLAB software (version 9.2; MathWorks, Natick, Mass) and the enamel thickness on the mesial, distal, labial, fossa, cingulum, and incisal edge of each tooth was computed, obtaining the mean value from slices at 0.1 mm intervals. The overall mean enamel thickness for each surface was also calculated, and these values were compared using paired t tests. Incisal wear stage and incisal enamel thickness that was measured were compared using Spearman rank correlation coefficient.
RESULTS
The mean enamel thickness was significantly thinner at the gingival level when compared with the incisal for all surfaces that were analyzed (1-tailed, P <0.001). The mean enamel coverage at the mesial was significantly thinner than the distal when measured gingival to the widest mesiodistal area. The mean enamel coverage of the cingulum was particularly thin and therefore requires extreme care in reshaping it. Incisal edge enamel thickness was highly negatively correlated with the wear stage of the scoring system that was used (1-tailed, P <0.001).
CONCLUSIONS
The enamel coverage of the maxillary canine varies depending on the tooth surface and the incisogingival measurement location.
Topics: Cuspid; Dental Enamel; Esthetics, Dental; Humans; Maxilla; Odontometry; X-Ray Microtomography
PubMed: 32653347
DOI: 10.1016/j.ajodo.2019.09.013 -
Journal of Neuro-ophthalmology : the... Mar 2018The aim of this study was to evaluate and compare peripapillary choroidal thickness (pCT) and macular choroidal thickness (CT), Bruch membrane opening-minimum rim width...
BACKGROUND
The aim of this study was to evaluate and compare peripapillary choroidal thickness (pCT) and macular choroidal thickness (CT), Bruch membrane opening-minimum rim width (BMO-MRW), retinal nerve fiber layer (RNFL) thickness, and optic disc area among nonarteritic anterior ischemic optic neuropathy (NAION) eyes, the contralateral unaffected eyes, and healthy control eyes.
METHODS
Twenty-six patients diagnosed with NAION (29 affected and 21 unaffected eyes) and 29 healthy matched control individuals (29 eyes) were analyzed by swept-source optical coherence tomography. All participants underwent scanning by Spectralis optical coherence tomography to analyze BMO-MRW, RNFL thickness, and optic disc area.
RESULTS
Mean pCT in the NAION eyes, unaffected fellow eyes, and the control group was 130.5 ± 72.1 μm, 149.6 ± 75.7 μm, and 103.7 ± 36.7 μm, respectively (analysis of variance [ANOVA], P = 0.04). Mean macular CT in the NAION eyes, unaffected fellow eyes, and the control group was 226.1 ± 79.8 μm, 244.6 ± 81.4 μm, and 189.9 ± 56.4 μm, respectively (ANOVA, P = 0.03). Mean and all sectorial RNFL and BMO-MRW thickness values were significantly thinner in the NAION eyes vs the unaffected fellow and control eyes (P ≤ 0.00). The unaffected fellow eyes in NAION patients showed a significantly thicker average and sectorial BMO-MRW values than control eyes (P ≤ 0.02) except for the nasal sector (P = 0.09). Mean optic disc area derived from BMO analysis was not significantly different among groups (ANOVA, P = 0.86).
CONCLUSIONS
The fellow unaffected eyes in patients with NAION showed significantly thicker mean peripapillary and macular choroidal and BMO-MRW thicknesses than disease-free control eyes. No differences in the mean optic disc area were found. Both a thick peripapillary choroid and a thick neuroretinal rim might contribute to the development of NAION or possibly be a secondary phenomenon.
Topics: Aged; Arteritis; Choroid; Cross-Sectional Studies; Female; Humans; Male; Middle Aged; Nerve Fibers; Optic Disk; Optic Neuropathy, Ischemic; Organ Size; Retinal Ganglion Cells; Tomography, Optical Coherence; Visual Acuity; Visual Fields
PubMed: 28885450
DOI: 10.1097/WNO.0000000000000571 -
Journal of Indian Prosthodontic Society 2022The aim of this study was to investigate the combined effect of ceramic material, ceramic thickness, and implant abutment background to the final color of restorations.
AIM
The aim of this study was to investigate the combined effect of ceramic material, ceramic thickness, and implant abutment background to the final color of restorations.
SETTINGS AND DESIGN
This was a comparative in vitro study.
MATERIALS AND METHODS
Three different types of monolithic and porcelain-veneered zirconia disc-shaped specimens (Prettau Anterior, VITA YZ ST, and VITA YZ HT) were prepared in A3 shade with two different thicknesses (1 mm and 1.5 mm) (n = 10). Each zirconia material was made of 4-mm thickness as a control specimen of each monolithic zirconia type, and 4-mm thick veneering ceramic (VITA VM9 Base Dentine) was made as a control for veneered zirconia groups. Three simulated implant abutments were fabricated from titanium, white-shaded and yellow-shaded zirconia. The zirconia specimens were placed on different abutment backgrounds, and the color difference (ΔE) between experimental and control specimens was measured.
STATISTICAL ANALYSIS USED
The three-way ANOVA and the Scheffé test were used for data analysis (α = 0.05).
RESULTS
The mean ΔE values between two thicknesses were significantly different in every background for all zirconia materials. The ΔE values of zirconia specimens on yellow zirconia were lower than those of other abutments. The clinically acceptable ΔE value (ΔE <3) was found in some monolithic zirconia specimens on white-shaded and yellow-shaded abutments, while the ΔE value is approximately 3 or less in all 1.5-mm thick porcelain-veneered zirconia groups.
CONCLUSIONS
Different zirconia materials on implant abutments affected the final color of restorations. To achieve satisfactory color, the minimum thickness of zirconia restorations should be at least 1.5 mm on yellow zirconia abutment.
Topics: Dental Porcelain; Materials Testing; Color; Dental Implants; Dental Materials
PubMed: 36511058
DOI: 10.4103/jips.jips_179_22 -
Using artificial intelligence to predict the final color of leucite-reinforced ceramic restorations.Journal of Esthetic and Restorative... Jan 2023The aim of this study was to evaluate the accuracy of machine learning regression models in predicting the final color of leucite-reinforced glass CAD/CAM ceramic veneer...
OBJECTIVES
The aim of this study was to evaluate the accuracy of machine learning regression models in predicting the final color of leucite-reinforced glass CAD/CAM ceramic veneer restorations based on substrate shade, ceramic shade, thickness and translucency.
METHODS
Leucite-reinforced glass ceramics in four different shades were sectioned in thicknesses of 0.3, 0.5, 0.7, and 1.2 mm. The CIELab coordinates of each specimen were obtained over four different backgrounds (black, white, A1, and A3) interposed with an experimental translucent resin cement using a calibrated spectrophotometer. The color change (CIEDE2000) values, as well as all the CIELab values for each one of the experimental groups, were submitted to 28 different regression models. Each regression model was adjusted according to the weights of each dependent variable to achieve the best-fitting model.
RESULTS
Different substrates, ceramic shades, and thicknesses influenced the L, a, and b of the final restoration. Of all variables, the substrate influenced the final ceramic shade most, followed by the ceramic thickness and the L, a, and b of the ceramic. The decision tree regression model had the lowest mean absolute error and highest accuracy to predict the shade of the ceramic restoration according to the substrate shade, ceramic shade and thickness.
CLINICAL SIGNIFICANCE
The machine learning regression model developed in the study can help clinicians predict the final color of the ceramic veneers made with leucite-reinforced glass CAD/CAM ceramic HT and LT when cemented with translucent cements, based on the color of the substrate and ceramic thicknesses.
Topics: Dental Porcelain; Artificial Intelligence; Ceramics; Aluminum Silicates; Resin Cements; Color; Materials Testing; Surface Properties
PubMed: 36592128
DOI: 10.1111/jerd.13007 -
European Journal of Ophthalmology Jul 2022To determine the possible impact of wearing N95 respirator or surgical masks on retinal vessel diameters and choroidal thickness in healthy healthcare workers.
PURPOSE
To determine the possible impact of wearing N95 respirator or surgical masks on retinal vessel diameters and choroidal thickness in healthy healthcare workers.
METHODS
Diameters of peripapillary retinal arteries and veins and choroidal thickness values at the foveal center and at 1000 μm distances from the foveal center in both nasal and temporal directions were measured before mask wearing using a spectral-domain optical coherence tomography. After four hours (h) of N95 or surgical mask wearing vessel diameter and choroidal thickness measurements were repeated.
RESULTS
A total of 52 eyes from 52 participants (28 F [53.8%]; 24 M [46.2%]) were enrolled in this study. The mean age of patients was 34.58 ± 5.24 years (25-44 years). The diameters of all measured arteries [inferior temporal artery (p = 0.003), superior temporal artery (p < 0.001), inferior nasal artery (p = 0.003), and superior nasal artery (p = 0.004)] and veins,with the exception of superior nasal vein, (inferior temporal vein (p = 0.031), superior temporal vein (p = 0.027), inferior nasal vein (p < 0.001), and superior nasal vein (p = 0.063)] increased significantly after four hour use of N95 respirators and surgical maskswhen compared to baseline. There was also a significant diameter increase of the superior temporal (p < 0.001), inferior nasal veins (p < 0.001), and superior temporal artery (p = 0.037) for N95 respirators and surgical masks use, respectively. The differences in central subfoveal, temporal, and nasal choroidal thickness between baseline and after 4 h use of N95 respirators were statistically significant (From 366.73 ± 70.81 μm to 381.23 ± 69.29μm,p < 0.001 for the subfoveal; from 324.00 ± 64.13μm to 335.40 ± 61.35 μm, p = 0.007 for the temporal; from 297.40 ± 68.18 μm to 308.23 ± 74.51μm, p = 0.002 for the nasal thicknesses). Choroidal thickness values were also increased with surgical mask use. But only the increase in central subfoveal thickness was statistically significant (From 366.78 ± 71.00 μm to 372.58 ± 76.56 μm, p = 0.031 for the central subfoveal; from 297.42 ± 68.35 μmto 302.79 ± 73.05 μm, p = 0.068 for the nasal; from 324.01 ± 64.21μm to 330.33 ± 65.84, p = 0.117 for the temporal thicknesses).
CONCLUSION
With four hours use of N95 respirators or surgical face masks, retinal vessel diameters and choroidal thicknesses showed an increase in comparison to baseline measurements. Hemodynamic changes seen secondary to hypercapnia due to prolonged use of N95 respirators or surgical masks may also be observed in the retinal and choroidal circulation. Furthermore, the use of face masks should be taken into account while assessing the retinal microvasculature.
Topics: Adult; Choroid; Humans; Masks; Microvessels; N95 Respirators; Retina; Tomography, Optical Coherence
PubMed: 35410534
DOI: 10.1177/11206721221093199 -
Arquivos Brasileiros de Oftalmologia 2020To evaluate changes in ocular blood flow and subfoveal choroidal thickness in patients with symptomatic carotid artery stenosis after carotid artery stenting.
PURPOSES
To evaluate changes in ocular blood flow and subfoveal choroidal thickness in patients with symptomatic carotid artery stenosis after carotid artery stenting.
METHODS
We included 15 men (mean age, 63.6 ± 9.1 years) with symptomatic carotid artery stenosis and 18 healthy volunteers (all men; mean age, 63.7 ± 5.3 years). All participants underwent detailed ophthalmologic examinations including choroidal thickness measurement using enhanced depth-imaging optic coherence tomography. The patients also underwent posterior ciliary artery blood flow measurements using color Doppler ultrasonography before and after carotid artery stenting.
RESULTS
Patients lacked ocular ischemic symptoms. Their peak systolic and end-diastolic velocities increased to 10.1 ± 13.1 (p=0.005) and 3.9 ± 6.3 (p=0.064) cm/s, respectively, after the procedure. Subfoveal choroidal thicknesses were significantly thinner in patients with carotid artery stenosis than those in the healthy controls (p=0.01). But during the first week post-procedure, the subfoveal choroidal thicknesses increased significantly (p=0.04). The peak systolic velocities of the posterior ciliary arteries increased significantly after carotid artery stenting (p=0.005). We found a significant negative correlation between the mean increase in peak systolic velocity values after treatment and the mean preprocedural subfoveal choroidal thickness in the study group (p=0.025, r=-0.617).
CONCLUSIONS
In patients with carotid artery stenosis, the subfoveal choroid is thinner than that in healthy controls. The subfoveal choroidal thickness increases after carotid artery stenting. Carotid artery stenting treatment increases the blood flow to the posterior ciliary artery, and the preprocedural subfoveal choroidal thickness may be a good predictor of the postprocedural peak systolic velocity of the posterior ciliary artery.
Topics: Aged; Blood Flow Velocity; Carotid Arteries; Carotid Stenosis; Choroid; Humans; Male; Middle Aged; Ophthalmic Artery; Regional Blood Flow; Stents; Tomography, Optical Coherence
PubMed: 33084820
DOI: 10.5935/0004-2749.20200081 -
Plastic Surgery (Oakville, Ont.) May 2023The increasing prevalence of obesity in patients with breast cancer has prompted a reappraisal of the role of the latissimus dorsi flap (LDF) in breast reconstruction....
The increasing prevalence of obesity in patients with breast cancer has prompted a reappraisal of the role of the latissimus dorsi flap (LDF) in breast reconstruction. Although the reliability of this flap in obese patients is well-documented, it is unclear whether sufficient volume can be achieved through a purely autologous reconstruction (eg, extended harvest of the subfascial fat layer). Additionally, the traditional combined autologous and prosthetic approach (LDF + expander/implant) is subject to increased implant-related complication rates related to flap thickness in obese patients. The purpose of this study is to provide data on the thicknesses of the various components of the latissimus flap and discuss the implications for breast reconstruction in patients with increasing body mass index (BMI). Measurements of back thickness in the usual donor site area of an LDF were obtained in 518 patients undergoing prone computed tomography-guided lung biopsies. Thicknesses of the soft tissue overall and of individual layers (e.g., muscle, subfascial fat) were obtained. Patient, demographics including age, gender, and BMI were obtained. A range of BMI from 15.7 to 65.7 was observed. In females, total back thickness (skin, fat, muscle) ranged from 0.6 to 9.4 cm. Every 1-point increase in BMI resulted in an increase of flap thickness by 1.11 mm (adjusted of 0.682, < .001) and an increase in the thickness of the subfascial fat layer by 0.513 mm (adjusted of 0.553, < .001). Mean total thicknesses for each weight category were 1.0, 1.7, 2.4, 3.0, 3.6, and 4.5 cm in underweight, normal weight, overweight, and class I, II, III obese individuals, respectively. The average contribution of the subfascial fat layer to flap thickness was 8.2 mm (32%) overall and 3.4 mm (21%), 6.7 mm (29%), 9.0 mm (30%), 11.1 mm (32%), and 15.6 mm (35%) in normal weight, overweight, class I, II, III obese individuals, respectively. The above findings demonstrate that the thickness of the LDF overall and of the subfascial layer closely correlated with BMI. The contribution of the subfascial layer to overall flap thickness tends to increase as a percentage of overall flap thickness with increasing BMI, which is favourable for extended LDF harvests. Because this layer cannot be separated from overall thickness on examination, these results are useful in estimating the amount of additional volume obtained from an extended latissimus harvest technique.
PubMed: 37188129
DOI: 10.1177/22925503211031927