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Contact Lens & Anterior Eye : the... Apr 2024It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power....
It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.
PubMed: 38641525
DOI: 10.1016/j.clae.2024.102156 -
Journal of Pharmacy & Bioallied Sciences Feb 2024Surface roughness of the crowns is dependent on the pattern material used for the making as well as the procedure of investing. The study was aimed to examine the impact...
INTRODUCTION
Surface roughness of the crowns is dependent on the pattern material used for the making as well as the procedure of investing. The study was aimed to examine the impact of various pattern materials and investment procedures on the surface roughness of nickel-chromium alloy raw castings.
MATERIALS AND METHODS
An study was piloted at a tertiary care hospital. Eighty samples of inlay wax and pattern resin were divided equally. They were invested in phosphate-bonded investment material and kept under normal atmospheric pressure as well as invested under a pressure of 3 bars. The surface roughness was calculated with a Profilometer. The values obtained were compared using statistical tools keeping < 0.05 as significant.
RESULTS
Lowest surface roughness was seen for the wax pattern invested under positive pressure. While the highest was seen for the resin patterns invested at room pressure. A significant variance between the wax 1 and wax 2 ( < 0.01); as well as between the wax 2 vs. Resin 2 specimens ( < 0.01) was noted.
CONCLUSIONS
Wax patterns can be suggested as the material and method of choice because they showed the least amount of surface roughness when placed under pressure. Resin patterns when invested under pressure can also be suggested as an alternate as they also exhibited similar surface roughness as that of the wax.
PubMed: 38595557
DOI: 10.4103/jpbs.jpbs_445_23 -
Journal of Pharmacy & Bioallied Sciences Feb 2024Indirect composite restoration is one of the commonly followed procedures in the posterior teeth. The success of this is dependent on many factors, one being the luting...
INTRODUCTION
Indirect composite restoration is one of the commonly followed procedures in the posterior teeth. The success of this is dependent on many factors, one being the luting cement. Hence, the current study explores the microleakage of the two luting cements at 2 different times.
MATERIALS AND METHODS
Eighty extracted human teeth were taken, and class II cavities were made that were to receive the composite inlays. They were grouped as supragingival and subgingival, which for further divided as were further subdivided to be observed for marginal leakage at cervical and occlusal margins, at the end of a day and 1 month. Each group had ten specimens. The luting cements that were evaluated were Variolink N and RelyX Unicem. After the composite inlay restoration was done for all the specimens, the sections were put on slides, and a stereomicroscope was used to measure the amount of dye penetration. Leakage was evaluated and compared using Mann-Whitney U test.
RESULTS
At the end of 1 day, there was no significant alteration in the microleakage in the occlusal or cervical regions for either region supragingivally or subgingivally between the two luting cements. Significant difference between the two cements at the cervical borders at the end of a month was seen for both the margins. When compared supragingivally and subgingivally at the end of 1 day or at the end of 1 month, there was not a significant difference for any of the cements.
CONCLUSION
Within the constraints of the current investigation, it can be said that there was similar microleakage for both Variolink N and RelyX Unicem at the conclusion of a day's storage time. After a 1-month storage period, RelyX Unicem showed more cervical microleakage than Variolink N.
PubMed: 38595365
DOI: 10.4103/jpbs.jpbs_438_23 -
Materials (Basel, Switzerland) Mar 2024The study aimed to assess the marginal, axial, and internal adaptation, as well as the fracture resistance of zirconia-reinforced lithium silicate (ZLS) endocrowns with...
The study aimed to assess the marginal, axial, and internal adaptation, as well as the fracture resistance of zirconia-reinforced lithium silicate (ZLS) endocrowns with varying pulpal inlay extensions and marginal geometry. Sixty extracted maxillary first molar teeth were divided into six groups (n = 10) according to pulpal inlay extension and marginal configuration. The first three groups (J2, J3, and J4) utilized prepared teeth for endocrowns without ferrule design and 2 mm, 3 mm, and 4 mm pulpal extensions, respectively. The second three groups (F2, F3, and F4) utilized prepared teeth with 1 mm shoulder margins and 2 mm, 3 mm, and 4 mm pulpal extensions. The endocrowns were fabricated from ZLS blocks using CAD/CAM milling technology. After cementation, the specimens underwent thermal aging for 5000 cycles and were evaluated for marginal adaptation. Using a universal testing machine, the fracture resistance was tested under quasistatic loading (1 mm/min). Two-way ANOVA and the Tukey's post hoc test were employed for data analysis ( ≤ 0.05). The results of this study revealed that endocrowns without ferrule exhibited superior fracture strength than a 1 mm ferrule design < 0.05, irrespective of the inlay depth. All designs with and without ferrule and all inlay depths showed clinically acceptable marginal and internal fit. The conventional endocrown design without ferrule and 2 mm inlay depth showed the lowest surface gap. The pulpal surface showed the highest discrepancy among all groups compared to the other surfaces. Endocrowns without ferrule are more conservative and have higher fracture strength than 1 mm ferrule designs; extending the inlay depth showed a significant increase in fracture resistance of the 1 mm ferrule design, but not for the conventional design without ferrule and 2 mm inlay depth. All groups exhibited a high auspicious fracture strength value for molar endocrown restorations.
PubMed: 38541565
DOI: 10.3390/ma17061411 -
The Journal of Prosthetic Dentistry May 2024The influence of computer-aided manufacturing (CAM) parameters and settings on the outcomes of milled indirect restorations is poorly understood. (Review)
Review
STATEMENT OF PROBLEM
The influence of computer-aided manufacturing (CAM) parameters and settings on the outcomes of milled indirect restorations is poorly understood.
PURPOSE
The purpose of this scoping review was to summarize the current CAM systems, parameters, and setting changes, and their effects on different outcomes of milled indirect restorations and aspects related to their manufacture.
MATERIAL AND METHODS
The protocol of this review is available online (https://osf.io/x28ps/). Studies that used at least 2 different parameters (CAM units, number of axes, digital spacers, or protocols with different rotatory instruments, grit-sizes, milling speed, or others) for milling indirect restorations were included. A structured search up to July 2023 was performed by 2 independent reviewers for articles written in English in LILACS, MEDLINE via PubMed, EMBASE, Web of Science, and Scopus.
RESULTS
Of 1546 studies identified, 22 were included in the review. Discrepancies were found between the planned and actual measured cement space, with a decreasing linear relationship impacting restoration adaptation at different points. The CEREC MC XL milling machine was the most used system in the included studies, with variations in bur types, milling modes, and number of burs uses affecting internal fit and surface trueness. The results demonstrated the better adaptation of restorations made with 5-axis over 3-axis milling machines. Lithium disilicate and zirconia were the most commonly used materials, and crowns and inlays were popular designs. Marginal and internal adaptation were the primary outcomes assessed using the various techniques.
CONCLUSIONS
The study presented a comprehensive exploration of CAM systems and parameters, and their influence on indirect restorations. The planned cement space was not properly reproduced by the milling. Bur characteristics can affect restoration fit and trueness. The 5-axis units seem to result in better-adapted restorations compared with 3- and 4-axis units.
Topics: Computer-Aided Design; Humans; Dental Prosthesis Design; Dental Restoration, Permanent; Dental Marginal Adaptation
PubMed: 38480018
DOI: 10.1016/j.prosdent.2024.02.021 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Feb 2024Noncarious lesions, a multifactorial condition encompassing tooth attrition, abrasion, and erosion, have a surge in prevalence and required increased attention in...
Noncarious lesions, a multifactorial condition encompassing tooth attrition, abrasion, and erosion, have a surge in prevalence and required increased attention in clinical practice. These nonbacterial-associated tooth defects can compromise aesthetics, phonetics, and masticatory functions. When providing full-arch fixed occlusal rehabilitation for such cases, the treatment strategy should extend beyond by restoring dentition morphology and aesthetics. This report details a complex case of erosive dental wear addressed through a fully digital, full-arch fixed occlusal rehabilitation. A 4D virtual patient was created using multiple digital data sources, including intraoral scanning, 3D facial scanning, digital facebow registration, and mandibular movement tracing. With a comprehensive understanding of the masticatory system, various types of microinvasive prostheses were customized for each tooth, including labial veneers, buccal-occlusal veneers, occlusal veneers, overlays, inlays, and full crowns, were customized for each tooth. The reported digital workflow offered a predictable diagnostic and treatment strategy, which was facilitated by virtual visualization and comprehensive quality control throughout the process.
Topics: Humans; Tooth Erosion; Digital Technology; Esthetics, Dental; Tooth Attrition; Inlays
PubMed: 38475959
DOI: 10.7518/hxkq.2023.2023130 -
The Journal of Advanced Prosthodontics Feb 2024The aim of this stuldy was to compare the clinical marginal fit of CAD-CAM inlays obtained from intraoral digital impression or addition silicone impression techniques.
PURPOSE
The aim of this stuldy was to compare the clinical marginal fit of CAD-CAM inlays obtained from intraoral digital impression or addition silicone impression techniques.
MATERIALS AND METHODS
The study included 31 inlays for prosthodontics purposes of 31 patients: 15 based on intraoral digital impressions (DI group); and 16 based on a conventional impression technique (CI group). Inlays included occlusal and a non-occlusal surface. Inlays were milled in ceramic. The inlay-teeth interface was replicated by placing each inlay in its corresponding uncemented clinical preparation and taking interface impressions with silicone material from occlusal and free surfaces. Interface analysis was made using white light confocal microscopy (WLCM) (scanning area: 694 × 510 µm) from the impression samples. The gap size and the inlay overextension were measured from the microscopy topographies. For analytical purposes (i.e., 95-%-confidence intervals calculations and -value calculations), the procedure REGRESS in SUDAAN was used to account for clustering (i.e., multiple measurements). For p-value calculation, the log transformation of the dependent variables was used to normalize the distributions.
RESULTS
Marginal fit values for occlusal and free surfaces were affected by the type of impression. There were no differences between surfaces (occlusal vs. free). Gap obtained for DI group was 164 ± 84 µm and that for CI group was 209 ± 104 µm, and there were statistical differences between them ( = .041). Mean overextension values were 60 ± 59 µm for DI group and 67 ± 73 µm for CI group, and there were no differences between then ( = .553).
CONCLUSION
Digital impression achieved inlays with higher clinical marginal fit and performed better than the conventional silicone materials.
PubMed: 38455677
DOI: 10.4047/jap.2024.16.1.57 -
Journal of the Mechanical Behavior of... Apr 2024The existing knowledge is insufficient for comprehending the fatigue survival and fracture resistance of molars that have deep approximal direct and indirect...
STATEMENT OF PROBLEM
The existing knowledge is insufficient for comprehending the fatigue survival and fracture resistance of molars that have deep approximal direct and indirect restorations, whether with or without deep margin elevation (DME).
PURPOSE
The aim of this laboratory and in silico study is to investigate the fatigue survival, fracture strength, failure pattern and tooth deformation of molars restored with DME in combination with a direct or indirect restoration.
MATERIAL AND METHODS
This study utilized 45 extracted sound human molars, divided into three groups (n = 15). Standardized 100% inter-cuspal inlay preparations were performed, extending 2 mm below the CEJ and immediate dentin sealing (IDS) was applied. Group 1 (Co_1) was restored with direct composite; Group 2 (Hyb_2) with a 2 mm DME of direct composite and a glass-ceramic lithium disilicate restoration; Group 3 (Cer_3) a glass-ceramic lithium disilicate restoration. All specimens were exposed to a fatigue process involving thermal-cyclic loading (50N for 1.2 × 10 cycles at 1.7 Hz, between 5 and 55 °C), if teeth survived, they were fractured using a load-to-failure test and failure types were analyzed. Finite element analysis (FEA) was conducted to assess tooth deformation and tensile stress in the restorations. Statistical evaluation of fracture strength was conducted using the Kruskal-Wallis test. Fisher's exact test was utilized to analyze the fracture types and repairability. A statistical significance level of α < 0.05 was set for all analyses.
RESULTS
All specimens successfully withstood the fatigue testing procedure, and no statistically significant differences in fracture strength were observed among the three groups (P > 0.05). The Fisher's exact test indicated a significant association between the restorative material and fracture type (F = 18.315, df = 2, P = 0.004), but also for repairability (F = 13.725, df = 2, P = 0.001). Crown-root fractures were significantly more common in the Cer_3 group compared to the Co_1 group (P = 0.001) and the Co_1 group had significantly more repairable fractures (F = 13.197, df = 2, P = 0.001). FEA revealed comparable outcomes of deformation among models and higher maximum tensile stress on models with higher frequency of catastrophic failures.
CONCLUSIONS
All tested restoration materials exhibited comparable fatigue survival and fracture strength in this laboratory and in silico study. However, it is important to recognize the potential for more severe and irreparable fractures when opting for deeply luted glass-ceramic inlay restorations in clinical practice. In such cases, it would be prudent to consider the alternative option being a direct composite approach, because of its more forgiving fracture types and repairability.
CLINICAL IMPLICATIONS
Molars with deep approximal direct and indirect restorations, whether with or without DME, are comparable in their fatigue survival and fracture resistance to withstand intra-oral forces. Deep direct restorations exhibit more repairable fractures compared to deeply luted glass-ceramics.
Topics: Humans; Molar; Finite Element Analysis; Flexural Strength; Fractures, Bone; Laboratories; Tooth Fractures
PubMed: 38394767
DOI: 10.1016/j.jmbbm.2024.106459 -
Bioengineering (Basel, Switzerland) Jan 2024Hip implants have a modular structure which enables patient-specific adaptation but also revision of worn or damaged friction partners without compromising the...
Hip implants have a modular structure which enables patient-specific adaptation but also revision of worn or damaged friction partners without compromising the implant-bone connection. To reduce complications during the extraction of ceramic inlays, this work presents a new approach of a shape-memory-alloy-actuator which enables the loosening of ceramic inlays from acetabular hip cups without ceramic chipping or damaging the metal cup. This technical in vitro study exam-ines two principles of heating currents and hot water for thermal activation of the shape-memory-alloy-actuator to generate a force between the metal cup and the ceramic inlay. Mechanical tests concerning push-in and push-out forces, deformation of the acetabular cup according to international test standards, and force generated by the actuator were generated to prove the feasibility of this new approach to ceramic inlay revision. The required disassembly force for a modular acetabular device achieved an average value of 602 N after static and 713 N after cyclic loading. The actuator can provide a push-out force up to 1951 N. In addition, it is shown that the necessary modifications to the implant modules for the implementation of the shape-memory-actuator-system do not result in any change in the mechanical properties compared to conventional systems.
PubMed: 38247952
DOI: 10.3390/bioengineering11010075 -
Journal of Yeungnam Medical Science Apr 2024This study aimed to compare and evaluate the marginal fit of nanocomposite computer-aided design/computer-aided manufacturing (CAD/CAM) inlays. Three types of...
BACKGROUND
This study aimed to compare and evaluate the marginal fit of nanocomposite computer-aided design/computer-aided manufacturing (CAD/CAM) inlays. Three types of nanocomposite CAD/CAM blocks (HASEM, VITA Enamic, and Lava Ultimate) were used as materials.
METHODS
Class II disto-occlusal inlay restorations were prepared on a typodont mandibular right first molar using diamond rotary instruments. The inlays were fabricated using CAD/CAM technology and evaluated using the silicone replica technique to measure marginal gaps at five locations on each inlay. The data were analyzed by two-way analysis of variance and Tukey post hoc tests ( α=0.05).
RESULTS
There were no significant differences in the marginal gaps based on the type of nanocomposite CAD/CAM inlay used (p=0.209). However, there was a significant difference in the marginal gaps between the measurement regions. The gingival region consistently exhibited a larger marginal gap than the axial and occlusal regions (p<0.001).
CONCLUSION
Within the limitations of this in vitro study, the measurement location significantly influenced the marginal fit of class II disto-occlusal inlay restorations. However, there were no significant differences in the marginal gaps among the different types of CAD/CAM blocks. Furthermore, the overall mean marginal fits of the class II disto-occlusal inlay restorations made with the three types of nanocomposite CAD/CAM blocks were within the clinically acceptable range.
PubMed: 38247035
DOI: 10.12701/jyms.2023.00934