Cost and effectiveness of 3-dimensionally printed model using three different printing layer parameters and two resins.

STATEMENT OF PROBLEM: When 3-dimensional printing casts, the operator can change the type of resin and the printing layer thickness, reducing the fabrication time. However, how these parameters affect the accuracy of 3-dimensionally printed casts is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the accuracy of 3-dimensionally printed casts by using a stereolithography (SLA) 3-dimensional printer (Forms2) with 3 different layer thickness (25, 50, and 100 µm) and 2 different resins (Gray and Cast) and by comparing the time to obtain each cast. MATERIAL AND METHODS: One master cast was scanned, and a single file was printed several times. The printed casts were then scanned by using a laboratory scanner. The standard tessellation language (STL) files provided by the laboratory scanner were superimposed and compared by using a software program (Geomagic Control; 3D Systems). The 2-way ANOVA test was used for the trueness evaluation, followed by the Tukey test to identify differences among the groups (α=.05). RESULTS: No statistically significant differences in accuracy were found among the 3 different layers for either resin (P>.05). Printing time doubled as layer thickness decreased. CONCLUSIONS: This study showed that when printing casts, the fastest printing settings can be used without losing accuracy and that the laboratory digital workflow can be accelerated with selection of the resin and cast layer, as the type of resin and layer thickness did not influence the quality of the casts.

Biomechanical behavior of extra-narrow implants after fatigue and pull-out tests.

STATEMENT OF PROBLEM: Narrow implants have limited indications, and implant fracture may occur when these indications are not followed. PURPOSE: The purpose of this in vitro study was to investigate the mechanical behavior of a 2.9-mm-diameter implant using a fatigue limit test and to investigate the Morse effect of 2 different Morse taper systems, 2.9-mm-diameter (FAC group) and 3.75-mm-diameter (CM group) implants, using a pull-out test. The null hypothesis was that the tensile strengths of the components for both systems would be similar. MATERIAL AND METHODS: The fatigue properties of 13 specimens under 6 loads were determined. The test was performed at 15 Hz and for 5×106 cycles. In the pull-out test, the specimens were divided into 2 groups (n=8), the FAC group (2.9-mm-diameter) and the CM group (3.75-mm-diameter). Statistical analysis for the pull-out test was performed with the Student t test (α=.05). RESULTS: Thirteen specimens underwent the fatigue test. Only 5 did not fail when subjected to the frequency and number of cycles examined. Three of the specimens did not fail under a load of 130 N. The pull-out test showed a significant difference between the FAC and CM groups (P<.001). CONCLUSIONS: According to the fatigue test, the extra-narrow implant (Facility; Neodent) was compatible with the low masticatory effort regions, as indicated by the manufacturer. The better performance of the FAC group in the pull-out test may be due to its design, which promotes the pure Morse effect in the implant-abutment interface, and the angulation of its internal conical portion.

Electric Saw Face Self-Mutilation in a 22-Year-Old Schizophrenic Man: Case Report.

Schizophrenia is a debilitating psychiatric disorder that affects a large segment of the population. It is managed mainly through pharmacotherapy, and family engagement is mandatory in the process. We present a case of self-mutilation in a 22-year-old man who cut his mandible with an electric saw, trying to modify his chin to better his appearance.

Influence of scanner, powder application, and adjustments on CAD-CAM crown misfit.

STATEMENT OF PROBLEM: The manufacturers of computer-aided design and computer-aided manufacturing (CAD-CAM) systems emphasize that new technologies can improve the marginal fit of dental crowns. However, data supporting this claim are limited. PURPOSE: The purpose of this in vitro study was to investigate the differences among the following fabrication methods on the marginal discrepancy of dental crowns: intraoral optical scanners, powder application, and adjustments of intaglio surface. MATERIAL AND METHODS: A single human premolar was fixed on a typodont and prepared to receive crowns prepared by the CEREC CAD-CAM system. Three fabrication techniques were used: digital scans using the CEREC Bluecam scanner with titanium dioxide powder (TDP), digital scans using the CEREC Omnicam scanner without TDP, and digital scans using the Omnicam scanner with TDP. Five experimental groups (n=10) were designated: Bluecam (group B), Bluecam with adjustments (group BA), Omnicam (group O), Omnicam with adjustments (group OA), and Omnicam with TDP (group OP). The specimens were scanned using microcomputed tomography to measure the vertical, horizontal, and internal fit and volumetric 3-dimensional (3D) internal fit values of each luting space. The paired t test was used to evaluate mean marginal fit change after adjustments within the same group. One-way analysis of variance and post hoc tests were used to compare groups B, O, and OP (α=.05). RESULTS: Mean vertical fit values ±standard deviations of group B=29.5 ±13.2 µm; BA=26.9 ±7.7 µm; O=149.4 ±64.4 µm; OA=49.4 ±12.7 µm; and OP=33.0 ±8.3 µm. Adjustments in the intaglio surface and TDP application statistically influenced the vertical fit of group O (P<.001). The percentage of vertical fit values <75 µm in group B=89.3%, BA=92.7%, O=31.0%, OA=73.5%, and OP=92.0%. Mean horizontal fit values for group B=56.2 ±21.5 µm; 85.8 ±44.4 µm for group BA; 77.5 ±11.8 µm for group O; 102.5 ±16.2 µm for group OA; and 91.4 ±19.4 µm for group OP. Results from group B were significantly different from those of the other test groups (P<.05). The percentages of horizontal misfit were 61.2% in group B; 73.5% in group BA; 88.1% in group O; 92.4% in group OA; and 85.0% in group OP. Volumetric 3D internal fit values in group B were 9.4 ±1.3 mm3; 10.7 ±1.0 mm3 in group BA; 11.8 ±2.1 mm3 in group O; 11.0 ±1.3 mm3 in group OA; and 9.6 ±0.9 mm3 in group OP. The overall results from groups B and OP were better than those of group O, with regard to vertical misfit and volumetric 3D internal fit. CONCLUSIONS: Different intraoral optical scanners, powder application, and internal adjustments influenced the marginal discrepancy of crowns. Crowns fabricated using the Omnicam system had significantly higher vertical discrepancy and volumetric 3D internal fit than those fabricated using the Bluecam scanner with TDP. Adjustments of the intaglio surface improved the vertical fit of crowns made using the Omnicam scanner; however, TDP application before Omnicam scanning improved the vertical fit as well as the volumetric 3D internal fit value of the luting space of crowns.

Influence of indexed abutments on the fracture resistance of internal conical dental implants.

The aim of this study was to evaluate the influence of abutments with a prosthetic index on the fracture resistance of Morse taper dental implants. Morse taper implants were divided into 2 groups (n = 5 per group): a group with an indexed implant and a nonindexed abutment (solid Morse taper universal post; WIS group), and a group with an indexed implant and an indexed abutment (WIP group). Both groups were subjected to bending tests for fracture strength until 5 mm of displacement or implant fracture occurred. Statistical analysis was performed using the Student t test (α = 0.05). There was no statistically significant difference between the mean fracture values, which were 305.8 N and 318.6 N for the WIS group and WIP group, respectively. The presence of a prosthetic index on Morse taper abutments did not influence the resistance to fracture.

Influence of the Prosthetic Index Into Morse Taper Implants on Bacterial Microleakage.

PURPOSE: To evaluate the influence of Morse taper implant index on microleakage. MATERIALS AND METHODS: Thirty implants and abutments were divided into 3 groups (n = 10): CM1 (universal post and implant without index), CM2 (universal post and implant with index), and CM3 (abutment and implant with index). To evaluate the microleakage from the implant inner part, the implants were inoculated with Streptococcus sanguinis solution at a 0.5 McFarland and incubated for 7 days at 37°C in Eppendorf tubes with sterile broth. To evaluate the microleakage into the inner part of implant, these were inoculated with sterile Schaedler broth and immersed in a Fusobacterium nucleatum solution at a 0.5 McFarland. The samples were incubated for 30 days in an anaerobic chamber. RESULTS: Nine samples of each group of the first methodology showed no presented bacterial contamination. No samples of the second methodology demonstrated turbidity of the broth. CONCLUSION: The presence of the prosthetic internal index had no influence on bacterial microleakage of Morse taper implants under static conditions, for both methodologies.

Placement of a distal implant to convert a mandibular removable Kennedy class I to an implant-supported partial removable Class III dental prosthesis: A systematic review.

STATEMENT OF PROBLEM: A number of authors have reported the placement of a distal implant associated with a partial removable dental prosthesis (PRDP) to make this rehabilitation more stable. This strategy may represent an option for resolving the problem of the intrusive movements of the PRDP and for reducing treatment costs. PURPOSE: The purpose of this systematic review was to evaluate the current evidence about the placement of a distal implant associated with a mandibular PRDP to improve patient satisfaction and the clinical performance of the abutment tooth and distal implant. MATERIAL AND METHODS: Two independent prosthetic specialist reviewers conducted this systematic review. The search was performed using selected clinical studies with PRDP associated with distal implants published in English up to May 2014 from the PubMed and Cochrane Library databases. A data extraction form was developed to collect general information: authors, title, year of publication, aim of study, level of evidence, number of participants, number of implants used, implant system, implant length and diameter, abutment type, masticatory performance, patient satisfaction, implant mean bone loss, abutment tooth mean bone loss, prosthetic complications, follow-up period, and implant survival rate. The quality of the selected studies and the risk of bias were also reported. RESULTS: The initial electronic search identified 231 studies, and the manual process identified 15 studies (total of 246 studies). After the title and abstract reading and the removal of duplicates, the full texts of 43 studies were obtained. The articles that did not meet the inclusion criteria were excluded (28 studies), and the data from 15 studies were extracted. Seven were retrospective studies, 1 a crossover pilot study, 2 case series, 2 paired clinical studies, and 3 case reports, demonstrating that a high number of the selected studies were of low methodological quality. Nevertheless, the high survival rates for PRDP associated with dental implants have been described. CONCLUSIONS: The use of a PRDP associated with dental implants to convert a Kennedy class I to class III dental prosthesis benefits patients by improving their satisfaction and masticatory abilities without decreasing implant survival rates. Considering the abutment tooth survival rate, clinical studies with comparable methodology are still lacking to define protocols regarding the use of distal implants associated with PRDP. Long-term, prospective clinical trials are still needed to understand which implant abutments increase abutment tooth survival rate.

Microcomputed tomography marginal fit evaluation of computer-aided design/computer-aided manufacturing crowns with different methods of virtual model acquisition.

This in vitro study used microcomputed tomography to evaluate the marginal fit of crowns fabricated using a chairside computer-aided design/computer-aided manufacturing (CAD/CAM) system with different methods of virtual model acquisition. Crowns were fabricated to fit in a cast containing a single human premolar. Four methods of virtual model acquisition were used: Group 1 (control), digital impressioning of a typodont; Group 2, digital impressioning of a powdered typodont; Group 3, digital impressioning of a regular impression; and Group 4, digital impressioning of a master cast. Statistically significant differences were found between the marginal gap of Group 2 and the other groups (P < 0.05); no differences were found among Groups 1, 3, and 4. The results showed that crowns fabricated using the chairside CAD/CAM system exhibited significantly smaller vertical misfit when a thin layer of powder was applied over the typodont before digital impressioning.

Micro-computed tomography evaluation of marginal fit of lithium disilicate crowns fabricated by using chairside CAD/CAM systems or the heat-pressing technique.

STATEMENT OF PROBLEM: No consensus exists concerning the acceptable ranges of marginal fit for lithium disilicate crowns fabricated with either heat-pressing techniques or computer-aided design and computer-aided manufacturing (CAD/CAM) systems. PURPOSE: The purpose of the study was to evaluate with micro-computed tomography the marginal fit of lithium disilicate crowns fabricated with different chairside CAD/CAM systems (Cerec or E4D) or the heat-pressing technique. MATERIAL AND METHODS: Lithium disilicate crowns were fabricated to fit an in vitro cast of a single human premolar. Three fabrication techniques were used: digital impressions with Cerec 3D Bluecam scanner with titanium dioxide powder, followed by milling from IPS e.max CAD for Cerec; digital impressions with E4D Laser scanner without powder, followed by milling from IPS e.max CAD for E4D; and fabrication from IPS e.max Press by using the lost-wax and heat-pressing techniques. Each crown was fixed to the cast and scanned with micro-computed tomography to obtain 52 images for measuring the vertical and horizontal fit. Data were statistically analyzed by 1-way ANOVA, followed by the Tukey honestly significant difference test (α=.05). RESULTS: The mean values of vertical misfit were 36.8 ±13.9 µm for the heat-pressing group and 39.2 ±8.7 µm for the Cerec group, which were significantly smaller values than for the E4D group at 66.9 ±31.9 µm (P=.046). The percentage of crowns with a vertical misfit <75 µm was 83.8% for Cerec and heat-pressing, whereas this value was 65% for E4D. Both types of horizontal misfit (underextended and overextended) were 49.2% for heat-pressing, 50.8% for Cerec, and 58.8% for E4D. CONCLUSIONS: Lithium disilicate crowns fabricated by using the Cerec 3D Bluecam scanner CAD/CAM system or the heat-pressing technique exhibited a significantly smaller vertical misfit than crowns fabricated by using an E4D Laser scanner CAD/CAM system.

Influence of fabrication method on the marginal fit of temporary restorations.

Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

Accuracy of Conventional and 3D-Printed Casts for Partial Fixed Prostheses.

PURPOSE: To evaluate and compare the accuracy of conventional and 3D-printed casts using five different 3D printers. MATERIALS AND METHODS: In the control group (CG group, n = 5), five conventional impressions using light- and heavy-body polyvinyl siloxane were obtained from the master model, resulting in five stone models. In the test groups, five different scans were performed by a well-trained and experienced clinician using a TRIOS intraoral scanner. All data were exported in STL file format, processed, and sent to five 3D printers. Five casts were manufactured in each printer group: SG (CARES P20, Straumann); FG (Form 2, Formlabs); WG (Duplicator 7, Wanhao); ZG (Zenith D, Zenith); and MG (Moonray S100, Moonray). Measurements of the accuracy (trueness and precision) of the casts obtained from conventional elastomeric impressions and 3D-printing methods were accomplished using a 3D analysis software (Geomagic Control). RESULTS: The FG group showed the lowest values for trueness (indicating a value closer to real dimensions), which were similar to the SG group only (P > .05). MG, WG, and ZG groups presented higher values and were similar compared to each other. Data on precision demonstrated that all 3D-printed groups showed lower values for precision (smaller deviation) when compared to the CG. CONCLUSIONS: The trueness depends on the chosen 3D printer. All of the tested 3D printers were more precise than cast models obtained from conventional elastomeric impressions.

Mandibular implant-assisted removable partial denture - Kennedy Class I to Class III modification - Case series with masticatory performance and satisfaction evaluation.

In this work, we present 5 cases of Kennedy Class I patients with atrophic posterior mandible treated with the placement of 01 short WS Neodent® implant and a healing screw to support the removable prosthesis, transforming them into Kennedy Class III patients. To quickly evaluate and verify the benefit of this treatment, masticatory performance was evaluated with maximum bite force and chewing ability. A VAS questionnaire was also applied for a practical preoperative and postoperative evaluation of overall quality of life-changing for the patient after this treatment. This treatment plan was planned in order to reduce drastically the treatment costs and morbidity, and to enhance oral function and the quality of life for these patients. Also, this treatment lead to residual bone preservation, enhanced masticatory function and patient satisfaction. Especially in countries with a large number of patients with missing teeth and socio-economic difficulties to be fully rehabilitated with dental implants and fixed prosthesis treatment options with reduced costs are important to be in our armamentary os possibilities. Key words:Dental implants, masticatory performance, chewing, oral function, mixing ability.

Effect of thickness and shade of CAD/CAM composite on the light transmission from different light-curing units.

The thickness and shade of a restoration will affect the transmission of light from the light-curing unit (LCU). This study determined the power (mW), spectral radiant power (mW/nm), and beam profile of different LCUs through various thicknesses and shades of a CAD-CAM resin composite (BRAVA Block, FGM). Five thicknesses: 0.5; 0.75; 1.0; 1.5, and 2.0 mm, in three shades: Bleach; A2 and A3.5 of a CAD-CAM resin (n = 5). Two single-peak LCUs: EL, Elipar DeepCure-S (3M Oral Care); and OP, Optilight Max (Gnatus), and one multiple-peak LCU: VL, VALO Grand (Ultradent), were used. The LCUs were positioned touching the surface of the BRAVA Block. The power and emission spectrum were measured using a fiberoptic spectrometer attached to an integrating sphere, and the beam profiles using a laser beam profiler. The effect of the material thickness on the light attenuation coefficients was determined. VL and EL delivered more homogeneous beam profiles than OP. The type of the BRAVA Block had a significant effect on the transmitted power, and wavelengths of transmitted light (p < 0.001). There was an exponential reduction in the power and emission spectrum as the thickness of the BRAVA Block increased (p < 0.001). The light transmission through the A2 shade was least affected by the thickness (p < 0.001). The attenuation coefficient was higher for the violet light and higher for A3.5 than the A2 or Bleach shades. No violet light from the VL could be detected at the bottom of 2.0 mm of the BRAVA Block.

Mechanical Behavior of One-Piece and Two-Piece Tapered Prosthetic Abutments with 11.5 and 16 Degrees.

The objective of this study is to examine the mechanical behavior of two-piece abutments (Morse taper with 16° internal angulation and Morse taper with 11.5° internal angulation) before and after cyclic fatigue testing, following ISO 14801:2016 guidelines. The specimens were divided into three groups: a modified Morse taper with a taper angle of 16° (GM group), a conventional Morse taper (taper angle of 11.5° deg) with a two-piece (CMt group), and one-piece abutments (CMo group). Each experimental group was formed by ten implants and ten abutments (n = 10) for a total of 30 specimens (n = 30). The abutments were tightened and loosened, and a fatigue test was applied with 15 Hz and 5 × 106 cycles. Subsequently, the abutments were loosened, and a pull-out test was performed on the CMt group. Finite element analysis (FEA) was conducted on stress concentration regions. The statistical analysis of the loosening test was performed using two-way ANOVA and Tukey's tests (p < 0.05) to compare screw loosening within each group and between the groups with and without mechanical fatigue. Significant differences were found among the three groups in the loosening test when analyzing the values with and without fatigue (p < 0.001) within each group. When the groups were compared with each other, there was also a significant difference between them (p < 0.001), except between groups GM and CMt without fatigue (p = 0.840). In the pull-out test of the CMt group, the sample exhibited frictional locking only after fatigue (mean = 94.2 N). The FEA demonstrated a varied stress distribution in all groups. The stress was found to be more concentrated in the upper third and middle third regions of the implant, as well as in the opposite region of the load application for all three groups. Although the CMo group showed lower rates of loosening, it displayed a poorer stress distribution in comparison to the GM and CMt groups. On the other hand, the CMt group exhibited a satisfactory frictional lock after undergoing the fatigue tests.

Physical and mechanical properties of four 3D-printed resins at two different thick layers: An in vitro comparative study.

OBJECTIVES: This in vitro comparative study aimed to evaluate the physical and mechanical properties of four 3D-printed resins with two different thickness layers. METHODS: Four printed resins (VarseoSmile Crown Plus, VSC; NexDent C&B MFH, MFH; Nanolab 3D, NNL; and Resilab 3D Temp, RSL) were printed with 50 µm and 100 µm layer thickness, resulting in 80 bars measuring 25 × 2×2 mm. The specimens underwent a Raman spectroscopy for degree of conversion, confocal laser scanning microscopy for surface roughness (Sa), three-point bending test for flexural strength and elastic modulus, and a Vickers hardness test (VHN). Data was tested for normality using the Shapiro-Wilk, two-way ANOVA, and Tukey test (α = 0.05) for statistical analysis. RESULTS: The layer thickness affected all performed tests, but the elastic modulus (p < 0.001). Specimens with 100 µm showed, in general, worse results outcomes than those with 50 µm (p < 0.001). However, within the limitations of this comparative in vitro study, it could be concluded that the tested resins and layer thicknesses directly influenced physical and mechanical properties. SIGNIFICANCE: The physical and mechanical properties of three-dimensional printed restorations can be affected by the layer thickness, which can interfere with the choice of the 3D printing resin for a desired clinical outcome.

Accuracy of conventional and 3D printed casts for partial fixed prosthesis.

PURPOSE: To evaluate and compare the accuracy of conventional and 3D-printed casts using five different 3D printers. MATERIALS AND METHODS: In the control group (CG group, n = 5), five conventional impressions using light- and heavy-body polyvinyl siloxane were obtained from the master model, resulting in five stone models. In the test groups, five different scans were performed by a well-trained and experienced clinician using a TRIOS intraoral scanner. All data were exported as an STL file format, processed, and sent to five 3D printers. Five casts were manufactured in each group: SG (CARES P20, Straumann); FG (Form 2, Formlabs); WG (Duplicator 7, Wanhao); ZG (Zenith D, Zenith); and MG (Moonray S100, Moonray). Measurements of the accuracy (trueness and precision) of the casts obtained from conventional elastomeric impressions and 3D-printing methods were accomplished using a 3D analysis software (Geomagic Control). RESULTS: The FG group showed the lowest values for trueness (closer to real dimensions), which were similar to the SG group only (P > .05). Groups MG, WG, and ZG presented higher values and were similar compared to each other. Data on precision demonstrated that all 3D-printed groups showed lower values for precision (smaller deviation) when compared to the control group. CONCLUSION: The trueness depends on the chosen 3D printer. All of the tested 3D printers were more precise than cast models obtained from conventional elastomeric impressions.

Microstructural and mechanical analysis of two CAD-CAM lithium disilicate glass-reinforced ceramics.

The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.

Influence of fabrication method on the marginal fit of temporary restorations

Abstract Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

Can intra-radicular cleaning protocols increase the retention of fiberglass posts? A systematic review.

The presence of residues within the root canal after post-space preparation can influence the bond strength between resin cement and root dentin when using fiberglass posts (FGPs). Currently, there is no consensus in the literature regarding what is the best solution for the removal of debris after post-space preparation. This systematic review involved "in vitro" studies to investigate if cleaning methods of the root canal after post-space preparation can increase the retention of FGPs evaluated by the push-out test. Searches were carried out in PubMed (MEDLINE) and Scopus databases up to July2017. English language studies published from 2007 to July 2017 were selected. 475 studies were found, and 9 were included in this review. Information from the 9 studies were collected regarding the number of samples, storage method after extraction, root canal preparation, method of post-space preparation, endodontic sealer, resin cement, cleaning methods after post-space and presence of irrigant activation. Five studies presented the best results for the association of sodium hypochlorite (NaOCl) and ethylenediamine tetra-acetic acid (EDTA), while in the other 4 studies, the solutions that showed improved retention of FGPs were photon-induced photoacoustic streaming (PIPS), Qmix, Sikko and EDTA. The results showed heterogeneity in all comparisons due to a high variety of information about cleaning methods, different concentrations, application time, type of adhesive system and resin cements used. In conclusion, this review suggests that the use of NaOCl/EDTA results in the retention of FGPs and may thus be recommended as a post-space cleaning method influencing the luting procedure.

Effect of thickness and shade of CAD/CAM composite on the light transmission from different light-curing units

Abstract The thickness and shade of a restoration will affect the transmission of light from the light-curing unit (LCU). This study determined the power (mW), spectral radiant power (mW/nm), and beam profile of different LCUs through various thicknesses and shades of a CAD-CAM resin composite (BRAVA Block, FGM). Five thicknesses: 0.5; 0.75; 1.0; 1.5, and 2.0 mm, in three shades: Bleach; A2 and A3.5 of a CAD-CAM resin (n = 5). Two single-peak LCUs: EL, Elipar DeepCure-S (3M Oral Care); and OP, Optilight Max (Gnatus), and one multiple-peak LCU: VL, VALO Grand (Ultradent), were used. The LCUs were positioned touching the surface of the BRAVA Block. The power and emission spectrum were measured using a fiberoptic spectrometer attached to an integrating sphere, and the beam profiles using a laser beam profiler. The effect of the material thickness on the light attenuation coefficients was determined. VL and EL delivered more homogeneous beam profiles than OP. The type of the BRAVA Block had a significant effect on the transmitted power, and wavelengths of transmitted light (p < 0.001). There was an exponential reduction in the power and emission spectrum as the thickness of the BRAVA Block increased (p < 0.001). The light transmission through the A2 shade was least affected by the thickness (p < 0.001). The attenuation coefficient was higher for the violet light and higher for A3.5 than the A2 or Bleach shades. No violet light from the VL could be detected at the bottom of 2.0 mm of the BRAVA Block.