Dentsply Sirona Research Articles

Computation of the fracture probability and lifetime of all ceramic anterior crowns under cyclic loading - An FEA study.

To predict the lifetime and fracture probability of anterior crowns made of a lithium disilicate glass-ceramic (IPS e.max CAD, LD, Ivoclar Vivadent, Liechtenstein) and a zirconia-containing lithium silicate glass-ceramic (Celtra Duo, ZLS, Dentsply Sirona, USA) under cycling loading. Three-point bending tests were conducted to measure the viscoelastic parameters. These parameters are used to compute the residual stresses of the anterior crown after crystallization. In the next analysis, the cyclic loading on the anterior crown was calculated. Based on this combined stress state (residual stress and stress state due to external cyclic loading), the life cycle and fracture probability of the anterior crown was calculated using the CARES/Life software. Finally, fatigue experiments were carried out to compare and validate the results of the computations. Although a sound qualitative comparison of the lifetime of both materials can be done using this methodology, the calculated fracture probability of the anterior crown for both materials was very low in comparison with the fatigue test results using the fatigue parameters determined from the experiments. In order to achieve good correspondence with the experimental results, the SCG exponent n for both materials should be modified by a correlation factor of 0.38. Using this modified computational strategy, the results of the time-consuming fatigue tests for dental glass-ceramics can be closely predicted. This methodology can be integrated into the development process of new glass-ceramic materials in order to save time and costs.

Evaluation of Dimensional Stability and Occlusal Wear of Additively and Subtractively Manufactured Resin-Based Crowns after Thermomechanical Aging

The knowledge on the surface deviations and wear of recently introduced additively or subtractively manufactured materials indicated for definitive prosthesis is limited. The aim of this present study was to evaluate the external surface and mesiodistal width deviation and the occlusal surface wear of one additively manufactured composite resin (MS) and three subtractively manufactured resins (nanographene-reinforced polymethylmethacrylate (GR), conventional polymethylmethacrylate (PMMA), and reinforced composite resin (BC)) after thermomechanical aging. Molar-shaped crowns were fabricated in the tested materials and digitized with an intraoral scanner (CEREC Primescan; Dentsply Sirona, Bensheim, Germany). Each crown was subjected to thermomechanical aging and rescanned with the same scanner. A three-dimensional analysis software (Geomagic Control X v.2022.1; 3D Systems, Rock Hill, SC, USA) was used to calculate the deviations on the external surface, mesiodistal width, and wear on the occlusal surfaces of the tested crowns. Data were analyzed using one-way ANOVA and Tukey’s tests (α = 0.05). MS had higher external surface deviations than PMMA and GR (p ≤ 0.038) and higher mesiodistal width deviations than PMMA and BC (p = 0.004). BC and GR had higher volume loss than PMMA (p ≤ 0.002). The additively manufactured composite resin was more prone to deviations, while reinforced composite resin had lower wear resistance than most of the tested materials.

Advanced lithium disilicate: A comparative evaluation of translucency and fatigue failure load to other ceramics for monolithic restorations

The aim of this in vitro study was to evaluate the surface roughness, translucency, fatigue failure load (FFL), and number of cycles for fatigue failure (CFF) of a recently released lithia-based material called advanced lithium disilicate and three other ceramics indicated for monolithic restorations. First, ALD (advanced lithium disilicate, CEREC Tessera, Dentsply Sirona), LD (lithium disilicate, IPS e. max CAD, Ivoclar), LS (lithium silicate-disilicate, Suprinity, Vita Zahnfabrik), and 4Y-PSZ (Yttria-stabilized zirconia, IPS e.max ZirCAD MT, Ivoclar) discs (n = 15, Ø = 10 mm and thickness = 1.0 mm) were fabricated from CAD/CAM blocks/discs, A2 shade. The discs were sintered/crystallized and subsequently analyzed by a rugosimeter (Mitutoyo SJ-410) to determine Ra and Rz surface roughness parameters. Next, they were evaluated to determine the translucency parameter (TP) using a bench-top spectrophotometer (SP60, EX-Rite). The discs were subsequently cemented to glass fiber epoxy resin discs, and the specimens were tested under cyclic loading (Step-test), immersed in distilled water at a frequency of 20 Hz, with an initial cyclic load of 200 N for 5,000 cycles and increments of 50 N every 10,000 cycles until failure. Fatigue failure load (FFL) and number of cycles for fatigue failure (CFF) were recorded for subsequent Kaplan Meier analysis, with post-hoc Mantel-Cox and Weibull analysis (α = 0.05). Complementary fractographic, topographic and energy dispersive spectroscopy analyses (EDS) were performed. 4Y-PSZ showed higher survival (p < 0.05), with higher FFL and CFF (1077 N; 180,333 cycles), followed by LD (980 N; 161,000 cycles), LS (937 N; 152,333 cycles) and ALD (910 N; 147,000 cycles). No differences were observed between the tested groups regarding Weibull modulus. ALD presented TP (28.14) equal to DL (28.27) and higher than LS (25.51). All lithia-based materials had higher translucency than 4Y-PSZ (TP = 8.62) (p < 0.05). ALD appears to have a similar elemental composition to LD and LSD for oxygen and silicon. ALD and LSD have a similar zirconium content. Fractures originated on the cemented surface of the ceramic discs. Lithia-based ceramics showed lower surface roughness, with ALD (Ra = 0.04 μm; Rz = 0.66 μm) showing the lowest values (p < 0.05). Despite showing lower FFL when compared to LD and 4Y-PSZ, ALD has compatible translucency and mechanical fatigue performance with its indication for fabricating monolithic, anterior and posterior adhesively cemented single-unit restorations. However, further studies are needed to substantiate its clinical performance.

Effect of sintering time on microstructure and optical properties of yttria-partially stabilized monolithic zirconia

ObjectivesTo evaluate the impact of speed sintering on the microstructure and optical properties of 3 and 5 mol% yttria-partially stabilized monolithic zirconias. Methods120 plate-shaped zirconia specimens (10x10x 0.4 mm) were prepared from three commercial 5 mol% yttria-partially stabilized zirconia blocks (5Y-PSZs); Katana UTML (Kuraray Noritake), Cercon xtML (Dentsply Sirona), and Zolid FX white (Amann Girrbach), and two commercial 3 mol% yttria-partially stabilized zirconia blocks (3Y-PSZs); Lava Plus (3 M ESPE) and InCoris (Sirona, GmbH). Specimens were either conventional sintered (CS) using a 7-hour program or speed sintered (SS) using a quick 90-minute program. The microstructure was inspected with a scanning electron microscope (SEM), and phase fractions were detected using x-ray diffraction analysis (XRD). Translucency (TP00), and contrast ratio (CR) were obtained using a spectrophotometer (VITA Easyshade V). Color difference (ΔE00) between both sintering processes was calculated with the CIEDE2000 formula. ΔE00 up to 1.8 was set as the acceptability threshold. Data were analyzed using two-way ANOVA, Krusakll-Wallis, and Mann-Whitney U tests. (n = 12, α = .05). ResultsGrain size was significantly decreased after SS for all tested materials (P < .0001). The average grain sizes of 5Y-PSZs were significantly larger than those of 3Y-PSZs. The atomic structure, microstructure, and transparency of CS and SS were all affected by the amount of yttria, the size of the crystals, and tetragonality. SS significantly reduced TP00 (F = 7135.95, P < 0.0001) and increased CR (F = 453.21, P < 0.0001). The CS Katana presented the highest TP00 and lowest CR value. ΔE00 between the CS and SS groups were clinically acceptable except for Lava, which had values above the set threshold (1.89). SignificanceSS altered the grain size and internal structure of the tested materials, which was reflected in translucency.

Positional transfer accuracy of titanium base implant abutment provided by two different scan body designs: an invitro study

BackgroundThe variabilities in design and material of scan bodies have a major role in the positional transfer accuracy of implants. The purpose of this invitro study was to compare the 3D transfer accuracy (trueness and precision) of titanium base (TB) abutment position provided by 2 different scan bodies: one-piece scan body (SB) in comparison to two-piece healing abutment and scan peg (HA-SP).MethodsA maxillary model with a dummy implant in the 2nd premolar (Proactive Tapered Implant; Neoss) was 3D printed and TB (Ti Neolink Mono; Neoss) was tightened on the implant and scanned by using a laboratory scanner (inEos X5; Dentsply Sirona) (reference scan). An SB (Elos Medtech) and an HA-SP (Neoss) were subsequently connected to the implant and were scanned 10 times each by using the same scanner (test scans). All the scans were exported as STL files and imported into CAD software where the TBs were formed. Test scans were superimposed on reference scans for transfer accuracy analysis using 3D metrology software (GOM Inspect; GOM GmbH) in terms of angular deviation in vertical and horizontal directions, linear deviation in each XYZ axis of TBs and total linear deviation in all axes. Statistical analysis was done using independent sample t test. When Levene’s test for equality of variances was significant, Welch’s t-test was used. (P value < 0.05)ResultsSignificant differences were found amongst the tested groups in both angular and linear deviation in terms of trueness with less deviation values for the SB group (P < 0.001). For the precision, significant differences were found amongst the tested groups in angular deviation in vertical direction with less deviation value for the SB group compared to HA-SP group (P < 0.001). However, no significant difference was found between the tested groups regarding the angular deviation in horizontal direction (P = 1.000). Moreover, significant differences were found amongst the tested groups in linear deviations with less linear deviations in XYZ axes for SB compared to HA-SP group (P = 0.020, < 0.001, = 0.010 respectively).ConclusionsSB showed less angular and linear deviation values in the 3D positional transfer of TB than HA-SP indicating higher degree of accuracy of SB.

Marginal Fit Evaluation of Zirconia Substructure Computer-Aided Design and Manufacturing (CAD/CAM) by Scanning Electron Microscope

Purpose. This in vitro study compared the vertical marginal discrepancy (MD) and absolute marginal discrepancy (AMD) between the zirconia substructure and titanium (Ti)-base abutment before and after cementation. Material and methods. An intraoral scanner (CEREC Omnicam scanner; Dentsply Sirona) was used to scan the dental model of missing tooth 36 and obtain a three-dimensional virtual model. It was designed and milled for 25 zirconia superstructures (inCoris ZI meso F2 L, Dentsply Sirona). The samples were cemented to Ti bases. The MD and AMD were measured for each sample by using a scanning electron microscope (SEM) before and after cementation. Results. The overall mean values of MD measurements before and after cementation were 14.12 μm and 20.28 μm, respectively. The overall mean values of AMD measurements prior to and after substructure cementation on the Ti base were 54.85 μm and 116.0 μm, respectively. ANOVA revealed significant differences in MD (p = 0.001) and AMD (p &lt; 0.001) before and after cementation. Conclusions. Significant differences were observed in MD and AMD values before and after cementation. The MD and AMD values were significantly lower before cementation than after cementation. The mean MD and AMD values were clinically acceptable.

Finite Element Analysis of Fracture Resistance of Mandibular Molars with Different Access Cavity Designs

IntroductionThis study aimed to assess the fracture resistance of mandibular first molars after preparation with 3 different access cavity designs and 2 rotary systems using finite element analysis. MethodsSix 3-dimensionally printed mandibular first molars simulating natural teeth received traditional, conservative, and ultraconservative (truss) access cavity preparations. The root canals in each group were instrumented with either XP-Endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) or TruNatomy (Dentsply Sirona, Ballaigues, Switzerland) rotary files. The models were individually digitized, and micro–computed tomographic scans were transferred to Mimics software (Materialise NV, Leuven, Belgium) to create a geometric model of the tooth. The designed model was exported to 3-matic software (Materialise NV), and STL files were transferred to Geomagic Design X (3D Systems, Rock Hill, SC). Point cloud data were used for surfacing and transferred to ANSYS software (Ansys, Canonsburg, PA). A 200-N superficial force was applied vertically to the buccal cusps and central fossa, and the maximum and minimum equivalent von Mises stress values were calculated and reported. ResultsThe traditional and ultraconservative access cavity designs yielded the highest and the lowest von Mises stress values, respectively. In the ultraconservative cavity design, the stress values in pericervical dentin were lower in canal preparation with TruNatomy compared with XP-Endo Shaper. In the traditional and conservative cavity designs, stress was lower in the first 2 mm from the cementoenamel junction in the XP-Endo Shaper group and in the next 3 mm in the TruNatomy group. ConclusionsStress was lower in the ultraconservative and conservative cavity designs compared with the traditional design. Also, root canal preparation with TruNatomy yielded lower stress values in general compared with XP-Endo Shaper.

Evaluation of the use of different intraoral scanners for auricular prosthetic reconstruction

The use of intraoral optical scanners has been introduced for direct digital data acquisition in maxillofacial prosthetics, but their clinical accuracy has not been evaluated sufficiently. The purpose of this observational study was to evaluate the use of different intraoral scanners for extraoral maxillofacial digitization of an ear and to assess visually the clinical outcome of the generated 3-dimensional ear casts. A selected intact ear was scanned by using 3 different intraoral optical scanners: CEREC Primescan (Dentsply Sirona), Medit i700 (Medit Corp) and Panda P2 (Pengtum Technologies). Three-dimensional printed auricular casts were fabricated from the obtained scans, and a questionnaire administered to assess visually the clinical outcome of the generated casts. Comparisons between scanners were done by using the Kruskal-Wallis test followed by the post hoc test with Bonferroni correction when results were significant. The Wilcoxon Sign Rank test was used to compare the responses of both the prosthodontists and the lay personnel. All tests were 2-tailed (α=.05). The 3-dimensional printed auricular casts fabricated from the data acquired by using Primescan and Medit i700 scanners showed a statistically significant difference in matching scores when compared with the Panda P2 scanner (P<.001). Digital ear scanning with the Primescan and Medit i700 intraoral scanners should produce auricular prostheses that more closely match the normal ear when compared with those scanned by the Panda P2 scanner.

Effect of Endo-Z bur or Bladesonic ultrasonic tip on the adaptation of filling material. A micro-CT study.

This study aimed to evaluate the effect of apicoectomy performed with a bur or an ultrasonic tip on the adaptation of the filling material to root canal dentin. Twenty human mandibular incisors were selected and prepared with a ProDesign Logic system up to diameter 40/.05. The root canals were filled with Bio-C Sealer (Angelus, PR, Brazil) using the single cone technique and were stored at 37ºC and 95% relative humidity for 7 days. After this period, the apicoectomy of the 3 millimeters of the root apex was performed using Endo-Z bur (Dentsply Sirona) or Bladesonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, Brazil) (n=10). The specimens were scanned by micro-computed tomography (micro-CT; SkyScan 1176) with a voxel size of 8.74 µm after obturation and after apicoectomy. The percentage of voids at the interface between the filling material and the root canal wall was evaluated in the apical 4 mm of the root after apicoectomy, besides the time cutting to both devices. The data obtained were submitted to paired and unpaired t-tests (α = 0.05). Endo-Z and Bladesonic increased the percentage of voids between the filling material and the dentin after apicectomy (p<0.05), and they were similar (p>0.05). Endo-Z has a shorter time to perform apicoectomy compared to Bladesonic (p<0.05). Apicectomies with Endo-Z or Bladesonic could harm the material/dentin interface, while the Endo-Z bur was faster than the Bladesonic ultrasonic tip.

Positional trueness of three removable die designs with different root geometries manufactured using stereolithographic 3D printing

Statement of problemThree-dimensional (3D) printed casts are a suitable alternative to dental stone casts. Contemporary dental design computer programs permit designing definitive casts with removable dies with different root geometries and retention mechanisms. Studies on the positional trueness of 3D-printed removable dies with different root geometries are lacking. PurposeThe purpose of this in vitro study was to investigate the 3D displacements of three 3D-printed removable die designs with different root geometries. Material and methodsThe digital file of a dental stone alveolar cast with root-form removable dies (MOD UJ IV Fixed Prosthetics; Ivoclar AG) was used as a reference to create 3 removable die and alveolar cast designs (Root Form, RF; Conical, CON; Cylindric, CYL) with different root geometries in 2 dental design computer programs (DentalCAD 3.1 Rijeka; exocad; GmbH; InLab CAD 22.0; Dentsply Sirona). 3 equidistant Ø1-mm spheres (C, Cervical; M, Middle; O, Occlusal) were designed on the buccal surface of the coronal portion of the removable die to evaluate their displacement. A total of 45 alveolar casts with 45 removable dies were fabricated using a stereolithographic 3D printer (Form 3; Formlabs); each die group consisted of 15 specimens. After fabrication and postprocessing, the specimens were scanned, and their digital files were analyzed in a metrology-grade computer program to evaluate the displacement of the removable dies with respect to the position of the die in the master reference file. Subsequently, the data were analyzed using a 3-way analysis of variance (ANOVA) followed by step-down Bonferroni-corrected pairwise comparisons (α=.05). ResultsTwo statistically significant 2-way interactions were detected between the independent variables, die design and direction (P<.001), and location and direction (P<.001). The post hoc analysis identified significant differences between the displacement values of RF and CYL (P<.001) and RF and the CON (P<.001) designs on the Y axis. The measured displacements were statistically different between the C and O locations on the Y axis (P=.001) and the M and O locations on the Z axis (P=.006). ConclusionsThe root geometry of a 3D-printed removable die and alveolar cast can affect seating, and variable degrees of tipping of the removable die can be seen. The seating and congruence of the removable die with the interocclusal space and relationships observed intraorally should be confirmed before adjusting indirect restorations.

Dentsply Sirona collaborates with the University of Bristol to open new state-of-the-art dental school in Bristol city centre

Dentsply Sirona collaborates with the University of Bristol to open new state-of-the-art dental school in Bristol city centre

An In Vitro Study Comparing the Impact and Flexural Strength of Leucitone 199 Denture Base Resin and Conventional Denture Base Resin Enhanced With Glass Fibre Mesh and Polyethylene Fibre Mesh.

Purpose The purpose of this in vitro study was to compare and evaluate the impact and flexural strength of conventional denture base resin reinforced with glass fiber mesh and polyethylene fiber mesh with Leucitone 199 denture base resin (Dentsply Sirona, Charlotte, USA). Leucitone is an expensive denture base material. To come up with a cheaper solution for reinforced denture base resin with superior impactand flexural strength was the goal of this study Material and methods The specimens (maxillary denture bases) were fabricated using a standard polyvinylsiloxane mold with conventional heat-cured polymethyl methacrylate resin (ISO 1567:1999). The specimens were divided into three groups (n = 10). Group I specimens, or the control group, were pre-reinforced Leucitone 199. Group II and Group IIIspecimens were reinforced with 3% by weight of glass fibers and polyethylene fibers in weave form, respectively. All the specimens were immersed in water for 1 week before testing. The impact strength was measured with a falling weight impact testing machine. One-way analysis of variance and Tukey's post hoc test were used for statistical analysis. The flexural strength was measured with the three-point bending test in a universal testing machine. Results The highest impact strength values were exhibited by the Leucitone 199 group, followed by the polyethylene fiber mesh group, followed by the glass fibers mesh group. The highest flexural strength was seen in the Leucitone 199 group, followed by the glass fiber mesh group. The least flexural strength was seen in the polyethylene fiber mesh-reinforced group. Conclusion Reinforcement of maxillary complete dentures showed a significant increase in impact strength and flexural strength, but not in comparison to pre-reinforced Leucitone 199 dentures. By using pre-impregnated glass and polyethylene fibers in woven form (prepregs), the impact strength of the denture bases can be increased effectively.

Effect of Dentine Conditioning with Silver Diamine Fluoride on Wettability of Root Canal Sealers.

To test the null hypothesis that dentine treatment with silver diamine fluoride (SDF), a potent antimicrobial agent, following use of proteolytic and chelating agents does not influence the wettability of an epoxy resin (AH Plus, Dentsply Sirona, Charlotte, NC, USA) and a tricalcium silicate sealer (BioRoot RCS, Septodont, Saint-Maur-des-Fossés, France). Seventy-two intraradicular dentine specimens were divided into six groups based on the final irrigation solutions used: 2.5% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA) (NaOCl-EDTA) (group 1); NaOCl-EDTA-NaOCl (group 2); NaOCl-EDTA followed by 3.8% SDF, NaOCl-EDTA-SDF (group 3); NaOCl-EDTA-NaOCl-SDF (group 4); SDF (group 5) and saline (group 6). After irrigation, the specimens were divided into subgroups according to the sealer used, AH Plus or BioRoot RCS. Contact angles were measured using a contact angle analyser. The data were analysed using an independent t test, one-way analysis of variance (ANOVA) and Tamhane T2 post hoc test, with the level of significance set at P < 0.05. In the epoxy resin sealer group, dentine surfaces treated with only SDF showed the lowest contact angle. This was significantly less than the groups in which NaOCl was used as the final irrigant (P < 0.05). In the tricalcium silicate-based sealer group, the groups treated with SDF showed significantly greater contact angles when compared to the control group (P < 0.05). It was concluded that SDF conditioning of dentine favours the wettability of epoxy resin sealer but is detrimental to the wettability of tricalcium silicate sealer.

Ultrathin lithium disilicate and translucent zirconia crowns for posterior teeth: Survival and failure modes.

To evaluate the reliability and failure modes of ultrathin (0.5 mm) lithium disilicate, translucent and ultra-translucent zirconia crowns for posterior teeth restorations. Fifty-four mandibular first molar crowns of three ceramic materials: (1) Lithium disilicate (e.max CAD, Ivoclar Vivadent), (2) 3Y-TZP (Zirconn Translucent, Vipi), and (3) 5Y-PSZ (Cercon XT, Dentsply Sirona), with 0.5 mm of thickness were milled and cemented onto composite resin abutments. Eighteen samples of each group were tested under mouth-motion step-stress accelerated life testing in a humid environment using mild, moderate, and aggressive profiles. Data was subjected to Weibull statistics. Use level curves were plotted and reliability was calculated for a given mission of 100,000 cycles at 100, 200, and 300 N. Fractographic analyses of representative samples were performed in scanning electron microscope. Beta (β) values suggest that failures were dictated by material's strength for lithium disilicate and by fatigue damage accumulation for both zirconias. No significant differences were detected in Weibull modulus and characteristic strength among groups. At a given mission of 100,000 cycles at 100 N, lithium disilicate presented higher reliability (98% CB: 95-99) regarding 3Y-TZP and 5Y-PSZ groups (84% CB: 65%-93% and 79% CB: 37&-94%, respectively). At 200 N, lithium disilicate reliability (82% CB: 66%-91%) was higher than 5Y-PSZ (20% CB: 4%-44%) and not significantly different from 3Y-TZP (54% CB: 32%-72%). Furthermore, at 300 N no significant differences in reliability were detected among groups, with a notable reduction in the reliability of all materials. Fractographic analyses showed that crack initiated at the interface between the composite core and the ceramic crowns due to tensile stress generated at the intaglio surface. Ultrathin lithium disilicate crowns demonstrated higher reliability relative to zirconia crowns at functional loads. Lithium disilicate and zirconia crown's reliability decreased significantly for missions at higher loads and similar failure modes were observed regardless of crown material. The indication of 0.5 mm thickness crowns in high-load bearing regions must be carefully evaluated. Ultraconservative lithium disilicate and zirconia crowns of 0.5 mm thickness may be indicated in anterior restorations and pre-molars. Their clinical indication in high-load requirement regions must be carefully evaluated.

Impact of Implant Diameter on Success and Survival of Dental Implants: An Observational Cohort Study

Narrow-diameter implants (NDIs) can be inserted instead of standard dental implants (SDIs) in sites with limited space and bone availability. The aim of this study was to evaluate the effect of implant diameter on peri-implant bone, attached mucosa, and on the associated probability of implant success and survival. The implants with progressive thread design and platform switching (Ankylos®, Dentsply Sirona; Mannheim, Germany) investigated were identified retrospectively and assigned to two groups based on their diameter: 3.5 mm (NDIs) and 4.5 mm (SDIs). Peri-implant bone loss was analyzed based on available radiographs. Descriptive and implant-associated factors were gathered from patient files. Data were statistically analyzed using the Kolmogorov–Smirnov–Lilliefors test and regression analyses. The level of significance was p ≤ 0.05. Results: In total, data for 415 implants in 194 patients were included in the study. Ten-year survival was 95.8% (NDIs) and 91.1% (SDIs). Implant diameter had no significant effect on peri-implant crestal bone loss (p = 0.098) or on the width of the attached gingiva (p = 0.052). Survival and success rates of NDIs were like or slightly better than those of SDIs. Because implant diameter had no effect on peri-implant tissue, NDIs can be recommended in selected cases.

Clinical and Radiographic Evaluation of OsseoSpeed EV Implants.

To evaluate the survival rate (primary outcome) and the marginal bone loss (secondary outcome) of the OsseoSpeed EV Implants (Astra Tech Implant System, Dentsply Sirona Implants; hereinafter EV implants) used in a wide range of clinical scenarios and followed up to 8 years in a nonuniversity setting. All EV implants consecutively placed from 2013 to 2021 in a private dental clinic were included, and medical and radiologic records were retrospectively investigated. Independent reviewers collected 11 data types as potential influencing variables and measured the mesial and distal marginal bone levels to the nearest 0.5 mm on available radiographs, either panoramic or periapical. Tables of descriptive statistics were made at implant and patient levels. Univariate and multiple Cox regression models were adjusted for clustering effects and determined the hazard ratio (HR) and odds ratio (OR) for each independent variable collected. The study sample consisted of 597 EV implants and 235 patients. During a mean follow-up of 42.1 ± 23 months (range: 10 to 94 months), 44 implants were lost (7.4%)-34 early (5.7%) and 10 late (1.7%)-in 38 patients (16.1%). The overall survival rate (SR) was 92.6% (CI: 90.5% to 94.7%), and the proportion of patients with all their implants surviving was 83.8% (CI: 79.1% to 88.5%). At the end of the study, the probability of survival of an implant that did not fail early was 98.2% (CI: 97.1% to 99.3%). Implant-level analysis identified two significant variables: implant diameter (HR 0.37, P = .009**) and immediate postextraction placement (HR 2.35, P = .025*). At the patient level, bruxism (OR = 3.29; P = .009**), history of periodontitis (OR = 2.18, P = .030*), and the number of implants placed (OR = 1.43; P = .001**) were found to be statistically significant. After removing dropouts and early failures from a sample of 528 implants, 412 (78%) had a marginal bone loss (MBL) ≤ 0 mm at the end of the observation time, and 106 surviving implants (22%) showed a mean MBL of 1.42 ± 1.08 mm (range: 0.25 to 6.75 mm). An overall medium-term SR of the EV implants was 92.6%. Four of five EV implants showed a mid-term MBL ≤ 0 mm, and 91.86% of implants completed the observation period with an MBL < 2 mm. Thus, the EV implant system was shown to be a valid alternative for routine use in a nonuniversity setting. Clinicians should remember that there is no 100% implant survival in everyday practice and that bruxism, periodontitis, narrow-diameter implants, and immediate placement are risk factors for a higher failure rate.

Comparison of Two Different Intraoral Scanners for Determination of Caries Related Volume Loss in Caries Removal

Objective: The study aimed to compare cavity volume data obtained with two different intraoral scanners. Methods: One hundred extracted molar teeth were divided into groups according to ICDAS-II classification, and scanned with Cerec Omnicam (Dentsply Sirona) and iTero Element Flex (Align Technology). The caries-infected tissues were removed regarding either minimally invasive or conventional cavity principles. Samples were scanned again and volumetric data were assessed by Meshmixer 3.5 (Autodesk) 3D modeling software. Statistical evaluations were performed with Mann Whitney U test and Spearman’s Correlation test. The significance level was α=0.05. Results: Although there was a significant difference between obtained initial volume readings of two scanners for 3M and 3C groups (p &lt; 0.05), no significant difference was observed among other groups (p ≥ 0.05). Regarding the comparison of final volume readings of two scanners, a significant difference was found for 5M group (p = 0.036), whereas no significant difference was observed for other groups (p ≥ 0.05). Percentage of volume loss between two scanners was statistically similar (p ≥ 0.05). Conclusion: Data obtained with Cerec Omnicam and iTero Element Flex were compatible with volumetric assessments. Both intraoral scanners may be considered effective for calculating caries-related cavity volumes. Minimally invasive cavity principles may provide less volume loss compared to conventional cavity principles.

Evaluation of The Accuracy of Two Apex Locators For Determining The Working Length of Endodontically Retreated Curved Mesial Roots of Maxillary Molar Teeth : An Ex Vivo Study

Objective: To evaluate the accuracy of PROPEX PİXİ (Dentsply Sirona, Ballaigues, Switzerland) and Apex ID (Sybron Endo, Orange, CA, USA) in determining the working lengths of curved mesial roots of upper molars during the retreatment procedure. Method: Twenty curved mesial roots of upper molar teeth were selected. Canals were shaped with ProTaper Next instruments (Dentsply Sirona) up to X3. The canal lengths were determined with a microscope (Carl Zeiss GmbH, Oberkochen, Germany) at 2,5X magnification (DM) and then also detected electronically (EM1P and EM1A) with PROPEX PİXİ (Dentsply Sirona) and Apex ID (Sybron Endo) in an alginate model. Specimens were then obturated using a size X3 master gutta-percha cone and an epoxy resin-based root canal sealer. Seven days later, the coronal part of the filling was removed with a Gates Glidden drill size 3 and for the middle part Protaper Universal Retreatment File D2 used. Working lengths electronically were detected again by two different apex locaters (EM2P and EM2A). Data were analysed by using the Wilcoxon Signed Rank and Mann Whitney u test. The analyses were carried out with MedCalc Statistical Software. Results: No significant difference was found between direct measurements (DM) and electronic measurements before and during retreatment for PROPEX PİXİ (P=0.135) and Apex ID (P=0.232). Also there was no significant difference between two apex locaters before (P=0.108) and during retreatment (P=0.242) Conclusion: PROPEX PİXİ and Apex ID were considered accurate for the root canal length determination during retreatment procedure. Keywords: Apex locator, curved molar, retreatment, working lenght

Scanning Electron Microscopic Analysis of Deformation of TruNatomy File Systems: An Ex-vivo Study.

Aim The aim of the study was to assess the instrument deformation following the usage of the TruNatomy(Dentsply Sirona, USA) file system in extracted premolars using Scanning Electron Microscopy (SEM). Materials and Methods For the present study, 84 extracted mandibular bicuspids were selected. The teeth were divided into two groups: Group 1, TruNatomy(n=42), and Group 2, Hero Shaper(Micro Mega, France) (n=42).The samples were shaped with 0.03 taper to size 36 with TruNatomy instruments and 0.04 taper to size 30 with Hero Shaper instruments. 5 ml of 5.25% Sodium Hypochlorite (NaOCl) and 2 ml of 17% ethylenediaminetetraacetic acid (EDTA) were used for the final irrigation of root canals. The master apical file was used to instrument seven teeth samples for assessing the safety of the instruments after multiple uses and autoclaving. So, a total of six files per group was used for the analysis of any distortions, cracks or micro-fractures after instrumentation of 42 teeth, at the tip (D0) and 5 mm from the tip (D5) of the rotary file under SEM at 500x magnification. Statistical analysis To determine the significance between the groups, the Mann-Whitney U-testwas applied. Results The mean surface wear of the instruments, at the tip (D0) in Group 1 was 1.2857 and in Group 2 was 1.4762. The mean spiral distortion of the instruments, at the tip (D0) in Group 1 was 1.1905 and in Group 2 was 1.4286. A statistically significant difference (P<0.05) was observed between the groups for surface wear and spiral distortion at the tip of the file (D0). There was no significant difference between groups for surface wear and spiral distortion values of the instruments at 5 mm from the tip (D5) (P>0.05). Conclusion The instrument distortion of the rotary file systems analysed was minimal following the biomechanical preparation of seven mandibular bicuspids without root curvature, using a single file. Therefore, both rotary file systems can be considered safe.

Behaviour of the Peri-Implant Soft Tissue with Different Rehabilitation Materials on Implants.

(1) Background: Mucointegration seems to gain interest when talking about success in the maintenance of dental implants. As we well know, collagen fibres cannot be inserted due to the lack of root structure on the implant surface, so the structural integration of peri-implant tissues that provide a firm seal around implants seems to be of interest when it comes to ensuring the survival of dental implants. To achieve a good epithelial barrier, the physicochemical characteristics of the surfaces of the restorative materials are of vital importance; therefore, the objective of this study is to analyse the histological behaviour of the peri-implant soft tissues in three different restorative materials. (2) Methods: Histological analysis of biopsied peri-implant keratinised mucosa, inflammatory epithelium and connective tissue in contact with a reinforced composite (BRILLIANT Crios), a cross-linked polymethylmethacrylate (TELIO CAD), and a hybrid ceramic (Vita Enamic), restored on a customised Atlantis-type abutment (Dentsply Sirona) between 60 and 180 days after restoration. (3) Results: A greater number of cells per mm2 of keratinised epithelium is observed in the reinforced composite, which could indicate greater surface roughness with greater inflammatory response. In this way, the greater number of lymphocytes and the lateral cellular composition of the inflammatory cells confirm the greater inflammatory activity towards that material. The best material to rehabilitate was hybrid ceramic, as it shows a better cellular response. (4) Conclusions: Knowing the limitations of the proposed study, despite the fact that greater inflammation is observed in the reinforced composite relative to the other materials studied, no statistically significant differences were found.