Biomechanical behavior of implant retained prostheses in the posterior maxilla using different materials: a finite element study.

BACKGROUND: The aim of this study is to evaluate the biomechanical behavior of the mesial and distal off-axial extensions of implant-retained prostheses in the posterior maxilla with different prosthetic materials using finite element analysis (FEA). METHODS: Three dimensional (3D) finite element models with three implant configurations and prosthetic designs (fixed-fixed, mesial cantilever, and distal cantilever) were designed and modelled depending upon cone beam computed tomography (CBCT) images of an intact maxilla of an anonymous patient. Implant prostheses with two materials; Monolithic zirconia (Zr) and polyetherketoneketone (PEKK) were also modeled .The 3D modeling software Mimics Innovation Suite (Mimics 14.0 / 3-matic 7.01; Materialise, Leuven, Belgium) was used. All the models were imported into the FE package Marc/Mentat (ver. 2015; MSC Software, Los Angeles, Calif). Then, individual models were subjected to separate axial loads of 300 N. Von mises stress values were computed for the prostheses, implants, and bone under axial loading. RESULTS: The highest von Mises stresses in implant (111.6 MPa) and bone (100.0 MPa) were recorded in distal cantilever model with PEKK material, while the lowest values in implant (48.9 MPa) and bone (19.6 MPa) were displayed in fixed fixed model with zirconia material. The distal cantilever model with zirconia material yielded the most elevated levels of von Mises stresses within the prosthesis (105 MPa), while the least stresses in prosthesis (35.4 MPa) were recorded in fixed fixed models with PEKK material. CONCLUSIONS: In the light of this study, the combination of fixed fixed implant prosthesis without cantilever using a rigid zirconia material exhibits better biomechanical behavior and stress distribution around bone and implants. As a prosthetic material, low elastic modulus PEKK transmitted more stress to implants and surrounding bone especially with distal cantilever.

Build angle effect on 3D-printed dental crowns marginal fit using digital light-processing and stereo-lithography technology: an in vitro study.

BACKGROUND: The effect of 3D printing technology and build angle on the marginal fit of printed crowns is unclear. The objective of this research was to use digital light processing (DLP) and stereo-lithography (SLA)-based 3D printing to construct single restorations with varied build angles and to analyze the crowns' marginal fit. METHODS: A prepared resin first molar was scanned utilizing an optical scanner. Three build orientations were used to construct the specimens: 0, 45, and 90º. DLP and SLA technology were used to produce the casting patterns. A digital microscope was used to measure the marginal gaps. The effect of build orientation was statistically analyzed by using Two-way ANOVA followed by pair-wise Tukey test. RESULTS: Two-way ANOVA revealed a significant effect of printer technology and build angle on the marginal discrepancy of 3D printed crowns (p < 0.001). One-way ANOVA revealed that SLA printers (55.6 [± 13.59]) showed significantly better mean [± SD] marginal discrepancy in µm than DLP printers (72 [± 13.67]) (p < 0.001). Regarding build angle, one-way ANOVA revealed significant differences between the different angles. Tukeys post-hoc test revealed that 0° (48.5 [± 9.04]) had the significantly smallest marginal discrepancy followed by 45° (62.5 [± 8.05]) then 90° (80.5 [± 8.99]) (p < 0.001). CONCLUSION: The build orientation affects the marginal discrepancy of single crowns manufactured utilizing DLP and SLA.

Effect of different span lengths with different total occlusal convergences on the accuracy of intraoral scanners.

PURPOSE: The aim was to assess the effect of span lengths and total occlusal convergence (TOC) on the accuracy of intraoral scanners . MATERIALS AND METHODS: Two typodont acrylic teeth models were prepared to receive fixed dental prostheses with three different span lengths. Span 1: between maxillary canines; span 2: between maxillary second premolars; and span 3: between maxillary second molars. In the first model, prepared teeth had a TOC of 12°, whereas, in the second model, teeth had a TOC of 20°. Each model was scanned 10 times using 4 different intraoral scanners (Omnicam, Primescan, Trios 4, and Medit i500). The STL files from the scans were compared to the reference models (trueness) and within each test group (precision) using a 3D comparison software. Data were then statistically analyzed. RESULTS: Regarding trueness, no significant differences were found among Primescan (32.58 ± 13.08), Trios 4 (32.33 ± 12.19), and Medit i500 (32.26 ± 9.57). However, all showed significantly better trueness than Omnicam (35.70 ± 8.35) (p < 0.001). The highest values were found in scans between the second molars (47.42 ± 3.94), followed by scans between second premolars (28.42 ± 3.78), and the highest trueness was found in scans between the canines (23.80 ± 3.85). For TOC, 12° had a significantly higher value than 20° (p < 0.001). Regarding precision, the highest values were found with Omnicam (29.84 ± 3.89), followed by Medit i500 (28.04 ± 2.94), then Trios 4 (25.64 ± 3.11), and Primescan (24.69 ± 5.25). The highest values and least precision were found in scans between the second molars (28.97 ± 5.27) and scans between second premolars (27.59 ± 3.97), whereas the highest precision was found in scans between the canines (24.60 ± 2.04). For TOC, 12° had significantly higher values than 20° (p < 0.001). CONCLUSIONS: Intraoral scans are directly affected by scanner type, TOC, and scan spans. All tested scanners showed clinically acceptable results even for long-span restorations.

Effect of cervical margin relocation on marginal adaptation and microleakage of indirect ceramic restorations.

PURPOSE: This study evaluated the effect of cervical margin relocation (CMR) with two different materials and contamination with hemostatic agents on the margin adaptation and microleakage of ceramic restorations. MATERIALS AND METHODS: Mesial-occlusal-distal cavities were prepared in 60 human first molars and distributed to 3 groups (n = 20) according to the margin relocation procedure. The groups were: group F; flowable composite applied in two 2 mm increments, group B; bulk-fill flowable composite applied as a bulk increment of 4 mm thickness and group C (control); no CMR was done. Each group was subdivided into two subgroups (subgroup N; no hemostatic agent applied and subgroup H; hemostatic agent was applied). In all groups, ceramic inlays were prepared and cemented. The samples were subjected to thermocycling (10,000 cycles). The adaptation of the cervical margin was evaluated with scanning electron microscopy (200×). Samples were then assessed for microleakage analysis with the dye penetration method. Marginal adaptation data were normally distributed and analyzed using two-way ANOVA followed by Tukey's post hoc test. Ordinal microleakage score data were analyzed using cumulative link models followed by the analysis of deviance using Wald chi-square tests. RESULTS: Both CMR and contamination with a hemostatic agent had significant effects on the margin adaptation of the cervical margin. Group C showed the highest adaptation with no significant difference from group F. The lowest adaptation was revealed in group B with a significant difference from group C. Subgroup N (in all groups) showed a statistically higher adaptation than subgroup H. Regarding microleakage assessment, CMR had no significant effect but hemostatic agent application showed a significantly higher microleakage score for all groups. CONCLUSIONS: Both the CMR procedure and contamination with AlCl3 hemostatic agent had a negative effect on marginal adaptation. For microleakage assessment, only contamination with hemostatic agent negatively affected the microleakage with no effect on the margin relocation procedure.

Effect of different preparation designs of minimally invasive occlusal onlays on the accuracy of different intraoral scanners: An in vitro study.

PURPOSE: The aim of this in vitro study was to assess and compare three different preparation designs of minimally invasive occlusal onlays on the trueness and precision of three different intraoral scanners under two different scanning conditions. MATERIALS AND METHODS: Three maxillary premolars were prepared in three different designs and divided accordingly into three groups, Group 1: Anatomical (n = 60), Group 2: Flat (n = 60), and Group 3: Ferrule (n = 60). The samples were then further divided into subgroups according to scanners as subgroup A: Medit i500 (n = 20), subgroup B: 3Shape TRIOS 4 (n = 20), and subgroup C: Cerec Primescan (n = 20). Last, the samples were further divided according to scanning conditions: Division i: As prepared (n = 10) and Division ii: Sprayed - scan spray (n = 10). An industrial 3D scanner was used to obtain the reference STL files. Accuracy was assessed in terms of trueness and precision and recorded in terms of root mean square in micrometers. Numerical data were explored for normality using Shapiro-Wilk test and were analyzed using 3-way ANOVA followed by Tukey's post hoc test. RESULTS: Regarding trueness, 3-way ANOVA showed that all tested variables had a significant effect on trueness. Significant interactions were found between the different variables (p < 0.001). For preparation design the highest value was found in ferrule preparation (27.88 ± 7.11), followed by flat preparation (22.99 ± 7.56), while the lowest value was found in anatomical preparation (18.83 ± 5.71) (p < 0.001). For scanner type, the highest value was found in Primescan (25.36 ± 10.66), followed by TRIOS 4 (22.75 ± 5.98), while the lowest value was found in Medit i500 (21.59 ± 5.03) (p < 0.001). As for the scanning condition, sprayed samples (26.54 ± 8.24) had a significantly higher value than non-sprayed samples (19.93 ± 5.53) (p < 0.001). Regarding precision, both preparation design and scanner type had a significant effect on precision. Scanning conditions had no significant effect. There was a significant interaction between the three tested variables (p = 0.012). CONCLUSIONS: Anatomical preparation of minimally invasive occlusal onlays produced the most accurate scans. Within the tested preparation designs, Medit i500 and 3Shape TRIOS 4 have better trueness than Cerec Primescan. Cerec Primescan is more precise than 3Shape TRIOS 4 and Medit i500 Scan spray application causes a higher deviation in the trueness of the tested intraoral scanners while it does not affect their precision.

Effect of different intraoral scanners and scanbody splinting on accuracy of scanning implant-supported full arch fixed prosthesis.

OBJECTIVE: This study evaluated the accuracy of different intraoral scanners (IOS) for scanning of implant-supported full arch fixed prosthesis with different implant angulations with and without scanbodies splinting. MATERIALS AND METHODS: Two maxillary models were designed and fabricated to receive an all-on-four implant retained. The models were divided into two groups according to the angulation of the posterior implant (Group 1; 30 and Group 2; 45). Each group was then divided into three subgroups according to the type of IOS used: Subgroup C; Primescan, subgroup T; Trios4, and subgroup M; Medit i600. Then each subgroup was divided into two divisions according to scanning technique; division S: splinted and division N: nonsplinted. Ten scans were made by each scanner for every division. Trueness and precision were analyzed using Geomagic controlX analysis software. RESULTS: Angulation had no significant effect on both the trueness (p = 0.854) and precision (p = 0.347). Splinting had a significant effect on trueness and precision (p < 0.001). Scanner type had a significant effect on trueness (p < 0.001) and precision (p < 0.001). There was no significant difference between trueness of Trios 4 (112.15 ± 12.85) and Primescan (106.75 ± 22.58). However, there was a significant difference when compared to trueness of Medit i600 (158.50 ± 27.65). For the precision results Cerec Primescan showed the highest precision (95.45 ± 33.21). There was a significant difference between the three scanners, precision of Trios4 (109.72 ± 19.24) and Medit i600 (121.21 ± 17.26). CONCLUSION: Cerec Primescan has higher trueness and precision than Trios 4 and Medit i600 in full arch implants scanning. Splinting the scanbodies improve the accuracy of full arch implants scanning. CLINICAL SIGNIFICANCE: Cerec Primescan and 3Shape Trios 4 can be used for scanning of All-on-four implant supported prosthesis when scanbodies are splinted using a modular chain device.

A modified form of the St Thomas' Hospital (STH) classification to improve cochlear implantation outcomes.

OBJECTIVES: re-evaluation and modification of the St Thomas' Hospital (STH) classification to improve cochlear implantation outcomes. STUDY DEIGN: a prospective cohort study. PATIENTS: children (n = 20) between 2 to 8 years old who received a unilateral cochlear implant, all had difficult round window visibility and/or accessibility for electrode insertion. 10 had a round window insertion through the endoscopic assisted cochlear implantation and the remaining 10 had the same insertion using the retro-facial approach. THE SURGERY: two alternative techniques were used to overcome the difficult cases of round window electrode insertion: 1Endoscopic assisted cochlear implantation 2Transmastoid retro-facial approach RESULTS: both techniques proved to be effective and practical to overcome cases with difficult round window visibility and/or accessibility for electrode insertion. CONCLUSION: Round window insertion is associated with superior cochlear implantation outcomes, so we recommend a new modification to the STH classification to bypass the cochleostomy insertion.

Mechanical behavior of different machinable ceramic crowns using vertical and horizontal preparations: an in-vitro study / Comportamento mecânico de diferentes coroas cerâmicas usináveis usando preparos verticais e horizontais: um estudo in vitro

Objective: the aim of this study was to compare the mechanical behavior of different ceramics when used in thin vertical preparations versus traditional horizontal preparation. Material and Methods: two stainless-steel dies were milled to simulate a minimally invasive vertical preparation (VP) and a traditional horizontal preparation (HP) for an all-ceramic crown of a maxillary first premolar. The stainless-steel dies were duplicated using epoxy resin. Eighty monolithic crowns were milled and divided into 2 groups according to preparation design. Each design group was subdivided into 4 sub-groups according to material (n=10): IPS e.max CAD (lithium disilicate), Bruxzir shaded zirconia (full contour zirconia), CeraSmart (resin nanoceramic) and CEREC Tessera (advanced lithium disilicate). The crowns were cemented on their relevant epoxy resin dies using self-adhesive resin cement. All specimens were subjected to 15,000 thermocycles and then loaded to fracture in a universal testing machine. Data were analyzed using two-way ANOVA and Tukey pair wise comparison test. Results: the fracture resistance mean values of the VP (1344 + 118 N) was significantly lower than the HP design (1646 + 191 N). Ceramic crowns made of full contour zirconia had higher fracture resistance mean values (2842 + 380 N) than advanced lithium disilicate (1272 + 125 N) followed by lithium disilicate crowns (983 + 52 N) and resin nanoceramic (882 + 61 N). Conclusion: both vertical and horizontal preparations, regardless the different ceramic materials, showed clinically acceptable fracture resistance values. (AU)

Objetivo: o objetivo deste estudo foi comparar o comportamento mecânico de diferentes cerâmicas quando utilizadas em preparos verticais finos ou preparos horizontais tradicionais. Material e Métodos: dois modelos de aço inoxidável foram fresados para simular um preparo vertical minimamente invasivo (PV) e um preparo horizontal tradicional (PH) para uma coroa totalmente em cerâmica de um primeiro pré-molar superior. As matrizes de aço inoxidável foram duplicadas usando resina epóxi. Oitenta coroas monolíticas foram fresadas e divididas em 2 grupos de acordo com o desenho do preparo. Cada grupo foi subdividido em 4 subgrupos de acordo com o material (n=10): IPS e.max CAD (dissilicato de lítio), zircônia Bruxzir (zircônia de contorno total), CeraSmart (resina nanocerâmica) e CEREC Tessera (dissilicato de lítio avançado). As coroas foram cimentadas em suas respectivas matrizes de resina epóxi usando cimento resinoso autoadesivo. Todos os espécimes foram submetidos a 15.000 ciclos térmicos e então carregados até a fratura em uma máquina de teste universal. Os dados foram analisados usando ANOVA com dois fatores e teste de comparação por pares de Tukey. Resultados: os valores médios de resistência à fratura do PV (1344 + 118 N) foram significativamente menores do que PH (1646 + 191 N). As coroas de cerâmica feitas de zircônia de contorno total apresentaram maiores valores médios de resistência à fratura (2842 + 380 N) do que dissilicato de lítio avançado (1272 + 125 N), seguido por coroas de dissilicato de lítio (983 + 52 N) e resina nanocerâmica (882 + 61 N). Conclusão: preparos verticais e horizontais, independentemente dos diferentes materiais cerâmicos, apresentaram valores de resistência à fratura clinicamente aceitáveis. (AU)

Accuracy of different laboratory scanners for scanning of implant-supported full arch fixed prosthesis.

OBJECTIVE: This study evaluated the accuracy of different laboratory scanners (LS) for scanning of implant-supported full arch fixed prosthesis with different implant angulations. MATERIALS AND METHODS: Two maxillary models that are designed to receive an all-on-four implant retained prosthesis were fabricated then scanned using five different LS. The models were divided into two groups according to the angulation of the posterior implant (Group 1; 30° and group 2; 45°). Each group was then subdivided into five subgroups according to the type of LS, subgroup T; Medit T710, subgroup I; IneosX5, subgroup E; 3ShapeE4, subgroup A; Autoscan DS-Mix, and subgroup M; Ceramill Map600. An industrial 3D scanner was used as reference scanner, then each model was scanned with 5 LS 10 times. Trueness and precision were analyzed using Geomagic 3D analysis software. RESULTS: Both scanner type and implant angle had a significant effect on the trueness (p < 0.001). Significant interaction was found between the scanner type and implant angle (p < 0.001). For scanner type tukeys post hoc test revealed highest trueness with the 3Shape E4 (21.3 ± 2.1) and the medit T710 (22.6 ± 2.1) and least trueness with the shining 3D autoscan ds-mix (33.8 ± 3.0). Significantly better trueness was observed with the 30° than the 45° angle. Regarding precision, two-way ANOVA revealed significant effect of the scanner type only (p < 0.001). There were no significant differences between the 3Shape E4, medit T710, Ineos X5, and the Ceramill map600. However, all showed significantly higher precision values when compared to shining 3D autoscan ds-mix. CONCLUSIONS: All tested scanners showed results within the clinically acceptable range with 3ShapeE4 and Medit T710 showing the highest accuracy. CLINICAL SIGNIFICANCE: Tested scanners can be used for scanning of All-on-four implant supported prosthesis.

Accuracy and repeatability of different intraoral instruments on shade determination compared to visual shade selection.

OBJECTIVE: To evaluate the accuracy and repeatability of intraoral instruments used for shade determination compared to visual shade selection (VSS). MATERIALS AND METHODS: A total of 20 subjects and 10 observers, balanced by gender, participated in the study. Observers performed VSS of the upper right central incisor from each subject. Instrumental shade determination of the same teeth was performed using a spectrophotometer (Easyshade V) and intraoral scanners (CEREC Omnicam, Primescan, Trios 3 and Trios 4). Vita Classical shade nomenclature was used to record the shade designation for all instruments and VSS. The accuracy of the instruments was determined by comparing the instrument readings with the most frequent visual shade selected. The percentage of accuracy was obtained by comparing the number of agreements with the number of comparisons. The percentage of repeatability was obtained by comparing the number of repeated shades with the number of shade measurements in each group. Accuracy was compared using Cochran Q test followed by pairwise comparisons using multiple McNemar's tests with Bonferroni correction. Repeatability of the instruments was evaluated using Cronbach's alpha. RESULTS: Omnicam showed a significant lower accuracy than the other instruments (p < 0.05). No statistical difference on repeatability was found among the different instruments (p > 0.05). It was not found any statistical differences for VSS accuracy among the observers (p = 0.437) and between genders (p = 0.867). CONCLUSION: Instrumental repeatability (≥75%) and similar accuracy between the best performed instruments (69%-77.5%) and the observers performance (65%-90%) supports the use of high-performance instruments for dental shade determination. CLINICAL SIGNIFICANCE: Most instruments (Easyshade V, Primescan, Trios 3, and Trios 4) showed similar accuracy performance to observers in the VSS.

Effect of Different Preparation Depths for an Inlay-Retained Fixed Partial Denture on the Accuracy of Different Intraoral Scanners: An In Vitro Study.

PURPOSE: The aim was to evaluate the effect of different preparation depths for inlay-retained fixed partial dentures on the accuracy of intraoral scanners. MATERIALS AND METHODS: Tooth preparations for two inlay-retained fixed partial dentures were done and divided according to depth of the preparation. Group A: 2 mm pulpal floor depth, 3 mm gingival floor depth and Group B: 3 mm pulpal floor depth, 4mm gingival floor depth. The CEREC Omnicam 4.4.4, Omnicam 4.6.2. Trios3 and Medit i500 intraoral scanners were used in this study. Tooth preparations were scanned by each scanner 10 times. The STL files obtained from the intraoral scanners were compared to the reference models (trueness) and within each test group (precision) using a 3D comparison software. Data were then statistically analyzed. RESULTS: Regarding trueness, two-way ANOVA revealed significant differences between the different types of scanners (p < 0.001) (Omnicam 4.4.4: 65.09 ± 2.87 Omnicam 4.6.1: 52.73 ± 3.31 Medit i500: 58.45 ± 2.63 Trios 3: 41.79 ± 4.42). Preparation depth had no significant influence on the trueness (p = 0.083). For precision two-way ANOVA revealed significant differences between the different types of scanners (p < 0.001). Preparation depth had no significant influence on the precision (p = 0.111). Statistically significant interactions were found between the different variables. CONCLUSIONS: The depth of preparation did not have an influence on the accuracy of different scanners. However, the type of scanner influenced the accuracy of digital impressions with Trios3 showing the highest accuracy.

Effect of photo-polymerization mode on the degree of conversion of resin cement under different ceramic materials.

BACKGROUND: This study evaluated the effect of different polymerization modes and duration on the degree of conversion (DC) of resin cement under different types of ceramics. METHODS: Ceramic materials were divided into 3 groups (N.=60): group 1, Cerasmart; group 2, Vita Enamic; and group 3, Vita Mark II. Each group was then divided into three subgroups (N.=20) according to the polymerization mode (A: low-intensity; B: high-intensity; and C: soft-start). Subgroups were then divided into two further groups according to the polymerization time (I: 10 s; and II: 20 s). DC of light-cured resin cement beneath different kinds of ceramics was tested using FTIR spectroscopy. Results were compared to a control group cured without overlying ceramic. RESULTS: While the type of ceramic and mode of polymerization showed a significant effect on the DC of resin cement, polymerization duration did not. Vita Mark II group showed the highest DC of resin cement followed by Vita Enamic and Cerasmart. High- and low-intensity polymerization modes did not show significant difference, but both showed significantly lower DC when compared to soft start mode. CONCLUSIONS: Type of ceramic and polymerization mode showed a direct effect on the DC of resin cement.

Accuracy and repeatability of different intraoral scanners on shade determination.

OBJECTIVE: To evaluate the accuracy and repeatability of different intraoral scanners on shade determination. MATERIALS AND METHODS: Ten different shades of Vita Mark II blocks were used. A disc-shape specimen (10 mm in diameter and 1 mm thick) per ceramic block was fabricated. Ten color measurements per specimen were performed by each instrument (Vita Easyshade V [control], 3shape Trios, Cerec Omnicam, Cerec Primescan) and recorded in Vita Classic color system. The number of correct shade match per instrument for each shade was recorded. Instrumental accuracy was compared using Cochran Q test and repeatability was analyzed using Cronbach's alpha. RESULTS: There was a significant difference in the instrumental accuracy for shade determination (p < 0.001). There was no statistical difference between the Easyshade V (78%) and the 3Shape Trios (66%) (p > 0.05), with the latter being similar to the other scanners Primescan(63%) and Omnicam (57%) (p > 0.05). No significant difference was found (p > 0.05) when different shades were evaluated by the same instrument. Similar repeatability was found for the different devices, ranging from 44.3% for Easyshade to 51.9% for Omnicam. CONCLUSION: The evaluated instruments showed less than expected repeatability and accuracy on measuring different dental shades. Therefore, caution should be exercised when using instrumental shade determination, which should be accompanied by experienced human visual assessment. CLINICAL SIGNIFICANCE: The outcome of this study might help clinicians evaluate the performance of intraoral scanners as a shade matching tool.

Growing skull fractures of the orbital roof: a multicentric experience with 28 patients.

BACKGROUND: Growing skull fracture (GSF) is a rare condition that may complicate pediatric head trauma. Patients may present with delayed-onset neurological manifestations. AIM: This study aims to highlight the different presentations, methods of evaluation, treatment modalities, and outcomes in patients with orbital roof GSF. METHODS: This retrospective multicentric cohort study reviewed the hospital records of children with GSF who presented at the Craniomaxillofacial Plastic Surgery Department, and Neurosurgery Department with Otorhinolaryngology Department (Maxillofacial unit), from 2011 to 2020. The collected data included age, gender, delay, manifestations, findings of imaging techniques, surgical treatment, complications, and satisfaction of patients' parents. RESULTS: Twenty-eight patients with orbital roof GSF were included in this study. Most of the patients (82.1%) were boys, and the mean (SD) age was 5 (2) years old. Head trauma was caused by falls in all cases. Clinical manifestations included eyelid swelling (75%), pulsatile proptosis (25%), headache (17.9%), and seizures (10.7%). The mean (SD) diameter of bony defects was 24.3 (8.7) mm. Duraplasty alone was performed in 57.1%, while dura-cranioplasty was done in 42.9% of patients. Dural reconstruction was done using pericranial graft in 82.1% and artificial grafts in 17.9% of patients. Most of the parents (95%) were absolutely satisfied. No mortalities or recurrence of symptoms were recorded. The median follow-up period after surgery was 3.9 years. CONCLUSION: Orbital roof GSF should be considered among the differential diagnoses in pediatric patients with history of head trauma presenting with ocular and/or neurological manifestations. Duraplasty is mandatory in all cases, whereas cranioplasty is required mainly in cases with large bony defects more than 25 mm. Prognosis in most patients was good both subjectively and objectively.

Influence of Preparation Type and Tooth Geometry on the Accuracy of Different Intraoral Scanners.

PURPOSE: To evaluate the influence of preparation design and tooth geometry on the accuracy of scans obtained from three different intraoral scanners (IOS). MATERIALS AND METHODS: Full coverage crown and inlay preparations with known axial wall tapers (6ᵒ and 12ᵒ) were performed on typodont teeth using a computer numerical control machine. Reference models were scanned with a highly accurate reference scanner (Ineos X5) and saved in standard tessellation language (STL) format then each IOS (Omnicam, Trios, and i500) scanned each model 10 times. The STL files obtained from the intraoral scanners were compared to the reference models (trueness) and within each test group (precision). Data were statistically analyzed using three- way ANOVA and one- way ANOVA. RESULTS: When comparing trueness values extracoronal preparations (32.30 ± 11.23 µm) was significantly better than intra-coronal preparation (59.61 ± 16.42 µm). As for opposing wall taper, one-way ANOVA revealed that the more the convergence or divergence between opposing walls the better is the trueness. Significant differences were observed between the scanners. 3 Shape Trios (35.70 ± 14.12 µm) and medit i500 (44.31 ± 11.41 µm) showed no statistically significant differences. However, both showed significantly better precision results when compared to Omnicam (57.83 ± 22.14 µm). CONCLUSION: Extracoronal preparations show better trueness and precision in comparison to intracoronal preparations. Trios and i500 have better trueness and precision than Omnicam. Increasing the taper of the axial wall has a direct effect on trueness of scans obtained from the IOS.

Oral Health Attitudes among Preclinical and Clinical Dental Students: A Pilot Study and Self-Assessment in an Egyptian State-Funded University.

Dentists should present to patients as good role models in their oral health behaviour. Previous studies have demonstrated how education can improve dental students' oral health. This pilot investigation aimed to compare and evaluate the features of the oral health behaviour and attitudes of preclinical and clinical dental students at Ain Shams University, a public Egyptian university. The Hiroshima University-Dental Behaviour Inventory (HU-DBI) survey was provided to 149 (78 female/71 male) dental students. Dichotomised (agree/disagree) answers to 20 HU-DBI items were possible, with a maximum conceivable score of 19. An estimation of oral health behaviour and attitudes was calculated by the sum of correct oral health answers to every item by the study groups and evaluated statistically. The score of oral health-favouring answers was higher in clinical (11.50) than preclinical students (10.63) and was statistically significant (p < 0.05). Single-item evaluations showed no statistical significance, except in one survey item. This survey exhibited weak differences in the improvement of oral hygiene behaviour and attitudes between participating preclinical and clinical students, as well as overall poor oral health behaviour in both groups. This inadequacy of Egyptian public dental education in terms of sufficient student oral health progress emphasises the necessity for supplementary courses and curricular reviews that accentuate the need for future dentists to display the correct oral health behaviour.

Effect of decontamination methods on shear bond strength of resin cement to translucent monolithic zirconia / Efeito de métodos de descontaminação na resistência ao cisalhamento entre cimento resinoso e zircônia monolítica translúcida

Objective: The aim of this study was to evaluate the effect of decontamination methods on shear bond strength of resin cement to translucent monolithic zirconia. Material and Methods: Eighty 4-mol yttria-stabilized tetragonal zirconia polycrystal specimens were fabricated. All specimens were subjected to saliva contamination and divided into four groups (n = 20) according to the decontamination methods: 70% isopropanol (AL); zirclean (ZC); 5.25% sodium hypochlorite (NaOCL); and no cleaning (NC). All specimens were bonded by using self-adhesive resin cement. Half of the specimens in each group (n = 10) were subjected to aging. All specimens were subjected to shear bond strength test in a universal testing machine. Failure modes were evaluated by using a scanning electron microscope (SEM). The data obtained were statistically analyzed by using one-way ANOVA followed by the HSD Tukey test (p < 0.05). Results: ANOVA test revealed a significant difference among the different decontamination methods (p < 0.05). No significant differences were found among NaOCL, ZC, and AL groups as revealed by the HSD Tukey test (p > 0.05). The effect of aging was significantly different in all groups (p < 0.05); whereas, no significant difference was found in group ZC (p > 0.05). The (SEM) analysis showed mixed failures in all groups, except in group NC where only adhesive failure was observed. Conclusion: Saliva contamination during clinical evaluation significantly decreases the shear bond strength between self-adhesive resin cement and translucent monolithic zirconia. The cleaning methods have an impact on improving the bond strength between resin cement and translucent monolithic zirconia (AU)

Objetivo: O objetivo deste estudo foi avaliar o efeito dos métodos de descontaminação na resistência ao cisalhamento entre cimento resinoso e zircônia monolítica translúcida. Material e métodos: Foram fabricados oitenta espécimes policristalinos de zircônia tetragonal estabilizada com ítria a 4 mol. Todas as amostras foram submetidas à contaminação salivar e divididas em quatro grupos (n = 20) de acordo com os métodos de descontaminação: isopropanol a 70% (AL); zircleano (ZC); Hipoclorito de sódio a 5,25% (NaOCL); e sem limpeza (NC). Todas as amostras foram cimentadas utilizando um cimento resinoso autoadesivo. Metade das amostras de cada grupo(n = 10) foram submetidas ao envelhecimento. Todas as amostras foram submetidas ao teste de resistência ao cisalhamento em uma máquina de teste universal. Os módulos de falha foram avaliados usando um microscópio eletrônico de varredura (MEV). Os dados obtidos foram analisados estatisticamente utilizando ANOVA de uma via, seguida pelo teste de HSD Tukey (p < 0,05). Resultados: O teste ANOVA revelou diferença significativa entre os diferentes métodos de descontaminação (p < 0,05). Não foram encontradas diferenças significativas entre os grupos NaOCl, ZC e AL, conforme revelado pelo teste HSD Tukey (p> 0,05). O efeito do envelhecimento foi significativamente diferente em todos os grupos (p < 0,05); enquanto nenhuma diferença significativa foi encontrada no grupo ZC (p > 0,05). A análise (SEM) mostrou falhas mistas em todos os grupos, exceto no grupo NC, onde apenas foi observada falha adesiva. Conclusão: A contaminação por saliva durante a avaliação clínica diminui significativamente a resistência ao cisalhamento entre o cimento resinoso autoadesivo e a zircônia monolítica translúcida. Os métodos de limpeza têm um impacto na melhoria da resistência da união entre o cimento resinoso e a zircônia monolítica translúcida. (AU)

Fracture load of nano-ceramic composite material for anterior endocrown restorations / Carga de fratura de material compósito nano-cerâmico para restaurações endocrown anteriores

Objective: to evaluate ability of Nano Ceramic Composite endocrown to withstand occlusal forces when used in the anterior region. Material and Methods: eighty endodontically treated maxillary central incisors teeth were randomly divided into two main groups according to the restoration type. Forty of these teeth were post, core and crown restorations and 40 were endocrown restorations. Then they were divided by halves into two subgroups according to the material used 20 were made with Lava Ultimate and the other 20 with IPS e.max. Each subgroup was then further subdivided into two divisions according to the remaining tooth structure above the CEJ (n = 10): 2 mm and 0.5 mm above the CEJ. After teeth preparation, the restorations were all made by CAD/CAM system (Cerec MCXL). All samples had undergone cyclic fatigue testing, and then loaded to fracture using a universal testing machine. The specimens were measured and statistically analyzed using Mann-Whitney test for comparing the mean changes between the groups. Results: Lava Ultimate showed higher mean fracture load values than IPS e.max specimens. Conclusions: endocrowns were found to be more favorable when used on endodontically treated teeth than the conventional post, core and crown restorations.(AU)

Objetivo: Avaliar a capacidade do compósito nanocerâmico endocrown para suportar forças oclusais quando usado na região anterior. Material e Métodos: Oitenta incisivos centrais superiores tratados endodonticamente foram divididos aleatoriamente em dois grupos principais, de acordo com o tipo de restauração. Quarenta desses dentes receberam restaurações com retentor intrarradicular, núcleo e coroa e 40 receberam restaurações endocrown. Em seguida, foram divididos pela metade em dois subgrupos, de acordo com o material utilizado, sendo 20 confeccionados com Lava Ultimate e os demais 20 com IPS e.max. Cada subgrupo foi posteriormente subdividido em dois, de acordo com a estrutura dentária remanescente acima da JEC (n = 10): 2 mm e 0,5 mm acima do JEC. Após o preparo dos dentes, todas as restaurações foram realizadas pelo sistema CAD/ CAM (Cerec MCXL). Todas as amostras foram submetidas a testes de fadiga cíclica e submetidas ao esforço até a fratura em uma máquina universal de testes. As amostras foram medidas e analisadas estatisticamente pelo teste de MannWhitney para comparação das alterações médias entre os grupos. Resultados: lava Ultimate apresentaram valores médios mais altos de carga até a fratura do que as amostras IPS e.max. Conclusões: as endocrowns mostraram-se mais favoráveis quando utilizadas em dentes tratados endodonticamente do que as restaurações convencionais com retentor intrarradicular, núcleo e coroa.(AU)

Biaxial flexural strength of different types of monolithic zirconia / Resistência Flexural Biaxial de diferentes tipos de zircônia monolítica

Objective: This study was designed to evaluate the biaxial flexural strength (BFS) of different types of unshaded and shaded monolithic zirconia. Material and Methods: 120 monolithic zirconia ceramic discs were fabricated. They were divided into twelve groups (n=10), Group 1; Bruxzir unshaded, Group 2; Bruxzir shaded A2, Group 3; Bruxzir anterior white, Group 4; Bruxzir anterior shade A2, Group 5; Prettau unshaded, Group 6; Prettau shaded with A2 coloring liquid, Group 7; Prettau anterior white, Group 8; Prettau anterior shaded with A2 coloring liquid, Group 9; Katana HT white, Group 10; Katana HT shade A2, Group 11; Katana ST white, Group 12; Katana ST shade A2. All discs were milled using a dental milling machine, and had final dimensions after sintering of 15 mm diameter and 1 mm thickness. BFS was tested using piston on three ball technique. Results: One-way ANOVA revealed significant differences among the 12 groups. Tukey post-hoc tests revealed no significant differences between the groups 3, 4, ,7 ,8 11, and 12. However, they all had BFS values that are significantly lower than all other groups. Group 2 showed statistically significant higher BFS values when compared to group 3,4, 7, 8, 11, and 12 while it showed statistically significant lower values when compared to groups 1, 5, 6, 9, and 10. Conclusion: Increase in the yttria content in zirconia led to a decrease in its BFS. Shading of zirconia did not have a significant effect on the final strength of zirconia. (AU)

Objetivo: Este estudo foi desenhado para avaliar a resistência à flexão biaxial (RFB) de diferentes tipos de zircônia monolítica maquiada e não-maquiadas. Material e Métodos: 120 discos cerâmicos de zircônia monolítica foram fabricados. Eles foram divididos em doze grupos (n = 10), Grupo 1; Bruxzir Não-maquiado, Grupo 2; Bruxzir maquiado A2, Grupo 3; Branco anterior de Bruxzir, Grupo 4; Maquiagem anterior de Bruxzir A2, Grupo 5; Prettau não maquiado, Grupo 6; Prettau maquiado com corante A2, Grupo 7; Prettau anterior branco, Grupo 8; Prettau anterior maquiado com corante A2, Grupo 9; Katana HT branco, Grupo 10; Katana HT maquiagem A2, Grupo 11; Katana ST White, Grupo 12; Katana ST maquiagem A2. Todos os discos foram fresados em uma fresadora dentária e tiveram suas dimensões finais após sinterização de 15 mm de diâmetro e 1 mm de espessura. A RFB foi testado usando pistão na técnica de três bolas. Resultados: One-way ANOVA revelou diferenças significativas entre os 12 grupos. Os testes post-hoc de Tukey não revelaram diferenças significativas entre os grupos 3, 4, 7, 8 11 e 12. No entanto, todos eles exibiram valores de RFB significativamente menores do que todos os outros grupos. O Grupo 2 apresentou valores estatisticamente significantes de ICS mais elevados quando comparado aos grupos 3,4, 7, 8, 11 e 12, enquanto apresentou valores estatisticamente significantes menores quando comparados aos grupos 1, 5, 6, 9 e 10. Conclusão: o aumento do conteúdo de ítria na zircônia levou a uma diminuição em sua RFB. A maquiagem da zircônia não teve um efeito significativo sobre a resistência final da zircônia. (AU)