Ahed Al-Wahadni

Background: Recently, the demand for esthetic restorations has grown dramatically and extended into the pediatric population. The prefabricated zirconia crowns (PZCs) and custom-made zirconia crowns (CZCs) are new esthetic options in pediatric dentistry. However, they are still inadequately tested for use in children. Aim: To determine the fracture resistance and failure mode of the PZC in comparison to the CZC. Materials and Methods: In this in-vitro study, thirty cobalt-chromium dies were fabricated by scanning the negative replica of a prefabricated lower first permanent molar zirconia crown. CZCs were designed and milled using two different zirconia brands: Ceramill Zolid-FX (FX) and the Highly-Translucent (HT) zirconia. Dies were randomly assigned to receive either a PZC or a CZC (n = 10 in each group). All crowns were cemented on their respective dies using glass ionomer cement. Following artificial aging, all specimens were loaded to failure. Fracture mode analysis was performed. One-way ANOVA and Bonferroni post-hoc test were used for multiple comparisons across the groups. The significant level was set at p ≤ 0.05. Results: HT zirconia had a significantly higher fracture load compared to other groups (p < 0.05). The mean fracture resistance values were: (3087 ± 385) N for HT zirconia, (2633 ± 300) N for PZCs, and (2483 ± 381) N for FX, with no statistically significant difference in fracture strengths between PZCs and FX. Conclusions: HT zirconia crowns showed the highest fracture resistance amongst all groups. The fracture loads of tested crowns exceeded the maximum posterior biteforce. When placed in permanent molars, PZC are expected to perform well under masticatory forces in children.

SUMMARY: Purpose: To compare the marginal and internal gap, surface roughness, fracture resistance and mode of failure of provisional crowns fabricated with 3D printing and CAD/CAM manufacturing techniques. Methods and Materials: A maxillary first premolar was prepared for an all-ceramic crown and reproduced in cobalt-chromium metal dies (n=30) following CAD/CAM technology. The die was digitally scanned and exocad software was used to design the missing crown, which was manufactured using a CAM milling machine and two types of 3D printing machines (SLA and DLP) to produce 10 provisional crowns per group. The crowns were cemented to their respective dies and stored in water (24 hours; 37°C) followed by 600 thermal cycles (5°C/55°C) and 100,000 mechanical cycles (at 50N). Marginal and internal gap measurements were carried out using a 3D superimposition technique. Surface roughness (Ra) was determined using a profilometer at 0.5 mm/ second cross-head speed. The crowns were loaded to fracture at 0.5 mm/minute cross-head speed. Fracture forces and mode of failure were recorded, and data were analyzed using one-way analysis of variance (ANOVA) and multiple comparisons post hoc tests (pppp<0.05) group. Mode of failure I: Minimal crown fracture or crack, was predominate among DLP and SLA crowns (60%), while the Mode II: Less than half of the crown lost, was predominant among CAD/CAM crowns (60%). Conclusions: Crowns manufactured following CAD/CAM technique have better marginal and internal fit, surface roughness than SLA and DLP crowns. The CAD/CAM and SLA crowns showed higher resistance to fracture than the DLP crowns.

Purpose: To compare the fracture resistance and failure modes of anterior cantilever resin‐bonded fixed partial dentures (RBFPDs) fabricated from high translucency zirconia with different intaglio surface treatments.Materials and methods: Sound‐extracted canines (N = 50) were randomly divided into five groups (n = 10) to be restored with high translucency zirconia RBFBDs of different intaglio surface treatments. The RBFPD was designed using exocad software and fabricated using a CAM milling machine. The RBFPDs were treated differently: abrasion with 50 µm alumina particles (Group 1); abrasion with 30 µm silica‐coated alumina particles (Group 2); abrasion with silica‐coated alumina particles (30 µm) and silane application (Group 3); abrasion with silica‐coated alumina particles (30 µm) and 10‐methacryloyloxydecyl dihydrogen phosphate (10‐MDP) primer application (Group 4); abrasion with silica‐coated alumina particles (30 µm) and silane, and 10‐MDP primer application. All RBFPDs were cemented using dual‐cured resin cement. The RBFPDs underwent 6000 thermal cycles with distilled water at 5/55°C for 2 min per cycle and then mechanical cyclic loading with 1200,000 cycles of 50 N at a 1.7 Hz frequency at an angle of 135° to the abutment's long axis. Then, RBFPDs were loaded to fracture using a universal testing machine at 1 mm/min. Maximum fracture forces and failure modes were recorded. Fractured specimens and uncemented specimens were examined using a scanning electron microscope. Data was analyzed using ANOVA and Games–Howell post hoc tests at p < 0.05.Results: Mean fracture load results showed a statistically significant difference between the research groups (p < 0.0001) and it ranged from 69.78 to 584 N. Group 4 exhibited the highest fracture load mean (p < 0.0001) which was significantly different from all other groups. Group 2 recorded a significantly higher fracture load mean than Group 3 (p = 0.029). Three modes of failure were observed: prosthesis debonding, prosthesis fracture, and abutment fracture.Conclusions: Abrasion of zirconia surface with 30 µm silica‐coated alumina particles and application of 10‐MDP primer yielded the highest mean fracture loads of monolithic high translucency zirconia RBFPD. The mode of fracture of the RBFPDs was influenced by the type of surface treatments.

Background: The development of procedures known as additive manufacturing, which aim to produce more complex items with a lower overall material consumption compared to processes known as subtractive manufacturing. In addition, in recent years there has been a significant rise in the quantity of dental materials that are produced via the use of these techniques. As a consequence of this, scientific research has been concentrating more and more on such technologies, particularly in order to shed light on the methodology, indicators, and boundaries of the emerging technology. Methods: The purpose of this paper is to provide a narrative assessment of the state-of-the-art in the area of these popular additive manufacturing methods, as well as the appropriate dental applications, by using scientific literature analysis and references to the authors’ clinical experience. In addition, the purpose of this study is to evaluate the appropriate dental applications. Results: The end result was a tremendous amount of data, most of it is conflicting, is now available for viewing. In tests conducted both in vitro and in vivo, the following additive manufacturing procedures were shown to be effective: Milling results in a number of negative side effects, including the loss of material, increased costs associated with equipment maintenance, and wasted production time. Additive manufacturing, often known as 3D printing, allows for the production of prostheses and models at a quicker rate and with less waste material. Conclusions: In order to successfully manufacture complex component geometries, CAM configuration and process design must be carefully considered. As a consequence of this, the speed at which the process is carried out is of equal importance to the interaction between the individual components. When dealing with geometry that is more complicated, 3D printing beats CAM.

Objectives: To evaluate and compare the maxillary sinus (MS) dimensions and volume in unilaterally displaced palatal and buccal maxillary canines. Methods: CBCT images for 133 patients were included in the study. Maxillary canines were unilaterally displaced palatally in 83 patients (PDCs) and buccally in 50 patients(BDCs). The following variables were measured: canine position in relation to MS walls, MS pneumatization and MS dimensions and volume. Results: MS was extended to the incisor region in 10% and 13% and to the canine region in 48% and 23% in BDCs and PDCs subjects, respectively. In BDC subjects, maxillary canine crown tip was more laterally (24.23 mm compared to 22.93 mm (p < 0.05)) and closer vertically (5.82 mm compared to 9.58 mm (p < 0.001)) to the MS, maxillary canine root tip was closer to the MS anterior (0 mm compared to 1.64 mm (p < 0.05)) and lateral (19.70 mm compared to 22.02 mm (p < 0.001)) walls and the MS volume (11.57mm³ compared to 9.09 mm³ (p < 0.001)) was increased in the displaced side compared to the non-displaced side. In PDC subjects, a significant difference between the displaced and non-displaced sides was detected in the vertical (3.28 mm compared to 5.89 mm (p < 0.001)) and lateral (21.63 mm compared to 24.25 mm (p < 0.001)) position of maxillary canine to the MS wall, the anterior (− 0.84 mm compared to 1.13 mm (p < 0.05)) and lateral (20.48 mm compared to 22.44 mm (p < 0.001)) position of canine root tip to the MS and the MS volume (7.71mm³ compared to 9.14mm³ (p < 0.001)). PDC sides differed from BDC sides in the lateral and vertical position of canine crown tip to MS and in MS volume. PDC showed negative association with MS volume and anteroposterior skeletal relationship and a positive association with MS height. Conclusions: PDCs subjects have a reduced MS volume and BDCs subjects have an increased MS volume. PDCs are associated with reduced MS volume, increased MS height and Class III skeletal relationship.

Blended learning is growing in popularity particularly following the emergence of COVID-19 pandemic. One of the fields that the pandemic has substantially affected is dental education. Purpose: The aim of this study was to evaluate the quality and effectiveness of the online dental education. Students’ perceptions and experiences of blended learning were also investigated. Methods: A 28-question online survey was designed to gauge students’ perceptions of the effect of blended learning on their academic performance. Results: 314 participants in preclinical and clinical years completed the questionnaire (223 females and 91 males). The majority of students (89%) believed that clinical and practical courses cannot be given by the internet. In terms of students’ opinion in the assessment process, more females (65.8%) preferred traditional exams than males (50.5%) (p < 0.05). Most clinical students (83%) preferred a combination of online and traditional teaching compared to 72% of preclinical students (p < 0.05). Clinical year students were more willing to communicate electronically with their classmates and instructors. The majority of dental students (65%) reported that future dental courses should be blended. Conclusions: In the pandemic era, blended learning, should become the preferred method of education whereby theoretical knowledge is delivered through online tutorials and clinical training is resumed on-site, to ensure competency of dental graduates while maintaining safety of the dental team. Current facilities and course designs should be improved in order to improve students’ experiences with blended learning.

Purpose Occlusal bite force (OBF) is the most important parameter in assessing biting efficiency. The aim of this study was to record OBF changes after surgical correction of high angle maxillary/mandibular (Max/Mand) class III patients and to compare these with that recorded in class III patients with average Max/Mand angle. Materials and methods Initially included were 42 patients with severe class III skeletal malocclusion who were scheduled for orthodontic surgery: group 1—22 patients with increased vertical relationship scheduled for bimaxillary surgery; group 2—20 patients with average vertical relationship scheduled for mandibular setback only. OBF measurements before surgery (T0), at debonding (T1) and at least 3 months after debonding (T2) were recorded using a portable occlusal force gauge. The following were also measured: maximum OBF (MOBF) achieved by the subject on each side, averaged OBF on each side (AOBF) and maximum OBF at the incisal region (MIOBF). At T2, only 33 patients (group 1: 17 and group 2: 16) were included in the analysis due to loss to follow-up. Results MOBF increased significantly in group 1, while no significant changes were detected in group 2. MIOBF increased after surgical correction in both groups. Significant increase in MIOBF was observed at T1 (P < 0.001) followed by an insignificant decrease during the observation period (3–6 months after treatment; P > 0.05). The two groups differed significantly in MOBF at T1 and T2, while no statistically significant differences were detected between the groups for MIOBF changes at the various time intervals (P > 0.05). The number of posterior teeth with occlusal contacts increased in both groups. Relapse was detected in group 1 where the number of posterior teeth in contact decreased during the observation period (T1–T2). Conclusion OBF greatly improved after surgical correction of the vertical morphology. Correction of high angle mandibular prognathism improves oral function in addition to esthetics.

Purpose: To report a comprehensive description of dental implant system selection practices among dentists practicing implantology worldwide.Materials and Methods: An online questionnaire was designed and sent to members of 15 dental implant organizations. The survey questions addressed: dental implant system selection criteria, implant design variables, dentists’ perspective to implant quality stamps, and dentists’ satisfaction with their implant system(s). Responses were compiled and analyzed to determine correlation of responses using the chi‐squared test (level of significance α ≤ 0.05).Results: Out of 4264 invitations sent, a total of 2001 (response rate = 46.9%) dentists participated in the survey. Approximately half of survey respondents (48.7%) were general dentists. More than two‐thirds of the survey respondents (72.5%) were performing both the surgical and prosthetic implant phases. Implant‐abutment connections were the most important dental implant system selection criterion (84.7%), followed by scientific evidence available on the implant system (82.8%), and simplicity of prosthetic steps (81.4%). Patient preferences (19.8%) were rated as the least important aspect. Sandblasted large gritted acid etched implant surfaces (SLA) were the most commonly used implant surfaces (75.8%); fluoride coated surfaces were the least commonly used (15.4%).Conclusion: According to the results of this survey, most survey respondents practiced both surgical and prosthetic phases of dental implantology. The majority of survey respondents agreed on the importance of implant‐abutment connections, scientific evidence available on implant systems, and simplicity of prosthetic steps when selecting implant systems.