Blended learning in undergraduate dental education: a global pilot study.

AIMS: To explore the global trends in blended learning in undergraduate dental education during the COVID pandemic and during the recovery phase by engaging with the students and faculty and evaluate the implications for dental education in the post-COVID era. METHODS: It was a pilot cross-sectional study which employed a convenience sampling technique to recruit representatives of dental faculty and undergraduate students in 80 dental institutions globally. A previously validated questionnaire consisting of a combination of closed and open-ended items was used for data collection. Responses to these online questionnaires were processed and analysed using the R statistical computing environment. RESULTS: A total of 320 dental students and 169 faculty members from 47 different dental institutions participated in the study. Video and Live Online Tutorials were considered to be the most effective method of online learning followed by online question banks by both groups. Significant differences were noted between faculty and students regarding time spent and effectiveness of online teaching and learning, respectively, both before and after the start of COVID. The results highlight the faculty need to engage more closely with the students to address their learning needs. Finally, the participants provided several recommendations regarding the future development of teaching and learning strategies as well as assessments in the post-pandemic era. CONCLUSIONS: This is the first study which explores blended learning in dental education with participants from multiple institutions in different regions of the globe. Compared to the faculty, students considered online learning to be less interactive and preferred learning activities and all assessments to be delivered face-to-face. The results underscore the need to adapt teaching practices to suit the learning needs of the students.

Surface Roughness of Monolithic and Layered Zirconia Restorations at Different Stages of Finishing and Polishing: An In Vitro Study.

PURPOSE: To evaluate surface roughness and topography of different zirconia-based restorations at various steps of finishing and polishing. MATERIALS AND METHODS: Seventy-five zirconia discs were fabricated and divided into 3 layered and 2 monolithic groups: layered conventional (VM9; Vita), layered pressed (PM9; Vita), layered digital (TriLuxe Forte; Vita), opaque monolithic (Ceramill Zi; Amann Girrbach), and translucent monolithic (Zolid FX; Amann Girrbach). Surface roughness testing (Ra, Rz) and scanning electron microscopy were performed at the glazed, unglazed, finished, polished, super-polished, and super-polished with diamond paste steps. One-way ANOVA and Tukey tests were used for statistical analysis. RESULTS: There were significant differences in all groups among the different steps (p < 0.001, F = 77.67 for layered conventional; p < 0.001, F = 133.90 for layered pressed; p < 0.001, F = 47.94 for layered digital; p < 0.001, F = 48.05 for zirconia opaque; p < 0.001, F = 43.91 for zirconia translucent). For the layered groups, glazed stage was significantly different from all other steps (p < 0.001). For the layered conventional and digital groups, polishing using diamond paste was not significantly different from the polished and super-polished steps (p = 0.448, p = 0.153), while for the layered pressed group, polishing using diamond paste was not significantly different from the super polished step (p = 0.815). For monolithic groups, there were no significant differences between the polished and super-polished steps (p = 0.957 for zirconia opaque, p = 1.00 for zirconia translucent). Both the diamond paste and super-polished steps showed no significant differences (p = 0.620, p = 0.550) from the glazed surface in the opaque zirconia group. CONCLUSIONS: Surface roughness of monolithic and layered zirconia was improved by polishing; however, only opaque zirconia reached the level of surface roughness of the glazed stage. Type of buildup affected the surface roughness of adjusted ceramics, with monolithic zirconia showing lower surface roughness than layered zirconia. Polishing with diamond paste provided no significant improvement in the surface roughness of monolithic or layered zirconia.

Spectrophotometric Analysis of the Influence of Metal Alloy Choice, Opaque Thickness, and Repeated Firing on the Shade of Metal Ceramic Restorations.

PURPOSE: To determine the effect of type of base metal alloy, opaque thickness, and repeated firing on color of metal ceramic restorations. MATERIALS AND METHODS: Four nickel chromium and four cobalt chromium were selected with one noble alloy as a control. Ten discs (16 mm 0.5 mm) were prepared for each group. Color of specimens were measured using a spectrophotometer and were calculated using CIEDE2000 formula (ΔL', ΔC', ΔH', ΔE') between experimental groups and control at six stages of porcelain constructions: opaque 0.1 and 0.3 mm, dentine, enamel, glaze, and three times repeated firing. Shade A3 was used. One-way analysis of variance and Bonferroni multiple test were performed (α = 0.05). RESULTS: Alloy type and stage showed statistical significance on total color and color parameter differences from the control and there was significant interaction between them (p < .05). Nidour alloy was the closest to control. Increase in ΔC' and a decrease in ΔH' and in a* and b* was the commonest in comparison with the control. However, ΔE' was below acceptability threshold for all alloys at all stages. CONCLUSION: Despite the statistical significance, base metal alloys performed as good as noble metal control. Neither opaque thickness, nor repeated firing affected color variations from the control group. There was no obvious trend in the behavior of metal alloys at all stages. However, increase in chroma and a decrease in hue, with green blue shift, was the most common. CLINICAL SIGNIFICANCE: Records of the effects of eight commonly used base metal alloys on the color of final shade of the metal-ceramic restorations, at various stages of ceramic buildup, have considerable value. (J Esthet Restor Dent 28:S56-S67, 2016).

Improved Construction of Auricular Prosthesis by Digital Technologies.

Implant-retained auricular prostheses are a successful prosthetic treatment option for patients who are missing their ear(s) due to trauma, oncology, or birth defects. The prosthetic ear is aesthetically pleasing, composed of natural looking anatomical contours, shape, and texture along with good color that blends with surrounding existing skin. These outcomes can be optimized by the integration of digital technologies in the construction process. This report describes a sequential process of reconstructing a missing left ear by digital technologies. Two implants were planned for placement in the left mastoid region utilizing specialist biomedical software (Materialise, Belgium). The implant positions were determined underneath the thickest portion (of anti-helix area) left ear that is virtually simulated by means of mirror imaging of the right ear. A surgical stent recording the implant positions was constructed and used in implant fixtures placement. Implants were left for eight weeks, after which they were loaded with abutments and an irreversible silicone impression was taken to record their positions. The right existing ear was virtually segmented using the patient CT scan and then mirror imaged to produce a left ear, which was then printed using 3D printer (Z Corp, USA). The left ear was then duplicated in wax which was fitted over the defect side. Then, it was conventionally flasked. Skin color was digitalized using spectromatch skin color system (London, UK). The resultant silicone color was mixed as prescribed and then packed into the mold. The silicone was cured conventionally. Ear was trimmed and fitted and there was no need for any extrinsic coloring. The prosthetic ear was an exact match to the existing right ear in shape, skin color, and orientation due to the great advantages of technologies employed. Additionally, these technologies saved time and provided a base for reproducible results regardless of operator.

Parallelism of abutment teeth on fixed partial dentures.

A total of 100 working dies for fixed partial denture (FPD) abutments were prepared to fit 50 three-unit fixed-fixed conventional FPDs. For each FPD, the axial convergence angles between the mesial and distal axial walls of the abutment teeth were measured. For all FPDs, there were no statistically significant differences between the mesial and distal convergence angles of abutment teeth measured, regardless of their location within the oral cavity. The distal convergence angle of posterior FPD abutments was the highest angle, while the lowest was recorded for the mesial convergence angle of the anterior FPD abutments.

Fracture resistance of aluminium oxide and lithium disilicate-based crowns using different luting cements: an in vitro study.

AIM: The aim of this study was to investigate the fracture resistance of two types of ceramic crowns cemented with two different cements. METHODS AND MATERIALS: Forty premolar crowns were fabricated using lithium-disilicate (IPS Empress-2) and glass-infiltrated aluminium-oxide (In-Ceram) ceramic systems. The crowns were divided into four groups (n=10) with Group 1 (IPS Empress-2) and Group 2 (In-Ceram) cemented with glass ionomer cement. Group 3 (IPS Empress-2) and Group 4 (In-Ceram) were cemented with resin cement. Crowns were tested in a universal testing machine at a compressive-load speed of 10 mm/min. Fracture modes were grouped into five categories. One way analysis of variance (ANOVA) and Bonferroni post-hoc tests were used to detect statistical significances (p<0.05). RESULTS: The mean (SD) fracture resistance (Newtons) for Groups 1 to 4 were: 245.35 (82.69), 390.48 (67.03), 269.69 (10.33), and 418.36 (26.24). The cement type had no statistical significant effect (p>0.05) on fracture resistance within each ceramic system tested. In-Ceram crowns cemented with either glass ionomer or resin cements exhibited a statistically significantly higher fracture-resistance than IPS Empress-2 crowns (p<0.05). Minimal fracture in the test crowns was the common mode exhibited. CONCLUSION: Fracture resistance of IPS Empress-2 and In-Ceram crowns was not affected by the type of cement used for luting. CLINICAL SIGNIFICANCE: Both In-Ceram and IPS Empress-2 crowns can be successfully luted with the cements tested with In-Ceram exhibiting higher fracture resistance than IPS Empress-2.

Fracture resistance of teeth restored with different post systems: in vitro study.

OBJECTIVES: The objective of this study was to investigate fracture resistance and mode of failure of teeth restored with different prefabricated post systems. STUDY DESIGN: Thirty teeth were collected, sectioned 15 mm from the apex, root canal prepared, and randomly allocated into 3 groups as follows: glass fiber posts (group 1), carbon fiber posts (group 2), and Radix-Anchor titanium posts (group 3). Teeth were then restored with a composite core and tested using a universal testing machine at 10 mm/min cross-head speed. Mode of failure was identified as either reparable or irreparable (catastrophic). RESULTS: Mean values of fracture forces (N) for teeth restored with Radix posts (571.6) were statistically significantly higher than teeth restored with either carbon fiber (420.6) or glass fiber posts (393.9). There were 86.67% of fractures that were catastrophic in nature. CONCLUSIONS: Teeth restored with Radix-titanium posts were more resistant to fracture than those restored with either carbon or glass fiber posts. Most of the fracture modes were catastrophic in nature.

Shear bond strength of orthodontic brackets bonded to different ceramic surfaces.

This study was undertaken to measure the shear bond strength (SBS) of stainless steel brackets bonded to different ceramic surfaces, to compare the SBS of the different ceramics with each other and with conventional ceramo-metal porcelains, and to determine the mode of failure for each group following debonding. A total of 60 ceramic crowns were constructed on extracted teeth and divided into three equal groups as follows: In-Ceram ceramic crowns, IPS-Impress ceramic crowns, and conventional ceramo-metal porcelain. Standard edgewise metal premolar brackets were bonded to the prepared porcelain surfaces. After bonding, all samples were tested in shear mode on an Instron universal testing machine. Statistical analysis was undertaken using analysis of variance, LSD, and chi-squared tests. The results showed that the SBS for the ceramo-metal and the In-Ceram groups were comparable, with mean values of 80.54 +/- 13.44 N and 78.87 +/- 13.47 N, respectively. The IPS-Impress group showed the weakest SBS which averaged 67.40 +/- 8.99 N. This was significantly lower than that of the conventional ceramo-metal porcelain (P < 0.001) and the In-Ceram surface (P < 0.01). The mode of failure in the ceramo-metal group was between the porcelain surface and adhesive and in the other two ceramic groups, between the brackets and adhesive (P < 0.001). The SBS of orthodontic brackets to the three tested ceramic surfaces were adequate for orthodontic use.

Relationship between tooth irregularity and periodontal disease in children with regular dental visits.

OBJECTIVES: The aim of this study was to investigate any association between irregular teeth and periodontal breakdown among children who attend dental clinics regularly. METHODS: The subjects were 80 children (39 females and 41 males) with a mean age of 12.38 +/- 0.75 years. Each subject had an alginate impression in the mandibular arch, periapical radiographs for the lower incisor teeth and clinical examination for periodontal health. Plaque accumulation, gingival condition and probing depth, bone level and status of lower incisor teeth contact areas were recorded. Spearman correlation test was used to observe any relationship between the clinical variables. RESULTS: The average probing depth, gingival index and plaque index scores in the subjects studied were 1.3 +/- 0.25, 0.99 +/- 0.28 and 1.17 +/- 0.52 respectively. The average number of sites with labiolingual displacement with mesiodistal overlap was 1.81 +/- 1.30 and those without mesiodistal overlap was 1.39 +/- 1.10. The average number of contact areas with spacing was 0.59 +/- 1.23. The correlation observed between irregularity and periodontal health indicated no association between the number and type of displacement and plaque accumulation, gingivitis, attachment loss and alveolar bone level. CONCLUSION: There was no association between irregularity of teeth and periodontal diseases in presence of good oral hygiene.

Oral health attitudes, knowledge, and behavior among school children in North Jordan.

The aim of this study was to assess the knowledge, attitude, and behavior of school children towards oral health and dental care as well as to evaluate the factors that determine these variables. School children (n=557) of an average age of 13.5 years attending public schools in North Jordan were recruited into this study. The subjects completed a questionnaire that aimed to evaluate young school children's behavior, knowledge, and perception of their oral health and dental treatment. The participants' oral hygiene habits (such as tooth brushing) were found to be irregular, and parents' role in the oral hygiene habits of their children was limited. The study population showed higher awareness of caries than periodontal conditions. Irregular visits to the dentist were found to be common, and toothache was the major driving factor for dental visits. Children had positive attitudes toward their dentists; nevertheless, they indicated that they feared dental treatment. The children in this study also recognized the importance of oral health to the well-being of the rest of the body. Parents were not proactive in making sure that their children received regular dental care. Parents' knowledge and attitudes about the importance of oral health care and their fears about dental treatment influenced their children's dental care. The results of this study indicate that children's and parents' attitudes toward oral health and dental care need to be improved. Comprehensive oral health educational programs for both children and their parents are required to achieve this goal.

Convergence angle, occlusal reduction, and finish line depth of full-crown preparations made by dental students.

OBJECTIVE: To measure the convergence angle, incisal/occlusal clearance, and finish line depth, which indicate the amount of axial reduction of full metal-ceramic crown preparations made by final-year dental students. METHOD AND MATERIALS: A total of 157 preparations were assessed. Convergence angle and finish line depths were measured by Tool Maker Microscope, while crown height was measured using a digital caliber. RESULTS: The mean convergence angle, faciolingually and mesiodistally, was 22.4 and 25.3 degrees, respectively. The mean for molars was statistically significantly greater than that for other teeth. The incisal/occlusal reduction ranged from 1.8 to 2.2 mm and averaged 2 mm. Buccal shoulder finish line depth averaged 0.86 mm, and mean chamfer finish line depth was 0.74 mm lingually, 0.7 mm mesially, and 0.66 mm distally. The buccal shoulder for mandibular anterior teeth was significantly smaller than for other teeth and averaged only 0.45 mm. CONCLUSION: The mean convergence angle was clinically acceptable. However, shoulder depth was less than the recommended depth of 1.0 to 1.5 mm for metal ceramic crowns. Incisal/occlusal reduction was clinically adequate to provide enough structural durability and color matching.

Evaluation of shear bond strength with different enamel pre-treatments.

The purpose of this study was to investigate the shear bond strengths of two adhesives, Panavia-21 and a composite resin (Transbond XT), with different enamel pre-treatments, acid etching (37 per cent phosphoric acid) and grit blasting (50 microm aluminium oxide particles). The mode of bond failure was also assessed using the modified adhesive remnant index (ARI). Ninety freshly extracted non-carious human premolar teeth were randomly divided into the following groups: (1) Transbond XT, acid-etched enamel surface; (2) Panavia-21, acid-etched enamel surface; (3) Transbond XT, grit-blasted enamel surface; (4) Panavia-21, grit-blasted enamel surface; (5) Transbond XT, acid-etched enamel surface with grit-blasted brackets; (6) Panavia-21, acid-etched enamel surface with grit-blasted brackets. All groups had stainless steel brackets bonded to the buccal surface of each tooth. An Instron universal testing machine was used to determine the shear bond strengths at a crosshead speed of 0.5 mm/second. Statistical analysis was undertaken using analysis of variance and the Tukey test. The mean bond strength values were as follows: group 1, 135.7 +/- 23.0 N; group 2, 181.5 +/- 18.4 N; group 3, 38.4 +/- 27.5 N; group 4, 59.1 +/- 24.1 N; group 5, 106.7 +/- 21.5 N; group 6, 165.3 +/- 21.4 N. Panavia-21 with the acid-etched enamel surface had a significantly higher shear bond strength than the other groups (P < 0.001). This was followed by the composite group with the acid-etched enamel surface. This group differed significantly from the composite and Panavia-21 groups with the grit-blasted tooth surface (P < 0.001) and from the composite and Panavia-21 groups with the acid-etched enamel surface and grit-blasted brackets (P < 0.01). The current findings indicate that Panavia-21 is an excellent adhesive and produces a bond strength that is clinically useful. Enamel surface preparation using grit blasting alone results in a significantly lower bond strength and should not be advocated for clinical use.

Dental diseases in subjects with beta-thalassemia major.

OBJECTIVES: The aim of this study was to determine whether beta-thalassemia major is associated with an increase in the severity of periodontal disease and dental caries. METHODS: A total of 61 thalassemia patients and 63 healthy controls (age range = 6-18 years) were examined for plaque deposits, gingivitis, periodontitis and dental caries using Silness and Löe plaque index (Pl.I), Löe and Silness gingival index (GI), probing pocket depth (PPD) and DMFT, respectively. RESULTS: There were no significant differences in Pl.I, GI and PPD scores between both thalassemia patients and healthy control groups (P > 0.05). Dental caries was significantly higher in thalassemia patients group (P < 0.0001) compared to the healthy controls. CONCLUSION: Thalassemia is not associated with increased levels of gingivitis or periodontitis but is associated with higher dental caries experience.

Uvulo-glosso-pharyngeal dimensions in subjects with beta-thalassaemia major.

The purpose of this study was to investigate cephalometrically the uvulo-glosso-pharyngeal dimensions in subjects with beta-thalassaemia major. The subjects were 15 thalassaemic patients (eight males, seven females) with a mean age of 14.13 +/- 1.06 years. The variables measured on the lateral cephalograms were tongue height and length, soft palate length and thickness, superior, middle and inferior pharyngeal airway space, and hyoid bone position. The thalassaemic group was compared with a normal control group matched for sex and age using a t-test. The results showed that thalassaemic patients had a smaller tongue size (length P < 0.05, height P < 0.001), shorter soft palate (P < 0.001), smaller upper (P < 0.001) and middle (P < 0.05) pharyngeal airway spaces, and a shorter vertical pharyngeal length (P < 0.05). The hyoid bone in thalassaemic patients was closer to the mandibular plane (P < 0.001).