Effects of Artificial Aging of Direct Resin Nano-Hybrid Composite on Mean Bond Strength Values for Veneer Ceramic Samples.

BACKGROUND This study investigates the effect of artificial aging of direct resin nanohybrid composites on mean bond strength values for veneer ceramic samples. MATERIAL AND METHODS Ninety direct nanohybrid composite resin (Tetric N-Ceram) cylindrical discs were divided into 5 groups (n=18 each) based on aging cycles (thermocycling), as follows: TC=no aging (control), T1=850, T3=2500, T6=5000, and T12=10000 cycles, representing 1, 3, 6, and 12 months of clinical usage, respectively. Lithium disilicate glass ceramic (IPS e.max Press) cylindrical discs were cemented to resin discs using resin cement (Variolink N) after surface treatments (ceramic etching, silaning, composite abrasion). Differences in means between subgroups were calculated using one-way ANOVA, followed by the Tukey honestly significant differences post hoc test. Differences were considered statistically significant with a P value ≤0.05. RESULTS The highest SBS between ceramic and aged composite was observed at 1 month (m=20.35) but did not differ significantly from the control group (m=20.97). For all other subgroups (3, 6, 12 months) SBS was significantly less than that of the control (P≤0.05). At 1 and 3 months, cohesive failures were more common, whereas adhesive failures were more common in 6- and 12-month-old composites. CONCLUSIONS SBS of aged composites was less than that of non-aged composites, with SBS decreasing proportionally as the resin aged. When cementing a ceramic restoration over existing composite restorations, those older than 1 month should be removed and replaced with new ones.

Influence of Prosthodontic Rehabilitation Using Zygomatic Implants in Covid 19 Related Mucormycosis (Rhino-Orbital-Cerebral) Maxillectomy Patients Upon Post-Operative Stress, Anxiety and Functional Impairment: A Prospective Cohort Study.

Purpose: To determine the influence of prosthodontic rehabilitation using zygomatic implants in partial maxillectomy upon post-operative stress, anxiety and functional impairment, due to covid 19 associated rhino-orbital-cerebral mucormycosis (ROCM). Patients and Methods: Twenty maxillectomy patients fulfilling study criterion, received zygomatic implants (ZI) (quad zygoma) (ZDI Simpladent, Switzerland) retained/supported complete maxillary denture. Assessment of stress, anxiety, masticatory performance and speech were determined using diurnal salivary cortisol level, Appearance Anxiety Inventory, multiple sieve technique and auditory perception analysis, respectively. Data were recorded at 6 different stages of rehabilitation (after maxillectomy, implant placement, and after prosthesis delivery (1 week, 1 month, 6 months and 1 year)). Demographic data were expressed as frequency distribution, while mean values were used to find differences between various rehabilitation stages using Friedman and chi-square test with statistical significance value at p < 0.05. Results: Average daily salivary cortisol levels declined from post maxillectomy (22.80 ± 0.902) to 1 year after prosthesis wearing (8.65 ± 0.985), indicating stress reduction after ZI rehabilitation. Mean scores for appearance anxiety reduced from pre-prosthetic rehabilitation (27.350 ± 3.030) to 1 year (8.950 ± 0.887) following prosthesis wearing. Functional parameters for mastication and speech also improved significantly during the course of rehabilitation. All differences between pre-prosthetic to 1-year stage after prosthesis wearing were found to be statistically significant at p < 0.05. Conclusion: Post ROCM maxillectomy cases after prosthetic rehabilitation using zygomatic implants showed significant improvement in the psychological (stress and anxiety) as well as function (mastication and speech) characteristics. Rehabilitation post ROCM maxillectomy with the present approach of fixed prosthesis using zygomatic implants mitigates deficient mastication and speech. It also impacts positively on patient psychology by decreasing stress and anxiety.

Assessment of Separation Impact and Perception of Discomfort on Various Orthodontic Separators: A Comparative Clinical Study.

AIM: This study aimed to evaluate the extent of separation and perception of pain and discomfort with the use of three different orthodontic separators. MATERIALS AND METHODS: A total of sixty participants (26 males and 34 females) aged between 18 and 25 years were enrolled in this study. Participants were divided into three experimental groups: Group I: elastomeric separator, Group II: Dumbbell separators, and Group III: Kesling Separators. All the participants were asked to revisit 24 h after separator placement, and the effect of separation obtained by three different types of separators was measured. The space generated between premolars and molars was recorded separately on days 1, 3, and 7. The visual analog scales were used to assess pain. RESULTS: The mean age in Dumbbell separators group was slightly more (23.32 ± 2.28) compared to Kesling Separators and Elastomeric separator group (22.46 ± 1.20 and 21.10 ± 1.19 years, respectively). The extent of separation on days 1, 3, and 7 was more in Group II study participants (0.20 ± 0.02, 0.32 ± 0.05, and 0.48 ± 0.07 mm, respectively) compared to other groups. A statistically significant (P = 0.022) difference was noted on day 7 in terms of no pain being recorded more in Group II participants, followed next by Groups III and I. CONCLUSION: This study concluded that the Dumbbell separators produce acceptable separation with negligible pain and discomfort when compared to elastomeric separators and Kesling separators.

Evaluation of the Effect of Different Types of Fluoride on Tensile Properties and Surface Roughness of Different Titanium-Based Archwires: An In vivo Study.

OBJECTIVES: The purpose of the study was to evaluate the effect of different types of fluoride on tensile properties and surface roughness of titanium based archwires clinically. MATERIALS AND METHODS: Three groups of archwires, namely nickel-titanium (NiTi), heat activated NiTi, and TMA was evaluated clinically. Each group comprised four subgroups, namely as received group, nonfluoride control group, APF gel group (received one application of 1.23% APF gel), and sodium fluoride mouthwash group (patients rinsed twice daily with 0.2% sodium fluoride mouthwash). All the archwires were removed after 3 weeks of clinical use and evaluated for surface roughness with three dimensional optical profiler. Tensile strength and elongation rate was determined with Instron universal testing machine. RESULTS: NiTi, heat activated NiTi, and TMA archwires with APF gel application showed the highest reduction in tensile strength and elongation rate and highest value for surface roughness, followed by sodium fluoride mouthwash group and finally wires without fluoride application. NiTi wires had the highest reduction in tensile strength with APF gel followed by heat activated NiTi and TMA. CONCLUSION: APF gel with highest concentration of fluoride caused most degradation in the tensile properties and surface roughness of titanium based arch wires.