Effect of Type of Resin Composite Material on Porosity, Interfacial Gaps and Microhardness of Small Class I Restorations.

AIM: This study aimed to compare the best restorative approach for the conservative class I cavity by comparing flowable and nanohybrid composites versus the placement technique regarding surface microhardness, porosity, and presence of interface gaps. MATERIALS AND METHODS: Forty human molars were divided into four groups (n = 10). Standardized class I cavities were prepared and restored using one of the following materials: Group I - Flowable composite placed by incremental technique; group II - Flowable composite placed in one increment; group III - Nanohybrid composite placed by incremental technique; and group IV - Nano-hybrid composite placed in one increment. After finishing and polishing, specimens were sectioned into two halves. One section was chosen randomly for the Vickers microhardness (HV) evaluation and the other section was used for the assessment of porosities and interfacial adaptation (IA). RESULTS: The surface microhardness range was 28.5-76.2 (p < 0.05), mean pulpal microhardness range was 27.6-74.4 (p < 0.05). Flowable composites had lower HV than conventional counterparts. The mean pulpal HV of all materials exceeded 80% of occlusal HV. Restorative approaches did not statistically differ in porosities. However, IA percentages were higher in flowable materials compared to nanocomposites. CONCLUSION: Flowable resin composite materials have lower microhardness than Nanohybrid composites. In small class I cavities, the number of porosities was similar between the different placement techniques and the interfacial gaps were highest in the flowable composites. CLINICAL SIGNIFICANCE: The use of nanohybrid resin composite to restore class I cavities will result in better hardness and less interfacial gaps compared to flowable composites.

Evaluation of Marginal and Internal Fit of a CAD/CAM Monolithic Zirconia-Reinforced Lithium Silicate Porcelain Laminate Veneer System.

PURPOSE: To evaluate the marginal and internal fit of monolithic computer-aided design/computer-aided manufacturing (CAD/CAM) ZLS (Vita Suprinity) glass ceramic porcelain laminate veneers (PLVs), in terms of marginal and internal gap widths, in comparison to monolithic lithium disilicate (LDS) [IPS e.max CAD] CAD/CAM veneers, and, also, to analyze the effect of incisal preparation designs (butt joint and chamfer), on the marginal and internal fit accuracy. MATERIALS AND METHODS: Forty dental stone dies poured from impressions made of two master metal dies with different incisal preparation designs were scanned to produce digital models. Forty ceramic veneers were designed and milled using the virtual models-10 ZLS butt joint, 10 ZLS chamfer, 10 LDS butt joint, and 10 LDS chamfer. The monolithic ceramic veneers produced were then subjected to marginal and internal gap width evaluation using X-ray nano-computed tomography and computerized digital analysis (n = 10). Descriptive analyses of data were performed and the influence of "material" and "preparation design" on the marginal and internal fit of veneers was assessed using 2-way ANOVA (α = 0.05). Bonferroni post-hoc multiple comparison tests were used to further analyze the interactions between the material and preparation design after adjusting the α value by Holm-Bonferroni method (α = 0.01). RESULTS: Mean marginal and internal gaps for ZLS PLVs were 65 ±11 µm and 112 ±14 µm for butt joint, and 100 ±24 µm and 100 ±21 µm for chamfer, respectively. Corresponding values for LDS PLVs were 78 ±25 µm and 114 ±17 µm for butt joint, and 104 ±18 µm and 106 ±7 µm for chamfer. Marginal gap and internal gap differences between ZLS and LDS PLVs were not significant (marginal gap: F = 1.786, p = 0.190; internal gap: F = 0.807, p = 0.375). However, the preparation designs (butt joint and chamfer) differed significantly in terms of marginal gaps (F = 23.797, p = 0.000), but not internal gaps (F = 3.703; p = 0.059). CONCLUSIONS: Butt joint margins produced better marginal accuracy in terms of marginal gap, compared to chamfers, for ZLS CAD/CAM laminate veneers.

Evaluating color stability and enamel surface roughness following resin infiltration treatment.

OBJECTIVE: To assess the impact of resin infiltration treatment on enamel color stability and surface roughness after simulating daily exposure to coffee stains and regular toothbrushing with standard toothpaste. MATERIALS AND METHODS: In this in vitro study, we utilized 47 caries-free human enamel specimens, which were divided into two distinct groups. The teeth in the study group underwent artificial demineralization, Icon resin infiltration, and polishing, while the control group received only polishing. Following this, all teeth from both groups were regularly immersed in freshly brewed coffee for 15 min, twice daily, over a span of 30 days. After each staining session, the teeth underwent 10 heavy circular strokes using a soft toothbrush and standard toothpaste. Color changes were measured on Days 1 and 30 using a spectrophotometer. The L*, a*, b* color system defined by the International Commission on Illumination was used to assess the changes. Surface roughness was evaluated at baseline and after 30 days using a 3D surface Metrology Microscope. RESULTS: After 30 days of immersion in coffee, both the study and control groups showed significant changes in color. However, differences were statistically significant between groups for "L" and "a" parameter but not for "b." The overall color change in the study group was higher than the control group. There were no significant differences in surface roughness within or between the groups before and after staining and brushing. CONCLUSIONS: Resin infiltration leads to a significant increase in staining compared to untreated enamel. These staining properties should be taken into account when making clinical decisions regarding the treatment of white spot lesions.

Knowledge, Attitude, and Barriers to Fluoride Application as a Preventive Measure among Oral Health Care Providers.

OBJECTIVE: To investigate the knowledge, attitude, and possible barriers to fluoride application among oral health-care providers in Kuwait. METHODS: A validated self-administered questionnaire was distributed to a random sample of 291 dentists. The questionnaire included four categories: dentists' characteristics, knowledge of and attitude towards fluoride application, factors influencing decision-making on prescription of fluoride, and the clinician's perception of own knowledge. Means, group differences, and logistic regression were calculated. RESULTS: 262 completed the questionnaire (response rate of 90%). Half of the participants (49%) reported that water fluoridation is the best method for caries prevention in children. Majority of the participants (80%) acknowledged that topical fluoride prevents dental caries, but only 40% frequently use it in their practices. Fear of overdose was a concern in 57% of the participants. About 31% believed that caries is a multifactorial disease and cannot be prevented. In addition, 32% of the dentists who thought caries is multifactorial and cannot be prevented stated that restorations take precedence over preventive therapy. CONCLUSION: Despite the participants being in favor of topical fluoride application and believing in its effectiveness, certain barriers were apparent such as knowledge deficiencies, products labelling flaw, and lack of participation in effective continuing educational activities.