Operative dentistry最新文献

Non-carious cervical lesions (NCCLs) become common in individuals over the age of 40 and are progressive. Those that are wedge-shaped in cross-section likely develop hazardous stress concentrations along their sharp axial extent, which can be distributed to lower, safer levels over a larger area via adhesive restoration. Restoration is indicated once a lesion progresses to a minimum restorable axial depth of at least 1.5 mm at the deepest extent, which threatens the strength of the tooth, especially a single-rooted tooth. Restorations with a glass ionomer or resin composite employing an adhesive system that is total-etch or is a self-etching primer combined with selective enamel etching are equally effective. Consequently, the restorative material can be selected based on isolation or esthetic factors.

This study evaluated the effect of 2.5% sodium hypochlorite (SH) or calcium hypochlorite (CH) submitted to passive ultrasonic irrigation (PUI) or conventional irrigation (CI) on the incidence of residues and the bond strength of the cementation system to post-space dentin. Distilled water (DW) and 2.5% SH followed by 17% EDTA (SH-ED) were used as negative and positive control groups, respectively. The cervical, middle, and apical thirds of the post space were evaluated. One hundred and twenty bovine incisors were endodontically treated and post-space preparation was performed. The specimens were randomly assigned to six groups, according to the solution and irrigation method: DW-CI, SH-ED-CI-SH, SH-CI, SH-PUI, CH-CI, and CH-PUI. The incidence of residues (n=10) over the dentin was evaluated by scores using SEM images. Other specimens were irrigated as previously described and the post cementation was immediately performed using a conventional dual resin cement and a two-step etch-and-rinse adhesive system. Push-out and failure modes were performed for bonding evaluation. Kruskal-Wallis and Dunn test for incidence of residues data and one-way ANOVA and Tukey tests for bond strength data were used at a significance level of 5%. The protocols that showed a lower incidence of residues were: SH-ED-CI-SH, SH-PUI, and CH-PUI for the cervical third and SH-ED-CI-SH for the middle third (p<0.05). In the apical third, the protocols were similar to each other (p>0.05). Bond strength values were higher after irrigation with DW-CI for all thirds (p<0.05). 2.5% sodium or calcium hypochlorite negatively impacted the adhesion interface and exhibited a greater incidence of residues over the post-space radicular dentin.

Objectives: The aim of this study was to measure radiant exposure and time necessary to deliver 16 J/cm2 of radiant exposure to simulated Class I and Class III preparations by first-year dental students. First-year dental students (n=89) received a 60-minute lecture on light-curing. Using the Managing Accurate Resin Curing Patient Simulator (MARC-PS) and protective blue-light-blocking glasses, students twice light-cured Class I and Class III restorations, using the Valo Grand Cordless light-curing unit with infection-control barriers on both Standard and High Power Plus modes. After their first attempts, if students did not obtain at least 16 J/cm2 of radiant exposure (RE), they received additional instruction. Paired t-tests were used to determine the change between the first and second attempts. After averaging two attempts, radiant exposure and time were compared between Standard and High Power Plus modes within individuals using paired t-tests.

Results: 79% of students provided 16 J/cm2 of radiant exposure on both attempts for Standard and High Power Plus modes. High Power Plus mode provided statistically significantly more radiant exposure and required less time to obtain 16 J/cm2 of radiant exposure for both restorations.

Conclusions: The MARC-PS is useful to identify students requiring instruction. It may be prudent to use High Power Plus mode or increase time on Standard mode to light-cure Class I restorations.

Objectives: This study aimed to assess color matching post-repair using the same or different single-shade composites of three distinct composite resin materials (Omnichroma-OM, ZenChroma-ZC, and Charisma Topaz One-CTO) following aging in coffee solution and distilled water. Evaluation focused on color change parameters (∆E00, ∆L00, ∆C00, and ∆H00).

Methods and materials: Specimens were prepared in disk shape with a diameter of 8 mm and a height of 2 mm (n=180). Half of each composite group was immersed in distilled water, while the other half was immersed in coffee solution for 12 days each (n=90). After aging, cylindrical cavities with a diameter of 4 mm and a depth of 1 mm were prepared at the center of the specimens. The cavities were repaired with both themselves and other composite resins (n=10). Color measurements of the specimens were performed using VITA Easyshade 5 (VITA Zahnfabrik, Bad Säckingen, Germany) at the following time points: baseline (T0), after aging (12 days) (T1), immediately after repair (T2), one day after repair (T3), one week after repair (T4), and one month after repair (T5).

Results: Statistically significant differences were found in the mean ΔE00 measurements among the study groups at all time points for each of the three composite resins (p<0.05). Similarly, statistically significant differences were found in the mean ΔE00 measurements over time for each of the three composite resins in each study group (p<0.05). The baseline measurements of materials repaired with themselves in the distilled water groups and the final measurements of materials repaired with themselves in the coffee groups were found to be within acceptable ∆E00limits. At the end of the study, only CTO repaired with OM showed acceptable color matching with different composites in both coffee and distilled water groups.

Conclusions: Acceptable color matching was achieved when using the same material for repair in specimens aged in distilled water and coffee. However, variations in matching were observed when different materials were used for repair, indicating the need for ongoing monitoring. Contributions of ΔL00, ΔC00, and ΔH00 values to color differences vary depending on the resins and repair process and change over time.

Objective: This study aimed to evaluate the mechanical and physical properties of dental dam sheets used for absolute isolation and to correlate the mechanical parameters with cost.

Methods and materials: Twenty-one dental dam sheets were tested: ALLPRIME; Madeitex; Sanctuary non-latex, Sanctuary latex black, green, and blue; Nic Tone blue and black; Mk Life; Elastidam; Bassi; Pribanic; Care; OK; MDC Dental; Keystone; Dura Dam; Flexidam; Sanctuary blue; Nic Tone blue; Ehros; and USE. The thicknesses of the dental dam sheets were measured using a digital micrometer (Mitutoyo). The dental dam sheets (n=15) were prepared by cutting the samples with dimensions of 80 × 10 mm with a 1.7 mm hole made at the center of each specimen, following the ISO 9001 standard. The specimens were tested using a universal testing machine (Emic) at a speed of 500 mm/min until rupture to calculate rupture force (RF, N), elongation (%), and ultimate tensile strength (UTS, MPa), their thickness (mm) was measured using a digital micrometer, and scanning electron microscopy and X-ray energy dispersive spectroscopy were performed to analyze the structure and composition. The radiopacity was measured using digital radiography. Thickness, UTS, RF, and elongation data were analyzed by one-way ANOVA and Tukey's test (α=0.05).

Results: The Flexidam dental dam had the largest thickness (0.5 mm), while Nic Tone had a median thickness of 0.3 mm; the RF value (41.3 N) was higher for the thicker dental dams. The other dental dams had RF values ranging from 19 to 30 N. The highest elongation was obtained for the non-latex Sanctuary dental dam (600 mm). The Bassi dental dam had the highest UTS value (15 MPa), and medium and small particles were observed in most of the gums. A loss of continuity was detected in the structure of Sanctuary green and blue media. The predominant elements in the sheets were carbon, magnesium, sulfur, silicon, and calcium.

Conclusions: The UTS, RF, and elongation varied substantially, indicating insufficient standardization of dental dam sheets. Nonetheless, most of the tested dental dams exhibited mechanical and physical properties suitable for clinical use. The correlation between the cost and mechanical properties of the dental dams was very low.

Objective: To evaluate the influence of battery level on power (mW), emission spectrum (mW/cm2/ nm), and light distribution on the active tip (mW/ cm2) of certified (FDA/ANVISA) and low-cost uncertified light-curing units (LCUs) purchased through e-commerce.

Methods: Seven LCUs, three certified: VALO Grand (Ultradent); Radii Xpert (SDI); and LED.B (Woodpecker); and four uncertified: 1 Sec; BS 300; LED curing light; and VAFU (VRN, AZDENT), were used. The LCUs were evaluated by calculating the power (mW) after each sequential five exposure cycles of 20 seconds and the emission spectrum (mW/cm2/nm) in the initial and final cycles, using an integrating sphere during three battery charging cycles. Beam profiling was used to check the light distribution on the LCU tip after every 50 exposure cycles until the battery fully discharged. Data were analyzed by linear regression between power and the number of exposure times (R2).

Results: The certified LCUs VALO Grand (R2=0.005), LED.B (R2=0.02), and Radii Xpert (R2=0.09) and the uncertified LCU VAFU (R2=0.002) had no significant power reduction during the three battery charging cycles. The uncertified LCUs BS 300 (R2=0.87), 1 Sec (R2=0.60), and LED curing light (R2=0.83) showed significant power reduction, decreasing the emission spectrum (mW/cm2/nm) at the end of the battery charging cycle. The light distribution on the active tip across the level battery was modified significantly with successive exposure times.

Conclusions: The certified LCUs (VALO Grand, Radii Xpert, and LED.B) and uncertified LCU (VAFU), maintained power, emission spectrum, and light distributions during the tested battery life cycles. Low-cost certified LCU LED.B exhibited inhomogeneous light concentrated at the center of the tip. Low-cost uncertified LCUs-BS 300, 1 Sec, and LED curing light-had significant power reductions during the battery cycles and increased inhomogeneous light distribution along the successive exposure times.

Objectives: This case report describes a digital workflow for designing and 3D printing a guide with the dual purpose of gingivectomy and tooth preparation in the esthetic zone, to be followed by cementation of ceramic veneers under rubber dam isolation.

Clinical considerations: The patient's primary concern was to improve her smile. After clinical evaluation, our recommendation was for a minimal gingivectomy to match the gingival zenith for both central incisors, to be followed by ceramic laminate veneers. A digitally designed and 3D printed guide was used for gingivectomy and tooth preparation for the ceramic veneers. Ceramic veneers were cemented under rubber dam isolation to maximize bonding properties.

Conclusions: A single guide can be digitally designed and 3D printed to perform controlled gingivectomy and minimally invasive tooth preparations. The outcome of the gingivectomy improved the gingival architecture for central incisors, and the ceramic veneers fulfilled the patient's esthetic demands.

Objectives: This study investigated the effect of different surface treatments on the shear bond strength (SBS) and failure modes of self-cured (SC) and light-cured (LC) high-viscosity glass ionomer cements (HVGICs) to silver diamine fluoride (SDF)-treated simulated carious dentin (SCD).

Methods and materials: Extracted human premolars were sectioned and pH cycled for 10 days to simulate carious dentin. The demineralized specimens were treated with 38% SDF (Riva Star) for 2 minutes, washed, stored in deionized distilled water at 37°C for 2 weeks, and subjected to the following surface treatments (n=14): T1 - no treatment (control); T2 - 10 seconds polyacrylic acid (PAA); T3 - 5 seconds phosphoric acid (PPA); T4 - 5 seconds PPA plus universal adhesive (Zipbond); and T5 - 5 seconds PPA plus resin-modified GIC adhesive (Riva bond LC). SC (Riva Self-cure HV) and LC (Riva Light-cure HV) HVGICs were applied to the conditioned specimens and stored in artificial saliva at 37°C for 1 week. SBS and failure modes were subsequently determined. Statistical analyses were performed using Kruskal-Wallis/post-hoc Mann-Whitney U and Chi-square tests (α=0.05).

Results: The highest SBS was observed when SC and LC were restored with T2 and T5, respectively. Significant differences in SBS were as follows: SC - T2, T1 > T5, T3; LC - T5, T4, T3 > T2. SC generally exhibited adhesive failures, while LC presented both adhesive and mixed failures.

Conclusion: The preferred method for preparing SDF-treated carious dentin before restoration application is PAA for SC and PPA plus RMGIC adhesive for LC HVGICs.