Evaluation of the radiopacity of restorative materials with different structures and thicknesses using a digital radiography system.

PURPOSE: The aim of this study was to evaluate the radiopacities of various types of restorative materials with different thicknesses compared with enamel, dentin, and aluminum. MATERIALS AND METHODS: Four bulk-fill resins, 2 hybrid ceramics, 2 micro-hybrid resin composites, 6 glass ionomer-based materials, 2 zinc phosphate cements, and an amalgam were used in the study. Twelve disk-shaped specimens were prepared from each of 17 restorative materials with thicknesses of 1 mm, 2 mm, and 4 mm (n=4). All the restorative material specimens with the same thickness, an aluminum (Al) step wedge, and enamel and dentin specimens were positioned on a phosphor storage plate and exposed using a dental X-ray unit. The mean gray values were measured on digital images and converted to equivalent Al thicknesses. Statistical analyses were performed using 2-way analysis of variance and the Bonferroni post hoc test (P<0.05). RESULTS: Radiopacity was significantly affected by both the thickness and the material type (P<0.05). GCP Glass Fill had the lowest radiopacity value for samples of 1 mm thickness, while Vita Enamic had the lowest radiopacity value for 2-mm-thick and 4-mm-thick samples. The materials with the highest radiopacity values after the amalgam were zinc phosphate cements. CONCLUSION: Significant differences were observed in the radiopacities of restorative materials with different thicknesses. Radiopacity was affected by both the material type and thickness.

Clinical effects of dehydration on tooth color: How much and how long?

OBJECTIVE: To evaluate effects of dehydration on tooth color determine whether color returns to baseline after 30 min or 24 h. MATERIALS AND METHODS: Thirty participants with intact maxillary central and lateral incisors were recruited for the study. Color measurements were performed with a spectrophotometer (SpectroShade Micro) at baseline and at 10, 20, and 30 min of dehydration, as well as 30 min and 24 h of rehydration. CIEDE2000 color parameters were used to calculate color difference. The data were analyzed for color changes over time by repeated-measures analysis of variance (ANOVA), and the Bonferroni-Tukey test was used for post-ANOVA comparisons (P < .05). RESULTS: After 30 min of dehydration, all the tested teeth were above the perceptibility threshold (ΔE00 = 0.8), and 85% of the teeth were above the acceptability threshold (ΔE00 = 1.8). After 30 min of rehydration, 78.3% of the tested teeth were above the perceptibility threshold, and 31.6% of the teeth were above the acceptability threshold. After 24 h of rehydration, 99.2% of the teeth were below the acceptability threshold, and 90% of the values were below the perceptibility threshold. CONCLUSIONS: Thirty-minute tooth dehydration can result in a clinically significant color change. After a 24-h rehydration period, reliable color assessment can be performed. CLINICAL SIGNIFICANCE: Tooth dehydration causes significant color change, thus assessment of final color or clinical success should be considered after tooth rehydration for esthetic restorations and tooth bleaching.

The effect of the different restorations on fracture resistance of root-filled premolars.

BACKGROUND: The study investigated the fracture resistance of root-filled maxillary premolars with class II cavities restored by different restorations. METHODS: A total of 55 intact maxillary premolar teeth were included (n = 11). G1 as positive control group, 44 teeth underwent root canal treatment, and MOD cavities were prepared. (G2) no restoration, (G3) direct composite restoration, (G4) direct composite strengthened with buccal to lingual pre-impregnated glass-fibers and (G5) ceramic inlay restoration. After thermocycling, fracture resistance test was performed and fracture type was recorded. Data were analyzed with one-way ANOVA and Chisquare test. RESULTS: The mean fracture resistance was as follows: G1 had the highest fracture resistance, G2 had the lowest (p < 0.05). There were no significant differences between the fracture resistance values of the groups that underwent different restorations (G3, G4, G5) (p > 0.05). According to fracture type, the groups showed similar results (p > 0.05). A significant level of unrestorable fracture was detected in G5 (ceramic inlay) (p < 0.05). CONCLUSIONS: All of the restoration techniques investigated herein increased the fracture strength of teeth; however, all of these values were lower than the fracture resistance of intact teeth. There were no significant differences between the fracture resistance values of the groups that underwent different restorations.

Effects of Novel Finishing and Polishing Systems on Surface Roughness and Morphology of Nanocomposites.

OBJECTIVES: The purpose of this in vitro study was to evaluate the effects of different finishing/polishing techniques on the surface roughness of nanocomposites after thermocycling aging. MATERIALS AND METHODS: Five contemporary resin-based composites (Clearfil Majesty ES-2, Filtek Z550, Estelite∑Quick, Zenit, Filtek Z250) were tested. For each resin-based composite, 50 disc-shaped specimens were prepared and groups were divided into five subgroups according to the finishing/polishing methods (n = 10): control, finishing/polishing brush, finishing/polishing disc, and two different finishing/polishing wheels. Before and after aging, the surface roughness of specimens was measured. For each treatment method two samples were analyzed using a scanning electron microscope. Two-way analysis of variance and paired samples t-tests were used to evaluate the data and the means were compared by Bonferroni tests (p ≤ 0.05). RESULTS: Before aging, the Filtek Z250 resin with the Mylar strip group showed the lowest surface roughness (Ra) value (0.13 ± 0.03 µm, p < 0.05) and the Clearfil Majesty ES 2 resin with Occlubrush finishing/polishing system showed the highest (0.7 ± 0.13 µm, p < 0.05). After aging, the Clearfil Majesty ES 2 resin with the Mylar strip group showed the highest surface roughness (Ra) value (0.96 ± 0.4 µm) and the Clearfil Majesty ES 2 resin with the Sof-Lex aluminum oxide disc finishing/polishing system showed the lowest surface roughness (Ra) value (0.25 ± 0.06 µm, p < 0.05). CONCLUSIONS: Composite type and finishing/polishing method significantly affected the surface roughness of composites before and after thermocycling aging. CLINICAL SIGNIFICANCE: There were significant interactions between finishing/polishing methods and composite types for surface roughness. The results give clinicians some flexibility in choosing appropriate finishing/polishing techniques for each resin composite material. (J Esthet Restor Dent 28:247-261, 2016).

In vitro evaluation of temperature rise during different post space preparations.

OBJECTIVE: The aim of this study was to evaluate temperature alterations on the outer root surface during post space preparation with six different post drills by using an infrared thermometer. MATERIALS AND METHODS: Sixty extracted single-rooted human mandibular incisor teeth were used. After root canal obturation, the specimens were divided into six groups (n = 10). During post space preparation, the temperature rises were measured in the middle third of the roots using a noncontact infrared thermometer with a sensitivity of 0.1°C. The temperature data were transferred from the thermometer to the computer and were observed graphically. RESULTS: The maximum temperature rise was observed in Snowpost 2 (29.95 ± 10.2°C) (P < 0.001), but there were no significant differences among Snowpost 2 (29.95 ± 10.2°C), Snowpost 1 (24.6 ± 8.0°C), and Relyx 2 (17.68 ± 9.1°C) (P > 0.05). CONCLUSIONS: Although water coolant used, the critical temperature rise was observed on the outer root surface in all post drill systems.

In vivo performance of two devices for occlusal caries detection.

OBJECTIVE: The aim of this in vivo study was to compare the performance of light-emitting diode (LED)- and laser fluorescence (LF)-based devices with that of visual inspection (VI) in the diagnosis of occlusal caries. METHODS: A total of 156 occlusal surfaces were investigated. Each occlusal surface was assessed with LED- and LF-based devices after a VI was performed. Pit and fissure opening was applied to the occlusal surfaces in which opacity or discoloration was distinctly visible after airdrying. The inter-examiner reliability of caries examination was assessed using the weighted κ statistics. The sensitivity, specificity, and accuracy of occlusal caries diagnosis using these methods were calculated according to the appropriate thresholds. RESULTS: Acceptable inter-examiner agreement was found for the LED- and LF-based devices and VI (κ=0.61, κ=0.76, and κ=0.87, respectively). Higher specificity values were achieved at a T2 threshold for the LF-based device (0.76 and 0.80) and at a T1 threshold for the LED-based readings (0.60 and 0.62) and VI (0.90 and 0.93) for both observers. With regard to VI, higher sensitivity values were found at both thresholds for the two observers in comparing the three caries detection methods (0.98 at T1 and 0.96 at T2). The accuracy values for T1 were higher than those for the T2 values, for all three caries detection methods. CONCLUSIONS: Caries lesions may be detected more accurately than clinically sound areas by both caries detection devices.

Assessment of changes in color and color parameters of light-cured composite resin after alternative polymerization methods.

OBJECTIVE: To examine the amount of change in color and color parameters of a composite resin (Filtek P60) polymerized by five different polymerization methods. METHODS: A Teflon mold (6mm in diameter, 2mm in height) was used to prepare the composite resin discs (n=10). G1: Polymerization with inlay oven; G2: Polymerization with HQTH and autoclave; G3: Polymerization with LED and autoclave; G4: Polymerization with HQTH; G5: Polymerization with LED. Colorimetric values of the specimens before and after polymerization were measured using a spectrophotometer. The CIE L*a*b color system was used for the determination of color difference. Analysis of variance (ANOVA) was used to analyze the data for significant differences. Tukey's HSD test and paired two-tailed tests were used to perform multiple comparisons (α=.05). RESULTS: There were no significant differences in total color change (ΔE*ab) among the polymerization groups (P>.05). However, the lowest color change (ΔE*ab) value was 3.3 in LED and autoclave; the highest color change (ΔE*ab) value was 4.6 in HQTH. For all groups, CIE L*, C*ab and a*values decreased after polymerization (P<.05). The highest Δb* and ΔC*ab values were observed in specimens polymerized in an inlay oven (P<.05). CONCLUSIONS: Composite resin material showed color changes above the clinically accepted value in all study groups (ΔE*ab⩾3.3). All specimens became darker during investigation (ΔL*< 0). Specimens polymerized with inlay oven presented the highest Δb* values which means less yellow color in specimens.

Antimicrobial efficiency of photodynamic therapy with different irradiation durations.

OBJECTIVE: This study aimed to evaluate the antimicrobial efficiency of PDT and the effect of different irradiation durations on the antimicrobial efficiency of PDT. MATERIALS AND METHODS: Sixty freshly extracted human teeth with a single root were decoronated and distributed into five groups. The control group received no treatment. Group 1 was treated with a 5% sodium hypochlorite (NaOCl) solution. Groups 2, 3, and 4 were treated with methylene-blue photosensitizer and 660-nm diode laser irradiation for 1, 2, and 4 min, respectively. The root canals were instrumented and irrigated with NaOCl, ethylenediamine-tetraacetic acid, and a saline solution, followed by autoclaving. All the roots were inoculated with an Enterococcus faecalis suspension and brain heart infusion broth and stored for 21 days to allow biofilm formation. Microbiological data on microorganism load were collected before and after the disinfection procedures and analyzed with the Wilcoxon ranged test, the Kruskal-Wallis test, and the Dunn's test. RESULTS: The microorganism load in the control group increased. The lowest reduction in the microorganism load was observed in the 1-min irradiation group (Group 2 = 99.8%), which was very close to the results of the other experimental groups (99.9%). There were no significant differences among the groups. CONCLUSIONS: PDT is as effective as conventional 5% NaOCl irrigation with regard to antimicrobial efficiency against Enterococcus faecalis.

Inadequate shear bond strengths of self-etch, self-adhesive systems for secure orthodontic bonding.

This study evaluated the shear bond strength (SBS) of a traditional orthodontic bracket bonding agent (Transbond XT) against two self-etch, self-adhesive systems (Maxcem Elite and Vertise Flow). Sixty premolar teeth and sixty brackets were randomly and equally divided into five groups: Transbond XT (TXT) as the control, Maxcem Elite (ME) without etching, ME with etching (ME/ Etch), Vertise Flow (VF) without etching, and VF with etching (VF/Etch). Respective SBS results of the five groups were 9.86±3.20, 4.67±2.94, 7.82±2.56, 2.55±0.77, and 7.89±1.17 MPa. SBS values of the new self-etch adhesive systems were significantly lower than the traditional etch-and-rinse control (p<0.005). However, no significant differences were found between TXT and the self-adhesives applied with etching (p>0.005). After debonding, ARI scores "0" and "1" were predominant in non-etched ME and VF groups. It was concluded that new self-etch, self-adhesive bonding systems require additional phosphoric acid application to achieve comparable SBS values as the traditional orthodontic bonding agent.

Effect of cavity preparation techniques and different preheating procedures on microleakage of class V resin restorations.

OBJECTIVES: This study aimed to evaluate the extent of microleakage of a single type of composite resin (Clearfil Majesty Posterior, Kuraray, Osaka, Japan) following different preheating procedures in Class V cavities prepared with a diamond bur or Er:YAG (erbium: yttrium aluminum garnet) laser. METHODS: The study randomly divided 72 permanent molar teeth divided into eight groups (n = 9): G1: Diamond bur-unheated composite resin (room temperature-24 ºC); G2: Diamond bur-composite preheated to 37 ºC; G3: Diamond bur-composite preheated to 54 ºC; G4: Diamond bur-composite preheated to 68 ºC; G5: Er:YAG laser-unheated composite resin (room temperature-24 ºC); G6: Er:YAG laser-composite preheated to 37 ºC; G7: Er:YAG laser-composite preheated to 54 ºC; and G8: Er:YAG laser-composite preheated to 68 ºC. The specimens were subjected to a thermal cycling regimen of 5000 cycles between 5 and 55 ºC; then they were immersed in a solution of 0.5% basic fuchsin dye for 24 hours. The dyed specimens were sectioned in the buccolingual direction and dye penetration was scored in a blinded manner using a five-point qualitative scale. Microleakage scores were analyzed with the Kruskall-Wallis, Mann-Whitney U, and Wilcoxon tests. RESULTS: There were no statistically significant differences between the microleakages of composite applied to cavities prepared by either the Er:YAG laser or diamond bur (P>.05). Statistical analysis revealed significant differences between the enamel and dentin in all restorations (P<.001). However, there were no significant differences among the preheated groups (P>.05). CONCLUSIONS: For all groups, microleakage values were higher at gingival margins than at occlusal margins. The use of the Er:YAG laser at different preheating procedures did not influence the marginal sealing in Class V composite resin restorations.

Conservative approach for restoring posterior missing tooth with fiber reinforcement materials: four clinical reports.

Adhesively luted, fiber-reinforced, composite-inlay, retained fixed-partial dentures can be a clinical alternative for the replacement of missing posterior teeth in selective situations. This type of restoration allows for satisfactory esthetics and reduced tooth preparation compared to a conventional, fixed-partial denture. This clinical report describes the use of a fiber-reinforced, composite-inlay, retained fixed-partial denture as a conservative alternative for the replacement of missing posterior teeth.

Temperature increase beneath etched dentin discs during composite polymerization.

OBJECTIVE: The purpose of this in vitro study was to measure the temperature increase during the polymerization of a composite resin beneath acid-etched or laser-etched dentin discs. BACKGROUND DATA: The irradiation of dentin with an Er:YAG laser may have a positive effect on the thermal conductivity of dentin. This technique has not been studied extensively. MATERIALS AND METHODS: Forty dentin discs (5 mm in diameter and 0.5 or 1 mm in height) were prepared from extracted permanent third molars. These dentin discs were etched with 20% orthophosphoric acid or an Er:YAG laser, and were then placed on an apparatus developed to measure temperature increases. The composite resin was polymerized with a high-intensity quartz tungsten halogen (HQTH) or light-emitting diode unit (LED). The temperature increase was measured under the dentin disc with a J-type thermocouple wire that was connected to a data logger. Five measurements were made for each dentin disc, curing unit, and etching system combination. Differences between the initial and the highest temperature readings were taken, and the five calculated temperature changes were averaged to determine the value of the temperature increase. Statistical analysis was performed with a three-way ANOVA and Tukey HSD tests at a 0.05 level of significance. Further SEM examinations were performed. RESULTS: The temperature increase values varied significantly, depending on etching systems (p < 0.05), dentin thicknesses (p < 0.05), and curing units (p < 0.05). Temperature increases measured beneath laser-etched discs were significantly higher than those for acid-etched dentin discs (p < 0.05). The HQTH unit induced significantly higher temperature increases than the LED unit (p < 0.05). The LED unit induced the lowest temperature change (5.2°C) in the 1-mm, acid-etched dentin group. The HQTH unit induced the highest temperature change (10.4°C) for the 0.5-mm, laser-etched dentin group. CONCLUSION: The risk of heat-induced pulpal damage should be taken into consideration during the polymerization of composite resin after laser etching when the dentin thickness is less than 0.5 mm.

Age estimation for dental patients using orthopantomographs.

OBJECTIVES: The aim of this study was to conduct age estimates for dental patients using orthopantomographs (OPGs). The OPGs were selected by an independent author with respect to criteria and evaluated by two independent dentists. The results were compared to chronologic ages. The reliability of the estimates, concurrently made by the two independent dentists using OPGs, was also evaluated. METHODS: In this retrospective study, the OPGs of 238 Turkish individuals of known chronological age, ranging from 1 to 60 years, were measured. Patients were then classified. Radiographs were evaluated by two independent dentists and age estimation was achieved according to the decades. RESULTS: The truest age estimates made by the dentists were in the 1-10 years age range (89.6%), the most inaccurate age estimates were in the 41-50 years age range (41.7%). Results indicate that the accuracy of age estimation diminishes with age. CONCLUSIONS: Despite the variations related to the practitioners, in this study, there were no significant differences in age estimations between the two participant practitioners. Age estimation through evaluating OPGs was the most accurate in the first decade and the least in fourth decade. It can be concluded that OPGs are not adequate for accurate age estimation.