Effect of desensitizing agents on the resin bond strength to sound dentin.

This study aimed to evaluate the effect of dentin hypersensitivity treatments on immediate and long-term shear bond strength (SBS) of composite restorations. Ninety non-carious extracted human molars were cut to expose dentin, which was embedded in acrylic resin, and randomly divided into three groups (n = 30/group) according to surface treatment: 1) no treatment (C and C*; control); 2) silver diamine fluoride with potassium iodide (SDF/KI and SDF/KI*; Riva Star); and 3) nano-hydroxyapatite (nHAp and nHAp*; PrevDent). The specimens were etched through the etch-and-rinse technique, followed by universal adhesive application and resin composite cylinders (2.38 mm in diameter × 3.5 mm high). The SBS was tested immediately (24 h after the restoration) and after thermocycling (*) (5000 cycles, 5 °C to 55 °C) at a 0.5 mm/min crosshead speed using a universal testing machine. A stereomicroscope was used to evaluate the mode of failure, and representative scanning electron microscopy (SEM) images were also acquired. Data normality was verified, and two-way ANOVA and Tukey's post hoc tests were performed for multiple comparisons (α = 0.05). The control group presented the highest SBS (27.10 MPa), while SDF/KI* had the lowest values (6.87 MPa). nHAp-based desensitizer exhibited higher SBS than SDF/KI for both immediate (22.6 MPa) and thermocycled (19.03 MPa) conditions. No intragroup difference was evidenced between immediate and thermocycled samples for any group. Most specimens for the C and nHAp groups presented mixed failure, while the SDF/KI groups presented comparable adhesive and mixed failures. The SBS of adhesive restorations after the application of desensitizing agents is material dependent, where SDF/KI reduces SBS values below the acceptable minimum bond strength, while the nHAp application meets the minimally required bond strength.

Translucency and flexural strength of translucent zirconia ceramics.

STATEMENT OF PROBLEM: Translucent zirconias have been developed with better esthetics than high-strength zirconias by reducing opacity. However, studies on their translucency and strength are sparse. PURPOSE: The purpose of this in vitro study was to compare the relationship between translucency and biaxial flexural strength of recently developed high-translucency zirconia, high-strength zirconia, and lithium disilicate ceramics. MATERIAL AND METHODS: Disks (n=12) were fabricated for 5 ceramic materials: high-strength zirconia (BruxZir 16 shaded), translucent zirconia (BruxZir Anterior shaded, Katana UTML, Katana STML), and lithium disilicate (IPS e.max, Press HT, and LT). A standard tessellation language (STL) file was designed, and the specimen milled, finished, and glazed according to manufacturer's instructions for each material. The translucency parameter was calculated against black and white backgrounds and white and stump shade with ND4 background by using a spectrophotometer. Biaxial flexural strength was calculated by using the 3-ball test. The load was applied at a crosshead speed of 0.5 mm/min with a 49-N load cell until failure occurred. Translucency parameter and biaxial flexural strength data were analyzed with 1-way analysis of variance (ANOVA). A Tukey honest significant difference multiple comparison test was used to determine significant differences (α=.05). RESULTS: The IPS e.max HT was more translucent against both backgrounds (32.85 for black/white and 15.34 for white/stump), while BruxZir 16 was the least translucent (19.78 for B/W and 8.83 for W/S). All groups tested differed in translucency (P<.001) except for BruxZir Anterior and Katana STML, which were not significantly different (P=.052). For biaxial flexural strength, BruxZir 16 had the highest strength (995.44 MPa) and e.max HT, the lowest (186.75 MPa). No significant differences were found between BruxZir anterior and Katana STML, Katana UTML and IPS e.max LT, or IPS e.max LT and IPS e.max HT (P>.05). Translucency parameter values using both backgrounds were strongly correlated (r=0.99). However, biaxial flexural strength values were inversely related to translucency parameter values when using black/white and white/stump shade but with high correlation (r=-0.777 and -0.756 respectively). CONCLUSIONS: Lithium disilicate was the most translucent and yet the weakest material, whereas high-strength zirconia was the most opaque ceramic and the strongest. Katana UTML had the highest translucency but was weakest among translucent and high-strength zirconia materials. Overall, translucency was negatively correlated with biaxial flexural strength.

Evaluation of micro-CT in the assessment of microleakage under bulk fill composite restorations.

PURPOSE: To evaluate microleakage measurements using micro-CT in comparison to dye tracers in Class 2 bulk-fill composite restorations with two adhesive techniques. METHODS: 60 sound molars were prepared with Class 2 cavities having cervical margins in enamel (mesial) and in dentin (distal) and restored with Filtek Bulk Fill, using either a self-etch or total-etch technique. All teeth were thermo-cycled between 5°C and 55°C for 800 cycles and randomly exposed to three tracer dyes: 2% methylene blue, 0.5% basic fuchsin or 50% silver nitrate solutions. Teeth were sectioned mesial-distal and depth of tracer penetration was measured as a ratio of dye penetration from the cavosurface divided by total depth of the cervical floor. The silver nitrate subgroup was micro-CT scanned prior to sectioning, evaluated in 3D serial sections, and calculated volumetrically. RESULTS: Analysis of ratios for dye tracer penetration showed significantly lower values for methylene blue (0.120). Micro-CT values calculated in 3D as volume (mm³) were significantly greater in enamel for self-etch (0.060) compared to total-etch (0.020). Micro-CT volumetric analysis showed better discrimination with significantly greater leakage in enamel margins using the self-etch adhesive. CLINICAL SIGNIFICANCE: Based on this in vitro study of microleakage, micro-CT volumetric evaluation in serial digital sections improves discrimination and represents a more reliable estimate of true microleakage. In vitro study of microleakage is most useful in comparing adhesive products, but clinical application of the data is questionable.

Color match using instrumental and visual methods for single, group, and multi-shade composite resins.

OBJECTIVE: To evaluate the shade match of three composite resin restorative materials to bi-layered acrylic teeth instrumentally and visually. MATERIALS AND METHODS: Three composite materials-Omnichroma [OM], Tetric EvoCeram [TE], and TPH Spectra ST [TS] were placed into occlusal preparations (5 mm diameter, 2 mm depth) on 15 bi-layered acrylic teeth per each shade A2, B1, B2, C2, and D3. The composites were placed in a single increment and cured using Bluephase G2 light. The L*, a*, and b* readings were obtained using VITA Easyshade V for the teeth and restorations; mean ΔE00 values were calculated and assessed using two-way analysis of variance with a test of simple effects with multiple comparisons for significance (P < .05). Three teeth were restored to anatomical form with each of the composites for the five shades and were subjectively graded by 30 evaluators as 1-best match, 2-intermediate, and 3-poorest match. RESULTS: In the instrumental evaluation, OM and TS showed lower ∆E00 values for lighter shades, whereas TE showed lower and similar ∆E00 values for all shades. In the visual evaluation, TE exhibited the best shade match for darker shades C2 and D3. OM and TS matched better with lighter shades. CONCLUSION: Shade matching is composite and shade-dependent. Overall, TE matched the multiple shades better than the other two materials. CLINICAL SIGNIFICANCE: Single and group shade composites displayed shade matching ability inferior to a multi-shade composite material, which may limit their use in highly esthetic clinical situations.

Efficacy of calcium hydroxide and resin-modified calcium silicate as pulp-capping materials: a retrospective study.

The aim of this study was to compare the clinical success rates of light-cured, resin-modified calcium silicate (TheraCal LC) and calcium hydroxide (Dycal) as pulp-capping materials in permanent teeth. In this retrospective electronic record review of patients treated in the years 2012 through 2015, the postoperative data of 120 patients (n = 60 per material) were collected. In these 2 groups, 69 teeth were treated with calcium hydroxide (29 in men, 40 in women) and 79 with calcium silicate (37 in men, 42 in women). The following data were recorded: treated tooth; patient age and sex; reason for treatment; direct or indirect pulp cap; date of treatment; date of most recent dental appointment; and treatment outcome. The selected patients met the following inclusion criteria: They had received either a direct or an indirect pulp cap in an anterior or posterior tooth after excavation of deep caries as part of a routine restorative procedure using either amalgam or composite resin; and they had returned to the clinic for other dental care at least 3 months after the pulp-capping treatment. Patients were excluded from the study if they reported symptoms of irreversible pulpitis or chronic tooth pain before the restorative treatment was started. The treatment outcome was considered clinically successful if the tooth was still present and asymptomatic at the appointments following the procedure. The outcome was considered unsuccessful if the tooth was extracted due to symptoms or if endodontic treatment had been performed postoperatively. There was no statistically significant difference between the clinical success rates of calcium silicate (85.5%) and calcium hydroxide (84.8%), according to the Fisher exact test (P < 0.05). Neither the patient's sex nor the tooth location affected the outcome. Within the limitations of this retrospective clinical study, it may be concluded that TheraCal LC calcium silicate can be considered equivalent inefficacy to calcium hydroxide for both direct and indirect pulp capping. A prospective clinical study with a larger sample size is needed to confirm these findings.

Effect of Silver Diamine Fluoride Treatment on Microbial Profiles of Plaque Biofilms from Root/Cervical Caries Lesions.

PURPOSE: To assess the effect of silver diamine fluoride (SDF) on microbial profiles present in plaque from root/cervical carious lesions, and its association with caries lesion arrest. MATERIALS AND METHODS: Twenty patients with at least one soft cavitated root/cervical carious lesion were included. One lesion/patient was randomly selected and treated with 38% SDF. Supragingival plaque samples were harvested at preintervention and 1 month postintervention. Using an MiSeq platform, 16S rDNA sequencing of the V3-V4 regions was used to determine bacterial profiles. Clinical evaluation of lesion hardness was used to evaluate arrest. t tests, principal component analysis (PCA), multidimensional scaling (MDS), and generalized linear models (GLMs) tests were used for statistical comparisons. RESULTS: From a total of 40 plaque samples, 468 probe targets were observed. Although 60% of lesions became hard postintervention, PCA and MDS tests showed no distinct pre- and postintervention groups. In addition, pre- and postintervention differences in diversity (Shannon index) of microbial profiles between patients with and without lesion arrest were not statistically different. A likelihood ratio test for pre- versus postintervention differences within patients, i.e., adjusting for differences between patients using negative binomial GLMs, showed 17 bacterial taxa with significant differences (FDR <0.05). CONCLUSION: Although 60% of lesions hardened after SDF treatment, this was not directly due to either overall statistically significant differences in microbial profiles or differences in microbial diversity. Nevertheless, there was a trend with some acid-producing species in that their relative abundance was reduced postintervention. The negative binomial GLMs showed 17 bacterial taxa that were significantly different after SDF treatment.

Retrospective evaluation of the clinical performance and longevity of porcelain laminate veneers 7 to 14 years after cementation.

STATEMENT OF PROBLEM: Studies on the long-term clinical assessment and longevity of porcelain laminate veneers (PLVs) are lacking. PURPOSE: The purpose of this clinical study was to assess the clinical performance and longevity of PLVs after 7 to 14 years of clinical service. MATERIAL AND METHODS: Patients with PLVs placed 7 to 14 years earlier were recalled for clinical evaluation. At the recall visit, clinical parameters such as margin integrity, margin discoloration, porcelain surface, anatomic form, and secondary caries were evaluated according to the Ryge criteria. Standardized photographs of veneers were made for each participant. Data were tabulated for all descriptive criteria and analyzed statistically. The Cohen Kappa assessment was carried out to determine interrater agreement, the Kaplan-Meier survival analysis for survival probability, and the Cox regression for significance between the arches. RESULTS: One hundred and fourteen veneers (83 maxillary and 31 mandibular) were evaluated in 26 participants, including 19 women restored with 87 veneers and 7 men restored with 27 veneers. Distribution of the veneers included 37 central incisors, 41 laterals, and 36 canines. The Alfa ratings for the veneers were as follows: porcelain surface (85%), anatomic form (87%), and secondary caries (96%). For margin integrity, 37% rated Alfa, 60% Bravo, and 3% Charlie. For margin discoloration, 56% rated Alfa and 44% Bravo. The overall Cohen Kappa interrater agreement was 0.7023 with an agreement rate of 88.3%. Clinical deficiencies included fracture rate of 4.35% (n=5); porcelain chipping 5.26% (n=6); caries 4% (n=4); debonding 2% (n=2); crack/craze lines 5.26% (n=6); loss of vitality 2% (n=2); and replaced veneers 4.38% (n=5). The main reason for failure was porcelain fracture. The survival rate for the veneers was 98%. The Kaplan-Meier success probability was 0.976 at 7 years and 0.882 at 14 years. CONCLUSIONS: Within the limitations of this clinical study, PLVs exhibited an estimated survival probability of 0.976 over 7 years and 0.882 over 14 years, a high survival rate of 98%, and a low failure rate of 4.38%.

The effects of different irrigation solutions on the bond strength of cemented fiber posts.

OBJECTIVE: To study effect of root canal irrigant solutions on the bond strength of cemented fiber posts, and resin cement-tags in root canal dentin. MATERIALS AND METHODS: Fifty-two human single-rooted anterior teeth were selected and stored in 1% sodium azide. Crowns were sectioned 2 mm incisal to the cemento enamel junction with diamond bur at high speed under water-cooling. After standard root canal treatment to tested teeth, they were randomly assigned into four groups (n=13) corresponding to the endodontic irrigant solution that was used during post space preparation. The treatment groups were: Group 1: 6.15% sodium hypochlorite; Group 2: 17% EDTA; Group 3: 6.15% NaOCl +17% EDTA; Group 4: 6.15% NaOCl +0.12% chlorhexidine solution. Parallel-sided fiber posts were used for all specimens. Samples were embedded in a cylindrical PVC mounting jig to facilitate perpendicular sectioning. With low speed diamond saw, cervical and apical specimens from each tooth were obtained and subjected to push-out test using universal testing machine. SEM was used to examine the root-canal dentin surface. RESULTS: Statistical analysis revealed significant difference among the groups at P<0.05. Group 2 treated with EDTA, had the highest bond strength; 18.63±2.85 MPa in cervical specimens and 13.49±3.67 MPa in apical specimens. The cervical specimens of Groups 2 and 3 were significantly different than the apical specimens in the same group. Adhesive failure between cement and dentin was the main failure mode observed in all groups. Groups irrigated with EDTA showed cleaner dentin surface and better resin tag formation, while groups treated with NaOCl showed less resin tag formation and insufficient smear layer removal. CONCLUSION: NaOCl had adverse effect on bond strength of self-adhesive resin cement to radicular dentin. EDTA irrigant solution produced higher bond strength and was more effective in removing smear layer than NaOCl.

Fluoride Levels in Unstimulated Whole Saliva following Clinical Application of Different 5% NaF Varnishes.

The aim of this study was to evaluate the fluoride release from differently formulated 5% NaF varnishes into unstimulated whole saliva in vivo. The fluoride concentration in unstimulated whole saliva was determined after the application of 3 different 5% NaF varnishes (5% NaF, 5% NaF + tricalcium phosphate [TCP], and 5% NaF + amorphous calcium phosphate [ACP]) or a placebo. Fifteen subjects were recruited and enrolled following Institutional Review Board approval based upon the inclusion/exclusion criteria of this study. A cross-over study design was used for the application of either one of the 5% NaF varnishes or a placebo. Unstimulated whole saliva was collected at baseline and at 1, 4, 6, 26, and 50 h following application and analyzed for supernatant ionic fluoride and whole fluoride by microdiffusion. Linear mixed-effects models (5% significance level) were used to determine the effects of varnish and time on the salivary fluoride concentration. The highest amount of fluoride in saliva was found 1 h after application of the fluoride varnishes, with no significant differences among the treatment varnishes with respect to whole fluoride but with lower levels for 5% NaF + ACP in the saliva supernatant. Salivary fluoride levels at 4, 6, and 26 h decreased at each time point and were generally significantly higher for 5% NaF and 5% NaF + TCP. After 50 h, fluoride levels in saliva for all groups were at or below baseline levels. In conclusion, the formulation of other ingredients in fluoride varnishes can affect the fluoride concentration in saliva. The reasons for this phenomenon warrant further investigation since it might affect efficacy of the treatment. This trial is registered at ClinicalTrials.gov (NCT01629290).

Effect of Silver Diamine Fluoride (SDF) Application on Microtensile Bonding Strength of Dentin in Primary Teeth.

PURPOSE: The purpose of this study was to investigate the effect of silver diamine fluoride (SDF) on the microtensile bonding strength of resin composite to the dentin of primary molars. METHODS: Twelve primary molars were randomly assigned to either the control or the SDF groups, and microtensile bonding strength (mTBS) was measured. The surface morphology was evaluated by visual inspection and scanning electron microscopy (SEM) imaging. RESULTS: The mean±(SD) value of mTBS in the control and SDF group was 162.09±81.08 and 139.85±88.53, respectively (P=0.402). SEM images showed that, in the control group, the majority of the fractures occurred at the adhesive-dentin conjunction, while in the SDF group failure mostly occurred within the adhesives. CONCLUSIONS: Pretreating dentin with 38 percent silver diamine fluoride does not affect the bonding strength of composite resin to dentin. The fracture patterns observed suggest that bonding strength might be stronger between the adhesive and the SDF-applied dentin. Our data suggest that SDF can be used as a dentin pretreatment prior to resin restoration potentially contributing to secondary caries prevention in primary teeth.

The effect of antacid on salivary pH in patients with and without dental erosion after multiple acid challenges.

PURPOSE: To evaluate the effect of antacid swish in the salivary pH values and to monitor the pH changes in subjects with and without dental erosion after multiple acid challenge tests. METHODS: 20 subjects with tooth erosion were matched in age and gender with 20 healthy controls according to specific inclusion/exclusion criteria. Baseline measures were taken of salivary pH, buffering capacity and salivary flow rate using the Saliva Check System. Subjects swished with Diet Pepsi three times at 10-minute intervals. Changes in pH were monitored using a digital pH meter at 0-, 5-, and 10- minute intervals and at every 5 minutes after the third swish until pH resumed baseline value or 45 minutes relapse. Swishing regimen was repeated on a second visit, followed by swishing with sugar-free liquid antacid (Mylanta Supreme). Recovery times were also recorded. Data was analyzed using independent t-tests, repeated measures ANOVA, and Fisher's exact test (α= 0.05). RESULTS: Baseline buffering capacity and flow rate were not significantly different between groups (P= 0.542; P= 0.2831, respectively). Baseline salivary pH values were similar between groups (P= 0.721). No significant differences in salivary pH values were found between erosion and non-erosion groups in response to multiple acid challenges (P= 0.695) or antacid neutralization (P= 0.861). Analysis of salivary pH recovery time revealed no significant differences between groups after acid challenges (P= 0.091) or after the use of antacid (P= 0.118). There was a highly significant difference in the survival curves of the two groups on Day 2, with the non-erosion group resolving significantly faster than the erosion group (P= 0.0086).

Physical Properties of an Ag-Doped Bioactive Flowable Composite Resin.

The aim of this work was to study the physical and antibacterial properties of a flowable resin composite incorporating a sol-gel derived silver doped bioactive glass (Ag-BGCOMP). The depth of the cure was calculated by measuring the surface micro-hardness for the top and bottom surfaces. The volumetric polymerization shrinkage was measured by recording the linear shrinkage as change in length, while the biaxial flexural strength was studied measuring the load at failure. The antibacterial properties of the samples were tested against Streptococcus mutans (S. mutans) and Lactobacillus casei (L. casei). The measured values were slightly decreased for all tested physical properties compared to those of control group (flowable resin composite without Ag-BG), however enhanced bacteria inhibition was observed for Ag-BGCOMP. Ag-BGCOMP could find an application in low stress-bearing areas as well as in small cavity preparations to decrease secondary caries. This work provides a good foundation for future studies on evaluating the effects of Ag-BG addition into packable composites for applications in larger cavity preparations where enhanced mechanical properties are needed.

Fixed maxillary and mandibular zirconia implant frameworks milled with anatomically contoured molars: a clinical report.

Retrospective studies on restoring the patients with complete edentulism have reported a variety of complications, including the excessive wear and fracture of the acrylic resin teeth. Approaches to slow the process of wear include the use of porcelain teeth or altering the occlusal surface of acrylic resin teeth with amalgam or gold. Two 1-piece fixed zirconia implant frameworks masked with gingival porcelain and stained anatomically contoured first and second molars and individual ceramic crowns were used to restore both arches to optimum function and esthetics. This clinical report describes the steps for one method of providing the fixed prosthetic needs of the patients who is edentulous.

Influence of post material and length on endodontically treated incisors: an in vitro and finite element study.

STATEMENT OF PROBLEM: Cast posts require sufficient length for prosthesis retention and root strength. For prefabricated metal and fiber posts, the effects of different post lengths on the strength and internal stress of the surrounding root need evaluation. PURPOSE: The purpose of this study was to examine, using both experimental and finite element (FE) approaches, the influence of post material and length on the mechanical response of endodontically treated teeth. MATERIAL AND METHODS: Sixty extracted incisors were endodontically treated and then restored with 1 of 3 prefabricated posts: stainless steel (SS), carbon fiber (CF), and glass fiber (GF), with intraradicular lengths of either 5 or 10 mm (n=10). After composite resin core and crown restorations, these teeth were thermal cycled and then loaded to fracture in an oblique direction. Statistical analysis was performed for the effects of post material and length on failure loads using 2-way ANOVA (α=.05). In addition, corresponding FE models of an incisor restored with a post were developed to examine mechanical responses. The simulated tooth was loaded with a 100-N oblique force to analyze the stress in the root dentin. RESULTS: The SS/5 mm and all fiber post groups presented no statistical differences, with mean (SD) fracture loads of 1247 to 1339 (53 to 121) N. The SS/10 mm group exhibited a lower fracture load, 973 (115) N, and a higher incidence of unfavorable root fracture (P<.05). The FE analysis showed high stress around the apical end of the long SS post, while stress was concentrated around the crown margins in the fiber post groups. CONCLUSIONS: Both long and short fiber posts provided root fracture resistance comparable to that of SS posts. For metal posts, extending the post length does not effectively prevent root fracture in restored teeth.

Effect of different surface treatments on the shear and flexural re-bond strengths of a micro-hybrid composite.

AIM: This study compared the shear bond strength (SBS) and flexural strength (FS) of repaired interfaces using three techniques of surface preparation and repair of a micro-hybrid composite. METHODS AND MATERIALS: Composite specimens for SBS tests (n=36: diameter=8 mm, thickness=3 mm) for repair were shaped in a metal mold, visible-light cured, and embedded in dental stone. Composite specimens for FS tests (n=36: 2 mm x 2 mm x 12.5 mm) for repair were shaped in a silicone mold. Three different methods of surface preparation were evaluated: Group A (control) specimens were treated by etching with 35% phosphoric acid; Group B specimens were air-abraded with 50 microm aluminum oxide at 100 psi; and Group C specimens received two parallel, 1 mm-deep grooves using a (1/4)-round bur before being treated by etching with 35% phosphoric acid. After surface treatment, a bonding agent was placed on each specimen, which was then light cured. Repairs were accomplished by adding more composite to the SBS or FS specimens. Specimens were thermocycled 500 times between 5 degrees C and 55 degrees C with 30-second dwell times. All specimens were tested by loading to failure at a rate of 0.5 mm/min using an Instron Universal Testing Machine. RESULTS: Mean SBSs in MPa were: Group A=24.5 +4.4, Group B=28.5 +4.3, and Group C=27.0 +2.8. Mean FSs (MPa) were: Group A=60.5 +9.9, Group B=73.9 +13.2 and Group C=81.3 +14.3. For the FS tests, Group B and C were significantly different than Group A, but Group C was not significantly different than group B. For the SBS test, Group B was significantly different than Group A, but Group C was not significantly different. CONCLUSION: Acid-etching alone was not very effective in producing well-bonded composite repairs (only 55% of the FS of normal micro-hybrid composite). Mechanical retention was more effective (SBS, FS) than acid-etching and as effective (SBS) or more effective (FS) than air-abrasion (p<0.05) for repaired composite specimens. CLINICAL SIGNIFICANCE: Either mechanical retention or air abrasion is recommended prior to repairing an existing composite restoration to achieve the highest bond strength.

In vivo evaluation of DIAGNOdent for the quantification of occlusal dental caries.

The accurate diagnosis of non-cavitated occlusal caries is generally considered problematic. Induced fluorescence quantified by the DIAGNOdent device (KaVo) gives a reading from 0-99, which may help in the caries diagnostic process. There is some controversy around the implication of increased severity of decay with increased DIAGNOdent readings. This in vivo study assessed the correlation of depth and volume of decay as it was removed by traditional rotary handpieces with DIAGNOdent readings and determined sensitivities/specificities of the device at different cut-off points. Included in the current study were 31 patients providing 60 permanent molar and premolar occlusal surfaces suspected of dentinal decay. DIAGNOdent readings were recorded, along with lesion depth (as measured by periodontal probe) and volume measurements (as calculated from measuring the mass of a polyvinyl siloxane impression of the cavity, divided by the material's calculated density). Clinical detection of decay at the DEJ was used as the gold-standard to calculate an appropriate cut-off. Pearson correlation coefficients indicated that DIAGNOdent readings were weakly correlated with lesion depth (r = 0.47) and lesion volume (also r = 0.47). An appropriate cut-off point for the sample in the current study was calculated between 35 and 40; a more specific cut-off point could not be determined due to the sample size distribution. It was concluded that the DIAGNOdent device should be used as an adjunct in the caries diagnosis and treatment planning process.

The effect of post type and length on the fracture resistance of endodontically treated teeth.

STATEMENT OF PROBLEM: Few studies have been conducted to determine a correlation between the flexural modulus of metal and fiber-reinforced posts and the fracture resistance and failure mode of teeth restored with posts. Questions remain as to whether a longer post length or a post with a higher flexural modulus will significantly improve the fracture resistance of a tooth restored with a prefabricated post and core. PURPOSE: The purpose of this study was to compare the fracture resistance and mode of failure of endodontically treated teeth restored with 3 different post systems, including 2 fiber-reinforced posts (Light-Post and Snowlight) and a stainless steel post (ParaPost XP). MATERIAL AND METHODS: Seventy single-rooted premolars were sectioned at the cemento-enamel junction and then endodontically treated. Teeth were distributed into 7 groups. Three different prefabricated posts were cemented into a post space either 5 or 10 mm in depth, and composite resin (ParaPost ParaCore automix) cores were fabricated. A composite resin core group without a post served as a negative control. Specimens were loaded at 90 degrees to the longitudinal axis until ultimate failure occurred. An initial failure load and mode of failure were also recorded. Statistical analysis was performed for initial and ultimate failure loads of groups by using 2-way ANOVA (P=.05). RESULTS: The groups with ParaPost XP posts demonstrated significantly higher initial and ultimate mean failure loads when compared with the fiber-reinforced post groups. The highest mean (SD) initial failure load was with the ParaPost XP group with a 10-mm post length (170.05 (60.08) N), and the lowest was with the Snowlight group with the 5-mm post length (62.85 (18.47) N). CONCLUSIONS: The stiffness and the load to initial fracture of the teeth restored with ParaPost XP posts were higher compared with the fiber-reinforced post groups.

Estimation of clinical axial extension of Class II caries lesions with ultraspeed and digital radiographs: an in-vivo study.

This study compared the newly introduced direct digital radiographic (DDR) system (RVG-6000) with conventional bitewing radiographs (D-speed film) to estimate the extension of Class II caries lesions. The patient's discomfort related to placement of each radiographic packet was also evaluated. Fifty-one Class II caries lesions were selected. Affected teeth were radiographed with D-speed film and t he RVG-6000 size 2sensor. Patients were asked to complete a one-page questionnaire regarding discomfort during the radiographic examination. The true caries depth was validated clinically from intra-operative photographs that captured the cross-sectional views of the lesion at its deepest point. During the operative procedures, the cavitation status was also recorded. A reference device was placed on the occlusal surface of the treatment or the adjacent tooth before taking radiographs and during the operative procedure. The caries lesion extension from the dentino-enamel junction (DEJ) was measured in mm on eachradiograph and the results were compared to the true clinical depth. Both radiographs significantly underestimated the clinical depth (p < 0.0001), but the RVG-6000 images were significantly closer to the actual depth of the lesion than the D-speed film (p = 0.0031). All of the lesions which were diagnosed radiographically to be deeper than 1 mm into dentin were cavitated. Size, sharp edges of the sensor or both comprised the source(s) of most of the discomfort caused by D-speed film (64%) and RVG-6000 sensor (79%). The results of this study showed that both types of radiographic images tend to underestimate caries depth; however, the RVG-6000 image was more accurate than the D-speed film. This study also provides information about sources of the patient's discomfort associated with these radiographs.

The correlation of DIFOTI to clinical and radiographic images in Class II carious lesions.

BACKGROUND: The authors conducted a study to evaluate the correlation between digital imaging fiber-optic transillumination (DIFOTI) (KaVo Dental, Lake Zurich, Ill.) and clinical and radiographic images in estimating the true clinical axial extension of Class II carious lesions. METHODS: The authors examined 51 Class II carious lesions visually, imaged them by means of DIFOTI and radiographed them with D-speed film and a complementary metal oxide silicon (CMOS)-based digital radiographic sensor. They validated axial extension of the lesions clinically. They compared the clinical and radiographic depths of the carious lesion with the size of the lesion on the DIFOTI images. RESULTS: The authors detected 84 percent of the lesions with DIFOTI, and 82 percent showed a visible dark shadow under the marginal ridge when examined clinically. DIFOTI correlated significantly with the clinical depth of decay (Pearson r = 0.43189). The combination of a CMOS digital sensor and DIFOTI (R2 = 0.7210) provided readings closer to the clinical measures than did the combination of D-speed film and DIFOTI (R2 = 0.6215). CONCLUSIONS: DIFOTI images correlated with clinical depth, especially in smaller lesions, and improved the estimation of lesion size when used in conjunction with the CMOS digital sensor and D-speed images. CLINICAL IMPLICATIONS: Using radiographs in combination with DIFOTI images could help clinicians determine the presence and, to some extent, the size of proximal caries, especially in smaller lesions.

Finishing systems on the final surface roughness of composites.

AIM: This study evaluated differences in surface roughness of a microhybrid (Gradia Direct, GC America) and a nanofil (Filtek Supreme, 3M ESPE) composite using four polishing systems: PoGo/Enhance (DENTSPLY/Caulk), Sof-Lex (3M ESPE), Astropol (Ivoclar Vivadent), and Optidisc (KerrHawe). METHODS AND MATERIALS: An aluminum mold was used to prepare 2 X 60 composite disks (10 mm X 2 mm). Composite was packed into the mold, placed between two glass slabs, and polymerized for 40 seconds from the top and bottom surfaces. Specimens were finished to a standard rough surface using Moore's disks with six brushing strokes. Specimens were rinsed and stored in artificial saliva in individual plastic bags at 36 degrees C for 24 hours prior to testing. Specimens were randomly assigned to one of the four polishing systems and were polished for 30 seconds (10 seconds per grit) with brushing strokes according to the manufacturer's instructions. Mean surface roughness (Ra) was recorded with a surface-analyzer 24 hours after storage in artificial saliva, both before and after polishing. Means were analyzed using two-way and one-way analysis of variance (ANOVA) and Tukey multiple comparison tests at p < 0.05. RESULTS: There was a statistically significant difference for baseline measures between Filtek and Gradia (p=0.0338). For Filtek, Sof-Lex provided a significantly smoother surface (Ra=0.80 +/- 0.21) than Optidisc (Ra=0.93 +/- 0.28), Astropol (Ra=1.15 +/- 0.24), and Pogo/Enhance (Ra=1.39 +/- 0.39). For Gradia, Sof-Lex provided a significantly smoother surface (Ra=0.47 +/- 0.09) and Astropol provided a significantly rougher surface (Ra=1.39 +/- 0.19) than Pogo/Enhance (Ra=1.11 +/- 0.20) and Optidisc (Ra=1.15 +/- 0.18). There was no significant difference in roughness between composites for individual polishing systems (p=0.3991). CONCLUSION: Filtek specimens were smoother than Gradia specimens after baseline roughening. Sof-Lex provided the smoothest final surface when used with either composite. Astropol provided a rough surface for Gradia specimens.