Markus Zaruba

Erosion-inhibiting potential of a stannous chloride-containing fluoride solution under acid flow conditions in vitro

OBJECTIVES This study aimed to analyse the erosion-inhibiting potential of a single application of stannous chloride-containing fluoride solution on pellicle-covered enamel and dentine under constant acid flow conditions in vitro. DESIGN Bovine enamel (n=60) and dentine (n=60) samples were exposed 1h to the oral cavity of 4 healthy volunteers to allow for in situ pellicle formation. Pellicle-covered samples were randomly assigned to three groups (each n=20 enamel and n=20 dentine samples; 5 enamel and 5 dentine samples/volunteer) and treated once with a SnCl2/AmF/NaF (800 ppm Sn(II), 500 ppm F, pH 4.5) or a NaF solution (500 ppm F, pH 4.5) for 2 min or remained untreated (controls). Samples were eroded with hydrochloric acid (pH 2.6) in a small erosion chamber at 60 microl/min for 25 min. Calcium release into the acid was monitored in consecutive 30s intervals for 5 min, then at 1 min intervals up to a total erosion time of 25 min using the Arsenazo III procedure. Data were statistically analysed by random-effects linear models (p<0.05). RESULTS The stannous chloride-containing fluoride solution reduced calcium loss of enamel and dentine to up to 6 min and 3.5 min, respectively. Calcium loss (% of control) amounted from 24+/-7 (30s) up to 93+/-14 (6 min) in enamel and from 38+/-13 (30s) to 87+/-15 (3.5 min) in dentine. The sodium fluoride solution was unable to reduce enamel and dentine erosion at any time point. CONCLUSION A single application of a stannous chloride-containing fluoride solution reduced enamel and dentine erosion up to 6 min and 3.5 min of constant acid flow, respectively.

Effect of Different Matrix Metalloproteinase Inhibitors on Microtensile Bond Strength of an Etch-and-Rinse and a Self-etching Adhesive to Dentin

AIM This study aimed to analyze the effect of different matrix metalloproteinase (MMP) inhibitors on the microtensile bond strength (microTBS) of an etch-and-rinse and a self-etching adhesive after 9 months of aging. METHODS AND MATERIALS Flat human dentin surfaces were bonded either with an etch-and-rinse adhesive (Optibond FL) or a self-etching adhesive (Clearfil SE Bond). Dentin surfaces were left untreated or were pretreated with MMP inhibitors (2% chlorhexidine digluconate [CHX], 0.05% green tea extract, 1 mM ferrous sulfate, or 0.2 mM galardin) prior to application of the adhesive. Composite buildups were made incrementally. Pretreated groups were tested after 9 months of storage in artificial saliva (37°C) and compared with untreated groups, which were tested immediately (initial microTBS) and upon aging (9-month microTBS). Data were analyzed by linear mixed-model regression. Failure mode analysis was performed microscopically and statistically analyzed by repeated-measures analysis of variance (p<0.05). RESULTS MicroTBS of the etch-and-rinse adhesive but not of the self-etching adhesive was significantly decreased by aging. For Optibond FL, pretreatment with 2% CHX, 0.05% green tea extract, and 0.2 mM galardin revealed bond strength values (MPa) similar to the initial microTBS (32.1±14.8) and significantly higher compared with the microTBS (20.3±13.6) of aged untreated dentin. No significant differences were observed between groups bonded with Clearfil SE Bond (initial microTBS: 28.3±12.4; 9-month microTBS: 25.3±11.8). Application of the MMP inhibitors decreased the number of adhesive failures compared with untreated controls after 9 months of aging, but this effect was not significant. CONCLUSION The MMP inhibitors prevented the decrease in microTBS upon aging of the etch-and-rinse but not of the self-etching adhesive.

Influence of a proximal margin elevation technique on marginal adaptation of ceramic inlays

PURPOSE Evaluating the effect of a proximal margin elevation technique on marginal adaptation of ceramic inlays. METHODS Class II MOD-cavities were prepared in 40 human molars and randomly distributed to four groups (n = 10). In group EN (positive control) proximal margins were located in enamel, 1 mm above the cementoenamel junction, while 2 mm below in groups DE-1In, DE-2In and DE. The groups DE-1In, DE-2In and DE simulated subgingival location of the cervical margin. In group DE-1In one 3 mm and in group DE-2In two 1.5 mm composite layers (Tetric) were placed for margin elevation of the proximal cavities using Syntac classic as an adhesive. The proximal cavities of group DE remained untreated and served as a negative control. In all groups, ceramic inlays (Cerec 3D) were adhesively inserted. Replicas were taken before and after thermomechanical loading (1.200.000 cycles, 50/5°C, max. load 49 N). Marginal integrity (tooth-composite, composite-inlay) was evaluated with scanning electron microscopy (200×). Percentage of continuous margin (% of total proximal margin length) was compared between groups before and after cycling using ANOVA and Scheffé post-hoc test. RESULTS After thermomechanical loading, no significant differences were observed between the different groups with respect to the interface composite-inlay and tooth-composite with margins in dentin. The interface tooth-composite in enamel of group EN was significantly better compared to group DE-2In, which was not different to the negative control group DE and DE-1In. CONCLUSION Margin elevation technique by placement of a composite filling in the proximal box before insertion of a ceramic inlay results in marginal integrities not different from margins of ceramic inlays placed in dentin.

Influence of material thickness on fractural strength of CAD/CAM fabricated ceramic crowns

The fracture behavior of CAD/CAM fabricated crowns was investigated as a function of material thickness for six silicate ceramic materials: Mark II, e.max CAD, Celtra Duo milled, Celtra Duo fired, Suprinity, Enamic. Crowns with thicknesses 0.5/1.0/1.5 mm were fabricated with CEREC and adhesively seated to dies fabricated with stereolithography technology (n=144). Thermomechanical loading and fractural loading was performed. Statistical analysis was done with one-way ANOVA and post-hoc Scheffé test. For 1.5 mm, all crowns survived fatigue testing, for 1.0 mm, survival was 100% only for materials e.max CAD and Suprinity. For 0.5 mm, best survival rate was 37.5% for Suprinity. Maximum fractural loading significantly varied among the groups. For 0.5 mm, highest value was found for Suprinity (660.1 N). Mark II showed lowest values for 1.0 mm (482.0 N), and 1.5 mm groups (634.8 N). e.max CAD showed highest values for 1.0 mm (774.2 N), and 1.5 mm groups (1,240.8 N).

Comparison between different flow application techniques: SDR vs flowable composite.

PURPOSE To evaluate the effect of layer thickness of flowable composites on the marginal adaptation of Class II fillings after thermomechanical loading (TML). MATERIALS AND METHODS Sixty standardized Class II box cavities were prepared under simulation of intrapulpal pressure with gingival margins located 1 mm below the cementoenamel junction (CEJ) in dentin. The samples were evenly distributed into six groups (A to F). After adhesive (XPBond) application, box preparations were filled with a first increment of either a nanohybrid composite (A, D) Ceram.X mono, or with one of two flowable materials SDR (B, E) or x-Flow (C, F). The first increments were 1 (A,B,C) or 4 mm (D,E,F) thick. All cavities were finally filled incrementally with Ceram.X mono. Replicas were prepared before and after TML (1.2 x 106 cycles; 5/50°C; maximum load 49 N). Replicas were evaluated for marginal adaptation (tooth/composite) using scanning electron microscopy (200X). The percentage of continuous margins was compared between and within groups before and after TML using ANOVA and Scheffés post-hoc tests. RESULTS For group F before TML, adaptation of cervical margins located in dentin was compromised compared to the other groups (p < 0.05). After TML, at the same location, group F showed significantly worse adaptation compared with groups A to C and E (p < 0.05), but no difference to group D was found. The marginal integrity of all interfaces before and after TML was significantly worse in group F compared with all other groups (p < 0.05). CONCLUSION Different flow application techniques for Class II cavities have an influence on the marginal adaptation (before/after TML). Applying a 4-mm first increment, both Ceram.X mono and SDR showed no differences vs groups in which the first increment was 1 mm thick.

Intracanal Antibiotic Medication for Sustained Root Surface Disinfection–A Laboratory Evaluation

Purpose: To measure the release of an antibiotic mixture of ciprofloxacin, cerfuroxim and metronidazole (TreVitaMix, TVM) through human dentine and to assess the growth inhibition of Fusobacterium nucleatum. Material and Methods: Twenty-four extracted human incisors were scaled and endodontically treated. Root canals were either filled with antibiotic tri-mixture (TVM) or with the carrier material alone (propylene glycol, PG) and were coronally and apically sealed with a flowable composite. Transradicular medicament release was spectrophotometrically measured at 277 nm in simulated body fluid for up to 21 days. In a second part, an agar diffusion assay (F. nucleatum) with representative TVM concentrations as determined in the first part was performed to study the growth inhibition. Samples were anaerobical incubated for 48 h and inhibition zones were measured. Results: TVM was spectrophotometrically detectable in the immersion solution and released in decreasing concentrations up to 21 days (222.5 ± 65.2 mg/ml at day 1 and 35.1 ± 15.6 mg/ml at day 21). In addition, inhibition zones were shown in the agar diffusion assay at representative TVM concentrations. The carrier material showed no antibacterial effect. Conlusion: TVM showed the potential to penetrate through dentine and to inhibit bacterial growth. Therefore, it might have the potential to disinfect the outer root surface in perio-endo lesions, but further research is needed to confirm these observations.