The comparison of the repair bond strength of the composite resin to direct and indirect composite restorations with different surface preparations.

Background: Indirect restorations have been employed in restorative dentistry to solve some of the drawbacks of direct restorations. The aim of this study was to evaluate the effect of different modes of a universal adhesive resin on the repair capacity of two indirect resin composites and a direct resin composite. Methods: Indirect composite resins (Ceramage and Gradia Plus) and a direct composite resin (Filtek Z250) were prepared in a plastic mold with a height and diameter of 2-mm and 6-mm, respectively. Composite blocks were thermocycled (5000 cycles, 5°C-55°C). Then, according to their surface treatments, composite blocks were categorized into six-groups: Group 1: ER (etch&rinse), Group 2: SE (self-etch), Group 3: Bur+ER (bur+etch&rinse), Group 4: Bur+SE (bur+self-etch), Group 5: Bur+Silane+ER (bur+silane+etch&rinse), Group 6: Bur+Silane+SE (bur+silane+self-etch), respectively. After surface treatments and adhesive application for bonding with a direct resin composite, all groups were then thermocycled before performing shear-bond-strength-test. Failure modes were evaluated using a stereomicroscope. Data were analyzed by two-way-ANOVA and Bonferroni-test (P<0.05). Results: The highest bond-strength values were obtained for Bur+Silane+SE groups, while the lowest values were obtained for the Bur+Silane+ER groups for all materials. Statistically significant differences were observed between the Bur+Silane+ER group and ER, Bur+ER and Bur+Silane+SE groups in Gradia Plus (P<0.05). Conclusion: The self-etch-mode of the universal-adhesive and silane applications led to the increase in the repair-strength of the adhesive in the Filtek Z250 and Ceramage. The self-etch-mode of the universal-adhesive might be used to reduce adhesive-application-steps in the clinical repair procedures.

Influence of operator experience on bond strength of different adhesives to dentin.

AIM: Application of adhesive systems on dentin is a multistep, technique-sensitive procedure. Thus, the aim was to assess the effect of operator experience on the shear bond strength of an etch-and-rinse adhesive system and a self-etch adhesive system on dentin. MATERIALS AND METHODS: Forty-eight extracted human molar teeth were used in the study. They were embedded in an acrylic resin after cutting off the roots. The mesial and distal enamels of the teeth were removed to expose dentin surfaces. The samples were allocated to four groups (n = 12): Group 1: restorative dentistry specialist with 13 years of experience, Group 2: with 6 years of experience, Group 3: postgraduate operator with 2 years of experience, and Group 4: undergraduate student with 1 year of experience and familiar with adhesive with systems. Each operator applied an etch-and-rinse adhesive system (Adper Single Bond 2) to mesial surface and a self-etch adhesive system (Clearfil SE Bond) to distal surface (n = 12). Then, a composite resin (Filtek Z250) was inserted with the aid of a plastic ring (2 mm × 2 mm) and light polymerized. The specimens were stored in distilled water before shear bond strength test. A two-way ANOVA test was used for statistical analysis. RESULTS: No statistically significant difference was found between each operator type with respect to etch-and-rinse adhesive system (P > 0.05); however, the undergraduate student performed better than 2-year experienced operator with respect to self-etch system application (P < 0.05). CONCLUSION: The shear bond strength of a self-etch system might vary according to the operator's experience.

Effects of staining and bleaching on a nanohybrid composite with or without surface sealant.

OBJECTIVE: The effect of different staining solutions and a bleaching procedure on color stability and surface roughness of a nanohybrid resin composite were evaluated with or without liquid resin polishing (RP). MATERIALS AND METHODS: Ninety-six disc-shaped resin composite specimens (A1 Shade, Z550 Filtek 3M ESPE, St. Paul, MN, USA) were prepared and divided randomly into two groups (n = 48). Liquid RP (BisCover LV, Bisco Inc., Schaumburg, IL, USA) was applied in one group (RP) and not in the other (P). Specimen color and surface roughness were determined using a colorimeter and profilometer, respectively. After baseline measurements, each group was divided into four subgroups (n = 12) for immersion in a control (distilled water) or three different staining solutions (ice tea, red wine, and cola) for 1 week. Color and surface roughness were then reevaluated. After measurements, all specimens were bleached using a 35% hydrogen peroxide gel. The color and surface roughness of the specimens were reevaluated. STATISTICAL ANALYSIS: Data were subjected to an analysis of variance for repeated measurements among the groups (P < 0.05). RESULTS: Staining and bleaching did not change the surface roughness of the RP and P groups (P > 0.05). Discoloration in the red wine group was higher than for the other staining solutions for the RP (P < 0.001) and P groups (P = 0.018). CONCLUSION: Application of liquid RP did not enhance the color stability and surface roughness of the composite resin restoration.

Dental students' ability to assess their performance in a preclinical restorative course: comparison of students' and faculty members' assessments.

Dental education consists of both theoretical and practical learning for students to develop competence in treating patients clinically. When dental students encounter practical courses in their first year as a new educational experience, they must also learn to evaluate themselves. Self-evaluation is an essential skill to learn for dental professionals to keep increasing their competence over the course of their careers. The aim of this study was to compare the assessment scores of second- and third-year dental students and the faculty in two consecutive preclinical practical exams in restorative dentistry courses in a dental school in Turkey. Faculty- and student-assigned scores were calculated from two consecutive preclinical examinations on tooth restorations performed on both artificial casts and phantom patients. The students were formally instructed on grading procedures for tooth preparations, base and restoration placement, and polishing criteria. After each step, each item was assessed by faculty members, the student, and another student. The results indicated that the initial differences between second-year students' assessments of their own preclinical practical ability and that of the faculty decreased among the third-year students. Self-evaluation scores did not indicate whether the third-year students tended to over- or underestimate the quality of their own work. However, the second-year students not only overestimated themselves but thought they were above average. The results point to the need to develop students' self-insight with more exercises and practical training.

Effect of chewing gums with xylitol, sorbitol and xylitol-sorbitol on the remineralization and hardness of initial enamel lesions in situ.

BACKGROUND: The purpose of this study was to determine the effect of three chewing gums and paraffin on the remineralization and the hardness of demineralized enamel. MATERIALS AND METHODS: A total of 12 subjects wore intraoral palatal appliances with two demineralized bovine enamel slabs. The study consisted of four experimental periods each lasting 21-days, during which subjects were assigned to one of three gum-chewing regimens: gum containing sorbitol, xylitol and a mixture of sorbitol and xylitol and with paraffin as control. The appliances were worn during gum-chewing for 20 min and then retained for 20 min 4 times/day. The slabs were subjected to energy dispersive X-ray spectroscopy analysis and surface microhardness measurements before in setting into the appliance and after the experimental period. The data were subjected to analysis of variance for repeated measures. A P < 0.05 was considered statistically significant. RESULTS: Mineral analysis revealed no significant difference between the baseline and after chewing periods for all groups (P > 0.05). No significant difference was found among the groups either for the baseline measurements or after chewing periods (P > 0.05). All groups showed higher microhardness values after the chewing periods than the baseline except for the Vivident Xylit group (P < 0.05). CONCLUSION: The chewing of gum had no effect on the Ca/P ratio of demineralized enamel surfaces. The hardening of the demineralized enamel surfaces may vary according to the type of chewing gum.

Influence of different staining beverages on color stability, surface roughness and microhardness of silorane and methacrylate-based composite resins.

AIM: To investigate the influence of different staining beverages on color stability, surface roughness and microhardness of silorane and methacrylate-based composite resins. MATERIALS AND METHODS: Three different composite resins (Filtek Silorane, Filtek P60, Filtek Supreme XT) were tested. Thirty cylindrical specimens (10 × 2 mm) per material were prepared and polished with a series of aluminum-oxide polishing disks. Each group was then randomly subdivided into three groups according to the test beverages: distilled water (control), cola and coffee. The samples were immersed into different beverages for 15 days. Color, surface roughness and microhardness values were measured by a spectrophotometer, prophylometer and Vickers hardness device respectively, at baseline and after 15 days. The data were subjected to statistical analysis. RESULTS: Immersion in coffee resulted in a significant discoloration for all the composites tested, although the color change was lower in Filtek Silorane than that of MBCs (p < 0.05). All the composites tested showed similar surface roughness changes after immersion in different beverages (p > 0.05). Besides coffee caused more roughness change than others. Immersion in coffee caused highest microhardness change in Filtek Supreme XT (p < 0.05). CONCLUSION: Cola and coffee altered, to some degree, the color, surface roughness and/or microhardness of the tested resin composites, depending on the characteristics of the materials.

1 year clinical evaluation of microhybrid composites used in the restoration of non-carious cervical lesions.

AIM: Microhybrid composite resins are commonly used to treat non-carious cervical lesions. The aim of this double blind study was to compare the 12-month clinical performance of cervical restorations placed with the use of two different microhybrid composite resins. METHODS: 20 patients with at least one pair of non-carious cervical lesion participated in this study. Ninety-seven cervical lesions were restored with either TPH Spectrum (n=48) or Filtek Z250 (n=49) using a two-step etch &rinse adhesive (Single Bond 2) Restorations were evaluated using modified USPHS criteria after 6 and 12 months. The statistical comparison of resin composites for each category was performed with the Pearson chi square test and the performance of restorations at the baseline, 6 months and after 12 month recall time was evaluated by Mc Nemar's test (p<0.05). RESULTS: The recall rate of the patients was 100% at each evaluation period. The retention rates were 100% at six months,89,6% and 91,8% at 12-months for TPH and Z250, respectively and no statistically significant difference was observed with respect to each evaluation criteria (p>0.05). CONCLUSION: Cervical restorations placed with two different microhybrid composites and a two-step etches and rinse system showed satisfactory clinical performance after 12-months.

The effect of dentin desensitizers and Nd:YAG laser pre-treatment on microtensile bond strength of self-adhesive resin cement to dentin.

PURPOSE: The purpose of this study is to evaluate if pre-treatment with desensitizers have a negative effect on microtensile bond strength before cementing a restoration using recently introduced self-adhesive resin cement to dentin. MATERIALS AND METHODS: Thirty-five human molars' occlusal surfaces were ground to expose dentin; and were randomly grouped as (n=5); 1) Gluma-(Glutaraldehyde/HEMA) 2) Aqua-Prep F-(Fluoride), 3) Bisblock-(Oxalate), 4) Cervitec Plus-(Clorhexidine), 5) Smart protect-(Triclosan), 6) Nd:YAG laser, 7) No treatment (control). After applying the selected agent, RelyX U200 self-adhesive resin cement was used to bond composite resin blocks to dentin. All groups were subjected to thermocycling for 1000 cycles between 5-55℃. Each bonded specimen was sectioned to microbars (6 mm × 1 mm × 1 mm) (n=20). Specimens were submitted to microtensile bond strength test at a crosshead speed of 0.5 mm/min. Kolmogorov-Smirnov, Levene's test, Kruskal-Wallis One-way Analysis of Variance, and Conover's nonparametric statistical analysis were used (P<.05). RESULTS: Gluma, Smart Protect and Nd:YAG laser treatments showed comparable microtensile bond strengths compared with the control group (P>.05). The microtensile bond strengths of Aqua-Prep F, and Cervitec Plus were similar to each other but significantly lower than the control group (P<.05). Bisblock showed the lowest microtensile bond strength among all groups (P<.001). Most groups showed adhesive failure. CONCLUSION: Within the limitation of this study, it is not recommended to use Aqua-prep F, Cervitec Plus and Bisblock on dentin when used with a self-adhesive resin cement due to the decrease they cause in bond strength. Beside, pre-treatment of dentin with Gluma, Smart protect, and Nd:YAG laser do not have a negative effect.

Effect of haemostatic agent application on the shear bond strength of contemporary/multi-mode adhesive systems.

OBJECTIVES: The aim was to determine the effect of blood contamination and haemostatic agent application on the shear bond strength (SBS) of different adhesives to dentin. MATERIALS AND METHODS: Seventy-two extracted human molars were used in this study. Teeth were mounted acrylic in moulds. Mesial and distal surfaces were removed to obtain flat dentin surfaces (n=144) and grinded with a 600 grit sandpaper. The samples were randomly divided into three main groups (N=48) based on the adhesive system and application procedures. GROUP 1: No contamination (control), GROUP 2: Blood contamination, GROUP 3: Blood Contamination+Haemostatic agent application. Each group was further divided into four subgroups: SUBGROUP I: Single Bond 2 (etch-and-rinse) Subgroup II: Clearfil SE Bond (two-step self-etch) Subgroup III: Single Bond Universal (multimode, etch-and-rinse) subgroup IV: Single Bond Universal (multimode, all-in-one self-etch) (n=12). Resin cylinders (Filtek Z550) were bonded to the dentin surfaces according to the manufacturers' instructions. A shear load was applied to the specimens using universal testing machine at a cross-head speed of 0.5 mm/min until failure. Data were analyzed statistically (p<0.05). RESULTS: Statistically significant differences were observed between no contamination (control) and blood + haemostatic agent contamination groups for both Single Bond 2 (etch-and-rinse) and Single Bond Universal (multimode, all-in-one self-etch) (p<0.05). When the adhesive systems were compared to each other, no statistically significant differences were found in all contamination groups and control group for the mean SBS values (p>0.05). CONCLUSION: When blood contamination is inevitable two step self- etching adhesive systems may be the choice of adhesive system in terms of shear bond strength.

Does the temperature of beverages affect the surface roughness, hardness, and color stability of a composite resin?

OBJECTIVE: To investigate the effect of beverages' temperature on the surface roughness, hardness, and color stability of a composite resin. MATERIALS AND METHODS: Fifty specimens of the Filtek Z250 composite (3M ESPE, Dental Products, St.Paul, MN, USA) were prepared and initial roughness, microhardness, and color were measured. Then the specimens were randomly divided into five groups of 10 specimens each: Coffee at 70°C, coffee at 37°C, cola at 10°C, cola at 37°C, and artificial saliva (control). After the samples were subjected to 15 min × 3 cycles per day of exposure to the solutions for 30 days, the final measurements were recorded. RESULTS: After immersion in beverages, the artificial saliva group showed hardness values higher than those of the other groups (P < 0.001) and the microhardness values were significantly different from the initial values in all groups except for the control group. Both cola groups showed roughness values higher than the baseline values (P < 0.05), while the other groups showed values similar to the baseline measurements. When ΔE measurements were examined, the 70°C coffee group showed the highest color change among all the groups (P < 0.05). CONCLUSION: High-temperature solutions caused alterations in certain properties of composites, such as increased color change, although they did not affect the hardness or roughness of the composite resin material tested.

Effect of prerestorative home-bleaching on microleakage of self-etch adhesives.

BACKGROUND: Tooth bleaching has become a routine treatment due to patients' esthetic demands. PURPOSE: The aim of this study was to evaluate how prerestorative home-bleaching affected microleakage of resin composite restorations bonded with etch-and-rinse and self-etch adhesives. MATERIALS AND METHODS: Fifty extracted human premolar teeth were used. The bleaching agent (10% carbamide peroxide) was applied to the buccal surface of each tooth for 6 hours a day for 2 weeks. The lingual surfaces of the same teeth received no application (control). The teeth were stored in artificial saliva. After 14 days, standardized Class V cavity preparations (2 mm high, 3 mm wide, and 2 mm deep) were made on the buccal and lingual surfaces with all margins in the enamel. They were randomly divided into five groups according to the adhesive systems: an etch-and-rinse adhesive (Single Bond [SB]), two two-step self-etch adhesives (Adper SE Plus [ASE] and One Coat [OC]), and two one-step self-etch adhesives (Adper Easy One [EO] and G-Bond [GB]). All adhesives were applied according to the manufacturers' instructions. The preparations were then restored using the same hybrid composite (Filtek Z250) in one increment and light-cured. The teeth were thermocycled (5/55 degrees C, 1,000x) and immersed in dye, then sectioned, and dye penetration was scored. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: Although statistically significant differences were found between the adhesive systems in the bleached teeth, no differences were observed in the control groups (non-bleached teeth). There were significant differences between SB/GB, SB/EO, SB/OC, and GB/ASE in the bleached teeth (p < 0.05). When comparing bleached and non-bleached teeth within each adhesive system, only SB and EO produced higher leakage scores when bleaching was applied. The other groups showed no difference in terms of bleaching (p > 0.05). CONCLUSION: Prerestorative home-bleaching had an adverse effect on microleakage of SB and EO. CLINICAL SIGNIFICANCE: The effect of prerestorative home-bleaching agents on microleakage of composite resin restorations differs according to the type of adhesive material used.

Effects of delayed finishing/polishing on surface roughness, hardness and gloss of tooth-coloured restorative materials.

OBJECTIVES: The aim of this study was to investigate the effect of delayed finishing/polishing on the surface roughness, hardness and gloss of tooth-coloured restorative materials. METHODS: Four different tooth-coloured restoratives: a flowable resin composite- Tetric Flow, a hybrid resin composite- Venus, a nanohybrid resin composite- Grandio, and a polyacid modified resin composite- Dyract Extra were used. 30 specimens were made for each material and randomly assigned into three groups. The first group was finished/polished immediately and the second group was finished/polished after 24 hours. The remaining 10 specimens served as control. The surface roughness of each sample was recorded using a laser profilometer. Gloss measurements were performed using a small-area glossmeter. Vickers microhardness measurements were performed from three locations on each specimen surface under 100g load and 10s dwell time. Data for surface roughness and hardness were analyzed by Kruskal Wallis test and data for gloss were subjected to one-way ANOVA and Tukey test (P <.05). RESULTS: The smoothest surfaces were obtained under Mylar strip for all materials. While there were no significant differences in surface roughness of immediate and delayed finished/polished Dyract Extra samples, immediately finished/polished Venus and Grandio samples showed significantly higher roughness than the delayed polished samples (P <.05). In Tetric Flow samples, immediately finishing/polishing provided smoother surface than delayed finishing/polishing (P <.05). The highest gloss values were recorded under Mylar strip for all materials. While delayed finishing/polishing resulted in a significantly higher gloss compared to immediate finishing/polishing in Venus samples (P <.05), no differences were observed between delayed or immediate finishing/polishing for the other materials (P>.05). The lowest hardness values were found under Mylar strip. Delayed finishing/polishing significantly increased the hardness of all materials. CONCLUSIONS: The effect of delayed finishing/polishing on surface roughness, gloss and hardness appears to be material dependent.

Clinical evaluation of a nanofilled fissure sealant placed with different adhesive systems: 24-month results.

OBJECTIVE: This clinical study compared the retention rates of a nanofilled occlusal fissure sealant placed with the use of an etch-and-rinse or a self-etch adhesive over 24 months. METHODS: Two-hundred and forty-four sealants were placed on the permanent premolars and molars of 16 subjects who had no restorations or sealants present on the fissures and no detectable caries. The sealants were placed with either SoloBond M two-step etch-and-rinse adhesive or FuturaBond NR one-step self-etch adhesive by four previously calibrated dentists, using a table of random numbers. After completion of the adhesive application, a nanofilled sealant, Grandio Seal, was applied and light-cured. Clinical evaluations were done at baseline and at 1-, 3-, 6-, 12-, 18- and 24-month recalls. Two other calibrated examiners, who were unaware of which adhesive had been used, independently evaluated the sealants. Evaluation of the sealants on every follow-up visit involved visual examination with the aid of a dental explorer and an intra-oral mirror. Each sealant was evaluated with the following criteria: 1 = completely retained; 2 = partial loss; 3 = total loss. The Pearson Chi-square test was used to evaluate differences in the retention rates among the sealants used with different adhesives for each evaluation period. RESULTS: For the 12-month recalls, complete retention rates of 89.3% for the SoloBond M group and 20.5% for the FuturaBond NR group were observed. Sixteen of the 244 restorations were unavailable after 12 months. At 24 months, a total loss of 9 sealants in the SoloBond M group and 84 in the FuturaBond NR group were observed, resulting in retention rates of 81.6% and 15.8%, respectively. There were statistically significant differences in retention rates between the SoloBond M and FuturaBond NR groups in all periods of evaluation (p < 0.05). No statistically significant difference between the retention rates for premolars and molars was found at each evaluation period (p > 0.05). There was no new caries formation throughout the 24-month recall period. CONCLUSION: Fissure sealants placed with etch-and-rinse adhesive showed better retention rates than those placed with self-etch adhesive.

The effect of saliva contamination on microleakage of an etch-and-rinse and a self-etching adhesive.

PURPOSE: To evaluate the effect of saliva contamination on the microleakage of an etch-and-rinse adhesive and a self-etching adhesive. MATERIALS AND METHODS: Class V cavity preparations at the cementoenamel junction were made on the buccal and lingual surfaces of 40 freshly extracted human molars. The teeth were randomly assigned into two groups for different adhesives: Group I, Single Bond (two-step etch-and-rinse adhesive) and Group II, Futura Bond NR (one-step self-etching adhesive). The adhesive materials were applied according to their manufacturers' recommendations. The specimens were then further subdivided into five subgroups (A-E; n = 8): group A, contamination before adhesive curing; group B, contamination before adhesive curing and re-application of adhesive; group C, contamination after adhesive curing; group D, contamination after adhesive curing and re-application of adhesive; and group E, no contamination (control). Contamination of adhesive surfaces was performed with fresh natural saliva and the saliva was removed by a gentle air blast. The specimens were restored with Z250 hybrid composite. After thermocycling (500x, 5 degrees C to 55 degrees C) and immersion in 0.5% basic fuchsin, the dye penetration was evaluated under a stereomicroscope. Statistical analysis was performed with the Kruskal-Wallis test at p < 0.05. RESULTS: No statistically significant differences were found among the contamination subgroups on the enamel or on the dentin for either group (p > 0.05). There was no significant difference in leakage between Group I and Group II for any subgroup (p > 0.05). CONCLUSION: Contamination of adhesives with saliva before and after adhesive curing did not worsen the microleakage of the two-step etch-and-rinse adhesive Single Bond or the one-step self-etching adhesive Futura Bond NR.

[Thoracopancreatic fistula: imaging findings (case report)]. / Torakopankreatik fistülün görüntüleme bulgulari

Thoracopancreatic fistula is a rare complication of acute and chronic pancreatitis caused by an inflammatory or traumatic injury to the main pancreatic duct or side branches. Rupture of the duct into the pleura, pericardium, and mediastinum may present as a pancreaticopleural fistula, mediastinal pseudocyst, pancreaticobronchial or pancreticopericardial fistula. We present the imaging findings in a rare case of thoracopancreatic fistula caused by recurrent pancreatitis.